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Commit 1038628d authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

userfaultfd: uAPI 



Defines the uAPI of the userfaultfd, notably the ioctl numbers and protocol.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarPavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 51360155

Documentation/ioctl/ioctl-number.txt

+1 −0
Original line number Diff line number Diff line
@@ -303,6 +303,7 @@ Code Seq#(hex) Include File Comments 
0xA3	80-8F	Port ACL		in development:

					<mailto:tlewis@mindspring.com>

0xA3	90-9F	linux/dtlk.h

0xAA	00-3F	linux/uapi/linux/userfaultfd.h

0xAB	00-1F	linux/nbd.h

0xAC	00-1F	linux/raw.h

0xAD	00	Netfilter device	in development:

include/uapi/linux/Kbuild

+1 −0
Original line number Diff line number Diff line
@@ -456,3 +456,4 @@ header-y += xfrm.h 
header-y += xilinx-v4l2-controls.h

header-y += zorro.h

header-y += zorro_ids.h

header-y += userfaultfd.h

include/uapi/linux/userfaultfd.h

0 → 100644
+83 −0
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/*

 *  include/linux/userfaultfd.h

 *

 *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>

 *  Copyright (C) 2015  Red Hat, Inc.

 *

 */



#ifndef _LINUX_USERFAULTFD_H

#define _LINUX_USERFAULTFD_H



#include <linux/types.h>



#define UFFD_API ((__u64)0xAA)

/* FIXME: add "|UFFD_BIT_WP" to UFFD_API_BITS after implementing it */

#define UFFD_API_BITS (UFFD_BIT_WRITE)

#define UFFD_API_IOCTLS				\

	((__u64)1 << _UFFDIO_REGISTER |		\

	 (__u64)1 << _UFFDIO_UNREGISTER |	\

	 (__u64)1 << _UFFDIO_API)

#define UFFD_API_RANGE_IOCTLS			\

	((__u64)1 << _UFFDIO_WAKE)



/*

 * Valid ioctl command number range with this API is from 0x00 to

 * 0x3F.  UFFDIO_API is the fixed number, everything else can be

 * changed by implementing a different UFFD_API. If sticking to the

 * same UFFD_API more ioctl can be added and userland will be aware of

 * which ioctl the running kernel implements through the ioctl command

 * bitmask written by the UFFDIO_API.

 */

#define _UFFDIO_REGISTER		(0x00)

#define _UFFDIO_UNREGISTER		(0x01)

#define _UFFDIO_WAKE			(0x02)

#define _UFFDIO_API			(0x3F)



/* userfaultfd ioctl ids */

#define UFFDIO 0xAA

#define UFFDIO_API		_IOWR(UFFDIO, _UFFDIO_API,	\

				      struct uffdio_api)

#define UFFDIO_REGISTER		_IOWR(UFFDIO, _UFFDIO_REGISTER, \

				      struct uffdio_register)

#define UFFDIO_UNREGISTER	_IOR(UFFDIO, _UFFDIO_UNREGISTER,	\

				     struct uffdio_range)

#define UFFDIO_WAKE		_IOR(UFFDIO, _UFFDIO_WAKE,	\

				     struct uffdio_range)



/*

 * Valid bits below PAGE_SHIFT in the userfault address read through

 * the read() syscall.

 */

#define UFFD_BIT_WRITE	(1<<0)	/* this was a write fault, MISSING or WP */

#define UFFD_BIT_WP	(1<<1)	/* handle_userfault() reason VM_UFFD_WP */

#define UFFD_BITS	2	/* two above bits used for UFFD_BIT_* mask */



struct uffdio_api {

	/* userland asks for an API number */

	__u64 api;



	/* kernel answers below with the available features for the API */

	__u64 bits;

	__u64 ioctls;

};



struct uffdio_range {

	__u64 start;

	__u64 len;

};



struct uffdio_register {

	struct uffdio_range range;

#define UFFDIO_REGISTER_MODE_MISSING	((__u64)1<<0)

#define UFFDIO_REGISTER_MODE_WP		((__u64)1<<1)

	__u64 mode;



	/*

	 * kernel answers which ioctl commands are available for the

	 * range, keep at the end as the last 8 bytes aren't read.

	 */

	__u64 ioctls;

};



#endif /* _LINUX_USERFAULTFD_H */