x86: make pda a percpu variable

[ Based on original patch from Christoph Lameter and Mike Travis. ]

As pda is now allocated in percpu area, it can easily be made a proper
percpu variable.  Make it so by defining per cpu symbol from linker
script and declaring it in C code for SMP and simply defining it for
UP.  This change cleans up code and brings SMP and UP closer a bit.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 7a995d0e9f7..c8ace880661 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -19,6 +19,7 @@
 #include <asm/msr.h>
 #include <asm/cache.h>
 #include <asm/processor-flags.h>
+#include <asm/percpu.h>
 
 #ifdef CONFIG_PARAVIRT
 #include <asm/asm-offsets.h>
@@ -250,7 +251,7 @@ ENTRY(secondary_startup_64)
          * secondary CPU,initial_gs should be set to its pda address
          * before the CPU runs this code.
          *
-         * On UP, initial_gs points to _boot_cpu_pda and doesn't
+         * On UP, initial_gs points to PER_CPU_VAR(__pda) and doesn't
          * change.
          */
         movl    $MSR_GS_BASE,%ecx
@@ -284,7 +285,7 @@ ENTRY(secondary_startup_64)
 #ifdef CONFIG_SMP
         .quad   __per_cpu_load
 #else
-        .quad   _boot_cpu_pda
+        .quad   PER_CPU_VAR(__pda)
 #endif
         __FINITDATA