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authorPaul Mackerras <paulus@samba.org>2012-05-28 13:03:47 +1000
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-27 21:00:07 -0700
commit1629372caaaf7ef744d3b983be56b99468a68ff8 (patch)
tree8d3cc2b69ba7b2626b2fe1b3de3ce2a19e45f524 /arch/powerpc/include/asm/word-at-a-time.h
parent69ea6405980f217557b6a58f70ff60d8d88519a5 (diff)
downloadlinux-1629372caaaf7ef744d3b983be56b99468a68ff8.tar.bz2
powerpc: Use the new generic strncpy_from_user() and strnlen_user()
This is much the same as for SPARC except that we can do the find_zero() function more efficiently using the count-leading-zeroes instructions. Tested on 32-bit and 64-bit PowerPC. Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/powerpc/include/asm/word-at-a-time.h')
-rw-r--r--arch/powerpc/include/asm/word-at-a-time.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/word-at-a-time.h b/arch/powerpc/include/asm/word-at-a-time.h
new file mode 100644
index 000000000000..d0b6d4ac6dda
--- /dev/null
+++ b/arch/powerpc/include/asm/word-at-a-time.h
@@ -0,0 +1,41 @@
+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+/*
+ * Word-at-a-time interfaces for PowerPC.
+ */
+
+#include <linux/kernel.h>
+#include <asm/asm-compat.h>
+
+struct word_at_a_time {
+ const unsigned long high_bits, low_bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
+
+/* Bit set in the bytes that have a zero */
+static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
+{
+ unsigned long mask = (val & c->low_bits) + c->low_bits;
+ return ~(mask | rhs);
+}
+
+#define create_zero_mask(mask) (mask)
+
+static inline long find_zero(unsigned long mask)
+{
+ long leading_zero_bits;
+
+ asm (PPC_CNTLZL "%0,%1" : "=r" (leading_zero_bits) : "r" (mask));
+ return leading_zero_bits >> 3;
+}
+
+static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
+{
+ unsigned long rhs = val | c->low_bits;
+ *data = rhs;
+ return (val + c->high_bits) & ~rhs;
+}
+
+#endif /* _ASM_WORD_AT_A_TIME_H */