[PATCH 6/7] powerpc/lib: inline more NUL size verifications

[Christophe Leroy]

strncmp(), strncpy(), memchr() are often called with constant
size.

This patch gives GCC a chance to optimise NULL size verification out

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 arch/powerpc/include/asm/string.h | 24 ++++++++++++++++++++++++
 arch/powerpc/lib/string.S         |  8 ++++++++
 2 files changed, 32 insertions(+)

diff --git a/arch/powerpc/include/asm/string.h 
b/arch/powerpc/include/asm/string.h
index 196ac5d587fb..1465d5629ef2 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -30,6 +30,22 @@ extern void * memchr(const void *,int,__kernel_size_t);
 extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
 
 #ifndef CONFIG_FORTIFY_SOURCE
+static inline char *__strncpy(char *p, const char *q, __kernel_size_t size)
+{
+       if (unlikely(!size))
+               return p;
+       return strncpy(p, q, size);
+}
+#define strncpy __strncpy
+
+static inline int __strncmp(const char *p, const char *q, __kernel_size_t size)
+{
+       if (unlikely(!size))
+               return 0;
+       return strncmp(p, q, size);
+}
+#define strncmp __strncmp
+
 static inline int ___memcmp(const void *p,const void *q,__kernel_size_t size, 
int offset)
 {
        int dif;
@@ -72,6 +88,14 @@ static inline int __memcmp(const void *p,const void 
*q,__kernel_size_t size)
        return memcmp(p, q, size);
 }
 #define memcmp __memcmp
+
+static inline void *__memchr(const void *p, int c, __kernel_size_t size)
+{
+       if (unlikely(!size))
+               return NULL;
+       return memchr(p, c, size);
+}
+#define memchr __memchr
 #endif
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S
index cbb90fdc672d..89af53b08b4a 100644
--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -18,8 +18,10 @@
 /* This clears out any unused part of the destination buffer,
    just as the libc version does.  -- paulus */
 _GLOBAL(strncpy)
+#ifdef CONFIG_FORTIFY_SOURCE
        PPC_LCMPI 0,r5,0
        beqlr
+#endif
        mtctr   r5
        addi    r6,r3,-1
        addi    r4,r4,-1
@@ -38,8 +40,10 @@ _GLOBAL(strncpy)
 EXPORT_SYMBOL(strncpy)
 
 _GLOBAL(strncmp)
+#ifdef CONFIG_FORTIFY_SOURCE
        PPC_LCMPI 0,r5,0
        beq-    2f
+#endif
        mtctr   r5
        addi    r5,r3,-1
        addi    r4,r4,-1
@@ -51,13 +55,17 @@ _GLOBAL(strncmp)
        beqlr   1
        bdnzt   eq,1b
        blr
+#ifdef CONFIG_FORTIFY_SOURCE
 2:     li      r3,0
        blr
+#endif
 EXPORT_SYMBOL(strncmp)
 
 _GLOBAL(memchr)
+#ifdef CONFIG_FORTIFY_SOURCE
        PPC_LCMPI 0,r5,0
        beq-    2f
+#endif
        mtctr   r5
        addi    r3,r3,-1
        .balign 16
-- 
2.13.3