From patchwork Tue Dec 1 21:36:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11943947 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=-26.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 02155C8302B for ; Tue, 1 Dec 2020 21:39:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95C532085B for ; Tue, 1 Dec 2020 21:39:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZHmcfGNp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390159AbgLAVjg (ORCPT ); Tue, 1 Dec 2020 16:39:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390015AbgLAVjb (ORCPT ); Tue, 1 Dec 2020 16:39:31 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C90A9C094242 for ; Tue, 1 Dec 2020 13:37:30 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id v13so3969352ybe.18 for ; Tue, 01 Dec 2020 13:37:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=9TLfWaf58UYL7wICLMCVVnhaOCpYf+H5DpQSRdiy6Cc=; b=ZHmcfGNpa7ZNviH3Lhbi7/0SDEQ3Jls1Fd4loR1GsDVBD7tyPoyw8FMMexSiO0w9DW 9RjrozMTcLSgrBxEv1Vz8SoUuZs1OCJb++caQa3OdSsaiYW67cFBU7PQ9LNeGNpQOT/K 9NZ2TIpPQb7/71Uv+3b78ioZtiLnITOk2KjhIvpWKQSdMkCVpud7TsnvOO4ORqlpu2u5 nOj1pZxLhS/1QmdqjetYddIidvonWTCSBDRIzR5umGDHjrntwGXK/yd6oSDTP2uLIXdB crW36MjeZXAzVs/1lqNDI0q9ni6fGs696oymio04cAycbm2CdWTbsus3NowlMPBHIFwm bePw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=9TLfWaf58UYL7wICLMCVVnhaOCpYf+H5DpQSRdiy6Cc=; b=XcOJWUfT0grVvZDRD2QioDneXfSmndwCnLaPEiG3RHlluqCqewuhePcn5sWcQip9H1 K7Tk0t+OYcHJlBWm2MMuoKyKmVBuw1giNy3zAv35/jegQ/2ZVb5nJoveUsEUNMQEj78D u+q1HWi5p6JDypYEeyBdg8kIpal8v29T4i/IrDg7PhsNhSGPxumH3KFuudiFCJUyxqwP BwReLuhO5+sAzobxFBzfxzI1RVtOz60jQAVgW9kU67tZOwoHaDS4VigyT5qc01JfsUcL TKWpGcHMFYsfw7k/haoiJk2lLfPptSYN8QBveboMW484utZzIjgshsWCasj6I4KZeSc/ sDCw== X-Gm-Message-State: AOAM531eGjD/RWruDnxa+mPtOolMUI0Oz3O3BKJyYj03SiXB8eTKgXNi oG+j7APaKbqdpAEk2C6WNAxBZONwexd0v8k3/QQ= X-Google-Smtp-Source: ABdhPJznzlwtgR/lC41/SY0FFtURTSnCC2xOHrCPe7akB5kk2L1nv9Me4GAJGApMzwCD081JTdMBkBEIq4IXR3L5M2Q= Sender: "samitolvanen via sendgmr" X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:f693:9fff:fef4:1b6d]) (user=samitolvanen job=sendgmr) by 2002:a25:cf0a:: with SMTP id f10mr7383764ybg.353.1606858650073; Tue, 01 Dec 2020 13:37:30 -0800 (PST) Date: Tue, 1 Dec 2020 13:36:59 -0800 In-Reply-To: <20201201213707.541432-1-samitolvanen@google.com> Message-Id: <20201201213707.541432-9-samitolvanen@google.com> Mime-Version: 1.0 References: <20201201213707.541432-1-samitolvanen@google.com> X-Mailer: git-send-email 2.29.2.576.ga3fc446d84-goog Subject: [PATCH v8 08/16] init: lto: fix PREL32 relocations From: Sami Tolvanen To: Masahiro Yamada , Steven Rostedt , Will Deacon Cc: Josh Poimboeuf , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org With LTO, the compiler can rename static functions to avoid global naming collisions. As initcall functions are typically static, renaming can break references to them in inline assembly. This change adds a global stub with a stable name for each initcall to fix the issue when PREL32 relocations are used. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- include/linux/init.h | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/include/linux/init.h b/include/linux/init.h index d466bea7ecba..27b9478dcdef 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -209,26 +209,49 @@ extern bool initcall_debug; */ #define __initcall_section(__sec, __iid) \ #__sec ".init.." #__iid + +/* + * With LTO, the compiler can rename static functions to avoid + * global naming collisions. We use a global stub function for + * initcalls to create a stable symbol name whose address can be + * taken in inline assembly when PREL32 relocations are used. + */ +#define __initcall_stub(fn, __iid, id) \ + __initcall_name(initstub, __iid, id) + +#define __define_initcall_stub(__stub, fn) \ + int __init __stub(void); \ + int __init __stub(void) \ + { \ + return fn(); \ + } \ + __ADDRESSABLE(__stub) #else #define __initcall_section(__sec, __iid) \ #__sec ".init" + +#define __initcall_stub(fn, __iid, id) fn + +#define __define_initcall_stub(__stub, fn) \ + __ADDRESSABLE(fn) #endif #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS -#define ____define_initcall(fn, __name, __sec) \ - __ADDRESSABLE(fn) \ +#define ____define_initcall(fn, __stub, __name, __sec) \ + __define_initcall_stub(__stub, fn) \ asm(".section \"" __sec "\", \"a\" \n" \ __stringify(__name) ": \n" \ - ".long " #fn " - . \n" \ + ".long " __stringify(__stub) " - . \n" \ ".previous \n"); #else -#define ____define_initcall(fn, __name, __sec) \ +#define ____define_initcall(fn, __unused, __name, __sec) \ static initcall_t __name __used \ __attribute__((__section__(__sec))) = fn; #endif #define __unique_initcall(fn, id, __sec, __iid) \ ____define_initcall(fn, \ + __initcall_stub(fn, __iid, id), \ __initcall_name(initcall, __iid, id), \ __initcall_section(__sec, __iid))