powerpc: Fix boot wrapper memcmp() called with zero length argument

I noticed, when trying to use, e.g.,
node = find_node_by_prop_value(prev, "booleanprop", "", 0))
to search for all nodes with a certain boolean property, that memcmp()
returns garbage when comparing zero bytes.  It should return zero.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/powerpc/boot/string.S b/arch/powerpc/boot/string.S
index 643e4cb2f11d..acc9428f2789 100644
--- a/arch/powerpc/boot/string.S
+++ b/arch/powerpc/boot/string.S
@@ -235,7 +235,7 @@ memchr:
         .globl  memcmp
 memcmp:
         cmpwi   0,r5,0
-        blelr
+        ble     2f
         mtctr   r5
         addi    r6,r3,-1
         addi    r4,r4,-1
@@ -244,6 +244,8 @@ memcmp:
         subf.   r3,r0,r3
         bdnzt   2,1b
         blr
+2:      li      r3,0
+        blr
 
 
 /*