[PATCH 097/104] powerpc: Fix parameter clobber in csum_partial_copy_generic()

[Kamal Mostafa]

3.8.13.11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Paul E. McKenney" <paulmck at linux.vnet.ibm.com>

commit d9813c3681a36774b254c0cdc9cce53c9e22c756 upstream.

The csum_partial_copy_generic() uses register r7 to adjust the remaining
bytes to process.  Unfortunately, r7 also holds a parameter, namely the
address of the flag to set in case of access exceptions while reading
the source buffer.  Lacking a quantum implementation of PowerPC, this
commit instead uses register r9 to do the adjusting, leaving r7's
pointer uncorrupted.

Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton at samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/powerpc/lib/checksum_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/lib/checksum_64.S b/arch/powerpc/lib/checksum_64.S
index 167f725..609665a 100644
--- a/arch/powerpc/lib/checksum_64.S
+++ b/arch/powerpc/lib/checksum_64.S
@@ -269,8 +269,8 @@ _GLOBAL(csum_partial_copy_generic)
 	rldicl. r6,r3,64-1,64-2		/* r6 = (r3 & 0x3) >> 1 */
 	beq	.Lcopy_aligned
 
-	li	r7,4
-	sub	r6,r7,r6
+	li	r9,4
+	sub	r6,r9,r6
 	mtctr	r6
 
 1:
-- 
1.8.1.2