diff mbox series

[V2,2/3] riscv: atomic: Optimize acquire and release for AMO operations

Message ID 20220412034957.1481088-3-guoren@kernel.org (mailing list archive)
State New, archived
Headers show
Series riscv: atomic: Optimize AMO instructions usage | expand

Commit Message

Guo Ren April 12, 2022, 3:49 a.m. UTC 
From: Guo Ren <guoren@linux.alibaba.com>

Current acquire & release implementations from atomic-arch-
fallback.h are using __atomic_acquire/release_fence(), it cause
another extra "fence r, rw/fence rw,w" instruction after/before
AMO instruction. RISC-V AMO instructions could combine acquire
and release in the instruction self, we could gain two benefits by
using this feature:
 - Reduce an instruction
 - Prevent strong "fence r/fence ,w" which are used to protect
   "lr/sc".

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Mark Rutland <mark.rutland@arm.com>
---
 arch/riscv/include/asm/atomic.h  | 64 ++++++++++++++++++++++++++++++++
 arch/riscv/include/asm/cmpxchg.h | 12 ++----
 2 files changed, 68 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
index ac9bdf4fc404..20ce8b83bc18 100644
--- a/arch/riscv/include/asm/atomic.h
+++ b/arch/riscv/include/asm/atomic.h
@@ -99,6 +99,30 @@  c_type arch_atomic##prefix##_fetch_##op##_relaxed(c_type i,		\
 	return ret;							\
 }									\
 static __always_inline							\
+c_type arch_atomic##prefix##_fetch_##op##_acquire(c_type i,		\
+					     atomic##prefix##_t *v)	\
+{									\
+	register c_type ret;						\
+	__asm__ __volatile__ (						\
+		"	amo" #asm_op "." #asm_type ".aq %1, %2, %0"	\
+		: "+A" (v->counter), "=r" (ret)				\
+		: "r" (I)						\
+		: "memory");						\
+	return ret;							\
+}									\
+static __always_inline							\
+c_type arch_atomic##prefix##_fetch_##op##_release(c_type i,		\
+					     atomic##prefix##_t *v)	\
+{									\
+	register c_type ret;						\
+	__asm__ __volatile__ (						\
+		"	amo" #asm_op "." #asm_type ".rl %1, %2, %0"	\
+		: "+A" (v->counter), "=r" (ret)				\
+		: "r" (I)						\
+		: "memory");						\
+	return ret;							\
+}									\
+static __always_inline							\
 c_type arch_atomic##prefix##_fetch_##op(c_type i, atomic##prefix##_t *v)	\
 {									\
 	register c_type ret;						\
@@ -118,6 +142,18 @@  c_type arch_atomic##prefix##_##op##_return_relaxed(c_type i,		\
         return arch_atomic##prefix##_fetch_##op##_relaxed(i, v) c_op I;	\
 }									\
 static __always_inline							\
+c_type arch_atomic##prefix##_##op##_return_acquire(c_type i,		\
+					      atomic##prefix##_t *v)	\
+{									\
+        return arch_atomic##prefix##_fetch_##op##_acquire(i, v) c_op I;	\
+}									\
+static __always_inline							\
+c_type arch_atomic##prefix##_##op##_return_release(c_type i,		\
+					      atomic##prefix##_t *v)	\
+{									\
+        return arch_atomic##prefix##_fetch_##op##_release(i, v) c_op I;	\
+}									\
+static __always_inline							\
 c_type arch_atomic##prefix##_##op##_return(c_type i, atomic##prefix##_t *v)	\
 {									\
         return arch_atomic##prefix##_fetch_##op(i, v) c_op I;		\
@@ -140,22 +176,38 @@  ATOMIC_OPS(sub, add, +, -i)
 
 #define arch_atomic_add_return_relaxed	arch_atomic_add_return_relaxed
 #define arch_atomic_sub_return_relaxed	arch_atomic_sub_return_relaxed
+#define arch_atomic_add_return_acquire	arch_atomic_add_return_acquire
+#define arch_atomic_sub_return_acquire	arch_atomic_sub_return_acquire
+#define arch_atomic_add_return_release	arch_atomic_add_return_release
+#define arch_atomic_sub_return_release	arch_atomic_sub_return_release
 #define arch_atomic_add_return		arch_atomic_add_return
 #define arch_atomic_sub_return		arch_atomic_sub_return
 
 #define arch_atomic_fetch_add_relaxed	arch_atomic_fetch_add_relaxed
 #define arch_atomic_fetch_sub_relaxed	arch_atomic_fetch_sub_relaxed
+#define arch_atomic_fetch_add_acquire	arch_atomic_fetch_add_acquire
+#define arch_atomic_fetch_sub_acquire	arch_atomic_fetch_sub_acquire
+#define arch_atomic_fetch_add_release	arch_atomic_fetch_add_release
+#define arch_atomic_fetch_sub_release	arch_atomic_fetch_sub_release
 #define arch_atomic_fetch_add		arch_atomic_fetch_add
 #define arch_atomic_fetch_sub		arch_atomic_fetch_sub
 
 #ifndef CONFIG_GENERIC_ATOMIC64
 #define arch_atomic64_add_return_relaxed	arch_atomic64_add_return_relaxed
 #define arch_atomic64_sub_return_relaxed	arch_atomic64_sub_return_relaxed
+#define arch_atomic64_add_return_acquire	arch_atomic64_add_return_acquire
+#define arch_atomic64_sub_return_acquire	arch_atomic64_sub_return_acquire
+#define arch_atomic64_add_return_release	arch_atomic64_add_return_release
+#define arch_atomic64_sub_return_release	arch_atomic64_sub_return_release
 #define arch_atomic64_add_return		arch_atomic64_add_return
 #define arch_atomic64_sub_return		arch_atomic64_sub_return
 
 #define arch_atomic64_fetch_add_relaxed	arch_atomic64_fetch_add_relaxed
 #define arch_atomic64_fetch_sub_relaxed	arch_atomic64_fetch_sub_relaxed
+#define arch_atomic64_fetch_add_acquire	arch_atomic64_fetch_add_acquire
+#define arch_atomic64_fetch_sub_acquire	arch_atomic64_fetch_sub_acquire
+#define arch_atomic64_fetch_add_release	arch_atomic64_fetch_add_release
+#define arch_atomic64_fetch_sub_release	arch_atomic64_fetch_sub_release
 #define arch_atomic64_fetch_add		arch_atomic64_fetch_add
 #define arch_atomic64_fetch_sub		arch_atomic64_fetch_sub
 #endif
@@ -178,6 +230,12 @@  ATOMIC_OPS(xor, xor, i)
 #define arch_atomic_fetch_and_relaxed	arch_atomic_fetch_and_relaxed
 #define arch_atomic_fetch_or_relaxed	arch_atomic_fetch_or_relaxed
 #define arch_atomic_fetch_xor_relaxed	arch_atomic_fetch_xor_relaxed
+#define arch_atomic_fetch_and_acquire	arch_atomic_fetch_and_acquire
+#define arch_atomic_fetch_or_acquire	arch_atomic_fetch_or_acquire
+#define arch_atomic_fetch_xor_acquire	arch_atomic_fetch_xor_acquire
+#define arch_atomic_fetch_and_release	arch_atomic_fetch_and_release
+#define arch_atomic_fetch_or_release	arch_atomic_fetch_or_release
+#define arch_atomic_fetch_xor_release	arch_atomic_fetch_xor_release
 #define arch_atomic_fetch_and		arch_atomic_fetch_and
 #define arch_atomic_fetch_or		arch_atomic_fetch_or
 #define arch_atomic_fetch_xor		arch_atomic_fetch_xor
@@ -186,6 +244,12 @@  ATOMIC_OPS(xor, xor, i)
 #define arch_atomic64_fetch_and_relaxed	arch_atomic64_fetch_and_relaxed
 #define arch_atomic64_fetch_or_relaxed	arch_atomic64_fetch_or_relaxed
 #define arch_atomic64_fetch_xor_relaxed	arch_atomic64_fetch_xor_relaxed
+#define arch_atomic64_fetch_and_acquire	arch_atomic64_fetch_and_acquire
+#define arch_atomic64_fetch_or_acquire	arch_atomic64_fetch_or_acquire
+#define arch_atomic64_fetch_xor_acquire	arch_atomic64_fetch_xor_acquire
+#define arch_atomic64_fetch_and_release	arch_atomic64_fetch_and_release
+#define arch_atomic64_fetch_or_release	arch_atomic64_fetch_or_release
+#define arch_atomic64_fetch_xor_release	arch_atomic64_fetch_xor_release
 #define arch_atomic64_fetch_and		arch_atomic64_fetch_and
 #define arch_atomic64_fetch_or		arch_atomic64_fetch_or
 #define arch_atomic64_fetch_xor		arch_atomic64_fetch_xor
diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h
index 12debce235e5..1af8db92250b 100644
--- a/arch/riscv/include/asm/cmpxchg.h
+++ b/arch/riscv/include/asm/cmpxchg.h
@@ -52,16 +52,14 @@ 
 	switch (size) {							\
 	case 4:								\
 		__asm__ __volatile__ (					\
-			"	amoswap.w %0, %2, %1\n"			\
-			RISCV_ACQUIRE_BARRIER				\
+			"	amoswap.w.aq %0, %2, %1\n"		\
 			: "=r" (__ret), "+A" (*__ptr)			\
 			: "r" (__new)					\
 			: "memory");					\
 		break;							\
 	case 8:								\
 		__asm__ __volatile__ (					\
-			"	amoswap.d %0, %2, %1\n"			\
-			RISCV_ACQUIRE_BARRIER				\
+			"	amoswap.d.aq %0, %2, %1\n"		\
 			: "=r" (__ret), "+A" (*__ptr)			\
 			: "r" (__new)					\
 			: "memory");					\
@@ -87,16 +85,14 @@ 
 	switch (size) {							\
 	case 4:								\
 		__asm__ __volatile__ (					\
-			RISCV_RELEASE_BARRIER				\
-			"	amoswap.w %0, %2, %1\n"			\
+			"	amoswap.w.rl %0, %2, %1\n"		\
 			: "=r" (__ret), "+A" (*__ptr)			\
 			: "r" (__new)					\
 			: "memory");					\
 		break;							\
 	case 8:								\
 		__asm__ __volatile__ (					\
-			RISCV_RELEASE_BARRIER				\
-			"	amoswap.d %0, %2, %1\n"			\
+			"	amoswap.d.rl %0, %2, %1\n"		\
 			: "=r" (__ret), "+A" (*__ptr)			\
 			: "r" (__new)					\
 			: "memory");					\