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From: Petr Mladek <>
To: Steven Rostedt <>
	Masami Hiramatsu <>,
	Andrew Morton <>,
	Peter Zijlstra <>,
	Ingo Molnar <>,
	Josh Poimboeuf <>,
	Jiri Kosina <>, Miroslav Benes <>,
Subject: Re: [PATCH 3/3 v7] livepatch: Use the default ftrace_ops instead of REGS when ARGS is available
Date: Thu, 19 Nov 2020 17:07:50 +0100	[thread overview]
Message-ID: <X7aYVgRa5uP8sAMM@alley> (raw)
In-Reply-To: <20201119091235.60be696e@gandalf.local.home>

On Thu 2020-11-19 09:12:35, Steven Rostedt wrote:
> On Thu, 19 Nov 2020 12:52:00 +0100
> Petr Mladek <> wrote:
> > >  #ifdef CONFIG_LIVEPATCH
> > > -static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
> > > +static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip)
> > >  {
> > > +	struct pt_regs *regs = ftrace_get_regs(fregs);  
> > 
> > Should we check for NULL pointer here?
> As mentioned in my last email. regs could have been NULL for the same
> reasons before this patch, and we didn't check it then. Why should we check
> it now?
> The ftrace_get_regs() only makes sure that a ftrace_ops that set
> FL_SAVE_REGS gets it, and those that did not, don't.
> But that's not entirely true either. If there's two callbacks to the same
> function, and one has FL_SAVE_REGS set, they both can have access to the
> regs (before and after this patch). It's just that the one that did not
> have FL_SAVE_REGS set, isn't guaranteed to have it.

Makes sense. Thanks for explanation. Feel free to use:

Acked-by: Petr Mladek <>

I actually did review of all patches and they looked fine to me.
I just did not check all corner cases, assembly, and did not test
it, so I give it just my ack. I believe your testing ;-)

Best Regards,

      reply	other threads:[~2020-11-19 16:08 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2020-11-13 17:18 ` [PATCH 3/3 v7] livepatch: Use the default ftrace_ops instead of REGS when ARGS is available Steven Rostedt
2020-11-19 11:52   ` Petr Mladek
2020-11-19 14:12     ` Steven Rostedt
2020-11-19 16:07       ` Petr Mladek [this message]

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