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
