commit 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
based on copy_tofrom_user()") introduced a bug when destination
address is odd and initial csum is not null
In that (rare) case the initial csum value has to be rotated one byte
as well as the resulting value is
This patch also fixes related comments
Fixes: 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
based on copy_tofrom_user()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
v2: updated comments as suggested by Segher
arch/powerpc/lib/checksum_32.S | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index d90870a..0a57fe6 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -127,8 +127,9 @@ _GLOBAL(csum_partial_copy_generic)
stw r7,12(r1)
stw r8,8(r1)
- andi. r0,r4,1 /* is destination address even ? */
- cmplwi cr7,r0,0
+ 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
@@ -237,7 +238,7 @@ _GLOBAL(csum_partial_copy_generic)
66: addze r3,r12
addi r1,r1,16
beqlr+ cr7
- rlwinm r3,r3,8,0,31 /* swap bytes for odd destination */
+ rlwinm r3,r3,8,0,31 /* odd destination address: rotate one byte */
blr
/* read fault */
--
2.1.0
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