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=-7.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 55914C433E0 for ; Wed, 27 Jan 2021 07:40:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F7542073C for ; Wed, 27 Jan 2021 07:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S317310AbhAZXw4 (ORCPT ); Tue, 26 Jan 2021 18:52:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:58772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726275AbhAZQ74 (ORCPT ); Tue, 26 Jan 2021 11:59:56 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id CB71B229C9; Tue, 26 Jan 2021 16:59:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611680356; bh=gRAls07DrECuk0X0leeEk0d93d6mXj1Kwan1fuByVy4=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=KnsAUeIzrJGXRzJY+SVSVSHHly5KZhwzKAKGXMOQbNrc25Rf4hcm8Y3aKAWQePl/Q wK7AoNr5g1J9hj6sXlI1UbimdA3jPsBFvAvpcpBlfg3VoTBBGLZkXyNIvfhtYuKJUi B+ZaiJzg2TcYC78+tx2kQHFsLWgvSz3QNUILUKK6278zNms2bXei6lBLzylxT4rCL5 0vUK9RCVSvwL0bNBU/cKIjGn88iKuzL+TMPC3uq2uzqWkAPt5F0bUCFnKURybuvoCP Ow47Xqgnoib42p33vuyp2KIPpIQ2EuFzYXuT5Fv/Shu5T+rCCgRZs6420ck63l/iTm hqqZ9ftMU7Yeg== Subject: Re: [PATCH 0/2] introduce DUMP_PREFIX_UNHASHED for hex dumps To: Vlastimil Babka , Sergey Senozhatsky , Matthew Wilcox Cc: Andrew Morton , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, Petr Mladek , roman.fietze@magna.com, keescook@chromium.org, Steven Rostedt , John Ogness , linux-mm@kvack.org, Akinobu Mita References: <20210116220950.47078-1-timur@kernel.org> <20210118182635.GD2260413@casper.infradead.org> <20210119014725.GH2260413@casper.infradead.org> <09c70d6b-c989-ca23-7ee8-b404bb0490f0@suse.cz> From: Timur Tabi Message-ID: Date: Tue, 26 Jan 2021 10:59:12 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <09c70d6b-c989-ca23-7ee8-b404bb0490f0@suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/26/21 10:47 AM, Vlastimil Babka wrote: > Given Linus' current stance later in this thread, could we revive the idea of a > boot time option, or at least a CONFIG (I assume a runtime toggle would be too > much, even if limited to !kernel_lockdown:) , that would disable all hashing? > It would be really useful for a development/active debugging, as evidenced > below. Thanks. So you're saying: if CONFIG_PRINTK_NEVER_HASH is disabled, then %p prints hashed addresses and %px prints unhashed. If CONFIG_PRINTK_NEVER_HASH is enabled, then %p and %px both print unhashed addresses. I like this idea, and I would accept it as a solution if I had to, but I still would also like for an option for print_hex_dump() to print unhashed addresses even when CONFIG_PRINTK_NEVER_HASH is disabled. I can't always recompile the entire kernel for my testing purposes. The only drawback to this idea is: what happens if distros start enabling CONFIG_PRINTK_NEVER_HASH by default, just because it makes debugging easier?