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

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Merged
merged 1 commit into from
Nov 10, 2025
+6 −12
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[scudo] Small cleanup of memory tagging code. #166860

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3 changes: 1 addition & 2 deletions compiler-rt/lib/scudo/standalone/combined.h
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Original file line number Diff line number Diff line change
Expand Up @@ -171,8 +171,7 @@ class Allocator {
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 =
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7 changes: 3 additions & 4 deletions compiler-rt/lib/scudo/standalone/memtag.h
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Expand Up @@ -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;
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@vitalybuka vitalybuka Nov 10, 2025

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Oh,
my thought during review: "nice! static locals are supported now" :)

https://lab.llvm.org/buildbot/#/builders/24/builds/14562

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@vitalybuka vitalybuka Nov 10, 2025

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CC @pcc

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@pcc pcc Nov 11, 2025

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Memory tagging support status is deliberately cached in the UseMemoryTagging bit instead of here to avoid issues with static locals such as those pointed out by the buildbot.

return SupportsMemoryTagging;
}

inline bool systemDetectsMemoryTagFaultsTestOnly() {
Expand Down Expand Up @@ -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");
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1 change: 0 additions & 1 deletion compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp
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Expand Up @@ -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");

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4 changes: 1 addition & 3 deletions compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp
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Expand Up @@ -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);
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3 changes: 1 addition & 2 deletions compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp
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Expand Up @@ -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;
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