/*      $NetBSD: mips_reloc.c,v 1.78 2024/11/30 01:04:05 christos Exp $ */

/*
 * Copyright 1997 Michael L. Hitch <mhitch@montana.edu>
 * Portions copyright 2002 Charles M. Hannum <root@ihack.net>
 * 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * 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.
 */

/*
 * MIPS ELF relocations, for all ABIs: o32, n32, n64.
 *
 * References:
 *
 *      [SYSVMIPS32ABI] System V Application Binary Interface: MIPS
 *      RISC Processor Supplement, 3rd ed., 1996.
 *      https://www.sco.com/developers/devspecs/mipsabi.pdf
 *      https://web.archive.org/web/20221026055746/http://www.sco.com/developers/devspecs/mipsabi.pdf
 *
 *      [SGIMIPS64ELF] 64-bit ELF Object File Specification, Draft
 *      Version 2.5, MIPS Technologies / Silicon Graphics Computer
 *      Systems.  Archived 2015-08-18.
 *      https://web.archive.org/web/20150818210955/http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: mips_reloc.c,v 1.78 2024/11/30 01:04:05 christos Exp $");
#endif /* not lint */

#include <sys/types.h>
#include <sys/endian.h>
#include <sys/tls.h>

#include <stdlib.h>
#include <string.h>

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

#include <machine/lwp_private.h>

#ifdef __mips_o32
#define SUPPORT_OLD_BROKEN_LD
#endif

void _rtld_bind_start(void);
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
caddr_t _rtld_bind(Elf_Word, Elf_Addr, Elf_Addr, Elf_Addr);

/*
 * It is possible for the compiler to emit relocations for unaligned data.
 * We handle this situation with these inlines.
 */

#if ELFSIZE == 64
/*
 * ELF64 MIPS encodes the relocs uniquely.  The first 32-bits of info contain
 * the symbol index.  The top 32-bits contain three relocation types encoded
 * in big-endian integer with first relocation in LSB.  This means for little
 * endian we have to byte swap that integer (r_type).
 */
#define Elf_Sxword                      Elf64_Sxword
#define ELF_R_NXTTYPE_64_P(r_type)      ((((r_type) >> 8) & 0xff) == R_TYPE(64))
#if BYTE_ORDER == LITTLE_ENDIAN
#undef ELF_R_SYM
#undef ELF_R_TYPE
#define ELF_R_SYM(r_info)               ((r_info) & 0xffffffff)
#define ELF_R_TYPE(r_info)              bswap32((r_info) >> 32)
#endif
#else
#define ELF_R_NXTTYPE_64_P(r_type)      (0)
#define Elf_Sxword                      Elf32_Sword
#endif
#define GOT1_MASK                       (~(Elf_Addr)0 >> 1)

static inline Elf_Sxword
load_ptr(void *where, size_t len)
{
        Elf_Sxword val;

        if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
#if ELFSIZE == 64
                if (len == sizeof(Elf_Sxword))
                        return *(Elf_Sxword *)where;
#endif
                return *(Elf_Sword *)where;
        }

        val = 0;
#if BYTE_ORDER == LITTLE_ENDIAN
        (void)memcpy(&val, where, len);
#endif
#if BYTE_ORDER == BIG_ENDIAN
        uint8_t *valp = (void *)&val;
        (void)memcpy(valp + sizeof(val) - len, where, len);
#endif
        return (len == sizeof(Elf_Sxword)) ? val : (Elf_Sword)val;
}

static inline void
store_ptr(void *where, Elf_Sxword val, size_t len)
{
        if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
#if ELFSIZE == 64
                if (len == sizeof(Elf_Sxword)) {
                        *(Elf_Sxword *)where = val;
                        return;
                }
#endif
                *(Elf_Sword *)where = val;
                return;
        }
#if BYTE_ORDER == LITTLE_ENDIAN
        (void)memcpy(where, &val, len);
#endif
#if BYTE_ORDER == BIG_ENDIAN
        const uint8_t *valp = (const void *)&val;
        (void)memcpy(where, valp + sizeof(val) - len, len);
#endif
}


void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
        obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
        /* XXX only if obj->pltgot[1] & 0x80000000 ?? */
        obj->pltgot[1] = (Elf_Addr) obj;
}

void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
        const Elf_Rel *rel = 0, *rellim;
        Elf_Addr relsz = 0;
        void *where;
        const Elf_Sym *symtab = NULL, *sym;
        Elf_Addr *got = NULL;
        Elf_Word local_gotno = 0, symtabno = 0, gotsym = 0;
        size_t i;

        for (; dynp->d_tag != DT_NULL; dynp++) {
                switch (dynp->d_tag) {
                case DT_REL:
                        rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
                        break;
                case DT_RELSZ:
                        relsz = dynp->d_un.d_val;
                        break;
                case DT_SYMTAB:
                        symtab = (const Elf_Sym *)(relocbase + dynp->d_un.d_ptr);
                        break;
                case DT_PLTGOT:
                        got = (Elf_Addr *)(relocbase + dynp->d_un.d_ptr);
                        break;
                case DT_MIPS_LOCAL_GOTNO:
                        local_gotno = dynp->d_un.d_val;
                        break;
                case DT_MIPS_SYMTABNO:
                        symtabno = dynp->d_un.d_val;
                        break;
                case DT_MIPS_GOTSYM:
                        gotsym = dynp->d_un.d_val;
                        break;
                }
        }

        i = (got[1] & 0x80000000) ? 2 : 1;
        /* Relocate the local GOT entries */
        got += i;
        for (; i < local_gotno; i++)
                *got++ += relocbase;
        sym = symtab + gotsym;
        /* Now do the global GOT entries */
        for (i = gotsym; i < symtabno; i++) {
                *got = sym->st_value + relocbase;
                ++sym;
                ++got;
        }

        rellim = (const Elf_Rel *)((uintptr_t)rel + relsz);
        for (; rel < rellim; rel++) {
                Elf_Word r_symndx, r_type;

                where = (void *)(relocbase + rel->r_offset);

                r_symndx = ELF_R_SYM(rel->r_info);
                r_type = ELF_R_TYPE(rel->r_info);

                switch (r_type & 0xff) {
                case R_TYPE(REL32): {
                        const size_t rlen =
                            ELF_R_NXTTYPE_64_P(r_type)
                                ? sizeof(Elf_Sxword)
                                : sizeof(Elf_Sword);
                        Elf_Sxword old = load_ptr(where, rlen);
                        Elf_Sxword val = old;
#if ELFSIZE == 64
                        assert(r_type == R_TYPE(REL32)
                            || r_type == (R_TYPE(REL32)|(R_TYPE(64) << 8)));
#endif
                        assert(r_symndx < gotsym);
                        sym = symtab + r_symndx;
                        assert(ELF_ST_BIND(sym->st_info) == STB_LOCAL);
                        val += relocbase;
                        store_ptr(where, val, sizeof(Elf_Sword));
                        rdbg(("REL32/L(%p) %p -> %p in <self>",
                            where, (void *)old, (void *)val));
                        store_ptr(where, val, rlen);
                        break;
                }

                case R_TYPE(GPREL32):
                case R_TYPE(NONE):
                        break;


                default:
                        abort();
                }
        }
}

int
_rtld_relocate_nonplt_objects(Obj_Entry *obj)
{
        const Elf_Rel *rel;
        Elf_Addr *got = obj->pltgot;
        const Elf_Sym *sym, *def = NULL;
        const Obj_Entry *defobj = NULL;
        unsigned long last_symnum = ULONG_MAX;
        Elf_Word i;
#ifdef SUPPORT_OLD_BROKEN_LD
        int broken;
#endif

#ifdef SUPPORT_OLD_BROKEN_LD
        broken = 0;
        sym = obj->symtab;
        for (i = 1; i < 12; i++)
                if (sym[i].st_info == ELF_ST_INFO(STB_LOCAL, STT_NOTYPE))
                        broken = 1;
        dbg(("%s: broken=%d", obj->path, broken));
#endif

        i = (got[1] & 0x80000000) ? 2 : 1;
        /* Relocate the local GOT entries */
        got += i;
        for (; i < obj->local_gotno; i++)
                *got++ += (Elf_Addr)obj->relocbase;
        sym = obj->symtab + obj->gotsym;
        /* Now do the global GOT entries */
        for (i = obj->gotsym; i < obj->symtabno; i++) {
                rdbg((" doing got %d sym %p (%s, %lx)", i - obj->gotsym, sym,
                    sym->st_name + obj->strtab, (u_long) *got));

#ifdef SUPPORT_OLD_BROKEN_LD
                if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
                    broken && sym->st_shndx == SHN_UNDEF) {
                        /*
                         * XXX DANGER WILL ROBINSON!
                         * You might think this is stupid, as it intentionally
                         * defeats lazy binding -- and you'd be right.
                         * Unfortunately, for lazy binding to work right, we
                         * need to a way to force the GOT slots used for
                         * function pointers to be resolved immediately.  This
                         * is supposed to be done automatically by the linker,
                         * by not outputting a PLT slot and setting st_value
                         * to 0 if there are non-PLT references, but older
                         * versions of GNU ld do not do this.
                         */
                        def = _rtld_find_symdef(i, obj, &defobj, false);
                        if (def == NULL)
                                return -1;
                        *got = def->st_value + (Elf_Addr)defobj->relocbase;
                } else
#endif
                if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
                    sym->st_value != 0 && sym->st_shndx == SHN_UNDEF) {
                        /*
                         * If there are non-PLT references to the function,
                         * st_value should be 0, forcing us to resolve the
                         * address immediately.
                         *
                         * XXX DANGER WILL ROBINSON!
                         * The linker is not outputting PLT slots for calls to
                         * functions that are defined in the same shared
                         * library.  This is a bug, because it can screw up
                         * link ordering rules if the symbol is defined in
                         * more than one module.  For now, if there is a
                         * definition, we fail the test above and force a full
                         * symbol lookup.  This means that all intra-module
                         * calls are bound immediately.  - mycroft, 2003/09/24
                         */
                        *got = sym->st_value + (Elf_Addr)obj->relocbase;
                } else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) {
                        /* Symbols with index SHN_ABS are not relocated. */
                        if (sym->st_shndx != SHN_ABS)
                                *got = sym->st_value +
                                    (Elf_Addr)obj->relocbase;
                } else {
                        def = _rtld_find_symdef(i, obj, &defobj, false);
                        if (def == NULL)
                                return -1;
                        *got = def->st_value + (Elf_Addr)defobj->relocbase;
                }

                rdbg(("  --> now %lx", (u_long) *got));
                ++sym;
                ++got;
        }

        got = obj->pltgot;
        for (rel = obj->rel; rel < obj->rellim; rel++) {
                unsigned long symnum;
                void            *where;

                where = obj->relocbase + rel->r_offset;

                switch (ELF_R_TYPE(rel->r_info) & 0xff) {
#if ELFSIZE == 64
                case R_TYPE(TLS_DTPMOD64):
                case R_TYPE(TLS_DTPREL64):
                case R_TYPE(TLS_TPREL64):
#else
                case R_TYPE(TLS_DTPMOD32):
                case R_TYPE(TLS_DTPREL32):
                case R_TYPE(TLS_TPREL32):
#endif
                        symnum = ELF_R_SYM(rel->r_info);
                        if (last_symnum != symnum) {
                                last_symnum = symnum;
                                def = _rtld_find_symdef(symnum, obj, &defobj,
                                    false);
                                if (def == NULL)
                                        return -1;
                        }
                        break;
                default:
                        break;
                }

                switch (ELF_R_TYPE(rel->r_info) & 0xff) {
                case R_TYPE(NONE):
                        break;

                case R_TYPE(REL32): {
                        /* 32-bit PC-relative reference */
                        const Elf_Sym *def2;
                        const size_t rlen =
                            ELF_R_NXTTYPE_64_P(ELF_R_TYPE(rel->r_info))
                                ? sizeof(Elf_Sxword)
                                : sizeof(Elf_Sword);
                        Elf_Sxword old = load_ptr(where, rlen);
                        Elf_Sxword val = old;

                        def2 = obj->symtab + ELF_R_SYM(rel->r_info);

                        if (ELF_R_SYM(rel->r_info) >= obj->gotsym) {
                                val += got[obj->local_gotno +
                                    ELF_R_SYM(rel->r_info) - obj->gotsym];
                                rdbg(("REL32/G(%p) %p --> %p (%s) in %s",
                                    where, (void *)old, (void *)val,
                                    obj->strtab + def2->st_name,
                                    obj->path));
                        } else {
                                /*
                                 * XXX: ABI DIFFERENCE!
                                 *
                                 * Old NetBSD binutils would generate shared
                                 * libs with section-relative relocations being
                                 * already adjusted for the start address of
                                 * the section.
                                 *
                                 * New binutils, OTOH, generate shared libs
                                 * with the same relocations being based at
                                 * zero, so we need to add in the start address
                                 * of the section.
                                 *
                                 * --rkb, Oct 6, 2001
                                 */

                                if (def2->st_info ==
                                    ELF_ST_INFO(STB_LOCAL, STT_SECTION)
#ifdef SUPPORT_OLD_BROKEN_LD
                                    && !broken
#endif
                                    )
                                        val += (Elf_Addr)def->st_value;

                                val += (Elf_Addr)obj->relocbase;

                                rdbg(("REL32/L(%p) %p -> %p (%s) in %s",
                                    where, (void *)old, (void *)val,
                                    obj->strtab + def2->st_name, obj->path));
                        }
                        store_ptr(where, val, rlen);
                        break;
                }

#if ELFSIZE == 64
                case R_TYPE(TLS_DTPMOD64):
#else
                case R_TYPE(TLS_DTPMOD32):
#endif
                {
                        Elf_Addr old = load_ptr(where, ELFSIZE / 8);
                        Elf_Addr val = old;

                        val += (Elf_Addr)defobj->tlsindex;

                        store_ptr(where, val, ELFSIZE / 8);
                        rdbg(("DTPMOD %s in %s --> %p in %s",
                            obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)].st_name,
                            obj->path, (void *)old, defobj->path));
                        break;
                }

#if ELFSIZE == 64
                case R_TYPE(TLS_DTPREL64):
#else
                case R_TYPE(TLS_DTPREL32):
#endif
                {
                        Elf_Addr old = load_ptr(where, ELFSIZE / 8);
                        Elf_Addr val = old;

                        val += (Elf_Addr)def->st_value - TLS_DTV_OFFSET;
                        store_ptr(where, val, ELFSIZE / 8);

                        rdbg(("DTPREL %s in %s --> %p in %s",
                            obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)].st_name,
                            obj->path, (void *)old, defobj->path));
                        break;
                }

#if ELFSIZE == 64
                case R_TYPE(TLS_TPREL64):
#else
                case R_TYPE(TLS_TPREL32):
#endif
                {
                        Elf_Addr old = load_ptr(where, ELFSIZE / 8);
                        Elf_Addr val = old;

                        if (!defobj->tls_static &&
                            _rtld_tls_offset_allocate(__UNCONST(defobj)))
                                return -1;

                        val += (Elf_Addr)(def->st_value + defobj->tlsoffset
                            - TLS_TP_OFFSET);
                        store_ptr(where, val, ELFSIZE / 8);

                        rdbg(("TPREL %s in %s --> %p in %s",
                            obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)].st_name,
                            obj->path, where, defobj->path));
                        break;
                }

                default:
                        rdbg(("sym = %lu, type = %lu, offset = %p, "
                            "contents = %p, symbol = %s",
                            (u_long)ELF_R_SYM(rel->r_info),
                            (u_long)ELF_R_TYPE(rel->r_info),
                            (void *)rel->r_offset,
                            (void *)load_ptr(where, sizeof(Elf_Sword)),
                            obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)].st_name));
                        _rtld_error("%s: Unsupported relocation type %ld "
                            "in non-PLT relocations",
                            obj->path, (u_long) ELF_R_TYPE(rel->r_info));
                        return -1;
                }
        }

        return 0;
}

int
_rtld_relocate_plt_lazy(Obj_Entry *obj)
{
        /* PLT fixups were done above in the GOT relocation. */
        return 0;
}

static inline int
_rtld_relocate_plt_object(const Obj_Entry *obj, Elf_Word sym, Elf_Addr *tp)
{
        Elf_Addr *got = obj->pltgot;
        const Elf_Sym *def;
        const Obj_Entry *defobj;
        Elf_Addr new_value;

        def = _rtld_find_plt_symdef(sym, obj, &defobj, tp != NULL);
        if (__predict_false(def == NULL))
                return -1;
        if (__predict_false(def == &_rtld_sym_zero))
                return 0;

        if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
                if (tp == NULL)
                        return 0;
                new_value = _rtld_resolve_ifunc(defobj, def);
        } else {
                new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
        }
        rdbg(("bind now/fixup in %s --> new=%p",
            defobj->strtab + def->st_name, (void *)new_value));
        got[obj->local_gotno + sym - obj->gotsym] = new_value;

        if (tp)
                *tp = new_value;
        return 0;
}

caddr_t
_rtld_bind(Elf_Word a0, Elf_Addr a1, Elf_Addr a2, Elf_Addr a3)
{
        Elf_Addr *got = (Elf_Addr *)(a2 - 0x7ff0);
        const Obj_Entry *obj = (Obj_Entry *)(got[1] & GOT1_MASK);
        Elf_Addr new_value = 0; /* XXX gcc */
        int err;

        _rtld_shared_enter();
        err = _rtld_relocate_plt_object(obj, a0, &new_value);
        if (err)
                _rtld_die();
        _rtld_shared_exit();

        return (caddr_t)new_value;
}

int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
        const Elf_Sym *sym = obj->symtab + obj->gotsym;
        Elf_Word i;

        for (i = obj->gotsym; i < obj->symtabno; i++, sym++) {
                if (ELF_ST_TYPE(sym->st_info) == STT_FUNC)
                        if (_rtld_relocate_plt_object(obj, i, NULL) < 0)
                                return -1;
        }

        return 0;
}