/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */

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/*

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* include/linux/userfaultfd.h

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*

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

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* Copyright (C) 2015 Red Hat, Inc.

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*

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*/

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#ifndef _LINUX_USERFAULTFD_H

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#define _LINUX_USERFAULTFD_H

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#include <linux/types.h>

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/*

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* If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and

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* UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In

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* userfaultfd.h we assumed the kernel was reading (instead _IOC_READ

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* means the userland is reading).

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*/

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#define UFFD_API ((__u64)0xAA)

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#define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \

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UFFD_FEATURE_EVENT_FORK | \

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UFFD_FEATURE_EVENT_REMAP | \

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UFFD_FEATURE_EVENT_REMOVE | \

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UFFD_FEATURE_EVENT_UNMAP | \

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UFFD_FEATURE_MISSING_HUGETLBFS | \

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UFFD_FEATURE_MISSING_SHMEM | \

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UFFD_FEATURE_SIGBUS | \

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UFFD_FEATURE_THREAD_ID)

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#define UFFD_API_IOCTLS \

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((__u64)1 << _UFFDIO_REGISTER | \

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(__u64)1 << _UFFDIO_UNREGISTER | \

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(__u64)1 << _UFFDIO_API)

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#define UFFD_API_RANGE_IOCTLS \

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((__u64)1 << _UFFDIO_WAKE | \

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(__u64)1 << _UFFDIO_COPY | \

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(__u64)1 << _UFFDIO_ZEROPAGE | \

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(__u64)1 << _UFFDIO_WRITEPROTECT)

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#define UFFD_API_RANGE_IOCTLS_BASIC \

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((__u64)1 << _UFFDIO_WAKE | \

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(__u64)1 << _UFFDIO_COPY)

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/*

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

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

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

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

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* which ioctl the running kernel implements through the ioctl command

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* bitmask written by the UFFDIO_API.

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*/

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#define _UFFDIO_REGISTER (0x00)

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#define _UFFDIO_UNREGISTER (0x01)

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#define _UFFDIO_WAKE (0x02)

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#define _UFFDIO_COPY (0x03)

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#define _UFFDIO_ZEROPAGE (0x04)

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#define _UFFDIO_WRITEPROTECT (0x06)

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#define _UFFDIO_API (0x3F)

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/* userfaultfd ioctl ids */

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#define UFFDIO 0xAA

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#define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \

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struct uffdio_api)

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#define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \

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struct uffdio_register)

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#define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \

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struct uffdio_range)

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#define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \

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struct uffdio_range)

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#define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \

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struct uffdio_copy)

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#define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \

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struct uffdio_zeropage)

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#define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \

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struct uffdio_writeprotect)

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/* read() structure */

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struct uffd_msg {

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__u8 event;

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__u8 reserved1;

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__u16 reserved2;

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__u32 reserved3;

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union {

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struct {

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__u64 flags;

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__u64 address;

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union {

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__u32 ptid;

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} feat;

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} pagefault;

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struct {

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__u32 ufd;

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} fork;

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struct {

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__u64 from;

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__u64 to;

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__u64 len;

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} remap;

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struct {

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__u64 start;

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__u64 end;

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} remove;

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struct {

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/* unused reserved fields */

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__u64 reserved1;

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__u64 reserved2;

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__u64 reserved3;

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} reserved;

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} arg;

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} __attribute__((packed));

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/*

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

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*/

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#define UFFD_EVENT_PAGEFAULT 0x12

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#define UFFD_EVENT_FORK 0x13

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#define UFFD_EVENT_REMAP 0x14

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#define UFFD_EVENT_REMOVE 0x15

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#define UFFD_EVENT_UNMAP 0x16

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/* flags for UFFD_EVENT_PAGEFAULT */

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

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

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struct uffdio_api {

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/* userland asks for an API number and the features to enable */

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__u64 api;

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/*

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* Kernel answers below with the all available features for

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* the API, this notifies userland of which events and/or

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* which flags for each event are enabled in the current

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* kernel.

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*

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* Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE

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* are to be considered implicitly always enabled in all kernels as

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* long as the uffdio_api.api requested matches UFFD_API.

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*

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* UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER

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* with UFFDIO_REGISTER_MODE_MISSING mode will succeed on

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* hugetlbfs virtual memory ranges. Adding or not adding

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* UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has

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* no real functional effect after UFFDIO_API returns, but

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* it's only useful for an initial feature set probe at

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* UFFDIO_API time. There are two ways to use it:

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*

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* 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the

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* uffdio_api.features before calling UFFDIO_API, an error

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* will be returned by UFFDIO_API on a kernel without

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* hugetlbfs missing support

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*

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* 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in

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* uffdio_api.features and instead it will be set by the

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* kernel in the uffdio_api.features if the kernel supports

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* it, so userland can later check if the feature flag is

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* present in uffdio_api.features after UFFDIO_API

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* succeeded.

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*

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* UFFD_FEATURE_MISSING_SHMEM works the same as

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* UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem

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* (i.e. tmpfs and other shmem based APIs).

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*

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* UFFD_FEATURE_SIGBUS feature means no page-fault

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* (UFFD_EVENT_PAGEFAULT) event will be delivered, instead

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* a SIGBUS signal will be sent to the faulting process.

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*

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* UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will

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* be returned, if feature is not requested 0 will be returned.

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*/

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#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)

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#define UFFD_FEATURE_EVENT_FORK (1<<1)

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#define UFFD_FEATURE_EVENT_REMAP (1<<2)

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#define UFFD_FEATURE_EVENT_REMOVE (1<<3)

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#define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)

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#define UFFD_FEATURE_MISSING_SHMEM (1<<5)

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#define UFFD_FEATURE_EVENT_UNMAP (1<<6)

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#define UFFD_FEATURE_SIGBUS (1<<7)

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#define UFFD_FEATURE_THREAD_ID (1<<8)

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__u64 features;

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__u64 ioctls;

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};

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struct uffdio_range {

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__u64 start;

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__u64 len;

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};

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struct uffdio_register {

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struct uffdio_range range;

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

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

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__u64 mode;

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/*

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* kernel answers which ioctl commands are available for the

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

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*/

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__u64 ioctls;

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};

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struct uffdio_copy {

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__u64 dst;

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__u64 src;

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__u64 len;

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

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/*

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* UFFDIO_COPY_MODE_WP will map the page write protected on

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* the fly. UFFDIO_COPY_MODE_WP is available only if the

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* write protected ioctl is implemented for the range

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* according to the uffdio_register.ioctls.

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*/

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#define UFFDIO_COPY_MODE_WP ((__u64)1<<1)

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__u64 mode;

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/*

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* "copy" is written by the ioctl and must be at the end: the

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* copy_from_user will not read the last 8 bytes.

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*/

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__s64 copy;

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};

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struct uffdio_zeropage {

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struct uffdio_range range;

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

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__u64 mode;

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/*

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* "zeropage" is written by the ioctl and must be at the end:

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* the copy_from_user will not read the last 8 bytes.

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*/

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__s64 zeropage;

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};

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struct uffdio_writeprotect {

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struct uffdio_range range;

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/*

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* UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range,

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* unset the flag to undo protection of a range which was previously

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* write protected.

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*

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* UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up

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* any wait thread after the operation succeeds.

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*

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* NOTE: Write protecting a region (WP=1) is unrelated to page faults,

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* therefore DONTWAKE flag is meaningless with WP=1. Removing write

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* protection (WP=0) in response to a page fault wakes the faulting

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* task unless DONTWAKE is set.

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*/

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

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#define UFFDIO_WRITEPROTECT_MODE_DONTWAKE ((__u64)1<<1)

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__u64 mode;

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};

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#endif /* _LINUX_USERFAULTFD_H */

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