1 files changed, 25 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index e3cdbf9a88bd..1e379ed17b1d 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -27,6 +27,7 @@
 #include <asm/mach_apic.h>
 #include <asm/mmu_context.h>
 #include <asm/proto.h>
+#include <asm/apicdef.h>
 
 /*
  *      Smarter SMP flushing macros. 
@@ -413,3 +414,27 @@ asmlinkage void smp_call_function_interrupt(void)
                 atomic_inc(&call_data->finished);
         }
 }
+
+int safe_smp_processor_id(void)
+{
+        int apicid, i;
+
+        if (disable_apic)
+                return 0;
+
+        apicid = hard_smp_processor_id();
+        if (x86_cpu_to_apicid[apicid] == apicid)
+                return apicid;
+
+        for (i = 0; i < NR_CPUS; ++i) {
+                if (x86_cpu_to_apicid[i] == apicid)
+                        return i;
+        }
+
+        /* No entries in x86_cpu_to_apicid?  Either no MPS|ACPI,
+         * or called too early.  Either way, we must be CPU 0. */
+        if (x86_cpu_to_apicid[0] == BAD_APICID)
+                return 0;
+
+        return 0; /* Should not happen */
+}