| /* Machine-dependent ELF dynamic relocation inline functions. x86-64 version. |
| Copyright (C) 2001-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Andreas Jaeger <aj@suse.de>. |
| |
| 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 "x86_64" |
| |
| #include <sys/param.h> |
| #include <sysdep.h> |
| #include <tls.h> |
| #include <dl-tlsdesc.h> |
| |
| /* Return nonzero iff ELF header is compatible with the running host. */ |
| static inline int __attribute__ ((unused)) |
| elf_machine_matches_host (const ElfW(Ehdr) *ehdr) |
| { |
| return ehdr->e_machine == EM_X86_64; |
| } |
| |
| |
| /* Return the link-time address of _DYNAMIC. Conveniently, this is the |
| first element of the GOT. This must be inlined in a function which |
| uses global data. */ |
| static inline ElfW(Addr) __attribute__ ((unused)) |
| elf_machine_dynamic (void) |
| { |
| /* This produces an IP-relative reloc which is resolved at link time. */ |
| extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden; |
| return _GLOBAL_OFFSET_TABLE_[0]; |
| } |
| |
| |
| /* Return the run-time load address of the shared object. */ |
| static inline ElfW(Addr) __attribute__ ((unused)) |
| elf_machine_load_address (void) |
| { |
| /* Compute the difference between the runtime address of _DYNAMIC as seen |
| by an IP-relative reference, and the link-time address found in the |
| special unrelocated first GOT entry. */ |
| extern ElfW(Dyn) _DYNAMIC[] attribute_hidden; |
| return (ElfW(Addr)) &_DYNAMIC - elf_machine_dynamic (); |
| } |
| |
| /* Set up the loaded object described by L so its unrelocated PLT |
| entries will jump to the on-demand fixup code in dl-runtime.c. */ |
| |
| static inline int __attribute__ ((unused, always_inline)) |
| elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) |
| { |
| Elf64_Addr *got; |
| extern void _dl_runtime_resolve (ElfW(Word)) attribute_hidden; |
| extern void _dl_runtime_profile (ElfW(Word)) attribute_hidden; |
| |
| if (l->l_info[DT_JMPREL] && lazy) |
| { |
| /* The GOT entries for functions in the PLT have not yet been filled |
| in. Their initial contents will arrange when called to push an |
| offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1], |
| and then jump to _GLOBAL_OFFSET_TABLE_[2]. */ |
| got = (Elf64_Addr *) D_PTR (l, l_info[DT_PLTGOT]); |
| /* If a library is prelinked but we have to relocate anyway, |
| we have to be able to undo the prelinking of .got.plt. |
| The prelinker saved us here address of .plt + 0x16. */ |
| if (got[1]) |
| { |
| l->l_mach.plt = got[1] + l->l_addr; |
| l->l_mach.gotplt = (ElfW(Addr)) &got[3]; |
| } |
| /* Identify this shared object. */ |
| *(ElfW(Addr) *) (got + 1) = (ElfW(Addr)) l; |
| |
| /* The got[2] entry contains the address of a function which gets |
| called to get the address of a so far unresolved function and |
| jump to it. The profiling extension of the dynamic linker allows |
| to intercept the calls to collect information. In this case we |
| don't store the address in the GOT so that all future calls also |
| end in this function. */ |
| if (__builtin_expect (profile, 0)) |
| { |
| *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile; |
| |
| if (GLRO(dl_profile) != NULL |
| && _dl_name_match_p (GLRO(dl_profile), l)) |
| /* This is the object we are looking for. Say that we really |
| want profiling and the timers are started. */ |
| GL(dl_profile_map) = l; |
| } |
| else |
| /* This function will get called to fix up the GOT entry indicated by |
| the offset on the stack, and then jump to the resolved address. */ |
| *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_resolve; |
| } |
| |
| if (l->l_info[ADDRIDX (DT_TLSDESC_GOT)] && lazy) |
| *(ElfW(Addr)*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_GOT)]) + l->l_addr) |
| = (ElfW(Addr)) &_dl_tlsdesc_resolve_rela; |
| |
| return lazy; |
| } |
| |
| /* Initial entry point code for the dynamic linker. |
| The C function `_dl_start' is the real entry point; |
| its return value is the user program's entry point. */ |
| #define RTLD_START asm ("\n\ |
| .text\n\ |
| .align 16\n\ |
| .globl _start\n\ |
| .globl _dl_start_user\n\ |
| _start:\n\ |
| movq %rsp, %rdi\n\ |
| call _dl_start\n\ |
| _dl_start_user:\n\ |
| # Save the user entry point address in %r12.\n\ |
| movq %rax, %r12\n\ |
| # See if we were run as a command with the executable file\n\ |
| # name as an extra leading argument.\n\ |
| movl _dl_skip_args(%rip), %eax\n\ |
| # Pop the original argument count.\n\ |
| popq %rdx\n\ |
| # Adjust the stack pointer to skip _dl_skip_args words.\n\ |
| leaq (%rsp,%rax,8), %rsp\n\ |
| # Subtract _dl_skip_args from argc.\n\ |
| subl %eax, %edx\n\ |
| # Push argc back on the stack.\n\ |
| pushq %rdx\n\ |
| # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\ |
| # argc -> rsi\n\ |
| movq %rdx, %rsi\n\ |
| # Save %rsp value in %r13.\n\ |
| movq %rsp, %r13\n\ |
| # And align stack for the _dl_init_internal call. \n\ |
| andq $-16, %rsp\n\ |
| # _dl_loaded -> rdi\n\ |
| movq _rtld_local(%rip), %rdi\n\ |
| # env -> rcx\n\ |
| leaq 16(%r13,%rdx,8), %rcx\n\ |
| # argv -> rdx\n\ |
| leaq 8(%r13), %rdx\n\ |
| # Clear %rbp to mark outermost frame obviously even for constructors.\n\ |
| xorl %ebp, %ebp\n\ |
| # Call the function to run the initializers.\n\ |
| call _dl_init_internal@PLT\n\ |
| # Pass our finalizer function to the user in %rdx, as per ELF ABI.\n\ |
| leaq _dl_fini(%rip), %rdx\n\ |
| # And make sure %rsp points to argc stored on the stack.\n\ |
| movq %r13, %rsp\n\ |
| # Jump to the user's entry point.\n\ |
| jmp *%r12\n\ |
| .previous\n\ |
| "); |
| |
| /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or |
| TLS variable, so undefined references 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. */ |
| #define elf_machine_type_class(type) \ |
| ((((type) == R_X86_64_JUMP_SLOT \ |
| || (type) == R_X86_64_DTPMOD64 \ |
| || (type) == R_X86_64_DTPOFF64 \ |
| || (type) == R_X86_64_TPOFF64 \ |
| || (type) == R_X86_64_TLSDESC) \ |
| * ELF_RTYPE_CLASS_PLT) \ |
| | (((type) == R_X86_64_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_X86_64_JUMP_SLOT |
| |
| /* The relative ifunc relocation. */ |
| // XXX This is a work-around for a broken linker. Remove! |
| #define ELF_MACHINE_IRELATIVE R_X86_64_IRELATIVE |
| |
| /* The x86-64 never uses Elf64_Rel/Elf32_Rel relocations. */ |
| #define ELF_MACHINE_NO_REL 1 |
| |
| /* We define an initialization function. This is called very early in |
| _dl_sysdep_start. */ |
| #define DL_PLATFORM_INIT dl_platform_init () |
| |
| static inline void __attribute__ ((unused)) |
| dl_platform_init (void) |
| { |
| if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0') |
| /* Avoid an empty string which would disturb us. */ |
| GLRO(dl_platform) = NULL; |
| } |
| |
| static inline ElfW(Addr) |
| elf_machine_fixup_plt (struct link_map *map, lookup_t t, |
| const ElfW(Rela) *reloc, |
| ElfW(Addr) *reloc_addr, ElfW(Addr) value) |
| { |
| return *reloc_addr = value; |
| } |
| |
| /* Return the final value of a PLT relocation. On x86-64 the |
| JUMP_SLOT relocation ignores the addend. */ |
| static inline ElfW(Addr) |
| elf_machine_plt_value (struct link_map *map, const ElfW(Rela) *reloc, |
| ElfW(Addr) value) |
| { |
| return value; |
| } |
| |
| |
| /* Names of the architecture-specific auditing callback functions. */ |
| #define ARCH_LA_PLTENTER x86_64_gnu_pltenter |
| #define ARCH_LA_PLTEXIT x86_64_gnu_pltexit |
| |
| #endif /* !dl_machine_h */ |
| |
| #ifdef RESOLVE_MAP |
| |
| /* Perform the relocation specified by RELOC and SYM (which is fully resolved). |
| MAP is the object containing the reloc. */ |
| |
| auto inline void |
| __attribute__ ((always_inline)) |
| elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc, |
| const ElfW(Sym) *sym, const struct r_found_version *version, |
| void *const reloc_addr_arg, int skip_ifunc) |
| { |
| ElfW(Addr) *const reloc_addr = reloc_addr_arg; |
| const unsigned long int r_type = ELFW(R_TYPE) (reloc->r_info); |
| |
| # if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC |
| if (__builtin_expect (r_type == R_X86_64_RELATIVE, 0)) |
| { |
| # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC |
| /* This is defined in rtld.c, but nowhere in the static libc.a; |
| make the reference weak so static programs can still link. |
| This declaration cannot be done when compiling rtld.c |
| (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the |
| common defn for _dl_rtld_map, which is incompatible with a |
| weak decl in the same file. */ |
| # ifndef SHARED |
| weak_extern (GL(dl_rtld_map)); |
| # endif |
| if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */ |
| # endif |
| *reloc_addr = map->l_addr + reloc->r_addend; |
| } |
| else |
| # endif |
| # if !defined RTLD_BOOTSTRAP |
| /* l_addr + r_addend may be > 0xffffffff and R_X86_64_RELATIVE64 |
| relocation updates the whole 64-bit entry. */ |
| if (__builtin_expect (r_type == R_X86_64_RELATIVE64, 0)) |
| *(Elf64_Addr *) reloc_addr = (Elf64_Addr) map->l_addr + reloc->r_addend; |
| else |
| # endif |
| if (__builtin_expect (r_type == R_X86_64_NONE, 0)) |
| return; |
| else |
| { |
| # ifndef RTLD_BOOTSTRAP |
| const ElfW(Sym) *const refsym = sym; |
| # endif |
| struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type); |
| ElfW(Addr) value = (sym == NULL ? 0 |
| : (ElfW(Addr)) sym_map->l_addr + sym->st_value); |
| |
| 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 = ((ElfW(Addr) (*) (void)) value) (); |
| |
| switch (r_type) |
| { |
| # ifndef RTLD_BOOTSTRAP |
| # ifdef __ILP32__ |
| case R_X86_64_SIZE64: |
| /* Set to symbol size plus addend. */ |
| *(Elf64_Addr *) (uintptr_t) reloc_addr |
| = (Elf64_Addr) sym->st_size + reloc->r_addend; |
| break; |
| |
| case R_X86_64_SIZE32: |
| # else |
| case R_X86_64_SIZE64: |
| # endif |
| /* Set to symbol size plus addend. */ |
| value = sym->st_size; |
| # endif |
| case R_X86_64_GLOB_DAT: |
| case R_X86_64_JUMP_SLOT: |
| *reloc_addr = value + reloc->r_addend; |
| break; |
| |
| # ifndef RESOLVE_CONFLICT_FIND_MAP |
| case R_X86_64_DTPMOD64: |
| # ifdef RTLD_BOOTSTRAP |
| /* During startup the dynamic linker is always the module |
| with index 1. |
| XXX If this relocation is necessary move before RESOLVE |
| call. */ |
| *reloc_addr = 1; |
| # else |
| /* Get the information from the link map returned by the |
| resolve function. */ |
| if (sym_map != NULL) |
| *reloc_addr = sym_map->l_tls_modid; |
| # endif |
| break; |
| case R_X86_64_DTPOFF64: |
| # ifndef RTLD_BOOTSTRAP |
| /* During relocation all TLS symbols are defined and used. |
| Therefore the offset is already correct. */ |
| if (sym != NULL) |
| { |
| value = sym->st_value + reloc->r_addend; |
| # ifdef __ILP32__ |
| /* This relocation type computes a signed offset that is |
| usually negative. The symbol and addend values are 32 |
| bits but the GOT entry is 64 bits wide and the whole |
| 64-bit entry is used as a signed quantity, so we need |
| to sign-extend the computed value to 64 bits. */ |
| *(Elf64_Sxword *) reloc_addr = (Elf64_Sxword) (Elf32_Sword) value; |
| # else |
| *reloc_addr = value; |
| # endif |
| } |
| # endif |
| break; |
| case R_X86_64_TLSDESC: |
| { |
| struct tlsdesc volatile *td = |
| (struct tlsdesc volatile *)reloc_addr; |
| |
| # ifndef RTLD_BOOTSTRAP |
| if (! sym) |
| { |
| td->arg = (void*)reloc->r_addend; |
| td->entry = _dl_tlsdesc_undefweak; |
| } |
| else |
| # endif |
| { |
| # ifndef RTLD_BOOTSTRAP |
| # ifndef SHARED |
| CHECK_STATIC_TLS (map, sym_map); |
| # else |
| if (!TRY_STATIC_TLS (map, sym_map)) |
| { |
| td->arg = _dl_make_tlsdesc_dynamic |
| (sym_map, sym->st_value + reloc->r_addend); |
| td->entry = _dl_tlsdesc_dynamic; |
| } |
| else |
| # endif |
| # endif |
| { |
| td->arg = (void*)(sym->st_value - sym_map->l_tls_offset |
| + reloc->r_addend); |
| td->entry = _dl_tlsdesc_return; |
| } |
| } |
| break; |
| } |
| case R_X86_64_TPOFF64: |
| /* The offset is negative, forward from the thread pointer. */ |
| # ifndef RTLD_BOOTSTRAP |
| if (sym != NULL) |
| # endif |
| { |
| # ifndef RTLD_BOOTSTRAP |
| CHECK_STATIC_TLS (map, sym_map); |
| # endif |
| /* We know the offset of the object the symbol is contained in. |
| It is a negative value which will be added to the |
| thread pointer. */ |
| value = (sym->st_value + reloc->r_addend |
| - sym_map->l_tls_offset); |
| # ifdef __ILP32__ |
| /* The symbol and addend values are 32 bits but the GOT |
| entry is 64 bits wide and the whole 64-bit entry is used |
| as a signed quantity, so we need to sign-extend the |
| computed value to 64 bits. */ |
| *(Elf64_Sxword *) reloc_addr = (Elf64_Sxword) (Elf32_Sword) value; |
| # else |
| *reloc_addr = value; |
| # endif |
| } |
| break; |
| # endif |
| |
| # ifndef RTLD_BOOTSTRAP |
| case R_X86_64_64: |
| /* value + r_addend may be > 0xffffffff and R_X86_64_64 |
| relocation updates the whole 64-bit entry. */ |
| *(Elf64_Addr *) reloc_addr = (Elf64_Addr) value + reloc->r_addend; |
| break; |
| # ifndef __ILP32__ |
| case R_X86_64_SIZE32: |
| /* Set to symbol size plus addend. */ |
| value = sym->st_size; |
| # endif |
| case R_X86_64_32: |
| value += reloc->r_addend; |
| *(unsigned int *) reloc_addr = value; |
| |
| const char *fmt; |
| if (__builtin_expect (value > UINT_MAX, 0)) |
| { |
| const char *strtab; |
| |
| fmt = "\ |
| %s: Symbol `%s' causes overflow in R_X86_64_32 relocation\n"; |
| # ifndef RESOLVE_CONFLICT_FIND_MAP |
| print_err: |
| # endif |
| strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]); |
| |
| _dl_error_printf (fmt, RTLD_PROGNAME, strtab + refsym->st_name); |
| } |
| break; |
| # ifndef RESOLVE_CONFLICT_FIND_MAP |
| /* Not needed for dl-conflict.c. */ |
| case R_X86_64_PC32: |
| value += reloc->r_addend - (ElfW(Addr)) reloc_addr; |
| *(unsigned int *) reloc_addr = value; |
| if (__builtin_expect (value != (int) value, 0)) |
| { |
| fmt = "\ |
| %s: Symbol `%s' causes overflow in R_X86_64_PC32 relocation\n"; |
| goto print_err; |
| } |
| break; |
| case R_X86_64_COPY: |
| if (sym == NULL) |
| /* This can happen in trace mode if an object could not be |
| found. */ |
| break; |
| memcpy (reloc_addr_arg, (void *) value, |
| MIN (sym->st_size, refsym->st_size)); |
| if (__builtin_expect (sym->st_size > refsym->st_size, 0) |
| || (__builtin_expect (sym->st_size < refsym->st_size, 0) |
| && GLRO(dl_verbose))) |
| { |
| fmt = "\ |
| %s: Symbol `%s' has different size in shared object, consider re-linking\n"; |
| goto print_err; |
| } |
| break; |
| # endif |
| case R_X86_64_IRELATIVE: |
| value = map->l_addr + reloc->r_addend; |
| value = ((ElfW(Addr) (*) (void)) value) (); |
| *reloc_addr = value; |
| break; |
| default: |
| _dl_reloc_bad_type (map, r_type, 0); |
| break; |
| # endif |
| } |
| } |
| } |
| |
| auto inline void |
| __attribute ((always_inline)) |
| elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc, |
| void *const reloc_addr_arg) |
| { |
| ElfW(Addr) *const reloc_addr = reloc_addr_arg; |
| #if !defined RTLD_BOOTSTRAP |
| /* l_addr + r_addend may be > 0xffffffff and R_X86_64_RELATIVE64 |
| relocation updates the whole 64-bit entry. */ |
| if (__builtin_expect (ELFW(R_TYPE) (reloc->r_info) == R_X86_64_RELATIVE64, 0)) |
| *(Elf64_Addr *) reloc_addr = (Elf64_Addr) l_addr + reloc->r_addend; |
| else |
| #endif |
| { |
| assert (ELFW(R_TYPE) (reloc->r_info) == R_X86_64_RELATIVE); |
| *reloc_addr = l_addr + reloc->r_addend; |
| } |
| } |
| |
| auto inline void |
| __attribute ((always_inline)) |
| elf_machine_lazy_rel (struct link_map *map, |
| ElfW(Addr) l_addr, const ElfW(Rela) *reloc, |
| int skip_ifunc) |
| { |
| ElfW(Addr) *const reloc_addr = (void *) (l_addr + reloc->r_offset); |
| const unsigned long int r_type = ELFW(R_TYPE) (reloc->r_info); |
| |
| /* Check for unexpected PLT reloc type. */ |
| if (__builtin_expect (r_type == R_X86_64_JUMP_SLOT, 1)) |
| { |
| if (__builtin_expect (map->l_mach.plt, 0) == 0) |
| *reloc_addr += l_addr; |
| else |
| *reloc_addr = |
| map->l_mach.plt |
| + (((ElfW(Addr)) reloc_addr) - map->l_mach.gotplt) * 2; |
| } |
| else if (__builtin_expect (r_type == R_X86_64_TLSDESC, 1)) |
| { |
| struct tlsdesc volatile * __attribute__((__unused__)) td = |
| (struct tlsdesc volatile *)reloc_addr; |
| |
| td->arg = (void*)reloc; |
| td->entry = (void*)(D_PTR (map, l_info[ADDRIDX (DT_TLSDESC_PLT)]) |
| + map->l_addr); |
| } |
| else if (__builtin_expect (r_type == R_X86_64_IRELATIVE, 0)) |
| { |
| ElfW(Addr) value = map->l_addr + reloc->r_addend; |
| if (__builtin_expect (!skip_ifunc, 1)) |
| value = ((ElfW(Addr) (*) (void)) value) (); |
| *reloc_addr = value; |
| } |
| else |
| _dl_reloc_bad_type (map, r_type, 1); |
| } |
| |
| #endif /* RESOLVE_MAP */ |