1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * fs/userfaultfd.c 3 * fs/userfaultfd.c
4 * 4 *
5 * Copyright (C) 2007 Davide Libenzi <davide 5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
6 * Copyright (C) 2008-2009 Red Hat, Inc. 6 * Copyright (C) 2008-2009 Red Hat, Inc.
7 * Copyright (C) 2015 Red Hat, Inc. 7 * Copyright (C) 2015 Red Hat, Inc.
8 * 8 *
9 * Some part derived from fs/eventfd.c (anon 9 * Some part derived from fs/eventfd.c (anon inode setup) and
10 * mm/ksm.c (mm hashing). 10 * mm/ksm.c (mm hashing).
11 */ 11 */
12 12
13 #include <linux/list.h> 13 #include <linux/list.h>
14 #include <linux/hashtable.h> 14 #include <linux/hashtable.h>
15 #include <linux/sched/signal.h> 15 #include <linux/sched/signal.h>
16 #include <linux/sched/mm.h> 16 #include <linux/sched/mm.h>
17 #include <linux/mm.h> 17 #include <linux/mm.h>
18 #include <linux/mm_inline.h> <<
19 #include <linux/mmu_notifier.h> <<
20 #include <linux/poll.h> 18 #include <linux/poll.h>
21 #include <linux/slab.h> 19 #include <linux/slab.h>
22 #include <linux/seq_file.h> 20 #include <linux/seq_file.h>
23 #include <linux/file.h> 21 #include <linux/file.h>
24 #include <linux/bug.h> 22 #include <linux/bug.h>
25 #include <linux/anon_inodes.h> 23 #include <linux/anon_inodes.h>
26 #include <linux/syscalls.h> 24 #include <linux/syscalls.h>
27 #include <linux/userfaultfd_k.h> 25 #include <linux/userfaultfd_k.h>
28 #include <linux/mempolicy.h> 26 #include <linux/mempolicy.h>
29 #include <linux/ioctl.h> 27 #include <linux/ioctl.h>
30 #include <linux/security.h> 28 #include <linux/security.h>
31 #include <linux/hugetlb.h> 29 #include <linux/hugetlb.h>
32 #include <linux/swapops.h> !! 30
33 #include <linux/miscdevice.h> !! 31 int sysctl_unprivileged_userfaultfd __read_mostly = 1;
34 #include <linux/uio.h> !! 32
35 !! 33 static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;
36 static int sysctl_unprivileged_userfaultfd __r !! 34
37 !! 35 enum userfaultfd_state {
38 #ifdef CONFIG_SYSCTL !! 36 UFFD_STATE_WAIT_API,
39 static struct ctl_table vm_userfaultfd_table[] !! 37 UFFD_STATE_RUNNING,
40 { <<
41 .procname = "unprivilege <<
42 .data = &sysctl_unpr <<
43 .maxlen = sizeof(sysct <<
44 .mode = 0644, <<
45 .proc_handler = proc_dointve <<
46 .extra1 = SYSCTL_ZERO, <<
47 .extra2 = SYSCTL_ONE, <<
48 }, <<
49 }; 38 };
50 #endif <<
51 39
52 static struct kmem_cache *userfaultfd_ctx_cach !! 40 /*
>> 41 * Start with fault_pending_wqh and fault_wqh so they're more likely
>> 42 * to be in the same cacheline.
>> 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.
>> 53 */
>> 54 struct userfaultfd_ctx {
>> 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 */
>> 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;
>> 61 /* waitqueue head for events */
>> 62 wait_queue_head_t event_wqh;
>> 63 /* a refile sequence protected by fault_pending_wqh lock */
>> 64 struct seqcount refile_seq;
>> 65 /* pseudo fd refcounting */
>> 66 refcount_t refcount;
>> 67 /* userfaultfd syscall flags */
>> 68 unsigned int flags;
>> 69 /* features requested from the userspace */
>> 70 unsigned int features;
>> 71 /* state machine */
>> 72 enum userfaultfd_state state;
>> 73 /* released */
>> 74 bool released;
>> 75 /* memory mappings are changing because of non-cooperative event */
>> 76 bool mmap_changing;
>> 77 /* mm with one ore more vmas attached to this userfaultfd_ctx */
>> 78 struct mm_struct *mm;
>> 79 };
53 80
54 struct userfaultfd_fork_ctx { 81 struct userfaultfd_fork_ctx {
55 struct userfaultfd_ctx *orig; 82 struct userfaultfd_ctx *orig;
56 struct userfaultfd_ctx *new; 83 struct userfaultfd_ctx *new;
57 struct list_head list; 84 struct list_head list;
58 }; 85 };
59 86
60 struct userfaultfd_unmap_ctx { 87 struct userfaultfd_unmap_ctx {
61 struct userfaultfd_ctx *ctx; 88 struct userfaultfd_ctx *ctx;
62 unsigned long start; 89 unsigned long start;
63 unsigned long end; 90 unsigned long end;
64 struct list_head list; 91 struct list_head list;
65 }; 92 };
66 93
67 struct userfaultfd_wait_queue { 94 struct userfaultfd_wait_queue {
68 struct uffd_msg msg; 95 struct uffd_msg msg;
69 wait_queue_entry_t wq; 96 wait_queue_entry_t wq;
70 struct userfaultfd_ctx *ctx; 97 struct userfaultfd_ctx *ctx;
71 bool waken; 98 bool waken;
72 }; 99 };
73 100
74 struct userfaultfd_wake_range { 101 struct userfaultfd_wake_range {
75 unsigned long start; 102 unsigned long start;
76 unsigned long len; 103 unsigned long len;
77 }; 104 };
78 105
79 /* internal indication that UFFD_API ioctl was <<
80 #define UFFD_FEATURE_INITIALIZED <<
81 <<
82 static bool userfaultfd_is_initialized(struct <<
83 { <<
84 return ctx->features & UFFD_FEATURE_IN <<
85 } <<
86 <<
87 static bool userfaultfd_wp_async_ctx(struct us <<
88 { <<
89 return ctx && (ctx->features & UFFD_FE <<
90 } <<
91 <<
92 /* <<
93 * Whether WP_UNPOPULATED is enabled on the uf <<
94 * meaningful when userfaultfd_wp()==true on t <<
95 * anonymous. <<
96 */ <<
97 bool userfaultfd_wp_unpopulated(struct vm_area <<
98 { <<
99 struct userfaultfd_ctx *ctx = vma->vm_ <<
100 <<
101 if (!ctx) <<
102 return false; <<
103 <<
104 return ctx->features & UFFD_FEATURE_WP <<
105 } <<
106 <<
107 static void userfaultfd_set_vm_flags(struct vm <<
108 vm_flags_ <<
109 { <<
110 const bool uffd_wp_changed = (vma->vm_ <<
111 <<
112 vm_flags_reset(vma, flags); <<
113 /* <<
114 * For shared mappings, we want to ena <<
115 * userfaultfd-wp is enabled (see vma_ <<
116 * recalculate vma->vm_page_prot whene <<
117 */ <<
118 if ((vma->vm_flags & VM_SHARED) && uff <<
119 vma_set_page_prot(vma); <<
120 } <<
121 <<
122 static int userfaultfd_wake_function(wait_queu 106 static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode,
123 int wake_ 107 int wake_flags, void *key)
124 { 108 {
125 struct userfaultfd_wake_range *range = 109 struct userfaultfd_wake_range *range = key;
126 int ret; 110 int ret;
127 struct userfaultfd_wait_queue *uwq; 111 struct userfaultfd_wait_queue *uwq;
128 unsigned long start, len; 112 unsigned long start, len;
129 113
130 uwq = container_of(wq, struct userfaul 114 uwq = container_of(wq, struct userfaultfd_wait_queue, wq);
131 ret = 0; 115 ret = 0;
132 /* len == 0 means wake all */ 116 /* len == 0 means wake all */
133 start = range->start; 117 start = range->start;
134 len = range->len; 118 len = range->len;
135 if (len && (start > uwq->msg.arg.pagef 119 if (len && (start > uwq->msg.arg.pagefault.address ||
136 start + len <= uwq->msg.ar 120 start + len <= uwq->msg.arg.pagefault.address))
137 goto out; 121 goto out;
138 WRITE_ONCE(uwq->waken, true); 122 WRITE_ONCE(uwq->waken, true);
139 /* 123 /*
140 * The Program-Order guarantees provid 124 * The Program-Order guarantees provided by the scheduler
141 * ensure uwq->waken is visible before 125 * ensure uwq->waken is visible before the task is woken.
142 */ 126 */
143 ret = wake_up_state(wq->private, mode) 127 ret = wake_up_state(wq->private, mode);
144 if (ret) { 128 if (ret) {
145 /* 129 /*
146 * Wake only once, autoremove 130 * Wake only once, autoremove behavior.
147 * 131 *
148 * After the effect of list_de 132 * After the effect of list_del_init is visible to the other
149 * CPUs, the waitqueue may dis 133 * CPUs, the waitqueue may disappear from under us, see the
150 * !list_empty_careful() in ha 134 * !list_empty_careful() in handle_userfault().
151 * 135 *
152 * try_to_wake_up() has an imp 136 * try_to_wake_up() has an implicit smp_mb(), and the
153 * wq->private is read before 137 * wq->private is read before calling the extern function
154 * "wake_up_state" (which in t 138 * "wake_up_state" (which in turns calls try_to_wake_up).
155 */ 139 */
156 list_del_init(&wq->entry); 140 list_del_init(&wq->entry);
157 } 141 }
158 out: 142 out:
159 return ret; 143 return ret;
160 } 144 }
161 145
162 /** 146 /**
163 * userfaultfd_ctx_get - Acquires a reference 147 * userfaultfd_ctx_get - Acquires a reference to the internal userfaultfd
164 * context. 148 * context.
165 * @ctx: [in] Pointer to the userfaultfd conte 149 * @ctx: [in] Pointer to the userfaultfd context.
166 */ 150 */
167 static void userfaultfd_ctx_get(struct userfau 151 static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx)
168 { 152 {
169 refcount_inc(&ctx->refcount); 153 refcount_inc(&ctx->refcount);
170 } 154 }
171 155
172 /** 156 /**
173 * userfaultfd_ctx_put - Releases a reference 157 * userfaultfd_ctx_put - Releases a reference to the internal userfaultfd
174 * context. 158 * context.
175 * @ctx: [in] Pointer to userfaultfd context. 159 * @ctx: [in] Pointer to userfaultfd context.
176 * 160 *
177 * The userfaultfd context reference must have 161 * The userfaultfd context reference must have been previously acquired either
178 * with userfaultfd_ctx_get() or userfaultfd_c 162 * with userfaultfd_ctx_get() or userfaultfd_ctx_fdget().
179 */ 163 */
180 static void userfaultfd_ctx_put(struct userfau 164 static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx)
181 { 165 {
182 if (refcount_dec_and_test(&ctx->refcou 166 if (refcount_dec_and_test(&ctx->refcount)) {
183 VM_BUG_ON(spin_is_locked(&ctx- 167 VM_BUG_ON(spin_is_locked(&ctx->fault_pending_wqh.lock));
184 VM_BUG_ON(waitqueue_active(&ct 168 VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh));
185 VM_BUG_ON(spin_is_locked(&ctx- 169 VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock));
186 VM_BUG_ON(waitqueue_active(&ct 170 VM_BUG_ON(waitqueue_active(&ctx->fault_wqh));
187 VM_BUG_ON(spin_is_locked(&ctx- 171 VM_BUG_ON(spin_is_locked(&ctx->event_wqh.lock));
188 VM_BUG_ON(waitqueue_active(&ct 172 VM_BUG_ON(waitqueue_active(&ctx->event_wqh));
189 VM_BUG_ON(spin_is_locked(&ctx- 173 VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock));
190 VM_BUG_ON(waitqueue_active(&ct 174 VM_BUG_ON(waitqueue_active(&ctx->fd_wqh));
191 mmdrop(ctx->mm); 175 mmdrop(ctx->mm);
192 kmem_cache_free(userfaultfd_ct 176 kmem_cache_free(userfaultfd_ctx_cachep, ctx);
193 } 177 }
194 } 178 }
195 179
196 static inline void msg_init(struct uffd_msg *m 180 static inline void msg_init(struct uffd_msg *msg)
197 { 181 {
198 BUILD_BUG_ON(sizeof(struct uffd_msg) ! 182 BUILD_BUG_ON(sizeof(struct uffd_msg) != 32);
199 /* 183 /*
200 * Must use memset to zero out the pad 184 * Must use memset to zero out the paddings or kernel data is
201 * leaked to userland. 185 * leaked to userland.
202 */ 186 */
203 memset(msg, 0, sizeof(struct uffd_msg) 187 memset(msg, 0, sizeof(struct uffd_msg));
204 } 188 }
205 189
206 static inline struct uffd_msg userfault_msg(un 190 static inline struct uffd_msg userfault_msg(unsigned long address,
207 un <<
208 un 191 unsigned int flags,
209 un 192 unsigned long reason,
210 un 193 unsigned int features)
211 { 194 {
212 struct uffd_msg msg; 195 struct uffd_msg msg;
213 <<
214 msg_init(&msg); 196 msg_init(&msg);
215 msg.event = UFFD_EVENT_PAGEFAULT; 197 msg.event = UFFD_EVENT_PAGEFAULT;
216 !! 198 msg.arg.pagefault.address = address;
217 msg.arg.pagefault.address = (features <<
218 real_addre <<
219 <<
220 /* <<
221 * These flags indicate why the userfa <<
222 * - UFFD_PAGEFAULT_FLAG_WP indicates <<
223 * - UFFD_PAGEFAULT_FLAG_MINOR indicat <<
224 * - Neither of these flags being set <<
225 * <<
226 * Separately, UFFD_PAGEFAULT_FLAG_WRI <<
227 * fault. Otherwise, it was a read fau <<
228 */ <<
229 if (flags & FAULT_FLAG_WRITE) 199 if (flags & FAULT_FLAG_WRITE)
>> 200 /*
>> 201 * If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the
>> 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.
>> 206 */
230 msg.arg.pagefault.flags |= UFF 207 msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WRITE;
231 if (reason & VM_UFFD_WP) 208 if (reason & VM_UFFD_WP)
>> 209 /*
>> 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.
>> 215 */
232 msg.arg.pagefault.flags |= UFF 216 msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WP;
233 if (reason & VM_UFFD_MINOR) <<
234 msg.arg.pagefault.flags |= UFF <<
235 if (features & UFFD_FEATURE_THREAD_ID) 217 if (features & UFFD_FEATURE_THREAD_ID)
236 msg.arg.pagefault.feat.ptid = 218 msg.arg.pagefault.feat.ptid = task_pid_vnr(current);
237 return msg; 219 return msg;
238 } 220 }
239 221
240 #ifdef CONFIG_HUGETLB_PAGE 222 #ifdef CONFIG_HUGETLB_PAGE
241 /* 223 /*
242 * Same functionality as userfaultfd_must_wait 224 * Same functionality as userfaultfd_must_wait below with modifications for
243 * hugepmd ranges. 225 * hugepmd ranges.
244 */ 226 */
245 static inline bool userfaultfd_huge_must_wait( 227 static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
246 !! 228 struct vm_area_struct *vma,
247 !! 229 unsigned long address,
>> 230 unsigned long flags,
>> 231 unsigned long reason)
248 { 232 {
249 struct vm_area_struct *vma = vmf->vma; !! 233 struct mm_struct *mm = ctx->mm;
250 pte_t *ptep, pte; 234 pte_t *ptep, pte;
251 bool ret = true; 235 bool ret = true;
252 236
253 assert_fault_locked(vmf); !! 237 VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
>> 238
>> 239 ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
254 240
255 ptep = hugetlb_walk(vma, vmf->address, <<
256 if (!ptep) 241 if (!ptep)
257 goto out; 242 goto out;
258 243
259 ret = false; 244 ret = false;
260 pte = huge_ptep_get(vma->vm_mm, vmf->a !! 245 pte = huge_ptep_get(ptep);
261 246
262 /* 247 /*
263 * Lockless access: we're in a wait_ev 248 * Lockless access: we're in a wait_event so it's ok if it
264 * changes under us. PTE markers shou !! 249 * changes under us.
265 * ptes here. <<
266 */ 250 */
267 if (huge_pte_none_mostly(pte)) !! 251 if (huge_pte_none(pte))
268 ret = true; 252 ret = true;
269 if (!huge_pte_write(pte) && (reason & 253 if (!huge_pte_write(pte) && (reason & VM_UFFD_WP))
270 ret = true; 254 ret = true;
271 out: 255 out:
272 return ret; 256 return ret;
273 } 257 }
274 #else 258 #else
275 static inline bool userfaultfd_huge_must_wait( 259 static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
276 !! 260 struct vm_area_struct *vma,
277 !! 261 unsigned long address,
>> 262 unsigned long flags,
>> 263 unsigned long reason)
278 { 264 {
279 return false; /* should never get he 265 return false; /* should never get here */
280 } 266 }
281 #endif /* CONFIG_HUGETLB_PAGE */ 267 #endif /* CONFIG_HUGETLB_PAGE */
282 268
283 /* 269 /*
284 * Verify the pagetables are still not ok afte 270 * Verify the pagetables are still not ok after having reigstered into
285 * the fault_pending_wqh to avoid userland hav 271 * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any
286 * userfault that has already been resolved, i !! 272 * userfault that has already been resolved, if userfaultfd_read and
287 * UFFDIO_COPY|ZEROPAGE are being run simultan 273 * UFFDIO_COPY|ZEROPAGE are being run simultaneously on two different
288 * threads. 274 * threads.
289 */ 275 */
290 static inline bool userfaultfd_must_wait(struc 276 static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
291 struc !! 277 unsigned long address,
>> 278 unsigned long flags,
292 unsig 279 unsigned long reason)
293 { 280 {
294 struct mm_struct *mm = ctx->mm; 281 struct mm_struct *mm = ctx->mm;
295 unsigned long address = vmf->address; <<
296 pgd_t *pgd; 282 pgd_t *pgd;
297 p4d_t *p4d; 283 p4d_t *p4d;
298 pud_t *pud; 284 pud_t *pud;
299 pmd_t *pmd, _pmd; 285 pmd_t *pmd, _pmd;
300 pte_t *pte; 286 pte_t *pte;
301 pte_t ptent; <<
302 bool ret = true; 287 bool ret = true;
303 288
304 assert_fault_locked(vmf); !! 289 VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
305 290
306 pgd = pgd_offset(mm, address); 291 pgd = pgd_offset(mm, address);
307 if (!pgd_present(*pgd)) 292 if (!pgd_present(*pgd))
308 goto out; 293 goto out;
309 p4d = p4d_offset(pgd, address); 294 p4d = p4d_offset(pgd, address);
310 if (!p4d_present(*p4d)) 295 if (!p4d_present(*p4d))
311 goto out; 296 goto out;
312 pud = pud_offset(p4d, address); 297 pud = pud_offset(p4d, address);
313 if (!pud_present(*pud)) 298 if (!pud_present(*pud))
314 goto out; 299 goto out;
315 pmd = pmd_offset(pud, address); 300 pmd = pmd_offset(pud, address);
316 again: !! 301 /*
317 _pmd = pmdp_get_lockless(pmd); !! 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);
318 if (pmd_none(_pmd)) 310 if (pmd_none(_pmd))
319 goto out; 311 goto out;
320 312
321 ret = false; 313 ret = false;
322 if (!pmd_present(_pmd) || pmd_devmap(_ !! 314 if (!pmd_present(_pmd))
323 goto out; 315 goto out;
324 316
325 if (pmd_trans_huge(_pmd)) { 317 if (pmd_trans_huge(_pmd)) {
326 if (!pmd_write(_pmd) && (reaso 318 if (!pmd_write(_pmd) && (reason & VM_UFFD_WP))
327 ret = true; 319 ret = true;
328 goto out; 320 goto out;
329 } 321 }
330 322
>> 323 /*
>> 324 * the pmd is stable (as in !pmd_trans_unstable) so we can re-read it
>> 325 * and use the standard pte_offset_map() instead of parsing _pmd.
>> 326 */
331 pte = pte_offset_map(pmd, address); 327 pte = pte_offset_map(pmd, address);
332 if (!pte) { <<
333 ret = true; <<
334 goto again; <<
335 } <<
336 /* 328 /*
337 * Lockless access: we're in a wait_ev 329 * Lockless access: we're in a wait_event so it's ok if it
338 * changes under us. PTE markers shou !! 330 * changes under us.
339 * ptes here. <<
340 */ 331 */
341 ptent = ptep_get(pte); !! 332 if (pte_none(*pte))
342 if (pte_none_mostly(ptent)) <<
343 ret = true; 333 ret = true;
344 if (!pte_write(ptent) && (reason & VM_ !! 334 if (!pte_write(*pte) && (reason & VM_UFFD_WP))
345 ret = true; 335 ret = true;
346 pte_unmap(pte); 336 pte_unmap(pte);
347 337
348 out: 338 out:
349 return ret; 339 return ret;
350 } 340 }
351 341
352 static inline unsigned int userfaultfd_get_blo !! 342 /* Should pair with userfaultfd_signal_pending() */
>> 343 static inline long userfaultfd_get_blocking_state(unsigned int flags)
353 { 344 {
354 if (flags & FAULT_FLAG_INTERRUPTIBLE) 345 if (flags & FAULT_FLAG_INTERRUPTIBLE)
355 return TASK_INTERRUPTIBLE; 346 return TASK_INTERRUPTIBLE;
356 347
357 if (flags & FAULT_FLAG_KILLABLE) 348 if (flags & FAULT_FLAG_KILLABLE)
358 return TASK_KILLABLE; 349 return TASK_KILLABLE;
359 350
360 return TASK_UNINTERRUPTIBLE; 351 return TASK_UNINTERRUPTIBLE;
361 } 352 }
362 353
>> 354 /* Should pair with userfaultfd_get_blocking_state() */
>> 355 static inline bool userfaultfd_signal_pending(unsigned int flags)
>> 356 {
>> 357 if (flags & FAULT_FLAG_INTERRUPTIBLE)
>> 358 return signal_pending(current);
>> 359
>> 360 if (flags & FAULT_FLAG_KILLABLE)
>> 361 return fatal_signal_pending(current);
>> 362
>> 363 return false;
>> 364 }
>> 365
363 /* 366 /*
364 * The locking rules involved in returning VM_ 367 * The locking rules involved in returning VM_FAULT_RETRY depending on
365 * FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NO 368 * FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NOWAIT and
366 * FAULT_FLAG_KILLABLE are not straightforward 369 * FAULT_FLAG_KILLABLE are not straightforward. The "Caution"
367 * recommendation in __lock_page_or_retry is n 370 * recommendation in __lock_page_or_retry is not an understatement.
368 * 371 *
369 * If FAULT_FLAG_ALLOW_RETRY is set, the mmap_ !! 372 * If FAULT_FLAG_ALLOW_RETRY is set, the mmap_sem must be released
370 * before returning VM_FAULT_RETRY only if FAU 373 * before returning VM_FAULT_RETRY only if FAULT_FLAG_RETRY_NOWAIT is
371 * not set. 374 * not set.
372 * 375 *
373 * If FAULT_FLAG_ALLOW_RETRY is set but FAULT_ 376 * If FAULT_FLAG_ALLOW_RETRY is set but FAULT_FLAG_KILLABLE is not
374 * set, VM_FAULT_RETRY can still be returned i 377 * set, VM_FAULT_RETRY can still be returned if and only if there are
375 * fatal_signal_pending()s, and the mmap_lock !! 378 * fatal_signal_pending()s, and the mmap_sem must be released before
376 * returning it. 379 * returning it.
377 */ 380 */
378 vm_fault_t handle_userfault(struct vm_fault *v 381 vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)
379 { 382 {
380 struct vm_area_struct *vma = vmf->vma; !! 383 struct mm_struct *mm = vmf->vma->vm_mm;
381 struct mm_struct *mm = vma->vm_mm; <<
382 struct userfaultfd_ctx *ctx; 384 struct userfaultfd_ctx *ctx;
383 struct userfaultfd_wait_queue uwq; 385 struct userfaultfd_wait_queue uwq;
384 vm_fault_t ret = VM_FAULT_SIGBUS; 386 vm_fault_t ret = VM_FAULT_SIGBUS;
385 bool must_wait; 387 bool must_wait;
386 unsigned int blocking_state; !! 388 long blocking_state;
387 389
388 /* 390 /*
389 * We don't do userfault handling for 391 * We don't do userfault handling for the final child pid update.
390 * 392 *
391 * We also don't do userfault handling 393 * We also don't do userfault handling during
392 * coredumping. hugetlbfs has the spec 394 * coredumping. hugetlbfs has the special
393 * hugetlb_follow_page_mask() to skip !! 395 * follow_hugetlb_page() to skip missing pages in the
394 * FOLL_DUMP case, anon memory also ch 396 * FOLL_DUMP case, anon memory also checks for FOLL_DUMP with
395 * the no_page_table() helper in follo 397 * the no_page_table() helper in follow_page_mask(), but the
396 * shmem_vm_ops->fault method is invok 398 * shmem_vm_ops->fault method is invoked even during
397 * coredumping and it ends up here. !! 399 * coredumping without mmap_sem and it ends up here.
398 */ 400 */
399 if (current->flags & (PF_EXITING|PF_DU 401 if (current->flags & (PF_EXITING|PF_DUMPCORE))
400 goto out; 402 goto out;
401 403
402 assert_fault_locked(vmf); !! 404 /*
>> 405 * Coredumping runs without mmap_sem so we can only check that
>> 406 * the mmap_sem is held, if PF_DUMPCORE was not set.
>> 407 */
>> 408 WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem));
403 409
404 ctx = vma->vm_userfaultfd_ctx.ctx; !! 410 ctx = vmf->vma->vm_userfaultfd_ctx.ctx;
405 if (!ctx) 411 if (!ctx)
406 goto out; 412 goto out;
407 413
408 BUG_ON(ctx->mm != mm); 414 BUG_ON(ctx->mm != mm);
409 415
410 /* Any unrecognized flag is a bug. */ !! 416 VM_BUG_ON(reason & ~(VM_UFFD_MISSING|VM_UFFD_WP));
411 VM_BUG_ON(reason & ~__VM_UFFD_FLAGS); !! 417 VM_BUG_ON(!(reason & VM_UFFD_MISSING) ^ !!(reason & VM_UFFD_WP));
412 /* 0 or > 1 flags set is a bug; we exp <<
413 VM_BUG_ON(!reason || (reason & (reason <<
414 418
415 if (ctx->features & UFFD_FEATURE_SIGBU 419 if (ctx->features & UFFD_FEATURE_SIGBUS)
416 goto out; 420 goto out;
417 if (!(vmf->flags & FAULT_FLAG_USER) && <<
418 goto out; <<
419 421
420 /* 422 /*
421 * If it's already released don't get 423 * If it's already released don't get it. This avoids to loop
422 * in __get_user_pages if userfaultfd_ 424 * in __get_user_pages if userfaultfd_release waits on the
423 * caller of handle_userfault to relea !! 425 * caller of handle_userfault to release the mmap_sem.
424 */ 426 */
425 if (unlikely(READ_ONCE(ctx->released)) 427 if (unlikely(READ_ONCE(ctx->released))) {
426 /* 428 /*
427 * Don't return VM_FAULT_SIGBU 429 * Don't return VM_FAULT_SIGBUS in this case, so a non
428 * cooperative manager can clo 430 * cooperative manager can close the uffd after the
429 * last UFFDIO_COPY, without r 431 * last UFFDIO_COPY, without risking to trigger an
430 * involuntary SIGBUS if the p 432 * involuntary SIGBUS if the process was starting the
431 * userfaultfd while the userf 433 * userfaultfd while the userfaultfd was still armed
432 * (but after the last UFFDIO_ 434 * (but after the last UFFDIO_COPY). If the uffd
433 * wasn't already closed when 435 * wasn't already closed when the userfault reached
434 * this point, that would norm 436 * this point, that would normally be solved by
435 * userfaultfd_must_wait retur 437 * userfaultfd_must_wait returning 'false'.
436 * 438 *
437 * If we were to return VM_FAU 439 * If we were to return VM_FAULT_SIGBUS here, the non
438 * cooperative manager would b 440 * cooperative manager would be instead forced to
439 * always call UFFDIO_UNREGIST 441 * always call UFFDIO_UNREGISTER before it can safely
440 * close the uffd. 442 * close the uffd.
441 */ 443 */
442 ret = VM_FAULT_NOPAGE; 444 ret = VM_FAULT_NOPAGE;
443 goto out; 445 goto out;
444 } 446 }
445 447
446 /* 448 /*
447 * Check that we can return VM_FAULT_R 449 * Check that we can return VM_FAULT_RETRY.
448 * 450 *
449 * NOTE: it should become possible to 451 * NOTE: it should become possible to return VM_FAULT_RETRY
450 * even if FAULT_FLAG_TRIED is set wit 452 * even if FAULT_FLAG_TRIED is set without leading to gup()
451 * -EBUSY failures, if the userfaultfd 453 * -EBUSY failures, if the userfaultfd is to be extended for
452 * VM_UFFD_WP tracking and we intend t 454 * VM_UFFD_WP tracking and we intend to arm the userfault
453 * without first stopping userland acc 455 * without first stopping userland access to the memory. For
454 * VM_UFFD_MISSING userfaults this is 456 * VM_UFFD_MISSING userfaults this is enough for now.
455 */ 457 */
456 if (unlikely(!(vmf->flags & FAULT_FLAG 458 if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) {
457 /* 459 /*
458 * Validate the invariant that 460 * Validate the invariant that nowait must allow retry
459 * to be sure not to return SI 461 * to be sure not to return SIGBUS erroneously on
460 * nowait invocations. 462 * nowait invocations.
461 */ 463 */
462 BUG_ON(vmf->flags & FAULT_FLAG 464 BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT);
463 #ifdef CONFIG_DEBUG_VM 465 #ifdef CONFIG_DEBUG_VM
464 if (printk_ratelimit()) { 466 if (printk_ratelimit()) {
465 printk(KERN_WARNING 467 printk(KERN_WARNING
466 "FAULT_FLAG_ALL 468 "FAULT_FLAG_ALLOW_RETRY missing %x\n",
467 vmf->flags); 469 vmf->flags);
468 dump_stack(); 470 dump_stack();
469 } 471 }
470 #endif 472 #endif
471 goto out; 473 goto out;
472 } 474 }
473 475
474 /* 476 /*
475 * Handle nowait, not much to do other 477 * Handle nowait, not much to do other than tell it to retry
476 * and wait. 478 * and wait.
477 */ 479 */
478 ret = VM_FAULT_RETRY; 480 ret = VM_FAULT_RETRY;
479 if (vmf->flags & FAULT_FLAG_RETRY_NOWA 481 if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
480 goto out; 482 goto out;
481 483
482 /* take the reference before dropping !! 484 /* take the reference before dropping the mmap_sem */
483 userfaultfd_ctx_get(ctx); 485 userfaultfd_ctx_get(ctx);
484 486
485 init_waitqueue_func_entry(&uwq.wq, use 487 init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function);
486 uwq.wq.private = current; 488 uwq.wq.private = current;
487 uwq.msg = userfault_msg(vmf->address, !! 489 uwq.msg = userfault_msg(vmf->address, vmf->flags, reason,
488 reason, ctx->f !! 490 ctx->features);
489 uwq.ctx = ctx; 491 uwq.ctx = ctx;
490 uwq.waken = false; 492 uwq.waken = false;
491 493
492 blocking_state = userfaultfd_get_block 494 blocking_state = userfaultfd_get_blocking_state(vmf->flags);
493 495
494 /* <<
495 * Take the vma lock now, in order to <<
496 * userfaultfd_huge_must_wait() later. <<
497 * (sleepable) vma lock can modify the <<
498 * must be before explicitly calling s <<
499 */ <<
500 if (is_vm_hugetlb_page(vma)) <<
501 hugetlb_vma_lock_read(vma); <<
502 <<
503 spin_lock_irq(&ctx->fault_pending_wqh. 496 spin_lock_irq(&ctx->fault_pending_wqh.lock);
504 /* 497 /*
505 * After the __add_wait_queue the uwq 498 * After the __add_wait_queue the uwq is visible to userland
506 * through poll/read(). 499 * through poll/read().
507 */ 500 */
508 __add_wait_queue(&ctx->fault_pending_w 501 __add_wait_queue(&ctx->fault_pending_wqh, &uwq.wq);
509 /* 502 /*
510 * The smp_mb() after __set_current_st 503 * The smp_mb() after __set_current_state prevents the reads
511 * following the spin_unlock to happen 504 * following the spin_unlock to happen before the list_add in
512 * __add_wait_queue. 505 * __add_wait_queue.
513 */ 506 */
514 set_current_state(blocking_state); 507 set_current_state(blocking_state);
515 spin_unlock_irq(&ctx->fault_pending_wq 508 spin_unlock_irq(&ctx->fault_pending_wqh.lock);
516 509
517 if (!is_vm_hugetlb_page(vma)) !! 510 if (!is_vm_hugetlb_page(vmf->vma))
518 must_wait = userfaultfd_must_w !! 511 must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
>> 512 reason);
519 else 513 else
520 must_wait = userfaultfd_huge_m !! 514 must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma,
521 if (is_vm_hugetlb_page(vma)) !! 515 vmf->address,
522 hugetlb_vma_unlock_read(vma); !! 516 vmf->flags, reason);
523 release_fault_lock(vmf); !! 517 up_read(&mm->mmap_sem);
524 518
525 if (likely(must_wait && !READ_ONCE(ctx !! 519 if (likely(must_wait && !READ_ONCE(ctx->released) &&
>> 520 !userfaultfd_signal_pending(vmf->flags))) {
526 wake_up_poll(&ctx->fd_wqh, EPO 521 wake_up_poll(&ctx->fd_wqh, EPOLLIN);
527 schedule(); 522 schedule();
>> 523 ret |= VM_FAULT_MAJOR;
>> 524
>> 525 /*
>> 526 * False wakeups can orginate even from rwsem before
>> 527 * up_read() however userfaults will wait either for a
>> 528 * targeted wakeup on the specific uwq waitqueue from
>> 529 * wake_userfault() or for signals or for uffd
>> 530 * release.
>> 531 */
>> 532 while (!READ_ONCE(uwq.waken)) {
>> 533 /*
>> 534 * This needs the full smp_store_mb()
>> 535 * guarantee as the state write must be
>> 536 * visible to other CPUs before reading
>> 537 * uwq.waken from other CPUs.
>> 538 */
>> 539 set_current_state(blocking_state);
>> 540 if (READ_ONCE(uwq.waken) ||
>> 541 READ_ONCE(ctx->released) ||
>> 542 userfaultfd_signal_pending(vmf->flags))
>> 543 break;
>> 544 schedule();
>> 545 }
528 } 546 }
529 547
530 __set_current_state(TASK_RUNNING); 548 __set_current_state(TASK_RUNNING);
531 549
532 /* 550 /*
533 * Here we race with the list_del; lis 551 * Here we race with the list_del; list_add in
534 * userfaultfd_ctx_read(), however bec 552 * userfaultfd_ctx_read(), however because we don't ever run
535 * list_del_init() to refile across th 553 * list_del_init() to refile across the two lists, the prev
536 * and next pointers will never point 554 * and next pointers will never point to self. list_add also
537 * would never let any of the two poin 555 * would never let any of the two pointers to point to
538 * self. So list_empty_careful won't r 556 * self. So list_empty_careful won't risk to see both pointers
539 * pointing to self at any time during 557 * pointing to self at any time during the list refile. The
540 * only case where list_del_init() is 558 * only case where list_del_init() is called is the full
541 * removal in the wake function and th 559 * removal in the wake function and there we don't re-list_add
542 * and it's fine not to block on the s 560 * and it's fine not to block on the spinlock. The uwq on this
543 * kernel stack can be released after 561 * kernel stack can be released after the list_del_init.
544 */ 562 */
545 if (!list_empty_careful(&uwq.wq.entry) 563 if (!list_empty_careful(&uwq.wq.entry)) {
546 spin_lock_irq(&ctx->fault_pend 564 spin_lock_irq(&ctx->fault_pending_wqh.lock);
547 /* 565 /*
548 * No need of list_del_init(), 566 * No need of list_del_init(), the uwq on the stack
549 * will be freed shortly anywa 567 * will be freed shortly anyway.
550 */ 568 */
551 list_del(&uwq.wq.entry); 569 list_del(&uwq.wq.entry);
552 spin_unlock_irq(&ctx->fault_pe 570 spin_unlock_irq(&ctx->fault_pending_wqh.lock);
553 } 571 }
554 572
555 /* 573 /*
556 * ctx may go away after this if the u 574 * ctx may go away after this if the userfault pseudo fd is
557 * already released. 575 * already released.
558 */ 576 */
559 userfaultfd_ctx_put(ctx); 577 userfaultfd_ctx_put(ctx);
560 578
561 out: 579 out:
562 return ret; 580 return ret;
563 } 581 }
564 582
565 static void userfaultfd_event_wait_completion( 583 static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
566 584 struct userfaultfd_wait_queue *ewq)
567 { 585 {
568 struct userfaultfd_ctx *release_new_ct 586 struct userfaultfd_ctx *release_new_ctx;
569 587
570 if (WARN_ON_ONCE(current->flags & PF_E 588 if (WARN_ON_ONCE(current->flags & PF_EXITING))
571 goto out; 589 goto out;
572 590
573 ewq->ctx = ctx; 591 ewq->ctx = ctx;
574 init_waitqueue_entry(&ewq->wq, current 592 init_waitqueue_entry(&ewq->wq, current);
575 release_new_ctx = NULL; 593 release_new_ctx = NULL;
576 594
577 spin_lock_irq(&ctx->event_wqh.lock); 595 spin_lock_irq(&ctx->event_wqh.lock);
578 /* 596 /*
579 * After the __add_wait_queue the uwq 597 * After the __add_wait_queue the uwq is visible to userland
580 * through poll/read(). 598 * through poll/read().
581 */ 599 */
582 __add_wait_queue(&ctx->event_wqh, &ewq 600 __add_wait_queue(&ctx->event_wqh, &ewq->wq);
583 for (;;) { 601 for (;;) {
584 set_current_state(TASK_KILLABL 602 set_current_state(TASK_KILLABLE);
585 if (ewq->msg.event == 0) 603 if (ewq->msg.event == 0)
586 break; 604 break;
587 if (READ_ONCE(ctx->released) | 605 if (READ_ONCE(ctx->released) ||
588 fatal_signal_pending(curre 606 fatal_signal_pending(current)) {
589 /* 607 /*
590 * &ewq->wq may be que 608 * &ewq->wq may be queued in fork_event, but
591 * __remove_wait_queue 609 * __remove_wait_queue ignores the head
592 * parameter. It would 610 * parameter. It would be a problem if it
593 * didn't. 611 * didn't.
594 */ 612 */
595 __remove_wait_queue(&c 613 __remove_wait_queue(&ctx->event_wqh, &ewq->wq);
596 if (ewq->msg.event == 614 if (ewq->msg.event == UFFD_EVENT_FORK) {
597 struct userfau 615 struct userfaultfd_ctx *new;
598 616
599 new = (struct 617 new = (struct userfaultfd_ctx *)
600 (unsig 618 (unsigned long)
601 ewq->m 619 ewq->msg.arg.reserved.reserved1;
602 release_new_ct 620 release_new_ctx = new;
603 } 621 }
604 break; 622 break;
605 } 623 }
606 624
607 spin_unlock_irq(&ctx->event_wq 625 spin_unlock_irq(&ctx->event_wqh.lock);
608 626
609 wake_up_poll(&ctx->fd_wqh, EPO 627 wake_up_poll(&ctx->fd_wqh, EPOLLIN);
610 schedule(); 628 schedule();
611 629
612 spin_lock_irq(&ctx->event_wqh. 630 spin_lock_irq(&ctx->event_wqh.lock);
613 } 631 }
614 __set_current_state(TASK_RUNNING); 632 __set_current_state(TASK_RUNNING);
615 spin_unlock_irq(&ctx->event_wqh.lock); 633 spin_unlock_irq(&ctx->event_wqh.lock);
616 634
617 if (release_new_ctx) { 635 if (release_new_ctx) {
618 struct vm_area_struct *vma; 636 struct vm_area_struct *vma;
619 struct mm_struct *mm = release 637 struct mm_struct *mm = release_new_ctx->mm;
620 VMA_ITERATOR(vmi, mm, 0); <<
621 638
622 /* the various vma->vm_userfau 639 /* the various vma->vm_userfaultfd_ctx still points to it */
623 mmap_write_lock(mm); !! 640 down_write(&mm->mmap_sem);
624 for_each_vma(vmi, vma) { !! 641 /* no task can run (and in turn coredump) yet */
>> 642 VM_WARN_ON(!mmget_still_valid(mm));
>> 643 for (vma = mm->mmap; vma; vma = vma->vm_next)
625 if (vma->vm_userfaultf 644 if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) {
626 vma_start_writ <<
627 vma->vm_userfa 645 vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
628 userfaultfd_se !! 646 vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
629 <<
630 } 647 }
631 } !! 648 up_write(&mm->mmap_sem);
632 mmap_write_unlock(mm); <<
633 649
634 userfaultfd_ctx_put(release_ne 650 userfaultfd_ctx_put(release_new_ctx);
635 } 651 }
636 652
637 /* 653 /*
638 * ctx may go away after this if the u 654 * ctx may go away after this if the userfault pseudo fd is
639 * already released. 655 * already released.
640 */ 656 */
641 out: 657 out:
642 atomic_dec(&ctx->mmap_changing); !! 658 WRITE_ONCE(ctx->mmap_changing, false);
643 VM_BUG_ON(atomic_read(&ctx->mmap_chang <<
644 userfaultfd_ctx_put(ctx); 659 userfaultfd_ctx_put(ctx);
645 } 660 }
646 661
647 static void userfaultfd_event_complete(struct 662 static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx,
648 struct 663 struct userfaultfd_wait_queue *ewq)
649 { 664 {
650 ewq->msg.event = 0; 665 ewq->msg.event = 0;
651 wake_up_locked(&ctx->event_wqh); 666 wake_up_locked(&ctx->event_wqh);
652 __remove_wait_queue(&ctx->event_wqh, & 667 __remove_wait_queue(&ctx->event_wqh, &ewq->wq);
653 } 668 }
654 669
655 int dup_userfaultfd(struct vm_area_struct *vma 670 int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
656 { 671 {
657 struct userfaultfd_ctx *ctx = NULL, *o 672 struct userfaultfd_ctx *ctx = NULL, *octx;
658 struct userfaultfd_fork_ctx *fctx; 673 struct userfaultfd_fork_ctx *fctx;
659 674
660 octx = vma->vm_userfaultfd_ctx.ctx; 675 octx = vma->vm_userfaultfd_ctx.ctx;
661 if (!octx) !! 676 if (!octx || !(octx->features & UFFD_FEATURE_EVENT_FORK)) {
662 return 0; <<
663 <<
664 if (!(octx->features & UFFD_FEATURE_EV <<
665 vma_start_write(vma); <<
666 vma->vm_userfaultfd_ctx = NULL 677 vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
667 userfaultfd_set_vm_flags(vma, !! 678 vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
668 return 0; 679 return 0;
669 } 680 }
670 681
671 list_for_each_entry(fctx, fcs, list) 682 list_for_each_entry(fctx, fcs, list)
672 if (fctx->orig == octx) { 683 if (fctx->orig == octx) {
673 ctx = fctx->new; 684 ctx = fctx->new;
674 break; 685 break;
675 } 686 }
676 687
677 if (!ctx) { 688 if (!ctx) {
678 fctx = kmalloc(sizeof(*fctx), 689 fctx = kmalloc(sizeof(*fctx), GFP_KERNEL);
679 if (!fctx) 690 if (!fctx)
680 return -ENOMEM; 691 return -ENOMEM;
681 692
682 ctx = kmem_cache_alloc(userfau 693 ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL);
683 if (!ctx) { 694 if (!ctx) {
684 kfree(fctx); 695 kfree(fctx);
685 return -ENOMEM; 696 return -ENOMEM;
686 } 697 }
687 698
688 refcount_set(&ctx->refcount, 1 699 refcount_set(&ctx->refcount, 1);
689 ctx->flags = octx->flags; 700 ctx->flags = octx->flags;
>> 701 ctx->state = UFFD_STATE_RUNNING;
690 ctx->features = octx->features 702 ctx->features = octx->features;
691 ctx->released = false; 703 ctx->released = false;
692 init_rwsem(&ctx->map_changing_ !! 704 ctx->mmap_changing = false;
693 atomic_set(&ctx->mmap_changing <<
694 ctx->mm = vma->vm_mm; 705 ctx->mm = vma->vm_mm;
695 mmgrab(ctx->mm); 706 mmgrab(ctx->mm);
696 707
697 userfaultfd_ctx_get(octx); 708 userfaultfd_ctx_get(octx);
698 down_write(&octx->map_changing !! 709 WRITE_ONCE(octx->mmap_changing, true);
699 atomic_inc(&octx->mmap_changin <<
700 up_write(&octx->map_changing_l <<
701 fctx->orig = octx; 710 fctx->orig = octx;
702 fctx->new = ctx; 711 fctx->new = ctx;
703 list_add_tail(&fctx->list, fcs 712 list_add_tail(&fctx->list, fcs);
704 } 713 }
705 714
706 vma->vm_userfaultfd_ctx.ctx = ctx; 715 vma->vm_userfaultfd_ctx.ctx = ctx;
707 return 0; 716 return 0;
708 } 717 }
709 718
710 static void dup_fctx(struct userfaultfd_fork_c 719 static void dup_fctx(struct userfaultfd_fork_ctx *fctx)
711 { 720 {
712 struct userfaultfd_ctx *ctx = fctx->or 721 struct userfaultfd_ctx *ctx = fctx->orig;
713 struct userfaultfd_wait_queue ewq; 722 struct userfaultfd_wait_queue ewq;
714 723
715 msg_init(&ewq.msg); 724 msg_init(&ewq.msg);
716 725
717 ewq.msg.event = UFFD_EVENT_FORK; 726 ewq.msg.event = UFFD_EVENT_FORK;
718 ewq.msg.arg.reserved.reserved1 = (unsi 727 ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new;
719 728
720 userfaultfd_event_wait_completion(ctx, 729 userfaultfd_event_wait_completion(ctx, &ewq);
721 } 730 }
722 731
723 void dup_userfaultfd_complete(struct list_head 732 void dup_userfaultfd_complete(struct list_head *fcs)
724 { 733 {
725 struct userfaultfd_fork_ctx *fctx, *n; 734 struct userfaultfd_fork_ctx *fctx, *n;
726 735
727 list_for_each_entry_safe(fctx, n, fcs, 736 list_for_each_entry_safe(fctx, n, fcs, list) {
728 dup_fctx(fctx); 737 dup_fctx(fctx);
729 list_del(&fctx->list); 738 list_del(&fctx->list);
730 kfree(fctx); 739 kfree(fctx);
731 } 740 }
732 } 741 }
733 742
734 void mremap_userfaultfd_prep(struct vm_area_st 743 void mremap_userfaultfd_prep(struct vm_area_struct *vma,
735 struct vm_userfau 744 struct vm_userfaultfd_ctx *vm_ctx)
736 { 745 {
737 struct userfaultfd_ctx *ctx; 746 struct userfaultfd_ctx *ctx;
738 747
739 ctx = vma->vm_userfaultfd_ctx.ctx; 748 ctx = vma->vm_userfaultfd_ctx.ctx;
740 749
741 if (!ctx) 750 if (!ctx)
742 return; 751 return;
743 752
744 if (ctx->features & UFFD_FEATURE_EVENT 753 if (ctx->features & UFFD_FEATURE_EVENT_REMAP) {
745 vm_ctx->ctx = ctx; 754 vm_ctx->ctx = ctx;
746 userfaultfd_ctx_get(ctx); 755 userfaultfd_ctx_get(ctx);
747 down_write(&ctx->map_changing_ !! 756 WRITE_ONCE(ctx->mmap_changing, true);
748 atomic_inc(&ctx->mmap_changing <<
749 up_write(&ctx->map_changing_lo <<
750 } else { 757 } else {
751 /* Drop uffd context if remap 758 /* Drop uffd context if remap feature not enabled */
752 vma_start_write(vma); <<
753 vma->vm_userfaultfd_ctx = NULL 759 vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
754 userfaultfd_set_vm_flags(vma, !! 760 vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
755 } 761 }
756 } 762 }
757 763
758 void mremap_userfaultfd_complete(struct vm_use 764 void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx,
759 unsigned long 765 unsigned long from, unsigned long to,
760 unsigned long 766 unsigned long len)
761 { 767 {
762 struct userfaultfd_ctx *ctx = vm_ctx-> 768 struct userfaultfd_ctx *ctx = vm_ctx->ctx;
763 struct userfaultfd_wait_queue ewq; 769 struct userfaultfd_wait_queue ewq;
764 770
765 if (!ctx) 771 if (!ctx)
766 return; 772 return;
767 773
768 if (to & ~PAGE_MASK) { 774 if (to & ~PAGE_MASK) {
769 userfaultfd_ctx_put(ctx); 775 userfaultfd_ctx_put(ctx);
770 return; 776 return;
771 } 777 }
772 778
773 msg_init(&ewq.msg); 779 msg_init(&ewq.msg);
774 780
775 ewq.msg.event = UFFD_EVENT_REMAP; 781 ewq.msg.event = UFFD_EVENT_REMAP;
776 ewq.msg.arg.remap.from = from; 782 ewq.msg.arg.remap.from = from;
777 ewq.msg.arg.remap.to = to; 783 ewq.msg.arg.remap.to = to;
778 ewq.msg.arg.remap.len = len; 784 ewq.msg.arg.remap.len = len;
779 785
780 userfaultfd_event_wait_completion(ctx, 786 userfaultfd_event_wait_completion(ctx, &ewq);
781 } 787 }
782 788
783 bool userfaultfd_remove(struct vm_area_struct 789 bool userfaultfd_remove(struct vm_area_struct *vma,
784 unsigned long start, u 790 unsigned long start, unsigned long end)
785 { 791 {
786 struct mm_struct *mm = vma->vm_mm; 792 struct mm_struct *mm = vma->vm_mm;
787 struct userfaultfd_ctx *ctx; 793 struct userfaultfd_ctx *ctx;
788 struct userfaultfd_wait_queue ewq; 794 struct userfaultfd_wait_queue ewq;
789 795
790 ctx = vma->vm_userfaultfd_ctx.ctx; 796 ctx = vma->vm_userfaultfd_ctx.ctx;
791 if (!ctx || !(ctx->features & UFFD_FEA 797 if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_REMOVE))
792 return true; 798 return true;
793 799
794 userfaultfd_ctx_get(ctx); 800 userfaultfd_ctx_get(ctx);
795 down_write(&ctx->map_changing_lock); !! 801 WRITE_ONCE(ctx->mmap_changing, true);
796 atomic_inc(&ctx->mmap_changing); !! 802 up_read(&mm->mmap_sem);
797 up_write(&ctx->map_changing_lock); <<
798 mmap_read_unlock(mm); <<
799 803
800 msg_init(&ewq.msg); 804 msg_init(&ewq.msg);
801 805
802 ewq.msg.event = UFFD_EVENT_REMOVE; 806 ewq.msg.event = UFFD_EVENT_REMOVE;
803 ewq.msg.arg.remove.start = start; 807 ewq.msg.arg.remove.start = start;
804 ewq.msg.arg.remove.end = end; 808 ewq.msg.arg.remove.end = end;
805 809
806 userfaultfd_event_wait_completion(ctx, 810 userfaultfd_event_wait_completion(ctx, &ewq);
807 811
808 return false; 812 return false;
809 } 813 }
810 814
811 static bool has_unmap_ctx(struct userfaultfd_c 815 static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps,
812 unsigned long start, 816 unsigned long start, unsigned long end)
813 { 817 {
814 struct userfaultfd_unmap_ctx *unmap_ct 818 struct userfaultfd_unmap_ctx *unmap_ctx;
815 819
816 list_for_each_entry(unmap_ctx, unmaps, 820 list_for_each_entry(unmap_ctx, unmaps, list)
817 if (unmap_ctx->ctx == ctx && u 821 if (unmap_ctx->ctx == ctx && unmap_ctx->start == start &&
818 unmap_ctx->end == end) 822 unmap_ctx->end == end)
819 return true; 823 return true;
820 824
821 return false; 825 return false;
822 } 826 }
823 827
824 int userfaultfd_unmap_prep(struct vm_area_stru !! 828 int userfaultfd_unmap_prep(struct vm_area_struct *vma,
825 unsigned long end, !! 829 unsigned long start, unsigned long end,
826 { !! 830 struct list_head *unmaps)
827 struct userfaultfd_unmap_ctx *unmap_ct !! 831 {
828 struct userfaultfd_ctx *ctx = vma->vm_ !! 832 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
>> 833 struct userfaultfd_unmap_ctx *unmap_ctx;
>> 834 struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
829 835
830 if (!ctx || !(ctx->features & UFFD_FEA !! 836 if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) ||
831 has_unmap_ctx(ctx, unmaps, start, !! 837 has_unmap_ctx(ctx, unmaps, start, end))
832 return 0; !! 838 continue;
833 839
834 unmap_ctx = kzalloc(sizeof(*unmap_ctx) !! 840 unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL);
835 if (!unmap_ctx) !! 841 if (!unmap_ctx)
836 return -ENOMEM; !! 842 return -ENOMEM;
837 843
838 userfaultfd_ctx_get(ctx); !! 844 userfaultfd_ctx_get(ctx);
839 down_write(&ctx->map_changing_lock); !! 845 WRITE_ONCE(ctx->mmap_changing, true);
840 atomic_inc(&ctx->mmap_changing); !! 846 unmap_ctx->ctx = ctx;
841 up_write(&ctx->map_changing_lock); !! 847 unmap_ctx->start = start;
842 unmap_ctx->ctx = ctx; !! 848 unmap_ctx->end = end;
843 unmap_ctx->start = start; !! 849 list_add_tail(&unmap_ctx->list, unmaps);
844 unmap_ctx->end = end; !! 850 }
845 list_add_tail(&unmap_ctx->list, unmaps <<
846 851
847 return 0; 852 return 0;
848 } 853 }
849 854
850 void userfaultfd_unmap_complete(struct mm_stru 855 void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf)
851 { 856 {
852 struct userfaultfd_unmap_ctx *ctx, *n; 857 struct userfaultfd_unmap_ctx *ctx, *n;
853 struct userfaultfd_wait_queue ewq; 858 struct userfaultfd_wait_queue ewq;
854 859
855 list_for_each_entry_safe(ctx, n, uf, l 860 list_for_each_entry_safe(ctx, n, uf, list) {
856 msg_init(&ewq.msg); 861 msg_init(&ewq.msg);
857 862
858 ewq.msg.event = UFFD_EVENT_UNM 863 ewq.msg.event = UFFD_EVENT_UNMAP;
859 ewq.msg.arg.remove.start = ctx 864 ewq.msg.arg.remove.start = ctx->start;
860 ewq.msg.arg.remove.end = ctx-> 865 ewq.msg.arg.remove.end = ctx->end;
861 866
862 userfaultfd_event_wait_complet 867 userfaultfd_event_wait_completion(ctx->ctx, &ewq);
863 868
864 list_del(&ctx->list); 869 list_del(&ctx->list);
865 kfree(ctx); 870 kfree(ctx);
866 } 871 }
867 } 872 }
868 873
869 static int userfaultfd_release(struct inode *i 874 static int userfaultfd_release(struct inode *inode, struct file *file)
870 { 875 {
871 struct userfaultfd_ctx *ctx = file->pr 876 struct userfaultfd_ctx *ctx = file->private_data;
872 struct mm_struct *mm = ctx->mm; 877 struct mm_struct *mm = ctx->mm;
873 struct vm_area_struct *vma, *prev; 878 struct vm_area_struct *vma, *prev;
874 /* len == 0 means wake all */ 879 /* len == 0 means wake all */
875 struct userfaultfd_wake_range range = 880 struct userfaultfd_wake_range range = { .len = 0, };
876 unsigned long new_flags; 881 unsigned long new_flags;
877 VMA_ITERATOR(vmi, mm, 0); !! 882 bool still_valid;
878 883
879 WRITE_ONCE(ctx->released, true); 884 WRITE_ONCE(ctx->released, true);
880 885
881 if (!mmget_not_zero(mm)) 886 if (!mmget_not_zero(mm))
882 goto wakeup; 887 goto wakeup;
883 888
884 /* 889 /*
885 * Flush page faults out of all CPUs. 890 * Flush page faults out of all CPUs. NOTE: all page faults
886 * must be retried without returning V 891 * must be retried without returning VM_FAULT_SIGBUS if
887 * userfaultfd_ctx_get() succeeds but 892 * userfaultfd_ctx_get() succeeds but vma->vma_userfault_ctx
888 * changes while handle_userfault rele !! 893 * changes while handle_userfault released the mmap_sem. So
889 * it's critical that released is set 894 * it's critical that released is set to true (above), before
890 * taking the mmap_lock for writing. !! 895 * taking the mmap_sem for writing.
891 */ 896 */
892 mmap_write_lock(mm); !! 897 down_write(&mm->mmap_sem);
>> 898 still_valid = mmget_still_valid(mm);
893 prev = NULL; 899 prev = NULL;
894 for_each_vma(vmi, vma) { !! 900 for (vma = mm->mmap; vma; vma = vma->vm_next) {
895 cond_resched(); 901 cond_resched();
896 BUG_ON(!!vma->vm_userfaultfd_c 902 BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^
897 !!(vma->vm_flags & __VM !! 903 !!(vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP)));
898 if (vma->vm_userfaultfd_ctx.ct 904 if (vma->vm_userfaultfd_ctx.ctx != ctx) {
899 prev = vma; 905 prev = vma;
900 continue; 906 continue;
901 } 907 }
902 /* Reset ptes for the whole vm !! 908 new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP);
903 if (userfaultfd_wp(vma)) !! 909 if (still_valid) {
904 uffd_wp_range(vma, vma !! 910 prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end,
905 vma->vm_ !! 911 new_flags, vma->anon_vma,
906 new_flags = vma->vm_flags & ~_ !! 912 vma->vm_file, vma->vm_pgoff,
907 vma = vma_modify_flags_uffd(&v !! 913 vma_policy(vma),
908 vm !! 914 NULL_VM_UFFD_CTX);
909 NU !! 915 if (prev)
910 !! 916 vma = prev;
911 vma_start_write(vma); !! 917 else
912 userfaultfd_set_vm_flags(vma, !! 918 prev = vma;
>> 919 }
>> 920 vma->vm_flags = new_flags;
913 vma->vm_userfaultfd_ctx = NULL 921 vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
914 <<
915 prev = vma; <<
916 } 922 }
917 mmap_write_unlock(mm); !! 923 up_write(&mm->mmap_sem);
918 mmput(mm); 924 mmput(mm);
919 wakeup: 925 wakeup:
920 /* 926 /*
921 * After no new page faults can wait o 927 * After no new page faults can wait on this fault_*wqh, flush
922 * the last page faults that may have 928 * the last page faults that may have been already waiting on
923 * the fault_*wqh. 929 * the fault_*wqh.
924 */ 930 */
925 spin_lock_irq(&ctx->fault_pending_wqh. 931 spin_lock_irq(&ctx->fault_pending_wqh.lock);
926 __wake_up_locked_key(&ctx->fault_pendi 932 __wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range);
927 __wake_up(&ctx->fault_wqh, TASK_NORMAL 933 __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range);
928 spin_unlock_irq(&ctx->fault_pending_wq 934 spin_unlock_irq(&ctx->fault_pending_wqh.lock);
929 935
930 /* Flush pending events that may still 936 /* Flush pending events that may still wait on event_wqh */
931 wake_up_all(&ctx->event_wqh); 937 wake_up_all(&ctx->event_wqh);
932 938
933 wake_up_poll(&ctx->fd_wqh, EPOLLHUP); 939 wake_up_poll(&ctx->fd_wqh, EPOLLHUP);
934 userfaultfd_ctx_put(ctx); 940 userfaultfd_ctx_put(ctx);
935 return 0; 941 return 0;
936 } 942 }
937 943
938 /* fault_pending_wqh.lock must be hold by the 944 /* fault_pending_wqh.lock must be hold by the caller */
939 static inline struct userfaultfd_wait_queue *f 945 static inline struct userfaultfd_wait_queue *find_userfault_in(
940 wait_queue_head_t *wqh) 946 wait_queue_head_t *wqh)
941 { 947 {
942 wait_queue_entry_t *wq; 948 wait_queue_entry_t *wq;
943 struct userfaultfd_wait_queue *uwq; 949 struct userfaultfd_wait_queue *uwq;
944 950
945 lockdep_assert_held(&wqh->lock); 951 lockdep_assert_held(&wqh->lock);
946 952
947 uwq = NULL; 953 uwq = NULL;
948 if (!waitqueue_active(wqh)) 954 if (!waitqueue_active(wqh))
949 goto out; 955 goto out;
950 /* walk in reverse to provide FIFO beh 956 /* walk in reverse to provide FIFO behavior to read userfaults */
951 wq = list_last_entry(&wqh->head, typeo 957 wq = list_last_entry(&wqh->head, typeof(*wq), entry);
952 uwq = container_of(wq, struct userfaul 958 uwq = container_of(wq, struct userfaultfd_wait_queue, wq);
953 out: 959 out:
954 return uwq; 960 return uwq;
955 } 961 }
956 962
957 static inline struct userfaultfd_wait_queue *f 963 static inline struct userfaultfd_wait_queue *find_userfault(
958 struct userfaultfd_ctx *ctx) 964 struct userfaultfd_ctx *ctx)
959 { 965 {
960 return find_userfault_in(&ctx->fault_p 966 return find_userfault_in(&ctx->fault_pending_wqh);
961 } 967 }
962 968
963 static inline struct userfaultfd_wait_queue *f 969 static inline struct userfaultfd_wait_queue *find_userfault_evt(
964 struct userfaultfd_ctx *ctx) 970 struct userfaultfd_ctx *ctx)
965 { 971 {
966 return find_userfault_in(&ctx->event_w 972 return find_userfault_in(&ctx->event_wqh);
967 } 973 }
968 974
969 static __poll_t userfaultfd_poll(struct file * 975 static __poll_t userfaultfd_poll(struct file *file, poll_table *wait)
970 { 976 {
971 struct userfaultfd_ctx *ctx = file->pr 977 struct userfaultfd_ctx *ctx = file->private_data;
972 __poll_t ret; 978 __poll_t ret;
973 979
974 poll_wait(file, &ctx->fd_wqh, wait); 980 poll_wait(file, &ctx->fd_wqh, wait);
975 981
976 if (!userfaultfd_is_initialized(ctx)) !! 982 switch (ctx->state) {
>> 983 case UFFD_STATE_WAIT_API:
977 return EPOLLERR; 984 return EPOLLERR;
>> 985 case UFFD_STATE_RUNNING:
>> 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)))
>> 991 return EPOLLERR;
>> 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))
>> 1005 ret = EPOLLIN;
>> 1006 else if (waitqueue_active(&ctx->event_wqh))
>> 1007 ret = EPOLLIN;
978 1008
979 /* !! 1009 return ret;
980 * poll() never guarantees that read w !! 1010 default:
981 * userfaults can be waken before they !! 1011 WARN_ON_ONCE(1);
982 */ <<
983 if (unlikely(!(file->f_flags & O_NONBL <<
984 return EPOLLERR; 1012 return EPOLLERR;
985 /* !! 1013 }
986 * lockless access to see if there are <<
987 * __pollwait last action is the add_w <<
988 * the spin_unlock would allow the wai <<
989 * pass above the actual list_add insi <<
990 * add_wait_queue critical section. So <<
991 * memory barrier to serialize the lis <<
992 * add_wait_queue() with the waitqueue <<
993 * below. <<
994 */ <<
995 ret = 0; <<
996 smp_mb(); <<
997 if (waitqueue_active(&ctx->fault_pendi <<
998 ret = EPOLLIN; <<
999 else if (waitqueue_active(&ctx->event_ <<
1000 ret = EPOLLIN; <<
1001 <<
1002 return ret; <<
1003 } 1014 }
1004 1015
1005 static const struct file_operations userfault 1016 static const struct file_operations userfaultfd_fops;
1006 1017
1007 static int resolve_userfault_fork(struct user !! 1018 static int resolve_userfault_fork(struct userfaultfd_ctx *ctx,
1008 struct inod !! 1019 struct userfaultfd_ctx *new,
1009 struct uffd 1020 struct uffd_msg *msg)
1010 { 1021 {
1011 int fd; 1022 int fd;
1012 1023
1013 fd = anon_inode_create_getfd("[userfa !! 1024 fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new,
1014 O_RDONLY | (new->flag !! 1025 O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS));
1015 if (fd < 0) 1026 if (fd < 0)
1016 return fd; 1027 return fd;
1017 1028
1018 msg->arg.reserved.reserved1 = 0; 1029 msg->arg.reserved.reserved1 = 0;
1019 msg->arg.fork.ufd = fd; 1030 msg->arg.fork.ufd = fd;
1020 return 0; 1031 return 0;
1021 } 1032 }
1022 1033
1023 static ssize_t userfaultfd_ctx_read(struct us 1034 static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
1024 struct uf !! 1035 struct uffd_msg *msg)
1025 { 1036 {
1026 ssize_t ret; 1037 ssize_t ret;
1027 DECLARE_WAITQUEUE(wait, current); 1038 DECLARE_WAITQUEUE(wait, current);
1028 struct userfaultfd_wait_queue *uwq; 1039 struct userfaultfd_wait_queue *uwq;
1029 /* 1040 /*
1030 * Handling fork event requires sleep 1041 * Handling fork event requires sleeping operations, so
1031 * we drop the event_wqh lock, then d 1042 * we drop the event_wqh lock, then do these ops, then
1032 * lock it back and wake up the waite 1043 * lock it back and wake up the waiter. While the lock is
1033 * dropped the ewq may go away so we 1044 * dropped the ewq may go away so we keep track of it
1034 * carefully. 1045 * carefully.
1035 */ 1046 */
1036 LIST_HEAD(fork_event); 1047 LIST_HEAD(fork_event);
1037 struct userfaultfd_ctx *fork_nctx = N 1048 struct userfaultfd_ctx *fork_nctx = NULL;
1038 1049
1039 /* always take the fd_wqh lock before 1050 /* always take the fd_wqh lock before the fault_pending_wqh lock */
1040 spin_lock_irq(&ctx->fd_wqh.lock); 1051 spin_lock_irq(&ctx->fd_wqh.lock);
1041 __add_wait_queue(&ctx->fd_wqh, &wait) 1052 __add_wait_queue(&ctx->fd_wqh, &wait);
1042 for (;;) { 1053 for (;;) {
1043 set_current_state(TASK_INTERR 1054 set_current_state(TASK_INTERRUPTIBLE);
1044 spin_lock(&ctx->fault_pending 1055 spin_lock(&ctx->fault_pending_wqh.lock);
1045 uwq = find_userfault(ctx); 1056 uwq = find_userfault(ctx);
1046 if (uwq) { 1057 if (uwq) {
1047 /* 1058 /*
1048 * Use a seqcount to 1059 * Use a seqcount to repeat the lockless check
1049 * in wake_userfault( 1060 * in wake_userfault() to avoid missing
1050 * wakeups because du 1061 * wakeups because during the refile both
1051 * waitqueue could be 1062 * waitqueue could become empty if this is the
1052 * only userfault. 1063 * only userfault.
1053 */ 1064 */
1054 write_seqcount_begin( 1065 write_seqcount_begin(&ctx->refile_seq);
1055 1066
1056 /* 1067 /*
1057 * The fault_pending_ 1068 * The fault_pending_wqh.lock prevents the uwq
1058 * to disappear from 1069 * to disappear from under us.
1059 * 1070 *
1060 * Refile this userfa 1071 * Refile this userfault from
1061 * fault_pending_wqh 1072 * fault_pending_wqh to fault_wqh, it's not
1062 * pending anymore af 1073 * pending anymore after we read it.
1063 * 1074 *
1064 * Use list_del() by 1075 * Use list_del() by hand (as
1065 * userfaultfd_wake_f 1076 * userfaultfd_wake_function also uses
1066 * list_del_init() by 1077 * list_del_init() by hand) to be sure nobody
1067 * changes __remove_w 1078 * changes __remove_wait_queue() to use
1068 * list_del_init() in 1079 * list_del_init() in turn breaking the
1069 * !list_empty_carefu 1080 * !list_empty_careful() check in
1070 * handle_userfault() 1081 * handle_userfault(). The uwq->wq.head list
1071 * must never be empt 1082 * must never be empty at any time during the
1072 * refile, or the wai 1083 * refile, or the waitqueue could disappear
1073 * from under us. The 1084 * from under us. The "wait_queue_head_t"
1074 * parameter of __rem 1085 * parameter of __remove_wait_queue() is unused
1075 * anyway. 1086 * anyway.
1076 */ 1087 */
1077 list_del(&uwq->wq.ent 1088 list_del(&uwq->wq.entry);
1078 add_wait_queue(&ctx-> 1089 add_wait_queue(&ctx->fault_wqh, &uwq->wq);
1079 1090
1080 write_seqcount_end(&c 1091 write_seqcount_end(&ctx->refile_seq);
1081 1092
1082 /* careful to always 1093 /* careful to always initialize msg if ret == 0 */
1083 *msg = uwq->msg; 1094 *msg = uwq->msg;
1084 spin_unlock(&ctx->fau 1095 spin_unlock(&ctx->fault_pending_wqh.lock);
1085 ret = 0; 1096 ret = 0;
1086 break; 1097 break;
1087 } 1098 }
1088 spin_unlock(&ctx->fault_pendi 1099 spin_unlock(&ctx->fault_pending_wqh.lock);
1089 1100
1090 spin_lock(&ctx->event_wqh.loc 1101 spin_lock(&ctx->event_wqh.lock);
1091 uwq = find_userfault_evt(ctx) 1102 uwq = find_userfault_evt(ctx);
1092 if (uwq) { 1103 if (uwq) {
1093 *msg = uwq->msg; 1104 *msg = uwq->msg;
1094 1105
1095 if (uwq->msg.event == 1106 if (uwq->msg.event == UFFD_EVENT_FORK) {
1096 fork_nctx = ( 1107 fork_nctx = (struct userfaultfd_ctx *)
1097 (unsi 1108 (unsigned long)
1098 uwq-> 1109 uwq->msg.arg.reserved.reserved1;
1099 list_move(&uw 1110 list_move(&uwq->wq.entry, &fork_event);
1100 /* 1111 /*
1101 * fork_nctx 1112 * fork_nctx can be freed as soon as
1102 * we drop th 1113 * we drop the lock, unless we take a
1103 * reference 1114 * reference on it.
1104 */ 1115 */
1105 userfaultfd_c 1116 userfaultfd_ctx_get(fork_nctx);
1106 spin_unlock(& 1117 spin_unlock(&ctx->event_wqh.lock);
1107 ret = 0; 1118 ret = 0;
1108 break; 1119 break;
1109 } 1120 }
1110 1121
1111 userfaultfd_event_com 1122 userfaultfd_event_complete(ctx, uwq);
1112 spin_unlock(&ctx->eve 1123 spin_unlock(&ctx->event_wqh.lock);
1113 ret = 0; 1124 ret = 0;
1114 break; 1125 break;
1115 } 1126 }
1116 spin_unlock(&ctx->event_wqh.l 1127 spin_unlock(&ctx->event_wqh.lock);
1117 1128
1118 if (signal_pending(current)) 1129 if (signal_pending(current)) {
1119 ret = -ERESTARTSYS; 1130 ret = -ERESTARTSYS;
1120 break; 1131 break;
1121 } 1132 }
1122 if (no_wait) { 1133 if (no_wait) {
1123 ret = -EAGAIN; 1134 ret = -EAGAIN;
1124 break; 1135 break;
1125 } 1136 }
1126 spin_unlock_irq(&ctx->fd_wqh. 1137 spin_unlock_irq(&ctx->fd_wqh.lock);
1127 schedule(); 1138 schedule();
1128 spin_lock_irq(&ctx->fd_wqh.lo 1139 spin_lock_irq(&ctx->fd_wqh.lock);
1129 } 1140 }
1130 __remove_wait_queue(&ctx->fd_wqh, &wa 1141 __remove_wait_queue(&ctx->fd_wqh, &wait);
1131 __set_current_state(TASK_RUNNING); 1142 __set_current_state(TASK_RUNNING);
1132 spin_unlock_irq(&ctx->fd_wqh.lock); 1143 spin_unlock_irq(&ctx->fd_wqh.lock);
1133 1144
1134 if (!ret && msg->event == UFFD_EVENT_ 1145 if (!ret && msg->event == UFFD_EVENT_FORK) {
1135 ret = resolve_userfault_fork( !! 1146 ret = resolve_userfault_fork(ctx, fork_nctx, msg);
1136 spin_lock_irq(&ctx->event_wqh 1147 spin_lock_irq(&ctx->event_wqh.lock);
1137 if (!list_empty(&fork_event)) 1148 if (!list_empty(&fork_event)) {
1138 /* 1149 /*
1139 * The fork thread di 1150 * The fork thread didn't abort, so we can
1140 * drop the temporary 1151 * drop the temporary refcount.
1141 */ 1152 */
1142 userfaultfd_ctx_put(f 1153 userfaultfd_ctx_put(fork_nctx);
1143 1154
1144 uwq = list_first_entr 1155 uwq = list_first_entry(&fork_event,
1145 1156 typeof(*uwq),
1146 1157 wq.entry);
1147 /* 1158 /*
1148 * If fork_event list 1159 * If fork_event list wasn't empty and in turn
1149 * the event wasn't a 1160 * the event wasn't already released by fork
1150 * (the event is allo 1161 * (the event is allocated on fork kernel
1151 * stack), put the ev 1162 * stack), put the event back to its place in
1152 * the event_wq. fork 1163 * the event_wq. fork_event head will be freed
1153 * as soon as we retu 1164 * as soon as we return so the event cannot
1154 * stay queued there 1165 * stay queued there no matter the current
1155 * "ret" value. 1166 * "ret" value.
1156 */ 1167 */
1157 list_del(&uwq->wq.ent 1168 list_del(&uwq->wq.entry);
1158 __add_wait_queue(&ctx 1169 __add_wait_queue(&ctx->event_wqh, &uwq->wq);
1159 1170
1160 /* 1171 /*
1161 * Leave the event in 1172 * Leave the event in the waitqueue and report
1162 * error to userland 1173 * error to userland if we failed to resolve
1163 * the userfault fork 1174 * the userfault fork.
1164 */ 1175 */
1165 if (likely(!ret)) 1176 if (likely(!ret))
1166 userfaultfd_e 1177 userfaultfd_event_complete(ctx, uwq);
1167 } else { 1178 } else {
1168 /* 1179 /*
1169 * Here the fork thre 1180 * Here the fork thread aborted and the
1170 * refcount from the 1181 * refcount from the fork thread on fork_nctx
1171 * has already been r 1182 * has already been released. We still hold
1172 * the reference we t 1183 * the reference we took before releasing the
1173 * lock above. If res 1184 * lock above. If resolve_userfault_fork
1174 * failed we've to dr 1185 * failed we've to drop it because the
1175 * fork_nctx has to b 1186 * fork_nctx has to be freed in such case. If
1176 * it succeeded we'll 1187 * it succeeded we'll hold it because the new
1177 * uffd references it 1188 * uffd references it.
1178 */ 1189 */
1179 if (ret) 1190 if (ret)
1180 userfaultfd_c 1191 userfaultfd_ctx_put(fork_nctx);
1181 } 1192 }
1182 spin_unlock_irq(&ctx->event_w 1193 spin_unlock_irq(&ctx->event_wqh.lock);
1183 } 1194 }
1184 1195
1185 return ret; 1196 return ret;
1186 } 1197 }
1187 1198
1188 static ssize_t userfaultfd_read_iter(struct k !! 1199 static ssize_t userfaultfd_read(struct file *file, char __user *buf,
>> 1200 size_t count, loff_t *ppos)
1189 { 1201 {
1190 struct file *file = iocb->ki_filp; <<
1191 struct userfaultfd_ctx *ctx = file->p 1202 struct userfaultfd_ctx *ctx = file->private_data;
1192 ssize_t _ret, ret = 0; 1203 ssize_t _ret, ret = 0;
1193 struct uffd_msg msg; 1204 struct uffd_msg msg;
1194 struct inode *inode = file_inode(file !! 1205 int no_wait = file->f_flags & O_NONBLOCK;
1195 bool no_wait; <<
1196 1206
1197 if (!userfaultfd_is_initialized(ctx)) !! 1207 if (ctx->state == UFFD_STATE_WAIT_API)
1198 return -EINVAL; 1208 return -EINVAL;
1199 1209
1200 no_wait = file->f_flags & O_NONBLOCK <<
1201 for (;;) { 1210 for (;;) {
1202 if (iov_iter_count(to) < size !! 1211 if (count < sizeof(msg))
1203 return ret ? ret : -E 1212 return ret ? ret : -EINVAL;
1204 _ret = userfaultfd_ctx_read(c !! 1213 _ret = userfaultfd_ctx_read(ctx, no_wait, &msg);
1205 if (_ret < 0) 1214 if (_ret < 0)
1206 return ret ? ret : _r 1215 return ret ? ret : _ret;
1207 _ret = !copy_to_iter_full(&ms !! 1216 if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg)))
1208 if (_ret) <<
1209 return ret ? ret : -E 1217 return ret ? ret : -EFAULT;
1210 ret += sizeof(msg); 1218 ret += sizeof(msg);
>> 1219 buf += sizeof(msg);
>> 1220 count -= sizeof(msg);
1211 /* 1221 /*
1212 * Allow to read more than on 1222 * Allow to read more than one fault at time but only
1213 * block if waiting for the v 1223 * block if waiting for the very first one.
1214 */ 1224 */
1215 no_wait = true; !! 1225 no_wait = O_NONBLOCK;
1216 } 1226 }
1217 } 1227 }
1218 1228
1219 static void __wake_userfault(struct userfault 1229 static void __wake_userfault(struct userfaultfd_ctx *ctx,
1220 struct userfault 1230 struct userfaultfd_wake_range *range)
1221 { 1231 {
1222 spin_lock_irq(&ctx->fault_pending_wqh 1232 spin_lock_irq(&ctx->fault_pending_wqh.lock);
1223 /* wake all in the range and autoremo 1233 /* wake all in the range and autoremove */
1224 if (waitqueue_active(&ctx->fault_pend 1234 if (waitqueue_active(&ctx->fault_pending_wqh))
1225 __wake_up_locked_key(&ctx->fa 1235 __wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL,
1226 range); 1236 range);
1227 if (waitqueue_active(&ctx->fault_wqh) 1237 if (waitqueue_active(&ctx->fault_wqh))
1228 __wake_up(&ctx->fault_wqh, TA 1238 __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range);
1229 spin_unlock_irq(&ctx->fault_pending_w 1239 spin_unlock_irq(&ctx->fault_pending_wqh.lock);
1230 } 1240 }
1231 1241
1232 static __always_inline void wake_userfault(st 1242 static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
1233 st 1243 struct userfaultfd_wake_range *range)
1234 { 1244 {
1235 unsigned seq; 1245 unsigned seq;
1236 bool need_wakeup; 1246 bool need_wakeup;
1237 1247
1238 /* 1248 /*
1239 * To be sure waitqueue_active() is n 1249 * To be sure waitqueue_active() is not reordered by the CPU
1240 * before the pagetable update, use a 1250 * before the pagetable update, use an explicit SMP memory
1241 * barrier here. PT lock release or m !! 1251 * barrier here. PT lock release or up_read(mmap_sem) still
1242 * have release semantics that can al 1252 * have release semantics that can allow the
1243 * waitqueue_active() to be reordered 1253 * waitqueue_active() to be reordered before the pte update.
1244 */ 1254 */
1245 smp_mb(); 1255 smp_mb();
1246 1256
1247 /* 1257 /*
1248 * Use waitqueue_active because it's 1258 * Use waitqueue_active because it's very frequent to
1249 * change the address space atomicall 1259 * change the address space atomically even if there are no
1250 * userfaults yet. So we take the spi 1260 * userfaults yet. So we take the spinlock only when we're
1251 * sure we've userfaults to wake. 1261 * sure we've userfaults to wake.
1252 */ 1262 */
1253 do { 1263 do {
1254 seq = read_seqcount_begin(&ct 1264 seq = read_seqcount_begin(&ctx->refile_seq);
1255 need_wakeup = waitqueue_activ 1265 need_wakeup = waitqueue_active(&ctx->fault_pending_wqh) ||
1256 waitqueue_active(&ctx 1266 waitqueue_active(&ctx->fault_wqh);
1257 cond_resched(); 1267 cond_resched();
1258 } while (read_seqcount_retry(&ctx->re 1268 } while (read_seqcount_retry(&ctx->refile_seq, seq));
1259 if (need_wakeup) 1269 if (need_wakeup)
1260 __wake_userfault(ctx, range); 1270 __wake_userfault(ctx, range);
1261 } 1271 }
1262 1272
1263 static __always_inline int validate_unaligned !! 1273 static __always_inline int validate_range(struct mm_struct *mm,
1264 struct mm_struct *mm, __u64 start, __ !! 1274 __u64 *start, __u64 len)
1265 { 1275 {
1266 __u64 task_size = mm->task_size; 1276 __u64 task_size = mm->task_size;
1267 1277
>> 1278 *start = untagged_addr(*start);
>> 1279
>> 1280 if (*start & ~PAGE_MASK)
>> 1281 return -EINVAL;
1268 if (len & ~PAGE_MASK) 1282 if (len & ~PAGE_MASK)
1269 return -EINVAL; 1283 return -EINVAL;
1270 if (!len) 1284 if (!len)
1271 return -EINVAL; 1285 return -EINVAL;
1272 if (start < mmap_min_addr) !! 1286 if (*start < mmap_min_addr)
1273 return -EINVAL; <<
1274 if (start >= task_size) <<
1275 return -EINVAL; 1287 return -EINVAL;
1276 if (len > task_size - start) !! 1288 if (*start >= task_size)
1277 return -EINVAL; 1289 return -EINVAL;
1278 if (start + len <= start) !! 1290 if (len > task_size - *start)
1279 return -EINVAL; 1291 return -EINVAL;
1280 return 0; 1292 return 0;
1281 } 1293 }
1282 1294
1283 static __always_inline int validate_range(str !! 1295 static inline bool vma_can_userfault(struct vm_area_struct *vma,
1284 __u !! 1296 unsigned long vm_flags)
1285 { 1297 {
1286 if (start & ~PAGE_MASK) !! 1298 /* FIXME: add WP support to hugetlbfs and shmem */
1287 return -EINVAL; !! 1299 return vma_is_anonymous(vma) ||
1288 !! 1300 ((is_vm_hugetlb_page(vma) || vma_is_shmem(vma)) &&
1289 return validate_unaligned_range(mm, s !! 1301 !(vm_flags & VM_UFFD_WP));
1290 } 1302 }
1291 1303
1292 static int userfaultfd_register(struct userfa 1304 static int userfaultfd_register(struct userfaultfd_ctx *ctx,
1293 unsigned long 1305 unsigned long arg)
1294 { 1306 {
1295 struct mm_struct *mm = ctx->mm; 1307 struct mm_struct *mm = ctx->mm;
1296 struct vm_area_struct *vma, *prev, *c 1308 struct vm_area_struct *vma, *prev, *cur;
1297 int ret; 1309 int ret;
1298 struct uffdio_register uffdio_registe 1310 struct uffdio_register uffdio_register;
1299 struct uffdio_register __user *user_u 1311 struct uffdio_register __user *user_uffdio_register;
1300 unsigned long vm_flags, new_flags; 1312 unsigned long vm_flags, new_flags;
1301 bool found; 1313 bool found;
1302 bool basic_ioctls; 1314 bool basic_ioctls;
1303 unsigned long start, end, vma_end; 1315 unsigned long start, end, vma_end;
1304 struct vma_iterator vmi; <<
1305 bool wp_async = userfaultfd_wp_async_ <<
1306 1316
1307 user_uffdio_register = (struct uffdio 1317 user_uffdio_register = (struct uffdio_register __user *) arg;
1308 1318
1309 ret = -EFAULT; 1319 ret = -EFAULT;
1310 if (copy_from_user(&uffdio_register, 1320 if (copy_from_user(&uffdio_register, user_uffdio_register,
1311 sizeof(uffdio_regi 1321 sizeof(uffdio_register)-sizeof(__u64)))
1312 goto out; 1322 goto out;
1313 1323
1314 ret = -EINVAL; 1324 ret = -EINVAL;
1315 if (!uffdio_register.mode) 1325 if (!uffdio_register.mode)
1316 goto out; 1326 goto out;
1317 if (uffdio_register.mode & ~UFFD_API_ !! 1327 if (uffdio_register.mode & ~(UFFDIO_REGISTER_MODE_MISSING|
>> 1328 UFFDIO_REGISTER_MODE_WP))
1318 goto out; 1329 goto out;
1319 vm_flags = 0; 1330 vm_flags = 0;
1320 if (uffdio_register.mode & UFFDIO_REG 1331 if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING)
1321 vm_flags |= VM_UFFD_MISSING; 1332 vm_flags |= VM_UFFD_MISSING;
1322 if (uffdio_register.mode & UFFDIO_REG !! 1333 if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP)
1323 #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP <<
1324 goto out; <<
1325 #endif <<
1326 vm_flags |= VM_UFFD_WP; 1334 vm_flags |= VM_UFFD_WP;
1327 } <<
1328 if (uffdio_register.mode & UFFDIO_REG <<
1329 #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR <<
1330 goto out; <<
1331 #endif <<
1332 vm_flags |= VM_UFFD_MINOR; <<
1333 } <<
1334 1335
1335 ret = validate_range(mm, uffdio_regis !! 1336 ret = validate_range(mm, &uffdio_register.range.start,
1336 uffdio_register. 1337 uffdio_register.range.len);
1337 if (ret) 1338 if (ret)
1338 goto out; 1339 goto out;
1339 1340
1340 start = uffdio_register.range.start; 1341 start = uffdio_register.range.start;
1341 end = start + uffdio_register.range.l 1342 end = start + uffdio_register.range.len;
1342 1343
1343 ret = -ENOMEM; 1344 ret = -ENOMEM;
1344 if (!mmget_not_zero(mm)) 1345 if (!mmget_not_zero(mm))
1345 goto out; 1346 goto out;
1346 1347
1347 ret = -EINVAL; !! 1348 down_write(&mm->mmap_sem);
1348 mmap_write_lock(mm); !! 1349 if (!mmget_still_valid(mm))
1349 vma_iter_init(&vmi, mm, start); !! 1350 goto out_unlock;
1350 vma = vma_find(&vmi, end); !! 1351 vma = find_vma_prev(mm, start, &prev);
1351 if (!vma) 1352 if (!vma)
1352 goto out_unlock; 1353 goto out_unlock;
1353 1354
>> 1355 /* check that there's at least one vma in the range */
>> 1356 ret = -EINVAL;
>> 1357 if (vma->vm_start >= end)
>> 1358 goto out_unlock;
>> 1359
1354 /* 1360 /*
1355 * If the first vma contains huge pag 1361 * If the first vma contains huge pages, make sure start address
1356 * is aligned to huge page size. 1362 * is aligned to huge page size.
1357 */ 1363 */
1358 if (is_vm_hugetlb_page(vma)) { 1364 if (is_vm_hugetlb_page(vma)) {
1359 unsigned long vma_hpagesize = 1365 unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
1360 1366
1361 if (start & (vma_hpagesize - 1367 if (start & (vma_hpagesize - 1))
1362 goto out_unlock; 1368 goto out_unlock;
1363 } 1369 }
1364 1370
1365 /* 1371 /*
1366 * Search for not compatible vmas. 1372 * Search for not compatible vmas.
1367 */ 1373 */
1368 found = false; 1374 found = false;
1369 basic_ioctls = false; 1375 basic_ioctls = false;
1370 cur = vma; !! 1376 for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
1371 do { <<
1372 cond_resched(); 1377 cond_resched();
1373 1378
1374 BUG_ON(!!cur->vm_userfaultfd_ 1379 BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
1375 !!(cur->vm_flags & __V !! 1380 !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP)));
1376 1381
1377 /* check not compatible vmas 1382 /* check not compatible vmas */
1378 ret = -EINVAL; 1383 ret = -EINVAL;
1379 if (!vma_can_userfault(cur, v !! 1384 if (!vma_can_userfault(cur, vm_flags))
1380 goto out_unlock; 1385 goto out_unlock;
1381 1386
1382 /* 1387 /*
1383 * UFFDIO_COPY will fill file 1388 * UFFDIO_COPY will fill file holes even without
1384 * PROT_WRITE. This check enf 1389 * PROT_WRITE. This check enforces that if this is a
1385 * MAP_SHARED, the process ha 1390 * MAP_SHARED, the process has write permission to the backing
1386 * file. If VM_MAYWRITE is se 1391 * file. If VM_MAYWRITE is set it also enforces that on a
1387 * MAP_SHARED vma: there is n 1392 * MAP_SHARED vma: there is no F_WRITE_SEAL and no further
1388 * F_WRITE_SEAL can be taken 1393 * F_WRITE_SEAL can be taken until the vma is destroyed.
1389 */ 1394 */
1390 ret = -EPERM; 1395 ret = -EPERM;
1391 if (unlikely(!(cur->vm_flags 1396 if (unlikely(!(cur->vm_flags & VM_MAYWRITE)))
1392 goto out_unlock; 1397 goto out_unlock;
1393 1398
1394 /* 1399 /*
1395 * If this vma contains endin 1400 * If this vma contains ending address, and huge pages
1396 * check alignment. 1401 * check alignment.
1397 */ 1402 */
1398 if (is_vm_hugetlb_page(cur) & 1403 if (is_vm_hugetlb_page(cur) && end <= cur->vm_end &&
1399 end > cur->vm_start) { 1404 end > cur->vm_start) {
1400 unsigned long vma_hpa 1405 unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
1401 1406
1402 ret = -EINVAL; 1407 ret = -EINVAL;
1403 1408
1404 if (end & (vma_hpages 1409 if (end & (vma_hpagesize - 1))
1405 goto out_unlo 1410 goto out_unlock;
1406 } 1411 }
1407 if ((vm_flags & VM_UFFD_WP) & 1412 if ((vm_flags & VM_UFFD_WP) && !(cur->vm_flags & VM_MAYWRITE))
1408 goto out_unlock; 1413 goto out_unlock;
1409 1414
1410 /* 1415 /*
1411 * Check that this vma isn't 1416 * Check that this vma isn't already owned by a
1412 * different userfaultfd. We 1417 * different userfaultfd. We can't allow more than one
1413 * userfaultfd to own a singl 1418 * userfaultfd to own a single vma simultaneously or we
1414 * wouldn't know which one to 1419 * wouldn't know which one to deliver the userfaults to.
1415 */ 1420 */
1416 ret = -EBUSY; 1421 ret = -EBUSY;
1417 if (cur->vm_userfaultfd_ctx.c 1422 if (cur->vm_userfaultfd_ctx.ctx &&
1418 cur->vm_userfaultfd_ctx.c 1423 cur->vm_userfaultfd_ctx.ctx != ctx)
1419 goto out_unlock; 1424 goto out_unlock;
1420 1425
1421 /* 1426 /*
1422 * Note vmas containing huge 1427 * Note vmas containing huge pages
1423 */ 1428 */
1424 if (is_vm_hugetlb_page(cur)) 1429 if (is_vm_hugetlb_page(cur))
1425 basic_ioctls = true; 1430 basic_ioctls = true;
1426 1431
1427 found = true; 1432 found = true;
1428 } for_each_vma_range(vmi, cur, end); !! 1433 }
1429 BUG_ON(!found); 1434 BUG_ON(!found);
1430 1435
1431 vma_iter_set(&vmi, start); <<
1432 prev = vma_prev(&vmi); <<
1433 if (vma->vm_start < start) 1436 if (vma->vm_start < start)
1434 prev = vma; 1437 prev = vma;
1435 1438
1436 ret = 0; 1439 ret = 0;
1437 for_each_vma_range(vmi, vma, end) { !! 1440 do {
1438 cond_resched(); 1441 cond_resched();
1439 1442
1440 BUG_ON(!vma_can_userfault(vma !! 1443 BUG_ON(!vma_can_userfault(vma, vm_flags));
1441 BUG_ON(vma->vm_userfaultfd_ct 1444 BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
1442 vma->vm_userfaultfd_ct 1445 vma->vm_userfaultfd_ctx.ctx != ctx);
1443 WARN_ON(!(vma->vm_flags & VM_ 1446 WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
1444 1447
1445 /* 1448 /*
1446 * Nothing to do: this vma is 1449 * Nothing to do: this vma is already registered into this
1447 * userfaultfd and with the r 1450 * userfaultfd and with the right tracking mode too.
1448 */ 1451 */
1449 if (vma->vm_userfaultfd_ctx.c 1452 if (vma->vm_userfaultfd_ctx.ctx == ctx &&
1450 (vma->vm_flags & vm_flags 1453 (vma->vm_flags & vm_flags) == vm_flags)
1451 goto skip; 1454 goto skip;
1452 1455
1453 if (vma->vm_start > start) 1456 if (vma->vm_start > start)
1454 start = vma->vm_start 1457 start = vma->vm_start;
1455 vma_end = min(end, vma->vm_en 1458 vma_end = min(end, vma->vm_end);
1456 1459
1457 new_flags = (vma->vm_flags & !! 1460 new_flags = (vma->vm_flags &
1458 vma = vma_modify_flags_uffd(& !! 1461 ~(VM_UFFD_MISSING|VM_UFFD_WP)) | vm_flags;
1459 n !! 1462 prev = vma_merge(mm, prev, start, vma_end, new_flags,
1460 ( !! 1463 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
1461 if (IS_ERR(vma)) { !! 1464 vma_policy(vma),
1462 ret = PTR_ERR(vma); !! 1465 ((struct vm_userfaultfd_ctx){ ctx }));
1463 break; !! 1466 if (prev) {
>> 1467 vma = prev;
>> 1468 goto next;
1464 } 1469 }
1465 !! 1470 if (vma->vm_start < start) {
>> 1471 ret = split_vma(mm, vma, start, 1);
>> 1472 if (ret)
>> 1473 break;
>> 1474 }
>> 1475 if (vma->vm_end > end) {
>> 1476 ret = split_vma(mm, vma, end, 0);
>> 1477 if (ret)
>> 1478 break;
>> 1479 }
>> 1480 next:
1466 /* 1481 /*
1467 * In the vma_merge() success 1482 * In the vma_merge() successful mprotect-like case 8:
1468 * the next vma was merged in 1483 * the next vma was merged into the current one and
1469 * the current one has not be 1484 * the current one has not been updated yet.
1470 */ 1485 */
1471 vma_start_write(vma); !! 1486 vma->vm_flags = new_flags;
1472 userfaultfd_set_vm_flags(vma, <<
1473 vma->vm_userfaultfd_ctx.ctx = 1487 vma->vm_userfaultfd_ctx.ctx = ctx;
1474 1488
1475 if (is_vm_hugetlb_page(vma) & <<
1476 hugetlb_unshare_all_p <<
1477 <<
1478 skip: 1489 skip:
1479 prev = vma; 1490 prev = vma;
1480 start = vma->vm_end; 1491 start = vma->vm_end;
1481 } !! 1492 vma = vma->vm_next;
1482 !! 1493 } while (vma && vma->vm_start < end);
1483 out_unlock: 1494 out_unlock:
1484 mmap_write_unlock(mm); !! 1495 up_write(&mm->mmap_sem);
1485 mmput(mm); 1496 mmput(mm);
1486 if (!ret) { 1497 if (!ret) {
1487 __u64 ioctls_out; 1498 __u64 ioctls_out;
1488 1499
1489 ioctls_out = basic_ioctls ? U 1500 ioctls_out = basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC :
1490 UFFD_API_RANGE_IOCTLS; 1501 UFFD_API_RANGE_IOCTLS;
1491 1502
1492 /* 1503 /*
1493 * Declare the WP ioctl only 1504 * Declare the WP ioctl only if the WP mode is
1494 * specified and all checks p 1505 * specified and all checks passed with the range
1495 */ 1506 */
1496 if (!(uffdio_register.mode & 1507 if (!(uffdio_register.mode & UFFDIO_REGISTER_MODE_WP))
1497 ioctls_out &= ~((__u6 1508 ioctls_out &= ~((__u64)1 << _UFFDIO_WRITEPROTECT);
1498 1509
1499 /* CONTINUE ioctl is only sup <<
1500 if (!(uffdio_register.mode & <<
1501 ioctls_out &= ~((__u6 <<
1502 <<
1503 /* 1510 /*
1504 * Now that we scanned all vm 1511 * Now that we scanned all vmas we can already tell
1505 * userland which ioctls meth 1512 * userland which ioctls methods are guaranteed to
1506 * succeed on this range. 1513 * succeed on this range.
1507 */ 1514 */
1508 if (put_user(ioctls_out, &use 1515 if (put_user(ioctls_out, &user_uffdio_register->ioctls))
1509 ret = -EFAULT; 1516 ret = -EFAULT;
1510 } 1517 }
1511 out: 1518 out:
1512 return ret; 1519 return ret;
1513 } 1520 }
1514 1521
1515 static int userfaultfd_unregister(struct user 1522 static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
1516 unsigned lo 1523 unsigned long arg)
1517 { 1524 {
1518 struct mm_struct *mm = ctx->mm; 1525 struct mm_struct *mm = ctx->mm;
1519 struct vm_area_struct *vma, *prev, *c 1526 struct vm_area_struct *vma, *prev, *cur;
1520 int ret; 1527 int ret;
1521 struct uffdio_range uffdio_unregister 1528 struct uffdio_range uffdio_unregister;
1522 unsigned long new_flags; 1529 unsigned long new_flags;
1523 bool found; 1530 bool found;
1524 unsigned long start, end, vma_end; 1531 unsigned long start, end, vma_end;
1525 const void __user *buf = (void __user 1532 const void __user *buf = (void __user *)arg;
1526 struct vma_iterator vmi; <<
1527 bool wp_async = userfaultfd_wp_async_ <<
1528 1533
1529 ret = -EFAULT; 1534 ret = -EFAULT;
1530 if (copy_from_user(&uffdio_unregister 1535 if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
1531 goto out; 1536 goto out;
1532 1537
1533 ret = validate_range(mm, uffdio_unreg !! 1538 ret = validate_range(mm, &uffdio_unregister.start,
1534 uffdio_unregiste 1539 uffdio_unregister.len);
1535 if (ret) 1540 if (ret)
1536 goto out; 1541 goto out;
1537 1542
1538 start = uffdio_unregister.start; 1543 start = uffdio_unregister.start;
1539 end = start + uffdio_unregister.len; 1544 end = start + uffdio_unregister.len;
1540 1545
1541 ret = -ENOMEM; 1546 ret = -ENOMEM;
1542 if (!mmget_not_zero(mm)) 1547 if (!mmget_not_zero(mm))
1543 goto out; 1548 goto out;
1544 1549
1545 mmap_write_lock(mm); !! 1550 down_write(&mm->mmap_sem);
1546 ret = -EINVAL; !! 1551 if (!mmget_still_valid(mm))
1547 vma_iter_init(&vmi, mm, start); !! 1552 goto out_unlock;
1548 vma = vma_find(&vmi, end); !! 1553 vma = find_vma_prev(mm, start, &prev);
1549 if (!vma) 1554 if (!vma)
1550 goto out_unlock; 1555 goto out_unlock;
1551 1556
>> 1557 /* check that there's at least one vma in the range */
>> 1558 ret = -EINVAL;
>> 1559 if (vma->vm_start >= end)
>> 1560 goto out_unlock;
>> 1561
1552 /* 1562 /*
1553 * If the first vma contains huge pag 1563 * If the first vma contains huge pages, make sure start address
1554 * is aligned to huge page size. 1564 * is aligned to huge page size.
1555 */ 1565 */
1556 if (is_vm_hugetlb_page(vma)) { 1566 if (is_vm_hugetlb_page(vma)) {
1557 unsigned long vma_hpagesize = 1567 unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
1558 1568
1559 if (start & (vma_hpagesize - 1569 if (start & (vma_hpagesize - 1))
1560 goto out_unlock; 1570 goto out_unlock;
1561 } 1571 }
1562 1572
1563 /* 1573 /*
1564 * Search for not compatible vmas. 1574 * Search for not compatible vmas.
1565 */ 1575 */
1566 found = false; 1576 found = false;
1567 cur = vma; !! 1577 ret = -EINVAL;
1568 do { !! 1578 for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
1569 cond_resched(); 1579 cond_resched();
1570 1580
1571 BUG_ON(!!cur->vm_userfaultfd_ 1581 BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
1572 !!(cur->vm_flags & __V !! 1582 !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP)));
1573 1583
1574 /* 1584 /*
1575 * Check not compatible vmas, 1585 * Check not compatible vmas, not strictly required
1576 * here as not compatible vma 1586 * here as not compatible vmas cannot have an
1577 * userfaultfd_ctx registered 1587 * userfaultfd_ctx registered on them, but this
1578 * provides for more strict b 1588 * provides for more strict behavior to notice
1579 * unregistration errors. 1589 * unregistration errors.
1580 */ 1590 */
1581 if (!vma_can_userfault(cur, c !! 1591 if (!vma_can_userfault(cur, cur->vm_flags))
1582 goto out_unlock; 1592 goto out_unlock;
1583 1593
1584 found = true; 1594 found = true;
1585 } for_each_vma_range(vmi, cur, end); !! 1595 }
1586 BUG_ON(!found); 1596 BUG_ON(!found);
1587 1597
1588 vma_iter_set(&vmi, start); <<
1589 prev = vma_prev(&vmi); <<
1590 if (vma->vm_start < start) 1598 if (vma->vm_start < start)
1591 prev = vma; 1599 prev = vma;
1592 1600
1593 ret = 0; 1601 ret = 0;
1594 for_each_vma_range(vmi, vma, end) { !! 1602 do {
1595 cond_resched(); 1603 cond_resched();
1596 1604
1597 BUG_ON(!vma_can_userfault(vma !! 1605 BUG_ON(!vma_can_userfault(vma, vma->vm_flags));
1598 1606
1599 /* 1607 /*
1600 * Nothing to do: this vma is 1608 * Nothing to do: this vma is already registered into this
1601 * userfaultfd and with the r 1609 * userfaultfd and with the right tracking mode too.
1602 */ 1610 */
1603 if (!vma->vm_userfaultfd_ctx. 1611 if (!vma->vm_userfaultfd_ctx.ctx)
1604 goto skip; 1612 goto skip;
1605 1613
1606 WARN_ON(!(vma->vm_flags & VM_ 1614 WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
1607 1615
1608 if (vma->vm_start > start) 1616 if (vma->vm_start > start)
1609 start = vma->vm_start 1617 start = vma->vm_start;
1610 vma_end = min(end, vma->vm_en 1618 vma_end = min(end, vma->vm_end);
1611 1619
1612 if (userfaultfd_missing(vma)) 1620 if (userfaultfd_missing(vma)) {
1613 /* 1621 /*
1614 * Wake any concurren 1622 * Wake any concurrent pending userfault while
1615 * we unregister, so 1623 * we unregister, so they will not hang
1616 * permanently and it 1624 * permanently and it avoids userland to call
1617 * UFFDIO_WAKE explic 1625 * UFFDIO_WAKE explicitly.
1618 */ 1626 */
1619 struct userfaultfd_wa 1627 struct userfaultfd_wake_range range;
1620 range.start = start; 1628 range.start = start;
1621 range.len = vma_end - 1629 range.len = vma_end - start;
1622 wake_userfault(vma->v 1630 wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range);
1623 } 1631 }
1624 1632
1625 /* Reset ptes for the whole v !! 1633 new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP);
1626 if (userfaultfd_wp(vma)) !! 1634 prev = vma_merge(mm, prev, start, vma_end, new_flags,
1627 uffd_wp_range(vma, st !! 1635 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
1628 !! 1636 vma_policy(vma),
1629 new_flags = vma->vm_flags & ~ !! 1637 NULL_VM_UFFD_CTX);
1630 vma = vma_modify_flags_uffd(& !! 1638 if (prev) {
1631 n !! 1639 vma = prev;
1632 if (IS_ERR(vma)) { !! 1640 goto next;
1633 ret = PTR_ERR(vma); <<
1634 break; <<
1635 } 1641 }
1636 !! 1642 if (vma->vm_start < start) {
>> 1643 ret = split_vma(mm, vma, start, 1);
>> 1644 if (ret)
>> 1645 break;
>> 1646 }
>> 1647 if (vma->vm_end > end) {
>> 1648 ret = split_vma(mm, vma, end, 0);
>> 1649 if (ret)
>> 1650 break;
>> 1651 }
>> 1652 next:
1637 /* 1653 /*
1638 * In the vma_merge() success 1654 * In the vma_merge() successful mprotect-like case 8:
1639 * the next vma was merged in 1655 * the next vma was merged into the current one and
1640 * the current one has not be 1656 * the current one has not been updated yet.
1641 */ 1657 */
1642 vma_start_write(vma); !! 1658 vma->vm_flags = new_flags;
1643 userfaultfd_set_vm_flags(vma, <<
1644 vma->vm_userfaultfd_ctx = NUL 1659 vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
1645 1660
1646 skip: 1661 skip:
1647 prev = vma; 1662 prev = vma;
1648 start = vma->vm_end; 1663 start = vma->vm_end;
1649 } !! 1664 vma = vma->vm_next;
1650 !! 1665 } while (vma && vma->vm_start < end);
1651 out_unlock: 1666 out_unlock:
1652 mmap_write_unlock(mm); !! 1667 up_write(&mm->mmap_sem);
1653 mmput(mm); 1668 mmput(mm);
1654 out: 1669 out:
1655 return ret; 1670 return ret;
1656 } 1671 }
1657 1672
1658 /* 1673 /*
1659 * userfaultfd_wake may be used in combinatio 1674 * userfaultfd_wake may be used in combination with the
1660 * UFFDIO_*_MODE_DONTWAKE to wakeup userfault 1675 * UFFDIO_*_MODE_DONTWAKE to wakeup userfaults in batches.
1661 */ 1676 */
1662 static int userfaultfd_wake(struct userfaultf 1677 static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
1663 unsigned long arg 1678 unsigned long arg)
1664 { 1679 {
1665 int ret; 1680 int ret;
1666 struct uffdio_range uffdio_wake; 1681 struct uffdio_range uffdio_wake;
1667 struct userfaultfd_wake_range range; 1682 struct userfaultfd_wake_range range;
1668 const void __user *buf = (void __user 1683 const void __user *buf = (void __user *)arg;
1669 1684
1670 ret = -EFAULT; 1685 ret = -EFAULT;
1671 if (copy_from_user(&uffdio_wake, buf, 1686 if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
1672 goto out; 1687 goto out;
1673 1688
1674 ret = validate_range(ctx->mm, uffdio_ !! 1689 ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
1675 if (ret) 1690 if (ret)
1676 goto out; 1691 goto out;
1677 1692
1678 range.start = uffdio_wake.start; 1693 range.start = uffdio_wake.start;
1679 range.len = uffdio_wake.len; 1694 range.len = uffdio_wake.len;
1680 1695
1681 /* 1696 /*
1682 * len == 0 means wake all and we don 1697 * len == 0 means wake all and we don't want to wake all here,
1683 * so check it again to be sure. 1698 * so check it again to be sure.
1684 */ 1699 */
1685 VM_BUG_ON(!range.len); 1700 VM_BUG_ON(!range.len);
1686 1701
1687 wake_userfault(ctx, &range); 1702 wake_userfault(ctx, &range);
1688 ret = 0; 1703 ret = 0;
1689 1704
1690 out: 1705 out:
1691 return ret; 1706 return ret;
1692 } 1707 }
1693 1708
1694 static int userfaultfd_copy(struct userfaultf 1709 static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
1695 unsigned long arg 1710 unsigned long arg)
1696 { 1711 {
1697 __s64 ret; 1712 __s64 ret;
1698 struct uffdio_copy uffdio_copy; 1713 struct uffdio_copy uffdio_copy;
1699 struct uffdio_copy __user *user_uffdi 1714 struct uffdio_copy __user *user_uffdio_copy;
1700 struct userfaultfd_wake_range range; 1715 struct userfaultfd_wake_range range;
1701 uffd_flags_t flags = 0; <<
1702 1716
1703 user_uffdio_copy = (struct uffdio_cop 1717 user_uffdio_copy = (struct uffdio_copy __user *) arg;
1704 1718
1705 ret = -EAGAIN; 1719 ret = -EAGAIN;
1706 if (atomic_read(&ctx->mmap_changing)) !! 1720 if (READ_ONCE(ctx->mmap_changing))
1707 goto out; 1721 goto out;
1708 1722
1709 ret = -EFAULT; 1723 ret = -EFAULT;
1710 if (copy_from_user(&uffdio_copy, user 1724 if (copy_from_user(&uffdio_copy, user_uffdio_copy,
1711 /* don't copy "cop 1725 /* don't copy "copy" last field */
1712 sizeof(uffdio_copy 1726 sizeof(uffdio_copy)-sizeof(__s64)))
1713 goto out; 1727 goto out;
1714 1728
1715 ret = validate_unaligned_range(ctx->m !! 1729 ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
1716 uffdio <<
1717 if (ret) 1730 if (ret)
1718 goto out; 1731 goto out;
1719 ret = validate_range(ctx->mm, uffdio_ !! 1732 /*
1720 if (ret) !! 1733 * double check for wraparound just in case. copy_from_user()
1721 goto out; !! 1734 * will later check uffdio_copy.src + uffdio_copy.len to fit
1722 !! 1735 * in the userland range.
>> 1736 */
1723 ret = -EINVAL; 1737 ret = -EINVAL;
>> 1738 if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src)
>> 1739 goto out;
1724 if (uffdio_copy.mode & ~(UFFDIO_COPY_ 1740 if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP))
1725 goto out; 1741 goto out;
1726 if (uffdio_copy.mode & UFFDIO_COPY_MO <<
1727 flags |= MFILL_ATOMIC_WP; <<
1728 if (mmget_not_zero(ctx->mm)) { 1742 if (mmget_not_zero(ctx->mm)) {
1729 ret = mfill_atomic_copy(ctx, !! 1743 ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
1730 uffdi !! 1744 uffdio_copy.len, &ctx->mmap_changing,
>> 1745 uffdio_copy.mode);
1731 mmput(ctx->mm); 1746 mmput(ctx->mm);
1732 } else { 1747 } else {
1733 return -ESRCH; 1748 return -ESRCH;
1734 } 1749 }
1735 if (unlikely(put_user(ret, &user_uffd 1750 if (unlikely(put_user(ret, &user_uffdio_copy->copy)))
1736 return -EFAULT; 1751 return -EFAULT;
1737 if (ret < 0) 1752 if (ret < 0)
1738 goto out; 1753 goto out;
1739 BUG_ON(!ret); 1754 BUG_ON(!ret);
1740 /* len == 0 would wake all */ 1755 /* len == 0 would wake all */
1741 range.len = ret; 1756 range.len = ret;
1742 if (!(uffdio_copy.mode & UFFDIO_COPY_ 1757 if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) {
1743 range.start = uffdio_copy.dst 1758 range.start = uffdio_copy.dst;
1744 wake_userfault(ctx, &range); 1759 wake_userfault(ctx, &range);
1745 } 1760 }
1746 ret = range.len == uffdio_copy.len ? 1761 ret = range.len == uffdio_copy.len ? 0 : -EAGAIN;
1747 out: 1762 out:
1748 return ret; 1763 return ret;
1749 } 1764 }
1750 1765
1751 static int userfaultfd_zeropage(struct userfa 1766 static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
1752 unsigned long 1767 unsigned long arg)
1753 { 1768 {
1754 __s64 ret; 1769 __s64 ret;
1755 struct uffdio_zeropage uffdio_zeropag 1770 struct uffdio_zeropage uffdio_zeropage;
1756 struct uffdio_zeropage __user *user_u 1771 struct uffdio_zeropage __user *user_uffdio_zeropage;
1757 struct userfaultfd_wake_range range; 1772 struct userfaultfd_wake_range range;
1758 1773
1759 user_uffdio_zeropage = (struct uffdio 1774 user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg;
1760 1775
1761 ret = -EAGAIN; 1776 ret = -EAGAIN;
1762 if (atomic_read(&ctx->mmap_changing)) !! 1777 if (READ_ONCE(ctx->mmap_changing))
1763 goto out; 1778 goto out;
1764 1779
1765 ret = -EFAULT; 1780 ret = -EFAULT;
1766 if (copy_from_user(&uffdio_zeropage, 1781 if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage,
1767 /* don't copy "zer 1782 /* don't copy "zeropage" last field */
1768 sizeof(uffdio_zero 1783 sizeof(uffdio_zeropage)-sizeof(__s64)))
1769 goto out; 1784 goto out;
1770 1785
1771 ret = validate_range(ctx->mm, uffdio_ !! 1786 ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
1772 uffdio_zeropage. 1787 uffdio_zeropage.range.len);
1773 if (ret) 1788 if (ret)
1774 goto out; 1789 goto out;
1775 ret = -EINVAL; 1790 ret = -EINVAL;
1776 if (uffdio_zeropage.mode & ~UFFDIO_ZE 1791 if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE)
1777 goto out; 1792 goto out;
1778 1793
1779 if (mmget_not_zero(ctx->mm)) { 1794 if (mmget_not_zero(ctx->mm)) {
1780 ret = mfill_atomic_zeropage(c !! 1795 ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
1781 uf !! 1796 uffdio_zeropage.range.len,
>> 1797 &ctx->mmap_changing);
1782 mmput(ctx->mm); 1798 mmput(ctx->mm);
1783 } else { 1799 } else {
1784 return -ESRCH; 1800 return -ESRCH;
1785 } 1801 }
1786 if (unlikely(put_user(ret, &user_uffd 1802 if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage)))
1787 return -EFAULT; 1803 return -EFAULT;
1788 if (ret < 0) 1804 if (ret < 0)
1789 goto out; 1805 goto out;
1790 /* len == 0 would wake all */ 1806 /* len == 0 would wake all */
1791 BUG_ON(!ret); 1807 BUG_ON(!ret);
1792 range.len = ret; 1808 range.len = ret;
1793 if (!(uffdio_zeropage.mode & UFFDIO_Z 1809 if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) {
1794 range.start = uffdio_zeropage 1810 range.start = uffdio_zeropage.range.start;
1795 wake_userfault(ctx, &range); 1811 wake_userfault(ctx, &range);
1796 } 1812 }
1797 ret = range.len == uffdio_zeropage.ra 1813 ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN;
1798 out: 1814 out:
1799 return ret; 1815 return ret;
1800 } 1816 }
1801 1817
1802 static int userfaultfd_writeprotect(struct us 1818 static int userfaultfd_writeprotect(struct userfaultfd_ctx *ctx,
1803 unsigned 1819 unsigned long arg)
1804 { 1820 {
1805 int ret; 1821 int ret;
1806 struct uffdio_writeprotect uffdio_wp; 1822 struct uffdio_writeprotect uffdio_wp;
1807 struct uffdio_writeprotect __user *us 1823 struct uffdio_writeprotect __user *user_uffdio_wp;
1808 struct userfaultfd_wake_range range; 1824 struct userfaultfd_wake_range range;
1809 bool mode_wp, mode_dontwake; 1825 bool mode_wp, mode_dontwake;
1810 1826
1811 if (atomic_read(&ctx->mmap_changing)) !! 1827 if (READ_ONCE(ctx->mmap_changing))
1812 return -EAGAIN; 1828 return -EAGAIN;
1813 1829
1814 user_uffdio_wp = (struct uffdio_write 1830 user_uffdio_wp = (struct uffdio_writeprotect __user *) arg;
1815 1831
1816 if (copy_from_user(&uffdio_wp, user_u 1832 if (copy_from_user(&uffdio_wp, user_uffdio_wp,
1817 sizeof(struct uffd 1833 sizeof(struct uffdio_writeprotect)))
1818 return -EFAULT; 1834 return -EFAULT;
1819 1835
1820 ret = validate_range(ctx->mm, uffdio_ !! 1836 ret = validate_range(ctx->mm, &uffdio_wp.range.start,
1821 uffdio_wp.range. 1837 uffdio_wp.range.len);
1822 if (ret) 1838 if (ret)
1823 return ret; 1839 return ret;
1824 1840
1825 if (uffdio_wp.mode & ~(UFFDIO_WRITEPR 1841 if (uffdio_wp.mode & ~(UFFDIO_WRITEPROTECT_MODE_DONTWAKE |
1826 UFFDIO_WRITEPR 1842 UFFDIO_WRITEPROTECT_MODE_WP))
1827 return -EINVAL; 1843 return -EINVAL;
1828 1844
1829 mode_wp = uffdio_wp.mode & UFFDIO_WRI 1845 mode_wp = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_WP;
1830 mode_dontwake = uffdio_wp.mode & UFFD 1846 mode_dontwake = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_DONTWAKE;
1831 1847
1832 if (mode_wp && mode_dontwake) 1848 if (mode_wp && mode_dontwake)
1833 return -EINVAL; 1849 return -EINVAL;
1834 1850
1835 if (mmget_not_zero(ctx->mm)) { !! 1851 ret = mwriteprotect_range(ctx->mm, uffdio_wp.range.start,
1836 ret = mwriteprotect_range(ctx !! 1852 uffdio_wp.range.len, mode_wp,
1837 uff !! 1853 &ctx->mmap_changing);
1838 mmput(ctx->mm); <<
1839 } else { <<
1840 return -ESRCH; <<
1841 } <<
1842 <<
1843 if (ret) 1854 if (ret)
1844 return ret; 1855 return ret;
1845 1856
1846 if (!mode_wp && !mode_dontwake) { 1857 if (!mode_wp && !mode_dontwake) {
1847 range.start = uffdio_wp.range 1858 range.start = uffdio_wp.range.start;
1848 range.len = uffdio_wp.range.l 1859 range.len = uffdio_wp.range.len;
1849 wake_userfault(ctx, &range); 1860 wake_userfault(ctx, &range);
1850 } 1861 }
1851 return ret; 1862 return ret;
1852 } 1863 }
1853 1864
1854 static int userfaultfd_continue(struct userfa <<
1855 { <<
1856 __s64 ret; <<
1857 struct uffdio_continue uffdio_continu <<
1858 struct uffdio_continue __user *user_u <<
1859 struct userfaultfd_wake_range range; <<
1860 uffd_flags_t flags = 0; <<
1861 <<
1862 user_uffdio_continue = (struct uffdio <<
1863 <<
1864 ret = -EAGAIN; <<
1865 if (atomic_read(&ctx->mmap_changing)) <<
1866 goto out; <<
1867 <<
1868 ret = -EFAULT; <<
1869 if (copy_from_user(&uffdio_continue, <<
1870 /* don't copy the <<
1871 sizeof(uffdio_cont <<
1872 goto out; <<
1873 <<
1874 ret = validate_range(ctx->mm, uffdio_ <<
1875 uffdio_continue. <<
1876 if (ret) <<
1877 goto out; <<
1878 <<
1879 ret = -EINVAL; <<
1880 if (uffdio_continue.mode & ~(UFFDIO_C <<
1881 UFFDIO_C <<
1882 goto out; <<
1883 if (uffdio_continue.mode & UFFDIO_CON <<
1884 flags |= MFILL_ATOMIC_WP; <<
1885 <<
1886 if (mmget_not_zero(ctx->mm)) { <<
1887 ret = mfill_atomic_continue(c <<
1888 u <<
1889 mmput(ctx->mm); <<
1890 } else { <<
1891 return -ESRCH; <<
1892 } <<
1893 <<
1894 if (unlikely(put_user(ret, &user_uffd <<
1895 return -EFAULT; <<
1896 if (ret < 0) <<
1897 goto out; <<
1898 <<
1899 /* len == 0 would wake all */ <<
1900 BUG_ON(!ret); <<
1901 range.len = ret; <<
1902 if (!(uffdio_continue.mode & UFFDIO_C <<
1903 range.start = uffdio_continue <<
1904 wake_userfault(ctx, &range); <<
1905 } <<
1906 ret = range.len == uffdio_continue.ra <<
1907 <<
1908 out: <<
1909 return ret; <<
1910 } <<
1911 <<
1912 static inline int userfaultfd_poison(struct u <<
1913 { <<
1914 __s64 ret; <<
1915 struct uffdio_poison uffdio_poison; <<
1916 struct uffdio_poison __user *user_uff <<
1917 struct userfaultfd_wake_range range; <<
1918 <<
1919 user_uffdio_poison = (struct uffdio_p <<
1920 <<
1921 ret = -EAGAIN; <<
1922 if (atomic_read(&ctx->mmap_changing)) <<
1923 goto out; <<
1924 <<
1925 ret = -EFAULT; <<
1926 if (copy_from_user(&uffdio_poison, us <<
1927 /* don't copy the <<
1928 sizeof(uffdio_pois <<
1929 goto out; <<
1930 <<
1931 ret = validate_range(ctx->mm, uffdio_ <<
1932 uffdio_poison.ra <<
1933 if (ret) <<
1934 goto out; <<
1935 <<
1936 ret = -EINVAL; <<
1937 if (uffdio_poison.mode & ~UFFDIO_POIS <<
1938 goto out; <<
1939 <<
1940 if (mmget_not_zero(ctx->mm)) { <<
1941 ret = mfill_atomic_poison(ctx <<
1942 uff <<
1943 mmput(ctx->mm); <<
1944 } else { <<
1945 return -ESRCH; <<
1946 } <<
1947 <<
1948 if (unlikely(put_user(ret, &user_uffd <<
1949 return -EFAULT; <<
1950 if (ret < 0) <<
1951 goto out; <<
1952 <<
1953 /* len == 0 would wake all */ <<
1954 BUG_ON(!ret); <<
1955 range.len = ret; <<
1956 if (!(uffdio_poison.mode & UFFDIO_POI <<
1957 range.start = uffdio_poison.r <<
1958 wake_userfault(ctx, &range); <<
1959 } <<
1960 ret = range.len == uffdio_poison.rang <<
1961 <<
1962 out: <<
1963 return ret; <<
1964 } <<
1965 <<
1966 bool userfaultfd_wp_async(struct vm_area_stru <<
1967 { <<
1968 return userfaultfd_wp_async_ctx(vma-> <<
1969 } <<
1970 <<
1971 static inline unsigned int uffd_ctx_features( 1865 static inline unsigned int uffd_ctx_features(__u64 user_features)
1972 { 1866 {
1973 /* 1867 /*
1974 * For the current set of features th !! 1868 * For the current set of features the bits just coincide
1975 * UFFD_FEATURE_INITIALIZED to mark t <<
1976 */ 1869 */
1977 return (unsigned int)user_features | !! 1870 return (unsigned int)user_features;
1978 } <<
1979 <<
1980 static int userfaultfd_move(struct userfaultf <<
1981 unsigned long arg <<
1982 { <<
1983 __s64 ret; <<
1984 struct uffdio_move uffdio_move; <<
1985 struct uffdio_move __user *user_uffdi <<
1986 struct userfaultfd_wake_range range; <<
1987 struct mm_struct *mm = ctx->mm; <<
1988 <<
1989 user_uffdio_move = (struct uffdio_mov <<
1990 <<
1991 if (atomic_read(&ctx->mmap_changing)) <<
1992 return -EAGAIN; <<
1993 <<
1994 if (copy_from_user(&uffdio_move, user <<
1995 /* don't copy "mov <<
1996 sizeof(uffdio_move <<
1997 return -EFAULT; <<
1998 <<
1999 /* Do not allow cross-mm moves. */ <<
2000 if (mm != current->mm) <<
2001 return -EINVAL; <<
2002 <<
2003 ret = validate_range(mm, uffdio_move. <<
2004 if (ret) <<
2005 return ret; <<
2006 <<
2007 ret = validate_range(mm, uffdio_move. <<
2008 if (ret) <<
2009 return ret; <<
2010 <<
2011 if (uffdio_move.mode & ~(UFFDIO_MOVE_ <<
2012 UFFDIO_MOVE <<
2013 return -EINVAL; <<
2014 <<
2015 if (mmget_not_zero(mm)) { <<
2016 ret = move_pages(ctx, uffdio_ <<
2017 uffdio_move. <<
2018 mmput(mm); <<
2019 } else { <<
2020 return -ESRCH; <<
2021 } <<
2022 <<
2023 if (unlikely(put_user(ret, &user_uffd <<
2024 return -EFAULT; <<
2025 if (ret < 0) <<
2026 goto out; <<
2027 <<
2028 /* len == 0 would wake all */ <<
2029 VM_WARN_ON(!ret); <<
2030 range.len = ret; <<
2031 if (!(uffdio_move.mode & UFFDIO_MOVE_ <<
2032 range.start = uffdio_move.dst <<
2033 wake_userfault(ctx, &range); <<
2034 } <<
2035 ret = range.len == uffdio_move.len ? <<
2036 <<
2037 out: <<
2038 return ret; <<
2039 } 1871 }
2040 1872
2041 /* 1873 /*
2042 * userland asks for a certain API version an 1874 * userland asks for a certain API version and we return which bits
2043 * and ioctl commands are implemented in this 1875 * and ioctl commands are implemented in this kernel for such API
2044 * version or -EINVAL if unknown. 1876 * version or -EINVAL if unknown.
2045 */ 1877 */
2046 static int userfaultfd_api(struct userfaultfd 1878 static int userfaultfd_api(struct userfaultfd_ctx *ctx,
2047 unsigned long arg) 1879 unsigned long arg)
2048 { 1880 {
2049 struct uffdio_api uffdio_api; 1881 struct uffdio_api uffdio_api;
2050 void __user *buf = (void __user *)arg 1882 void __user *buf = (void __user *)arg;
2051 unsigned int ctx_features; <<
2052 int ret; 1883 int ret;
2053 __u64 features; 1884 __u64 features;
2054 1885
>> 1886 ret = -EINVAL;
>> 1887 if (ctx->state != UFFD_STATE_WAIT_API)
>> 1888 goto out;
2055 ret = -EFAULT; 1889 ret = -EFAULT;
2056 if (copy_from_user(&uffdio_api, buf, 1890 if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api)))
2057 goto out; 1891 goto out;
2058 features = uffdio_api.features; 1892 features = uffdio_api.features;
2059 ret = -EINVAL; 1893 ret = -EINVAL;
2060 if (uffdio_api.api != UFFD_API) !! 1894 if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES))
2061 goto err_out; 1895 goto err_out;
2062 ret = -EPERM; 1896 ret = -EPERM;
2063 if ((features & UFFD_FEATURE_EVENT_FO 1897 if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE))
2064 goto err_out; 1898 goto err_out;
2065 <<
2066 /* WP_ASYNC relies on WP_UNPOPULATED, <<
2067 if (features & UFFD_FEATURE_WP_ASYNC) <<
2068 features |= UFFD_FEATURE_WP_U <<
2069 <<
2070 /* report all available features and 1899 /* report all available features and ioctls to userland */
2071 uffdio_api.features = UFFD_API_FEATUR 1900 uffdio_api.features = UFFD_API_FEATURES;
2072 #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR <<
2073 uffdio_api.features &= <<
2074 ~(UFFD_FEATURE_MINOR_HUGETLBF <<
2075 #endif <<
2076 #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP <<
2077 uffdio_api.features &= ~UFFD_FEATURE_ <<
2078 #endif <<
2079 #ifndef CONFIG_PTE_MARKER_UFFD_WP <<
2080 uffdio_api.features &= ~UFFD_FEATURE_ <<
2081 uffdio_api.features &= ~UFFD_FEATURE_ <<
2082 uffdio_api.features &= ~UFFD_FEATURE_ <<
2083 #endif <<
2084 <<
2085 ret = -EINVAL; <<
2086 if (features & ~uffdio_api.features) <<
2087 goto err_out; <<
2088 <<
2089 uffdio_api.ioctls = UFFD_API_IOCTLS; 1901 uffdio_api.ioctls = UFFD_API_IOCTLS;
2090 ret = -EFAULT; 1902 ret = -EFAULT;
2091 if (copy_to_user(buf, &uffdio_api, si 1903 if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
2092 goto out; 1904 goto out;
2093 !! 1905 ctx->state = UFFD_STATE_RUNNING;
2094 /* only enable the requested features 1906 /* only enable the requested features for this uffd context */
2095 ctx_features = uffd_ctx_features(feat !! 1907 ctx->features = uffd_ctx_features(features);
2096 ret = -EINVAL; <<
2097 if (cmpxchg(&ctx->features, 0, ctx_fe <<
2098 goto err_out; <<
2099 <<
2100 ret = 0; 1908 ret = 0;
2101 out: 1909 out:
2102 return ret; 1910 return ret;
2103 err_out: 1911 err_out:
2104 memset(&uffdio_api, 0, sizeof(uffdio_ 1912 memset(&uffdio_api, 0, sizeof(uffdio_api));
2105 if (copy_to_user(buf, &uffdio_api, si 1913 if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
2106 ret = -EFAULT; 1914 ret = -EFAULT;
2107 goto out; 1915 goto out;
2108 } 1916 }
2109 1917
2110 static long userfaultfd_ioctl(struct file *fi 1918 static long userfaultfd_ioctl(struct file *file, unsigned cmd,
2111 unsigned long a 1919 unsigned long arg)
2112 { 1920 {
2113 int ret = -EINVAL; 1921 int ret = -EINVAL;
2114 struct userfaultfd_ctx *ctx = file->p 1922 struct userfaultfd_ctx *ctx = file->private_data;
2115 1923
2116 if (cmd != UFFDIO_API && !userfaultfd !! 1924 if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API)
2117 return -EINVAL; 1925 return -EINVAL;
2118 1926
2119 switch(cmd) { 1927 switch(cmd) {
2120 case UFFDIO_API: 1928 case UFFDIO_API:
2121 ret = userfaultfd_api(ctx, ar 1929 ret = userfaultfd_api(ctx, arg);
2122 break; 1930 break;
2123 case UFFDIO_REGISTER: 1931 case UFFDIO_REGISTER:
2124 ret = userfaultfd_register(ct 1932 ret = userfaultfd_register(ctx, arg);
2125 break; 1933 break;
2126 case UFFDIO_UNREGISTER: 1934 case UFFDIO_UNREGISTER:
2127 ret = userfaultfd_unregister( 1935 ret = userfaultfd_unregister(ctx, arg);
2128 break; 1936 break;
2129 case UFFDIO_WAKE: 1937 case UFFDIO_WAKE:
2130 ret = userfaultfd_wake(ctx, a 1938 ret = userfaultfd_wake(ctx, arg);
2131 break; 1939 break;
2132 case UFFDIO_COPY: 1940 case UFFDIO_COPY:
2133 ret = userfaultfd_copy(ctx, a 1941 ret = userfaultfd_copy(ctx, arg);
2134 break; 1942 break;
2135 case UFFDIO_ZEROPAGE: 1943 case UFFDIO_ZEROPAGE:
2136 ret = userfaultfd_zeropage(ct 1944 ret = userfaultfd_zeropage(ctx, arg);
2137 break; 1945 break;
2138 case UFFDIO_MOVE: <<
2139 ret = userfaultfd_move(ctx, a <<
2140 break; <<
2141 case UFFDIO_WRITEPROTECT: 1946 case UFFDIO_WRITEPROTECT:
2142 ret = userfaultfd_writeprotec 1947 ret = userfaultfd_writeprotect(ctx, arg);
2143 break; 1948 break;
2144 case UFFDIO_CONTINUE: <<
2145 ret = userfaultfd_continue(ct <<
2146 break; <<
2147 case UFFDIO_POISON: <<
2148 ret = userfaultfd_poison(ctx, <<
2149 break; <<
2150 } 1949 }
2151 return ret; 1950 return ret;
2152 } 1951 }
2153 1952
2154 #ifdef CONFIG_PROC_FS 1953 #ifdef CONFIG_PROC_FS
2155 static void userfaultfd_show_fdinfo(struct se 1954 static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f)
2156 { 1955 {
2157 struct userfaultfd_ctx *ctx = f->priv 1956 struct userfaultfd_ctx *ctx = f->private_data;
2158 wait_queue_entry_t *wq; 1957 wait_queue_entry_t *wq;
2159 unsigned long pending = 0, total = 0; 1958 unsigned long pending = 0, total = 0;
2160 1959
2161 spin_lock_irq(&ctx->fault_pending_wqh 1960 spin_lock_irq(&ctx->fault_pending_wqh.lock);
2162 list_for_each_entry(wq, &ctx->fault_p 1961 list_for_each_entry(wq, &ctx->fault_pending_wqh.head, entry) {
2163 pending++; 1962 pending++;
2164 total++; 1963 total++;
2165 } 1964 }
2166 list_for_each_entry(wq, &ctx->fault_w 1965 list_for_each_entry(wq, &ctx->fault_wqh.head, entry) {
2167 total++; 1966 total++;
2168 } 1967 }
2169 spin_unlock_irq(&ctx->fault_pending_w 1968 spin_unlock_irq(&ctx->fault_pending_wqh.lock);
2170 1969
2171 /* 1970 /*
2172 * If more protocols will be added, t 1971 * If more protocols will be added, there will be all shown
2173 * separated by a space. Like this: 1972 * separated by a space. Like this:
2174 * protocols: aa:... bb:... 1973 * protocols: aa:... bb:...
2175 */ 1974 */
2176 seq_printf(m, "pending:\t%lu\ntotal:\ 1975 seq_printf(m, "pending:\t%lu\ntotal:\t%lu\nAPI:\t%Lx:%x:%Lx\n",
2177 pending, total, UFFD_API, 1976 pending, total, UFFD_API, ctx->features,
2178 UFFD_API_IOCTLS|UFFD_API_R 1977 UFFD_API_IOCTLS|UFFD_API_RANGE_IOCTLS);
2179 } 1978 }
2180 #endif 1979 #endif
2181 1980
2182 static const struct file_operations userfault 1981 static const struct file_operations userfaultfd_fops = {
2183 #ifdef CONFIG_PROC_FS 1982 #ifdef CONFIG_PROC_FS
2184 .show_fdinfo = userfaultfd_show_fd 1983 .show_fdinfo = userfaultfd_show_fdinfo,
2185 #endif 1984 #endif
2186 .release = userfaultfd_release 1985 .release = userfaultfd_release,
2187 .poll = userfaultfd_poll, 1986 .poll = userfaultfd_poll,
2188 .read_iter = userfaultfd_read_it !! 1987 .read = userfaultfd_read,
2189 .unlocked_ioctl = userfaultfd_ioctl, 1988 .unlocked_ioctl = userfaultfd_ioctl,
2190 .compat_ioctl = compat_ptr_ioctl, 1989 .compat_ioctl = compat_ptr_ioctl,
2191 .llseek = noop_llseek, 1990 .llseek = noop_llseek,
2192 }; 1991 };
2193 1992
2194 static void init_once_userfaultfd_ctx(void *m 1993 static void init_once_userfaultfd_ctx(void *mem)
2195 { 1994 {
2196 struct userfaultfd_ctx *ctx = (struct 1995 struct userfaultfd_ctx *ctx = (struct userfaultfd_ctx *) mem;
2197 1996
2198 init_waitqueue_head(&ctx->fault_pendi 1997 init_waitqueue_head(&ctx->fault_pending_wqh);
2199 init_waitqueue_head(&ctx->fault_wqh); 1998 init_waitqueue_head(&ctx->fault_wqh);
2200 init_waitqueue_head(&ctx->event_wqh); 1999 init_waitqueue_head(&ctx->event_wqh);
2201 init_waitqueue_head(&ctx->fd_wqh); 2000 init_waitqueue_head(&ctx->fd_wqh);
2202 seqcount_spinlock_init(&ctx->refile_s !! 2001 seqcount_init(&ctx->refile_seq);
2203 } 2002 }
2204 2003
2205 static int new_userfaultfd(int flags) !! 2004 SYSCALL_DEFINE1(userfaultfd, int, flags)
2206 { 2005 {
2207 struct userfaultfd_ctx *ctx; 2006 struct userfaultfd_ctx *ctx;
2208 struct file *file; <<
2209 int fd; 2007 int fd;
2210 2008
>> 2009 if (!sysctl_unprivileged_userfaultfd && !capable(CAP_SYS_PTRACE))
>> 2010 return -EPERM;
>> 2011
2211 BUG_ON(!current->mm); 2012 BUG_ON(!current->mm);
2212 2013
2213 /* Check the UFFD_* constants for con 2014 /* Check the UFFD_* constants for consistency. */
2214 BUILD_BUG_ON(UFFD_USER_MODE_ONLY & UF <<
2215 BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXE 2015 BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXEC);
2216 BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBL 2016 BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBLOCK);
2217 2017
2218 if (flags & ~(UFFD_SHARED_FCNTL_FLAGS !! 2018 if (flags & ~UFFD_SHARED_FCNTL_FLAGS)
2219 return -EINVAL; 2019 return -EINVAL;
2220 2020
2221 ctx = kmem_cache_alloc(userfaultfd_ct 2021 ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL);
2222 if (!ctx) 2022 if (!ctx)
2223 return -ENOMEM; 2023 return -ENOMEM;
2224 2024
2225 refcount_set(&ctx->refcount, 1); 2025 refcount_set(&ctx->refcount, 1);
2226 ctx->flags = flags; 2026 ctx->flags = flags;
2227 ctx->features = 0; 2027 ctx->features = 0;
>> 2028 ctx->state = UFFD_STATE_WAIT_API;
2228 ctx->released = false; 2029 ctx->released = false;
2229 init_rwsem(&ctx->map_changing_lock); !! 2030 ctx->mmap_changing = false;
2230 atomic_set(&ctx->mmap_changing, 0); <<
2231 ctx->mm = current->mm; 2031 ctx->mm = current->mm;
2232 <<
2233 fd = get_unused_fd_flags(flags & UFFD <<
2234 if (fd < 0) <<
2235 goto err_out; <<
2236 <<
2237 /* Create a new inode so that the LSM <<
2238 file = anon_inode_create_getfile("[us <<
2239 O_RDONLY | (flags & U <<
2240 if (IS_ERR(file)) { <<
2241 put_unused_fd(fd); <<
2242 fd = PTR_ERR(file); <<
2243 goto err_out; <<
2244 } <<
2245 /* prevent the mm struct to be freed 2032 /* prevent the mm struct to be freed */
2246 mmgrab(ctx->mm); 2033 mmgrab(ctx->mm);
2247 file->f_mode |= FMODE_NOWAIT; <<
2248 fd_install(fd, file); <<
2249 return fd; <<
2250 err_out: <<
2251 kmem_cache_free(userfaultfd_ctx_cache <<
2252 return fd; <<
2253 } <<
2254 2034
2255 static inline bool userfaultfd_syscall_allowe !! 2035 fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx,
2256 { !! 2036 O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
2257 /* Userspace-only page faults are alw !! 2037 if (fd < 0) {
2258 if (flags & UFFD_USER_MODE_ONLY) !! 2038 mmdrop(ctx->mm);
2259 return true; !! 2039 kmem_cache_free(userfaultfd_ctx_cachep, ctx);
2260 !! 2040 }
2261 /* !! 2041 return fd;
2262 * The user is requesting a userfault <<
2263 * Privileged users are always allowe <<
2264 */ <<
2265 if (capable(CAP_SYS_PTRACE)) <<
2266 return true; <<
2267 <<
2268 /* Otherwise, access to kernel fault <<
2269 return sysctl_unprivileged_userfaultf <<
2270 } <<
2271 <<
2272 SYSCALL_DEFINE1(userfaultfd, int, flags) <<
2273 { <<
2274 if (!userfaultfd_syscall_allowed(flag <<
2275 return -EPERM; <<
2276 <<
2277 return new_userfaultfd(flags); <<
2278 } <<
2279 <<
2280 static long userfaultfd_dev_ioctl(struct file <<
2281 { <<
2282 if (cmd != USERFAULTFD_IOC_NEW) <<
2283 return -EINVAL; <<
2284 <<
2285 return new_userfaultfd(flags); <<
2286 } 2042 }
2287 2043
2288 static const struct file_operations userfault <<
2289 .unlocked_ioctl = userfaultfd_dev_ioc <<
2290 .compat_ioctl = userfaultfd_dev_ioctl <<
2291 .owner = THIS_MODULE, <<
2292 .llseek = noop_llseek, <<
2293 }; <<
2294 <<
2295 static struct miscdevice userfaultfd_misc = { <<
2296 .minor = MISC_DYNAMIC_MINOR, <<
2297 .name = "userfaultfd", <<
2298 .fops = &userfaultfd_dev_fops <<
2299 }; <<
2300 <<
2301 static int __init userfaultfd_init(void) 2044 static int __init userfaultfd_init(void)
2302 { 2045 {
2303 int ret; <<
2304 <<
2305 ret = misc_register(&userfaultfd_misc <<
2306 if (ret) <<
2307 return ret; <<
2308 <<
2309 userfaultfd_ctx_cachep = kmem_cache_c 2046 userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache",
2310 2047 sizeof(struct userfaultfd_ctx),
2311 2048 0,
2312 2049 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2313 2050 init_once_userfaultfd_ctx);
2314 #ifdef CONFIG_SYSCTL <<
2315 register_sysctl_init("vm", vm_userfau <<
2316 #endif <<
2317 return 0; 2051 return 0;
2318 } 2052 }
2319 __initcall(userfaultfd_init); 2053 __initcall(userfaultfd_init);
2320 2054
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