From: David Woodhouse <dwmw2@infradead.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Jan Beulich <jbeulich@suse.com>
Cc: xen-devel@lists.xenproject.org
Subject: Re: xen/link: Move .data.rel.ro sections into .rodata for final link
Date: Mon, 31 Jul 2017 00:18:56 +0100 [thread overview]
Message-ID: <1501456736.4771.219.camel@infradead.org> (raw)
In-Reply-To: <8d36dedc-3cd9-6a75-1c56-ed816185f7bf@citrix.com>
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On Sun, 2017-07-30 at 13:50 +0100, Andrew Cooper wrote:
> On 30/07/17 07:16, Jan Beulich wrote:
> >
> > >
> > > >
> > > > >
> > > > > David Woodhouse <dwmw2@infradead.org> 07/20/17 5:22 PM >>>
> > > This includes stuff lke the hypercall tables which we really want
> > > to be read-only. And they were going into .data.read-mostly.
> > Yes, we'd like them to be read-only, but what if EFI properly assigned r/o
> > permissions to the .rodata section when loading xen.efi? We'd then be
> > unable to apply relocations when switching from 1:1 to virtual mappings
> > (see efi_arch_relocate_image()).
> Ah yes. I'd overlooked that point when considering the ramifications of
> this change.
>
> efi_arch_relocate_image() should probably do the same as what we do with
> livepatching, and temporarily clear CR0.WP for the duration of the patching.
Hm, efi/mkreloc.c was already emitting relocations in the .rodata
section before this change. Are you saying that was already broken?
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next prev parent reply other threads:[~2017-07-30 23:19 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-20 15:20 xen/link: Move .data.rel.ro sections into .rodata for final link David Woodhouse
2017-07-20 16:46 ` Wei Liu
2017-07-20 16:54 ` Wei Liu
2017-07-21 10:43 ` Julien Grall
2017-07-21 16:41 ` Andrew Cooper
2017-07-25 9:21 ` [PATCH v2] " David Woodhouse
2017-07-30 6:16 ` Jan Beulich
2017-07-30 12:50 ` Andrew Cooper
2017-07-30 23:18 ` David Woodhouse [this message]
2017-07-31 9:57 ` Jan Beulich
2017-07-31 10:15 ` David Woodhouse
2017-07-31 9:55 ` Jan Beulich
2017-07-31 11:02 ` David Woodhouse
2017-07-31 13:15 ` Jan Beulich
2017-07-31 15:56 ` David Woodhouse
2017-08-02 9:17 ` Jan Beulich
2017-08-02 11:30 ` [PATCH] x86/efi: Do not write relocations in efi_arch_relocate_image() first pass David Woodhouse
2017-08-02 11:56 ` Jan Beulich
2017-08-02 12:11 ` David Woodhouse
2017-08-02 13:58 ` Jan Beulich
2017-08-02 14:45 ` David Woodhouse
2017-08-02 15:16 ` Jan Beulich
2017-08-02 15:56 ` David Woodhouse
2017-08-02 11:43 ` xen/link: Move .data.rel.ro sections into .rodata for final link David Woodhouse
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