From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v2 3/7] x86, ptrace: Ifdef HW_BREAKPOINTS code in ptrace
Date: Mon, 10 Mar 2014 15:35:22 +0100
Message-ID: <20140310143522.GB21735@redhat.com>
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Cc: kvm@vger.kernel.org, Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
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To: Josh Triplett <josh@joshtriplett.org>
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On 03/09, Josh Triplett wrote:
>
> +#ifdef CONFIG_HW_BREAKPOINTS
> +
>  static void ptrace_triggered(struct perf_event *bp,
>  			     struct perf_sample_data *data,
>  			     struct pt_regs *regs)
> @@ -778,6 +780,34 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n,
>  	return rc;
>  }
>
> +#else
> +
> +/* Without breakpoints only handle DR6 */
> +static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
> +{
> +	struct thread_struct *thread = &tsk->thread;
> +
> +	if (n == 6)
> +		return thread->debugreg6;
> +	return 0;
> +}
> +
> +/* Without breakpoints only handle DR6 */
> +static int ptrace_set_debugreg(struct task_struct *tsk, int n,
> +			       unsigned long val)
> +{
> +	struct thread_struct *thread = &tsk->thread;
> +	int rc = -EIO;
> +
> +	if (n == 6) {
> +		thread->debugreg6 = val;
> +		rc = 0;
> +	}
> +	return rc;
> +}
> +
> +#endif

OK, but then perhaps this patch should also make thread_struct->ptrace_bps[]
depend on CONFIG_HW_BREAKPOINTS ?

This needs more changes though. In particular, it seems it makes sense to
move flush_ptrace_hw_breakpoint() to x86/kernel/ptrace.c, so that it can
live in the same ifdef'ed section.

copy_threads() needs a cleanup anyway...

But I won't insist if you prefer to do this later.

Oleg.


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