From patchwork Mon Sep 30 05:59:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 1132459 Return-Path: Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF215C4360C for ; Mon, 30 Sep 2019 06:02:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B032A20815 for ; Mon, 30 Sep 2019 06:02:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="sVJyT1RO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729635AbfI3GCz (ORCPT ); Mon, 30 Sep 2019 02:02:55 -0400 Received: from conuserg-10.nifty.com ([210.131.2.77]:65305 "EHLO conuserg-10.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726121AbfI3GCz (ORCPT ); Mon, 30 Sep 2019 02:02:55 -0400 Received: from localhost.localdomain (p14092-ipngnfx01kyoto.kyoto.ocn.ne.jp [153.142.97.92]) (authenticated) by conuserg-10.nifty.com with ESMTP id x8U60ANM011158; Mon, 30 Sep 2019 15:00:10 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-10.nifty.com x8U60ANM011158 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1569823213; bh=31RHoPop8t0h2pCPRnwABR+VMelvfuLJ6qwFWQxvRAk=; h=From:To:Cc:Subject:Date:From; b=sVJyT1ROU+6mzkZMRTb0M214/0QcKkmxRbNgDwh2q1TPJpEjPLOoE+y1jkVndgyce qBfr7v3nYiN5WSsx5xTwPYvHohsWcSS3AWwyVRw8Kxjd0CGrX8l5WcF76SmCvJPLCB wLRZ7C1/Z/zv9v8AVlB2BGhDmSvNQJ9bvuGi42d+JbBXGDfg0HZGGHEj7yDDLBV9nW EZkTGzP6wtIdqgD6DM5Lj4LA7FnlzH8Ocy6yp5agIZ7tdaiVh4E+Xb97KFsLgRin/o kTPCap5ub1TziurVW+1pbzwH+G3TNVeY+yJdYcAQRFzXXOrTa7s5zIJUtObrYVGCA2 ctH5uaN1kjx1g== X-Nifty-SrcIP: [153.142.97.92] From: Masahiro Yamada To: linux-arm-kernel@lists.infradead.org, Russell King Cc: Linus Torvalds , Olof Johansson , Arnd Bergmann , Nick Desaulniers , Nicolas Saenz Julienne , Masahiro Yamada , Julien Thierry , Russell King , Stefan Agner , Thomas Gleixner , Vincent Whitchurch , linux-kernel@vger.kernel.org Subject: [PATCH] ARM: fix __get_user_check() in case uaccess_* calls are not inlined Date: Mon, 30 Sep 2019 14:59:25 +0900 Message-Id: <20190930055925.25842-1-yamada.masahiro@socionext.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KernelCI reports that bcm2835_defconfig is no longer booting since commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING forcibly"): https://lkml.org/lkml/2019/9/26/825 I also received a regression report from Nicolas Saenz Julienne: https://lkml.org/lkml/2019/9/27/263 This problem has cropped up on arch/arm/config/bcm2835_defconfig because it enables CONFIG_CC_OPTIMIZE_FOR_SIZE. The compiler tends to prefer not inlining functions with -Os. I was able to reproduce it with other boards and defconfig files by manually enabling CONFIG_CC_OPTIMIZE_FOR_SIZE. The __get_user_check() specifically uses r0, r1, r2 registers. So, uaccess_save_and_enable() and uaccess_restore() must be inlined in order to avoid those registers being overwritten in the callees. Prior to commit 9012d011660e ("compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING"), the 'inline' marker was always enough for inlining functions, except on x86. Since that commit, all architectures can enable CONFIG_OPTIMIZE_INLINING. So, __always_inline is now the only guaranteed way of forcible inlining. I want to keep as much compiler's freedom as possible about the inlining decision. So, I changed the function call order instead of adding __always_inline around. Call uaccess_save_and_enable() before assigning the __p ("r0"), and uaccess_restore() after evacuating the __e ("r0"). Fixes: 9012d011660e ("compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING") Reported-by: "kernelci.org bot" Reported-by: Nicolas Saenz Julienne Signed-off-by: Masahiro Yamada Acked-by: Arnd Bergmann Tested-by: Nicolas Saenz Julienne Tested-by: Fabrizio Castro Tested-by: Geert Uytterhoeven --- arch/arm/include/asm/uaccess.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 303248e5b990..559f252d7e3c 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -191,11 +191,12 @@ extern int __get_user_64t_4(void *); #define __get_user_check(x, p) \ ({ \ unsigned long __limit = current_thread_info()->addr_limit - 1; \ + unsigned int __ua_flags = uaccess_save_and_enable(); \ register typeof(*(p)) __user *__p asm("r0") = (p); \ register __inttype(x) __r2 asm("r2"); \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \ - unsigned int __ua_flags = uaccess_save_and_enable(); \ + unsigned int __err; \ switch (sizeof(*(__p))) { \ case 1: \ if (sizeof((x)) >= 8) \ @@ -223,9 +224,10 @@ extern int __get_user_64t_4(void *); break; \ default: __e = __get_user_bad(); break; \ } \ - uaccess_restore(__ua_flags); \ + __err = __e; \ x = (typeof(*(p))) __r2; \ - __e; \ + uaccess_restore(__ua_flags); \ + __err; \ }) #define get_user(x, p) \