linux-kernel - Re: [PATCH] livepatch: use FTRACE_OPS_FL

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Message-ID: <20141222174117.GB26666@treble.redhat.com>
Date:	Mon, 22 Dec 2014 11:41:17 -0600
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Petr Mladek <pmladek@...e.cz>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Seth Jennings <sjenning@...hat.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Vojtech Pavlik <vojtech@...e.cz>,
	Steven Rostedt <rostedt@...dmis.org>,
	Miroslav Benes <mbenes@...e.cz>,
	Christoph Hellwig <hch@...radead.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Andy Lutomirski <luto@...capital.net>,
	live-patching@...r.kernel.org, x86@...nel.org, kpatch@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] livepatch: use FTRACE_OPS_FL_IPMODIFY

On Mon, Dec 22, 2014 at 06:34:09PM +0100, Petr Mladek wrote:
> On Fri 2014-12-19 10:43:35, Petr Mladek wrote:
> > On Thu 2014-12-18 09:49:35, Josh Poimboeuf wrote:
> > > On Thu, Dec 18, 2014 at 08:55:21PM +0900, Masami Hiramatsu wrote:
> > > > (2014/12/17 2:58), Seth Jennings wrote:
> > > > > changes in v7:
> > > > > - TODO: set IPMODIFY (not a blocker to moving forward)
> > > > 
> > > > Why don't you set this?
> > > > IPMODIFY series are not completely applied yet, but you can already
> > > > use the flag. All you need is just set it :)
> > > 
> > > Yeah, I don't see any reason why we can't start using this flag now.
> > > How about we add this patch to the queue?
> > > 
> > > -->8--
> > > 
> > > Subject: livepatch: use FTRACE_OPS_FL_IPMODIFY
> > > 
> > > Use the FTRACE_OPS_FL_IPMODIFY flag to prevent conflicts with other
> > > ftrace users who also modify regs->ip.
> > > 
> > > Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> > 
> > It makes sense. The flag is available even in 3.19.
> > 
> > Reviewed-by: Petr Mladek <pmladek@...e.cz>
> 
> Feel free to keep the Reviewed-by if you fix the typo, see below.
> 
> > > ---
> > >  kernel/livepatch/core.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> > > index 0004a71..bdd99975 100644
> > > --- a/kernel/livepatch/core.c
> > > +++ b/kernel/livepatch/core.c
> > > @@ -640,7 +640,8 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
> > >  
> > >  	ops->private = func;
> > >  	ops->func = klp_ftrace_handler;
> > > -	ops->flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_DYNAMIC;
> > > +	ops->flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_DYNAMIC |
> > > +		     FTRACE_FL_IPMODIFY;
> 
> Heh, there is a typo. Please replace FTRACE_FL_IPMODIFY
> with FTRACE_OPS_FL_IPMODIFY ;-)

Argh!  At least the commit message is correct ;-)

I'll send out a v2.

> Best Regards,
> Petr
> 
> > >  	func->fops = ops;
> > >  	func->state = KLP_DISABLED;
> > >  
> > > -- 
> > > 2.1.0
> > > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe live-patching" in
> > the body of a message to majordomo@...r.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Josh
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