/**
MIPS ABI Supplement:
DT_PLTGOT This member holds the address of the .got section.
DT_MIPS_SYMTABNO This member holds the number of entries in the
.dynsym section.
DT_MIPS_LOCAL_GOTNO This member holds the number of local global
offset table entries.
DT_MIPS_GOTSYM This member holds the index of the first dyamic
symbol table entry that corresponds to an entry in the gobal offset
table.
*/
int
arch_elf_init(struct ltelf *lte, struct library *lib)
{
Elf_Scn *scn;
GElf_Shdr shdr;
/* FIXME: for CPIC we should really scan both GOT tables
* to pick up relocations to external functions. Right now
* function pointers from the main binary to external functions
* can't be traced in CPIC mode. */
if (mips_elf_is_cpic(lte->ehdr.e_flags)) {
return 0; /* We are already done. */
}
if (elf_get_section_type(lte, SHT_DYNAMIC, &scn, &shdr) < 0
|| scn == NULL) {
fail:
error(0, 0, "Couldn't get SHT_DYNAMIC: %s",
elf_errmsg(-1));
return -1;
}
Elf_Data *data = elf_loaddata(scn, &shdr);
if (data == NULL)
goto fail;
size_t j;
for (j = 0; j < shdr.sh_size / shdr.sh_entsize; ++j) {
GElf_Dyn dyn;
if (gelf_getdyn(data, j, &dyn) == NULL)
goto fail;
if(dyn.d_tag == DT_PLTGOT) {
lte->arch.pltgot_addr = dyn.d_un.d_ptr;
}
if(dyn.d_tag == DT_MIPS_LOCAL_GOTNO){
lte->arch.mips_local_gotno = dyn.d_un.d_val;
}
if(dyn.d_tag == DT_MIPS_GOTSYM){
lte->arch.mips_gotsym = dyn.d_un.d_val;
}
}
/* Tell the generic code how many dynamic trace:able symbols
* we've got. */
lte->relplt_count = lte->dynsym_count - lte->arch.mips_gotsym;
return 0;
}
int
arch_elf_init(struct ltelf *lte, struct library *lib)
{
/* Nothing in this section is strictly critical. It's not
* that much of a deal if we fail to guess right whether the
* ABI is softfp or hardfp. */
unsigned hardfp = 0;
Elf_Scn *scn;
Elf_Data *data;
GElf_Shdr shdr;
if (elf_get_section_type(lte, SHT_ARM_ATTRIBUTES, &scn, &shdr) < 0
|| (scn != NULL && (data = elf_loaddata(scn, &shdr)) == NULL)) {
fprintf(stderr,
"Error when obtaining ARM attribute section: %s\n",
elf_errmsg(-1));
goto done;
} else if (scn != NULL && data != NULL) {
GElf_Xword offset = 0;
uint8_t version;
if (elf_read_next_u8(data, &offset, &version) < 0) {
goto done;
} else if (version != 'A') {
fprintf(stderr, "Unsupported ARM attribute section "
"version %d ('%c').\n", version, version);
goto done;
}
do {
const char signature[] = "aeabi";
/* N.B. LEN is including the length field
* itself. */
uint32_t sec_len;
if (elf_read_u32(data, offset, &sec_len) < 0
|| !elf_can_read_next(data, offset, sec_len)) {
goto done;
}
const GElf_Xword next_offset = offset + sec_len;
offset += 4;
if (sec_len < 4 + sizeof signature
|| strcmp(signature, data->d_buf + offset) != 0)
goto skip;
offset += sizeof signature;
const GElf_Xword offset0 = offset;
uint64_t tag;
uint32_t sub_len;
if (elf_read_next_uleb128(data, &offset, &tag) < 0
|| elf_read_next_u32(data, &offset, &sub_len) < 0
|| !elf_can_read_next(data, offset0, sub_len))
goto done;
if (tag != 1)
/* IHI0045D_ABI_addenda: "section and
* symbol attributes are deprecated
* [...] consumers are permitted to
* ignore them." */
goto skip;
while (offset < offset0 + sub_len) {
if (elf_read_next_uleb128(data,
&offset, &tag) < 0)
goto done;
switch (tag) {
uint64_t v;
case 6: /* Tag_CPU_arch */
case 7: /* Tag_CPU_arch_profile */
case 8: /* Tag_ARM_ISA_use */
case 9: /* Tag_THUMB_ISA_use */
case 10: /* Tag_FP_arch */
case 11: /* Tag_WMMX_arch */
case 12: /* Tag_Advanced_SIMD_arch */
case 13: /* Tag_PCS_config */
case 14: /* Tag_ABI_PCS_R9_use */
case 15: /* Tag_ABI_PCS_RW_data */
case 16: /* Tag_ABI_PCS_RO_data */
case 17: /* Tag_ABI_PCS_GOT_use */
case 18: /* Tag_ABI_PCS_wchar_t */
case 19: /* Tag_ABI_FP_rounding */
case 20: /* Tag_ABI_FP_denormal */
case 21: /* Tag_ABI_FP_exceptions */
case 22: /* Tag_ABI_FP_user_exceptions */
case 23: /* Tag_ABI_FP_number_model */
case 24: /* Tag_ABI_align_needed */
case 25: /* Tag_ABI_align_preserved */
case 26: /* Tag_ABI_enum_size */
case 27: /* Tag_ABI_HardFP_use */
case 28: /* Tag_ABI_VFP_args */
case 29: /* Tag_ABI_WMMX_args */
case 30: /* Tag_ABI_optimization_goals */
case 31: /* Tag_ABI_FP_optimization_goals */
case 32: /* Tag_compatibility */
case 34: /* Tag_CPU_unaligned_access */
case 36: /* Tag_FP_HP_extension */
case 38: /* Tag_ABI_FP_16bit_format */
case 42: /* Tag_MPextension_use */
case 70: /* Tag_MPextension_use as well */
case 44: /* Tag_DIV_use */
case 64: /* Tag_nodefaults */
case 66: /* Tag_T2EE_use */
case 68: /* Tag_Virtualization_use */
uleb128:
if (elf_read_next_uleb128
(data, &offset, &v) < 0)
goto done;
if (tag == 28)
hardfp = get_hardfp(v);
if (tag != 32)
continue;
/* Tag 32 has two arguments,
* fall through. */
case 4: /* Tag_CPU_raw_name */
case 5: /* Tag_CPU_name */
case 65: /* Tag_also_compatible_with */
case 67: /* Tag_conformance */
ntbs:
offset += strlen(data->d_buf
+ offset) + 1;
continue;
}
/* Handle unknown tags in a generic
* manner, if possible. */
if (tag <= 32) {
fprintf(stderr,
"Unknown tag %lld "
"at offset %#llx "
"of ARM attribute section.",
tag, offset);
goto skip;
} else if (tag % 2 == 0) {
goto uleb128;
} else {
goto ntbs;
}
}
skip:
offset = next_offset;
} while (elf_can_read_next(data, offset, 1));
}
done:
lib->arch.hardfp = hardfp;
return 0;
}