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io: define stronger ordering for the default readX() implementation 

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>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Sinan Kaya 2018-04-05 09:09:10 -04:00 committed by Arnd Bergmann
parent 64e2c6738b
commit 032d59e1cd
1 changed files with 24 additions and 4 deletions
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28
include/asm-generic/io.h
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@ -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 */