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| author | Will Deacon <will.deacon@arm.com> | 2012-07-06 16:46:08 +0200 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2012-07-09 18:41:11 +0200 |
| commit | b9a50f74905ad9126c91b495ece8a5f45434c643 (patch) | |
| tree | 8ae821933d953f50b52de596e7281bf888c098ec /arch | |
| parent | ARM: 7449/1: use generic strnlen_user and strncpy_from_user functions (diff) | |
| download | linux-b9a50f74905ad9126c91b495ece8a5f45434c643.tar.xz linux-b9a50f74905ad9126c91b495ece8a5f45434c643.zip | |
ARM: 7450/1: dcache: select DCACHE_WORD_ACCESS for little-endian ARMv6+ 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 for ARM CPUs
with native support for unaligned memory accesses (v6+) when running
little-endian.
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/Kconfig | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/word-at-a-time.h | 41 |
2 files changed, 42 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 574561a66d75..acd12efe6f3e 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -48,6 +48,7 @@ config ARM select GENERIC_CLOCKEVENTS_BROADCAST if SMP select GENERIC_STRNCPY_FROM_USER select GENERIC_STRNLEN_USER + select DCACHE_WORD_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && !CPU_BIG_ENDIAN help The ARM series is a line of low-power-consumption RISC chip designs licensed by ARM Ltd and targeted at embedded applications and diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h index 74b2d4578577..4d52f92967a6 100644 --- a/arch/arm/include/asm/word-at-a-time.h +++ b/arch/arm/include/asm/word-at-a-time.h @@ -48,6 +48,47 @@ static inline unsigned long find_zero(unsigned long mask) return ret; } +#ifdef CONFIG_DCACHE_WORD_ACCESS + +#define zero_bytemask(mask) (mask) + +/* + * 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, [%2]\n" + "2:\n" + " .pushsection .fixup,\"ax\"\n" + " .align 2\n" + "3: and %1, %2, #0x3\n" + " bic %2, %2, #0x3\n" + " ldr %0, [%2]\n" + " lsl %1, %1, #0x3\n" + " lsr %0, %0, %1\n" + " b 2b\n" + " .popsection\n" + " .pushsection __ex_table,\"a\"\n" + " .align 3\n" + " .long 1b, 3b\n" + " .popsection" + : "=&r" (ret), "=&r" (offset) + : "r" (addr), "Qo" (*(unsigned long *)addr)); + + return ret; +} + + +#endif /* DCACHE_WORD_ACCESS */ + #else /* __ARMEB__ */ #include <asm-generic/word-at-a-time.h> #endif |