In-Reply-To: <1460552003-15409-3-git-send-email-mpe@ellerman.id.au>
To: Michael Ellerman <mpe@ellerman.id.au>, <linuxppc-dev@ozlabs.org>
From: Michael Ellerman <mpe@ellerman.id.au>
Cc: pmladek@suse.com, jeyu@redhat.com, jikos@kernel.org,
        linux-kernel@vger.kernel.org, rostedt@goodmis.org,
        kamalesh@linux.vnet.ibm.com, duwe@lst.de,
        live-patching@vger.kernel.org, mbenes@suse.cz
Subject: Re: [2/5] livepatch: Allow architectures to specify an alternate ftrace location
Message-Id: <3qq1Bj3wbTz9t8k@ozlabs.org>
Date: Tue, 19 Apr 2016 20:16:29 +1000 (AEST)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 818
Lines: 20

On Wed, 2016-13-04 at 12:53:20 UTC, Michael Ellerman wrote:
> When livepatch tries to patch a function it takes the function address
> and asks ftrace to install the livepatch handler at that location.
> ftrace will look for an mcount call site at that exact address.
> 
> On powerpc the mcount location is not the first instruction of the
> function, and in fact it's not at a constant offset from the start of
> the function. To accommodate this add a hook which arch code can
> override to customise the behaviour.
> 
> Signed-off-by: Torsten Duwe <duwe@suse.de>
> Signed-off-by: Balbir Singh <bsingharora@gmail.com>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Applied to powerpc next.

https://git.kernel.org/powerpc/c/28e7cbd3e0f5fefec892842d13

cheers