/* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
/* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */
/* Copyright (C) 2014 OSCAR lab, Stony Brook University
This file is part of Graphene Library OS.
Graphene Library OS is free software: you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
Graphene Library OS 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see . */
/*
* dl-machine-x86_64.h
*
* This files contain architecture-specific implementation of ELF dynamic
* relocation function.
* The source code is imported and modified from the GNU C Library.
*/
#ifndef dl_machine_h
#define dl_machine_h
#define ELF_MACHINE_NAME "x86_64"
#include
#include
#include
#include "pal_internal.h"
/* The x86-64 never uses Elf64_Rel relocations. */
#define ELF_MACHINE_NO_REL 1
/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
MAP is the object containing the reloc. */
//#define DEBUG_RELOC
static void
elf_machine_rela (Elf64_Dyn **l_info, Elf64_Addr l_addr,
Elf64_Rela *reloc, Elf64_Sym *sym, void *const reloc_addr_arg,
bool rel, bool rel_relative)
{
Elf64_Addr *const reloc_addr = reloc_addr_arg;
const unsigned long int r_type = ELF64_R_TYPE (reloc->r_info);
const char * __attribute__ ((unused)) strtab =
(const void *) D_PTR (l_info[DT_STRTAB]);
#ifdef DEBUG_RELOC
#define elf_machine_rela_debug(r_type, sym, value) \
({ if (strtab && sym && sym->st_name) \
printf(#r_type ": %s\n", strtab + sym->st_name); \
else if (value) \
printf(#r_type ": %p\n", value); \
else \
printf(#r_type "\n", value); \
})
#else
#define elf_machine_rela_debug(...) ({})
#endif
if (__builtin_expect (r_type == R_X86_64_RELATIVE, 0))
{
/* 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. */
if (rel_relative)
{
#ifndef RTLD_BOOTSTRAP
elf_machine_rela_debug (R_X86_64_RELATIVE, sym, 0);
*reloc_addr = l_addr + reloc->r_addend;
#endif
}
return;
}
if (__builtin_expect (r_type == R_X86_64_NONE, 0))
{
elf_machine_rela_debug (R_X86_64_NONE, sym, 0);
return;
}
#ifdef RTLD_BOOTSTRAP
Elf64_Addr value = (sym == NULL ? 0 : l_addr + sym->st_value);
#define SYM (sym)
#else
Elf64_Sym *refsym = sym;
Elf64_Addr value;
Elf64_Addr sym_map = 0;
value = RESOLVE_RTLD(strtab + sym->st_name);
if (value) {
/* We can't handle a IRELEATIVE symbol if it's found in RTLD,
they should never exist */
if (r_type == R_X86_64_IRELATIVE)
return;
} else {
sym_map = RESOLVE_MAP(&strtab, &sym) ? : l_addr;
value = sym_map + (sym ? sym->st_value : refsym->st_value);
}
#define SYM (sym ? : refsym)
/* We do a very special relocation for loaded libraries */
if (!rel) {
if (sym && refsym && refsym != sym) {
refsym->st_info = sym->st_info;
refsym->st_size = sym->st_size;
if (__builtin_expect (ELFW(ST_TYPE) (sym->st_info)
== STT_GNU_IFUNC, 0)
&& __builtin_expect (sym->st_shndx != SHN_UNDEF, 1))
{
value = ((Elf64_Addr (*) (void)) value) ();
refsym->st_info ^= ELFW(ST_TYPE)(sym->st_info);
refsym->st_info |= STT_FUNC;
}
refsym->st_value = value - l_addr;
} else {
return;
}
}
#endif
if (sym != NULL
&& __builtin_expect (ELFW(ST_TYPE) (sym->st_info)
== STT_GNU_IFUNC, 0)
&& __builtin_expect (sym->st_shndx != SHN_UNDEF, 1))
value = ((Elf64_Addr (*) (void)) value) ();
/* In the libc loader, they guaranteed that only R_ARCH_RELATIVE,
R_ARCH_GLOB_DAT, R_ARCH_JUMP_SLOT appear in ld.so. We observed
the same thing in libpal.so, so we are gonna to make the same
assumption */
switch (r_type)
{
case R_X86_64_GLOB_DAT:
elf_machine_rela_debug (R_X86_64_GLOB_DAT, SYM, value);
*reloc_addr = value + reloc->r_addend;
break;
case R_X86_64_JUMP_SLOT:
elf_machine_rela_debug (R_X86_64_JUMP_SLOT, SYM, value);
*reloc_addr = value + reloc->r_addend;
break;
#ifndef RTLD_BOOTSTRAP
case R_X86_64_64:
elf_machine_rela_debug (R_X86_64_64, SYM, value);
*reloc_addr = value + reloc->r_addend;
break;
case R_X86_64_32:
elf_machine_rela_debug (R_X86_64_32, SYM, value);
value += reloc->r_addend;
*(Elf64_Addr *) reloc_addr = value;
break;
/* Not needed for dl-conflict.c. */
case R_X86_64_PC32:
elf_machine_rela_debug (R_X86_64_PC32, SYM, value);
value += reloc->r_addend - (Elf64_Addr) reloc_addr;
*(Elf64_Addr *) reloc_addr = value;
break;
case R_X86_64_COPY:
elf_machine_rela_debug (R_X86_64_COPY, SYM, value);
size_t sym_size = sym ? sym->st_size : 0;
size_t ref_size = refsym ? refsym->st_size : 0;
memcpy (reloc_addr_arg, (void *) value, MIN (sym_size,
ref_size));
break;
case R_X86_64_IRELATIVE:
elf_machine_rela_debug (R_X86_64_IRELATIVE, SYM, value);
value = sym_map + reloc->r_addend;
value = ((Elf64_Addr (*) (void)) value) ();
*reloc_addr = value;
break;
#endif
default:
return;
}
if (!rel)
/* We have relocated the symbol, we don't want the
interpreter to relocate it again. */
reloc->r_info ^= ELF64_R_TYPE (reloc->r_info);
}
static void
elf_machine_rela_relative (Elf64_Addr l_addr, const Elf64_Rela *reloc,
void *const reloc_addr_arg)
{
Elf64_Addr *const reloc_addr = reloc_addr_arg;
assert (ELF64_R_TYPE (reloc->r_info) == R_X86_64_RELATIVE);
*reloc_addr = l_addr + reloc->r_addend;
}
#endif /* !dl_machine_h */