| /* Machine-dependent ELF dynamic relocation inline functions. PowerPC version. |
| Copyright (C) 1995-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #ifndef dl_machine_h |
| #define dl_machine_h |
| |
| #define ELF_MACHINE_NAME "powerpc" |
| |
| #include <assert.h> |
| #include <dl-tls.h> |
| #include <dl-irel.h> |
| |
| /* Translate a processor specific dynamic tag to the index |
| in l_info array. */ |
| #define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM) |
| |
| /* Return nonzero iff ELF header is compatible with the running host. */ |
| static inline int |
| elf_machine_matches_host (const Elf32_Ehdr *ehdr) |
| { |
| return ehdr->e_machine == EM_PPC; |
| } |
| |
| /* Return the value of the GOT pointer. */ |
| static inline Elf32_Addr * __attribute__ ((const)) |
| ppc_got (void) |
| { |
| Elf32_Addr *got; |
| |
| asm ("bcl 20,31,1f\n" |
| "1: mflr %0\n" |
| " addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n" |
| " addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n" |
| : "=b" (got) : : "lr"); |
| |
| return got; |
| } |
| |
| /* Return the link-time address of _DYNAMIC, stored as |
| the first value in the GOT. */ |
| static inline Elf32_Addr __attribute__ ((const)) |
| elf_machine_dynamic (void) |
| { |
| return *ppc_got (); |
| } |
| |
| /* Return the run-time load address of the shared object. */ |
| static inline Elf32_Addr __attribute__ ((const)) |
| elf_machine_load_address (void) |
| { |
| Elf32_Addr *branchaddr; |
| Elf32_Addr runtime_dynamic; |
| |
| /* This is much harder than you'd expect. Possibly I'm missing something. |
| The 'obvious' way: |
| |
| Apparently, "bcl 20,31,$+4" is what should be used to load LR |
| with the address of the next instruction. |
| I think this is so that machines that do bl/blr pairing don't |
| get confused. |
| |
| asm ("bcl 20,31,0f ;" |
| "0: mflr 0 ;" |
| "lis %0,0b@ha;" |
| "addi %0,%0,0b@l;" |
| "subf %0,%0,0" |
| : "=b" (addr) : : "r0", "lr"); |
| |
| doesn't work, because the linker doesn't have to (and in fact doesn't) |
| update the @ha and @l references; the loader (which runs after this |
| code) will do that. |
| |
| Instead, we use the following trick: |
| |
| The linker puts the _link-time_ address of _DYNAMIC at the first |
| word in the GOT. We could branch to that address, if we wanted, |
| by using an @local reloc; the linker works this out, so it's safe |
| to use now. We can't, of course, actually branch there, because |
| we'd cause an illegal instruction exception; so we need to compute |
| the address ourselves. That gives us the following code: */ |
| |
| /* Get address of the 'b _DYNAMIC@local'... */ |
| asm ("bcl 20,31,0f;" |
| "b _DYNAMIC@local;" |
| "0:" |
| : "=l" (branchaddr)); |
| |
| /* So now work out the difference between where the branch actually points, |
| and the offset of that location in memory from the start of the file. */ |
| runtime_dynamic = ((Elf32_Addr) branchaddr |
| + ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6)); |
| |
| return runtime_dynamic - elf_machine_dynamic (); |
| } |
| |
| #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */ |
| |
| /* The PLT uses Elf32_Rela relocs. */ |
| #define elf_machine_relplt elf_machine_rela |
| |
| /* Mask identifying addresses reserved for the user program, |
| where the dynamic linker should not map anything. */ |
| #define ELF_MACHINE_USER_ADDRESS_MASK 0xf0000000UL |
| |
| /* The actual _start code is in dl-start.S. Use a really |
| ugly bit of assembler to let dl-start.o see _dl_start. */ |
| #define RTLD_START asm (".globl _dl_start"); |
| |
| /* Decide where a relocatable object should be loaded. */ |
| extern ElfW(Addr) |
| __elf_preferred_address(struct link_map *loader, size_t maplength, |
| ElfW(Addr) mapstartpref); |
| #define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \ |
| __elf_preferred_address (loader, maplength, mapstartpref) |
| |
| /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so |
| PLT entries should not be allowed to define the value. |
| ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one |
| of the main executable's symbols, as for a COPY reloc. */ |
| /* We never want to use a PLT entry as the destination of a |
| reloc, when what is being relocated is a branch. This is |
| partly for efficiency, but mostly so we avoid loops. */ |
| #define elf_machine_type_class(type) \ |
| ((((type) == R_PPC_JMP_SLOT \ |
| || (type) == R_PPC_REL24 \ |
| || ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */ \ |
| && (type) <= R_PPC_DTPREL32) \ |
| || (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \ |
| | (((type) == R_PPC_COPY) * ELF_RTYPE_CLASS_COPY)) |
| |
| /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */ |
| #define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT |
| |
| /* The PowerPC never uses REL relocations. */ |
| #define ELF_MACHINE_NO_REL 1 |
| |
| /* Set up the loaded object described by MAP so its unrelocated PLT |
| entries will jump to the on-demand fixup code in dl-runtime.c. |
| Also install a small trampoline to be used by entries that have |
| been relocated to an address too far away for a single branch. */ |
| extern int __elf_machine_runtime_setup (struct link_map *map, |
| int lazy, int profile); |
| |
| static inline int |
| elf_machine_runtime_setup (struct link_map *map, |
| int lazy, int profile) |
| { |
| if (map->l_info[DT_JMPREL] == 0) |
| return lazy; |
| |
| if (map->l_info[DT_PPC(GOT)] == 0) |
| /* Handle old style PLT. */ |
| return __elf_machine_runtime_setup (map, lazy, profile); |
| |
| /* New style non-exec PLT consisting of an array of addresses. */ |
| map->l_info[DT_PPC(GOT)]->d_un.d_ptr += map->l_addr; |
| if (lazy) |
| { |
| Elf32_Addr *plt, *got, glink; |
| Elf32_Word num_plt_entries; |
| void (*dlrr) (void); |
| extern void _dl_runtime_resolve (void); |
| extern void _dl_prof_resolve (void); |
| |
| if (__builtin_expect (!profile, 1)) |
| dlrr = _dl_runtime_resolve; |
| else |
| { |
| if (GLRO(dl_profile) != NULL |
| &&_dl_name_match_p (GLRO(dl_profile), map)) |
| GL(dl_profile_map) = map; |
| dlrr = _dl_prof_resolve; |
| } |
| got = (Elf32_Addr *) map->l_info[DT_PPC(GOT)]->d_un.d_ptr; |
| glink = got[1]; |
| got[1] = (Elf32_Addr) dlrr; |
| got[2] = (Elf32_Addr) map; |
| |
| /* Relocate everything in .plt by the load address offset. */ |
| plt = (Elf32_Addr *) D_PTR (map, l_info[DT_PLTGOT]); |
| num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val |
| / sizeof (Elf32_Rela)); |
| |
| /* If a library is prelinked but we have to relocate anyway, |
| we have to be able to undo the prelinking of .plt section. |
| The prelinker saved us at got[1] address of .glink |
| section's start. */ |
| if (glink) |
| { |
| glink += map->l_addr; |
| while (num_plt_entries-- != 0) |
| *plt++ = glink, glink += 4; |
| } |
| else |
| while (num_plt_entries-- != 0) |
| *plt++ += map->l_addr; |
| } |
| return lazy; |
| } |
| |
| /* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */ |
| extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map, |
| Elf32_Addr *reloc_addr, |
| Elf32_Addr finaladdr); |
| |
| static inline Elf32_Addr |
| elf_machine_fixup_plt (struct link_map *map, lookup_t t, |
| const Elf32_Rela *reloc, |
| Elf32_Addr *reloc_addr, Elf64_Addr finaladdr) |
| { |
| if (map->l_info[DT_PPC(GOT)] == 0) |
| /* Handle old style PLT. */ |
| return __elf_machine_fixup_plt (map, reloc_addr, finaladdr); |
| |
| *reloc_addr = finaladdr; |
| return finaladdr; |
| } |
| |
| /* Return the final value of a plt relocation. */ |
| static inline Elf32_Addr |
| elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc, |
| Elf32_Addr value) |
| { |
| return value + reloc->r_addend; |
| } |
| |
| |
| /* Names of the architecture-specific auditing callback functions. */ |
| #define ARCH_LA_PLTENTER ppc32_gnu_pltenter |
| #define ARCH_LA_PLTEXIT ppc32_gnu_pltexit |
| |
| #endif /* dl_machine_h */ |
| |
| #ifdef RESOLVE_MAP |
| |
| /* Do the actual processing of a reloc, once its target address |
| has been determined. */ |
| extern void __process_machine_rela (struct link_map *map, |
| const Elf32_Rela *reloc, |
| struct link_map *sym_map, |
| const Elf32_Sym *sym, |
| const Elf32_Sym *refsym, |
| Elf32_Addr *const reloc_addr, |
| Elf32_Addr finaladdr, |
| int rinfo) attribute_hidden; |
| |
| /* Call _dl_signal_error when a resolved value overflows a relocated area. */ |
| extern void _dl_reloc_overflow (struct link_map *map, |
| const char *name, |
| Elf32_Addr *const reloc_addr, |
| const Elf32_Sym *refsym) attribute_hidden; |
| |
| /* Perform the relocation specified by RELOC and SYM (which is fully resolved). |
| LOADADDR is the load address of the object; INFO is an array indexed |
| by DT_* of the .dynamic section info. */ |
| |
| auto inline void __attribute__ ((always_inline)) |
| elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc, |
| const Elf32_Sym *sym, const struct r_found_version *version, |
| void *const reloc_addr_arg, int skip_ifunc) |
| { |
| Elf32_Addr *const reloc_addr = reloc_addr_arg; |
| const Elf32_Sym *const refsym = sym; |
| Elf32_Addr value; |
| const int r_type = ELF32_R_TYPE (reloc->r_info); |
| struct link_map *sym_map = NULL; |
| |
| #ifndef RESOLVE_CONFLICT_FIND_MAP |
| if (r_type == R_PPC_RELATIVE) |
| { |
| *reloc_addr = map->l_addr + reloc->r_addend; |
| return; |
| } |
| |
| if (__builtin_expect (r_type == R_PPC_NONE, 0)) |
| return; |
| |
| /* binutils on ppc32 includes st_value in r_addend for relocations |
| against local symbols. */ |
| if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0) |
| && sym->st_shndx != SHN_UNDEF) |
| value = map->l_addr; |
| else |
| { |
| sym_map = RESOLVE_MAP (&sym, version, r_type); |
| value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value; |
| } |
| value += reloc->r_addend; |
| #else |
| value = reloc->r_addend; |
| #endif |
| |
| if (sym != NULL |
| && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0) |
| && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1) |
| && __builtin_expect (!skip_ifunc, 1)) |
| value = elf_ifunc_invoke (value); |
| |
| /* A small amount of code is duplicated here for speed. In libc, |
| more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared |
| libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or |
| R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine |
| wouldn't usually handle). As an bonus, doing this here allows |
| the switch statement in __process_machine_rela to work. */ |
| switch (r_type) |
| { |
| case R_PPC_GLOB_DAT: |
| case R_PPC_ADDR32: |
| *reloc_addr = value; |
| break; |
| |
| #ifndef RESOLVE_CONFLICT_FIND_MAP |
| # ifdef RTLD_BOOTSTRAP |
| # define NOT_BOOTSTRAP 0 |
| # else |
| # define NOT_BOOTSTRAP 1 |
| # endif |
| |
| case R_PPC_DTPMOD32: |
| if (!NOT_BOOTSTRAP) |
| /* During startup the dynamic linker is always index 1. */ |
| *reloc_addr = 1; |
| else if (sym_map != NULL) |
| /* Get the information from the link map returned by the |
| RESOLVE_MAP function. */ |
| *reloc_addr = sym_map->l_tls_modid; |
| break; |
| case R_PPC_DTPREL32: |
| /* During relocation all TLS symbols are defined and used. |
| Therefore the offset is already correct. */ |
| if (NOT_BOOTSTRAP && sym_map != NULL) |
| *reloc_addr = TLS_DTPREL_VALUE (sym, reloc); |
| break; |
| case R_PPC_TPREL32: |
| if (!NOT_BOOTSTRAP || sym_map != NULL) |
| { |
| if (NOT_BOOTSTRAP) |
| CHECK_STATIC_TLS (map, sym_map); |
| *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc); |
| } |
| break; |
| #endif |
| |
| case R_PPC_JMP_SLOT: |
| #ifdef RESOLVE_CONFLICT_FIND_MAP |
| RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr); |
| #endif |
| if (map->l_info[DT_PPC(GOT)] != 0) |
| { |
| *reloc_addr = value; |
| break; |
| } |
| /* FALLTHROUGH */ |
| |
| default: |
| __process_machine_rela (map, reloc, sym_map, sym, refsym, |
| reloc_addr, value, r_type); |
| } |
| } |
| |
| auto inline void __attribute__ ((always_inline)) |
| elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc, |
| void *const reloc_addr_arg) |
| { |
| Elf32_Addr *const reloc_addr = reloc_addr_arg; |
| *reloc_addr = l_addr + reloc->r_addend; |
| } |
| |
| auto inline void __attribute__ ((always_inline)) |
| elf_machine_lazy_rel (struct link_map *map, |
| Elf32_Addr l_addr, const Elf32_Rela *reloc, |
| int skip_ifunc) |
| { |
| /* elf_machine_runtime_setup handles this. */ |
| } |
| |
| #endif /* RESOLVE_MAP */ |