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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 C01DBC433E0 for ; Mon, 1 Mar 2021 15:53:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 738FE64DE3 for ; Mon, 1 Mar 2021 15:53:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237461AbhCAPxa (ORCPT ); Mon, 1 Mar 2021 10:53:30 -0500 Received: from mail.skyhub.de ([5.9.137.197]:44432 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237394AbhCAPx3 (ORCPT ); Mon, 1 Mar 2021 10:53:29 -0500 Received: from zn.tnic (p200300ec2f03de000c49bde6bf5f8ea0.dip0.t-ipconnect.de [IPv6:2003:ec:2f03:de00:c49:bde6:bf5f:8ea0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 89E871EC0105; Mon, 1 Mar 2021 16:52:43 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1614613963; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=a4oJdFpxQg9VwC++9PZ/n66EH9Uyg5uXgGcU17/8q6g=; b=P2oo+rDN9qTQYwJH3/qzEiUUhEZuT5Y2oGLpKajp7d9lOdwBvDV86OTX1BSAcVyL/bZ1Jb z4xpMqdSczHw4fudawj7lpdSOAH1N9atj52HxDhaTyftc+XA2ELNMoXMa8aCjo0PWqBeO4 N6kITEOCjeOLapteI23oeWqaRg1tXXM= Date: Mon, 1 Mar 2021 16:52:34 +0100 From: Borislav Petkov 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 , 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" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Subject: Re: [PATCH v21 08/26] x86/mm: Introduce _PAGE_COW Message-ID: <20210301155234.GF6699@zn.tnic> References: <20210217222730.15819-1-yu-cheng.yu@intel.com> <20210217222730.15819-9-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210217222730.15819-9-yu-cheng.yu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Wed, Feb 17, 2021 at 02:27:12PM -0800, Yu-cheng Yu wrote: > @@ -182,7 +206,7 @@ static inline int pud_young(pud_t pud) > > static inline int pte_write(pte_t pte) > { > - return pte_flags(pte) & _PAGE_RW; Put here a comment along the lines of: /* * Shadow stack pages are always writable - but not by normal * instructions but only by shadow stack operations. Therefore, the * W=0, D=1 test. */ to make it clear what this means. > + return (pte_flags(pte) & _PAGE_RW) || pte_shstk(pte); > } > > static inline int pte_huge(pte_t pte) > @@ -314,6 +338,24 @@ static inline pte_t pte_clear_flags(pte_t pte, pteval_t clear) > return native_make_pte(v & ~clear); > } > > +static inline pte_t pte_make_cow(pte_t pte) pte_mkcow like the rest of the "pte_mkX" functions. And below too, for the other newly added pXd_make_* helpers. > static inline pmd_t pmd_mkdirty(pmd_t pmd) > { > - return pmd_set_flags(pmd, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); > + pmdval_t dirty = _PAGE_DIRTY; > + > + /* Avoid creating (HW)Dirty=1, Write=0 PMDs */ > + if (cpu_feature_enabled(X86_FEATURE_SHSTK) && !(pmd_flags(pmd) & _PAGE_RW)) !(pmd_write(pmd)) > + dirty = _PAGE_COW; > + > + return pmd_set_flags(pmd, dirty | _PAGE_SOFT_DIRTY); > +} ... > static inline pud_t pud_mkdirty(pud_t pud) > { > - return pud_set_flags(pud, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); > + pudval_t dirty = _PAGE_DIRTY; > + > + /* Avoid creating (HW)Dirty=1, Write=0 PUDs */ > + if (cpu_feature_enabled(X86_FEATURE_SHSTK) && !(pud_flags(pud) & _PAGE_RW)) !(pud_write(pud)) -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette