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readq/writeq: Add explicit lo_hi_[read|write]_q and hi_lo_[read|write]_q

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Even on x86-64, I've found the need to break up a readq() into 2 readl()
calls. According to the Intel datasheet for the E3-1200 processor:

"
Software must not access B0/D0/F0 32-bit memory-mapped registers with
requests that cross a DW boundary.
"

(http://www.intel.com/content/www/us/en/processors/xeon/xeon-e3-1200-family-vol-2-datasheet.html p. 16)

I can confirm this is true via several hard machine lockups.

Thus, add explicit hi_lo_[readq|write]_q and lo_hi_[read|write]_q so that these
uses are spelled out.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Link: http://lkml.kernel.org/r/281f09da7ad01e5cea99737ec34d2399bdbbbf63.1403818526.git.jbaron@akamai.com
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Jason Baron 2014-07-04 13:27:04 +02:00 committed by Borislav Petkov
parent 6866b39056
commit 3a044178cc
2 changed files with 18 additions and 10 deletions
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14
include/asm-generic/io-64-nonatomic-hi-lo.h
View File

@ -4,8 +4,7 @@
#include <linux/io.h>
#include <asm-generic/int-ll64.h>
#ifndef readq
static inline __u64 readq(const volatile void __iomem *addr)
static inline __u64 hi_lo_readq(const volatile void __iomem *addr)
{
const volatile u32 __iomem *p = addr;
u32 low, high;
@ -15,14 +14,19 @@ static inline __u64 readq(const volatile void __iomem *addr)
return low + ((u64)high << 32);
}
#endif
#ifndef writeq
static inline void writeq(__u64 val, volatile void __iomem *addr)
static inline void hi_lo_writeq(__u64 val, volatile void __iomem *addr)
{
writel(val >> 32, addr + 4);
writel(val, addr);
}
#ifndef readq
#define readq hi_lo_readq
#endif
#ifndef writeq
#define writeq hi_lo_writeq
#endif
#endif /* _ASM_IO_64_NONATOMIC_HI_LO_H_ */

14
include/asm-generic/io-64-nonatomic-lo-hi.h
View File

@ -4,8 +4,7 @@
#include <linux/io.h>
#include <asm-generic/int-ll64.h>
#ifndef readq
static inline __u64 readq(const volatile void __iomem *addr)
static inline __u64 lo_hi_readq(const volatile void __iomem *addr)
{
const volatile u32 __iomem *p = addr;
u32 low, high;
@ -15,14 +14,19 @@ static inline __u64 readq(const volatile void __iomem *addr)
return low + ((u64)high << 32);
}
#endif
#ifndef writeq
static inline void writeq(__u64 val, volatile void __iomem *addr)
static inline void lo_hi_writeq(__u64 val, volatile void __iomem *addr)
{
writel(val, addr);
writel(val >> 32, addr + 4);
}
#ifndef readq
#define readq lo_hi_readq
#endif
#ifndef writeq
#define writeq lo_hi_writeq
#endif
#endif /* _ASM_IO_64_NONATOMIC_LO_HI_H_ */