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>, Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Marty McFadden <mcfadden8@llnl.gov>, Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v3 12/28] userfaultfd: wp: apply _PAGE_UFFD_WP bit
Date: Wed, 20 Mar 2019 10:06:26 +0800 [thread overview]
Message-ID: <20190320020642.4000-13-peterx@redhat.com> (raw)
In-Reply-To: <20190320020642.4000-1-peterx@redhat.com>
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 <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
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
next prev parent reply other threads:[~2019-03-20 2:08 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 2:06 [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-03-20 2:06 ` [PATCH v3 01/28] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-03-20 2:06 ` [PATCH v3 02/28] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-03-20 2:06 ` [PATCH v3 03/28] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-03-20 2:06 ` [PATCH v3 04/28] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-04-18 20:11 ` Jerome Glisse
2019-04-19 6:00 ` Peter Xu
2019-03-20 2:06 ` [PATCH v3 05/28] mm: gup: " Peter Xu
2019-03-20 2:06 ` [PATCH v3 06/28] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-03-20 2:06 ` [PATCH v3 07/28] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-04-18 20:03 ` Jerome Glisse
2019-03-20 2:06 ` [PATCH v3 08/28] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-03-20 2:06 ` [PATCH v3 09/28] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-03-20 2:06 ` [PATCH v3 10/28] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-03-20 2:06 ` [PATCH v3 11/28] mm: merge parameters for change_protection() Peter Xu
2019-03-20 2:06 ` Peter Xu [this message]
2019-03-20 2:06 ` [PATCH v3 13/28] mm: export wp_page_copy() Peter Xu
2019-03-20 2:06 ` [PATCH v3 14/28] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-04-18 20:51 ` Jerome Glisse
2019-04-19 6:26 ` Peter Xu
2019-04-19 15:02 ` Jerome Glisse
2019-04-22 12:20 ` Peter Xu
2019-04-22 14:54 ` Jerome Glisse
2019-04-23 3:00 ` Peter Xu
2019-04-23 15:34 ` Jerome Glisse
2019-04-24 8:38 ` Peter Xu
2019-03-20 2:06 ` [PATCH v3 15/28] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-03-20 2:06 ` [PATCH v3 16/28] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-03-20 2:06 ` [PATCH v3 17/28] userfaultfd: wp: support swap and page migration Peter Xu
2019-04-18 20:59 ` Jerome Glisse
2019-04-19 7:42 ` Peter Xu
2019-04-19 15:08 ` Jerome Glisse
2019-04-22 12:23 ` Peter Xu
2019-03-20 2:06 ` [PATCH v3 18/28] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-03-20 2:06 ` [PATCH v3 19/28] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-03-20 2:06 ` [PATCH v3 20/28] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-03-20 2:06 ` [PATCH v3 21/28] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-03-20 2:06 ` [PATCH v3 22/28] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-03-22 21:37 ` Mike Rapoport
2019-03-20 2:06 ` [PATCH v3 23/28] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-03-20 2:06 ` [PATCH v3 24/28] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-03-22 21:46 ` Mike Rapoport
2019-03-20 2:06 ` [PATCH v3 25/28] userfaultfd: wp: fixup swap entries in change_pte_range Peter Xu
2019-04-18 21:01 ` Jerome Glisse
2019-03-20 2:06 ` [PATCH v3 26/28] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally Peter Xu
2019-03-22 21:43 ` Mike Rapoport
2019-03-20 2:06 ` [PATCH v3 27/28] userfaultfd: selftests: refactor statistics Peter Xu
2019-03-20 2:06 ` [PATCH v3 28/28] userfaultfd: selftests: add write-protect test Peter Xu
2019-04-09 6:08 ` [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-04-18 21:07 ` Jerome Glisse
2019-04-19 7:53 ` Peter Xu
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