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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFF3AC77B7E for ; Sun, 28 May 2023 20:03:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231447AbjE1UC7 (ORCPT ); Sun, 28 May 2023 16:02:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229523AbjE1UC4 (ORCPT ); Sun, 28 May 2023 16:02:56 -0400 Received: from mail-ej1-x634.google.com (mail-ej1-x634.google.com [IPv6:2a00:1450:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13144A8; Sun, 28 May 2023 13:02:55 -0700 (PDT) Received: by mail-ej1-x634.google.com with SMTP id a640c23a62f3a-970028cfb6cso521288166b.1; Sun, 28 May 2023 13:02:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685304173; x=1687896173; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=Zo6CAhX/gKpTGl7xNzss4y9YGs7PPZhQ0B+6ZO4rHpo=; b=lmyAX8YvijPl9JTnu/+1ez+IEbz4YIX0RKM0OEzi8J793Xt/s9RCgCl7j/nm2Ge50J kKYDFBKL9WNE87XQdkgWWJiFktlw7XZpElXXGp/XQ9XBJ1EFmxgWgCHelRV1wqjbdrV4 AngIoQgk1xxWX/Cdw3tiTOu4g1ZI6pWpjvF8s2ckLO5giUYibQaVO+NC5FdWYE4nenO9 +FHom1aw+edwFW6s0Y+QaUhHtRAifMTuj2HGIyRgmUFrjwIv9iMAjEW6kuEYYnhFO9tY xyLM63K5Zzg92QWMHd2aO4qscr9I2wK/Q8PzFPeH4rybNacWDLqFBFrmnjhi9BxQ4hIr j2VA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685304173; x=1687896173; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Zo6CAhX/gKpTGl7xNzss4y9YGs7PPZhQ0B+6ZO4rHpo=; b=eeb9lHRvkJGIkUGJ2I45xkApmYT5172Sjvr2t1BeAgFI9f4It4XknE2dODpX6HR0Dz YCNTiYEP3xzdcZJ9DiOv9DcI5oYL0/izjBXIKQiRQ7BN+2Bu5rltvYStqkbYCUrV1IlL a74KcRUMLRptfAJjCBEhTLRS2rY01aOQVi3ZTyHXm+GjX/NTw0vuiIy0tPFvEplMhAV7 g3dvbbgrT3JQe7BaSV3/bDCMp/VYdSMz/hivHt3u0+TsjksHz1nYZjNdI+/2nJRe5U8b KBwBCs53G7pF/Cd8SjHOpqrmnDVU1a0vV7lwCGJmOQgZ7hoJWquDf2ag4YiOYl9amZsU gjag== X-Gm-Message-State: AC+VfDzwYF+MojJipuFEr00l78b1t0DEKSZeQ0Ein9suvPh9q92KnR5O iXrctYXVz3QaGgRC0MqKf1Y= X-Google-Smtp-Source: ACHHUZ7amSCeEjsuTpePFIraYwQK5RrXHcbx6rWKwrU9eJeY6Nyzlnvs4W+vU8kdZC3CUytueRKAyw== X-Received: by 2002:a17:907:7251:b0:973:d953:4bf7 with SMTP id ds17-20020a170907725100b00973d9534bf7mr6095191ejc.48.1685304173207; Sun, 28 May 2023 13:02:53 -0700 (PDT) Received: from krava ([83.240.62.205]) by smtp.gmail.com with ESMTPSA id v19-20020a1709060b5300b0096621340285sm5027344ejg.198.2023.05.28.13.02.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 May 2023 13:02:52 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Sun, 28 May 2023 22:02:49 +0200 To: Greg KH Cc: stable@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Masami Hiramatsu , Tsahee Zidenberg , Andrii Nakryiko , Christoph Hellwig , Daniel Borkmann , Thomas Gleixner , =?iso-8859-1?Q?Mah=E9?= Tardy , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH stable 5.4 0/8] bpf: Fix bpf_probe_read/bpf_probe_read_str helpers Message-ID: References: <20230522203352.738576-1-jolsa@kernel.org> <2023052646-magnetize-equate-2b24@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2023052646-magnetize-equate-2b24@gregkh> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 26, 2023 at 07:54:17PM +0100, Greg KH wrote: > On Mon, May 22, 2023 at 10:33:44PM +0200, Jiri Olsa wrote: > > hi, > > we see broken access to user space with bpf_probe_read/bpf_probe_read_str > > helpers on arm64 with 5.4 kernel. The problem is that both helpers try to > > read user memory by calling probe_kernel_read, which seems to work on x86 > > but fails on arm64. > > Has this ever worked on arm64 for the 5.4 kernel tree? If not, it's not > really a regression, and so, why not use a newer kernel that has this > new feature added to it there? > > In other words, what requires you to use the 5.4.y tree and requires > feature parity across architectures? we have a customer running ok on x86 v5.4, but arm64 is broken with the same bpf/user space code upgrade is an option of course, but it's not a big change and we can have 5.4 working on arm64 as well I can send out the change that will be closer to upstream changes, if that's a concern.. with adding the new probe helpers, which I guess is not a problem, because it does not change current API jirka