Release 4.7 include/uapi/linux/userfaultfd.h

/*
 *  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)
/*
 * After implementing the respective features it will become:
 * #define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \
 *                            UFFD_FEATURE_EVENT_FORK)
 */

#define UFFD_API_FEATURES (0)

#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 |             \
         (__u64)1 << _UFFDIO_COPY |             \
         (__u64)1 << _UFFDIO_ZEROPAGE)

/*
 * 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_COPY			(0x03)

#define _UFFDIO_ZEROPAGE		(0x04)

#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)

#define UFFDIO_COPY		_IOWR(UFFDIO, _UFFDIO_COPY,     \
                                      struct uffdio_copy)

#define UFFDIO_ZEROPAGE		_IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
                                      struct uffdio_zeropage)

/* read() structure */

struct uffd_msg {
	
__u8	event;

	
__u8	reserved1;
	
__u16	reserved2;
	
__u32	reserved3;

	union {
		struct {
			
__u64	flags;
			
__u64	address;
		} 
pagefault;

		struct {
			/* unused reserved fields */
			
__u64	reserved1;
			
__u64	reserved2;
			
__u64	reserved3;
		} 
reserved;
	} 
arg;
} 
__packed;

/*
 * Start at 0x12 and not at 0 to be more strict against bugs.
 */

#define UFFD_EVENT_PAGEFAULT	0x12
#if 0 /* not available yet */
#define UFFD_EVENT_FORK		0x13
#endif

/* flags for UFFD_EVENT_PAGEFAULT */

#define UFFD_PAGEFAULT_FLAG_WRITE	(1<<0)	
/* If this was a write fault */

#define UFFD_PAGEFAULT_FLAG_WP		(1<<1)	
/* If reason is VM_UFFD_WP */


struct uffdio_api {
	/* userland asks for an API number and the features to enable */
	
__u64 api;
	/*
         * Kernel answers below with the all available features for
         * the API, this notifies userland of which events and/or
         * which flags for each event are enabled in the current
         * kernel.
         *
         * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
         * are to be considered implicitly always enabled in all kernels as
         * long as the uffdio_api.api requested matches UFFD_API.
         */
#if 0 /* not available yet */
#define UFFD_FEATURE_PAGEFAULT_FLAG_WP		(1<<0)
#define UFFD_FEATURE_EVENT_FORK			(1<<1)
#endif
	
__u64 features;

	
__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;
};


struct uffdio_copy {
	
__u64 dst;
	
__u64 src;
	
__u64 len;
	/*
         * There will be a wrprotection flag later that allows to map
         * pages wrprotected on the fly. And such a flag will be
         * available if the wrprotection ioctl are implemented for the
         * range according to the uffdio_register.ioctls.
         */

#define UFFDIO_COPY_MODE_DONTWAKE		((__u64)1<<0)
	
__u64 mode;

	/*
         * "copy" is written by the ioctl and must be at the end: the
         * copy_from_user will not read the last 8 bytes.
         */
	
__s64 copy;
};


struct uffdio_zeropage {
	
struct uffdio_range range;

#define UFFDIO_ZEROPAGE_MODE_DONTWAKE		((__u64)1<<0)
	
__u64 mode;

	/*
         * "zeropage" is written by the ioctl and must be at the end:
         * the copy_from_user will not read the last 8 bytes.
         */
	
__s64 zeropage;
};

#endif /* _LINUX_USERFAULTFD_H */
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