2 files changed, 29 insertions, 0 deletions

diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c
index 465188e2d701..1b080ab8a49f 100644
--- a/arch/i386/kernel/smp.c
+++ b/arch/i386/kernel/smp.c
@@ -700,3 +700,30 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
         return 0;
 }
 EXPORT_SYMBOL(smp_call_function_single);
+
+static int convert_apicid_to_cpu(int apic_id)
+{
+        int i;
+
+        for (i = 0; i < NR_CPUS; i++) {
+                if (x86_cpu_to_apicid[i] == apic_id)
+                        return i;
+        }
+        return -1;
+}
+
+int safe_smp_processor_id(void)
+{
+        int apicid, cpuid;
+
+        if (!boot_cpu_has(X86_FEATURE_APIC))
+                return 0;
+
+        apicid = hard_smp_processor_id();
+        if (apicid == BAD_APICID)
+                return 0;
+
+        cpuid = convert_apicid_to_cpu(apicid);
+
+        return cpuid >= 0 ? cpuid : 0;
+}
diff --git a/include/asm-i386/smp.h b/include/asm-i386/smp.h
index 915c26a31b79..6aa1206f6e2a 100644
--- a/include/asm-i386/smp.h
+++ b/include/asm-i386/smp.h
@@ -84,6 +84,7 @@ static inline int hard_smp_processor_id(void)
 #endif
 #endif
 
+extern int safe_smp_processor_id(void);
 extern int __cpu_disable(void);
 extern void __cpu_die(unsigned int cpu);
 extern unsigned int num_processors;
@@ -92,6 +93,7 @@ extern unsigned int num_processors;
 
 #else /* CONFIG_SMP */
 
+#define safe_smp_processor_id()         0
 #define cpu_physical_id(cpu)            boot_cpu_physical_apicid
 
 #define NO_PROC_ID              0xFF            /* No processor magic marker */