kernel/events/hw_breakpoint.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  15  *
  16  * Copyright (C) 2007 Alan Stern
  17  * Copyright (C) IBM Corporation, 2009
  18  * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
  19  *
  20  * Thanks to Ingo Molnar for his many suggestions.
  21  *
  22  * Authors: Alan Stern <stern@rowland.harvard.edu>
  23  *          K.Prasad <prasad@linux.vnet.ibm.com>
  24  *          Frederic Weisbecker <fweisbec@gmail.com>
  25  */
  26
  27 /*
  28  * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
  29  * using the CPU's debug registers.
  30  * This file contains the arch-independent routines.
  31  */
  32
  33 #include <linux/irqflags.h>
  34 #include <linux/kallsyms.h>
  35 #include <linux/notifier.h>
  36 #include <linux/kprobes.h>
  37 #include <linux/kdebug.h>
  38 #include <linux/kernel.h>
  39 #include <linux/module.h>
  40 #include <linux/percpu.h>
  41 #include <linux/sched.h>
  42 #include <linux/init.h>
  43 #include <linux/slab.h>
  44 #include <linux/list.h>
  45 #include <linux/cpu.h>
  46 #include <linux/smp.h>
  47 #include <linux/bug.h>
  48
  49 #include <linux/hw_breakpoint.h>
  50 /*
  51  * Constraints data
  52  */
  53 struct bp_cpuinfo {
  54         /* Number of pinned cpu breakpoints in a cpu */
  55         unsigned int    cpu_pinned;
  56         /* tsk_pinned[n] is the number of tasks having n+1 breakpoints */
  57         unsigned int    *tsk_pinned;
  58         /* Number of non-pinned cpu/task breakpoints in a cpu */
  59         unsigned int    flexible; /* XXX: placeholder, see fetch_this_slot() */
  60 };
  61
  62 static DEFINE_PER_CPU(struct bp_cpuinfo, bp_cpuinfo[TYPE_MAX]);
  63 static int nr_slots[TYPE_MAX];
  64
  65 static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type)
  66 {
  67         return per_cpu_ptr(bp_cpuinfo + type, cpu);
  68 }
  69
  70 /* Keep track of the breakpoints attached to tasks */
  71 static LIST_HEAD(bp_task_head);
  72
  73 static int constraints_initialized;
  74
  75 /* Gather the number of total pinned and un-pinned bp in a cpuset */
  76 struct bp_busy_slots {
  77         unsigned int pinned;
  78         unsigned int flexible;
  79 };
  80
  81 /* Serialize accesses to the above constraints */
  82 static DEFINE_MUTEX(nr_bp_mutex);
  83
  84 __weak int hw_breakpoint_weight(struct perf_event *bp)
  85 {
  86         return 1;
  87 }
  88
  89 static inline enum bp_type_idx find_slot_idx(u64 bp_type)
  90 {
  91         if (bp_type & HW_BREAKPOINT_RW)
  92                 return TYPE_DATA;
  93
  94         return TYPE_INST;
  95 }
  96
  97 /*
  98  * Report the maximum number of pinned breakpoints a task
  99  * have in this cpu
 100  */
 101 static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
 102 {
 103         unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned;
 104         int i;
 105
 106         for (i = nr_slots[type] - 1; i >= 0; i--) {
 107                 if (tsk_pinned[i] > 0)
 108                         return i + 1;
 109         }
 110
 111         return 0;
 112 }
 113
 114 /*
 115  * Count the number of breakpoints of the same type and same task.
 116  * The given event must be not on the list.
 117  */
 118 static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type)
 119 {
 120         struct task_struct *tsk = bp->hw.target;
 121         struct perf_event *iter;
 122         int count = 0;
 123
 124         list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
 125                 if (iter->hw.target == tsk &&
 126                     find_slot_idx(iter->attr.bp_type) == type &&
 127                     (iter->cpu < 0 || cpu == iter->cpu))
 128                         count += hw_breakpoint_weight(iter);
 129         }
 130
 131         return count;
 132 }
 133
 134 static const struct cpumask *cpumask_of_bp(struct perf_event *bp)
 135 {
 136         if (bp->cpu >= 0)
 137                 return cpumask_of(bp->cpu);
 138         return cpu_possible_mask;
 139 }
 140
 141 /*
 142  * Report the number of pinned/un-pinned breakpoints we have in
 143  * a given cpu (cpu > -1) or in all of them (cpu = -1).
 144  */
 145 static void
 146 fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
 147                     enum bp_type_idx type)
 148 {
 149         const struct cpumask *cpumask = cpumask_of_bp(bp);
 150         int cpu;
 151
 152         for_each_cpu(cpu, cpumask) {
 153                 struct bp_cpuinfo *info = get_bp_info(cpu, type);
 154                 int nr;
 155
 156                 nr = info->cpu_pinned;
 157                 if (!bp->hw.target)
 158                         nr += max_task_bp_pinned(cpu, type);
 159                 else
 160                         nr += task_bp_pinned(cpu, bp, type);
 161
 162                 if (nr > slots->pinned)
 163                         slots->pinned = nr;
 164
 165                 nr = info->flexible;
 166                 if (nr > slots->flexible)
 167                         slots->flexible = nr;
 168         }
 169 }
 170
 171 /*
 172  * For now, continue to consider flexible as pinned, until we can
 173  * ensure no flexible event can ever be scheduled before a pinned event
 174  * in a same cpu.
 175  */
 176 static void
 177 fetch_this_slot(struct bp_busy_slots *slots, int weight)
 178 {
 179         slots->pinned += weight;
 180 }
 181
 182 /*
 183  * Add a pinned breakpoint for the given task in our constraint table
 184  */
 185 static void toggle_bp_task_slot(struct perf_event *bp, int cpu,
 186                                 enum bp_type_idx type, int weight)
 187 {
 188         unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned;
 189         int old_idx, new_idx;
 190
 191         old_idx = task_bp_pinned(cpu, bp, type) - 1;
 192         new_idx = old_idx + weight;
 193
 194         if (old_idx >= 0)
 195                 tsk_pinned[old_idx]--;
 196         if (new_idx >= 0)
 197                 tsk_pinned[new_idx]++;
 198 }
 199
 200 /*
 201  * Add/remove the given breakpoint in our constraint table
 202  */
 203 static void
 204 toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
 205                int weight)
 206 {
 207         const struct cpumask *cpumask = cpumask_of_bp(bp);
 208         int cpu;
 209
 210         if (!enable)
 211                 weight = -weight;
 212
 213         /* Pinned counter cpu profiling */
 214         if (!bp->hw.target) {
 215                 get_bp_info(bp->cpu, type)->cpu_pinned += weight;
 216                 return;
 217         }
 218
 219         /* Pinned counter task profiling */
 220         for_each_cpu(cpu, cpumask)
 221                 toggle_bp_task_slot(bp, cpu, type, weight);
 222
 223         if (enable)
 224                 list_add_tail(&bp->hw.bp_list, &bp_task_head);
 225         else
 226                 list_del(&bp->hw.bp_list);
 227 }
 228
 229 /*
 230  * Function to perform processor-specific cleanup during unregistration
 231  */
 232 __weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
 233 {
 234         /*
 235          * A weak stub function here for those archs that don't define
 236          * it inside arch/.../kernel/hw_breakpoint.c
 237          */
 238 }
 239
 240 /*
 241  * Contraints to check before allowing this new breakpoint counter:
 242  *
 243  *  == Non-pinned counter == (Considered as pinned for now)
 244  *
 245  *   - If attached to a single cpu, check:
 246  *
 247  *       (per_cpu(info->flexible, cpu) || (per_cpu(info->cpu_pinned, cpu)
 248  *           + max(per_cpu(info->tsk_pinned, cpu)))) < HBP_NUM
 249  *
 250  *       -> If there are already non-pinned counters in this cpu, it means
 251  *          there is already a free slot for them.
 252  *          Otherwise, we check that the maximum number of per task
 253  *          breakpoints (for this cpu) plus the number of per cpu breakpoint
 254  *          (for this cpu) doesn't cover every registers.
 255  *
 256  *   - If attached to every cpus, check:
 257  *
 258  *       (per_cpu(info->flexible, *) || (max(per_cpu(info->cpu_pinned, *))
 259  *           + max(per_cpu(info->tsk_pinned, *)))) < HBP_NUM
 260  *
 261  *       -> This is roughly the same, except we check the number of per cpu
 262  *          bp for every cpu and we keep the max one. Same for the per tasks
 263  *          breakpoints.
 264  *
 265  *
 266  * == Pinned counter ==
 267  *
 268  *   - If attached to a single cpu, check:
 269  *
 270  *       ((per_cpu(info->flexible, cpu) > 1) + per_cpu(info->cpu_pinned, cpu)
 271  *            + max(per_cpu(info->tsk_pinned, cpu))) < HBP_NUM
 272  *
 273  *       -> Same checks as before. But now the info->flexible, if any, must keep
 274  *          one register at least (or they will never be fed).
 275  *
 276  *   - If attached to every cpus, check:
 277  *
 278  *       ((per_cpu(info->flexible, *) > 1) + max(per_cpu(info->cpu_pinned, *))
 279  *            + max(per_cpu(info->tsk_pinned, *))) < HBP_NUM
 280  */
 281 static int __reserve_bp_slot(struct perf_event *bp, u64 bp_type)
 282 {
 283         struct bp_busy_slots slots = {0};
 284         enum bp_type_idx type;
 285         int weight;
 286
 287         /* We couldn't initialize breakpoint constraints on boot */
 288         if (!constraints_initialized)
 289                 return -ENOMEM;
 290
 291         /* Basic checks */
 292         if (bp_type == HW_BREAKPOINT_EMPTY ||
 293             bp_type == HW_BREAKPOINT_INVALID)
 294                 return -EINVAL;
 295
 296         type = find_slot_idx(bp_type);
 297         weight = hw_breakpoint_weight(bp);
 298
 299         fetch_bp_busy_slots(&slots, bp, type);
 300         /*
 301          * Simulate the addition of this breakpoint to the constraints
 302          * and see the result.
 303          */
 304         fetch_this_slot(&slots, weight);
 305
 306         /* Flexible counters need to keep at least one slot */
 307         if (slots.pinned + (!!slots.flexible) > nr_slots[type])
 308                 return -ENOSPC;
 309
 310         toggle_bp_slot(bp, true, type, weight);
 311
 312         return 0;
 313 }
 314
 315 int reserve_bp_slot(struct perf_event *bp)
 316 {
 317         int ret;
 318
 319         mutex_lock(&nr_bp_mutex);
 320
 321         ret = __reserve_bp_slot(bp, bp->attr.bp_type);
 322
 323         mutex_unlock(&nr_bp_mutex);
 324
 325         return ret;
 326 }
 327
 328 static void __release_bp_slot(struct perf_event *bp, u64 bp_type)
 329 {
 330         enum bp_type_idx type;
 331         int weight;
 332
 333         type = find_slot_idx(bp_type);
 334         weight = hw_breakpoint_weight(bp);
 335         toggle_bp_slot(bp, false, type, weight);
 336 }
 337
 338 void release_bp_slot(struct perf_event *bp)
 339 {
 340         mutex_lock(&nr_bp_mutex);
 341
 342         arch_unregister_hw_breakpoint(bp);
 343         __release_bp_slot(bp, bp->attr.bp_type);
 344
 345         mutex_unlock(&nr_bp_mutex);
 346 }
 347
 348 static int __modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type)
 349 {
 350         int err;
 351
 352         __release_bp_slot(bp, old_type);
 353
 354         err = __reserve_bp_slot(bp, new_type);
 355         if (err) {
 356                 /*
 357                  * Reserve the old_type slot back in case
 358                  * there's no space for the new type.
 359                  *
 360                  * This must succeed, because we just released
 361                  * the old_type slot in the __release_bp_slot
 362                  * call above. If not, something is broken.
 363                  */
 364                 WARN_ON(__reserve_bp_slot(bp, old_type));
 365         }
 366
 367         return err;
 368 }
 369
 370 static int modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type)
 371 {
 372         int ret;
 373
 374         mutex_lock(&nr_bp_mutex);
 375         ret = __modify_bp_slot(bp, old_type, new_type);
 376         mutex_unlock(&nr_bp_mutex);
 377         return ret;
 378 }
 379
 380 /*
 381  * Allow the kernel debugger to reserve breakpoint slots without
 382  * taking a lock using the dbg_* variant of for the reserve and
 383  * release breakpoint slots.
 384  */
 385 int dbg_reserve_bp_slot(struct perf_event *bp)
 386 {
 387         if (mutex_is_locked(&nr_bp_mutex))
 388                 return -1;
 389
 390         return __reserve_bp_slot(bp, bp->attr.bp_type);
 391 }
 392
 393 int dbg_release_bp_slot(struct perf_event *bp)
 394 {
 395         if (mutex_is_locked(&nr_bp_mutex))
 396                 return -1;
 397
 398         __release_bp_slot(bp, bp->attr.bp_type);
 399
 400         return 0;
 401 }
 402
 403 static int hw_breakpoint_parse(struct perf_event *bp,
 404                                const struct perf_event_attr *attr,
 405                                struct arch_hw_breakpoint *hw)
 406 {
 407         int err;
 408
 409         err = hw_breakpoint_arch_parse(bp, attr, hw);
 410         if (err)
 411                 return err;
 412
 413         if (arch_check_bp_in_kernelspace(hw)) {
 414                 if (attr->exclude_kernel)
 415                         return -EINVAL;
 416                 /*
 417                  * Don't let unprivileged users set a breakpoint in the trap
 418                  * path to avoid trap recursion attacks.
 419                  */
 420                 if (!capable(CAP_SYS_ADMIN))
 421                         return -EPERM;
 422         }
 423
 424         return 0;
 425 }
 426
 427 int register_perf_hw_breakpoint(struct perf_event *bp)
 428 {
 429         struct arch_hw_breakpoint hw;
 430         int err;
 431
 432         err = reserve_bp_slot(bp);
 433         if (err)
 434                 return err;
 435
 436         err = hw_breakpoint_parse(bp, &bp->attr, &hw);
 437         if (err) {
 438                 release_bp_slot(bp);
 439                 return err;
 440         }
 441
 442         bp->hw.info = hw;
 443
 444         return 0;
 445 }
 446
 447 /**
 448  * register_user_hw_breakpoint - register a hardware breakpoint for user space
 449  * @attr: breakpoint attributes
 450  * @triggered: callback to trigger when we hit the breakpoint
 451  * @tsk: pointer to 'task_struct' of the process to which the address belongs
 452  */
 453 struct perf_event *
 454 register_user_hw_breakpoint(struct perf_event_attr *attr,
 455                             perf_overflow_handler_t triggered,
 456                             void *context,
 457                             struct task_struct *tsk)
 458 {
 459         return perf_event_create_kernel_counter(attr, -1, tsk, triggered,
 460                                                 context);
 461 }
 462 EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
 463
 464 static void hw_breakpoint_copy_attr(struct perf_event_attr *to,
 465                                     struct perf_event_attr *from)
 466 {
 467         to->bp_addr = from->bp_addr;
 468         to->bp_type = from->bp_type;
 469         to->bp_len  = from->bp_len;
 470         to->disabled = from->disabled;
 471 }
 472
 473 int
 474 modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *attr,
 475                                 bool check)
 476 {
 477         struct arch_hw_breakpoint hw;
 478         int err;
 479
 480         err = hw_breakpoint_parse(bp, attr, &hw);
 481         if (err)
 482                 return err;
 483
 484         if (check) {
 485                 struct perf_event_attr old_attr;
 486
 487                 old_attr = bp->attr;
 488                 hw_breakpoint_copy_attr(&old_attr, attr);
 489                 if (memcmp(&old_attr, attr, sizeof(*attr)))
 490                         return -EINVAL;
 491         }
 492
 493         if (bp->attr.bp_type != attr->bp_type) {
 494                 err = modify_bp_slot(bp, bp->attr.bp_type, attr->bp_type);
 495                 if (err)
 496                         return err;
 497         }
 498
 499         hw_breakpoint_copy_attr(&bp->attr, attr);
 500         bp->hw.info = hw;
 501
 502         return 0;
 503 }
 504
 505 /**
 506  * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
 507  * @bp: the breakpoint structure to modify
 508  * @attr: new breakpoint attributes
 509  */
 510 int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
 511 {
 512         /*
 513          * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it
 514          * will not be possible to raise IPIs that invoke __perf_event_disable.
 515          * So call the function directly after making sure we are targeting the
 516          * current task.
 517          */
 518         if (irqs_disabled() && bp->ctx && bp->ctx->task == current)
 519                 perf_event_disable_local(bp);
 520         else
 521                 perf_event_disable(bp);
 522
 523         if (!attr->disabled) {
 524                 int err = modify_user_hw_breakpoint_check(bp, attr, false);
 525
 526                 if (err)
 527                         return err;
 528                 perf_event_enable(bp);
 529                 bp->attr.disabled = 0;
 530         }
 531         return 0;
 532 }
 533 EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
 534
 535 /**
 536  * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
 537  * @bp: the breakpoint structure to unregister
 538  */
 539 void unregister_hw_breakpoint(struct perf_event *bp)
 540 {
 541         if (!bp)
 542                 return;
 543         perf_event_release_kernel(bp);
 544 }
 545 EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
 546
 547 /**
 548  * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
 549  * @attr: breakpoint attributes
 550  * @triggered: callback to trigger when we hit the breakpoint
 551  *
 552  * @return a set of per_cpu pointers to perf events
 553  */
 554 struct perf_event * __percpu *
 555 register_wide_hw_breakpoint(struct perf_event_attr *attr,
 556                             perf_overflow_handler_t triggered,
 557                             void *context)
 558 {
 559         struct perf_event * __percpu *cpu_events, *bp;
 560         long err = 0;
 561         int cpu;
 562
 563         cpu_events = alloc_percpu(typeof(*cpu_events));
 564         if (!cpu_events)
 565                 return (void __percpu __force *)ERR_PTR(-ENOMEM);
 566
 567         get_online_cpus();
 568         for_each_online_cpu(cpu) {
 569                 bp = perf_event_create_kernel_counter(attr, cpu, NULL,
 570                                                       triggered, context);
 571                 if (IS_ERR(bp)) {
 572                         err = PTR_ERR(bp);
 573                         break;
 574                 }
 575
 576                 per_cpu(*cpu_events, cpu) = bp;
 577         }
 578         put_online_cpus();
 579
 580         if (likely(!err))
 581                 return cpu_events;
 582
 583         unregister_wide_hw_breakpoint(cpu_events);
 584         return (void __percpu __force *)ERR_PTR(err);
 585 }
 586 EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
 587
 588 /**
 589  * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
 590  * @cpu_events: the per cpu set of events to unregister
 591  */
 592 void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
 593 {
 594         int cpu;
 595
 596         for_each_possible_cpu(cpu)
 597                 unregister_hw_breakpoint(per_cpu(*cpu_events, cpu));
 598
 599         free_percpu(cpu_events);
 600 }
 601 EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
 602
 603 static struct notifier_block hw_breakpoint_exceptions_nb = {
 604         .notifier_call = hw_breakpoint_exceptions_notify,
 605         /* we need to be notified first */
 606         .priority = 0x7fffffff
 607 };
 608
 609 static void bp_perf_event_destroy(struct perf_event *event)
 610 {
 611         release_bp_slot(event);
 612 }
 613
 614 static int hw_breakpoint_event_init(struct perf_event *bp)
 615 {
 616         int err;
 617
 618         if (bp->attr.type != PERF_TYPE_BREAKPOINT)
 619                 return -ENOENT;
 620
 621         /*
 622          * no branch sampling for breakpoint events
 623          */
 624         if (has_branch_stack(bp))
 625                 return -EOPNOTSUPP;
 626
 627         err = register_perf_hw_breakpoint(bp);
 628         if (err)
 629                 return err;
 630
 631         bp->destroy = bp_perf_event_destroy;
 632
 633         return 0;
 634 }
 635
 636 static int hw_breakpoint_add(struct perf_event *bp, int flags)
 637 {
 638         if (!(flags & PERF_EF_START))
 639                 bp->hw.state = PERF_HES_STOPPED;
 640
 641         if (is_sampling_event(bp)) {
 642                 bp->hw.last_period = bp->hw.sample_period;
 643                 perf_swevent_set_period(bp);
 644         }
 645
 646         return arch_install_hw_breakpoint(bp);
 647 }
 648
 649 static void hw_breakpoint_del(struct perf_event *bp, int flags)
 650 {
 651         arch_uninstall_hw_breakpoint(bp);
 652 }
 653
 654 static void hw_breakpoint_start(struct perf_event *bp, int flags)
 655 {
 656         bp->hw.state = 0;
 657 }
 658
 659 static void hw_breakpoint_stop(struct perf_event *bp, int flags)
 660 {
 661         bp->hw.state = PERF_HES_STOPPED;
 662 }
 663
 664 static struct pmu perf_breakpoint = {
 665         .task_ctx_nr    = perf_sw_context, /* could eventually get its own */
 666
 667         .event_init     = hw_breakpoint_event_init,
 668         .add            = hw_breakpoint_add,
 669         .del            = hw_breakpoint_del,
 670         .start          = hw_breakpoint_start,
 671         .stop           = hw_breakpoint_stop,
 672         .read           = hw_breakpoint_pmu_read,
 673 };
 674
 675 int __init init_hw_breakpoint(void)
 676 {
 677         int cpu, err_cpu;
 678         int i;
 679
 680         for (i = 0; i < TYPE_MAX; i++)
 681                 nr_slots[i] = hw_breakpoint_slots(i);
 682
 683         for_each_possible_cpu(cpu) {
 684                 for (i = 0; i < TYPE_MAX; i++) {
 685                         struct bp_cpuinfo *info = get_bp_info(cpu, i);
 686
 687                         info->tsk_pinned = kcalloc(nr_slots[i], sizeof(int),
 688                                                         GFP_KERNEL);
 689                         if (!info->tsk_pinned)
 690                                 goto err_alloc;
 691                 }
 692         }
 693
 694         constraints_initialized = 1;
 695
 696         perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT);
 697
 698         return register_die_notifier(&hw_breakpoint_exceptions_nb);
 699
 700  err_alloc:
 701         for_each_possible_cpu(err_cpu) {
 702                 for (i = 0; i < TYPE_MAX; i++)
 703                         kfree(get_bp_info(err_cpu, i)->tsk_pinned);
 704                 if (err_cpu == cpu)
 705                         break;
 706         }
 707
 708         return -ENOMEM;
 709 }
 710
 711