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Optimize stack unwinding by reducing AddressIsReadable calls.

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PiperOrigin-RevId: 822738922
Change-Id: Ifd784d16ffb8ae810900b11e41a74ac1f263ed89
This commit is contained in:
Abseil Team
2025-10-22 14:20:50 -07:00
committed by Copybara-Service
parent 6cdb3d1b38
commit f40a1cce40
1 changed files with 8 additions and 3 deletions
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11
absl/debugging/internal/stacktrace_x86-inl.inc
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@@ -245,6 +245,7 @@ static void **NextStackFrame(void **old_fp, const void *uc,
}
#endif
const size_t page_size = static_cast<size_t>(getpagesize());
const uintptr_t old_fp_u = reinterpret_cast<uintptr_t>(old_fp);
const uintptr_t new_fp_u = reinterpret_cast<uintptr_t>(new_fp);
@@ -273,8 +274,7 @@ static void **NextStackFrame(void **old_fp, const void *uc,
// so we assume the large frame is legit if we know the real stack bounds
// and are within the stack.
if (new_fp_u <= old_fp_u || new_fp_u - old_fp_u > kMaxFrameBytes) {
if (stack_high < kUnknownStackEnd &&
static_cast<size_t>(getpagesize()) < stack_low) {
if (stack_high < kUnknownStackEnd && page_size < stack_low) {
// Stack bounds are known.
if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) {
// new_fp_u is not within the known stack.
@@ -311,7 +311,12 @@ static void **NextStackFrame(void **old_fp, const void *uc,
if (new_fp_u >= 0xffffe000) return nullptr;
#endif
#if !defined(_WIN32)
if (!STRICT_UNWINDING) {
const uintptr_t old_fp_page = old_fp_u & ~(page_size - 1);
const uintptr_t new_fp_page = new_fp_u & ~(page_size - 1);
if (old_fp_page == new_fp_page && (new_fp_u & (sizeof(void*) - 1)) == 0) {
// We dereferenced the old_fp above, so it is safe to dereference
// new_fp if it's on the same page as the old_fp and is aligned.
} else if (!STRICT_UNWINDING) {
// Lax sanity checks cause a crash in 32-bit tcmalloc/crash_reason_test
// on AMD-based machines with VDSO-enabled kernels.
// Make an extra sanity check to insure new_fp is readable.