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authorWill Deacon <will.deacon@arm.com>2013-11-06 19:32:13 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2013-12-19 17:43:08 +0000
commit7bc13fd33adb9536bd73965cd46bbf7377df097c (patch)
tree7b394763246d3362bc40836bf31f17069f5d6ab8 /arch/arm64
parentarm64: futex: ensure .fixup entries are sufficiently aligned (diff)
downloadlinux-dev-7bc13fd33adb9536bd73965cd46bbf7377df097c.tar.xz
linux-dev-7bc13fd33adb9536bd73965cd46bbf7377df097c.zip
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: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/Kconfig1
-rw-r--r--arch/arm64/include/asm/word-at-a-time.h40
2 files changed, 41 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 295bf2de7128..435c9bc1c86c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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
diff --git a/arch/arm64/include/asm/word-at-a-time.h b/arch/arm64/include/asm/word-at-a-time.h
index 27a167d044d9..aab5bf09e9d9 100644
--- a/arch/arm64/include/asm/word-at-a-time.h
+++ b/arch/arm64/include/asm/word-at-a-time.h
@@ -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 */