From: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
To: Bhupesh Sharma <bhsharma@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Boris Petkov <bp@alien8.de>, Baoquan He <bhe@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Dave Anderson <anderson@redhat.com>,
James Morse <james.morse@arm.com>, Omar Sandoval <osandov@fb.com>,
"x86@kernel.org" <x86@kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v2] x86_64, vmcoreinfo: Append 'page_offset_base' to vmcoreinfo
Date: Mon, 19 Nov 2018 21:07:27 +0000 [thread overview]
Message-ID: <4AE2DC15AC0B8543882A74EA0D43DBEC03560F84@BPXM09GP.gisp.nec.co.jp> (raw)
In-Reply-To: <1542318469-13699-1-git-send-email-bhsharma@redhat.com>
On 11/15/2018 4:47 PM, Bhupesh Sharma wrote:
> Adding 'page_offset_base' to the vmcoreinfo can be specially useful for
> live-debugging of a running kernel via user-space utilities
> like makedumpfile (see [1]).
I agree.
> Recently, I saw an issue with the 'makedumpfile' utility (see [2] for
> details), whose live debugging feature is broken with newer kernels
> (I tested the same with 4.19-rc8+ kernel), as KCORE_REMAP segments were
> added to kcore, thus leading to an additional sections in the same, and
> makedumpfile is not longer able to determine the start of direct
> mapping of all physical memory, as it relies on traversing the PT_LOAD
> segments inside kcore and using the last PT_LOAD segment
> to determine the start of direct mapping.
Actually, the KCORE_REMAP segments were already removed from kcore by
commit bf904d2762ee ("x86/pti/64: Remove the SYSCALL64 entry trampoline")
and kcore's program headers got back to the previous ones, but this
fact shows that they are changeable.
So I think that if we have this NUMBER(page_offset_base) in vmcoreinfo
for x86_64, user-space tools (especially makedumpfile) would become
more stable against changes in kcore and vmcore, rather than depending
on their PT_LOAD values.
Thanks,
Kazu
WARNING: multiple messages have this Message-ID (diff)
From: k-hagio@ab.jp.nec.com (Kazuhito Hagio)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] x86_64, vmcoreinfo: Append 'page_offset_base' to vmcoreinfo
Date: Mon, 19 Nov 2018 21:07:27 +0000 [thread overview]
Message-ID: <4AE2DC15AC0B8543882A74EA0D43DBEC03560F84@BPXM09GP.gisp.nec.co.jp> (raw)
In-Reply-To: <1542318469-13699-1-git-send-email-bhsharma@redhat.com>
On 11/15/2018 4:47 PM, Bhupesh Sharma wrote:
> Adding 'page_offset_base' to the vmcoreinfo can be specially useful for
> live-debugging of a running kernel via user-space utilities
> like makedumpfile (see [1]).
I agree.
> Recently, I saw an issue with the 'makedumpfile' utility (see [2] for
> details), whose live debugging feature is broken with newer kernels
> (I tested the same with 4.19-rc8+ kernel), as KCORE_REMAP segments were
> added to kcore, thus leading to an additional sections in the same, and
> makedumpfile is not longer able to determine the start of direct
> mapping of all physical memory, as it relies on traversing the PT_LOAD
> segments inside kcore and using the last PT_LOAD segment
> to determine the start of direct mapping.
Actually, the KCORE_REMAP segments were already removed from kcore by
commit bf904d2762ee ("x86/pti/64: Remove the SYSCALL64 entry trampoline")
and kcore's program headers got back to the previous ones, but this
fact shows that they are changeable.
So I think that if we have this NUMBER(page_offset_base) in vmcoreinfo
for x86_64, user-space tools (especially makedumpfile) would become
more stable against changes in kcore and vmcore, rather than depending
on their PT_LOAD values.
Thanks,
Kazu
WARNING: multiple messages have this Message-ID (diff)
From: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
To: Bhupesh Sharma <bhsharma@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: James Morse <james.morse@arm.com>, Baoquan He <bhe@redhat.com>,
"x86@kernel.org" <x86@kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
Omar Sandoval <osandov@fb.com>,
Dave Anderson <anderson@redhat.com>, Boris Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v2] x86_64, vmcoreinfo: Append 'page_offset_base' to vmcoreinfo
Date: Mon, 19 Nov 2018 21:07:27 +0000 [thread overview]
Message-ID: <4AE2DC15AC0B8543882A74EA0D43DBEC03560F84@BPXM09GP.gisp.nec.co.jp> (raw)
In-Reply-To: <1542318469-13699-1-git-send-email-bhsharma@redhat.com>
On 11/15/2018 4:47 PM, Bhupesh Sharma wrote:
> Adding 'page_offset_base' to the vmcoreinfo can be specially useful for
> live-debugging of a running kernel via user-space utilities
> like makedumpfile (see [1]).
I agree.
> Recently, I saw an issue with the 'makedumpfile' utility (see [2] for
> details), whose live debugging feature is broken with newer kernels
> (I tested the same with 4.19-rc8+ kernel), as KCORE_REMAP segments were
> added to kcore, thus leading to an additional sections in the same, and
> makedumpfile is not longer able to determine the start of direct
> mapping of all physical memory, as it relies on traversing the PT_LOAD
> segments inside kcore and using the last PT_LOAD segment
> to determine the start of direct mapping.
Actually, the KCORE_REMAP segments were already removed from kcore by
commit bf904d2762ee ("x86/pti/64: Remove the SYSCALL64 entry trampoline")
and kcore's program headers got back to the previous ones, but this
fact shows that they are changeable.
So I think that if we have this NUMBER(page_offset_base) in vmcoreinfo
for x86_64, user-space tools (especially makedumpfile) would become
more stable against changes in kcore and vmcore, rather than depending
on their PT_LOAD values.
Thanks,
Kazu
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2018-11-19 21:17 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-15 21:47 [PATCH v2] x86_64, vmcoreinfo: Append 'page_offset_base' to vmcoreinfo Bhupesh Sharma
2018-11-15 21:47 ` Bhupesh Sharma
2018-11-15 21:47 ` Bhupesh Sharma
2018-11-19 21:07 ` Kazuhito Hagio [this message]
2018-11-19 21:07 ` Kazuhito Hagio
2018-11-19 21:07 ` Kazuhito Hagio
2018-11-21 7:37 ` Bhupesh Sharma
2018-11-21 7:37 ` Bhupesh Sharma
2018-11-21 7:37 ` Bhupesh Sharma
2018-11-21 11:39 ` Borislav Petkov
2018-11-21 11:39 ` Borislav Petkov
2018-11-21 11:39 ` Borislav Petkov
2018-11-24 20:06 ` Bhupesh Sharma
2018-11-24 20:06 ` Bhupesh Sharma
2018-11-24 20:06 ` Bhupesh Sharma
2018-11-25 10:19 ` Baoquan He
2018-11-25 10:19 ` Baoquan He
2018-11-25 10:19 ` Baoquan He
2018-11-27 22:16 ` Kees Cook
2018-11-27 22:16 ` Kees Cook
2018-11-27 22:16 ` Kees Cook
2018-11-27 23:29 ` Baoquan He
2018-11-27 23:29 ` Baoquan He
2018-11-27 23:29 ` Baoquan He
2018-11-28 0:39 ` Kees Cook
2018-11-28 0:39 ` Kees Cook
2018-11-28 0:39 ` Kees Cook
2018-11-28 1:39 ` Baoquan He
2018-11-28 1:39 ` Baoquan He
2018-11-28 1:39 ` Baoquan He
2018-11-28 1:57 ` Baoquan He
2018-11-28 1:57 ` Baoquan He
2018-11-28 1:57 ` Baoquan He
2018-11-28 4:26 ` Bhupesh Sharma
2018-11-28 4:26 ` Bhupesh Sharma
2018-11-28 4:26 ` Bhupesh Sharma
2018-11-28 11:38 ` Dave Young
2018-11-28 11:38 ` Dave Young
2018-11-28 11:38 ` Dave Young
2018-11-26 1:28 ` Baoquan He
2018-11-26 1:28 ` Baoquan He
2018-11-26 1:28 ` Baoquan He
2018-11-26 19:31 ` Bhupesh Sharma
2018-11-26 19:31 ` Bhupesh Sharma
2018-11-26 19:31 ` Bhupesh Sharma
2018-11-27 6:48 ` Baoquan He
2018-11-27 6:48 ` Baoquan He
2018-11-27 6:48 ` Baoquan He
2018-11-27 7:15 ` Baoquan He
2018-11-27 7:15 ` Baoquan He
2018-11-27 7:15 ` Baoquan He
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=4AE2DC15AC0B8543882A74EA0D43DBEC03560F84@BPXM09GP.gisp.nec.co.jp \
--to=k-hagio@ab.jp.nec.com \
--cc=anderson@redhat.com \
--cc=bhe@redhat.com \
--cc=bhsharma@redhat.com \
--cc=bp@alien8.de \
--cc=james.morse@arm.com \
--cc=kexec@lists.infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=osandov@fb.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.