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.
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.
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.
16 * Copyright (C) 2007 Alan Stern
17 * Copyright (C) IBM Corporation, 2009
18 * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
22 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
23 * using the CPU's debug registers.
24 * This file contains the arch-independent routines.
27 #include <linux/irqflags.h>
28 #include <linux/kallsyms.h>
29 #include <linux/notifier.h>
30 #include <linux/kprobes.h>
31 #include <linux/kdebug.h>
32 #include <linux/kernel.h>
33 #include <linux/module.h>
34 #include <linux/percpu.h>
35 #include <linux/sched.h>
36 #include <linux/init.h>
37 #include <linux/smp.h>
39 #include <linux/hw_breakpoint.h>
41 #include <asm/processor.h>
44 #include <asm/debugreg.h>
47 static atomic_t bp_slot
;
49 int reserve_bp_slot(struct perf_event
*bp
)
51 if (atomic_inc_return(&bp_slot
) == HBP_NUM
) {
60 void release_bp_slot(struct perf_event
*bp
)
65 int __register_perf_hw_breakpoint(struct perf_event
*bp
)
69 ret
= reserve_bp_slot(bp
);
73 if (!bp
->attr
.disabled
)
74 ret
= arch_validate_hwbkpt_settings(bp
, bp
->ctx
->task
);
79 int register_perf_hw_breakpoint(struct perf_event
*bp
)
81 bp
->callback
= perf_bp_event
;
83 return __register_perf_hw_breakpoint(bp
);
87 * Register a breakpoint bound to a task and a given cpu.
88 * If cpu is -1, the breakpoint is active for the task in every cpu
89 * If the task is -1, the breakpoint is active for every tasks in the given
92 static struct perf_event
*
93 register_user_hw_breakpoint_cpu(unsigned long addr
,
96 perf_callback_t triggered
,
101 struct perf_event_attr
*attr
;
102 struct perf_event
*bp
;
104 attr
= kzalloc(sizeof(*attr
), GFP_KERNEL
);
106 return ERR_PTR(-ENOMEM
);
108 attr
->type
= PERF_TYPE_BREAKPOINT
;
109 attr
->size
= sizeof(*attr
);
110 attr
->bp_addr
= addr
;
112 attr
->bp_type
= type
;
114 * Such breakpoints are used by debuggers to trigger signals when
115 * we hit the excepted memory op. We can't miss such events, they
123 bp
= perf_event_create_kernel_counter(attr
, cpu
, pid
, triggered
);
130 * register_user_hw_breakpoint - register a hardware breakpoint for user space
131 * @addr: is the memory address that triggers the breakpoint
132 * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
133 * @type: the type of the access to the memory (read/write/exec)
134 * @triggered: callback to trigger when we hit the breakpoint
135 * @tsk: pointer to 'task_struct' of the process to which the address belongs
136 * @active: should we activate it while registering it
140 register_user_hw_breakpoint(unsigned long addr
,
143 perf_callback_t triggered
,
144 struct task_struct
*tsk
,
147 return register_user_hw_breakpoint_cpu(addr
, len
, type
, triggered
,
148 tsk
->pid
, -1, active
);
150 EXPORT_SYMBOL_GPL(register_user_hw_breakpoint
);
153 * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
154 * @bp: the breakpoint structure to modify
155 * @addr: is the memory address that triggers the breakpoint
156 * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
157 * @type: the type of the access to the memory (read/write/exec)
158 * @triggered: callback to trigger when we hit the breakpoint
159 * @tsk: pointer to 'task_struct' of the process to which the address belongs
160 * @active: should we activate it while registering it
163 modify_user_hw_breakpoint(struct perf_event
*bp
,
167 perf_callback_t triggered
,
168 struct task_struct
*tsk
,
172 * FIXME: do it without unregistering
173 * - We don't want to lose our slot
174 * - If the new bp is incorrect, don't lose the older one
176 unregister_hw_breakpoint(bp
);
178 return register_user_hw_breakpoint(addr
, len
, type
, triggered
,
181 EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint
);
184 * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
185 * @bp: the breakpoint structure to unregister
187 void unregister_hw_breakpoint(struct perf_event
*bp
)
191 perf_event_release_kernel(bp
);
193 EXPORT_SYMBOL_GPL(unregister_hw_breakpoint
);
195 static struct perf_event
*
196 register_kernel_hw_breakpoint_cpu(unsigned long addr
,
199 perf_callback_t triggered
,
203 return register_user_hw_breakpoint_cpu(addr
, len
, type
, triggered
,
208 * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
209 * @addr: is the memory address that triggers the breakpoint
210 * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
211 * @type: the type of the access to the memory (read/write/exec)
212 * @triggered: callback to trigger when we hit the breakpoint
213 * @active: should we activate it while registering it
215 * @return a set of per_cpu pointers to perf events
218 register_wide_hw_breakpoint(unsigned long addr
,
221 perf_callback_t triggered
,
224 struct perf_event
**cpu_events
, **pevent
, *bp
;
228 cpu_events
= alloc_percpu(typeof(*cpu_events
));
230 return ERR_PTR(-ENOMEM
);
232 for_each_possible_cpu(cpu
) {
233 pevent
= per_cpu_ptr(cpu_events
, cpu
);
234 bp
= register_kernel_hw_breakpoint_cpu(addr
, len
, type
,
235 triggered
, cpu
, active
);
239 if (IS_ERR(bp
) || !bp
) {
248 for_each_possible_cpu(cpu
) {
249 pevent
= per_cpu_ptr(cpu_events
, cpu
);
250 if (IS_ERR(*pevent
) || !*pevent
)
252 unregister_hw_breakpoint(*pevent
);
254 free_percpu(cpu_events
);
255 /* return the error if any */
260 * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
261 * @cpu_events: the per cpu set of events to unregister
263 void unregister_wide_hw_breakpoint(struct perf_event
**cpu_events
)
266 struct perf_event
**pevent
;
268 for_each_possible_cpu(cpu
) {
269 pevent
= per_cpu_ptr(cpu_events
, cpu
);
270 unregister_hw_breakpoint(*pevent
);
272 free_percpu(cpu_events
);
276 static struct notifier_block hw_breakpoint_exceptions_nb
= {
277 .notifier_call
= hw_breakpoint_exceptions_notify
,
278 /* we need to be notified first */
279 .priority
= 0x7fffffff
282 static int __init
init_hw_breakpoint(void)
284 return register_die_notifier(&hw_breakpoint_exceptions_nb
);
286 core_initcall(init_hw_breakpoint
);
289 struct pmu perf_ops_bp
= {
290 .enable
= arch_install_hw_breakpoint
,
291 .disable
= arch_uninstall_hw_breakpoint
,
292 .read
= hw_breakpoint_pmu_read
,
293 .unthrottle
= hw_breakpoint_pmu_unthrottle