linux-kernel - Re: [RFC][PATCH 2/3] perf: Take a hot regs snapshot for trace events

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 03 Mar 2010 17:37:38 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	rostedt@...dmis.org
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [RFC][PATCH 2/3] perf: Take a hot regs snapshot for trace
 events

On Wed, 2010-03-03 at 11:06 -0500, Steven Rostedt wrote:
> On Wed, 2010-03-03 at 07:55 +0100, Frederic Weisbecker wrote:
> 
> > +/*
> >   * Output
> >   */
> >  static bool perf_output_space(struct perf_mmap_data *data, unsigned long tail,
> > @@ -4337,6 +4347,8 @@ static const struct pmu perf_ops_task_clock = {
> >  void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
> >  			  int entry_size)
> >  {
> > +	struct pt_regs regs;
> > +
> >  	struct perf_raw_record raw = {
> >  		.size = entry_size,
> >  		.data = record,
> > @@ -4347,14 +4359,11 @@ void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
> >  		.raw = &raw,
> >  	};
> >  
> > -	struct pt_regs *regs = get_irq_regs();
> > -
> > -	if (!regs)
> > -		regs = task_pt_regs(current);
> > +	PERF_SAVE_REGS(&regs);
> >  
> >  	/* Trace events already protected against recursion */
> >  	do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
> > -				&data, regs);
> > +				&data, &regs);
> 
> Off-topic: Why is the above a perf sw event? Couldn't that also be a
> normal TRACE_EVENT()?

Well, no, this is the stuff that transforms TRACE_EVENT() into perf
software events ;-)

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/