While reviewing the addition of io{read,write}64be accessors, Arnd
-finds a potential problem:
"If an architecture overrides readq/writeq to have barriers but does
not override ioread64be/iowrite64be, this will lack the barriers and
behave differently from the little-endian version. I think the only
affected architecture is ARC, since ARM and ARM64 both override the
big-endian accessors to have the correct barriers, and all others
don't use barriers at all."
-suggests a fix for the same problem in existing code (16/32-bit
accessors); the fix leads "to a double-swap on architectures that
don't override the io{read,write}{16,32}be accessors, but it will
work correctly on all architectures without them having to override
these accessors."
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Horia Geantă <horia.geanta@xxxxxxx>
---
include/asm-generic/io.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index eed3bbe88c8a..b79fb2c248a1 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -613,7 +613,7 @@ static inline void iowrite32(u32 value, volatile void __iomem *addr)
#define ioread16be ioread16be
static inline u16 ioread16be(const volatile void __iomem *addr)
{
- return __be16_to_cpu(__raw_readw(addr));
+ return swab16(readw(addr));
}
#endif
@@ -621,7 +621,7 @@ static inline u16 ioread16be(const volatile void __iomem *addr)
#define ioread32be ioread32be
static inline u32 ioread32be(const volatile void __iomem *addr)
{
- return __be32_to_cpu(__raw_readl(addr));
+ return swab32(readl(addr));
}
#endif
@@ -629,7 +629,7 @@ static inline u32 ioread32be(const volatile void __iomem *addr)
#define iowrite16be iowrite16be
static inline void iowrite16be(u16 value, void volatile __iomem *addr)
{
- __raw_writew(__cpu_to_be16(value), addr);
+ writew(swab16(value), addr);
}
#endif
@@ -637,7 +637,7 @@ static inline void iowrite16be(u16 value, void volatile __iomem *addr)
#define iowrite32be iowrite32be
static inline void iowrite32be(u32 value, volatile void __iomem *addr)
{
- __raw_writel(__cpu_to_be32(value), addr);
+ writel(swab32(value), addr);
}
#endif
--
2.4.4
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