/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 1996, 1997, 1998, 1999 John D. Polstra.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Dynamic linker for ELF.
 *
 * John Polstra <jdp@polstra.com>.
 */

#define _WANT_P_OSREL
#include <sys/param.h>
#include <sys/mman.h>

#include <machine/cpufunc.h>
#include <machine/specialreg.h>
#include <machine/sysarch.h>

#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "debug.h"
#include "rtld.h"
#include "rtld_tls.h"

/*
 * Process the special R_X86_64_COPY relocations in the main program.  These
 * copy data from a shared object into a region in the main program's BSS
 * segment.
 *
 * Returns 0 on success, -1 on failure.
 */
int
do_copy_relocations(Obj_Entry *dstobj)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */

        relalim = (const Elf_Rela *)((const char *)dstobj->rela +
            dstobj->relasize);
        for (rela = dstobj->rela; rela < relalim; rela++) {
                if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) {
                        void *dstaddr;
                        const Elf_Sym *dstsym;
                        const char *name;
                        size_t size;
                        const void *srcaddr;
                        const Elf_Sym *srcsym;
                        const Obj_Entry *srcobj, *defobj;
                        SymLook req;
                        int res;

                        dstaddr = (void *)(dstobj->relocbase + rela->r_offset);
                        dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
                        name = dstobj->strtab + dstsym->st_name;
                        size = dstsym->st_size;
                        symlook_init(&req, name);
                        req.ventry = fetch_ventry(dstobj,
                            ELF_R_SYM(rela->r_info));
                        req.flags = SYMLOOK_EARLY;

                        for (srcobj = globallist_next(dstobj); srcobj != NULL;
                            srcobj = globallist_next(srcobj)) {
                                res = symlook_obj(&req, srcobj);
                                if (res == 0) {
                                        srcsym = req.sym_out;
                                        defobj = req.defobj_out;
                                        break;
                                }
                        }

                        if (srcobj == NULL) {
                                _rtld_error(
            "Undefined symbol \"%s\" referenced from COPY relocation in %s",
                                    name, dstobj->path);
                                return (-1);
                        }

                        srcaddr = (const void *)(defobj->relocbase +
                            srcsym->st_value);
                        memcpy(dstaddr, srcaddr, size);
                }
        }

        return (0);
}

/* Initialize the special GOT entries. */
void
init_pltgot(Obj_Entry *obj)
{
        if (obj->pltgot != NULL) {
                obj->pltgot[1] = (Elf_Addr)obj;
                obj->pltgot[2] = (Elf_Addr)&_rtld_bind_start;
        }
}

/* Process the non-PLT relocations. */
int
reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags,
    RtldLockState *lockstate)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;
        SymCache *cache;
        const Elf_Sym *def;
        const Obj_Entry *defobj;
        Elf_Addr *where, symval;
        Elf32_Addr *where32;
        int r;

        r = -1;
        symval = 0;
        def = NULL;

        /*
         * The dynamic loader may be called from a thread, we have
         * limited amounts of stack available so we cannot use alloca().
         */
        if (obj != obj_rtld) {
                cache = calloc(obj->dynsymcount, sizeof(SymCache));
                /* No need to check for NULL here */
        } else
                cache = NULL;

        relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize);
        for (rela = obj->rela; rela < relalim; rela++) {
                /*
                 * First, resolve symbol for relocations which
                 * reference symbols.
                 */
                switch (ELF_R_TYPE(rela->r_info)) {
                case R_X86_64_64:
                case R_X86_64_PC32:
                case R_X86_64_GLOB_DAT:
                case R_X86_64_TPOFF64:
                case R_X86_64_TPOFF32:
                case R_X86_64_DTPMOD64:
                case R_X86_64_DTPOFF64:
                case R_X86_64_DTPOFF32:
                        def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
                            flags, cache, lockstate);
                        if (def == NULL)
                                goto done;

                        /*
                         * If symbol is IFUNC, only perform relocation
                         * when caller allowed it by passing
                         * SYMLOOK_IFUNC flag.  Skip the relocations
                         * otherwise.
                         *
                         * Also error out in case IFUNC relocations
                         * are specified for TLS, which cannot be
                         * usefully interpreted.
                         */
                        if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
                                switch (ELF_R_TYPE(rela->r_info)) {
                                case R_X86_64_64:
                                case R_X86_64_PC32:
                                case R_X86_64_GLOB_DAT:
                                        if ((flags & SYMLOOK_IFUNC) == 0) {
                                                obj->non_plt_gnu_ifunc = true;
                                                continue;
                                        }
                                        symval = (Elf_Addr)rtld_resolve_ifunc(
                                            defobj, def);
                                        break;
                                case R_X86_64_TPOFF64:
                                case R_X86_64_TPOFF32:
                                case R_X86_64_DTPMOD64:
                                case R_X86_64_DTPOFF64:
                                case R_X86_64_DTPOFF32:
                                        _rtld_error("%s: IFUNC for TLS reloc",
                                            obj->path);
                                        goto done;
                                }
                        } else {
                                if ((flags & SYMLOOK_IFUNC) != 0)
                                        continue;
                                symval = (Elf_Addr)defobj->relocbase +
                                    def->st_value;
                        }
                        break;
                default:
                        if ((flags & SYMLOOK_IFUNC) != 0)
                                continue;
                        break;
                }
                where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                where32 = (Elf32_Addr *)where;

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_X86_64_NONE:
                        break;
                case R_X86_64_64:
                        *where = symval + rela->r_addend;
                        break;
                case R_X86_64_PC32:
                        /*
                         * I don't think the dynamic linker should
                         * ever see this type of relocation.  But the
                         * binutils-2.6 tools sometimes generate it.
                         */
                        *where32 = (Elf32_Addr)(unsigned long)(symval +
                            rela->r_addend - (Elf_Addr)where);
                        break;
                /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */
                case R_X86_64_COPY:
                        /*
                         * These are deferred until all other
                         * relocations have been done.  All we do here
                         * is make sure that the COPY relocation is
                         * not in a shared library.  They are allowed
                         * only in executable files.
                         */
                        if (!obj->mainprog) {
                                _rtld_error(
                    "%s: Unexpected R_X86_64_COPY relocation in shared library",
                                    obj->path);
                                goto done;
                        }
                        break;
                case R_X86_64_GLOB_DAT:
                        *where = symval;
                        break;
                case R_X86_64_TPOFF64:
                        /*
                         * We lazily allocate offsets for static TLS
                         * as we see the first relocation that
                         * references the TLS block. This allows us to
                         * support (small amounts of) static TLS in
                         * dynamically loaded modules. If we run out
                         * of space, we generate an error.
                         */
                        if (!defobj->tls_static) {
                                if (!allocate_tls_offset(__DECONST(Obj_Entry *,
                                    defobj))) {
                                        _rtld_error(
                    "%s: No space available for static Thread Local Storage",
                                            obj->path);
                                        goto done;
                                }
                        }
                        *where = (Elf_Addr)(def->st_value - defobj->tlsoffset +
                            rela->r_addend);
                        break;
                case R_X86_64_TPOFF32:
                        /*
                         * We lazily allocate offsets for static TLS
                         * as we see the first relocation that
                         * references the TLS block. This allows us to
                         * support (small amounts of) static TLS in
                         * dynamically loaded modules. If we run out
                         * of space, we generate an error.
                         */
                        if (!defobj->tls_static) {
                                if (!allocate_tls_offset(__DECONST(Obj_Entry *,
                                    defobj))) {
                                        _rtld_error(
                    "%s: No space available for static Thread Local Storage",
                                            obj->path);
                                        goto done;
                                }
                        }
                        *where32 = (Elf32_Addr)(def->st_value -
                            defobj->tlsoffset + rela->r_addend);
                        break;
                case R_X86_64_DTPMOD64:
                        *where += (Elf_Addr)defobj->tlsindex;
                        break;
                case R_X86_64_DTPOFF64:
                        *where += (Elf_Addr)(def->st_value + rela->r_addend);
                        break;
                case R_X86_64_DTPOFF32:
                        *where32 += (Elf32_Addr)(def->st_value +
                            rela->r_addend);
                        break;
                case R_X86_64_RELATIVE:
                        *where = (Elf_Addr)(obj->relocbase + rela->r_addend);
                        break;
                case R_X86_64_IRELATIVE:
                        obj->irelative_nonplt = true;
                        break;

                /*
                 * missing:
                 * R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16,
                 * R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8
                 */
                default:
                        _rtld_error(
                    "%s: Unsupported relocation type %u in non-PLT relocations",
                            obj->path, (unsigned int)ELF_R_TYPE(rela->r_info));
                        goto done;
                }
        }
        r = 0;
done:
        free(cache);
        return (r);
}

/* Process the PLT relocations. */
int
reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        relalim = (const Elf_Rela *)((const char *)obj->pltrela +
            obj->pltrelasize);
        for (rela = obj->pltrela; rela < relalim; rela++) {
                Elf_Addr *where;

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_X86_64_JMP_SLOT:
                        /* Relocate the GOT slot pointing into the PLT. */
                        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                        *where += (Elf_Addr)obj->relocbase;
                        break;

                case R_X86_64_IRELATIVE:
                        obj->irelative = true;
                        break;

                default:
                        _rtld_error("Unknown relocation type %x in PLT",
                            (unsigned int)ELF_R_TYPE(rela->r_info));
                        return (-1);
                }
        }
        return (0);
}

/* Relocate the jump slots in an object. */
int
reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        if (obj->jmpslots_done)
                return (0);
        relalim = (const Elf_Rela *)((const char *)obj->pltrela +
            obj->pltrelasize);
        for (rela = obj->pltrela; rela < relalim; rela++) {
                Elf_Addr *where, target;
                const Elf_Sym *def;
                const Obj_Entry *defobj;

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_X86_64_JMP_SLOT:
                        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                        def = find_symdef(ELF_R_SYM(rela->r_info), obj,
                            &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate);
                        if (def == NULL)
                                return (-1);
                        if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
                                obj->gnu_ifunc = true;
                                continue;
                        }
                        target = (Elf_Addr)(defobj->relocbase + def->st_value +
                            rela->r_addend);
                        reloc_jmpslot(where, target, defobj, obj,
                            (const Elf_Rel *)rela);
                        break;

                case R_X86_64_IRELATIVE:
                        break;

                default:
                        _rtld_error("Unknown relocation type %x in PLT",
                            (unsigned int)ELF_R_TYPE(rela->r_info));
                        return (-1);
                }
        }
        obj->jmpslots_done = true;
        return (0);
}

/* Fixup the jump slot at "where" to transfer control to "target". */
Elf_Addr
reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
    const struct Struct_Obj_Entry *obj __unused,
    const struct Struct_Obj_Entry *refobj __unused, const Elf_Rel *rel __unused)
{
        dbg("reloc_jmpslot: *%p = %p", where, (void *)target);
        if (!ld_bind_not)
                *where = target;
        return (target);
}

static void
reloc_iresolve_one(Obj_Entry *obj, const Elf_Rela *rela,
    RtldLockState *lockstate)
{
        Elf_Addr *where, target, *ptr;

        ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend);
        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
        lock_release(rtld_bind_lock, lockstate);
        target = call_ifunc_resolver(ptr);
        wlock_acquire(rtld_bind_lock, lockstate);
        *where = target;
}

int
reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        if (!obj->irelative)
                return (0);
        obj->irelative = false;
        relalim = (const Elf_Rela *)((const char *)obj->pltrela +
            obj->pltrelasize);
        for (rela = obj->pltrela; rela < relalim; rela++) {
                if (ELF_R_TYPE(rela->r_info) == R_X86_64_IRELATIVE)
                        reloc_iresolve_one(obj, rela, lockstate);
        }
        return (0);
}

int
reloc_iresolve_nonplt(Obj_Entry *obj, RtldLockState *lockstate)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        if (!obj->irelative_nonplt)
                return (0);
        obj->irelative_nonplt = false;
        relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize);
        for (rela = obj->rela; rela < relalim; rela++) {
                if (ELF_R_TYPE(rela->r_info) == R_X86_64_IRELATIVE)
                        reloc_iresolve_one(obj, rela, lockstate);
        }
        return (0);
}

int
reloc_gnu_ifunc(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        if (!obj->gnu_ifunc)
                return (0);
        relalim = (const Elf_Rela *)((const char *)obj->pltrela +
            obj->pltrelasize);
        for (rela = obj->pltrela; rela < relalim; rela++) {
                Elf_Addr *where, target;
                const Elf_Sym *def;
                const Obj_Entry *defobj;

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_X86_64_JMP_SLOT:
                        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                        def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
                            SYMLOOK_IN_PLT | flags, NULL, lockstate);
                        if (def == NULL)
                                return (-1);
                        if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
                                continue;
                        lock_release(rtld_bind_lock, lockstate);
                        target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
                        wlock_acquire(rtld_bind_lock, lockstate);
                        reloc_jmpslot(where, target, defobj, obj,
                            (const Elf_Rel *)rela);
                        break;
                }
        }
        obj->gnu_ifunc = false;
        return (0);
}

uint32_t cpu_feature, cpu_feature2, cpu_stdext_feature, cpu_stdext_feature2;

void
ifunc_init(Elf_Auxinfo *aux_info[__min_size(AT_COUNT)] __unused)
{
        u_int p[4], cpu_high;

        do_cpuid(1, p);
        cpu_feature = p[3];
        cpu_feature2 = p[2];
        do_cpuid(0, p);
        cpu_high = p[0];
        if (cpu_high >= 7) {
                cpuid_count(7, 0, p);
                cpu_stdext_feature = p[1];
                cpu_stdext_feature2 = p[2];
        }
}

int __getosreldate(void);

void
allocate_initial_tls(Obj_Entry *objs)
{
        void *addr;

        /*
         * Fix the size of the static TLS block by using the maximum
         * offset allocated so far and adding a bit for dynamic
         * modules to use.
         */
        tls_static_space = tls_last_offset + ld_static_tls_extra;

        addr = allocate_tls(objs, 0, TLS_TCB_SIZE, TLS_TCB_ALIGN);

        /*
         * This does not use _tcb_set() as it calls amd64_set_tlsbase()
         * which is an ifunc and rtld must not use ifuncs.
         */
        if (__getosreldate() >= P_OSREL_TLSBASE)
                sysarch(AMD64_SET_TLSBASE, &addr);
        else if ((cpu_stdext_feature & CPUID_STDEXT_FSGSBASE) != 0)
                wrfsbase((uintptr_t)addr);
        else
                sysarch(AMD64_SET_FSBASE, &addr);
}

void *
__tls_get_addr(tls_index *ti)
{
        return (tls_get_addr_common(_tcb_get(), ti->ti_module, ti->ti_offset));
}

size_t
calculate_tls_offset(size_t prev_offset, size_t prev_size __unused, size_t size,
    size_t align, size_t offset)
{
        size_t res;

        /*
         * res is the smallest integer satisfying res - prev_offset >= size
         * and (-res) % p_align = p_vaddr % p_align (= p_offset % p_align).
         */
        res = prev_offset + size + align - 1;
        res -= (res + offset) & (align - 1);
        return (res);
}

size_t
calculate_first_tls_offset(size_t size, size_t align, size_t offset)
{
        return (calculate_tls_offset(0, 0, size, align, offset));
}