From patchwork Fri Sep 18 20:14:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11786103 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 5647E139A for ; Fri, 18 Sep 2020 20:16:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3175B23888 for ; Fri, 18 Sep 2020 20:16:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DmFIi1OV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726617AbgIRUQX (ORCPT ); Fri, 18 Sep 2020 16:16:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726599AbgIRUPa (ORCPT ); Fri, 18 Sep 2020 16:15:30 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 35E68C0613DA for ; Fri, 18 Sep 2020 13:15:22 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id z40so6609837ybi.3 for ; Fri, 18 Sep 2020 13:15:22 -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=XxAfB/P/jhgYhoVgUFO0krm50APtT+WWyqbk+4ioXTk=; b=DmFIi1OVxsFoFg92oFWH2VPRTDu4wE9Rmg6s0bvmp2TuRAbHoKv6/fPJl1fuBdrjn7 VWzTK0IQDIyNMi23xcASGWrTPyHk0S7e0w5yoc9SZ/pQdToneOnD9OdIiO2v+KW9gj7y 9zlTW9p+FprZHdCq5rpUHZD/0n8xUda24onsLXZ66jqtU8LkEkm1FqYFsbOXQY9gVmIy ib61pYrKwyraXm+h5krhXzdEdTlzkFDCT45b4X7mDBl5iBONcOD1ksa0s/BExbykYGIB wn/5Ms/kn3W2LpKihjogJj5qO+B0a2gDh6bG4SxQfn0sDbgdsmBBEBBNuSsdj96B5Er/ uLBg== 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=XxAfB/P/jhgYhoVgUFO0krm50APtT+WWyqbk+4ioXTk=; b=mpIV+pjuSwZdtsCV3tHAIbD0VHup8Kretw1vHZdhMa/qZjA0eUa/1SyjLwTJpkaxZY cWlx3EI1kAKArjuo3vXi5b6XrcxTq1ljl4JuznReUMR361R3yu1mEvs7Lbvkm9E+gACU JlsMiuLzcKAe2heltbaP/9e+48jutaJv1l6zUKigDwNdGE3+M3aikrlmuTtxbeAjxE5E GpwheaK93PW+ggfzzDARTWuCR66nh5AkbzN621nIe4CQ+H7GM6KieAbuFIa6ugEeues0 8CtOUtEu2SUdJlDhKNy838zCmrvgHqa1NOeQ/einbGYtD4WZWcBdw1nGK3QIlaKpHGWg jz4A== X-Gm-Message-State: AOAM533YbdNrvxuQVtNrKMNAaKrho/sy0Sw04AG8BX1VZx+KuQFMAUGQ pfW9IRlprobegTp51/AsD9BnxtgtK8Oq93CiSrA= X-Google-Smtp-Source: ABdhPJy2KjHLDlLlwF3FZGYG4YjeDAk7DNS4RO40Qo5O+7UwvN2wgXBj6NsmIvpwMLwrVraEYVu5qDWHVwe1uVR3arc= 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:e009:: with SMTP id x9mr6392448ybg.373.1600460121392; Fri, 18 Sep 2020 13:15:21 -0700 (PDT) Date: Fri, 18 Sep 2020 13:14:24 -0700 In-Reply-To: <20200918201436.2932360-1-samitolvanen@google.com> Message-Id: <20200918201436.2932360-19-samitolvanen@google.com> Mime-Version: 1.0 References: <20200918201436.2932360-1-samitolvanen@google.com> X-Mailer: git-send-email 2.28.0.681.g6f77f65b4e-goog Subject: [PATCH v3 18/30] init: lto: fix PREL32 relocations From: Sami Tolvanen To: Masahiro Yamada , Will Deacon Cc: Peter Zijlstra , Steven Rostedt , 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))