Commit 1bd46782 authored by Russell King's avatar Russell King
Browse files

ARM: avoid unwanted GCC memset()/memcpy() optimisations for IO variants 



We don't want GCC optimising our memset_io(), memcpy_fromio() or
memcpy_toio() variants, so we must not call one of the standard
functions.  Provide a separate name for our assembly memcpy() and
memset() functions, and use that instead, thereby bypassing GCC's
ability to optimise these operations.

GCCs optimisation may introduce unaligned accesses which are invalid
for device mappings.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 9ab79bb2

arch/arm/include/asm/io.h

+6 −3
Original line number Diff line number Diff line
@@ -316,21 +316,24 @@ extern void _memset_io(volatile void __iomem *, int, size_t); 
static inline void memset_io(volatile void __iomem *dst, unsigned c,

	size_t count)

{

	memset((void __force *)dst, c, count);

	extern void mmioset(void *, unsigned int, size_t);

	mmioset((void __force *)dst, c, count);

}

#define memset_io(dst,c,count) memset_io(dst,c,count)



static inline void memcpy_fromio(void *to, const volatile void __iomem *from,

	size_t count)

{

	memcpy(to, (const void __force *)from, count);

	extern void mmiocpy(void *, const void *, size_t);

	mmiocpy(to, (const void __force *)from, count);

}

#define memcpy_fromio(to,from,count) memcpy_fromio(to,from,count)



static inline void memcpy_toio(volatile void __iomem *to, const void *from,

	size_t count)

{

	memcpy((void __force *)to, from, count);

	extern void mmiocpy(void *, const void *, size_t);

	mmiocpy((void __force *)to, from, count);

}

#define memcpy_toio(to,from,count) memcpy_toio(to,from,count)

arch/arm/kernel/armksyms.c

+6 −0
Original line number Diff line number Diff line
@@ -50,6 +50,9 @@ extern void __aeabi_ulcmp(void); 


extern void fpundefinstr(void);



void mmioset(void *, unsigned int, size_t);

void mmiocpy(void *, const void *, size_t);



	/* platform dependent support */

EXPORT_SYMBOL(arm_delay_ops);
@@ -88,6 +91,9 @@ EXPORT_SYMBOL(memmove); 
EXPORT_SYMBOL(memchr);

EXPORT_SYMBOL(__memzero);



EXPORT_SYMBOL(mmioset);

EXPORT_SYMBOL(mmiocpy);



#ifdef CONFIG_MMU

EXPORT_SYMBOL(copy_page);

arch/arm/lib/memcpy.S

+2 −0
Original line number Diff line number Diff line
@@ -61,8 +61,10 @@ 


/* Prototype: void *memcpy(void *dest, const void *src, size_t n); */



ENTRY(mmiocpy)

ENTRY(memcpy)



#include "copy_template.S"



ENDPROC(memcpy)

ENDPROC(mmiocpy)

arch/arm/lib/memset.S

+2 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
	.text

	.align	5



ENTRY(mmioset)

ENTRY(memset)

UNWIND( .fnstart         )

	ands	r3, r0, #3		@ 1 unaligned?
@@ -133,3 +134,4 @@ UNWIND( .fnstart ) 
	b	1b

UNWIND( .fnend   )

ENDPROC(memset)

ENDPROC(mmioset)

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