From patchwork Mon Apr 4 19:38:03 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Borislav Petkov X-Patchwork-Id: 8743801 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 456949F38C for ; Mon, 4 Apr 2016 19:38:35 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6CA3120263 for ; Mon, 4 Apr 2016 19:38:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CA952025A for ; Mon, 4 Apr 2016 19:38:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755840AbcDDTiP (ORCPT ); Mon, 4 Apr 2016 15:38:15 -0400 Received: from mail.skyhub.de ([78.46.96.112]:40255 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754591AbcDDTiN (ORCPT ); Mon, 4 Apr 2016 15:38:13 -0400 X-Virus-Scanned: Nedap ESD1 at mail.skyhub.de Received: from mail.skyhub.de ([127.0.0.1]) by localhost (door.skyhub.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id GPOeQPP5SKb9; Mon, 4 Apr 2016 21:38:11 +0200 (CEST) Received: from pd.tnic (p5DDC51EF.dip0.t-ipconnect.de [93.220.81.239]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 0E6F3245A95; Mon, 4 Apr 2016 21:38:11 +0200 (CEST) Received: by pd.tnic (Postfix, from userid 1000) id 834421617AB; Mon, 4 Apr 2016 21:38:03 +0200 (CEST) Date: Mon, 4 Apr 2016 21:38:03 +0200 From: Borislav Petkov To: Peter Zijlstra , Andy Lutomirski Cc: Jan Kara , Paolo Bonzini , xen-devel , Arjan van de Ven , X86 ML , Andrew Morton , Petr Mladek , KVM list , "linux-kernel@vger.kernel.org" , Linus Torvalds Subject: Re: [PATCH v5 3/9] x86/head: Move early exception panic code into early_fixup_exception Message-ID: <20160404193803.GK351@pd.tnic> References: <4085070316fc3ab29538d3fcfe282648d1d4ee2e.1459605520.git.luto@kernel.org> <20160402183919.GA2538@pd.tnic> <20160402204752.GC2538@pd.tnic> <20160404115206.GG8372@quack.suse.cz> <20160404160042.GB3448@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160404160042.GB3448@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Mon, Apr 04, 2016 at 06:00:42PM +0200, Peter Zijlstra wrote: > On Mon, Apr 04, 2016 at 08:32:21AM -0700, Andy Lutomirski wrote: > > > Adding locking would be easy enough, wouldn't it? > > See patch in this thread.. > > > But do any platforms really boot a second CPU before switching to real > > printk? > > I _only_ use early_printk() as printk() is a quagmire of fail :-) And since I'm the king of minimalistic changes... this below works. However, the problem is that we need to pull up all that early_param parsing in order to enable the early console, i.e. "earlyprintk=ttyS0,115200" cmdline parsing. And we can do all that after having setup the IDT. So I'd need to do some early dancing with cmdline_find_option_bool(boot_command_line, ... in asm or so. Need to think about it more. diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 1f4422d5c8d0..ad534226653b 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -130,6 +130,13 @@ static void __init copy_bootdata(char *real_mode_data) } } +static int _early_printk(const char *fmt, va_list args) +{ + early_printk(fmt, args); + + return 0; +} + asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) { int i; @@ -164,6 +171,10 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) load_idt((const struct desc_ptr *)&idt_descr); copy_bootdata(__va(real_mode_data)); + parse_early_param(); + this_cpu_write(printk_func, _early_printk); + + printk("This is a test!\n"); /* * Load microcode early on BSP. diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 2367ae07eb76..998d6c675549 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -882,6 +882,7 @@ void __init setup_arch(char **cmdline_p) */ __flush_tlb_all(); #else + this_cpu_write(printk_func, vprintk_default); printk(KERN_INFO "Command line: %s\n", boot_command_line); #endif diff --git a/include/linux/printk.h b/include/linux/printk.h index 9ccbdf2c1453..97df81c97b2f 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -169,6 +169,7 @@ void __init setup_log_buf(int early); __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...); void dump_stack_print_info(const char *log_lvl); void show_regs_print_info(const char *log_lvl); +int vprintk_default(const char *fmt, va_list args); #else static inline __printf(1, 0) int vprintk(const char *s, va_list args)