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Commit 3a044178 authored by Jason Baron's avatar Jason Baron Committed by Borislav Petkov
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readq/writeq: Add explicit lo_hi_[read|write]_q and hi_lo_[read|write]_q 

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: default avatarJason Baron <jbaron@akamai.com>
Link: http://lkml.kernel.org/r/281f09da7ad01e5cea99737ec34d2399bdbbbf63.1403818526.git.jbaron@akamai.com


Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
parent 6866b390

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

+9 −5
Original line number Diff line number Diff line
@@ -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_ */

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

+9 −5
Original line number Diff line number Diff line
@@ -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_ */