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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4FE16C433F5 for ; Tue, 18 Jan 2022 14:15:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=VGPhbMxNaQjXCGTq6CGbnFJNlgoXdYkXwMSrgAol+0k=; b=bCLVFvrtB/S+S/4pXqJTPs3JMS KF0M9rVLH9FoKgcaTj4mJRd6DOQX3o/4uaqK+o365i6AOI/DWe+jNdckZj3dQwJeAnAtzjWnXcDFC yFzG9QE+NAcIdhwtgD1WOIiszzE4yrAusAfrSO8wAZH8rweouDKGNn4yirfgASqxEredX9EzE7K1n uZcEBRGLDOA9ap94CHYYxfGFu0EU/pg2itzGWY+4c92Smu90w867w1LrnM3KIJpJjrmQJbK8PfIPm t8cVK2rbjrmJLWbdG71nvl8+sFouDWviTzUoaD8dpElFDJ8PZJhDT7Td5czUvBp65Bv3dLmZLsoH4 hnGr0icg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n9pFM-001oE9-2w; Tue, 18 Jan 2022 14:14:04 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n9pFI-001oDA-IO for linux-arm-kernel@lists.infradead.org; Tue, 18 Jan 2022 14:14:01 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 502B81FB; Tue, 18 Jan 2022 06:13:59 -0800 (PST) Received: from [10.57.35.29] (unknown [10.57.35.29]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 681EC3F766; Tue, 18 Jan 2022 06:13:58 -0800 (PST) Subject: Re: [RFC PATCH 2/2] perf: arm_spe: Enable CONTEXT packets in SPE traces if the profiler runs in CPU mode. To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, james.clark@arm.com, leo.yan@linaro.org References: <20220117124432.3119132-1-german.gomez@arm.com> <20220117124432.3119132-3-german.gomez@arm.com> <20220118095258.GA16547@willie-the-truck> From: German Gomez Message-ID: Date: Tue, 18 Jan 2022 14:13:42 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20220118095258.GA16547@willie-the-truck> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220118_061400_690965_2F546FDD X-CRM114-Status: GOOD ( 15.99 ) 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 On 18/01/2022 09:52, Will Deacon wrote: > On Mon, Jan 17, 2022 at 12:44:32PM +0000, German Gomez wrote: >> Enable CONTEXT packets in SPE traces if the profiler runs in CPU mode. >> This is no less permissive than the existing behavior for the following >> reason: >> >> If perf_event_paranoid <= 0, then non perfmon_capable() users can open >> a per-CPU event. With a per-CPU event, unpriviledged users are allowed >> to profile _all_ processes, even ones owned by root. >> >> Without this change, users could see kernel addresses, root processes, >> etc, but not gather the PIDs of those processes. The PID is probably the >> least sensitive of all the information. >> >> It would be more idiomatic to check the perf_event_paranoid level with >> perf_allow_cpu(), but this function is not exported so cannot be used >> from a module. Looking for cpu != -1 is the indirect way of checking >> the same thing as it could never get to arm_spe_pmu_event_init() without >> perf_event_paranoid <= 0. > perf_allow_cpu() is a static inline so there's no need to export it. What's > missing? We were still running into build errors: ERROR: modpost: "security_perf_event_open" [drivers/perf/arm_spe_pmu.ko] undefined! ERROR: modpost: "sysctl_perf_event_paranoid" [drivers/perf/arm_spe_pmu.ko] undefined > > Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel