Blame view
fs/userfaultfd.c
50.5 KB
86039bd3b userfaultfd: add ... |
1 2 3 4 5 6 7 8 9 10 11 12 13 |
/* * fs/userfaultfd.c * * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org> * Copyright (C) 2008-2009 Red Hat, Inc. * Copyright (C) 2015 Red Hat, Inc. * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * * Some part derived from fs/eventfd.c (anon inode setup) and * mm/ksm.c (mm hashing). */ |
9cd75c3cd userfaultfd: non-... |
14 |
#include <linux/list.h> |
86039bd3b userfaultfd: add ... |
15 |
#include <linux/hashtable.h> |
174cd4b1e sched/headers: Pr... |
16 |
#include <linux/sched/signal.h> |
6e84f3152 sched/headers: Pr... |
17 |
#include <linux/sched/mm.h> |
86039bd3b userfaultfd: add ... |
18 19 20 21 22 23 24 25 26 27 28 29 |
#include <linux/mm.h> #include <linux/poll.h> #include <linux/slab.h> #include <linux/seq_file.h> #include <linux/file.h> #include <linux/bug.h> #include <linux/anon_inodes.h> #include <linux/syscalls.h> #include <linux/userfaultfd_k.h> #include <linux/mempolicy.h> #include <linux/ioctl.h> #include <linux/security.h> |
cab350afc userfaultfd: huge... |
30 |
#include <linux/hugetlb.h> |
86039bd3b userfaultfd: add ... |
31 |
|
3004ec9ca userfaultfd: allo... |
32 |
static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly; |
86039bd3b userfaultfd: add ... |
33 34 35 36 |
enum userfaultfd_state { UFFD_STATE_WAIT_API, UFFD_STATE_RUNNING, }; |
3004ec9ca userfaultfd: allo... |
37 38 39 40 |
/* * Start with fault_pending_wqh and fault_wqh so they're more likely * to be in the same cacheline. */ |
86039bd3b userfaultfd: add ... |
41 |
struct userfaultfd_ctx { |
15b726ef0 userfaultfd: opti... |
42 43 44 |
/* waitqueue head for the pending (i.e. not read) userfaults */ wait_queue_head_t fault_pending_wqh; /* waitqueue head for the userfaults */ |
86039bd3b userfaultfd: add ... |
45 46 47 |
wait_queue_head_t fault_wqh; /* waitqueue head for the pseudo fd to wakeup poll/read */ wait_queue_head_t fd_wqh; |
9cd75c3cd userfaultfd: non-... |
48 49 |
/* waitqueue head for events */ wait_queue_head_t event_wqh; |
2c5b7e1be userfaultfd: avoi... |
50 51 |
/* a refile sequence protected by fault_pending_wqh lock */ struct seqcount refile_seq; |
3004ec9ca userfaultfd: allo... |
52 53 |
/* pseudo fd refcounting */ atomic_t refcount; |
86039bd3b userfaultfd: add ... |
54 55 |
/* userfaultfd syscall flags */ unsigned int flags; |
9cd75c3cd userfaultfd: non-... |
56 57 |
/* features requested from the userspace */ unsigned int features; |
86039bd3b userfaultfd: add ... |
58 59 60 61 |
/* state machine */ enum userfaultfd_state state; /* released */ bool released; |
df2cc96e7 userfaultfd: prev... |
62 63 |
/* memory mappings are changing because of non-cooperative event */ bool mmap_changing; |
86039bd3b userfaultfd: add ... |
64 65 66 |
/* mm with one ore more vmas attached to this userfaultfd_ctx */ struct mm_struct *mm; }; |
893e26e61 userfaultfd: non-... |
67 68 69 70 71 |
struct userfaultfd_fork_ctx { struct userfaultfd_ctx *orig; struct userfaultfd_ctx *new; struct list_head list; }; |
897ab3e0c userfaultfd: non-... |
72 73 74 75 76 77 |
struct userfaultfd_unmap_ctx { struct userfaultfd_ctx *ctx; unsigned long start; unsigned long end; struct list_head list; }; |
86039bd3b userfaultfd: add ... |
78 |
struct userfaultfd_wait_queue { |
a9b85f941 userfaultfd: chan... |
79 |
struct uffd_msg msg; |
ac6424b98 sched/wait: Renam... |
80 |
wait_queue_entry_t wq; |
86039bd3b userfaultfd: add ... |
81 |
struct userfaultfd_ctx *ctx; |
15a77c6fe userfaultfd: fix ... |
82 |
bool waken; |
86039bd3b userfaultfd: add ... |
83 84 85 86 87 88 |
}; struct userfaultfd_wake_range { unsigned long start; unsigned long len; }; |
ac6424b98 sched/wait: Renam... |
89 |
static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode, |
86039bd3b userfaultfd: add ... |
90 91 92 93 94 95 96 97 98 |
int wake_flags, void *key) { struct userfaultfd_wake_range *range = key; int ret; struct userfaultfd_wait_queue *uwq; unsigned long start, len; uwq = container_of(wq, struct userfaultfd_wait_queue, wq); ret = 0; |
86039bd3b userfaultfd: add ... |
99 100 101 |
/* len == 0 means wake all */ start = range->start; len = range->len; |
a9b85f941 userfaultfd: chan... |
102 103 |
if (len && (start > uwq->msg.arg.pagefault.address || start + len <= uwq->msg.arg.pagefault.address)) |
86039bd3b userfaultfd: add ... |
104 |
goto out; |
15a77c6fe userfaultfd: fix ... |
105 106 |
WRITE_ONCE(uwq->waken, true); /* |
a9668cd6e locking: Remove s... |
107 108 |
* The Program-Order guarantees provided by the scheduler * ensure uwq->waken is visible before the task is woken. |
15a77c6fe userfaultfd: fix ... |
109 |
*/ |
86039bd3b userfaultfd: add ... |
110 |
ret = wake_up_state(wq->private, mode); |
a9668cd6e locking: Remove s... |
111 |
if (ret) { |
86039bd3b userfaultfd: add ... |
112 113 114 |
/* * Wake only once, autoremove behavior. * |
a9668cd6e locking: Remove s... |
115 116 117 118 119 120 121 |
* After the effect of list_del_init is visible to the other * CPUs, the waitqueue may disappear from under us, see the * !list_empty_careful() in handle_userfault(). * * try_to_wake_up() has an implicit smp_mb(), and the * wq->private is read before calling the extern function * "wake_up_state" (which in turns calls try_to_wake_up). |
86039bd3b userfaultfd: add ... |
122 |
*/ |
2055da973 sched/wait: Disam... |
123 |
list_del_init(&wq->entry); |
a9668cd6e locking: Remove s... |
124 |
} |
86039bd3b userfaultfd: add ... |
125 126 127 128 129 130 131 132 |
out: return ret; } /** * userfaultfd_ctx_get - Acquires a reference to the internal userfaultfd * context. * @ctx: [in] Pointer to the userfaultfd context. |
86039bd3b userfaultfd: add ... |
133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 |
*/ static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx) { if (!atomic_inc_not_zero(&ctx->refcount)) BUG(); } /** * userfaultfd_ctx_put - Releases a reference to the internal userfaultfd * context. * @ctx: [in] Pointer to userfaultfd context. * * The userfaultfd context reference must have been previously acquired either * with userfaultfd_ctx_get() or userfaultfd_ctx_fdget(). */ static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx) { if (atomic_dec_and_test(&ctx->refcount)) { VM_BUG_ON(spin_is_locked(&ctx->fault_pending_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh)); VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fault_wqh)); |
9cd75c3cd userfaultfd: non-... |
155 156 |
VM_BUG_ON(spin_is_locked(&ctx->event_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->event_wqh)); |
86039bd3b userfaultfd: add ... |
157 158 |
VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fd_wqh)); |
d2005e3f4 userfaultfd: don'... |
159 |
mmdrop(ctx->mm); |
3004ec9ca userfaultfd: allo... |
160 |
kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
86039bd3b userfaultfd: add ... |
161 162 |
} } |
a9b85f941 userfaultfd: chan... |
163 |
static inline void msg_init(struct uffd_msg *msg) |
86039bd3b userfaultfd: add ... |
164 |
{ |
a9b85f941 userfaultfd: chan... |
165 166 167 168 169 170 171 172 173 174 |
BUILD_BUG_ON(sizeof(struct uffd_msg) != 32); /* * Must use memset to zero out the paddings or kernel data is * leaked to userland. */ memset(msg, 0, sizeof(struct uffd_msg)); } static inline struct uffd_msg userfault_msg(unsigned long address, unsigned int flags, |
9d4ac9348 userfaultfd: prov... |
175 176 |
unsigned long reason, unsigned int features) |
a9b85f941 userfaultfd: chan... |
177 178 179 180 181 |
{ struct uffd_msg msg; msg_init(&msg); msg.event = UFFD_EVENT_PAGEFAULT; msg.arg.pagefault.address = address; |
86039bd3b userfaultfd: add ... |
182 183 |
if (flags & FAULT_FLAG_WRITE) /* |
a4605a61d userfaultfd: corr... |
184 |
* If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the |
a9b85f941 userfaultfd: chan... |
185 186 187 188 |
* uffdio_api.features and UFFD_PAGEFAULT_FLAG_WRITE * was not set in a UFFD_EVENT_PAGEFAULT, it means it * was a read fault, otherwise if set it means it's * a write fault. |
86039bd3b userfaultfd: add ... |
189 |
*/ |
a9b85f941 userfaultfd: chan... |
190 |
msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WRITE; |
86039bd3b userfaultfd: add ... |
191 192 |
if (reason & VM_UFFD_WP) /* |
a9b85f941 userfaultfd: chan... |
193 194 195 196 197 |
* If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the * uffdio_api.features and UFFD_PAGEFAULT_FLAG_WP was * not set in a UFFD_EVENT_PAGEFAULT, it means it was * a missing fault, otherwise if set it means it's a * write protect fault. |
86039bd3b userfaultfd: add ... |
198 |
*/ |
a9b85f941 userfaultfd: chan... |
199 |
msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WP; |
9d4ac9348 userfaultfd: prov... |
200 |
if (features & UFFD_FEATURE_THREAD_ID) |
a36985d31 userfaultfd: prov... |
201 |
msg.arg.pagefault.feat.ptid = task_pid_vnr(current); |
a9b85f941 userfaultfd: chan... |
202 |
return msg; |
86039bd3b userfaultfd: add ... |
203 |
} |
369cd2121 userfaultfd: huge... |
204 205 206 207 208 209 |
#ifdef CONFIG_HUGETLB_PAGE /* * Same functionality as userfaultfd_must_wait below with modifications for * hugepmd ranges. */ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, |
7868a2087 mm/hugetlb: add s... |
210 |
struct vm_area_struct *vma, |
369cd2121 userfaultfd: huge... |
211 212 213 214 215 |
unsigned long address, unsigned long flags, unsigned long reason) { struct mm_struct *mm = ctx->mm; |
1e2c04362 userfaultfd: huge... |
216 |
pte_t *ptep, pte; |
369cd2121 userfaultfd: huge... |
217 218 219 |
bool ret = true; VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); |
1e2c04362 userfaultfd: huge... |
220 221 222 |
ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); if (!ptep) |
369cd2121 userfaultfd: huge... |
223 224 225 |
goto out; ret = false; |
1e2c04362 userfaultfd: huge... |
226 |
pte = huge_ptep_get(ptep); |
369cd2121 userfaultfd: huge... |
227 228 229 230 231 |
/* * Lockless access: we're in a wait_event so it's ok if it * changes under us. */ |
1e2c04362 userfaultfd: huge... |
232 |
if (huge_pte_none(pte)) |
369cd2121 userfaultfd: huge... |
233 |
ret = true; |
1e2c04362 userfaultfd: huge... |
234 |
if (!huge_pte_write(pte) && (reason & VM_UFFD_WP)) |
369cd2121 userfaultfd: huge... |
235 236 237 238 239 240 |
ret = true; out: return ret; } #else static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, |
7868a2087 mm/hugetlb: add s... |
241 |
struct vm_area_struct *vma, |
369cd2121 userfaultfd: huge... |
242 243 244 245 246 247 248 |
unsigned long address, unsigned long flags, unsigned long reason) { return false; /* should never get here */ } #endif /* CONFIG_HUGETLB_PAGE */ |
86039bd3b userfaultfd: add ... |
249 |
/* |
8d2afd96c userfaultfd: solv... |
250 251 252 253 254 255 256 257 258 259 260 261 262 |
* Verify the pagetables are still not ok after having reigstered into * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any * userfault that has already been resolved, if userfaultfd_read and * UFFDIO_COPY|ZEROPAGE are being run simultaneously on two different * threads. */ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, unsigned long address, unsigned long flags, unsigned long reason) { struct mm_struct *mm = ctx->mm; pgd_t *pgd; |
c2febafc6 mm: convert gener... |
263 |
p4d_t *p4d; |
8d2afd96c userfaultfd: solv... |
264 265 266 267 268 269 270 271 272 273 |
pud_t *pud; pmd_t *pmd, _pmd; pte_t *pte; bool ret = true; VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) goto out; |
c2febafc6 mm: convert gener... |
274 275 276 277 |
p4d = p4d_offset(pgd, address); if (!p4d_present(*p4d)) goto out; pud = pud_offset(p4d, address); |
8d2afd96c userfaultfd: solv... |
278 279 280 281 282 283 284 285 286 287 288 289 |
if (!pud_present(*pud)) goto out; pmd = pmd_offset(pud, address); /* * READ_ONCE must function as a barrier with narrower scope * and it must be equivalent to: * _pmd = *pmd; barrier(); * * This is to deal with the instability (as in * pmd_trans_unstable) of the pmd. */ _pmd = READ_ONCE(*pmd); |
a365ac09d mm, userfaultfd, ... |
290 |
if (pmd_none(_pmd)) |
8d2afd96c userfaultfd: solv... |
291 292 293 |
goto out; ret = false; |
a365ac09d mm, userfaultfd, ... |
294 295 |
if (!pmd_present(_pmd)) goto out; |
8d2afd96c userfaultfd: solv... |
296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 |
if (pmd_trans_huge(_pmd)) goto out; /* * the pmd is stable (as in !pmd_trans_unstable) so we can re-read it * and use the standard pte_offset_map() instead of parsing _pmd. */ pte = pte_offset_map(pmd, address); /* * Lockless access: we're in a wait_event so it's ok if it * changes under us. */ if (pte_none(*pte)) ret = true; pte_unmap(pte); out: return ret; } /* |
86039bd3b userfaultfd: add ... |
317 318 319 320 321 322 323 324 325 326 327 328 329 330 |
* The locking rules involved in returning VM_FAULT_RETRY depending on * FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NOWAIT and * FAULT_FLAG_KILLABLE are not straightforward. The "Caution" * recommendation in __lock_page_or_retry is not an understatement. * * If FAULT_FLAG_ALLOW_RETRY is set, the mmap_sem must be released * before returning VM_FAULT_RETRY only if FAULT_FLAG_RETRY_NOWAIT is * not set. * * If FAULT_FLAG_ALLOW_RETRY is set but FAULT_FLAG_KILLABLE is not * set, VM_FAULT_RETRY can still be returned if and only if there are * fatal_signal_pending()s, and the mmap_sem must be released before * returning it. */ |
2b7403035 mm: Change return... |
331 |
vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) |
86039bd3b userfaultfd: add ... |
332 |
{ |
82b0f8c39 mm: join struct f... |
333 |
struct mm_struct *mm = vmf->vma->vm_mm; |
86039bd3b userfaultfd: add ... |
334 335 |
struct userfaultfd_ctx *ctx; struct userfaultfd_wait_queue uwq; |
2b7403035 mm: Change return... |
336 |
vm_fault_t ret = VM_FAULT_SIGBUS; |
dfa37dc3f userfaultfd: allo... |
337 |
bool must_wait, return_to_userland; |
15a77c6fe userfaultfd: fix ... |
338 |
long blocking_state; |
86039bd3b userfaultfd: add ... |
339 |
|
64c2b2030 userfaultfd: shme... |
340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 |
/* * We don't do userfault handling for the final child pid update. * * We also don't do userfault handling during * coredumping. hugetlbfs has the special * follow_hugetlb_page() to skip missing pages in the * FOLL_DUMP case, anon memory also checks for FOLL_DUMP with * the no_page_table() helper in follow_page_mask(), but the * shmem_vm_ops->fault method is invoked even during * coredumping without mmap_sem and it ends up here. */ if (current->flags & (PF_EXITING|PF_DUMPCORE)) goto out; /* * Coredumping runs without mmap_sem so we can only check that * the mmap_sem is held, if PF_DUMPCORE was not set. */ WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem)); |
82b0f8c39 mm: join struct f... |
359 |
ctx = vmf->vma->vm_userfaultfd_ctx.ctx; |
86039bd3b userfaultfd: add ... |
360 |
if (!ctx) |
ba85c702e userfaultfd: wake... |
361 |
goto out; |
86039bd3b userfaultfd: add ... |
362 363 364 365 366 |
BUG_ON(ctx->mm != mm); VM_BUG_ON(reason & ~(VM_UFFD_MISSING|VM_UFFD_WP)); VM_BUG_ON(!(reason & VM_UFFD_MISSING) ^ !!(reason & VM_UFFD_WP)); |
2d6d6f5a0 mm: userfaultfd: ... |
367 368 |
if (ctx->features & UFFD_FEATURE_SIGBUS) goto out; |
86039bd3b userfaultfd: add ... |
369 370 371 372 373 |
/* * If it's already released don't get it. This avoids to loop * in __get_user_pages if userfaultfd_release waits on the * caller of handle_userfault to release the mmap_sem. */ |
6aa7de059 locking/atomics: ... |
374 |
if (unlikely(READ_ONCE(ctx->released))) { |
656710a60 userfaultfd: non-... |
375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 |
/* * Don't return VM_FAULT_SIGBUS in this case, so a non * cooperative manager can close the uffd after the * last UFFDIO_COPY, without risking to trigger an * involuntary SIGBUS if the process was starting the * userfaultfd while the userfaultfd was still armed * (but after the last UFFDIO_COPY). If the uffd * wasn't already closed when the userfault reached * this point, that would normally be solved by * userfaultfd_must_wait returning 'false'. * * If we were to return VM_FAULT_SIGBUS here, the non * cooperative manager would be instead forced to * always call UFFDIO_UNREGISTER before it can safely * close the uffd. */ ret = VM_FAULT_NOPAGE; |
ba85c702e userfaultfd: wake... |
392 |
goto out; |
656710a60 userfaultfd: non-... |
393 |
} |
86039bd3b userfaultfd: add ... |
394 395 396 397 398 399 400 401 402 403 404 |
/* * Check that we can return VM_FAULT_RETRY. * * NOTE: it should become possible to return VM_FAULT_RETRY * even if FAULT_FLAG_TRIED is set without leading to gup() * -EBUSY failures, if the userfaultfd is to be extended for * VM_UFFD_WP tracking and we intend to arm the userfault * without first stopping userland access to the memory. For * VM_UFFD_MISSING userfaults this is enough for now. */ |
82b0f8c39 mm: join struct f... |
405 |
if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) { |
86039bd3b userfaultfd: add ... |
406 407 408 409 410 |
/* * Validate the invariant that nowait must allow retry * to be sure not to return SIGBUS erroneously on * nowait invocations. */ |
82b0f8c39 mm: join struct f... |
411 |
BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT); |
86039bd3b userfaultfd: add ... |
412 413 414 |
#ifdef CONFIG_DEBUG_VM if (printk_ratelimit()) { printk(KERN_WARNING |
82b0f8c39 mm: join struct f... |
415 416 417 |
"FAULT_FLAG_ALLOW_RETRY missing %x ", vmf->flags); |
86039bd3b userfaultfd: add ... |
418 419 420 |
dump_stack(); } #endif |
ba85c702e userfaultfd: wake... |
421 |
goto out; |
86039bd3b userfaultfd: add ... |
422 423 424 425 426 427 |
} /* * Handle nowait, not much to do other than tell it to retry * and wait. */ |
ba85c702e userfaultfd: wake... |
428 |
ret = VM_FAULT_RETRY; |
82b0f8c39 mm: join struct f... |
429 |
if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) |
ba85c702e userfaultfd: wake... |
430 |
goto out; |
86039bd3b userfaultfd: add ... |
431 432 433 |
/* take the reference before dropping the mmap_sem */ userfaultfd_ctx_get(ctx); |
86039bd3b userfaultfd: add ... |
434 435 |
init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function); uwq.wq.private = current; |
9d4ac9348 userfaultfd: prov... |
436 437 |
uwq.msg = userfault_msg(vmf->address, vmf->flags, reason, ctx->features); |
86039bd3b userfaultfd: add ... |
438 |
uwq.ctx = ctx; |
15a77c6fe userfaultfd: fix ... |
439 |
uwq.waken = false; |
86039bd3b userfaultfd: add ... |
440 |
|
bae473a42 mm: introduce fau... |
441 |
return_to_userland = |
82b0f8c39 mm: join struct f... |
442 |
(vmf->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) == |
dfa37dc3f userfaultfd: allo... |
443 |
(FAULT_FLAG_USER|FAULT_FLAG_KILLABLE); |
15a77c6fe userfaultfd: fix ... |
444 445 |
blocking_state = return_to_userland ? TASK_INTERRUPTIBLE : TASK_KILLABLE; |
dfa37dc3f userfaultfd: allo... |
446 |
|
15b726ef0 userfaultfd: opti... |
447 |
spin_lock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
448 449 450 451 |
/* * After the __add_wait_queue the uwq is visible to userland * through poll/read(). */ |
15b726ef0 userfaultfd: opti... |
452 453 454 455 456 457 |
__add_wait_queue(&ctx->fault_pending_wqh, &uwq.wq); /* * The smp_mb() after __set_current_state prevents the reads * following the spin_unlock to happen before the list_add in * __add_wait_queue. */ |
15a77c6fe userfaultfd: fix ... |
458 |
set_current_state(blocking_state); |
15b726ef0 userfaultfd: opti... |
459 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
460 |
|
369cd2121 userfaultfd: huge... |
461 462 463 464 |
if (!is_vm_hugetlb_page(vmf->vma)) must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, reason); else |
7868a2087 mm/hugetlb: add s... |
465 466 |
must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma, vmf->address, |
369cd2121 userfaultfd: huge... |
467 |
vmf->flags, reason); |
8d2afd96c userfaultfd: solv... |
468 |
up_read(&mm->mmap_sem); |
6aa7de059 locking/atomics: ... |
469 |
if (likely(must_wait && !READ_ONCE(ctx->released) && |
dfa37dc3f userfaultfd: allo... |
470 471 |
(return_to_userland ? !signal_pending(current) : !fatal_signal_pending(current)))) { |
a9a08845e vfs: do bulk POLL... |
472 |
wake_up_poll(&ctx->fd_wqh, EPOLLIN); |
86039bd3b userfaultfd: add ... |
473 |
schedule(); |
ba85c702e userfaultfd: wake... |
474 |
ret |= VM_FAULT_MAJOR; |
15a77c6fe userfaultfd: fix ... |
475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 |
/* * False wakeups can orginate even from rwsem before * up_read() however userfaults will wait either for a * targeted wakeup on the specific uwq waitqueue from * wake_userfault() or for signals or for uffd * release. */ while (!READ_ONCE(uwq.waken)) { /* * This needs the full smp_store_mb() * guarantee as the state write must be * visible to other CPUs before reading * uwq.waken from other CPUs. */ set_current_state(blocking_state); if (READ_ONCE(uwq.waken) || READ_ONCE(ctx->released) || (return_to_userland ? signal_pending(current) : fatal_signal_pending(current))) break; schedule(); } |
ba85c702e userfaultfd: wake... |
498 |
} |
86039bd3b userfaultfd: add ... |
499 |
|
ba85c702e userfaultfd: wake... |
500 |
__set_current_state(TASK_RUNNING); |
15b726ef0 userfaultfd: opti... |
501 |
|
dfa37dc3f userfaultfd: allo... |
502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 |
if (return_to_userland) { if (signal_pending(current) && !fatal_signal_pending(current)) { /* * If we got a SIGSTOP or SIGCONT and this is * a normal userland page fault, just let * userland return so the signal will be * handled and gdb debugging works. The page * fault code immediately after we return from * this function is going to release the * mmap_sem and it's not depending on it * (unlike gup would if we were not to return * VM_FAULT_RETRY). * * If a fatal signal is pending we still take * the streamlined VM_FAULT_RETRY failure path * and there's no need to retake the mmap_sem * in such case. */ down_read(&mm->mmap_sem); |
6bbc4a414 userfaultfd: shme... |
522 |
ret = VM_FAULT_NOPAGE; |
dfa37dc3f userfaultfd: allo... |
523 524 |
} } |
15b726ef0 userfaultfd: opti... |
525 526 527 528 529 530 531 532 533 534 535 536 537 |
/* * Here we race with the list_del; list_add in * userfaultfd_ctx_read(), however because we don't ever run * list_del_init() to refile across the two lists, the prev * and next pointers will never point to self. list_add also * would never let any of the two pointers to point to * self. So list_empty_careful won't risk to see both pointers * pointing to self at any time during the list refile. The * only case where list_del_init() is called is the full * removal in the wake function and there we don't re-list_add * and it's fine not to block on the spinlock. The uwq on this * kernel stack can be released after the list_del_init. */ |
2055da973 sched/wait: Disam... |
538 |
if (!list_empty_careful(&uwq.wq.entry)) { |
15b726ef0 userfaultfd: opti... |
539 540 541 542 543 |
spin_lock(&ctx->fault_pending_wqh.lock); /* * No need of list_del_init(), the uwq on the stack * will be freed shortly anyway. */ |
2055da973 sched/wait: Disam... |
544 |
list_del(&uwq.wq.entry); |
15b726ef0 userfaultfd: opti... |
545 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
546 |
} |
86039bd3b userfaultfd: add ... |
547 548 549 550 551 552 |
/* * ctx may go away after this if the userfault pseudo fd is * already released. */ userfaultfd_ctx_put(ctx); |
ba85c702e userfaultfd: wake... |
553 554 |
out: return ret; |
86039bd3b userfaultfd: add ... |
555 |
} |
8c9e7bb7a userfaultfd: non-... |
556 557 |
static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx, struct userfaultfd_wait_queue *ewq) |
9cd75c3cd userfaultfd: non-... |
558 |
{ |
0cbb4b4f4 userfaultfd: clea... |
559 |
struct userfaultfd_ctx *release_new_ctx; |
9a69a829f userfaultfd: non-... |
560 561 |
if (WARN_ON_ONCE(current->flags & PF_EXITING)) goto out; |
9cd75c3cd userfaultfd: non-... |
562 563 564 |
ewq->ctx = ctx; init_waitqueue_entry(&ewq->wq, current); |
0cbb4b4f4 userfaultfd: clea... |
565 |
release_new_ctx = NULL; |
9cd75c3cd userfaultfd: non-... |
566 567 568 569 570 571 572 573 574 575 576 |
spin_lock(&ctx->event_wqh.lock); /* * After the __add_wait_queue the uwq is visible to userland * through poll/read(). */ __add_wait_queue(&ctx->event_wqh, &ewq->wq); for (;;) { set_current_state(TASK_KILLABLE); if (ewq->msg.event == 0) break; |
6aa7de059 locking/atomics: ... |
577 |
if (READ_ONCE(ctx->released) || |
9cd75c3cd userfaultfd: non-... |
578 |
fatal_signal_pending(current)) { |
384632e67 userfaultfd: non-... |
579 580 581 582 583 584 |
/* * &ewq->wq may be queued in fork_event, but * __remove_wait_queue ignores the head * parameter. It would be a problem if it * didn't. */ |
9cd75c3cd userfaultfd: non-... |
585 |
__remove_wait_queue(&ctx->event_wqh, &ewq->wq); |
7eb76d457 userfaultfd: non-... |
586 587 588 589 590 591 |
if (ewq->msg.event == UFFD_EVENT_FORK) { struct userfaultfd_ctx *new; new = (struct userfaultfd_ctx *) (unsigned long) ewq->msg.arg.reserved.reserved1; |
0cbb4b4f4 userfaultfd: clea... |
592 |
release_new_ctx = new; |
7eb76d457 userfaultfd: non-... |
593 |
} |
9cd75c3cd userfaultfd: non-... |
594 595 596 597 |
break; } spin_unlock(&ctx->event_wqh.lock); |
a9a08845e vfs: do bulk POLL... |
598 |
wake_up_poll(&ctx->fd_wqh, EPOLLIN); |
9cd75c3cd userfaultfd: non-... |
599 600 601 602 603 604 |
schedule(); spin_lock(&ctx->event_wqh.lock); } __set_current_state(TASK_RUNNING); spin_unlock(&ctx->event_wqh.lock); |
0cbb4b4f4 userfaultfd: clea... |
605 606 607 608 609 610 611 |
if (release_new_ctx) { struct vm_area_struct *vma; struct mm_struct *mm = release_new_ctx->mm; /* the various vma->vm_userfaultfd_ctx still points to it */ down_write(&mm->mmap_sem); for (vma = mm->mmap; vma; vma = vma->vm_next) |
31e810aa1 userfaultfd: remo... |
612 |
if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) { |
0cbb4b4f4 userfaultfd: clea... |
613 |
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
31e810aa1 userfaultfd: remo... |
614 615 |
vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); } |
0cbb4b4f4 userfaultfd: clea... |
616 617 618 619 |
up_write(&mm->mmap_sem); userfaultfd_ctx_put(release_new_ctx); } |
9cd75c3cd userfaultfd: non-... |
620 621 622 623 |
/* * ctx may go away after this if the userfault pseudo fd is * already released. */ |
9a69a829f userfaultfd: non-... |
624 |
out: |
df2cc96e7 userfaultfd: prev... |
625 |
WRITE_ONCE(ctx->mmap_changing, false); |
9cd75c3cd userfaultfd: non-... |
626 |
userfaultfd_ctx_put(ctx); |
9cd75c3cd userfaultfd: non-... |
627 628 629 630 631 632 633 634 635 |
} static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx, struct userfaultfd_wait_queue *ewq) { ewq->msg.event = 0; wake_up_locked(&ctx->event_wqh); __remove_wait_queue(&ctx->event_wqh, &ewq->wq); } |
893e26e61 userfaultfd: non-... |
636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 |
int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs) { struct userfaultfd_ctx *ctx = NULL, *octx; struct userfaultfd_fork_ctx *fctx; octx = vma->vm_userfaultfd_ctx.ctx; if (!octx || !(octx->features & UFFD_FEATURE_EVENT_FORK)) { vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); return 0; } list_for_each_entry(fctx, fcs, list) if (fctx->orig == octx) { ctx = fctx->new; break; } if (!ctx) { fctx = kmalloc(sizeof(*fctx), GFP_KERNEL); if (!fctx) return -ENOMEM; ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); if (!ctx) { kfree(fctx); return -ENOMEM; } atomic_set(&ctx->refcount, 1); ctx->flags = octx->flags; ctx->state = UFFD_STATE_RUNNING; ctx->features = octx->features; ctx->released = false; |
df2cc96e7 userfaultfd: prev... |
670 |
ctx->mmap_changing = false; |
893e26e61 userfaultfd: non-... |
671 |
ctx->mm = vma->vm_mm; |
00bb31fa4 userfaultfd: use ... |
672 |
mmgrab(ctx->mm); |
893e26e61 userfaultfd: non-... |
673 674 |
userfaultfd_ctx_get(octx); |
df2cc96e7 userfaultfd: prev... |
675 |
WRITE_ONCE(octx->mmap_changing, true); |
893e26e61 userfaultfd: non-... |
676 677 678 679 680 681 682 683 |
fctx->orig = octx; fctx->new = ctx; list_add_tail(&fctx->list, fcs); } vma->vm_userfaultfd_ctx.ctx = ctx; return 0; } |
8c9e7bb7a userfaultfd: non-... |
684 |
static void dup_fctx(struct userfaultfd_fork_ctx *fctx) |
893e26e61 userfaultfd: non-... |
685 686 687 688 689 690 691 692 |
{ struct userfaultfd_ctx *ctx = fctx->orig; struct userfaultfd_wait_queue ewq; msg_init(&ewq.msg); ewq.msg.event = UFFD_EVENT_FORK; ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new; |
8c9e7bb7a userfaultfd: non-... |
693 |
userfaultfd_event_wait_completion(ctx, &ewq); |
893e26e61 userfaultfd: non-... |
694 695 696 697 |
} void dup_userfaultfd_complete(struct list_head *fcs) { |
893e26e61 userfaultfd: non-... |
698 699 700 |
struct userfaultfd_fork_ctx *fctx, *n; list_for_each_entry_safe(fctx, n, fcs, list) { |
8c9e7bb7a userfaultfd: non-... |
701 |
dup_fctx(fctx); |
893e26e61 userfaultfd: non-... |
702 703 704 705 |
list_del(&fctx->list); kfree(fctx); } } |
72f87654c userfaultfd: non-... |
706 707 708 709 710 711 |
void mremap_userfaultfd_prep(struct vm_area_struct *vma, struct vm_userfaultfd_ctx *vm_ctx) { struct userfaultfd_ctx *ctx; ctx = vma->vm_userfaultfd_ctx.ctx; |
2011eb741 userfaultfd: clea... |
712 713 714 715 716 |
if (!ctx) return; if (ctx->features & UFFD_FEATURE_EVENT_REMAP) { |
72f87654c userfaultfd: non-... |
717 718 |
vm_ctx->ctx = ctx; userfaultfd_ctx_get(ctx); |
df2cc96e7 userfaultfd: prev... |
719 |
WRITE_ONCE(ctx->mmap_changing, true); |
2011eb741 userfaultfd: clea... |
720 721 722 723 |
} else { /* Drop uffd context if remap feature not enabled */ vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); |
72f87654c userfaultfd: non-... |
724 725 |
} } |
90794bf19 userfaultfd: non-... |
726 |
void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx, |
72f87654c userfaultfd: non-... |
727 728 729 |
unsigned long from, unsigned long to, unsigned long len) { |
90794bf19 userfaultfd: non-... |
730 |
struct userfaultfd_ctx *ctx = vm_ctx->ctx; |
72f87654c userfaultfd: non-... |
731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 |
struct userfaultfd_wait_queue ewq; if (!ctx) return; if (to & ~PAGE_MASK) { userfaultfd_ctx_put(ctx); return; } msg_init(&ewq.msg); ewq.msg.event = UFFD_EVENT_REMAP; ewq.msg.arg.remap.from = from; ewq.msg.arg.remap.to = to; ewq.msg.arg.remap.len = len; userfaultfd_event_wait_completion(ctx, &ewq); } |
70ccb92fd userfaultfd: non-... |
750 |
bool userfaultfd_remove(struct vm_area_struct *vma, |
d811914d8 userfaultfd: non-... |
751 |
unsigned long start, unsigned long end) |
05ce77249 userfaultfd: non-... |
752 753 754 755 756 757 |
{ struct mm_struct *mm = vma->vm_mm; struct userfaultfd_ctx *ctx; struct userfaultfd_wait_queue ewq; ctx = vma->vm_userfaultfd_ctx.ctx; |
d811914d8 userfaultfd: non-... |
758 |
if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_REMOVE)) |
70ccb92fd userfaultfd: non-... |
759 |
return true; |
05ce77249 userfaultfd: non-... |
760 761 |
userfaultfd_ctx_get(ctx); |
df2cc96e7 userfaultfd: prev... |
762 |
WRITE_ONCE(ctx->mmap_changing, true); |
05ce77249 userfaultfd: non-... |
763 |
up_read(&mm->mmap_sem); |
05ce77249 userfaultfd: non-... |
764 |
msg_init(&ewq.msg); |
d811914d8 userfaultfd: non-... |
765 766 767 |
ewq.msg.event = UFFD_EVENT_REMOVE; ewq.msg.arg.remove.start = start; ewq.msg.arg.remove.end = end; |
05ce77249 userfaultfd: non-... |
768 769 |
userfaultfd_event_wait_completion(ctx, &ewq); |
70ccb92fd userfaultfd: non-... |
770 |
return false; |
05ce77249 userfaultfd: non-... |
771 |
} |
897ab3e0c userfaultfd: non-... |
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 |
static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps, unsigned long start, unsigned long end) { struct userfaultfd_unmap_ctx *unmap_ctx; list_for_each_entry(unmap_ctx, unmaps, list) if (unmap_ctx->ctx == ctx && unmap_ctx->start == start && unmap_ctx->end == end) return true; return false; } int userfaultfd_unmap_prep(struct vm_area_struct *vma, unsigned long start, unsigned long end, struct list_head *unmaps) { for ( ; vma && vma->vm_start < end; vma = vma->vm_next) { struct userfaultfd_unmap_ctx *unmap_ctx; struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) || has_unmap_ctx(ctx, unmaps, start, end)) continue; unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL); if (!unmap_ctx) return -ENOMEM; userfaultfd_ctx_get(ctx); |
df2cc96e7 userfaultfd: prev... |
802 |
WRITE_ONCE(ctx->mmap_changing, true); |
897ab3e0c userfaultfd: non-... |
803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 |
unmap_ctx->ctx = ctx; unmap_ctx->start = start; unmap_ctx->end = end; list_add_tail(&unmap_ctx->list, unmaps); } return 0; } void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf) { struct userfaultfd_unmap_ctx *ctx, *n; struct userfaultfd_wait_queue ewq; list_for_each_entry_safe(ctx, n, uf, list) { msg_init(&ewq.msg); ewq.msg.event = UFFD_EVENT_UNMAP; ewq.msg.arg.remove.start = ctx->start; ewq.msg.arg.remove.end = ctx->end; userfaultfd_event_wait_completion(ctx->ctx, &ewq); list_del(&ctx->list); kfree(ctx); } } |
86039bd3b userfaultfd: add ... |
830 831 832 833 834 835 836 837 |
static int userfaultfd_release(struct inode *inode, struct file *file) { struct userfaultfd_ctx *ctx = file->private_data; struct mm_struct *mm = ctx->mm; struct vm_area_struct *vma, *prev; /* len == 0 means wake all */ struct userfaultfd_wake_range range = { .len = 0, }; unsigned long new_flags; |
6aa7de059 locking/atomics: ... |
838 |
WRITE_ONCE(ctx->released, true); |
86039bd3b userfaultfd: add ... |
839 |
|
d2005e3f4 userfaultfd: don'... |
840 841 |
if (!mmget_not_zero(mm)) goto wakeup; |
86039bd3b userfaultfd: add ... |
842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 |
/* * Flush page faults out of all CPUs. NOTE: all page faults * must be retried without returning VM_FAULT_SIGBUS if * userfaultfd_ctx_get() succeeds but vma->vma_userfault_ctx * changes while handle_userfault released the mmap_sem. So * it's critical that released is set to true (above), before * taking the mmap_sem for writing. */ down_write(&mm->mmap_sem); prev = NULL; for (vma = mm->mmap; vma; vma = vma->vm_next) { cond_resched(); BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^ !!(vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); if (vma->vm_userfaultfd_ctx.ctx != ctx) { prev = vma; continue; } new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), NULL_VM_UFFD_CTX); if (prev) vma = prev; else prev = vma; vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; } up_write(&mm->mmap_sem); |
d2005e3f4 userfaultfd: don'... |
874 875 |
mmput(mm); wakeup: |
86039bd3b userfaultfd: add ... |
876 |
/* |
15b726ef0 userfaultfd: opti... |
877 |
* After no new page faults can wait on this fault_*wqh, flush |
86039bd3b userfaultfd: add ... |
878 |
* the last page faults that may have been already waiting on |
15b726ef0 userfaultfd: opti... |
879 |
* the fault_*wqh. |
86039bd3b userfaultfd: add ... |
880 |
*/ |
15b726ef0 userfaultfd: opti... |
881 |
spin_lock(&ctx->fault_pending_wqh.lock); |
ac5be6b47 userfaultfd: reve... |
882 |
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range); |
c430d1e84 userfaultfd: use ... |
883 |
__wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range); |
15b726ef0 userfaultfd: opti... |
884 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
885 |
|
5a18b64e3 userfaultfd: non-... |
886 887 |
/* Flush pending events that may still wait on event_wqh */ wake_up_all(&ctx->event_wqh); |
a9a08845e vfs: do bulk POLL... |
888 |
wake_up_poll(&ctx->fd_wqh, EPOLLHUP); |
86039bd3b userfaultfd: add ... |
889 890 891 |
userfaultfd_ctx_put(ctx); return 0; } |
15b726ef0 userfaultfd: opti... |
892 |
/* fault_pending_wqh.lock must be hold by the caller */ |
6dcc27fd3 userfaultfd: non-... |
893 894 |
static inline struct userfaultfd_wait_queue *find_userfault_in( wait_queue_head_t *wqh) |
86039bd3b userfaultfd: add ... |
895 |
{ |
ac6424b98 sched/wait: Renam... |
896 |
wait_queue_entry_t *wq; |
15b726ef0 userfaultfd: opti... |
897 |
struct userfaultfd_wait_queue *uwq; |
86039bd3b userfaultfd: add ... |
898 |
|
6dcc27fd3 userfaultfd: non-... |
899 |
VM_BUG_ON(!spin_is_locked(&wqh->lock)); |
86039bd3b userfaultfd: add ... |
900 |
|
15b726ef0 userfaultfd: opti... |
901 |
uwq = NULL; |
6dcc27fd3 userfaultfd: non-... |
902 |
if (!waitqueue_active(wqh)) |
15b726ef0 userfaultfd: opti... |
903 904 |
goto out; /* walk in reverse to provide FIFO behavior to read userfaults */ |
2055da973 sched/wait: Disam... |
905 |
wq = list_last_entry(&wqh->head, typeof(*wq), entry); |
15b726ef0 userfaultfd: opti... |
906 907 908 |
uwq = container_of(wq, struct userfaultfd_wait_queue, wq); out: return uwq; |
86039bd3b userfaultfd: add ... |
909 |
} |
6dcc27fd3 userfaultfd: non-... |
910 911 912 913 914 915 |
static inline struct userfaultfd_wait_queue *find_userfault( struct userfaultfd_ctx *ctx) { return find_userfault_in(&ctx->fault_pending_wqh); } |
86039bd3b userfaultfd: add ... |
916 |
|
9cd75c3cd userfaultfd: non-... |
917 918 919 920 921 |
static inline struct userfaultfd_wait_queue *find_userfault_evt( struct userfaultfd_ctx *ctx) { return find_userfault_in(&ctx->event_wqh); } |
076ccb76e fs: annotate ->po... |
922 |
static __poll_t userfaultfd_poll(struct file *file, poll_table *wait) |
86039bd3b userfaultfd: add ... |
923 924 |
{ struct userfaultfd_ctx *ctx = file->private_data; |
076ccb76e fs: annotate ->po... |
925 |
__poll_t ret; |
86039bd3b userfaultfd: add ... |
926 927 928 929 930 |
poll_wait(file, &ctx->fd_wqh, wait); switch (ctx->state) { case UFFD_STATE_WAIT_API: |
a9a08845e vfs: do bulk POLL... |
931 |
return EPOLLERR; |
86039bd3b userfaultfd: add ... |
932 |
case UFFD_STATE_RUNNING: |
ba85c702e userfaultfd: wake... |
933 934 935 936 937 |
/* * poll() never guarantees that read won't block. * userfaults can be waken before they're read(). */ if (unlikely(!(file->f_flags & O_NONBLOCK))) |
a9a08845e vfs: do bulk POLL... |
938 |
return EPOLLERR; |
15b726ef0 userfaultfd: opti... |
939 940 941 942 943 944 945 946 947 948 949 950 951 |
/* * lockless access to see if there are pending faults * __pollwait last action is the add_wait_queue but * the spin_unlock would allow the waitqueue_active to * pass above the actual list_add inside * add_wait_queue critical section. So use a full * memory barrier to serialize the list_add write of * add_wait_queue() with the waitqueue_active read * below. */ ret = 0; smp_mb(); if (waitqueue_active(&ctx->fault_pending_wqh)) |
a9a08845e vfs: do bulk POLL... |
952 |
ret = EPOLLIN; |
9cd75c3cd userfaultfd: non-... |
953 |
else if (waitqueue_active(&ctx->event_wqh)) |
a9a08845e vfs: do bulk POLL... |
954 |
ret = EPOLLIN; |
9cd75c3cd userfaultfd: non-... |
955 |
|
86039bd3b userfaultfd: add ... |
956 957 |
return ret; default: |
8474901a3 userfaultfd: conv... |
958 |
WARN_ON_ONCE(1); |
a9a08845e vfs: do bulk POLL... |
959 |
return EPOLLERR; |
86039bd3b userfaultfd: add ... |
960 961 |
} } |
893e26e61 userfaultfd: non-... |
962 963 964 965 966 967 968 |
static const struct file_operations userfaultfd_fops; static int resolve_userfault_fork(struct userfaultfd_ctx *ctx, struct userfaultfd_ctx *new, struct uffd_msg *msg) { int fd; |
893e26e61 userfaultfd: non-... |
969 |
|
284cd241a userfaultfd: conv... |
970 971 |
fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new, O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS)); |
893e26e61 userfaultfd: non-... |
972 973 |
if (fd < 0) return fd; |
893e26e61 userfaultfd: non-... |
974 975 |
msg->arg.reserved.reserved1 = 0; msg->arg.fork.ufd = fd; |
893e26e61 userfaultfd: non-... |
976 977 |
return 0; } |
86039bd3b userfaultfd: add ... |
978 |
static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, |
a9b85f941 userfaultfd: chan... |
979 |
struct uffd_msg *msg) |
86039bd3b userfaultfd: add ... |
980 981 982 |
{ ssize_t ret; DECLARE_WAITQUEUE(wait, current); |
15b726ef0 userfaultfd: opti... |
983 |
struct userfaultfd_wait_queue *uwq; |
893e26e61 userfaultfd: non-... |
984 985 986 987 988 989 990 991 992 |
/* * Handling fork event requires sleeping operations, so * we drop the event_wqh lock, then do these ops, then * lock it back and wake up the waiter. While the lock is * dropped the ewq may go away so we keep track of it * carefully. */ LIST_HEAD(fork_event); struct userfaultfd_ctx *fork_nctx = NULL; |
86039bd3b userfaultfd: add ... |
993 |
|
15b726ef0 userfaultfd: opti... |
994 |
/* always take the fd_wqh lock before the fault_pending_wqh lock */ |
d2e97f026 userfaultfd: disa... |
995 |
spin_lock_irq(&ctx->fd_wqh.lock); |
86039bd3b userfaultfd: add ... |
996 997 998 |
__add_wait_queue(&ctx->fd_wqh, &wait); for (;;) { set_current_state(TASK_INTERRUPTIBLE); |
15b726ef0 userfaultfd: opti... |
999 1000 1001 |
spin_lock(&ctx->fault_pending_wqh.lock); uwq = find_userfault(ctx); if (uwq) { |
86039bd3b userfaultfd: add ... |
1002 |
/* |
2c5b7e1be userfaultfd: avoi... |
1003 1004 1005 1006 1007 1008 1009 1010 1011 |
* Use a seqcount to repeat the lockless check * in wake_userfault() to avoid missing * wakeups because during the refile both * waitqueue could become empty if this is the * only userfault. */ write_seqcount_begin(&ctx->refile_seq); /* |
15b726ef0 userfaultfd: opti... |
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 |
* The fault_pending_wqh.lock prevents the uwq * to disappear from under us. * * Refile this userfault from * fault_pending_wqh to fault_wqh, it's not * pending anymore after we read it. * * Use list_del() by hand (as * userfaultfd_wake_function also uses * list_del_init() by hand) to be sure nobody * changes __remove_wait_queue() to use * list_del_init() in turn breaking the * !list_empty_careful() check in |
2055da973 sched/wait: Disam... |
1025 |
* handle_userfault(). The uwq->wq.head list |
15b726ef0 userfaultfd: opti... |
1026 1027 1028 1029 1030 |
* must never be empty at any time during the * refile, or the waitqueue could disappear * from under us. The "wait_queue_head_t" * parameter of __remove_wait_queue() is unused * anyway. |
86039bd3b userfaultfd: add ... |
1031 |
*/ |
2055da973 sched/wait: Disam... |
1032 |
list_del(&uwq->wq.entry); |
c430d1e84 userfaultfd: use ... |
1033 |
add_wait_queue(&ctx->fault_wqh, &uwq->wq); |
15b726ef0 userfaultfd: opti... |
1034 |
|
2c5b7e1be userfaultfd: avoi... |
1035 |
write_seqcount_end(&ctx->refile_seq); |
a9b85f941 userfaultfd: chan... |
1036 1037 |
/* careful to always initialize msg if ret == 0 */ *msg = uwq->msg; |
15b726ef0 userfaultfd: opti... |
1038 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1039 1040 1041 |
ret = 0; break; } |
15b726ef0 userfaultfd: opti... |
1042 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
9cd75c3cd userfaultfd: non-... |
1043 1044 1045 1046 1047 |
spin_lock(&ctx->event_wqh.lock); uwq = find_userfault_evt(ctx); if (uwq) { *msg = uwq->msg; |
893e26e61 userfaultfd: non-... |
1048 1049 1050 1051 |
if (uwq->msg.event == UFFD_EVENT_FORK) { fork_nctx = (struct userfaultfd_ctx *) (unsigned long) uwq->msg.arg.reserved.reserved1; |
2055da973 sched/wait: Disam... |
1052 |
list_move(&uwq->wq.entry, &fork_event); |
384632e67 userfaultfd: non-... |
1053 1054 1055 1056 1057 1058 |
/* * fork_nctx can be freed as soon as * we drop the lock, unless we take a * reference on it. */ userfaultfd_ctx_get(fork_nctx); |
893e26e61 userfaultfd: non-... |
1059 1060 1061 1062 |
spin_unlock(&ctx->event_wqh.lock); ret = 0; break; } |
9cd75c3cd userfaultfd: non-... |
1063 1064 1065 1066 1067 1068 |
userfaultfd_event_complete(ctx, uwq); spin_unlock(&ctx->event_wqh.lock); ret = 0; break; } spin_unlock(&ctx->event_wqh.lock); |
86039bd3b userfaultfd: add ... |
1069 1070 1071 1072 1073 1074 1075 1076 |
if (signal_pending(current)) { ret = -ERESTARTSYS; break; } if (no_wait) { ret = -EAGAIN; break; } |
d2e97f026 userfaultfd: disa... |
1077 |
spin_unlock_irq(&ctx->fd_wqh.lock); |
86039bd3b userfaultfd: add ... |
1078 |
schedule(); |
d2e97f026 userfaultfd: disa... |
1079 |
spin_lock_irq(&ctx->fd_wqh.lock); |
86039bd3b userfaultfd: add ... |
1080 1081 1082 |
} __remove_wait_queue(&ctx->fd_wqh, &wait); __set_current_state(TASK_RUNNING); |
d2e97f026 userfaultfd: disa... |
1083 |
spin_unlock_irq(&ctx->fd_wqh.lock); |
86039bd3b userfaultfd: add ... |
1084 |
|
893e26e61 userfaultfd: non-... |
1085 1086 |
if (!ret && msg->event == UFFD_EVENT_FORK) { ret = resolve_userfault_fork(ctx, fork_nctx, msg); |
384632e67 userfaultfd: non-... |
1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 |
spin_lock(&ctx->event_wqh.lock); if (!list_empty(&fork_event)) { /* * The fork thread didn't abort, so we can * drop the temporary refcount. */ userfaultfd_ctx_put(fork_nctx); uwq = list_first_entry(&fork_event, typeof(*uwq), wq.entry); /* * If fork_event list wasn't empty and in turn * the event wasn't already released by fork * (the event is allocated on fork kernel * stack), put the event back to its place in * the event_wq. fork_event head will be freed * as soon as we return so the event cannot * stay queued there no matter the current * "ret" value. */ list_del(&uwq->wq.entry); __add_wait_queue(&ctx->event_wqh, &uwq->wq); |
893e26e61 userfaultfd: non-... |
1110 |
|
384632e67 userfaultfd: non-... |
1111 1112 1113 1114 1115 1116 |
/* * Leave the event in the waitqueue and report * error to userland if we failed to resolve * the userfault fork. */ if (likely(!ret)) |
893e26e61 userfaultfd: non-... |
1117 |
userfaultfd_event_complete(ctx, uwq); |
384632e67 userfaultfd: non-... |
1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 |
} else { /* * Here the fork thread aborted and the * refcount from the fork thread on fork_nctx * has already been released. We still hold * the reference we took before releasing the * lock above. If resolve_userfault_fork * failed we've to drop it because the * fork_nctx has to be freed in such case. If * it succeeded we'll hold it because the new * uffd references it. */ if (ret) userfaultfd_ctx_put(fork_nctx); |
893e26e61 userfaultfd: non-... |
1132 |
} |
384632e67 userfaultfd: non-... |
1133 |
spin_unlock(&ctx->event_wqh.lock); |
893e26e61 userfaultfd: non-... |
1134 |
} |
86039bd3b userfaultfd: add ... |
1135 1136 1137 1138 1139 1140 1141 1142 |
return ret; } static ssize_t userfaultfd_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct userfaultfd_ctx *ctx = file->private_data; ssize_t _ret, ret = 0; |
a9b85f941 userfaultfd: chan... |
1143 |
struct uffd_msg msg; |
86039bd3b userfaultfd: add ... |
1144 1145 1146 1147 |
int no_wait = file->f_flags & O_NONBLOCK; if (ctx->state == UFFD_STATE_WAIT_API) return -EINVAL; |
86039bd3b userfaultfd: add ... |
1148 1149 |
for (;;) { |
a9b85f941 userfaultfd: chan... |
1150 |
if (count < sizeof(msg)) |
86039bd3b userfaultfd: add ... |
1151 |
return ret ? ret : -EINVAL; |
a9b85f941 userfaultfd: chan... |
1152 |
_ret = userfaultfd_ctx_read(ctx, no_wait, &msg); |
86039bd3b userfaultfd: add ... |
1153 1154 |
if (_ret < 0) return ret ? ret : _ret; |
a9b85f941 userfaultfd: chan... |
1155 |
if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg))) |
86039bd3b userfaultfd: add ... |
1156 |
return ret ? ret : -EFAULT; |
a9b85f941 userfaultfd: chan... |
1157 1158 1159 |
ret += sizeof(msg); buf += sizeof(msg); count -= sizeof(msg); |
86039bd3b userfaultfd: add ... |
1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 |
/* * Allow to read more than one fault at time but only * block if waiting for the very first one. */ no_wait = O_NONBLOCK; } } static void __wake_userfault(struct userfaultfd_ctx *ctx, struct userfaultfd_wake_range *range) { |
15b726ef0 userfaultfd: opti... |
1171 |
spin_lock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1172 |
/* wake all in the range and autoremove */ |
15b726ef0 userfaultfd: opti... |
1173 |
if (waitqueue_active(&ctx->fault_pending_wqh)) |
ac5be6b47 userfaultfd: reve... |
1174 |
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, |
15b726ef0 userfaultfd: opti... |
1175 1176 |
range); if (waitqueue_active(&ctx->fault_wqh)) |
c430d1e84 userfaultfd: use ... |
1177 |
__wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range); |
15b726ef0 userfaultfd: opti... |
1178 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1179 1180 1181 1182 1183 |
} static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, struct userfaultfd_wake_range *range) { |
2c5b7e1be userfaultfd: avoi... |
1184 1185 |
unsigned seq; bool need_wakeup; |
86039bd3b userfaultfd: add ... |
1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 |
/* * To be sure waitqueue_active() is not reordered by the CPU * before the pagetable update, use an explicit SMP memory * barrier here. PT lock release or up_read(mmap_sem) still * have release semantics that can allow the * waitqueue_active() to be reordered before the pte update. */ smp_mb(); /* * Use waitqueue_active because it's very frequent to * change the address space atomically even if there are no * userfaults yet. So we take the spinlock only when we're * sure we've userfaults to wake. */ |
2c5b7e1be userfaultfd: avoi... |
1201 1202 1203 1204 1205 1206 1207 |
do { seq = read_seqcount_begin(&ctx->refile_seq); need_wakeup = waitqueue_active(&ctx->fault_pending_wqh) || waitqueue_active(&ctx->fault_wqh); cond_resched(); } while (read_seqcount_retry(&ctx->refile_seq, seq)); if (need_wakeup) |
86039bd3b userfaultfd: add ... |
1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 |
__wake_userfault(ctx, range); } static __always_inline int validate_range(struct mm_struct *mm, __u64 start, __u64 len) { __u64 task_size = mm->task_size; if (start & ~PAGE_MASK) return -EINVAL; if (len & ~PAGE_MASK) return -EINVAL; if (!len) return -EINVAL; if (start < mmap_min_addr) return -EINVAL; if (start >= task_size) return -EINVAL; if (len > task_size - start) return -EINVAL; return 0; } |
ba6907db6 userfaultfd: intr... |
1230 1231 |
static inline bool vma_can_userfault(struct vm_area_struct *vma) { |
cac673292 userfaultfd: shme... |
1232 1233 |
return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || vma_is_shmem(vma); |
ba6907db6 userfaultfd: intr... |
1234 |
} |
86039bd3b userfaultfd: add ... |
1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 |
static int userfaultfd_register(struct userfaultfd_ctx *ctx, unsigned long arg) { struct mm_struct *mm = ctx->mm; struct vm_area_struct *vma, *prev, *cur; int ret; struct uffdio_register uffdio_register; struct uffdio_register __user *user_uffdio_register; unsigned long vm_flags, new_flags; bool found; |
ce53e8e6f userfaultfd: repo... |
1245 |
bool basic_ioctls; |
86039bd3b userfaultfd: add ... |
1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 |
unsigned long start, end, vma_end; user_uffdio_register = (struct uffdio_register __user *) arg; ret = -EFAULT; if (copy_from_user(&uffdio_register, user_uffdio_register, sizeof(uffdio_register)-sizeof(__u64))) goto out; ret = -EINVAL; if (!uffdio_register.mode) goto out; if (uffdio_register.mode & ~(UFFDIO_REGISTER_MODE_MISSING| UFFDIO_REGISTER_MODE_WP)) goto out; vm_flags = 0; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) vm_flags |= VM_UFFD_MISSING; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { vm_flags |= VM_UFFD_WP; /* * FIXME: remove the below error constraint by * implementing the wprotect tracking mode. */ ret = -EINVAL; goto out; } ret = validate_range(mm, uffdio_register.range.start, uffdio_register.range.len); if (ret) goto out; start = uffdio_register.range.start; end = start + uffdio_register.range.len; |
d2005e3f4 userfaultfd: don'... |
1281 1282 1283 |
ret = -ENOMEM; if (!mmget_not_zero(mm)) goto out; |
86039bd3b userfaultfd: add ... |
1284 1285 |
down_write(&mm->mmap_sem); vma = find_vma_prev(mm, start, &prev); |
86039bd3b userfaultfd: add ... |
1286 1287 1288 1289 1290 1291 1292 1293 1294 |
if (!vma) goto out_unlock; /* check that there's at least one vma in the range */ ret = -EINVAL; if (vma->vm_start >= end) goto out_unlock; /* |
cab350afc userfaultfd: huge... |
1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 |
* If the first vma contains huge pages, make sure start address * is aligned to huge page size. */ if (is_vm_hugetlb_page(vma)) { unsigned long vma_hpagesize = vma_kernel_pagesize(vma); if (start & (vma_hpagesize - 1)) goto out_unlock; } /* |
86039bd3b userfaultfd: add ... |
1306 |
* Search for not compatible vmas. |
86039bd3b userfaultfd: add ... |
1307 1308 |
*/ found = false; |
ce53e8e6f userfaultfd: repo... |
1309 |
basic_ioctls = false; |
86039bd3b userfaultfd: add ... |
1310 1311 1312 1313 1314 1315 1316 1317 |
for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { cond_resched(); BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); /* check not compatible vmas */ ret = -EINVAL; |
ba6907db6 userfaultfd: intr... |
1318 |
if (!vma_can_userfault(cur)) |
86039bd3b userfaultfd: add ... |
1319 |
goto out_unlock; |
34b7a7cc5 userfaultfd: shme... |
1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 |
/* * UFFDIO_COPY will fill file holes even without * PROT_WRITE. This check enforces that if this is a * MAP_SHARED, the process has write permission to the backing * file. If VM_MAYWRITE is set it also enforces that on a * MAP_SHARED vma: there is no F_WRITE_SEAL and no further * F_WRITE_SEAL can be taken until the vma is destroyed. */ ret = -EPERM; if (unlikely(!(cur->vm_flags & VM_MAYWRITE))) goto out_unlock; |
cab350afc userfaultfd: huge... |
1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 |
/* * If this vma contains ending address, and huge pages * check alignment. */ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end && end > cur->vm_start) { unsigned long vma_hpagesize = vma_kernel_pagesize(cur); ret = -EINVAL; if (end & (vma_hpagesize - 1)) goto out_unlock; } |
86039bd3b userfaultfd: add ... |
1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 |
/* * Check that this vma isn't already owned by a * different userfaultfd. We can't allow more than one * userfaultfd to own a single vma simultaneously or we * wouldn't know which one to deliver the userfaults to. */ ret = -EBUSY; if (cur->vm_userfaultfd_ctx.ctx && cur->vm_userfaultfd_ctx.ctx != ctx) goto out_unlock; |
cab350afc userfaultfd: huge... |
1356 1357 1358 |
/* * Note vmas containing huge pages */ |
ce53e8e6f userfaultfd: repo... |
1359 1360 |
if (is_vm_hugetlb_page(cur)) basic_ioctls = true; |
cab350afc userfaultfd: huge... |
1361 |
|
86039bd3b userfaultfd: add ... |
1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 |
found = true; } BUG_ON(!found); if (vma->vm_start < start) prev = vma; ret = 0; do { cond_resched(); |
ba6907db6 userfaultfd: intr... |
1372 |
BUG_ON(!vma_can_userfault(vma)); |
86039bd3b userfaultfd: add ... |
1373 1374 |
BUG_ON(vma->vm_userfaultfd_ctx.ctx && vma->vm_userfaultfd_ctx.ctx != ctx); |
34b7a7cc5 userfaultfd: shme... |
1375 |
WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); |
86039bd3b userfaultfd: add ... |
1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 |
/* * Nothing to do: this vma is already registered into this * userfaultfd and with the right tracking mode too. */ if (vma->vm_userfaultfd_ctx.ctx == ctx && (vma->vm_flags & vm_flags) == vm_flags) goto skip; if (vma->vm_start > start) start = vma->vm_start; vma_end = min(end, vma->vm_end); new_flags = (vma->vm_flags & ~vm_flags) | vm_flags; prev = vma_merge(mm, prev, start, vma_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), ((struct vm_userfaultfd_ctx){ ctx })); if (prev) { vma = prev; goto next; } if (vma->vm_start < start) { ret = split_vma(mm, vma, start, 1); if (ret) break; } if (vma->vm_end > end) { ret = split_vma(mm, vma, end, 0); if (ret) break; } next: /* * In the vma_merge() successful mprotect-like case 8: * the next vma was merged into the current one and * the current one has not been updated yet. */ vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx.ctx = ctx; skip: prev = vma; start = vma->vm_end; vma = vma->vm_next; } while (vma && vma->vm_start < end); out_unlock: up_write(&mm->mmap_sem); |
d2005e3f4 userfaultfd: don'... |
1424 |
mmput(mm); |
86039bd3b userfaultfd: add ... |
1425 1426 1427 1428 1429 1430 |
if (!ret) { /* * Now that we scanned all vmas we can already tell * userland which ioctls methods are guaranteed to * succeed on this range. */ |
ce53e8e6f userfaultfd: repo... |
1431 |
if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : |
cab350afc userfaultfd: huge... |
1432 |
UFFD_API_RANGE_IOCTLS, |
86039bd3b userfaultfd: add ... |
1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 |
&user_uffdio_register->ioctls)) ret = -EFAULT; } out: return ret; } static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, unsigned long arg) { struct mm_struct *mm = ctx->mm; struct vm_area_struct *vma, *prev, *cur; int ret; struct uffdio_range uffdio_unregister; unsigned long new_flags; bool found; unsigned long start, end, vma_end; const void __user *buf = (void __user *)arg; ret = -EFAULT; if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) goto out; ret = validate_range(mm, uffdio_unregister.start, uffdio_unregister.len); if (ret) goto out; start = uffdio_unregister.start; end = start + uffdio_unregister.len; |
d2005e3f4 userfaultfd: don'... |
1463 1464 1465 |
ret = -ENOMEM; if (!mmget_not_zero(mm)) goto out; |
86039bd3b userfaultfd: add ... |
1466 1467 |
down_write(&mm->mmap_sem); vma = find_vma_prev(mm, start, &prev); |
86039bd3b userfaultfd: add ... |
1468 1469 1470 1471 1472 1473 1474 1475 1476 |
if (!vma) goto out_unlock; /* check that there's at least one vma in the range */ ret = -EINVAL; if (vma->vm_start >= end) goto out_unlock; /* |
cab350afc userfaultfd: huge... |
1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 |
* If the first vma contains huge pages, make sure start address * is aligned to huge page size. */ if (is_vm_hugetlb_page(vma)) { unsigned long vma_hpagesize = vma_kernel_pagesize(vma); if (start & (vma_hpagesize - 1)) goto out_unlock; } /* |
86039bd3b userfaultfd: add ... |
1488 |
* Search for not compatible vmas. |
86039bd3b userfaultfd: add ... |
1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 |
*/ found = false; ret = -EINVAL; for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { cond_resched(); BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); /* * Check not compatible vmas, not strictly required * here as not compatible vmas cannot have an * userfaultfd_ctx registered on them, but this * provides for more strict behavior to notice * unregistration errors. */ |
ba6907db6 userfaultfd: intr... |
1505 |
if (!vma_can_userfault(cur)) |
86039bd3b userfaultfd: add ... |
1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 |
goto out_unlock; found = true; } BUG_ON(!found); if (vma->vm_start < start) prev = vma; ret = 0; do { cond_resched(); |
ba6907db6 userfaultfd: intr... |
1518 |
BUG_ON(!vma_can_userfault(vma)); |
86039bd3b userfaultfd: add ... |
1519 1520 1521 1522 1523 1524 1525 |
/* * Nothing to do: this vma is already registered into this * userfaultfd and with the right tracking mode too. */ if (!vma->vm_userfaultfd_ctx.ctx) goto skip; |
d41c49daf userfaultfd: chec... |
1526 |
WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); |
86039bd3b userfaultfd: add ... |
1527 1528 1529 |
if (vma->vm_start > start) start = vma->vm_start; vma_end = min(end, vma->vm_end); |
09fa5296a userfaultfd: non-... |
1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 |
if (userfaultfd_missing(vma)) { /* * Wake any concurrent pending userfault while * we unregister, so they will not hang * permanently and it avoids userland to call * UFFDIO_WAKE explicitly. */ struct userfaultfd_wake_range range; range.start = start; range.len = vma_end - start; wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); } |
86039bd3b userfaultfd: add ... |
1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 |
new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); prev = vma_merge(mm, prev, start, vma_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), NULL_VM_UFFD_CTX); if (prev) { vma = prev; goto next; } if (vma->vm_start < start) { ret = split_vma(mm, vma, start, 1); if (ret) break; } if (vma->vm_end > end) { ret = split_vma(mm, vma, end, 0); if (ret) break; } next: /* * In the vma_merge() successful mprotect-like case 8: * the next vma was merged into the current one and * the current one has not been updated yet. */ vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; skip: prev = vma; start = vma->vm_end; vma = vma->vm_next; } while (vma && vma->vm_start < end); out_unlock: up_write(&mm->mmap_sem); |
d2005e3f4 userfaultfd: don'... |
1577 |
mmput(mm); |
86039bd3b userfaultfd: add ... |
1578 1579 1580 1581 1582 |
out: return ret; } /* |
ba85c702e userfaultfd: wake... |
1583 1584 |
* userfaultfd_wake may be used in combination with the * UFFDIO_*_MODE_DONTWAKE to wakeup userfaults in batches. |
86039bd3b userfaultfd: add ... |
1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 |
*/ static int userfaultfd_wake(struct userfaultfd_ctx *ctx, unsigned long arg) { int ret; struct uffdio_range uffdio_wake; struct userfaultfd_wake_range range; const void __user *buf = (void __user *)arg; ret = -EFAULT; if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake))) goto out; ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len); if (ret) goto out; range.start = uffdio_wake.start; range.len = uffdio_wake.len; /* * len == 0 means wake all and we don't want to wake all here, * so check it again to be sure. */ VM_BUG_ON(!range.len); wake_userfault(ctx, &range); ret = 0; out: return ret; } |
ad465cae9 userfaultfd: UFFD... |
1617 1618 1619 1620 1621 1622 1623 1624 1625 |
static int userfaultfd_copy(struct userfaultfd_ctx *ctx, unsigned long arg) { __s64 ret; struct uffdio_copy uffdio_copy; struct uffdio_copy __user *user_uffdio_copy; struct userfaultfd_wake_range range; user_uffdio_copy = (struct uffdio_copy __user *) arg; |
df2cc96e7 userfaultfd: prev... |
1626 1627 1628 |
ret = -EAGAIN; if (READ_ONCE(ctx->mmap_changing)) goto out; |
ad465cae9 userfaultfd: UFFD... |
1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 |
ret = -EFAULT; if (copy_from_user(&uffdio_copy, user_uffdio_copy, /* don't copy "copy" last field */ sizeof(uffdio_copy)-sizeof(__s64))) goto out; ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); if (ret) goto out; /* * double check for wraparound just in case. copy_from_user() * will later check uffdio_copy.src + uffdio_copy.len to fit * in the userland range. */ ret = -EINVAL; if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src) goto out; if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE) goto out; |
d2005e3f4 userfaultfd: don'... |
1648 1649 |
if (mmget_not_zero(ctx->mm)) { ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src, |
df2cc96e7 userfaultfd: prev... |
1650 |
uffdio_copy.len, &ctx->mmap_changing); |
d2005e3f4 userfaultfd: don'... |
1651 |
mmput(ctx->mm); |
96333187a userfaultfd_copy:... |
1652 |
} else { |
e86b298be userfaultfd: repl... |
1653 |
return -ESRCH; |
d2005e3f4 userfaultfd: don'... |
1654 |
} |
ad465cae9 userfaultfd: UFFD... |
1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 |
if (unlikely(put_user(ret, &user_uffdio_copy->copy))) return -EFAULT; if (ret < 0) goto out; BUG_ON(!ret); /* len == 0 would wake all */ range.len = ret; if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) { range.start = uffdio_copy.dst; wake_userfault(ctx, &range); } ret = range.len == uffdio_copy.len ? 0 : -EAGAIN; out: return ret; } static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, unsigned long arg) { __s64 ret; struct uffdio_zeropage uffdio_zeropage; struct uffdio_zeropage __user *user_uffdio_zeropage; struct userfaultfd_wake_range range; user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg; |
df2cc96e7 userfaultfd: prev... |
1680 1681 1682 |
ret = -EAGAIN; if (READ_ONCE(ctx->mmap_changing)) goto out; |
ad465cae9 userfaultfd: UFFD... |
1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 |
ret = -EFAULT; if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage, /* don't copy "zeropage" last field */ sizeof(uffdio_zeropage)-sizeof(__s64))) goto out; ret = validate_range(ctx->mm, uffdio_zeropage.range.start, uffdio_zeropage.range.len); if (ret) goto out; ret = -EINVAL; if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE) goto out; |
d2005e3f4 userfaultfd: don'... |
1696 1697 |
if (mmget_not_zero(ctx->mm)) { ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, |
df2cc96e7 userfaultfd: prev... |
1698 1699 |
uffdio_zeropage.range.len, &ctx->mmap_changing); |
d2005e3f4 userfaultfd: don'... |
1700 |
mmput(ctx->mm); |
9d95aa4ba userfaultfd_zerop... |
1701 |
} else { |
e86b298be userfaultfd: repl... |
1702 |
return -ESRCH; |
d2005e3f4 userfaultfd: don'... |
1703 |
} |
ad465cae9 userfaultfd: UFFD... |
1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 |
if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) return -EFAULT; if (ret < 0) goto out; /* len == 0 would wake all */ BUG_ON(!ret); range.len = ret; if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) { range.start = uffdio_zeropage.range.start; wake_userfault(ctx, &range); } ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN; out: return ret; } |
9cd75c3cd userfaultfd: non-... |
1719 1720 1721 1722 1723 1724 1725 |
static inline unsigned int uffd_ctx_features(__u64 user_features) { /* * For the current set of features the bits just coincide */ return (unsigned int)user_features; } |
86039bd3b userfaultfd: add ... |
1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 |
/* * userland asks for a certain API version and we return which bits * and ioctl commands are implemented in this kernel for such API * version or -EINVAL if unknown. */ static int userfaultfd_api(struct userfaultfd_ctx *ctx, unsigned long arg) { struct uffdio_api uffdio_api; void __user *buf = (void __user *)arg; int ret; |
656031445 userfaultfd: non-... |
1737 |
__u64 features; |
86039bd3b userfaultfd: add ... |
1738 1739 1740 1741 1742 |
ret = -EINVAL; if (ctx->state != UFFD_STATE_WAIT_API) goto out; ret = -EFAULT; |
a9b85f941 userfaultfd: chan... |
1743 |
if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api))) |
86039bd3b userfaultfd: add ... |
1744 |
goto out; |
656031445 userfaultfd: non-... |
1745 1746 |
features = uffdio_api.features; if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) { |
86039bd3b userfaultfd: add ... |
1747 1748 1749 1750 1751 1752 |
memset(&uffdio_api, 0, sizeof(uffdio_api)); if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) goto out; ret = -EINVAL; goto out; } |
656031445 userfaultfd: non-... |
1753 1754 |
/* report all available features and ioctls to userland */ uffdio_api.features = UFFD_API_FEATURES; |
86039bd3b userfaultfd: add ... |
1755 1756 1757 1758 1759 |
uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) goto out; ctx->state = UFFD_STATE_RUNNING; |
656031445 userfaultfd: non-... |
1760 1761 |
/* only enable the requested features for this uffd context */ ctx->features = uffd_ctx_features(features); |
86039bd3b userfaultfd: add ... |
1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 |
ret = 0; out: return ret; } static long userfaultfd_ioctl(struct file *file, unsigned cmd, unsigned long arg) { int ret = -EINVAL; struct userfaultfd_ctx *ctx = file->private_data; |
e6485a47b userfaultfd: requ... |
1772 1773 |
if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API) return -EINVAL; |
86039bd3b userfaultfd: add ... |
1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 |
switch(cmd) { case UFFDIO_API: ret = userfaultfd_api(ctx, arg); break; case UFFDIO_REGISTER: ret = userfaultfd_register(ctx, arg); break; case UFFDIO_UNREGISTER: ret = userfaultfd_unregister(ctx, arg); break; case UFFDIO_WAKE: ret = userfaultfd_wake(ctx, arg); break; |
ad465cae9 userfaultfd: UFFD... |
1787 1788 1789 1790 1791 1792 |
case UFFDIO_COPY: ret = userfaultfd_copy(ctx, arg); break; case UFFDIO_ZEROPAGE: ret = userfaultfd_zeropage(ctx, arg); break; |
86039bd3b userfaultfd: add ... |
1793 1794 1795 1796 1797 1798 1799 1800 |
} return ret; } #ifdef CONFIG_PROC_FS static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f) { struct userfaultfd_ctx *ctx = f->private_data; |
ac6424b98 sched/wait: Renam... |
1801 |
wait_queue_entry_t *wq; |
86039bd3b userfaultfd: add ... |
1802 |
unsigned long pending = 0, total = 0; |
15b726ef0 userfaultfd: opti... |
1803 |
spin_lock(&ctx->fault_pending_wqh.lock); |
2055da973 sched/wait: Disam... |
1804 |
list_for_each_entry(wq, &ctx->fault_pending_wqh.head, entry) { |
15b726ef0 userfaultfd: opti... |
1805 1806 1807 |
pending++; total++; } |
2055da973 sched/wait: Disam... |
1808 |
list_for_each_entry(wq, &ctx->fault_wqh.head, entry) { |
86039bd3b userfaultfd: add ... |
1809 1810 |
total++; } |
15b726ef0 userfaultfd: opti... |
1811 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 |
/* * If more protocols will be added, there will be all shown * separated by a space. Like this: * protocols: aa:... bb:... */ seq_printf(m, "pending:\t%lu total:\t%lu API:\t%Lx:%x:%Lx ", |
045098e94 userfaultfd: repo... |
1822 |
pending, total, UFFD_API, ctx->features, |
86039bd3b userfaultfd: add ... |
1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 |
UFFD_API_IOCTLS|UFFD_API_RANGE_IOCTLS); } #endif static const struct file_operations userfaultfd_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = userfaultfd_show_fdinfo, #endif .release = userfaultfd_release, .poll = userfaultfd_poll, .read = userfaultfd_read, .unlocked_ioctl = userfaultfd_ioctl, .compat_ioctl = userfaultfd_ioctl, .llseek = noop_llseek, }; |
3004ec9ca userfaultfd: allo... |
1838 1839 1840 1841 1842 1843 |
static void init_once_userfaultfd_ctx(void *mem) { struct userfaultfd_ctx *ctx = (struct userfaultfd_ctx *) mem; init_waitqueue_head(&ctx->fault_pending_wqh); init_waitqueue_head(&ctx->fault_wqh); |
9cd75c3cd userfaultfd: non-... |
1844 |
init_waitqueue_head(&ctx->event_wqh); |
3004ec9ca userfaultfd: allo... |
1845 |
init_waitqueue_head(&ctx->fd_wqh); |
2c5b7e1be userfaultfd: avoi... |
1846 |
seqcount_init(&ctx->refile_seq); |
3004ec9ca userfaultfd: allo... |
1847 |
} |
284cd241a userfaultfd: conv... |
1848 |
SYSCALL_DEFINE1(userfaultfd, int, flags) |
86039bd3b userfaultfd: add ... |
1849 |
{ |
86039bd3b userfaultfd: add ... |
1850 |
struct userfaultfd_ctx *ctx; |
284cd241a userfaultfd: conv... |
1851 |
int fd; |
86039bd3b userfaultfd: add ... |
1852 1853 1854 1855 1856 1857 |
BUG_ON(!current->mm); /* Check the UFFD_* constants for consistency. */ BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXEC); BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBLOCK); |
86039bd3b userfaultfd: add ... |
1858 |
if (flags & ~UFFD_SHARED_FCNTL_FLAGS) |
284cd241a userfaultfd: conv... |
1859 |
return -EINVAL; |
86039bd3b userfaultfd: add ... |
1860 |
|
3004ec9ca userfaultfd: allo... |
1861 |
ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); |
86039bd3b userfaultfd: add ... |
1862 |
if (!ctx) |
284cd241a userfaultfd: conv... |
1863 |
return -ENOMEM; |
86039bd3b userfaultfd: add ... |
1864 1865 |
atomic_set(&ctx->refcount, 1); |
86039bd3b userfaultfd: add ... |
1866 |
ctx->flags = flags; |
9cd75c3cd userfaultfd: non-... |
1867 |
ctx->features = 0; |
86039bd3b userfaultfd: add ... |
1868 1869 |
ctx->state = UFFD_STATE_WAIT_API; ctx->released = false; |
df2cc96e7 userfaultfd: prev... |
1870 |
ctx->mmap_changing = false; |
86039bd3b userfaultfd: add ... |
1871 1872 |
ctx->mm = current->mm; /* prevent the mm struct to be freed */ |
f1f100764 mm: add new mmgra... |
1873 |
mmgrab(ctx->mm); |
86039bd3b userfaultfd: add ... |
1874 |
|
284cd241a userfaultfd: conv... |
1875 1876 1877 |
fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx, O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS)); if (fd < 0) { |
d2005e3f4 userfaultfd: don'... |
1878 |
mmdrop(ctx->mm); |
3004ec9ca userfaultfd: allo... |
1879 |
kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
c03e946fd userfaultfd: add ... |
1880 |
} |
86039bd3b userfaultfd: add ... |
1881 |
return fd; |
86039bd3b userfaultfd: add ... |
1882 |
} |
3004ec9ca userfaultfd: allo... |
1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 |
static int __init userfaultfd_init(void) { userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache", sizeof(struct userfaultfd_ctx), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, init_once_userfaultfd_ctx); return 0; } __initcall(userfaultfd_init); |