On 10/12/2020 12:58 PM, Cyrill Gorcunov wrote:
On Mon, Oct 12, 2020 at 08:38:27AM -0700, Yu-cheng Yu wrote: .../* * x86-64 Task Priority Register, CR8 diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 038e19c0019e..705fd9b94e31 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -38,6 +38,9 @@ static const char *xfeature_names[] = "Processor Trace (unused)" , "Protection Keys User registers", "unknown xstate feature" , + "Control-flow User registers" , + "Control-flow Kernel registers" , + "unknown xstate feature" , };static short xsave_cpuid_features[] __initdata = {@@ -51,6 +54,9 @@ static short xsave_cpuid_features[] __initdata = { X86_FEATURE_AVX512F, X86_FEATURE_INTEL_PT, X86_FEATURE_PKU, + -1, /* Unused */ + X86_FEATURE_SHSTK, /* XFEATURE_CET_USER */ + X86_FEATURE_SHSTK, /* XFEATURE_CET_KERNEL */ };Why do you need "-1" here in the array? The only 1:1 mapping is between the names itselves and values, not indices of arrays so i don't understand why we need this unused value. Sorry if it is a dumb questions and been discussed already.
The indices are used indirectly in fpu__init_system_xstate() to set bits in xfeatures_mask_all, i.e.
xfeatures_mask_all &= ~BIT_ULL(i). So they need to match the xstate feature bits. Yu-cheng
