Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Infrastructure for profiling code inserted by 'gcc -pg'. |
| 3 | * |
| 4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> |
| 5 | * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com> |
| 6 | * |
| 7 | * Originally ported from the -rt patch by: |
| 8 | * Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com> |
| 9 | * |
| 10 | * Based on code in the latency_tracer, that is: |
| 11 | * |
| 12 | * Copyright (C) 2004-2006 Ingo Molnar |
| 13 | * Copyright (C) 2004 William Lee Irwin III |
| 14 | */ |
| 15 | |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 16 | #include <linux/stop_machine.h> |
| 17 | #include <linux/clocksource.h> |
| 18 | #include <linux/kallsyms.h> |
| 19 | #include <linux/kthread.h> |
| 20 | #include <linux/hardirq.h> |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 21 | #include <linux/ftrace.h> |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 22 | #include <linux/module.h> |
| 23 | #include <linux/hash.h> |
| 24 | #include <linux/list.h> |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 25 | |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 26 | #include "trace.h" |
| 27 | |
| 28 | static DEFINE_SPINLOCK(ftrace_lock); |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 29 | static struct ftrace_ops ftrace_list_end __read_mostly = |
| 30 | { |
| 31 | .func = ftrace_stub, |
| 32 | }; |
| 33 | |
| 34 | static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end; |
| 35 | ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub; |
| 36 | |
| 37 | /* mcount is defined per arch in assembly */ |
| 38 | EXPORT_SYMBOL(mcount); |
| 39 | |
| 40 | notrace void ftrace_list_func(unsigned long ip, unsigned long parent_ip) |
| 41 | { |
| 42 | struct ftrace_ops *op = ftrace_list; |
| 43 | |
| 44 | /* in case someone actually ports this to alpha! */ |
| 45 | read_barrier_depends(); |
| 46 | |
| 47 | while (op != &ftrace_list_end) { |
| 48 | /* silly alpha */ |
| 49 | read_barrier_depends(); |
| 50 | op->func(ip, parent_ip); |
| 51 | op = op->next; |
| 52 | }; |
| 53 | } |
| 54 | |
| 55 | /** |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 56 | * clear_ftrace_function - reset the ftrace function |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 57 | * |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 58 | * This NULLs the ftrace function and in essence stops |
| 59 | * tracing. There may be lag |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 60 | */ |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 61 | void clear_ftrace_function(void) |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 62 | { |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 63 | ftrace_trace_function = ftrace_stub; |
| 64 | } |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 65 | |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 66 | static int notrace __register_ftrace_function(struct ftrace_ops *ops) |
| 67 | { |
| 68 | /* Should never be called by interrupts */ |
| 69 | spin_lock(&ftrace_lock); |
| 70 | |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 71 | ops->next = ftrace_list; |
| 72 | /* |
| 73 | * We are entering ops into the ftrace_list but another |
| 74 | * CPU might be walking that list. We need to make sure |
| 75 | * the ops->next pointer is valid before another CPU sees |
| 76 | * the ops pointer included into the ftrace_list. |
| 77 | */ |
| 78 | smp_wmb(); |
| 79 | ftrace_list = ops; |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 80 | |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 81 | /* |
| 82 | * For one func, simply call it directly. |
| 83 | * For more than one func, call the chain. |
| 84 | */ |
| 85 | if (ops->next == &ftrace_list_end) |
| 86 | ftrace_trace_function = ops->func; |
| 87 | else |
| 88 | ftrace_trace_function = ftrace_list_func; |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 89 | |
| 90 | spin_unlock(&ftrace_lock); |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 91 | |
| 92 | return 0; |
| 93 | } |
| 94 | |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 95 | static int notrace __unregister_ftrace_function(struct ftrace_ops *ops) |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 96 | { |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 97 | struct ftrace_ops **p; |
| 98 | int ret = 0; |
| 99 | |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 100 | spin_lock(&ftrace_lock); |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 101 | |
| 102 | /* |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 103 | * If we are removing the last function, then simply point |
| 104 | * to the ftrace_stub. |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 105 | */ |
| 106 | if (ftrace_list == ops && ops->next == &ftrace_list_end) { |
| 107 | ftrace_trace_function = ftrace_stub; |
| 108 | ftrace_list = &ftrace_list_end; |
| 109 | goto out; |
| 110 | } |
| 111 | |
| 112 | for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next) |
| 113 | if (*p == ops) |
| 114 | break; |
| 115 | |
| 116 | if (*p != ops) { |
| 117 | ret = -1; |
| 118 | goto out; |
| 119 | } |
| 120 | |
| 121 | *p = (*p)->next; |
| 122 | |
| 123 | /* If we only have one func left, then call that directly */ |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 124 | if (ftrace_list == &ftrace_list_end || |
| 125 | ftrace_list->next == &ftrace_list_end) |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 126 | ftrace_trace_function = ftrace_list->func; |
| 127 | |
| 128 | out: |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 129 | spin_unlock(&ftrace_lock); |
| 130 | |
| 131 | return ret; |
| 132 | } |
| 133 | |
| 134 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 135 | |
| 136 | static struct hlist_head ftrace_hash[FTRACE_HASHSIZE]; |
| 137 | |
| 138 | static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu); |
| 139 | |
| 140 | static DEFINE_SPINLOCK(ftrace_shutdown_lock); |
| 141 | static DEFINE_MUTEX(ftraced_lock); |
| 142 | |
| 143 | static int ftraced_trigger; |
| 144 | static int ftraced_suspend; |
| 145 | |
| 146 | static int ftrace_record_suspend; |
| 147 | |
| 148 | static inline int |
| 149 | notrace ftrace_ip_in_hash(unsigned long ip, unsigned long key) |
| 150 | { |
| 151 | struct dyn_ftrace *p; |
| 152 | struct hlist_node *t; |
| 153 | int found = 0; |
| 154 | |
| 155 | hlist_for_each_entry(p, t, &ftrace_hash[key], node) { |
| 156 | if (p->ip == ip) { |
| 157 | found = 1; |
| 158 | break; |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | return found; |
| 163 | } |
| 164 | |
| 165 | static inline void notrace |
| 166 | ftrace_add_hash(struct dyn_ftrace *node, unsigned long key) |
| 167 | { |
| 168 | hlist_add_head(&node->node, &ftrace_hash[key]); |
| 169 | } |
| 170 | |
| 171 | static void notrace |
| 172 | ftrace_record_ip(unsigned long ip, unsigned long parent_ip) |
| 173 | { |
| 174 | struct dyn_ftrace *node; |
| 175 | unsigned long flags; |
| 176 | unsigned long key; |
| 177 | int resched; |
| 178 | int atomic; |
| 179 | |
| 180 | resched = need_resched(); |
| 181 | preempt_disable_notrace(); |
| 182 | |
| 183 | /* We simply need to protect against recursion */ |
| 184 | __get_cpu_var(ftrace_shutdown_disable_cpu)++; |
| 185 | if (__get_cpu_var(ftrace_shutdown_disable_cpu) != 1) |
| 186 | goto out; |
| 187 | |
| 188 | if (unlikely(ftrace_record_suspend)) |
| 189 | goto out; |
| 190 | |
| 191 | key = hash_long(ip, FTRACE_HASHBITS); |
| 192 | |
| 193 | WARN_ON_ONCE(key >= FTRACE_HASHSIZE); |
| 194 | |
| 195 | if (ftrace_ip_in_hash(ip, key)) |
| 196 | goto out; |
| 197 | |
| 198 | atomic = irqs_disabled(); |
| 199 | |
| 200 | spin_lock_irqsave(&ftrace_shutdown_lock, flags); |
| 201 | |
| 202 | /* This ip may have hit the hash before the lock */ |
| 203 | if (ftrace_ip_in_hash(ip, key)) |
| 204 | goto out_unlock; |
| 205 | |
| 206 | /* |
| 207 | * There's a slight race that the ftraced will update the |
| 208 | * hash and reset here. The arch alloc is responsible |
| 209 | * for seeing if the IP has already changed, and if |
| 210 | * it has, the alloc will fail. |
| 211 | */ |
| 212 | node = ftrace_alloc_shutdown_node(ip); |
| 213 | if (!node) |
| 214 | goto out_unlock; |
| 215 | |
| 216 | node->ip = ip; |
| 217 | |
| 218 | ftrace_add_hash(node, key); |
| 219 | |
| 220 | ftraced_trigger = 1; |
| 221 | |
| 222 | out_unlock: |
| 223 | spin_unlock_irqrestore(&ftrace_shutdown_lock, flags); |
| 224 | out: |
| 225 | __get_cpu_var(ftrace_shutdown_disable_cpu)--; |
| 226 | |
| 227 | /* prevent recursion with scheduler */ |
| 228 | if (resched) |
| 229 | preempt_enable_no_resched_notrace(); |
| 230 | else |
| 231 | preempt_enable_notrace(); |
| 232 | } |
| 233 | |
| 234 | static struct ftrace_ops ftrace_shutdown_ops __read_mostly = |
| 235 | { |
| 236 | .func = ftrace_record_ip, |
| 237 | }; |
| 238 | |
| 239 | |
| 240 | static int notrace __ftrace_modify_code(void *data) |
| 241 | { |
| 242 | void (*func)(void) = data; |
| 243 | |
| 244 | func(); |
| 245 | return 0; |
| 246 | } |
| 247 | |
| 248 | static void notrace ftrace_run_startup_code(void) |
| 249 | { |
| 250 | stop_machine_run(__ftrace_modify_code, ftrace_startup_code, NR_CPUS); |
| 251 | } |
| 252 | |
| 253 | static void notrace ftrace_run_shutdown_code(void) |
| 254 | { |
| 255 | stop_machine_run(__ftrace_modify_code, ftrace_shutdown_code, NR_CPUS); |
| 256 | } |
| 257 | |
| 258 | static void notrace ftrace_startup(void) |
| 259 | { |
| 260 | mutex_lock(&ftraced_lock); |
| 261 | ftraced_suspend++; |
| 262 | if (ftraced_suspend != 1) |
| 263 | goto out; |
| 264 | __unregister_ftrace_function(&ftrace_shutdown_ops); |
| 265 | |
| 266 | ftrace_run_startup_code(); |
| 267 | out: |
| 268 | mutex_unlock(&ftraced_lock); |
| 269 | } |
| 270 | |
| 271 | static void notrace ftrace_shutdown(void) |
| 272 | { |
| 273 | mutex_lock(&ftraced_lock); |
| 274 | ftraced_suspend--; |
| 275 | if (ftraced_suspend) |
| 276 | goto out; |
| 277 | |
| 278 | ftrace_run_shutdown_code(); |
| 279 | |
| 280 | __register_ftrace_function(&ftrace_shutdown_ops); |
| 281 | out: |
| 282 | mutex_unlock(&ftraced_lock); |
| 283 | } |
| 284 | |
| 285 | static cycle_t ftrace_update_time; |
| 286 | static unsigned long ftrace_update_cnt; |
| 287 | unsigned long ftrace_update_tot_cnt; |
| 288 | |
| 289 | static int notrace __ftrace_update_code(void *ignore) |
| 290 | { |
| 291 | struct dyn_ftrace *p; |
| 292 | struct hlist_head head; |
| 293 | struct hlist_node *t; |
| 294 | cycle_t start, stop; |
| 295 | int i; |
| 296 | |
| 297 | /* Don't be calling ftrace ops now */ |
| 298 | __unregister_ftrace_function(&ftrace_shutdown_ops); |
| 299 | |
| 300 | start = now(raw_smp_processor_id()); |
| 301 | ftrace_update_cnt = 0; |
| 302 | |
| 303 | /* No locks needed, the machine is stopped! */ |
| 304 | for (i = 0; i < FTRACE_HASHSIZE; i++) { |
| 305 | if (hlist_empty(&ftrace_hash[i])) |
| 306 | continue; |
| 307 | |
| 308 | head = ftrace_hash[i]; |
| 309 | INIT_HLIST_HEAD(&ftrace_hash[i]); |
| 310 | |
| 311 | /* all CPUS are stopped, we are safe to modify code */ |
| 312 | hlist_for_each_entry(p, t, &head, node) { |
| 313 | ftrace_code_disable(p); |
| 314 | ftrace_update_cnt++; |
| 315 | } |
| 316 | |
| 317 | } |
| 318 | |
| 319 | stop = now(raw_smp_processor_id()); |
| 320 | ftrace_update_time = stop - start; |
| 321 | ftrace_update_tot_cnt += ftrace_update_cnt; |
| 322 | |
| 323 | __register_ftrace_function(&ftrace_shutdown_ops); |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 324 | |
| 325 | return 0; |
| 326 | } |
| 327 | |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 328 | static void notrace ftrace_update_code(void) |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 329 | { |
Steven Rostedt | 3d08339 | 2008-05-12 21:20:42 +0200 | [diff] [blame^] | 330 | stop_machine_run(__ftrace_update_code, NULL, NR_CPUS); |
| 331 | } |
| 332 | |
| 333 | static int notrace ftraced(void *ignore) |
| 334 | { |
| 335 | unsigned long usecs; |
| 336 | |
| 337 | set_current_state(TASK_INTERRUPTIBLE); |
| 338 | |
| 339 | while (!kthread_should_stop()) { |
| 340 | |
| 341 | /* check once a second */ |
| 342 | schedule_timeout(HZ); |
| 343 | |
| 344 | mutex_lock(&ftraced_lock); |
| 345 | if (ftraced_trigger && !ftraced_suspend) { |
| 346 | ftrace_record_suspend++; |
| 347 | ftrace_update_code(); |
| 348 | usecs = nsecs_to_usecs(ftrace_update_time); |
| 349 | if (ftrace_update_tot_cnt > 100000) { |
| 350 | ftrace_update_tot_cnt = 0; |
| 351 | pr_info("hm, dftrace overflow: %lu change%s" |
| 352 | " (%lu total) in %lu usec%s\n", |
| 353 | ftrace_update_cnt, |
| 354 | ftrace_update_cnt != 1 ? "s" : "", |
| 355 | ftrace_update_tot_cnt, |
| 356 | usecs, usecs != 1 ? "s" : ""); |
| 357 | WARN_ON_ONCE(1); |
| 358 | } |
| 359 | ftraced_trigger = 0; |
| 360 | ftrace_record_suspend--; |
| 361 | } |
| 362 | mutex_unlock(&ftraced_lock); |
| 363 | |
| 364 | ftrace_shutdown_replenish(); |
| 365 | |
| 366 | set_current_state(TASK_INTERRUPTIBLE); |
| 367 | } |
| 368 | __set_current_state(TASK_RUNNING); |
| 369 | return 0; |
| 370 | } |
| 371 | |
| 372 | static int __init notrace ftrace_shutdown_init(void) |
| 373 | { |
| 374 | struct task_struct *p; |
| 375 | int ret; |
| 376 | |
| 377 | ret = ftrace_shutdown_arch_init(); |
| 378 | if (ret) |
| 379 | return ret; |
| 380 | |
| 381 | p = kthread_run(ftraced, NULL, "ftraced"); |
| 382 | if (IS_ERR(p)) |
| 383 | return -1; |
| 384 | |
| 385 | __register_ftrace_function(&ftrace_shutdown_ops); |
| 386 | |
| 387 | return 0; |
| 388 | } |
| 389 | |
| 390 | core_initcall(ftrace_shutdown_init); |
| 391 | #else |
| 392 | # define ftrace_startup() do { } while (0) |
| 393 | # define ftrace_shutdown() do { } while (0) |
| 394 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
| 395 | |
| 396 | /** |
| 397 | * register_ftrace_function - register a function for profiling |
| 398 | * @ops - ops structure that holds the function for profiling. |
| 399 | * |
| 400 | * Register a function to be called by all functions in the |
| 401 | * kernel. |
| 402 | * |
| 403 | * Note: @ops->func and all the functions it calls must be labeled |
| 404 | * with "notrace", otherwise it will go into a |
| 405 | * recursive loop. |
| 406 | */ |
| 407 | int register_ftrace_function(struct ftrace_ops *ops) |
| 408 | { |
| 409 | ftrace_startup(); |
| 410 | |
| 411 | return __register_ftrace_function(ops); |
| 412 | } |
| 413 | |
| 414 | /** |
| 415 | * unregister_ftrace_function - unresgister a function for profiling. |
| 416 | * @ops - ops structure that holds the function to unregister |
| 417 | * |
| 418 | * Unregister a function that was added to be called by ftrace profiling. |
| 419 | */ |
| 420 | int unregister_ftrace_function(struct ftrace_ops *ops) |
| 421 | { |
| 422 | int ret; |
| 423 | |
| 424 | ret = __unregister_ftrace_function(ops); |
| 425 | |
| 426 | if (ftrace_list == &ftrace_list_end) |
| 427 | ftrace_shutdown(); |
| 428 | |
| 429 | return ret; |
Arnaldo Carvalho de Melo | 16444a8 | 2008-05-12 21:20:42 +0200 | [diff] [blame] | 430 | } |