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

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 000000000000..3f21f1b72e45
--- /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 */