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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-Disposition: inline In-Reply-To: <2023052646-magnetize-equate-2b24@gregkh> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230528_130255_761096_D3289473 X-CRM114-Status: GOOD ( 21.38 ) 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 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel