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33
34#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
35
36#include <linux/unistd.h>
37#include <linux/errno.h>
38#include <linux/types.h>
39#include <linux/uio.h>
40#include <linux/kernel.h>
41#include <linux/string.h>
42#include <linux/err.h>
43#include <linux/slab.h>
44#include <linux/fcntl.h>
45#include <linux/kthread.h>
46#include <linux/reboot.h>
47#include <linux/rwsem.h>
48#include <linux/mutex.h>
49#include <asm/xen/hypervisor.h>
50#include <xen/xenbus.h>
51#include <xen/xen.h>
52#include "xenbus.h"
53
54
55
56
57
58
59
60
61
62
63
64static DEFINE_SPINLOCK(xs_state_lock);
65
66static unsigned int xs_state_users;
67
68static int xs_suspend_active;
69
70static uint32_t xs_request_id;
71
72
73static DECLARE_WAIT_QUEUE_HEAD(xs_state_enter_wq);
74
75static DECLARE_WAIT_QUEUE_HEAD(xs_state_exit_wq);
76
77
78static LIST_HEAD(watches);
79static DEFINE_SPINLOCK(watches_lock);
80
81
82static LIST_HEAD(watch_events);
83static DEFINE_SPINLOCK(watch_events_lock);
84
85
86static DECLARE_RWSEM(xs_watch_rwsem);
87
88
89
90
91
92
93
94static pid_t xenwatch_pid;
95static DEFINE_MUTEX(xenwatch_mutex);
96static DECLARE_WAIT_QUEUE_HEAD(watch_events_waitq);
97
98static void xs_suspend_enter(void)
99{
100 spin_lock(&xs_state_lock);
101 xs_suspend_active++;
102 spin_unlock(&xs_state_lock);
103 wait_event(xs_state_exit_wq, xs_state_users == 0);
104}
105
106static void xs_suspend_exit(void)
107{
108 xb_dev_generation_id++;
109 spin_lock(&xs_state_lock);
110 xs_suspend_active--;
111 spin_unlock(&xs_state_lock);
112 wake_up_all(&xs_state_enter_wq);
113}
114
115static uint32_t xs_request_enter(struct xb_req_data *req)
116{
117 uint32_t rq_id;
118
119 req->type = req->msg.type;
120
121 spin_lock(&xs_state_lock);
122
123 while (!xs_state_users && xs_suspend_active) {
124 spin_unlock(&xs_state_lock);
125 wait_event(xs_state_enter_wq, xs_suspend_active == 0);
126 spin_lock(&xs_state_lock);
127 }
128
129 if (req->type == XS_TRANSACTION_START && !req->user_req)
130 xs_state_users++;
131 xs_state_users++;
132 rq_id = xs_request_id++;
133
134 spin_unlock(&xs_state_lock);
135
136 return rq_id;
137}
138
139void xs_request_exit(struct xb_req_data *req)
140{
141 spin_lock(&xs_state_lock);
142 xs_state_users--;
143 if ((req->type == XS_TRANSACTION_START && req->msg.type == XS_ERROR) ||
144 (req->type == XS_TRANSACTION_END && !req->user_req &&
145 !WARN_ON_ONCE(req->msg.type == XS_ERROR &&
146 !strcmp(req->body, "ENOENT"))))
147 xs_state_users--;
148 spin_unlock(&xs_state_lock);
149
150 if (xs_suspend_active && !xs_state_users)
151 wake_up(&xs_state_exit_wq);
152}
153
154static int get_error(const char *errorstring)
155{
156 unsigned int i;
157
158 for (i = 0; strcmp(errorstring, xsd_errors[i].errstring) != 0; i++) {
159 if (i == ARRAY_SIZE(xsd_errors) - 1) {
160 pr_warn("xen store gave: unknown error %s\n",
161 errorstring);
162 return EINVAL;
163 }
164 }
165 return xsd_errors[i].errnum;
166}
167
168static bool xenbus_ok(void)
169{
170 switch (xen_store_domain_type) {
171 case XS_LOCAL:
172 switch (system_state) {
173 case SYSTEM_POWER_OFF:
174 case SYSTEM_RESTART:
175 case SYSTEM_HALT:
176 return false;
177 default:
178 break;
179 }
180 return true;
181 case XS_PV:
182 case XS_HVM:
183
184
185 return true;
186 default:
187 break;
188 }
189 return false;
190}
191
192static bool test_reply(struct xb_req_data *req)
193{
194 if (req->state == xb_req_state_got_reply || !xenbus_ok())
195 return true;
196
197
198 barrier();
199
200 return false;
201}
202
203static void *read_reply(struct xb_req_data *req)
204{
205 while (req->state != xb_req_state_got_reply) {
206 wait_event(req->wq, test_reply(req));
207
208 if (!xenbus_ok())
209
210
211
212
213
214
215 return ERR_PTR(-EIO);
216 if (req->err)
217 return ERR_PTR(req->err);
218
219 }
220
221 return req->body;
222}
223
224static void xs_send(struct xb_req_data *req, struct xsd_sockmsg *msg)
225{
226 bool notify;
227
228 req->msg = *msg;
229 req->err = 0;
230 req->state = xb_req_state_queued;
231 init_waitqueue_head(&req->wq);
232
233
234 req->caller_req_id = req->msg.req_id;
235 req->msg.req_id = xs_request_enter(req);
236
237 mutex_lock(&xb_write_mutex);
238 list_add_tail(&req->list, &xb_write_list);
239 notify = list_is_singular(&xb_write_list);
240 mutex_unlock(&xb_write_mutex);
241
242 if (notify)
243 wake_up(&xb_waitq);
244}
245
246static void *xs_wait_for_reply(struct xb_req_data *req, struct xsd_sockmsg *msg)
247{
248 void *ret;
249
250 ret = read_reply(req);
251
252 xs_request_exit(req);
253
254 msg->type = req->msg.type;
255 msg->len = req->msg.len;
256
257 mutex_lock(&xb_write_mutex);
258 if (req->state == xb_req_state_queued ||
259 req->state == xb_req_state_wait_reply)
260 req->state = xb_req_state_aborted;
261 else
262 kfree(req);
263 mutex_unlock(&xb_write_mutex);
264
265 return ret;
266}
267
268static void xs_wake_up(struct xb_req_data *req)
269{
270 wake_up(&req->wq);
271}
272
273int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par)
274{
275 struct xb_req_data *req;
276 struct kvec *vec;
277
278 req = kmalloc(sizeof(*req) + sizeof(*vec), GFP_KERNEL);
279 if (!req)
280 return -ENOMEM;
281
282 vec = (struct kvec *)(req + 1);
283 vec->iov_len = msg->len;
284 vec->iov_base = msg + 1;
285
286 req->vec = vec;
287 req->num_vecs = 1;
288 req->cb = xenbus_dev_queue_reply;
289 req->par = par;
290 req->user_req = true;
291
292 xs_send(req, msg);
293
294 return 0;
295}
296EXPORT_SYMBOL(xenbus_dev_request_and_reply);
297
298
299static void *xs_talkv(struct xenbus_transaction t,
300 enum xsd_sockmsg_type type,
301 const struct kvec *iovec,
302 unsigned int num_vecs,
303 unsigned int *len)
304{
305 struct xb_req_data *req;
306 struct xsd_sockmsg msg;
307 void *ret = NULL;
308 unsigned int i;
309 int err;
310
311 req = kmalloc(sizeof(*req), GFP_NOIO | __GFP_HIGH);
312 if (!req)
313 return ERR_PTR(-ENOMEM);
314
315 req->vec = iovec;
316 req->num_vecs = num_vecs;
317 req->cb = xs_wake_up;
318 req->user_req = false;
319
320 msg.req_id = 0;
321 msg.tx_id = t.id;
322 msg.type = type;
323 msg.len = 0;
324 for (i = 0; i < num_vecs; i++)
325 msg.len += iovec[i].iov_len;
326
327 xs_send(req, &msg);
328
329 ret = xs_wait_for_reply(req, &msg);
330 if (len)
331 *len = msg.len;
332
333 if (IS_ERR(ret))
334 return ret;
335
336 if (msg.type == XS_ERROR) {
337 err = get_error(ret);
338 kfree(ret);
339 return ERR_PTR(-err);
340 }
341
342 if (msg.type != type) {
343 pr_warn_ratelimited("unexpected type [%d], expected [%d]\n",
344 msg.type, type);
345 kfree(ret);
346 return ERR_PTR(-EINVAL);
347 }
348 return ret;
349}
350
351
352static void *xs_single(struct xenbus_transaction t,
353 enum xsd_sockmsg_type type,
354 const char *string,
355 unsigned int *len)
356{
357 struct kvec iovec;
358
359 iovec.iov_base = (void *)string;
360 iovec.iov_len = strlen(string) + 1;
361 return xs_talkv(t, type, &iovec, 1, len);
362}
363
364
365static int xs_error(char *reply)
366{
367 if (IS_ERR(reply))
368 return PTR_ERR(reply);
369 kfree(reply);
370 return 0;
371}
372
373static unsigned int count_strings(const char *strings, unsigned int len)
374{
375 unsigned int num;
376 const char *p;
377
378 for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1)
379 num++;
380
381 return num;
382}
383
384
385static char *join(const char *dir, const char *name)
386{
387 char *buffer;
388
389 if (strlen(name) == 0)
390 buffer = kasprintf(GFP_NOIO | __GFP_HIGH, "%s", dir);
391 else
392 buffer = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/%s", dir, name);
393 return (!buffer) ? ERR_PTR(-ENOMEM) : buffer;
394}
395
396static char **split(char *strings, unsigned int len, unsigned int *num)
397{
398 char *p, **ret;
399
400
401 *num = count_strings(strings, len);
402
403
404 ret = kmalloc(*num * sizeof(char *) + len, GFP_NOIO | __GFP_HIGH);
405 if (!ret) {
406 kfree(strings);
407 return ERR_PTR(-ENOMEM);
408 }
409 memcpy(&ret[*num], strings, len);
410 kfree(strings);
411
412 strings = (char *)&ret[*num];
413 for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1)
414 ret[(*num)++] = p;
415
416 return ret;
417}
418
419char **xenbus_directory(struct xenbus_transaction t,
420 const char *dir, const char *node, unsigned int *num)
421{
422 char *strings, *path;
423 unsigned int len;
424
425 path = join(dir, node);
426 if (IS_ERR(path))
427 return (char **)path;
428
429 strings = xs_single(t, XS_DIRECTORY, path, &len);
430 kfree(path);
431 if (IS_ERR(strings))
432 return (char **)strings;
433
434 return split(strings, len, num);
435}
436EXPORT_SYMBOL_GPL(xenbus_directory);
437
438
439int xenbus_exists(struct xenbus_transaction t,
440 const char *dir, const char *node)
441{
442 char **d;
443 int dir_n;
444
445 d = xenbus_directory(t, dir, node, &dir_n);
446 if (IS_ERR(d))
447 return 0;
448 kfree(d);
449 return 1;
450}
451EXPORT_SYMBOL_GPL(xenbus_exists);
452
453
454
455
456
457void *xenbus_read(struct xenbus_transaction t,
458 const char *dir, const char *node, unsigned int *len)
459{
460 char *path;
461 void *ret;
462
463 path = join(dir, node);
464 if (IS_ERR(path))
465 return (void *)path;
466
467 ret = xs_single(t, XS_READ, path, len);
468 kfree(path);
469 return ret;
470}
471EXPORT_SYMBOL_GPL(xenbus_read);
472
473
474
475
476int xenbus_write(struct xenbus_transaction t,
477 const char *dir, const char *node, const char *string)
478{
479 const char *path;
480 struct kvec iovec[2];
481 int ret;
482
483 path = join(dir, node);
484 if (IS_ERR(path))
485 return PTR_ERR(path);
486
487 iovec[0].iov_base = (void *)path;
488 iovec[0].iov_len = strlen(path) + 1;
489 iovec[1].iov_base = (void *)string;
490 iovec[1].iov_len = strlen(string);
491
492 ret = xs_error(xs_talkv(t, XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL));
493 kfree(path);
494 return ret;
495}
496EXPORT_SYMBOL_GPL(xenbus_write);
497
498
499int xenbus_mkdir(struct xenbus_transaction t,
500 const char *dir, const char *node)
501{
502 char *path;
503 int ret;
504
505 path = join(dir, node);
506 if (IS_ERR(path))
507 return PTR_ERR(path);
508
509 ret = xs_error(xs_single(t, XS_MKDIR, path, NULL));
510 kfree(path);
511 return ret;
512}
513EXPORT_SYMBOL_GPL(xenbus_mkdir);
514
515
516int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node)
517{
518 char *path;
519 int ret;
520
521 path = join(dir, node);
522 if (IS_ERR(path))
523 return PTR_ERR(path);
524
525 ret = xs_error(xs_single(t, XS_RM, path, NULL));
526 kfree(path);
527 return ret;
528}
529EXPORT_SYMBOL_GPL(xenbus_rm);
530
531
532
533
534int xenbus_transaction_start(struct xenbus_transaction *t)
535{
536 char *id_str;
537
538 id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL);
539 if (IS_ERR(id_str))
540 return PTR_ERR(id_str);
541
542 t->id = simple_strtoul(id_str, NULL, 0);
543 kfree(id_str);
544 return 0;
545}
546EXPORT_SYMBOL_GPL(xenbus_transaction_start);
547
548
549
550
551int xenbus_transaction_end(struct xenbus_transaction t, int abort)
552{
553 char abortstr[2];
554
555 if (abort)
556 strcpy(abortstr, "F");
557 else
558 strcpy(abortstr, "T");
559
560 return xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL));
561}
562EXPORT_SYMBOL_GPL(xenbus_transaction_end);
563
564
565int xenbus_scanf(struct xenbus_transaction t,
566 const char *dir, const char *node, const char *fmt, ...)
567{
568 va_list ap;
569 int ret;
570 char *val;
571
572 val = xenbus_read(t, dir, node, NULL);
573 if (IS_ERR(val))
574 return PTR_ERR(val);
575
576 va_start(ap, fmt);
577 ret = vsscanf(val, fmt, ap);
578 va_end(ap);
579 kfree(val);
580
581 if (ret == 0)
582 return -ERANGE;
583 return ret;
584}
585EXPORT_SYMBOL_GPL(xenbus_scanf);
586
587
588unsigned int xenbus_read_unsigned(const char *dir, const char *node,
589 unsigned int default_val)
590{
591 unsigned int val;
592 int ret;
593
594 ret = xenbus_scanf(XBT_NIL, dir, node, "%u", &val);
595 if (ret <= 0)
596 val = default_val;
597
598 return val;
599}
600EXPORT_SYMBOL_GPL(xenbus_read_unsigned);
601
602
603int xenbus_printf(struct xenbus_transaction t,
604 const char *dir, const char *node, const char *fmt, ...)
605{
606 va_list ap;
607 int ret;
608 char *buf;
609
610 va_start(ap, fmt);
611 buf = kvasprintf(GFP_NOIO | __GFP_HIGH, fmt, ap);
612 va_end(ap);
613
614 if (!buf)
615 return -ENOMEM;
616
617 ret = xenbus_write(t, dir, node, buf);
618
619 kfree(buf);
620
621 return ret;
622}
623EXPORT_SYMBOL_GPL(xenbus_printf);
624
625
626int xenbus_gather(struct xenbus_transaction t, const char *dir, ...)
627{
628 va_list ap;
629 const char *name;
630 int ret = 0;
631
632 va_start(ap, dir);
633 while (ret == 0 && (name = va_arg(ap, char *)) != NULL) {
634 const char *fmt = va_arg(ap, char *);
635 void *result = va_arg(ap, void *);
636 char *p;
637
638 p = xenbus_read(t, dir, name, NULL);
639 if (IS_ERR(p)) {
640 ret = PTR_ERR(p);
641 break;
642 }
643 if (fmt) {
644 if (sscanf(p, fmt, result) == 0)
645 ret = -EINVAL;
646 kfree(p);
647 } else
648 *(char **)result = p;
649 }
650 va_end(ap);
651 return ret;
652}
653EXPORT_SYMBOL_GPL(xenbus_gather);
654
655static int xs_watch(const char *path, const char *token)
656{
657 struct kvec iov[2];
658
659 iov[0].iov_base = (void *)path;
660 iov[0].iov_len = strlen(path) + 1;
661 iov[1].iov_base = (void *)token;
662 iov[1].iov_len = strlen(token) + 1;
663
664 return xs_error(xs_talkv(XBT_NIL, XS_WATCH, iov,
665 ARRAY_SIZE(iov), NULL));
666}
667
668static int xs_unwatch(const char *path, const char *token)
669{
670 struct kvec iov[2];
671
672 iov[0].iov_base = (char *)path;
673 iov[0].iov_len = strlen(path) + 1;
674 iov[1].iov_base = (char *)token;
675 iov[1].iov_len = strlen(token) + 1;
676
677 return xs_error(xs_talkv(XBT_NIL, XS_UNWATCH, iov,
678 ARRAY_SIZE(iov), NULL));
679}
680
681static struct xenbus_watch *find_watch(const char *token)
682{
683 struct xenbus_watch *i, *cmp;
684
685 cmp = (void *)simple_strtoul(token, NULL, 16);
686
687 list_for_each_entry(i, &watches, list)
688 if (i == cmp)
689 return i;
690
691 return NULL;
692}
693
694int xs_watch_msg(struct xs_watch_event *event)
695{
696 if (count_strings(event->body, event->len) != 2) {
697 kfree(event);
698 return -EINVAL;
699 }
700 event->path = (const char *)event->body;
701 event->token = (const char *)strchr(event->body, '\0') + 1;
702
703 spin_lock(&watches_lock);
704 event->handle = find_watch(event->token);
705 if (event->handle != NULL) {
706 spin_lock(&watch_events_lock);
707 list_add_tail(&event->list, &watch_events);
708 wake_up(&watch_events_waitq);
709 spin_unlock(&watch_events_lock);
710 } else
711 kfree(event);
712 spin_unlock(&watches_lock);
713
714 return 0;
715}
716
717
718
719
720
721
722
723static bool xen_strict_xenbus_quirk(void)
724{
725#ifdef CONFIG_X86
726 uint32_t eax, ebx, ecx, edx, base;
727
728 base = xen_cpuid_base();
729 cpuid(base + 1, &eax, &ebx, &ecx, &edx);
730
731 if ((eax >> 16) < 4)
732 return true;
733#endif
734 return false;
735
736}
737static void xs_reset_watches(void)
738{
739 int err;
740
741 if (!xen_hvm_domain() || xen_initial_domain())
742 return;
743
744 if (xen_strict_xenbus_quirk())
745 return;
746
747 if (!xenbus_read_unsigned("control",
748 "platform-feature-xs_reset_watches", 0))
749 return;
750
751 err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));
752 if (err && err != -EEXIST)
753 pr_warn("xs_reset_watches failed: %d\n", err);
754}
755
756
757int register_xenbus_watch(struct xenbus_watch *watch)
758{
759
760 char token[sizeof(watch) * 2 + 1];
761 int err;
762
763 sprintf(token, "%lX", (long)watch);
764
765 down_read(&xs_watch_rwsem);
766
767 spin_lock(&watches_lock);
768 BUG_ON(find_watch(token));
769 list_add(&watch->list, &watches);
770 spin_unlock(&watches_lock);
771
772 err = xs_watch(watch->node, token);
773
774 if (err) {
775 spin_lock(&watches_lock);
776 list_del(&watch->list);
777 spin_unlock(&watches_lock);
778 }
779
780 up_read(&xs_watch_rwsem);
781
782 return err;
783}
784EXPORT_SYMBOL_GPL(register_xenbus_watch);
785
786void unregister_xenbus_watch(struct xenbus_watch *watch)
787{
788 struct xs_watch_event *event, *tmp;
789 char token[sizeof(watch) * 2 + 1];
790 int err;
791
792 sprintf(token, "%lX", (long)watch);
793
794 down_read(&xs_watch_rwsem);
795
796 spin_lock(&watches_lock);
797 BUG_ON(!find_watch(token));
798 list_del(&watch->list);
799 spin_unlock(&watches_lock);
800
801 err = xs_unwatch(watch->node, token);
802 if (err)
803 pr_warn("Failed to release watch %s: %i\n", watch->node, err);
804
805 up_read(&xs_watch_rwsem);
806
807
808
809 if (current->pid != xenwatch_pid)
810 mutex_lock(&xenwatch_mutex);
811
812
813 spin_lock(&watch_events_lock);
814 list_for_each_entry_safe(event, tmp, &watch_events, list) {
815 if (event->handle != watch)
816 continue;
817 list_del(&event->list);
818 kfree(event);
819 }
820 spin_unlock(&watch_events_lock);
821
822 if (current->pid != xenwatch_pid)
823 mutex_unlock(&xenwatch_mutex);
824}
825EXPORT_SYMBOL_GPL(unregister_xenbus_watch);
826
827void xs_suspend(void)
828{
829 xs_suspend_enter();
830
831 down_write(&xs_watch_rwsem);
832 mutex_lock(&xs_response_mutex);
833}
834
835void xs_resume(void)
836{
837 struct xenbus_watch *watch;
838 char token[sizeof(watch) * 2 + 1];
839
840 xb_init_comms();
841
842 mutex_unlock(&xs_response_mutex);
843
844 xs_suspend_exit();
845
846
847 list_for_each_entry(watch, &watches, list) {
848 sprintf(token, "%lX", (long)watch);
849 xs_watch(watch->node, token);
850 }
851
852 up_write(&xs_watch_rwsem);
853}
854
855void xs_suspend_cancel(void)
856{
857 mutex_unlock(&xs_response_mutex);
858 up_write(&xs_watch_rwsem);
859
860 xs_suspend_exit();
861}
862
863static int xenwatch_thread(void *unused)
864{
865 struct list_head *ent;
866 struct xs_watch_event *event;
867
868 xenwatch_pid = current->pid;
869
870 for (;;) {
871 wait_event_interruptible(watch_events_waitq,
872 !list_empty(&watch_events));
873
874 if (kthread_should_stop())
875 break;
876
877 mutex_lock(&xenwatch_mutex);
878
879 spin_lock(&watch_events_lock);
880 ent = watch_events.next;
881 if (ent != &watch_events)
882 list_del(ent);
883 spin_unlock(&watch_events_lock);
884
885 if (ent != &watch_events) {
886 event = list_entry(ent, struct xs_watch_event, list);
887 event->handle->callback(event->handle, event->path,
888 event->token);
889 kfree(event);
890 }
891
892 mutex_unlock(&xenwatch_mutex);
893 }
894
895 return 0;
896}
897
898
899
900
901
902
903
904
905static int xs_reboot_notify(struct notifier_block *nb,
906 unsigned long code, void *unused)
907{
908 struct xb_req_data *req;
909
910 mutex_lock(&xb_write_mutex);
911 list_for_each_entry(req, &xs_reply_list, list)
912 wake_up(&req->wq);
913 list_for_each_entry(req, &xb_write_list, list)
914 wake_up(&req->wq);
915 mutex_unlock(&xb_write_mutex);
916 return NOTIFY_DONE;
917}
918
919static struct notifier_block xs_reboot_nb = {
920 .notifier_call = xs_reboot_notify,
921};
922
923int xs_init(void)
924{
925 int err;
926 struct task_struct *task;
927
928 register_reboot_notifier(&xs_reboot_nb);
929
930
931 err = xb_init_comms();
932 if (err)
933 return err;
934
935 task = kthread_run(xenwatch_thread, NULL, "xenwatch");
936 if (IS_ERR(task))
937 return PTR_ERR(task);
938
939
940 xs_reset_watches();
941
942 return 0;
943}
944