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authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-26 16:57:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-26 16:57:16 -0700
commit1e2aec873ad6d16538512dbb96853caa1fa076af (patch)
treed792b19ac47be44debd24610ae27f1330fa490e4 /include/asm-generic
parentae32adc1e06d096399f195eeda12d443d53539c4 (diff)
parent2c66f623631709aa5f2e4c14c7e089682e7394a3 (diff)
Merge branch 'generic-string-functions'
This makes <asm/word-at-a-time.h> actually live up to its promise of allowing architectures to help tune the string functions that do their work a word at a time. David had already taken the x86 strncpy_from_user() function, modified it to work on sparc, and then done the extra work to make it generically useful. This then expands on that work by making x86 use that generic version, completing the circle. But more importantly, it fixes up the word-at-a-time interfaces so that it's now easy to also support things like strnlen_user(), and pretty much most random string functions. David reports that it all works fine on sparc, and Jonas Bonn reported that an earlier version of this worked on OpenRISC too. It's pretty easy for architectures to add support for this and just replace their private versions with the generic code. * generic-string-functions: sparc: use the new generic strnlen_user() function x86: use the new generic strnlen_user() function lib: add generic strnlen_user() function word-at-a-time: make the interfaces truly generic x86: use generic strncpy_from_user routine
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/word-at-a-time.h52
1 files changed, 52 insertions, 0 deletions
diff --git a/include/asm-generic/word-at-a-time.h b/include/asm-generic/word-at-a-time.h
new file mode 100644
index 00000000000..3f21f1b72e4
--- /dev/null
+++ b/include/asm-generic/word-at-a-time.h
@@ -0,0 +1,52 @@
+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+/*
+ * This says "generic", but it's actually big-endian only.
+ * Little-endian can use more efficient versions of these
+ * interfaces, see for example
+ * arch/x86/include/asm/word-at-a-time.h
+ * for those.
+ */
+
+#include <linux/kernel.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 byte = 0;
+#ifdef CONFIG_64BIT
+ if (mask >> 32)
+ mask >>= 32;
+ else
+ byte = 4;
+#endif
+ if (mask >> 16)
+ mask >>= 16;
+ else
+ byte += 2;
+ return (mask >> 8) ? byte : byte + 1;
+}
+
+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 */