From nobody Sun Feb 8 03:27:32 2026 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 33326C001DC for ; Wed, 19 Jul 2023 22:50:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231447AbjGSWuQ (ORCPT ); Wed, 19 Jul 2023 18:50:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231349AbjGSWsB (ORCPT ); Wed, 19 Jul 2023 18:48:01 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B37F1272E; Wed, 19 Jul 2023 15:47:46 -0700 (PDT) Date: Wed, 19 Jul 2023 22:47:43 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1689806864; h=from:from:sender:sender:reply-to: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:content-transfer-encoding; bh=8f5DMXEf7X81RbgTGU0XSKH5lIM6jC9ZTg0YCnkAQL0=; b=O5g/w8jpBDFiL+XPMHsq5+ZRw+Hfm4HaAmZs4mnO2EffiQ4Uj3/gM3UW6AXiAHlPLy24O+ hxu5E/9szqX70LFZY0ijZhl1xMP3oL3Va9L8Edajy7KGSTyKQ36/ft/XKrtJOam0qEHRr0 srAlu1IA/Q+mVhwyFr59/DVA8a10ZgJiPwVVhL4hoTv/yVm3qTkUoOuvZR0mYp8CaaTt+i wT8HCZaHErnF1mvblGhOP+wUS0ljtktfx6XH0lVgv01CUcwmPbMWRviu3eQuIgQrmaZBNd gtAR9UEYD+KOyq60QFb0i41IpPBOrRN5xq/fI+OcPBFDX0dCwRwsG7Tr2F3S+g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1689806864; h=from:from:sender:sender:reply-to: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:content-transfer-encoding; bh=8f5DMXEf7X81RbgTGU0XSKH5lIM6jC9ZTg0YCnkAQL0=; b=lGO9mS1rcZnTxOYhX8Kp0H8dfctw2ciTWJ0Ll416tc+XSUNut2dDLklurNyWmu8o/hHp9G WuIG9H41ckJx04Bw== From: "tip-bot2 for Rick Edgecombe" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/shstk] mm: Move pte/pmd_mkwrite() callers with no VMA to _novma() Cc: Rick Edgecombe , Dave Hansen , "Mike Rapoport (IBM)" , David Hildenbrand , x86@kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Message-ID: <168980686350.28540.1064645086568907964.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/shstk branch of tip: Commit-ID: 6ecc21bb432dab7241bcbd766ecd1b15620c75c3 Gitweb: https://git.kernel.org/tip/6ecc21bb432dab7241bcbd766ecd1b156= 20c75c3 Author: Rick Edgecombe AuthorDate: Mon, 12 Jun 2023 17:10:28 -07:00 Committer: Rick Edgecombe CommitterDate: Tue, 11 Jul 2023 14:10:57 -07:00 mm: Move pte/pmd_mkwrite() callers with no VMA to _novma() The x86 Shadow stack 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. One of these unusual properties is that shadow stack memory is writable, but only in limited ways. These limits are applied via a specific PTE bit combination. Nevertheless, the memory is writable, and core mm code will need to apply the writable permissions in the typical paths that call pte_mkwrite(). Future patches will make pte_mkwrite() take a VMA, so that the x86 implementation of it can know whether to create regular writable or shadow stack mappings. But there are a couple of challenges to this. Modifying the signatures of each arch pte_mkwrite() implementation would be error prone because some are generated with macros and would need to be re-implemented. Also, some pte_mkwrite() callers operate on kernel memory without a VMA. So this can be done in a three step process. First pte_mkwrite() can be renamed to pte_mkwrite_novma() in each arch, with a generic pte_mkwrite() added that just calls pte_mkwrite_novma(). Next callers without a VMA can be moved to pte_mkwrite_novma(). And lastly, pte_mkwrite() and all callers can be changed to take/pass a VMA. Earlier work did the first step, so next move the callers that don't have a VMA to pte_mkwrite_novma(). Also do the same for pmd_mkwrite(). This will be ok for the shadow stack feature, as these callers are on kernel memory which will not need to be made shadow stack, and the other architectures only currently support one type of memory in pte_mkwrite() Signed-off-by: Rick Edgecombe Signed-off-by: Dave Hansen Reviewed-by: Mike Rapoport (IBM) Acked-by: David Hildenbrand Link: https://lore.kernel.org/all/20230613001108.3040476-3-rick.p.edgecombe= %40intel.com --- arch/arm64/mm/trans_pgd.c | 4 ++-- arch/s390/mm/pageattr.c | 4 ++-- arch/x86/xen/mmu_pv.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c index 4ea2eef..a01493f 100644 --- a/arch/arm64/mm/trans_pgd.c +++ b/arch/arm64/mm/trans_pgd.c @@ -40,7 +40,7 @@ static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, u= nsigned long addr) * read only (code, rodata). Clear the RDONLY bit from * the temporary mappings we use during restore. */ - set_pte(dst_ptep, pte_mkwrite(pte)); + set_pte(dst_ptep, pte_mkwrite_novma(pte)); } else if (debug_pagealloc_enabled() && !pte_none(pte)) { /* * debug_pagealloc will removed the PTE_VALID bit if @@ -53,7 +53,7 @@ static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, u= nsigned long addr) */ BUG_ON(!pfn_valid(pte_pfn(pte))); =20 - set_pte(dst_ptep, pte_mkpresent(pte_mkwrite(pte))); + set_pte(dst_ptep, pte_mkpresent(pte_mkwrite_novma(pte))); } } =20 diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index ca5a418..e5ec762 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -98,7 +98,7 @@ static int walk_pte_level(pmd_t *pmdp, unsigned long addr= , unsigned long end, if (flags & SET_MEMORY_RO) new =3D pte_wrprotect(new); else if (flags & SET_MEMORY_RW) - new =3D pte_mkwrite(pte_mkdirty(new)); + new =3D pte_mkwrite_novma(pte_mkdirty(new)); if (flags & SET_MEMORY_NX) new =3D set_pte_bit(new, __pgprot(_PAGE_NOEXEC)); else if (flags & SET_MEMORY_X) @@ -156,7 +156,7 @@ static void modify_pmd_page(pmd_t *pmdp, unsigned long = addr, if (flags & SET_MEMORY_RO) new =3D pmd_wrprotect(new); else if (flags & SET_MEMORY_RW) - new =3D pmd_mkwrite(pmd_mkdirty(new)); + new =3D pmd_mkwrite_novma(pmd_mkdirty(new)); if (flags & SET_MEMORY_NX) new =3D set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC)); else if (flags & SET_MEMORY_X) diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index e0a9751..ccf3d30 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -166,7 +166,7 @@ void make_lowmem_page_readwrite(void *vaddr) if (pte =3D=3D NULL) return; /* vaddr missing */ =20 - ptev =3D pte_mkwrite(*pte); + ptev =3D pte_mkwrite_novma(*pte); =20 if (HYPERVISOR_update_va_mapping(address, ptev, 0)) BUG();