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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
	Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
	Jerome Glisse <jglisse@redhat.com>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	peterx@redhat.com, Martin Cracauer <cracauer@cons.org>,
	Shaohua Li <shli@fb.com>, Marty McFadden <mcfadden8@llnl.gov>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Denis Plotnikov <dplotnikov@virtuozzo.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Mel Gorman <mgorman@suse.de>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	Rik van Riel <riel@redhat.com>
Subject: [PATCH v2 20/26] userfaultfd: wp: support write protection for userfault vma range
Date: Tue, 12 Feb 2019 10:56:26 +0800	[thread overview]
Message-ID: <20190212025632.28946-21-peterx@redhat.com> (raw)
In-Reply-To: <20190212025632.28946-1-peterx@redhat.com>

From: Shaohua Li <shli@fb.com>

Add API to enable/disable writeprotect a vma range. Unlike mprotect,
this doesn't split/merge vmas.

Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
[peterx:
 - use the helper to find VMA;
 - return -ENOENT if not found to match mcopy case;
 - use the new MM_CP_UFFD_WP* flags for change_protection
 - check against mmap_changing for failures]
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/linux/userfaultfd_k.h |  3 ++
 mm/userfaultfd.c              | 54 +++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 765ce884cec0..8f6e6ed544fb 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -39,6 +39,9 @@ extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
 			      unsigned long dst_start,
 			      unsigned long len,
 			      bool *mmap_changing);
+extern int mwriteprotect_range(struct mm_struct *dst_mm,
+			       unsigned long start, unsigned long len,
+			       bool enable_wp, bool *mmap_changing);
 
 /* mm helpers */
 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index fefa81c301b7..529d180bb4d7 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -639,3 +639,57 @@ ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
 {
 	return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0);
 }
+
+int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
+			unsigned long len, bool enable_wp, bool *mmap_changing)
+{
+	struct vm_area_struct *dst_vma;
+	pgprot_t newprot;
+	int err;
+
+	/*
+	 * Sanitize the command parameters:
+	 */
+	BUG_ON(start & ~PAGE_MASK);
+	BUG_ON(len & ~PAGE_MASK);
+
+	/* Does the address range wrap, or is the span zero-sized? */
+	BUG_ON(start + len <= start);
+
+	down_read(&dst_mm->mmap_sem);
+
+	/*
+	 * If memory mappings are changing because of non-cooperative
+	 * operation (e.g. mremap) running in parallel, bail out and
+	 * request the user to retry later
+	 */
+	err = -EAGAIN;
+	if (mmap_changing && READ_ONCE(*mmap_changing))
+		goto out_unlock;
+
+	err = -ENOENT;
+	dst_vma = vma_find_uffd(dst_mm, start, len);
+	/*
+	 * Make sure the vma is not shared, that the dst range is
+	 * both valid and fully within a single existing vma.
+	 */
+	if (!dst_vma || (dst_vma->vm_flags & VM_SHARED))
+		goto out_unlock;
+	if (!userfaultfd_wp(dst_vma))
+		goto out_unlock;
+	if (!vma_is_anonymous(dst_vma))
+		goto out_unlock;
+
+	if (enable_wp)
+		newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE));
+	else
+		newprot = vm_get_page_prot(dst_vma->vm_flags);
+
+	change_protection(dst_vma, start, start + len, newprot,
+			  enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE);
+
+	err = 0;
+out_unlock:
+	up_read(&dst_mm->mmap_sem);
+	return err;
+}
-- 
2.17.1


  parent reply	other threads:[~2019-02-12  3:00 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-12  2:56 [PATCH v2 00/26] userfaultfd: write protection support Peter Xu
2019-02-12  2:56 ` [PATCH v2 01/26] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-02-21 15:17   ` Jerome Glisse
2019-02-22  3:42     ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 02/26] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-02-21 15:29   ` Jerome Glisse
2019-02-22  3:51     ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 03/26] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-02-21 15:34   ` Jerome Glisse
2019-02-12  2:56 ` [PATCH v2 04/26] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-02-13  3:34   ` Peter Xu
2019-02-20 11:48     ` Peter Xu
2019-02-21  8:56   ` [PATCH v2.1 " Peter Xu
2019-02-21 15:53     ` Jerome Glisse
2019-02-22  4:25       ` Peter Xu
2019-02-22 15:11         ` Jerome Glisse
2019-02-25  6:19           ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 05/26] mm: gup: " Peter Xu
2019-02-21 16:06   ` Jerome Glisse
2019-02-22  4:41     ` Peter Xu
2019-02-22 15:13       ` Jerome Glisse
2019-02-12  2:56 ` [PATCH v2 06/26] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-02-21 16:07   ` Jerome Glisse
2019-02-25 15:41   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 07/26] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-02-21 16:25   ` Jerome Glisse
2019-02-25 15:43   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 08/26] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-02-21 17:20   ` Jerome Glisse
2019-02-25 15:48   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 09/26] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-02-21 17:21   ` Jerome Glisse
2019-02-25 17:12   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 10/26] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-02-21 17:29   ` Jerome Glisse
2019-02-22  7:11     ` Peter Xu
2019-02-22 15:15       ` Jerome Glisse
2019-02-25  6:45         ` Peter Xu
2019-02-25 15:58   ` Mike Rapoport
2019-02-26  5:09     ` Peter Xu
2019-02-26  8:28       ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 11/26] mm: merge parameters for change_protection() Peter Xu
2019-02-21 17:32   ` Jerome Glisse
2019-02-12  2:56 ` [PATCH v2 12/26] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-02-21 17:44   ` Jerome Glisse
2019-02-22  7:31     ` Peter Xu
2019-02-22 15:17       ` Jerome Glisse
2019-02-25 18:00   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 13/26] mm: export wp_page_copy() Peter Xu
2019-02-21 17:44   ` Jerome Glisse
2019-02-12  2:56 ` [PATCH v2 14/26] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-02-21 18:04   ` Jerome Glisse
2019-02-22  8:46     ` Peter Xu
2019-02-22 15:35       ` Jerome Glisse
2019-02-25  7:13         ` Peter Xu
2019-02-25 15:32           ` Jerome Glisse
2019-02-12  2:56 ` [PATCH v2 15/26] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-02-21 18:06   ` Jerome Glisse
2019-02-22  9:09     ` Peter Xu
2019-02-22 15:36       ` Jerome Glisse
2019-02-25 18:19   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 16/26] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-02-21 18:07   ` Jerome Glisse
2019-02-25 18:20   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 17/26] userfaultfd: wp: support swap and page migration Peter Xu
2019-02-21 18:16   ` Jerome Glisse
2019-02-25  7:48     ` Peter Xu
2019-02-25 18:28   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 18/26] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-02-21 18:17   ` Jerome Glisse
2019-02-25 18:50   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 19/26] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-02-21 18:19   ` Jerome Glisse
2019-02-25 20:48   ` Mike Rapoport
2019-02-12  2:56 ` Peter Xu [this message]
2019-02-21 18:23   ` [PATCH v2 20/26] userfaultfd: wp: support write protection for userfault vma range Jerome Glisse
2019-02-25  8:16     ` Peter Xu
2019-02-25 20:52   ` Mike Rapoport
2019-02-26  6:06     ` Peter Xu
2019-02-26  6:43       ` Mike Rapoport
2019-02-26  7:20         ` Peter Xu
2019-02-26  7:46           ` Mike Rapoport
2019-02-26  7:54             ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 21/26] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-02-21 18:28   ` Jerome Glisse
2019-02-25  8:31     ` Peter Xu
2019-02-25 21:03   ` Mike Rapoport
2019-02-26  6:30     ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 22/26] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-02-21 18:29   ` Jerome Glisse
2019-02-25  8:34     ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 23/26] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-02-21 18:36   ` Jerome Glisse
2019-02-25  8:58     ` Peter Xu
2019-02-25 21:15       ` Mike Rapoport
2019-02-25 21:09   ` Mike Rapoport
2019-02-26  6:24     ` Peter Xu
2019-02-26  7:29       ` Mike Rapoport
2019-02-26  7:41         ` Peter Xu
2019-02-26  8:00           ` Mike Rapoport
2019-02-28  2:47             ` Peter Xu
2019-02-26  8:00   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 24/26] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-02-21 18:38   ` Jerome Glisse
2019-02-25 21:19   ` Mike Rapoport
2019-02-26  6:53     ` Peter Xu
2019-02-26  7:04       ` Mike Rapoport
2019-02-26  7:42         ` Peter Xu
2019-02-12  2:56 ` [PATCH v2 25/26] userfaultfd: selftests: refactor statistics Peter Xu
2019-02-26  6:50   ` Mike Rapoport
2019-02-12  2:56 ` [PATCH v2 26/26] userfaultfd: selftests: add write-protect test Peter Xu
2019-02-26  6:58   ` Mike Rapoport
2019-02-26  7:52     ` Peter Xu

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