x86: Support for this_cpu_add, sub, dec, inc_return

Supply an implementation for x86 in order to generate more efficient code.

V2->V3:
	- Cleanup
	- Remove strange type checking from percpu_add_return_op.

tj: - Dropped unused typedef from percpu_add_return_op().
    - Renamed ret__ to paro_ret__ in percpu_add_return_op().
    - Minor indentation adjustments.

Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index f899e01a8ac9..38f9e965ff96 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -177,6 +177,39 @@ do {									\
         }                                                               \
 } while (0)
 
+/*
+ * Add return operation
+ */
+#define percpu_add_return_op(var, val)                                  \
+({                                                                      \
+        typeof(var) paro_ret__ = val;                                   \
+        switch (sizeof(var)) {                                          \
+        case 1:                                                         \
+                asm("xaddb %0, "__percpu_arg(1)                         \
+                            : "+q" (paro_ret__), "+m" (var)             \
+                            : : "memory");                              \
+                break;                                                  \
+        case 2:                                                         \
+                asm("xaddw %0, "__percpu_arg(1)                         \
+                            : "+r" (paro_ret__), "+m" (var)             \
+                            : : "memory");                              \
+                break;                                                  \
+        case 4:                                                         \
+                asm("xaddl %0, "__percpu_arg(1)                         \
+                            : "+r" (paro_ret__), "+m" (var)             \
+                            : : "memory");                              \
+                break;                                                  \
+        case 8:                                                         \
+                asm("xaddq %0, "__percpu_arg(1)                         \
+                            : "+re" (paro_ret__), "+m" (var)            \
+                            : : "memory");                              \
+                break;                                                  \
+        default: __bad_percpu_size();                                   \
+        }                                                               \
+        paro_ret__ += val;                                              \
+        paro_ret__;                                                     \
+})
+
 #define percpu_from_op(op, var, constraint)             \
 ({                                                      \
         typeof(var) pfo_ret__;                          \
@@ -300,6 +333,14 @@ do {									\
 #define irqsafe_cpu_xor_2(pcp, val)     percpu_to_op("xor", (pcp), val)
 #define irqsafe_cpu_xor_4(pcp, val)     percpu_to_op("xor", (pcp), val)
 
+#ifndef CONFIG_M386
+#define __this_cpu_add_return_1(pcp, val) percpu_add_return_op(pcp, val)
+#define __this_cpu_add_return_2(pcp, val) percpu_add_return_op(pcp, val)
+#define __this_cpu_add_return_4(pcp, val) percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_1(pcp, val) percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_2(pcp, val) percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_4(pcp, val) percpu_add_return_op(pcp, val)
+#endif
 /*
  * Per cpu atomic 64 bit operations are only available under 64 bit.
  * 32 bit must fall back to generic operations.
@@ -324,6 +365,8 @@ do {									\
 #define irqsafe_cpu_or_8(pcp, val)      percpu_to_op("or", (pcp), val)
 #define irqsafe_cpu_xor_8(pcp, val)     percpu_to_op("xor", (pcp), val)
 
+#define __this_cpu_add_return_8(pcp, val) percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_8(pcp, val) percpu_add_return_op(pcp, val)
 #endif
 
 /* This is not atomic against other CPUs -- CPU preemption needs to be off */