kernel/trace/trace_functions.c

   1 /*
   2  * ring buffer based function tracer
   3  *
   4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   6  *
   7  * Based on code from the latency_tracer, that is:
   8  *
   9  *  Copyright (C) 2004-2006 Ingo Molnar
  10  *  Copyright (C) 2004 William Lee Irwin III
  11  */
  12 #include <linux/ring_buffer.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/ftrace.h>
  16 #include <linux/fs.h>
  17
  18 #include "trace.h"
  19
  20 /* function tracing enabled */
  21 static int                      ftrace_function_enabled;
  22
  23 static struct trace_array       *func_trace;
  24
  25 static void tracing_start_function_trace(void);
  26 static void tracing_stop_function_trace(void);
  27
  28 static int function_trace_init(struct trace_array *tr)
  29 {
  30         func_trace = tr;
  31         tr->cpu = get_cpu();
  32         put_cpu();
  33
  34         tracing_start_cmdline_record();
  35         tracing_start_function_trace();
  36         return 0;
  37 }
  38
  39 static void function_trace_reset(struct trace_array *tr)
  40 {
  41         tracing_stop_function_trace();
  42         tracing_stop_cmdline_record();
  43 }
  44
  45 static void function_trace_start(struct trace_array *tr)
  46 {
  47         tracing_reset_online_cpus(tr);
  48 }
  49
  50 static void
  51 function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip,
  52                                  struct ftrace_ops *op)
  53 {
  54         struct trace_array *tr = func_trace;
  55         struct trace_array_cpu *data;
  56         unsigned long flags;
  57         long disabled;
  58         int cpu;
  59         int pc;
  60
  61         if (unlikely(!ftrace_function_enabled))
  62                 return;
  63
  64         pc = preempt_count();
  65         preempt_disable_notrace();
  66         local_save_flags(flags);
  67         cpu = raw_smp_processor_id();
  68         data = tr->data[cpu];
  69         disabled = atomic_inc_return(&data->disabled);
  70
  71         if (likely(disabled == 1))
  72                 trace_function(tr, ip, parent_ip, flags, pc);
  73
  74         atomic_dec(&data->disabled);
  75         preempt_enable_notrace();
  76 }
  77
  78 static void
  79 function_trace_call(unsigned long ip, unsigned long parent_ip,
  80                     struct ftrace_ops *op)
  81 {
  82         struct trace_array *tr = func_trace;
  83         struct trace_array_cpu *data;
  84         unsigned long flags;
  85         long disabled;
  86         int cpu;
  87         int pc;
  88
  89         if (unlikely(!ftrace_function_enabled))
  90                 return;
  91
  92         /*
  93          * Need to use raw, since this must be called before the
  94          * recursive protection is performed.
  95          */
  96         local_irq_save(flags);
  97         cpu = raw_smp_processor_id();
  98         data = tr->data[cpu];
  99         disabled = atomic_inc_return(&data->disabled);
 100
 101         if (likely(disabled == 1)) {
 102                 pc = preempt_count();
 103                 trace_function(tr, ip, parent_ip, flags, pc);
 104         }
 105
 106         atomic_dec(&data->disabled);
 107         local_irq_restore(flags);
 108 }
 109
 110 static void
 111 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 112                           struct ftrace_ops *op)
 113 {
 114         struct trace_array *tr = func_trace;
 115         struct trace_array_cpu *data;
 116         unsigned long flags;
 117         long disabled;
 118         int cpu;
 119         int pc;
 120
 121         if (unlikely(!ftrace_function_enabled))
 122                 return;
 123
 124         /*
 125          * Need to use raw, since this must be called before the
 126          * recursive protection is performed.
 127          */
 128         local_irq_save(flags);
 129         cpu = raw_smp_processor_id();
 130         data = tr->data[cpu];
 131         disabled = atomic_inc_return(&data->disabled);
 132
 133         if (likely(disabled == 1)) {
 134                 pc = preempt_count();
 135                 trace_function(tr, ip, parent_ip, flags, pc);
 136                 /*
 137                  * skip over 5 funcs:
 138                  *    __ftrace_trace_stack,
 139                  *    __trace_stack,
 140                  *    function_stack_trace_call
 141                  *    ftrace_list_func
 142                  *    ftrace_call
 143                  */
 144                 __trace_stack(tr, flags, 5, pc);
 145         }
 146
 147         atomic_dec(&data->disabled);
 148         local_irq_restore(flags);
 149 }
 150
 151
 152 static struct ftrace_ops trace_ops __read_mostly =
 153 {
 154         .func = function_trace_call,
 155         .flags = FTRACE_OPS_FL_GLOBAL,
 156 };
 157
 158 static struct ftrace_ops trace_stack_ops __read_mostly =
 159 {
 160         .func = function_stack_trace_call,
 161         .flags = FTRACE_OPS_FL_GLOBAL,
 162 };
 163
 164 /* Our two options */
 165 enum {
 166         TRACE_FUNC_OPT_STACK = 0x1,
 167 };
 168
 169 static struct tracer_opt func_opts[] = {
 170 #ifdef CONFIG_STACKTRACE
 171         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 172 #endif
 173         { } /* Always set a last empty entry */
 174 };
 175
 176 static struct tracer_flags func_flags = {
 177         .val = 0, /* By default: all flags disabled */
 178         .opts = func_opts
 179 };
 180
 181 static void tracing_start_function_trace(void)
 182 {
 183         ftrace_function_enabled = 0;
 184
 185         if (trace_flags & TRACE_ITER_PREEMPTONLY)
 186                 trace_ops.func = function_trace_call_preempt_only;
 187         else
 188                 trace_ops.func = function_trace_call;
 189
 190         if (func_flags.val & TRACE_FUNC_OPT_STACK)
 191                 register_ftrace_function(&trace_stack_ops);
 192         else
 193                 register_ftrace_function(&trace_ops);
 194
 195         ftrace_function_enabled = 1;
 196 }
 197
 198 static void tracing_stop_function_trace(void)
 199 {
 200         ftrace_function_enabled = 0;
 201
 202         if (func_flags.val & TRACE_FUNC_OPT_STACK)
 203                 unregister_ftrace_function(&trace_stack_ops);
 204         else
 205                 unregister_ftrace_function(&trace_ops);
 206 }
 207
 208 static int func_set_flag(u32 old_flags, u32 bit, int set)
 209 {
 210         if (bit == TRACE_FUNC_OPT_STACK) {
 211                 /* do nothing if already set */
 212                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
 213                         return 0;
 214
 215                 if (set) {
 216                         unregister_ftrace_function(&trace_ops);
 217                         register_ftrace_function(&trace_stack_ops);
 218                 } else {
 219                         unregister_ftrace_function(&trace_stack_ops);
 220                         register_ftrace_function(&trace_ops);
 221                 }
 222
 223                 return 0;
 224         }
 225
 226         return -EINVAL;
 227 }
 228
 229 static struct tracer function_trace __read_mostly =
 230 {
 231         .name           = "function",
 232         .init           = function_trace_init,
 233         .reset          = function_trace_reset,
 234         .start          = function_trace_start,
 235         .wait_pipe      = poll_wait_pipe,
 236         .flags          = &func_flags,
 237         .set_flag       = func_set_flag,
 238 #ifdef CONFIG_FTRACE_SELFTEST
 239         .selftest       = trace_selftest_startup_function,
 240 #endif
 241 };
 242
 243 #ifdef CONFIG_DYNAMIC_FTRACE
 244 static void
 245 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
 246 {
 247         long *count = (long *)data;
 248
 249         if (tracing_is_on())
 250                 return;
 251
 252         if (!*count)
 253                 return;
 254
 255         if (*count != -1)
 256                 (*count)--;
 257
 258         tracing_on();
 259 }
 260
 261 static void
 262 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
 263 {
 264         long *count = (long *)data;
 265
 266         if (!tracing_is_on())
 267                 return;
 268
 269         if (!*count)
 270                 return;
 271
 272         if (*count != -1)
 273                 (*count)--;
 274
 275         tracing_off();
 276 }
 277
 278 static int
 279 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
 280                          struct ftrace_probe_ops *ops, void *data);
 281
 282 static struct ftrace_probe_ops traceon_probe_ops = {
 283         .func                   = ftrace_traceon,
 284         .print                  = ftrace_trace_onoff_print,
 285 };
 286
 287 static struct ftrace_probe_ops traceoff_probe_ops = {
 288         .func                   = ftrace_traceoff,
 289         .print                  = ftrace_trace_onoff_print,
 290 };
 291
 292 static int
 293 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
 294                          struct ftrace_probe_ops *ops, void *data)
 295 {
 296         long count = (long)data;
 297
 298         seq_printf(m, "%ps:", (void *)ip);
 299
 300         if (ops == &traceon_probe_ops)
 301                 seq_printf(m, "traceon");
 302         else
 303                 seq_printf(m, "traceoff");
 304
 305         if (count == -1)
 306                 seq_printf(m, ":unlimited\n");
 307         else
 308                 seq_printf(m, ":count=%ld\n", count);
 309
 310         return 0;
 311 }
 312
 313 static int
 314 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
 315 {
 316         struct ftrace_probe_ops *ops;
 317
 318         /* we register both traceon and traceoff to this callback */
 319         if (strcmp(cmd, "traceon") == 0)
 320                 ops = &traceon_probe_ops;
 321         else
 322                 ops = &traceoff_probe_ops;
 323
 324         unregister_ftrace_function_probe_func(glob, ops);
 325
 326         return 0;
 327 }
 328
 329 static int
 330 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
 331                             char *glob, char *cmd, char *param, int enable)
 332 {
 333         struct ftrace_probe_ops *ops;
 334         void *count = (void *)-1;
 335         char *number;
 336         int ret;
 337
 338         /* hash funcs only work with set_ftrace_filter */
 339         if (!enable)
 340                 return -EINVAL;
 341
 342         if (glob[0] == '!')
 343                 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
 344
 345         /* we register both traceon and traceoff to this callback */
 346         if (strcmp(cmd, "traceon") == 0)
 347                 ops = &traceon_probe_ops;
 348         else
 349                 ops = &traceoff_probe_ops;
 350
 351         if (!param)
 352                 goto out_reg;
 353
 354         number = strsep(&param, ":");
 355
 356         if (!strlen(number))
 357                 goto out_reg;
 358
 359         /*
 360          * We use the callback data field (which is a pointer)
 361          * as our counter.
 362          */
 363         ret = strict_strtoul(number, 0, (unsigned long *)&count);
 364         if (ret)
 365                 return ret;
 366
 367  out_reg:
 368         ret = register_ftrace_function_probe(glob, ops, count);
 369
 370         return ret < 0 ? ret : 0;
 371 }
 372
 373 static struct ftrace_func_command ftrace_traceon_cmd = {
 374         .name                   = "traceon",
 375         .func                   = ftrace_trace_onoff_callback,
 376 };
 377
 378 static struct ftrace_func_command ftrace_traceoff_cmd = {
 379         .name                   = "traceoff",
 380         .func                   = ftrace_trace_onoff_callback,
 381 };
 382
 383 static int __init init_func_cmd_traceon(void)
 384 {
 385         int ret;
 386
 387         ret = register_ftrace_command(&ftrace_traceoff_cmd);
 388         if (ret)
 389                 return ret;
 390
 391         ret = register_ftrace_command(&ftrace_traceon_cmd);
 392         if (ret)
 393                 unregister_ftrace_command(&ftrace_traceoff_cmd);
 394         return ret;
 395 }
 396 #else
 397 static inline int init_func_cmd_traceon(void)
 398 {
 399         return 0;
 400 }
 401 #endif /* CONFIG_DYNAMIC_FTRACE */
 402
 403 static __init int init_function_trace(void)
 404 {
 405         init_func_cmd_traceon();
 406         return register_tracer(&function_trace);
 407 }
 408 device_initcall(init_function_trace);
 409