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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 6624BC433DB for ; Wed, 17 Mar 2021 16:19:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 174C564F17 for ; Wed, 17 Mar 2021 16:19:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232167AbhCQQSz (ORCPT ); Wed, 17 Mar 2021 12:18:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:44932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232268AbhCQQSq (ORCPT ); Wed, 17 Mar 2021 12:18:46 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8DB3A60C41; Wed, 17 Mar 2021 16:18:42 +0000 (UTC) Date: Wed, 17 Mar 2021 16:18:39 +0000 From: Catalin Marinas To: Arnd Bergmann Cc: Will Deacon , Nathan Chancellor , Nick Desaulniers , Arnd Bergmann , Kees Cook , Mark Brown , Vincenzo Frascino , Geert Uytterhoeven , Kristina Martsenko , Ionela Voinescu , Mark Rutland , Andrew Scull , David Brazdil , Marc Zyngier , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] [RFC] arm64: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION Message-ID: <20210317161838.GF12269@arm.com> References: <20210225112122.2198845-1-arnd@kernel.org> <20210317143757.GD12269@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210317143757.GD12269@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 17, 2021 at 02:37:57PM +0000, Catalin Marinas wrote: > On Thu, Feb 25, 2021 at 12:20:56PM +0100, Arnd Bergmann wrote: > > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > > index bad2b9eaab22..926cdb597a45 100644 > > --- a/arch/arm64/kernel/vmlinux.lds.S > > +++ b/arch/arm64/kernel/vmlinux.lds.S > > @@ -217,7 +217,7 @@ SECTIONS > > INIT_CALLS > > CON_INITCALL > > INIT_RAM_FS > > - *(.init.altinstructions .init.bss .init.bss.*) /* from the EFI stub */ > > + *(.init.altinstructions .init.data.* .init.bss .init.bss.*) /* from the EFI stub */ > > INIT_DATA already covers .init.data and .init.data.*, so I don't think > we need this change. Ah, INIT_DATA only covers init.data.* (so no dot in front). The above is needed for the EFI stub. However, I gave this a quick try and under Qemu with -cpu max and -smp 2 (or more) it fails as below. I haven't debugged but the lr points to just after the switch_to() call. Maybe some section got discarded and we patched in the wrong instructions. It is fine with -cpu host or -smp 1. -------------------8<------------------------ smp: Bringing up secondary CPUs ... Detected PIPT I-cache on CPU1 CPU1: Booted secondary processor 0x0000000001 [0x000f0510] Unable to handle kernel paging request at virtual address eb91d81ad2971160 Mem abort info: ESR = 0x86000004 EC = 0x21: IABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 [eb91d81ad2971160] address between user and kernel address ranges Internal error: Oops: 86000004 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 16 Comm: migration/1 Not tainted 5.12.0-rc3-00002-g128e977c1322 #1 Stopper: 0x0 <- 0x0 pstate: 60000085 (nZCv daIf -PAN -UAO -TCO BTYPE=--) pc : 0xeb91d81ad2971160 lr : __schedule+0x230/0x6b8 sp : ffff80001009bd60 x29: ffff80001009bd60 x28: 0000000000000000 x27: ffff0000000a6760 x26: ffff0000000b7540 x25: 0080000000000000 x24: ffffd81ad3969000 x23: ffff0000000a6200 x22: 6ee0d81ad2971658 x21: ffff0000000a6200 x20: ffff000000080000 x19: ffff00007fbc6bc0 x18: 0000000000000030 x17: 0000000000000000 x16: 0000000000000000 x15: 00008952b30a9a9e x14: 0000000000000366 x13: 0000000000000192 x12: 0000000000000000 x11: 0000000000000003 x10: 00000000000009b0 x9 : ffff80001009bd30 x8 : ffff0000000a6c10 x7 : ffff00007fbc6cc0 x6 : 00000000fffedb30 x5 : 00000000ffffffff x4 : 0000000000000000 x3 : 0000000000000008 x2 : 0000000000000000 x1 : ffff0000000a6200 x0 : ffff0000000a3800 Call trace: 0xeb91d81ad2971160 schedule+0x70/0x108 schedule_preempt_disabled+0x24/0x40 __kthread_parkme+0x68/0xd0 kthread+0x138/0x170 ret_from_fork+0x10/0x30 Code: bad PC value ---[ end trace af3481062ecef3e7 ]--- -- Catalin