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cbfstool: add relocation parsing to ELF parser 

Optionally parse the relocation entries found within an ELF
file.

Change-Id: I343647f104901eb8a6a997ddf44aa5d36c31b44b
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5374
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
This commit is contained in:
Aaron Durbin 2014-03-05 13:57:30 -06:00 committed by Aaron Durbin
parent d0f6165923
commit ccb5ad8d3c
2 changed files with 97 additions and 0 deletions
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87
util/cbfstool/elfheaders.c
View File

@ -322,6 +322,79 @@ shdr_read(const struct buffer *in, struct parsed_elf *pelf,
return 0;
}
static int
reloc_read(const struct buffer *in, struct parsed_elf *pelf,
struct xdr *xdr, int bit64)
{
struct buffer b;
Elf64_Word i;
Elf64_Ehdr *ehdr;
ehdr = &pelf->ehdr;
pelf->relocs = calloc(ehdr->e_shnum, sizeof(Elf64_Rela *));
/* Allocate array for each section that contains relocation entries. */
for (i = 0; i < ehdr->e_shnum; i++) {
Elf64_Shdr *shdr;
Elf64_Rela *rela;
Elf64_Xword j;
Elf64_Xword nrelocs;
int is_rela;
shdr = &pelf->shdr[i];
/* Only process REL and RELA sections. */
if (shdr->sh_type != SHT_REL && shdr->sh_type != SHT_RELA)
continue;
DEBUG("Checking relocation section %u\n", i);
/* Ensure the section that relocations apply is a valid. */
if (shdr->sh_info >= ehdr->e_shnum ||
shdr->sh_info == SHN_UNDEF) {
ERROR("Relocations apply to an invalid section: %u\n",
shdr[i].sh_info);
return -1;
}
is_rela = shdr->sh_type == SHT_RELA;
/* Determine the number relocations in this section. */
nrelocs = shdr->sh_size / shdr->sh_entsize;
pelf->relocs[i] = calloc(nrelocs, sizeof(Elf64_Rela));
buffer_splice(&b, in, shdr->sh_offset, shdr->sh_size);
if (check_size(in, shdr->sh_offset, buffer_size(&b),
"relocation section")) {
ERROR("Relocation section %u failed.\n", i);
return -1;
}
rela = pelf->relocs[i];
for (j = 0; j < nrelocs; j++) {
if (bit64) {
rela->r_offset = xdr->get64(&b);
rela->r_info = xdr->get64(&b);
if (is_rela)
rela->r_addend = xdr->get64(&b);
} else {
uint32_t r_info;
rela->r_offset = xdr->get32(&b);
r_info = xdr->get32(&b);
rela->r_info = ELF64_R_INFO(ELF32_R_SYM(r_info),
ELF32_R_TYPE(r_info));
if (is_rela)
rela->r_addend = xdr->get32(&b);
}
rela++;
}
}
return 0;
}
int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags)
{
struct xdr *xdr = &xdr_le;
@ -351,12 +424,19 @@ int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags)
elf_ehdr(&input, ehdr, xdr, bit64);
/* Relocation processing requires section header parsing. */
if (flags & ELF_PARSE_RELOC)
flags |= ELF_PARSE_SHDR;
if ((flags & ELF_PARSE_PHDR) && phdr_read(pinput, pelf, xdr, bit64))
goto fail;
if ((flags & ELF_PARSE_SHDR) && shdr_read(pinput, pelf, xdr, bit64))
goto fail;
if ((flags & ELF_PARSE_RELOC) && reloc_read(pinput, pelf, xdr, bit64))
goto fail;
return 0;
fail:
@ -368,6 +448,13 @@ void parsed_elf_destroy(struct parsed_elf *pelf)
{
free(pelf->phdr);
free(pelf->shdr);
if (pelf->relocs != NULL) {
Elf64_Half i;
for (i = 0; i < pelf->ehdr.e_shnum; i++)
free(pelf->relocs[i]);
}
free(pelf->relocs);
}
/* Get the headers from the buffer.

10
util/cbfstool/elfparsing.h
View File

@ -26,10 +26,20 @@ struct parsed_elf {
Elf64_Ehdr ehdr;
Elf64_Phdr *phdr;
Elf64_Shdr *shdr;
/*
* The relocs array contains pointers to arrays of relocation
* structures. Each index into the relocs array corresponds to its
* corresponding section index. i.e. if a section i is of type SHT_REL
* or SHT_RELA then the corresponding index into the relocs array will
* contain the associated relocations. Otherwise thee entry will be
* NULL.
*/
Elf64_Rela **relocs;
};
#define ELF_PARSE_PHDR (1 << 0)
#define ELF_PARSE_SHDR (1 << 1)
#define ELF_PARSE_RELOC (1 << 2)
#define ELF_PARSE_ALL (-1)