/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
* 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>
/*
* If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and
* UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In
* userfaultfd.h we assumed the kernel was reading (instead _IOC_READ
* means the userland is reading).
*/
#define UFFD_API ((__u64)0xAA)
#define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \
UFFD_FEATURE_EVENT_FORK | \
UFFD_FEATURE_EVENT_REMAP | \
UFFD_FEATURE_EVENT_REMOVE | \
UFFD_FEATURE_EVENT_UNMAP | \
UFFD_FEATURE_MISSING_HUGETLBFS | \
UFFD_FEATURE_MISSING_SHMEM | \
UFFD_FEATURE_SIGBUS | \
UFFD_FEATURE_THREAD_ID)
#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 | \
(__u64)1 << _UFFDIO_WRITEPROTECT)
#define UFFD_API_RANGE_IOCTLS_BASIC \
((__u64)1 << _UFFDIO_WAKE | \
(__u64)1 << _UFFDIO_COPY)
/*
* 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_WRITEPROTECT (0x06)
#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)
#define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
struct uffdio_writeprotect)
/* read() structure */
struct uffd_msg {
__u8 event;
__u8 reserved1;
__u16 reserved2;
__u32 reserved3;
union {
struct {
__u64 flags;
__u64 address;
union {
__u32 ptid;
} feat;
} pagefault;
struct {
__u32 ufd;
} fork;
struct {
__u64 from;
__u64 to;
__u64 len;
} remap;
struct {
__u64 start;
__u64 end;
} remove;
struct {
/* unused reserved fields */
__u64 reserved1;
__u64 reserved2;
__u64 reserved3;
} reserved;
} arg;
} __attribute__((packed));
/*
* Start at 0x12 and not at 0 to be more strict against bugs.
*/
#define UFFD_EVENT_PAGEFAULT 0x12
#define UFFD_EVENT_FORK 0x13
#define UFFD_EVENT_REMAP 0x14
#define UFFD_EVENT_REMOVE 0x15
#define UFFD_EVENT_UNMAP 0x16
/* 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.
*
* UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER
* with UFFDIO_REGISTER_MODE_MISSING mode will succeed on
* hugetlbfs virtual memory ranges. Adding or not adding
* UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has
* no real functional effect after UFFDIO_API returns, but
* it's only useful for an initial feature set probe at
* UFFDIO_API time. There are two ways to use it:
*
* 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the
* uffdio_api.features before calling UFFDIO_API, an error
* will be returned by UFFDIO_API on a kernel without
* hugetlbfs missing support
*
* 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in
* uffdio_api.features and instead it will be set by the
* kernel in the uffdio_api.features if the kernel supports
* it, so userland can later check if the feature flag is
* present in uffdio_api.features after UFFDIO_API
* succeeded.
*
* UFFD_FEATURE_MISSING_SHMEM works the same as
* UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
* (i.e. tmpfs and other shmem based APIs).
*
* UFFD_FEATURE_SIGBUS feature means no page-fault
* (UFFD_EVENT_PAGEFAULT) event will be delivered, instead
* a SIGBUS signal will be sent to the faulting process.
*
* UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will
* be returned, if feature is not requested 0 will be returned.
*/
#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
#define UFFD_FEATURE_EVENT_FORK (1<<1)
#define UFFD_FEATURE_EVENT_REMAP (1<<2)
#define UFFD_FEATURE_EVENT_REMOVE (1<<3)
#define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)
#define UFFD_FEATURE_MISSING_SHMEM (1<<5)
#define UFFD_FEATURE_EVENT_UNMAP (1<<6)
#define UFFD_FEATURE_SIGBUS (1<<7)
#define UFFD_FEATURE_THREAD_ID (1<<8)
__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;
#define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0)
/*
* UFFDIO_COPY_MODE_WP will map the page write protected on
* the fly. UFFDIO_COPY_MODE_WP is available only if the
* write protected ioctl is implemented for the range
* according to the uffdio_register.ioctls.
*/
#define UFFDIO_COPY_MODE_WP ((__u64)1<<1)
__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;
};
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;
};
/*
* Flags for the userfaultfd(2) system call itself.
*/
/*
* Create a userfaultfd that can handle page faults only in user mode.
*/
#define UFFD_USER_MODE_ONLY 1
#endif /* _LINUX_USERFAULTFD_H */
