From patchwork Tue Sep 29 21:46:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11807049 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D45D913B2 for ; Tue, 29 Sep 2020 21:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B18D421974 for ; Tue, 29 Sep 2020 21:47:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="b55hwPid" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728895AbgI2VrW (ORCPT ); Tue, 29 Sep 2020 17:47:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728074AbgI2VrV (ORCPT ); Tue, 29 Sep 2020 17:47:21 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EE2CC0613D4 for ; Tue, 29 Sep 2020 14:47:14 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id s4so4059630pgk.17 for ; Tue, 29 Sep 2020 14:47:14 -0700 (PDT) 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=/vP7q5BBB0uTfRm2AgwdilGSRfsWzFPQ2WkTiyoFr6c=; b=b55hwPidpBtwXSYzPL7nG9/Vda7JuMVr/EGJixbfG0vXQwUBtPjkDoj3MJOTqZMsWM vzguUIrKQvSlcJMS9LcTLx25efyz9HzS/XNyEl+Vmt3JZFYWS9Xi9CW480UD18Iv8V/8 Zv0q3PdFWw+MxCu1kPSRKo5b5kauZeRMwrGkfiXKdlBUKbyUb+Mx09RiNdFeO5g1b1k/ MGs4GivcBr1kLWAINFKbVMCXqvyatQdyLKZ3K2d+FSPXYNUWpizBFCZ7ExOm+k6gsGZr 9pRIvsrPB/pkdVgUtISLhxoJY5If1dpdNi3Vrr64TIoPSMdOxtuHEgcrwzGEARSD2d7Y rM6w== 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=/vP7q5BBB0uTfRm2AgwdilGSRfsWzFPQ2WkTiyoFr6c=; b=WyAs/TNlLnYaHH2CorFqC95oVMkifOnPh0lGFjE6AAxOd/V0Uj8gJj/AZkRcL+tcKQ +7becuETsZNbKetbG5S4ta69t+qcpCfYHdpQshDLD9NhwKn2IuvKR0gw3TddZSvXwGjA pfzSb/4aDVZXwao1Vwn4h/945KR83c/DI4ZKIo1z4zBVMYxkkpyB8E/3GLkemOMqSzpj PkXp6iIVRVE+puwZToiN1p05ydE+TSnMQctAAFMkuUuj5vqn2+gAKmB44zdKTaiwqcQF hUvYMI5CJ/osn5QP+vsCeNreDLt2yoBMgLBqjKTEVdlg1l5iRSxuzLgd1HE5bWzMUbWV KOtw== X-Gm-Message-State: AOAM532gazQ7kdzTnGO8QLszUu28jZKiTa+q4BlseTT9l/yMgENpeflC oFQcOaLXpZpxEp32QhYezIoGmZdhdyv9d9QAyfw= X-Google-Smtp-Source: ABdhPJzwunn8/64a+JvNFjvDzCLI2jH4jHUm6kjJgtH3L7MwJCKNh04+JiRlVd1IwEJ79vkmzQAo7H0Oi+ZByvS+NaY= 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:a63:e813:: with SMTP id s19mr4805529pgh.33.1601416033950; Tue, 29 Sep 2020 14:47:13 -0700 (PDT) Date: Tue, 29 Sep 2020 14:46:20 -0700 In-Reply-To: <20200929214631.3516445-1-samitolvanen@google.com> Message-Id: <20200929214631.3516445-19-samitolvanen@google.com> Mime-Version: 1.0 References: <20200929214631.3516445-1-samitolvanen@google.com> X-Mailer: git-send-email 2.28.0.709.gb0816b6eb0-goog Subject: [PATCH v4 18/29] init: lto: fix PREL32 relocations From: Sami Tolvanen To: Masahiro Yamada , Will Deacon , Steven Rostedt Cc: 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, x86@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 af638cd6dd52..cea63f7e7705 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))