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Diffstat (limited to 'sysdeps/x86_64/dl-machine.h')
| -rw-r--r-- | sysdeps/x86_64/dl-machine.h | 417 |
1 files changed, 417 insertions, 0 deletions
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h new file mode 100644 index 0000000000..268c2c31d6 --- /dev/null +++ b/sysdeps/x86_64/dl-machine.h @@ -0,0 +1,417 @@ +/* Machine-dependent ELF dynamic relocation inline functions. x86-64 version. + Copyright (C) 2001 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#ifndef dl_machine_h +#define dl_machine_h + +#define ELF_MACHINE_NAME "x86_64" + +#include <sys/param.h> + +/* Return nonzero iff ELF header is compatible with the running host. */ +static inline int __attribute__ ((unused)) +elf_machine_matches_host (const Elf64_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 Elf64_Addr __attribute__ ((unused)) +elf_machine_dynamic (void) +{ + register Elf64_Addr addr; + + asm ("leaq _DYNAMIC, %0\n" : "=r" (addr)); + return addr; +} + + +/* Return the run-time load address of the shared object. */ +static inline Elf64_Addr __attribute__ ((unused)) +elf_machine_load_address (void) +{ + register Elf64_Addr addr, tmp; + + asm ("leaq _dl_start, %0\n" + "leaq _dl_start(%%rip), %1\n" + "subq %0, %1\n" + : "=r" (tmp), "=r" (addr) : : "cc"); + return addr; +} + +/* 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)) +elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) +{ + Elf64_Addr *got; + extern void _dl_runtime_resolve (Elf64_Word); + extern void _dl_runtime_profile (Elf64_Word); + + 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]); + got[1] = (Elf64_Addr) l; /* Identify this shared object. */ + + /* 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)) + { + got[2] = (Elf64_Addr) &_dl_runtime_profile; + + if (_dl_name_match_p (_dl_profile, l)) + /* This is the object we are looking for. Say that we really + want profiling and the timers are started. */ + _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. */ + got[2] = (Elf64_Addr) &_dl_runtime_resolve; + } + + return lazy; +} + +/* This code is used in dl-runtime.c to call the `fixup' function + and then redirect to the address it returns. */ +#ifndef PROF +# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\ + .text\n\ + .globl _dl_runtime_resolve\n\ + .type _dl_runtime_resolve, @function\n\ + .align 16\n\ +_dl_runtime_resolve:\n\ + pushq %rax # Preserve registers otherwise clobbered.\n\ + pushq %rcx\n\ + pushq %rdx\n\ + pushq %rsi\n\ + pushq %rdi\n\ + pushq %r8\n\ + pushq %r9\n\ + movq 64(%rsp), %rsi # Copy args pushed by PLT in register.\n\ + movq %rsi,%r11 # Multiply by 24\n\ + addq %r11,%rsi\n\ + addq %r11,%rsi\n\ + shlq $3, %rsi\n\ + movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_offset\n\ + call fixup # Call resolver.\n\ + movq %rax, %r11 # Save return value\n\ + popq %r9 # Get register content back.\n\ + popq %r8\n\ + popq %rdi\n\ + popq %rsi\n\ + popq %rdx\n\ + popq %rcx\n\ + popq %rax\n\ + addq $16,%rsp # Adjust stack\n\ + jmp *%r11 # Jump to function address.\n\ + .size _dl_runtime_resolve, .-_dl_runtime_resolve\n\ +\n\ + .globl _dl_runtime_profile\n\ + .type _dl_runtime_profile, @function\n\ + .align 16\n\ +_dl_runtime_profile:\n\ + pushq %rax # Preserve registers otherwise clobbered.\n\ + pushq %rcx\n\ + pushq %rdx\n\ + pushq %rsi\n\ + pushq %rdi\n\ + pushq %r8\n\ + pushq %r9\n\ + movq 72(%rsp), %rdx # Load return address if needed\n\ + movq 64(%rsp), %rsi # Copy args pushed by PLT in register.\n\ + movq %rsi,%r11 # Multiply by 24\n\ + addq %r11,%rsi\n\ + addq %r11,%rsi\n\ + shlq $3, %rsi\n\ + movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_offset\n\ + call profile_fixup # Call resolver.\n\ + movq %rax, %r11 # Save return value\n\ + popq %r9 # Get register content back.\n\ + popq %r8\n\ + popq %rdi\n\ + popq %rsi\n\ + popq %rdx\n\ + popq %rcx\n\ + popq %rax\n\ + addq $16,%rsp # Adjust stack\n\ + jmp *%r11 # Jump to function address.\n\ + .size _dl_runtime_profile, .-_dl_runtime_profile\n\ + .previous\n\ +"); +#else +# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\ + .text\n\ + .globl _dl_runtime_resolve\n\ + .globl _dl_runtime_profile\n\ + .type _dl_runtime_resolve, @function\n\ + .type _dl_runtime_profile, @function\n\ + .align 16\n\ +_dl_runtime_resolve:\n\ +_dl_runtime_profile:\n\ + pushq %rax # Preserve registers otherwise clobbered.\n\ + pushq %rcx\n\ + pushq %rdx\n\ + pushq %rsi\n\ + pushq %rdi\n\ + pushq %r8\n\ + pushq %r9\n\ + movq 64(%rsp), %rsi # Copy args pushed by PLT in register.\n\ + movq %rsi,%r11 # Multiply by 24\n\ + addq %r11,%rsi\n\ + addq %r11,%rsi\n\ + shlq $3, %rsi\n\ + movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_offset\n\ + call fixup # Call resolver.\n\ + movq %rax, %r11 # Save return value\n\ + popq %r9 # Get register content back.\n\ + popq %r8\n\ + popq %rdi\n\ + popq %rsi\n\ + popq %rdx\n\ + popq %rcx\n\ + popq %rax\n\ + addq $16,%rsp # Adjust stack\n\ + jmp *%r11 # Jump to function address.\n\ + .size _dl_runtime_resolve, .-_dl_runtime_resolve\n\ + .size _dl_runtime_profile, .-_dl_runtime_profile\n\ + .previous\n\ +"); +#endif + +/* 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\ + # Store the highest stack address\n\ + movq __libc_stack_end@GOTPCREL(%rip), %rax\n\ + movq %rsp, (%rax)\n\ + # See if we were run as a command with the executable file\n\ + # name as an extra leading argument.\n\ + movq _dl_skip_args@GOTPCREL(%rip), %rax\n\ + movl (%rax), %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\ + # _dl_loaded -> rdi\n\ + movq _dl_loaded@GOTPCREL(%rip), %rdi\n\ + movq (%rdi), %rdi\n\ + # env -> rcx\n\ + leaq 16(%rsp,%rdx,8), %rcx\n\ + # argv -> rdx\n\ + leaq 8(%rsp), %rdx\n\ + # Call the function to run the initializers.\n\ + call _dl_init@PLT\n\ + # Pass our finalizer function to the user in %rdx, as per ELF ABI.\n\ + movq _dl_fini@GOTPCREL(%rip), %rdx\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, 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. */ +#define elf_machine_type_class(type) \ + ((((type) == R_X86_64_JUMP_SLOT) * 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 x86-64 never uses Elf64_Rel relocations. */ +#define ELF_MACHINE_NO_REL 1 + +/* We define an initialization functions. This is called very early in + _dl_sysdep_start. */ +#define DL_PLATFORM_INIT dl_platform_init () + +extern const char *_dl_platform; + +static inline void __attribute__ ((unused)) +dl_platform_init (void) +{ + if (_dl_platform != NULL && *_dl_platform == '\0') + /* Avoid an empty string which would disturb us. */ + _dl_platform = NULL; +} + +static inline Elf64_Addr +elf_machine_fixup_plt (struct link_map *map, lookup_t t, + const Elf64_Rela *reloc, + Elf64_Addr *reloc_addr, Elf64_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 Elf64_Addr +elf_machine_plt_value (struct link_map *map, const Elf64_Rela *reloc, + Elf64_Addr value) +{ + return value; +} + +#endif /* !dl_machine_h */ + +#ifdef RESOLVE + +/* Perform the relocation specified by RELOC and SYM (which is fully resolved). + MAP is the object containing the reloc. */ + +static inline void +elf_machine_rela (struct link_map *map, const Elf64_Rela *reloc, + const Elf64_Sym *sym, const struct r_found_version *version, + Elf64_Addr *const reloc_addr) +{ + const unsigned long int r_type = ELF64_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. */ + weak_extern (_dl_rtld_map); + if (map != &_dl_rtld_map) /* Already done in rtld itself. */ +# endif + *reloc_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 Elf64_Sym *const refsym = sym; +#endif + Elf64_Addr value = RESOLVE (&sym, version, r_type); + if (sym) + value += sym->st_value; + +#ifdef RTLD_BOOTSTRAP + assert (r_type == R_X86_64_GLOB_DAT || r_type == R_X86_64_JUMP_SLOT); + *reloc_addr = value + reloc->r_addend; +#else + switch (r_type) + { + case R_X86_64_GLOB_DAT: + case R_X86_64_JUMP_SLOT: + *reloc_addr = value + reloc->r_addend; + break; + case R_X86_64_64: + *reloc_addr = value + reloc->r_addend; + break; + case R_X86_64_32: + *(unsigned int *) reloc_addr = value + reloc->r_addend; + break; + case R_X86_64_PC32: + *(unsigned int *) reloc_addr = value + reloc->r_addend + - (Elf64_Addr) reloc_addr; + break; + case R_X86_64_COPY: + if (sym == NULL) + /* This can happen in trace mode if an object could not be + found. */ + break; + if (__builtin_expect (sym->st_size > refsym->st_size, 0) + || (__builtin_expect (sym->st_size < refsym->st_size, 0) + && _dl_verbose)) + { + const char *strtab; + + strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]); + _dl_error_printf ("\ +%s: Symbol `%s' has different size in shared object, consider re-linking\n", + _dl_argv[0] ?: "<program name unknown>", + strtab + refsym->st_name); + } + memcpy (reloc_addr, (void *) value, MIN (sym->st_size, + refsym->st_size)); + break; + default: + _dl_reloc_bad_type (map, r_type, 0); + break; + } +#endif + } +} + +static inline void +elf_machine_rela_relative (Elf64_Addr l_addr, const Elf64_Rela *reloc, + Elf64_Addr *const reloc_addr) +{ + assert (ELF64_R_TYPE (reloc->r_info) == R_X86_64_RELATIVE); + *reloc_addr = l_addr + reloc->r_addend; +} + +static inline void +elf_machine_lazy_rel (struct link_map *map, + Elf64_Addr l_addr, const Elf64_Rela *reloc) +{ + Elf64_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset); + const unsigned long int r_type = ELF64_R_TYPE (reloc->r_info); + + /* Check for unexpected PLT reloc type. */ + if (__builtin_expect (r_type == R_X86_64_JUMP_SLOT, 1)) + *reloc_addr += l_addr; + else + _dl_reloc_bad_type (map, r_type, 1); +} + +#endif /* RESOLVE */ |