alpha: Use new generic strncpy_from_user() and strnlen_user()
Similar to x86/sparc/powerpc implementations except:
1) we implement an extremely efficient has_zero()/find_zero()
sequence with both prep_zero_mask() and create_zero_mask()
no-operations.
2) Our output from prep_zero_mask() differs in that only the
lowest eight bits are used to represent the zero bytes
nevertheless it can be safely ORed with other similar masks
from prep_zero_mask() and forms input to create_zero_mask(),
the two fundamental properties prep_zero_mask() must satisfy.
Tests on EV67 and EV68 CPUs revealed that the generic code is
essentially as fast (to within 0.5% of CPU cycles) of the old
Alpha specific code for large quadword-aligned strings, despite
the 30% extra CPU instructions executed. In contrast, the
generic code for unaligned strings is substantially slower (by
more than a factor of 3) than the old Alpha specific code.
Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Acked-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index b49ec2f..766fdfd 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -433,36 +433,12 @@
#undef __module_address
#undef __module_call
-/* Returns: -EFAULT if exception before terminator, N if the entire
- buffer filled, else strlen. */
+#define user_addr_max() \
+ (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
-extern long __strncpy_from_user(char *__to, const char __user *__from, long __to_len);
-
-extern inline long
-strncpy_from_user(char *to, const char __user *from, long n)
-{
- long ret = -EFAULT;
- if (__access_ok((unsigned long)from, 0, get_fs()))
- ret = __strncpy_from_user(to, from, n);
- return ret;
-}
-
-/* Returns: 0 if bad, string length+1 (memory size) of string if ok */
-extern long __strlen_user(const char __user *);
-
-extern inline long strlen_user(const char __user *str)
-{
- return access_ok(VERIFY_READ,str,0) ? __strlen_user(str) : 0;
-}
-
-/* Returns: 0 if exception before NUL or reaching the supplied limit (N),
- * a value greater than N if the limit would be exceeded, else strlen. */
-extern long __strnlen_user(const char __user *, long);
-
-extern inline long strnlen_user(const char __user *str, long n)
-{
- return access_ok(VERIFY_READ,str,0) ? __strnlen_user(str, n) : 0;
-}
+extern long strncpy_from_user(char *dest, const char __user *src, long count);
+extern __must_check long strlen_user(const char __user *str);
+extern __must_check long strnlen_user(const char __user *str, long n);
/*
* About the exception table:
diff --git a/arch/alpha/include/asm/word-at-a-time.h b/arch/alpha/include/asm/word-at-a-time.h
new file mode 100644
index 0000000..6b340d0
--- /dev/null
+++ b/arch/alpha/include/asm/word-at-a-time.h
@@ -0,0 +1,55 @@
+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+#include <asm/compiler.h>
+
+/*
+ * word-at-a-time interface for Alpha.
+ */
+
+/*
+ * We do not use the word_at_a_time struct on Alpha, but it needs to be
+ * implemented to humour the generic code.
+ */
+struct word_at_a_time {
+ const unsigned long unused;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { 0 }
+
+/* Return nonzero if val has a zero */
+static inline unsigned long has_zero(unsigned long val, unsigned long *bits, const struct word_at_a_time *c)
+{
+ unsigned long zero_locations = __kernel_cmpbge(0, val);
+ *bits = zero_locations;
+ return zero_locations;
+}
+
+static inline unsigned long prep_zero_mask(unsigned long val, unsigned long bits, const struct word_at_a_time *c)
+{
+ return bits;
+}
+
+#define create_zero_mask(bits) (bits)
+
+static inline unsigned long find_zero(unsigned long bits)
+{
+#if defined(CONFIG_ALPHA_EV6) && defined(CONFIG_ALPHA_EV67)
+ /* Simple if have CIX instructions */
+ return __kernel_cttz(bits);
+#else
+ unsigned long t1, t2, t3;
+ /* Retain lowest set bit only */
+ bits &= -bits;
+ /* Binary search for lowest set bit */
+ t1 = bits & 0xf0;
+ t2 = bits & 0xcc;
+ t3 = bits & 0xaa;
+ if (t1) t1 = 4;
+ if (t2) t2 = 2;
+ if (t3) t3 = 1;
+ return t1 + t2 + t3;
+#endif
+}
+
+#endif /* _ASM_WORD_AT_A_TIME_H */