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sh: Handle calling csum_partial with misaligned data 

In rare circumstances csum_partial() can be called with data which is
not 16 or 32 bit aligned. This is been observed with RPC calls for NFS
file systems for example. Add support for handling this without resorting
to the misaligned fixup code (which is why this hasn't been seen as a
problem). This mimics the i386 version, which has had this support for
some time.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Stuart Menefy 2008-12-12 18:34:38 +00:00 committed by Paul Mundt
parent 3d22fca7ab
commit cadc4e1a2b
1 changed files with 50 additions and 19 deletions
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69
arch/sh/lib/checksum.S
View File

@ -36,8 +36,7 @@
*/
/*
* unsigned int csum_partial(const unsigned char *buf, int len,
* unsigned int sum);
* asmlinkage __wsum csum_partial(const void *buf, int len, __wsum sum);
*/
.text
@ -49,11 +48,31 @@ ENTRY(csum_partial)
* Fortunately, it is easy to convert 2-byte alignment to 4-byte
* alignment for the unrolled loop.
*/
mov r5, r1
mov r4, r0
tst #2, r0 ! Check alignment.
bt 2f ! Jump if alignment is ok.
tst #3, r0 ! Check alignment.
bt/s 2f ! Jump if alignment is ok.
mov r4, r7 ! Keep a copy to check for alignment
!
tst #1, r0 ! Check alignment.
bt 21f ! Jump if alignment is boundary of 2bytes.
! buf is odd
tst r5, r5
add #-1, r5
bt 9f
mov.b @r4+, r0
extu.b r0, r0
addc r0, r6 ! t=0 from previous tst
mov r6, r0
shll8 r6
shlr16 r0
shlr8 r0
or r0, r6
mov r4, r0
tst #2, r0
bt 2f
21:
! buf is 2 byte aligned (len could be 0)
add #-2, r5 ! Alignment uses up two bytes.
cmp/pz r5 !
bt/s 1f ! Jump if we had at least two bytes.
@ -61,16 +80,17 @@ ENTRY(csum_partial)
bra 6f
add #2, r5 ! r5 was < 2. Deal with it.
1:
mov r5, r1 ! Save new len for later use.
mov.w @r4+, r0
extu.w r0, r0
addc r0, r6
bf 2f
add #1, r6
2:
! buf is 4 byte aligned (len could be 0)
mov r5, r1
mov #-5, r0
shld r0, r5
tst r5, r5
shld r0, r1
tst r1, r1
bt/s 4f ! if it's =0, go to 4f
clrt
.align 2
@ -92,30 +112,31 @@ ENTRY(csum_partial)
addc r0, r6
addc r2, r6
movt r0
dt r5
dt r1
bf/s 3b
cmp/eq #1, r0
! here, we know r5==0
addc r5, r6 ! add carry to r6
! here, we know r1==0
addc r1, r6 ! add carry to r6
4:
mov r1, r0
mov r5, r0
and #0x1c, r0
tst r0, r0
bt/s 6f
mov r0, r5
shlr2 r5
bt 6f
! 4 bytes or more remaining
mov r0, r1
shlr2 r1
mov #0, r2
5:
addc r2, r6
mov.l @r4+, r2
movt r0
dt r5
dt r1
bf/s 5b
cmp/eq #1, r0
addc r2, r6
addc r5, r6 ! r5==0 here, so it means add carry-bit
addc r1, r6 ! r1==0 here, so it means add carry-bit
6:
mov r1, r5
! 3 bytes or less remaining
mov #3, r0
and r0, r5
tst r5, r5
@ -139,8 +160,18 @@ ENTRY(csum_partial)
8:
addc r0, r6
mov #0, r0
addc r0, r6
addc r0, r6
9:
! Check if the buffer was misaligned, if so realign sum
mov r7, r0
tst #1, r0
bt 10f
mov r6, r0
shll8 r6
shlr16 r0
shlr8 r0
or r0, r6
10:
rts
mov r6, r0