/
sys_ulock.c
1097 lines (936 loc) · 28.3 KB
/
sys_ulock.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Copyright (c) 2015-2020 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <machine/atomic.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/file_internal.h>
#include <sys/proc_internal.h>
#include <sys/kernel.h>
#include <sys/guarded.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/sysproto.h>
#include <sys/pthread_shims.h>
#include <mach/mach_types.h>
#include <kern/cpu_data.h>
#include <kern/mach_param.h>
#include <kern/kern_types.h>
#include <kern/assert.h>
#include <kern/zalloc.h>
#include <kern/thread.h>
#include <kern/clock.h>
#include <kern/ledger.h>
#include <kern/policy_internal.h>
#include <kern/task.h>
#include <kern/telemetry.h>
#include <kern/waitq.h>
#include <kern/sched_prim.h>
#include <kern/turnstile.h>
#include <kern/zalloc.h>
#include <kern/debug.h>
#include <pexpert/pexpert.h>
#define XNU_TEST_BITMAP
#include <kern/bits.h>
#include <os/hash.h>
#include <sys/ulock.h>
/*
* How ulock promotion works:
*
* There’s a requested policy field on every thread called ‘promotions’, which
* expresses which ulock promotions are happening to this thread.
* The promotion priority saturates until the promotion count goes to 0.
*
* We also track effective promotion qos, which is the qos before clamping.
* This value is used for promoting a thread that another thread is waiting on,
* so that the lock owner reinflates to the right priority after unclamping.
*
* This also works for non-QoS threads, which can donate base priority to QoS
* and non-QoS threads alike.
*
* ulock wait applies a promotion to the owner communicated through
* UL_UNFAIR_LOCK as waiters block, and that promotion is saturated as long as
* there is still an owner. In ulock wake, if the waker is still the owner,
* then it clears its ownership and drops the boost. It does NOT transfer
* ownership/priority boost to the new thread. Instead, it selects the
* waiting thread with the highest base priority to be woken next, and
* relies on that thread to carry the torch for the other waiting threads.
*/
static LCK_GRP_DECLARE(ull_lck_grp, "ulocks");
#if ULL_TICKET_LOCK
typedef lck_ticket_t ull_lock_t;
#define ull_lock_init(ull) lck_ticket_init(&ull->ull_lock, &ull_lck_grp)
#define ull_lock_destroy(ull) lck_ticket_destroy(&ull->ull_lock, &ull_lck_grp)
#define ull_lock(ull) lck_ticket_lock(&ull->ull_lock, &ull_lck_grp)
#define ull_unlock(ull) lck_ticket_unlock(&ull->ull_lock)
#define ull_assert_owned(ull) lck_ticket_assert_owned(&ull->ull_lock)
#define ull_assert_notwned(ull) lck_ticket_assert_not_owned(&ull->ull_lock)
#else
typedef lck_spin_t ull_lock_t;
#define ull_lock_init(ull) lck_spin_init(&ull->ull_lock, &ull_lck_grp, NULL)
#define ull_lock_destroy(ull) lck_spin_destroy(&ull->ull_lock, &ull_lck_grp)
#define ull_lock(ull) lck_spin_lock_grp(&ull->ull_lock, &ull_lck_grp)
#define ull_unlock(ull) lck_spin_unlock(&ull->ull_lock)
#define ull_assert_owned(ull) LCK_SPIN_ASSERT(&ull->ull_lock, LCK_ASSERT_OWNED)
#define ull_assert_notwned(ull) LCK_SPIN_ASSERT(&ull->ull_lock, LCK_ASSERT_NOTOWNED)
#endif /* ULL_TICKET_LOCK */
#define ULOCK_TO_EVENT(ull) ((event_t)ull)
#define EVENT_TO_ULOCK(event) ((ull_t *)event)
typedef enum {
ULK_INVALID = 0,
ULK_UADDR,
ULK_XPROC,
} ulk_type;
typedef struct {
union {
struct __attribute__((packed)) {
user_addr_t ulk_addr;
/*
* We use the task address as a hashing key,
* so that ulock wakes across exec can't
* be confused.
*/
task_t ulk_task __kernel_data_semantics;
};
struct __attribute__((packed)) {
uint64_t ulk_object;
uint64_t ulk_offset;
};
};
ulk_type ulk_key_type;
} ulk_t;
#define ULK_UADDR_LEN (sizeof(user_addr_t) + sizeof(task_t))
#define ULK_XPROC_LEN (sizeof(uint64_t) + sizeof(uint64_t))
inline static bool
ull_key_match(ulk_t *a, ulk_t *b)
{
if (a->ulk_key_type != b->ulk_key_type) {
return false;
}
if (a->ulk_key_type == ULK_UADDR) {
return (a->ulk_task == b->ulk_task) &&
(a->ulk_addr == b->ulk_addr);
}
assert(a->ulk_key_type == ULK_XPROC);
return (a->ulk_object == b->ulk_object) &&
(a->ulk_offset == b->ulk_offset);
}
typedef struct ull {
/*
* ull_owner is the most recent known value for the owner of this ulock
* i.e. it may be out of date WRT the real value in userspace.
*/
thread_t ull_owner; /* holds +1 thread reference */
ulk_t ull_key;
ull_lock_t ull_lock;
uint ull_bucket_index;
int32_t ull_nwaiters;
int32_t ull_refcount;
uint8_t ull_opcode;
struct turnstile *ull_turnstile;
queue_chain_t ull_hash_link;
} ull_t;
#define ULL_MUST_EXIST 0x0001
static void ull_put(ull_t *);
static uint32_t ulock_adaptive_spin_usecs = 20;
SYSCTL_INT(_kern, OID_AUTO, ulock_adaptive_spin_usecs, CTLFLAG_RW | CTLFLAG_LOCKED,
&ulock_adaptive_spin_usecs, 0, "ulock adaptive spin duration");
#if DEVELOPMENT || DEBUG
static int ull_simulate_copyin_fault = 0;
static void
ull_dump(ull_t *ull)
{
kprintf("ull\t%p\n", ull);
switch (ull->ull_key.ulk_key_type) {
case ULK_UADDR:
kprintf("ull_key.ulk_key_type\tULK_UADDR\n");
kprintf("ull_key.ulk_task\t%p\n", ull->ull_key.ulk_task);
kprintf("ull_key.ulk_addr\t%p\n", (void *)(ull->ull_key.ulk_addr));
break;
case ULK_XPROC:
kprintf("ull_key.ulk_key_type\tULK_XPROC\n");
kprintf("ull_key.ulk_object\t%p\n", (void *)(ull->ull_key.ulk_object));
kprintf("ull_key.ulk_offset\t%p\n", (void *)(ull->ull_key.ulk_offset));
break;
default:
kprintf("ull_key.ulk_key_type\tUNKNOWN %d\n", ull->ull_key.ulk_key_type);
break;
}
kprintf("ull_nwaiters\t%d\n", ull->ull_nwaiters);
kprintf("ull_refcount\t%d\n", ull->ull_refcount);
kprintf("ull_opcode\t%d\n\n", ull->ull_opcode);
kprintf("ull_owner\t0x%llx\n\n", thread_tid(ull->ull_owner));
kprintf("ull_turnstile\t%p\n\n", ull->ull_turnstile);
}
#endif
typedef struct ull_bucket {
queue_head_t ulb_head;
#if ULL_TICKET_LOCK
lck_ticket_t ulb_lock;
#else
lck_spin_t ulb_lock;
#endif /* ULL_TICKET_LOCK */
} ull_bucket_t;
static SECURITY_READ_ONLY_LATE(int) ull_hash_buckets;
static SECURITY_READ_ONLY_LATE(ull_bucket_t *) ull_bucket;
static uint32_t ull_nzalloc = 0;
static KALLOC_TYPE_DEFINE(ull_zone, ull_t, KT_DEFAULT);
#if ULL_TICKET_LOCK
#define ull_bucket_lock(i) lck_ticket_lock(&ull_bucket[i].ulb_lock, &ull_lck_grp)
#define ull_bucket_unlock(i) lck_ticket_unlock(&ull_bucket[i].ulb_lock)
#else
#define ull_bucket_lock(i) lck_spin_lock_grp(&ull_bucket[i].ulb_lock, &ull_lck_grp)
#define ull_bucket_unlock(i) lck_spin_unlock(&ull_bucket[i].ulb_lock)
#endif /* ULL_TICKET_LOCK */
static __inline__ uint32_t
ull_hash_index(const void *key, size_t length)
{
uint32_t hash = os_hash_jenkins(key, length);
hash &= (ull_hash_buckets - 1);
return hash;
}
#define ULL_INDEX(keyp) ull_hash_index(keyp, keyp->ulk_key_type == ULK_UADDR ? ULK_UADDR_LEN : ULK_XPROC_LEN)
static void
ulock_initialize(void)
{
assert(thread_max > 16);
/* Size ull_hash_buckets based on thread_max.
* Round up to nearest power of 2, then divide by 4
*/
ull_hash_buckets = (1 << (bit_ceiling(thread_max) - 2));
kprintf("%s>thread_max=%d, ull_hash_buckets=%d\n", __FUNCTION__, thread_max, ull_hash_buckets);
assert(ull_hash_buckets >= thread_max / 4);
ull_bucket = zalloc_permanent(sizeof(ull_bucket_t) * ull_hash_buckets,
ZALIGN_PTR);
assert(ull_bucket != NULL);
for (int i = 0; i < ull_hash_buckets; i++) {
queue_init(&ull_bucket[i].ulb_head);
#if ULL_TICKET_LOCK
lck_ticket_init(&ull_bucket[i].ulb_lock, &ull_lck_grp);
#else
lck_spin_init(&ull_bucket[i].ulb_lock, &ull_lck_grp, NULL);
#endif /* ULL_TICKET_LOCK */
}
}
STARTUP(EARLY_BOOT, STARTUP_RANK_FIRST, ulock_initialize);
#if DEVELOPMENT || DEBUG
/* Count the number of hash entries for a given task address.
* if task==0, dump the whole table.
*/
static int
ull_hash_dump(task_t task)
{
int count = 0;
if (task == TASK_NULL) {
kprintf("%s>total number of ull_t allocated %d\n", __FUNCTION__, ull_nzalloc);
kprintf("%s>BEGIN\n", __FUNCTION__);
}
for (int i = 0; i < ull_hash_buckets; i++) {
ull_bucket_lock(i);
if (!queue_empty(&ull_bucket[i].ulb_head)) {
ull_t *elem;
if (task == TASK_NULL) {
kprintf("%s>index %d:\n", __FUNCTION__, i);
}
qe_foreach_element(elem, &ull_bucket[i].ulb_head, ull_hash_link) {
if ((task == TASK_NULL) || ((elem->ull_key.ulk_key_type == ULK_UADDR)
&& (task == elem->ull_key.ulk_task))) {
ull_dump(elem);
count++;
}
}
}
ull_bucket_unlock(i);
}
if (task == TASK_NULL) {
kprintf("%s>END\n", __FUNCTION__);
ull_nzalloc = 0;
}
return count;
}
#endif
static ull_t *
ull_alloc(ulk_t *key)
{
ull_t *ull = (ull_t *)zalloc_flags(ull_zone, Z_SET_NOTSHARED);
assert(ull != NULL);
ull->ull_refcount = 1;
ull->ull_key = *key;
ull->ull_bucket_index = ULL_INDEX(key);
ull->ull_nwaiters = 0;
ull->ull_opcode = 0;
ull->ull_owner = THREAD_NULL;
ull->ull_turnstile = TURNSTILE_NULL;
ull_lock_init(ull);
ull_nzalloc++;
return ull;
}
static void
ull_free(ull_t *ull)
{
assert(ull->ull_owner == THREAD_NULL);
assert(ull->ull_turnstile == TURNSTILE_NULL);
ull_assert_notwned(ull);
ull_lock_destroy(ull);
zfree(ull_zone, ull);
}
/* Finds an existing ulock structure (ull_t), or creates a new one.
* If MUST_EXIST flag is set, returns NULL instead of creating a new one.
* The ulock structure is returned with ull_lock locked
*/
static ull_t *
ull_get(ulk_t *key, uint32_t flags, ull_t **unused_ull)
{
ull_t *ull = NULL;
uint i = ULL_INDEX(key);
ull_t *new_ull = (flags & ULL_MUST_EXIST) ? NULL : ull_alloc(key);
ull_t *elem;
ull_bucket_lock(i);
qe_foreach_element(elem, &ull_bucket[i].ulb_head, ull_hash_link) {
ull_lock(elem);
if (ull_key_match(&elem->ull_key, key)) {
ull = elem;
break;
} else {
ull_unlock(elem);
}
}
if (ull == NULL) {
if (flags & ULL_MUST_EXIST) {
/* Must already exist (called from wake) */
ull_bucket_unlock(i);
assert(new_ull == NULL);
assert(unused_ull == NULL);
return NULL;
}
if (new_ull == NULL) {
/* Alloc above failed */
ull_bucket_unlock(i);
return NULL;
}
ull = new_ull;
ull_lock(ull);
enqueue(&ull_bucket[i].ulb_head, &ull->ull_hash_link);
} else if (!(flags & ULL_MUST_EXIST)) {
assert(new_ull);
assert(unused_ull);
assert(*unused_ull == NULL);
*unused_ull = new_ull;
}
ull->ull_refcount++;
ull_bucket_unlock(i);
return ull; /* still locked */
}
/*
* Must be called with ull_lock held
*/
static void
ull_put(ull_t *ull)
{
ull_assert_owned(ull);
int refcount = --ull->ull_refcount;
assert(refcount == 0 ? (ull->ull_key.ulk_key_type == ULK_INVALID) : 1);
ull_unlock(ull);
if (refcount > 0) {
return;
}
ull_bucket_lock(ull->ull_bucket_index);
remqueue(&ull->ull_hash_link);
ull_bucket_unlock(ull->ull_bucket_index);
ull_free(ull);
}
extern kern_return_t vm_map_page_info(vm_map_t map, vm_map_offset_t offset, vm_page_info_flavor_t flavor, vm_page_info_t info, mach_msg_type_number_t *count);
extern vm_map_t current_map(void);
extern boolean_t machine_thread_on_core(thread_t thread);
static int
uaddr_findobj(user_addr_t uaddr, uint64_t *objectp, uint64_t *offsetp)
{
kern_return_t ret;
vm_page_info_basic_data_t info;
mach_msg_type_number_t count = VM_PAGE_INFO_BASIC_COUNT;
ret = vm_map_page_info(current_map(), uaddr, VM_PAGE_INFO_BASIC, (vm_page_info_t)&info, &count);
if (ret != KERN_SUCCESS) {
return EINVAL;
}
if (objectp != NULL) {
*objectp = (uint64_t)info.object_id;
}
if (offsetp != NULL) {
*offsetp = (uint64_t)info.offset;
}
return 0;
}
static void ulock_wait_continue(void *, wait_result_t);
static void ulock_wait_cleanup(ull_t *, thread_t, thread_t, int32_t *);
inline static int
wait_result_to_return_code(wait_result_t wr)
{
int ret = 0;
switch (wr) {
case THREAD_AWAKENED:
break;
case THREAD_TIMED_OUT:
ret = ETIMEDOUT;
break;
case THREAD_INTERRUPTED:
case THREAD_RESTART:
default:
ret = EINTR;
break;
}
return ret;
}
static int
ulock_resolve_owner(uint32_t value, thread_t *owner)
{
mach_port_name_t owner_name = ulock_owner_value_to_port_name(value);
*owner = port_name_to_thread(owner_name,
PORT_INTRANS_THREAD_IN_CURRENT_TASK |
PORT_INTRANS_THREAD_NOT_CURRENT_THREAD);
if (*owner == THREAD_NULL) {
/*
* Translation failed - even though the lock value is up to date,
* whatever was stored in the lock wasn't actually a thread port.
*/
return owner_name == MACH_PORT_DEAD ? ESRCH : EOWNERDEAD;
}
return 0;
}
int
sys_ulock_wait(struct proc *p, struct ulock_wait_args *args, int32_t *retval)
{
struct ulock_wait2_args args2;
args2.operation = args->operation;
args2.addr = args->addr;
args2.value = args->value;
args2.timeout = (uint64_t)(args->timeout) * NSEC_PER_USEC;
args2.value2 = 0;
return sys_ulock_wait2(p, &args2, retval);
}
int
sys_ulock_wait2(struct proc *p, struct ulock_wait2_args *args, int32_t *retval)
{
uint8_t opcode = (uint8_t)(args->operation & UL_OPCODE_MASK);
uint flags = args->operation & UL_FLAGS_MASK;
if (flags & ULF_WAIT_CANCEL_POINT) {
__pthread_testcancel(1);
}
int ret = 0;
thread_t self = current_thread();
ulk_t key;
/* involved threads - each variable holds +1 ref if not null */
thread_t owner_thread = THREAD_NULL;
thread_t old_owner = THREAD_NULL;
ull_t *unused_ull = NULL;
if ((flags & ULF_WAIT_MASK) != flags) {
ret = EINVAL;
goto munge_retval;
}
bool set_owner = false;
bool xproc = false;
size_t lock_size = sizeof(uint32_t);
int copy_ret;
switch (opcode) {
case UL_UNFAIR_LOCK:
set_owner = true;
break;
case UL_COMPARE_AND_WAIT:
break;
case UL_COMPARE_AND_WAIT64:
lock_size = sizeof(uint64_t);
break;
case UL_COMPARE_AND_WAIT_SHARED:
xproc = true;
break;
case UL_COMPARE_AND_WAIT64_SHARED:
xproc = true;
lock_size = sizeof(uint64_t);
break;
default:
ret = EINVAL;
goto munge_retval;
}
uint64_t value = 0;
if ((args->addr == 0) || (args->addr & (lock_size - 1))) {
ret = EINVAL;
goto munge_retval;
}
if (xproc) {
uint64_t object = 0;
uint64_t offset = 0;
ret = uaddr_findobj(args->addr, &object, &offset);
if (ret) {
ret = EINVAL;
goto munge_retval;
}
key.ulk_key_type = ULK_XPROC;
key.ulk_object = object;
key.ulk_offset = offset;
} else {
key.ulk_key_type = ULK_UADDR;
key.ulk_task = proc_task(p);
key.ulk_addr = args->addr;
}
if ((flags & ULF_WAIT_ADAPTIVE_SPIN) && set_owner) {
/*
* Attempt the copyin outside of the lock once,
*
* If it doesn't match (which is common), return right away.
*
* If it matches, resolve the current owner, and if it is on core,
* spin a bit waiting for the value to change. If the owner isn't on
* core, or if the value stays stable, then go on with the regular
* blocking code.
*/
uint64_t end = 0;
uint32_t u32;
ret = copyin_atomic32(args->addr, &u32);
if (ret || u32 != args->value) {
goto munge_retval;
}
for (;;) {
if (owner_thread == NULL && ulock_resolve_owner(u32, &owner_thread) != 0) {
break;
}
/* owner_thread may have a +1 starting here */
if (!machine_thread_on_core(owner_thread)) {
break;
}
if (end == 0) {
clock_interval_to_deadline(ulock_adaptive_spin_usecs,
NSEC_PER_USEC, &end);
} else if (mach_absolute_time() > end) {
break;
}
if (copyin_atomic32_wait_if_equals(args->addr, u32) != 0) {
goto munge_retval;
}
}
}
ull_t *ull = ull_get(&key, 0, &unused_ull);
if (ull == NULL) {
ret = ENOMEM;
goto munge_retval;
}
/* ull is locked */
ull->ull_nwaiters++;
if (ull->ull_opcode == 0) {
ull->ull_opcode = opcode;
} else if (ull->ull_opcode != opcode) {
ret = EDOM;
goto out_locked;
}
/*
* We don't want this copyin to get wedged behind VM operations,
* but we have to read the userspace value under the ull lock for correctness.
*
* Until <rdar://problem/24999882> exists,
* holding the ull spinlock across copyin forces any
* vm_fault we encounter to fail.
*/
/* copyin_atomicXX always checks alignment */
if (lock_size == 4) {
uint32_t u32;
copy_ret = copyin_atomic32(args->addr, &u32);
value = u32;
} else {
copy_ret = copyin_atomic64(args->addr, &value);
}
#if DEVELOPMENT || DEBUG
/* Occasionally simulate copyin finding the user address paged out */
if (((ull_simulate_copyin_fault == proc_getpid(p)) || (ull_simulate_copyin_fault == 1)) && (copy_ret == 0)) {
static _Atomic int fault_inject = 0;
if (os_atomic_inc_orig(&fault_inject, relaxed) % 73 == 0) {
copy_ret = EFAULT;
}
}
#endif
if (copy_ret != 0) {
/* copyin() will return an error if the access to the user addr would have faulted,
* so just return and let the user level code fault it in.
*/
ret = copy_ret;
goto out_locked;
}
if (value != args->value) {
/* Lock value has changed from expected so bail out */
goto out_locked;
}
if (set_owner) {
if (owner_thread == THREAD_NULL) {
ret = ulock_resolve_owner((uint32_t)args->value, &owner_thread);
if (ret == EOWNERDEAD) {
/*
* Translation failed - even though the lock value is up to date,
* whatever was stored in the lock wasn't actually a thread port.
*/
goto out_locked;
}
/* HACK: don't bail on MACH_PORT_DEAD, to avoid blowing up the no-tsd pthread lock */
ret = 0;
}
/* owner_thread has a +1 reference */
/*
* At this point, I know:
* a) owner_thread is definitely the current owner, because I just read the value
* b) owner_thread is either:
* i) holding the user lock or
* ii) has just unlocked the user lock after I looked
* and is heading toward the kernel to call ull_wake.
* If so, it's going to have to wait for the ull mutex.
*
* Therefore, I can ask the turnstile to promote its priority, and I can rely
* on it to come by later to issue the wakeup and lose its promotion.
*/
/* Return the +1 ref from the ull_owner field */
old_owner = ull->ull_owner;
ull->ull_owner = THREAD_NULL;
if (owner_thread != THREAD_NULL) {
/* The ull_owner field now owns a +1 ref on owner_thread */
thread_reference(owner_thread);
ull->ull_owner = owner_thread;
}
}
wait_result_t wr;
uint64_t timeout = args->timeout; /* nanoseconds */
uint64_t deadline = TIMEOUT_WAIT_FOREVER;
wait_interrupt_t interruptible = THREAD_ABORTSAFE;
struct turnstile *ts;
ts = turnstile_prepare((uintptr_t)ull, &ull->ull_turnstile,
TURNSTILE_NULL, TURNSTILE_ULOCK);
thread_set_pending_block_hint(self, kThreadWaitUserLock);
if (flags & ULF_WAIT_WORKQ_DATA_CONTENTION) {
interruptible |= THREAD_WAIT_NOREPORT;
}
if (timeout) {
nanoseconds_to_deadline(timeout, &deadline);
}
turnstile_update_inheritor(ts, owner_thread,
(TURNSTILE_DELAYED_UPDATE | TURNSTILE_INHERITOR_THREAD));
wr = waitq_assert_wait64(&ts->ts_waitq, CAST_EVENT64_T(ULOCK_TO_EVENT(ull)),
interruptible, deadline);
if (wr == THREAD_WAITING) {
uthread_t uthread = (uthread_t)get_bsdthread_info(self);
uthread->uu_save.uus_ulock_wait_data.ull = ull;
uthread->uu_save.uus_ulock_wait_data.retval = retval;
uthread->uu_save.uus_ulock_wait_data.flags = flags;
uthread->uu_save.uus_ulock_wait_data.owner_thread = owner_thread;
uthread->uu_save.uus_ulock_wait_data.old_owner = old_owner;
}
ull_unlock(ull);
if (unused_ull) {
ull_free(unused_ull);
unused_ull = NULL;
}
turnstile_update_inheritor_complete(ts, TURNSTILE_INTERLOCK_NOT_HELD);
if (wr == THREAD_WAITING) {
if (set_owner && owner_thread != THREAD_NULL) {
thread_handoff_parameter(owner_thread, ulock_wait_continue, ull, THREAD_HANDOFF_NONE);
} else {
assert(owner_thread == THREAD_NULL);
thread_block_parameter(ulock_wait_continue, ull);
}
/* NOT REACHED */
}
ret = wait_result_to_return_code(wr);
ull_lock(ull);
turnstile_complete((uintptr_t)ull, &ull->ull_turnstile, NULL, TURNSTILE_ULOCK);
out_locked:
ulock_wait_cleanup(ull, owner_thread, old_owner, retval);
owner_thread = NULL;
if (unused_ull) {
ull_free(unused_ull);
unused_ull = NULL;
}
assert(*retval >= 0);
munge_retval:
if (owner_thread) {
thread_deallocate(owner_thread);
}
if (ret == ESTALE) {
ret = 0;
}
if ((flags & ULF_NO_ERRNO) && (ret != 0)) {
*retval = -ret;
ret = 0;
}
return ret;
}
/*
* Must be called with ull_lock held
*/
static void
ulock_wait_cleanup(ull_t *ull, thread_t owner_thread, thread_t old_owner, int32_t *retval)
{
ull_assert_owned(ull);
thread_t old_lingering_owner = THREAD_NULL;
*retval = --ull->ull_nwaiters;
if (ull->ull_nwaiters == 0) {
/*
* If the wait was canceled early, we might need to
* clear out the lingering owner reference before
* freeing the ull.
*/
old_lingering_owner = ull->ull_owner;
ull->ull_owner = THREAD_NULL;
memset(&ull->ull_key, 0, sizeof ull->ull_key);
ull->ull_refcount--;
assert(ull->ull_refcount > 0);
}
ull_put(ull);
/* Need to be called after dropping the interlock */
turnstile_cleanup();
if (owner_thread != THREAD_NULL) {
thread_deallocate(owner_thread);
}
if (old_owner != THREAD_NULL) {
thread_deallocate(old_owner);
}
if (old_lingering_owner != THREAD_NULL) {
thread_deallocate(old_lingering_owner);
}
assert(*retval >= 0);
}
__attribute__((noreturn))
static void
ulock_wait_continue(__unused void * parameter, wait_result_t wr)
{
uthread_t uthread = current_uthread();
int ret = 0;
ull_t *ull = uthread->uu_save.uus_ulock_wait_data.ull;
int32_t *retval = uthread->uu_save.uus_ulock_wait_data.retval;
uint flags = uthread->uu_save.uus_ulock_wait_data.flags;
thread_t owner_thread = uthread->uu_save.uus_ulock_wait_data.owner_thread;
thread_t old_owner = uthread->uu_save.uus_ulock_wait_data.old_owner;
ret = wait_result_to_return_code(wr);
ull_lock(ull);
turnstile_complete((uintptr_t)ull, &ull->ull_turnstile, NULL, TURNSTILE_ULOCK);
ulock_wait_cleanup(ull, owner_thread, old_owner, retval);
if ((flags & ULF_NO_ERRNO) && (ret != 0)) {
*retval = -ret;
ret = 0;
}
unix_syscall_return(ret);
}
int
sys_ulock_wake(struct proc *p, struct ulock_wake_args *args, int32_t *retval)
{
int ret = 0;
#if DEVELOPMENT || DEBUG
uint8_t opcode = (uint8_t)(args->operation & UL_OPCODE_MASK);
if (opcode == UL_DEBUG_HASH_DUMP_PID) {
*retval = ull_hash_dump(proc_task(p));
return ret;
} else if (opcode == UL_DEBUG_HASH_DUMP_ALL) {
*retval = ull_hash_dump(TASK_NULL);
return ret;
} else if (opcode == UL_DEBUG_SIMULATE_COPYIN_FAULT) {
ull_simulate_copyin_fault = (int)(args->wake_value);
return ret;
}
#endif
ret = ulock_wake(proc_task(p), args->operation, args->addr, args->wake_value);
if ((args->operation & ULF_NO_ERRNO) && (ret != 0)) {
*retval = -ret;
ret = 0;
}
return ret;
}
int
ulock_wake(task_t task, uint32_t operation, user_addr_t addr, uint64_t wake_value)
{
uint8_t opcode = (uint8_t)(operation & UL_OPCODE_MASK);
uint flags = operation & UL_FLAGS_MASK;
int ret = 0;
ulk_t key;
/* involved threads - each variable holds +1 ref if not null */
thread_t wake_thread = THREAD_NULL;
bool set_owner = false;
bool allow_non_owner = false;
bool xproc = false;
switch (opcode) {
case UL_UNFAIR_LOCK:
set_owner = true;
break;
case UL_COMPARE_AND_WAIT:
case UL_COMPARE_AND_WAIT64:
break;
case UL_COMPARE_AND_WAIT_SHARED:
case UL_COMPARE_AND_WAIT64_SHARED:
xproc = true;
break;
default:
ret = EINVAL;
goto munge_retval;
}
if ((flags & ULF_WAKE_MASK) != flags) {
ret = EINVAL;
goto munge_retval;
}
if ((flags & ULF_WAKE_THREAD) && ((flags & ULF_WAKE_ALL) || set_owner)) {
ret = EINVAL;
goto munge_retval;
}
if (flags & ULF_WAKE_ALLOW_NON_OWNER) {
if (!set_owner) {
ret = EINVAL;
goto munge_retval;
}
allow_non_owner = true;
}
if (addr == 0) {
ret = EINVAL;
goto munge_retval;
}
if (xproc) {
uint64_t object = 0;
uint64_t offset = 0;
ret = uaddr_findobj(addr, &object, &offset);
if (ret) {
ret = EINVAL;
goto munge_retval;
}
key.ulk_key_type = ULK_XPROC;
key.ulk_object = object;
key.ulk_offset = offset;
} else {
key.ulk_key_type = ULK_UADDR;
key.ulk_task = task;
key.ulk_addr = addr;
}
if (flags & ULF_WAKE_THREAD) {
mach_port_name_t wake_thread_name = (mach_port_name_t)(wake_value);
wake_thread = port_name_to_thread(wake_thread_name,
PORT_INTRANS_THREAD_IN_CURRENT_TASK |
PORT_INTRANS_THREAD_NOT_CURRENT_THREAD);
if (wake_thread == THREAD_NULL) {
ret = ESRCH;
goto munge_retval;
}
}
ull_t *ull = ull_get(&key, ULL_MUST_EXIST, NULL);
thread_t new_owner = THREAD_NULL;
struct turnstile *ts = TURNSTILE_NULL;
thread_t cleanup_thread = THREAD_NULL;
if (ull == NULL) {
ret = ENOENT;
goto munge_retval;
}
/* ull is locked */
if (opcode != ull->ull_opcode) {
ret = EDOM;
goto out_ull_put;
}
if (set_owner) {
if ((ull->ull_owner != current_thread()) && !allow_non_owner) {
/*