Date: Wed, 20 Dec 2006 12:52:02 -0800 From: "Kip Macy" <kip.macy@gmail.com> To: "Dmitry Pryanishnikov" <dmitry@atlantis.dp.ua> Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-current@freebsd.org, Kip Macy <kmacy@freebsd.org> Subject: Re: ddb(4) spoils kernel stack in CURRENT? Message-ID: <b1fa29170612201252w98d0848ja2b6f476b108db41@mail.gmail.com> In-Reply-To: <b1fa29170612201241t3de56acag81d60348a07a1791@mail.gmail.com> References: <20061219175917.L84683@atlantis.atlantis.dp.ua> <20061220130559.P54963@atlantis.atlantis.dp.ua> <20061220124032.GC23698@deviant.kiev.zoral.com.ua> <20061220215753.H53808@atlantis.atlantis.dp.ua> <b1fa29170612201241t3de56acag81d60348a07a1791@mail.gmail.com>
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I've identified the workaround code in DDB. I'll commit a fix as soon as I
have some time to test my changes.
-Kip
On 12/20/06, Kip Macy <kip.macy@gmail.com> wrote:
>
> I worried that gdb probably had workaround for the large stack argument.
> I'll have to dig it up, thanks for the heads up.
>
> -Kip
>
> On 12/20/06, Dmitry Pryanishnikov <dmitry@atlantis.dp.ua> wrote:
> >
> >
> > Hello!
> >
> > On Wed, 20 Dec 2006, Kostik Belousov wrote:
> > >>> So it looks like a regression in CURRENT vs RELENG_6 (either ddb
> > 'spoils'
> > >>> the stack somehow, or kgdb fails to unwind it).
> > >
> > > Could you further localize the problem, i.e. try to backtrace CURRENT
> > dump
> >
> > Good news: I've managed to localize the bug! I'm Feeling Lucky (TM)
> > ;)
> > just because CURRENT on my notebook was updated approx. at 17-Dec 00:00,
> >
> > and it didn't manifest such a behaviour! So it was easy to identify the
> > regression - it comes with the following commit:
> >
> > -----------------------------------------------------------------------
> >
> > Date: Sun, 17 Dec 2006 05:07:01 +0000 (UTC)
> > From: Kip Macy <kmacy@freebsd.org>
> > To: src-committers@freebsd.org, cvs-src@freebsd.org ,
> > cvs-all@freebsd.org
> > Subject: cvs commit: src/sys/i386/i386 apic_vector.s exception.slocal_apic.c
> > trap.c vm86.c vm86bios.s src/sys/i386/include apicvar.h
> > src/sys/i386/isa atpic.c atpic_vector.s icu.h
> >
> > kmacy 2006-12-17 05:07:01 UTC
> >
> > FreeBSD src repository
> >
> > Modified files:
> > sys/i386/i386 apic_vector.s exception.s local_apic.c
> > trap.c vm86.c vm86bios.s
> > sys/i386/include apicvar.h
> > sys/i386/isa atpic.c atpic_vector.s icu.h
> > Log:
> > Evidently FreeBSD has long relied on the compiler to treat structures
> > passed by value (trap frames) as if they were in fact being passed by
> >
> > reference. For better or worse, this incorrect behaviour is no longer
> > present in gcc 4.1. In this patch I convert all trapframe arguments
> > to
> > be explicitly pass by reference. I also remove vm86_initflags,
> > pushing
> > the very little work that it actually does up into vm86_prepcall.
> >
> > -----------------------------------------------------------------------
> >
> > So kernel built from sources as of date=2006.12.17.05.00.00 gives dump
> > with analyzable backtrace, and kernel built from sources as of
> > date=2006.12.17.05.10.00 (which include this commit) gives dump
> > which confuses kgdb. I believe that commit itself is correct,
> > but kgdb contains some workaround against the old (incorrect) behaviour
> > of the kernel, so it's the kgdb that should be fixed.
> >
> > Sincerely, Dmitry
> > --
> > Atlantis ISP, System Administrator
> > e-mail: dmitry@atlantis.dp.ua
> > nic-hdl: LYNX-RIPE
> > _______________________________________________
> > freebsd-current@freebsd.org mailing list
> > http://lists.freebsd.org/mailman/listinfo/freebsd-current
> > To unsubscribe, send any mail to "
> > freebsd-current-unsubscribe@freebsd.org"
> >
>
>
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