Messages in this thread Patch in this message | | | From | Sinan Kaya <> | Subject | [PATCH v4 2/5] io: define stronger ordering for the default readX() implementation | Date | Thu, 5 Apr 2018 09:09:10 -0400 |
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The default implementation of mapping readX() to __raw_readX() is wrong. readX() has stronger ordering semantics. Compiler is allowed to reorder __raw_readX() against the memory accesses following register read.
Use the previously defined __io_ar() and __io_br() macros to harden code generation according to architecture support.
Signed-off-by: Sinan Kaya <okaya@codeaurora.org> --- include/asm-generic/io.h | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index 570433b..d27e8af 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -154,7 +154,12 @@ static inline void __raw_writeq(u64 value, volatile void __iomem *addr) #define readb readb static inline u8 readb(const volatile void __iomem *addr) { - return __raw_readb(addr); + u8 val; + + __io_br(); + val = __raw_readb(addr); + __io_ar(); + return val; } #endif @@ -162,7 +167,12 @@ static inline u8 readb(const volatile void __iomem *addr) #define readw readw static inline u16 readw(const volatile void __iomem *addr) { - return __le16_to_cpu(__raw_readw(addr)); + u16 val; + + __io_br(); + val = __le16_to_cpu(__raw_readw(addr)); + __io_ar(); + return val; } #endif @@ -170,7 +180,12 @@ static inline u16 readw(const volatile void __iomem *addr) #define readl readl static inline u32 readl(const volatile void __iomem *addr) { - return __le32_to_cpu(__raw_readl(addr)); + u32 val; + + __io_br(); + val = __le32_to_cpu(__raw_readl(addr)); + __io_ar(); + return val; } #endif @@ -179,7 +194,12 @@ static inline u32 readl(const volatile void __iomem *addr) #define readq readq static inline u64 readq(const volatile void __iomem *addr) { - return __le64_to_cpu(__raw_readq(addr)); + u64 val; + + __io_br(); + val = __le64_to_cpu(__raw_readq(addr)); + __io_ar(); + return val; } #endif #endif /* CONFIG_64BIT */ -- 2.7.4
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