+++ /dev/null
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright (C) 2007 Alan Stern
- * Copyright (C) IBM Corporation, 2009
- * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
- *
- * Thanks to Ingo Molnar for his many suggestions.
- *
- * Authors: Alan Stern <stern@rowland.harvard.edu>
- * K.Prasad <prasad@linux.vnet.ibm.com>
- * Frederic Weisbecker <fweisbec@gmail.com>
- */
-
-/*
- * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
- * using the CPU's debug registers.
- * This file contains the arch-independent routines.
- */
-
-#include <linux/irqflags.h>
-#include <linux/kallsyms.h>
-#include <linux/notifier.h>
-#include <linux/kprobes.h>
-#include <linux/kdebug.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/percpu.h>
-#include <linux/sched.h>
-#include <linux/init.h>
-#include <linux/slab.h>
-#include <linux/list.h>
-#include <linux/cpu.h>
-#include <linux/smp.h>
-
-#include <linux/hw_breakpoint.h>
-
-
-/*
- * Constraints data
- */
-
-/* Number of pinned cpu breakpoints in a cpu */
-static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]);
-
-/* Number of pinned task breakpoints in a cpu */
-static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]);
-
-/* Number of non-pinned cpu/task breakpoints in a cpu */
-static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]);
-
-static int nr_slots[TYPE_MAX];
-
-/* Keep track of the breakpoints attached to tasks */
-static LIST_HEAD(bp_task_head);
-
-static int constraints_initialized;
-
-/* Gather the number of total pinned and un-pinned bp in a cpuset */
-struct bp_busy_slots {
- unsigned int pinned;
- unsigned int flexible;
-};
-
-/* Serialize accesses to the above constraints */
-static DEFINE_MUTEX(nr_bp_mutex);
-
-__weak int hw_breakpoint_weight(struct perf_event *bp)
-{
- return 1;
-}
-
-static inline enum bp_type_idx find_slot_idx(struct perf_event *bp)
-{
- if (bp->attr.bp_type & HW_BREAKPOINT_RW)
- return TYPE_DATA;
-
- return TYPE_INST;
-}
-
-/*
- * Report the maximum number of pinned breakpoints a task
- * have in this cpu
- */
-static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
-{
- int i;
- unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
-
- for (i = nr_slots[type] - 1; i >= 0; i--) {
- if (tsk_pinned[i] > 0)
- return i + 1;
- }
-
- return 0;
-}
-
-/*
- * Count the number of breakpoints of the same type and same task.
- * The given event must be not on the list.
- */
-static int task_bp_pinned(struct perf_event *bp, enum bp_type_idx type)
-{
- struct task_struct *tsk = bp->hw.bp_target;
- struct perf_event *iter;
- int count = 0;
-
- list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
- if (iter->hw.bp_target == tsk && find_slot_idx(iter) == type)
- count += hw_breakpoint_weight(iter);
- }
-
- return count;
-}
-
-/*
- * Report the number of pinned/un-pinned breakpoints we have in
- * a given cpu (cpu > -1) or in all of them (cpu = -1).
- */
-static void
-fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
- enum bp_type_idx type)
-{
- int cpu = bp->cpu;
- struct task_struct *tsk = bp->hw.bp_target;
-
- if (cpu >= 0) {
- slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu);
- if (!tsk)
- slots->pinned += max_task_bp_pinned(cpu, type);
- else
- slots->pinned += task_bp_pinned(bp, type);
- slots->flexible = per_cpu(nr_bp_flexible[type], cpu);
-
- return;
- }
-
- for_each_online_cpu(cpu) {
- unsigned int nr;
-
- nr = per_cpu(nr_cpu_bp_pinned[type], cpu);
- if (!tsk)
- nr += max_task_bp_pinned(cpu, type);
- else
- nr += task_bp_pinned(bp, type);
-
- if (nr > slots->pinned)
- slots->pinned = nr;
-
- nr = per_cpu(nr_bp_flexible[type], cpu);
-
- if (nr > slots->flexible)
- slots->flexible = nr;
- }
-}
-
-/*
- * For now, continue to consider flexible as pinned, until we can
- * ensure no flexible event can ever be scheduled before a pinned event
- * in a same cpu.
- */
-static void
-fetch_this_slot(struct bp_busy_slots *slots, int weight)
-{
- slots->pinned += weight;
-}
-
-/*
- * Add a pinned breakpoint for the given task in our constraint table
- */
-static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
- enum bp_type_idx type, int weight)
-{
- unsigned int *tsk_pinned;
- int old_count = 0;
- int old_idx = 0;
- int idx = 0;
-
- old_count = task_bp_pinned(bp, type);
- old_idx = old_count - 1;
- idx = old_idx + weight;
-
- /* tsk_pinned[n] is the number of tasks having n breakpoints */
- tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
- if (enable) {
- tsk_pinned[idx]++;
- if (old_count > 0)
- tsk_pinned[old_idx]--;
- } else {
- tsk_pinned[idx]--;
- if (old_count > 0)
- tsk_pinned[old_idx]++;
- }
-}
-
-/*
- * Add/remove the given breakpoint in our constraint table
- */
-static void
-toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
- int weight)
-{
- int cpu = bp->cpu;
- struct task_struct *tsk = bp->hw.bp_target;
-
- /* Pinned counter cpu profiling */
- if (!tsk) {
-
- if (enable)
- per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
- else
- per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight;
- return;
- }
-
- /* Pinned counter task profiling */
-
- if (!enable)
- list_del(&bp->hw.bp_list);
-
- if (cpu >= 0) {
- toggle_bp_task_slot(bp, cpu, enable, type, weight);
- } else {
- for_each_online_cpu(cpu)
- toggle_bp_task_slot(bp, cpu, enable, type, weight);
- }
-
- if (enable)
- list_add_tail(&bp->hw.bp_list, &bp_task_head);
-}
-
-/*
- * Function to perform processor-specific cleanup during unregistration
- */
-__weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
-{
- /*
- * A weak stub function here for those archs that don't define
- * it inside arch/.../kernel/hw_breakpoint.c
- */
-}
-
-/*
- * Contraints to check before allowing this new breakpoint counter:
- *
- * == Non-pinned counter == (Considered as pinned for now)
- *
- * - If attached to a single cpu, check:
- *
- * (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu)
- * + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM
- *
- * -> If there are already non-pinned counters in this cpu, it means
- * there is already a free slot for them.
- * Otherwise, we check that the maximum number of per task
- * breakpoints (for this cpu) plus the number of per cpu breakpoint
- * (for this cpu) doesn't cover every registers.
- *
- * - If attached to every cpus, check:
- *
- * (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *))
- * + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM
- *
- * -> This is roughly the same, except we check the number of per cpu
- * bp for every cpu and we keep the max one. Same for the per tasks
- * breakpoints.
- *
- *
- * == Pinned counter ==
- *
- * - If attached to a single cpu, check:
- *
- * ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu)
- * + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM
- *
- * -> Same checks as before. But now the nr_bp_flexible, if any, must keep
- * one register at least (or they will never be fed).
- *
- * - If attached to every cpus, check:
- *
- * ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
- * + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM
- */
-static int __reserve_bp_slot(struct perf_event *bp)
-{
- struct bp_busy_slots slots = {0};
- enum bp_type_idx type;
- int weight;
-
- /* We couldn't initialize breakpoint constraints on boot */
- if (!constraints_initialized)
- return -ENOMEM;
-
- /* Basic checks */
- if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY ||
- bp->attr.bp_type == HW_BREAKPOINT_INVALID)
- return -EINVAL;
-
- type = find_slot_idx(bp);
- weight = hw_breakpoint_weight(bp);
-
- fetch_bp_busy_slots(&slots, bp, type);
- /*
- * Simulate the addition of this breakpoint to the constraints
- * and see the result.
- */
- fetch_this_slot(&slots, weight);
-
- /* Flexible counters need to keep at least one slot */
- if (slots.pinned + (!!slots.flexible) > nr_slots[type])
- return -ENOSPC;
-
- toggle_bp_slot(bp, true, type, weight);
-
- return 0;
-}
-
-int reserve_bp_slot(struct perf_event *bp)
-{
- int ret;
-
- mutex_lock(&nr_bp_mutex);
-
- ret = __reserve_bp_slot(bp);
-
- mutex_unlock(&nr_bp_mutex);
-
- return ret;
-}
-
-static void __release_bp_slot(struct perf_event *bp)
-{
- enum bp_type_idx type;
- int weight;
-
- type = find_slot_idx(bp);
- weight = hw_breakpoint_weight(bp);
- toggle_bp_slot(bp, false, type, weight);
-}
-
-void release_bp_slot(struct perf_event *bp)
-{
- mutex_lock(&nr_bp_mutex);
-
- arch_unregister_hw_breakpoint(bp);
- __release_bp_slot(bp);
-
- mutex_unlock(&nr_bp_mutex);
-}
-
-/*
- * Allow the kernel debugger to reserve breakpoint slots without
- * taking a lock using the dbg_* variant of for the reserve and
- * release breakpoint slots.
- */
-int dbg_reserve_bp_slot(struct perf_event *bp)
-{
- if (mutex_is_locked(&nr_bp_mutex))
- return -1;
-
- return __reserve_bp_slot(bp);
-}
-
-int dbg_release_bp_slot(struct perf_event *bp)
-{
- if (mutex_is_locked(&nr_bp_mutex))
- return -1;
-
- __release_bp_slot(bp);
-
- return 0;
-}
-
-static int validate_hw_breakpoint(struct perf_event *bp)
-{
- int ret;
-
- ret = arch_validate_hwbkpt_settings(bp);
- if (ret)
- return ret;
-
- if (arch_check_bp_in_kernelspace(bp)) {
- if (bp->attr.exclude_kernel)
- return -EINVAL;
- /*
- * Don't let unprivileged users set a breakpoint in the trap
- * path to avoid trap recursion attacks.
- */
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- }
-
- return 0;
-}
-
-int register_perf_hw_breakpoint(struct perf_event *bp)
-{
- int ret;
-
- ret = reserve_bp_slot(bp);
- if (ret)
- return ret;
-
- ret = validate_hw_breakpoint(bp);
-
- /* if arch_validate_hwbkpt_settings() fails then release bp slot */
- if (ret)
- release_bp_slot(bp);
-
- return ret;
-}
-
-/**
- * register_user_hw_breakpoint - register a hardware breakpoint for user space
- * @attr: breakpoint attributes
- * @triggered: callback to trigger when we hit the breakpoint
- * @tsk: pointer to 'task_struct' of the process to which the address belongs
- */
-struct perf_event *
-register_user_hw_breakpoint(struct perf_event_attr *attr,
- perf_overflow_handler_t triggered,
- struct task_struct *tsk)
-{
- return perf_event_create_kernel_counter(attr, -1, tsk, triggered);
-}
-EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
-
-/**
- * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
- * @bp: the breakpoint structure to modify
- * @attr: new breakpoint attributes
- * @triggered: callback to trigger when we hit the breakpoint
- * @tsk: pointer to 'task_struct' of the process to which the address belongs
- */
-int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
-{
- u64 old_addr = bp->attr.bp_addr;
- u64 old_len = bp->attr.bp_len;
- int old_type = bp->attr.bp_type;
- int err = 0;
-
- perf_event_disable(bp);
-
- bp->attr.bp_addr = attr->bp_addr;
- bp->attr.bp_type = attr->bp_type;
- bp->attr.bp_len = attr->bp_len;
-
- if (attr->disabled)
- goto end;
-
- err = validate_hw_breakpoint(bp);
- if (!err)
- perf_event_enable(bp);
-
- if (err) {
- bp->attr.bp_addr = old_addr;
- bp->attr.bp_type = old_type;
- bp->attr.bp_len = old_len;
- if (!bp->attr.disabled)
- perf_event_enable(bp);
-
- return err;
- }
-
-end:
- bp->attr.disabled = attr->disabled;
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
-
-/**
- * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
- * @bp: the breakpoint structure to unregister
- */
-void unregister_hw_breakpoint(struct perf_event *bp)
-{
- if (!bp)
- return;
- perf_event_release_kernel(bp);
-}
-EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
-
-/**
- * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
- * @attr: breakpoint attributes
- * @triggered: callback to trigger when we hit the breakpoint
- *
- * @return a set of per_cpu pointers to perf events
- */
-struct perf_event * __percpu *
-register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_overflow_handler_t triggered)
-{
- struct perf_event * __percpu *cpu_events, **pevent, *bp;
- long err;
- int cpu;
-
- cpu_events = alloc_percpu(typeof(*cpu_events));
- if (!cpu_events)
- return (void __percpu __force *)ERR_PTR(-ENOMEM);
-
- get_online_cpus();
- for_each_online_cpu(cpu) {
- pevent = per_cpu_ptr(cpu_events, cpu);
- bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered);
-
- *pevent = bp;
-
- if (IS_ERR(bp)) {
- err = PTR_ERR(bp);
- goto fail;
- }
- }
- put_online_cpus();
-
- return cpu_events;
-
-fail:
- for_each_online_cpu(cpu) {
- pevent = per_cpu_ptr(cpu_events, cpu);
- if (IS_ERR(*pevent))
- break;
- unregister_hw_breakpoint(*pevent);
- }
- put_online_cpus();
-
- free_percpu(cpu_events);
- return (void __percpu __force *)ERR_PTR(err);
-}
-EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
-
-/**
- * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
- * @cpu_events: the per cpu set of events to unregister
- */
-void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
-{
- int cpu;
- struct perf_event **pevent;
-
- for_each_possible_cpu(cpu) {
- pevent = per_cpu_ptr(cpu_events, cpu);
- unregister_hw_breakpoint(*pevent);
- }
- free_percpu(cpu_events);
-}
-EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
-
-static struct notifier_block hw_breakpoint_exceptions_nb = {
- .notifier_call = hw_breakpoint_exceptions_notify,
- /* we need to be notified first */
- .priority = 0x7fffffff
-};
-
-static void bp_perf_event_destroy(struct perf_event *event)
-{
- release_bp_slot(event);
-}
-
-static int hw_breakpoint_event_init(struct perf_event *bp)
-{
- int err;
-
- if (bp->attr.type != PERF_TYPE_BREAKPOINT)
- return -ENOENT;
-
- err = register_perf_hw_breakpoint(bp);
- if (err)
- return err;
-
- bp->destroy = bp_perf_event_destroy;
-
- return 0;
-}
-
-static int hw_breakpoint_add(struct perf_event *bp, int flags)
-{
- if (!(flags & PERF_EF_START))
- bp->hw.state = PERF_HES_STOPPED;
-
- return arch_install_hw_breakpoint(bp);
-}
-
-static void hw_breakpoint_del(struct perf_event *bp, int flags)
-{
- arch_uninstall_hw_breakpoint(bp);
-}
-
-static void hw_breakpoint_start(struct perf_event *bp, int flags)
-{
- bp->hw.state = 0;
-}
-
-static void hw_breakpoint_stop(struct perf_event *bp, int flags)
-{
- bp->hw.state = PERF_HES_STOPPED;
-}
-
-static struct pmu perf_breakpoint = {
- .task_ctx_nr = perf_sw_context, /* could eventually get its own */
-
- .event_init = hw_breakpoint_event_init,
- .add = hw_breakpoint_add,
- .del = hw_breakpoint_del,
- .start = hw_breakpoint_start,
- .stop = hw_breakpoint_stop,
- .read = hw_breakpoint_pmu_read,
-};
-
-int __init init_hw_breakpoint(void)
-{
- unsigned int **task_bp_pinned;
- int cpu, err_cpu;
- int i;
-
- for (i = 0; i < TYPE_MAX; i++)
- nr_slots[i] = hw_breakpoint_slots(i);
-
- for_each_possible_cpu(cpu) {
- for (i = 0; i < TYPE_MAX; i++) {
- task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu);
- *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i],
- GFP_KERNEL);
- if (!*task_bp_pinned)
- goto err_alloc;
- }
- }
-
- constraints_initialized = 1;
-
- perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT);
-
- return register_die_notifier(&hw_breakpoint_exceptions_nb);
-
- err_alloc:
- for_each_possible_cpu(err_cpu) {
- if (err_cpu == cpu)
- break;
- for (i = 0; i < TYPE_MAX; i++)
- kfree(per_cpu(nr_task_bp_pinned[i], cpu));
- }
-
- return -ENOMEM;
-}
-
-
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