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/* This file is part of centaur.
*
* centaur is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License 2 as
* published by the Free Software Foundation.
* centaur 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 centaur. If not, see <http://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <libelfu/libelfu.h>
/* Apply relocation information from section *msrt to data in
* section *mstarget (which is stored in *metarget). */
int elfu_mRelocate(ElfuElf *metarget, ElfuScn *mstarget, ElfuScn *msrt)
{
ElfuRel *rel;
ElfuSym *sym;
assert(mstarget);
assert(msrt);
ELFU_DEBUG("Relocating in section of type %u size %x\n",
mstarget->shdr.sh_type,
(unsigned)mstarget->shdr.sh_size);
CIRCLEQ_FOREACH(rel, &msrt->reltab.rels, elem) {
Elf32_Word *dest32 = (Elf32_Word*)(mstarget->databuf + rel->offset);
Elf64_Word *dest64 = (Elf64_Word*)(mstarget->databuf + rel->offset);
GElf_Addr s;
int haveSymval = 0;
sym = elfu_mSymtabIndexToSym(msrt->linkptr, rel->sym);
assert(sym);
haveSymval = !elfu_mSymtabLookupSymToAddr(metarget,
msrt->linkptr,
sym,
&s);
if (!haveSymval) {
if (sym->shndx == SHN_UNDEF) {
haveSymval = !elfu_mDynLookupPltAddrByName(metarget,
elfu_mSymtabSymToName(msrt->linkptr, sym),
&s);
if (!haveSymval) {
haveSymval = !elfu_mDynLookupReldynAddrByName(metarget,
elfu_mSymtabSymToName(msrt->linkptr, sym),
&s);
}
}
}
if (metarget->elfclass == ELFCLASS32) {
Elf32_Word a32 = rel->addendUsed ? rel->addend : *dest32;
Elf32_Addr p32 = mstarget->shdr.sh_addr + rel->offset;
Elf32_Addr s32 = (Elf32_Addr)s;
switch(metarget->ehdr.e_machine) {
case EM_386:
switch(rel->type) {
case R_386_NONE:
ELFU_DEBUG("Skipping relocation: R_386_NONE\n");
break;
case R_386_32:
if (!haveSymval) {
goto MISSINGSYM;
}
*dest32 = s32 + a32;
break;
case R_386_PC32:
if (!haveSymval) {
goto MISSINGSYM;
}
*dest32 = s32 + a32 - p32;
break;
default:
ELFU_DEBUG("elfu_mRelocate: Skipping unknown relocation type %d\n", rel->type);
}
break;
default:
ELFU_WARN("elfu_mRelocate: Unknown machine type. Aborting.\n");
}
} else if (metarget->elfclass == ELFCLASS64) {
Elf64_Word a64 = rel->addendUsed ? rel->addend : *dest64;
Elf64_Addr p64 = mstarget->shdr.sh_addr + rel->offset;
Elf64_Addr s64 = (Elf64_Addr)s;
switch(metarget->ehdr.e_machine) {
case EM_X86_64:
switch(rel->type) {
case R_X86_64_NONE:
ELFU_DEBUG("Skipping relocation: R_386_NONE\n");
break;
case R_X86_64_64:
if (!haveSymval) {
goto MISSINGSYM;
}
*dest64 = s64 + a64;
break;
case R_X86_64_PC32:
if (!haveSymval) {
goto MISSINGSYM;
}
*dest32 = s64 + a64 - p64;
break;
case R_X86_64_32:
if (!haveSymval) {
goto MISSINGSYM;
}
*dest32 = s64 + a64;
break;
default:
ELFU_DEBUG("elfu_mRelocate: Skipping unknown relocation type %d", rel->type);
}
break;
default:
ELFU_WARN("elfu_mRelocate: Unknown machine type. Aborting.\n");
}
}
}
return 0;
MISSINGSYM:
ELFU_WARN("elfu_mRelocate: Could not resolve symbol %s. Aborting.\n",
elfu_mSymtabSymToName(msrt->linkptr, sym));
return -1;
}
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