From: Paul Durrant <xadimgnik@gmail.com>
To: "'Jan Beulich'" <jbeulich@suse.com>,
"'Andrew Cooper'" <andrew.cooper3@citrix.com>
Cc: "'Wei Liu'" <wl@xen.org>,
"'Konrad Rzeszutek Wilk'" <konrad.wilk@oracle.com>,
"'Ross Lagerwall'" <ross.lagerwall@citrix.com>,
"'Pawel Wieczorkiewicz'" <wipawel@amazon.de>,
'Xen-devel' <xen-devel@lists.xenproject.org>,
"'Roger Pau Monné'" <roger.pau@citrix.com>
Subject: RE: [PATCH v2 for-4.14] x86/livepatch: Make livepatching compatible with CET Shadow Stacks
Date: Fri, 26 Jun 2020 14:21:55 +0100 [thread overview]
Message-ID: <000c01d64bbc$c3f75730$4be60590$@xen.org> (raw)
In-Reply-To: <af00d3ae-eba1-43dd-f8b7-d800e53c197b@suse.com>
> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 26 June 2020 14:15
> To: Andrew Cooper <andrew.cooper3@citrix.com>
> Cc: Xen-devel <xen-devel@lists.xenproject.org>; Wei Liu <wl@xen.org>; Roger Pau Monné
> <roger.pau@citrix.com>; Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>; Ross Lagerwall
> <ross.lagerwall@citrix.com>; Pawel Wieczorkiewicz <wipawel@amazon.de>; Paul Durrant <paul@xen.org>
> Subject: Re: [PATCH v2 for-4.14] x86/livepatch: Make livepatching compatible with CET Shadow Stacks
>
> On 26.06.2020 14:24, Andrew Cooper wrote:
> > Just like the alternatives infrastructure, the livepatch infrastructure
> > disables CR0.WP to perform patching, which is not permitted with CET active.
> >
> > Modify arch_livepatch_{quiesce,revive}() to disable CET before disabling WP,
> > and reset the dirty bits on all virtual regions before re-enabling CET.
> >
> > One complication is that arch_livepatch_revive() has to fix up the top of the
> > shadow stack. This depends on the functions not being inlined, even under
> > LTO. Another limitation is that reset_virtual_region_perms() may shatter the
> > final superpage of .text depending on alignment.
> >
> > This logic, and its downsides, are temporary until the patching infrastructure
> > can be adjusted to not use CR0.WP.
>
> In particular on this basis ...
>
> > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Paul Durrant <paul@xen.org>
>
> Jan
next prev parent reply other threads:[~2020-06-26 13:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-26 12:24 [PATCH v2 for-4.14] x86/livepatch: Make livepatching compatible with CET Shadow Stacks Andrew Cooper
2020-06-26 13:14 ` Jan Beulich
2020-06-26 13:21 ` Paul Durrant [this message]
2020-06-26 13:59 ` Ross Lagerwall
2020-06-26 14:26 ` Jan Beulich
2020-06-26 14:46 ` Andrew Cooper
2020-06-26 14:49 ` Jan Beulich
2020-06-26 15:07 ` Ross Lagerwall
2020-06-26 15:08 ` Andrew Cooper
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