[PATCH 4.7 141/184] powerpc/32: Fix again csum_partial_copy_generic()

[Greg Kroah-Hartman]

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

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

From: Christophe Leroy <christophe.leroy@xxxxxx>

commit 8540571e01f973d321b0821f4f32ed6e9ae8263c upstream.

Commit 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
based on copy_tofrom_user()") introduced a bug when destination address
is odd and len is lower than cacheline size.

In that case the resulting csum value doesn't have to be rotated one
byte because the cache-aligned copy part is skipped so no alignment
is performed.

Fixes: 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic() based on copy_tofrom_user()")
Cc: stable@xxxxxxxxxxxxxxx # v4.6+
Reported-by: Alessio Igor Bogani <alessio.bogani@xxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
Tested-by: Alessio Igor Bogani <alessio.bogani@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/powerpc/lib/checksum_32.S |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -127,18 +127,19 @@ _GLOBAL(csum_partial_copy_generic)
 	stw	r7,12(r1)
 	stw	r8,8(r1)
 
-	rlwinm	r0,r4,3,0x8
-	rlwnm	r6,r6,r0,0,31	/* odd destination address: rotate one byte */
-	cmplwi	cr7,r0,0	/* is destination address even ? */
 	addic	r12,r6,0
 	addi	r6,r4,-4
 	neg	r0,r4
 	addi	r4,r3,-4
 	andi.	r0,r0,CACHELINE_MASK	/* # bytes to start of cache line */
+	crset	4*cr7+eq
 	beq	58f
 
 	cmplw	0,r5,r0			/* is this more than total to do? */
 	blt	63f			/* if not much to do */
+	rlwinm	r7,r6,3,0x8
+	rlwnm	r12,r12,r7,0,31	/* odd destination address: rotate one byte */
+	cmplwi	cr7,r7,0	/* is destination address even ? */
 	andi.	r8,r0,3			/* get it word-aligned first */
 	mtctr	r8
 	beq+	61f