// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
 */

#define _GNU_SOURCE /* memmem() */
#include <fnmatch.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <sys/mman.h>

#include <objtool/builtin.h>
#include <objtool/cfi.h>
#include <objtool/arch.h>
#include <objtool/disas.h>
#include <objtool/check.h>
#include <objtool/special.h>
#include <objtool/trace.h>
#include <objtool/warn.h>
#include <objtool/checksum.h>
#include <objtool/util.h>

#include <linux/objtool_types.h>
#include <linux/hashtable.h>
#include <linux/kernel.h>
#include <linux/static_call_types.h>
#include <linux/string.h>

static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;

static struct cfi_init_state initial_func_cfi;
static struct cfi_state init_cfi;
static struct cfi_state func_cfi;
static struct cfi_state force_undefined_cfi;

struct disas_context *objtool_disas_ctx;

size_t sym_name_max_len;

struct instruction *find_insn(struct objtool_file *file,
                              struct section *sec, unsigned long offset)
{
        struct instruction *insn;

        hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
                if (insn->sec == sec && insn->offset == offset)
                        return insn;
        }

        return NULL;
}

struct instruction *next_insn_same_sec(struct objtool_file *file,
                                       struct instruction *insn)
{
        if (insn->idx == INSN_CHUNK_MAX)
                return find_insn(file, insn->sec, insn->offset + insn->len);

        insn++;
        if (!insn->len)
                return NULL;

        return insn;
}

static struct instruction *next_insn_same_func(struct objtool_file *file,
                                               struct instruction *insn)
{
        struct instruction *next = next_insn_same_sec(file, insn);
        struct symbol *func = insn_func(insn);

        if (!func)
                return NULL;

        if (next && insn_func(next) == func)
                return next;

        /* Check if we're already in the subfunction: */
        if (func == func->cfunc)
                return NULL;

        /* Move to the subfunction: */
        return find_insn(file, func->cfunc->sec, func->cfunc->offset);
}

static struct instruction *prev_insn_same_sec(struct objtool_file *file,
                                              struct instruction *insn)
{
        if (insn->idx == 0) {
                if (insn->prev_len)
                        return find_insn(file, insn->sec, insn->offset - insn->prev_len);
                return NULL;
        }

        return insn - 1;
}

static struct instruction *prev_insn_same_sym(struct objtool_file *file,
                                              struct instruction *insn)
{
        struct instruction *prev = prev_insn_same_sec(file, insn);

        if (prev && insn_func(prev) == insn_func(insn))
                return prev;

        return NULL;
}

#define for_each_insn(file, insn)                                       \
        for (struct section *__sec, *__fake = (struct section *)1;      \
             __fake; __fake = NULL)                                     \
                for_each_sec(file->elf, __sec)                          \
                        sec_for_each_insn(file, __sec, insn)

#define func_for_each_insn(file, func, insn)                            \
        for (insn = find_insn(file, func->sec, func->offset);           \
             insn;                                                      \
             insn = next_insn_same_func(file, insn))

#define sym_for_each_insn(file, sym, insn)                              \
        for (insn = find_insn(file, sym->sec, sym->offset);             \
             insn && insn->offset < sym->offset + sym->len;             \
             insn = next_insn_same_sec(file, insn))

#define sym_for_each_insn_continue_reverse(file, sym, insn)             \
        for (insn = prev_insn_same_sec(file, insn);                     \
             insn && insn->offset >= sym->offset;                       \
             insn = prev_insn_same_sec(file, insn))

#define sec_for_each_insn_from(file, insn)                              \
        for (; insn; insn = next_insn_same_sec(file, insn))

#define sec_for_each_insn_continue(file, insn)                          \
        for (insn = next_insn_same_sec(file, insn); insn;               \
             insn = next_insn_same_sec(file, insn))

static inline struct reloc *insn_jump_table(struct instruction *insn)
{
        if (insn->type == INSN_JUMP_DYNAMIC ||
            insn->type == INSN_CALL_DYNAMIC)
                return insn->_jump_table;

        return NULL;
}

static inline unsigned long insn_jump_table_size(struct instruction *insn)
{
        if (insn->type == INSN_JUMP_DYNAMIC ||
            insn->type == INSN_CALL_DYNAMIC)
                return insn->_jump_table_size;

        return 0;
}

static bool is_jump_table_jump(struct instruction *insn)
{
        struct alt_group *alt_group = insn->alt_group;

        if (insn_jump_table(insn))
                return true;

        /* Retpoline alternative for a jump table? */
        return alt_group && alt_group->orig_group &&
               insn_jump_table(alt_group->orig_group->first_insn);
}

static bool is_sibling_call(struct instruction *insn)
{
        /*
         * Assume only STT_FUNC calls have jump-tables.
         */
        if (insn_func(insn)) {
                /* An indirect jump is either a sibling call or a jump to a table. */
                if (insn->type == INSN_JUMP_DYNAMIC)
                        return !is_jump_table_jump(insn);
        }

        /* add_jump_destinations() sets insn_call_dest(insn) for sibling calls. */
        return (is_static_jump(insn) && insn_call_dest(insn));
}

/*
 * Checks if a function is a Rust "noreturn" one.
 */
static bool is_rust_noreturn(const struct symbol *func)
{
        /*
         * If it does not start with "_R", then it is not a Rust symbol.
         */
        if (strncmp(func->name, "_R", 2))
                return false;

        /*
         * These are just heuristics -- we do not control the precise symbol
         * name, due to the crate disambiguators (which depend on the compiler)
         * as well as changes to the source code itself between versions (since
         * these come from the Rust standard library).
         */
        return str_ends_with(func->name, "_4core3num20from_str_radix_panic")                            ||
               str_ends_with(func->name, "_4core3num22from_ascii_radix_panic")                          ||
               str_ends_with(func->name, "_4core5sliceSp15copy_from_slice17len_mismatch_fail")          ||
               str_ends_with(func->name, "_4core6option13expect_failed")                                ||
               str_ends_with(func->name, "_4core6option13unwrap_failed")                                ||
               str_ends_with(func->name, "_4core6result13unwrap_failed")                                ||
               str_ends_with(func->name, "_4core9panicking5panic")                                      ||
               str_ends_with(func->name, "_4core9panicking9panic_fmt")                                  ||
               str_ends_with(func->name, "_4core9panicking14panic_explicit")                            ||
               str_ends_with(func->name, "_4core9panicking14panic_nounwind")                            ||
               str_ends_with(func->name, "_4core9panicking18panic_bounds_check")                        ||
               str_ends_with(func->name, "_4core9panicking18panic_nounwind_fmt")                        ||
               str_ends_with(func->name, "_4core9panicking19assert_failed_inner")                       ||
               str_ends_with(func->name, "_4core9panicking30panic_null_pointer_dereference")            ||
               str_ends_with(func->name, "_4core9panicking36panic_misaligned_pointer_dereference")      ||
               str_ends_with(func->name, "_7___rustc17rust_begin_unwind")                               ||
               strstr(func->name, "_4core9panicking13assert_failed")                                    ||
               strstr(func->name, "_4core9panicking11panic_const24panic_const_")                        ||
               (strstr(func->name, "_4core5slice5index") &&
                strstr(func->name, "slice_") &&
                str_ends_with(func->name, "_fail"));
}

/*
 * This checks to see if the given function is a "noreturn" function.
 *
 * For global functions which are outside the scope of this object file, we
 * have to keep a manual list of them.
 *
 * For local functions, we have to detect them manually by simply looking for
 * the lack of a return instruction.
 */
static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
                                int recursion)
{
        int i;
        struct instruction *insn;
        bool empty = true;

#define NORETURN(func) __stringify(func),
        static const char * const global_noreturns[] = {
#include "noreturns.h"
        };
#undef NORETURN

        if (!func)
                return false;

        if (!is_local_sym(func)) {
                if (is_rust_noreturn(func))
                        return true;

                for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
                        if (!strcmp(func->name, global_noreturns[i]))
                                return true;
        }

        if (is_weak_sym(func))
                return false;

        if (!func->len)
                return false;

        insn = find_insn(file, func->sec, func->offset);
        if (!insn || !insn_func(insn))
                return false;

        func_for_each_insn(file, func, insn) {
                empty = false;

                if (insn->type == INSN_RETURN)
                        return false;
        }

        if (empty)
                return false;

        /*
         * A function can have a sibling call instead of a return.  In that
         * case, the function's dead-end status depends on whether the target
         * of the sibling call returns.
         */
        func_for_each_insn(file, func, insn) {
                if (is_sibling_call(insn)) {
                        struct instruction *dest = insn->jump_dest;

                        if (!dest)
                                /* sibling call to another file */
                                return false;

                        /* local sibling call */
                        if (recursion == 5) {
                                /*
                                 * Infinite recursion: two functions have
                                 * sibling calls to each other.  This is a very
                                 * rare case.  It means they aren't dead ends.
                                 */
                                return false;
                        }

                        return __dead_end_function(file, insn_func(dest), recursion+1);
                }
        }

        return true;
}

static bool dead_end_function(struct objtool_file *file, struct symbol *func)
{
        return __dead_end_function(file, func, 0);
}

static void init_cfi_state(struct cfi_state *cfi)
{
        int i;

        for (i = 0; i < CFI_NUM_REGS; i++) {
                cfi->regs[i].base = CFI_UNDEFINED;
                cfi->vals[i].base = CFI_UNDEFINED;
        }
        cfi->cfa.base = CFI_UNDEFINED;
        cfi->drap_reg = CFI_UNDEFINED;
        cfi->drap_offset = -1;
}

static void init_insn_state(struct objtool_file *file, struct insn_state *state,
                            struct section *sec)
{
        memset(state, 0, sizeof(*state));
        init_cfi_state(&state->cfi);

        if (opts.noinstr && sec)
                state->noinstr = sec->noinstr;
}

static struct cfi_state *cfi_alloc(void)
{
        struct cfi_state *cfi = calloc(1, sizeof(struct cfi_state));
        if (!cfi) {
                ERROR_GLIBC("calloc");
                exit(1);
        }
        nr_cfi++;
        return cfi;
}

static int cfi_bits;
static struct hlist_head *cfi_hash;

static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
{
        return memcmp((void *)cfi1 + sizeof(cfi1->hash),
                      (void *)cfi2 + sizeof(cfi2->hash),
                      sizeof(struct cfi_state) - sizeof(struct hlist_node));
}

static inline u32 cfi_key(struct cfi_state *cfi)
{
        return jhash((void *)cfi + sizeof(cfi->hash),
                     sizeof(*cfi) - sizeof(cfi->hash), 0);
}

static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
{
        struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
        struct cfi_state *obj;

        hlist_for_each_entry(obj, head, hash) {
                if (!cficmp(cfi, obj)) {
                        nr_cfi_cache++;
                        return obj;
                }
        }

        obj = cfi_alloc();
        *obj = *cfi;
        hlist_add_head(&obj->hash, head);

        return obj;
}

static void cfi_hash_add(struct cfi_state *cfi)
{
        struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];

        hlist_add_head(&cfi->hash, head);
}

static void *cfi_hash_alloc(unsigned long size)
{
        cfi_bits = max(10, ilog2(size));
        cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
                        PROT_READ|PROT_WRITE,
                        MAP_PRIVATE|MAP_ANON, -1, 0);
        if (cfi_hash == (void *)-1L) {
                ERROR_GLIBC("mmap fail cfi_hash");
                cfi_hash = NULL;
        }  else if (opts.stats) {
                printf("cfi_bits: %d\n", cfi_bits);
        }

        return cfi_hash;
}

static unsigned long nr_insns;
static unsigned long nr_insns_visited;

/*
 * Call the arch-specific instruction decoder for all the instructions and add
 * them to the global instruction list.
 */
static int decode_instructions(struct objtool_file *file)
{
        struct section *sec;
        struct symbol *func;
        unsigned long offset;
        struct instruction *insn;

        for_each_sec(file->elf, sec) {
                struct instruction *insns = NULL;
                u8 prev_len = 0;
                u8 idx = 0;

                if (!is_text_sec(sec))
                        continue;

                if (strcmp(sec->name, ".altinstr_replacement") &&
                    strcmp(sec->name, ".altinstr_aux") &&
                    strncmp(sec->name, ".discard.", 9))
                        sec->text = true;

                if (!strcmp(sec->name, ".noinstr.text") ||
                    !strcmp(sec->name, ".entry.text") ||
                    !strcmp(sec->name, ".cpuidle.text") ||
                    !strncmp(sec->name, ".text..__x86.", 13))
                        sec->noinstr = true;

                /*
                 * .init.text code is ran before userspace and thus doesn't
                 * strictly need retpolines, except for modules which are
                 * loaded late, they very much do need retpoline in their
                 * .init.text
                 */
                if (!strcmp(sec->name, ".init.text") && !opts.module)
                        sec->init = true;

                for (offset = 0; offset < sec_size(sec); offset += insn->len) {
                        if (!insns || idx == INSN_CHUNK_MAX) {
                                insns = calloc(INSN_CHUNK_SIZE, sizeof(*insn));
                                if (!insns) {
                                        ERROR_GLIBC("calloc");
                                        return -1;
                                }
                                idx = 0;
                        } else {
                                idx++;
                        }
                        insn = &insns[idx];
                        insn->idx = idx;

                        INIT_LIST_HEAD(&insn->call_node);
                        insn->sec = sec;
                        insn->offset = offset;
                        insn->prev_len = prev_len;

                        if (arch_decode_instruction(file, sec, offset, sec_size(sec) - offset, insn))
                                return -1;

                        prev_len = insn->len;

                        /*
                         * By default, "ud2" is a dead end unless otherwise
                         * annotated, because GCC 7 inserts it for certain
                         * divide-by-zero cases.
                         */
                        if (insn->type == INSN_BUG)
                                insn->dead_end = true;

                        hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
                        nr_insns++;
                }

                sec_for_each_sym(sec, func) {
                        if (!is_notype_sym(func) && !is_func_sym(func))
                                continue;

                        if (func->offset == sec_size(sec)) {
                                /* Heuristic: likely an "end" symbol */
                                if (is_notype_sym(func))
                                        continue;
                                ERROR("%s(): STT_FUNC at end of section", func->name);
                                return -1;
                        }

                        if (func->embedded_insn || func->alias != func)
                                continue;

                        if (!find_insn(file, sec, func->offset)) {
                                ERROR("%s(): can't find starting instruction", func->name);
                                return -1;
                        }

                        sym_for_each_insn(file, func, insn) {
                                insn->sym = func;
                                if (is_func_sym(func) &&
                                    insn->type == INSN_ENDBR &&
                                    list_empty(&insn->call_node)) {
                                        if (insn->offset == func->offset) {
                                                list_add_tail(&insn->call_node, &file->endbr_list);
                                                file->nr_endbr++;
                                        } else {
                                                file->nr_endbr_int++;
                                        }
                                }
                        }
                }
        }

        if (opts.stats)
                printf("nr_insns: %lu\n", nr_insns);

        return 0;
}

/*
 * Known pv_ops*[] arrays.
 */
static struct {
        const char *name;
        int idx_off;
} pv_ops_tables[] = {
        { .name = "pv_ops", },
        { .name = "pv_ops_lock", },
        { .name = NULL, .idx_off = -1 }
};

/*
 * Get index offset for a pv_ops* array.
 */
int pv_ops_idx_off(const char *symname)
{
        int idx;

        for (idx = 0; pv_ops_tables[idx].name; idx++) {
                if (!strcmp(symname, pv_ops_tables[idx].name))
                        break;
        }

        return pv_ops_tables[idx].idx_off;
}

/*
 * Read a pv_ops*[] .data table to find the static initialized values.
 */
static int add_pv_ops(struct objtool_file *file, int pv_ops_idx)
{
        struct symbol *sym, *func;
        unsigned long off, end;
        struct reloc *reloc;
        int idx, idx_off;
        const char *symname;

        symname = pv_ops_tables[pv_ops_idx].name;
        sym = find_symbol_by_name(file->elf, symname);
        if (!sym) {
                ERROR("Unknown pv_ops array %s", symname);
                return -1;
        }

        off = sym->offset;
        end = off + sym->len;
        idx_off = pv_ops_tables[pv_ops_idx].idx_off;
        if (idx_off < 0) {
                ERROR("pv_ops array %s has unknown index offset", symname);
                return -1;
        }

        for (;;) {
                reloc = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
                if (!reloc)
                        break;

                idx = (reloc_offset(reloc) - sym->offset) / sizeof(unsigned long);

                func = reloc->sym;
                if (is_sec_sym(func))
                        func = find_symbol_by_offset(reloc->sym->sec,
                                                     reloc_addend(reloc));
                if (!func) {
                        ERROR_FUNC(reloc->sym->sec, reloc_addend(reloc),
                                   "can't find func at %s[%d]", symname, idx);
                        return -1;
                }

                if (objtool_pv_add(file, idx + idx_off, func))
                        return -1;

                off = reloc_offset(reloc) + 1;
                if (off > end)
                        break;
        }

        return 0;
}

/*
 * Allocate and initialize file->pv_ops[].
 */
static int init_pv_ops(struct objtool_file *file)
{
        struct symbol *sym;
        int idx, nr;

        if (!opts.noinstr)
                return 0;

        file->pv_ops = NULL;

        nr = 0;
        for (idx = 0; pv_ops_tables[idx].name; idx++) {
                sym = find_symbol_by_name(file->elf, pv_ops_tables[idx].name);
                if (!sym) {
                        pv_ops_tables[idx].idx_off = -1;
                        continue;
                }
                pv_ops_tables[idx].idx_off = nr;
                nr += sym->len / sizeof(unsigned long);
        }

        if (nr == 0)
                return 0;

        file->pv_ops = calloc(nr, sizeof(struct pv_state));
        if (!file->pv_ops) {
                ERROR_GLIBC("calloc");
                return -1;
        }

        for (idx = 0; idx < nr; idx++)
                INIT_LIST_HEAD(&file->pv_ops[idx].targets);

        for (idx = 0; pv_ops_tables[idx].name; idx++) {
                if (pv_ops_tables[idx].idx_off < 0)
                        continue;
                if (add_pv_ops(file, idx))
                        return -1;
        }

        return 0;
}

static bool is_livepatch_module(struct objtool_file *file)
{
        struct section *sec;

        if (!opts.module)
                return false;

        sec = find_section_by_name(file->elf, ".modinfo");
        if (!sec)
                return false;

        return memmem(sec->data->d_buf, sec_size(sec), "\0livepatch=Y", 12);
}

static int create_static_call_sections(struct objtool_file *file)
{
        struct static_call_site *site;
        struct section *sec;
        struct instruction *insn;
        struct symbol *key_sym;
        char *key_name, *tmp;
        int idx;

        sec = find_section_by_name(file->elf, ".static_call_sites");
        if (sec) {
                /*
                 * Livepatch modules may have already extracted the static call
                 * site entries to take advantage of vmlinux static call
                 * privileges.
                 */
                if (!file->klp)
                        WARN("file already has .static_call_sites section, skipping");

                return 0;
        }

        if (list_empty(&file->static_call_list))
                return 0;

        idx = 0;
        list_for_each_entry(insn, &file->static_call_list, call_node)
                idx++;

        sec = elf_create_section_pair(file->elf, ".static_call_sites",
                                      sizeof(*site), idx, idx * 2);
        if (!sec)
                return -1;

        /* Allow modules to modify the low bits of static_call_site::key */
        sec->sh.sh_flags |= SHF_WRITE;

        idx = 0;
        list_for_each_entry(insn, &file->static_call_list, call_node) {

                /* populate reloc for 'addr' */
                if (!elf_init_reloc_text_sym(file->elf, sec,
                                             idx * sizeof(*site), idx * 2,
                                             insn->sec, insn->offset))
                        return -1;

                /* find key symbol */
                key_name = strdup(insn_call_dest(insn)->name);
                if (!key_name) {
                        ERROR_GLIBC("strdup");
                        return -1;
                }
                if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
                            STATIC_CALL_TRAMP_PREFIX_LEN)) {
                        ERROR("static_call: trampoline name malformed: %s", key_name);
                        return -1;
                }
                tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
                memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);

                key_sym = find_symbol_by_name(file->elf, tmp);
                if (!key_sym) {
                        if (!opts.module) {
                                ERROR("static_call: can't find static_call_key symbol: %s", tmp);
                                return -1;
                        }

                        /*
                         * For modules(), the key might not be exported, which
                         * means the module can make static calls but isn't
                         * allowed to change them.
                         *
                         * In that case we temporarily set the key to be the
                         * trampoline address.  This is fixed up in
                         * static_call_add_module().
                         */
                        key_sym = insn_call_dest(insn);
                }

                /* populate reloc for 'key' */
                if (!elf_init_reloc_data_sym(file->elf, sec,
                                             idx * sizeof(*site) + 4,
                                             (idx * 2) + 1, key_sym,
                                             is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
                        return -1;

                idx++;
        }

        return 0;
}

static int create_retpoline_sites_sections(struct objtool_file *file)
{
        struct instruction *insn;
        struct section *sec;
        int idx;

        sec = find_section_by_name(file->elf, ".retpoline_sites");
        if (sec) {
                WARN("file already has .retpoline_sites, skipping");
                return 0;
        }

        idx = 0;
        list_for_each_entry(insn, &file->retpoline_call_list, call_node)
                idx++;

        if (!idx)
                return 0;

        sec = elf_create_section_pair(file->elf, ".retpoline_sites",
                                      sizeof(int), idx, idx);
        if (!sec)
                return -1;

        idx = 0;
        list_for_each_entry(insn, &file->retpoline_call_list, call_node) {

                if (!elf_init_reloc_text_sym(file->elf, sec,
                                             idx * sizeof(int), idx,
                                             insn->sec, insn->offset))
                        return -1;

                idx++;
        }

        return 0;
}

static int create_return_sites_sections(struct objtool_file *file)
{
        struct instruction *insn;
        struct section *sec;
        int idx;

        sec = find_section_by_name(file->elf, ".return_sites");
        if (sec) {
                WARN("file already has .return_sites, skipping");
                return 0;
        }

        idx = 0;
        list_for_each_entry(insn, &file->return_thunk_list, call_node)
                idx++;

        if (!idx)
                return 0;

        sec = elf_create_section_pair(file->elf, ".return_sites",
                                      sizeof(int), idx, idx);
        if (!sec)
                return -1;

        idx = 0;
        list_for_each_entry(insn, &file->return_thunk_list, call_node) {

                if (!elf_init_reloc_text_sym(file->elf, sec,
                                             idx * sizeof(int), idx,
                                             insn->sec, insn->offset))
                        return -1;

                idx++;
        }

        return 0;
}

static int create_ibt_endbr_seal_sections(struct objtool_file *file)
{
        struct instruction *insn;
        struct section *sec;
        int idx;

        sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
        if (sec) {
                WARN("file already has .ibt_endbr_seal, skipping");
                return 0;
        }

        idx = 0;
        list_for_each_entry(insn, &file->endbr_list, call_node)
                idx++;

        if (opts.stats) {
                printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
                printf("ibt: ENDBR inside functions:  %d\n", file->nr_endbr_int);
                printf("ibt: superfluous ENDBR:       %d\n", idx);
        }

        if (!idx)
                return 0;

        sec = elf_create_section_pair(file->elf, ".ibt_endbr_seal",
                                      sizeof(int), idx, idx);
        if (!sec)
                return -1;

        idx = 0;
        list_for_each_entry(insn, &file->endbr_list, call_node) {

                int *site = (int *)sec->data->d_buf + idx;
                struct symbol *sym = insn->sym;
                *site = 0;

                if (opts.module && sym && is_func_sym(sym) &&
                    insn->offset == sym->offset &&
                    (!strcmp(sym->name, "init_module") ||
                     !strcmp(sym->name, "cleanup_module"))) {
                        ERROR("%s(): Magic init_module() function name is deprecated, use module_init(fn) instead",
                              sym->name);
                        return -1;
                }

                if (!elf_init_reloc_text_sym(file->elf, sec,
                                             idx * sizeof(int), idx,
                                             insn->sec, insn->offset))
                        return -1;

                idx++;
        }

        return 0;
}

static int create_cfi_sections(struct objtool_file *file)
{
        struct section *sec;
        struct symbol *sym;
        int idx;

        sec = find_section_by_name(file->elf, ".cfi_sites");
        if (sec) {
                WARN("file already has .cfi_sites section, skipping");
                return 0;
        }

        idx = 0;
        for_each_sym(file->elf, sym) {
                if (!is_func_sym(sym))
                        continue;

                if (strncmp(sym->name, "__cfi_", 6))
                        continue;

                idx++;
        }

        sec = elf_create_section_pair(file->elf, ".cfi_sites",
                                      sizeof(unsigned int), idx, idx);
        if (!sec)
                return -1;

        idx = 0;
        for_each_sym(file->elf, sym) {
                if (!is_func_sym(sym))
                        continue;

                if (strncmp(sym->name, "__cfi_", 6))
                        continue;

                if (!elf_init_reloc_text_sym(file->elf, sec,
                                             idx * sizeof(unsigned int), idx,
                                             sym->sec, sym->offset))
                        return -1;

                idx++;
        }

        return 0;
}

static int create_mcount_loc_sections(struct objtool_file *file)
{
        size_t addr_size = elf_addr_size(file->elf);
        struct instruction *insn;
        struct section *sec;
        int idx;

        sec = find_section_by_name(file->elf, "__mcount_loc");
        if (sec) {
                /*
                 * Livepatch modules have already extracted their __mcount_loc
                 * entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case.
                 */
                if (!file->klp)
                        WARN("file already has __mcount_loc section, skipping");

                return 0;
        }

        if (list_empty(&file->mcount_loc_list))
                return 0;

        idx = 0;
        list_for_each_entry(insn, &file->mcount_loc_list, call_node)
                idx++;

        sec = elf_create_section_pair(file->elf, "__mcount_loc", addr_size,
                                      idx, idx);
        if (!sec)
                return -1;

        sec->sh.sh_addralign = addr_size;

        idx = 0;
        list_for_each_entry(insn, &file->mcount_loc_list, call_node) {

                struct reloc *reloc;

                reloc = elf_init_reloc_text_sym(file->elf, sec, idx * addr_size, idx,
                                               insn->sec, insn->offset);
                if (!reloc)
                        return -1;

                set_reloc_type(file->elf, reloc, addr_size == 8 ? R_ABS64 : R_ABS32);

                idx++;
        }

        return 0;
}

static int create_direct_call_sections(struct objtool_file *file)
{
        struct instruction *insn;
        struct section *sec;
        int idx;

        sec = find_section_by_name(file->elf, ".call_sites");
        if (sec) {
                WARN("file already has .call_sites section, skipping");
                return 0;
        }

        if (list_empty(&file->call_list))
                return 0;

        idx = 0;
        list_for_each_entry(insn, &file->call_list, call_node)
                idx++;

        sec = elf_create_section_pair(file->elf, ".call_sites",
                                      sizeof(unsigned int), idx, idx);
        if (!sec)
                return -1;

        idx = 0;
        list_for_each_entry(insn, &file->call_list, call_node) {

                if (!elf_init_reloc_text_sym(file->elf, sec,
                                             idx * sizeof(unsigned int), idx,
                                             insn->sec, insn->offset))
                        return -1;

                idx++;
        }

        return 0;
}

#ifdef BUILD_KLP
static int create_sym_checksum_section(struct objtool_file *file)
{
        struct section *sec;
        struct symbol *sym;
        unsigned int idx = 0;
        struct sym_checksum *checksum;
        size_t entsize = sizeof(struct sym_checksum);

        sec = find_section_by_name(file->elf, ".discard.sym_checksum");
        if (sec) {
                if (!opts.dryrun)
                        WARN("file already has .discard.sym_checksum section, skipping");

                return 0;
        }

        for_each_sym(file->elf, sym)
                if (sym->csum.checksum)
                        idx++;

        if (!idx)
                return 0;

        sec = elf_create_section_pair(file->elf, ".discard.sym_checksum", entsize,
                                      idx, idx);
        if (!sec)
                return -1;

        idx = 0;
        for_each_sym(file->elf, sym) {
                if (!sym->csum.checksum)
                        continue;

                if (!elf_init_reloc(file->elf, sec->rsec, idx, idx * entsize,
                                    sym, 0, R_TEXT64))
                        return -1;

                checksum = (struct sym_checksum *)sec->data->d_buf + idx;
                checksum->addr = 0; /* reloc */
                checksum->checksum = sym->csum.checksum;

                mark_sec_changed(file->elf, sec, true);

                idx++;
        }

        return 0;
}
#else
static int create_sym_checksum_section(struct objtool_file *file) { return -EINVAL; }
#endif

/*
 * Warnings shouldn't be reported for ignored functions.
 */
static int add_ignores(struct objtool_file *file)
{
        struct section *rsec;
        struct symbol *func;
        struct reloc *reloc;

        rsec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
        if (!rsec)
                return 0;

        for_each_reloc(rsec, reloc) {
                switch (reloc->sym->type) {
                case STT_FUNC:
                        func = reloc->sym;
                        break;

                case STT_SECTION:
                        func = find_func_by_offset(reloc->sym->sec, reloc_addend(reloc));
                        if (!func)
                                continue;
                        break;

                default:
                        ERROR("unexpected relocation symbol type in %s: %d",
                              rsec->name, reloc->sym->type);
                        return -1;
                }

                func->ignore = true;
                if (func->cfunc)
                        func->cfunc->ignore = true;
        }

        return 0;
}

/*
 * This is a whitelist of functions that is allowed to be called with AC set.
 * The list is meant to be minimal and only contains compiler instrumentation
 * ABI and a few functions used to implement *_{to,from}_user() functions.
 *
 * These functions must not directly change AC, but may PUSHF/POPF.
 */
static const char *uaccess_safe_builtin[] = {
        /* KASAN */
        "kasan_report",
        "kasan_check_range",
        /* KASAN out-of-line */
        "__asan_loadN_noabort",
        "__asan_load1_noabort",
        "__asan_load2_noabort",
        "__asan_load4_noabort",
        "__asan_load8_noabort",
        "__asan_load16_noabort",
        "__asan_storeN_noabort",
        "__asan_store1_noabort",
        "__asan_store2_noabort",
        "__asan_store4_noabort",
        "__asan_store8_noabort",
        "__asan_store16_noabort",
        "__kasan_check_read",
        "__kasan_check_write",
        /* KASAN in-line */
        "__asan_report_load_n_noabort",
        "__asan_report_load1_noabort",
        "__asan_report_load2_noabort",
        "__asan_report_load4_noabort",
        "__asan_report_load8_noabort",
        "__asan_report_load16_noabort",
        "__asan_report_store_n_noabort",
        "__asan_report_store1_noabort",
        "__asan_report_store2_noabort",
        "__asan_report_store4_noabort",
        "__asan_report_store8_noabort",
        "__asan_report_store16_noabort",
        /* KCSAN */
        "__kcsan_check_access",
        "__kcsan_mb",
        "__kcsan_wmb",
        "__kcsan_rmb",
        "__kcsan_release",
        "kcsan_found_watchpoint",
        "kcsan_setup_watchpoint",
        "kcsan_check_scoped_accesses",
        "kcsan_disable_current",
        "kcsan_enable_current_nowarn",
        /* KCSAN/TSAN */
        "__tsan_func_entry",
        "__tsan_func_exit",
        "__tsan_read_range",
        "__tsan_write_range",
        "__tsan_read1",
        "__tsan_read2",
        "__tsan_read4",
        "__tsan_read8",
        "__tsan_read16",
        "__tsan_write1",
        "__tsan_write2",
        "__tsan_write4",
        "__tsan_write8",
        "__tsan_write16",
        "__tsan_read_write1",
        "__tsan_read_write2",
        "__tsan_read_write4",
        "__tsan_read_write8",
        "__tsan_read_write16",
        "__tsan_volatile_read1",
        "__tsan_volatile_read2",
        "__tsan_volatile_read4",
        "__tsan_volatile_read8",
        "__tsan_volatile_read16",
        "__tsan_volatile_write1",
        "__tsan_volatile_write2",
        "__tsan_volatile_write4",
        "__tsan_volatile_write8",
        "__tsan_volatile_write16",
        "__tsan_atomic8_load",
        "__tsan_atomic16_load",
        "__tsan_atomic32_load",
        "__tsan_atomic64_load",
        "__tsan_atomic8_store",
        "__tsan_atomic16_store",
        "__tsan_atomic32_store",
        "__tsan_atomic64_store",
        "__tsan_atomic8_exchange",
        "__tsan_atomic16_exchange",
        "__tsan_atomic32_exchange",
        "__tsan_atomic64_exchange",
        "__tsan_atomic8_fetch_add",
        "__tsan_atomic16_fetch_add",
        "__tsan_atomic32_fetch_add",
        "__tsan_atomic64_fetch_add",
        "__tsan_atomic8_fetch_sub",
        "__tsan_atomic16_fetch_sub",
        "__tsan_atomic32_fetch_sub",
        "__tsan_atomic64_fetch_sub",
        "__tsan_atomic8_fetch_and",
        "__tsan_atomic16_fetch_and",
        "__tsan_atomic32_fetch_and",
        "__tsan_atomic64_fetch_and",
        "__tsan_atomic8_fetch_or",
        "__tsan_atomic16_fetch_or",
        "__tsan_atomic32_fetch_or",
        "__tsan_atomic64_fetch_or",
        "__tsan_atomic8_fetch_xor",
        "__tsan_atomic16_fetch_xor",
        "__tsan_atomic32_fetch_xor",
        "__tsan_atomic64_fetch_xor",
        "__tsan_atomic8_fetch_nand",
        "__tsan_atomic16_fetch_nand",
        "__tsan_atomic32_fetch_nand",
        "__tsan_atomic64_fetch_nand",
        "__tsan_atomic8_compare_exchange_strong",
        "__tsan_atomic16_compare_exchange_strong",
        "__tsan_atomic32_compare_exchange_strong",
        "__tsan_atomic64_compare_exchange_strong",
        "__tsan_atomic8_compare_exchange_weak",
        "__tsan_atomic16_compare_exchange_weak",
        "__tsan_atomic32_compare_exchange_weak",
        "__tsan_atomic64_compare_exchange_weak",
        "__tsan_atomic8_compare_exchange_val",
        "__tsan_atomic16_compare_exchange_val",
        "__tsan_atomic32_compare_exchange_val",
        "__tsan_atomic64_compare_exchange_val",
        "__tsan_atomic_thread_fence",
        "__tsan_atomic_signal_fence",
        "__tsan_unaligned_read16",
        "__tsan_unaligned_write16",
        /* KCOV */
        "write_comp_data",
        "check_kcov_mode",
        "__sanitizer_cov_trace_pc",
        "__sanitizer_cov_trace_const_cmp1",
        "__sanitizer_cov_trace_const_cmp2",
        "__sanitizer_cov_trace_const_cmp4",
        "__sanitizer_cov_trace_const_cmp8",
        "__sanitizer_cov_trace_cmp1",
        "__sanitizer_cov_trace_cmp2",
        "__sanitizer_cov_trace_cmp4",
        "__sanitizer_cov_trace_cmp8",
        "__sanitizer_cov_trace_switch",
        /* KMSAN */
        "kmsan_copy_to_user",
        "kmsan_disable_current",
        "kmsan_enable_current",
        "kmsan_report",
        "kmsan_unpoison_entry_regs",
        "kmsan_unpoison_memory",
        "__msan_chain_origin",
        "__msan_get_context_state",
        "__msan_instrument_asm_store",
        "__msan_metadata_ptr_for_load_1",
        "__msan_metadata_ptr_for_load_2",
        "__msan_metadata_ptr_for_load_4",
        "__msan_metadata_ptr_for_load_8",
        "__msan_metadata_ptr_for_load_n",
        "__msan_metadata_ptr_for_store_1",
        "__msan_metadata_ptr_for_store_2",
        "__msan_metadata_ptr_for_store_4",
        "__msan_metadata_ptr_for_store_8",
        "__msan_metadata_ptr_for_store_n",
        "__msan_poison_alloca",
        "__msan_warning",
        /* UBSAN */
        "ubsan_type_mismatch_common",
        "__ubsan_handle_type_mismatch",
        "__ubsan_handle_type_mismatch_v1",
        "__ubsan_handle_shift_out_of_bounds",
        "__ubsan_handle_load_invalid_value",
        /* KSTACK_ERASE */
        "__sanitizer_cov_stack_depth",
        /* TRACE_BRANCH_PROFILING */
        "ftrace_likely_update",
        /* STACKPROTECTOR */
        "__stack_chk_fail",
        /* misc */
        "csum_partial_copy_generic",
        "copy_mc_fragile",
        "copy_mc_fragile_handle_tail",
        "copy_mc_enhanced_fast_string",
        "rep_stos_alternative",
        "rep_movs_alternative",
        "__copy_user_nocache",
        NULL
};

static void add_uaccess_safe(struct objtool_file *file)
{
        struct symbol *func;
        const char **name;

        if (!opts.uaccess)
                return;

        for (name = uaccess_safe_builtin; *name; name++) {
                func = find_symbol_by_name(file->elf, *name);
                if (!func)
                        continue;

                func->uaccess_safe = true;
        }
}

/*
 * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
 * will be added to the .retpoline_sites section.
 */
__weak bool arch_is_retpoline(struct symbol *sym)
{
        return false;
}

/*
 * Symbols that replace INSN_RETURN, every (tail) call to such a symbol
 * will be added to the .return_sites section.
 */
__weak bool arch_is_rethunk(struct symbol *sym)
{
        return false;
}

/*
 * Symbols that are embedded inside other instructions, because sometimes crazy
 * code exists. These are mostly ignored for validation purposes.
 */
__weak bool arch_is_embedded_insn(struct symbol *sym)
{
        return false;
}

static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
{
        struct reloc *reloc;

        if (insn->no_reloc)
                return NULL;

        if (!file)
                return NULL;

        reloc = find_reloc_by_dest_range(file->elf, insn->sec,
                                         insn->offset, insn->len);
        if (!reloc) {
                insn->no_reloc = 1;
                return NULL;
        }

        return reloc;
}

static void remove_insn_ops(struct instruction *insn)
{
        struct stack_op *op, *next;

        for (op = insn->stack_ops; op; op = next) {
                next = op->next;
                free(op);
        }
        insn->stack_ops = NULL;
}

static int annotate_call_site(struct objtool_file *file,
                               struct instruction *insn, bool sibling)
{
        struct reloc *reloc = insn_reloc(file, insn);
        struct symbol *sym = insn_call_dest(insn);

        if (!sym)
                sym = reloc->sym;

        if (sym->static_call_tramp) {
                list_add_tail(&insn->call_node, &file->static_call_list);
                return 0;
        }

        if (sym->retpoline_thunk) {
                list_add_tail(&insn->call_node, &file->retpoline_call_list);
                return 0;
        }

        /*
         * Many compilers cannot disable KCOV or sanitizer calls with a function
         * attribute so they need a little help, NOP out any such calls from
         * noinstr text.
         */
        if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
                if (reloc)
                        set_reloc_type(file->elf, reloc, R_NONE);

                if (elf_write_insn(file->elf, insn->sec,
                                   insn->offset, insn->len,
                                   sibling ? arch_ret_insn(insn->len)
                                           : arch_nop_insn(insn->len))) {
                        return -1;
                }

                insn->type = sibling ? INSN_RETURN : INSN_NOP;

                if (sibling) {
                        /*
                         * We've replaced the tail-call JMP insn by two new
                         * insn: RET; INT3, except we only have a single struct
                         * insn here. Mark it retpoline_safe to avoid the SLS
                         * warning, instead of adding another insn.
                         */
                        insn->retpoline_safe = true;
                }

                return 0;
        }

        if (opts.mcount && sym->fentry) {
                if (sibling)
                        WARN_INSN(insn, "tail call to __fentry__ !?!?");
                if (opts.mnop) {
                        if (reloc)
                                set_reloc_type(file->elf, reloc, R_NONE);

                        if (elf_write_insn(file->elf, insn->sec,
                                           insn->offset, insn->len,
                                           arch_nop_insn(insn->len))) {
                                return -1;
                        }

                        insn->type = INSN_NOP;
                }

                list_add_tail(&insn->call_node, &file->mcount_loc_list);
                return 0;
        }

        if (insn->type == INSN_CALL && !insn->sec->init &&
            !insn->_call_dest->embedded_insn)
                list_add_tail(&insn->call_node, &file->call_list);

        if (!sibling && dead_end_function(file, sym))
                insn->dead_end = true;

        return 0;
}

static int add_call_dest(struct objtool_file *file, struct instruction *insn,
                          struct symbol *dest, bool sibling)
{
        insn->_call_dest = dest;
        if (!dest)
                return 0;

        /*
         * Whatever stack impact regular CALLs have, should be undone
         * by the RETURN of the called function.
         *
         * Annotated intra-function calls retain the stack_ops but
         * are converted to JUMP, see read_intra_function_calls().
         */
        remove_insn_ops(insn);

        return annotate_call_site(file, insn, sibling);
}

static int add_retpoline_call(struct objtool_file *file, struct instruction *insn)
{
        /*
         * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
         * so convert them accordingly.
         */
        switch (insn->type) {
        case INSN_CALL:
                insn->type = INSN_CALL_DYNAMIC;
                break;
        case INSN_JUMP_UNCONDITIONAL:
                insn->type = INSN_JUMP_DYNAMIC;
                break;
        case INSN_JUMP_CONDITIONAL:
                insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
                break;
        default:
                return 0;
        }

        insn->retpoline_safe = true;

        /*
         * Whatever stack impact regular CALLs have, should be undone
         * by the RETURN of the called function.
         *
         * Annotated intra-function calls retain the stack_ops but
         * are converted to JUMP, see read_intra_function_calls().
         */
        remove_insn_ops(insn);

        return annotate_call_site(file, insn, false);
}

static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
{
        /*
         * Return thunk tail calls are really just returns in disguise,
         * so convert them accordingly.
         */
        insn->type = INSN_RETURN;
        insn->retpoline_safe = true;

        if (add)
                list_add_tail(&insn->call_node, &file->return_thunk_list);
}

static bool is_first_func_insn(struct objtool_file *file,
                               struct instruction *insn)
{
        struct symbol *func = insn_func(insn);

        if (!func)
                return false;

        if (insn->offset == func->offset)
                return true;

        /* Allow direct CALL/JMP past ENDBR */
        if (opts.ibt) {
                struct instruction *prev = prev_insn_same_sym(file, insn);

                if (prev && prev->type == INSN_ENDBR &&
                    insn->offset == func->offset + prev->len)
                        return true;
        }

        return false;
}

/*
 * Find the destination instructions for all jumps.
 */
static int add_jump_destinations(struct objtool_file *file)
{
        struct instruction *insn;
        struct reloc *reloc;

        for_each_insn(file, insn) {
                struct symbol *func = insn_func(insn);
                struct instruction *dest_insn;
                struct section *dest_sec;
                struct symbol *dest_sym;
                unsigned long dest_off;

                if (!is_static_jump(insn))
                        continue;

                if (insn->jump_dest) {
                        /*
                         * handle_group_alt() may have previously set
                         * 'jump_dest' for some alternatives.
                         */
                        continue;
                }

                reloc = insn_reloc(file, insn);
                if (!reloc) {
                        dest_sec = insn->sec;
                        dest_off = arch_jump_destination(insn);
                        dest_sym = dest_sec->sym;
                } else {
                        dest_sym = reloc->sym;
                        if (is_undef_sym(dest_sym)) {
                                if (dest_sym->retpoline_thunk) {
                                        if (add_retpoline_call(file, insn))
                                                return -1;
                                        continue;
                                }

                                if (dest_sym->return_thunk) {
                                        add_return_call(file, insn, true);
                                        continue;
                                }

                                /* External symbol */
                                if (func) {
                                        /* External sibling call */
                                        if (add_call_dest(file, insn, dest_sym, true))
                                                return -1;
                                        continue;
                                }

                                /* Non-func asm code jumping to external symbol */
                                continue;
                        }

                        dest_sec = dest_sym->sec;
                        dest_off = dest_sym->offset + arch_insn_adjusted_addend(insn, reloc);
                }

                dest_insn = find_insn(file, dest_sec, dest_off);
                if (!dest_insn) {
                        struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);

                        /*
                         * retbleed_untrain_ret() jumps to
                         * __x86_return_thunk(), but objtool can't find
                         * the thunk's starting RET instruction,
                         * because the RET is also in the middle of
                         * another instruction.  Objtool only knows
                         * about the outer instruction.
                         */
                        if (sym && sym->embedded_insn) {
                                add_return_call(file, insn, false);
                                continue;
                        }

                        /*
                         * GCOV/KCOV dead code can jump to the end of
                         * the function/section.
                         */
                        if (file->ignore_unreachables && func &&
                            dest_sec == insn->sec &&
                            dest_off == func->offset + func->len)
                                continue;

                        ERROR_INSN(insn, "can't find jump dest instruction at %s",
                                   offstr(dest_sec, dest_off));
                        return -1;
                }

                if (!dest_sym || is_sec_sym(dest_sym)) {
                        dest_sym = dest_insn->sym;
                        if (!dest_sym)
                                goto set_jump_dest;
                }

                if (dest_sym->retpoline_thunk && dest_insn->offset == dest_sym->offset) {
                        if (add_retpoline_call(file, insn))
                                return -1;
                        continue;
                }

                if (dest_sym->return_thunk && dest_insn->offset == dest_sym->offset) {
                        add_return_call(file, insn, true);
                        continue;
                }

                if (!insn->sym || insn->sym->pfunc == dest_sym->pfunc)
                        goto set_jump_dest;

                /*
                 * Internal cross-function jump.
                 */

                if (is_first_func_insn(file, dest_insn)) {
                        /* Internal sibling call */
                        if (add_call_dest(file, insn, dest_sym, true))
                                return -1;
                        continue;
                }

set_jump_dest:
                insn->jump_dest = dest_insn;
        }

        return 0;
}

static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
{
        struct symbol *call_dest;

        call_dest = find_func_by_offset(sec, offset);
        if (!call_dest)
                call_dest = find_symbol_by_offset(sec, offset);

        return call_dest;
}

/*
 * Find the destination instructions for all calls.
 */
static int add_call_destinations(struct objtool_file *file)
{
        struct instruction *insn;
        unsigned long dest_off;
        struct symbol *dest;
        struct reloc *reloc;

        for_each_insn(file, insn) {
                struct symbol *func = insn_func(insn);
                if (insn->type != INSN_CALL)
                        continue;

                reloc = insn_reloc(file, insn);
                if (!reloc) {
                        dest_off = arch_jump_destination(insn);
                        dest = find_call_destination(insn->sec, dest_off);

                        if (add_call_dest(file, insn, dest, false))
                                return -1;

                        if (func && func->ignore)
                                continue;

                        if (!insn_call_dest(insn)) {
                                ERROR_INSN(insn, "unannotated intra-function call");
                                return -1;
                        }

                        if (func && !is_func_sym(insn_call_dest(insn))) {
                                ERROR_INSN(insn, "unsupported call to non-function");
                                return -1;
                        }

                } else if (is_sec_sym(reloc->sym)) {
                        dest_off = arch_insn_adjusted_addend(insn, reloc);
                        dest = find_call_destination(reloc->sym->sec, dest_off);
                        if (!dest) {
                                ERROR_INSN(insn, "can't find call dest symbol at %s+0x%lx",
                                           reloc->sym->sec->name, dest_off);
                                return -1;
                        }

                        if (add_call_dest(file, insn, dest, false))
                                return -1;

                } else if (reloc->sym->retpoline_thunk) {
                        if (add_retpoline_call(file, insn))
                                return -1;

                } else {
                        if (add_call_dest(file, insn, reloc->sym, false))
                                return -1;
                }
        }

        return 0;
}

/*
 * The .alternatives section requires some extra special care over and above
 * other special sections because alternatives are patched in place.
 */
static int handle_group_alt(struct objtool_file *file,
                            struct special_alt *special_alt,
                            struct instruction *orig_insn,
                            struct instruction **new_insn)
{
        struct instruction *last_new_insn = NULL, *insn, *nop = NULL;
        struct alt_group *orig_alt_group, *new_alt_group;
        unsigned long dest_off;

        orig_alt_group = orig_insn->alt_group;
        if (!orig_alt_group) {
                struct instruction *last_orig_insn = NULL;

                orig_alt_group = calloc(1, sizeof(*orig_alt_group));
                if (!orig_alt_group) {
                        ERROR_GLIBC("calloc");
                        return -1;
                }
                orig_alt_group->cfi = calloc(special_alt->orig_len,
                                             sizeof(struct cfi_state *));
                if (!orig_alt_group->cfi) {
                        ERROR_GLIBC("calloc");
                        return -1;
                }

                insn = orig_insn;
                sec_for_each_insn_from(file, insn) {
                        if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
                                break;

                        insn->alt_group = orig_alt_group;
                        last_orig_insn = insn;
                }
                orig_alt_group->orig_group = NULL;
                orig_alt_group->first_insn = orig_insn;
                orig_alt_group->last_insn = last_orig_insn;
                orig_alt_group->nop = NULL;
                orig_alt_group->ignore = orig_insn->ignore_alts;
                orig_alt_group->feature = 0;
        } else {
                if (orig_alt_group->last_insn->offset + orig_alt_group->last_insn->len -
                    orig_alt_group->first_insn->offset != special_alt->orig_len) {
                        ERROR_INSN(orig_insn, "weirdly overlapping alternative! %ld != %d",
                                   orig_alt_group->last_insn->offset +
                                   orig_alt_group->last_insn->len -
                                   orig_alt_group->first_insn->offset,
                                   special_alt->orig_len);
                        return -1;
                }
        }

        new_alt_group = calloc(1, sizeof(*new_alt_group));
        if (!new_alt_group) {
                ERROR_GLIBC("calloc");
                return -1;
        }

        if (special_alt->new_len < special_alt->orig_len) {
                /*
                 * Insert a fake nop at the end to make the replacement
                 * alt_group the same size as the original.  This is needed to
                 * allow propagate_alt_cfi() to do its magic.  When the last
                 * instruction affects the stack, the instruction after it (the
                 * nop) will propagate the new state to the shared CFI array.
                 */
                nop = calloc(1, sizeof(*nop));
                if (!nop) {
                        ERROR_GLIBC("calloc");
                        return -1;
                }
                memset(nop, 0, sizeof(*nop));

                nop->sec = special_alt->new_sec;
                nop->offset = special_alt->new_off + special_alt->new_len;
                nop->len = special_alt->orig_len - special_alt->new_len;
                nop->type = INSN_NOP;
                nop->sym = orig_insn->sym;
                nop->alt_group = new_alt_group;
                nop->fake = 1;
        }

        if (!special_alt->new_len) {
                *new_insn = nop;
                goto end;
        }

        insn = *new_insn;
        sec_for_each_insn_from(file, insn) {
                struct reloc *alt_reloc;

                if (insn->offset >= special_alt->new_off + special_alt->new_len)
                        break;

                last_new_insn = insn;

                insn->sym = orig_insn->sym;
                insn->alt_group = new_alt_group;

                /*
                 * Since alternative replacement code is copy/pasted by the
                 * kernel after applying relocations, generally such code can't
                 * have relative-address relocation references to outside the
                 * .altinstr_replacement section, unless the arch's
                 * alternatives code can adjust the relative offsets
                 * accordingly.
                 */
                alt_reloc = insn_reloc(file, insn);
                if (alt_reloc && arch_pc_relative_reloc(alt_reloc) &&
                    !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {

                        ERROR_INSN(insn, "unsupported relocation in alternatives section");
                        return -1;
                }

                if (!is_static_jump(insn))
                        continue;

                if (!insn->immediate)
                        continue;

                dest_off = arch_jump_destination(insn);
                if (dest_off == special_alt->new_off + special_alt->new_len) {
                        insn->jump_dest = next_insn_same_sec(file, orig_alt_group->last_insn);
                        if (!insn->jump_dest) {
                                ERROR_INSN(insn, "can't find alternative jump destination");
                                return -1;
                        }
                }
        }

        if (!last_new_insn) {
                ERROR_FUNC(special_alt->new_sec, special_alt->new_off,
                           "can't find last new alternative instruction");
                return -1;
        }

end:
        new_alt_group->orig_group = orig_alt_group;
        new_alt_group->first_insn = *new_insn;
        new_alt_group->last_insn = last_new_insn;
        new_alt_group->nop = nop;
        new_alt_group->ignore = (*new_insn)->ignore_alts;
        new_alt_group->cfi = orig_alt_group->cfi;
        new_alt_group->feature = special_alt->feature;
        return 0;
}

/*
 * A jump table entry can either convert a nop to a jump or a jump to a nop.
 * If the original instruction is a jump, make the alt entry an effective nop
 * by just skipping the original instruction.
 */
static int handle_jump_alt(struct objtool_file *file,
                           struct special_alt *special_alt,
                           struct instruction *orig_insn,
                           struct instruction **new_insn)
{
        if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
            orig_insn->type != INSN_NOP) {

                ERROR_INSN(orig_insn, "unsupported instruction at jump label");
                return -1;
        }

        if (opts.hack_jump_label && special_alt->key_addend & 2) {
                struct reloc *reloc = insn_reloc(file, orig_insn);

                if (reloc)
                        set_reloc_type(file->elf, reloc, R_NONE);

                if (elf_write_insn(file->elf, orig_insn->sec,
                                   orig_insn->offset, orig_insn->len,
                                   arch_nop_insn(orig_insn->len))) {
                        return -1;
                }

                orig_insn->type = INSN_NOP;
        }

        if (orig_insn->type == INSN_NOP) {
                if (orig_insn->len == 2)
                        file->jl_nop_short++;
                else
                        file->jl_nop_long++;

                return 0;
        }

        if (orig_insn->len == 2)
                file->jl_short++;
        else
                file->jl_long++;

        *new_insn = next_insn_same_sec(file, orig_insn);
        return 0;
}

/*
 * Read all the special sections which have alternate instructions which can be
 * patched in or redirected to at runtime.  Each instruction having alternate
 * instruction(s) has them added to its insn->alts list, which will be
 * traversed in validate_branch().
 */
static int add_special_section_alts(struct objtool_file *file)
{
        struct list_head special_alts;
        struct instruction *orig_insn, *new_insn;
        struct special_alt *special_alt, *tmp;
        enum alternative_type alt_type;
        struct alternative *alt;
        struct alternative *a;

        if (special_get_alts(file->elf, &special_alts))
                return -1;

        list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {

                orig_insn = find_insn(file, special_alt->orig_sec,
                                      special_alt->orig_off);
                if (!orig_insn) {
                        ERROR_FUNC(special_alt->orig_sec, special_alt->orig_off,
                                   "special: can't find orig instruction");
                        return -1;
                }

                new_insn = NULL;
                if (!special_alt->group || special_alt->new_len) {
                        new_insn = find_insn(file, special_alt->new_sec,
                                             special_alt->new_off);
                        if (!new_insn) {
                                ERROR_FUNC(special_alt->new_sec, special_alt->new_off,
                                           "special: can't find new instruction");
                                return -1;
                        }
                }

                if (special_alt->group) {
                        if (!special_alt->orig_len) {
                                ERROR_INSN(orig_insn, "empty alternative entry");
                                continue;
                        }

                        if (handle_group_alt(file, special_alt, orig_insn, &new_insn))
                                return -1;

                        alt_type = ALT_TYPE_INSTRUCTIONS;

                } else if (special_alt->jump_or_nop) {
                        if (handle_jump_alt(file, special_alt, orig_insn, &new_insn))
                                return -1;

                        alt_type = ALT_TYPE_JUMP_TABLE;
                } else {
                        alt_type = ALT_TYPE_EX_TABLE;
                }

                alt = calloc(1, sizeof(*alt));
                if (!alt) {
                        ERROR_GLIBC("calloc");
                        return -1;
                }

                alt->insn = new_insn;
                alt->type = alt_type;
                alt->next = NULL;

                /*
                 * Store alternatives in the same order they have been
                 * defined.
                 */
                if (!orig_insn->alts) {
                        orig_insn->alts = alt;
                } else {
                        for (a = orig_insn->alts; a->next; a = a->next)
                                ;
                        a->next = alt;
                }

                list_del(&special_alt->list);
                free(special_alt);
        }

        if (opts.stats) {
                printf("jl\\\tNOP\tJMP\n");
                printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
                printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
        }

        return 0;
}

__weak unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *table)
{
        return reloc->sym->offset + reloc_addend(reloc);
}

static int add_jump_table(struct objtool_file *file, struct instruction *insn)
{
        unsigned long table_size = insn_jump_table_size(insn);
        struct symbol *pfunc = insn_func(insn)->pfunc;
        struct reloc *table = insn_jump_table(insn);
        struct instruction *dest_insn;
        unsigned int prev_offset = 0;
        struct reloc *reloc = table;
        struct alternative *alt;
        unsigned long sym_offset;

        /*
         * Each @reloc is a switch table relocation which points to the target
         * instruction.
         */
        for_each_reloc_from(table->sec, reloc) {

                /* Check for the end of the table: */
                if (table_size && reloc_offset(reloc) - reloc_offset(table) >= table_size)
                        break;
                if (reloc != table && is_jump_table(reloc))
                        break;

                /* Make sure the table entries are consecutive: */
                if (prev_offset && reloc_offset(reloc) != prev_offset + arch_reloc_size(reloc))
                        break;

                sym_offset = arch_jump_table_sym_offset(reloc, table);

                /* Detect function pointers from contiguous objects: */
                if (reloc->sym->sec == pfunc->sec && sym_offset == pfunc->offset)
                        break;

                /*
                 * Clang sometimes leaves dangling unused jump table entries
                 * which point to the end of the function.  Ignore them.
                 */
                if (reloc->sym->sec == pfunc->sec &&
                    sym_offset == pfunc->offset + pfunc->len)
                        goto next;

                dest_insn = find_insn(file, reloc->sym->sec, sym_offset);
                if (!dest_insn)
                        break;

                /* Make sure the destination is in the same function: */
                if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
                        break;

                alt = calloc(1, sizeof(*alt));
                if (!alt) {
                        ERROR_GLIBC("calloc");
                        return -1;
                }

                alt->insn = dest_insn;
                alt->next = insn->alts;
                insn->alts = alt;
next:
                prev_offset = reloc_offset(reloc);
        }

        if (!prev_offset) {
                ERROR_INSN(insn, "can't find switch jump table");
                return -1;
        }

        return 0;
}

/*
 * find_jump_table() - Given a dynamic jump, find the switch jump table
 * associated with it.
 */
static void find_jump_table(struct objtool_file *file, struct symbol *func,
                            struct instruction *insn)
{
        struct reloc *table_reloc;
        struct instruction *dest_insn, *orig_insn = insn;
        unsigned long table_size;
        unsigned long sym_offset;

        /*
         * Backward search using the @first_jump_src links, these help avoid
         * much of the 'in between' code. Which avoids us getting confused by
         * it.
         */
        for (;
             insn && insn_func(insn) && insn_func(insn)->pfunc == func;
             insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {

                if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
                        break;

                /* allow small jumps within the range */
                if (insn->type == INSN_JUMP_UNCONDITIONAL &&
                    insn->jump_dest &&
                    (insn->jump_dest->offset <= insn->offset ||
                     insn->jump_dest->offset > orig_insn->offset))
                        break;

                table_reloc = arch_find_switch_table(file, insn, &table_size);
                if (!table_reloc)
                        continue;

                sym_offset = table_reloc->sym->offset + reloc_addend(table_reloc);

                dest_insn = find_insn(file, table_reloc->sym->sec, sym_offset);
                if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
                        continue;

                set_jump_table(table_reloc);
                orig_insn->_jump_table = table_reloc;
                orig_insn->_jump_table_size = table_size;

                break;
        }
}

/*
 * First pass: Mark the head of each jump table so that in the next pass,
 * we know when a given jump table ends and the next one starts.
 */
static void mark_func_jump_tables(struct objtool_file *file,
                                    struct symbol *func)
{
        struct instruction *insn, *last = NULL;

        func_for_each_insn(file, func, insn) {
                if (!last)
                        last = insn;

                /*
                 * Store back-pointers for forward jumps such
                 * that find_jump_table() can back-track using those and
                 * avoid some potentially confusing code.
                 */
                if (insn->jump_dest &&
                    insn->jump_dest->offset > insn->offset &&
                    !insn->jump_dest->first_jump_src) {

                        insn->jump_dest->first_jump_src = insn;
                        last = insn->jump_dest;
                }

                if (insn->type != INSN_JUMP_DYNAMIC)
                        continue;

                find_jump_table(file, func, insn);
        }
}

static int add_func_jump_tables(struct objtool_file *file,
                                  struct symbol *func)
{
        struct instruction *insn;

        func_for_each_insn(file, func, insn) {
                if (!insn_jump_table(insn))
                        continue;

                if (add_jump_table(file, insn))
                        return -1;
        }

        return 0;
}

/*
 * For some switch statements, gcc generates a jump table in the .rodata
 * section which contains a list of addresses within the function to jump to.
 * This finds these jump tables and adds them to the insn->alts lists.
 */
static int add_jump_table_alts(struct objtool_file *file)
{
        struct symbol *func;

        if (!file->rodata)
                return 0;

        for_each_sym(file->elf, func) {
                if (!is_func_sym(func) || func->alias != func)
                        continue;

                mark_func_jump_tables(file, func);
                if (add_func_jump_tables(file, func))
                        return -1;
        }

        return 0;
}

static void set_func_state(struct cfi_state *state)
{
        state->cfa = initial_func_cfi.cfa;
        memcpy(&state->regs, &initial_func_cfi.regs,
               CFI_NUM_REGS * sizeof(struct cfi_reg));
        state->stack_size = initial_func_cfi.cfa.offset;
        state->type = UNWIND_HINT_TYPE_CALL;
}

static int read_unwind_hints(struct objtool_file *file)
{
        struct cfi_state cfi = init_cfi;
        struct section *sec;
        struct unwind_hint *hint;
        struct instruction *insn;
        struct reloc *reloc;
        unsigned long offset;
        int i;

        sec = find_section_by_name(file->elf, ".discard.unwind_hints");
        if (!sec)
                return 0;

        if (!sec->rsec) {
                ERROR("missing .rela.discard.unwind_hints section");
                return -1;
        }

        if (sec_size(sec) % sizeof(struct unwind_hint)) {
                ERROR("struct unwind_hint size mismatch");
                return -1;
        }

        file->hints = true;

        for (i = 0; i < sec_size(sec) / sizeof(struct unwind_hint); i++) {
                hint = (struct unwind_hint *)sec->data->d_buf + i;

                reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
                if (!reloc) {
                        ERROR("can't find reloc for unwind_hints[%d]", i);
                        return -1;
                }

                offset = reloc->sym->offset + reloc_addend(reloc);

                insn = find_insn(file, reloc->sym->sec, offset);
                if (!insn) {
                        ERROR("can't find insn for unwind_hints[%d]", i);
                        return -1;
                }

                insn->hint = true;

                if (hint->type == UNWIND_HINT_TYPE_UNDEFINED) {
                        insn->cfi = &force_undefined_cfi;
                        continue;
                }

                if (hint->type == UNWIND_HINT_TYPE_SAVE) {
                        insn->hint = false;
                        insn->save = true;
                        continue;
                }

                if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
                        insn->restore = true;
                        continue;
                }

                if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
                        struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);

                        if (sym && is_global_sym(sym)) {
                                if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
                                        ERROR_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
                                        return -1;
                                }
                        }
                }

                if (hint->type == UNWIND_HINT_TYPE_FUNC) {
                        insn->cfi = &func_cfi;
                        continue;
                }

                if (insn->cfi)
                        cfi = *(insn->cfi);

                if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
                        ERROR_INSN(insn, "unsupported unwind_hint sp base reg %d", hint->sp_reg);
                        return -1;
                }

                cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset);
                cfi.type = hint->type;
                cfi.signal = hint->signal;

                insn->cfi = cfi_hash_find_or_add(&cfi);
        }

        return 0;
}

static int read_annotate(struct objtool_file *file,
                         int (*func)(struct objtool_file *file, int type, struct instruction *insn))
{
        struct section *sec;
        struct instruction *insn;
        struct reloc *reloc;
        uint64_t offset;
        int type;

        sec = find_section_by_name(file->elf, ".discard.annotate_insn");
        if (!sec)
                return 0;

        if (!sec->rsec)
                return 0;

        if (sec->sh.sh_entsize != 8) {
                static bool warned = false;
                if (!warned && opts.verbose) {
                        WARN("%s: dodgy linker, sh_entsize != 8", sec->name);
                        warned = true;
                }
                sec->sh.sh_entsize = 8;
        }

        if (sec_num_entries(sec) != sec_num_entries(sec->rsec)) {
                ERROR("bad .discard.annotate_insn section: missing relocs");
                return -1;
        }

        for_each_reloc(sec->rsec, reloc) {
                type = annotype(file->elf, sec, reloc);
                offset = reloc->sym->offset + reloc_addend(reloc);
                insn = find_insn(file, reloc->sym->sec, offset);

                if (!insn) {
                        ERROR("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type);
                        return -1;
                }

                if (func(file, type, insn))
                        return -1;
        }

        return 0;
}

static int __annotate_early(struct objtool_file *file, int type, struct instruction *insn)
{
        switch (type) {

        /* Must be before add_special_section_alts() */
        case ANNOTYPE_IGNORE_ALTS:
                insn->ignore_alts = true;
                break;

        /*
         * Must be before read_unwind_hints() since that needs insn->noendbr.
         */
        case ANNOTYPE_NOENDBR:
                insn->noendbr = 1;
                break;

        default:
                break;
        }

        return 0;
}

static int __annotate_ifc(struct objtool_file *file, int type, struct instruction *insn)
{
        unsigned long dest_off;

        if (type != ANNOTYPE_INTRA_FUNCTION_CALL)
                return 0;

        if (insn->type != INSN_CALL) {
                ERROR_INSN(insn, "intra_function_call not a direct call");
                return -1;
        }

        /*
         * Treat intra-function CALLs as JMPs, but with a stack_op.
         * See add_call_destinations(), which strips stack_ops from
         * normal CALLs.
         */
        insn->type = INSN_JUMP_UNCONDITIONAL;

        dest_off = arch_jump_destination(insn);
        insn->jump_dest = find_insn(file, insn->sec, dest_off);
        if (!insn->jump_dest) {
                ERROR_INSN(insn, "can't find call dest at %s+0x%lx",
                           insn->sec->name, dest_off);
                return -1;
        }

        return 0;
}

static int __annotate_late(struct objtool_file *file, int type, struct instruction *insn)
{
        struct symbol *sym;

        switch (type) {
        case ANNOTYPE_NOENDBR:
                /* early */
                break;

        case ANNOTYPE_RETPOLINE_SAFE:
                if (insn->type != INSN_JUMP_DYNAMIC &&
                    insn->type != INSN_CALL_DYNAMIC &&
                    insn->type != INSN_RETURN &&
                    insn->type != INSN_NOP) {
                        ERROR_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
                        return -1;
                }

                insn->retpoline_safe = true;
                break;

        case ANNOTYPE_INSTR_BEGIN:
                insn->instr++;
                break;

        case ANNOTYPE_INSTR_END:
                insn->instr--;
                break;

        case ANNOTYPE_UNRET_BEGIN:
                insn->unret = 1;
                break;

        case ANNOTYPE_IGNORE_ALTS:
                /* early */
                break;

        case ANNOTYPE_INTRA_FUNCTION_CALL:
                /* ifc */
                break;

        case ANNOTYPE_REACHABLE:
                insn->dead_end = false;
                break;

        case ANNOTYPE_NOCFI:
                sym = insn->sym;
                if (!sym) {
                        ERROR_INSN(insn, "dodgy NOCFI annotation");
                        return -1;
                }
                insn->sym->nocfi = 1;
                break;

        default:
                ERROR_INSN(insn, "Unknown annotation type: %d", type);
                return -1;
        }

        return 0;
}

/*
 * Return true if name matches an instrumentation function, where calls to that
 * function from noinstr code can safely be removed, but compilers won't do so.
 */
static bool is_profiling_func(const char *name)
{
        /*
         * Many compilers cannot disable KCOV with a function attribute.
         */
        if (!strncmp(name, "__sanitizer_cov_", 16))
                return true;

        return false;
}

static int classify_symbols(struct objtool_file *file)
{
        struct symbol *func;
        size_t len;

        for_each_sym(file->elf, func) {
                if (is_notype_sym(func) && strstarts(func->name, ".L"))
                        func->local_label = true;

                if (!is_global_sym(func))
                        continue;

                if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
                             strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
                        func->static_call_tramp = true;

                if (arch_is_retpoline(func))
                        func->retpoline_thunk = true;

                if (arch_is_rethunk(func))
                        func->return_thunk = true;

                if (arch_is_embedded_insn(func))
                        func->embedded_insn = true;

                if (arch_ftrace_match(func->name))
                        func->fentry = true;

                if (is_profiling_func(func->name))
                        func->profiling_func = true;

                len = strlen(func->name);
                if (len > sym_name_max_len)
                        sym_name_max_len = len;
        }

        return 0;
}

static void mark_rodata(struct objtool_file *file)
{
        struct section *sec;
        bool found = false;

        /*
         * Search for the following rodata sections, each of which can
         * potentially contain jump tables:
         *
         * - .rodata: can contain GCC switch tables
         * - .rodata.<func>: same, if -fdata-sections is being used
         * - .data.rel.ro.c_jump_table: contains C annotated jump tables
         *
         * .rodata.str1.* sections are ignored; they don't contain jump tables.
         */
        for_each_sec(file->elf, sec) {
                if ((!strncmp(sec->name, ".rodata", 7) &&
                     !strstr(sec->name, ".str1.")) ||
                    !strncmp(sec->name, ".data.rel.ro", 12)) {
                        sec->rodata = true;
                        found = true;
                }
        }

        file->rodata = found;
}

static void mark_holes(struct objtool_file *file)
{
        struct instruction *insn;
        bool in_hole = false;

        if (!opts.link)
                return;

        /*
         * Whole archive runs might encounter dead code from weak symbols.
         * This is where the linker will have dropped the weak symbol in
         * favour of a regular symbol, but leaves the code in place.
         */
        for_each_insn(file, insn) {
                if (insn->sym || !find_symbol_hole_containing(insn->sec, insn->offset)) {
                        in_hole = false;
                        continue;
                }

                /* Skip function padding and pfx code */
                if (!in_hole && insn->type == INSN_NOP)
                        continue;

                in_hole = true;
                insn->hole = 1;

                /*
                 * If this hole jumps to a .cold function, mark it ignore.
                 */
                if (insn->jump_dest) {
                        struct symbol *dest_func = insn_func(insn->jump_dest);

                        if (dest_func && dest_func->cold)
                                dest_func->ignore = true;
                }
        }
}

static bool validate_branch_enabled(void)
{
        return opts.stackval ||
               opts.orc ||
               opts.uaccess ||
               opts.checksum;
}

static int decode_sections(struct objtool_file *file)
{
        file->klp = is_livepatch_module(file);

        mark_rodata(file);

        if (init_pv_ops(file))
                return -1;

        /*
         * Must be before add_{jump_call}_destination.
         */
        if (classify_symbols(file))
                return -1;

        if (decode_instructions(file))
                return -1;

        if (add_ignores(file))
                return -1;

        add_uaccess_safe(file);

        if (read_annotate(file, __annotate_early))
                return -1;

        /*
         * Must be before add_jump_destinations(), which depends on 'func'
         * being set for alternatives, to enable proper sibling call detection.
         */
        if (validate_branch_enabled() || opts.noinstr || opts.hack_jump_label || opts.disas) {
                if (add_special_section_alts(file))
                        return -1;
        }

        if (add_jump_destinations(file))
                return -1;

        /*
         * Must be before add_call_destination(); it changes INSN_CALL to
         * INSN_JUMP.
         */
        if (read_annotate(file, __annotate_ifc))
                return -1;

        if (add_call_destinations(file))
                return -1;

        if (add_jump_table_alts(file))
                return -1;

        if (read_unwind_hints(file))
                return -1;

        /* Must be after add_jump_destinations() */
        mark_holes(file);

        /*
         * Must be after add_call_destinations() such that it can override
         * dead_end_function() marks.
         */
        if (read_annotate(file, __annotate_late))
                return -1;

        return 0;
}

static bool is_special_call(struct instruction *insn)
{
        if (insn->type == INSN_CALL) {
                struct symbol *dest = insn_call_dest(insn);

                if (!dest)
                        return false;

                if (dest->fentry || dest->embedded_insn)
                        return true;
        }

        return false;
}

static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
{
        struct cfi_state *cfi = &state->cfi;
        int i;

        if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
                return true;

        if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
                return true;

        if (cfi->stack_size != initial_func_cfi.cfa.offset)
                return true;

        for (i = 0; i < CFI_NUM_REGS; i++) {
                if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
                    cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
                        return true;
        }

        return false;
}

static bool check_reg_frame_pos(const struct cfi_reg *reg,
                                int expected_offset)
{
        return reg->base == CFI_CFA &&
               reg->offset == expected_offset;
}

static bool has_valid_stack_frame(struct insn_state *state)
{
        struct cfi_state *cfi = &state->cfi;

        if (cfi->cfa.base == CFI_BP &&
            check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
            check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
                return true;

        if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
                return true;

        return false;
}

static int update_cfi_state_regs(struct instruction *insn,
                                  struct cfi_state *cfi,
                                  struct stack_op *op)
{
        struct cfi_reg *cfa = &cfi->cfa;

        if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
                return 0;

        /* push */
        if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
                cfa->offset += 8;

        /* pop */
        if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
                cfa->offset -= 8;

        /* add immediate to sp */
        if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
            op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
                cfa->offset -= op->src.offset;

        return 0;
}

static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
{
        if (arch_callee_saved_reg(reg) &&
            cfi->regs[reg].base == CFI_UNDEFINED) {
                cfi->regs[reg].base = base;
                cfi->regs[reg].offset = offset;
        }
}

static void restore_reg(struct cfi_state *cfi, unsigned char reg)
{
        cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
        cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
}

/*
 * A note about DRAP stack alignment:
 *
 * GCC has the concept of a DRAP register, which is used to help keep track of
 * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
 * register.  The typical DRAP pattern is:
 *
 *   4c 8d 54 24 08             lea    0x8(%rsp),%r10
 *   48 83 e4 c0                and    $0xffffffffffffffc0,%rsp
 *   41 ff 72 f8                pushq  -0x8(%r10)
 *   55                         push   %rbp
 *   48 89 e5                   mov    %rsp,%rbp
 *                              (more pushes)
 *   41 52                      push   %r10
 *                              ...
 *   41 5a                      pop    %r10
 *                              (more pops)
 *   5d                         pop    %rbp
 *   49 8d 62 f8                lea    -0x8(%r10),%rsp
 *   c3                         retq
 *
 * There are some variations in the epilogues, like:
 *
 *   5b                         pop    %rbx
 *   41 5a                      pop    %r10
 *   41 5c                      pop    %r12
 *   41 5d                      pop    %r13
 *   41 5e                      pop    %r14
 *   c9                         leaveq
 *   49 8d 62 f8                lea    -0x8(%r10),%rsp
 *   c3                         retq
 *
 * and:
 *
 *   4c 8b 55 e8                mov    -0x18(%rbp),%r10
 *   48 8b 5d e0                mov    -0x20(%rbp),%rbx
 *   4c 8b 65 f0                mov    -0x10(%rbp),%r12
 *   4c 8b 6d f8                mov    -0x8(%rbp),%r13
 *   c9                         leaveq
 *   49 8d 62 f8                lea    -0x8(%r10),%rsp
 *   c3                         retq
 *
 * Sometimes r13 is used as the DRAP register, in which case it's saved and
 * restored beforehand:
 *
 *   41 55                      push   %r13
 *   4c 8d 6c 24 10             lea    0x10(%rsp),%r13
 *   48 83 e4 f0                and    $0xfffffffffffffff0,%rsp
 *                              ...
 *   49 8d 65 f0                lea    -0x10(%r13),%rsp
 *   41 5d                      pop    %r13
 *   c3                         retq
 */
static int update_cfi_state(struct instruction *insn,
                            struct instruction *next_insn,
                            struct cfi_state *cfi, struct stack_op *op)
{
        struct cfi_reg *cfa = &cfi->cfa;
        struct cfi_reg *regs = cfi->regs;

        /* ignore UNWIND_HINT_UNDEFINED regions */
        if (cfi->force_undefined)
                return 0;

        /* stack operations don't make sense with an undefined CFA */
        if (cfa->base == CFI_UNDEFINED) {
                if (insn_func(insn)) {
                        WARN_INSN(insn, "undefined stack state");
                        return 1;
                }
                return 0;
        }

        if (cfi->type == UNWIND_HINT_TYPE_REGS ||
            cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
                return update_cfi_state_regs(insn, cfi, op);

        switch (op->dest.type) {

        case OP_DEST_REG:
                switch (op->src.type) {

                case OP_SRC_REG:
                        if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
                            cfa->base == CFI_SP &&
                            check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {

                                /* mov %rsp, %rbp */
                                cfa->base = op->dest.reg;
                                cfi->bp_scratch = false;
                        }

                        else if (op->src.reg == CFI_SP &&
                                 op->dest.reg == CFI_BP && cfi->drap) {

                                /* drap: mov %rsp, %rbp */
                                regs[CFI_BP].base = CFI_BP;
                                regs[CFI_BP].offset = -cfi->stack_size;
                                cfi->bp_scratch = false;
                        }

                        else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {

                                /*
                                 * mov %rsp, %reg
                                 *
                                 * This is needed for the rare case where GCC
                                 * does:
                                 *
                                 *   mov    %rsp, %rax
                                 *   ...
                                 *   mov    %rax, %rsp
                                 */
                                cfi->vals[op->dest.reg].base = CFI_CFA;
                                cfi->vals[op->dest.reg].offset = -cfi->stack_size;
                        }

                        else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
                                 (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {

                                /*
                                 * mov %rbp, %rsp
                                 *
                                 * Restore the original stack pointer (Clang).
                                 */
                                cfi->stack_size = -cfi->regs[CFI_BP].offset;
                        }

                        else if (op->dest.reg == cfa->base) {

                                /* mov %reg, %rsp */
                                if (cfa->base == CFI_SP &&
                                    cfi->vals[op->src.reg].base == CFI_CFA) {

                                        /*
                                         * This is needed for the rare case
                                         * where GCC does something dumb like:
                                         *
                                         *   lea    0x8(%rsp), %rcx
                                         *   ...
                                         *   mov    %rcx, %rsp
                                         */
                                        cfa->offset = -cfi->vals[op->src.reg].offset;
                                        cfi->stack_size = cfa->offset;

                                } else if (cfa->base == CFI_SP &&
                                           cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
                                           cfi->vals[op->src.reg].offset == cfa->offset) {

                                        /*
                                         * Stack swizzle:
                                         *
                                         * 1: mov %rsp, (%[tos])
                                         * 2: mov %[tos], %rsp
                                         *    ...
                                         * 3: pop %rsp
                                         *
                                         * Where:
                                         *
                                         * 1 - places a pointer to the previous
                                         *     stack at the Top-of-Stack of the
                                         *     new stack.
                                         *
                                         * 2 - switches to the new stack.
                                         *
                                         * 3 - pops the Top-of-Stack to restore
                                         *     the original stack.
                                         *
                                         * Note: we set base to SP_INDIRECT
                                         * here and preserve offset. Therefore
                                         * when the unwinder reaches ToS it
                                         * will dereference SP and then add the
                                         * offset to find the next frame, IOW:
                                         * (%rsp) + offset.
                                         */
                                        cfa->base = CFI_SP_INDIRECT;

                                } else {
                                        cfa->base = CFI_UNDEFINED;
                                        cfa->offset = 0;
                                }
                        }

                        else if (op->dest.reg == CFI_SP &&
                                 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
                                 cfi->vals[op->src.reg].offset == cfa->offset) {

                                /*
                                 * The same stack swizzle case 2) as above. But
                                 * because we can't change cfa->base, case 3)
                                 * will become a regular POP. Pretend we're a
                                 * PUSH so things don't go unbalanced.
                                 */
                                cfi->stack_size += 8;
                        }

                        else if (cfi->vals[op->src.reg].base == CFI_CFA) {
                                /*
                                 * Clang RSP musical chairs:
                                 *
                                 *   mov %rsp, %rdx [handled above]
                                 *   ...
                                 *   mov %rdx, %rbx [handled here]
                                 *   ...
                                 *   mov %rbx, %rsp [handled above]
                                 */
                                cfi->vals[op->dest.reg].base = CFI_CFA;
                                cfi->vals[op->dest.reg].offset = cfi->vals[op->src.reg].offset;
                        }


                        break;

                case OP_SRC_ADD:
                        if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {

                                /* add imm, %rsp */
                                cfi->stack_size -= op->src.offset;
                                if (cfa->base == CFI_SP)
                                        cfa->offset -= op->src.offset;
                                break;
                        }

                        if (op->dest.reg == CFI_BP && op->src.reg == CFI_SP &&
                            insn->sym->frame_pointer) {
                                /* addi.d fp,sp,imm on LoongArch */
                                if (cfa->base == CFI_SP && cfa->offset == op->src.offset) {
                                        cfa->base = CFI_BP;
                                        cfa->offset = 0;
                                }
                                break;
                        }

                        if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
                                /* addi.d sp,fp,imm on LoongArch */
                                if (cfa->base == CFI_BP && cfa->offset == 0) {
                                        if (insn->sym->frame_pointer) {
                                                cfa->base = CFI_SP;
                                                cfa->offset = -op->src.offset;
                                        }
                                } else {
                                        /* lea disp(%rbp), %rsp */
                                        cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
                                }
                                break;
                        }

                        if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {

                                /* drap: lea disp(%rsp), %drap */
                                cfi->drap_reg = op->dest.reg;

                                /*
                                 * lea disp(%rsp), %reg
                                 *
                                 * This is needed for the rare case where GCC
                                 * does something dumb like:
                                 *
                                 *   lea    0x8(%rsp), %rcx
                                 *   ...
                                 *   mov    %rcx, %rsp
                                 */
                                cfi->vals[op->dest.reg].base = CFI_CFA;
                                cfi->vals[op->dest.reg].offset = \
                                        -cfi->stack_size + op->src.offset;

                                break;
                        }

                        if (cfi->drap && op->dest.reg == CFI_SP &&
                            op->src.reg == cfi->drap_reg) {

                                 /* drap: lea disp(%drap), %rsp */
                                cfa->base = CFI_SP;
                                cfa->offset = cfi->stack_size = -op->src.offset;
                                cfi->drap_reg = CFI_UNDEFINED;
                                cfi->drap = false;
                                break;
                        }

                        if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
                                WARN_INSN(insn, "unsupported stack register modification");
                                return -1;
                        }

                        break;

                case OP_SRC_AND:
                        if (op->dest.reg != CFI_SP ||
                            (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
                            (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
                                WARN_INSN(insn, "unsupported stack pointer realignment");
                                return -1;
                        }

                        if (cfi->drap_reg != CFI_UNDEFINED) {
                                /* drap: and imm, %rsp */
                                cfa->base = cfi->drap_reg;
                                cfa->offset = cfi->stack_size = 0;
                                cfi->drap = true;
                        }

                        /*
                         * Older versions of GCC (4.8ish) realign the stack
                         * without DRAP, with a frame pointer.
                         */

                        break;

                case OP_SRC_POP:
                case OP_SRC_POPF:
                        if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {

                                /* pop %rsp; # restore from a stack swizzle */
                                cfa->base = CFI_SP;
                                break;
                        }

                        if (!cfi->drap && op->dest.reg == cfa->base) {

                                /* pop %rbp */
                                cfa->base = CFI_SP;
                        }

                        if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
                            op->dest.reg == cfi->drap_reg &&
                            cfi->drap_offset == -cfi->stack_size) {

                                /* drap: pop %drap */
                                cfa->base = cfi->drap_reg;
                                cfa->offset = 0;
                                cfi->drap_offset = -1;

                        } else if (cfi->stack_size == -regs[op->dest.reg].offset) {

                                /* pop %reg */
                                restore_reg(cfi, op->dest.reg);
                        }

                        cfi->stack_size -= 8;
                        if (cfa->base == CFI_SP)
                                cfa->offset -= 8;

                        break;

                case OP_SRC_REG_INDIRECT:
                        if (!cfi->drap && op->dest.reg == cfa->base &&
                            op->dest.reg == CFI_BP) {

                                /* mov disp(%rsp), %rbp */
                                cfa->base = CFI_SP;
                                cfa->offset = cfi->stack_size;
                        }

                        if (cfi->drap && op->src.reg == CFI_BP &&
                            op->src.offset == cfi->drap_offset) {

                                /* drap: mov disp(%rbp), %drap */
                                cfa->base = cfi->drap_reg;
                                cfa->offset = 0;
                                cfi->drap_offset = -1;
                        }

                        if (cfi->drap && op->src.reg == CFI_BP &&
                            op->src.offset == regs[op->dest.reg].offset) {

                                /* drap: mov disp(%rbp), %reg */
                                restore_reg(cfi, op->dest.reg);

                        } else if (op->src.reg == cfa->base &&
                            op->src.offset == regs[op->dest.reg].offset + cfa->offset) {

                                /* mov disp(%rbp), %reg */
                                /* mov disp(%rsp), %reg */
                                restore_reg(cfi, op->dest.reg);

                        } else if (op->src.reg == CFI_SP &&
                                   op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {

                                /* mov disp(%rsp), %reg */
                                restore_reg(cfi, op->dest.reg);
                        }

                        break;

                default:
                        WARN_INSN(insn, "unknown stack-related instruction");
                        return -1;
                }

                break;

        case OP_DEST_PUSH:
        case OP_DEST_PUSHF:
                cfi->stack_size += 8;
                if (cfa->base == CFI_SP)
                        cfa->offset += 8;

                if (op->src.type != OP_SRC_REG)
                        break;

                if (cfi->drap) {
                        if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {

                                /* drap: push %drap */
                                cfa->base = CFI_BP_INDIRECT;
                                cfa->offset = -cfi->stack_size;

                                /* save drap so we know when to restore it */
                                cfi->drap_offset = -cfi->stack_size;

                        } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {

                                /* drap: push %rbp */
                                cfi->stack_size = 0;

                        } else {

                                /* drap: push %reg */
                                save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
                        }

                } else {

                        /* push %reg */
                        save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
                }

                /* detect when asm code uses rbp as a scratch register */
                if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&
                    cfa->base != CFI_BP)
                        cfi->bp_scratch = true;
                break;

        case OP_DEST_REG_INDIRECT:

                if (cfi->drap) {
                        if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {

                                /* drap: mov %drap, disp(%rbp) */
                                cfa->base = CFI_BP_INDIRECT;
                                cfa->offset = op->dest.offset;

                                /* save drap offset so we know when to restore it */
                                cfi->drap_offset = op->dest.offset;
                        } else {

                                /* drap: mov reg, disp(%rbp) */
                                save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
                        }

                } else if (op->dest.reg == cfa->base) {

                        /* mov reg, disp(%rbp) */
                        /* mov reg, disp(%rsp) */
                        save_reg(cfi, op->src.reg, CFI_CFA,
                                 op->dest.offset - cfi->cfa.offset);

                } else if (op->dest.reg == CFI_SP) {

                        /* mov reg, disp(%rsp) */
                        save_reg(cfi, op->src.reg, CFI_CFA,
                                 op->dest.offset - cfi->stack_size);

                } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {

                        /* mov %rsp, (%reg); # setup a stack swizzle. */
                        cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
                        cfi->vals[op->dest.reg].offset = cfa->offset;
                }

                break;

        case OP_DEST_MEM:
                if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
                        WARN_INSN(insn, "unknown stack-related memory operation");
                        return -1;
                }

                /* pop mem */
                cfi->stack_size -= 8;
                if (cfa->base == CFI_SP)
                        cfa->offset -= 8;

                break;

        default:
                WARN_INSN(insn, "unknown stack-related instruction");
                return -1;
        }

        return 0;
}

/*
 * The stack layouts of alternatives instructions can sometimes diverge when
 * they have stack modifications.  That's fine as long as the potential stack
 * layouts don't conflict at any given potential instruction boundary.
 *
 * Flatten the CFIs of the different alternative code streams (both original
 * and replacement) into a single shared CFI array which can be used to detect
 * conflicts and nicely feed a linear array of ORC entries to the unwinder.
 */
static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
{
        struct cfi_state **alt_cfi;
        int group_off;

        if (!insn->alt_group)
                return 0;

        if (!insn->cfi) {
                WARN("CFI missing");
                return -1;
        }

        alt_cfi = insn->alt_group->cfi;
        group_off = insn->offset - insn->alt_group->first_insn->offset;

        if (!alt_cfi[group_off]) {
                alt_cfi[group_off] = insn->cfi;
        } else {
                if (cficmp(alt_cfi[group_off], insn->cfi)) {
                        struct alt_group *orig_group = insn->alt_group->orig_group ?: insn->alt_group;
                        struct instruction *orig = orig_group->first_insn;
                        WARN_INSN(orig, "stack layout conflict in alternatives: %s",
                                  offstr(insn->sec, insn->offset));
                        return -1;
                }
        }

        return 0;
}

static int noinline handle_insn_ops(struct instruction *insn,
                                    struct instruction *next_insn,
                                    struct insn_state *state)
{
        struct insn_state prev_state __maybe_unused = *state;
        struct stack_op *op;
        int ret = 0;

        for (op = insn->stack_ops; op; op = op->next) {

                ret = update_cfi_state(insn, next_insn, &state->cfi, op);
                if (ret)
                        goto done;

                if (!opts.uaccess || !insn->alt_group)
                        continue;

                if (op->dest.type == OP_DEST_PUSHF) {
                        if (!state->uaccess_stack) {
                                state->uaccess_stack = 1;
                        } else if (state->uaccess_stack >> 31) {
                                WARN_INSN(insn, "PUSHF stack exhausted");
                                ret = 1;
                                goto done;
                        }
                        state->uaccess_stack <<= 1;
                        state->uaccess_stack  |= state->uaccess;
                }

                if (op->src.type == OP_SRC_POPF) {
                        if (state->uaccess_stack) {
                                state->uaccess = state->uaccess_stack & 1;
                                state->uaccess_stack >>= 1;
                                if (state->uaccess_stack == 1)
                                        state->uaccess_stack = 0;
                        }
                }
        }

done:
        TRACE_INSN_STATE(insn, &prev_state, state);

        return ret;
}

static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
{
        struct cfi_state *cfi1 = insn->cfi;
        int i;

        if (!cfi1) {
                WARN("CFI missing");
                return false;
        }

        if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {

                WARN_INSN(insn, "stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
                          cfi1->cfa.base, cfi1->cfa.offset,
                          cfi2->cfa.base, cfi2->cfa.offset);
                return false;

        }

        if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
                for (i = 0; i < CFI_NUM_REGS; i++) {

                        if (!memcmp(&cfi1->regs[i], &cfi2->regs[i], sizeof(struct cfi_reg)))
                                continue;

                        WARN_INSN(insn, "stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
                                  i, cfi1->regs[i].base, cfi1->regs[i].offset,
                                  i, cfi2->regs[i].base, cfi2->regs[i].offset);
                }
                return false;
        }

        if (cfi1->type != cfi2->type) {

                WARN_INSN(insn, "stack state mismatch: type1=%d type2=%d",
                          cfi1->type, cfi2->type);
                return false;
        }

        if (cfi1->drap != cfi2->drap ||
                   (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
                   (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {

                WARN_INSN(insn, "stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
                          cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
                          cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
                return false;
        }

        return true;
}

static inline bool func_uaccess_safe(struct symbol *func)
{
        if (func)
                return func->uaccess_safe;

        return false;
}

static inline const char *call_dest_name(struct instruction *insn)
{
        static char pvname[19];
        struct reloc *reloc;
        int idx;

        if (insn_call_dest(insn))
                return insn_call_dest(insn)->name;

        reloc = insn_reloc(NULL, insn);
        if (reloc && !strcmp(reloc->sym->name, "pv_ops")) {
                idx = (reloc_addend(reloc) / sizeof(void *));
                snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
                return pvname;
        }

        return "{dynamic}";
}

static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
{
        struct symbol *target;
        struct reloc *reloc;
        int idx;

        reloc = insn_reloc(file, insn);
        if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
                return false;

        idx = arch_insn_adjusted_addend(insn, reloc) / sizeof(void *);

        if (file->pv_ops[idx].clean)
                return true;

        file->pv_ops[idx].clean = true;

        list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
                if (!target->sec->noinstr) {
                        WARN("pv_ops[%d]: %s", idx, target->name);
                        file->pv_ops[idx].clean = false;
                }
        }

        return file->pv_ops[idx].clean;
}

static inline bool noinstr_call_dest(struct objtool_file *file,
                                     struct instruction *insn,
                                     struct symbol *func)
{
        /*
         * We can't deal with indirect function calls at present;
         * assume they're instrumented.
         */
        if (!func) {
                if (file->pv_ops)
                        return pv_call_dest(file, insn);

                return false;
        }

        /*
         * If the symbol is from a noinstr section; we good.
         */
        if (func->sec->noinstr)
                return true;

        /*
         * If the symbol is a static_call trampoline, we can't tell.
         */
        if (func->static_call_tramp)
                return true;

        /*
         * The __ubsan_handle_*() calls are like WARN(), they only happen when
         * something 'BAD' happened. At the risk of taking the machine down,
         * let them proceed to get the message out.
         */
        if (!strncmp(func->name, "__ubsan_handle_", 15))
                return true;

        return false;
}

static int validate_call(struct objtool_file *file,
                         struct instruction *insn,
                         struct insn_state *state)
{
        if (state->noinstr && state->instr <= 0 &&
            !noinstr_call_dest(file, insn, insn_call_dest(insn))) {
                WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(insn));
                return 1;
        }

        if (state->uaccess && !func_uaccess_safe(insn_call_dest(insn))) {
                WARN_INSN(insn, "call to %s() with UACCESS enabled", call_dest_name(insn));
                return 1;
        }

        if (state->df) {
                WARN_INSN(insn, "call to %s() with DF set", call_dest_name(insn));
                return 1;
        }

        return 0;
}

static int validate_sibling_call(struct objtool_file *file,
                                 struct instruction *insn,
                                 struct insn_state *state)
{
        if (insn_func(insn) && has_modified_stack_frame(insn, state)) {
                WARN_INSN(insn, "sibling call from callable instruction with modified stack frame");
                return 1;
        }

        return validate_call(file, insn, state);
}

static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
{
        if (state->noinstr && state->instr > 0) {
                WARN_INSN(insn, "return with instrumentation enabled");
                return 1;
        }

        if (state->uaccess && !func_uaccess_safe(func)) {
                WARN_INSN(insn, "return with UACCESS enabled");
                return 1;
        }

        if (!state->uaccess && func_uaccess_safe(func)) {
                WARN_INSN(insn, "return with UACCESS disabled from a UACCESS-safe function");
                return 1;
        }

        if (state->df) {
                WARN_INSN(insn, "return with DF set");
                return 1;
        }

        if (func && has_modified_stack_frame(insn, state)) {
                WARN_INSN(insn, "return with modified stack frame");
                return 1;
        }

        if (state->cfi.bp_scratch) {
                WARN_INSN(insn, "BP used as a scratch register");
                return 1;
        }

        return 0;
}

static struct instruction *next_insn_to_validate(struct objtool_file *file,
                                                 struct instruction *insn)
{
        struct alt_group *alt_group = insn->alt_group;

        /*
         * Simulate the fact that alternatives are patched in-place.  When the
         * end of a replacement alt_group is reached, redirect objtool flow to
         * the end of the original alt_group.
         *
         * insn->alts->insn -> alt_group->first_insn
         *                     ...
         *                     alt_group->last_insn
         *                     [alt_group->nop]      -> next(orig_group->last_insn)
         */
        if (alt_group) {
                if (alt_group->nop) {
                        /* ->nop implies ->orig_group */
                        if (insn == alt_group->last_insn)
                                return alt_group->nop;
                        if (insn == alt_group->nop)
                                goto next_orig;
                }
                if (insn == alt_group->last_insn && alt_group->orig_group)
                        goto next_orig;
        }

        return next_insn_same_sec(file, insn);

next_orig:
        return next_insn_same_sec(file, alt_group->orig_group->last_insn);
}

static bool skip_alt_group(struct instruction *insn)
{
        struct instruction *alt_insn = insn->alts ? insn->alts->insn : NULL;

        if (!insn->alt_group)
                return false;

        /* ANNOTATE_IGNORE_ALTERNATIVE */
        if (insn->alt_group->ignore) {
                TRACE_ALT(insn, "alt group ignored");
                return true;
        }

        /*
         * For NOP patched with CLAC/STAC, only follow the latter to avoid
         * impossible code paths combining patched CLAC with unpatched STAC
         * or vice versa.
         *
         * ANNOTATE_IGNORE_ALTERNATIVE could have been used here, but Linus
         * requested not to do that to avoid hurting .s file readability
         * around CLAC/STAC alternative sites.
         */

        if (!alt_insn)
                return false;

        /* Don't override ASM_{CLAC,STAC}_UNSAFE */
        if (alt_insn->alt_group && alt_insn->alt_group->ignore)
                return false;

        return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
}

static int checksum_debug_init(struct objtool_file *file)
{
        char *dup, *s;

        if (!opts.debug_checksum)
                return 0;

        dup = strdup(opts.debug_checksum);
        if (!dup) {
                ERROR_GLIBC("strdup");
                return -1;
        }

        s = dup;
        while (*s) {
                struct symbol *func;
                char *comma;

                comma = strchr(s, ',');
                if (comma)
                        *comma = '\0';

                func = find_symbol_by_name(file->elf, s);
                if (!func || !is_func_sym(func))
                        WARN("--debug-checksum: can't find '%s'", s);
                else
                        func->debug_checksum = 1;

                if (!comma)
                        break;

                s = comma + 1;
        }

        free(dup);
        return 0;
}

static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
                                 struct instruction *insn)
{
        struct reloc *reloc = insn_reloc(file, insn);
        unsigned long offset;
        struct symbol *sym;

        if (insn->fake)
                return;

        checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);

        if (!reloc) {
                struct symbol *call_dest = insn_call_dest(insn);

                if (call_dest)
                        checksum_update(func, insn, call_dest->demangled_name,
                                        strlen(call_dest->demangled_name));
                return;
        }

        sym = reloc->sym;
        offset = arch_insn_adjusted_addend(insn, reloc);

        if (is_string_sec(sym->sec)) {
                char *str;

                str = sym->sec->data->d_buf + sym->offset + offset;
                checksum_update(func, insn, str, strlen(str));
                return;
        }

        if (is_sec_sym(sym)) {
                sym = find_symbol_containing(reloc->sym->sec, offset);
                if (!sym)
                        return;

                offset -= sym->offset;
        }

        checksum_update(func, insn, sym->demangled_name, strlen(sym->demangled_name));
        checksum_update(func, insn, &offset, sizeof(offset));
}

static int validate_branch(struct objtool_file *file, struct symbol *func,
                           struct instruction *insn, struct insn_state state);
static int do_validate_branch(struct objtool_file *file, struct symbol *func,
                              struct instruction *insn, struct insn_state *state);

static int validate_insn(struct objtool_file *file, struct symbol *func,
                         struct instruction *insn, struct insn_state *statep,
                         struct instruction *prev_insn, struct instruction *next_insn,
                         bool *dead_end)
{
        char *alt_name __maybe_unused = NULL;
        struct alternative *alt;
        u8 visited;
        int ret;

        /*
         * Any returns before the end of this function are effectively dead
         * ends, i.e. validate_branch() has reached the end of the branch.
         */
        *dead_end = true;

        visited = VISITED_BRANCH << statep->uaccess;
        if (insn->visited & VISITED_BRANCH_MASK) {
                if (!insn->hint && !insn_cfi_match(insn, &statep->cfi))
                        return 1;

                if (insn->visited & visited) {
                        TRACE_INSN(insn, "already visited");
                        return 0;
                }
        } else {
                nr_insns_visited++;
        }

        if (statep->noinstr)
                statep->instr += insn->instr;

        if (insn->hint) {
                if (insn->restore) {
                        struct instruction *save_insn, *i;

                        i = insn;
                        save_insn = NULL;

                        sym_for_each_insn_continue_reverse(file, func, i) {
                                if (i->save) {
                                        save_insn = i;
                                        break;
                                }
                        }

                        if (!save_insn) {
                                WARN_INSN(insn, "no corresponding CFI save for CFI restore");
                                return 1;
                        }

                        if (!save_insn->visited) {
                                /*
                                 * If the restore hint insn is at the
                                 * beginning of a basic block and was
                                 * branched to from elsewhere, and the
                                 * save insn hasn't been visited yet,
                                 * defer following this branch for now.
                                 * It will be seen later via the
                                 * straight-line path.
                                 */
                                if (!prev_insn) {
                                        TRACE_INSN(insn, "defer restore");
                                        return 0;
                                }

                                WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo");
                                return 1;
                        }

                        insn->cfi = save_insn->cfi;
                        nr_cfi_reused++;
                }

                statep->cfi = *insn->cfi;
        } else {
                /* XXX track if we actually changed statep->cfi */

                if (prev_insn && !cficmp(prev_insn->cfi, &statep->cfi)) {
                        insn->cfi = prev_insn->cfi;
                        nr_cfi_reused++;
                } else {
                        insn->cfi = cfi_hash_find_or_add(&statep->cfi);
                }
        }

        insn->visited |= visited;

        if (propagate_alt_cfi(file, insn))
                return 1;

        if (insn->alts) {
                for (alt = insn->alts; alt; alt = alt->next) {
                        TRACE_ALT_BEGIN(insn, alt, alt_name);
                        ret = validate_branch(file, func, alt->insn, *statep);
                        TRACE_ALT_END(insn, alt, alt_name);
                        if (ret) {
                                BT_INSN(insn, "(alt)");
                                return ret;
                        }
                }
                TRACE_ALT_INFO_NOADDR(insn, "/ ", "DEFAULT");
        }

        if (skip_alt_group(insn))
                return 0;

        if (handle_insn_ops(insn, next_insn, statep))
                return 1;

        switch (insn->type) {

        case INSN_RETURN:
                TRACE_INSN(insn, "return");
                return validate_return(func, insn, statep);

        case INSN_CALL:
        case INSN_CALL_DYNAMIC:
                if (insn->type == INSN_CALL)
                        TRACE_INSN(insn, "call");
                else
                        TRACE_INSN(insn, "indirect call");

                ret = validate_call(file, insn, statep);
                if (ret)
                        return ret;

                if (opts.stackval && func && !is_special_call(insn) &&
                    !has_valid_stack_frame(statep)) {
                        WARN_INSN(insn, "call without frame pointer save/setup");
                        return 1;
                }

                break;

        case INSN_JUMP_CONDITIONAL:
        case INSN_JUMP_UNCONDITIONAL:
                if (is_sibling_call(insn)) {
                        TRACE_INSN(insn, "sibling call");
                        ret = validate_sibling_call(file, insn, statep);
                        if (ret)
                                return ret;

                } else if (insn->jump_dest) {
                        if (insn->type == INSN_JUMP_UNCONDITIONAL)
                                TRACE_INSN(insn, "unconditional jump");
                        else
                                TRACE_INSN(insn, "jump taken");

                        ret = validate_branch(file, func, insn->jump_dest, *statep);
                        if (ret) {
                                BT_INSN(insn, "(branch)");
                                return ret;
                        }
                }

                if (insn->type == INSN_JUMP_UNCONDITIONAL)
                        return 0;

                TRACE_INSN(insn, "jump not taken");
                break;

        case INSN_JUMP_DYNAMIC:
        case INSN_JUMP_DYNAMIC_CONDITIONAL:
                TRACE_INSN(insn, "indirect jump");
                if (is_sibling_call(insn)) {
                        ret = validate_sibling_call(file, insn, statep);
                        if (ret)
                                return ret;
                }

                if (insn->type == INSN_JUMP_DYNAMIC)
                        return 0;

                break;

        case INSN_SYSCALL:
                TRACE_INSN(insn, "syscall");
                if (func && (!next_insn || !next_insn->hint)) {
                        WARN_INSN(insn, "unsupported instruction in callable function");
                        return 1;
                }

                break;

        case INSN_SYSRET:
                TRACE_INSN(insn, "sysret");
                if (func && (!next_insn || !next_insn->hint)) {
                        WARN_INSN(insn, "unsupported instruction in callable function");
                        return 1;
                }

                return 0;

        case INSN_STAC:
                TRACE_INSN(insn, "stac");
                if (!opts.uaccess)
                        break;

                if (statep->uaccess) {
                        WARN_INSN(insn, "recursive UACCESS enable");
                        return 1;
                }

                statep->uaccess = true;
                break;

        case INSN_CLAC:
                TRACE_INSN(insn, "clac");
                if (!opts.uaccess)
                        break;

                if (!statep->uaccess && func) {
                        WARN_INSN(insn, "redundant UACCESS disable");
                        return 1;
                }

                if (func_uaccess_safe(func) && !statep->uaccess_stack) {
                        WARN_INSN(insn, "UACCESS-safe disables UACCESS");
                        return 1;
                }

                statep->uaccess = false;
                break;

        case INSN_STD:
                TRACE_INSN(insn, "std");
                if (statep->df) {
                        WARN_INSN(insn, "recursive STD");
                        return 1;
                }

                statep->df = true;
                break;

        case INSN_CLD:
                TRACE_INSN(insn, "cld");
                if (!statep->df && func) {
                        WARN_INSN(insn, "redundant CLD");
                        return 1;
                }

                statep->df = false;
                break;

        default:
                break;
        }

        if (insn->dead_end)
                TRACE_INSN(insn, "dead end");

        *dead_end = insn->dead_end;
        return 0;
}

/*
 * Follow the branch starting at the given instruction, and recursively follow
 * any other branches (jumps).  Meanwhile, track the frame pointer state at
 * each instruction and validate all the rules described in
 * tools/objtool/Documentation/objtool.txt.
 */
static int do_validate_branch(struct objtool_file *file, struct symbol *func,
                              struct instruction *insn, struct insn_state *state)
{
        struct instruction *next_insn, *prev_insn = NULL;
        bool dead_end;
        int ret;

        if (func && func->ignore)
                return 0;

        do {
                insn->trace = 0;
                next_insn = next_insn_to_validate(file, insn);

                if (opts.checksum && func && insn->sec)
                        checksum_update_insn(file, func, insn);

                if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
                        /* Ignore KCFI type preambles, which always fall through */
                        if (is_prefix_func(func))
                                return 0;

                        if (file->ignore_unreachables)
                                return 0;

                        WARN("%s() falls through to next function %s()",
                             func->name, insn_func(insn)->name);
                        func->warned = 1;

                        return 1;
                }

                ret = validate_insn(file, func, insn, state, prev_insn, next_insn,
                                    &dead_end);

                if (!insn->trace) {
                        if (ret)
                                TRACE_INSN(insn, "warning (%d)", ret);
                        else
                                TRACE_INSN(insn, NULL);
                }

                if (!dead_end && !next_insn) {
                        if (state->cfi.cfa.base == CFI_UNDEFINED)
                                return 0;
                        if (file->ignore_unreachables)
                                return 0;

                        WARN("%s%sunexpected end of section %s",
                             func ? func->name : "", func ? "(): " : "",
                             insn->sec->name);
                        return 1;
                }

                prev_insn = insn;
                insn = next_insn;

        } while (!dead_end);

        return ret;
}

static int validate_branch(struct objtool_file *file, struct symbol *func,
                           struct instruction *insn, struct insn_state state)
{
        int ret;

        trace_depth_inc();
        ret = do_validate_branch(file, func, insn, &state);
        trace_depth_dec();

        return ret;
}

static int validate_unwind_hint(struct objtool_file *file,
                                  struct instruction *insn,
                                  struct insn_state *state)
{
        if (insn->hint && !insn->visited) {
                struct symbol *func = insn_func(insn);
                int ret;

                if (opts.checksum)
                        checksum_init(func);

                ret = validate_branch(file, func, insn, *state);
                if (ret)
                        BT_INSN(insn, "<=== (hint)");
                return ret;
        }

        return 0;
}

static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
{
        struct instruction *insn;
        struct insn_state state;
        int warnings = 0;

        if (!file->hints)
                return 0;

        init_insn_state(file, &state, sec);

        if (sec) {
                sec_for_each_insn(file, sec, insn)
                        warnings += validate_unwind_hint(file, insn, &state);
        } else {
                for_each_insn(file, insn)
                        warnings += validate_unwind_hint(file, insn, &state);
        }

        return warnings;
}

/*
 * Validate rethunk entry constraint: must untrain RET before the first RET.
 *
 * Follow every branch (intra-function) and ensure VALIDATE_UNRET_END comes
 * before an actual RET instruction.
 */
static int validate_unret(struct objtool_file *file, struct instruction *insn)
{
        struct instruction *next, *dest;
        int ret;

        for (;;) {
                next = next_insn_to_validate(file, insn);

                if (insn->visited & VISITED_UNRET)
                        return 0;

                insn->visited |= VISITED_UNRET;

                if (insn->alts) {
                        struct alternative *alt;
                        for (alt = insn->alts; alt; alt = alt->next) {
                                ret = validate_unret(file, alt->insn);
                                if (ret) {
                                        BT_INSN(insn, "(alt)");
                                        return ret;
                                }
                        }
                }

                switch (insn->type) {

                case INSN_CALL_DYNAMIC:
                case INSN_JUMP_DYNAMIC:
                case INSN_JUMP_DYNAMIC_CONDITIONAL:
                        WARN_INSN(insn, "early indirect call");
                        return 1;

                case INSN_JUMP_UNCONDITIONAL:
                case INSN_JUMP_CONDITIONAL:
                        if (!is_sibling_call(insn)) {
                                if (!insn->jump_dest) {
                                        WARN_INSN(insn, "unresolved jump target after linking?!?");
                                        return 1;
                                }
                                ret = validate_unret(file, insn->jump_dest);
                                if (ret) {
                                        BT_INSN(insn, "(branch%s)",
                                                insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
                                        return ret;
                                }

                                if (insn->type == INSN_JUMP_UNCONDITIONAL)
                                        return 0;

                                break;
                        }

                        /* fallthrough */
                case INSN_CALL:
                        dest = find_insn(file, insn_call_dest(insn)->sec,
                                         insn_call_dest(insn)->offset);
                        if (!dest) {
                                WARN("Unresolved function after linking!?: %s",
                                     insn_call_dest(insn)->name);
                                return 1;
                        }

                        ret = validate_unret(file, dest);
                        if (ret) {
                                BT_INSN(insn, "(call)");
                                return ret;
                        }
                        /*
                         * If a call returns without error, it must have seen UNTRAIN_RET.
                         * Therefore any non-error return is a success.
                         */
                        return 0;

                case INSN_RETURN:
                        WARN_INSN(insn, "RET before UNTRAIN");
                        return 1;

                case INSN_SYSCALL:
                        break;

                case INSN_SYSRET:
                        return 0;

                case INSN_NOP:
                        if (insn->retpoline_safe)
                                return 0;
                        break;

                default:
                        break;
                }

                if (insn->dead_end)
                        return 0;

                if (!next) {
                        WARN_INSN(insn, "teh end!");
                        return 1;
                }
                insn = next;
        }

        return 0;
}

/*
 * Validate that all branches starting at VALIDATE_UNRET_BEGIN encounter
 * VALIDATE_UNRET_END before RET.
 */
static int validate_unrets(struct objtool_file *file)
{
        struct instruction *insn;
        int warnings = 0;

        for_each_insn(file, insn) {
                if (!insn->unret)
                        continue;

                warnings += validate_unret(file, insn);
        }

        return warnings;
}

static int validate_retpoline(struct objtool_file *file)
{
        struct instruction *insn;
        int warnings = 0;

        for_each_insn(file, insn) {
                if (insn->type != INSN_JUMP_DYNAMIC &&
                    insn->type != INSN_CALL_DYNAMIC &&
                    insn->type != INSN_RETURN)
                        continue;

                if (insn->retpoline_safe)
                        continue;

                if (insn->sec->init)
                        continue;

                if (insn->type == INSN_RETURN) {
                        if (opts.rethunk) {
                                WARN_INSN(insn, "'naked' return found in MITIGATION_RETHUNK build");
                                warnings++;
                        }
                        continue;
                }

                WARN_INSN(insn, "indirect %s found in MITIGATION_RETPOLINE build",
                          insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
                warnings++;
        }

        if (!opts.cfi)
                return warnings;

        /*
         * kCFI call sites look like:
         *
         *     movl $(-0x12345678), %r10d
         *     addl -4(%r11), %r10d
         *     jz 1f
         *     ud2
         *  1: cs call __x86_indirect_thunk_r11
         *
         * Verify all indirect calls are kCFI adorned by checking for the
         * UD2. Notably, doing __nocfi calls to regular (cfi) functions is
         * broken.
         */
        list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
                struct symbol *sym = insn->sym;

                if (sym && (sym->type == STT_NOTYPE ||
                            sym->type == STT_FUNC) && !sym->nocfi) {
                        struct instruction *prev =
                                prev_insn_same_sym(file, insn);

                        if (!prev || prev->type != INSN_BUG) {
                                WARN_INSN(insn, "no-cfi indirect call!");
                                warnings++;
                        }
                }
        }

        return warnings;
}

static bool is_kasan_insn(struct instruction *insn)
{
        return (insn->type == INSN_CALL &&
                !strcmp(insn_call_dest(insn)->name, "__asan_handle_no_return"));
}

static bool is_ubsan_insn(struct instruction *insn)
{
        return (insn->type == INSN_CALL &&
                !strcmp(insn_call_dest(insn)->name,
                        "__ubsan_handle_builtin_unreachable"));
}

static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
{
        struct symbol *func = insn_func(insn);
        struct instruction *prev_insn;
        int i;

        if (insn->type == INSN_NOP || insn->type == INSN_TRAP ||
            insn->hole || (func && func->ignore))
                return true;

        /*
         * Ignore alternative replacement instructions.  This can happen
         * when a whitelisted function uses one of the ALTERNATIVE macros.
         */
        if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
            !strcmp(insn->sec->name, ".altinstr_aux"))
                return true;

        if (!func)
                return false;

        if (func->static_call_tramp)
                return true;

        /*
         * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
         * __builtin_unreachable().  The BUG() macro has an unreachable() after
         * the UD2, which causes GCC's undefined trap logic to emit another UD2
         * (or occasionally a JMP to UD2).
         *
         * It may also insert a UD2 after calling a __noreturn function.
         */
        prev_insn = prev_insn_same_sec(file, insn);
        if (prev_insn && prev_insn->dead_end &&
            (insn->type == INSN_BUG ||
             (insn->type == INSN_JUMP_UNCONDITIONAL &&
              insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
                return true;

        /*
         * Check if this (or a subsequent) instruction is related to
         * CONFIG_UBSAN or CONFIG_KASAN.
         *
         * End the search at 5 instructions to avoid going into the weeds.
         */
        for (i = 0; i < 5; i++) {

                if (is_kasan_insn(insn) || is_ubsan_insn(insn))
                        return true;

                if (insn->type == INSN_JUMP_UNCONDITIONAL) {
                        if (insn->jump_dest &&
                            insn_func(insn->jump_dest) == func) {
                                insn = insn->jump_dest;
                                continue;
                        }

                        break;
                }

                if (insn->offset + insn->len >= func->offset + func->len)
                        break;

                insn = next_insn_same_sec(file, insn);
        }

        return false;
}

/*
 * For FineIBT or kCFI, a certain number of bytes preceding the function may be
 * NOPs.  Those NOPs may be rewritten at runtime and executed, so give them a
 * proper function name: __pfx_<func>.
 *
 * The NOPs may not exist for the following cases:
 *
 *   - compiler cloned functions (*.cold, *.part0, etc)
 *   - asm functions created with inline asm or without SYM_FUNC_START()
 *
 * Also, the function may already have a prefix from a previous objtool run
 * (livepatch extracted functions, or manually running objtool multiple times).
 *
 * So return 0 if the NOPs are missing or the function already has a prefix
 * symbol.
 */
static int create_prefix_symbol(struct objtool_file *file, struct symbol *func)
{
        struct instruction *insn, *prev;
        char name[SYM_NAME_LEN];
        struct cfi_state *cfi;

        if (!is_func_sym(func) || is_prefix_func(func) ||
            func->cold || func->static_call_tramp)
                return 0;

        if ((strlen(func->name) + sizeof("__pfx_") > SYM_NAME_LEN)) {
                WARN("%s: symbol name too long, can't create __pfx_ symbol",
                      func->name);
                return 0;
        }

        if (snprintf_check(name, SYM_NAME_LEN, "__pfx_%s", func->name))
                return -1;

        if (file->klp) {
                struct symbol *pfx;

                pfx = find_symbol_by_offset(func->sec, func->offset - opts.prefix);
                if (pfx && is_prefix_func(pfx) && !strcmp(pfx->name, name))
                        return 0;
        }

        insn = find_insn(file, func->sec, func->offset);
        if (!insn) {
                WARN("%s: can't find starting instruction", func->name);
                return -1;
        }

        for (prev = prev_insn_same_sec(file, insn);
             prev;
             prev = prev_insn_same_sec(file, prev)) {
                u64 offset;

                if (prev->type != INSN_NOP)
                        return 0;

                offset = func->offset - prev->offset;

                if (offset > opts.prefix)
                        return 0;

                if (offset < opts.prefix)
                        continue;

                if (!elf_create_symbol(file->elf, name, func->sec,
                                       GELF_ST_BIND(func->sym.st_info),
                                       GELF_ST_TYPE(func->sym.st_info),
                                       prev->offset, opts.prefix))
                        return -1;

                break;
        }

        if (!prev)
                return 0;

        if (!insn->cfi) {
                /*
                 * This can happen if stack validation isn't enabled or the
                 * function is annotated with STACK_FRAME_NON_STANDARD.
                 */
                return 0;
        }

        /* Propagate insn->cfi to the prefix code */
        cfi = cfi_hash_find_or_add(insn->cfi);
        for (; prev != insn; prev = next_insn_same_sec(file, prev))
                prev->cfi = cfi;

        return 0;
}

static int create_prefix_symbols(struct objtool_file *file)
{
        struct section *sec;
        struct symbol *func;

        for_each_sec(file->elf, sec) {
                if (!is_text_sec(sec))
                        continue;

                sec_for_each_sym(sec, func) {
                        if (create_prefix_symbol(file, func))
                                return -1;
                }
        }

        return 0;
}

static int validate_symbol(struct objtool_file *file, struct section *sec,
                           struct symbol *sym, struct insn_state *state)
{
        struct instruction *insn;
        struct symbol *func;
        int ret;

        if (!sym->len) {
                WARN("%s() is missing an ELF size annotation", sym->name);
                return 1;
        }

        if (sym->pfunc != sym || sym->alias != sym)
                return 0;

        insn = find_insn(file, sec, sym->offset);
        if (!insn || insn->visited)
                return 0;

        if (opts.uaccess)
                state->uaccess = sym->uaccess_safe;

        func = insn_func(insn);

        if (opts.checksum)
                checksum_init(func);

        if (opts.trace && !fnmatch(opts.trace, sym->name, 0)) {
                trace_enable();
                TRACE("%s: validation begin\n", sym->name);
        }

        ret = validate_branch(file, func, insn, *state);
        if (ret)
                BT_INSN(insn, "<=== (sym)");

        TRACE("%s: validation %s\n\n", sym->name, ret ? "failed" : "end");
        trace_disable();

        if (opts.checksum)
                checksum_finish(func);

        return ret;
}

static int validate_section(struct objtool_file *file, struct section *sec)
{
        struct insn_state state;
        struct symbol *func;
        int warnings = 0;

        sec_for_each_sym(sec, func) {
                if (!is_func_sym(func))
                        continue;

                init_insn_state(file, &state, sec);
                set_func_state(&state.cfi);

                warnings += validate_symbol(file, sec, func, &state);
        }

        return warnings;
}

static int validate_noinstr_sections(struct objtool_file *file)
{
        struct section *sec;
        int warnings = 0;

        sec = find_section_by_name(file->elf, ".noinstr.text");
        if (sec) {
                warnings += validate_section(file, sec);
                warnings += validate_unwind_hints(file, sec);
        }

        sec = find_section_by_name(file->elf, ".entry.text");
        if (sec) {
                warnings += validate_section(file, sec);
                warnings += validate_unwind_hints(file, sec);
        }

        sec = find_section_by_name(file->elf, ".cpuidle.text");
        if (sec) {
                warnings += validate_section(file, sec);
                warnings += validate_unwind_hints(file, sec);
        }

        return warnings;
}

static int validate_functions(struct objtool_file *file)
{
        struct section *sec;
        int warnings = 0;

        for_each_sec(file->elf, sec) {
                if (!is_text_sec(sec))
                        continue;

                warnings += validate_section(file, sec);
        }

        return warnings;
}

static void mark_endbr_used(struct instruction *insn)
{
        if (!list_empty(&insn->call_node))
                list_del_init(&insn->call_node);
}

static bool noendbr_range(struct objtool_file *file, struct instruction *insn)
{
        struct symbol *sym = find_symbol_containing(insn->sec, insn->offset-1);
        struct instruction *first;

        if (!sym)
                return false;

        first = find_insn(file, sym->sec, sym->offset);
        if (!first)
                return false;

        if (first->type != INSN_ENDBR && !first->noendbr)
                return false;

        return insn->offset == sym->offset + sym->len;
}

static int __validate_ibt_insn(struct objtool_file *file, struct instruction *insn,
                               struct instruction *dest)
{
        if (dest->type == INSN_ENDBR) {
                mark_endbr_used(dest);
                return 0;
        }

        if (insn_func(dest) && insn_func(insn) &&
            insn_func(dest)->pfunc == insn_func(insn)->pfunc) {
                /*
                 * Anything from->to self is either _THIS_IP_ or
                 * IRET-to-self.
                 *
                 * There is no sane way to annotate _THIS_IP_ since the
                 * compiler treats the relocation as a constant and is
                 * happy to fold in offsets, skewing any annotation we
                 * do, leading to vast amounts of false-positives.
                 *
                 * There's also compiler generated _THIS_IP_ through
                 * KCOV and such which we have no hope of annotating.
                 *
                 * As such, blanket accept self-references without
                 * issue.
                 */
                return 0;
        }

        /*
         * Accept anything ANNOTATE_NOENDBR.
         */
        if (dest->noendbr)
                return 0;

        /*
         * Accept if this is the instruction after a symbol
         * that is (no)endbr -- typical code-range usage.
         */
        if (noendbr_range(file, dest))
                return 0;

        WARN_INSN(insn, "relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));
        return 1;
}

static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
{
        struct instruction *dest;
        struct reloc *reloc;
        unsigned long off;
        int warnings = 0;

        /*
         * Looking for function pointer load relocations.  Ignore
         * direct/indirect branches:
         */
        switch (insn->type) {

        case INSN_CALL:
        case INSN_CALL_DYNAMIC:
        case INSN_JUMP_CONDITIONAL:
        case INSN_JUMP_UNCONDITIONAL:
        case INSN_JUMP_DYNAMIC:
        case INSN_JUMP_DYNAMIC_CONDITIONAL:
        case INSN_RETURN:
        case INSN_NOP:
                return 0;

        case INSN_LEA_RIP:
                if (!insn_reloc(file, insn)) {
                        /* local function pointer reference without reloc */

                        off = arch_jump_destination(insn);

                        dest = find_insn(file, insn->sec, off);
                        if (!dest) {
                                WARN_INSN(insn, "corrupt function pointer reference");
                                return 1;
                        }

                        return __validate_ibt_insn(file, insn, dest);
                }
                break;

        default:
                break;
        }

        for (reloc = insn_reloc(file, insn);
             reloc;
             reloc = find_reloc_by_dest_range(file->elf, insn->sec,
                                              reloc_offset(reloc) + 1,
                                              (insn->offset + insn->len) - (reloc_offset(reloc) + 1))) {

                off = reloc->sym->offset + arch_insn_adjusted_addend(insn, reloc);

                dest = find_insn(file, reloc->sym->sec, off);
                if (!dest)
                        continue;

                warnings += __validate_ibt_insn(file, insn, dest);
        }

        return warnings;
}

static int validate_ibt_data_reloc(struct objtool_file *file,
                                   struct reloc *reloc)
{
        struct instruction *dest;

        dest = find_insn(file, reloc->sym->sec,
                         reloc->sym->offset + reloc_addend(reloc));
        if (!dest)
                return 0;

        if (dest->type == INSN_ENDBR) {
                mark_endbr_used(dest);
                return 0;
        }

        if (dest->noendbr)
                return 0;

        WARN_FUNC(reloc->sec->base, reloc_offset(reloc),
                  "data relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));

        return 1;
}

/*
 * Validate IBT rules and remove used ENDBR instructions from the seal list.
 * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
 * NOPs) later, in create_ibt_endbr_seal_sections().
 */
static int validate_ibt(struct objtool_file *file)
{
        struct section *sec;
        struct reloc *reloc;
        struct instruction *insn;
        int warnings = 0;

        for_each_insn(file, insn)
                warnings += validate_ibt_insn(file, insn);

        for_each_sec(file->elf, sec) {

                /* Already done by validate_ibt_insn() */
                if (is_text_sec(sec))
                        continue;

                if (!sec->rsec)
                        continue;

                /*
                 * These sections can reference text addresses, but not with
                 * the intent to indirect branch to them.
                 */
                if ((!strncmp(sec->name, ".discard", 8) &&
                     strcmp(sec->name, ".discard.ibt_endbr_noseal"))    ||
                    !strncmp(sec->name, ".debug", 6)                    ||
                    !strcmp(sec->name, ".altinstructions")              ||
                    !strcmp(sec->name, ".ibt_endbr_seal")               ||
                    !strcmp(sec->name, ".kcfi_traps")                   ||
                    !strcmp(sec->name, ".orc_unwind_ip")                ||
                    !strcmp(sec->name, ".retpoline_sites")              ||
                    !strcmp(sec->name, ".smp_locks")                    ||
                    !strcmp(sec->name, ".static_call_sites")            ||
                    !strcmp(sec->name, "_error_injection_whitelist")    ||
                    !strcmp(sec->name, "_kprobe_blacklist")             ||
                    !strcmp(sec->name, "__bug_table")                   ||
                    !strcmp(sec->name, "__ex_table")                    ||
                    !strcmp(sec->name, "__jump_table")                  ||
                    !strcmp(sec->name, ".init.klp_funcs")               ||
                    !strcmp(sec->name, "__mcount_loc")                  ||
                    !strcmp(sec->name, ".llvm.call-graph-profile")      ||
                    !strcmp(sec->name, ".llvm_bb_addr_map")             ||
                    !strcmp(sec->name, "__tracepoints")                 ||
                    !strcmp(sec->name, ".return_sites")                 ||
                    !strcmp(sec->name, ".call_sites")                   ||
                    !strcmp(sec->name, "__patchable_function_entries"))
                        continue;

                for_each_reloc(sec->rsec, reloc)
                        warnings += validate_ibt_data_reloc(file, reloc);
        }

        return warnings;
}

static int validate_sls(struct objtool_file *file)
{
        struct instruction *insn, *next_insn;
        int warnings = 0;

        for_each_insn(file, insn) {
                next_insn = next_insn_same_sec(file, insn);

                if (insn->retpoline_safe)
                        continue;

                switch (insn->type) {
                case INSN_RETURN:
                        if (!next_insn || next_insn->type != INSN_TRAP) {
                                WARN_INSN(insn, "missing int3 after ret");
                                warnings++;
                        }

                        break;
                case INSN_JUMP_DYNAMIC:
                        if (!next_insn || next_insn->type != INSN_TRAP) {
                                WARN_INSN(insn, "missing int3 after indirect jump");
                                warnings++;
                        }
                        break;
                default:
                        break;
                }
        }

        return warnings;
}

static int validate_reachable_instructions(struct objtool_file *file)
{
        struct instruction *insn, *prev_insn;
        struct symbol *call_dest;
        int warnings = 0;

        if (file->ignore_unreachables)
                return 0;

        for_each_insn(file, insn) {
                if (insn->visited || ignore_unreachable_insn(file, insn))
                        continue;

                prev_insn = prev_insn_same_sec(file, insn);
                if (prev_insn && prev_insn->dead_end) {
                        call_dest = insn_call_dest(prev_insn);
                        if (call_dest) {
                                WARN_INSN(insn, "%s() missing __noreturn in .c/.h or NORETURN() in noreturns.h",
                                          call_dest->name);
                                warnings++;
                                continue;
                        }
                }

                WARN_INSN(insn, "unreachable instruction");
                warnings++;
        }

        return warnings;
}

__weak bool arch_absolute_reloc(struct elf *elf, struct reloc *reloc)
{
        unsigned int type = reloc_type(reloc);
        size_t sz = elf_addr_size(elf);

        return (sz == 8) ? (type == R_ABS64) : (type == R_ABS32);
}

static int check_abs_references(struct objtool_file *file)
{
        struct section *sec;
        struct reloc *reloc;
        int ret = 0;

        for_each_sec(file->elf, sec) {
                /* absolute references in non-loadable sections are fine */
                if (!(sec->sh.sh_flags & SHF_ALLOC))
                        continue;

                /* section must have an associated .rela section */
                if (!sec->rsec)
                        continue;

                /*
                 * Special case for compiler generated metadata that is not
                 * consumed until after boot.
                 */
                if (!strcmp(sec->name, "__patchable_function_entries"))
                        continue;

                for_each_reloc(sec->rsec, reloc) {
                        if (arch_absolute_reloc(file->elf, reloc)) {
                                WARN("section %s has absolute relocation at offset 0x%llx",
                                     sec->name, (unsigned long long)reloc_offset(reloc));
                                ret++;
                        }
                }
        }
        return ret;
}

struct insn_chunk {
        void *addr;
        struct insn_chunk *next;
};

/*
 * Reduce peak RSS usage by freeing insns memory before writing the ELF file,
 * which can trigger more allocations for .debug_* sections whose data hasn't
 * been read yet.
 */
static void free_insns(struct objtool_file *file)
{
        struct instruction *insn;
        struct insn_chunk *chunks = NULL, *chunk;

        for_each_insn(file, insn) {
                if (!insn->idx) {
                        chunk = malloc(sizeof(*chunk));
                        chunk->addr = insn;
                        chunk->next = chunks;
                        chunks = chunk;
                }
        }

        for (chunk = chunks; chunk; chunk = chunk->next)
                free(chunk->addr);
}

const char *objtool_disas_insn(struct instruction *insn)
{
        struct disas_context *dctx = objtool_disas_ctx;

        if (!dctx)
                return "";

        disas_insn(dctx, insn);
        return disas_result(dctx);
}

int check(struct objtool_file *file)
{
        struct disas_context *disas_ctx = NULL;
        int ret = 0, warnings = 0;

        /*
         * Create a disassembly context if we might disassemble any
         * instruction or function.
         */
        if (opts.verbose || opts.backtrace || opts.trace || opts.disas) {
                disas_ctx = disas_context_create(file);
                if (!disas_ctx) {
                        opts.disas = false;
                        opts.trace = false;
                }
                objtool_disas_ctx = disas_ctx;
        }

        arch_initial_func_cfi_state(&initial_func_cfi);
        init_cfi_state(&init_cfi);
        init_cfi_state(&func_cfi);
        set_func_state(&func_cfi);
        init_cfi_state(&force_undefined_cfi);
        force_undefined_cfi.force_undefined = true;

        if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3))) {
                ret = -1;
                goto out;
        }

        cfi_hash_add(&init_cfi);
        cfi_hash_add(&func_cfi);

        ret = checksum_debug_init(file);
        if (ret)
                goto out;

        ret = decode_sections(file);
        if (ret)
                goto out;

        if (!nr_insns)
                goto out;

        if (opts.retpoline)
                warnings += validate_retpoline(file);

        if (validate_branch_enabled()) {
                int w = 0;

                w += validate_functions(file);
                w += validate_unwind_hints(file, NULL);
                if (!w)
                        w += validate_reachable_instructions(file);

                warnings += w;

        } else if (opts.noinstr) {
                warnings += validate_noinstr_sections(file);
        }

        if (opts.unret) {
                /*
                 * Must be after validate_branch() and friends, it plays
                 * further games with insn->visited.
                 */
                warnings += validate_unrets(file);
        }

        if (opts.ibt)
                warnings += validate_ibt(file);

        if (opts.sls)
                warnings += validate_sls(file);

        if (opts.static_call) {
                ret = create_static_call_sections(file);
                if (ret)
                        goto out;
        }

        if (opts.retpoline) {
                ret = create_retpoline_sites_sections(file);
                if (ret)
                        goto out;
        }

        if (opts.cfi) {
                ret = create_cfi_sections(file);
                if (ret)
                        goto out;
        }

        if (opts.rethunk) {
                ret = create_return_sites_sections(file);
                if (ret)
                        goto out;

                if (opts.hack_skylake) {
                        ret = create_direct_call_sections(file);
                        if (ret)
                                goto out;
                }
        }

        if (opts.mcount) {
                ret = create_mcount_loc_sections(file);
                if (ret)
                        goto out;
        }

        if (opts.prefix) {
                ret = create_prefix_symbols(file);
                if (ret)
                        goto out;
        }

        if (opts.ibt) {
                ret = create_ibt_endbr_seal_sections(file);
                if (ret)
                        goto out;
        }

        if (opts.noabs)
                warnings += check_abs_references(file);

        if (opts.checksum) {
                ret = create_sym_checksum_section(file);
                if (ret)
                        goto out;
        }

        if (opts.orc && nr_insns) {
                ret = orc_create(file);
                if (ret)
                        goto out;
        }

        if (opts.stats) {
                printf("nr_insns_visited: %ld\n", nr_insns_visited);
                printf("nr_cfi: %ld\n", nr_cfi);
                printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
                printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
        }

out:
        if (ret || warnings) {
                if (opts.werror && warnings)
                        ret = 1;

                if (opts.verbose) {
                        if (opts.werror && warnings)
                                WARN("%d warning(s) upgraded to errors", warnings);
                        disas_warned_funcs(disas_ctx);
                }
        }

        if (opts.disas)
                disas_funcs(disas_ctx);

        if (disas_ctx) {
                disas_context_destroy(disas_ctx);
                objtool_disas_ctx = NULL;
        }

        free_insns(file);

        if (!ret && !warnings)
                return 0;

        if (opts.backup && make_backup())
                return 1;

        return ret;
}