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From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"mingo@elte.hu" <mingo@elte.hu>, Jiri Olsa <jolsa@redhat.com>,
	Salman Qazi <sqazi@google.com>,
	"ak@linux.intel.com" <ak@linux.intel.com>
Subject: Re: [PATCH] perf,x86: fix uninitialized pt_regs in intel_pmu_drain_bts_buffer()
Date: Tue, 19 Mar 2013 13:58:22 +0100	[thread overview]
Message-ID: <1363697902.22553.43.camel@laptop> (raw)
In-Reply-To: <CABPqkBSmVzk=0nvHiuk-+XSfNX8ODXWKeJ+jUu2482=NvMoghg@mail.gmail.com>

On Tue, 2013-03-19 at 13:50 +0100, Stephane Eranian wrote:
> > Should we not replace:
> >
> >         regs.ip     = 0;
> >
> > with that memset? It avoids the memset work in a few cases and
> removes
> > the then superfluous clearing of the IP field.
> >
> We could drop it because it's covered by the memset().

Yeah, but also place the memset a little lower than you did, avoids the
stack writes when not needed.

> The issue here was that you eventually end up in code_segment_base()
> which
> looks at other uninitialized fields in pt_regs and may cause breakage.

Right, your changelog said so ;-)


  reply	other threads:[~2013-03-19 12:58 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-18 13:46 [PATCH] perf,x86: fix uninitialized pt_regs in intel_pmu_drain_bts_buffer() Stephane Eranian
2013-03-19 12:43 ` Peter Zijlstra
2013-03-19 12:50   ` Stephane Eranian
2013-03-19 12:58     ` Peter Zijlstra [this message]
2013-03-19 13:02       ` Stephane Eranian

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