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authorAndrea Arcangeli <aarcange@redhat.com>2020-04-06 20:06:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:39 -0700
commit63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 (patch)
treef47e83aacce2857bbd27b884f8e1bdd7caca3a95 /include
parentffd05793963a44bd119311df3c02b191982574ee (diff)
userfaultfd: wp: add the writeprotect API to userfaultfd ioctl
Introduce the new uffd-wp APIs for userspace. Firstly, we'll allow to do UFFDIO_REGISTER with write protection tracking using the new UFFDIO_REGISTER_MODE_WP flag. Note that this flag can co-exist with the existing UFFDIO_REGISTER_MODE_MISSING, in which case the userspace program can not only resolve missing page faults, and at the same time tracking page data changes along the way. Secondly, we introduced the new UFFDIO_WRITEPROTECT API to do page level write protection tracking. Note that we will need to register the memory region with UFFDIO_REGISTER_MODE_WP before that. [peterx@redhat.com: write up the commit message] [peterx@redhat.com: remove useless block, write commit message, check against VM_MAYWRITE rather than VM_WRITE when register] 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> 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: Mike Rapoport <rppt@linux.vnet.ibm.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/20200220163112.11409-14-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/uapi/linux/userfaultfd.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 340f23bc251d..95c4a160e5f8 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -52,6 +52,7 @@
#define _UFFDIO_WAKE (0x02)
#define _UFFDIO_COPY (0x03)
#define _UFFDIO_ZEROPAGE (0x04)
+#define _UFFDIO_WRITEPROTECT (0x06)
#define _UFFDIO_API (0x3F)
/* userfaultfd ioctl ids */
@@ -68,6 +69,8 @@
struct uffdio_copy)
#define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
struct uffdio_zeropage)
+#define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
+ struct uffdio_writeprotect)
/* read() structure */
struct uffd_msg {
@@ -232,4 +235,24 @@ struct uffdio_zeropage {
__s64 zeropage;
};
+struct uffdio_writeprotect {
+ struct uffdio_range range;
+/*
+ * UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range,
+ * unset the flag to undo protection of a range which was previously
+ * write protected.
+ *
+ * UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up
+ * any wait thread after the operation succeeds.
+ *
+ * NOTE: Write protecting a region (WP=1) is unrelated to page faults,
+ * therefore DONTWAKE flag is meaningless with WP=1. Removing write
+ * protection (WP=0) in response to a page fault wakes the faulting
+ * task unless DONTWAKE is set.
+ */
+#define UFFDIO_WRITEPROTECT_MODE_WP ((__u64)1<<0)
+#define UFFDIO_WRITEPROTECT_MODE_DONTWAKE ((__u64)1<<1)
+ __u64 mode;
+};
+
#endif /* _LINUX_USERFAULTFD_H */