LCOV - code coverage report
Current view: top level - kernel/events - hw_breakpoint.c (source / functions) Hit Total Coverage
Test: landlock.info Lines: 17 254 6.7 %
Date: 2021-04-22 12:43:58 Functions: 2 32 6.2 %

          Line data    Source code
       1             : // SPDX-License-Identifier: GPL-2.0+
       2             : /*
       3             :  * Copyright (C) 2007 Alan Stern
       4             :  * Copyright (C) IBM Corporation, 2009
       5             :  * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
       6             :  *
       7             :  * Thanks to Ingo Molnar for his many suggestions.
       8             :  *
       9             :  * Authors: Alan Stern <stern@rowland.harvard.edu>
      10             :  *          K.Prasad <prasad@linux.vnet.ibm.com>
      11             :  *          Frederic Weisbecker <fweisbec@gmail.com>
      12             :  */
      13             : 
      14             : /*
      15             :  * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
      16             :  * using the CPU's debug registers.
      17             :  * This file contains the arch-independent routines.
      18             :  */
      19             : 
      20             : #include <linux/irqflags.h>
      21             : #include <linux/kallsyms.h>
      22             : #include <linux/notifier.h>
      23             : #include <linux/kprobes.h>
      24             : #include <linux/kdebug.h>
      25             : #include <linux/kernel.h>
      26             : #include <linux/module.h>
      27             : #include <linux/percpu.h>
      28             : #include <linux/sched.h>
      29             : #include <linux/init.h>
      30             : #include <linux/slab.h>
      31             : #include <linux/list.h>
      32             : #include <linux/cpu.h>
      33             : #include <linux/smp.h>
      34             : #include <linux/bug.h>
      35             : 
      36             : #include <linux/hw_breakpoint.h>
      37             : /*
      38             :  * Constraints data
      39             :  */
      40             : struct bp_cpuinfo {
      41             :         /* Number of pinned cpu breakpoints in a cpu */
      42             :         unsigned int    cpu_pinned;
      43             :         /* tsk_pinned[n] is the number of tasks having n+1 breakpoints */
      44             :         unsigned int    *tsk_pinned;
      45             :         /* Number of non-pinned cpu/task breakpoints in a cpu */
      46             :         unsigned int    flexible; /* XXX: placeholder, see fetch_this_slot() */
      47             : };
      48             : 
      49             : static DEFINE_PER_CPU(struct bp_cpuinfo, bp_cpuinfo[TYPE_MAX]);
      50             : static int nr_slots[TYPE_MAX];
      51             : 
      52           4 : static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type)
      53             : {
      54           4 :         return per_cpu_ptr(bp_cpuinfo + type, cpu);
      55             : }
      56             : 
      57             : /* Keep track of the breakpoints attached to tasks */
      58             : static LIST_HEAD(bp_task_head);
      59             : 
      60             : static int constraints_initialized;
      61             : 
      62             : /* Gather the number of total pinned and un-pinned bp in a cpuset */
      63             : struct bp_busy_slots {
      64             :         unsigned int pinned;
      65             :         unsigned int flexible;
      66             : };
      67             : 
      68             : /* Serialize accesses to the above constraints */
      69             : static DEFINE_MUTEX(nr_bp_mutex);
      70             : 
      71           0 : __weak int hw_breakpoint_weight(struct perf_event *bp)
      72             : {
      73           0 :         return 1;
      74             : }
      75             : 
      76           0 : static inline enum bp_type_idx find_slot_idx(u64 bp_type)
      77             : {
      78           0 :         if (bp_type & HW_BREAKPOINT_RW)
      79             :                 return TYPE_DATA;
      80             : 
      81             :         return TYPE_INST;
      82             : }
      83             : 
      84             : /*
      85             :  * Report the maximum number of pinned breakpoints a task
      86             :  * have in this cpu
      87             :  */
      88           0 : static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
      89             : {
      90           0 :         unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned;
      91           0 :         int i;
      92             : 
      93           0 :         for (i = nr_slots[type] - 1; i >= 0; i--) {
      94           0 :                 if (tsk_pinned[i] > 0)
      95           0 :                         return i + 1;
      96             :         }
      97             : 
      98             :         return 0;
      99             : }
     100             : 
     101             : /*
     102             :  * Count the number of breakpoints of the same type and same task.
     103             :  * The given event must be not on the list.
     104             :  */
     105           0 : static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type)
     106             : {
     107           0 :         struct task_struct *tsk = bp->hw.target;
     108           0 :         struct perf_event *iter;
     109           0 :         int count = 0;
     110             : 
     111           0 :         list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
     112           0 :                 if (iter->hw.target == tsk &&
     113           0 :                     find_slot_idx(iter->attr.bp_type) == type &&
     114           0 :                     (iter->cpu < 0 || cpu == iter->cpu))
     115           0 :                         count += hw_breakpoint_weight(iter);
     116             :         }
     117             : 
     118           0 :         return count;
     119             : }
     120             : 
     121           0 : static const struct cpumask *cpumask_of_bp(struct perf_event *bp)
     122             : {
     123           0 :         if (bp->cpu >= 0)
     124           0 :                 return cpumask_of(bp->cpu);
     125             :         return cpu_possible_mask;
     126             : }
     127             : 
     128             : /*
     129             :  * Report the number of pinned/un-pinned breakpoints we have in
     130             :  * a given cpu (cpu > -1) or in all of them (cpu = -1).
     131             :  */
     132             : static void
     133           0 : fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
     134             :                     enum bp_type_idx type)
     135             : {
     136           0 :         const struct cpumask *cpumask = cpumask_of_bp(bp);
     137           0 :         int cpu;
     138             : 
     139           0 :         for_each_cpu(cpu, cpumask) {
     140           0 :                 struct bp_cpuinfo *info = get_bp_info(cpu, type);
     141           0 :                 int nr;
     142             : 
     143           0 :                 nr = info->cpu_pinned;
     144           0 :                 if (!bp->hw.target)
     145           0 :                         nr += max_task_bp_pinned(cpu, type);
     146             :                 else
     147           0 :                         nr += task_bp_pinned(cpu, bp, type);
     148             : 
     149           0 :                 if (nr > slots->pinned)
     150           0 :                         slots->pinned = nr;
     151             : 
     152           0 :                 nr = info->flexible;
     153           0 :                 if (nr > slots->flexible)
     154           0 :                         slots->flexible = nr;
     155             :         }
     156           0 : }
     157             : 
     158             : /*
     159             :  * For now, continue to consider flexible as pinned, until we can
     160             :  * ensure no flexible event can ever be scheduled before a pinned event
     161             :  * in a same cpu.
     162             :  */
     163             : static void
     164           0 : fetch_this_slot(struct bp_busy_slots *slots, int weight)
     165             : {
     166           0 :         slots->pinned += weight;
     167             : }
     168             : 
     169             : /*
     170             :  * Add a pinned breakpoint for the given task in our constraint table
     171             :  */
     172           0 : static void toggle_bp_task_slot(struct perf_event *bp, int cpu,
     173             :                                 enum bp_type_idx type, int weight)
     174             : {
     175           0 :         unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned;
     176           0 :         int old_idx, new_idx;
     177             : 
     178           0 :         old_idx = task_bp_pinned(cpu, bp, type) - 1;
     179           0 :         new_idx = old_idx + weight;
     180             : 
     181           0 :         if (old_idx >= 0)
     182           0 :                 tsk_pinned[old_idx]--;
     183           0 :         if (new_idx >= 0)
     184           0 :                 tsk_pinned[new_idx]++;
     185           0 : }
     186             : 
     187             : /*
     188             :  * Add/remove the given breakpoint in our constraint table
     189             :  */
     190             : static void
     191           0 : toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
     192             :                int weight)
     193             : {
     194           0 :         const struct cpumask *cpumask = cpumask_of_bp(bp);
     195           0 :         int cpu;
     196             : 
     197           0 :         if (!enable)
     198           0 :                 weight = -weight;
     199             : 
     200             :         /* Pinned counter cpu profiling */
     201           0 :         if (!bp->hw.target) {
     202           0 :                 get_bp_info(bp->cpu, type)->cpu_pinned += weight;
     203           0 :                 return;
     204             :         }
     205             : 
     206             :         /* Pinned counter task profiling */
     207           0 :         for_each_cpu(cpu, cpumask)
     208           0 :                 toggle_bp_task_slot(bp, cpu, type, weight);
     209             : 
     210           0 :         if (enable)
     211           0 :                 list_add_tail(&bp->hw.bp_list, &bp_task_head);
     212             :         else
     213           0 :                 list_del(&bp->hw.bp_list);
     214             : }
     215             : 
     216           0 : __weak int arch_reserve_bp_slot(struct perf_event *bp)
     217             : {
     218           0 :         return 0;
     219             : }
     220             : 
     221           0 : __weak void arch_release_bp_slot(struct perf_event *bp)
     222             : {
     223           0 : }
     224             : 
     225             : /*
     226             :  * Function to perform processor-specific cleanup during unregistration
     227             :  */
     228           0 : __weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
     229             : {
     230             :         /*
     231             :          * A weak stub function here for those archs that don't define
     232             :          * it inside arch/.../kernel/hw_breakpoint.c
     233             :          */
     234           0 : }
     235             : 
     236             : /*
     237             :  * Constraints to check before allowing this new breakpoint counter:
     238             :  *
     239             :  *  == Non-pinned counter == (Considered as pinned for now)
     240             :  *
     241             :  *   - If attached to a single cpu, check:
     242             :  *
     243             :  *       (per_cpu(info->flexible, cpu) || (per_cpu(info->cpu_pinned, cpu)
     244             :  *           + max(per_cpu(info->tsk_pinned, cpu)))) < HBP_NUM
     245             :  *
     246             :  *       -> If there are already non-pinned counters in this cpu, it means
     247             :  *          there is already a free slot for them.
     248             :  *          Otherwise, we check that the maximum number of per task
     249             :  *          breakpoints (for this cpu) plus the number of per cpu breakpoint
     250             :  *          (for this cpu) doesn't cover every registers.
     251             :  *
     252             :  *   - If attached to every cpus, check:
     253             :  *
     254             :  *       (per_cpu(info->flexible, *) || (max(per_cpu(info->cpu_pinned, *))
     255             :  *           + max(per_cpu(info->tsk_pinned, *)))) < HBP_NUM
     256             :  *
     257             :  *       -> This is roughly the same, except we check the number of per cpu
     258             :  *          bp for every cpu and we keep the max one. Same for the per tasks
     259             :  *          breakpoints.
     260             :  *
     261             :  *
     262             :  * == Pinned counter ==
     263             :  *
     264             :  *   - If attached to a single cpu, check:
     265             :  *
     266             :  *       ((per_cpu(info->flexible, cpu) > 1) + per_cpu(info->cpu_pinned, cpu)
     267             :  *            + max(per_cpu(info->tsk_pinned, cpu))) < HBP_NUM
     268             :  *
     269             :  *       -> Same checks as before. But now the info->flexible, if any, must keep
     270             :  *          one register at least (or they will never be fed).
     271             :  *
     272             :  *   - If attached to every cpus, check:
     273             :  *
     274             :  *       ((per_cpu(info->flexible, *) > 1) + max(per_cpu(info->cpu_pinned, *))
     275             :  *            + max(per_cpu(info->tsk_pinned, *))) < HBP_NUM
     276             :  */
     277           0 : static int __reserve_bp_slot(struct perf_event *bp, u64 bp_type)
     278             : {
     279           0 :         struct bp_busy_slots slots = {0};
     280           0 :         enum bp_type_idx type;
     281           0 :         int weight;
     282           0 :         int ret;
     283             : 
     284             :         /* We couldn't initialize breakpoint constraints on boot */
     285           0 :         if (!constraints_initialized)
     286             :                 return -ENOMEM;
     287             : 
     288             :         /* Basic checks */
     289           0 :         if (bp_type == HW_BREAKPOINT_EMPTY ||
     290           0 :             bp_type == HW_BREAKPOINT_INVALID)
     291             :                 return -EINVAL;
     292             : 
     293           0 :         type = find_slot_idx(bp_type);
     294           0 :         weight = hw_breakpoint_weight(bp);
     295             : 
     296           0 :         fetch_bp_busy_slots(&slots, bp, type);
     297             :         /*
     298             :          * Simulate the addition of this breakpoint to the constraints
     299             :          * and see the result.
     300             :          */
     301           0 :         fetch_this_slot(&slots, weight);
     302             : 
     303             :         /* Flexible counters need to keep at least one slot */
     304           0 :         if (slots.pinned + (!!slots.flexible) > nr_slots[type])
     305             :                 return -ENOSPC;
     306             : 
     307           0 :         ret = arch_reserve_bp_slot(bp);
     308           0 :         if (ret)
     309             :                 return ret;
     310             : 
     311           0 :         toggle_bp_slot(bp, true, type, weight);
     312             : 
     313           0 :         return 0;
     314             : }
     315             : 
     316           0 : int reserve_bp_slot(struct perf_event *bp)
     317             : {
     318           0 :         int ret;
     319             : 
     320           0 :         mutex_lock(&nr_bp_mutex);
     321             : 
     322           0 :         ret = __reserve_bp_slot(bp, bp->attr.bp_type);
     323             : 
     324           0 :         mutex_unlock(&nr_bp_mutex);
     325             : 
     326           0 :         return ret;
     327             : }
     328             : 
     329           0 : static void __release_bp_slot(struct perf_event *bp, u64 bp_type)
     330             : {
     331           0 :         enum bp_type_idx type;
     332           0 :         int weight;
     333             : 
     334           0 :         arch_release_bp_slot(bp);
     335             : 
     336           0 :         type = find_slot_idx(bp_type);
     337           0 :         weight = hw_breakpoint_weight(bp);
     338           0 :         toggle_bp_slot(bp, false, type, weight);
     339           0 : }
     340             : 
     341           0 : void release_bp_slot(struct perf_event *bp)
     342             : {
     343           0 :         mutex_lock(&nr_bp_mutex);
     344             : 
     345           0 :         arch_unregister_hw_breakpoint(bp);
     346           0 :         __release_bp_slot(bp, bp->attr.bp_type);
     347             : 
     348           0 :         mutex_unlock(&nr_bp_mutex);
     349           0 : }
     350             : 
     351           0 : static int __modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type)
     352             : {
     353           0 :         int err;
     354             : 
     355           0 :         __release_bp_slot(bp, old_type);
     356             : 
     357           0 :         err = __reserve_bp_slot(bp, new_type);
     358           0 :         if (err) {
     359             :                 /*
     360             :                  * Reserve the old_type slot back in case
     361             :                  * there's no space for the new type.
     362             :                  *
     363             :                  * This must succeed, because we just released
     364             :                  * the old_type slot in the __release_bp_slot
     365             :                  * call above. If not, something is broken.
     366             :                  */
     367           0 :                 WARN_ON(__reserve_bp_slot(bp, old_type));
     368             :         }
     369             : 
     370           0 :         return err;
     371             : }
     372             : 
     373           0 : static int modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type)
     374             : {
     375           0 :         int ret;
     376             : 
     377           0 :         mutex_lock(&nr_bp_mutex);
     378           0 :         ret = __modify_bp_slot(bp, old_type, new_type);
     379           0 :         mutex_unlock(&nr_bp_mutex);
     380           0 :         return ret;
     381             : }
     382             : 
     383             : /*
     384             :  * Allow the kernel debugger to reserve breakpoint slots without
     385             :  * taking a lock using the dbg_* variant of for the reserve and
     386             :  * release breakpoint slots.
     387             :  */
     388           0 : int dbg_reserve_bp_slot(struct perf_event *bp)
     389             : {
     390           0 :         if (mutex_is_locked(&nr_bp_mutex))
     391             :                 return -1;
     392             : 
     393           0 :         return __reserve_bp_slot(bp, bp->attr.bp_type);
     394             : }
     395             : 
     396           0 : int dbg_release_bp_slot(struct perf_event *bp)
     397             : {
     398           0 :         if (mutex_is_locked(&nr_bp_mutex))
     399             :                 return -1;
     400             : 
     401           0 :         __release_bp_slot(bp, bp->attr.bp_type);
     402             : 
     403           0 :         return 0;
     404             : }
     405             : 
     406           0 : static int hw_breakpoint_parse(struct perf_event *bp,
     407             :                                const struct perf_event_attr *attr,
     408             :                                struct arch_hw_breakpoint *hw)
     409             : {
     410           0 :         int err;
     411             : 
     412           0 :         err = hw_breakpoint_arch_parse(bp, attr, hw);
     413           0 :         if (err)
     414             :                 return err;
     415             : 
     416           0 :         if (arch_check_bp_in_kernelspace(hw)) {
     417           0 :                 if (attr->exclude_kernel)
     418             :                         return -EINVAL;
     419             :                 /*
     420             :                  * Don't let unprivileged users set a breakpoint in the trap
     421             :                  * path to avoid trap recursion attacks.
     422             :                  */
     423           0 :                 if (!capable(CAP_SYS_ADMIN))
     424           0 :                         return -EPERM;
     425             :         }
     426             : 
     427             :         return 0;
     428             : }
     429             : 
     430           0 : int register_perf_hw_breakpoint(struct perf_event *bp)
     431             : {
     432           0 :         struct arch_hw_breakpoint hw = { };
     433           0 :         int err;
     434             : 
     435           0 :         err = reserve_bp_slot(bp);
     436           0 :         if (err)
     437             :                 return err;
     438             : 
     439           0 :         err = hw_breakpoint_parse(bp, &bp->attr, &hw);
     440           0 :         if (err) {
     441           0 :                 release_bp_slot(bp);
     442           0 :                 return err;
     443             :         }
     444             : 
     445           0 :         bp->hw.info = hw;
     446             : 
     447           0 :         return 0;
     448             : }
     449             : 
     450             : /**
     451             :  * register_user_hw_breakpoint - register a hardware breakpoint for user space
     452             :  * @attr: breakpoint attributes
     453             :  * @triggered: callback to trigger when we hit the breakpoint
     454             :  * @tsk: pointer to 'task_struct' of the process to which the address belongs
     455             :  */
     456             : struct perf_event *
     457           0 : register_user_hw_breakpoint(struct perf_event_attr *attr,
     458             :                             perf_overflow_handler_t triggered,
     459             :                             void *context,
     460             :                             struct task_struct *tsk)
     461             : {
     462           0 :         return perf_event_create_kernel_counter(attr, -1, tsk, triggered,
     463             :                                                 context);
     464             : }
     465             : EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
     466             : 
     467           0 : static void hw_breakpoint_copy_attr(struct perf_event_attr *to,
     468             :                                     struct perf_event_attr *from)
     469             : {
     470           0 :         to->bp_addr = from->bp_addr;
     471           0 :         to->bp_type = from->bp_type;
     472           0 :         to->bp_len  = from->bp_len;
     473           0 :         to->disabled = from->disabled;
     474             : }
     475             : 
     476             : int
     477           0 : modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *attr,
     478             :                                 bool check)
     479             : {
     480           0 :         struct arch_hw_breakpoint hw = { };
     481           0 :         int err;
     482             : 
     483           0 :         err = hw_breakpoint_parse(bp, attr, &hw);
     484           0 :         if (err)
     485             :                 return err;
     486             : 
     487           0 :         if (check) {
     488           0 :                 struct perf_event_attr old_attr;
     489             : 
     490           0 :                 old_attr = bp->attr;
     491           0 :                 hw_breakpoint_copy_attr(&old_attr, attr);
     492           0 :                 if (memcmp(&old_attr, attr, sizeof(*attr)))
     493           0 :                         return -EINVAL;
     494             :         }
     495             : 
     496           0 :         if (bp->attr.bp_type != attr->bp_type) {
     497           0 :                 err = modify_bp_slot(bp, bp->attr.bp_type, attr->bp_type);
     498           0 :                 if (err)
     499             :                         return err;
     500             :         }
     501             : 
     502           0 :         hw_breakpoint_copy_attr(&bp->attr, attr);
     503           0 :         bp->hw.info = hw;
     504             : 
     505           0 :         return 0;
     506             : }
     507             : 
     508             : /**
     509             :  * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
     510             :  * @bp: the breakpoint structure to modify
     511             :  * @attr: new breakpoint attributes
     512             :  */
     513           0 : int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
     514             : {
     515           0 :         int err;
     516             : 
     517             :         /*
     518             :          * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it
     519             :          * will not be possible to raise IPIs that invoke __perf_event_disable.
     520             :          * So call the function directly after making sure we are targeting the
     521             :          * current task.
     522             :          */
     523           0 :         if (irqs_disabled() && bp->ctx && bp->ctx->task == current)
     524           0 :                 perf_event_disable_local(bp);
     525             :         else
     526           0 :                 perf_event_disable(bp);
     527             : 
     528           0 :         err = modify_user_hw_breakpoint_check(bp, attr, false);
     529             : 
     530           0 :         if (!bp->attr.disabled)
     531           0 :                 perf_event_enable(bp);
     532             : 
     533           0 :         return err;
     534             : }
     535             : EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
     536             : 
     537             : /**
     538             :  * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
     539             :  * @bp: the breakpoint structure to unregister
     540             :  */
     541        8148 : void unregister_hw_breakpoint(struct perf_event *bp)
     542             : {
     543        8148 :         if (!bp)
     544             :                 return;
     545           0 :         perf_event_release_kernel(bp);
     546             : }
     547             : EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
     548             : 
     549             : /**
     550             :  * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
     551             :  * @attr: breakpoint attributes
     552             :  * @triggered: callback to trigger when we hit the breakpoint
     553             :  *
     554             :  * @return a set of per_cpu pointers to perf events
     555             :  */
     556             : struct perf_event * __percpu *
     557           0 : register_wide_hw_breakpoint(struct perf_event_attr *attr,
     558             :                             perf_overflow_handler_t triggered,
     559             :                             void *context)
     560             : {
     561           0 :         struct perf_event * __percpu *cpu_events, *bp;
     562           0 :         long err = 0;
     563           0 :         int cpu;
     564             : 
     565           0 :         cpu_events = alloc_percpu(typeof(*cpu_events));
     566           0 :         if (!cpu_events)
     567           0 :                 return (void __percpu __force *)ERR_PTR(-ENOMEM);
     568             : 
     569           0 :         get_online_cpus();
     570           0 :         for_each_online_cpu(cpu) {
     571           0 :                 bp = perf_event_create_kernel_counter(attr, cpu, NULL,
     572             :                                                       triggered, context);
     573           0 :                 if (IS_ERR(bp)) {
     574           0 :                         err = PTR_ERR(bp);
     575           0 :                         break;
     576             :                 }
     577             : 
     578           0 :                 per_cpu(*cpu_events, cpu) = bp;
     579             :         }
     580           0 :         put_online_cpus();
     581             : 
     582           0 :         if (likely(!err))
     583             :                 return cpu_events;
     584             : 
     585           0 :         unregister_wide_hw_breakpoint(cpu_events);
     586           0 :         return (void __percpu __force *)ERR_PTR(err);
     587             : }
     588             : EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
     589             : 
     590             : /**
     591             :  * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
     592             :  * @cpu_events: the per cpu set of events to unregister
     593             :  */
     594           0 : void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
     595             : {
     596           0 :         int cpu;
     597             : 
     598           0 :         for_each_possible_cpu(cpu)
     599           0 :                 unregister_hw_breakpoint(per_cpu(*cpu_events, cpu));
     600             : 
     601           0 :         free_percpu(cpu_events);
     602           0 : }
     603             : EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
     604             : 
     605             : static struct notifier_block hw_breakpoint_exceptions_nb = {
     606             :         .notifier_call = hw_breakpoint_exceptions_notify,
     607             :         /* we need to be notified first */
     608             :         .priority = 0x7fffffff
     609             : };
     610             : 
     611           0 : static void bp_perf_event_destroy(struct perf_event *event)
     612             : {
     613           0 :         release_bp_slot(event);
     614           0 : }
     615             : 
     616           0 : static int hw_breakpoint_event_init(struct perf_event *bp)
     617             : {
     618           0 :         int err;
     619             : 
     620           0 :         if (bp->attr.type != PERF_TYPE_BREAKPOINT)
     621             :                 return -ENOENT;
     622             : 
     623             :         /*
     624             :          * no branch sampling for breakpoint events
     625             :          */
     626           0 :         if (has_branch_stack(bp))
     627             :                 return -EOPNOTSUPP;
     628             : 
     629           0 :         err = register_perf_hw_breakpoint(bp);
     630           0 :         if (err)
     631             :                 return err;
     632             : 
     633           0 :         bp->destroy = bp_perf_event_destroy;
     634             : 
     635           0 :         return 0;
     636             : }
     637             : 
     638           0 : static int hw_breakpoint_add(struct perf_event *bp, int flags)
     639             : {
     640           0 :         if (!(flags & PERF_EF_START))
     641           0 :                 bp->hw.state = PERF_HES_STOPPED;
     642             : 
     643           0 :         if (is_sampling_event(bp)) {
     644           0 :                 bp->hw.last_period = bp->hw.sample_period;
     645           0 :                 perf_swevent_set_period(bp);
     646             :         }
     647             : 
     648           0 :         return arch_install_hw_breakpoint(bp);
     649             : }
     650             : 
     651           0 : static void hw_breakpoint_del(struct perf_event *bp, int flags)
     652             : {
     653           0 :         arch_uninstall_hw_breakpoint(bp);
     654           0 : }
     655             : 
     656           0 : static void hw_breakpoint_start(struct perf_event *bp, int flags)
     657             : {
     658           0 :         bp->hw.state = 0;
     659           0 : }
     660             : 
     661           0 : static void hw_breakpoint_stop(struct perf_event *bp, int flags)
     662             : {
     663           0 :         bp->hw.state = PERF_HES_STOPPED;
     664           0 : }
     665             : 
     666             : static struct pmu perf_breakpoint = {
     667             :         .task_ctx_nr    = perf_sw_context, /* could eventually get its own */
     668             : 
     669             :         .event_init     = hw_breakpoint_event_init,
     670             :         .add            = hw_breakpoint_add,
     671             :         .del            = hw_breakpoint_del,
     672             :         .start          = hw_breakpoint_start,
     673             :         .stop           = hw_breakpoint_stop,
     674             :         .read           = hw_breakpoint_pmu_read,
     675             : };
     676             : 
     677           1 : int __init init_hw_breakpoint(void)
     678             : {
     679           1 :         int cpu, err_cpu;
     680           1 :         int i;
     681             : 
     682           2 :         for (i = 0; i < TYPE_MAX; i++)
     683           1 :                 nr_slots[i] = hw_breakpoint_slots(i);
     684             : 
     685           5 :         for_each_possible_cpu(cpu) {
     686           8 :                 for (i = 0; i < TYPE_MAX; i++) {
     687           4 :                         struct bp_cpuinfo *info = get_bp_info(cpu, i);
     688             : 
     689           4 :                         info->tsk_pinned = kcalloc(nr_slots[i], sizeof(int),
     690             :                                                         GFP_KERNEL);
     691           4 :                         if (!info->tsk_pinned)
     692           0 :                                 goto err_alloc;
     693             :                 }
     694             :         }
     695             : 
     696           1 :         constraints_initialized = 1;
     697             : 
     698           1 :         perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT);
     699             : 
     700           1 :         return register_die_notifier(&hw_breakpoint_exceptions_nb);
     701             : 
     702           0 :  err_alloc:
     703           0 :         for_each_possible_cpu(err_cpu) {
     704           0 :                 for (i = 0; i < TYPE_MAX; i++)
     705           0 :                         kfree(get_bp_info(err_cpu, i)->tsk_pinned);
     706           0 :                 if (err_cpu == cpu)
     707             :                         break;
     708             :         }
     709             : 
     710             :         return -ENOMEM;
     711             : }
     712             : 
     713             : 

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