kexec fails to boot kernels where CONFIG_RANDOMIZE_BASE=y is set

[WANG Chao]

On 08/18/14 at 10:57am, Vivek Goyal wrote:
> Hi Thomas,
> 
> I think kexec is broken with CONFIG_RANDOMIZE_BASE=y. Chao had raised
> this issue some time back when this option was introduced. I don't
> remember the details though that why it is broken.

The following fix the problem for kdump case:

commit 0d52644
Author: WANG Chao <chaowang at redhat.com>
Date:   Fri Mar 28 15:05:00 2014 +0800

    x86, kaslr: add alternative way to locate kernel text mapping area


For kexec case, it hangs in purgatory:

[  556.859384] kexec: Starting new kernel
I'm in purgatory

> 
> CCing Kees Cook. 
> 
> Kees, is there a quick fix to the issue. Sooner or later people will
> start enabling CONFIG_RANDOMIZE_BASE=y and broken kexec will be a
> big issue.
> 
> Thanks
> Vivek
>  
> On Sun, Aug 17, 2014 at 11:02:58PM +0200, Thomas D. wrote:
> > Hi,
> > 
> > looks like kexec doesn't support kernels where
> > 
> >   CONFIG_RANDOMIZE_BASE=y
> > 
> > is set.
> > 
> > 
> > I already created a bug for Debian in June for this problem [1].
> > 
> > I am able to confirm the same problem with kexec 2.0.7 on Gentoo and
> > when building from source (943ba35f8143408d8ada9a24d0986663cc612df9).
> > 
> > Is this a known problem/limitation?
> > 
> > Is there anything I can help you with to get this fixed?
> > 
> > Thanks.
> > 
> > 
> > See also:
> > =========
> > [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=754288
> > 
> > 
> > -Thomas
> > 
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