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authorAndrea Arcangeli <aarcange@redhat.com>2020-04-07 06:05:33 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 20:43:39 +0300
commit5a281062af1d43d3f3956a6b429c2d727bc92603 (patch)
tree8c4c2c81d3e0c66fa7208dd9e1862a2a74df1945 /include/asm-generic
parent529b930b87d997c3d231c9d8638a0bf8db569d70 (diff)
downloadlinux-5a281062af1d43d3f3956a6b429c2d727bc92603.tar.xz
userfaultfd: wp: add WP pagetable tracking to x86
Accurate userfaultfd WP tracking is possible by tracking exactly which virtual memory ranges were writeprotected by userland. We can't relay only on the RW bit of the mapped pagetable because that information is destroyed by fork() or KSM or swap. If we were to relay on that, we'd need to stay on the safe side and generate false positive wp faults for every swapped out page. [peterx@redhat.com: append _PAGE_UFD_WP to _PAGE_CHG_MASK] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Brian Geffon <bgeffon@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@fb.com> Link: http://lkml.kernel.org/r/20200220163112.11409-4-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/pgtable.h1
-rw-r--r--include/asm-generic/pgtable_uffd.h51
2 files changed, 52 insertions, 0 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index e2e2bef07dd2..329b8c8ca703 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -10,6 +10,7 @@
#include <linux/mm_types.h>
#include <linux/bug.h>
#include <linux/errno.h>
+#include <asm-generic/pgtable_uffd.h>
#if 5 - defined(__PAGETABLE_P4D_FOLDED) - defined(__PAGETABLE_PUD_FOLDED) - \
defined(__PAGETABLE_PMD_FOLDED) != CONFIG_PGTABLE_LEVELS
diff --git a/include/asm-generic/pgtable_uffd.h b/include/asm-generic/pgtable_uffd.h
new file mode 100644
index 000000000000..643d1bf559c2
--- /dev/null
+++ b/include/asm-generic/pgtable_uffd.h
@@ -0,0 +1,51 @@
+#ifndef _ASM_GENERIC_PGTABLE_UFFD_H
+#define _ASM_GENERIC_PGTABLE_UFFD_H
+
+#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP
+static __always_inline int pte_uffd_wp(pte_t pte)
+{
+ return 0;
+}
+
+static __always_inline int pmd_uffd_wp(pmd_t pmd)
+{
+ return 0;
+}
+
+static __always_inline pte_t pte_mkuffd_wp(pte_t pte)
+{
+ return pte;
+}
+
+static __always_inline pmd_t pmd_mkuffd_wp(pmd_t pmd)
+{
+ return pmd;
+}
+
+static __always_inline pte_t pte_clear_uffd_wp(pte_t pte)
+{
+ return pte;
+}
+
+static __always_inline pmd_t pmd_clear_uffd_wp(pmd_t pmd)
+{
+ return pmd;
+}
+
+static __always_inline pte_t pte_swp_mkuffd_wp(pte_t pte)
+{
+ return pte;
+}
+
+static __always_inline int pte_swp_uffd_wp(pte_t pte)
+{
+ return 0;
+}
+
+static __always_inline pte_t pte_swp_clear_uffd_wp(pte_t pte)
+{
+ return pte;
+}
+#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */
+
+#endif /* _ASM_GENERIC_PGTABLE_UFFD_H */