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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 C03BFC43381 for ; Wed, 20 Mar 2019 02:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F56A217F4 for ; Wed, 20 Mar 2019 02:08:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727821AbfCTCId (ORCPT ); Tue, 19 Mar 2019 22:08:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47180 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727192AbfCTCId (ORCPT ); Tue, 19 Mar 2019 22:08:33 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A40623086205; Wed, 20 Mar 2019 02:08:32 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id EB86660634; Wed, 20 Mar 2019 02:08:26 +0000 (UTC) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: David Hildenbrand , Hugh Dickins , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , peterx@redhat.com, Martin Cracauer , Shaohua Li , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Marty McFadden , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: [PATCH v3 12/28] userfaultfd: wp: apply _PAGE_UFFD_WP bit Date: Wed, 20 Mar 2019 10:06:26 +0800 Message-Id: <20190320020642.4000-13-peterx@redhat.com> In-Reply-To: <20190320020642.4000-1-peterx@redhat.com> References: <20190320020642.4000-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Wed, 20 Mar 2019 02:08:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Firstly, introduce two new flags MM_CP_UFFD_WP[_RESOLVE] for change_protection() when used with uffd-wp and make sure the two new flags are exclusively used. Then, - For MM_CP_UFFD_WP: apply the _PAGE_UFFD_WP bit and remove _PAGE_RW when a range of memory is write protected by uffd - For MM_CP_UFFD_WP_RESOLVE: remove the _PAGE_UFFD_WP bit and recover _PAGE_RW when write protection is resolved from userspace And use this new interface in mwriteprotect_range() to replace the old MM_CP_DIRTY_ACCT. Do this change for both PTEs and huge PMDs. Then we can start to identify which PTE/PMD is write protected by general (e.g., COW or soft dirty tracking), and which is for userfaultfd-wp. Since we should keep the _PAGE_UFFD_WP when doing pte_modify(), add it into _PAGE_CHG_MASK as well. Meanwhile, since we have this new bit, we can be even more strict when detecting uffd-wp page faults in either do_wp_page() or wp_huge_pmd(). Reviewed-by: Jerome Glisse Reviewed-by: Mike Rapoport Signed-off-by: Peter Xu --- include/linux/mm.h | 5 +++++ mm/huge_memory.c | 14 +++++++++++++- mm/memory.c | 4 ++-- mm/mprotect.c | 12 ++++++++++++ mm/userfaultfd.c | 8 ++++++-- 5 files changed, 38 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 937559a74dc4..b39efe5ca7f6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1693,6 +1693,11 @@ extern unsigned long move_page_tables(struct vm_area_struct *vma, #define MM_CP_DIRTY_ACCT (1UL << 0) /* Whether this protection change is for NUMA hints */ #define MM_CP_PROT_NUMA (1UL << 1) +/* Whether this change is for write protecting */ +#define MM_CP_UFFD_WP (1UL << 2) /* do wp */ +#define MM_CP_UFFD_WP_RESOLVE (1UL << 3) /* Resolve wp */ +#define MM_CP_UFFD_WP_ALL (MM_CP_UFFD_WP | \ + MM_CP_UFFD_WP_RESOLVE) extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, unsigned long end, pgprot_t newprot, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8d65b0f041f9..817335b443c2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1868,6 +1868,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, bool preserve_write; int ret; bool prot_numa = cp_flags & MM_CP_PROT_NUMA; + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; ptl = __pmd_trans_huge_lock(pmd, vma); if (!ptl) @@ -1934,6 +1936,13 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, entry = pmd_modify(entry, newprot); if (preserve_write) entry = pmd_mk_savedwrite(entry); + if (uffd_wp) { + entry = pmd_wrprotect(entry); + entry = pmd_mkuffd_wp(entry); + } else if (uffd_wp_resolve) { + entry = pmd_mkwrite(entry); + entry = pmd_clear_uffd_wp(entry); + } ret = HPAGE_PMD_NR; set_pmd_at(mm, addr, pmd, entry); BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); @@ -2083,7 +2092,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, struct page *page; pgtable_t pgtable; pmd_t old_pmd, _pmd; - bool young, write, soft_dirty, pmd_migration = false; + bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; unsigned long addr; int i; @@ -2165,6 +2174,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, write = pmd_write(old_pmd); young = pmd_young(old_pmd); soft_dirty = pmd_soft_dirty(old_pmd); + uffd_wp = pmd_uffd_wp(old_pmd); } VM_BUG_ON_PAGE(!page_count(page), page); page_ref_add(page, HPAGE_PMD_NR - 1); @@ -2198,6 +2208,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, entry = pte_mkold(entry); if (soft_dirty) entry = pte_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_mkuffd_wp(entry); } pte = pte_offset_map(&_pmd, addr); BUG_ON(!pte_none(*pte)); diff --git a/mm/memory.c b/mm/memory.c index 567686ec086d..50c2990648ab 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2483,7 +2483,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; - if (userfaultfd_wp(vma)) { + if (userfaultfd_pte_wp(vma, *vmf->pte)) { pte_unmap_unlock(vmf->pte, vmf->ptl); return handle_userfault(vmf, VM_UFFD_WP); } @@ -3690,7 +3690,7 @@ static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd) { if (vma_is_anonymous(vmf->vma)) { - if (userfaultfd_wp(vmf->vma)) + if (userfaultfd_huge_pmd_wp(vmf->vma, orig_pmd)) return handle_userfault(vmf, VM_UFFD_WP); return do_huge_pmd_wp_page(vmf, orig_pmd); } diff --git a/mm/mprotect.c b/mm/mprotect.c index a6ba448c8565..9d4433044c21 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -46,6 +46,8 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, int target_node = NUMA_NO_NODE; bool dirty_accountable = cp_flags & MM_CP_DIRTY_ACCT; bool prot_numa = cp_flags & MM_CP_PROT_NUMA; + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; /* * Can be called with only the mmap_sem for reading by @@ -117,6 +119,14 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, if (preserve_write) ptent = pte_mk_savedwrite(ptent); + if (uffd_wp) { + ptent = pte_wrprotect(ptent); + ptent = pte_mkuffd_wp(ptent); + } else if (uffd_wp_resolve) { + ptent = pte_mkwrite(ptent); + ptent = pte_clear_uffd_wp(ptent); + } + /* Avoid taking write faults for known dirty pages */ if (dirty_accountable && pte_dirty(ptent) && (pte_soft_dirty(ptent) || @@ -301,6 +311,8 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, { unsigned long pages; + BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); + if (is_vm_hugetlb_page(vma)) pages = hugetlb_change_protection(vma, start, end, newprot); else diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index eaecc21806da..240de2a8492d 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -73,8 +73,12 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, goto out_release; _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); - if ((dst_vma->vm_flags & VM_WRITE) && !wp_copy) - _dst_pte = pte_mkwrite(_dst_pte); + if (dst_vma->vm_flags & VM_WRITE) { + if (wp_copy) + _dst_pte = pte_mkuffd_wp(_dst_pte); + else + _dst_pte = pte_mkwrite(_dst_pte); + } dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); if (dst_vma->vm_file) { -- 2.17.1