Re: [PATCH 03/35] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET)
From: Dave Hansen <hidden>
Date: 2022-02-07 22:45:34
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On 1/30/22 13:18, Rick Edgecombe wrote:
quoted hunk ↗ jump to hunk
--- a/arch/x86/kernel/cpu/cpuid-deps.c +++ b/arch/x86/kernel/cpu/cpuid-deps.c@@ -78,6 +78,7 @@ static const struct cpuid_dep cpuid_deps[] = { { X86_FEATURE_XFD, X86_FEATURE_XSAVES }, { X86_FEATURE_XFD, X86_FEATURE_XGETBV1 }, { X86_FEATURE_AMX_TILE, X86_FEATURE_XFD }, + { X86_FEATURE_SHSTK, X86_FEATURE_XSAVES }, {} };
Please add a chunk to the changelog that explains the dependency. This would suffice: To protect shadow stack state from malicious modification, the registers are only accessible in supervisor mode. This implementation context-switches the registers with XSAVES. Make X86_FEATURE_SHSTK depend on XSAVES. The XSAVES dependency is touched on in the documentation, but it's a bit buried in there.