From: Ingo Molnar <mingo@elte.hu>
To: "Klaus S. Madsen" <ksm@hjernemadsen.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending
Date: Thu, 28 Feb 2008 10:16:39 +0100 [thread overview]
Message-ID: <20080228091639.GB1133@elte.hu> (raw)
In-Reply-To: <20080227221033.GR17932@hjernemadsen.org>
* Klaus S. Madsen <ksm@hjernemadsen.org> wrote:
> Hi all,
>
> I have a Thinkpad T61p, which I'm able to suspend with s2ram
> on Linux 2.6.24.3. However when I try to suspend it on 2.6.25-rc3,
> s2ram dies after changing to vt1, with a segfault. I'm using s2ram
> from cvs, and libx86 version 0.99 from
> http://www.codon.org.uk/~mjg59/libx86/.
>
> Some details about the segfault:
>
> $ sudo gdb ./s2ram
> (gdb) run
> Starting program: /home/ksm/downloads/suspend/s2ram
> Switching from vt7 to vt1
> Calling get_mode
>
> Program received signal SIGSEGV, Segmentation fault.
> 0xb7facf4a in run_vm86 () at lrmi.c:526
> 526 asm volatile (
> (gdb) list
> 521 static int
> 522 lrmi_vm86(struct vm86_struct *vm)
> 523 {
> 524 int r;
> 525 #ifdef __PIC__
> 526 asm volatile (
> 527 "pushl %%ebx\n\t"
> 528 "movl %2, %%ebx\n\t"
> 529 "int $0x80\n\t"
> 530 "popl %%ebx"
> (gdb) bt
> #0 0xb7facf4a in run_vm86 () at lrmi.c:526
> #1 0xb7fad61b in LRMI_int (i=16, r=0xbffca670) at lrmi.c:844
> #2 0x0804acfc in do_vbe_service (AX=20227, BX=0, regs=0xbffca670)
> at vbetool/vbetool.c:158
> #3 0x0804af7e in __get_mode () at vbetool/vbetool.c:453
> #4 0x0804a30f in s2ram_hacks () at s2ram-x86.c:268
> #5 0x0804954f in main (argc=1, argv=0x0) at s2ram-main.c:92
>
> I have tried to bisect the problem, and it fingered the following
> commit:
>
> commit 82bc03fc158e28c90d7ed9919410776039cb4e14
> Author: Ingo Molnar <mingo@elte.hu>
>
> x86: add PWT to NOCACHE flags
>
> Reverting this commit in the bisected tree (by executing git show
> 82bc03fc158e28c90d7ed9919410776039cb4e14 | patch -R -p1), makes the
> segfault go away. I've run make clean between each kernel compile, to
> be sure the tree was correctly compiled.
thanks for tracking this down. It would be nice to figure out why this
change made a difference. Perhaps VM86 mode has some restrictions in
what type of pagetables it can operate in - and the CPU just refuses to
properly emulate those 16-bit instructions? (this would be very weird).
We are trying to execute 16-bit BIOS code here, right?
which instruction is the segfault coming from - the int $0x80? So in
vm86 mode we generated a #GPF which shows up as a SIGSEGV?
Ingo
next prev parent reply other threads:[~2008-02-28 9:17 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-27 22:10 Regression in 2.6.25-rc3: s2ram segfaults before suspending Klaus S. Madsen
2008-02-27 22:19 ` Rafael J. Wysocki
2008-02-27 22:40 ` Pavel Machek
2008-02-28 6:47 ` Klaus S. Madsen
2008-02-28 7:03 ` Pavel Machek
2008-02-28 7:08 ` Klaus S. Madsen
2008-02-28 9:16 ` Ingo Molnar [this message]
2008-02-28 9:28 ` Klaus S. Madsen
2008-02-28 9:40 ` Ingo Molnar
2008-02-28 15:04 ` Klaus S. Madsen
2008-02-28 17:52 ` H. Peter Anvin
2008-02-28 19:24 ` Klaus S. Madsen
2008-02-28 19:31 ` H. Peter Anvin
2008-02-28 19:49 ` Klaus S. Madsen
2008-02-28 22:45 ` H. Peter Anvin
2008-02-29 7:00 ` Klaus S. Madsen
2008-02-29 21:05 ` H. Peter Anvin
2008-02-29 21:26 ` Ingo Molnar
2008-03-01 9:45 ` Klaus S. Madsen
2008-03-01 19:53 ` H. Peter Anvin
2008-03-03 12:17 ` Pavel Machek
2008-03-03 15:11 ` Klaus S. Madsen
2008-03-03 17:48 ` Ingo Molnar
2008-03-03 17:53 ` H. Peter Anvin
2008-03-03 20:52 ` Klaus S. Madsen
2008-03-03 20:58 ` H. Peter Anvin
2008-03-03 21:05 ` Pavel Machek
2008-03-03 21:06 ` Matthew Garrett
2008-03-03 21:06 ` Pavel Machek
2008-03-03 21:21 ` Klaus S. Madsen
2008-03-04 12:36 ` Ingo Molnar
2008-03-04 21:58 ` Klaus S. Madsen
2008-03-04 22:08 ` H. Peter Anvin
2008-03-04 23:00 ` Jeremy Fitzhardinge
2008-03-04 23:11 ` H. Peter Anvin
2008-03-04 23:21 ` Jeremy Fitzhardinge
2008-03-04 23:30 ` Matthew Garrett
2008-03-04 12:42 ` Ingo Molnar
2008-03-03 15:40 ` Rafael J. Wysocki
2008-03-03 17:10 ` H. Peter Anvin
2008-03-03 17:47 ` Pavel Machek
2008-03-03 17:50 ` H. Peter Anvin
2008-03-03 17:53 ` Ingo Molnar
2008-03-03 17:58 ` H. Peter Anvin
2008-03-01 1:18 ` Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20080228091639.GB1133@elte.hu \
--to=mingo@elte.hu \
--cc=hpa@zytor.com \
--cc=ksm@hjernemadsen.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pavel@ucw.cz \
--cc=rjw@sisk.pl \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).