// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <elfutils/libdw.h>
#include <elfutils/libdwfl.h>
#include <inttypes.h>
#include <errno.h>
#include "debug.h"
#include "dso.h"
#include <dwarf-regs.h>
#include "unwind.h"
#include "unwind-libdw.h"
#include "machine.h"
#include "map.h"
#include "symbol.h"
#include "thread.h"
#include <linux/types.h>
#include <linux/zalloc.h>
#include "event.h"
#include "perf_regs.h"
#include "callchain.h"
#include "util/env.h"

/*
 * The dwfl thread argument passed to functions like memory_read. Memory has to
 * be allocated to persist of multiple uses of the dwfl.
 */
struct dwfl_ui_thread_info {
        /* Back link to the dwfl. */
        Dwfl *dwfl;
        /* The current unwind info, only 1 is supported. */
        struct unwind_info *ui;
};

static char *debuginfo_path;

static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata,
                            const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused,
                            const char *file_name, const char *debuglink_file __maybe_unused,
                            GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name)
{
        const struct dso *dso = *userdata;

        assert(dso);
        if (dso__symsrc_filename(dso) && strcmp(file_name, dso__symsrc_filename(dso)))
                *debuginfo_file_name = strdup(dso__symsrc_filename(dso));
        return -1;
}

void libdw__invalidate_dwfl(struct maps *maps, void *arg)
{
        struct dwfl_ui_thread_info *dwfl_ui_ti = arg;

        if (!dwfl_ui_ti)
                return;

        assert(dwfl_ui_ti->ui == NULL);
        maps__set_libdw_addr_space_dwfl(maps, NULL);
        dwfl_end(dwfl_ui_ti->dwfl);
        free(dwfl_ui_ti);
}

static const Dwfl_Callbacks offline_callbacks = {
        .find_debuginfo         = __find_debuginfo,
        .debuginfo_path         = &debuginfo_path,
        .section_address        = dwfl_offline_section_address,
        // .find_elf is not set as we use dwfl_report_elf() instead.
};

static int __report_module(struct addr_location *al, u64 ip,
                            struct unwind_info *ui)
{
        Dwfl_Module *mod;
        struct dso *dso = NULL;
        Dwarf_Addr base;
        /*
         * Some callers will use al->sym, so we can't just use the
         * cheaper thread__find_map() here.
         */
        thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);

        if (al->map)
                dso = map__dso(al->map);

        if (!dso)
                return 0;

        /*
         * The generated JIT DSO files only map the code segment without
         * ELF headers.  Since JIT codes used to be packed in a memory
         * segment, calculating the base address using pgoff falls into
         * a different code in another DSO.  So just use the map->start
         * directly to pick the correct one.
         */
        if (!strncmp(dso__long_name(dso), "/tmp/jitted-", 12))
                base = map__start(al->map);
        else
                base = map__start(al->map) - map__pgoff(al->map);

        mod = dwfl_addrmodule(ui->dwfl, ip);
        if (mod) {
                Dwarf_Addr s;

                dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
                if (s != base)
                        mod = NULL;
        }

        if (!mod) {
                char filename[PATH_MAX];

                __symbol__join_symfs(filename, sizeof(filename), dso__long_name(dso));
                /* Don't hang up on device files like /dev/dri/renderD128. */
                if (is_regular_file(filename)) {
                        mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1,
                                              base, false);
                }
        }
        if (!mod) {
                char filename[PATH_MAX];

                if (dso__build_id_filename(dso, filename, sizeof(filename), false))
                        mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1,
                                              base, false);
        }

        if (mod) {
                void **userdatap;

                dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL);
                *userdatap = dso;
        }

        return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
}

static int report_module(u64 ip, struct unwind_info *ui)
{
        struct addr_location al;
        int res;

        addr_location__init(&al);
        res = __report_module(&al, ip, ui);
        addr_location__exit(&al);
        return res;
}

/*
 * Store all entries within entries array,
 * we will process it after we finish unwind.
 */
static int entry(u64 ip, struct unwind_info *ui)

{
        struct unwind_entry *e = &ui->entries[ui->idx++];
        struct addr_location al;

        addr_location__init(&al);
        if (__report_module(&al, ip, ui)) {
                addr_location__exit(&al);
                return -1;
        }

        e->ip     = ip;
        e->ms.thread = thread__get(al.thread);
        e->ms.map = map__get(al.map);
        e->ms.sym = al.sym;

        pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
                 al.sym ? al.sym->name : "''",
                 ip,
                 al.map ? map__map_ip(al.map, ip) : (u64) 0);
        addr_location__exit(&al);
        return 0;
}

static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
{
        /* We want only single thread to be processed. */
        if (*thread_argp != NULL)
                return 0;

        *thread_argp = arg;
        return dwfl_pid(dwfl);
}

static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
                          Dwarf_Word *data)
{
        struct addr_location al;
        ssize_t size;
        struct dso *dso;

        addr_location__init(&al);
        if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
                pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
                goto out_fail;
        }
        dso = map__dso(al.map);
        if (!dso)
                goto out_fail;

        size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data));

        addr_location__exit(&al);
        return !(size == sizeof(*data));
out_fail:
        addr_location__exit(&al);
        return -1;
}

static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
                        void *arg)
{
        struct dwfl_ui_thread_info *dwfl_ui_ti = arg;
        struct unwind_info *ui = dwfl_ui_ti->ui;
        struct stack_dump *stack = &ui->sample->user_stack;
        u64 start, end;
        int offset;
        int ret;

        if (!ui->sample->user_regs)
                return false;

        ret = perf_reg_value(&start, ui->sample->user_regs,
                             perf_arch_reg_sp(ui->e_machine));
        if (ret)
                return false;

        end = start + stack->size;

        /* Check overflow. */
        if (addr + sizeof(Dwarf_Word) < addr)
                return false;

        if (addr < start || addr + sizeof(Dwarf_Word) > end) {
                ret = access_dso_mem(ui, addr, result);
                if (ret) {
                        pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
                                 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
                                addr, start, end);
                        return false;
                }
                return true;
        }

        offset  = addr - start;
        *result = *(Dwarf_Word *)&stack->data[offset];
        pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
                 addr, (unsigned long)*result, offset);
        return true;
}

static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
{
        struct dwfl_ui_thread_info *dwfl_ui_ti = arg;
        struct unwind_info *ui = dwfl_ui_ti->ui;
        struct regs_dump *user_regs = perf_sample__user_regs(ui->sample);
        Dwarf_Word *dwarf_regs;
        int max_dwarf_reg = 0;
        bool ret;
        uint16_t e_machine = ui->e_machine;
        int e_flags = ui->e_flags;
        uint64_t ip_perf_reg = perf_arch_reg_ip(e_machine);
        Dwarf_Word val = 0;


        /*
         * For every possible perf register in the bitmap determine the dwarf
         * register and use to compute the max.
         */
        for (int perf_reg = 0; perf_reg < 64; perf_reg++) {
                if (user_regs->mask & (1ULL << perf_reg)) {
                        int dwarf_reg =
                                get_dwarf_regnum_for_perf_regnum(perf_reg, e_machine,
                                                                 e_flags,
                                                                 /*only_libdw_supported=*/true);
                        if (dwarf_reg > max_dwarf_reg)
                                max_dwarf_reg = dwarf_reg;
                }
        }

        dwarf_regs = calloc(max_dwarf_reg + 1, sizeof(*dwarf_regs));
        if (!dwarf_regs)
                return false;

        for (int perf_reg = 0; perf_reg < 64; perf_reg++) {
                if (user_regs->mask & (1ULL << perf_reg)) {
                        int dwarf_reg =
                                get_dwarf_regnum_for_perf_regnum(perf_reg, e_machine,
                                                                 e_flags,
                                                                 /*only_libdw_supported=*/true);
                        if (dwarf_reg >= 0) {
                                val = 0;
                                if (perf_reg_value(&val, user_regs, perf_reg) == 0)
                                        dwarf_regs[dwarf_reg] = val;
                        }
                }
        }
        if (perf_reg_value(&val, user_regs, ip_perf_reg) == 0)
                dwfl_thread_state_register_pc(thread, val);

        ret = dwfl_thread_state_registers(thread, 0, max_dwarf_reg + 1, dwarf_regs);
        free(dwarf_regs);
        return ret;
}

static const Dwfl_Thread_Callbacks callbacks = {
        .next_thread           = next_thread,
        .memory_read           = memory_read,
        .set_initial_registers = libdw_set_initial_registers,
};

static int
frame_callback(Dwfl_Frame *state, void *arg)
{
        struct unwind_info *ui = arg;
        Dwarf_Addr pc;
        bool isactivation;

        if (!dwfl_frame_pc(state, &pc, NULL)) {
                if (!ui->best_effort)
                        pr_err("%s", dwfl_errmsg(-1));
                return DWARF_CB_ABORT;
        }

        // report the module before we query for isactivation
        report_module(pc, ui);

        if (!dwfl_frame_pc(state, &pc, &isactivation)) {
                if (!ui->best_effort)
                        pr_err("%s", dwfl_errmsg(-1));
                return DWARF_CB_ABORT;
        }

        if (!isactivation)
                --pc;

        return entry(pc, ui) || !(--ui->max_stack) ?
               DWARF_CB_ABORT : DWARF_CB_OK;
}

int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
                        struct thread *thread,
                        struct perf_sample *data,
                        int max_stack,
                        bool best_effort)
{
        struct maps *maps = thread__maps(thread);
        struct machine *machine = maps__machine(maps);
        uint32_t e_flags = 0;
        uint16_t e_machine = thread__e_machine(thread, machine, &e_flags);
        struct dwfl_ui_thread_info *dwfl_ui_ti;
        static struct unwind_info *ui;
        Dwfl *dwfl;
        Dwarf_Word ip;
        int err = -EINVAL, i;

        if (!data->user_regs || !data->user_regs->regs)
                return -EINVAL;

        ui = zalloc(sizeof(*ui) + sizeof(ui->entries[0]) * max_stack);
        if (!ui)
                return -ENOMEM;

        *ui = (struct unwind_info){
                .sample         = data,
                .thread         = thread,
                .machine        = machine,
                .cb             = cb,
                .arg            = arg,
                .max_stack      = max_stack,
                .e_machine      = e_machine,
                .e_flags        = e_flags,
                .best_effort    = best_effort
        };

        dwfl_ui_ti = maps__libdw_addr_space_dwfl(maps);
        if (dwfl_ui_ti) {
                dwfl = dwfl_ui_ti->dwfl;
        } else {
                dwfl_ui_ti = zalloc(sizeof(*dwfl_ui_ti));
                dwfl = dwfl_begin(&offline_callbacks);
                if (!dwfl)
                        goto out;

                dwfl_ui_ti->dwfl = dwfl;
                maps__set_libdw_addr_space_dwfl(maps, dwfl_ui_ti);
        }
        assert(dwfl_ui_ti->ui == NULL);
        assert(dwfl_ui_ti->dwfl == dwfl);
        assert(dwfl_ui_ti == maps__libdw_addr_space_dwfl(maps));
        dwfl_ui_ti->ui = ui;
        ui->dwfl = dwfl;

        err = perf_reg_value(&ip, data->user_regs, perf_arch_reg_ip(e_machine));
        if (err)
                goto out;

        err = report_module(ip, ui);
        if (err)
                goto out;

        dwfl_attach_state(dwfl, /*elf=*/NULL, thread__tid(thread), &callbacks,
                          /* Dwfl thread function argument*/dwfl_ui_ti);
        // Ignore thread already attached error.

        err = dwfl_getthread_frames(dwfl, thread__tid(thread), frame_callback,
                                    /* Dwfl frame function argument*/ui);

        if (err && ui->max_stack != max_stack)
                err = 0;

        /*
         * Display what we got based on the order setup.
         */
        for (i = 0; i < ui->idx && !err; i++) {
                int j = i;

                if (callchain_param.order == ORDER_CALLER)
                        j = ui->idx - i - 1;

                err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
        }

 out:
        if (err)
                pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));

        for (i = 0; i < ui->idx; i++)
                map_symbol__exit(&ui->entries[i].ms);

        dwfl_ui_ti->ui = NULL;
        free(ui);
        return 0;
}