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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 ADB95C4363A for ; Thu, 22 Oct 2020 07:06:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A26F222E9 for ; Thu, 22 Oct 2020 07:06:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603350403; bh=P+1vZ8unu+0ns0wljqnT1FgTdU/YiidiqdFoESKRWCs=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=rInG0jU24RL0eIqYQ2lYo2vSNgybpncJBRyq9oDA8FuIfdSf+F2Zhk+EN6MgxsGsZ FWlhpnbDzCdJIeT4ceFMK+bQP6R0gpeje+0A72jFphsqo2ru7M2MgAv1pzApgT7Dnx 109vhuCTHKYCmCJNaWSyKPAI5nhuxta6OksUiTiU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2505116AbgJVHGk (ORCPT ); Thu, 22 Oct 2020 03:06:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:59444 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2504797AbgJVHGk (ORCPT ); Thu, 22 Oct 2020 03:06:40 -0400 Received: from mail-oi1-f171.google.com (mail-oi1-f171.google.com [209.85.167.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5E0C221534 for ; Thu, 22 Oct 2020 07:06:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603350399; bh=P+1vZ8unu+0ns0wljqnT1FgTdU/YiidiqdFoESKRWCs=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=VVfx0awhyqBJqfMYvDQBfd6ICEVb8eLQ3+JnHI0TlfuegiD0eWrjKAZFPBGB3BGZB kYZPcuKXu8DJeb9X9TAUa0AQQg07i5sXjaCLkLb1VXH4cxtvnIVNHxyh08QxuSZapP BlPCVIFsd49f0q4IJ2SJ7xSWJbcMcjdyP0OFQPY0= Received: by mail-oi1-f171.google.com with SMTP id n3so723531oie.1 for ; Thu, 22 Oct 2020 00:06:39 -0700 (PDT) X-Gm-Message-State: AOAM532saDP0DDjzXoGsfkkySONodwhLHjtSycV/aA2GN+DiFzPCl5VS scU/kq2l3AFkSqTLEORfGWlrujCzKXYZq71aySg= X-Google-Smtp-Source: ABdhPJwCjYtB5nNwE4OfiydcST8z0itvvgSzMtW3Mo/CktytbXqt8eBtjFeuc57QkLfWjunTGtnpO0gB9a6+BFcttj0= X-Received: by 2002:aca:4085:: with SMTP id n127mr639122oia.33.1603350398525; Thu, 22 Oct 2020 00:06:38 -0700 (PDT) MIME-Version: 1.0 References: <20201021225737.739-1-digetx@gmail.com> <202010211637.7CFD8435@keescook> <773fbdb0-5fc4-ab39-e72d-89845faa4c6d@gmail.com> <202010212028.32E8A5EF9B@keescook> In-Reply-To: <202010212028.32E8A5EF9B@keescook> From: Ard Biesheuvel Date: Thu, 22 Oct 2020 09:06:27 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v1] ARM: vfp: Use long jump to fix THUMB2 kernel compilation error To: Kees Cook Cc: Dmitry Osipenko , Nick Desaulniers , Linux Kernel Mailing List , Russell King , clang-built-linux , Ingo Molnar , Linux ARM Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 22 Oct 2020 at 05:30, Kees Cook wrote: > > On Thu, Oct 22, 2020 at 03:00:06AM +0300, Dmitry Osipenko wrote: > > 22.10.2020 02:40, Kees Cook =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > > > On Thu, Oct 22, 2020 at 01:57:37AM +0300, Dmitry Osipenko wrote: > > >> The vfp_kmode_exception() function now is unreachable using relative > > >> branching in THUMB2 kernel configuration, resulting in a "relocation > > >> truncated to fit: R_ARM_THM_JUMP19 against symbol `vfp_kmode_excepti= on'" > > >> linker error. Let's use long jump in order to fix the issue. > > > > > > Eek. Is this with gcc or clang? > > > > GCC 9.3.0 > > > > >> Fixes: eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input secti= ons") > > > > > > Are you sure it wasn't 512dd2eebe55 ("arm/build: Add missing sections= ") ? > > > That commit may have implicitly moved the location of .vfp11_veneer, > > > though I thought I had chosen the correct position. > > > > I re-checked that the fixes tag is correct. > > > > >> Signed-off-by: Dmitry Osipenko > > >> --- > > >> arch/arm/vfp/vfphw.S | 3 ++- > > >> 1 file changed, 2 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S > > >> index 4fcff9f59947..6e2b29f0c48d 100644 > > >> --- a/arch/arm/vfp/vfphw.S > > >> +++ b/arch/arm/vfp/vfphw.S > > >> @@ -82,7 +82,8 @@ ENTRY(vfp_support_entry) > > >> ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exc= eptions > > >> and r3, r3, #MODE_MASK @ are supported in kernel mode > > >> teq r3, #USR_MODE > > >> - bne vfp_kmode_exception @ Returns through lr > > >> + ldr r1, =3Dvfp_kmode_exception > > >> + bxne r1 @ Returns through lr > > >> > > >> VFPFMRX r1, FPEXC @ Is the VFP enabled? > > >> DBGSTR1 "fpexc %08x", r1 > > > > > > This seems like a workaround though? I suspect the vfp11_veneer needs > > > moving? > > > > > > > I don't know where it needs to be moved. Please feel free to make a > > patch if you have a better idea, I'll be glad to test it. > > I might have just been distracted by the common "vfp" prefix. It's > possible that the text section shuffling just ended up being very large, > so probably this patch is right then! > I already sent a fix for this issue: https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=3D9018/1