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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F856C2B9F8 for ; Tue, 25 May 2021 07:33:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D4A861421 for ; Tue, 25 May 2021 07:33:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231698AbhEYHfR (ORCPT ); Tue, 25 May 2021 03:35:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230005AbhEYHfK (ORCPT ); Tue, 25 May 2021 03:35:10 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6948C061574 for ; Tue, 25 May 2021 00:33:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Subject:Cc:To:From:Date:Message-ID: Sender:Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To:References; bh=4zoxU5b1QV6QiUvFvnDKve3Vz+8+npvl/t6DvzE8QCs=; b=WshCUQJztw84n+ha/CGhoWt8hT 6zs3f9EFu2enwzRMsPNPQNqxatXjROMLLxhN1YcXqlkQd63gPDtN6aby77/amstjza6qEVoIWo8db EoUuPwHo30xy2LP1Lh2nD/XouwZ7Mn3/dfyM2dfjLOOkD6ypqvXITMXoav3miwAb0cQtTorEe88+y Ze/9IfrMqxFWHnbJe6MnuqivvwVGSxicPfsxYj1SPzX17OYfvBaMNSFOuhjPlS9j56pMi1BuT+alA 6hsSsdC0D1QX84tt2j5BfLxhF1oVtr8tf3rgaXGMD0q2RHQq3Kq+Lwv+ARv7iaeIo4oYXkJiSoHQK AS85E/9A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1llRYg-003Eis-Hz; Tue, 25 May 2021 07:33:03 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 2E6F93001E4; Tue, 25 May 2021 09:32:57 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id D15AB30A65B78; Tue, 25 May 2021 09:32:57 +0200 (CEST) Message-ID: <20210525072518.791889911@infradead.org> User-Agent: quilt/0.66 Date: Tue, 25 May 2021 09:25:18 +0200 From: Peter Zijlstra To: mhiramat@kernel.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@kernel.org, rostedt@goodmis.org, naveen.n.rao@linux.vnet.ibm.com, ananth@linux.ibm.com, x86@kernel.org Subject: [PATCH 0/2] kprobes: Remove kprobe::fault_handler Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The reason for kprobe::fault_handler(), as given by their comment: * We come here because instructions in the pre/post * handler caused the page_fault, this could happen * if handler tries to access user space by * copy_from_user(), get_user() etc. Let the * user-specified handler try to fix it first. Is just plain bad. Those other handlers are ran from non-preemptible context and had better use _nofault() functions. Also, there is no upstream usage of this. The corollary of this change is that no tracing/probing/whatever can consume faults.