linux-kernel - Re: [PATCH v8 8/8] livepatch: Detect offset for the ftrace location during build

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Message-ID: <56CD925E.4060000@gmail.com>
Date:	Wed, 24 Feb 2016 22:22:06 +1100
From:	Balbir Singh <bsingharora@...il.com>
To:	Torsten Duwe <duwe@....de>
Cc:	Michael Ellerman <mpe@...erman.id.au>,
	Petr Mladek <pmladek@...e.com>, Jessica Yu <jeyu@...hat.com>,
	Jiri Kosina <jkosina@...e.cz>, linux-kernel@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	live-patching@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v8 8/8] livepatch: Detect offset for the ftrace location
 during build



On 24/02/16 20:23, Torsten Duwe wrote:
> On Wed, Feb 24, 2016 at 05:55:35PM +1100, Balbir Singh wrote:
>> <snip>
>>
>> We need to remove the SQUASH_TOC_SAVE_INSNS bits as well, now that the ppc64_profile_stub_insns does not save r2
> Sure -- this was meant to _replace_ the changes from patch 2/8, not on top.
> And yes, it exposes duplicate definitions, but does not cause them AFAICS.
> The two unasked questions about it were: Is Michael's solution on a similar
> basis? Is this worth any further effort e.g. put into v9?
>
>
My bad you did mention _replace_, but I think 2/8 and 6/8 of tightly bound
together, so the replacement is not straight forward. Yes, it is heading in
a similar direction, but it focuses mostly on ftrace. I think v9 makes sense,
but I'll let Michael comment on this as well]

Personally, I think your v8 or v9 + Michael's changes - RECORD_C_MCOUNT +
some changes (yet to code them based on v8/v9/ftrace stability) should get
the full live patching working.

Balbir Singh.