x86/cpufeature: Speed up cpu_feature_enabled()

commit f2cc8e0 upstream

When GCC cannot do constant folding for this macro, it falls back to
cpu_has(). But static_cpu_has() is optimal and it works at all times
now. So use it and speedup the fallback case.

Before we had this:

  mov    0x99d674(%rip),%rdx        # ffffffff81b0d9f4 <boot_cpu_data+0x34>
  shr    $0x2e,%rdx
  and    $0x1,%edx
  jne    ffffffff811704e9 <do_munmap+0x3f9>

After alternatives patching, it turns into:

		  jmp    0xffffffff81170390
		  nopl   (%rax)
		  ...
		  callq  ffffffff81056e00 <mpx_notify_unmap>
ffffffff81170390: mov    0x170(%r12),%rdi

Signed-off-by: Borislav Petkov <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Srivatsa S. Bhat <[email protected]>
Reviewed-by: Matt Helsley (VMware) <[email protected]>
Reviewed-by: Alexey Makhalov <[email protected]>
Reviewed-by: Bo Gan <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: suryasaimadhu

arch/x86/include/asm/cpufeature.h

@@ -88,8 +88,7 @@ extern const char * const x86_bug_flags[NBUGINTS*32];
  * is not relevant.
  */
 #define cpu_feature_enabled(bit)	\
-	(__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 :	\
-	 cpu_has(&boot_cpu_data, bit))
+	(__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit))
 
 #define boot_cpu_has(bit)	cpu_has(&boot_cpu_data, bit)