Commit cadc4e1a authored by Stuart Menefy's avatar Stuart Menefy Committed by Paul Mundt
Browse files

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: default avatarStuart Menefy <stuart.menefy@st.com>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 3d22fca7

arch/sh/lib/checksum.S

+50 −19
Original line number Diff line number Diff line
@@ -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
@@ -141,6 +162,16 @@ ENTRY(csum_partial) 
	mov	#0, r0

	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

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