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