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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=ham 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 C0F58C2D0B1 for ; Tue, 4 Feb 2020 12:29:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F1E12084E for ; Tue, 4 Feb 2020 12:29:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727181AbgBDM3E (ORCPT ); Tue, 4 Feb 2020 07:29:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:48720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727127AbgBDM3D (ORCPT ); Tue, 4 Feb 2020 07:29:03 -0500 Received: from oasis.local.home (unknown [212.187.182.162]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 22E342084E; Tue, 4 Feb 2020 12:29:00 +0000 (UTC) Date: Tue, 4 Feb 2020 07:28:56 -0500 From: Steven Rostedt To: Linus Torvalds Cc: LKML , Ingo Molnar , Andrew Morton , Masami Hiramatsu , Tom Zanussi , Peter Zijlstra Subject: Re: [GIT PULL] tracing: Changes for 5.6 Message-ID: <20200204072856.0da60613@oasis.local.home> In-Reply-To: References: <20200204053155.127c3f1e@oasis.local.home> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Feb 2020 11:54:09 +0000 Linus Torvalds wrote: > On Tue, Feb 4, 2020 at 10:32 AM Steven Rostedt wrote: > > > > - Added new "bootconfig". > > Looks for a file appended to initrd to add boot config options. > > This has been discussed thoroughly at Linux Plumbers. > > Very useful for adding kprobes at bootup. > > Is there a way to disable this from the "real" kernel command line? Currently no. > > If I have problems, I want to boot with a known kernel command line > (forcing text mode etc). If the bootconfig file always gets parsed, > there's no way to do that from the bootloader (grub2, whatever).. > I totally agree as I had that exact same issue while testing this. I wanted to not have it and found it a bit annoying I needed to modify the initrd to remove it for just a single boot up. Would this work? -- Steve diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ade4e6ec23e0..c4f1417f1934 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -857,6 +857,10 @@ on Perform hardened usercopy checks (default). off Disable hardened usercopy checks. + disable_bootconfig + Disable reading the bootconfig that may be attached + to the initrd. + disable_radix [PPC] Disable RADIX MMU mode on POWER9 diff --git a/init/main.c b/init/main.c index dd7da62d99a5..b52636cd9c1d 100644 --- a/init/main.c +++ b/init/main.c @@ -336,15 +336,23 @@ u32 boot_config_checksum(unsigned char *p, u32 size) return ret; } -static void __init setup_boot_config(void) +static void __init setup_boot_config(const char *cmdline) { u32 size, csum; char *data, *copy; + const char *p; u32 *hdr; if (!initrd_end) return; + p = strstr(cmdline, "disable_bootconfig"); + if (p && (p == cmdline || isspace(*(p-1))) && + (!p[18] || isspace(p[18]))) { + pr_info("Disabling bootconfig because 'disable_bootconfig' found on the command line\n"); + return; + } + hdr = (u32 *)(initrd_end - 8); size = hdr[0]; csum = hdr[1]; @@ -379,7 +387,7 @@ static void __init setup_boot_config(void) } } #else -#define setup_boot_config() do { } while (0) +#define setup_boot_config(cmdline) do { } while (0) #endif /* Change NUL term back to "=", to make "param" the whole string. */ @@ -760,7 +768,7 @@ asmlinkage __visible void __init start_kernel(void) pr_notice("%s", linux_banner); early_security_init(); setup_arch(&command_line); - setup_boot_config(); + setup_boot_config(command_line); setup_command_line(command_line); setup_nr_cpu_ids(); setup_per_cpu_areas();