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Date: Tue, 16 Feb 2016 09:23:02 +0100
From: Torsten Duwe <duwe@lst.de>
To: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>, Balbir Singh <bsingharora@gmail.com>,
        Jessica Yu <jeyu@redhat.com>, linux-kernel@vger.kernel.org,
        Steven Rostedt <rostedt@goodmis.org>, Jiri Kosina <jkosina@suse.cz>,
        live-patching@vger.kernel.org, Miroslav Benes <mbenes@suse.cz>,
        linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v8 8/8] livepatch: Detect offset for the ftrace
	location during build
Message-ID: <20160216082302.GA20522@lst.de>
References: <20160210174221.EBBEC692C8@newverein.lst.de> <20160210174517.8347D692C8@newverein.lst.de> <1455293609.16012.9.camel@gmail.com> <20160212164517.GO12548@pathway.suse.cz> <20160216054701.GA20570@linux.vnet.ibm.com>
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On Tue, Feb 16, 2016 at 11:17:02AM +0530, Kamalesh Babulal wrote:
> * Petr Mladek <pmladek@suse.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.

You may alternatively try my gcc patch ;-)

Another caveat is functions with stack arguments (>8 args, varargs).
My code needs special precautions then because of the return helper.

	Torsten