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/*
* ELF relocation code (not used by xen kernel right now).
*
* This 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;
* version 2.1 of the License.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libelf-private.h"
/* ------------------------------------------------------------------------ */
static const char *rel_names_i386[] = {
"R_386_NONE",
"R_386_32",
"R_386_PC32",
"R_386_GOT32",
"R_386_PLT32",
"R_386_COPY",
"R_386_GLOB_DAT",
"R_386_JMP_SLOT",
"R_386_RELATIVE",
"R_386_GOTOFF",
"R_386_GOTPC",
"R_386_32PLT",
"R_386_TLS_TPOFF",
"R_386_TLS_IE",
"R_386_TLS_GOTIE",
"R_386_TLS_LE",
"R_386_TLS_GD",
"R_386_TLS_LDM",
"R_386_16",
"R_386_PC16",
"R_386_8",
"R_386_PC8",
"R_386_TLS_GD_32",
"R_386_TLS_GD_PUSH",
"R_386_TLS_GD_CALL",
"R_386_TLS_GD_POP",
"R_386_TLS_LDM_32",
"R_386_TLS_LDM_PUSH",
"R_386_TLS_LDM_CALL",
"R_386_TLS_LDM_POP",
"R_386_TLS_LDO_32",
"R_386_TLS_IE_32",
"R_386_TLS_LE_32",
"R_386_TLS_DTPMOD32",
"R_386_TLS_DTPOFF32",
"R_386_TLS_TPOFF32",
};
static int elf_reloc_i386(struct elf_binary *elf, int type,
uint64_t addr, uint64_t value)
{
void *ptr = elf_get_ptr(elf, addr);
uint32_t *u32;
switch ( type )
{
case 1 /* R_386_32 */ :
u32 = ptr;
*u32 += elf->reloc_offset;
break;
case 2 /* R_386_PC32 */ :
/* nothing */
break;
default:
return -1;
}
return 0;
}
/* ------------------------------------------------------------------------ */
static const char *rel_names_x86_64[] = {
"R_X86_64_NONE",
"R_X86_64_64",
"R_X86_64_PC32",
"R_X86_64_GOT32",
"R_X86_64_PLT32",
"R_X86_64_COPY",
"R_X86_64_GLOB_DAT",
"R_X86_64_JUMP_SLOT",
"R_X86_64_RELATIVE",
"R_X86_64_GOTPCREL",
"R_X86_64_32",
"R_X86_64_32S",
"R_X86_64_16",
"R_X86_64_PC16",
"R_X86_64_8",
"R_X86_64_PC8",
"R_X86_64_DTPMOD64",
"R_X86_64_DTPOFF64",
"R_X86_64_TPOFF64",
"R_X86_64_TLSGD",
"R_X86_64_TLSLD",
"R_X86_64_DTPOFF32",
"R_X86_64_GOTTPOFF",
"R_X86_64_TPOFF32",
};
static int elf_reloc_x86_64(struct elf_binary *elf, int type,
uint64_t addr, uint64_t value)
{
void *ptr = elf_get_ptr(elf, addr);
uint64_t *u64;
uint32_t *u32;
int32_t *s32;
switch ( type )
{
case 1 /* R_X86_64_64 */ :
u64 = ptr;
value += elf->reloc_offset;
*u64 = value;
break;
case 2 /* R_X86_64_PC32 */ :
u32 = ptr;
*u32 = value - addr;
if ( *u32 != (uint32_t)(value - addr) )
{
elf_err(elf, "R_X86_64_PC32 overflow: 0x%" PRIx32
" != 0x%" PRIx32 "\n",
*u32, (uint32_t) (value - addr));
return -1;
}
break;
case 10 /* R_X86_64_32 */ :
u32 = ptr;
value += elf->reloc_offset;
*u32 = value;
if ( *u32 != value )
{
elf_err(elf, "R_X86_64_32 overflow: 0x%" PRIx32
" != 0x%" PRIx64 "\n",
*u32, value);
return -1;
}
break;
case 11 /* R_X86_64_32S */ :
s32 = ptr;
value += elf->reloc_offset;
*s32 = value;
if ( *s32 != (int64_t) value )
{
elf_err(elf, "R_X86_64_32S overflow: 0x%" PRIx32
" != 0x%" PRIx64 "\n",
*s32, (int64_t) value);
return -1;
}
break;
default:
return -1;
}
return 0;
}
/* ------------------------------------------------------------------------ */
static struct relocs {
const char **names;
int count;
int (*func) (struct elf_binary * elf, int type, uint64_t addr,
uint64_t value);
} relocs[] =
/* *INDENT-OFF* */
{
[EM_386] = {
.names = rel_names_i386,
.count = sizeof(rel_names_i386) / sizeof(rel_names_i386[0]),
.func = elf_reloc_i386,
},
[EM_X86_64] = {
.names = rel_names_x86_64,
.count = sizeof(rel_names_x86_64) / sizeof(rel_names_x86_64[0]),
.func = elf_reloc_x86_64,
}
};
/* *INDENT-ON* */
/* ------------------------------------------------------------------------ */
static const char *rela_name(int machine, int type)
{
if ( machine > sizeof(relocs) / sizeof(relocs[0]) )
return "unknown mach";
if ( !relocs[machine].names )
return "unknown mach";
if ( type > relocs[machine].count )
return "unknown rela";
return relocs[machine].names[type];
}
static int elf_reloc_section(struct elf_binary *elf,
const elf_shdr * rels,
const elf_shdr * sect, const elf_shdr * syms)
{
const void *ptr, *end;
const elf_shdr *shdr;
const elf_rela *rela;
const elf_rel *rel;
const elf_sym *sym;
uint64_t s_type;
uint64_t r_offset;
uint64_t r_info;
uint64_t r_addend;
int r_type, r_sym;
size_t rsize;
uint64_t shndx, sbase, addr, value;
const char *sname;
int machine;
machine = elf_uval(elf, elf->ehdr, e_machine);
if ( (machine >= (sizeof(relocs) / sizeof(relocs[0]))) ||
(relocs[machine].func == NULL) )
{
elf_err(elf, "%s: can't handle machine %d\n",
__FUNCTION__, machine);
return -1;
}
if ( elf_swap(elf) )
{
elf_err(elf, "%s: non-native byte order, relocation not supported\n",
__FUNCTION__);
return -1;
}
s_type = elf_uval(elf, rels, sh_type);
rsize = (SHT_REL == s_type) ? elf_size(elf, rel) : elf_size(elf, rela);
ptr = elf_section_start(elf, rels);
end = elf_section_end(elf, rels);
for ( ; ptr < end; ptr += rsize )
{
switch ( s_type )
{
case SHT_REL:
rel = ptr;
r_offset = elf_uval(elf, rel, r_offset);
r_info = elf_uval(elf, rel, r_info);
r_addend = 0;
break;
case SHT_RELA:
rela = ptr;
r_offset = elf_uval(elf, rela, r_offset);
r_info = elf_uval(elf, rela, r_info);
r_addend = elf_uval(elf, rela, r_addend);
break;
default:
/* can't happen */
return -1;
}
if ( elf_64bit(elf) )
{
r_type = ELF64_R_TYPE(r_info);
r_sym = ELF64_R_SYM(r_info);
}
else
{
r_type = ELF32_R_TYPE(r_info);
r_sym = ELF32_R_SYM(r_info);
}
sym = elf_sym_by_index(elf, r_sym);
shndx = elf_uval(elf, sym, st_shndx);
switch ( shndx )
{
case SHN_UNDEF:
sname = "*UNDEF*";
sbase = 0;
break;
case SHN_COMMON:
elf_err(elf, "%s: invalid section: %" PRId64 "\n",
__FUNCTION__, shndx);
return -1;
case SHN_ABS:
sname = "*ABS*";
sbase = 0;
break;
default:
shdr = elf_shdr_by_index(elf, shndx);
if ( shdr == NULL )
{
elf_err(elf, "%s: invalid section: %" PRId64 "\n",
__FUNCTION__, shndx);
return -1;
}
sname = elf_section_name(elf, shdr);
sbase = elf_uval(elf, shdr, sh_addr);
}
addr = r_offset;
value = elf_uval(elf, sym, st_value);
value += r_addend;
if ( elf->log_callback && (elf->verbose > 1) )
{
uint64_t st_name = elf_uval(elf, sym, st_name);
const char *name = st_name ? elf->sym_strtab + st_name : "*NONE*";
elf_msg(elf,
"%s: type %s [%d], off 0x%" PRIx64 ", add 0x%" PRIx64 ","
" sym %s [0x%" PRIx64 "], sec %s [0x%" PRIx64 "]"
" -> addr 0x%" PRIx64 " value 0x%" PRIx64 "\n",
__FUNCTION__, rela_name(machine, r_type), r_type, r_offset,
r_addend, name, elf_uval(elf, sym, st_value), sname, sbase,
addr, value);
}
if ( relocs[machine].func(elf, r_type, addr, value) == -1 )
{
elf_err(elf, "%s: unknown/unsupported reloc type %s [%d]\n",
__FUNCTION__, rela_name(machine, r_type), r_type);
return -1;
}
}
return 0;
}
int elf_reloc(struct elf_binary *elf)
{
const elf_shdr *rels, *sect, *syms;
uint64_t i, count, type;
count = elf_shdr_count(elf);
for ( i = 0; i < count; i++ )
{
rels = elf_shdr_by_index(elf, i);
type = elf_uval(elf, rels, sh_type);
if ( (type != SHT_REL) && (type != SHT_RELA) )
continue;
sect = elf_shdr_by_index(elf, elf_uval(elf, rels, sh_info));
syms = elf_shdr_by_index(elf, elf_uval(elf, rels, sh_link));
if ( NULL == sect || NULL == syms )
continue;
if ( !(elf_uval(elf, sect, sh_flags) & SHF_ALLOC) )
{
elf_msg(elf, "%s: relocations for %s, skipping\n",
__FUNCTION__, elf_section_name(elf, sect));
continue;
}
elf_msg(elf, "%s: relocations for %s @ 0x%" PRIx64 "\n",
__FUNCTION__, elf_section_name(elf, sect),
elf_uval(elf, sect, sh_addr));
if ( elf_reloc_section(elf, rels, sect, syms) != 0 )
return -1;
}
return 0;
}
/*
* Local variables:
* mode: C
* c-set-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
|
