percpu: introduce arch_raw_cpu_ptr()

Currently, archs can override raw_cpu_ptr() directly; however, we
wanna build a layer of indirection in the generic part of percpu so
that we can implement generic features there without affecting archs.

Introduce arch_raw_cpu_ptr() which is used to define raw_cpu_ptr() by
generic percpu code.  The two are identical for now.  x86 is currently
the only arch which overrides raw_cpu_ptr() and is converted to
define arch_raw_cpu_ptr() instead.

This doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 63d2b68c826e..a247d80b6630 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -53,9 +53,16 @@ extern unsigned long __per_cpu_offset[NR_CPUS];
 #define per_cpu(var, cpu) \
 	(*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu)))
 
-#ifndef raw_cpu_ptr
-#define raw_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
+/*
+ * Arch may define arch_raw_cpu_ptr() to provide more efficient address
+ * translations for raw_cpu_ptr().
+ */
+#ifndef arch_raw_cpu_ptr
+#define arch_raw_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
 #endif
+
+#define raw_cpu_ptr(ptr) arch_raw_cpu_ptr(ptr)
+
 #ifdef CONFIG_DEBUG_PREEMPT
 #define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
 #else