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Commit 7bc13fd3 authored by Will Deacon's avatar Will Deacon Committed by Catalin Marinas
Browse files

arm64: dcache: select DCACHE_WORD_ACCESS for little-endian CPUs 



DCACHE_WORD_ACCESS uses the word-at-a-time API for optimised string
comparisons in the vfs layer.

This patch implements support for load_unaligned_zeropad in much the
same way as has been done for ARM, although big-endian systems are also
supported.

Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 4da7a56c

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ config ARM64 
	select BUILDTIME_EXTABLE_SORT

	select CLONE_BACKWARDS

	select COMMON_CLK

	select DCACHE_WORD_ACCESS

	select GENERIC_CLOCKEVENTS

	select GENERIC_IOMAP

	select GENERIC_IRQ_PROBE

arch/arm64/include/asm/word-at-a-time.h

+40 −0
Original line number Diff line number Diff line
@@ -47,8 +47,48 @@ static inline unsigned long find_zero(unsigned long mask) 
	return fls64(mask) >> 3;

}



#define zero_bytemask(mask) (mask)



#else	/* __AARCH64EB__ */

#include <asm-generic/word-at-a-time.h>

#endif



/*

 * Load an unaligned word from kernel space.

 *

 * In the (very unlikely) case of the word being a page-crosser

 * and the next page not being mapped, take the exception and

 * return zeroes in the non-existing part.

 */

static inline unsigned long load_unaligned_zeropad(const void *addr)

{

	unsigned long ret, offset;



	/* Load word from unaligned pointer addr */

	asm(

	"1:	ldr	%0, %3\n"

	"2:\n"

	"	.pushsection .fixup,\"ax\"\n"

	"	.align 2\n"

	"3:	and	%1, %2, #0x7\n"

	"	bic	%2, %2, #0x7\n"

	"	ldr	%0, [%2]\n"

	"	lsl	%1, %1, #0x3\n"

#ifndef __AARCH64EB__

	"	lsr	%0, %0, %1\n"

#else

	"	lsl	%0, %0, %1\n"

#endif

	"	b	2b\n"

	"	.popsection\n"

	"	.pushsection __ex_table,\"a\"\n"

	"	.align	3\n"

	"	.quad	1b, 3b\n"

	"	.popsection"

	: "=&r" (ret), "=&r" (offset)

	: "r" (addr), "Q" (*(unsigned long *)addr));



	return ret;

}



#endif /* __ASM_WORD_AT_A_TIME_H */