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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable 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 7EE65C4361B for ; Thu, 17 Dec 2020 08:34:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39AE7236F9 for ; Thu, 17 Dec 2020 08:34:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727354AbgLQIeU (ORCPT ); Thu, 17 Dec 2020 03:34:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726569AbgLQIeU (ORCPT ); Thu, 17 Dec 2020 03:34:20 -0500 Received: from mail-il1-x129.google.com (mail-il1-x129.google.com [IPv6:2607:f8b0:4864:20::129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B294EC0617A7 for ; Thu, 17 Dec 2020 00:33:39 -0800 (PST) Received: by mail-il1-x129.google.com with SMTP id x15so25154019ilq.1 for ; Thu, 17 Dec 2020 00:33:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=atishpatra.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=DUte5MZb3VgmcVGjhmZGHO+sbeoQVX9ioF310lk1DlM=; b=sTA4NLIAZ6ZSRkLiJJDaYIwt+a0K9pKODxKCrc3xUiXv6exsXJ2CGMHUEK3+vLuL/O i7nD0VF5A/5MTADxkf/ZykzVwz+y/twHQKWqudTU662Y2lQ3xI0H5WBCjx8V/EDPeIGR XQIFrh0jLpMUVPpMFXVc4mxTS4DlAk00uM/og= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=DUte5MZb3VgmcVGjhmZGHO+sbeoQVX9ioF310lk1DlM=; b=V0ULYF7WKy1FjuUT/Tbrigy6RHdQ51ajcerKKtGt0ls6yCZjtsHFZxY8SCltJzW/QB t6cYxYskVsBKPOa1fhAcQqHD+Y4VORz1wpdlyHEXh6V4AQZu4ld8nZmgH6H2qU/0G2h0 v7Gv4XkSsJU9JRue8H46DRMs5N/w/rvnHXuP3q66IdcWDvtG0KZqBc5haAsRPt4h0D/W d88Z7HpMfMsSOF5FVm2zV4YkzEeTJ5A7jkySX1MsNN24eqgqLTSE9kpvMHErDe7QUmid 9MfjO8fzigCHFJY0rh+pDFplLFs2I0hHL27DSR14q73bIbZfHqMlAEwgo7fn383Ost0p iQ/A== X-Gm-Message-State: AOAM530DNUQyHJ44o/dPd9dzlyZ2PYJPQmlanLjjJ89MxmdUeRGHFkoc i4Y060khYZHoY3Xtywpcb2sZhqpSs3UYwlpWJWqX X-Google-Smtp-Source: ABdhPJzt31wK+zmuokHE1Cu7YvCT4RhK78rmt7+i93T60Wfs0RAnKDae02C8YXuPWWHsEVCYpQG1FXdYnnpxHiaqYC8= X-Received: by 2002:a92:d84a:: with SMTP id h10mr47844317ilq.77.1608194018942; Thu, 17 Dec 2020 00:33:38 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Atish Patra Date: Thu, 17 Dec 2020 00:33:28 -0800 Message-ID: Subject: Re: [PATCH v3 3/5] RISC-V: Align the .init.text section To: Palmer Dabbelt Cc: Alistair Francis , Albert Ou , Zong Li , Anup Patel , "linux-kernel@vger.kernel.org List" , linux-riscv , Atish Patra , ren_guo@c-sky.com, Paul Walmsley , ojeda@kernel.org, Greentime Hu , Andrew Morton , Michel Lespinasse , Ard Biesheuvel , Mike Rapoport , Jim Wilson Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 16, 2020 at 10:51 PM Palmer Dabbelt wrote: > > On Tue, 15 Dec 2020 22:02:54 PST (-0800), Palmer Dabbelt wrote: > > On Wed, 04 Nov 2020 16:04:37 PST (-0800), Atish Patra wrote: > >> In order to improve kernel text protection, we need separate .init.text/ > >> .init.data/.text in separate sections. However, RISC-V linker relaxation > >> code is not aware of any alignment between sections. As a result, it may > >> relax any RISCV_CALL relocations between sections to JAL without realizing > >> that an inter section alignment may move the address farther. That may > >> lead to a relocation truncated fit error. However, linker relaxation code > >> is aware of the individual section alignments. > >> > >> The detailed discussion on this issue can be found here. > >> https://github.com/riscv/riscv-gnu-toolchain/issues/738 > >> > >> Keep the .init.text section aligned so that linker relaxation will take > >> that as a hint while relaxing inter section calls. > >> Here are the code size changes for each section because of this change. > >> > >> section change in size (in bytes) > >> .head.text +4 > >> .text +40 > >> .init.text +6530 > >> .exit.text +84 > >> > >> The only significant increase in size happened for .init.text because > >> all intra relocations also use 2MB alignment. > >> > >> Suggested-by: Jim Wilson > >> Signed-off-by: Atish Patra > >> --- > >> arch/riscv/kernel/vmlinux.lds.S | 8 +++++++- > >> 1 file changed, 7 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S > >> index 3ffbd6cbdb86..cacd7898ba7f 100644 > >> --- a/arch/riscv/kernel/vmlinux.lds.S > >> +++ b/arch/riscv/kernel/vmlinux.lds.S > >> @@ -30,7 +30,13 @@ SECTIONS > >> . = ALIGN(PAGE_SIZE); > >> > >> __init_begin = .; > >> - INIT_TEXT_SECTION(PAGE_SIZE) > >> + __init_text_begin = .; > >> + .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) ALIGN(SECTION_ALIGN) { \ > >> + _sinittext = .; \ > >> + INIT_TEXT \ > >> + _einittext = .; \ > >> + } > >> + > >> . = ALIGN(8); > >> __soc_early_init_table : { > >> __soc_early_init_table_start = .; > > > > Not sure what's going on here (or why I wasn't catching it earlier), but this > > is breaking boot on one of my test configs. I'm not getting any Linux boot > > spew, so it's something fairly early. I'm running defconfig with > > > > CONFIG_PREEMPT=y > > CONFIG_DEBUG_PREEMPT=y > > CONFIG_PROVE_LOCKING=y > > > > It looks like that's been throwing a bunch of warnings for a while, but it did > > at least used to boot. No idea what PREEMPT would have to do with this, and > > the other two don't generally trigger issues that early in boot (or at least, > > trigger halts that early in boot). > > > > There's a bunch of other stuff that depends on this that's on for-next so I > > don't want to just drop it, but I also don't want to break something. I'm just > > running QEMU's virt board. > > I just verified for-next on QEMU 5.2.0 for virt (RV32,64, nommu) and sifive_u as well. I will give it a try on unleashed tomorrow as well with the above configs enabled. > > I'll take a look again tomorrow night, but if anyone has some time to look > > that'd be great! > > Looks like this breaks on QEMU 5.0.0 but works on 5.2.0. I will take a look tomorrow to check the root cause. I guess technically > that means could be considered a regression, but as we don't really have any > scheme for which old versions of QEMU we support it's not absolute. I'd > usually err on the side of keeping support for older platforms, but in this > case it's probably just not worth the time so I'm going to just ignore it. > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv -- Regards, Atish