lkml.org 
[lkml]   [2018]   [Apr]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v4 2/5] io: define stronger ordering for the default readX() implementation
Date
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
\
 
 \ /
  Last update: 2018-04-05 15:10    [W:0.059 / U:0.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site