SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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/debugfs.h>
  13 #include <linux/uaccess.h>
  14 #include <linux/ftrace.h>
  15 #include <linux/fs.h>
  16
  17 #include "trace.h"
  18
  19 static struct trace_array       *func_trace;
  20
  21 static void start_function_trace(struct trace_array *tr)
  22 {
  23         func_trace = tr;
  24         tr->cpu = get_cpu();
  25         tracing_reset_online_cpus(tr);
  26         put_cpu();
  27
  28         tracing_start_cmdline_record();
  29         tracing_start_function_trace();
  30 }
  31
  32 static void stop_function_trace(struct trace_array *tr)
  33 {
  34         tracing_stop_function_trace();
  35         tracing_stop_cmdline_record();
  36 }
  37
  38 static int function_trace_init(struct trace_array *tr)
  39 {
  40         start_function_trace(tr);
  41         return 0;
  42 }
  43
  44 static void function_trace_reset(struct trace_array *tr)
  45 {
  46         stop_function_trace(tr);
  47 }
  48
  49 static void function_trace_start(struct trace_array *tr)
  50 {
  51         tracing_reset_online_cpus(tr);
  52 }
  53
  54 static void
  55 function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
  56 {
  57         struct trace_array *tr = func_trace;
  58         struct trace_array_cpu *data;
  59         unsigned long flags;
  60         long disabled;
  61         int cpu, resched;
  62         int pc;
  63
  64         if (unlikely(!ftrace_function_enabled))
  65                 return;
  66
  67         pc = preempt_count();
  68         resched = ftrace_preempt_disable();
  69         local_save_flags(flags);
  70         cpu = raw_smp_processor_id();
  71         data = tr->data[cpu];
  72         disabled = atomic_inc_return(&data->disabled);
  73
  74         if (likely(disabled == 1))
  75                 trace_function(tr, data, ip, parent_ip, flags, pc);
  76
  77         atomic_dec(&data->disabled);
  78         ftrace_preempt_enable(resched);
  79 }
  80
  81 static void
  82 function_trace_call(unsigned long ip, unsigned long parent_ip)
  83 {
  84         struct trace_array *tr = func_trace;
  85         struct trace_array_cpu *data;
  86         unsigned long flags;
  87         long disabled;
  88         int cpu;
  89         int pc;
  90
  91         if (unlikely(!ftrace_function_enabled))
  92                 return;
  93
  94         /*
  95          * Need to use raw, since this must be called before the
  96          * recursive protection is performed.
  97          */
  98         local_irq_save(flags);
  99         cpu = raw_smp_processor_id();
 100         data = tr->data[cpu];
 101         disabled = atomic_inc_return(&data->disabled);
 102
 103         if (likely(disabled == 1)) {
 104                 pc = preempt_count();
 105                 trace_function(tr, data, ip, parent_ip, flags, pc);
 106         }
 107
 108         atomic_dec(&data->disabled);
 109         local_irq_restore(flags);
 110 }
 111
 112 static void
 113 function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
 114 {
 115         struct trace_array *tr = func_trace;
 116         struct trace_array_cpu *data;
 117         unsigned long flags;
 118         long disabled;
 119         int cpu;
 120         int pc;
 121
 122         if (unlikely(!ftrace_function_enabled))
 123                 return;
 124
 125         /*
 126          * Need to use raw, since this must be called before the
 127          * recursive protection is performed.
 128          */
 129         local_irq_save(flags);
 130         cpu = raw_smp_processor_id();
 131         data = tr->data[cpu];
 132         disabled = atomic_inc_return(&data->disabled);
 133
 134         if (likely(disabled == 1)) {
 135                 pc = preempt_count();
 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, data, 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 };
 156
 157 void tracing_start_function_trace(void)
 158 {
 159         ftrace_function_enabled = 0;
 160
 161         if (trace_flags & TRACE_ITER_PREEMPTONLY)
 162                 trace_ops.func = function_trace_call_preempt_only;
 163         else
 164                 trace_ops.func = function_trace_call;
 165
 166         register_ftrace_function(&trace_ops);
 167         ftrace_function_enabled = 1;
 168 }
 169
 170 void tracing_stop_function_trace(void)
 171 {
 172         ftrace_function_enabled = 0;
 173         unregister_ftrace_function(&trace_ops);
 174 }
 175 static struct ftrace_ops trace_stack_ops __read_mostly =
 176 {
 177         .func = function_stack_trace_call,
 178 };
 179
 180 /* Our two options */
 181 enum {
 182         TRACE_FUNC_OPT_STACK = 0x1,
 183 };
 184
 185 static struct tracer_opt func_opts[] = {
 186 #ifdef CONFIG_STACKTRACE
 187         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 188 #endif
 189         { } /* Always set a last empty entry */
 190 };
 191
 192 static struct tracer_flags func_flags = {
 193         .val = 0, /* By default: all flags disabled */
 194         .opts = func_opts
 195 };
 196
 197 static int func_set_flag(u32 old_flags, u32 bit, int set)
 198 {
 199         if (bit == TRACE_FUNC_OPT_STACK) {
 200                 /* do nothing if already set */
 201                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
 202                         return 0;
 203
 204                 if (set)
 205                         register_ftrace_function(&trace_stack_ops);
 206                 else
 207                         unregister_ftrace_function(&trace_stack_ops);
 208
 209                 return 0;
 210         }
 211
 212         return -EINVAL;
 213 }
 214
 215 static struct tracer function_trace __read_mostly =
 216 {
 217         .name        = "function",
 218         .init        = function_trace_init,
 219         .reset       = function_trace_reset,
 220         .start       = function_trace_start,
 221         .flags          = &func_flags,
 222         .set_flag       = func_set_flag,
 223 #ifdef CONFIG_FTRACE_SELFTEST
 224         .selftest    = trace_selftest_startup_function,
 225 #endif
 226 };
 227
 228 static __init int init_function_trace(void)
 229 {
 230         return register_tracer(&function_trace);
 231 }
 232
 233 device_initcall(init_function_trace);