Thomas Gleixner | 20c8ccb | 2019-06-04 10:11:32 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 2 | /* |
| 3 | * fs/userfaultfd.c |
| 4 | * |
| 5 | * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org> |
| 6 | * Copyright (C) 2008-2009 Red Hat, Inc. |
| 7 | * Copyright (C) 2015 Red Hat, Inc. |
| 8 | * |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 9 | * Some part derived from fs/eventfd.c (anon inode setup) and |
| 10 | * mm/ksm.c (mm hashing). |
| 11 | */ |
| 12 | |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 13 | #include <linux/list.h> |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 14 | #include <linux/hashtable.h> |
Ingo Molnar | 174cd4b | 2017-02-02 19:15:33 +0100 | [diff] [blame] | 15 | #include <linux/sched/signal.h> |
Ingo Molnar | 6e84f31 | 2017-02-08 18:51:29 +0100 | [diff] [blame] | 16 | #include <linux/sched/mm.h> |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 17 | #include <linux/mm.h> |
| 18 | #include <linux/poll.h> |
| 19 | #include <linux/slab.h> |
| 20 | #include <linux/seq_file.h> |
| 21 | #include <linux/file.h> |
| 22 | #include <linux/bug.h> |
| 23 | #include <linux/anon_inodes.h> |
| 24 | #include <linux/syscalls.h> |
| 25 | #include <linux/userfaultfd_k.h> |
| 26 | #include <linux/mempolicy.h> |
| 27 | #include <linux/ioctl.h> |
| 28 | #include <linux/security.h> |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 29 | #include <linux/hugetlb.h> |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 30 | |
Peter Xu | cefdca0 | 2019-05-13 17:16:41 -0700 | [diff] [blame] | 31 | int sysctl_unprivileged_userfaultfd __read_mostly = 1; |
| 32 | |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 33 | static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly; |
| 34 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 35 | enum userfaultfd_state { |
| 36 | UFFD_STATE_WAIT_API, |
| 37 | UFFD_STATE_RUNNING, |
| 38 | }; |
| 39 | |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 40 | /* |
| 41 | * Start with fault_pending_wqh and fault_wqh so they're more likely |
| 42 | * to be in the same cacheline. |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 43 | * |
| 44 | * Locking order: |
| 45 | * fd_wqh.lock |
| 46 | * fault_pending_wqh.lock |
| 47 | * fault_wqh.lock |
| 48 | * event_wqh.lock |
| 49 | * |
| 50 | * To avoid deadlocks, IRQs must be disabled when taking any of the above locks, |
| 51 | * since fd_wqh.lock is taken by aio_poll() while it's holding a lock that's |
| 52 | * also taken in IRQ context. |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 53 | */ |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 54 | struct userfaultfd_ctx { |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 55 | /* waitqueue head for the pending (i.e. not read) userfaults */ |
| 56 | wait_queue_head_t fault_pending_wqh; |
| 57 | /* waitqueue head for the userfaults */ |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 58 | wait_queue_head_t fault_wqh; |
| 59 | /* waitqueue head for the pseudo fd to wakeup poll/read */ |
| 60 | wait_queue_head_t fd_wqh; |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 61 | /* waitqueue head for events */ |
| 62 | wait_queue_head_t event_wqh; |
Andrea Arcangeli | 2c5b7e1 | 2015-09-04 15:47:23 -0700 | [diff] [blame] | 63 | /* a refile sequence protected by fault_pending_wqh lock */ |
| 64 | struct seqcount refile_seq; |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 65 | /* pseudo fd refcounting */ |
Eric Biggers | ca88042 | 2018-12-28 00:34:43 -0800 | [diff] [blame] | 66 | refcount_t refcount; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 67 | /* userfaultfd syscall flags */ |
| 68 | unsigned int flags; |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 69 | /* features requested from the userspace */ |
| 70 | unsigned int features; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 71 | /* state machine */ |
| 72 | enum userfaultfd_state state; |
| 73 | /* released */ |
| 74 | bool released; |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 75 | /* memory mappings are changing because of non-cooperative event */ |
| 76 | bool mmap_changing; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 77 | /* mm with one ore more vmas attached to this userfaultfd_ctx */ |
| 78 | struct mm_struct *mm; |
| 79 | }; |
| 80 | |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 81 | struct userfaultfd_fork_ctx { |
| 82 | struct userfaultfd_ctx *orig; |
| 83 | struct userfaultfd_ctx *new; |
| 84 | struct list_head list; |
| 85 | }; |
| 86 | |
Mike Rapoport | 897ab3e | 2017-02-24 14:58:22 -0800 | [diff] [blame] | 87 | struct userfaultfd_unmap_ctx { |
| 88 | struct userfaultfd_ctx *ctx; |
| 89 | unsigned long start; |
| 90 | unsigned long end; |
| 91 | struct list_head list; |
| 92 | }; |
| 93 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 94 | struct userfaultfd_wait_queue { |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 95 | struct uffd_msg msg; |
Ingo Molnar | ac6424b | 2017-06-20 12:06:13 +0200 | [diff] [blame] | 96 | wait_queue_entry_t wq; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 97 | struct userfaultfd_ctx *ctx; |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 98 | bool waken; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 99 | }; |
| 100 | |
| 101 | struct userfaultfd_wake_range { |
| 102 | unsigned long start; |
| 103 | unsigned long len; |
| 104 | }; |
| 105 | |
Ingo Molnar | ac6424b | 2017-06-20 12:06:13 +0200 | [diff] [blame] | 106 | static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode, |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 107 | int wake_flags, void *key) |
| 108 | { |
| 109 | struct userfaultfd_wake_range *range = key; |
| 110 | int ret; |
| 111 | struct userfaultfd_wait_queue *uwq; |
| 112 | unsigned long start, len; |
| 113 | |
| 114 | uwq = container_of(wq, struct userfaultfd_wait_queue, wq); |
| 115 | ret = 0; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 116 | /* len == 0 means wake all */ |
| 117 | start = range->start; |
| 118 | len = range->len; |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 119 | if (len && (start > uwq->msg.arg.pagefault.address || |
| 120 | start + len <= uwq->msg.arg.pagefault.address)) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 121 | goto out; |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 122 | WRITE_ONCE(uwq->waken, true); |
| 123 | /* |
Peter Zijlstra | a9668cd | 2017-06-07 17:51:27 +0200 | [diff] [blame] | 124 | * The Program-Order guarantees provided by the scheduler |
| 125 | * ensure uwq->waken is visible before the task is woken. |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 126 | */ |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 127 | ret = wake_up_state(wq->private, mode); |
Peter Zijlstra | a9668cd | 2017-06-07 17:51:27 +0200 | [diff] [blame] | 128 | if (ret) { |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 129 | /* |
| 130 | * Wake only once, autoremove behavior. |
| 131 | * |
Peter Zijlstra | a9668cd | 2017-06-07 17:51:27 +0200 | [diff] [blame] | 132 | * After the effect of list_del_init is visible to the other |
| 133 | * CPUs, the waitqueue may disappear from under us, see the |
| 134 | * !list_empty_careful() in handle_userfault(). |
| 135 | * |
| 136 | * try_to_wake_up() has an implicit smp_mb(), and the |
| 137 | * wq->private is read before calling the extern function |
| 138 | * "wake_up_state" (which in turns calls try_to_wake_up). |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 139 | */ |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 140 | list_del_init(&wq->entry); |
Peter Zijlstra | a9668cd | 2017-06-07 17:51:27 +0200 | [diff] [blame] | 141 | } |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 142 | out: |
| 143 | return ret; |
| 144 | } |
| 145 | |
| 146 | /** |
| 147 | * userfaultfd_ctx_get - Acquires a reference to the internal userfaultfd |
| 148 | * context. |
| 149 | * @ctx: [in] Pointer to the userfaultfd context. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 150 | */ |
| 151 | static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx) |
| 152 | { |
Eric Biggers | ca88042 | 2018-12-28 00:34:43 -0800 | [diff] [blame] | 153 | refcount_inc(&ctx->refcount); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 154 | } |
| 155 | |
| 156 | /** |
| 157 | * userfaultfd_ctx_put - Releases a reference to the internal userfaultfd |
| 158 | * context. |
| 159 | * @ctx: [in] Pointer to userfaultfd context. |
| 160 | * |
| 161 | * The userfaultfd context reference must have been previously acquired either |
| 162 | * with userfaultfd_ctx_get() or userfaultfd_ctx_fdget(). |
| 163 | */ |
| 164 | static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx) |
| 165 | { |
Eric Biggers | ca88042 | 2018-12-28 00:34:43 -0800 | [diff] [blame] | 166 | if (refcount_dec_and_test(&ctx->refcount)) { |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 167 | VM_BUG_ON(spin_is_locked(&ctx->fault_pending_wqh.lock)); |
| 168 | VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh)); |
| 169 | VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock)); |
| 170 | VM_BUG_ON(waitqueue_active(&ctx->fault_wqh)); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 171 | VM_BUG_ON(spin_is_locked(&ctx->event_wqh.lock)); |
| 172 | VM_BUG_ON(waitqueue_active(&ctx->event_wqh)); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 173 | VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock)); |
| 174 | VM_BUG_ON(waitqueue_active(&ctx->fd_wqh)); |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 175 | mmdrop(ctx->mm); |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 176 | kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 177 | } |
| 178 | } |
| 179 | |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 180 | static inline void msg_init(struct uffd_msg *msg) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 181 | { |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 182 | BUILD_BUG_ON(sizeof(struct uffd_msg) != 32); |
| 183 | /* |
| 184 | * Must use memset to zero out the paddings or kernel data is |
| 185 | * leaked to userland. |
| 186 | */ |
| 187 | memset(msg, 0, sizeof(struct uffd_msg)); |
| 188 | } |
| 189 | |
| 190 | static inline struct uffd_msg userfault_msg(unsigned long address, |
| 191 | unsigned int flags, |
Alexey Perevalov | 9d4ac93 | 2017-09-06 16:23:56 -0700 | [diff] [blame] | 192 | unsigned long reason, |
| 193 | unsigned int features) |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 194 | { |
| 195 | struct uffd_msg msg; |
| 196 | msg_init(&msg); |
| 197 | msg.event = UFFD_EVENT_PAGEFAULT; |
| 198 | msg.arg.pagefault.address = address; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 199 | if (flags & FAULT_FLAG_WRITE) |
| 200 | /* |
Andrea Arcangeli | a4605a6 | 2017-02-22 15:42:09 -0800 | [diff] [blame] | 201 | * If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 202 | * uffdio_api.features and UFFD_PAGEFAULT_FLAG_WRITE |
| 203 | * was not set in a UFFD_EVENT_PAGEFAULT, it means it |
| 204 | * was a read fault, otherwise if set it means it's |
| 205 | * a write fault. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 206 | */ |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 207 | msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WRITE; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 208 | if (reason & VM_UFFD_WP) |
| 209 | /* |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 210 | * If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the |
| 211 | * uffdio_api.features and UFFD_PAGEFAULT_FLAG_WP was |
| 212 | * not set in a UFFD_EVENT_PAGEFAULT, it means it was |
| 213 | * a missing fault, otherwise if set it means it's a |
| 214 | * write protect fault. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 215 | */ |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 216 | msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WP; |
Alexey Perevalov | 9d4ac93 | 2017-09-06 16:23:56 -0700 | [diff] [blame] | 217 | if (features & UFFD_FEATURE_THREAD_ID) |
Andrea Arcangeli | a36985d | 2017-09-06 16:23:59 -0700 | [diff] [blame] | 218 | msg.arg.pagefault.feat.ptid = task_pid_vnr(current); |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 219 | return msg; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 220 | } |
| 221 | |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 222 | #ifdef CONFIG_HUGETLB_PAGE |
| 223 | /* |
| 224 | * Same functionality as userfaultfd_must_wait below with modifications for |
| 225 | * hugepmd ranges. |
| 226 | */ |
| 227 | static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, |
Punit Agrawal | 7868a20 | 2017-07-06 15:39:42 -0700 | [diff] [blame] | 228 | struct vm_area_struct *vma, |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 229 | unsigned long address, |
| 230 | unsigned long flags, |
| 231 | unsigned long reason) |
| 232 | { |
| 233 | struct mm_struct *mm = ctx->mm; |
Janosch Frank | 1e2c043 | 2018-07-03 17:02:39 -0700 | [diff] [blame] | 234 | pte_t *ptep, pte; |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 235 | bool ret = true; |
| 236 | |
| 237 | VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); |
| 238 | |
Janosch Frank | 1e2c043 | 2018-07-03 17:02:39 -0700 | [diff] [blame] | 239 | ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); |
| 240 | |
| 241 | if (!ptep) |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 242 | goto out; |
| 243 | |
| 244 | ret = false; |
Janosch Frank | 1e2c043 | 2018-07-03 17:02:39 -0700 | [diff] [blame] | 245 | pte = huge_ptep_get(ptep); |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 246 | |
| 247 | /* |
| 248 | * Lockless access: we're in a wait_event so it's ok if it |
| 249 | * changes under us. |
| 250 | */ |
Janosch Frank | 1e2c043 | 2018-07-03 17:02:39 -0700 | [diff] [blame] | 251 | if (huge_pte_none(pte)) |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 252 | ret = true; |
Janosch Frank | 1e2c043 | 2018-07-03 17:02:39 -0700 | [diff] [blame] | 253 | if (!huge_pte_write(pte) && (reason & VM_UFFD_WP)) |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 254 | ret = true; |
| 255 | out: |
| 256 | return ret; |
| 257 | } |
| 258 | #else |
| 259 | static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, |
Punit Agrawal | 7868a20 | 2017-07-06 15:39:42 -0700 | [diff] [blame] | 260 | struct vm_area_struct *vma, |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 261 | unsigned long address, |
| 262 | unsigned long flags, |
| 263 | unsigned long reason) |
| 264 | { |
| 265 | return false; /* should never get here */ |
| 266 | } |
| 267 | #endif /* CONFIG_HUGETLB_PAGE */ |
| 268 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 269 | /* |
Andrea Arcangeli | 8d2afd9 | 2015-09-04 15:46:51 -0700 | [diff] [blame] | 270 | * Verify the pagetables are still not ok after having reigstered into |
| 271 | * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any |
| 272 | * userfault that has already been resolved, if userfaultfd_read and |
| 273 | * UFFDIO_COPY|ZEROPAGE are being run simultaneously on two different |
| 274 | * threads. |
| 275 | */ |
| 276 | static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, |
| 277 | unsigned long address, |
| 278 | unsigned long flags, |
| 279 | unsigned long reason) |
| 280 | { |
| 281 | struct mm_struct *mm = ctx->mm; |
| 282 | pgd_t *pgd; |
Kirill A. Shutemov | c2febaf | 2017-03-09 17:24:07 +0300 | [diff] [blame] | 283 | p4d_t *p4d; |
Andrea Arcangeli | 8d2afd9 | 2015-09-04 15:46:51 -0700 | [diff] [blame] | 284 | pud_t *pud; |
| 285 | pmd_t *pmd, _pmd; |
| 286 | pte_t *pte; |
| 287 | bool ret = true; |
| 288 | |
| 289 | VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); |
| 290 | |
| 291 | pgd = pgd_offset(mm, address); |
| 292 | if (!pgd_present(*pgd)) |
| 293 | goto out; |
Kirill A. Shutemov | c2febaf | 2017-03-09 17:24:07 +0300 | [diff] [blame] | 294 | p4d = p4d_offset(pgd, address); |
| 295 | if (!p4d_present(*p4d)) |
| 296 | goto out; |
| 297 | pud = pud_offset(p4d, address); |
Andrea Arcangeli | 8d2afd9 | 2015-09-04 15:46:51 -0700 | [diff] [blame] | 298 | if (!pud_present(*pud)) |
| 299 | goto out; |
| 300 | pmd = pmd_offset(pud, address); |
| 301 | /* |
| 302 | * READ_ONCE must function as a barrier with narrower scope |
| 303 | * and it must be equivalent to: |
| 304 | * _pmd = *pmd; barrier(); |
| 305 | * |
| 306 | * This is to deal with the instability (as in |
| 307 | * pmd_trans_unstable) of the pmd. |
| 308 | */ |
| 309 | _pmd = READ_ONCE(*pmd); |
Huang Ying | a365ac0 | 2018-01-31 16:17:32 -0800 | [diff] [blame] | 310 | if (pmd_none(_pmd)) |
Andrea Arcangeli | 8d2afd9 | 2015-09-04 15:46:51 -0700 | [diff] [blame] | 311 | goto out; |
| 312 | |
| 313 | ret = false; |
Huang Ying | a365ac0 | 2018-01-31 16:17:32 -0800 | [diff] [blame] | 314 | if (!pmd_present(_pmd)) |
| 315 | goto out; |
| 316 | |
Andrea Arcangeli | 8d2afd9 | 2015-09-04 15:46:51 -0700 | [diff] [blame] | 317 | if (pmd_trans_huge(_pmd)) |
| 318 | goto out; |
| 319 | |
| 320 | /* |
| 321 | * the pmd is stable (as in !pmd_trans_unstable) so we can re-read it |
| 322 | * and use the standard pte_offset_map() instead of parsing _pmd. |
| 323 | */ |
| 324 | pte = pte_offset_map(pmd, address); |
| 325 | /* |
| 326 | * Lockless access: we're in a wait_event so it's ok if it |
| 327 | * changes under us. |
| 328 | */ |
| 329 | if (pte_none(*pte)) |
| 330 | ret = true; |
| 331 | pte_unmap(pte); |
| 332 | |
| 333 | out: |
| 334 | return ret; |
| 335 | } |
| 336 | |
| 337 | /* |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 338 | * The locking rules involved in returning VM_FAULT_RETRY depending on |
| 339 | * FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NOWAIT and |
| 340 | * FAULT_FLAG_KILLABLE are not straightforward. The "Caution" |
| 341 | * recommendation in __lock_page_or_retry is not an understatement. |
| 342 | * |
| 343 | * If FAULT_FLAG_ALLOW_RETRY is set, the mmap_sem must be released |
| 344 | * before returning VM_FAULT_RETRY only if FAULT_FLAG_RETRY_NOWAIT is |
| 345 | * not set. |
| 346 | * |
| 347 | * If FAULT_FLAG_ALLOW_RETRY is set but FAULT_FLAG_KILLABLE is not |
| 348 | * set, VM_FAULT_RETRY can still be returned if and only if there are |
| 349 | * fatal_signal_pending()s, and the mmap_sem must be released before |
| 350 | * returning it. |
| 351 | */ |
Souptick Joarder | 2b74030 | 2018-08-23 17:01:36 -0700 | [diff] [blame] | 352 | vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 353 | { |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 354 | struct mm_struct *mm = vmf->vma->vm_mm; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 355 | struct userfaultfd_ctx *ctx; |
| 356 | struct userfaultfd_wait_queue uwq; |
Souptick Joarder | 2b74030 | 2018-08-23 17:01:36 -0700 | [diff] [blame] | 357 | vm_fault_t ret = VM_FAULT_SIGBUS; |
Andrea Arcangeli | dfa37dc | 2015-09-04 15:47:18 -0700 | [diff] [blame] | 358 | bool must_wait, return_to_userland; |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 359 | long blocking_state; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 360 | |
Andrea Arcangeli | 64c2b20 | 2017-06-16 14:02:37 -0700 | [diff] [blame] | 361 | /* |
| 362 | * We don't do userfault handling for the final child pid update. |
| 363 | * |
| 364 | * We also don't do userfault handling during |
| 365 | * coredumping. hugetlbfs has the special |
| 366 | * follow_hugetlb_page() to skip missing pages in the |
| 367 | * FOLL_DUMP case, anon memory also checks for FOLL_DUMP with |
| 368 | * the no_page_table() helper in follow_page_mask(), but the |
| 369 | * shmem_vm_ops->fault method is invoked even during |
| 370 | * coredumping without mmap_sem and it ends up here. |
| 371 | */ |
| 372 | if (current->flags & (PF_EXITING|PF_DUMPCORE)) |
| 373 | goto out; |
| 374 | |
| 375 | /* |
| 376 | * Coredumping runs without mmap_sem so we can only check that |
| 377 | * the mmap_sem is held, if PF_DUMPCORE was not set. |
| 378 | */ |
| 379 | WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem)); |
| 380 | |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 381 | ctx = vmf->vma->vm_userfaultfd_ctx.ctx; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 382 | if (!ctx) |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 383 | goto out; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 384 | |
| 385 | BUG_ON(ctx->mm != mm); |
| 386 | |
| 387 | VM_BUG_ON(reason & ~(VM_UFFD_MISSING|VM_UFFD_WP)); |
| 388 | VM_BUG_ON(!(reason & VM_UFFD_MISSING) ^ !!(reason & VM_UFFD_WP)); |
| 389 | |
Prakash Sangappa | 2d6d6f5 | 2017-09-06 16:23:39 -0700 | [diff] [blame] | 390 | if (ctx->features & UFFD_FEATURE_SIGBUS) |
| 391 | goto out; |
| 392 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 393 | /* |
| 394 | * If it's already released don't get it. This avoids to loop |
| 395 | * in __get_user_pages if userfaultfd_release waits on the |
| 396 | * caller of handle_userfault to release the mmap_sem. |
| 397 | */ |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 398 | if (unlikely(READ_ONCE(ctx->released))) { |
Andrea Arcangeli | 656710a | 2017-09-08 16:12:42 -0700 | [diff] [blame] | 399 | /* |
| 400 | * Don't return VM_FAULT_SIGBUS in this case, so a non |
| 401 | * cooperative manager can close the uffd after the |
| 402 | * last UFFDIO_COPY, without risking to trigger an |
| 403 | * involuntary SIGBUS if the process was starting the |
| 404 | * userfaultfd while the userfaultfd was still armed |
| 405 | * (but after the last UFFDIO_COPY). If the uffd |
| 406 | * wasn't already closed when the userfault reached |
| 407 | * this point, that would normally be solved by |
| 408 | * userfaultfd_must_wait returning 'false'. |
| 409 | * |
| 410 | * If we were to return VM_FAULT_SIGBUS here, the non |
| 411 | * cooperative manager would be instead forced to |
| 412 | * always call UFFDIO_UNREGISTER before it can safely |
| 413 | * close the uffd. |
| 414 | */ |
| 415 | ret = VM_FAULT_NOPAGE; |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 416 | goto out; |
Andrea Arcangeli | 656710a | 2017-09-08 16:12:42 -0700 | [diff] [blame] | 417 | } |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 418 | |
| 419 | /* |
| 420 | * Check that we can return VM_FAULT_RETRY. |
| 421 | * |
| 422 | * NOTE: it should become possible to return VM_FAULT_RETRY |
| 423 | * even if FAULT_FLAG_TRIED is set without leading to gup() |
| 424 | * -EBUSY failures, if the userfaultfd is to be extended for |
| 425 | * VM_UFFD_WP tracking and we intend to arm the userfault |
| 426 | * without first stopping userland access to the memory. For |
| 427 | * VM_UFFD_MISSING userfaults this is enough for now. |
| 428 | */ |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 429 | if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) { |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 430 | /* |
| 431 | * Validate the invariant that nowait must allow retry |
| 432 | * to be sure not to return SIGBUS erroneously on |
| 433 | * nowait invocations. |
| 434 | */ |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 435 | BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 436 | #ifdef CONFIG_DEBUG_VM |
| 437 | if (printk_ratelimit()) { |
| 438 | printk(KERN_WARNING |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 439 | "FAULT_FLAG_ALLOW_RETRY missing %x\n", |
| 440 | vmf->flags); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 441 | dump_stack(); |
| 442 | } |
| 443 | #endif |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 444 | goto out; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 445 | } |
| 446 | |
| 447 | /* |
| 448 | * Handle nowait, not much to do other than tell it to retry |
| 449 | * and wait. |
| 450 | */ |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 451 | ret = VM_FAULT_RETRY; |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 452 | if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 453 | goto out; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 454 | |
| 455 | /* take the reference before dropping the mmap_sem */ |
| 456 | userfaultfd_ctx_get(ctx); |
| 457 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 458 | init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function); |
| 459 | uwq.wq.private = current; |
Alexey Perevalov | 9d4ac93 | 2017-09-06 16:23:56 -0700 | [diff] [blame] | 460 | uwq.msg = userfault_msg(vmf->address, vmf->flags, reason, |
| 461 | ctx->features); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 462 | uwq.ctx = ctx; |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 463 | uwq.waken = false; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 464 | |
Kirill A. Shutemov | bae473a | 2016-07-26 15:25:20 -0700 | [diff] [blame] | 465 | return_to_userland = |
Jan Kara | 82b0f8c | 2016-12-14 15:06:58 -0800 | [diff] [blame] | 466 | (vmf->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) == |
Andrea Arcangeli | dfa37dc | 2015-09-04 15:47:18 -0700 | [diff] [blame] | 467 | (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE); |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 468 | blocking_state = return_to_userland ? TASK_INTERRUPTIBLE : |
| 469 | TASK_KILLABLE; |
Andrea Arcangeli | dfa37dc | 2015-09-04 15:47:18 -0700 | [diff] [blame] | 470 | |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 471 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 472 | /* |
| 473 | * After the __add_wait_queue the uwq is visible to userland |
| 474 | * through poll/read(). |
| 475 | */ |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 476 | __add_wait_queue(&ctx->fault_pending_wqh, &uwq.wq); |
| 477 | /* |
| 478 | * The smp_mb() after __set_current_state prevents the reads |
| 479 | * following the spin_unlock to happen before the list_add in |
| 480 | * __add_wait_queue. |
| 481 | */ |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 482 | set_current_state(blocking_state); |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 483 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 484 | |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 485 | if (!is_vm_hugetlb_page(vmf->vma)) |
| 486 | must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, |
| 487 | reason); |
| 488 | else |
Punit Agrawal | 7868a20 | 2017-07-06 15:39:42 -0700 | [diff] [blame] | 489 | must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma, |
| 490 | vmf->address, |
Mike Kravetz | 369cd212 | 2017-02-22 15:43:10 -0800 | [diff] [blame] | 491 | vmf->flags, reason); |
Andrea Arcangeli | 8d2afd9 | 2015-09-04 15:46:51 -0700 | [diff] [blame] | 492 | up_read(&mm->mmap_sem); |
| 493 | |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 494 | if (likely(must_wait && !READ_ONCE(ctx->released) && |
Andrea Arcangeli | dfa37dc | 2015-09-04 15:47:18 -0700 | [diff] [blame] | 495 | (return_to_userland ? !signal_pending(current) : |
| 496 | !fatal_signal_pending(current)))) { |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 497 | wake_up_poll(&ctx->fd_wqh, EPOLLIN); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 498 | schedule(); |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 499 | ret |= VM_FAULT_MAJOR; |
Andrea Arcangeli | 15a77c6 | 2017-01-24 15:17:59 -0800 | [diff] [blame] | 500 | |
| 501 | /* |
| 502 | * False wakeups can orginate even from rwsem before |
| 503 | * up_read() however userfaults will wait either for a |
| 504 | * targeted wakeup on the specific uwq waitqueue from |
| 505 | * wake_userfault() or for signals or for uffd |
| 506 | * release. |
| 507 | */ |
| 508 | while (!READ_ONCE(uwq.waken)) { |
| 509 | /* |
| 510 | * This needs the full smp_store_mb() |
| 511 | * guarantee as the state write must be |
| 512 | * visible to other CPUs before reading |
| 513 | * uwq.waken from other CPUs. |
| 514 | */ |
| 515 | set_current_state(blocking_state); |
| 516 | if (READ_ONCE(uwq.waken) || |
| 517 | READ_ONCE(ctx->released) || |
| 518 | (return_to_userland ? signal_pending(current) : |
| 519 | fatal_signal_pending(current))) |
| 520 | break; |
| 521 | schedule(); |
| 522 | } |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 523 | } |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 524 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 525 | __set_current_state(TASK_RUNNING); |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 526 | |
Andrea Arcangeli | dfa37dc | 2015-09-04 15:47:18 -0700 | [diff] [blame] | 527 | if (return_to_userland) { |
| 528 | if (signal_pending(current) && |
| 529 | !fatal_signal_pending(current)) { |
| 530 | /* |
| 531 | * If we got a SIGSTOP or SIGCONT and this is |
| 532 | * a normal userland page fault, just let |
| 533 | * userland return so the signal will be |
| 534 | * handled and gdb debugging works. The page |
| 535 | * fault code immediately after we return from |
| 536 | * this function is going to release the |
| 537 | * mmap_sem and it's not depending on it |
| 538 | * (unlike gup would if we were not to return |
| 539 | * VM_FAULT_RETRY). |
| 540 | * |
| 541 | * If a fatal signal is pending we still take |
| 542 | * the streamlined VM_FAULT_RETRY failure path |
| 543 | * and there's no need to retake the mmap_sem |
| 544 | * in such case. |
| 545 | */ |
| 546 | down_read(&mm->mmap_sem); |
Andrea Arcangeli | 6bbc4a4 | 2017-03-09 16:16:28 -0800 | [diff] [blame] | 547 | ret = VM_FAULT_NOPAGE; |
Andrea Arcangeli | dfa37dc | 2015-09-04 15:47:18 -0700 | [diff] [blame] | 548 | } |
| 549 | } |
| 550 | |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 551 | /* |
| 552 | * Here we race with the list_del; list_add in |
| 553 | * userfaultfd_ctx_read(), however because we don't ever run |
| 554 | * list_del_init() to refile across the two lists, the prev |
| 555 | * and next pointers will never point to self. list_add also |
| 556 | * would never let any of the two pointers to point to |
| 557 | * self. So list_empty_careful won't risk to see both pointers |
| 558 | * pointing to self at any time during the list refile. The |
| 559 | * only case where list_del_init() is called is the full |
| 560 | * removal in the wake function and there we don't re-list_add |
| 561 | * and it's fine not to block on the spinlock. The uwq on this |
| 562 | * kernel stack can be released after the list_del_init. |
| 563 | */ |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 564 | if (!list_empty_careful(&uwq.wq.entry)) { |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 565 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 566 | /* |
| 567 | * No need of list_del_init(), the uwq on the stack |
| 568 | * will be freed shortly anyway. |
| 569 | */ |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 570 | list_del(&uwq.wq.entry); |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 571 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 572 | } |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 573 | |
| 574 | /* |
| 575 | * ctx may go away after this if the userfault pseudo fd is |
| 576 | * already released. |
| 577 | */ |
| 578 | userfaultfd_ctx_put(ctx); |
| 579 | |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 580 | out: |
| 581 | return ret; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 582 | } |
| 583 | |
Andrea Arcangeli | 8c9e7bb | 2017-03-09 16:16:54 -0800 | [diff] [blame] | 584 | static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx, |
| 585 | struct userfaultfd_wait_queue *ewq) |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 586 | { |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 587 | struct userfaultfd_ctx *release_new_ctx; |
| 588 | |
Andrea Arcangeli | 9a69a82 | 2017-03-09 16:16:52 -0800 | [diff] [blame] | 589 | if (WARN_ON_ONCE(current->flags & PF_EXITING)) |
| 590 | goto out; |
| 591 | |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 592 | ewq->ctx = ctx; |
| 593 | init_waitqueue_entry(&ewq->wq, current); |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 594 | release_new_ctx = NULL; |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 595 | |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 596 | spin_lock_irq(&ctx->event_wqh.lock); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 597 | /* |
| 598 | * After the __add_wait_queue the uwq is visible to userland |
| 599 | * through poll/read(). |
| 600 | */ |
| 601 | __add_wait_queue(&ctx->event_wqh, &ewq->wq); |
| 602 | for (;;) { |
| 603 | set_current_state(TASK_KILLABLE); |
| 604 | if (ewq->msg.event == 0) |
| 605 | break; |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 606 | if (READ_ONCE(ctx->released) || |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 607 | fatal_signal_pending(current)) { |
Andrea Arcangeli | 384632e | 2017-10-03 16:15:38 -0700 | [diff] [blame] | 608 | /* |
| 609 | * &ewq->wq may be queued in fork_event, but |
| 610 | * __remove_wait_queue ignores the head |
| 611 | * parameter. It would be a problem if it |
| 612 | * didn't. |
| 613 | */ |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 614 | __remove_wait_queue(&ctx->event_wqh, &ewq->wq); |
Mike Rapoport | 7eb76d4 | 2017-03-09 16:17:09 -0800 | [diff] [blame] | 615 | if (ewq->msg.event == UFFD_EVENT_FORK) { |
| 616 | struct userfaultfd_ctx *new; |
| 617 | |
| 618 | new = (struct userfaultfd_ctx *) |
| 619 | (unsigned long) |
| 620 | ewq->msg.arg.reserved.reserved1; |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 621 | release_new_ctx = new; |
Mike Rapoport | 7eb76d4 | 2017-03-09 16:17:09 -0800 | [diff] [blame] | 622 | } |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 623 | break; |
| 624 | } |
| 625 | |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 626 | spin_unlock_irq(&ctx->event_wqh.lock); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 627 | |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 628 | wake_up_poll(&ctx->fd_wqh, EPOLLIN); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 629 | schedule(); |
| 630 | |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 631 | spin_lock_irq(&ctx->event_wqh.lock); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 632 | } |
| 633 | __set_current_state(TASK_RUNNING); |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 634 | spin_unlock_irq(&ctx->event_wqh.lock); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 635 | |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 636 | if (release_new_ctx) { |
| 637 | struct vm_area_struct *vma; |
| 638 | struct mm_struct *mm = release_new_ctx->mm; |
| 639 | |
| 640 | /* the various vma->vm_userfaultfd_ctx still points to it */ |
| 641 | down_write(&mm->mmap_sem); |
Andrea Arcangeli | 04f5866 | 2019-04-18 17:50:52 -0700 | [diff] [blame] | 642 | /* no task can run (and in turn coredump) yet */ |
| 643 | VM_WARN_ON(!mmget_still_valid(mm)); |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 644 | for (vma = mm->mmap; vma; vma = vma->vm_next) |
Mike Rapoport | 31e810a | 2018-08-02 15:36:09 -0700 | [diff] [blame] | 645 | if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) { |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 646 | vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
Mike Rapoport | 31e810a | 2018-08-02 15:36:09 -0700 | [diff] [blame] | 647 | vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); |
| 648 | } |
Andrea Arcangeli | 0cbb4b4 | 2018-01-04 16:18:09 -0800 | [diff] [blame] | 649 | up_write(&mm->mmap_sem); |
| 650 | |
| 651 | userfaultfd_ctx_put(release_new_ctx); |
| 652 | } |
| 653 | |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 654 | /* |
| 655 | * ctx may go away after this if the userfault pseudo fd is |
| 656 | * already released. |
| 657 | */ |
Andrea Arcangeli | 9a69a82 | 2017-03-09 16:16:52 -0800 | [diff] [blame] | 658 | out: |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 659 | WRITE_ONCE(ctx->mmap_changing, false); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 660 | userfaultfd_ctx_put(ctx); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 661 | } |
| 662 | |
| 663 | static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx, |
| 664 | struct userfaultfd_wait_queue *ewq) |
| 665 | { |
| 666 | ewq->msg.event = 0; |
| 667 | wake_up_locked(&ctx->event_wqh); |
| 668 | __remove_wait_queue(&ctx->event_wqh, &ewq->wq); |
| 669 | } |
| 670 | |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 671 | int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs) |
| 672 | { |
| 673 | struct userfaultfd_ctx *ctx = NULL, *octx; |
| 674 | struct userfaultfd_fork_ctx *fctx; |
| 675 | |
| 676 | octx = vma->vm_userfaultfd_ctx.ctx; |
| 677 | if (!octx || !(octx->features & UFFD_FEATURE_EVENT_FORK)) { |
| 678 | vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
| 679 | vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); |
| 680 | return 0; |
| 681 | } |
| 682 | |
| 683 | list_for_each_entry(fctx, fcs, list) |
| 684 | if (fctx->orig == octx) { |
| 685 | ctx = fctx->new; |
| 686 | break; |
| 687 | } |
| 688 | |
| 689 | if (!ctx) { |
| 690 | fctx = kmalloc(sizeof(*fctx), GFP_KERNEL); |
| 691 | if (!fctx) |
| 692 | return -ENOMEM; |
| 693 | |
| 694 | ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); |
| 695 | if (!ctx) { |
| 696 | kfree(fctx); |
| 697 | return -ENOMEM; |
| 698 | } |
| 699 | |
Eric Biggers | ca88042 | 2018-12-28 00:34:43 -0800 | [diff] [blame] | 700 | refcount_set(&ctx->refcount, 1); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 701 | ctx->flags = octx->flags; |
| 702 | ctx->state = UFFD_STATE_RUNNING; |
| 703 | ctx->features = octx->features; |
| 704 | ctx->released = false; |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 705 | ctx->mmap_changing = false; |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 706 | ctx->mm = vma->vm_mm; |
Mike Rapoport | 00bb31f | 2017-11-15 17:36:56 -0800 | [diff] [blame] | 707 | mmgrab(ctx->mm); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 708 | |
| 709 | userfaultfd_ctx_get(octx); |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 710 | WRITE_ONCE(octx->mmap_changing, true); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 711 | fctx->orig = octx; |
| 712 | fctx->new = ctx; |
| 713 | list_add_tail(&fctx->list, fcs); |
| 714 | } |
| 715 | |
| 716 | vma->vm_userfaultfd_ctx.ctx = ctx; |
| 717 | return 0; |
| 718 | } |
| 719 | |
Andrea Arcangeli | 8c9e7bb | 2017-03-09 16:16:54 -0800 | [diff] [blame] | 720 | static void dup_fctx(struct userfaultfd_fork_ctx *fctx) |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 721 | { |
| 722 | struct userfaultfd_ctx *ctx = fctx->orig; |
| 723 | struct userfaultfd_wait_queue ewq; |
| 724 | |
| 725 | msg_init(&ewq.msg); |
| 726 | |
| 727 | ewq.msg.event = UFFD_EVENT_FORK; |
| 728 | ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new; |
| 729 | |
Andrea Arcangeli | 8c9e7bb | 2017-03-09 16:16:54 -0800 | [diff] [blame] | 730 | userfaultfd_event_wait_completion(ctx, &ewq); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 731 | } |
| 732 | |
| 733 | void dup_userfaultfd_complete(struct list_head *fcs) |
| 734 | { |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 735 | struct userfaultfd_fork_ctx *fctx, *n; |
| 736 | |
| 737 | list_for_each_entry_safe(fctx, n, fcs, list) { |
Andrea Arcangeli | 8c9e7bb | 2017-03-09 16:16:54 -0800 | [diff] [blame] | 738 | dup_fctx(fctx); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 739 | list_del(&fctx->list); |
| 740 | kfree(fctx); |
| 741 | } |
| 742 | } |
| 743 | |
Pavel Emelyanov | 72f8765 | 2017-02-22 15:42:34 -0800 | [diff] [blame] | 744 | void mremap_userfaultfd_prep(struct vm_area_struct *vma, |
| 745 | struct vm_userfaultfd_ctx *vm_ctx) |
| 746 | { |
| 747 | struct userfaultfd_ctx *ctx; |
| 748 | |
| 749 | ctx = vma->vm_userfaultfd_ctx.ctx; |
Peter Xu | 3cfd22b | 2018-12-28 00:38:47 -0800 | [diff] [blame] | 750 | |
| 751 | if (!ctx) |
| 752 | return; |
| 753 | |
| 754 | if (ctx->features & UFFD_FEATURE_EVENT_REMAP) { |
Pavel Emelyanov | 72f8765 | 2017-02-22 15:42:34 -0800 | [diff] [blame] | 755 | vm_ctx->ctx = ctx; |
| 756 | userfaultfd_ctx_get(ctx); |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 757 | WRITE_ONCE(ctx->mmap_changing, true); |
Peter Xu | 3cfd22b | 2018-12-28 00:38:47 -0800 | [diff] [blame] | 758 | } else { |
| 759 | /* Drop uffd context if remap feature not enabled */ |
| 760 | vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
| 761 | vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); |
Pavel Emelyanov | 72f8765 | 2017-02-22 15:42:34 -0800 | [diff] [blame] | 762 | } |
| 763 | } |
| 764 | |
Andrea Arcangeli | 90794bf | 2017-02-22 15:42:37 -0800 | [diff] [blame] | 765 | void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx, |
Pavel Emelyanov | 72f8765 | 2017-02-22 15:42:34 -0800 | [diff] [blame] | 766 | unsigned long from, unsigned long to, |
| 767 | unsigned long len) |
| 768 | { |
Andrea Arcangeli | 90794bf | 2017-02-22 15:42:37 -0800 | [diff] [blame] | 769 | struct userfaultfd_ctx *ctx = vm_ctx->ctx; |
Pavel Emelyanov | 72f8765 | 2017-02-22 15:42:34 -0800 | [diff] [blame] | 770 | struct userfaultfd_wait_queue ewq; |
| 771 | |
| 772 | if (!ctx) |
| 773 | return; |
| 774 | |
| 775 | if (to & ~PAGE_MASK) { |
| 776 | userfaultfd_ctx_put(ctx); |
| 777 | return; |
| 778 | } |
| 779 | |
| 780 | msg_init(&ewq.msg); |
| 781 | |
| 782 | ewq.msg.event = UFFD_EVENT_REMAP; |
| 783 | ewq.msg.arg.remap.from = from; |
| 784 | ewq.msg.arg.remap.to = to; |
| 785 | ewq.msg.arg.remap.len = len; |
| 786 | |
| 787 | userfaultfd_event_wait_completion(ctx, &ewq); |
| 788 | } |
| 789 | |
Andrea Arcangeli | 70ccb92 | 2017-03-09 16:17:11 -0800 | [diff] [blame] | 790 | bool userfaultfd_remove(struct vm_area_struct *vma, |
Mike Rapoport | d811914 | 2017-02-24 14:56:02 -0800 | [diff] [blame] | 791 | unsigned long start, unsigned long end) |
Pavel Emelyanov | 05ce772 | 2017-02-22 15:42:40 -0800 | [diff] [blame] | 792 | { |
| 793 | struct mm_struct *mm = vma->vm_mm; |
| 794 | struct userfaultfd_ctx *ctx; |
| 795 | struct userfaultfd_wait_queue ewq; |
| 796 | |
| 797 | ctx = vma->vm_userfaultfd_ctx.ctx; |
Mike Rapoport | d811914 | 2017-02-24 14:56:02 -0800 | [diff] [blame] | 798 | if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_REMOVE)) |
Andrea Arcangeli | 70ccb92 | 2017-03-09 16:17:11 -0800 | [diff] [blame] | 799 | return true; |
Pavel Emelyanov | 05ce772 | 2017-02-22 15:42:40 -0800 | [diff] [blame] | 800 | |
| 801 | userfaultfd_ctx_get(ctx); |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 802 | WRITE_ONCE(ctx->mmap_changing, true); |
Pavel Emelyanov | 05ce772 | 2017-02-22 15:42:40 -0800 | [diff] [blame] | 803 | up_read(&mm->mmap_sem); |
| 804 | |
Pavel Emelyanov | 05ce772 | 2017-02-22 15:42:40 -0800 | [diff] [blame] | 805 | msg_init(&ewq.msg); |
| 806 | |
Mike Rapoport | d811914 | 2017-02-24 14:56:02 -0800 | [diff] [blame] | 807 | ewq.msg.event = UFFD_EVENT_REMOVE; |
| 808 | ewq.msg.arg.remove.start = start; |
| 809 | ewq.msg.arg.remove.end = end; |
Pavel Emelyanov | 05ce772 | 2017-02-22 15:42:40 -0800 | [diff] [blame] | 810 | |
| 811 | userfaultfd_event_wait_completion(ctx, &ewq); |
| 812 | |
Andrea Arcangeli | 70ccb92 | 2017-03-09 16:17:11 -0800 | [diff] [blame] | 813 | return false; |
Pavel Emelyanov | 05ce772 | 2017-02-22 15:42:40 -0800 | [diff] [blame] | 814 | } |
| 815 | |
Mike Rapoport | 897ab3e | 2017-02-24 14:58:22 -0800 | [diff] [blame] | 816 | static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps, |
| 817 | unsigned long start, unsigned long end) |
| 818 | { |
| 819 | struct userfaultfd_unmap_ctx *unmap_ctx; |
| 820 | |
| 821 | list_for_each_entry(unmap_ctx, unmaps, list) |
| 822 | if (unmap_ctx->ctx == ctx && unmap_ctx->start == start && |
| 823 | unmap_ctx->end == end) |
| 824 | return true; |
| 825 | |
| 826 | return false; |
| 827 | } |
| 828 | |
| 829 | int userfaultfd_unmap_prep(struct vm_area_struct *vma, |
| 830 | unsigned long start, unsigned long end, |
| 831 | struct list_head *unmaps) |
| 832 | { |
| 833 | for ( ; vma && vma->vm_start < end; vma = vma->vm_next) { |
| 834 | struct userfaultfd_unmap_ctx *unmap_ctx; |
| 835 | struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; |
| 836 | |
| 837 | if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) || |
| 838 | has_unmap_ctx(ctx, unmaps, start, end)) |
| 839 | continue; |
| 840 | |
| 841 | unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL); |
| 842 | if (!unmap_ctx) |
| 843 | return -ENOMEM; |
| 844 | |
| 845 | userfaultfd_ctx_get(ctx); |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 846 | WRITE_ONCE(ctx->mmap_changing, true); |
Mike Rapoport | 897ab3e | 2017-02-24 14:58:22 -0800 | [diff] [blame] | 847 | unmap_ctx->ctx = ctx; |
| 848 | unmap_ctx->start = start; |
| 849 | unmap_ctx->end = end; |
| 850 | list_add_tail(&unmap_ctx->list, unmaps); |
| 851 | } |
| 852 | |
| 853 | return 0; |
| 854 | } |
| 855 | |
| 856 | void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf) |
| 857 | { |
| 858 | struct userfaultfd_unmap_ctx *ctx, *n; |
| 859 | struct userfaultfd_wait_queue ewq; |
| 860 | |
| 861 | list_for_each_entry_safe(ctx, n, uf, list) { |
| 862 | msg_init(&ewq.msg); |
| 863 | |
| 864 | ewq.msg.event = UFFD_EVENT_UNMAP; |
| 865 | ewq.msg.arg.remove.start = ctx->start; |
| 866 | ewq.msg.arg.remove.end = ctx->end; |
| 867 | |
| 868 | userfaultfd_event_wait_completion(ctx->ctx, &ewq); |
| 869 | |
| 870 | list_del(&ctx->list); |
| 871 | kfree(ctx); |
| 872 | } |
| 873 | } |
| 874 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 875 | static int userfaultfd_release(struct inode *inode, struct file *file) |
| 876 | { |
| 877 | struct userfaultfd_ctx *ctx = file->private_data; |
| 878 | struct mm_struct *mm = ctx->mm; |
| 879 | struct vm_area_struct *vma, *prev; |
| 880 | /* len == 0 means wake all */ |
| 881 | struct userfaultfd_wake_range range = { .len = 0, }; |
| 882 | unsigned long new_flags; |
| 883 | |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 884 | WRITE_ONCE(ctx->released, true); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 885 | |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 886 | if (!mmget_not_zero(mm)) |
| 887 | goto wakeup; |
| 888 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 889 | /* |
| 890 | * Flush page faults out of all CPUs. NOTE: all page faults |
| 891 | * must be retried without returning VM_FAULT_SIGBUS if |
| 892 | * userfaultfd_ctx_get() succeeds but vma->vma_userfault_ctx |
| 893 | * changes while handle_userfault released the mmap_sem. So |
| 894 | * it's critical that released is set to true (above), before |
| 895 | * taking the mmap_sem for writing. |
| 896 | */ |
| 897 | down_write(&mm->mmap_sem); |
Andrea Arcangeli | 04f5866 | 2019-04-18 17:50:52 -0700 | [diff] [blame] | 898 | if (!mmget_still_valid(mm)) |
| 899 | goto skip_mm; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 900 | prev = NULL; |
| 901 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| 902 | cond_resched(); |
| 903 | BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^ |
| 904 | !!(vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); |
| 905 | if (vma->vm_userfaultfd_ctx.ctx != ctx) { |
| 906 | prev = vma; |
| 907 | continue; |
| 908 | } |
| 909 | new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); |
| 910 | prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end, |
| 911 | new_flags, vma->anon_vma, |
| 912 | vma->vm_file, vma->vm_pgoff, |
| 913 | vma_policy(vma), |
| 914 | NULL_VM_UFFD_CTX); |
| 915 | if (prev) |
| 916 | vma = prev; |
| 917 | else |
| 918 | prev = vma; |
| 919 | vma->vm_flags = new_flags; |
| 920 | vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
| 921 | } |
Andrea Arcangeli | 04f5866 | 2019-04-18 17:50:52 -0700 | [diff] [blame] | 922 | skip_mm: |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 923 | up_write(&mm->mmap_sem); |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 924 | mmput(mm); |
| 925 | wakeup: |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 926 | /* |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 927 | * After no new page faults can wait on this fault_*wqh, flush |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 928 | * the last page faults that may have been already waiting on |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 929 | * the fault_*wqh. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 930 | */ |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 931 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | ac5be6b | 2015-09-22 14:58:49 -0700 | [diff] [blame] | 932 | __wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range); |
Matthew Wilcox | c430d1e | 2018-08-21 21:56:30 -0700 | [diff] [blame] | 933 | __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range); |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 934 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 935 | |
Mike Rapoport | 5a18b64 | 2017-08-02 13:32:24 -0700 | [diff] [blame] | 936 | /* Flush pending events that may still wait on event_wqh */ |
| 937 | wake_up_all(&ctx->event_wqh); |
| 938 | |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 939 | wake_up_poll(&ctx->fd_wqh, EPOLLHUP); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 940 | userfaultfd_ctx_put(ctx); |
| 941 | return 0; |
| 942 | } |
| 943 | |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 944 | /* fault_pending_wqh.lock must be hold by the caller */ |
Pavel Emelyanov | 6dcc27f | 2017-02-22 15:42:18 -0800 | [diff] [blame] | 945 | static inline struct userfaultfd_wait_queue *find_userfault_in( |
| 946 | wait_queue_head_t *wqh) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 947 | { |
Ingo Molnar | ac6424b | 2017-06-20 12:06:13 +0200 | [diff] [blame] | 948 | wait_queue_entry_t *wq; |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 949 | struct userfaultfd_wait_queue *uwq; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 950 | |
Lance Roy | 456a737 | 2018-10-04 23:45:44 -0700 | [diff] [blame] | 951 | lockdep_assert_held(&wqh->lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 952 | |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 953 | uwq = NULL; |
Pavel Emelyanov | 6dcc27f | 2017-02-22 15:42:18 -0800 | [diff] [blame] | 954 | if (!waitqueue_active(wqh)) |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 955 | goto out; |
| 956 | /* walk in reverse to provide FIFO behavior to read userfaults */ |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 957 | wq = list_last_entry(&wqh->head, typeof(*wq), entry); |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 958 | uwq = container_of(wq, struct userfaultfd_wait_queue, wq); |
| 959 | out: |
| 960 | return uwq; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 961 | } |
| 962 | |
Pavel Emelyanov | 6dcc27f | 2017-02-22 15:42:18 -0800 | [diff] [blame] | 963 | static inline struct userfaultfd_wait_queue *find_userfault( |
| 964 | struct userfaultfd_ctx *ctx) |
| 965 | { |
| 966 | return find_userfault_in(&ctx->fault_pending_wqh); |
| 967 | } |
| 968 | |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 969 | static inline struct userfaultfd_wait_queue *find_userfault_evt( |
| 970 | struct userfaultfd_ctx *ctx) |
| 971 | { |
| 972 | return find_userfault_in(&ctx->event_wqh); |
| 973 | } |
| 974 | |
Al Viro | 076ccb7 | 2017-07-03 01:02:18 -0400 | [diff] [blame] | 975 | static __poll_t userfaultfd_poll(struct file *file, poll_table *wait) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 976 | { |
| 977 | struct userfaultfd_ctx *ctx = file->private_data; |
Al Viro | 076ccb7 | 2017-07-03 01:02:18 -0400 | [diff] [blame] | 978 | __poll_t ret; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 979 | |
| 980 | poll_wait(file, &ctx->fd_wqh, wait); |
| 981 | |
| 982 | switch (ctx->state) { |
| 983 | case UFFD_STATE_WAIT_API: |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 984 | return EPOLLERR; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 985 | case UFFD_STATE_RUNNING: |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 986 | /* |
| 987 | * poll() never guarantees that read won't block. |
| 988 | * userfaults can be waken before they're read(). |
| 989 | */ |
| 990 | if (unlikely(!(file->f_flags & O_NONBLOCK))) |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 991 | return EPOLLERR; |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 992 | /* |
| 993 | * lockless access to see if there are pending faults |
| 994 | * __pollwait last action is the add_wait_queue but |
| 995 | * the spin_unlock would allow the waitqueue_active to |
| 996 | * pass above the actual list_add inside |
| 997 | * add_wait_queue critical section. So use a full |
| 998 | * memory barrier to serialize the list_add write of |
| 999 | * add_wait_queue() with the waitqueue_active read |
| 1000 | * below. |
| 1001 | */ |
| 1002 | ret = 0; |
| 1003 | smp_mb(); |
| 1004 | if (waitqueue_active(&ctx->fault_pending_wqh)) |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 1005 | ret = EPOLLIN; |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1006 | else if (waitqueue_active(&ctx->event_wqh)) |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 1007 | ret = EPOLLIN; |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1008 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1009 | return ret; |
| 1010 | default: |
Andrea Arcangeli | 8474901 | 2017-02-22 15:42:12 -0800 | [diff] [blame] | 1011 | WARN_ON_ONCE(1); |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 1012 | return EPOLLERR; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1013 | } |
| 1014 | } |
| 1015 | |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1016 | static const struct file_operations userfaultfd_fops; |
| 1017 | |
| 1018 | static int resolve_userfault_fork(struct userfaultfd_ctx *ctx, |
| 1019 | struct userfaultfd_ctx *new, |
| 1020 | struct uffd_msg *msg) |
| 1021 | { |
| 1022 | int fd; |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1023 | |
Eric Biggers | 284cd24 | 2018-01-31 16:19:48 -0800 | [diff] [blame] | 1024 | fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new, |
| 1025 | O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS)); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1026 | if (fd < 0) |
| 1027 | return fd; |
| 1028 | |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1029 | msg->arg.reserved.reserved1 = 0; |
| 1030 | msg->arg.fork.ufd = fd; |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1031 | return 0; |
| 1032 | } |
| 1033 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1034 | static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1035 | struct uffd_msg *msg) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1036 | { |
| 1037 | ssize_t ret; |
| 1038 | DECLARE_WAITQUEUE(wait, current); |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1039 | struct userfaultfd_wait_queue *uwq; |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1040 | /* |
| 1041 | * Handling fork event requires sleeping operations, so |
| 1042 | * we drop the event_wqh lock, then do these ops, then |
| 1043 | * lock it back and wake up the waiter. While the lock is |
| 1044 | * dropped the ewq may go away so we keep track of it |
| 1045 | * carefully. |
| 1046 | */ |
| 1047 | LIST_HEAD(fork_event); |
| 1048 | struct userfaultfd_ctx *fork_nctx = NULL; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1049 | |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1050 | /* always take the fd_wqh lock before the fault_pending_wqh lock */ |
Christoph Hellwig | ae62c16 | 2018-10-26 15:02:19 -0700 | [diff] [blame] | 1051 | spin_lock_irq(&ctx->fd_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1052 | __add_wait_queue(&ctx->fd_wqh, &wait); |
| 1053 | for (;;) { |
| 1054 | set_current_state(TASK_INTERRUPTIBLE); |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1055 | spin_lock(&ctx->fault_pending_wqh.lock); |
| 1056 | uwq = find_userfault(ctx); |
| 1057 | if (uwq) { |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1058 | /* |
Andrea Arcangeli | 2c5b7e1 | 2015-09-04 15:47:23 -0700 | [diff] [blame] | 1059 | * Use a seqcount to repeat the lockless check |
| 1060 | * in wake_userfault() to avoid missing |
| 1061 | * wakeups because during the refile both |
| 1062 | * waitqueue could become empty if this is the |
| 1063 | * only userfault. |
| 1064 | */ |
| 1065 | write_seqcount_begin(&ctx->refile_seq); |
| 1066 | |
| 1067 | /* |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1068 | * The fault_pending_wqh.lock prevents the uwq |
| 1069 | * to disappear from under us. |
| 1070 | * |
| 1071 | * Refile this userfault from |
| 1072 | * fault_pending_wqh to fault_wqh, it's not |
| 1073 | * pending anymore after we read it. |
| 1074 | * |
| 1075 | * Use list_del() by hand (as |
| 1076 | * userfaultfd_wake_function also uses |
| 1077 | * list_del_init() by hand) to be sure nobody |
| 1078 | * changes __remove_wait_queue() to use |
| 1079 | * list_del_init() in turn breaking the |
| 1080 | * !list_empty_careful() check in |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 1081 | * handle_userfault(). The uwq->wq.head list |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1082 | * must never be empty at any time during the |
| 1083 | * refile, or the waitqueue could disappear |
| 1084 | * from under us. The "wait_queue_head_t" |
| 1085 | * parameter of __remove_wait_queue() is unused |
| 1086 | * anyway. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1087 | */ |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 1088 | list_del(&uwq->wq.entry); |
Matthew Wilcox | c430d1e | 2018-08-21 21:56:30 -0700 | [diff] [blame] | 1089 | add_wait_queue(&ctx->fault_wqh, &uwq->wq); |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1090 | |
Andrea Arcangeli | 2c5b7e1 | 2015-09-04 15:47:23 -0700 | [diff] [blame] | 1091 | write_seqcount_end(&ctx->refile_seq); |
| 1092 | |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1093 | /* careful to always initialize msg if ret == 0 */ |
| 1094 | *msg = uwq->msg; |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1095 | spin_unlock(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1096 | ret = 0; |
| 1097 | break; |
| 1098 | } |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1099 | spin_unlock(&ctx->fault_pending_wqh.lock); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1100 | |
| 1101 | spin_lock(&ctx->event_wqh.lock); |
| 1102 | uwq = find_userfault_evt(ctx); |
| 1103 | if (uwq) { |
| 1104 | *msg = uwq->msg; |
| 1105 | |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1106 | if (uwq->msg.event == UFFD_EVENT_FORK) { |
| 1107 | fork_nctx = (struct userfaultfd_ctx *) |
| 1108 | (unsigned long) |
| 1109 | uwq->msg.arg.reserved.reserved1; |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 1110 | list_move(&uwq->wq.entry, &fork_event); |
Andrea Arcangeli | 384632e | 2017-10-03 16:15:38 -0700 | [diff] [blame] | 1111 | /* |
| 1112 | * fork_nctx can be freed as soon as |
| 1113 | * we drop the lock, unless we take a |
| 1114 | * reference on it. |
| 1115 | */ |
| 1116 | userfaultfd_ctx_get(fork_nctx); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1117 | spin_unlock(&ctx->event_wqh.lock); |
| 1118 | ret = 0; |
| 1119 | break; |
| 1120 | } |
| 1121 | |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1122 | userfaultfd_event_complete(ctx, uwq); |
| 1123 | spin_unlock(&ctx->event_wqh.lock); |
| 1124 | ret = 0; |
| 1125 | break; |
| 1126 | } |
| 1127 | spin_unlock(&ctx->event_wqh.lock); |
| 1128 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1129 | if (signal_pending(current)) { |
| 1130 | ret = -ERESTARTSYS; |
| 1131 | break; |
| 1132 | } |
| 1133 | if (no_wait) { |
| 1134 | ret = -EAGAIN; |
| 1135 | break; |
| 1136 | } |
Christoph Hellwig | ae62c16 | 2018-10-26 15:02:19 -0700 | [diff] [blame] | 1137 | spin_unlock_irq(&ctx->fd_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1138 | schedule(); |
Christoph Hellwig | ae62c16 | 2018-10-26 15:02:19 -0700 | [diff] [blame] | 1139 | spin_lock_irq(&ctx->fd_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1140 | } |
| 1141 | __remove_wait_queue(&ctx->fd_wqh, &wait); |
| 1142 | __set_current_state(TASK_RUNNING); |
Christoph Hellwig | ae62c16 | 2018-10-26 15:02:19 -0700 | [diff] [blame] | 1143 | spin_unlock_irq(&ctx->fd_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1144 | |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1145 | if (!ret && msg->event == UFFD_EVENT_FORK) { |
| 1146 | ret = resolve_userfault_fork(ctx, fork_nctx, msg); |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 1147 | spin_lock_irq(&ctx->event_wqh.lock); |
Andrea Arcangeli | 384632e | 2017-10-03 16:15:38 -0700 | [diff] [blame] | 1148 | if (!list_empty(&fork_event)) { |
| 1149 | /* |
| 1150 | * The fork thread didn't abort, so we can |
| 1151 | * drop the temporary refcount. |
| 1152 | */ |
| 1153 | userfaultfd_ctx_put(fork_nctx); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1154 | |
Andrea Arcangeli | 384632e | 2017-10-03 16:15:38 -0700 | [diff] [blame] | 1155 | uwq = list_first_entry(&fork_event, |
| 1156 | typeof(*uwq), |
| 1157 | wq.entry); |
| 1158 | /* |
| 1159 | * If fork_event list wasn't empty and in turn |
| 1160 | * the event wasn't already released by fork |
| 1161 | * (the event is allocated on fork kernel |
| 1162 | * stack), put the event back to its place in |
| 1163 | * the event_wq. fork_event head will be freed |
| 1164 | * as soon as we return so the event cannot |
| 1165 | * stay queued there no matter the current |
| 1166 | * "ret" value. |
| 1167 | */ |
| 1168 | list_del(&uwq->wq.entry); |
| 1169 | __add_wait_queue(&ctx->event_wqh, &uwq->wq); |
| 1170 | |
| 1171 | /* |
| 1172 | * Leave the event in the waitqueue and report |
| 1173 | * error to userland if we failed to resolve |
| 1174 | * the userfault fork. |
| 1175 | */ |
| 1176 | if (likely(!ret)) |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1177 | userfaultfd_event_complete(ctx, uwq); |
Andrea Arcangeli | 384632e | 2017-10-03 16:15:38 -0700 | [diff] [blame] | 1178 | } else { |
| 1179 | /* |
| 1180 | * Here the fork thread aborted and the |
| 1181 | * refcount from the fork thread on fork_nctx |
| 1182 | * has already been released. We still hold |
| 1183 | * the reference we took before releasing the |
| 1184 | * lock above. If resolve_userfault_fork |
| 1185 | * failed we've to drop it because the |
| 1186 | * fork_nctx has to be freed in such case. If |
| 1187 | * it succeeded we'll hold it because the new |
| 1188 | * uffd references it. |
| 1189 | */ |
| 1190 | if (ret) |
| 1191 | userfaultfd_ctx_put(fork_nctx); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1192 | } |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 1193 | spin_unlock_irq(&ctx->event_wqh.lock); |
Pavel Emelyanov | 893e26e | 2017-02-22 15:42:27 -0800 | [diff] [blame] | 1194 | } |
| 1195 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1196 | return ret; |
| 1197 | } |
| 1198 | |
| 1199 | static ssize_t userfaultfd_read(struct file *file, char __user *buf, |
| 1200 | size_t count, loff_t *ppos) |
| 1201 | { |
| 1202 | struct userfaultfd_ctx *ctx = file->private_data; |
| 1203 | ssize_t _ret, ret = 0; |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1204 | struct uffd_msg msg; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1205 | int no_wait = file->f_flags & O_NONBLOCK; |
| 1206 | |
| 1207 | if (ctx->state == UFFD_STATE_WAIT_API) |
| 1208 | return -EINVAL; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1209 | |
| 1210 | for (;;) { |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1211 | if (count < sizeof(msg)) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1212 | return ret ? ret : -EINVAL; |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1213 | _ret = userfaultfd_ctx_read(ctx, no_wait, &msg); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1214 | if (_ret < 0) |
| 1215 | return ret ? ret : _ret; |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1216 | if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg))) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1217 | return ret ? ret : -EFAULT; |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1218 | ret += sizeof(msg); |
| 1219 | buf += sizeof(msg); |
| 1220 | count -= sizeof(msg); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1221 | /* |
| 1222 | * Allow to read more than one fault at time but only |
| 1223 | * block if waiting for the very first one. |
| 1224 | */ |
| 1225 | no_wait = O_NONBLOCK; |
| 1226 | } |
| 1227 | } |
| 1228 | |
| 1229 | static void __wake_userfault(struct userfaultfd_ctx *ctx, |
| 1230 | struct userfaultfd_wake_range *range) |
| 1231 | { |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 1232 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1233 | /* wake all in the range and autoremove */ |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1234 | if (waitqueue_active(&ctx->fault_pending_wqh)) |
Andrea Arcangeli | ac5be6b | 2015-09-22 14:58:49 -0700 | [diff] [blame] | 1235 | __wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1236 | range); |
| 1237 | if (waitqueue_active(&ctx->fault_wqh)) |
Matthew Wilcox | c430d1e | 2018-08-21 21:56:30 -0700 | [diff] [blame] | 1238 | __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range); |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 1239 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1240 | } |
| 1241 | |
| 1242 | static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, |
| 1243 | struct userfaultfd_wake_range *range) |
| 1244 | { |
Andrea Arcangeli | 2c5b7e1 | 2015-09-04 15:47:23 -0700 | [diff] [blame] | 1245 | unsigned seq; |
| 1246 | bool need_wakeup; |
| 1247 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1248 | /* |
| 1249 | * To be sure waitqueue_active() is not reordered by the CPU |
| 1250 | * before the pagetable update, use an explicit SMP memory |
| 1251 | * barrier here. PT lock release or up_read(mmap_sem) still |
| 1252 | * have release semantics that can allow the |
| 1253 | * waitqueue_active() to be reordered before the pte update. |
| 1254 | */ |
| 1255 | smp_mb(); |
| 1256 | |
| 1257 | /* |
| 1258 | * Use waitqueue_active because it's very frequent to |
| 1259 | * change the address space atomically even if there are no |
| 1260 | * userfaults yet. So we take the spinlock only when we're |
| 1261 | * sure we've userfaults to wake. |
| 1262 | */ |
Andrea Arcangeli | 2c5b7e1 | 2015-09-04 15:47:23 -0700 | [diff] [blame] | 1263 | do { |
| 1264 | seq = read_seqcount_begin(&ctx->refile_seq); |
| 1265 | need_wakeup = waitqueue_active(&ctx->fault_pending_wqh) || |
| 1266 | waitqueue_active(&ctx->fault_wqh); |
| 1267 | cond_resched(); |
| 1268 | } while (read_seqcount_retry(&ctx->refile_seq, seq)); |
| 1269 | if (need_wakeup) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1270 | __wake_userfault(ctx, range); |
| 1271 | } |
| 1272 | |
| 1273 | static __always_inline int validate_range(struct mm_struct *mm, |
| 1274 | __u64 start, __u64 len) |
| 1275 | { |
| 1276 | __u64 task_size = mm->task_size; |
| 1277 | |
| 1278 | if (start & ~PAGE_MASK) |
| 1279 | return -EINVAL; |
| 1280 | if (len & ~PAGE_MASK) |
| 1281 | return -EINVAL; |
| 1282 | if (!len) |
| 1283 | return -EINVAL; |
| 1284 | if (start < mmap_min_addr) |
| 1285 | return -EINVAL; |
| 1286 | if (start >= task_size) |
| 1287 | return -EINVAL; |
| 1288 | if (len > task_size - start) |
| 1289 | return -EINVAL; |
| 1290 | return 0; |
| 1291 | } |
| 1292 | |
Mike Rapoport | ba6907d | 2017-02-22 15:43:22 -0800 | [diff] [blame] | 1293 | static inline bool vma_can_userfault(struct vm_area_struct *vma) |
| 1294 | { |
Mike Rapoport | cac6732 | 2017-02-22 15:43:40 -0800 | [diff] [blame] | 1295 | return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || |
| 1296 | vma_is_shmem(vma); |
Mike Rapoport | ba6907d | 2017-02-22 15:43:22 -0800 | [diff] [blame] | 1297 | } |
| 1298 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1299 | static int userfaultfd_register(struct userfaultfd_ctx *ctx, |
| 1300 | unsigned long arg) |
| 1301 | { |
| 1302 | struct mm_struct *mm = ctx->mm; |
| 1303 | struct vm_area_struct *vma, *prev, *cur; |
| 1304 | int ret; |
| 1305 | struct uffdio_register uffdio_register; |
| 1306 | struct uffdio_register __user *user_uffdio_register; |
| 1307 | unsigned long vm_flags, new_flags; |
| 1308 | bool found; |
Mike Rapoport | ce53e8e | 2017-09-06 16:23:12 -0700 | [diff] [blame] | 1309 | bool basic_ioctls; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1310 | unsigned long start, end, vma_end; |
| 1311 | |
| 1312 | user_uffdio_register = (struct uffdio_register __user *) arg; |
| 1313 | |
| 1314 | ret = -EFAULT; |
| 1315 | if (copy_from_user(&uffdio_register, user_uffdio_register, |
| 1316 | sizeof(uffdio_register)-sizeof(__u64))) |
| 1317 | goto out; |
| 1318 | |
| 1319 | ret = -EINVAL; |
| 1320 | if (!uffdio_register.mode) |
| 1321 | goto out; |
| 1322 | if (uffdio_register.mode & ~(UFFDIO_REGISTER_MODE_MISSING| |
| 1323 | UFFDIO_REGISTER_MODE_WP)) |
| 1324 | goto out; |
| 1325 | vm_flags = 0; |
| 1326 | if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) |
| 1327 | vm_flags |= VM_UFFD_MISSING; |
| 1328 | if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { |
| 1329 | vm_flags |= VM_UFFD_WP; |
| 1330 | /* |
| 1331 | * FIXME: remove the below error constraint by |
| 1332 | * implementing the wprotect tracking mode. |
| 1333 | */ |
| 1334 | ret = -EINVAL; |
| 1335 | goto out; |
| 1336 | } |
| 1337 | |
| 1338 | ret = validate_range(mm, uffdio_register.range.start, |
| 1339 | uffdio_register.range.len); |
| 1340 | if (ret) |
| 1341 | goto out; |
| 1342 | |
| 1343 | start = uffdio_register.range.start; |
| 1344 | end = start + uffdio_register.range.len; |
| 1345 | |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1346 | ret = -ENOMEM; |
| 1347 | if (!mmget_not_zero(mm)) |
| 1348 | goto out; |
| 1349 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1350 | down_write(&mm->mmap_sem); |
Andrea Arcangeli | 04f5866 | 2019-04-18 17:50:52 -0700 | [diff] [blame] | 1351 | if (!mmget_still_valid(mm)) |
| 1352 | goto out_unlock; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1353 | vma = find_vma_prev(mm, start, &prev); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1354 | if (!vma) |
| 1355 | goto out_unlock; |
| 1356 | |
| 1357 | /* check that there's at least one vma in the range */ |
| 1358 | ret = -EINVAL; |
| 1359 | if (vma->vm_start >= end) |
| 1360 | goto out_unlock; |
| 1361 | |
| 1362 | /* |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 1363 | * If the first vma contains huge pages, make sure start address |
| 1364 | * is aligned to huge page size. |
| 1365 | */ |
| 1366 | if (is_vm_hugetlb_page(vma)) { |
| 1367 | unsigned long vma_hpagesize = vma_kernel_pagesize(vma); |
| 1368 | |
| 1369 | if (start & (vma_hpagesize - 1)) |
| 1370 | goto out_unlock; |
| 1371 | } |
| 1372 | |
| 1373 | /* |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1374 | * Search for not compatible vmas. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1375 | */ |
| 1376 | found = false; |
Mike Rapoport | ce53e8e | 2017-09-06 16:23:12 -0700 | [diff] [blame] | 1377 | basic_ioctls = false; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1378 | for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { |
| 1379 | cond_resched(); |
| 1380 | |
| 1381 | BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ |
| 1382 | !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); |
| 1383 | |
| 1384 | /* check not compatible vmas */ |
| 1385 | ret = -EINVAL; |
Mike Rapoport | ba6907d | 2017-02-22 15:43:22 -0800 | [diff] [blame] | 1386 | if (!vma_can_userfault(cur)) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1387 | goto out_unlock; |
Andrea Arcangeli | 29ec9066 | 2018-11-30 14:09:32 -0800 | [diff] [blame] | 1388 | |
| 1389 | /* |
| 1390 | * UFFDIO_COPY will fill file holes even without |
| 1391 | * PROT_WRITE. This check enforces that if this is a |
| 1392 | * MAP_SHARED, the process has write permission to the backing |
| 1393 | * file. If VM_MAYWRITE is set it also enforces that on a |
| 1394 | * MAP_SHARED vma: there is no F_WRITE_SEAL and no further |
| 1395 | * F_WRITE_SEAL can be taken until the vma is destroyed. |
| 1396 | */ |
| 1397 | ret = -EPERM; |
| 1398 | if (unlikely(!(cur->vm_flags & VM_MAYWRITE))) |
| 1399 | goto out_unlock; |
| 1400 | |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 1401 | /* |
| 1402 | * If this vma contains ending address, and huge pages |
| 1403 | * check alignment. |
| 1404 | */ |
| 1405 | if (is_vm_hugetlb_page(cur) && end <= cur->vm_end && |
| 1406 | end > cur->vm_start) { |
| 1407 | unsigned long vma_hpagesize = vma_kernel_pagesize(cur); |
| 1408 | |
| 1409 | ret = -EINVAL; |
| 1410 | |
| 1411 | if (end & (vma_hpagesize - 1)) |
| 1412 | goto out_unlock; |
| 1413 | } |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1414 | |
| 1415 | /* |
| 1416 | * Check that this vma isn't already owned by a |
| 1417 | * different userfaultfd. We can't allow more than one |
| 1418 | * userfaultfd to own a single vma simultaneously or we |
| 1419 | * wouldn't know which one to deliver the userfaults to. |
| 1420 | */ |
| 1421 | ret = -EBUSY; |
| 1422 | if (cur->vm_userfaultfd_ctx.ctx && |
| 1423 | cur->vm_userfaultfd_ctx.ctx != ctx) |
| 1424 | goto out_unlock; |
| 1425 | |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 1426 | /* |
| 1427 | * Note vmas containing huge pages |
| 1428 | */ |
Mike Rapoport | ce53e8e | 2017-09-06 16:23:12 -0700 | [diff] [blame] | 1429 | if (is_vm_hugetlb_page(cur)) |
| 1430 | basic_ioctls = true; |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 1431 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1432 | found = true; |
| 1433 | } |
| 1434 | BUG_ON(!found); |
| 1435 | |
| 1436 | if (vma->vm_start < start) |
| 1437 | prev = vma; |
| 1438 | |
| 1439 | ret = 0; |
| 1440 | do { |
| 1441 | cond_resched(); |
| 1442 | |
Mike Rapoport | ba6907d | 2017-02-22 15:43:22 -0800 | [diff] [blame] | 1443 | BUG_ON(!vma_can_userfault(vma)); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1444 | BUG_ON(vma->vm_userfaultfd_ctx.ctx && |
| 1445 | vma->vm_userfaultfd_ctx.ctx != ctx); |
Andrea Arcangeli | 29ec9066 | 2018-11-30 14:09:32 -0800 | [diff] [blame] | 1446 | WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1447 | |
| 1448 | /* |
| 1449 | * Nothing to do: this vma is already registered into this |
| 1450 | * userfaultfd and with the right tracking mode too. |
| 1451 | */ |
| 1452 | if (vma->vm_userfaultfd_ctx.ctx == ctx && |
| 1453 | (vma->vm_flags & vm_flags) == vm_flags) |
| 1454 | goto skip; |
| 1455 | |
| 1456 | if (vma->vm_start > start) |
| 1457 | start = vma->vm_start; |
| 1458 | vma_end = min(end, vma->vm_end); |
| 1459 | |
| 1460 | new_flags = (vma->vm_flags & ~vm_flags) | vm_flags; |
| 1461 | prev = vma_merge(mm, prev, start, vma_end, new_flags, |
| 1462 | vma->anon_vma, vma->vm_file, vma->vm_pgoff, |
| 1463 | vma_policy(vma), |
| 1464 | ((struct vm_userfaultfd_ctx){ ctx })); |
| 1465 | if (prev) { |
| 1466 | vma = prev; |
| 1467 | goto next; |
| 1468 | } |
| 1469 | if (vma->vm_start < start) { |
| 1470 | ret = split_vma(mm, vma, start, 1); |
| 1471 | if (ret) |
| 1472 | break; |
| 1473 | } |
| 1474 | if (vma->vm_end > end) { |
| 1475 | ret = split_vma(mm, vma, end, 0); |
| 1476 | if (ret) |
| 1477 | break; |
| 1478 | } |
| 1479 | next: |
| 1480 | /* |
| 1481 | * In the vma_merge() successful mprotect-like case 8: |
| 1482 | * the next vma was merged into the current one and |
| 1483 | * the current one has not been updated yet. |
| 1484 | */ |
| 1485 | vma->vm_flags = new_flags; |
| 1486 | vma->vm_userfaultfd_ctx.ctx = ctx; |
| 1487 | |
| 1488 | skip: |
| 1489 | prev = vma; |
| 1490 | start = vma->vm_end; |
| 1491 | vma = vma->vm_next; |
| 1492 | } while (vma && vma->vm_start < end); |
| 1493 | out_unlock: |
| 1494 | up_write(&mm->mmap_sem); |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1495 | mmput(mm); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1496 | if (!ret) { |
| 1497 | /* |
| 1498 | * Now that we scanned all vmas we can already tell |
| 1499 | * userland which ioctls methods are guaranteed to |
| 1500 | * succeed on this range. |
| 1501 | */ |
Mike Rapoport | ce53e8e | 2017-09-06 16:23:12 -0700 | [diff] [blame] | 1502 | if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 1503 | UFFD_API_RANGE_IOCTLS, |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1504 | &user_uffdio_register->ioctls)) |
| 1505 | ret = -EFAULT; |
| 1506 | } |
| 1507 | out: |
| 1508 | return ret; |
| 1509 | } |
| 1510 | |
| 1511 | static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, |
| 1512 | unsigned long arg) |
| 1513 | { |
| 1514 | struct mm_struct *mm = ctx->mm; |
| 1515 | struct vm_area_struct *vma, *prev, *cur; |
| 1516 | int ret; |
| 1517 | struct uffdio_range uffdio_unregister; |
| 1518 | unsigned long new_flags; |
| 1519 | bool found; |
| 1520 | unsigned long start, end, vma_end; |
| 1521 | const void __user *buf = (void __user *)arg; |
| 1522 | |
| 1523 | ret = -EFAULT; |
| 1524 | if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) |
| 1525 | goto out; |
| 1526 | |
| 1527 | ret = validate_range(mm, uffdio_unregister.start, |
| 1528 | uffdio_unregister.len); |
| 1529 | if (ret) |
| 1530 | goto out; |
| 1531 | |
| 1532 | start = uffdio_unregister.start; |
| 1533 | end = start + uffdio_unregister.len; |
| 1534 | |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1535 | ret = -ENOMEM; |
| 1536 | if (!mmget_not_zero(mm)) |
| 1537 | goto out; |
| 1538 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1539 | down_write(&mm->mmap_sem); |
Andrea Arcangeli | 04f5866 | 2019-04-18 17:50:52 -0700 | [diff] [blame] | 1540 | if (!mmget_still_valid(mm)) |
| 1541 | goto out_unlock; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1542 | vma = find_vma_prev(mm, start, &prev); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1543 | if (!vma) |
| 1544 | goto out_unlock; |
| 1545 | |
| 1546 | /* check that there's at least one vma in the range */ |
| 1547 | ret = -EINVAL; |
| 1548 | if (vma->vm_start >= end) |
| 1549 | goto out_unlock; |
| 1550 | |
| 1551 | /* |
Mike Kravetz | cab350a | 2017-02-22 15:43:04 -0800 | [diff] [blame] | 1552 | * If the first vma contains huge pages, make sure start address |
| 1553 | * is aligned to huge page size. |
| 1554 | */ |
| 1555 | if (is_vm_hugetlb_page(vma)) { |
| 1556 | unsigned long vma_hpagesize = vma_kernel_pagesize(vma); |
| 1557 | |
| 1558 | if (start & (vma_hpagesize - 1)) |
| 1559 | goto out_unlock; |
| 1560 | } |
| 1561 | |
| 1562 | /* |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1563 | * Search for not compatible vmas. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1564 | */ |
| 1565 | found = false; |
| 1566 | ret = -EINVAL; |
| 1567 | for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { |
| 1568 | cond_resched(); |
| 1569 | |
| 1570 | BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ |
| 1571 | !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); |
| 1572 | |
| 1573 | /* |
| 1574 | * Check not compatible vmas, not strictly required |
| 1575 | * here as not compatible vmas cannot have an |
| 1576 | * userfaultfd_ctx registered on them, but this |
| 1577 | * provides for more strict behavior to notice |
| 1578 | * unregistration errors. |
| 1579 | */ |
Mike Rapoport | ba6907d | 2017-02-22 15:43:22 -0800 | [diff] [blame] | 1580 | if (!vma_can_userfault(cur)) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1581 | goto out_unlock; |
| 1582 | |
| 1583 | found = true; |
| 1584 | } |
| 1585 | BUG_ON(!found); |
| 1586 | |
| 1587 | if (vma->vm_start < start) |
| 1588 | prev = vma; |
| 1589 | |
| 1590 | ret = 0; |
| 1591 | do { |
| 1592 | cond_resched(); |
| 1593 | |
Mike Rapoport | ba6907d | 2017-02-22 15:43:22 -0800 | [diff] [blame] | 1594 | BUG_ON(!vma_can_userfault(vma)); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1595 | |
| 1596 | /* |
| 1597 | * Nothing to do: this vma is already registered into this |
| 1598 | * userfaultfd and with the right tracking mode too. |
| 1599 | */ |
| 1600 | if (!vma->vm_userfaultfd_ctx.ctx) |
| 1601 | goto skip; |
| 1602 | |
Andrea Arcangeli | 01e881f | 2018-12-14 14:17:17 -0800 | [diff] [blame] | 1603 | WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); |
| 1604 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1605 | if (vma->vm_start > start) |
| 1606 | start = vma->vm_start; |
| 1607 | vma_end = min(end, vma->vm_end); |
| 1608 | |
Andrea Arcangeli | 09fa529 | 2017-02-22 15:42:46 -0800 | [diff] [blame] | 1609 | if (userfaultfd_missing(vma)) { |
| 1610 | /* |
| 1611 | * Wake any concurrent pending userfault while |
| 1612 | * we unregister, so they will not hang |
| 1613 | * permanently and it avoids userland to call |
| 1614 | * UFFDIO_WAKE explicitly. |
| 1615 | */ |
| 1616 | struct userfaultfd_wake_range range; |
| 1617 | range.start = start; |
| 1618 | range.len = vma_end - start; |
| 1619 | wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); |
| 1620 | } |
| 1621 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1622 | new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); |
| 1623 | prev = vma_merge(mm, prev, start, vma_end, new_flags, |
| 1624 | vma->anon_vma, vma->vm_file, vma->vm_pgoff, |
| 1625 | vma_policy(vma), |
| 1626 | NULL_VM_UFFD_CTX); |
| 1627 | if (prev) { |
| 1628 | vma = prev; |
| 1629 | goto next; |
| 1630 | } |
| 1631 | if (vma->vm_start < start) { |
| 1632 | ret = split_vma(mm, vma, start, 1); |
| 1633 | if (ret) |
| 1634 | break; |
| 1635 | } |
| 1636 | if (vma->vm_end > end) { |
| 1637 | ret = split_vma(mm, vma, end, 0); |
| 1638 | if (ret) |
| 1639 | break; |
| 1640 | } |
| 1641 | next: |
| 1642 | /* |
| 1643 | * In the vma_merge() successful mprotect-like case 8: |
| 1644 | * the next vma was merged into the current one and |
| 1645 | * the current one has not been updated yet. |
| 1646 | */ |
| 1647 | vma->vm_flags = new_flags; |
| 1648 | vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
| 1649 | |
| 1650 | skip: |
| 1651 | prev = vma; |
| 1652 | start = vma->vm_end; |
| 1653 | vma = vma->vm_next; |
| 1654 | } while (vma && vma->vm_start < end); |
| 1655 | out_unlock: |
| 1656 | up_write(&mm->mmap_sem); |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1657 | mmput(mm); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1658 | out: |
| 1659 | return ret; |
| 1660 | } |
| 1661 | |
| 1662 | /* |
Andrea Arcangeli | ba85c70 | 2015-09-04 15:46:41 -0700 | [diff] [blame] | 1663 | * userfaultfd_wake may be used in combination with the |
| 1664 | * UFFDIO_*_MODE_DONTWAKE to wakeup userfaults in batches. |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1665 | */ |
| 1666 | static int userfaultfd_wake(struct userfaultfd_ctx *ctx, |
| 1667 | unsigned long arg) |
| 1668 | { |
| 1669 | int ret; |
| 1670 | struct uffdio_range uffdio_wake; |
| 1671 | struct userfaultfd_wake_range range; |
| 1672 | const void __user *buf = (void __user *)arg; |
| 1673 | |
| 1674 | ret = -EFAULT; |
| 1675 | if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake))) |
| 1676 | goto out; |
| 1677 | |
| 1678 | ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len); |
| 1679 | if (ret) |
| 1680 | goto out; |
| 1681 | |
| 1682 | range.start = uffdio_wake.start; |
| 1683 | range.len = uffdio_wake.len; |
| 1684 | |
| 1685 | /* |
| 1686 | * len == 0 means wake all and we don't want to wake all here, |
| 1687 | * so check it again to be sure. |
| 1688 | */ |
| 1689 | VM_BUG_ON(!range.len); |
| 1690 | |
| 1691 | wake_userfault(ctx, &range); |
| 1692 | ret = 0; |
| 1693 | |
| 1694 | out: |
| 1695 | return ret; |
| 1696 | } |
| 1697 | |
Andrea Arcangeli | ad465cae | 2015-09-04 15:47:11 -0700 | [diff] [blame] | 1698 | static int userfaultfd_copy(struct userfaultfd_ctx *ctx, |
| 1699 | unsigned long arg) |
| 1700 | { |
| 1701 | __s64 ret; |
| 1702 | struct uffdio_copy uffdio_copy; |
| 1703 | struct uffdio_copy __user *user_uffdio_copy; |
| 1704 | struct userfaultfd_wake_range range; |
| 1705 | |
| 1706 | user_uffdio_copy = (struct uffdio_copy __user *) arg; |
| 1707 | |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 1708 | ret = -EAGAIN; |
| 1709 | if (READ_ONCE(ctx->mmap_changing)) |
| 1710 | goto out; |
| 1711 | |
Andrea Arcangeli | ad465cae | 2015-09-04 15:47:11 -0700 | [diff] [blame] | 1712 | ret = -EFAULT; |
| 1713 | if (copy_from_user(&uffdio_copy, user_uffdio_copy, |
| 1714 | /* don't copy "copy" last field */ |
| 1715 | sizeof(uffdio_copy)-sizeof(__s64))) |
| 1716 | goto out; |
| 1717 | |
| 1718 | ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); |
| 1719 | if (ret) |
| 1720 | goto out; |
| 1721 | /* |
| 1722 | * double check for wraparound just in case. copy_from_user() |
| 1723 | * will later check uffdio_copy.src + uffdio_copy.len to fit |
| 1724 | * in the userland range. |
| 1725 | */ |
| 1726 | ret = -EINVAL; |
| 1727 | if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src) |
| 1728 | goto out; |
| 1729 | if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE) |
| 1730 | goto out; |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1731 | if (mmget_not_zero(ctx->mm)) { |
| 1732 | ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src, |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 1733 | uffdio_copy.len, &ctx->mmap_changing); |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1734 | mmput(ctx->mm); |
Mike Rapoport | 9633318 | 2017-02-24 14:58:31 -0800 | [diff] [blame] | 1735 | } else { |
Mike Rapoport | e86b298 | 2017-08-10 15:24:32 -0700 | [diff] [blame] | 1736 | return -ESRCH; |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1737 | } |
Andrea Arcangeli | ad465cae | 2015-09-04 15:47:11 -0700 | [diff] [blame] | 1738 | if (unlikely(put_user(ret, &user_uffdio_copy->copy))) |
| 1739 | return -EFAULT; |
| 1740 | if (ret < 0) |
| 1741 | goto out; |
| 1742 | BUG_ON(!ret); |
| 1743 | /* len == 0 would wake all */ |
| 1744 | range.len = ret; |
| 1745 | if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) { |
| 1746 | range.start = uffdio_copy.dst; |
| 1747 | wake_userfault(ctx, &range); |
| 1748 | } |
| 1749 | ret = range.len == uffdio_copy.len ? 0 : -EAGAIN; |
| 1750 | out: |
| 1751 | return ret; |
| 1752 | } |
| 1753 | |
| 1754 | static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, |
| 1755 | unsigned long arg) |
| 1756 | { |
| 1757 | __s64 ret; |
| 1758 | struct uffdio_zeropage uffdio_zeropage; |
| 1759 | struct uffdio_zeropage __user *user_uffdio_zeropage; |
| 1760 | struct userfaultfd_wake_range range; |
| 1761 | |
| 1762 | user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg; |
| 1763 | |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 1764 | ret = -EAGAIN; |
| 1765 | if (READ_ONCE(ctx->mmap_changing)) |
| 1766 | goto out; |
| 1767 | |
Andrea Arcangeli | ad465cae | 2015-09-04 15:47:11 -0700 | [diff] [blame] | 1768 | ret = -EFAULT; |
| 1769 | if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage, |
| 1770 | /* don't copy "zeropage" last field */ |
| 1771 | sizeof(uffdio_zeropage)-sizeof(__s64))) |
| 1772 | goto out; |
| 1773 | |
| 1774 | ret = validate_range(ctx->mm, uffdio_zeropage.range.start, |
| 1775 | uffdio_zeropage.range.len); |
| 1776 | if (ret) |
| 1777 | goto out; |
| 1778 | ret = -EINVAL; |
| 1779 | if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE) |
| 1780 | goto out; |
| 1781 | |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1782 | if (mmget_not_zero(ctx->mm)) { |
| 1783 | ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 1784 | uffdio_zeropage.range.len, |
| 1785 | &ctx->mmap_changing); |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1786 | mmput(ctx->mm); |
Mike Rapoport | 9d95aa4 | 2017-08-02 13:32:15 -0700 | [diff] [blame] | 1787 | } else { |
Mike Rapoport | e86b298 | 2017-08-10 15:24:32 -0700 | [diff] [blame] | 1788 | return -ESRCH; |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1789 | } |
Andrea Arcangeli | ad465cae | 2015-09-04 15:47:11 -0700 | [diff] [blame] | 1790 | if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) |
| 1791 | return -EFAULT; |
| 1792 | if (ret < 0) |
| 1793 | goto out; |
| 1794 | /* len == 0 would wake all */ |
| 1795 | BUG_ON(!ret); |
| 1796 | range.len = ret; |
| 1797 | if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) { |
| 1798 | range.start = uffdio_zeropage.range.start; |
| 1799 | wake_userfault(ctx, &range); |
| 1800 | } |
| 1801 | ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN; |
| 1802 | out: |
| 1803 | return ret; |
| 1804 | } |
| 1805 | |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1806 | static inline unsigned int uffd_ctx_features(__u64 user_features) |
| 1807 | { |
| 1808 | /* |
| 1809 | * For the current set of features the bits just coincide |
| 1810 | */ |
| 1811 | return (unsigned int)user_features; |
| 1812 | } |
| 1813 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1814 | /* |
| 1815 | * userland asks for a certain API version and we return which bits |
| 1816 | * and ioctl commands are implemented in this kernel for such API |
| 1817 | * version or -EINVAL if unknown. |
| 1818 | */ |
| 1819 | static int userfaultfd_api(struct userfaultfd_ctx *ctx, |
| 1820 | unsigned long arg) |
| 1821 | { |
| 1822 | struct uffdio_api uffdio_api; |
| 1823 | void __user *buf = (void __user *)arg; |
| 1824 | int ret; |
Andrea Arcangeli | 6560314 | 2017-02-22 15:42:24 -0800 | [diff] [blame] | 1825 | __u64 features; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1826 | |
| 1827 | ret = -EINVAL; |
| 1828 | if (ctx->state != UFFD_STATE_WAIT_API) |
| 1829 | goto out; |
| 1830 | ret = -EFAULT; |
Andrea Arcangeli | a9b85f9 | 2015-09-04 15:46:37 -0700 | [diff] [blame] | 1831 | if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api))) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1832 | goto out; |
Andrea Arcangeli | 6560314 | 2017-02-22 15:42:24 -0800 | [diff] [blame] | 1833 | features = uffdio_api.features; |
| 1834 | if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) { |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1835 | memset(&uffdio_api, 0, sizeof(uffdio_api)); |
| 1836 | if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) |
| 1837 | goto out; |
| 1838 | ret = -EINVAL; |
| 1839 | goto out; |
| 1840 | } |
Andrea Arcangeli | 6560314 | 2017-02-22 15:42:24 -0800 | [diff] [blame] | 1841 | /* report all available features and ioctls to userland */ |
| 1842 | uffdio_api.features = UFFD_API_FEATURES; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1843 | uffdio_api.ioctls = UFFD_API_IOCTLS; |
| 1844 | ret = -EFAULT; |
| 1845 | if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) |
| 1846 | goto out; |
| 1847 | ctx->state = UFFD_STATE_RUNNING; |
Andrea Arcangeli | 6560314 | 2017-02-22 15:42:24 -0800 | [diff] [blame] | 1848 | /* only enable the requested features for this uffd context */ |
| 1849 | ctx->features = uffd_ctx_features(features); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1850 | ret = 0; |
| 1851 | out: |
| 1852 | return ret; |
| 1853 | } |
| 1854 | |
| 1855 | static long userfaultfd_ioctl(struct file *file, unsigned cmd, |
| 1856 | unsigned long arg) |
| 1857 | { |
| 1858 | int ret = -EINVAL; |
| 1859 | struct userfaultfd_ctx *ctx = file->private_data; |
| 1860 | |
Andrea Arcangeli | e6485a4 | 2015-09-04 15:47:15 -0700 | [diff] [blame] | 1861 | if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API) |
| 1862 | return -EINVAL; |
| 1863 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1864 | switch(cmd) { |
| 1865 | case UFFDIO_API: |
| 1866 | ret = userfaultfd_api(ctx, arg); |
| 1867 | break; |
| 1868 | case UFFDIO_REGISTER: |
| 1869 | ret = userfaultfd_register(ctx, arg); |
| 1870 | break; |
| 1871 | case UFFDIO_UNREGISTER: |
| 1872 | ret = userfaultfd_unregister(ctx, arg); |
| 1873 | break; |
| 1874 | case UFFDIO_WAKE: |
| 1875 | ret = userfaultfd_wake(ctx, arg); |
| 1876 | break; |
Andrea Arcangeli | ad465cae | 2015-09-04 15:47:11 -0700 | [diff] [blame] | 1877 | case UFFDIO_COPY: |
| 1878 | ret = userfaultfd_copy(ctx, arg); |
| 1879 | break; |
| 1880 | case UFFDIO_ZEROPAGE: |
| 1881 | ret = userfaultfd_zeropage(ctx, arg); |
| 1882 | break; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1883 | } |
| 1884 | return ret; |
| 1885 | } |
| 1886 | |
| 1887 | #ifdef CONFIG_PROC_FS |
| 1888 | static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f) |
| 1889 | { |
| 1890 | struct userfaultfd_ctx *ctx = f->private_data; |
Ingo Molnar | ac6424b | 2017-06-20 12:06:13 +0200 | [diff] [blame] | 1891 | wait_queue_entry_t *wq; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1892 | unsigned long pending = 0, total = 0; |
| 1893 | |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 1894 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 1895 | list_for_each_entry(wq, &ctx->fault_pending_wqh.head, entry) { |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1896 | pending++; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1897 | total++; |
| 1898 | } |
Ingo Molnar | 2055da9 | 2017-06-20 12:06:46 +0200 | [diff] [blame] | 1899 | list_for_each_entry(wq, &ctx->fault_wqh.head, entry) { |
Andrea Arcangeli | 15b726e | 2015-09-04 15:46:44 -0700 | [diff] [blame] | 1900 | total++; |
| 1901 | } |
Eric Biggers | cbcfa13 | 2019-07-04 15:14:39 -0700 | [diff] [blame] | 1902 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1903 | |
| 1904 | /* |
| 1905 | * If more protocols will be added, there will be all shown |
| 1906 | * separated by a space. Like this: |
| 1907 | * protocols: aa:... bb:... |
| 1908 | */ |
| 1909 | seq_printf(m, "pending:\t%lu\ntotal:\t%lu\nAPI:\t%Lx:%x:%Lx\n", |
Mike Rapoport | 045098e | 2017-04-07 16:04:42 -0700 | [diff] [blame] | 1910 | pending, total, UFFD_API, ctx->features, |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1911 | UFFD_API_IOCTLS|UFFD_API_RANGE_IOCTLS); |
| 1912 | } |
| 1913 | #endif |
| 1914 | |
| 1915 | static const struct file_operations userfaultfd_fops = { |
| 1916 | #ifdef CONFIG_PROC_FS |
| 1917 | .show_fdinfo = userfaultfd_show_fdinfo, |
| 1918 | #endif |
| 1919 | .release = userfaultfd_release, |
| 1920 | .poll = userfaultfd_poll, |
| 1921 | .read = userfaultfd_read, |
| 1922 | .unlocked_ioctl = userfaultfd_ioctl, |
| 1923 | .compat_ioctl = userfaultfd_ioctl, |
| 1924 | .llseek = noop_llseek, |
| 1925 | }; |
| 1926 | |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 1927 | static void init_once_userfaultfd_ctx(void *mem) |
| 1928 | { |
| 1929 | struct userfaultfd_ctx *ctx = (struct userfaultfd_ctx *) mem; |
| 1930 | |
| 1931 | init_waitqueue_head(&ctx->fault_pending_wqh); |
| 1932 | init_waitqueue_head(&ctx->fault_wqh); |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1933 | init_waitqueue_head(&ctx->event_wqh); |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 1934 | init_waitqueue_head(&ctx->fd_wqh); |
Andrea Arcangeli | 2c5b7e1 | 2015-09-04 15:47:23 -0700 | [diff] [blame] | 1935 | seqcount_init(&ctx->refile_seq); |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 1936 | } |
| 1937 | |
Eric Biggers | 284cd24 | 2018-01-31 16:19:48 -0800 | [diff] [blame] | 1938 | SYSCALL_DEFINE1(userfaultfd, int, flags) |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1939 | { |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1940 | struct userfaultfd_ctx *ctx; |
Eric Biggers | 284cd24 | 2018-01-31 16:19:48 -0800 | [diff] [blame] | 1941 | int fd; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1942 | |
Peter Xu | cefdca0 | 2019-05-13 17:16:41 -0700 | [diff] [blame] | 1943 | if (!sysctl_unprivileged_userfaultfd && !capable(CAP_SYS_PTRACE)) |
| 1944 | return -EPERM; |
| 1945 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1946 | BUG_ON(!current->mm); |
| 1947 | |
| 1948 | /* Check the UFFD_* constants for consistency. */ |
| 1949 | BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXEC); |
| 1950 | BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBLOCK); |
| 1951 | |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1952 | if (flags & ~UFFD_SHARED_FCNTL_FLAGS) |
Eric Biggers | 284cd24 | 2018-01-31 16:19:48 -0800 | [diff] [blame] | 1953 | return -EINVAL; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1954 | |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 1955 | ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1956 | if (!ctx) |
Eric Biggers | 284cd24 | 2018-01-31 16:19:48 -0800 | [diff] [blame] | 1957 | return -ENOMEM; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1958 | |
Eric Biggers | ca88042 | 2018-12-28 00:34:43 -0800 | [diff] [blame] | 1959 | refcount_set(&ctx->refcount, 1); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1960 | ctx->flags = flags; |
Pavel Emelyanov | 9cd75c3 | 2017-02-22 15:42:21 -0800 | [diff] [blame] | 1961 | ctx->features = 0; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1962 | ctx->state = UFFD_STATE_WAIT_API; |
| 1963 | ctx->released = false; |
Mike Rapoport | df2cc96 | 2018-06-07 17:09:25 -0700 | [diff] [blame] | 1964 | ctx->mmap_changing = false; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1965 | ctx->mm = current->mm; |
| 1966 | /* prevent the mm struct to be freed */ |
Vegard Nossum | f1f1007 | 2017-02-27 14:30:07 -0800 | [diff] [blame] | 1967 | mmgrab(ctx->mm); |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1968 | |
Eric Biggers | 284cd24 | 2018-01-31 16:19:48 -0800 | [diff] [blame] | 1969 | fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx, |
| 1970 | O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS)); |
| 1971 | if (fd < 0) { |
Oleg Nesterov | d2005e3 | 2016-05-20 16:58:36 -0700 | [diff] [blame] | 1972 | mmdrop(ctx->mm); |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 1973 | kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
Eric Biggers | c03e946 | 2015-09-17 16:01:54 -0700 | [diff] [blame] | 1974 | } |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1975 | return fd; |
Andrea Arcangeli | 86039bd | 2015-09-04 15:46:31 -0700 | [diff] [blame] | 1976 | } |
Andrea Arcangeli | 3004ec9 | 2015-09-04 15:46:48 -0700 | [diff] [blame] | 1977 | |
| 1978 | static int __init userfaultfd_init(void) |
| 1979 | { |
| 1980 | userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache", |
| 1981 | sizeof(struct userfaultfd_ctx), |
| 1982 | 0, |
| 1983 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, |
| 1984 | init_once_userfaultfd_ctx); |
| 1985 | return 0; |
| 1986 | } |
| 1987 | __initcall(userfaultfd_init); |