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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 55D4EC5CFEB for ; Wed, 11 Jul 2018 09:10:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0390520854 for ; Wed, 11 Jul 2018 09:10:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="eSTn1Zy5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0390520854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732348AbeGKJNt (ORCPT ); Wed, 11 Jul 2018 05:13:49 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:60880 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726289AbeGKJNt (ORCPT ); Wed, 11 Jul 2018 05:13:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=axBSON5cvs4xwlba/fqyRyd7rPG8BRp78PXGOPrsffs=; b=eSTn1Zy5c/Aun+4usiHSDLp+M wgUUGJcLaFMiOOg2URSQvlxCY5ynPBHcRD1sSnmB9b7tRvnhXPsrDGtqggLQjBwqHBhOtE+qpa78Z D3xMoaMW6WtqxFPk84rnDXcFhehpXAmMxFg5RxtGXcYnB17IDfrQjbX7AayPZ0/GyReFR5oOtmYwj bYESxGDxIMMU8efDlu9egWY48SH5/olLkjJNdA0B0DlQOeQrmLLYNZIlfZ8r7TZvtEqFU/15fmJZP 6UUlbqu0g5FUG3Db+CSM5KTe8gEPTeR29TRI5/X4MeEB34OWmmLpBBLgz4RW6uB1gmSifmtT6k2QV mNAIfkiPQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fdB8h-0004nw-Q0; Wed, 11 Jul 2018 09:10:23 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4727320291063; Wed, 11 Jul 2018 11:10:22 +0200 (CEST) Date: Wed, 11 Jul 2018 11:10:22 +0200 From: Peter Zijlstra To: Yu-cheng Yu Cc: 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 , Cyrill Gorcunov , Dave Hansen , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , "Ravi V. Shankar" , Vedvyas Shanbhogue Subject: Re: [RFC PATCH v2 14/27] mm: Handle THP/HugeTLB shadow stack page fault Message-ID: <20180711091022.GT2476@hirez.programming.kicks-ass.net> References: <20180710222639.8241-1-yu-cheng.yu@intel.com> <20180710222639.8241-15-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180710222639.8241-15-yu-cheng.yu@intel.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 10, 2018 at 03:26:26PM -0700, Yu-cheng Yu wrote: > diff --git a/mm/memory.c b/mm/memory.c > index a2695dbc0418..f7c46d61eaea 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4108,7 +4108,13 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > if (pmd_protnone(orig_pmd) && vma_is_accessible(vma)) > return do_huge_pmd_numa_page(&vmf, orig_pmd); > > - if (dirty && !pmd_write(orig_pmd)) { > + /* > + * Shadow stack trans huge PMDs are copy-on-access, > + * so wp_huge_pmd() on them no mater if we have a > + * write fault or not. > + */ > + if (is_shstk_mapping(vma->vm_flags) || > + (dirty && !pmd_write(orig_pmd))) { > ret = wp_huge_pmd(&vmf, orig_pmd); > if (!(ret & VM_FAULT_FALLBACK)) > return ret; Can't we do this (and the do_wp_page thing) by setting FAULT_FLAG_WRITE in the arch fault handler on shadow stack faults?