zig

userfaultfd.h (12016B) - Raw

---

 /* 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>
 
 /* ioctls for /dev/userfaultfd */
 #define USERFAULTFD_IOC 0xAA
 #define USERFAULTFD_IOC_NEW _IO(USERFAULTFD_IOC, 0x00)
 
 /*
  * 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_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING |	\
 				 UFFDIO_REGISTER_MODE_WP |	\
 				 UFFDIO_REGISTER_MODE_MINOR)
 #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 |		\
 			   UFFD_FEATURE_MINOR_HUGETLBFS |	\
 			   UFFD_FEATURE_MINOR_SHMEM |		\
 			   UFFD_FEATURE_EXACT_ADDRESS |		\
 			   UFFD_FEATURE_WP_HUGETLBFS_SHMEM |	\
 			   UFFD_FEATURE_WP_UNPOPULATED |	\
 			   UFFD_FEATURE_POISON |		\
 			   UFFD_FEATURE_WP_ASYNC |		\
 			   UFFD_FEATURE_MOVE)
 #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_MOVE |		\
 	 (__u64)1 << _UFFDIO_WRITEPROTECT |	\
 	 (__u64)1 << _UFFDIO_CONTINUE |		\
 	 (__u64)1 << _UFFDIO_POISON)
 #define UFFD_API_RANGE_IOCTLS_BASIC		\
 	((__u64)1 << _UFFDIO_WAKE |		\
 	 (__u64)1 << _UFFDIO_COPY |		\
 	 (__u64)1 << _UFFDIO_WRITEPROTECT |	\
 	 (__u64)1 << _UFFDIO_CONTINUE |		\
 	 (__u64)1 << _UFFDIO_POISON)
 
 /*
  * 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_MOVE			(0x05)
 #define _UFFDIO_WRITEPROTECT		(0x06)
 #define _UFFDIO_CONTINUE		(0x07)
 #define _UFFDIO_POISON			(0x08)
 #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_MOVE		_IOWR(UFFDIO, _UFFDIO_MOVE,	\
 				      struct uffdio_move)
 #define UFFDIO_WRITEPROTECT	_IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
 				      struct uffdio_writeprotect)
 #define UFFDIO_CONTINUE		_IOWR(UFFDIO, _UFFDIO_CONTINUE,	\
 				      struct uffdio_continue)
 #define UFFDIO_POISON		_IOWR(UFFDIO, _UFFDIO_POISON, \
 				      struct uffdio_poison)
 
 /* 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 */
 #define UFFD_PAGEFAULT_FLAG_MINOR	(1<<2)	/* If reason is VM_UFFD_MINOR */
 
 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.
 	 *
 	 * UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults
 	 * can be intercepted (via REGISTER_MODE_MINOR) for
 	 * hugetlbfs-backed pages.
 	 *
 	 * UFFD_FEATURE_MINOR_SHMEM indicates the same support as
 	 * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead.
 	 *
 	 * UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page
 	 * faults would be provided and the offset within the page would not be
 	 * masked.
 	 *
 	 * UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd
 	 * write-protection mode is supported on both shmem and hugetlbfs.
 	 *
 	 * UFFD_FEATURE_WP_UNPOPULATED indicates that userfaultfd
 	 * write-protection mode will always apply to unpopulated pages
 	 * (i.e. empty ptes).  This will be the default behavior for shmem
 	 * & hugetlbfs, so this flag only affects anonymous memory behavior
 	 * when userfault write-protection mode is registered.
 	 *
 	 * UFFD_FEATURE_WP_ASYNC indicates that userfaultfd write-protection
 	 * asynchronous mode is supported in which the write fault is
 	 * automatically resolved and write-protection is un-set.
 	 * It implies UFFD_FEATURE_WP_UNPOPULATED.
 	 *
 	 * UFFD_FEATURE_MOVE indicates that the kernel supports moving an
 	 * existing page contents from userspace.
 	 */
 #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)
 #define UFFD_FEATURE_MINOR_HUGETLBFS		(1<<9)
 #define UFFD_FEATURE_MINOR_SHMEM		(1<<10)
 #define UFFD_FEATURE_EXACT_ADDRESS		(1<<11)
 #define UFFD_FEATURE_WP_HUGETLBFS_SHMEM		(1<<12)
 #define UFFD_FEATURE_WP_UNPOPULATED		(1<<13)
 #define UFFD_FEATURE_POISON			(1<<14)
 #define UFFD_FEATURE_WP_ASYNC			(1<<15)
 #define UFFD_FEATURE_MOVE			(1<<16)
 	__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)
 #define UFFDIO_REGISTER_MODE_MINOR	((__u64)1<<2)
 	__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;
 };
 
 struct uffdio_continue {
 	struct uffdio_range range;
 #define UFFDIO_CONTINUE_MODE_DONTWAKE		((__u64)1<<0)
 	/*
 	 * UFFDIO_CONTINUE_MODE_WP will map the page write protected on
 	 * the fly.  UFFDIO_CONTINUE_MODE_WP is available only if the
 	 * write protected ioctl is implemented for the range
 	 * according to the uffdio_register.ioctls.
 	 */
 #define UFFDIO_CONTINUE_MODE_WP			((__u64)1<<1)
 	__u64 mode;
 
 	/*
 	 * Fields below here are written by the ioctl and must be at the end:
 	 * the copy_from_user will not read past here.
 	 */
 	__s64 mapped;
 };
 
 struct uffdio_poison {
 	struct uffdio_range range;
 #define UFFDIO_POISON_MODE_DONTWAKE		((__u64)1<<0)
 	__u64 mode;
 
 	/*
 	 * Fields below here are written by the ioctl and must be at the end:
 	 * the copy_from_user will not read past here.
 	 */
 	__s64 updated;
 };
 
 struct uffdio_move {
 	__u64 dst;
 	__u64 src;
 	__u64 len;
 	/*
 	 * Especially if used to atomically remove memory from the
 	 * address space the wake on the dst range is not needed.
 	 */
 #define UFFDIO_MOVE_MODE_DONTWAKE		((__u64)1<<0)
 #define UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES	((__u64)1<<1)
 	__u64 mode;
 	/*
 	 * "move" is written by the ioctl and must be at the end: the
 	 * copy_from_user will not read the last 8 bytes.
 	 */
 	__s64 move;
 };
 
 /*
  * 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 */