riscv/cmpxchg: Deduplicate xchg() asm functions

In this header every xchg define (_relaxed, _acquire, _release, vanilla)
contain it's own asm file, both for 4-byte variables an 8-byte variables,
on a total of 8 versions of mostly the same asm.

This is usually bad, as it means any change may be done in up to 8
different places.

Unify those versions by creating a new define with enough parameters to
generate any version of the previous 8.

Then unify the result under a more general define, and simplify
arch_xchg* generation.

(This did not cause any change in generated asm)

Signed-off-by: Leonardo Bras <[email protected]>
Reviewed-by: Guo Ren <[email protected]>
Reviewed-by: Andrea Parri <[email protected]>
Tested-by: Guo Ren <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: Leonardo Bras

arch/riscv/include/asm/cmpxchg.h

@@ -11,140 +11,48 @@
 #include <asm/barrier.h>
 #include <asm/fence.h>
 
-#define __xchg_relaxed(ptr, new, size)					\
+#define __arch_xchg(sfx, prepend, append, r, p, n)			\
 ({									\
-	__typeof__(ptr) __ptr = (ptr);					\
-	__typeof__(new) __new = (new);					\
-	__typeof__(*(ptr)) __ret;					\
-	switch (size) {							\
-	case 4:								\
-		__asm__ __volatile__ (					\
-			"	amoswap.w %0, %2, %1\n"			\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
-		break;							\
-	case 8:								\
-		__asm__ __volatile__ (					\
-			"	amoswap.d %0, %2, %1\n"			\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
-		break;							\
-	default:							\
-		BUILD_BUG();						\
-	}								\
-	__ret;								\
-})
-
-#define arch_xchg_relaxed(ptr, x)					\
-({									\
-	__typeof__(*(ptr)) _x_ = (x);					\
-	(__typeof__(*(ptr))) __xchg_relaxed((ptr),			\
-					    _x_, sizeof(*(ptr)));	\
+	__asm__ __volatile__ (						\
+		prepend							\
+		"	amoswap" sfx " %0, %2, %1\n"			\
+		append							\
+		: "=r" (r), "+A" (*(p))					\
+		: "r" (n)						\
+		: "memory");						\
 })
 
-#define __xchg_acquire(ptr, new, size)					\
+#define _arch_xchg(ptr, new, sfx, prepend, append)			\
 ({									\
 	__typeof__(ptr) __ptr = (ptr);					\
-	__typeof__(new) __new = (new);					\
-	__typeof__(*(ptr)) __ret;					\
-	switch (size) {							\
+	__typeof__(*(__ptr)) __new = (new);				\
+	__typeof__(*(__ptr)) __ret;					\
+	switch (sizeof(*__ptr)) {					\
 	case 4:								\
-		__asm__ __volatile__ (					\
-			"	amoswap.w %0, %2, %1\n"			\
-			RISCV_ACQUIRE_BARRIER				\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
+		__arch_xchg(".w" sfx, prepend, append,			\
+			      __ret, __ptr, __new);			\
 		break;							\
 	case 8:								\
-		__asm__ __volatile__ (					\
-			"	amoswap.d %0, %2, %1\n"			\
-			RISCV_ACQUIRE_BARRIER				\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
+		__arch_xchg(".d" sfx, prepend, append,			\
+			      __ret, __ptr, __new);			\
 		break;							\
 	default:							\
 		BUILD_BUG();						\
 	}								\
-	__ret;								\
+	(__typeof__(*(__ptr)))__ret;					\
 })
 
-#define arch_xchg_acquire(ptr, x)					\
-({									\
-	__typeof__(*(ptr)) _x_ = (x);					\
-	(__typeof__(*(ptr))) __xchg_acquire((ptr),			\
-					    _x_, sizeof(*(ptr)));	\
-})
+#define arch_xchg_relaxed(ptr, x)					\
+	_arch_xchg(ptr, x, "", "", "")
 
-#define __xchg_release(ptr, new, size)					\
-({									\
-	__typeof__(ptr) __ptr = (ptr);					\
-	__typeof__(new) __new = (new);					\
-	__typeof__(*(ptr)) __ret;					\
-	switch (size) {							\
-	case 4:								\
-		__asm__ __volatile__ (					\
-			RISCV_RELEASE_BARRIER				\
-			"	amoswap.w %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"			\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
-		break;							\
-	default:							\
-		BUILD_BUG();						\
-	}								\
-	__ret;								\
-})
+#define arch_xchg_acquire(ptr, x)					\
+	_arch_xchg(ptr, x, "", "", RISCV_ACQUIRE_BARRIER)
 
 #define arch_xchg_release(ptr, x)					\
-({									\
-	__typeof__(*(ptr)) _x_ = (x);					\
-	(__typeof__(*(ptr))) __xchg_release((ptr),			\
-					    _x_, sizeof(*(ptr)));	\
-})
-
-#define __arch_xchg(ptr, new, size)					\
-({									\
-	__typeof__(ptr) __ptr = (ptr);					\
-	__typeof__(new) __new = (new);					\
-	__typeof__(*(ptr)) __ret;					\
-	switch (size) {							\
-	case 4:								\
-		__asm__ __volatile__ (					\
-			"	amoswap.w.aqrl %0, %2, %1\n"		\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
-		break;							\
-	case 8:								\
-		__asm__ __volatile__ (					\
-			"	amoswap.d.aqrl %0, %2, %1\n"		\
-			: "=r" (__ret), "+A" (*__ptr)			\
-			: "r" (__new)					\
-			: "memory");					\
-		break;							\
-	default:							\
-		BUILD_BUG();						\
-	}								\
-	__ret;								\
-})
+	_arch_xchg(ptr, x, "", RISCV_RELEASE_BARRIER, "")
 
 #define arch_xchg(ptr, x)						\
-({									\
-	__typeof__(*(ptr)) _x_ = (x);					\
-	(__typeof__(*(ptr))) __arch_xchg((ptr), _x_, sizeof(*(ptr)));	\
-})
+	_arch_xchg(ptr, x, ".aqrl", "", "")
 
 #define xchg32(ptr, x)							\
 ({									\