Hello !
New (since test12) optimized memmove function seems to be broken
on alpha platform.
If dest and src arguments are misaligned, new memmove does wrong things.
example:
static char p[] = "abcdefghijklmnopkrstuvwxyz01234567890";
memmove(p + 2, p + 13, 17);
printk ("DEBUG: memmove test: %s\n", p);
produces:
DEBUG: memmove test: abyz0123tuvwxyz0123tuvwxyz01234567890
Old memmove variant didn't have this problem.
Thanks,
Alex.
On Wed, Dec 20, 2000 at 10:03:42PM +0300, Alexander Zarochentcev wrote:
> New (since test12) optimized memmove function seems to be broken
> on alpha platform.
Indeed it is.
> If dest and src arguments are misaligned, new memmove does wrong things.
Actually it broke when dest < src. Incrementing pointers should be used in
this case.
This patch seems to work (tested in userspace).
Ivan.
--- linux/arch/alpha/lib/memmove.S.orig Tue Dec 12 00:46:26 2000
+++ linux/arch/alpha/lib/memmove.S Thu Dec 21 18:32:59 2000
@@ -26,12 +26,16 @@ memmove:
bne $1,memcpy
and $2,7,$2 /* Test for src/dest co-alignment. */
- bne $2,$misaligned
+ and $16,7,$1
+ cmpule $16,$17,$3
+ bne $3,$memmove_up /* dest < src */
and $4,7,$1
- beq $1,$skip_aligned_byte_loop_head
+ bne $2,$misaligned_dn
+ unop
+ beq $1,$skip_aligned_byte_loop_head_dn
-$aligned_byte_loop_head:
+$aligned_byte_loop_head_dn:
lda $4,-1($4)
lda $5,-1($5)
unop
@@ -48,13 +52,13 @@ $aligned_byte_loop_head:
and $4,7,$6
stq_u $1,0($4)
- bne $6,$aligned_byte_loop_head
+ bne $6,$aligned_byte_loop_head_dn
-$skip_aligned_byte_loop_head:
+$skip_aligned_byte_loop_head_dn:
lda $18,-8($18)
- blt $18,$skip_aligned_word_loop
+ blt $18,$skip_aligned_word_loop_dn
-$aligned_word_loop:
+$aligned_word_loop_dn:
ldq $1,-8($5)
nop
lda $5,-8($5)
@@ -63,22 +67,22 @@ $aligned_word_loop:
stq $1,-8($4)
nop
lda $4,-8($4)
- bge $18,$aligned_word_loop
+ bge $18,$aligned_word_loop_dn
-$skip_aligned_word_loop:
+$skip_aligned_word_loop_dn:
lda $18,8($18)
- bgt $18,$byte_loop_tail
+ bgt $18,$byte_loop_tail_dn
unop
ret $31,($26),1
.align 4
-$misaligned:
+$misaligned_dn:
nop
fnop
unop
beq $18,$egress
-$byte_loop_tail:
+$byte_loop_tail_dn:
ldq_u $3,-1($5)
ldq_u $2,-1($4)
lda $5,-1($5)
@@ -91,8 +95,77 @@ $byte_loop_tail:
bis $1,$2,$1
stq_u $1,0($4)
+ bgt $18,$byte_loop_tail_dn
+ br $egress
+
+$memmove_up:
+ mov $16,$4
+ mov $17,$5
+ bne $2,$misaligned_up
+ beq $1,$skip_aligned_byte_loop_head_up
+
+$aligned_byte_loop_head_up:
+ unop
+ ble $18,$egress
+ ldq_u $3,0($5)
+ ldq_u $2,0($4)
+
+ lda $18,-1($18)
+ extbl $3,$5,$1
+ insbl $1,$4,$1
+ mskbl $2,$4,$2
+
+ bis $1,$2,$1
+ lda $5,1($5)
+ stq_u $1,0($4)
+ lda $4,1($4)
+
+ and $4,7,$6
+ bne $6,$aligned_byte_loop_head_up
+
+$skip_aligned_byte_loop_head_up:
+ lda $18,-8($18)
+ blt $18,$skip_aligned_word_loop_up
+
+$aligned_word_loop_up:
+ ldq $1,0($5)
+ nop
+ lda $5,8($5)
+ lda $18,-8($18)
+
+ stq $1,0($4)
+ nop
+ lda $4,8($4)
+ bge $18,$aligned_word_loop_up
+
+$skip_aligned_word_loop_up:
+ lda $18,8($18)
+ bgt $18,$byte_loop_tail_up
+ unop
+ ret $31,($26),1
+
+ .align 4
+$misaligned_up:
+ nop
+ fnop
+ unop
+ beq $18,$egress
+
+$byte_loop_tail_up:
+ ldq_u $3,0($5)
+ ldq_u $2,0($4)
+ lda $18,-1($18)
+ extbl $3,$5,$1
+
+ insbl $1,$4,$1
+ mskbl $2,$4,$2
+ bis $1,$2,$1
+ stq_u $1,0($4)
+
+ lda $5,1($5)
+ lda $4,1($4)
nop
- bgt $18,$byte_loop_tail
+ bgt $18,$byte_loop_tail_up
$egress:
ret $31,($26),1
On Thu, Dec 21, 2000 at 06:40:46PM +0300, Ivan Kokshaysky wrote:
> On Wed, Dec 20, 2000 at 10:03:42PM +0300, Alexander Zarochentcev wrote:
> > New (since test12) optimized memmove function seems to be broken
> > on alpha platform.
>
> Indeed it is.
>
> > If dest and src arguments are misaligned, new memmove does wrong things.
>
> Actually it broke when dest < src. Incrementing pointers should be used in
> this case.
>
> This patch seems to work (tested in userspace).
>
> Ivan.
>
> --- linux/arch/alpha/lib/memmove.S.orig Tue Dec 12 00:46:26 2000
> +++ linux/arch/alpha/lib/memmove.S Thu Dec 21 18:32:59 2000
> @@ -26,12 +26,16 @@ memmove:
> bne $1,memcpy
>
> and $2,7,$2 /* Test for src/dest co-alignment. */
> - bne $2,$misaligned
> + and $16,7,$1
> + cmpule $16,$17,$3
> + bne $3,$memmove_up /* dest < src */
>
> and $4,7,$1
> - beq $1,$skip_aligned_byte_loop_head
> + bne $2,$misaligned_dn
> + unop
> + beq $1,$skip_aligned_byte_loop_head_dn
>
> -$aligned_byte_loop_head:
> +$aligned_byte_loop_head_dn:
> lda $4,-1($4)
> lda $5,-1($5)
> unop
> @@ -48,13 +52,13 @@ $aligned_byte_loop_head:
> and $4,7,$6
>
> stq_u $1,0($4)
> - bne $6,$aligned_byte_loop_head
> + bne $6,$aligned_byte_loop_head_dn
>
> -$skip_aligned_byte_loop_head:
> +$skip_aligned_byte_loop_head_dn:
> lda $18,-8($18)
> - blt $18,$skip_aligned_word_loop
> + blt $18,$skip_aligned_word_loop_dn
>
> -$aligned_word_loop:
> +$aligned_word_loop_dn:
> ldq $1,-8($5)
> nop
> lda $5,-8($5)
> @@ -63,22 +67,22 @@ $aligned_word_loop:
> stq $1,-8($4)
> nop
> lda $4,-8($4)
> - bge $18,$aligned_word_loop
> + bge $18,$aligned_word_loop_dn
>
> -$skip_aligned_word_loop:
> +$skip_aligned_word_loop_dn:
> lda $18,8($18)
> - bgt $18,$byte_loop_tail
> + bgt $18,$byte_loop_tail_dn
> unop
> ret $31,($26),1
>
> .align 4
> -$misaligned:
> +$misaligned_dn:
> nop
> fnop
> unop
> beq $18,$egress
>
> -$byte_loop_tail:
> +$byte_loop_tail_dn:
> ldq_u $3,-1($5)
> ldq_u $2,-1($4)
> lda $5,-1($5)
> @@ -91,8 +95,77 @@ $byte_loop_tail:
>
> bis $1,$2,$1
> stq_u $1,0($4)
> + bgt $18,$byte_loop_tail_dn
> + br $egress
> +
> +$memmove_up:
> + mov $16,$4
> + mov $17,$5
> + bne $2,$misaligned_up
> + beq $1,$skip_aligned_byte_loop_head_up
> +
> +$aligned_byte_loop_head_up:
> + unop
> + ble $18,$egress
> + ldq_u $3,0($5)
> + ldq_u $2,0($4)
> +
> + lda $18,-1($18)
> + extbl $3,$5,$1
> + insbl $1,$4,$1
> + mskbl $2,$4,$2
> +
> + bis $1,$2,$1
> + lda $5,1($5)
> + stq_u $1,0($4)
> + lda $4,1($4)
> +
> + and $4,7,$6
> + bne $6,$aligned_byte_loop_head_up
> +
> +$skip_aligned_byte_loop_head_up:
> + lda $18,-8($18)
> + blt $18,$skip_aligned_word_loop_up
> +
> +$aligned_word_loop_up:
> + ldq $1,0($5)
> + nop
> + lda $5,8($5)
> + lda $18,-8($18)
> +
> + stq $1,0($4)
> + nop
> + lda $4,8($4)
> + bge $18,$aligned_word_loop_up
> +
> +$skip_aligned_word_loop_up:
> + lda $18,8($18)
> + bgt $18,$byte_loop_tail_up
> + unop
> + ret $31,($26),1
> +
> + .align 4
> +$misaligned_up:
> + nop
> + fnop
> + unop
> + beq $18,$egress
> +
> +$byte_loop_tail_up:
> + ldq_u $3,0($5)
> + ldq_u $2,0($4)
> + lda $18,-1($18)
> + extbl $3,$5,$1
> +
> + insbl $1,$4,$1
> + mskbl $2,$4,$2
> + bis $1,$2,$1
> + stq_u $1,0($4)
> +
> + lda $5,1($5)
> + lda $4,1($4)
> nop
> - bgt $18,$byte_loop_tail
> + bgt $18,$byte_loop_tail_up
>
> $egress:
> ret $31,($26),1
Ok. It works.
Thanks.
--
Alex.