From: Greg KH on
2.6.33-stable review patch. If anyone has any objections, please let me know.


From: Jeff Mahoney <jeffm(a)>

commit 637a99022fb119b90fb281715d13172f0394fc12 upstream.

Commit 0119536c, which added the assembly version of strncmp to
powerpc, mentions that it adds two instructions to the version from
boot/string.S to allow it to handle len=0. Unfortunately, it doesn't
always return 0 when that is the case. The length is passed in r5, but
the return value is passed back in r3. In certain cases, this will
happen to work. Otherwise it will pass back the address of the first
string as the return value.

This patch lifts the len <= 0 handling code from memcpy to handle that

Reported by: Christian_Sellars(a)
Signed-off-by: Jeff Mahoney <jeffm(a)>
Signed-off-by: Benjamin Herrenschmidt <benh(a)>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)>

arch/powerpc/lib/string.S | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -71,7 +71,7 @@ _GLOBAL(strcmp)

- beqlr
+ ble- 2f
mtctr r5
addi r5,r3,-1
addi r4,r4,-1
@@ -82,6 +82,8 @@ _GLOBAL(strncmp)
beqlr 1
bdnzt eq,1b
+2: li r3,0
+ blr

addi r4,r3,-1

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