linux-kernel - Re: [PATCH 1/5] perf: Add hardware breakpoint address mask

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Message-ID: <20130420214632.GA6155@jshin-Toonie>
Date:	Sat, 20 Apr 2013 16:46:32 -0500
From:	Jacob Shin <jacob.shin@....com>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>, <x86@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	Jiri Olsa <jolsa@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/5] perf: Add hardware breakpoint address mask

On Sat, Apr 20, 2013 at 06:22:23PM +0200, Oleg Nesterov wrote:
> On 04/09, Jacob Shin wrote:
> >
> > @@ -612,6 +612,9 @@ static int hw_breakpoint_add(struct perf_event *bp, int flags)
> >  	if (!(flags & PERF_EF_START))
> >  		bp->hw.state = PERF_HES_STOPPED;
> >
> > +	if (bp->attr.bp_addr_mask && !arch_has_hw_breakpoint_addr_mask())
> > +		return -EOPNOTSUPP;
> > +
> 
> This is called by sched_in... Isn't it "too late" ?
> 
> Perhaps arch_validate_hwbkpt_settings() should validate mask/cpu_has_bpext?

Ah, yes okay. Should I do this for all the archs that HAVE_HW_BREAKPOINT ?

Or is creating HAVE_HW_BREAKPOINT_ADDR_MASK and in validate_hw_breakpoint:

  #ifndef HAVE_HW_BREAKPOINT_ADDR_MASK
  if (bp->attr.bp_addr_mask)
  	return -EOPNOTSUPP;
  #endif

Okay to do?


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