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Diffstat (limited to 'newlib/libc/sys/linux/machine')
| -rw-r--r-- | newlib/libc/sys/linux/machine/i386/dl-machine.h | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/newlib/libc/sys/linux/machine/i386/dl-machine.h b/newlib/libc/sys/linux/machine/i386/dl-machine.h new file mode 100644 index 000000000..032713e5b --- /dev/null +++ b/newlib/libc/sys/linux/machine/i386/dl-machine.h @@ -0,0 +1,403 @@ +/* Machine-dependent ELF dynamic relocation inline functions. i386 version. + Copyright (C) 1995,96,97,98,99,2000,2001 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, 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 <machine/weakalias.h> + +/* Return nonzero iff ELF header is compatible with the running host. */ +static inline int __attribute__ ((unused)) +elf_machine_matches_host (const Elf32_Ehdr *ehdr) +{ + return ehdr->e_machine == EM_386; +} + + +/* 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 __attribute__ ((unused)) +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 ("leal _dl_start@GOTOFF(%%ebx), %0\n" + "subl _dl_start@GOT(%%ebx), %0" + : "=r" (addr) : : "cc"); + return addr; +} + +#if !defined PROF && !__BOUNDED_POINTERS__ +/* 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. */ +/* GKM FIXME: Fix trampoline to pass bounds so we can do + without the `__unbounded' qualifier. */ +static ElfW(Addr) fixup (struct link_map *__unbounded l, ElfW(Word) reloc_offset) + __attribute__ ((regparm (2), unused)); +static ElfW(Addr) profile_fixup (struct link_map *l, ElfW(Word) reloc_offset, + ElfW(Addr) retaddr) + __attribute__ ((regparm (3), 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 __attribute__ ((unused)) +elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) +{ + Elf32_Addr *got; + extern void _dl_runtime_resolve (Elf32_Word); + extern void _dl_runtime_profile (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 *) D_PTR (l, l_info[DT_PLTGOT]); + got[1] = (Elf32_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] = (Elf32_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] = (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. */ +#if !defined PROF && !__BOUNDED_POINTERS__ +# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\ + .text\n\ + .globl _dl_runtime_resolve\n\ + .type _dl_runtime_resolve, @function\n\ + .align 16\n\ +_dl_runtime_resolve:\n\ + pushl %eax # Preserve registers otherwise clobbered.\n\ + pushl %ecx\n\ + pushl %edx\n\ + movl 16(%esp), %edx # Copy args pushed by PLT in register. Note\n\ + movl 12(%esp), %eax # that `fixup' takes its parameters in regs.\n\ + call fixup # Call resolver.\n\ + popl %edx # Get register content back.\n\ + popl %ecx\n\ + xchgl %eax, (%esp) # Get %eax contents end store function address.\n\ + ret $8 # 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\ + pushl %eax # Preserve registers otherwise clobbered.\n\ + pushl %ecx\n\ + pushl %edx\n\ + movl 20(%esp), %ecx # Load return address\n\ + movl 16(%esp), %edx # Copy args pushed by PLT in register. Note\n\ + movl 12(%esp), %eax # that `fixup' takes its parameters in regs.\n\ + call profile_fixup # Call resolver.\n\ + popl %edx # Get register content back.\n\ + popl %ecx\n\ + xchgl %eax, (%esp) # Get %eax contents end store function address.\n\ + ret $8 # 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\ + pushl %eax # Preserve registers otherwise clobbered.\n\ + pushl %ecx\n\ + pushl %edx\n\ + movl 16(%esp), %edx # Push the arguments for `fixup'\n\ + movl 12(%esp), %eax\n\ + pushl %edx\n\ + pushl %eax\n\ + call fixup # Call resolver.\n\ + popl %edx # Pop the parameters\n\ + popl %ecx\n\ + popl %edx # Get register content back.\n\ + popl %ecx\n\ + xchgl %eax, (%esp) # Get %eax contents end store function address.\n\ + ret $8 # Jump to function address.\n\ + .size _dl_runtime_resolve, .-_dl_runtime_resolve\n\ + .size _dl_runtime_profile, .-_dl_runtime_profile\n\ + .previous\n\ +"); +#endif + +/* 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 ("\n\ + .text\n\ + .align 16\n\ +0: movl (%esp), %ebx\n\ + ret\n\ + .align 16\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.\n\ + call 0b\n\ + addl $_GLOBAL_OFFSET_TABLE_, %ebx\n\ + # Store the highest stack address\n\ + movl __libc_stack_end@GOT(%ebx), %eax\n\ + movl %esp, (%eax)\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 %edx\n\ + # Adjust the stack pointer to skip _dl_skip_args words.\n\ + leal (%esp,%eax,4), %esp\n\ + # Subtract _dl_skip_args from argc.\n\ + subl %eax, %edx\n\ + # Push argc back on the stack.\n\ + push %edx\n\ + # The special initializer gets called with the stack just\n\ + # as the application's entry point will see it; it can\n\ + # switch stacks if it moves these contents over.\n\ +" RTLD_START_SPECIAL_INIT "\n\ + # Load the parameters again.\n\ + # (eax, edx, ecx, *--esp) = (_dl_loaded, argc, argv, envp)\n\ + movl _dl_loaded@GOT(%ebx), %esi\n\ + leal 8(%esp,%edx,4), %eax\n\ + leal 4(%esp), %ecx\n\ + pushl %eax\n\ + movl (%esi), %eax\n\ + # Call the function to run the initializers.\n\ + call _dl_init@PLT\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\ + .previous\n\ +"); + +#ifndef RTLD_START_SPECIAL_INIT +#define RTLD_START_SPECIAL_INIT /* nothing */ +#endif + +/* 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_386_JMP_SLOT) * ELF_RTYPE_CLASS_PLT) \ + | (((type) == R_386_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_386_JMP_SLOT + +/* The i386 never uses Elf32_Rela relocations. */ +#define ELF_MACHINE_NO_RELA 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 Elf32_Addr +elf_machine_fixup_plt (struct link_map *map, lookup_t t, + const Elf32_Rel *reloc, + Elf32_Addr *reloc_addr, Elf32_Addr value) +{ + return *reloc_addr = value; +} + +/* Return the final value of a plt relocation. */ +static inline Elf32_Addr +elf_machine_plt_value (struct link_map *map, const Elf32_Rel *reloc, + Elf32_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_rel (struct link_map *map, const Elf32_Rel *reloc, + const Elf32_Sym *sym, const struct r_found_version *version, + Elf32_Addr *const reloc_addr) +{ + const unsigned int r_type = ELF32_R_TYPE (reloc->r_info); + +#if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC + if (__builtin_expect (r_type == R_386_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; + } +# ifndef RTLD_BOOTSTRAP + else if (__builtin_expect (r_type == R_386_NONE, 0)) + return; +# endif + else +#endif + { +#ifndef RTLD_BOOTSTRAP + const Elf32_Sym *const refsym = sym; +#endif + Elf32_Addr value = RESOLVE (&sym, version, r_type); + if (sym) + value += sym->st_value; + +#ifdef RTLD_BOOTSTRAP + assert (r_type == R_386_GLOB_DAT || r_type == R_386_JMP_SLOT); + *reloc_addr = value; +#else + switch (r_type) + { + case R_386_GLOB_DAT: + case R_386_JMP_SLOT: + *reloc_addr = value; + break; + case R_386_32: + *reloc_addr += value; + break; + case R_386_PC32: + *reloc_addr += (value - (Elf32_Addr) reloc_addr); + break; + case R_386_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_rel_relative (Elf32_Addr l_addr, const Elf32_Rel *reloc, + Elf32_Addr *const reloc_addr) +{ + assert (ELF32_R_TYPE (reloc->r_info) == R_386_RELATIVE); + *reloc_addr += l_addr; +} + +static inline void +elf_machine_lazy_rel (struct link_map *map, + Elf32_Addr l_addr, const Elf32_Rel *reloc) +{ + Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset); + const unsigned int r_type = ELF32_R_TYPE (reloc->r_info); + /* Check for unexpected PLT reloc type. */ + if (__builtin_expect (r_type == R_386_JMP_SLOT, 1)) + *reloc_addr += l_addr; + else + _dl_reloc_bad_type (map, r_type, 1); +} + +#endif /* RESOLVE */ |