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Merge "Microoptimize vdso lookup." into main am: 18a6fa2d2f

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Original change: https://android-review.googlesource.com/c/platform/bionic/+/2871814

Change-Id: I661c136e478f485f5ce8a1564964352d48605dac
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
This commit is contained in:
Elliott Hughes 2023-12-13 16:13:08 +00:00 committed by Automerger Merge Worker
commit ad27b8618e
1 changed files with 8 additions and 4 deletions
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12
libc/bionic/vdso.cpp
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@ -131,6 +131,7 @@ void __libc_init_vdso(libc_globals* globals) {
for (size_t i = 0; i < vdso_ehdr->e_shnum; ++i) {
if (vdso_shdr[i].sh_type == SHT_DYNSYM) {
symbol_count = vdso_shdr[i].sh_size / sizeof(ElfW(Sym));
break;
}
}
if (symbol_count == 0) {
@ -147,6 +148,7 @@ void __libc_init_vdso(libc_globals* globals) {
} else if (vdso_phdr[i].p_type == PT_LOAD) {
vdso_addr = vdso_ehdr_addr + vdso_phdr[i].p_offset - vdso_phdr[i].p_vaddr;
}
if (vdso_addr && vdso_dyn) break;
}
if (vdso_addr == 0 || vdso_dyn == nullptr) {
return;
@ -161,16 +163,18 @@ void __libc_init_vdso(libc_globals* globals) {
} else if (d->d_tag == DT_SYMTAB) {
symtab = reinterpret_cast<ElfW(Sym)*>(vdso_addr + d->d_un.d_ptr);
}
if (strtab && symtab) break;
}
if (strtab == nullptr || symtab == nullptr) {
return;
}
// Are there any symbols we want?
for (size_t i = 0; i < symbol_count; ++i) {
for (size_t j = 0; j < VDSO_END; ++j) {
if (strcmp(vdso[j].name, strtab + symtab[i].st_name) == 0) {
vdso[j].fn = reinterpret_cast<void*>(vdso_addr + symtab[i].st_value);
for (size_t i = 0; i < VDSO_END; ++i) {
for (size_t j = 0; j < symbol_count; ++j) {
if (strcmp(vdso[i].name, strtab + symtab[j].st_name) == 0) {
vdso[i].fn = reinterpret_cast<void*>(vdso_addr + symtab[j].st_value);
break;
}
}
}