Re: [RFC PATCH v9 02/27] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET)

Kees Cook
2020-02-25T20:02:50Z

On Wed, Feb 05, 2020 at 10:19:10AM -0800, Yu-cheng Yu wrote:
> 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>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> Reviewed-by: Borislav Petkov <bp@suse.de>
> ---
> arch/x86/include/asm/cpufeatures.h | 2 ++
> arch/x86/kernel/cpu/cpuid-deps.c | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index e9b62498fe75..a2c6b1b5c026 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -336,6 +336,7 @@
> #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 */
> @@ -361,6 +362,7 @@
> #define X86_FEATURE_MD_CLEAR (18*32+10) /* VERW clears CPU buffers */
> #define X86_FEATURE_TSX_FORCE_ABORT (18*32+13) /* "" TSX_FORCE_ABORT */
> #define X86_FEATURE_PCONFIG (18*32+18) /* Intel PCONFIG */
> +#define X86_FEATURE_IBT (18*32+20) /* Indirect Branch Tracking */
> #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 */
> #define X86_FEATURE_FLUSH_L1D (18*32+28) /* Flush L1D cache */
> diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
> index 3cbe24ca80ab..fec83cc74b9e 100644
> --- a/arch/x86/kernel/cpu/cpuid-deps.c
> +++ b/arch/x86/kernel/cpu/cpuid-deps.c
> @@ -69,6 +69,8 @@ static const struct cpuid_dep cpuid_deps[] = {
> { X86_FEATURE_CQM_MBM_TOTAL, X86_FEATURE_CQM_LLC },
> { X86_FEATURE_CQM_MBM_LOCAL, X86_FEATURE_CQM_LLC },
> { X86_FEATURE_AVX512_BF16, X86_FEATURE_AVX512VL },
> + { X86_FEATURE_SHSTK, X86_FEATURE_XSAVES },
> + { X86_FEATURE_IBT, X86_FEATURE_XSAVES },
> {}
> };
>
> --
> 2.21.0
>

--
Kees Cook