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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 2EDE2C433DB for ; Fri, 8 Jan 2021 22:24:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0694223A3C for ; Fri, 8 Jan 2021 22:24:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726761AbhAHWYN (ORCPT ); Fri, 8 Jan 2021 17:24:13 -0500 Received: from mga09.intel.com ([134.134.136.24]:1525 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725763AbhAHWYM (ORCPT ); Fri, 8 Jan 2021 17:24:12 -0500 IronPort-SDR: 41bHxkV0yZQ5kXHEsm0OURGHvxKIDzeXOuMKDZc4rbMgAGripvvnEDRheWkutdHYClpCfVP8bA fz8RZdao0XSw== X-IronPort-AV: E=McAfee;i="6000,8403,9858"; a="177810719" X-IronPort-AV: E=Sophos;i="5.79,332,1602572400"; d="scan'208";a="177810719" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2021 14:22:59 -0800 IronPort-SDR: 6AZfUQRjruUiq3waI6R4k01goON3OjB2cqqQj1j2GNQRPzZpyApD/F3AYswfgMRTmeJhb6rm1s +vA4n6WyeXBQ== X-IronPort-AV: E=Sophos;i="5.79,332,1602572400"; d="scan'208";a="423091296" Received: from agluck-desk2.sc.intel.com ([10.3.52.68]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2021 14:22:59 -0800 From: Tony Luck To: Borislav Petkov Cc: Tony Luck , x86@kernel.org, Andrew Morton , Peter Zijlstra , Darren Hart , Andy Lutomirski , linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/2] futex, x86/mce: Avoid double machine checks Date: Fri, 8 Jan 2021 14:22:51 -0800 Message-Id: <20210108222251.14391-3-tony.luck@intel.com> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20210108222251.14391-1-tony.luck@intel.com> References: <20210108222251.14391-1-tony.luck@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org futex_wait_setup() first tries to read the user value with page faults disabled (because it holds a lock, and so cannot sleep). If that read fails it drops the lock and tries again. But there are now two reasons why the user space read can fail. Either: 1) legacy case of a page fault, in which case it is reasonable to retry 2) machine check on the user address, bad idea to re-read Add some infrastructure to differentiate these cases. Signed-off-by: Tony Luck --- arch/x86/include/asm/mmu.h | 7 +++++++ arch/x86/kernel/cpu/mce/core.c | 10 ++++++++++ include/linux/mm.h | 4 ++++ kernel/futex.c | 3 +++ 4 files changed, 24 insertions(+) diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index 5d7494631ea9..a46c78381388 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -66,4 +66,11 @@ typedef struct { void leave_mm(int cpu); #define leave_mm leave_mm +#if defined(CONFIG_X86_MCE) && defined(CONFIG_MEMORY_FAILURE) +#undef arch_memory_failure +#define arch_memory_failure x86_memory_failure +#endif + +bool x86_memory_failure(u32 __user *addr); + #endif /* _ASM_X86_MMU_H */ diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 1bf11213e093..b27aa30290bb 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1236,6 +1236,16 @@ static void __mc_scan_banks(struct mce *m, struct pt_regs *regs, struct mce *fin *m = *final; } +bool x86_memory_failure(u32 __user *addr) +{ + if (current->mce_busy == 0) + return false; + + WARN_ON(current->mce_vaddr != addr); + + return true; +} + static void kill_me_now(struct callback_head *ch) { force_sig(SIGBUS); diff --git a/include/linux/mm.h b/include/linux/mm.h index ecdf8a8cd6ae..470708a71dd3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3177,5 +3177,9 @@ unsigned long wp_shared_mapping_range(struct address_space *mapping, extern int sysctl_nr_trim_pages; +#ifndef arch_memory_failure +#define arch_memory_failure(vaddr) (0) +#endif + #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */ diff --git a/kernel/futex.c b/kernel/futex.c index c47d1015d759..8fa2fc854026 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2658,6 +2658,9 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, if (ret) { queue_unlock(*hb); + if (arch_memory_failure(uaddr)) + return ret; + ret = get_user(uval, uaddr); if (ret) return ret; -- 2.21.1