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f2b0f935d7
from zero fill. * elf/dl-lookup.c (_dl_lookup_symbol): Take new flag arg NOSELF; if nonzero, don't let *REF satisfy the reference itself. * elf/link.h (_dl_lookup_symbol): Add new arg NOSELF in decl. * sysdeps/i386/dl-runtime.c (_dl_runtime_resolve): Pass new arg to _dl_lookup_symbol. * elf/do-rel.h (elf_dynamic_do_rel): Pass new second arg of R->r_offset to RESOLVE callback. * elf/dl-reloc.c (_dl_relocate_object: resolve): Don't let *REF satisfy the reference itself if its value equals the reloc's offset. * elf/rtld.c (dl_main): Write a newline in fatal msg. * Makerules (lib%.so: lib%_pic.a): Pass $(LDFLAGS.so).
95 lines
3.3 KiB
C
95 lines
3.3 KiB
C
/* On-demand PLT fixup for shared objects. i386 version.
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Copyright (C) 1995 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <link.h>
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#include "dynamic-link.h"
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/* This function is not called in the normal way. The PLT jumps here, not
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using a call. The stack looks like this:
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-->8(%esp) address to return to the caller of the function in the PLT
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4(%esp) relocation offset for this PLT entry
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0(%esp) identifier for this shared object (struct link_map *)
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The user expects the real function the PLT refers to to be entered
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with 8(%esp) as the top of stack. */
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void
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_dl_runtime_resolve (Elf32_Word reloc_offset)
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{
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__label__ return_insn;
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struct link_map *l = (void *) (&reloc_offset)[-1];
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const Elf32_Sym *const symtab
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= (const Elf32_Sym *) (l->l_addr + l->l_info[DT_SYMTAB]->d_un.d_ptr);
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const char *strtab =
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(const char *) (l->l_addr + l->l_info[DT_STRTAB]->d_un.d_ptr);
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const Elf32_Rel *const reloc
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= (const void *) (l->l_addr + l->l_info[DT_JMPREL]->d_un.d_ptr +
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reloc_offset);
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const Elf32_Sym *definer;
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Elf32_Addr loadbase;
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struct link_map *scope, *real_next;
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/* Look up the symbol's run-time value. */
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real_next = l->l_next;
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if (l->l_info[DT_SYMBOLIC])
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{
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l->l_next = _dl_loaded;
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if (l->l_prev)
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l->l_prev->l_next = real_next;
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scope = l;
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}
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else
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scope = _dl_loaded;
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definer = &symtab[ELF32_R_SYM (reloc->r_info)];
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loadbase = _dl_lookup_symbol (strtab + definer->st_name, &definer,
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scope, l->l_name, 0);
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/* Restore list frobnication done above for DT_SYMBOLIC. */
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l->l_next = real_next;
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if (l->l_prev)
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l->l_prev->l_next = l;
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/* Apply the relocation with that value. */
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elf_machine_rel (l, reloc, loadbase, definer);
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/* The top of the stack is the word we set L from; but this location
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holds the address we will return to. Store there the address of a
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"ret" instruction, which will pop the stack and run the code at the
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address in the next stack word. */
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(&reloc_offset)[-1] = (Elf32_Word) &&return_insn;
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/* The next stack word is our argument RELOC_OFFSET; but that "ret" will
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pop and jump to this location, and the next stack word is the user's
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return address. So store here the resolved address of the function
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referred to by this PLT entry; once "ret" pops this address, the
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function in the shared object will run with the stack arranged just as
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when the user entered the PLT. */
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(&reloc_offset)[0] = *(Elf32_Word *) (l->l_addr + reloc->r_offset);
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return;
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return_insn: asm volatile ("ret");
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}
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