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

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Message-ID: <20100219085831.GA10837@in.ibm.com>
Date:	Fri, 19 Feb 2010 14:28:31 +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 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

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