From: ebiederm@xmission.com (Eric W. Biederman)
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Mike Travis <travis@sgi.com>, "H. Peter Anvin" <hpa@zytor.com>,
Christoph Lameter <clameter@sgi.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area
Date: Tue, 01 Jul 2008 01:40:02 -0700 [thread overview]
Message-ID: <m1skuuov4t.fsf@frodo.ebiederm.org> (raw)
In-Reply-To: <48694B3B.3010600@goop.org> (Jeremy Fitzhardinge's message of "Mon, 30 Jun 2008 14:08:11 -0700")
Jeremy Fitzhardinge <jeremy@goop.org> writes:
> No, the original crash being discussed was a GP fault in head_64.S as it tries
> to initialize the kernel segments. The cause was that the prototype GDT is all
> zero, even though it's an initialized variable, and inspection of vmlinux shows
> that it has the right contents. But somehow it's either 1) getting zeroed on
> load, or 2) is loaded to the wrong place.
>
> The zero-based PDA mechanism requires the introduction of a new ELF segment
> based at vaddr 0 which is sufficiently unusual that it wouldn't surprise me if
> its triggering some toolchain bug.
Agreed. Given the previous description my hunch is that the bug is occurring
during objcopy. If vmlinux is good and the compressed kernel is bad.
It should be possible to look at vmlinux.bin and see if that was generated
properly.
> Mike: what would happen if the PDA were based at 4k rather than 0? The stack
> canary would still be at its small offset (0x20?), but it doesn't need to be
> initialized. I'm not sure if doing so would fix anything, however.
I'm dense today. Why are we doing a zero based pda? That seems the most
likely culprit of linker trouble, and we should be able to put a smaller
offset in the segment register to allow for everything to work as expected.
Eric
next prev parent reply other threads:[~2008-07-01 8:41 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-04 0:30 [PATCH 0/4] percpu: Optimize percpu accesses Mike Travis
2008-06-04 0:30 ` [PATCH 1/4] Zero based percpu: Infrastructure to rebase the per cpu area to zero Mike Travis
2008-06-10 10:06 ` Ingo Molnar
2008-06-04 0:30 ` [PATCH 2/4] x86: Extend percpu ops to 64 bit Mike Travis
2008-06-10 10:04 ` Ingo Molnar
2008-06-04 0:30 ` [PATCH 3/4] x86_64: Fold pda into per cpu area Mike Travis
2008-06-04 12:59 ` Jeremy Fitzhardinge
2008-06-04 13:48 ` Mike Travis
2008-06-04 13:58 ` Jeremy Fitzhardinge
2008-06-04 14:17 ` Mike Travis
2008-06-09 23:18 ` Christoph Lameter
2008-06-05 10:22 ` [crash, bisected] " Ingo Molnar
2008-06-05 16:02 ` Mike Travis
2008-06-06 8:29 ` Jeremy Fitzhardinge
2008-06-06 13:15 ` Mike Travis
2008-06-18 5:34 ` Jeremy Fitzhardinge
2008-06-10 21:31 ` Mike Travis
2008-06-18 17:36 ` Jeremy Fitzhardinge
2008-06-18 18:17 ` Mike Travis
2008-06-18 18:33 ` Ingo Molnar
2008-06-18 19:33 ` Jeremy Fitzhardinge
[not found] ` <48596893.4040908@sgi.com>
[not found] ` <485AADAC.3070301@sgi.com>
[not found] ` <485AB78B.5090904@goop.org>
[not found] ` <485AC120.6010202@sgi.com>
[not found] ` <485AC5D4.6040302@goop.org>
[not found] ` <485ACA8F.10006@sgi.com>
[not found] ` <485ACD92.8050109@sgi.com>
2008-06-19 21:35 ` Jeremy Fitzhardinge
2008-06-19 21:54 ` Jeremy Fitzhardinge
2008-06-19 22:13 ` Mike Travis
2008-06-19 22:21 ` Jeremy Fitzhardinge
2008-06-30 17:49 ` Mike Travis
2008-06-19 22:23 ` Jeremy Fitzhardinge
[not found] ` <485BDB04.4090709@sgi.com>
2008-06-20 17:25 ` Jeremy Fitzhardinge
2008-06-20 17:48 ` Christoph Lameter
2008-06-20 18:30 ` Mike Travis
2008-06-20 18:40 ` Jeremy Fitzhardinge
2008-06-20 18:37 ` Jeremy Fitzhardinge
2008-06-20 18:51 ` Christoph Lameter
2008-06-20 19:04 ` Jeremy Fitzhardinge
2008-06-20 19:21 ` H. Peter Anvin
2008-06-20 19:43 ` Eric W. Biederman
2008-06-20 20:04 ` Mike Travis
2008-06-20 20:37 ` Christoph Lameter
2008-06-20 19:06 ` Mike Travis
2008-06-20 20:25 ` Eric W. Biederman
2008-06-20 20:55 ` Christoph Lameter
2008-06-23 16:55 ` Mike Travis
2008-06-23 17:33 ` Jeremy Fitzhardinge
2008-06-23 18:04 ` Mike Travis
2008-06-23 18:36 ` Mike Travis
2008-06-23 19:41 ` Jeremy Fitzhardinge
2008-06-24 0:02 ` Mike Travis
2008-06-30 17:07 ` Mike Travis
2008-06-30 17:18 ` H. Peter Anvin
2008-06-30 17:57 ` Mike Travis
2008-06-30 20:50 ` Eric W. Biederman
2008-06-30 21:08 ` Jeremy Fitzhardinge
2008-07-01 8:40 ` Eric W. Biederman [this message]
2008-07-01 16:27 ` Jeremy Fitzhardinge
2008-07-01 16:55 ` Mike Travis
2008-07-01 16:56 ` H. Peter Anvin
2008-07-01 17:26 ` Jeremy Fitzhardinge
2008-07-01 20:40 ` Eric W. Biederman
2008-07-01 21:10 ` Jeremy Fitzhardinge
2008-07-01 21:39 ` Eric W. Biederman
2008-07-01 21:52 ` Jeremy Fitzhardinge
2008-07-02 0:20 ` H. Peter Anvin
2008-07-02 1:15 ` Mike Travis
2008-07-02 1:32 ` Eric W. Biederman
2008-07-02 1:51 ` Mike Travis
2008-07-02 2:50 ` Eric W. Biederman
2008-07-02 1:40 ` H. Peter Anvin
2008-07-02 1:44 ` Mike Travis
2008-07-02 1:45 ` H. Peter Anvin
2008-07-02 1:55 ` Mike Travis
2008-07-02 22:50 ` Mike Travis
2008-07-03 4:34 ` Eric W. Biederman
2008-07-07 17:17 ` Mike Travis
2008-07-07 19:46 ` Eric W. Biederman
2008-07-08 18:21 ` Mike Travis
2008-07-08 23:36 ` Eric W. Biederman
2008-07-08 23:49 ` Jeremy Fitzhardinge
2008-07-09 14:39 ` Mike Travis
2008-07-25 20:06 ` Mike Travis
2008-07-25 20:12 ` Jeremy Fitzhardinge
2008-07-25 20:34 ` Mike Travis
2008-07-25 20:43 ` Jeremy Fitzhardinge
2008-07-25 21:05 ` Mike Travis
2008-07-09 14:37 ` Mike Travis
2008-07-09 22:38 ` Eric W. Biederman
2008-07-09 23:30 ` Mike Travis
2008-07-10 0:04 ` Eric W. Biederman
2008-07-02 2:01 ` H. Peter Anvin
2008-07-02 3:08 ` Eric W. Biederman
2008-07-01 21:11 ` Andi Kleen
2008-07-01 21:42 ` Eric W. Biederman
2008-07-01 18:41 ` Eric W. Biederman
2008-07-01 12:09 ` Mike Travis
2008-07-01 11:49 ` Mike Travis
2008-06-30 17:43 ` Jeremy Fitzhardinge
2008-06-04 0:30 ` [PATCH 4/4] x86: Replace xxx_pda() operations with x86_xx_percpu() Mike Travis
2008-06-09 13:03 ` Ingo Molnar
2008-06-09 16:08 ` Mike Travis
2008-06-09 17:36 ` Mike Travis
2008-06-09 18:20 ` Christoph Lameter
2008-06-09 23:29 ` Jeremy Fitzhardinge
2008-06-10 10:09 ` Ingo Molnar
2008-06-10 15:07 ` Mike Travis
2008-06-04 10:18 ` [PATCH] x86: collapse the various size-dependent percpu accessors together Jeremy Fitzhardinge
2008-06-04 10:45 ` Jeremy Fitzhardinge
2008-06-04 11:29 ` Ingo Molnar
2008-06-04 12:09 ` Jeremy Fitzhardinge
2008-06-10 17:21 ` Christoph Lameter
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