From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755184AbbFBHlZ (ORCPT ); Tue, 2 Jun 2015 03:41:25 -0400 Received: from mail-wg0-f48.google.com ([74.125.82.48]:35605 "EHLO mail-wg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbbFBHlR (ORCPT ); Tue, 2 Jun 2015 03:41:17 -0400 Date: Tue, 2 Jun 2015 09:41:12 +0200 From: Ingo Molnar To: Andy Lutomirski Cc: "H.J. Lu" , X86 ML , "linux-kernel@vger.kernel.org" , Markus Trippelsdorf , Binutils , Andy Lutomirski , Linus Torvalds , Greg Kroah-Hartman Subject: Re: [committed, PATCH] Add -mshared option to x86 ELF assembler Message-ID: <20150602074112.GA8005@gmail.com> References: <20150515103414.GA20518@intel.com> <20150601083214.GA381@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andy Lutomirski wrote: > On Mon, Jun 1, 2015 at 4:05 AM, H.J. Lu wrote: > > On Mon, Jun 1, 2015 at 1:32 AM, Markus Trippelsdorf > > wrote: > >> On 2015.05.15 at 03:34 -0700, H.J. Lu wrote: > >>> This patch adds -mshared option to x86 ELF assembler. By default, > >>> assembler will optimize out non-PLT relocations against defined non-weak > >>> global branch targets with default visibility. The -mshared option tells > >>> the assembler to generate code which may go into a shared library > >>> where all non-weak global branch targets with default visibility can > >>> be preempted. The resulting code is slightly bigger. This option > >>> only affects the handling of branch instructions. > >>> > >>> This Linux kernel patch is needed to create a working x86 Linux kernel if > >>> it hasn't been applied: > >>> > >>> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > >>> index ae6588b..b91a00c 100644 > >>> --- a/arch/x86/kernel/head_64.S > >>> +++ b/arch/x86/kernel/head_64.S > >>> @@ -339,8 +339,8 @@ early_idt_handlers: > >>> i = i + 1 > >>> .endr > >>> > >>> -/* This is global to keep gas from relaxing the jumps */ > >>> -ENTRY(early_idt_handler) > >>> +/* This is weak to keep gas from relaxing the jumps */ > >>> +WEAK(early_idt_handler) > >>> cld > >> > >> Have you posted the patch to LKML already? > >> (I hit this issue today and it took me a while to figure out the cause.) > > > > A kernel patch will be checked in soon. > > > > It already is: > > https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=x86/asm&id=cdeb6048940fa4bfb429e2f1cba0d28a11e20cd5 > > It's currently queued for 4.2. > > Ingo, would it make sense to promote this to 4.1? It's definitely a violation > of the "no development after the merge window" rule, but it's sort of a build > fix. [...] Yeah, agreed - the commit was problem-free in testing, so I've cherry-picked it over into tip:x86/urgent and will push it to Linus for v4.1. Thanks, Ingo