On Thu, 2018-11-08 at 19:40 +0100, Borislav Petkov wrote:

On Thu, Oct 11, 2018 at 08:15:00AM -0700, Yu-cheng Yu wrote:

quoted

[...] 
+/*
+ * State component 11 is Control flow Enforcement user states

Why the Camel-cased naming?

"Control" then "flow" then capitalized again "Enforcement".

Fix all occurrences pls, especially the user-visible strings.

I will change it to "Control-flow Enforcement" everywhere.

quoted

+ */
+struct cet_user_state {
+	u64 u_cet;	/* user control flow settings */
+	u64 user_ssp;	/* user shadow stack pointer */

Prefix both with "usr_" instead.

Ok.

[...]

Just write "privilege level" everywhere - not "ring".

Btw, do you see how the type and the name of all those other fields in
that file are tabulated? Except yours...

I will fix it.

[...] 

quoted

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 605ec6decf3e..ad36ea28bfd1 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c

@@ -35,6 +35,9 @@ 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"	,

So there are two "unknown xstate feature" array elems now...

quoted

 static short xsave_cpuid_features[] __initdata = {

@@ -48,6 +51,9 @@ static short xsave_cpuid_features[] __initdata = {
 	X86_FEATURE_AVX512F,
 	X86_FEATURE_INTEL_PT,
 	X86_FEATURE_PKU,
+	0,		   /* Unused */

What's that for?

In fpu_init_system_xstate(), we test and clear features that are not enabled.
There we depend on the order of these elements.  This is the tenth "unknown
xstate feature".

Yu-cheng