From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,T_DKIM_INVALID autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 96D9AC5CFC1 for ; Fri, 15 Jun 2018 07:45:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48D8D20896 for ; Fri, 15 Jun 2018 07:45:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jkNxR2LD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48D8D20896 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755952AbeFOHpO (ORCPT ); Fri, 15 Jun 2018 03:45:14 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:40584 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755925AbeFOHpN (ORCPT ); Fri, 15 Jun 2018 03:45:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=tuQhFlerIgYW+Pyntjohd18YxKK8bU5xgHtRqZmBctE=; b=jkNxR2LDOgiGWMaUjKT0hzmE2 jNDZA+EPXr6E/ALD+huweNPmV+lKPJY1QqcWvx98HuEz1Z1+4X7+u5po5Ok0kcw9IKDOFcq9OttBX 5CWr+KJIhI6XpZFzz6W19GX09dDKzL+g9LzCPUvRtG1oji3jPOCqMTN0YQqE9okbfVJB+WlMKLlSv cV/oVRWNGdGpO9XXWmQhje1H6CAHM1BmaEKHmLPqGVkjJQIXADmHMzuTCtjGTXvhocRq97l77POYS E4LQ06UPiKwlK25u/ZqsY0Mr12gO7GWUaI8dQmOYqjI1yjnjNPrYE5j6WZDKd54ST2j+A9Dqd8lwg seF5wQj5w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fTjPu-0001q6-Gy; Fri, 15 Jun 2018 07:45:06 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1721D2029FA11; Fri, 15 Jun 2018 09:45:04 +0200 (CEST) Date: Fri, 15 Jun 2018 09:45:04 +0200 From: Peter Zijlstra To: Jin Yao Cc: acme@kernel.org, jolsa@kernel.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, me@kylehuey.com, Linux-kernel@vger.kernel.org, vincent.weaver@maine.edu, will.deacon@arm.com, eranian@google.com, namhyung@kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com Subject: Re: [PATCH v1 0/2] perf: Drop leaked kernel samples Message-ID: <20180615074504.GA2458@hirez.programming.kicks-ass.net> References: <1529057003-2212-1-git-send-email-yao.jin@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1529057003-2212-1-git-send-email-yao.jin@linux.intel.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 15, 2018 at 06:03:21PM +0800, Jin Yao wrote: > On workloads that do a lot of kernel entry/exits we see kernel > samples, even though :u is specified. This is due to skid existing. > > This might be a security issue because it can leak kernel addresses even > though kernel sampling support is disabled. > > One patch "perf/core: Drop kernel samples even though :u is specified" > was posted in last year but it was reverted because it introduced a > regression issue that broke the rr-project. > > Now this patch set uses sysctl to control the dropping of leaked > kernel samples. So what happened to the suggestion of keeping the samples but 0-stuffing all the tricky bits?