315 lines
9.4 KiB
C
315 lines
9.4 KiB
C
/* 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_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING | \
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UFFDIO_REGISTER_MODE_WP | \
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UFFDIO_REGISTER_MODE_MINOR)
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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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UFFD_FEATURE_MINOR_HUGETLBFS | \
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UFFD_FEATURE_MINOR_SHMEM | \
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UFFD_FEATURE_EXACT_ADDRESS | \
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UFFD_FEATURE_WP_HUGETLBFS_SHMEM)
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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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(__u64)1 << _UFFDIO_CONTINUE)
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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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(__u64)1 << _UFFDIO_CONTINUE | \
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(__u64)1 << _UFFDIO_WRITEPROTECT)
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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_CONTINUE (0x07)
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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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#define UFFDIO_CONTINUE _IOWR(UFFDIO, _UFFDIO_CONTINUE, \
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struct uffdio_continue)
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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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} __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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#define UFFD_PAGEFAULT_FLAG_MINOR (1<<2) /* If reason is VM_UFFD_MINOR */
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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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* UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults
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* can be intercepted (via REGISTER_MODE_MINOR) for
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* hugetlbfs-backed pages.
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*
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* UFFD_FEATURE_MINOR_SHMEM indicates the same support as
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* UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead.
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*
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* UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page
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* faults would be provided and the offset within the page would not be
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* masked.
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*
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* UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd
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* write-protection mode is supported on both shmem and hugetlbfs.
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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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#define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9)
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#define UFFD_FEATURE_MINOR_SHMEM (1<<10)
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#define UFFD_FEATURE_EXACT_ADDRESS (1<<11)
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#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<12)
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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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#define UFFDIO_REGISTER_MODE_MINOR ((__u64)1<<2)
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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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struct uffdio_continue {
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struct uffdio_range range;
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#define UFFDIO_CONTINUE_MODE_DONTWAKE ((__u64)1<<0)
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__u64 mode;
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/*
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* Fields below here are written by the ioctl and must be at the end:
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* the copy_from_user will not read past here.
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*/
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__s64 mapped;
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};
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/*
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* Flags for the userfaultfd(2) system call itself.
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*/
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/*
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* Create a userfaultfd that can handle page faults only in user mode.
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*/
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#define UFFD_USER_MODE_ONLY 1
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#endif /* _LINUX_USERFAULTFD_H */
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