Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934002AbbKSL3B (ORCPT ); Thu, 19 Nov 2015 06:29:01 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:53295 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932087AbbKSL3A (ORCPT ); Thu, 19 Nov 2015 06:29:00 -0500 Date: Thu, 19 Nov 2015 12:28:50 +0100 From: Peter Zijlstra To: "Wangnan (F)" Cc: Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , David Ahern , Milian Wolff , linux-kernel@vger.kernel.org, pi3orama , lizefan 00213767 Subject: Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction Message-ID: <20151119112850.GM3816@twins.programming.kicks-ass.net> References: <564C26C4.2040603@huawei.com> <564C3011.8090002@huawei.com> <20151118082033.GA24726@gmail.com> <564C3A0E.3030502@huawei.com> <564C3BAA.4040806@huawei.com> <20151119063709.GA14852@gmail.com> <564D6FF9.3030105@huawei.com> <20151119102300.GA2830@gmail.com> <564DA7C2.8060002@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <564DA7C2.8060002@huawei.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 688 Lines: 18 On Thu, Nov 19, 2015 at 06:43:14PM +0800, Wangnan (F) wrote: > Also, why not fixing rsp in kernel if that instruction is a 'callq'? > For avoiding instruction decoding? Why would the kernel do that? It doesn't need this. Have userspace do it when trying to interpret the data. If PERF_EFLAGS_EXACT is set, you know the IP points to the actual instruction and you can attempt to undo whatever parts of it you need at post processing time. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/