[net-next-2.6.git] / kernel / hw_breakpoint.c

/*
 * 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/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);

/* Number of pinned task breakpoints in a cpu */
static DEFINE_PER_CPU(unsigned int, task_bp_pinned[HBP_NUM]);

/* Number of non-pinned cpu/task breakpoints in a cpu */
static DEFINE_PER_CPU(unsigned int, nr_bp_flexible);

/* 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);

/*
 * Report the maximum number of pinned breakpoints a task
 * have in this cpu
 */
static unsigned int max_task_bp_pinned(int cpu)
{
	int i;
	unsigned int *tsk_pinned = per_cpu(task_bp_pinned, cpu);

	for (i = HBP_NUM -1; i >= 0; i--) {
		if (tsk_pinned[i] > 0)
			return i + 1;
	}

	return 0;
}

/*
 * 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, int cpu)
{
	if (cpu >= 0) {
		slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu);
		slots->pinned += max_task_bp_pinned(cpu);
		slots->flexible = per_cpu(nr_bp_flexible, cpu);

		return;
	}

	for_each_online_cpu(cpu) {
		unsigned int nr;

		nr = per_cpu(nr_cpu_bp_pinned, cpu);
		nr += max_task_bp_pinned(cpu);

		if (nr > slots->pinned)
			slots->pinned = nr;

		nr = per_cpu(nr_bp_flexible, cpu);

		if (nr > slots->flexible)
			slots->flexible = nr;
	}
}

/*
 * Add a pinned breakpoint for the given task in our constraint table
 */
static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)
{
	int count = 0;
	struct perf_event *bp;
	struct perf_event_context *ctx = tsk->perf_event_ctxp;
	unsigned int *tsk_pinned;
	struct list_head *list;
	unsigned long flags;

	if (WARN_ONCE(!ctx, "No perf context for this task"))
		return;

	list = &ctx->event_list;

	spin_lock_irqsave(&ctx->lock, flags);

	/*
	 * The current breakpoint counter is not included in the list
	 * at the open() callback time
	 */
	list_for_each_entry(bp, list, event_entry) {
		if (bp->attr.type == PERF_TYPE_BREAKPOINT)
			count++;
	}

	spin_unlock_irqrestore(&ctx->lock, flags);

	if (WARN_ONCE(count < 0, "No breakpoint counter found in the counter list"))
		return;

	tsk_pinned = per_cpu(task_bp_pinned, cpu);
	if (enable) {
		tsk_pinned[count]++;
		if (count > 0)
			tsk_pinned[count-1]--;
	} else {
		tsk_pinned[count]--;
		if (count > 0)
			tsk_pinned[count-1]++;
	}
}

/*
 * Add/remove the given breakpoint in our constraint table
 */
static void toggle_bp_slot(struct perf_event *bp, bool enable)
{
	int cpu = bp->cpu;
	struct task_struct *tsk = bp->ctx->task;

	/* Pinned counter task profiling */
	if (tsk) {
		if (cpu >= 0) {
			toggle_bp_task_slot(tsk, cpu, enable);
			return;
		}

		for_each_online_cpu(cpu)
			toggle_bp_task_slot(tsk, cpu, enable);
		return;
	}

	/* Pinned counter cpu profiling */
	if (enable)
		per_cpu(nr_cpu_bp_pinned, bp->cpu)++;
	else
		per_cpu(nr_cpu_bp_pinned, bp->cpu)--;
}

/*
 * 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(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(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(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(task_bp_pinned, *))) < HBP_NUM
 */
int reserve_bp_slot(struct perf_event *bp)
{
	struct bp_busy_slots slots = {0};
	int ret = 0;

	mutex_lock(&nr_bp_mutex);

	fetch_bp_busy_slots(&slots, bp->cpu);

	/* Flexible counters need to keep at least one slot */
	if (slots.pinned + (!!slots.flexible) == HBP_NUM) {
		ret = -ENOSPC;
		goto end;
	}

	toggle_bp_slot(bp, true);

end:
	mutex_unlock(&nr_bp_mutex);

	return ret;
}

void release_bp_slot(struct perf_event *bp)
{
	mutex_lock(&nr_bp_mutex);

	toggle_bp_slot(bp, false);

	mutex_unlock(&nr_bp_mutex);
}


int __register_perf_hw_breakpoint(struct perf_event *bp)
{
	int ret;

	ret = reserve_bp_slot(bp);
	if (ret)
		return ret;

	/*
	 * Ptrace breakpoints can be temporary perf events only
	 * meant to reserve a slot. In this case, it is created disabled and
	 * we don't want to check the params right now (as we put a null addr)
	 * But perf tools create events as disabled and we want to check
	 * the params for them.
	 * This is a quick hack that will be removed soon, once we remove
	 * the tmp breakpoints from ptrace
	 */
	if (!bp->attr.disabled || bp->callback == perf_bp_event)
		ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);

	return ret;
}

int register_perf_hw_breakpoint(struct perf_event *bp)
{
	bp->callback = perf_bp_event;

	return __register_perf_hw_breakpoint(bp);
}

/**
 * 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_callback_t triggered,
			    struct task_struct *tsk)
{
	return perf_event_create_kernel_counter(attr, -1, tsk->pid, 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
 */
struct perf_event *
modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr,
			  perf_callback_t triggered,
			  struct task_struct *tsk)
{
	/*
	 * FIXME: do it without unregistering
	 * - We don't want to lose our slot
	 * - If the new bp is incorrect, don't lose the older one
	 */
	unregister_hw_breakpoint(bp);

	return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
}
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 **
register_wide_hw_breakpoint(struct perf_event_attr *attr,
			    perf_callback_t triggered)
{
	struct perf_event **cpu_events, **pevent, *bp;
	long err;
	int cpu;

	cpu_events = alloc_percpu(typeof(*cpu_events));
	if (!cpu_events)
		return ERR_PTR(-ENOMEM);

	for_each_possible_cpu(cpu) {
		pevent = per_cpu_ptr(cpu_events, cpu);
		bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered);

		*pevent = bp;

		if (IS_ERR(bp)) {
			err = PTR_ERR(bp);
			goto fail;
		}
	}

	return cpu_events;

fail:
	for_each_possible_cpu(cpu) {
		pevent = per_cpu_ptr(cpu_events, cpu);
		if (IS_ERR(*pevent))
			break;
		unregister_hw_breakpoint(*pevent);
	}
	free_percpu(cpu_events);
	/* return the error if any */
	return 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 **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 int __init init_hw_breakpoint(void)
{
	return register_die_notifier(&hw_breakpoint_exceptions_nb);
}
core_initcall(init_hw_breakpoint);


struct pmu perf_ops_bp = {
	.enable		= arch_install_hw_breakpoint,
	.disable	= arch_uninstall_hw_breakpoint,
	.read		= hw_breakpoint_pmu_read,
	.unthrottle	= hw_breakpoint_pmu_unthrottle
};
Commit	Line	Data
62a038d3 P	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
24f1e32c	18	* Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
ba1c813a FW	19	*
ba1c813a FW	20	* Thanks to Ingo Molnar for his many suggestions.
ba6909b7 P	21	*
	22	* Authors: Alan Stern <stern@rowland.harvard.edu>
	23	* K.Prasad <prasad@linux.vnet.ibm.com>
	24	* Frederic Weisbecker <fweisbec@gmail.com>
62a038d3 P	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/smp.h>
	44
24f1e32c FW	45	#include <linux/hw_breakpoint.h>
24f1e32c FW	46
ba1c813a FW	47	/*
	48	* Constraints data
	49	*/
62a038d3	50
ba1c813a FW	51	/* Number of pinned cpu breakpoints in a cpu */
	52	static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned);
	53
	54	/* Number of pinned task breakpoints in a cpu */
	55	static DEFINE_PER_CPU(unsigned int, task_bp_pinned[HBP_NUM]);
	56
	57	/* Number of non-pinned cpu/task breakpoints in a cpu */
	58	static DEFINE_PER_CPU(unsigned int, nr_bp_flexible);
	59
	60	/* Gather the number of total pinned and un-pinned bp in a cpuset */
	61	struct bp_busy_slots {
	62	unsigned int pinned;
	63	unsigned int flexible;
	64	};
	65
	66	/* Serialize accesses to the above constraints */
	67	static DEFINE_MUTEX(nr_bp_mutex);
	68
	69	/*
	70	* Report the maximum number of pinned breakpoints a task
	71	* have in this cpu
	72	*/
	73	static unsigned int max_task_bp_pinned(int cpu)
62a038d3	74	{
ba1c813a FW	75	int i;
ba1c813a FW	76	unsigned int *tsk_pinned = per_cpu(task_bp_pinned, cpu);
62a038d3	77
ba1c813a FW	78	for (i = HBP_NUM -1; i >= 0; i--) {
	79	if (tsk_pinned[i] > 0)
	80	return i + 1;
62a038d3 P	81	}
62a038d3 P	82
24f1e32c	83	return 0;
62a038d3 P	84	}
62a038d3 P	85
ba1c813a FW	86	/*
	87	* Report the number of pinned/un-pinned breakpoints we have in
	88	* a given cpu (cpu > -1) or in all of them (cpu = -1).
	89	*/
	90	static void fetch_bp_busy_slots(struct bp_busy_slots *slots, int cpu)
	91	{
	92	if (cpu >= 0) {
	93	slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu);
	94	slots->pinned += max_task_bp_pinned(cpu);
	95	slots->flexible = per_cpu(nr_bp_flexible, cpu);
	96
	97	return;
	98	}
	99
	100	for_each_online_cpu(cpu) {
	101	unsigned int nr;
	102
	103	nr = per_cpu(nr_cpu_bp_pinned, cpu);
	104	nr += max_task_bp_pinned(cpu);
	105
	106	if (nr > slots->pinned)
	107	slots->pinned = nr;
	108
	109	nr = per_cpu(nr_bp_flexible, cpu);
	110
	111	if (nr > slots->flexible)
	112	slots->flexible = nr;
	113	}
	114	}
	115
	116	/*
	117	* Add a pinned breakpoint for the given task in our constraint table
	118	*/
	119	static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)
	120	{
	121	int count = 0;
	122	struct perf_event *bp;
	123	struct perf_event_context *ctx = tsk->perf_event_ctxp;
11e66357	124	unsigned int *tsk_pinned;
ba1c813a FW	125	struct list_head *list;
	126	unsigned long flags;
	127
	128	if (WARN_ONCE(!ctx, "No perf context for this task"))
	129	return;
	130
	131	list = &ctx->event_list;
	132
	133	spin_lock_irqsave(&ctx->lock, flags);
	134
	135	/*
	136	* The current breakpoint counter is not included in the list
	137	* at the open() callback time
	138	*/
	139	list_for_each_entry(bp, list, event_entry) {
	140	if (bp->attr.type == PERF_TYPE_BREAKPOINT)
	141	count++;
	142	}
	143
	144	spin_unlock_irqrestore(&ctx->lock, flags);
	145
	146	if (WARN_ONCE(count < 0, "No breakpoint counter found in the counter list"))
	147	return;
	148
11e66357	149	tsk_pinned = per_cpu(task_bp_pinned, cpu);
ba1c813a	150	if (enable) {
11e66357	151	tsk_pinned[count]++;
ba1c813a	152	if (count > 0)
11e66357	153	tsk_pinned[count-1]--;
ba1c813a	154	} else {
11e66357	155	tsk_pinned[count]--;
ba1c813a	156	if (count > 0)
11e66357	157	tsk_pinned[count-1]++;
ba1c813a FW	158	}
	159	}
	160
	161	/*
	162	* Add/remove the given breakpoint in our constraint table
	163	*/
	164	static void toggle_bp_slot(struct perf_event *bp, bool enable)
	165	{
	166	int cpu = bp->cpu;
	167	struct task_struct *tsk = bp->ctx->task;
	168
	169	/* Pinned counter task profiling */
	170	if (tsk) {
	171	if (cpu >= 0) {
	172	toggle_bp_task_slot(tsk, cpu, enable);
	173	return;
	174	}
	175
	176	for_each_online_cpu(cpu)
	177	toggle_bp_task_slot(tsk, cpu, enable);
	178	return;
	179	}
	180
	181	/* Pinned counter cpu profiling */
	182	if (enable)
	183	per_cpu(nr_cpu_bp_pinned, bp->cpu)++;
	184	else
	185	per_cpu(nr_cpu_bp_pinned, bp->cpu)--;
	186	}
	187
	188	/*
	189	* Contraints to check before allowing this new breakpoint counter:
	190	*
	191	* == Non-pinned counter == (Considered as pinned for now)
	192	*
	193	* - If attached to a single cpu, check:
	194	*
	195	* (per_cpu(nr_bp_flexible, cpu) \|\| (per_cpu(nr_cpu_bp_pinned, cpu)
	196	* + max(per_cpu(task_bp_pinned, cpu)))) < HBP_NUM
	197	*
	198	* -> If there are already non-pinned counters in this cpu, it means
	199	* there is already a free slot for them.
	200	* Otherwise, we check that the maximum number of per task
	201	* breakpoints (for this cpu) plus the number of per cpu breakpoint
	202	* (for this cpu) doesn't cover every registers.
	203	*
	204	* - If attached to every cpus, check:
	205	*
	206	* (per_cpu(nr_bp_flexible, ) \|\| (max(per_cpu(nr_cpu_bp_pinned, ))
	207	* + max(per_cpu(task_bp_pinned, *)))) < HBP_NUM
	208	*
	209	* -> This is roughly the same, except we check the number of per cpu
	210	* bp for every cpu and we keep the max one. Same for the per tasks
	211	* breakpoints.
	212	*
	213	*
	214	* == Pinned counter ==
	215	*
	216	* - If attached to a single cpu, check:
	217	*
	218	* ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu)
	219	* + max(per_cpu(task_bp_pinned, cpu))) < HBP_NUM
	220	*
	221	* -> Same checks as before. But now the nr_bp_flexible, if any, must keep
222	* one register at least (or they will never be fed).
223	*
224	* - If attached to every cpus, check:
225	*
226	* ((per_cpu(nr_bp_flexible, ) > 1) + max(per_cpu(nr_cpu_bp_pinned, ))
227	* + max(per_cpu(task_bp_pinned, *))) < HBP_NUM
228	*/
229	int reserve_bp_slot(struct perf_event *bp)
230	{
231	struct bp_busy_slots slots = {0};
232	int ret = 0;
233
234	mutex_lock(&nr_bp_mutex);
235
236	fetch_bp_busy_slots(&slots, bp->cpu);
237
238	/* Flexible counters need to keep at least one slot */
239	if (slots.pinned + (!!slots.flexible) == HBP_NUM) {
240	ret = -ENOSPC;
241	goto end;
242	}
243
244	toggle_bp_slot(bp, true);
245
246	end:
247	mutex_unlock(&nr_bp_mutex);
248
249	return ret;
250	}
251
24f1e32c	252	void release_bp_slot(struct perf_event *bp)
62a038d3	253	{
ba1c813a FW	254	mutex_lock(&nr_bp_mutex);
	255
	256	toggle_bp_slot(bp, false);
	257
	258	mutex_unlock(&nr_bp_mutex);
62a038d3 P	259	}
62a038d3 P	260
ba1c813a	261
24f1e32c	262	int __register_perf_hw_breakpoint(struct perf_event *bp)
62a038d3	263	{
24f1e32c	264	int ret;
62a038d3	265
24f1e32c FW	266	ret = reserve_bp_slot(bp);
	267	if (ret)
	268	return ret;
62a038d3	269
fdf6bc95 FW	270	/*
	271	* Ptrace breakpoints can be temporary perf events only
	272	* meant to reserve a slot. In this case, it is created disabled and
	273	* we don't want to check the params right now (as we put a null addr)
	274	* But perf tools create events as disabled and we want to check
	275	* the params for them.
	276	* This is a quick hack that will be removed soon, once we remove
	277	* the tmp breakpoints from ptrace
	278	*/
	279	if (!bp->attr.disabled \|\| bp->callback == perf_bp_event)
24f1e32c	280	ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
62a038d3	281
24f1e32c FW	282	return ret;
24f1e32c FW	283	}
62a038d3	284
24f1e32c FW	285	int register_perf_hw_breakpoint(struct perf_event *bp)
	286	{
	287	bp->callback = perf_bp_event;
62a038d3	288
24f1e32c	289	return __register_perf_hw_breakpoint(bp);
62a038d3 P	290	}
62a038d3 P	291
62a038d3 P	292	/**
62a038d3 P	293	* register_user_hw_breakpoint - register a hardware breakpoint for user space
5fa10b28	294	* @attr: breakpoint attributes
24f1e32c	295	* @triggered: callback to trigger when we hit the breakpoint
62a038d3	296	* @tsk: pointer to 'task_struct' of the process to which the address belongs
62a038d3	297	*/
24f1e32c	298	struct perf_event *
5fa10b28	299	register_user_hw_breakpoint(struct perf_event_attr *attr,
24f1e32c	300	perf_callback_t triggered,
5fa10b28	301	struct task_struct *tsk)
62a038d3	302	{
5fa10b28	303	return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
62a038d3 P	304	}
	305	EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
	306
	307	/**
	308	* modify_user_hw_breakpoint - modify a user-space hardware breakpoint
24f1e32c	309	* @bp: the breakpoint structure to modify
5fa10b28	310	* @attr: new breakpoint attributes
24f1e32c	311	* @triggered: callback to trigger when we hit the breakpoint
62a038d3	312	* @tsk: pointer to 'task_struct' of the process to which the address belongs
62a038d3	313	*/
24f1e32c	314	struct perf_event *
5fa10b28	315	modify_user_hw_breakpoint(struct perf_event bp, struct perf_event_attr attr,
24f1e32c	316	perf_callback_t triggered,
5fa10b28	317	struct task_struct *tsk)
62a038d3	318	{
24f1e32c FW	319	/*
	320	* FIXME: do it without unregistering
	321	* - We don't want to lose our slot
	322	* - If the new bp is incorrect, don't lose the older one
	323	*/
	324	unregister_hw_breakpoint(bp);
62a038d3	325
5fa10b28	326	return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
62a038d3 P	327	}
	328	EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
	329
	330	/**
24f1e32c	331	* unregister_hw_breakpoint - unregister a user-space hardware breakpoint
62a038d3	332	* @bp: the breakpoint structure to unregister
62a038d3	333	*/
24f1e32c	334	void unregister_hw_breakpoint(struct perf_event *bp)
62a038d3	335	{
24f1e32c FW	336	if (!bp)
	337	return;
	338	perf_event_release_kernel(bp);
	339	}
	340	EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
	341
62a038d3	342	/**
24f1e32c	343	* register_wide_hw_breakpoint - register a wide breakpoint in the kernel
dd1853c3	344	* @attr: breakpoint attributes
24f1e32c	345	* @triggered: callback to trigger when we hit the breakpoint
62a038d3	346	*
24f1e32c	347	* @return a set of per_cpu pointers to perf events
62a038d3	348	*/
24f1e32c	349	struct perf_event **
dd1853c3 FW	350	register_wide_hw_breakpoint(struct perf_event_attr *attr,
dd1853c3 FW	351	perf_callback_t triggered)
62a038d3	352	{
24f1e32c FW	353	struct perf_event cpu_events, pevent, *bp;
	354	long err;
	355	int cpu;
	356
	357	cpu_events = alloc_percpu(typeof(*cpu_events));
	358	if (!cpu_events)
	359	return ERR_PTR(-ENOMEM);
62a038d3	360
24f1e32c FW	361	for_each_possible_cpu(cpu) {
24f1e32c FW	362	pevent = per_cpu_ptr(cpu_events, cpu);
dd1853c3	363	bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered);
62a038d3	364
24f1e32c	365	*pevent = bp;
62a038d3	366
605bfaee	367	if (IS_ERR(bp)) {
24f1e32c FW	368	err = PTR_ERR(bp);
	369	goto fail;
	370	}
62a038d3 P	371	}
62a038d3 P	372
24f1e32c FW	373	return cpu_events;
	374
	375	fail:
	376	for_each_possible_cpu(cpu) {
	377	pevent = per_cpu_ptr(cpu_events, cpu);
605bfaee	378	if (IS_ERR(*pevent))
24f1e32c FW	379	break;
	380	unregister_hw_breakpoint(*pevent);
	381	}
	382	free_percpu(cpu_events);
	383	/* return the error if any */
	384	return ERR_PTR(err);
62a038d3	385	}
f60d24d2	386	EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
62a038d3 P	387
62a038d3 P	388	/**
24f1e32c FW	389	* unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
24f1e32c FW	390	* @cpu_events: the per cpu set of events to unregister
62a038d3	391	*/
24f1e32c	392	void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)
62a038d3	393	{
24f1e32c FW	394	int cpu;
24f1e32c FW	395	struct perf_event **pevent;
62a038d3	396
24f1e32c FW	397	for_each_possible_cpu(cpu) {
	398	pevent = per_cpu_ptr(cpu_events, cpu);
	399	unregister_hw_breakpoint(*pevent);
62a038d3	400	}
24f1e32c	401	free_percpu(cpu_events);
62a038d3	402	}
f60d24d2	403	EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
62a038d3 P	404
	405	static struct notifier_block hw_breakpoint_exceptions_nb = {
	406	.notifier_call = hw_breakpoint_exceptions_notify,
	407	/* we need to be notified first */
	408	.priority = 0x7fffffff
	409	};
	410
	411	static int __init init_hw_breakpoint(void)
	412	{
	413	return register_die_notifier(&hw_breakpoint_exceptions_nb);
	414	}
62a038d3	415	core_initcall(init_hw_breakpoint);
24f1e32c FW	416
	417
	418	struct pmu perf_ops_bp = {
	419	.enable = arch_install_hw_breakpoint,
	420	.disable = arch_uninstall_hw_breakpoint,
	421	.read = hw_breakpoint_pmu_read,
	422	.unthrottle = hw_breakpoint_pmu_unthrottle
	423	};