x86/cpufeatures, x86/fault: Mark SMAP as disabled when configured out

Add X86_FEATURE_SMAP to the disabled features mask as appropriate
and use cpu_feature_enabled() in the fault code. This lets us get
rid of a redundant IS_ENABLED(CONFIG_X86_SMAP).

Signed-off-by: Andy Lutomirski <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Brian Gerst <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: Denys Vlasenko <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Yu-cheng Yu <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/disabled-features.h

···
 # define DISABLE_MPX	(1<<(X86_FEATURE_MPX & 31))
 #endif
 
+#ifdef CONFIG_X86_SMAP
+# define DISABLE_SMAP	0
+#else
+# define DISABLE_SMAP	(1<<(X86_FEATURE_SMAP & 31))
+#endif
+
 #ifdef CONFIG_X86_INTEL_UMIP
 # define DISABLE_UMIP	0
 #else
···
 #define DISABLED_MASK6	0
 #define DISABLED_MASK7	(DISABLE_PTI)
 #define DISABLED_MASK8	0
-#define DISABLED_MASK9	(DISABLE_MPX)
+#define DISABLED_MASK9	(DISABLE_MPX|DISABLE_SMAP)
 #define DISABLED_MASK10	0
 #define DISABLED_MASK11	0
 #define DISABLED_MASK12	0

arch/x86/mm/fault.c

···
 
 static inline bool smap_violation(int error_code, struct pt_regs *regs)
 {
-	if (!IS_ENABLED(CONFIG_X86_SMAP))
-		return false;
-
-	if (!static_cpu_has(X86_FEATURE_SMAP))
+	if (!cpu_feature_enabled(X86_FEATURE_SMAP))
 		return false;
 
 	if (error_code & X86_PF_USER)