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From: Peter Xu <peterx@redhat.com>
Subject: [PATCH RFC 11/24] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers
Date: Mon, 21 Jan 2019 15:57:09 +0800
Message-Id: <20190121075722.7945-12-peterx@redhat.com>
In-Reply-To: <20190121075722.7945-1-peterx@redhat.com>
References: <20190121075722.7945-1-peterx@redhat.com>
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To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>, Jerome Glisse <jglisse@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, peterx@redhat.com, Martin Cracauer <cracauer@cons.org>, Denis Plotnikov <dplotnikov@virtuozzo.com>, Shaohua Li <shli@fb.com>, Andrea Arcangeli <aarcange@redhat.com>, Pavel Emelyanov <xemul@parallels.com>, Mike Kravetz <mike.kravetz@oracle.com>, Marty McFadden <mcfadden8@llnl.gov>, 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>

From: Andrea Arcangeli <aarcange@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@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.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 e82f3156f4e9..0d3b32b54e2a 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
@@ -57,6 +59,18 @@ 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);
@@ -106,6 +120,19 @@ 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;
-- 
2.17.1