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=-12.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 91782C43219 for ; Tue, 30 Apr 2019 11:17:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E8622173E for ; Tue, 30 Apr 2019 11:17:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="tiqcCWk5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727419AbfD3LRy (ORCPT ); Tue, 30 Apr 2019 07:17:54 -0400 Received: from terminus.zytor.com ([198.137.202.136]:42787 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726648AbfD3LRv (ORCPT ); Tue, 30 Apr 2019 07:17:51 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x3UBHIMt1346785 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Tue, 30 Apr 2019 04:17:18 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 terminus.zytor.com x3UBHIMt1346785 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019041745; t=1556623039; bh=U0dRxSN+YqY2hUrN8UV7cxDakgiQX/5QEsi+3wBp5Ac=; h=Date:From:Cc:Reply-To:In-Reply-To:References:To:Subject:From; b=tiqcCWk5SIYF+VnGYPEiPHdNI39LtMv56xQyq5Y2X6UdgD1kg0BCZO4tcHoiIiTXA fWOSsenbHhzL4c5i5xtAZU2+MXs0A0ZuvEvoH3vazLs/6eKGPBLj0d7KW1ZCwaRrZd aNmk+RT6/gm54+hzu5io2W7oYxO05xcKWDw1ewxzz3XMeetEhaC+00QTddtVuU9F1C Ad6XbFEy4Y4SPhO3W2rH/O/jNPEgkfSLyw6oVjT/LSAt4qxIf/Q42mru3qWCEgkVm6 6W2V9HNHs62WG7MGisd+ZIbG7c4wecW26+0KncG3ekN+7sQ2IXRlpEYOrY5dfZXpVs fE6ufzDIzGBDQ== Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x3UBHILM1346780; Tue, 30 Apr 2019 04:17:18 -0700 Date: Tue, 30 Apr 2019 04:17:18 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Nadav Amit Message-ID: Cc: bp@alien8.de, tglx@linutronix.de, hpa@zytor.com, rick.p.edgecombe@intel.com, peterz@infradead.org, mingo@kernel.org, akpm@linux-foundation.org, will.deacon@arm.com, luto@kernel.org, ard.biesheuvel@linaro.org, deneen.t.dock@intel.com, linux-kernel@vger.kernel.org, namit@vmware.com, riel@surriel.com, kristen@linux.intel.com, linux_dti@icloud.com, torvalds@linux-foundation.org, dave.hansen@linux.intel.com, kernel-hardening@lists.openwall.com Reply-To: riel@surriel.com, kristen@linux.intel.com, linux_dti@icloud.com, namit@vmware.com, kernel-hardening@lists.openwall.com, dave.hansen@linux.intel.com, torvalds@linux-foundation.org, mingo@kernel.org, akpm@linux-foundation.org, peterz@infradead.org, bp@alien8.de, tglx@linutronix.de, hpa@zytor.com, rick.p.edgecombe@intel.com, linux-kernel@vger.kernel.org, ard.biesheuvel@linaro.org, deneen.t.dock@intel.com, will.deacon@arm.com, luto@kernel.org In-Reply-To: <20190426001143.4983-5-namit@vmware.com> References: <20190426001143.4983-5-namit@vmware.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/mm: Save debug registers when loading a temporary mm Git-Commit-ID: d97080ebed7811a53c931032a284166ee46b9565 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: d97080ebed7811a53c931032a284166ee46b9565 Gitweb: https://git.kernel.org/tip/d97080ebed7811a53c931032a284166ee46b9565 Author: Nadav Amit AuthorDate: Thu, 25 Apr 2019 17:11:24 -0700 Committer: Ingo Molnar CommitDate: Tue, 30 Apr 2019 12:37:50 +0200 x86/mm: Save debug registers when loading a temporary mm Prevent user watchpoints from mistakenly firing while the temporary mm is being used. As the addresses of the temporary mm might overlap those of the user-process, this is necessary to prevent wrong signals or worse things from happening. Signed-off-by: Nadav Amit Signed-off-by: Rick Edgecombe Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Cc: Cc: Cc: Cc: Cc: Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Rik van Riel Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190426001143.4983-5-namit@vmware.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/mmu_context.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 24dc3b810970..93dff1963337 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -13,6 +13,7 @@ #include #include #include +#include extern atomic64_t last_mm_ctx_id; @@ -380,6 +381,21 @@ static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm) lockdep_assert_irqs_disabled(); temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm); switch_mm_irqs_off(NULL, mm, current); + + /* + * If breakpoints are enabled, disable them while the temporary mm is + * used. Userspace might set up watchpoints on addresses that are used + * in the temporary mm, which would lead to wrong signals being sent or + * crashes. + * + * Note that breakpoints are not disabled selectively, which also causes + * kernel breakpoints (e.g., perf's) to be disabled. This might be + * undesirable, but still seems reasonable as the code that runs in the + * temporary mm should be short. + */ + if (hw_breakpoint_active()) + hw_breakpoint_disable(); + return temp_state; } @@ -387,6 +403,13 @@ static inline void unuse_temporary_mm(temp_mm_state_t prev_state) { lockdep_assert_irqs_disabled(); switch_mm_irqs_off(NULL, prev_state.mm, current); + + /* + * Restore the breakpoints if they were disabled before the temporary mm + * was loaded. + */ + if (hw_breakpoint_active()) + hw_breakpoint_restore(); } #endif /* _ASM_X86_MMU_CONTEXT_H */