linux/arch/arm/lib/csumpartialcopygeneric.S
Catalin Marinas 90303b1023 [ARM] 3256/1: Make the function-returning ldm's use sp as the base register
Patch from Catalin Marinas

If the low interrupt latency mode is enabled for the CPU (from ARMv6
onwards), the ldm/stm instructions are no longer atomic. An ldm instruction
restoring the sp and pc registers can be interrupted immediately after sp
was updated but before the pc. If this happens, the CPU restores the base
register to the value before the ldm instruction but if the base register
is not sp, the interrupt routine will corrupt the stack and the restarted
ldm instruction will load garbage.

Note that future ARM cores might always run in the low interrupt latency
mode.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-12 16:53:51 +00:00

331 lines
6.7 KiB
ArmAsm

/*
* linux/arch/arm/lib/csumpartialcopygeneric.S
*
* Copyright (C) 1995-2001 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
/*
* unsigned int
* csum_partial_copy_xxx(const char *src, char *dst, int len, int sum, )
* r0 = src, r1 = dst, r2 = len, r3 = sum
* Returns : r0 = checksum
*
* Note that 'tst' and 'teq' preserve the carry flag.
*/
src .req r0
dst .req r1
len .req r2
sum .req r3
.Lzero: mov r0, sum
load_regs
/*
* Align an unaligned destination pointer. We know that
* we have >= 8 bytes here, so we don't need to check
* the length. Note that the source pointer hasn't been
* aligned yet.
*/
.Ldst_unaligned:
tst dst, #1
beq .Ldst_16bit
load1b ip
sub len, len, #1
adcs sum, sum, ip, put_byte_1 @ update checksum
strb ip, [dst], #1
tst dst, #2
moveq pc, lr @ dst is now 32bit aligned
.Ldst_16bit: load2b r8, ip
sub len, len, #2
adcs sum, sum, r8, put_byte_0
strb r8, [dst], #1
adcs sum, sum, ip, put_byte_1
strb ip, [dst], #1
mov pc, lr @ dst is now 32bit aligned
/*
* Handle 0 to 7 bytes, with any alignment of source and
* destination pointers. Note that when we get here, C = 0
*/
.Lless8: teq len, #0 @ check for zero count
beq .Lzero
/* we must have at least one byte. */
tst dst, #1 @ dst 16-bit aligned
beq .Lless8_aligned
/* Align dst */
load1b ip
sub len, len, #1
adcs sum, sum, ip, put_byte_1 @ update checksum
strb ip, [dst], #1
tst len, #6
beq .Lless8_byteonly
1: load2b r8, ip
sub len, len, #2
adcs sum, sum, r8, put_byte_0
strb r8, [dst], #1
adcs sum, sum, ip, put_byte_1
strb ip, [dst], #1
.Lless8_aligned:
tst len, #6
bne 1b
.Lless8_byteonly:
tst len, #1
beq .Ldone
load1b r8
adcs sum, sum, r8, put_byte_0 @ update checksum
strb r8, [dst], #1
b .Ldone
FN_ENTRY
save_regs
cmp len, #8 @ Ensure that we have at least
blo .Lless8 @ 8 bytes to copy.
adds sum, sum, #0 @ C = 0
tst dst, #3 @ Test destination alignment
blne .Ldst_unaligned @ align destination, return here
/*
* Ok, the dst pointer is now 32bit aligned, and we know
* that we must have more than 4 bytes to copy. Note
* that C contains the carry from the dst alignment above.
*/
tst src, #3 @ Test source alignment
bne .Lsrc_not_aligned
/* Routine for src & dst aligned */
bics ip, len, #15
beq 2f
1: load4l r4, r5, r6, r7
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r4, r5
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
tst ip, #4
beq 4f
3: load1l r4
str r4, [dst], #4
adcs sum, sum, r4
4: ands len, len, #3
beq .Ldone
load1l r4
tst len, #2
mov r5, r4, get_byte_0
beq .Lexit
adcs sum, sum, r4, push #16
strb r5, [dst], #1
mov r5, r4, get_byte_1
strb r5, [dst], #1
mov r5, r4, get_byte_2
.Lexit: tst len, #1
strneb r5, [dst], #1
andne r5, r5, #255
adcnes sum, sum, r5, put_byte_0
/*
* If the dst pointer was not 16-bit aligned, we
* need to rotate the checksum here to get around
* the inefficient byte manipulations in the
* architecture independent code.
*/
.Ldone: adc r0, sum, #0
ldr sum, [sp, #0] @ dst
tst sum, #1
movne r0, r0, ror #8
load_regs
.Lsrc_not_aligned:
adc sum, sum, #0 @ include C from dst alignment
and ip, src, #3
bic src, src, #3
load1l r5
cmp ip, #2
beq .Lsrc2_aligned
bhi .Lsrc3_aligned
mov r4, r5, pull #8 @ C = 0
bics ip, len, #15
beq 2f
1: load4l r5, r6, r7, r8
orr r4, r4, r5, push #24
mov r5, r5, pull #8
orr r5, r5, r6, push #24
mov r6, r6, pull #8
orr r6, r6, r7, push #24
mov r7, r7, pull #8
orr r7, r7, r8, push #24
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
mov r4, r8, pull #8
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r5, r6
orr r4, r4, r5, push #24
mov r5, r5, pull #8
orr r5, r5, r6, push #24
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
mov r4, r6, pull #8
tst ip, #4
beq 4f
3: load1l r5
orr r4, r4, r5, push #24
str r4, [dst], #4
adcs sum, sum, r4
mov r4, r5, pull #8
4: ands len, len, #3
beq .Ldone
mov r5, r4, get_byte_0
tst len, #2
beq .Lexit
adcs sum, sum, r4, push #16
strb r5, [dst], #1
mov r5, r4, get_byte_1
strb r5, [dst], #1
mov r5, r4, get_byte_2
b .Lexit
.Lsrc2_aligned: mov r4, r5, pull #16
adds sum, sum, #0
bics ip, len, #15
beq 2f
1: load4l r5, r6, r7, r8
orr r4, r4, r5, push #16
mov r5, r5, pull #16
orr r5, r5, r6, push #16
mov r6, r6, pull #16
orr r6, r6, r7, push #16
mov r7, r7, pull #16
orr r7, r7, r8, push #16
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
mov r4, r8, pull #16
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r5, r6
orr r4, r4, r5, push #16
mov r5, r5, pull #16
orr r5, r5, r6, push #16
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
mov r4, r6, pull #16
tst ip, #4
beq 4f
3: load1l r5
orr r4, r4, r5, push #16
str r4, [dst], #4
adcs sum, sum, r4
mov r4, r5, pull #16
4: ands len, len, #3
beq .Ldone
mov r5, r4, get_byte_0
tst len, #2
beq .Lexit
adcs sum, sum, r4
strb r5, [dst], #1
mov r5, r4, get_byte_1
strb r5, [dst], #1
tst len, #1
beq .Ldone
load1b r5
b .Lexit
.Lsrc3_aligned: mov r4, r5, pull #24
adds sum, sum, #0
bics ip, len, #15
beq 2f
1: load4l r5, r6, r7, r8
orr r4, r4, r5, push #8
mov r5, r5, pull #24
orr r5, r5, r6, push #8
mov r6, r6, pull #24
orr r6, r6, r7, push #8
mov r7, r7, pull #24
orr r7, r7, r8, push #8
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
mov r4, r8, pull #24
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r5, r6
orr r4, r4, r5, push #8
mov r5, r5, pull #24
orr r5, r5, r6, push #8
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
mov r4, r6, pull #24
tst ip, #4
beq 4f
3: load1l r5
orr r4, r4, r5, push #8
str r4, [dst], #4
adcs sum, sum, r4
mov r4, r5, pull #24
4: ands len, len, #3
beq .Ldone
mov r5, r4, get_byte_0
tst len, #2
beq .Lexit
strb r5, [dst], #1
adcs sum, sum, r4
load1l r4
mov r5, r4, get_byte_0
strb r5, [dst], #1
adcs sum, sum, r4, push #24
mov r5, r4, get_byte_1
b .Lexit