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From: ebiederm@xmission.com (Eric W. Biederman)
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: keir@xen.org, Kees Cook <keescook@chromium.org>,
	Richard Weinberger <richard.weinberger@gmail.com>,
	Richard Weinberger <richard@nod.at>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	kexec@lists.infradead.org, LKML <linux-kernel@vger.kernel.org>,
	xen-devel@lists.xen.org, hbabu@us.ibm.com,
	david.vrabel@citrix.com, jbeulich@suse.com,
	"H. Peter Anvin" <hpa@linux.intel.com>,
	Vivek Goyal <vgoyal@redhat.com>
Subject: Re: kexec: Clearing registers just before jumping into purgatory
Date: Fri, 11 Oct 2013 13:44:19 -0700	[thread overview]
Message-ID: <87ob6va670.fsf@tw-ebiederman.twitter.com> (raw)
In-Reply-To: <20131011170138.GA32619@srcf.ucam.org> (Matthew Garrett's message of "Fri, 11 Oct 2013 18:01:39 +0100")

Matthew Garrett <mjg59@srcf.ucam.org> writes:

> On Fri, Oct 11, 2013 at 06:59:41PM +0200, Richard Weinberger wrote:
>> Am 11.10.2013 18:55, schrieb Matthew Garrett:
>> > On Fri, Oct 11, 2013 at 06:47:19PM +0200, Richard Weinberger wrote:
>> > 
>> >> But you still need a magic tool which create you this list.
>> > 
>> > I just read /proc/kallsyms. I'm really not doing anything complicated.
>> > 
>> >> If you have a tool which takes two kernel images and create such
>> >> a delta, fine.
>> > 
>> > Isn't that ksplice?
>> 
>> So, you have a variant of ksplice which is able to kexec?
>
> No, I manually look up some addresses from /proc/kallsyms and then 
> modify them in the second kernel.

An interesting approach I think most of the rest of us would have just
built a module, or rebuilt our kernels.

Now if this is a backwards argument to remove that silly code path it
totally fails because now we know the code has not bit-rotted and
that there are active users.

If you are still pushing the signed-boot agenda I eagerly await your
patches to make all of this work in a sensible way with signed binaries.

Eric


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

WARNING: multiple messages have this Message-ID (diff)
From: ebiederm@xmission.com (Eric W. Biederman)
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Richard Weinberger <richard@nod.at>,
	Richard Weinberger <richard.weinberger@gmail.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	hbabu@us.ibm.com, "H. Peter Anvin" <hpa@linux.intel.com>,
	Kees Cook <keescook@chromium.org>,
	kexec@lists.infradead.org, LKML <linux-kernel@vger.kernel.org>,
	david.vrabel@citrix.com, jbeulich@suse.com, keir@xen.org,
	xen-devel@lists.xen.org
Subject: Re: kexec: Clearing registers just before jumping into purgatory
Date: Fri, 11 Oct 2013 13:44:19 -0700	[thread overview]
Message-ID: <87ob6va670.fsf@tw-ebiederman.twitter.com> (raw)
In-Reply-To: <20131011170138.GA32619@srcf.ucam.org> (Matthew Garrett's message of "Fri, 11 Oct 2013 18:01:39 +0100")

Matthew Garrett <mjg59@srcf.ucam.org> writes:

> On Fri, Oct 11, 2013 at 06:59:41PM +0200, Richard Weinberger wrote:
>> Am 11.10.2013 18:55, schrieb Matthew Garrett:
>> > On Fri, Oct 11, 2013 at 06:47:19PM +0200, Richard Weinberger wrote:
>> > 
>> >> But you still need a magic tool which create you this list.
>> > 
>> > I just read /proc/kallsyms. I'm really not doing anything complicated.
>> > 
>> >> If you have a tool which takes two kernel images and create such
>> >> a delta, fine.
>> > 
>> > Isn't that ksplice?
>> 
>> So, you have a variant of ksplice which is able to kexec?
>
> No, I manually look up some addresses from /proc/kallsyms and then 
> modify them in the second kernel.

An interesting approach I think most of the rest of us would have just
built a module, or rebuilt our kernels.

Now if this is a backwards argument to remove that silly code path it
totally fails because now we know the code has not bit-rotted and
that there are active users.

If you are still pushing the signed-boot agenda I eagerly await your
patches to make all of this work in a sensible way with signed binaries.

Eric


  reply	other threads:[~2013-10-11 20:48 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-11  9:28 kexec: Clearing registers just before jumping into purgatory Daniel Kiper
2013-10-11  9:28 ` Daniel Kiper
2013-10-11 10:08 ` Eric W. Biederman
2013-10-11 10:08   ` Eric W. Biederman
2013-10-11 11:04   ` Daniel Kiper
2013-10-11 11:04     ` Daniel Kiper
2013-10-11 12:52     ` Vivek Goyal
2013-10-11 12:52     ` Vivek Goyal
2013-10-11 12:52       ` Vivek Goyal
2013-10-11 15:37       ` Matthew Garrett
2013-10-11 15:37         ` Matthew Garrett
2013-10-11 15:44         ` Vivek Goyal
2013-10-11 15:44         ` Vivek Goyal
2013-10-11 15:44           ` Vivek Goyal
2013-10-11 15:48           ` Matthew Garrett
2013-10-11 15:48           ` Matthew Garrett
2013-10-11 15:48             ` Matthew Garrett
2013-10-11 16:33             ` Richard Weinberger
2013-10-11 16:33             ` Richard Weinberger
2013-10-11 16:33               ` Richard Weinberger
2013-10-11 16:39               ` Matthew Garrett
2013-10-11 16:39               ` Matthew Garrett
2013-10-11 16:39                 ` Matthew Garrett
2013-10-11 16:42                 ` Richard Weinberger
2013-10-11 16:42                 ` Richard Weinberger
2013-10-11 16:42                   ` Richard Weinberger
2013-10-11 16:44                   ` Matthew Garrett
2013-10-11 16:44                     ` Matthew Garrett
2013-10-11 16:47                     ` Richard Weinberger
2013-10-11 16:47                     ` Richard Weinberger
2013-10-11 16:47                       ` Richard Weinberger
2013-10-11 16:55                       ` Matthew Garrett
2013-10-11 16:55                       ` Matthew Garrett
2013-10-11 16:55                         ` Matthew Garrett
2013-10-11 16:59                         ` Richard Weinberger
2013-10-11 16:59                           ` Richard Weinberger
2013-10-11 17:01                           ` Matthew Garrett
2013-10-11 17:01                             ` Matthew Garrett
2013-10-11 20:44                             ` Eric W. Biederman [this message]
2013-10-11 20:44                               ` Eric W. Biederman
2013-10-11 20:50                               ` Matthew Garrett
2013-10-11 20:50                               ` Matthew Garrett
2013-10-11 20:50                                 ` Matthew Garrett
2013-10-11 20:44                             ` Eric W. Biederman
2013-10-11 17:01                           ` Matthew Garrett
2013-10-11 16:59                         ` Richard Weinberger
2013-10-11 16:53                     ` Vivek Goyal
2013-10-11 16:53                       ` Vivek Goyal
2013-10-11 16:56                       ` Matthew Garrett
2013-10-11 16:56                       ` Matthew Garrett
2013-10-11 16:56                         ` Matthew Garrett
2013-10-11 16:53                     ` Vivek Goyal
2013-10-11 16:44                   ` Matthew Garrett
2013-10-11 15:37       ` Matthew Garrett
2013-10-11 22:15     ` Eric W. Biederman
2013-10-11 22:15       ` Eric W. Biederman
2013-10-14 18:24       ` Daniel Kiper
2013-10-14 18:24         ` Daniel Kiper
2013-10-14 18:24       ` Daniel Kiper
2013-10-11 22:15     ` Eric W. Biederman
2013-10-11 11:04   ` Daniel Kiper
2013-10-11 10:08 ` Eric W. Biederman
  -- strict thread matches above, loose matches on Subject: below --
2013-10-11  9:28 Daniel Kiper

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