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-rw-r--r--arch/arm/include/asm/word-at-a-time.h96
1 files changed, 96 insertions, 0 deletions
diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h
new file mode 100644
index 00000000000..4d52f92967a
--- /dev/null
+++ b/arch/arm/include/asm/word-at-a-time.h
@@ -0,0 +1,96 @@
+#ifndef __ASM_ARM_WORD_AT_A_TIME_H
+#define __ASM_ARM_WORD_AT_A_TIME_H
+
+#ifndef __ARMEB__
+
+/*
+ * Little-endian word-at-a-time zero byte handling.
+ * Heavily based on the x86 algorithm.
+ */
+#include <linux/kernel.h>
+
+struct word_at_a_time {
+ const unsigned long one_bits, high_bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
+
+static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
+ const struct word_at_a_time *c)
+{
+ unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
+ *bits = mask;
+ return mask;
+}
+
+#define prep_zero_mask(a, bits, c) (bits)
+
+static inline unsigned long create_zero_mask(unsigned long bits)
+{
+ bits = (bits - 1) & ~bits;
+ return bits >> 7;
+}
+
+static inline unsigned long find_zero(unsigned long mask)
+{
+ unsigned long ret;
+
+#if __LINUX_ARM_ARCH__ >= 5
+ /* We have clz available. */
+ ret = fls(mask) >> 3;
+#else
+ /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
+ ret = (0x0ff0001 + mask) >> 23;
+ /* Fix the 1 for 00 case */
+ ret &= mask;
+#endif
+
+ 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
+
+#endif /* __ASM_ARM_WORD_AT_A_TIME_H */