linux-kernel - Re: [PATCH 01/10] perf, trace: Remove IRQ-disable from perf/tracepoint interaction

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Date:	Mon, 24 May 2010 14:29:58 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/10] perf, trace: Remove IRQ-disable from
 perf/tracepoint interaction

On Sun, May 23, 2010 at 08:16:27PM +0200, Peter Zijlstra wrote:

> On Sun, 2010-05-23 at 22:11 +1000, Paul Mackerras wrote:
> > This is breaking on powerpc -- we don't have a "flags" element in
> > struct pt_regs.  What is it trying to do?  Get the interrupt enable
> > state, as local_irq_save(flags) would provide?
> 
> Yes, I fouled that up.
> 
> On x86 perf_arch_fetch_caller_regs() stores pt_regs::flags, which is the
> same as used in local_save_flags().
> 
> So to avoid another local_save_flags() for the ftrace code, I wanted to
> reuse it, and totally forgot the !x86 side of things.
> 
> Possibly we could remove the local_save_flags() from the
> perf_arch_fetch_caller_regs() as I'm not sure we actually use
> pt_regs::flags (Frederic?) and leave the ftrace thing to use
> local_save_flags().
> 
> Something like:

Yes, that works -- at least, it compiles and seems to run. :)

Acked-by: Paul Mackerras <paulus@...ba.org>

Paul.
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