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

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Message-ID: <20160216103028.GA10730@linux.vnet.ibm.com>
Date:	Tue, 16 Feb 2016 16:00:30 +0530
From:	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>
To:	Torsten Duwe <duwe@....de>
Cc:	Petr Mladek <pmladek@...e.com>,
	Balbir Singh <bsingharora@...il.com>,
	Jessica Yu <jeyu@...hat.com>, linux-kernel@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Jiri Kosina <jkosina@...e.cz>, 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

* Torsten Duwe <duwe@....de> [2016-02-16 09:23:02]:

> On Tue, Feb 16, 2016 at 11:17:02AM +0530, Kamalesh Babulal wrote:
> > * Petr Mladek <pmladek@...e.com> [2016-02-12 17:45:17]:
> > >  int test(int a)
> > >  {
> > > +	printk("%d\n", a);
> > >  	return ++a;
> > >  }
> > 
> > Thanks. This workaround, helped to load sample livepatch module.
> 
> N.b.: if you try to livepatch/trace such a leaf function without
> global dependencies, it will crash if that function got called with
> a different TOC value. Hence this whole testing.
> 

I am running out of ideas on how to generate this crash, any pointers
will be helpful.

> You may alternatively try my gcc patch ;-)

Thank you. I will give the patch a try.

Regards,
Kamalesh