From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754277AbdKHC2t (ORCPT ); Tue, 7 Nov 2017 21:28:49 -0500 Received: from www62.your-server.de ([213.133.104.62]:40834 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753674AbdKHC2r (ORCPT ); Tue, 7 Nov 2017 21:28:47 -0500 Message-ID: <5A026BD2.6000007@iogearbox.net> Date: Wed, 08 Nov 2017 03:28:34 +0100 From: Daniel Borkmann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Josef Bacik , rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org, kernel-team@fb.com CC: Josef Bacik Subject: Re: [PATCH 1/2] bpf: add a bpf_override_function helper References: <1510086523-8859-1-git-send-email-josef@toxicpanda.com> <1510086523-8859-2-git-send-email-josef@toxicpanda.com> In-Reply-To: <1510086523-8859-2-git-send-email-josef@toxicpanda.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/07/2017 09:28 PM, Josef Bacik wrote: > From: Josef Bacik > > Error injection is sloppy and very ad-hoc. BPF could fill this niche > perfectly with it's kprobe functionality. We could make sure errors are > only triggered in specific call chains that we care about with very > specific situations. Accomplish this with the bpf_override_funciton > helper. This will modify the probe'd callers return value to the > specified value and set the PC to an override function that simply > returns, bypassing the originally probed function. This gives us a nice > clean way to implement systematic error injection for all of our code > paths. > > Acked-by: Alexei Starovoitov > Signed-off-by: Josef Bacik BPF bits: Acked-by: Daniel Borkmann