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x86_64 linker.

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Based on I8dc3e2cb596f75dc58ae82e4dc58f8c177dd3323 by
Pavel Chupin <pavel.v.chupin@intel.com>.

Change-Id: Icd582d277cbe273477b450f2848343d72c86ec9f
This commit is contained in:
Elliott Hughes
2013-10-04 17:01:33 -07:00
parent 5d06718cd3
commit c00f2cb587
8 changed files with 361 additions and 70 deletions
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236
linker/linker.cpp
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@@ -404,7 +404,7 @@ _Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int *pcount)
soinfo *si;
unsigned addr = (unsigned)pc;
for (si = solist; si != 0; si = si->next){
for (si = solist; si != 0; si = si->next) {
if ((addr >= si->base) && (addr < (si->base + si->size))) {
*pcount = si->ARM_exidx_count;
return (_Unwind_Ptr)si->ARM_exidx;
@@ -441,23 +441,24 @@ static Elf_Sym* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name) {
Elf_Sym* symtab = si->symtab;
const char* strtab = si->strtab;
TRACE_TYPE(LOOKUP, "SEARCH %s in %s@0x%08x %08x %zd",
name, si->name, si->base, hash, hash % si->nbucket);
TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p %x %zd",
name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket);
for (unsigned n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]) {
Elf_Sym* s = symtab + n;
if (strcmp(strtab + s->st_name, name)) continue;
/* only concern ourselves with global and weak symbol definitions */
switch(ELF32_ST_BIND(s->st_info)){
switch (ELF_ST_BIND(s->st_info)) {
case STB_GLOBAL:
case STB_WEAK:
if (s->st_shndx == SHN_UNDEF) {
continue;
}
TRACE_TYPE(LOOKUP, "FOUND %s in %s (%08x) %d",
name, si->name, s->st_value, s->st_size);
TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
name, si->name, reinterpret_cast<void*>(s->st_value),
static_cast<size_t>(s->st_size));
return s;
}
}
@@ -568,10 +569,11 @@ static Elf_Sym* soinfo_do_lookup(soinfo* si, const char* name, soinfo** lsi, soi
done:
if (s != NULL) {
TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = 0x%08x, "
"found in %s, base = 0x%08x, load bias = 0x%08x",
si->name, name, s->st_value,
(*lsi)->name, (*lsi)->base, (*lsi)->load_bias);
TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = %p, "
"found in %s, base = %p, load bias = %p",
si->name, name, reinterpret_cast<void*>(s->st_value),
(*lsi)->name, reinterpret_cast<void*>((*lsi)->base),
reinterpret_cast<void*>((*lsi)->load_bias));
return s;
}
@@ -613,8 +615,8 @@ Elf_Sym* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start) {
}
if (s != NULL) {
TRACE_TYPE(LOOKUP, "%s s->st_value = 0x%08x, found->base = 0x%08x",
name, s->st_value, (*found)->base);
TRACE_TYPE(LOOKUP, "%s s->st_value = %p, found->base = %p",
name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base));
}
return s;
@@ -767,8 +769,8 @@ static soinfo* find_library_internal(const char* name) {
// At this point we know that whatever is loaded @ base is a valid ELF
// shared library whose segments are properly mapped in.
TRACE("[ init_library base=0x%08x sz=0x%08x name='%s' ]",
si->base, si->size, si->name);
TRACE("[ init_library base=%p sz=0x%08x name='%s' ]",
reinterpret_cast<void*>(si->base), si->size, si->name);
if (!soinfo_link_image(si)) {
munmap(reinterpret_cast<void*>(si->base), si->size);
@@ -838,10 +840,124 @@ int do_dlclose(soinfo* si) {
return result;
}
/* TODO: don't use unsigned for addrs below. It works, but is not
* ideal. They should probably be either uint32_t, Elf_Addr, or unsigned
* long.
*/
#if defined(ANDROID_X86_64_LINKER)
static int soinfo_relocate_a(soinfo* si, Elf_Rela* rela, unsigned count, soinfo* needed[]) {
Elf_Sym* symtab = si->symtab;
const char* strtab = si->strtab;
Elf_Sym* s;
Elf_Rela* start = rela;
soinfo* lsi;
for (size_t idx = 0; idx < count; ++idx, ++rela) {
unsigned type = ELF_R_TYPE(rela->r_info);
unsigned sym = ELF_R_SYM(rela->r_info);
Elf_Addr reloc = static_cast<Elf_Addr>(rela->r_offset + si->load_bias);
Elf_Addr sym_addr = 0;
char* sym_name = NULL;
DEBUG("Processing '%s' relocation at index %zd", si->name, idx);
if (type == 0) { // R_*_NONE
continue;
}
if (sym != 0) {
sym_name = (char *)(strtab + symtab[sym].st_name);
s = soinfo_do_lookup(si, sym_name, &lsi, needed);
if (s == NULL) {
// We only allow an undefined symbol if this is a weak reference...
s = &symtab[sym];
if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name);
return -1;
}
/* IHI0044C AAELF 4.5.1.1:
Libraries are not searched to resolve weak references.
It is not an error for a weak reference to remain unsatisfied.
During linking, the value of an undefined weak reference is:
- Zero if the relocation type is absolute
- The address of the place if the relocation is pc-relative
- The address of nominal base address if the relocation
type is base-relative.
*/
switch (type) {
case R_X86_64_JUMP_SLOT:
case R_X86_64_GLOB_DAT:
case R_X86_64_32:
case R_X86_64_RELATIVE:
// No need to do anything.
break;
case R_X86_64_PC32:
sym_addr = reloc;
break;
default:
DL_ERR("unknown weak reloc type %d @ %p (%d)", type, rela, (int) (rela - start));
return -1;
}
} else {
// We got a definition.
sym_addr = static_cast<Elf_Addr>(s->st_value + lsi->load_bias);
}
count_relocation(kRelocSymbol);
} else {
s = NULL;
}
switch (type) {
case R_X86_64_JUMP_SLOT:
count_relocation(kRelocAbsolute);
MARK(rela->r_offset);
TRACE_TYPE(RELO, "RELO JMP_SLOT %08zx <- %08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr + rela->r_addend), sym_name);
*reinterpret_cast<Elf_Addr*>(reloc) = sym_addr + rela->r_addend;
break;
case R_X86_64_GLOB_DAT:
count_relocation(kRelocAbsolute);
MARK(rela->r_offset);
TRACE_TYPE(RELO, "RELO GLOB_DAT %08zx <- %08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr + rela->r_addend), sym_name);
*reinterpret_cast<Elf_Addr*>(reloc) = sym_addr + rela->r_addend;
break;
case R_X86_64_RELATIVE:
count_relocation(kRelocRelative);
MARK(rela->r_offset);
if (sym) {
DL_ERR("odd RELATIVE form...");
return -1;
}
TRACE_TYPE(RELO, "RELO RELATIVE %08zx <- +%08zx", static_cast<size_t>(reloc),
static_cast<size_t>(si->base));
*reinterpret_cast<Elf_Addr*>(reloc) = si->base + rela->r_addend;
break;
case R_X86_64_32:
count_relocation(kRelocRelative);
MARK(rela->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_32 %08zx <- +%08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr), sym_name);
*reinterpret_cast<Elf_Addr*>(reloc) = sym_addr + rela->r_addend;
break;
case R_X86_64_PC32:
count_relocation(kRelocRelative);
MARK(rela->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_PC32 %08zx <- +%08zx (%08zx - %08zx) %s",
static_cast<size_t>(reloc), static_cast<size_t>(sym_addr - reloc),
static_cast<size_t>(sym_addr), static_cast<size_t>(reloc), sym_name);
*reinterpret_cast<Elf_Addr*>(reloc) = sym_addr + rela->r_addend - reloc;
break;
default:
DL_ERR("unknown reloc type %d @ %p (%d)", type, rela, (int) (rela - start));
return -1;
}
}
return 0;
}
#else
static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
soinfo* needed[])
{
@@ -852,8 +968,9 @@ static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
soinfo* lsi;
for (size_t idx = 0; idx < count; ++idx, ++rel) {
unsigned type = ELF32_R_TYPE(rel->r_info);
unsigned sym = ELF32_R_SYM(rel->r_info);
unsigned type = ELF_R_TYPE(rel->r_info);
// TODO: don't use unsigned for 'sym'. Use uint32_t or Elf_Addr instead.
unsigned sym = ELF_R_SYM(rel->r_info);
Elf_Addr reloc = static_cast<Elf_Addr>(rel->r_offset + si->load_bias);
Elf_Addr sym_addr = 0;
char* sym_name = NULL;
@@ -869,7 +986,7 @@ static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
/* We only allow an undefined symbol if this is a weak
reference.. */
s = &symtab[sym];
if (ELF32_ST_BIND(s->st_info) != STB_WEAK) {
if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name);
return -1;
}
@@ -897,7 +1014,7 @@ static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
case R_386_JMP_SLOT:
case R_386_GLOB_DAT:
case R_386_32:
case R_386_RELATIVE: /* Dont' care. */
case R_386_RELATIVE: /* Don't care. */
#endif /* ANDROID_*_LINKER */
/* sym_addr was initialized to be zero above or relocation
code below does not care about value of sym_addr.
@@ -940,7 +1057,7 @@ static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
/* TODO: This is ugly. Split up the relocations by arch into
* different files.
*/
switch(type){
switch (type) {
#if defined(ANDROID_ARM_LINKER)
case R_ARM_JUMP_SLOT:
count_relocation(kRelocAbsolute);
@@ -1005,7 +1122,8 @@ static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
DL_ERR("odd RELATIVE form...");
return -1;
}
TRACE_TYPE(RELO, "RELO RELATIVE %08x <- +%08x", reloc, si->base);
TRACE_TYPE(RELO, "RELO RELATIVE %p <- +%p",
reinterpret_cast<void*>(reloc), reinterpret_cast<void*>(si->base));
*reinterpret_cast<Elf_Addr*>(reloc) += si->base;
break;
@@ -1080,6 +1198,7 @@ static int soinfo_relocate(soinfo* si, Elf_Rel* rel, unsigned count,
}
return 0;
}
#endif
#ifdef ANDROID_MIPS_LINKER
static bool mips_relocate_got(soinfo* si, soinfo* needed[]) {
@@ -1129,7 +1248,7 @@ static bool mips_relocate_got(soinfo* si, soinfo* needed[]) {
/* We only allow an undefined symbol if this is a weak
reference.. */
s = &symtab[g];
if (ELF32_ST_BIND(s->st_info) != STB_WEAK) {
if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
DL_ERR("cannot locate \"%s\"...", sym_name);
return false;
}
@@ -1307,7 +1426,7 @@ static bool soinfo_link_image(soinfo* si) {
/* We can't debug anything until the linker is relocated */
if (!relocating_linker) {
INFO("[ linking %s ]", si->name);
DEBUG("si->base = 0x%08x si->flags = 0x%08x", si->base, si->flags);
DEBUG("si->base = %p si->flags = 0x%08x", reinterpret_cast<void*>(si->base), si->flags);
}
/* Extract dynamic section */
@@ -1334,8 +1453,9 @@ static bool soinfo_link_image(soinfo* si) {
// Extract useful information from dynamic section.
uint32_t needed_count = 0;
for (Elf_Dyn* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
DEBUG("d = %p, d[0](tag) = 0x%08x d[1](val) = 0x%08x", d, d->d_tag, d->d_un.d_val);
switch(d->d_tag){
DEBUG("d = %p, d[0](tag) = %p d[1](val) = %p",
d, reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val));
switch (d->d_tag) {
case DT_HASH:
si->nbucket = ((unsigned *) (base + d->d_un.d_ptr))[0];
si->nchain = ((unsigned *) (base + d->d_un.d_ptr))[1];
@@ -1348,28 +1468,34 @@ static bool soinfo_link_image(soinfo* si) {
case DT_SYMTAB:
si->symtab = (Elf_Sym *) (base + d->d_un.d_ptr);
break;
#if !defined(ANDROID_X86_64_LINKER)
case DT_PLTREL:
if (d->d_un.d_val != DT_REL) {
DL_ERR("unsupported DT_RELA in \"%s\"", si->name);
return false;
}
break;
#endif
case DT_JMPREL:
#if defined(ANDROID_X86_64_LINKER)
si->plt_rela = (Elf_Rela*) (base + d->d_un.d_ptr);
#else
si->plt_rel = (Elf_Rel*) (base + d->d_un.d_ptr);
#endif
break;
case DT_PLTRELSZ:
#if defined(ANDROID_X86_64_LINKER)
si->plt_rela_count = d->d_un.d_val / sizeof(Elf_Rela);
#else
si->plt_rel_count = d->d_un.d_val / sizeof(Elf_Rel);
break;
case DT_REL:
si->rel = (Elf_Rel*) (base + d->d_un.d_ptr);
break;
case DT_RELSZ:
si->rel_count = d->d_un.d_val / sizeof(Elf_Rel);
#endif
break;
case DT_PLTGOT:
#if !defined(ANDROID_X86_64_LINKER)
/* Save this in case we decide to do lazy binding. We don't yet. */
si->plt_got = (unsigned *)(base + d->d_un.d_ptr);
break;
#endif
case DT_DEBUG:
// Set the DT_DEBUG entry to the address of _r_debug for GDB
// if the dynamic table is writable
@@ -1377,9 +1503,30 @@ static bool soinfo_link_image(soinfo* si) {
d->d_un.d_val = reinterpret_cast<uintptr_t>(&_r_debug);
}
break;
#if defined(ANDROID_X86_64_LINKER)
case DT_RELA:
si->rela = (Elf_Rela*) (base + d->d_un.d_ptr);
break;
case DT_RELASZ:
si->rela_count = d->d_un.d_val / sizeof(Elf_Rela);
break;
case DT_REL:
DL_ERR("unsupported DT_REL in \"%s\"", si->name);
return false;
case DT_RELSZ:
DL_ERR("unsupported DT_RELSZ in \"%s\"", si->name);
return false;
#else
case DT_REL:
si->rel = (Elf_Rel*) (base + d->d_un.d_ptr);
break;
case DT_RELSZ:
si->rel_count = d->d_un.d_val / sizeof(Elf_Rel);
break;
case DT_RELA:
DL_ERR("unsupported DT_RELA in \"%s\"", si->name);
return false;
#endif
case DT_INIT:
si->init_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr);
DEBUG("%s constructors (DT_INIT) found at %p", si->name, si->init_func);
@@ -1466,8 +1613,8 @@ static bool soinfo_link_image(soinfo* si) {
}
}
DEBUG("si->base = 0x%08x, si->strtab = %p, si->symtab = %p",
si->base, si->strtab, si->symtab);
DEBUG("si->base = %p, si->strtab = %p, si->symtab = %p",
reinterpret_cast<void*>(si->base), si->strtab, si->symtab);
// Sanity checks.
if (relocating_linker && needed_count != 0) {
@@ -1537,6 +1684,20 @@ static bool soinfo_link_image(soinfo* si) {
}
}
#if defined(ANDROID_X86_64_LINKER)
if (si->plt_rela != NULL) {
DEBUG("[ relocating %s plt ]\n", si->name );
if (soinfo_relocate_a(si, si->plt_rela, si->plt_rela_count, needed)) {
return false;
}
}
if (si->rela != NULL) {
DEBUG("[ relocating %s ]\n", si->name );
if (soinfo_relocate_a(si, si->rela, si->rela_count, needed)) {
return false;
}
}
#else
if (si->plt_rel != NULL) {
DEBUG("[ relocating %s plt ]", si->name );
if (soinfo_relocate(si, si->plt_rel, si->plt_rel_count, needed)) {
@@ -1549,6 +1710,7 @@ static bool soinfo_link_image(soinfo* si) {
return false;
}
}
#endif
#ifdef ANDROID_MIPS_LINKER
if (!mips_relocate_got(si, needed)) {
@@ -1781,7 +1943,7 @@ static Elf_Addr __linker_init_post_relocation(KernelArgumentBlock& args, Elf_Add
fflush(stdout);
#endif
TRACE("[ Ready to execute '%s' @ 0x%08x ]", si->name, si->entry);
TRACE("[ Ready to execute '%s' @ %p ]", si->name, reinterpret_cast<void*>(si->entry));
return si->entry;
}