x86: use X86_FEATURE_NOPL in alternatives

Use X86_FEATURE_NOPL to determine if it is safe to use P6 NOPs in
alternatives.  Also, replace table and loop with simple if statement.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 2763cb3..65a0c1b 100644 (file)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -145,35 +145,25 @@ static const unsigned char *const p6_nops[ASM_NOP_MAX+1] = {
 extern char __vsyscall_0;
 const unsigned char *const *find_nop_table(void)
 {
-       return boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
-              boot_cpu_data.x86 < 6 ? k8_nops : p6_nops;
+       if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+           boot_cpu_has(X86_FEATURE_NOPL))
+               return p6_nops;
+       else
+               return k8_nops;
 }
 
 #else /* CONFIG_X86_64 */
 
-static const struct nop {
-       int cpuid;
-       const unsigned char *const *noptable;
-} noptypes[] = {
-       { X86_FEATURE_K8, k8_nops },
-       { X86_FEATURE_K7, k7_nops },
-       { X86_FEATURE_P4, p6_nops },
-       { X86_FEATURE_P3, p6_nops },
-       { -1, NULL }
-};
-
 const unsigned char *const *find_nop_table(void)
 {
-       const unsigned char *const *noptable = intel_nops;
-       int i;
-
-       for (i = 0; noptypes[i].cpuid >= 0; i++) {
-               if (boot_cpu_has(noptypes[i].cpuid)) {
-                       noptable = noptypes[i].noptable;
-                       break;
-               }
-       }
-       return noptable;
+       if (boot_cpu_has(X86_FEATURE_K8))
+               return k8_nops;
+       else if (boot_cpu_has(X86_FEATURE_K7))
+               return k7_nops;
+       else if (boot_cpu_has(X86_FEATURE_NOPL))
+               return p6_nops;
+       else
+               return intel_nops;
 }
 
 #endif /* CONFIG_X86_64 */