On Mon, Oct 21, 2013 at 9:34 AM, Michael Schmitz
<schm...@biophys.uni-duesseldorf.de> wrote:
> this looks like it might be related to the ESP driver - scsi_finish_command
> called from the swapper process during apt-get dist-upgrade does seem
> plausible.
>
> Some of the Amiga SCSI drivers did fiddle with the chip interrupt enable on
> SCSI interrupt entry, but I'd have thought the ESP core is reasonably
> thread-safe these days.
>
> To pinpoint where in sd_completed_bytes this happens, I'd need the sd_mod
> module and the module symbol map.
/* be careful ... don't want any overflows */
u64 factor = scmd->device->sector_size / 512;
do_div(start_lba, factor);
do_div(end_lba, factor);
scmd->device->sector_size should be 512, so factor should be 1.
Let's try a bit harder with a fresher mind and a cup of coffee and
a mini-twix:
>> [77568.320000] PC: [<0484c33a>] sd_completed_bytes+0x90/0xe8 [sd_mod]
>> [77568.330000] SR: 2000 SP: 00277e58 a2: 0027e2e4
>> [77568.340000] d0: 00000000 d1: 007735a0 d2: 00000000 d3: 00000001
>> [77568.350000] d4: 00000000 d5: 007735a8 a0: 024dd000 a1: 024a0ea0
>> [77569.190000] Code: 4a80 6704 4c42 0001 2c01 2207 4c42 1406 <2c00> 2e01
>> 2004 2204 6704 4c42 0001 2801 2205 4c42 1404 2800 2a01 202e fff8 222e
"4c42" is a division. It's the second one of the four divisions:
0: 4a80 tstl %d0
d0 is zero, so the first division is skipped.
2: 6704 beqs 0x8
4: 4c42 0001 divull %d2,%d1,%d0
8: 2c01 movel %d1,%d6
a: 2207 movel %d7,%d1
c: 4c42 1406 divul %d2,%d6,%d1
It's dividing by d2, which is zero. So scmd->device->sector_size must be
smaller than 512 (probably zero).
10: 2c00 movel %d0,%d6
12: 2e01 movel %d1,%d7
14: 2004 movel %d4,%d0
16: 2204 movel %d4,%d1
18: 6704 beqs 0x1e
1a: 4c42 0001 divull %d2,%d1,%d0
1e: 2801 movel %d1,%d4
20: 2205 movel %d5,%d1
22: 4c42 1404 divul %d2,%d4,%d1
26: 2800 movel %d0,%d4
28: 2a01 movel %d1,%d5
2a: 202e fff8 movel %fp@(-8),%d0
The posted binary has slightly different code (different addresses, and the
division is "4c40"):
00168404 <sd_completed_bytes>:
168404: 4e56 fff8 linkw %fp,#-8
168408: 48e7 3f1c moveml %d2-%d7/%a3-%a5,%sp@-
16840c: 266e 0008 moveal %fp@(8),%a3
168410: 206b 0054 moveal %a3@(84),%a0
168414: 2828 0032 movel %a0@(50),%d4
168418: 2a28 0036 movel %a0@(54),%d5
16841c: 2c2b 0040 movel %a3@(64),%d6
168420: 2e2b 0044 movel %a3@(68),%d7
168424: 7001 moveq #1,%d0
168426: b0a8 0022 cmpl %a0@(34),%d0
16842a: 6600 00b2 bnew 1684de <sd_completed_bytes+0xda>
16842e: 486e fff8 pea %fp@(-8)
168432: 4878 0060 pea 60 <PAGE_TABLE_SIZE+0x20>
168436: 2f2b 0058 movel %a3@(88),%sp@-
16843a: 4eb9 0015 4e86 jsr 154e86 <scsi_get_sense_info_fld>
168440: 4fef 000c lea %sp@(12),%sp
168444: 4a80 tstl %d0
168446: 6700 0096 beqw 1684de <sd_completed_bytes+0xda>
16844a: 2053 moveal %a3@,%a0
16844c: 2028 0054 movel %a0@(84),%d0
168450: b0ab 0040 cmpl %a3@(64),%d0
168454: 6400 0088 bccw 1684de <sd_completed_bytes+0xda>
168458: 2206 movel %d6,%d1
16845a: 7409 moveq #9,%d2
16845c: e4a9 lsrl %d2,%d1
16845e: 2601 movel %d1,%d3
168460: 4202 clrb %d2
168462: d685 addl %d5,%d3
168464: d584 addxl %d4,%d2
168466: 0c80 0000 01ff cmpil #511,%d0
16846c: 6212 bhis 168480 <sd_completed_bytes+0x7c>
16846e: da85 addl %d5,%d5
168470: d984 addxl %d4,%d4
168472: 2002 movel %d2,%d0
168474: 2203 movel %d3,%d1
168476: d281 addl %d1,%d1
168478: d180 addxl %d0,%d0
16847a: 2840 moveal %d0,%a4
16847c: 2a41 moveal %d1,%a5
16847e: 602a bras 1684aa <sd_completed_bytes+0xa6>
168480: 7209 moveq #9,%d1
168482: e2a8 lsrl %d1,%d0
168484: 2204 movel %d4,%d1
168486: 2045 moveal %d5,%a0
168488: 6704 beqs 16848e <sd_completed_bytes+0x8a>
16848a: 4c40 1004 divull %d0,%d4,%d1
16848e: 2a08 movel %a0,%d5
168490: 4c40 5404 divul %d0,%d4,%d5
168494: 2801 movel %d1,%d4
168496: 2202 movel %d2,%d1
168498: 2043 moveal %d3,%a0
16849a: 6704 beqs 1684a0 <sd_completed_bytes+0x9c>
16849c: 4c40 1002 divull %d0,%d2,%d1
1684a0: 2608 movel %a0,%d3
1684a2: 4c40 3402 divul %d0,%d2,%d3
1684a6: 2841 moveal %d1,%a4
1684a8: 2a43 moveal %d3,%a5
1684aa: 202e fff8 movel %fp@(-8),%d0
1684ae: 222e fffc movel %fp@(-4),%d1
1684b2: 2400 movel %d0,%d2
1684b4: 2601 movel %d1,%d3
1684b6: 9685 subl %d5,%d3
1684b8: 9584 subxl %d4,%d2
1684ba: 6522 bcss 1684de <sd_completed_bytes+0xda>
1684bc: 240c movel %a4,%d2
1684be: 260d movel %a5,%d3
1684c0: 9681 subl %d1,%d3
1684c2: 9580 subxl %d0,%d2
1684c4: 6318 blss 1684de <sd_completed_bytes+0xda>
1684c6: 9285 subl %d5,%d1
1684c8: 9184 subxl %d4,%d0
1684ca: 2053 moveal %a3@,%a0
1684cc: 9c87 subl %d7,%d6
1684ce: 2028 0054 movel %a0@(84),%d0
1684d2: 4c01 0800 mulsl %d1,%d0
1684d6: bc80 cmpl %d0,%d6
1684d8: 6406 bccs 1684e0 <sd_completed_bytes+0xdc>
1684da: 2006 movel %d6,%d0
1684dc: 6002 bras 1684e0 <sd_completed_bytes+0xdc>
1684de: 4280 clrl %d0
1684e0: 4cee 38fc ffd4 moveml %fp@(-44),%d2-%d7/%a3-%a5
1684e6: 4e5e unlk %fp
1684e8: 4e75 rts
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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