RE: crash mod -S problem

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Sorry, I have been away from this crash stuff for a while and 
am catching up on work after having been sick for a week.
I can hopefully look at this later this evening...

-----Original Message-----

----- "Cliff Wickman" <cpw@xxxxxxx> wrote:

> On Thu, Jan 29, 2009 at 11:23:49AM -0500, Dave Anderson wrote:
> > 
> > ----- "Cliff Wickman" <cpw@xxxxxxx> wrote:
> > 
> > > Hi Dave, and company,
> > > 
> > > I have a question.  Perhaps this is a known issue -- should I be
looking
> > > in an archive somewhere?
> > > 
> > > The crash command "mod -S" is messing up the address list.
> > > 
> > > This is crash-4.0-7.6, running on ia64.
> > > 
> > > Note how the value of module symbol xfs_ioerror_alert has changed
> > > after the mod -S.
> > > 
> > > Is this a crash problem?  Or my problem?  (there are several ?'s
in
> > > the mod -S output, including on the xfs module)
> > 
> > Good question -- I don't know.
> > 
> > It appears that the determination of the module's text starting
location
> > is being changed by the "mod -S".  That can happen when the
symbols.c
> > function store_load_module_symbols() calls
calculate_load_order_v2(),
> > which can change the text start location that was initialized during
> > the crash session initialization by store_module_symbols_v2().
> > 
> > The question is which text start address value is correct.
> > 
> > Try this:
> > 
> >   $ crash -s
> >   crash> help -s | grep mod_text_start > before
> >   crash> mod -S
> >   ... [ snip ] ...
> >   crash> help -s | grep mod_text_start > after
> >   crash> q
> > 
> >   $ diff before after
> 
> It changed:
> $ diff before after
> 1,3c1,3
> <         mod_text_start: a0000002093f0000 (0)
> <         mod_text_start: a000000209410000 (0)
> <         mod_text_start: a000000209430000 (0)
> ---
> >         mod_text_start: a0000002093f49e0 (49e0)
> >         mod_text_start: a000000209412040 (2040)
> >         mod_text_start: a000000209433968 (3968)
> 5,7c5,7
> <         mod_text_start: a000000209470000 (0)
> <         mod_text_start: a0000002094b0000 (0)
> <         mod_text_start: a000000209510000 (0)
> ---
> >         mod_text_start: a000000209483c68 (13c68)
> >         mod_text_start: a0000002094d31a8 (231a8)
> >         mod_text_start: a00000020951c4d8 (c4d8)
> [snip]
> 
>  
> > Typically it won't change, and the before and after files are
> identical.
> > 
> > But on your system it would appear that many (if not all) of the
modules are
> > changing their mod_text_start values upon running "mod -S".
> > 
> > You can also determine which value is correct by doing a "dis
<function>"
> > command before and after the "mod -S".
> 
> Yes, we were doing a "dis" when we noticed the problem.  The addresses
> are correct before the mod -S.
> 
> So you suspect the problem is in  calculate_load_order_v2() ?
> 
> -Cliff

If the text was correct *before* the "mod -S", then yes, the
text base address was changed by calculate_load_order_v2().

My first response started a cc: to Castor Fu, the author of 
calculate_load_order_v2() function, because I'd be interested
in what he has to say on the matter.  He's on west coast time.

As I understand it, calculate_load_order_v2() is taking the
first (lowest) symbol of each module section (as determined
during initialization), and searches for it in the module
object file.  And when it finds it, it calls bfd_get_section_name()
to get the section name string, and based upon that updates the
fields associated with that section.  For the .text section it
normally finds the first text symbol to have an offset value of 0,
and therefore no changes are made to the mod_text_offset.  It looks
like it's finding the "first" text symbol at a higher offset?

If you enter "set debug 3", and then do a "mod -s <module-name>",
you'll see its machinations on a given module.

Dave

 
> 
> 
> > > crash> sym xfs_ioerror_alert
> > > a000000209955f80 (t) xfs_ioerror_alert  
> > > 
> > > crash> mod -S
> > >      MODULE       NAME                   SIZE  OBJECT FILE
> > > a0000002093fc088  scsi_transport_spi    50672 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/scsi_transport_spi.ko 
> > > mod: ioc4: last symbol is not _MODULE_END_ioc4?
> > > a000000209412fa8  ioc4                  13056 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/misc/ioc4.ko 
> > > mod: scsi_tgt: last symbol is not _MODULE_END_scsi_tgt?
> > > a000000209435cd0  scsi_tgt              24640 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/scsi_tgt.ko 
> > > a000000209453610  sgiioc4               14656 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/ide/pci/sgiioc4.ko 
> > > mod: mptbase: last symbol is not _MODULE_END_mptbase?
> > > a000000209497298  mptbase              166540 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/message/fusion/mptbase.ko 
> > > a0000002094f8008  scsi_mod             299024 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/scsi_mod.ko 
> > > a000000209547038  ide_core             229280 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/ide/ide-core.ko 
> > > a000000209583da0  qla1280              148256 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/qla1280.ko 
> > > mod: scsi_transport_fc: last symbol is not
> > > _MODULE_END_scsi_transport_fc?
> > > a0000002095b51d0  scsi_transport_fc     88156 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/scsi_transport_fc.ko 
> > > a0000002095d7bd8  mptfc                 32776 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/message/fusion/mptfc.ko 
> > > mod: mptscsih: last symbol is not _MODULE_END_mptscsih?
> > > a000000209610618  mptscsih              68816 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/message/fusion/mptscsih.ko 
> > > a000000209631208  hwmon                  5304 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/hwmon/hwmon.ko 
> > > mod: thermal_sys: last symbol is not _MODULE_END_thermal_sys?
> > > a000000209655c90  thermal_sys           24656 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/thermal/thermal_sys.ko 
> > > a000000209679b40  thermal               41144 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/acpi/thermal.ko 
> > > a0000002096b4340  processor             85008 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/acpi/processor.ko 
> > > a0000002096d23c8  fan                    9960 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/acpi/fan.ko 
> > > a000000209718490  mptspi                34936 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/message/fusion/mptspi.ko 
> > > a000000209730e00  ide_generic            4264 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/ide/ide-generic.ko 
> > > a0000002097506f0  crc_t10dif             2336 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/lib/crc-t10dif.ko 
> > > a000000209773430  button                14312 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/acpi/button.ko 
> > > a0000002097b1380  sd_mod                72432 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/sd_mod.ko 
> > > a0000002097e12a0  sg                    71976 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/sg.ko 
> > > a0000002098124b8  cdrom                 77752 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/cdrom/cdrom.ko 
> > > mod: cannot find or load object file for ide_cd_mod module
> > > mod: libphy: last symbol is not _MODULE_END_libphy?
> > > a000000209859928  libphy                40168 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/net/phy/libphy.ko 
> > > mod: xfs: last symbol is not _MODULE_END_xfs?
> > > a0000002099abaf0  xfs                 1233888 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/xfs/xfs.ko 
> > > a0000002099ed130  mptctl               188064 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/message/fusion/mptctl.ko 
> > > a000000209a04690  mmtimer               18836 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/char/mmtimer.ko 
> > > a000000209a53a68  kdbm_pg               16632 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/kdb/modules/kdbm_pg.ko 
> > > a000000209a70a48  kdbm_sched             3296 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/kdb/modules/kdbm_sched.ko 
> > > a000000209a91b28  kdbm_task             40608 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/kdb/modules/kdbm_task.ko 
> > > a000000209b1fba0  qla2xxx              463704 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/scsi/qla2xxx/qla2xxx.ko 
> > > a000000209b850c0  tg3                  284796 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/net/tg3.ko 
> > > mod: dm_mod: last symbol is not _MODULE_END_dm_mod?
> > > a000000209ff25f8  dm_mod               143048 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/md/dm-mod.ko 
> > > a00000020a016518  kdbm_vm               28112 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/kdb/modules/kdbm_vm.ko 
> > > a00000020a031f20  mspec                 16932 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/char/mspec.ko 
> > > a00000020a05e290  numatools             59232 
> > > /lib/modules/2.6.27.8-1-sgidev/up
> > > dates/numatools.ko 
> > > a00000020a073f38  xp                    17216 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/misc/sgi-xp/xp.ko 
> > > a00000020a0b4c08  gru                   87288 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/misc/sgi-gru/gru.ko 
> > > a00000020a0d38e0  sgi_gpl_lib           15272 
> > > /lib/modules/2.6.27.8-1-sgidev/we
> > > ak-updates/extra/gpl_lib/sgi-gpl-lib.ko 
> > > a00000020a115c58  myri10ge              91048 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/net/myri10ge/myri10ge.ko 
> > > mod: loop: last symbol is not _MODULE_END_loop?
> > > a00000020a138478  loop                  34788 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/block/loop.ko 
> > > mod: cannot find or load object file for nls_iso8859_1 module
> > > a00000020a18ac80  sgi_os_lib           111192 
> > > /lib/modules/2.6.27.8-1-sgidev/we
> > > ak-updates/extra/os_lib/sgi-os-lib.ko 
> > > mod: crypto_blkcipher: last symbol is not
> > > _MODULE_END_crypto_blkcipher?
> > > a00000020a1a8c00  crypto_blkcipher      36848 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/crypto/crypto_blkcipher.ko 
> > > a00000020a1c6fd0  dm_crypt              29784 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/drivers/md/dm-crypt.ko 
> > > a00000020a1e4cd8  binfmt_misc           20444 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/binfmt_misc.ko 
> > > a00000020a25d758  xpmem                122536 
> > > /lib/modules/2.6.27.8-1-sgidev/up
> > > dates/xpmem.ko 
> > > a00000020a28d518  fuse                 121352 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/fuse/fuse.ko 
> > > mod: ipv6: last symbol is not _MODULE_END_ipv6?
> > > a00000020a358030  ipv6                 627656 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/net/ipv6/ipv6.ko 
> > > mod: sgi_xvm: last symbol is not _MODULE_END_sgi_xvm?
> > > a00000020a41a520  sgi_xvm              704400 
> > > /lib/modules/2.6.27.8-1-sgidev/we
> > > ak-updates/extra/xvm/sgi-xvm.ko 
> > > a00000020a46ba78  autofs4               48656 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/autofs4/autofs4.ko 
> > > a00000020a482090  exportfs               8944 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/exportfs/exportfs.ko 
> > > mod: auth_rpcgss: last symbol is not _MODULE_END_auth_rpcgss?
> > > a00000020a4b3ee0  auth_rpcgss           82696 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/net/sunrpc/auth_gss/auth_rpcgss.ko 
> > > mod: nfs_acl: last symbol is not _MODULE_END_nfs_acl?
> > > a00000020a4d17b8  nfs_acl                6648 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/nfs_common/nfs_acl.ko 
> > > a00000020a5b1e88  sunrpc               472176 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/net/sunrpc/sunrpc.ko 
> > > mod: lockd: last symbol is not _MODULE_END_lockd?
> > > a00000020a5f1e00  lockd                141416 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/lockd/lockd.ko 
> > > a00000020a6aaa98  nfs                  641664 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/nfs/nfs.ko 
> > > a00000020a73ea30  nfsd                 523168 
> > > /lib/modules/2.6.27.8-1-sgidev/ke
> > > rnel/fs/nfsd/nfsd.ko 
> > > 
> > > crash> sym xfs_ioerror_alert
> > > a000000209992d18 (T) xfs_ioerror_alert 
> > > 
> > > Thanks.
> > > -Cliff
> > > 
> > > --
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> > > https://www.redhat.com/mailman/listinfo/crash-utility
> > 
> > --
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> 
> -- 
> Cliff Wickman
> Silicon Graphics, Inc.
> cpw@xxxxxxx
> (651) 683-3824
> 
> --
> Crash-utility mailing list
> Crash-utility@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/crash-utility


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