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qsimd: don't enforce shstk (CET) feature on launch

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Clang with -march=tigerlake or -march=sapphirerapids pre-defines
__SHSTK__, which QtCore require the feature, even if the OS does not
have support for it. That's of no consequence because the compiler does
not generate shadow stack operations on its own.

Pick-to: 6.2 6.3 6.4
Change-Id: Id0fb9ab0089845ee8843fffd16fa1ad910f008b8
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
This commit is contained in:
Thiago Macieira 2022-06-19 12:02:12 -07:00
parent da0d7f61c8
commit d531c4b65d
1 changed files with 6 additions and 0 deletions
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6
src/corelib/global/qsimd.cpp
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@ -564,6 +564,12 @@ uint64_t QT_MANGLE_NAMESPACE(qDetectCpuFeatures)()
// Yocto hard-codes CRC32+AES on. Since they are unlikely to be used // Yocto hard-codes CRC32+AES on. Since they are unlikely to be used
// automatically by compilers, we can just add runtime check. // automatically by compilers, we can just add runtime check.
minFeatureTest &= ~(CpuFeatureAES|CpuFeatureCRC32); minFeatureTest &= ~(CpuFeatureAES|CpuFeatureCRC32);
#endif
#if defined(Q_PROCESSOR_X86_64) && defined(cpu_feature_shstk)
// Controlflow Enforcement Technology (CET) is an OS-assisted
// hardware-feature, meaning the CPUID bit may be disabled if the OS
// doesn't support it, but that's ok.
minFeatureTest &= ~CpuFeatureSHSTK;
#endif #endif
QCpuFeatureType f = detectProcessorFeatures(); QCpuFeatureType f = detectProcessorFeatures();