[libunwind] Be more careful about enabling GCS #101973
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We need both GCS to be enabled by the compiler (which we do by checking if __ARM_FEATURE_GCS_DEFAULT is defined) and for arm_acle.h to define the GCS intrinsics. Check the latter by checking if _CHKFEAT_GCS is defined.
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@llvm/pr-subscribers-libunwind Author: John Brawn (john-brawn-arm) ChangesWe need both GCS to be enabled by the compiler (which we do by checking if __ARM_FEATURE_GCS_DEFAULT is defined) and for arm_acle.h to define the GCS intrinsics. Check the latter by checking if _CHKFEAT_GCS is defined. Full diff: https://github.com/llvm/llvm-project/pull/101973.diff 1 Files Affected:
diff --git a/libunwind/src/cet_unwind.h b/libunwind/src/cet_unwind.h
index 45c11973cb7fa..47d7616a7322c 100644
--- a/libunwind/src/cet_unwind.h
+++ b/libunwind/src/cet_unwind.h
@@ -39,9 +39,13 @@
// need to guard any use of GCS instructions with __chkfeat though, as GCS may
// not be enabled.
#if defined(_LIBUNWIND_TARGET_AARCH64) && defined(__ARM_FEATURE_GCS_DEFAULT)
-#define _LIBUNWIND_USE_GCS 1
#include <arm_acle.h>
+// We can only use GCS if arm_acle.h defines the GCS intrinsics.
+#ifdef _CHKFEAT_GCS
+#define _LIBUNWIND_USE_GCS 1
+#endif
+
#define _LIBUNWIND_POP_CET_SSP(x) \
do { \
if (__chkfeat(_CHKFEAT_GCS)) { \
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MaskRay
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Aug 5, 2024
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We need both GCS to be enabled by the compiler (which we do by checking if __ARM_FEATURE_GCS_DEFAULT is defined) and for arm_acle.h to define the GCS intrinsics. Check the latter by checking if _CHKFEAT_GCS is defined. (cherry picked from commit c649194)
tru
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Aug 20, 2024
We need both GCS to be enabled by the compiler (which we do by checking if __ARM_FEATURE_GCS_DEFAULT is defined) and for arm_acle.h to define the GCS intrinsics. Check the latter by checking if _CHKFEAT_GCS is defined. (cherry picked from commit c649194)
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We need both GCS to be enabled by the compiler (which we do by checking if __ARM_FEATURE_GCS_DEFAULT is defined) and for arm_acle.h to define the GCS intrinsics. Check the latter by checking if _CHKFEAT_GCS is defined.