| /* Machine-dependent ELF dynamic relocation inline functions. i386 version. |
| Copyright (C) 1995, 1996, 1997 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 Library General Public License as |
| published by the Free Software Foundation; either version 2 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 |
| Library General Public License for more details. |
| |
| You should have received a copy of the GNU Library General Public |
| License along with the GNU C Library; see the file COPYING.LIB. 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 "i386" |
| |
| #include <sys/param.h> |
| |
| #include <assert.h> |
| |
| /* Return nonzero iff E_MACHINE is compatible with the running host. */ |
| static inline int __attribute__ ((unused)) |
| elf_machine_matches_host (Elf32_Half e_machine) |
| { |
| switch (e_machine) |
| { |
| case EM_386: |
| case EM_486: |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| |
| /* 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 Elf32_Addr |
| elf_machine_dynamic (void) |
| { |
| register Elf32_Addr *got asm ("%ebx"); |
| return *got; |
| } |
| |
| |
| /* Return the run-time load address of the shared object. */ |
| static inline Elf32_Addr __attribute__ ((unused)) |
| elf_machine_load_address (void) |
| { |
| Elf32_Addr addr; |
| asm (" call .Lhere\n" |
| ".Lhere: popl %0\n" |
| " subl $.Lhere, %0" |
| : "=r" (addr)); |
| return addr; |
| } |
| /* The `subl' insn above will contain an R_386_32 relocation entry |
| intended to insert the run-time address of the label `.Lhere'. |
| This will be the first relocation in the text of the dynamic linker; |
| we skip it to avoid trying to modify read-only text in this early stage. */ |
| #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \ |
| ++(const Elf32_Rel *) (dynamic_info)[DT_REL]->d_un.d_ptr; \ |
| (dynamic_info)[DT_RELSZ]->d_un.d_val -= sizeof (Elf32_Rel); |
| |
| |
| #ifndef PROF |
| /* We add a declaration of this function here so that in dl-runtime.c |
| the ELF_MACHINE_RUNTIME_TRAMPOLINE macro really can pass the parameters |
| in registers. |
| |
| We cannot use this scheme for profiling because the _mcount call |
| destroys the passed register information. */ |
| static ElfW(Addr) fixup (struct link_map *l, ElfW(Word) reloc_offset) |
| __attribute__ ((regparm (2), unused)); |
| #endif |
| |
| /* 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 |
| elf_machine_runtime_setup (struct link_map *l, int lazy) |
| { |
| Elf32_Addr *got; |
| extern void _dl_runtime_resolve (Elf32_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 = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr); |
| got[1] = (Elf32_Addr) l; /* Identify this shared object. */ |
| /* 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] = (Elf32_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 ("\ |
| .globl _dl_runtime_resolve |
| .type _dl_runtime_resolve, @function |
| _dl_runtime_resolve: |
| pushl %eax # Preserve registers otherwise clobbered. |
| pushl %ecx |
| pushl %edx |
| movl 16(%esp), %edx # Copy args pushed by PLT in register. Note |
| movl 12(%esp), %eax # that `fixup' takes its parameters in regs. |
| call fixup # Call resolver. |
| popl %edx # Get register content back. |
| popl %ecx |
| xchgl %eax, (%esp) # Get %eax contents end store function address. |
| ret $8 # Jump to function address. |
| .size _dl_runtime_resolve, .-_dl_runtime_resolve |
| "); |
| #else |
| # define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\ |
| .globl _dl_runtime_resolve |
| .type _dl_runtime_resolve, @function |
| _dl_runtime_resolve: |
| pushl %eax # Preserve registers otherwise clobbered. |
| pushl %ecx |
| pushl %edx |
| movl 16(%esp), %edx # Push the arguments for `fixup' |
| movl 12(%esp), %eax |
| pushl %edx |
| pushl %eax |
| call fixup # Call resolver. |
| popl %edx # Pop the parameters |
| popl %ecx |
| popl %edx # Get register content back. |
| popl %ecx |
| xchgl %eax, (%esp) # Get %eax contents end store function address. |
| ret $8 # Jump to function address. |
| .size _dl_runtime_resolve, .-_dl_runtime_resolve |
| "); |
| #endif |
| /* The PLT uses Elf32_Rel relocs. */ |
| #define elf_machine_relplt elf_machine_rel |
| |
| /* Mask identifying addresses reserved for the user program, |
| where the dynamic linker should not map anything. */ |
| #define ELF_MACHINE_USER_ADDRESS_MASK 0xf8000000UL |
| |
| |
| |
| /* 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 ("\ |
| .text\n\ |
| .globl _start\n\ |
| .globl _dl_start_user\n\ |
| _start:\n\ |
| pushl %esp\n\ |
| call _dl_start\n\ |
| popl %ebx\n\ |
| _dl_start_user:\n\ |
| # Save the user entry point address in %edi.\n\ |
| movl %eax, %edi\n\ |
| # Point %ebx at the GOT. |
| call 0f\n\ |
| 0: popl %ebx\n\ |
| addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %ebx\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@GOT(%ebx), %eax\n\ |
| movl (%eax), %eax\n\ |
| # Pop the original argument count.\n\ |
| popl %ecx\n\ |
| # Subtract _dl_skip_args from it.\n\ |
| subl %eax, %ecx\n\ |
| # Adjust the stack pointer to skip _dl_skip_args words.\n\ |
| leal (%esp,%eax,4), %esp\n\ |
| # Push back the modified argument count.\n\ |
| pushl %ecx\n\ |
| # Push _dl_default_scope[2] as argument in _dl_init_next call below.\n\ |
| movl _dl_default_scope@GOT(%ebx), %eax\n\ |
| movl 8(%eax), %esi\n\ |
| 0: pushl %esi\n\ |
| # Call _dl_init_next to return the address of an initializer\n\ |
| # function to run.\n\ |
| call _dl_init_next@PLT\n\ |
| addl $4, %esp # Pop argument.\n\ |
| # Check for zero return, when out of initializers.\n\ |
| testl %eax, %eax\n\ |
| jz 1f\n\ |
| # Call the shared object initializer function.\n\ |
| # NOTE: We depend only on the registers (%ebx, %esi and %edi)\n\ |
| # and the return address pushed by this call;\n\ |
| # the initializer is called with the stack just\n\ |
| # as it appears on entry, and it is free to move\n\ |
| # the stack around, as long as it winds up jumping to\n\ |
| # the return address on the top of the stack.\n\ |
| call *%eax\n\ |
| # Loop to call _dl_init_next for the next initializer.\n\ |
| jmp 0b\n\ |
| 1: # Clear the startup flag.\n\ |
| movl _dl_starting_up@GOT(%ebx), %eax\n\ |
| movl $0, (%eax)\n\ |
| # Pass our finalizer function to the user in %edx, as per ELF ABI.\n\ |
| movl _dl_fini@GOT(%ebx), %edx\n\ |
| # Jump to the user's entry point.\n\ |
| jmp *%edi\n\ |
| "); |
| |
| /* Nonzero iff TYPE should not be allowed to resolve to one of |
| the main executable's symbols, as for a COPY reloc. */ |
| #define elf_machine_lookup_noexec_p(type) ((type) == R_386_COPY) |
| |
| /* Nonzero iff TYPE describes relocation of a PLT entry, so |
| PLT entries should not be allowed to define the value. */ |
| #define elf_machine_lookup_noplt_p(type) ((type) == R_386_JMP_SLOT) |
| |
| /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */ |
| #define ELF_MACHINE_RELOC_NOPLT R_386_JMP_SLOT |
| |
| /* The i386 never uses Elf32_Rela relocations. */ |
| #define ELF_MACHINE_NO_RELA 1 |
| |
| #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_rel (struct link_map *map, const Elf32_Rel *reloc, |
| const Elf32_Sym *sym, const struct r_found_version *version) |
| { |
| Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset); |
| |
| if (ELF32_R_TYPE (reloc->r_info) == R_386_RELATIVE) |
| { |
| #ifndef RTLD_BOOTSTRAP |
| if (map != &_dl_rtld_map) /* Already done in rtld itself. */ |
| #endif |
| *reloc_addr += map->l_addr; |
| } |
| else if (ELF32_R_TYPE (reloc->r_info) != R_386_NONE) |
| { |
| const Elf32_Sym *const refsym = sym; |
| Elf32_Addr value = RESOLVE (&sym, version, ELF32_R_TYPE (reloc->r_info)); |
| if (sym) |
| value += sym->st_value; |
| |
| switch (ELF32_R_TYPE (reloc->r_info)) |
| { |
| case R_386_COPY: |
| if (sym->st_size > refsym->st_size |
| || (_dl_verbose && sym->st_size < refsym->st_size)) |
| { |
| const char *strtab; |
| |
| strtab = ((void *) map->l_addr |
| + map->l_info[DT_STRTAB]->d_un.d_ptr); |
| _dl_sysdep_error ("Symbol `", strtab + refsym->st_name, |
| "' has different size in shared object, " |
| "consider re-linking\n", NULL); |
| } |
| memcpy (reloc_addr, (void *) value, MIN (sym->st_size, |
| refsym->st_size)); |
| break; |
| case R_386_GLOB_DAT: |
| case R_386_JMP_SLOT: |
| *reloc_addr = value; |
| break; |
| case R_386_32: |
| { |
| #ifndef RTLD_BOOTSTRAP |
| /* 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) |
| /* Undo the relocation done here during bootstrapping. |
| Now we will relocate it anew, possibly using a |
| binding found in the user program or a loaded library |
| rather than the dynamic linker's built-in definitions |
| used while loading those libraries. */ |
| value -= map->l_addr + refsym->st_value; |
| #endif |
| *reloc_addr += value; |
| break; |
| } |
| case R_386_PC32: |
| *reloc_addr += (value - (Elf32_Addr) reloc_addr); |
| break; |
| default: |
| assert (! "unexpected dynamic reloc type"); |
| break; |
| } |
| } |
| } |
| |
| static inline void |
| elf_machine_lazy_rel (struct link_map *map, const Elf32_Rel *reloc) |
| { |
| Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset); |
| switch (ELF32_R_TYPE (reloc->r_info)) |
| { |
| case R_386_JMP_SLOT: |
| *reloc_addr += map->l_addr; |
| break; |
| default: |
| assert (! "unexpected PLT reloc type"); |
| break; |
| } |
| } |
| |
| #endif /* RESOLVE */ |