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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBFD1C4332F for ; Fri, 4 Nov 2022 22:42:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230208AbiKDWmi (ORCPT ); Fri, 4 Nov 2022 18:42:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230214AbiKDWlh (ORCPT ); Fri, 4 Nov 2022 18:41:37 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30E6E4E43F; Fri, 4 Nov 2022 15:39:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1667601582; x=1699137582; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=4aVCw5ODNp+SkJKgvPAW6TwS6KUC24UPNM4SuYiLUfg=; b=QOaLeC5hksoUbpgOqXEw0SygnmAo8GB4E2veLGgHokb83WqMo9qKmclN A5PkTqwoDrJ5DfvLC1pX3Gn5xaZe/IwPpSqXGrJbSYNHBVXD1v+bUcqOP Zib9IqyjDCv0z8EUx/Jj6muWAcQHcD7Tkwqq7vjJQTbmHt3CRI4vrABnY i9AU+UwabwTZk47lzfLJK7g7llXp2ZDr4RPf86aW6B1V2L/zILFlPHbMM VpiRpUzwVmBrcaGfqe3j0WoB1QC5mNbmCjrOPklGxP45H8FHajhL2ae19 VBEzDXbOddrcXqSutRnoECIEEz2gWBm+BBaHOUfyeUYoxbPP0ishNiA9F w==; X-IronPort-AV: E=McAfee;i="6500,9779,10521"; a="311840561" X-IronPort-AV: E=Sophos;i="5.96,138,1665471600"; d="scan'208";a="311840561" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Nov 2022 15:39:40 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10521"; a="668514089" X-IronPort-AV: E=Sophos;i="5.96,138,1665471600"; d="scan'208";a="668514089" Received: from adhjerms-mobl1.amr.corp.intel.com (HELO rpedgeco-desk.amr.corp.intel.com) ([10.212.227.68]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Nov 2022 15:39:39 -0700 From: Rick Edgecombe To: x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org Cc: rick.p.edgecombe@intel.com, Yu-cheng Yu Subject: [PATCH v3 20/37] mm/mprotect: Exclude shadow stack from preserve_write Date: Fri, 4 Nov 2022 15:35:47 -0700 Message-Id: <20221104223604.29615-21-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221104223604.29615-1-rick.p.edgecombe@intel.com> References: <20221104223604.29615-1-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org From: Yu-cheng Yu The x86 Control-flow Enforcement Technology (CET) feature includes a new type of memory called shadow stack. This shadow stack memory has some unusual properties, which requires some core mm changes to function properly. In change_pte_range(), when a PTE is changed for prot_numa, _PAGE_RW is preserved to avoid the additional write fault after the NUMA hinting fault. However, pte_write() now includes both normal writable and shadow stack (Write=0, Dirty=1) PTEs, but the latter does not have _PAGE_RW and has no need to preserve it. Exclude shadow stack from preserve_write test, and apply the same change to change_huge_pmd(). Tested-by: Pengfei Xu Tested-by: John Allen Signed-off-by: Yu-cheng Yu Reviewed-by: Kirill A. Shutemov Signed-off-by: Rick Edgecombe --- Yu-cheng v25: - Move is_shadow_stack_mapping() to a separate line. Yu-cheng v24: - Change arch_shadow_stack_mapping() to is_shadow_stack_mapping(). mm/huge_memory.c | 7 +++++++ mm/mprotect.c | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 73b9b78f8cf4..7643a4db1b50 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1803,6 +1803,13 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, return 0; preserve_write = prot_numa && pmd_write(*pmd); + + /* + * Preserve only normal writable huge PMD, but not shadow + * stack (RW=0, Dirty=1). + */ + if (vma->vm_flags & VM_SHADOW_STACK) + preserve_write = false; ret = 1; #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION diff --git a/mm/mprotect.c b/mm/mprotect.c index 668bfaa6ed2a..ea82ce5f38fe 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -115,6 +115,13 @@ static unsigned long change_pte_range(struct mmu_gather *tlb, pte_t ptent; bool preserve_write = prot_numa && pte_write(oldpte); + /* + * Preserve only normal writable PTE, but not shadow + * stack (RW=0, Dirty=1). + */ + if (vma->vm_flags & VM_SHADOW_STACK) + preserve_write = false; + /* * Avoid trapping faults against the zero or KSM * pages. See similar comment in change_huge_pmd. -- 2.17.1