kernel/trace/trace_boot.c

   1 /*
   2  * ring buffer based initcalls tracer
   3  *
   4  * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
   5  *
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/debugfs.h>
  10 #include <linux/ftrace.h>
  11 #include <linux/kallsyms.h>
  12
  13 #include "trace.h"
  14
  15 static struct trace_array *boot_trace;
  16 static bool pre_initcalls_finished;
  17
  18 /* Tells the boot tracer that the pre_smp_initcalls are finished.
  19  * So we are ready .
  20  * It doesn't enable sched events tracing however.
  21  * You have to call enable_boot_trace to do so.
  22  */
  23 void start_boot_trace(void)
  24 {
  25         pre_initcalls_finished = true;
  26 }
  27
  28 void enable_boot_trace(void)
  29 {
  30         if (pre_initcalls_finished)
  31                 tracing_start_cmdline_record();
  32 }
  33
  34 void disable_boot_trace(void)
  35 {
  36         if (pre_initcalls_finished)
  37                 tracing_stop_cmdline_record();
  38 }
  39
  40 static void reset_boot_trace(struct trace_array *tr)
  41 {
  42         int cpu;
  43
  44         tr->time_start = ftrace_now(tr->cpu);
  45
  46         for_each_online_cpu(cpu)
  47                 tracing_reset(tr, cpu);
  48 }
  49
  50 static void boot_trace_init(struct trace_array *tr)
  51 {
  52         int cpu;
  53         boot_trace = tr;
  54
  55         for_each_cpu_mask(cpu, cpu_possible_map)
  56                 tracing_reset(tr, cpu);
  57
  58         tracing_cmdline_assign_trace(tr);
  59 }
  60
  61 static void boot_trace_ctrl_update(struct trace_array *tr)
  62 {
  63         if (tr->ctrl)
  64                 enable_boot_trace();
  65         else
  66                 disable_boot_trace();
  67 }
  68
  69 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
  70 {
  71         int ret;
  72         struct trace_entry *entry = iter->ent;
  73         struct trace_boot *field = (struct trace_boot *)entry;
  74         struct boot_trace *it = &field->initcall;
  75         struct trace_seq *s = &iter->seq;
  76         struct timespec calltime = ktime_to_timespec(it->calltime);
  77         struct timespec rettime = ktime_to_timespec(it->rettime);
  78
  79         if (entry->type == TRACE_BOOT) {
  80                 ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  81                                           calltime.tv_sec,
  82                                           calltime.tv_nsec,
  83                                           it->func, it->caller);
  84                 if (!ret)
  85                         return TRACE_TYPE_PARTIAL_LINE;
  86
  87                 ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  88                                           "returned %d after %lld msecs\n",
  89                                           rettime.tv_sec,
  90                                           rettime.tv_nsec,
  91                                           it->func, it->result, it->duration);
  92
  93                 if (!ret)
  94                         return TRACE_TYPE_PARTIAL_LINE;
  95                 return TRACE_TYPE_HANDLED;
  96         }
  97         return TRACE_TYPE_UNHANDLED;
  98 }
  99
 100 struct tracer boot_tracer __read_mostly =
 101 {
 102         .name           = "initcall",
 103         .init           = boot_trace_init,
 104         .reset          = reset_boot_trace,
 105         .ctrl_update    = boot_trace_ctrl_update,
 106         .print_line     = initcall_print_line,
 107 };
 108
 109 void trace_boot(struct boot_trace *it, initcall_t fn)
 110 {
 111         struct ring_buffer_event *event;
 112         struct trace_boot *entry;
 113         struct trace_array_cpu *data;
 114         unsigned long irq_flags;
 115         struct trace_array *tr = boot_trace;
 116
 117         if (!pre_initcalls_finished)
 118                 return;
 119
 120         /* Get its name now since this function could
 121          * disappear because it is in the .init section.
 122          */
 123         sprint_symbol(it->func, (unsigned long)fn);
 124         preempt_disable();
 125         data = tr->data[smp_processor_id()];
 126
 127         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 128                                          &irq_flags);
 129         if (!event)
 130                 goto out;
 131         entry   = ring_buffer_event_data(event);
 132         tracing_generic_entry_update(&entry->ent, 0, 0);
 133         entry->ent.type = TRACE_BOOT;
 134         entry->initcall = *it;
 135         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 136
 137         trace_wake_up();
 138
 139  out:
 140         preempt_enable();
 141 }