linux-kernel - Re: [PATCH 2/2] hw-breakpoint: Keep track of dr7 local enable bits

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Message-ID: <20100219180435.GB4736@in.ibm.com>
Date:	Fri, 19 Feb 2010 23:34:35 +0530
From:	"K.Prasad" <prasad@...ux.vnet.ibm.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Michael Stefaniuc <mstefani@...hat.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Maneesh Soni <maneesh@...ux.vnet.ibm.com>,
	Alexandre Julliard <julliard@...ehq.org>,
	"Rafael J . Wysocki" <rjw@...k.pl>,
	Maciej Rutecki <maciej.rutecki@...il.com>,
	Roland McGrath <roland@...hat.com>
Subject: Re: [PATCH 2/2] hw-breakpoint: Keep track of dr7 local enable bits

On Fri, Feb 19, 2010 at 06:41:53PM +0100, Frederic Weisbecker wrote:
> On Fri, Feb 19, 2010 at 02:28:31PM +0530, K.Prasad wrote:
> > On Thu, Feb 18, 2010 at 07:00:01PM +0100, Frederic Weisbecker wrote:
> > 
> > > diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
> > > index 017d937..0c1033d 100644
> > > --- a/arch/x86/kernel/ptrace.c
> > > +++ b/arch/x86/kernel/ptrace.c
> > > @@ -702,7 +702,7 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
> > >  	} else if (n == 6) {
> > >  		val = thread->debugreg6;
> > >  	 } else if (n == 7) {
> > > -		val = ptrace_get_dr7(thread->ptrace_bps);
> > > +		val = thread->ptrace_dr7;
> > 
> > Some more comments that I missed out in the previous mail...
> > 
> > Shouldn't ptrace_get_dr7() function be entirely removed now, given that
> > its only caller no longer invokes it?
> > 
> > >  	}
> > >  	return val;
> > >  }
> > > @@ -778,8 +778,11 @@ int ptrace_set_debugreg(struct task_struct *tsk, int n, unsigned long val)
> > >  			return rc;
> > >  	}
> > >  	/* All that's left is DR7 */
> > > -	if (n == 7)
> > > +	if (n == 7) {
> > >  		rc = ptrace_write_dr7(tsk, val);
> > 
> > And ptrace_write_dr7() should be made to populate thread->ptrace_dr7 if
> > it is going to return a success.
> > 
> > > +		if (!rc)
> > > +			thread->ptrace_dr7 = val;
> > > +	}
> > > 
> > >  ret_path:
> > >  	return rc;
> > > -- 
> > > 1.6.2.3
> > > 
> > 
> > Thanks,
> > K.Prasad
> > 
> 
> 
> This is urgent so I'm pushing the two patches right away as they fix the
> regression and are not intrusive.
> 
> Let's further improve that later, for a merge window, ok?
> 
> Thanks.
>

Sure, please go ahead with the patch.

Thanks,
K.Prasad
 
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