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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CC3FC433DB for ; Tue, 9 Mar 2021 14:46:17 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C791B64F62 for ; Tue, 9 Mar 2021 14:46:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C791B64F62 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=sz91KDuJMslsxHd+9nLl2d8glEdeCejwAb5T1YA+QQ4=; b=g7M09VbBGoiE2yEAEOf/92wxP csJecVt9txVaywzEWsKV7Zxw+lrZAbD3tiGTsEHznT4q4guS3SvPJcmpIH3Et+6GKP29yz4yIR5xp mGh/znup4oLfEcH4tGaJ6iHZ6Tx61rm3MON3F11EZ9zNgyOB9Imtirty8NBdl0riwhLaIYEIcj6mM 0cNNkJO3nFV5VLMKj+RWKshVPHf5WQOLbr9DmPQ7YpgZk1n4ANnt4+UJCVDje+Aoey1bl1VTvNN1s rYBFK4320BWVSWsNMfHq/Tzw3OCdpg+q+1DtciceDD79otPm82zNzrJbRIkMHPlDtBBxkKCaALBIA Og+ui3rLw==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lJdbD-004s0y-6C; Tue, 09 Mar 2021 14:44:40 +0000 Received: from mga04.intel.com ([192.55.52.120]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lJdb5-004ryQ-33 for linux-arm-kernel@lists.infradead.org; Tue, 09 Mar 2021 14:44:36 +0000 IronPort-SDR: GS0JP2VMyN+Uf+DjszgvekpVINEaIDdsLwi54LKJVcuYfspw9FcnTp0j7KEur6NlWb7c+eSUwz vIaWjEby2wRg== X-IronPort-AV: E=McAfee;i="6000,8403,9918"; a="185866159" X-IronPort-AV: E=Sophos;i="5.81,234,1610438400"; d="scan'208";a="185866159" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Mar 2021 06:44:25 -0800 IronPort-SDR: N00FXBDQ9afDM/JN8pm9XqrqOtHE5msPirwbQdR4+r16djEwDNZRd9UycDpjKTYd7W8DFp7uFz 49Hw5FFfY0tw== X-IronPort-AV: E=Sophos;i="5.81,234,1610438400"; d="scan'208";a="447519100" Received: from tassilo.jf.intel.com ([10.54.74.11]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Mar 2021 06:44:24 -0800 Date: Tue, 9 Mar 2021 06:44:23 -0800 From: Andi Kleen To: Sai Prakash Ranjan Cc: acme@kernel.org, al.grant@arm.com, alexander.shishkin@linux.intel.com, coresight@lists.linaro.org, denik@chromium.org, dianders@chromium.org, jolsa@redhat.com, leo.yan@linaro.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, mathieu.poirier@linaro.org, mike.leach@linaro.org, mingo@redhat.com, mnissler@chromium.org, namhyung@kernel.org, peterz@infradead.org, suzuki.poulose@arm.com, swboyd@chromium.org Subject: Re: [PATCHv2 0/4] perf/core: Add support to exclude kernel mode PMU tracing Message-ID: <20210309144423.GD203350@tassilo.jf.intel.com> References: <87tupqu10c.fsf@linux.intel.com> <20210309063828.26392-1-saiprakash.ranjan@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210309063828.26392-1-saiprakash.ranjan@codeaurora.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210309_144431_489838_F520AEFE X-CRM114-Status: GOOD ( 17.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > The disk encryption is just one example and there might be others which > we might not be aware of yet and we are not suspecting there is something > wrong with the crypto code that needs to be fixed. Then you don't have any leaks relating to branch tracing. > restrict an external(in the sense that its not related to crypto or any > other security related component) entity such as hardware assisted tracing > like ARM coresight and so on. I don't see why or how the crypto code needs > to be fixed for something that is not related to it although it is affected. It's just a general property that if some code that is handling secrets is data dependent it already leaks. > The analogy would be like of the victims and a perpetrator. Lets take coresight > as an example for perpetrator and crypto as the victim here. Now we can try There's no victim with branch tracing, unless it is already leaky. > If we just know one victim (lets say crypto code here), what happens to the > others which we haven't identified yet? Do we just wait for someone to write > an exploit based on this and then scramble to fix it? For a useful security mitigation you need a threat model first I would say. So you need to have at least some idea how an attack with branch tracing would work. > Initial change was to restrict this only to HW assisted instruction tracing [1] I don't think it's needed for instruction tracing. -Andi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel