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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160216082302.GA20522@lst.de>
Date:	Tue, 16 Feb 2016 09:23:02 +0100
From:	Torsten Duwe <duwe@....de>
To:	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>
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

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.

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