K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 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 |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 18 | * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com> |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 19 | */ |
| 20 | |
| 21 | /* |
| 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. |
| 25 | */ |
| 26 | |
| 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> |
| 38 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 39 | #include <linux/hw_breakpoint.h> |
| 40 | |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 41 | #include <asm/processor.h> |
| 42 | |
| 43 | #ifdef CONFIG_X86 |
| 44 | #include <asm/debugreg.h> |
| 45 | #endif |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 46 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 47 | static atomic_t bp_slot; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 48 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 49 | int reserve_bp_slot(struct perf_event *bp) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 50 | { |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 51 | if (atomic_inc_return(&bp_slot) == HBP_NUM) { |
| 52 | atomic_dec(&bp_slot); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 53 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 54 | return -ENOSPC; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 55 | } |
| 56 | |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 57 | return 0; |
| 58 | } |
| 59 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 60 | void release_bp_slot(struct perf_event *bp) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 61 | { |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 62 | atomic_dec(&bp_slot); |
| 63 | } |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 64 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 65 | int __register_perf_hw_breakpoint(struct perf_event *bp) |
| 66 | { |
| 67 | int ret; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 68 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 69 | ret = reserve_bp_slot(bp); |
| 70 | if (ret) |
| 71 | return ret; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 72 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 73 | if (!bp->attr.disabled) |
| 74 | ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 75 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 76 | return ret; |
| 77 | } |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 78 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 79 | int register_perf_hw_breakpoint(struct perf_event *bp) |
| 80 | { |
| 81 | bp->callback = perf_bp_event; |
| 82 | |
| 83 | return __register_perf_hw_breakpoint(bp); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 84 | } |
| 85 | |
| 86 | /* |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 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 |
| 90 | * cpu. |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 91 | */ |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 92 | static struct perf_event * |
| 93 | register_user_hw_breakpoint_cpu(unsigned long addr, |
| 94 | int len, |
| 95 | int type, |
| 96 | perf_callback_t triggered, |
| 97 | pid_t pid, |
| 98 | int cpu, |
| 99 | bool active) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 100 | { |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 101 | struct perf_event_attr *attr; |
| 102 | struct perf_event *bp; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 103 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 104 | attr = kzalloc(sizeof(*attr), GFP_KERNEL); |
| 105 | if (!attr) |
| 106 | return ERR_PTR(-ENOMEM); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 107 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 108 | attr->type = PERF_TYPE_BREAKPOINT; |
| 109 | attr->size = sizeof(*attr); |
| 110 | attr->bp_addr = addr; |
| 111 | attr->bp_len = len; |
| 112 | attr->bp_type = type; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 113 | /* |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 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 |
| 116 | * must be pinned. |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 117 | */ |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 118 | attr->pinned = 1; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 119 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 120 | if (!active) |
| 121 | attr->disabled = 1; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 122 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 123 | bp = perf_event_create_kernel_counter(attr, cpu, pid, triggered); |
| 124 | kfree(attr); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 125 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 126 | return bp; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 127 | } |
| 128 | |
| 129 | /** |
| 130 | * register_user_hw_breakpoint - register a hardware breakpoint for user space |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 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 |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 135 | * @tsk: pointer to 'task_struct' of the process to which the address belongs |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 136 | * @active: should we activate it while registering it |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 137 | * |
| 138 | */ |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 139 | struct perf_event * |
| 140 | register_user_hw_breakpoint(unsigned long addr, |
| 141 | int len, |
| 142 | int type, |
| 143 | perf_callback_t triggered, |
| 144 | struct task_struct *tsk, |
| 145 | bool active) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 146 | { |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 147 | return register_user_hw_breakpoint_cpu(addr, len, type, triggered, |
| 148 | tsk->pid, -1, active); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 149 | } |
| 150 | EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); |
| 151 | |
| 152 | /** |
| 153 | * modify_user_hw_breakpoint - modify a user-space hardware breakpoint |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 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 |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 159 | * @tsk: pointer to 'task_struct' of the process to which the address belongs |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 160 | * @active: should we activate it while registering it |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 161 | */ |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 162 | struct perf_event * |
| 163 | modify_user_hw_breakpoint(struct perf_event *bp, |
| 164 | unsigned long addr, |
| 165 | int len, |
| 166 | int type, |
| 167 | perf_callback_t triggered, |
| 168 | struct task_struct *tsk, |
| 169 | bool active) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 170 | { |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 171 | /* |
| 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 |
| 175 | */ |
| 176 | unregister_hw_breakpoint(bp); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 177 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 178 | return register_user_hw_breakpoint(addr, len, type, triggered, |
| 179 | tsk, active); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 180 | } |
| 181 | EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); |
| 182 | |
| 183 | /** |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 184 | * unregister_hw_breakpoint - unregister a user-space hardware breakpoint |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 185 | * @bp: the breakpoint structure to unregister |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 186 | */ |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 187 | void unregister_hw_breakpoint(struct perf_event *bp) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 188 | { |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 189 | if (!bp) |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 190 | return; |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 191 | perf_event_release_kernel(bp); |
| 192 | } |
| 193 | EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); |
| 194 | |
| 195 | static struct perf_event * |
| 196 | register_kernel_hw_breakpoint_cpu(unsigned long addr, |
| 197 | int len, |
| 198 | int type, |
| 199 | perf_callback_t triggered, |
| 200 | int cpu, |
| 201 | bool active) |
| 202 | { |
| 203 | return register_user_hw_breakpoint_cpu(addr, len, type, triggered, |
| 204 | -1, cpu, active); |
| 205 | } |
| 206 | |
| 207 | /** |
| 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 |
| 214 | * |
| 215 | * @return a set of per_cpu pointers to perf events |
| 216 | */ |
| 217 | struct perf_event ** |
| 218 | register_wide_hw_breakpoint(unsigned long addr, |
| 219 | int len, |
| 220 | int type, |
| 221 | perf_callback_t triggered, |
| 222 | bool active) |
| 223 | { |
| 224 | struct perf_event **cpu_events, **pevent, *bp; |
| 225 | long err; |
| 226 | int cpu; |
| 227 | |
| 228 | cpu_events = alloc_percpu(typeof(*cpu_events)); |
| 229 | if (!cpu_events) |
| 230 | return ERR_PTR(-ENOMEM); |
| 231 | |
| 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); |
| 236 | |
| 237 | *pevent = bp; |
| 238 | |
| 239 | if (IS_ERR(bp) || !bp) { |
| 240 | err = PTR_ERR(bp); |
| 241 | goto fail; |
| 242 | } |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 243 | } |
| 244 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 245 | return cpu_events; |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 246 | |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 247 | fail: |
| 248 | for_each_possible_cpu(cpu) { |
| 249 | pevent = per_cpu_ptr(cpu_events, cpu); |
| 250 | if (IS_ERR(*pevent) || !*pevent) |
| 251 | break; |
| 252 | unregister_hw_breakpoint(*pevent); |
| 253 | } |
| 254 | free_percpu(cpu_events); |
| 255 | /* return the error if any */ |
| 256 | return ERR_PTR(err); |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 257 | } |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 258 | |
| 259 | /** |
| 260 | * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel |
| 261 | * @cpu_events: the per cpu set of events to unregister |
| 262 | */ |
| 263 | void unregister_wide_hw_breakpoint(struct perf_event **cpu_events) |
| 264 | { |
| 265 | int cpu; |
| 266 | struct perf_event **pevent; |
| 267 | |
| 268 | for_each_possible_cpu(cpu) { |
| 269 | pevent = per_cpu_ptr(cpu_events, cpu); |
| 270 | unregister_hw_breakpoint(*pevent); |
| 271 | } |
| 272 | free_percpu(cpu_events); |
| 273 | } |
| 274 | |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 275 | |
| 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 |
| 280 | }; |
| 281 | |
| 282 | static int __init init_hw_breakpoint(void) |
| 283 | { |
| 284 | return register_die_notifier(&hw_breakpoint_exceptions_nb); |
| 285 | } |
K.Prasad | 62a038d | 2009-06-01 23:43:33 +0530 | [diff] [blame] | 286 | core_initcall(init_hw_breakpoint); |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame^] | 287 | |
| 288 | |
| 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 |
| 294 | }; |