[Devel] [PATCH vz8 25/42] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers

[Andrey Ryabinin]

From: Andrea Arcangeli <aarcange at redhat.com>

Implement helpers methods to invoke userfaultfd wp faults more
selectively: not only when a wp fault triggers on a vma with vma->vm_flags
VM_UFFD_WP set, but only if the _PAGE_UFFD_WP bit is set in the pagetable
too.

Signed-off-by: Andrea Arcangeli <aarcange at redhat.com>
Signed-off-by: Peter Xu <peterx at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Reviewed-by: Jerome Glisse <jglisse at redhat.com>
Reviewed-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
Cc: Bobby Powers <bobbypowers at gmail.com>
Cc: Brian Geffon <bgeffon at google.com>
Cc: David Hildenbrand <david at redhat.com>
Cc: Denis Plotnikov <dplotnikov at virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert at redhat.com>
Cc: Hugh Dickins <hughd at google.com>
Cc: Johannes Weiner <hannes at cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill at shutemov.name>
Cc: Martin Cracauer <cracauer at cons.org>
Cc: Marty McFadden <mcfadden8 at llnl.gov>
Cc: Maya Gokhale <gokhale2 at llnl.gov>
Cc: Mel Gorman <mgorman at suse.de>
Cc: Mike Kravetz <mike.kravetz at oracle.com>
Cc: Pavel Emelyanov <xemul at openvz.org>
Cc: Rik van Riel <riel at redhat.com>
Cc: Shaohua Li <shli at fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-5-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

https://jira.sw.ru/browse/PSBM-102938
(cherry picked from commit 55adf4de30346e0ec6b988cb9b885a5dddc954af)
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 include/linux/userfaultfd_k.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 52dcb3beaa5e..8fc07c5af632 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -14,6 +14,8 @@
 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
 
 #include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <asm-generic/pgtable_uffd.h>
 
 /*
  * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
@@ -55,6 +57,18 @@ static inline bool userfaultfd_wp(struct vm_area_struct *vma)
 	return vma->vm_flags & VM_UFFD_WP;
 }
 
+static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
+				      pte_t pte)
+{
+	return userfaultfd_wp(vma) && pte_uffd_wp(pte);
+}
+
+static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
+					   pmd_t pmd)
+{
+	return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
+}
+
 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
@@ -103,6 +117,19 @@ static inline bool userfaultfd_wp(struct vm_area_struct *vma)
 	return false;
 }
 
+static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
+				      pte_t pte)
+{
+	return false;
+}
+
+static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
+					   pmd_t pmd)
+{
+	return false;
+}
+
+
 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
 {
 	return false;
-- 
2.25.3