linux-kernel - Re: [PATCH] reduce the time of finding symbols for module

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Message-ID: <20171013131841.en3yuwtl3wedei5t@suse.de>
Date:   Fri, 13 Oct 2017 15:18:41 +0200
From:   Torsten Duwe <duwe@...e.de>
To:     Ruslan Bilovol <ruslan.bilovol@...il.com>
Cc:     Li Bin <huawei.libin@...wei.com>, Jessica Yu <jeyu@...hat.com>,
        Miroslav Benes <mbenes@...e.cz>,
        zhouchengming <zhouchengming1@...wei.com>,
        live-patching@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        jpoimboe@...hat.com, jikos@...nel.org, pmladek@...e.com,
        Zefan Li <lizefan@...wei.com>,
        Hanjun Guo <guohanjun@...wei.com>, rbilovol@...co.com
Subject: Re: [PATCH] reduce the time of finding symbols for module

On Fri, Oct 13, 2017 at 03:54:46PM +0300, Ruslan Bilovol wrote:
> Hi Li,
> 
> On Wed, Mar 29, 2017 at 4:50 AM, Li Bin <huawei.libin@...wei.com> wrote:
> > Hi,
> [snip]
> >
> > Yeah, from 2014, we started to work on livepatch support on aarch64, and
> > in May 2015, we pushed the solution to the livepatch community[1] and gcc
> > community (mfentry feature on aarch64)[2]. And then, there were an another
> > gcc solution from linaro [3], which proposes to implement a new option
> > -fprolog-pad=N that generate a pad of N nops at the beginning of each
> > function, and AFAIK, Torsten Duwe from SUSE is still discussing this method
> > with gcc community.
> >
> > At this stage, we are validating the livepatch support on aarch64 based on
> > aarch64 mfentry feature. When the community has a clear plan, we are happy
> > to make adaptation and contribute our related work to the community, including
> > the kpatch-build support :-)
> >
> > [1] livepatch: add support on arm64
> > https://lkml.org/lkml/2015/5/28/54
> > [2] [AArch64] support -mfentry feature for arm64
> > https://gcc.gnu.org/ml/gcc-patches/2016-03/msg00756.html
> > [3] Kernel livepatching support in GCC
> > https://gcc.gnu.org/ml/gcc/2015-05/msg00267.html
> > [4] arm64: ftrace with regs for livepatch support
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/401352.html
> >
> 
> Since there is already -fpatchable-function-entry option committed by Torsten
> to gcc on 25 Jul [1], have you restarted your activities with AArch64 livepatch
> support?
> If yes, I'm interested in testing of that feature/patches on our hardware

I also have the coresponding kernel patch(es) here. IIRC I already sent
tham to LKML. I'll re-send them once there are more gcc's with -fpatchable-function-entry 
support out there.

	Torsten