/* $NetBSD: mips_reloc.c,v 1.78 2024/11/30 01:04:05 christos Exp $ */ /* * Copyright 1997 Michael L. Hitch * Portions copyright 2002 Charles M. Hannum * 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 #ifndef lint __RCSID("$NetBSD: mips_reloc.c,v 1.78 2024/11/30 01:04:05 christos Exp $"); #endif /* not lint */ #include #include #include #include #include #include "debug.h" #include "rtld.h" #include #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 ", 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; }