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>

5 files changed, 48 insertions, 83 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 00b9874e2240..050cb371a69e 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -135,6 +135,8 @@ config PPC
         select GENERIC_CMOS_UPDATE
         select GENERIC_TIME_VSYSCALL
         select GENERIC_CLOCKEVENTS
+        select GENERIC_STRNCPY_FROM_USER
+        select GENERIC_STRNLEN_USER
 
 config EARLY_PRINTK
         bool
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index bd0fb8495154..17bb40cad5bf 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -40,6 +40,8 @@
 
 #define segment_eq(a, b)        ((a).seg == (b).seg)
 
+#define user_addr_max() (get_fs().seg)
+
 #ifdef __powerpc64__
 /*
  * This check is sufficient because there is a large enough
@@ -453,42 +455,9 @@ static inline unsigned long clear_user(void __user *addr, unsigned long size)
         return size;
 }
 
-extern int __strncpy_from_user(char *dst, const char __user *src, long count);
-
-static inline long strncpy_from_user(char *dst, const char __user *src,
-                long count)
-{
-        might_sleep();
-        if (likely(access_ok(VERIFY_READ, src, 1)))
-                return __strncpy_from_user(dst, src, count);
-        return -EFAULT;
-}
-
-/*
- * Return the size of a string (including the ending 0)
- *
- * Return 0 for error
- */
-extern int __strnlen_user(const char __user *str, long len, unsigned long top);
-
-/*
- * Returns the length of the string at str (including the null byte),
- * or 0 if we hit a page we can't access,
- * or something > len if we didn't find a null byte.
- *
- * The `top' parameter to __strnlen_user is to make sure that
- * we can never overflow from the user area into kernel space.
- */
-static inline int strnlen_user(const char __user *str, long len)
-{
-        unsigned long top = current->thread.fs.seg;
-
-        if ((unsigned long)str > top)
-                return 0;
-        return __strnlen_user(str, len, top);
-}
-
-#define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
+extern long strncpy_from_user(char *dst, 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);
 
 #endif  /* __ASSEMBLY__ */
 #endif /* __KERNEL__ */
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 */
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index d1f2aafcbe8c..3e4031581c65 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -85,8 +85,6 @@ EXPORT_SYMBOL(csum_tcpudp_magic);
 
 EXPORT_SYMBOL(__copy_tofrom_user);
 EXPORT_SYMBOL(__clear_user);
-EXPORT_SYMBOL(__strncpy_from_user);
-EXPORT_SYMBOL(__strnlen_user);
 EXPORT_SYMBOL(copy_page);
 
 #if defined(CONFIG_PCI) && defined(CONFIG_PPC32)
diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S
index 455881a5563f..093d6316435c 100644
--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -160,48 +160,3 @@ _GLOBAL(__clear_user)
         PPC_LONG        1b,91b
         PPC_LONG        8b,92b
         .text
-
-_GLOBAL(__strncpy_from_user)
-        addi    r6,r3,-1
-        addi    r4,r4,-1
-        cmpwi   0,r5,0
-        beq     2f
-        mtctr   r5
-1:      lbzu    r0,1(r4)
-        cmpwi   0,r0,0
-        stbu    r0,1(r6)
-        bdnzf   2,1b            /* dec ctr, branch if ctr != 0 && !cr0.eq */
-        beq     3f
-2:      addi    r6,r6,1
-3:      subf    r3,r3,r6
-        blr
-99:     li      r3,-EFAULT
-        blr
-
-        .section __ex_table,"a"
-        PPC_LONG        1b,99b
-        .text
-
-/* r3 = str, r4 = len (> 0), r5 = top (highest addr) */
-_GLOBAL(__strnlen_user)
-        addi    r7,r3,-1
-        subf    r6,r7,r5        /* top+1 - str */
-        cmplw   0,r4,r6
-        bge     0f
-        mr      r6,r4
-0:      mtctr   r6              /* ctr = min(len, top - str) */
-1:      lbzu    r0,1(r7)        /* get next byte */
-        cmpwi   0,r0,0
-        bdnzf   2,1b            /* loop if --ctr != 0 && byte != 0 */
-        addi    r7,r7,1
-        subf    r3,r3,r7        /* number of bytes we have looked at */
-        beqlr                   /* return if we found a 0 byte */
-        cmpw    0,r3,r4         /* did we look at all len bytes? */
-        blt     99f             /* if not, must have hit top */
-        addi    r3,r4,1         /* return len + 1 to indicate no null found */
-        blr
-99:     li      r3,0            /* bad address, return 0 */
-        blr
-
-        .section __ex_table,"a"
-        PPC_LONG        1b,99b