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Subject[PATCH v26 03/30] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET)
Date
Add CPU feature flags for Control-flow Enforcement Technology (CET).

CPUID.(EAX=7,ECX=0):ECX[bit 7] Shadow stack
CPUID.(EAX=7,ECX=0):EDX[bit 20] Indirect Branch Tracking

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
---
v25:
- Make X86_FEATURE_IBT depend on X86_FEATURE_SHSTK.

v24:
- Update for splitting CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK and CONFIG_X86_IBT.
- Move DISABLE_IBT definition to the IBT series.

arch/x86/include/asm/cpufeatures.h | 2 ++
arch/x86/include/asm/disabled-features.h | 8 +++++++-
arch/x86/kernel/cpu/cpuid-deps.c | 2 ++
3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index cc96e26d69f7..bf861fc89fef 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -345,6 +345,7 @@
#define X86_FEATURE_OSPKE (16*32+ 4) /* OS Protection Keys Enable */
#define X86_FEATURE_WAITPKG (16*32+ 5) /* UMONITOR/UMWAIT/TPAUSE Instructions */
#define X86_FEATURE_AVX512_VBMI2 (16*32+ 6) /* Additional AVX512 Vector Bit Manipulation Instructions */
+#define X86_FEATURE_SHSTK (16*32+ 7) /* Shadow Stack */
#define X86_FEATURE_GFNI (16*32+ 8) /* Galois Field New Instructions */
#define X86_FEATURE_VAES (16*32+ 9) /* Vector AES */
#define X86_FEATURE_VPCLMULQDQ (16*32+10) /* Carry-Less Multiplication Double Quadword */
@@ -377,6 +378,7 @@
#define X86_FEATURE_TSXLDTRK (18*32+16) /* TSX Suspend Load Address Tracking */
#define X86_FEATURE_PCONFIG (18*32+18) /* Intel PCONFIG */
#define X86_FEATURE_ARCH_LBR (18*32+19) /* Intel ARCH LBR */
+#define X86_FEATURE_IBT (18*32+20) /* Indirect Branch Tracking */
#define X86_FEATURE_AVX512_FP16 (18*32+23) /* AVX512 FP16 */
#define X86_FEATURE_SPEC_CTRL (18*32+26) /* "" Speculation Control (IBRS + IBPB) */
#define X86_FEATURE_INTEL_STIBP (18*32+27) /* "" Single Thread Indirect Branch Predictors */
diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index b7dd944dc867..e5c6ed9373e8 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -68,6 +68,12 @@
# define DISABLE_SGX (1 << (X86_FEATURE_SGX & 31))
#endif

+#ifdef CONFIG_X86_SHADOW_STACK
+#define DISABLE_SHSTK 0
+#else
+#define DISABLE_SHSTK (1 << (X86_FEATURE_SHSTK & 31))
+#endif
+
/*
* Make sure to add features to the correct mask
*/
@@ -88,7 +94,7 @@
#define DISABLED_MASK14 0
#define DISABLED_MASK15 0
#define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP| \
- DISABLE_ENQCMD)
+ DISABLE_ENQCMD|DISABLE_SHSTK)
#define DISABLED_MASK17 0
#define DISABLED_MASK18 0
#define DISABLED_MASK19 0
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 42af31b64c2c..c88b7e0ebf6d 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -72,6 +72,8 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_AVX512_FP16, X86_FEATURE_AVX512BW },
{ X86_FEATURE_ENQCMD, X86_FEATURE_XSAVES },
{ X86_FEATURE_PER_THREAD_MBA, X86_FEATURE_MBA },
+ { X86_FEATURE_SHSTK, X86_FEATURE_XSAVES },
+ { X86_FEATURE_IBT, X86_FEATURE_SHSTK },
{}
};

--
2.21.0
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