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userfaultfd.h
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/* 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; }; #endif /* _LINUX_USERFAULTFD_H */