From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2AF780034; Thu, 13 Feb 2025 01:44:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739411069; cv=none; b=MsZQAGip0xJAQYxcTrv5/JyPcZkTf/1v7juT92mBVkH/y6Lefg7ijQkqw5qo1Z/EG9LiBq4ocmIqwbsNKGq5mGEKnGDzpnzOpTBt1NsyGiZKW0/aY2ciesUiYjfV6NNhhMGm1tEhNCtC74bLQhhb+cqXO7E80x8esTJULCo4FmY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739411069; c=relaxed/simple; bh=wzUJkID6PgklgGpm0weU8DjYBBZpfzyA5yAhlyuAsG4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EpjeOTlD4X2SiWlZ/SiF69l1ehC4Kbpdsh4TuJKwhLPYRkMbg3XvuRPbhK5VosVK7Rur0VaAMHn1B2ChUjtlNcAOh7rhijhSFF/HPkuFHOIM+cDHp4mDVWB2q/fGu3yI2+Josthrq09NZYagKAe1YC3/txBIWiBcn2CE0+1ymW4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MxmfcJ0c; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MxmfcJ0c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9A51C4CEDF; Thu, 13 Feb 2025 01:44:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739411068; bh=wzUJkID6PgklgGpm0weU8DjYBBZpfzyA5yAhlyuAsG4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MxmfcJ0cVtyMjA9UmTwDiDTwP6zb603GgyKEXaWMW5F1ZA1fNvbyHCxhlnX7EU3iG gz3nt7ngw2IjzHpSdpEVq9GaKj7tJm2LHcPweuWQ6xNjOKTr8fVEdMpsYY+pSO8K6b WXvZbxZriCGIn8ZFgsTfHExcNYkoeRkc/j63P95SFhhMjh5GW56dQr1H8R6/oK51qn IXRGwxopzg2C9odZ0O8ikyZUQtawVACT3uQMjmvMSJmtcEotydwTzsOLDWxxjAVDmw kpDfo7FGjJJ0OVIhzA89bJXD8waO1TOs4nt3wWCQsP8K5rmBKOfFeYqdL9udp0iNUx 2gJ36ih0JT2qg== Date: Wed, 12 Feb 2025 17:44:24 -0800 From: Namhyung Kim To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , Hao Ge , James Clark , Howard Chu , Dominique Martinet , Levi Yun , Xu Yang , Tengda Wu , Yang Jihong , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 00/10] Move uid filtering to BPF filters Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Feb 12, 2025 at 03:17:35PM -0800, Ian Rogers wrote: > On Wed, Feb 12, 2025 at 2:56 PM Namhyung Kim wrote: > > > > On Wed, Feb 12, 2025 at 12:00:42PM -0800, Ian Rogers wrote: > > > On Wed, Feb 12, 2025 at 10:46 AM Namhyung Kim wrote: > > > > It's not completely broken and works sometimes. > > > > > > No this is the definition of completely broken. If it only works > > > sometimes then you can't use it, we can't put a test on it, there is > > > no point in it. Even when it doesn't fail on perf_event_open, does it > > > work for processes that start after /proc is scanned? No, it is > > > completely broken. > > > > Ok, we have a different definition for it. Let's ignore the imaginary > > users of the broken features. Have you added a test for this change? > > > > Anyway I've tested your change and found some issues: > > > > 1. It silently exited when BPF-skel is not built. Better to put some > > messages at least. > > > > $ sudo ./perf record -u $(id -u) -- sleep 1 > > > > 2. Even with BPF-skel, perf record doesn't work well. It did something > > but failed to get sample data for some reason. > > > > $ sudo ./perf record -u $(id -u) -- sleep 1 > > [ perf record: Woken up 1 times to write data ] > > [ perf record: Captured and wrote 0.045 MB perf.data ] > > > > Oh, I think you now need to pass -a because it now works in > > system-wide mode and drops samples for other users. > > This is a pre-existing problem, no? No, it worked without -a in the past. Please see my previous reply. I think -u/--uid is one of the supported target in the perf tool (not for the system call) and it used to disable system-wide mode if -u is used at the same time. Thanks, Namhyung > > > 3. With BPF-skel, non-root users will see this. > > > > $ ./perf record -u $(id -u) -- sleep 1 > > cannot get fd for 'filters' map > > failed to set filter "BPF" on event cycles:P with 13 (Permission denied) > > > > I think it's confusing and better to tell user that you need to run > > 'perf record --setup-filter pin' as root first. But maybe due to the > > issue #2, you still need to run it as root. > > > > Thanks, > > Namhyung > >