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[scudo] Small cleanup of memory tagging code. (#166860)

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Make the systemSupportsMemoryTagging() function return even on system
that don't support memory tagging. This avoids the need to always check
if memory tagging is supported before calling th function.

Make systemSupportsMemoryTagging() cache the getauxval return value
instead of calling the function every time.

Updated the code that calls systemSupportsMemoryTagging().
This commit is contained in:
Christopher Ferris 2025-11-10 14:17:23 -08:00 committed by GitHub
parent a1934ee500
commit 046ae85536
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GPG Key ID: B5690EEEBB952194
5 changed files with 6 additions and 12 deletions
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3
compiler-rt/lib/scudo/standalone/combined.h
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@ -171,8 +171,7 @@ public:
Primary.Options.set(OptionBit::DeallocTypeMismatch);
if (getFlags()->delete_size_mismatch)
Primary.Options.set(OptionBit::DeleteSizeMismatch);
if (allocatorSupportsMemoryTagging<AllocatorConfig>() &&
systemSupportsMemoryTagging())
if (systemSupportsMemoryTagging())
Primary.Options.set(OptionBit::UseMemoryTagging);
QuarantineMaxChunkSize =

7
compiler-rt/lib/scudo/standalone/memtag.h
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@ -66,7 +66,8 @@ inline bool systemSupportsMemoryTagging() {
#ifndef HWCAP2_MTE
#define HWCAP2_MTE (1 << 18)
#endif
return getauxval(AT_HWCAP2) & HWCAP2_MTE;
static bool SupportsMemoryTagging = getauxval(AT_HWCAP2) & HWCAP2_MTE;
return SupportsMemoryTagging;
}
inline bool systemDetectsMemoryTagFaultsTestOnly() {
@ -261,9 +262,7 @@ inline uptr loadTag(uptr Ptr) {
#else
inline NORETURN bool systemSupportsMemoryTagging() {
UNREACHABLE("memory tagging not supported");
}
inline bool systemSupportsMemoryTagging() { return false; }
inline NORETURN bool systemDetectsMemoryTagFaultsTestOnly() {
UNREACHABLE("memory tagging not supported");

1
compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp
View File

@ -28,7 +28,6 @@ TEST(MemtagBasicDeathTest, Unsupported) {
EXPECT_DEATH(untagPointer((uptr)0), "not supported");
EXPECT_DEATH(extractTag((uptr)0), "not supported");
EXPECT_DEATH(systemSupportsMemoryTagging(), "not supported");
EXPECT_DEATH(systemDetectsMemoryTagFaultsTestOnly(), "not supported");
EXPECT_DEATH(enableSystemMemoryTaggingTestOnly(), "not supported");

4
compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp
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@ -27,9 +27,7 @@
const scudo::uptr PageSize = scudo::getPageSizeCached();
template <typename Config> static scudo::Options getOptionsForConfig() {
if (!Config::getMaySupportMemoryTagging() ||
!scudo::archSupportsMemoryTagging() ||
!scudo::systemSupportsMemoryTagging())
if (!scudo::systemSupportsMemoryTagging())
return {};
scudo::AtomicOptions AO;
AO.set(scudo::OptionBit::UseMemoryTagging);

3
compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp
View File

@ -187,8 +187,7 @@ TEST_F(ScudoWrappersCppTest, ThreadedNew) {
// TODO: Investigate why libc sometimes crashes with tag missmatch in
// __pthread_clockjoin_ex.
std::unique_ptr<scudo::ScopedDisableMemoryTagChecks> NoTags;
if (!SCUDO_ANDROID && scudo::archSupportsMemoryTagging() &&
scudo::systemSupportsMemoryTagging())
if (!SCUDO_ANDROID && scudo::systemSupportsMemoryTagging())
NoTags = std::make_unique<scudo::ScopedDisableMemoryTagChecks>();
Ready = false;