[v2,2/4] riscv: uaccess: use input constraints for ptr of __put_user

Commit Message

Cyril Bur Nov. 18, 2024, 11:01 p.m. UTC

From: Jisheng Zhang <[e-mail]>

I believe the output constraints "=m" is not necessary, because
the instruction itself is "write", we don't need the compiler
to "write" for us. So tell compiler we read from memory instead
of writing.

Signed-off-by: Jisheng Zhang <[e-mail]>
Signed-off-by: Cyril Bur <[e-mail]>
---
 arch/riscv/include/asm/uaccess.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

Patch

diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index 09d4ca37522c..84b084e388a7 100644
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -186,11 +186,11 @@  do {								\
 	__typeof__(*(ptr)) __x = x;				\
 	__asm__ __volatile__ (					\
 		"1:\n"						\
-		"	" insn " %z2, %1\n"			\
+		"	" insn " %z1, %2\n"			\
 		"2:\n"						\
 		_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %0)		\
-		: "+r" (err), "=m" (*(ptr))			\
-		: "rJ" (__x));					\
+		: "+r" (err)			\
+		: "rJ" (__x), "m"(*(ptr)));					\
 } while (0)
 
 #ifdef CONFIG_64BIT
@@ -203,16 +203,16 @@  do {								\
 	u64 __x = (__typeof__((x)-(x)))(x);			\
 	__asm__ __volatile__ (					\
 		"1:\n"						\
-		"	sw %z3, %1\n"				\
+		"	sw %z1, %3\n"				\
 		"2:\n"						\
-		"	sw %z4, %2\n"				\
+		"	sw %z2, %4\n"				\
 		"3:\n"						\
 		_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0)		\
 		_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0)		\
-		: "+r" (err),					\
-			"=m" (__ptr[__LSW]),			\
-			"=m" (__ptr[__MSW])			\
-		: "rJ" (__x), "rJ" (__x >> 32));		\
+		: "+r" (err)					\
+		: "rJ" (__x), "rJ" (__x >> 32),			\
+			"m" (__ptr[__LSW]),			\
+			"m" (__ptr[__MSW]));			\
 } while (0)
 #endif /* CONFIG_64BIT */