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linux/arch/sh/lib/checksum.S
Stuart Menefy cadc4e1a2b 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>
2009-01-29 11:56:02 +09:00

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/* $Id: checksum.S,v 1.10 2001/07/06 13:11:32 gniibe Exp $
*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* IP/TCP/UDP checksumming routines
*
* Authors: Jorge Cwik, <jorge@laser.satlink.net>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Tom May, <ftom@netcom.com>
* Pentium Pro/II routines:
* Alexander Kjeldaas <astor@guardian.no>
* Finn Arne Gangstad <finnag@guardian.no>
* Lots of code moved from tcp.c and ip.c; see those files
* for more names.
*
* Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
* handling.
* Andi Kleen, add zeroing on error
* converted to pure assembler
*
* SuperH version: Copyright (C) 1999 Niibe Yutaka
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/errno.h>
#include <linux/linkage.h>
/*
* computes a partial checksum, e.g. for TCP/UDP fragments
*/
/*
* asmlinkage __wsum csum_partial(const void *buf, int len, __wsum sum);
*/
.text
ENTRY(csum_partial)
/*
* Experiments with Ethernet and SLIP connections show that buff
* is aligned on either a 2-byte or 4-byte boundary. We get at
* least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
* Fortunately, it is easy to convert 2-byte alignment to 4-byte
* alignment for the unrolled loop.
*/
mov r4, r0
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.
clrt
bra 6f
add #2, r5 ! r5 was < 2. Deal with it.
1:
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, r1
tst r1, r1
bt/s 4f ! if it's =0, go to 4f
clrt
.align 2
3:
mov.l @r4+, r0
mov.l @r4+, r2
mov.l @r4+, r3
addc r0, r6
mov.l @r4+, r0
addc r2, r6
mov.l @r4+, r2
addc r3, r6
mov.l @r4+, r3
addc r0, r6
mov.l @r4+, r0
addc r2, r6
mov.l @r4+, r2
addc r3, r6
addc r0, r6
addc r2, r6
movt r0
dt r1
bf/s 3b
cmp/eq #1, r0
! here, we know r1==0
addc r1, r6 ! add carry to r6
4:
mov r5, r0
and #0x1c, r0
tst r0, r0
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 r1
bf/s 5b
cmp/eq #1, r0
addc r2, r6
addc r1, r6 ! r1==0 here, so it means add carry-bit
6:
! 3 bytes or less remaining
mov #3, r0
and r0, r5
tst r5, r5
bt 9f ! if it's =0 go to 9f
mov #2, r1
cmp/hs r1, r5
bf 7f
mov.w @r4+, r0
extu.w r0, r0
cmp/eq r1, r5
bt/s 8f
clrt
shll16 r0
addc r0, r6
7:
mov.b @r4+, r0
extu.b r0, r0
#ifndef __LITTLE_ENDIAN__
shll8 r0
#endif
8:
addc r0, r6
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
/*
unsigned int csum_partial_copy_generic (const char *src, char *dst, int len,
int sum, int *src_err_ptr, int *dst_err_ptr)
*/
/*
* Copy from ds while checksumming, otherwise like csum_partial
*
* The macros SRC and DST specify the type of access for the instruction.
* thus we can call a custom exception handler for all access types.
*
* FIXME: could someone double-check whether I haven't mixed up some SRC and
* DST definitions? It's damn hard to trigger all cases. I hope I got
* them all but there's no guarantee.
*/
#define SRC(...) \
9999: __VA_ARGS__ ; \
.section __ex_table, "a"; \
.long 9999b, 6001f ; \
.previous
#define DST(...) \
9999: __VA_ARGS__ ; \
.section __ex_table, "a"; \
.long 9999b, 6002f ; \
.previous
!
! r4: const char *SRC
! r5: char *DST
! r6: int LEN
! r7: int SUM
!
! on stack:
! int *SRC_ERR_PTR
! int *DST_ERR_PTR
!
ENTRY(csum_partial_copy_generic)
mov.l r5,@-r15
mov.l r6,@-r15
mov #3,r0 ! Check src and dest are equally aligned
mov r4,r1
and r0,r1
and r5,r0
cmp/eq r1,r0
bf 3f ! Different alignments, use slow version
tst #1,r0 ! Check dest word aligned
bf 3f ! If not, do it the slow way
mov #2,r0
tst r0,r5 ! Check dest alignment.
bt 2f ! Jump if alignment is ok.
add #-2,r6 ! Alignment uses up two bytes.
cmp/pz r6 ! Jump if we had at least two bytes.
bt/s 1f
clrt
add #2,r6 ! r6 was < 2. Deal with it.
bra 4f
mov r6,r2
3: ! Handle different src and dest alignments.
! This is not common, so simple byte by byte copy will do.
mov r6,r2
shlr r6
tst r6,r6
bt 4f
clrt
.align 2
5:
SRC( mov.b @r4+,r1 )
SRC( mov.b @r4+,r0 )
extu.b r1,r1
DST( mov.b r1,@r5 )
DST( mov.b r0,@(1,r5) )
extu.b r0,r0
add #2,r5
#ifdef __LITTLE_ENDIAN__
shll8 r0
#else
shll8 r1
#endif
or r1,r0
addc r0,r7
movt r0
dt r6
bf/s 5b
cmp/eq #1,r0
mov #0,r0
addc r0, r7
mov r2, r0
tst #1, r0
bt 7f
bra 5f
clrt
! src and dest equally aligned, but to a two byte boundary.
! Handle first two bytes as a special case
.align 2
1:
SRC( mov.w @r4+,r0 )
DST( mov.w r0,@r5 )
add #2,r5
extu.w r0,r0
addc r0,r7
mov #0,r0
addc r0,r7
2:
mov r6,r2
mov #-5,r0
shld r0,r6
tst r6,r6
bt/s 2f
clrt
.align 2
1:
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@r5 )
DST( mov.l r1,@(4,r5) )
addc r1,r7
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@(8,r5) )
DST( mov.l r1,@(12,r5) )
addc r1,r7
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@(16,r5) )
DST( mov.l r1,@(20,r5) )
addc r1,r7
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@(24,r5) )
DST( mov.l r1,@(28,r5) )
addc r1,r7
add #32,r5
movt r0
dt r6
bf/s 1b
cmp/eq #1,r0
mov #0,r0
addc r0,r7
2: mov r2,r6
mov #0x1c,r0
and r0,r6
cmp/pl r6
bf/s 4f
clrt
shlr2 r6
3:
SRC( mov.l @r4+,r0 )
addc r0,r7
DST( mov.l r0,@r5 )
add #4,r5
movt r0
dt r6
bf/s 3b
cmp/eq #1,r0
mov #0,r0
addc r0,r7
4: mov r2,r6
mov #3,r0
and r0,r6
cmp/pl r6
bf 7f
mov #2,r1
cmp/hs r1,r6
bf 5f
SRC( mov.w @r4+,r0 )
DST( mov.w r0,@r5 )
extu.w r0,r0
add #2,r5
cmp/eq r1,r6
bt/s 6f
clrt
shll16 r0
addc r0,r7
5:
SRC( mov.b @r4+,r0 )
DST( mov.b r0,@r5 )
extu.b r0,r0
#ifndef __LITTLE_ENDIAN__
shll8 r0
#endif
6: addc r0,r7
mov #0,r0
addc r0,r7
7:
5000:
# Exception handler:
.section .fixup, "ax"
6001:
mov.l @(8,r15),r0 ! src_err_ptr
mov #-EFAULT,r1
mov.l r1,@r0
! zero the complete destination - computing the rest
! is too much work
mov.l @(4,r15),r5 ! dst
mov.l @r15,r6 ! len
mov #0,r7
1: mov.b r7,@r5
dt r6
bf/s 1b
add #1,r5
mov.l 8000f,r0
jmp @r0
nop
.align 2
8000: .long 5000b
6002:
mov.l @(12,r15),r0 ! dst_err_ptr
mov #-EFAULT,r1
mov.l r1,@r0
mov.l 8001f,r0
jmp @r0
nop
.align 2
8001: .long 5000b
.previous
add #8,r15
rts
mov r7,r0
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