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 int trace_boot_enabled;
  17
  18
  19 /* Should be started after do_pre_smp_initcalls() in init/main.c */
  20 void start_boot_trace(void)
  21 {
  22         trace_boot_enabled = 1;
  23 }
  24
  25 void stop_boot_trace(void)
  26 {
  27         trace_boot_enabled = 0;
  28 }
  29
  30 void reset_boot_trace(struct trace_array *tr)
  31 {
  32         stop_boot_trace();
  33 }
  34
  35 static void boot_trace_init(struct trace_array *tr)
  36 {
  37         int cpu;
  38         boot_trace = tr;
  39
  40         trace_boot_enabled = 0;
  41
  42         for_each_cpu_mask(cpu, cpu_possible_map)
  43                 tracing_reset(tr, cpu);
  44 }
  45
  46 static void boot_trace_ctrl_update(struct trace_array *tr)
  47 {
  48         if (tr->ctrl)
  49                 start_boot_trace();
  50         else
  51                 stop_boot_trace();
  52 }
  53
  54 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
  55 {
  56         int ret;
  57         struct trace_entry *entry = iter->ent;
  58         struct trace_boot *field = (struct trace_boot *)entry;
  59         struct boot_trace *it = &field->initcall;
  60         struct trace_seq *s = &iter->seq;
  61         struct timespec calltime = ktime_to_timespec(it->calltime);
  62         struct timespec rettime = ktime_to_timespec(it->rettime);
  63
  64         if (entry->type == TRACE_BOOT) {
  65                 ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  66                                           calltime.tv_sec,
  67                                           calltime.tv_nsec,
  68                                           it->func, it->caller);
  69                 if (!ret)
  70                         return TRACE_TYPE_PARTIAL_LINE;
  71
  72                 ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  73                                           "returned %d after %lld msecs\n",
  74                                           rettime.tv_sec,
  75                                           rettime.tv_nsec,
  76                                           it->func, it->result, it->duration);
  77
  78                 if (!ret)
  79                         return TRACE_TYPE_PARTIAL_LINE;
  80                 return TRACE_TYPE_HANDLED;
  81         }
  82         return TRACE_TYPE_UNHANDLED;
  83 }
  84
  85 struct tracer boot_tracer __read_mostly =
  86 {
  87         .name           = "initcall",
  88         .init           = boot_trace_init,
  89         .reset          = reset_boot_trace,
  90         .ctrl_update    = boot_trace_ctrl_update,
  91         .print_line     = initcall_print_line,
  92 };
  93
  94 void trace_boot(struct boot_trace *it, initcall_t fn)
  95 {
  96         struct ring_buffer_event *event;
  97         struct trace_boot *entry;
  98         struct trace_array_cpu *data;
  99         unsigned long irq_flags;
 100         struct trace_array *tr = boot_trace;
 101
 102         if (!trace_boot_enabled)
 103                 return;
 104
 105         /* Get its name now since this function could
 106          * disappear because it is in the .init section.
 107          */
 108         sprint_symbol(it->func, (unsigned long)fn);
 109         preempt_disable();
 110         data = tr->data[smp_processor_id()];
 111
 112         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 113                                          &irq_flags);
 114         if (!event)
 115                 goto out;
 116         entry   = ring_buffer_event_data(event);
 117         tracing_generic_entry_update(&entry->ent, 0, 0);
 118         entry->ent.type = TRACE_BOOT;
 119         entry->initcall = *it;
 120         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 121
 122         trace_wake_up();
 123
 124  out:
 125         preempt_enable();
 126 }