[v3,08/11] x86/percpu: Clean up percpu_cmpxchg_op()
diff mbox series

Message ID 20200720204925.3654302-9-ndesaulniers@google.com
State In Next
Commit 2355e79e8d550c7a5f319264d3b50b0e8cbb82b6
Headers show
Series
  • i386 Clang support
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Commit Message

Nick Desaulniers July 20, 2020, 8:49 p.m. UTC
From: Brian Gerst <brgerst@gmail.com>

The core percpu macros already have a switch on the data size, so the switch
in the x86 code is redundant and produces more dead code.

Also use appropriate types for the width of the instructions.  This avoids
errors when compiling with Clang.

Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
 arch/x86/include/asm/percpu.h | 58 +++++++++++------------------------
 1 file changed, 18 insertions(+), 40 deletions(-)

Patch
diff mbox series

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index ac6d7e76c0d4..7efc0b5c4ff0 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -236,39 +236,17 @@  do {									\
  * cmpxchg has no such implied lock semantics as a result it is much
  * more efficient for cpu local operations.
  */
-#define percpu_cmpxchg_op(qual, var, oval, nval)			\
+#define percpu_cmpxchg_op(size, qual, _var, _oval, _nval)		\
 ({									\
-	typeof(var) pco_ret__;						\
-	typeof(var) pco_old__ = (oval);					\
-	typeof(var) pco_new__ = (nval);					\
-	switch (sizeof(var)) {						\
-	case 1:								\
-		asm qual ("cmpxchgb %2, "__percpu_arg(1)		\
-			    : "=a" (pco_ret__), "+m" (var)		\
-			    : "q" (pco_new__), "0" (pco_old__)		\
-			    : "memory");				\
-		break;							\
-	case 2:								\
-		asm qual ("cmpxchgw %2, "__percpu_arg(1)		\
-			    : "=a" (pco_ret__), "+m" (var)		\
-			    : "r" (pco_new__), "0" (pco_old__)		\
-			    : "memory");				\
-		break;							\
-	case 4:								\
-		asm qual ("cmpxchgl %2, "__percpu_arg(1)		\
-			    : "=a" (pco_ret__), "+m" (var)		\
-			    : "r" (pco_new__), "0" (pco_old__)		\
-			    : "memory");				\
-		break;							\
-	case 8:								\
-		asm qual ("cmpxchgq %2, "__percpu_arg(1)		\
-			    : "=a" (pco_ret__), "+m" (var)		\
-			    : "r" (pco_new__), "0" (pco_old__)		\
-			    : "memory");				\
-		break;							\
-	default: __bad_percpu_size();					\
-	}								\
-	pco_ret__;							\
+	__pcpu_type_##size pco_old__ = __pcpu_cast_##size(_oval);	\
+	__pcpu_type_##size pco_new__ = __pcpu_cast_##size(_nval);	\
+	asm qual (__pcpu_op2_##size("cmpxchg", "%[nval]",		\
+				    __percpu_arg([var]))		\
+		  : [oval] "+a" (pco_old__),				\
+		    [var] "+m" (_var)					\
+		  : [nval] __pcpu_reg_##size(, pco_new__)		\
+		  : "memory");						\
+	(typeof(_var))(unsigned long) pco_old__;			\
 })
 
 /*
@@ -336,16 +314,16 @@  do {									\
 #define raw_cpu_add_return_1(pcp, val)		percpu_add_return_op(1, , pcp, val)
 #define raw_cpu_add_return_2(pcp, val)		percpu_add_return_op(2, , pcp, val)
 #define raw_cpu_add_return_4(pcp, val)		percpu_add_return_op(4, , pcp, val)
-#define raw_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(, pcp, oval, nval)
-#define raw_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(, pcp, oval, nval)
-#define raw_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(, pcp, oval, nval)
+#define raw_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(1, , pcp, oval, nval)
+#define raw_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(2, , pcp, oval, nval)
+#define raw_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(4, , pcp, oval, nval)
 
 #define this_cpu_add_return_1(pcp, val)		percpu_add_return_op(1, volatile, pcp, val)
 #define this_cpu_add_return_2(pcp, val)		percpu_add_return_op(2, volatile, pcp, val)
 #define this_cpu_add_return_4(pcp, val)		percpu_add_return_op(4, volatile, pcp, val)
-#define this_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(volatile, pcp, oval, nval)
-#define this_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(volatile, pcp, oval, nval)
-#define this_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(volatile, pcp, oval, nval)
+#define this_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(1, volatile, pcp, oval, nval)
+#define this_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(2, volatile, pcp, oval, nval)
+#define this_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(4, volatile, pcp, oval, nval)
 
 #ifdef CONFIG_X86_CMPXCHG64
 #define percpu_cmpxchg8b_double(pcp1, pcp2, o1, o2, n1, n2)		\
@@ -376,7 +354,7 @@  do {									\
 #define raw_cpu_or_8(pcp, val)			percpu_to_op(8, , "or", (pcp), val)
 #define raw_cpu_add_return_8(pcp, val)		percpu_add_return_op(8, , pcp, val)
 #define raw_cpu_xchg_8(pcp, nval)		raw_percpu_xchg_op(pcp, nval)
-#define raw_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(, pcp, oval, nval)
+#define raw_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(8, , pcp, oval, nval)
 
 #define this_cpu_read_8(pcp)			percpu_from_op(8, volatile, "mov", pcp)
 #define this_cpu_write_8(pcp, val)		percpu_to_op(8, volatile, "mov", (pcp), val)
@@ -385,7 +363,7 @@  do {									\
 #define this_cpu_or_8(pcp, val)			percpu_to_op(8, volatile, "or", (pcp), val)
 #define this_cpu_add_return_8(pcp, val)		percpu_add_return_op(8, volatile, pcp, val)
 #define this_cpu_xchg_8(pcp, nval)		percpu_xchg_op(8, volatile, pcp, nval)
-#define this_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(volatile, pcp, oval, nval)
+#define this_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(8, volatile, pcp, oval, nval)
 
 /*
  * Pretty complex macro to generate cmpxchg16 instruction.  The instruction