linux-kernel - Re: [PATCH v5 3.1.0-rc4-tip 13/26] x86: define a x86 specific exception notifier.

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Date:	Tue, 27 Sep 2011 13:46:15 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Hugh Dickins <hughd@...gle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Jonathan Corbet <corbet@....net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...k.frob.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v5 3.1.0-rc4-tip 13/26] x86: define a x86 specific
 exception notifier.

On Mon, 2011-09-26 at 21:22 +0530, Srikar Dronamraju wrote:
> * Peter Zijlstra <peterz@...radead.org> [2011-09-26 16:19:51]:
> 
> > On Tue, 2011-09-20 at 17:32 +0530, Srikar Dronamraju wrote:
> > > @@ -820,6 +821,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
> > >                 mce_notify_process();
> > >  #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
> > >  
> > > +       if (thread_info_flags & _TIF_UPROBE) {
> > > +               clear_thread_flag(TIF_UPROBE);
> > > +#ifdef CONFIG_X86_32
> > > +               /*
> > > +                * On x86_32, do_notify_resume() gets called with
> > > +                * interrupts disabled. Hence enable interrupts if they
> > > +                * are still disabled.
> > > +                */
> > > +               local_irq_enable();
> > > +#endif
> > > +               uprobe_notify_resume(regs);
> > > +       }
> > > +
> > >         /* deal with pending signal delivery */
> > >         if (thread_info_flags & _TIF_SIGPENDING)
> > >                 do_signal(regs); 
> > 
> > It would be good to remove this difference between i386 and x86_64.
> 
> 
> I think, we have already discussed this. I tried getting to know why we
> have this difference in behaviour. However I havent been able to find
> the answer.
> 
> If you can get somebody to answer this, I would be happy to modify as
> required.

The Changelog failed to mention this. Afaict there really is no reason
other than that touching entry_32.S is a pain.
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