Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Work-around an obscure bug (reported by a couple of people, and reproduced 

exactly twice by me) which causes the code at the top of copyin which
word-aligns the destination pointer to copy more bytes than necessary,
resulting in an alignment fault later on.

The bug is difficult to reproduce, but as far as I can tell it seems
to be as a result of the condition codes being corrupted, possibly
following a page fault caused by the first ldrbt/strb instructions.
The subsequent ldr<cc>bt/str<cc>b instructions then _always_ execute.
I can't think of any obvious reason why this would happen, though.
This commit is contained in:
scw 2003-12-15 09:27:18 +00:00
parent fbdf861fac
commit 5f0d6f1b24
1 changed files with 54 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

101
sys/arch/arm/arm/bcopyinout_xscale.S
View File

@ -1,4 +1,4 @@
/* $NetBSD: bcopyinout_xscale.S,v 1.2 2003/10/23 09:11:35 scw Exp $ */
/* $NetBSD: bcopyinout_xscale.S,v 1.3 2003/12/15 09:27:18 scw Exp $ */
/*
* Copyright 2003 Wasabi Systems, Inc.
@ -35,7 +35,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
RCSID("$NetBSD: bcopyinout_xscale.S,v 1.2 2003/10/23 09:11:35 scw Exp $")
RCSID("$NetBSD: bcopyinout_xscale.S,v 1.3 2003/12/15 09:27:18 scw Exp $")
.text
.align 0
@ -57,8 +57,8 @@ RCSID("$NetBSD: bcopyinout_xscale.S,v 1.2 2003/10/23 09:11:35 scw Exp $")
*/
ENTRY(copyin)
cmp r2, #0x00
moveq r0, #0x00
moveq pc, lr /* Bail early if length is zero */
movle r0, #0x00
movle pc, lr /* Bail early if length is <= 0 */
stmfd sp!, {r10-r11, lr}
@ -99,16 +99,16 @@ ENTRY(copyin)
rsb ip, ip, #0x04
cmp r2, ip /* Enough bytes left to align it? */
blt .Lcopyin_l4_2 /* Nope. Just copy bytewise */
cmp ip, #0x02
sub r2, r2, ip
rsbs ip, ip, #0x03
addne pc, pc, ip, lsl #3
nop
ldrbt ip, [r0], #0x01
strb ip, [r1], #0x01
ldrbt ip, [r0], #0x01
strb ip, [r1], #0x01
ldrbt ip, [r0], #0x01
sub r2, r2, #0x01
strb ip, [r1], #0x01
ldrgebt ip, [r0], #0x01
subge r2, r2, #0x01
strgeb ip, [r1], #0x01
ldrgtbt ip, [r0], #0x01
subgt r2, r2, #0x01
strgtb ip, [r1], #0x01
cmp r2, #0x00 /* All done? */
moveq pc, lr
@ -124,6 +124,7 @@ ENTRY(copyin)
ldrnet ip, [r0], #0x04
stmfd sp!, {r4-r9} /* Free up some registers */
mov r3, #-1 /* Signal restore r4-r9 */
tst r1, #0x07 /* XXX: bug work-around */
subne r2, r2, #0x04
strne ip, [r1], #0x04
@ -465,13 +466,15 @@ ENTRY(copyin)
adds r2, r2, #0x04
moveq pc, lr
.Lcopyin_l4_2:
rsbs r2, r2, #0x03
addne pc, pc, r2, lsl #3
nop
ldrbt ip, [r0], #0x01
cmp r2, #0x02
ldrgebt r2, [r0], #0x01
strb ip, [r1], #0x01
ldrgtbt ip, [r0]
strgeb r2, [r1], #0x01
strgtb ip, [r1]
ldrbt ip, [r0], #0x01
strb ip, [r1], #0x01
ldrbt ip, [r0]
strb ip, [r1]
mov pc, lr
@ -484,8 +487,8 @@ ENTRY(copyin)
*/
ENTRY(copyout)
cmp r2, #0x00
moveq r0, #0x00
moveq pc, lr /* Bail early if length is zero */
movle r0, #0x00
movle pc, lr /* Bail early if length is <= 0 */
stmfd sp!, {r10-r11, lr}
@ -526,16 +529,16 @@ ENTRY(copyout)
rsb ip, ip, #0x04
cmp r2, ip /* Enough bytes left to align it? */
blt .Lcopyout_l4_2 /* Nope. Just copy bytewise */
cmp ip, #0x02
sub r2, r2, ip
rsbs ip, ip, #0x03
addne pc, pc, ip, lsl #3
nop
ldrb ip, [r0], #0x01
strbt ip, [r1], #0x01
ldrb ip, [r0], #0x01
strbt ip, [r1], #0x01
ldrb ip, [r0], #0x01
sub r2, r2, #0x01
strbt ip, [r1], #0x01
ldrgeb ip, [r0], #0x01
subge r2, r2, #0x01
strgebt ip, [r1], #0x01
ldrgtb ip, [r0], #0x01
subgt r2, r2, #0x01
strgtbt ip, [r1], #0x01
cmp r2, #0x00 /* All done? */
moveq pc, lr
@ -551,6 +554,7 @@ ENTRY(copyout)
ldrne ip, [r0], #0x04
stmfd sp!, {r4-r9} /* Free up some registers */
mov r3, #-1 /* Signal restore r4-r9 */
tst r1, #0x07 /* XXX: bug work-around */
subne r2, r2, #0x04
strnet ip, [r1], #0x04
@ -912,13 +916,15 @@ ENTRY(copyout)
adds r2, r2, #0x04
moveq pc, lr
.Lcopyout_l4_2:
rsbs r2, r2, #0x03
addne pc, pc, r2, lsl #3
nop
ldrb ip, [r0], #0x01
cmp r2, #0x02
ldrgeb r2, [r0], #0x01
strbt ip, [r1], #0x01
ldrgtb ip, [r0]
strgebt r2, [r1], #0x01
strgtbt ip, [r1]
ldrb ip, [r0], #0x01
strbt ip, [r1], #0x01
ldrb ip, [r0]
strbt ip, [r1]
mov pc, lr
@ -931,8 +937,8 @@ ENTRY(copyout)
*/
ENTRY(kcopy)
cmp r2, #0x00
moveq r0, #0x00
moveq pc, lr /* Bail early if length is zero */
movle r0, #0x00
movle pc, lr /* Bail early if length is <= 0 */
stmfd sp!, {r10-r11, lr}
@ -973,16 +979,15 @@ ENTRY(kcopy)
rsb ip, ip, #0x04
cmp r2, ip /* Enough bytes left to align it? */
blt .Lkcopy_bad_endgame2 /* Nope. Just copy bytewise */
cmp ip, #0x02
sub r2, r2, ip
rsbs ip, ip, #0x03
addne pc, pc, ip, lsl #3
ldrb ip, [r0], #0x01
strb ip, [r1], #0x01
ldrb ip, [r0], #0x01
strb ip, [r1], #0x01
ldrb ip, [r0], #0x01
sub r2, r2, #0x01
strb ip, [r1], #0x01
ldrgeb ip, [r0], #0x01
subge r2, r2, #0x01
strgeb ip, [r1], #0x01
ldrgtb ip, [r0], #0x01
subgt r2, r2, #0x01
strgtb ip, [r1], #0x01
cmp r2, #0x00 /* All done? */
moveq pc, lr
@ -1339,11 +1344,13 @@ ENTRY(kcopy)
adds r2, r2, #0x04
moveq pc, lr
.Lkcopy_bad_endgame2:
rsbs r2, r2, #0x03
addne pc, pc, r2, lsl #3
nop
ldrb ip, [r0], #0x01
cmp r2, #0x02
ldrgeb r2, [r0], #0x01
strb ip, [r1], #0x01
ldrgtb ip, [r0]
strgeb r2, [r1], #0x01
strgtb ip, [r1]
ldrb ip, [r0], #0x01
strb ip, [r1], #0x01
ldrb ip, [r0]
strb ip, [r1]
mov pc, lr