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From: "Wieczorkiewicz, Pawel" <wipawel@amazon.de>
To: Julien Grall <julien.grall@arm.com>
Cc: "Tim Deegan" <tim@xen.org>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wl@xen.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"George Dunlap" <George.Dunlap@eu.citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ross Lagerwall" <ross.lagerwall@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	xen-devel <xen-devel@lists.xen.org>,
	"Pohlack, Martin" <mpohlack@amazon.de>,
	"Wieczorkiewicz, Pawel" <wipawel@amazon.de>,
	"Jan Beulich" <jbeulich@suse.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 09/14] livepatch: Add per-function applied/reverted state tracking marker
Date: Thu, 22 Aug 2019 07:44:50 +0000
Message-ID: <BEEC1E7D-4A4D-406E-97C3-D5433BAE8CAF@amazon.com> (raw)
In-Reply-To: <680c5b24-b3fd-97b6-c048-49a2bdba4a3d@arm.com>

[-- Attachment #1.1: Type: text/plain, Size: 2264 bytes --]


On 21. Aug 2019, at 23:34, Julien Grall <julien.grall@arm.com<mailto:julien.grall@arm.com>> wrote:

Hi Pawel,

Hi Julien,


On 8/21/19 9:19 AM, Pawel Wieczorkiewicz wrote:
Livepatch only tracks an entire payload applied/reverted state. But,
with an option to supply the apply_payload() and/or revert_payload()
functions as optional hooks, it becomes possible to intermix the
execution of the original apply_payload()/revert_payload() functions
with their dynamically supplied counterparts.
It is important then to track the current state of every function
being patched and prevent situations of unintentional double-apply
or unapplied revert.
To support that, it is necessary to extend public interface of the
livepatch. The struct livepatch_func gets additional field holding
the applied/reverted state marker.
To reflect the livepatch payload ABI change, bump the version flag
LIVEPATCH_PAYLOAD_VERSION up to 2.
The above solution only applies to x86 architecture for now.

Is this going to break livepatch on Arm? If so, do you have any plan to fix it?


No, I do not think it is. But, I am unable to test on Arm (No access to HW and SW),
so I took the conservative approach here.

[...]

diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h
index 2aec532ee2..a93126f631 100644
--- a/xen/include/xen/livepatch.h
+++ b/xen/include/xen/livepatch.h
@@ -117,7 +117,7 @@ int arch_livepatch_quiesce(void);
 void arch_livepatch_revive(void);
   void arch_livepatch_apply(struct livepatch_func *func);
-void arch_livepatch_revert(const struct livepatch_func *func);
+void arch_livepatch_revert(struct livepatch_func *func);

I doubt livepatch on Arm will compile after this change.


What would be you suggestion then?
Shall I limit the change to X86 everywhere
 Or maybe drop the compilation flag completely?

 void arch_livepatch_post_action(void);
   void arch_livepatch_mask(void);

Cheers,

--
Julien Grall

Best Regards,
Pawel Wieczorkiewicz






Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879



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<div>
<blockquote type="cite" class="">
<div class="">On 21. Aug 2019, at 23:34, Julien Grall &lt;<a href="mailto:julien.grall@arm.com" class="">julien.grall@arm.com</a>&gt; wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="">Hi Pawel,<br class="">
</div>
</div>
</blockquote>
<div><br class="">
</div>
<div>Hi Julien,</div>
<br class="">
<blockquote type="cite" class="">
<div class="">
<div class=""><br class="">
On 8/21/19 9:19 AM, Pawel Wieczorkiewicz wrote:<br class="">
<blockquote type="cite" class="">Livepatch only tracks an entire payload applied/reverted state. But,<br class="">
with an option to supply the apply_payload() and/or revert_payload()<br class="">
functions as optional hooks, it becomes possible to intermix the<br class="">
execution of the original apply_payload()/revert_payload() functions<br class="">
with their dynamically supplied counterparts.<br class="">
It is important then to track the current state of every function<br class="">
being patched and prevent situations of unintentional double-apply<br class="">
or unapplied revert.<br class="">
To support that, it is necessary to extend public interface of the<br class="">
livepatch. The struct livepatch_func gets additional field holding<br class="">
the applied/reverted state marker.<br class="">
To reflect the livepatch payload ABI change, bump the version flag<br class="">
LIVEPATCH_PAYLOAD_VERSION up to 2.<br class="">
The above solution only applies to x86 architecture for now.<br class="">
</blockquote>
<br class="">
Is this going to break livepatch on Arm? If so, do you have any plan to fix it?<br class="">
<br class="">
</div>
</div>
</blockquote>
<div><br class="">
</div>
<div>No, I do not think it is. But, I am unable to test on Arm (No access to HW and SW),</div>
<div>so I took the conservative approach here.</div>
<br class="">
<blockquote type="cite" class="">
<div class="">
<div class="">[...]<br class="">
<br class="">
<blockquote type="cite" class="">diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h<br class="">
index 2aec532ee2..a93126f631 100644<br class="">
--- a/xen/include/xen/livepatch.h<br class="">
&#43;&#43;&#43; b/xen/include/xen/livepatch.h<br class="">
@@ -117,7 +117,7 @@ int arch_livepatch_quiesce(void);<br class="">
&nbsp;void arch_livepatch_revive(void);<br class="">
&nbsp;&nbsp;&nbsp;void arch_livepatch_apply(struct livepatch_func *func);<br class="">
-void arch_livepatch_revert(const struct livepatch_func *func);<br class="">
&#43;void arch_livepatch_revert(struct livepatch_func *func);<br class="">
</blockquote>
<br class="">
I doubt livepatch on Arm will compile after this change.<br class="">
<br class="">
</div>
</div>
</blockquote>
<div><br class="">
</div>
<div>What would be you suggestion then?</div>
<div>Shall I limit the change to X86 everywhere</div>
<div>&nbsp;Or maybe drop the compilation flag completely?</div>
<br class="">
<blockquote type="cite" class="">
<div class="">
<div class="">
<blockquote type="cite" class="">&nbsp;void arch_livepatch_post_action(void);<br class="">
&nbsp;&nbsp;&nbsp;void arch_livepatch_mask(void);<br class="">
</blockquote>
<br class="">
Cheers,<br class="">
<br class="">
-- <br class="">
Julien Grall<br class="">
</div>
</div>
</blockquote>
</div>
<br class="">
<div class="">
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">
<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
Best Regards,<br class="">
Pawel Wieczorkiewicz</div>
<br class="Apple-interchange-newline">
</div>
<br class="Apple-interchange-newline">
</div>
<br class="">
<br><br><br>Amazon Development Center Germany GmbH
<br>Krausenstr. 38
<br>10117 Berlin
<br>Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
<br>Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
<br>Sitz: Berlin
<br>Ust-ID: DE 289 237 879
<br><br><br>
</body>
</html>

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Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-21  8:19 [Xen-devel] [PATCH 00/14] livepatch: new features and fixes Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 01/14] livepatch: Always check hypervisor build ID upon hotpatch upload Pawel Wieczorkiewicz
2019-08-21 18:16   ` Konrad Rzeszutek Wilk
2019-08-21  8:19 ` [Xen-devel] [PATCH 02/14] livepatch: Allow to override inter-modules buildid dependency Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 03/14] python: Add XC binding for Xen build ID Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 04/14] livepatch: Export payload structure via livepatch_payload.h Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 05/14] livepatch: Implement pre-|post- apply|revert hooks Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 06/14] livepatch: Add support for apply|revert action replacement hooks Pawel Wieczorkiewicz
2019-08-21 18:31   ` Konrad Rzeszutek Wilk
2019-08-21 19:06     ` Wieczorkiewicz, Pawel
2019-08-26 14:30       ` Konrad Rzeszutek Wilk
2019-08-21  8:19 ` [Xen-devel] [PATCH 07/14] livepatch: Do not enforce ELF_LIVEPATCH_FUNC section presence Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 08/14] livepatch: always print XENLOG_ERR information Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 09/14] livepatch: Add per-function applied/reverted state tracking marker Pawel Wieczorkiewicz
2019-08-21 18:28   ` Konrad Rzeszutek Wilk
2019-08-21 19:00     ` Wieczorkiewicz, Pawel
2019-08-21 21:34   ` Julien Grall
2019-08-22  7:44     ` Wieczorkiewicz, Pawel [this message]
2019-08-22 10:07       ` Julien Grall
2019-08-22 10:20         ` Wieczorkiewicz, Pawel
2019-08-22 10:43           ` Julien Grall
2019-08-22 11:15             ` Wieczorkiewicz, Pawel
2019-08-22 15:02               ` Julien Grall
2019-08-22 10:29   ` Julien Grall
2019-08-22 11:02     ` Wieczorkiewicz, Pawel
2019-08-22 15:30       ` Julien Grall
2019-08-22 15:42         ` Wieczorkiewicz, Pawel
2019-08-21  8:19 ` [Xen-devel] [PATCH 10/14] livepatch: Add support for inline asm hotpatching expectations Pawel Wieczorkiewicz
2019-08-21 18:30   ` Konrad Rzeszutek Wilk
2019-08-21 19:02     ` Wieczorkiewicz, Pawel
2019-08-22 10:31   ` Julien Grall
2019-08-22 11:03     ` Wieczorkiewicz, Pawel
2019-08-21  8:19 ` [Xen-devel] [PATCH 11/14] livepatch: Add support for modules .modinfo section metadata Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 12/14] livepatch: Handle arbitrary size names with the list operation Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 13/14] livepatch: Add metadata runtime retrieval mechanism Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 14/14] livepatch: Add python bindings for livepatch operations Pawel Wieczorkiewicz
2019-08-22 21:55   ` Marek Marczykowski-Górecki
2019-08-27  8:46 ` [Xen-devel] [PATCH v2 00/12] livepatch: new features and fixes Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 01/12] livepatch: Always check hypervisor build ID upon hotpatch upload Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 02/12] livepatch: Allow to override inter-modules buildid dependency Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 03/12] livepatch: Export payload structure via livepatch_payload.h Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 04/12] livepatch: Implement pre-|post- apply|revert hooks Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 05/12] livepatch: Add support for apply|revert action replacement hooks Pawel Wieczorkiewicz
2019-08-27 16:58     ` Konrad Rzeszutek Wilk
2019-08-28  7:37       ` Wieczorkiewicz, Pawel
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 06/12] livepatch: Do not enforce ELF_LIVEPATCH_FUNC section presence Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 07/12] livepatch: Add per-function applied/reverted state tracking marker Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 08/12] livepatch: Add support for inline asm hotpatching expectations Pawel Wieczorkiewicz
2019-08-29 14:34     ` Konrad Rzeszutek Wilk
2019-08-29 15:29       ` Wieczorkiewicz, Pawel
2019-08-29 15:58     ` Konrad Rzeszutek Wilk
2019-08-29 16:16       ` Wieczorkiewicz, Pawel
2019-08-29 17:49         ` Konrad Rzeszutek Wilk
2019-08-29 19:07           ` Wieczorkiewicz, Pawel
2019-08-29 20:48             ` Konrad Rzeszutek Wilk
2019-09-05 18:05     ` Konrad Rzeszutek Wilk
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 09/12] livepatch: Add support for modules .modinfo section metadata Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 10/12] livepatch: Handle arbitrary size names with the list operation Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 11/12] livepatch: Add metadata runtime retrieval mechanism Pawel Wieczorkiewicz
2019-08-29 20:48     ` Konrad Rzeszutek Wilk
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 12/12] livepatch: Add python bindings for livepatch operations Pawel Wieczorkiewicz
2019-08-28 13:21     ` Marek Marczykowski-Górecki
2019-08-29 19:23   ` [Xen-devel] [PATCH v2 00/12] livepatch: new features and fixes Konrad Rzeszutek Wilk
2019-09-05 19:13   ` Konrad Rzeszutek Wilk
2019-09-06 22:52     ` Julien Grall
2019-09-06 22:42   ` Julien Grall

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