Use the APIC to determine the hardware processor id - i386

hard_smp_processor_id used to be just a macro that hard-coded
hard_smp_processor_id to 0 in the non SMP case.  When booting non SMP kernels
on hardware where the boot ioapic id is not 0 this turns out to be a problem.
This is happens frequently in the case of kdump and once in a great while in
the case of real hardware.

Use the APIC to determine the hardware processor id in both UP and SMP kernels
to fix this issue.

Notice that hard_smp_processor_id is only used by SMP code or by code that
works with apics so we do not need to handle the case when apics are not
present and hard_smp_processor_id should never be called there.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Cc: "Luck, Tony" <tony.luck@intel.com>
Acked-by: Andi Kleen <ak@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 15 deletions

diff --git a/include/asm-i386/smp.h b/include/asm-i386/smp.h
index 3243fa6..0c71327 100644
--- a/include/asm-i386/smp.h
+++ b/include/asm-i386/smp.h
@@ -124,20 +124,6 @@ static inline int num_booting_cpus(void)
 	return cpus_weight(cpu_callout_map);
 }
 
-#ifdef CONFIG_X86_LOCAL_APIC
-
-#ifdef APIC_DEFINITION
-extern int hard_smp_processor_id(void);
-#else
-#include <mach_apicdef.h>
-static inline int hard_smp_processor_id(void)
-{
-	/* we don't want to mark this access volatile - bad code generation */
-	return GET_APIC_ID(*(unsigned long *)(APIC_BASE+APIC_ID));
-}
-#endif
-#endif
-
 extern int safe_smp_processor_id(void);
 extern int __cpu_disable(void);
 extern void __cpu_die(unsigned int cpu);
@@ -147,7 +133,6 @@ extern unsigned int num_processors;
 
 #else /* CONFIG_SMP */
 
-#define hard_smp_processor_id()		0
 #define safe_smp_processor_id()		0
 #define cpu_physical_id(cpu)		boot_cpu_physical_apicid
 
@@ -157,6 +142,27 @@ extern unsigned int num_processors;
 
 #ifndef __ASSEMBLY__
 
+#ifdef CONFIG_X86_LOCAL_APIC
+
+#ifdef APIC_DEFINITION
+extern int hard_smp_processor_id(void);
+#else
+#include <mach_apicdef.h>
+static inline int hard_smp_processor_id(void)
+{
+	/* we don't want to mark this access volatile - bad code generation */
+	return GET_APIC_ID(*(unsigned long *)(APIC_BASE+APIC_ID));
+}
+#endif /* APIC_DEFINITION */
+
+#else /* CONFIG_X86_LOCAL_APIC */
+
+#ifndef CONFIG_SMP
+#define hard_smp_processor_id()		0
+#endif
+
+#endif /* CONFIG_X86_LOCAL_APIC */
+
 extern u8 apicid_2_node[];
 
 #ifdef CONFIG_X86_LOCAL_APIC