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>
diff --git a/arch/x86/kernel/vmlinux_64.lds.S b/arch/x86/kernel/vmlinux_64.lds.S
index 962f21f..d2a0baa 100644
--- a/arch/x86/kernel/vmlinux_64.lds.S
+++ b/arch/x86/kernel/vmlinux_64.lds.S
@@ -217,10 +217,12 @@
* percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the
* output PHDR, so the next output section - __data_nosave - should
* switch it back to data.init. Also, pda should be at the head of
- * percpu area. Preallocate it.
+ * percpu area. Preallocate it and define the percpu offset symbol
+ * so that it can be accessed as a percpu variable.
*/
. = ALIGN(PAGE_SIZE);
PERCPU_VADDR_PREALLOC(0, :percpu, pda_size)
+ per_cpu____pda = __per_cpu_start;
#else
PERCPU(PAGE_SIZE)
#endif