Date: Mon, 10 Mar 2003 22:03:28 +0800 From: Jun Su <JunSu@gmx.net> To: Dag-Erling Smorgrav <des@ofug.org> Cc: freebsd-current@freebsd.org Subject: Re: GDB kernel debug new command Message-ID: <200303102203.28668.JunSu@gmx.net> In-Reply-To: <xzpllznbmf4.fsf@flood.ping.uio.no> References: <200303081224.53273.JunSu@gmx.net> <xzpllznbmf4.fsf@flood.ping.uio.no>
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On Monday 10 March 2003 17:28, Dag-Erling Smorgrav wrote:
> Jun Su <JunSu@gmx.net> writes:
> > To help myself more easily check the kernel dump, I added two new
> > command. One is ps, the other is kldstat. I know we can print the kernel
> > data manually to get the same information. I still think this is useful.
> > This can help the newbies to get the information without many knowledge
> > about the kernel. This also can help the experienced user to get the data
> > more quickly.
> >
> > Here is the new file. Just put it in /usr/src/gnu/usr.bin/binutils/gdb.
> > And add the file to Makefile. Please give me some comments if this is
> > garbage. :)
>
> This is pointless as it won't work unless gdb is in synch with the
> kernel (since it depends on knowing the layout of struct proc and
> struct linker_file). Both of these commands can be implemented as
> macros, which will not depend on gdb being in synch with the kernel.
>
> Greg Lehey wrote this ps macro:
>
> define ps
> set $nproc = nprocs
> set $aproc = allproc.lh_first
> set $proc = allproc.lh_first
> printf " pid proc addr uid ppid pgrp flag stat comm
> wchan\n" while (--$nproc >= 0)
> set $pptr = $proc.p_pptr
> if ($pptr == 0)
> set $pptr = $proc
> end
> if ($proc.p_stat)
> printf "%5d %08x %08x %4d %5d %5d %06x %d %-10s ", \
> $proc.p_pid, $aproc, \
> $proc.p_addr, $proc.p_cred->p_ruid, $pptr->p_pid, \
> $proc.p_pgrp->pg_id, $proc.p_flag, $proc.p_stat, \
> &$proc.p_comm[0]
> if ($proc.p_wchan)
> if ($proc.p_wmesg)
> printf "%s ", $proc.p_wmesg
> end
> printf "%x", $proc.p_wchan
> end
> printf "\n"
> end
> set $aproc = $proc.p_list.le_next
> if ($aproc == 0 && $nproc > 0)
> set $aproc = zombproc
> end
> set $proc = $aproc
> end
> end
>
> document ps
> "ps" -- when kernel debugging, type out a ps-like listing of active
> processes. end
>
> and I've written two variants of kldstat myself, plus a kldload:
>
> end
>
> document kldstat
> Lists the modules that were loaded when the kernel crashed.
> end
>
> define kldstat-v
> set $kld = linker_files.tqh_first
> printf "Id Refs Address Size Name\n"
> while ($kld != 0)
> printf "%2d %4d 0x%08x %-8x %s\n", \
> $kld->id, $kld->refs, $kld->address, $kld->size, $kld->filename
> printf " Contains modules:\n"
> printf " Id Name\n"
> set $module = $kld->modules.tqh_first
> while ($module != 0)
> printf " %2d %s\n", $module->id, $module->name
> set $module = $module->link.tqe_next
> end
> set $kld = $kld->link.tqe_next
> end
> end
>
> document kldstat-v
> Lists modules with full information.
> end
>
> define kldload
> set $kld = linker_files.tqh_first
> set $done = 0
> while ($kld != 0 && $done == 0)
> if ($kld->filename == $arg0)
> set $done = 1
> else
> set $kld = $kld->link.tqe_next
> end
> end
> if ($done == 1)
> shell /usr/bin/objdump -h $arg0 | \
> awk '/ .text/ { print "set \$offset = 0x" $6 }' > .kgdb.temp
> source .kgdb.temp
> add-symbol-file $arg0 $kld->address + $offset
> end
> end
>
> document kldload
> Loads a module. Arguments are module name and offset of text section.
> end
>
> Note that for kldload to work, you need to know the offset of the text
> section for the module you wish to load (objdump -h will tell you)
>
> Note also that I haven't used any of these macros in a long time, so
> there may be some issues related to KSE or whatnot.
>
> DES
You are so cool. Your macro is better than my code. Thanks.
I think the kernel structure is not changed often. These type of macro can
help most newbies such as me to enter the freebsd debug easily. It is worth
to maintain a copy somewhere. (In source tree, it may be great.) I used
windbg for a long time. it provides many commands to help developer debug.
This is a good pratice I think. :)
Jun Su
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