[PATCH] riscv: Avoid io read/write cause wrong result

Nick Hu nick.hu at sifive.com
Mon Oct 18 05:50:05 CEST 2021

io read/write may cause wrong result because they may read/write data
from/to register instead of memory. Add 'volatile' to avoid it.

Signed-off-by: Nick Hu <nick.hu at sifive.com>
 arch/riscv/include/asm/io.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index acf5a96449..3540773c4f 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -44,15 +44,15 @@ static inline phys_addr_t map_to_sysmem(const void *ptr)
  * read/writes.  We define __arch_*[bl] here, and leave __arch_*w
  * to the architecture specific code.
-#define __arch_getb(a)			(*(unsigned char *)(a))
-#define __arch_getw(a)			(*(unsigned short *)(a))
-#define __arch_getl(a)			(*(unsigned int *)(a))
-#define __arch_getq(a)			(*(unsigned long long *)(a))
-#define __arch_putb(v, a)		(*(unsigned char *)(a) = (v))
-#define __arch_putw(v, a)		(*(unsigned short *)(a) = (v))
-#define __arch_putl(v, a)		(*(unsigned int *)(a) = (v))
-#define __arch_putq(v, a)		(*(unsigned long long *)(a) = (v))
+#define __arch_getb(a)			(*(volatile unsigned char *)(a))
+#define __arch_getw(a)			(*(volatile unsigned short *)(a))
+#define __arch_getl(a)			(*(volatile unsigned int *)(a))
+#define __arch_getq(a)			(*(volatile unsigned long long *)(a))
+#define __arch_putb(v, a)		(*(volatile unsigned char *)(a) = (v))
+#define __arch_putw(v, a)		(*(volatile unsigned short *)(a) = (v))
+#define __arch_putl(v, a)		(*(volatile unsigned int *)(a) = (v))
+#define __arch_putq(v, a)		(*(volatile unsigned long long *)(a) = (v))
 #define __raw_writeb(v, a)		__arch_putb(v, a)
 #define __raw_writew(v, a)		__arch_putw(v, a)

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