1 files changed, 17 insertions, 27 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 2763cb37b55..fb04e49776b 100644
--- 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 */
@@ -241,25 +231,25 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
                         continue;
                 if (*ptr > text_end)
                         continue;
-                text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock prefix */
+                /* turn DS segment override prefix into lock prefix */
+                text_poke(*ptr, ((unsigned char []){0xf0}), 1);
         };
 }
 
 static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end)
 {
         u8 **ptr;
-        char insn[1];
 
         if (noreplace_smp)
                 return;
 
-        add_nops(insn, 1);
         for (ptr = start; ptr < end; ptr++) {
                 if (*ptr < text)
                         continue;
                 if (*ptr > text_end)
                         continue;
-                text_poke(*ptr, insn, 1);
+                /* turn lock prefix into DS segment override prefix */
+                text_poke(*ptr, ((unsigned char []){0x3E}), 1);
         };
 }