userfaultfd.h
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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)
/*
* 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 */