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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 | // SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2017 - Cambridge Greys Ltd * Copyright (C) 2011 - 2014 Cisco Systems Inc * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) * Derived (i.e. mostly copied) from arch/i386/kernel/irq.c: * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar */ #include <linux/cpumask.h> #include <linux/hardirq.h> #include <linux/interrupt.h> #include <linux/kernel_stat.h> #include <linux/module.h> #include <linux/sched.h> #include <linux/seq_file.h> #include <linux/slab.h> #include <as-layout.h> #include <kern_util.h> #include <os.h> #include <irq_user.h> #include <irq_kern.h> #include <linux/time-internal.h> extern void free_irqs(void); /* When epoll triggers we do not know why it did so * we can also have different IRQs for read and write. * This is why we keep a small irq_reg array for each fd - * one entry per IRQ type */ struct irq_reg { void *id; int irq; /* it's cheaper to store this than to query it */ int events; bool active; bool pending; bool wakeup; #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT bool pending_on_resume; void (*timetravel_handler)(int, int, void *, struct time_travel_event *); struct time_travel_event event; #endif }; struct irq_entry { struct list_head list; int fd; struct irq_reg reg[NUM_IRQ_TYPES]; bool suspended; bool sigio_workaround; }; static DEFINE_SPINLOCK(irq_lock); static LIST_HEAD(active_fds); static DECLARE_BITMAP(irqs_allocated, UM_LAST_SIGNAL_IRQ); static bool irqs_suspended; static void irq_io_loop(struct irq_reg *irq, struct uml_pt_regs *regs) { /* * irq->active guards against reentry * irq->pending accumulates pending requests * if pending is raised the irq_handler is re-run * until pending is cleared */ if (irq->active) { irq->active = false; do { irq->pending = false; do_IRQ(irq->irq, regs); } while (irq->pending); irq->active = true; } else { irq->pending = true; } } #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT static void irq_event_handler(struct time_travel_event *ev) { struct irq_reg *reg = container_of(ev, struct irq_reg, event); /* do nothing if suspended - just to cause a wakeup */ if (irqs_suspended) return; generic_handle_irq(reg->irq); } static bool irq_do_timetravel_handler(struct irq_entry *entry, enum um_irq_type t) { struct irq_reg *reg = &entry->reg[t]; if (!reg->timetravel_handler) return false; /* * Handle all messages - we might get multiple even while * interrupts are already suspended, due to suspend order * etc. Note that time_travel_add_irq_event() will not add * an event twice, if it's pending already "first wins". */ reg->timetravel_handler(reg->irq, entry->fd, reg->id, ®->event); if (!reg->event.pending) return false; if (irqs_suspended) reg->pending_on_resume = true; return true; } #else static bool irq_do_timetravel_handler(struct irq_entry *entry, enum um_irq_type t) { return false; } #endif static void sigio_reg_handler(int idx, struct irq_entry *entry, enum um_irq_type t, struct uml_pt_regs *regs, bool timetravel_handlers_only) { struct irq_reg *reg = &entry->reg[t]; if (!reg->events) return; if (os_epoll_triggered(idx, reg->events) <= 0) return; if (irq_do_timetravel_handler(entry, t)) return; /* * If we're called to only run time-travel handlers then don't * actually proceed but mark sigio as pending (if applicable). * For suspend/resume, timetravel_handlers_only may be true * despite time-travel not being configured and used. */ if (timetravel_handlers_only) { #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT mark_sigio_pending(); #endif return; } irq_io_loop(reg, regs); } static void _sigio_handler(struct uml_pt_regs *regs, bool timetravel_handlers_only) { struct irq_entry *irq_entry; int n, i; if (timetravel_handlers_only && !um_irq_timetravel_handler_used()) return; while (1) { /* This is now lockless - epoll keeps back-referencesto the irqs * which have trigger it so there is no need to walk the irq * list and lock it every time. We avoid locking by turning off * IO for a specific fd by executing os_del_epoll_fd(fd) before * we do any changes to the actual data structures */ n = os_waiting_for_events_epoll(); if (n <= 0) { if (n == -EINTR) continue; else break; } for (i = 0; i < n ; i++) { enum um_irq_type t; irq_entry = os_epoll_get_data_pointer(i); for (t = 0; t < NUM_IRQ_TYPES; t++) sigio_reg_handler(i, irq_entry, t, regs, timetravel_handlers_only); } } if (!timetravel_handlers_only) free_irqs(); } void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) { _sigio_handler(regs, irqs_suspended); } static struct irq_entry *get_irq_entry_by_fd(int fd) { struct irq_entry *walk; lockdep_assert_held(&irq_lock); list_for_each_entry(walk, &active_fds, list) { if (walk->fd == fd) return walk; } return NULL; } static void free_irq_entry(struct irq_entry *to_free, bool remove) { if (!to_free) return; if (remove) os_del_epoll_fd(to_free->fd); list_del(&to_free->list); kfree(to_free); } static bool update_irq_entry(struct irq_entry *entry) { enum um_irq_type i; int events = 0; for (i = 0; i < NUM_IRQ_TYPES; i++) events |= entry->reg[i].events; if (events) { /* will modify (instead of add) if needed */ os_add_epoll_fd(events, entry->fd, entry); return true; } os_del_epoll_fd(entry->fd); return false; } static void update_or_free_irq_entry(struct irq_entry *entry) { if (!update_irq_entry(entry)) free_irq_entry(entry, false); } static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id, void (*timetravel_handler)(int, int, void *, struct time_travel_event *)) { struct irq_entry *irq_entry; int err, events = os_event_mask(type); unsigned long flags; err = os_set_fd_async(fd); if (err < 0) goto out; spin_lock_irqsave(&irq_lock, flags); irq_entry = get_irq_entry_by_fd(fd); if (irq_entry) { /* cannot register the same FD twice with the same type */ if (WARN_ON(irq_entry->reg[type].events)) { err = -EALREADY; goto out_unlock; } /* temporarily disable to avoid IRQ-side locking */ os_del_epoll_fd(fd); } else { irq_entry = kzalloc(sizeof(*irq_entry), GFP_ATOMIC); if (!irq_entry) { err = -ENOMEM; goto out_unlock; } irq_entry->fd = fd; list_add_tail(&irq_entry->list, &active_fds); maybe_sigio_broken(fd); } irq_entry->reg[type].id = dev_id; irq_entry->reg[type].irq = irq; irq_entry->reg[type].active = true; irq_entry->reg[type].events = events; #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT if (um_irq_timetravel_handler_used()) { irq_entry->reg[type].timetravel_handler = timetravel_handler; irq_entry->reg[type].event.fn = irq_event_handler; } #endif WARN_ON(!update_irq_entry(irq_entry)); spin_unlock_irqrestore(&irq_lock, flags); return 0; out_unlock: spin_unlock_irqrestore(&irq_lock, flags); out: return err; } /* * Remove the entry or entries for a specific FD, if you * don't want to remove all the possible entries then use * um_free_irq() or deactivate_fd() instead. */ void free_irq_by_fd(int fd) { struct irq_entry *to_free; unsigned long flags; spin_lock_irqsave(&irq_lock, flags); to_free = get_irq_entry_by_fd(fd); free_irq_entry(to_free, true); spin_unlock_irqrestore(&irq_lock, flags); } EXPORT_SYMBOL(free_irq_by_fd); static void free_irq_by_irq_and_dev(unsigned int irq, void *dev) { struct irq_entry *entry; unsigned long flags; spin_lock_irqsave(&irq_lock, flags); list_for_each_entry(entry, &active_fds, list) { enum um_irq_type i; for (i = 0; i < NUM_IRQ_TYPES; i++) { struct irq_reg *reg = &entry->reg[i]; if (!reg->events) continue; if (reg->irq != irq) continue; if (reg->id != dev) continue; os_del_epoll_fd(entry->fd); reg->events = 0; update_or_free_irq_entry(entry); goto out; } } out: spin_unlock_irqrestore(&irq_lock, flags); } void deactivate_fd(int fd, int irqnum) { struct irq_entry *entry; unsigned long flags; enum um_irq_type i; os_del_epoll_fd(fd); spin_lock_irqsave(&irq_lock, flags); entry = get_irq_entry_by_fd(fd); if (!entry) goto out; for (i = 0; i < NUM_IRQ_TYPES; i++) { if (!entry->reg[i].events) continue; if (entry->reg[i].irq == irqnum) entry->reg[i].events = 0; } update_or_free_irq_entry(entry); out: spin_unlock_irqrestore(&irq_lock, flags); ignore_sigio_fd(fd); } EXPORT_SYMBOL(deactivate_fd); /* * Called just before shutdown in order to provide a clean exec * environment in case the system is rebooting. No locking because * that would cause a pointless shutdown hang if something hadn't * released the lock. */ int deactivate_all_fds(void) { struct irq_entry *entry; /* Stop IO. The IRQ loop has no lock so this is our * only way of making sure we are safe to dispose * of all IRQ handlers */ os_set_ioignore(); /* we can no longer call kfree() here so just deactivate */ list_for_each_entry(entry, &active_fds, list) os_del_epoll_fd(entry->fd); os_close_epoll_fd(); return 0; } /* * do_IRQ handles all normal device IRQs (the special * SMP cross-CPU interrupts have their own specific * handlers). */ unsigned int do_IRQ(int irq, struct uml_pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs((struct pt_regs *)regs); irq_enter(); generic_handle_irq(irq); irq_exit(); set_irq_regs(old_regs); return 1; } void um_free_irq(int irq, void *dev) { if (WARN(irq < 0 || irq > UM_LAST_SIGNAL_IRQ, "freeing invalid irq %d", irq)) return; free_irq_by_irq_and_dev(irq, dev); free_irq(irq, dev); clear_bit(irq, irqs_allocated); } EXPORT_SYMBOL(um_free_irq); static int _um_request_irq(int irq, int fd, enum um_irq_type type, irq_handler_t handler, unsigned long irqflags, const char *devname, void *dev_id, void (*timetravel_handler)(int, int, void *, struct time_travel_event *)) { int err; if (irq == UM_IRQ_ALLOC) { int i; for (i = UM_FIRST_DYN_IRQ; i < NR_IRQS; i++) { if (!test_and_set_bit(i, irqs_allocated)) { irq = i; break; } } } if (irq < 0) return -ENOSPC; if (fd != -1) { err = activate_fd(irq, fd, type, dev_id, timetravel_handler); if (err) goto error; } err = request_irq(irq, handler, irqflags, devname, dev_id); if (err < 0) goto error; return irq; error: clear_bit(irq, irqs_allocated); return err; } int um_request_irq(int irq, int fd, enum um_irq_type type, irq_handler_t handler, unsigned long irqflags, const char *devname, void *dev_id) { return _um_request_irq(irq, fd, type, handler, irqflags, devname, dev_id, NULL); } EXPORT_SYMBOL(um_request_irq); #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT int um_request_irq_tt(int irq, int fd, enum um_irq_type type, irq_handler_t handler, unsigned long irqflags, const char *devname, void *dev_id, void (*timetravel_handler)(int, int, void *, struct time_travel_event *)) { return _um_request_irq(irq, fd, type, handler, irqflags, devname, dev_id, timetravel_handler); } EXPORT_SYMBOL(um_request_irq_tt); void sigio_run_timetravel_handlers(void) { _sigio_handler(NULL, true); } #endif #ifdef CONFIG_PM_SLEEP void um_irqs_suspend(void) { struct irq_entry *entry; unsigned long flags; irqs_suspended = true; spin_lock_irqsave(&irq_lock, flags); list_for_each_entry(entry, &active_fds, list) { enum um_irq_type t; bool clear = true; for (t = 0; t < NUM_IRQ_TYPES; t++) { if (!entry->reg[t].events) continue; /* * For the SIGIO_WRITE_IRQ, which is used to handle the * SIGIO workaround thread, we need special handling: * enable wake for it itself, but below we tell it about * any FDs that should be suspended. */ if (entry->reg[t].wakeup || entry->reg[t].irq == SIGIO_WRITE_IRQ #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT || entry->reg[t].timetravel_handler #endif ) { clear = false; break; } } if (clear) { entry->suspended = true; os_clear_fd_async(entry->fd); entry->sigio_workaround = !__ignore_sigio_fd(entry->fd); } } spin_unlock_irqrestore(&irq_lock, flags); } void um_irqs_resume(void) { struct irq_entry *entry; unsigned long flags; local_irq_save(flags); #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT /* * We don't need to lock anything here since we're in resume * and nothing else is running, but have disabled IRQs so we * don't try anything else with the interrupt list from there. */ list_for_each_entry(entry, &active_fds, list) { enum um_irq_type t; for (t = 0; t < NUM_IRQ_TYPES; t++) { struct irq_reg *reg = &entry->reg[t]; if (reg->pending_on_resume) { irq_enter(); generic_handle_irq(reg->irq); irq_exit(); reg->pending_on_resume = false; } } } #endif spin_lock(&irq_lock); list_for_each_entry(entry, &active_fds, list) { if (entry->suspended) { int err = os_set_fd_async(entry->fd); WARN(err < 0, "os_set_fd_async returned %d\n", err); entry->suspended = false; if (entry->sigio_workaround) { err = __add_sigio_fd(entry->fd); WARN(err < 0, "add_sigio_returned %d\n", err); } } } spin_unlock_irqrestore(&irq_lock, flags); irqs_suspended = false; send_sigio_to_self(); } static int normal_irq_set_wake(struct irq_data *d, unsigned int on) { struct irq_entry *entry; unsigned long flags; spin_lock_irqsave(&irq_lock, flags); list_for_each_entry(entry, &active_fds, list) { enum um_irq_type t; for (t = 0; t < NUM_IRQ_TYPES; t++) { if (!entry->reg[t].events) continue; if (entry->reg[t].irq != d->irq) continue; entry->reg[t].wakeup = on; goto unlock; } } unlock: spin_unlock_irqrestore(&irq_lock, flags); return 0; } #else #define normal_irq_set_wake NULL #endif /* * irq_chip must define at least enable/disable and ack when * the edge handler is used. */ static void dummy(struct irq_data *d) { } /* This is used for everything other than the timer. */ static struct irq_chip normal_irq_type = { .name = "SIGIO", .irq_disable = dummy, .irq_enable = dummy, .irq_ack = dummy, .irq_mask = dummy, .irq_unmask = dummy, .irq_set_wake = normal_irq_set_wake, }; static struct irq_chip alarm_irq_type = { .name = "SIGALRM", .irq_disable = dummy, .irq_enable = dummy, .irq_ack = dummy, .irq_mask = dummy, .irq_unmask = dummy, }; void __init init_IRQ(void) { int i; irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_edge_irq); for (i = 1; i < UM_LAST_SIGNAL_IRQ; i++) irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq); /* Initialize EPOLL Loop */ os_setup_epoll(); } /* * IRQ stack entry and exit: * * Unlike i386, UML doesn't receive IRQs on the normal kernel stack * and switch over to the IRQ stack after some preparation. We use * sigaltstack to receive signals on a separate stack from the start. * These two functions make sure the rest of the kernel won't be too * upset by being on a different stack. The IRQ stack has a * thread_info structure at the bottom so that current et al continue * to work. * * to_irq_stack copies the current task's thread_info to the IRQ stack * thread_info and sets the tasks's stack to point to the IRQ stack. * * from_irq_stack copies the thread_info struct back (flags may have * been modified) and resets the task's stack pointer. * * Tricky bits - * * What happens when two signals race each other? UML doesn't block * signals with sigprocmask, SA_DEFER, or sa_mask, so a second signal * could arrive while a previous one is still setting up the * thread_info. * * There are three cases - * The first interrupt on the stack - sets up the thread_info and * handles the interrupt * A nested interrupt interrupting the copying of the thread_info - * can't handle the interrupt, as the stack is in an unknown state * A nested interrupt not interrupting the copying of the * thread_info - doesn't do any setup, just handles the interrupt * * The first job is to figure out whether we interrupted stack setup. * This is done by xchging the signal mask with thread_info->pending. * If the value that comes back is zero, then there is no setup in * progress, and the interrupt can be handled. If the value is * non-zero, then there is stack setup in progress. In order to have * the interrupt handled, we leave our signal in the mask, and it will * be handled by the upper handler after it has set up the stack. * * Next is to figure out whether we are the outer handler or a nested * one. As part of setting up the stack, thread_info->real_thread is * set to non-NULL (and is reset to NULL on exit). This is the * nesting indicator. If it is non-NULL, then the stack is already * set up and the handler can run. */ static unsigned long pending_mask; unsigned long to_irq_stack(unsigned long *mask_out) { struct thread_info *ti; unsigned long mask, old; int nested; mask = xchg(&pending_mask, *mask_out); if (mask != 0) { /* * If any interrupts come in at this point, we want to * make sure that their bits aren't lost by our * putting our bit in. So, this loop accumulates bits * until xchg returns the same value that we put in. * When that happens, there were no new interrupts, * and pending_mask contains a bit for each interrupt * that came in. */ old = *mask_out; do { old |= mask; mask = xchg(&pending_mask, old); } while (mask != old); return 1; } ti = current_thread_info(); nested = (ti->real_thread != NULL); if (!nested) { struct task_struct *task; struct thread_info *tti; task = cpu_tasks[ti->cpu].task; tti = task_thread_info(task); *ti = *tti; ti->real_thread = tti; task->stack = ti; } mask = xchg(&pending_mask, 0); *mask_out |= mask | nested; return 0; } unsigned long from_irq_stack(int nested) { struct thread_info *ti, *to; unsigned long mask; ti = current_thread_info(); pending_mask = 1; to = ti->real_thread; current->stack = to; ti->real_thread = NULL; *to = *ti; mask = xchg(&pending_mask, 0); return mask & ~1; } |