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 #include <linux/time.h>
  13
  14 #include "trace.h"
  15 #include "trace_output.h"
  16
  17 static struct trace_array *boot_trace;
  18 static bool pre_initcalls_finished;
  19
  20 /* Tells the boot tracer that the pre_smp_initcalls are finished.
  21  * So we are ready .
  22  * It doesn't enable sched events tracing however.
  23  * You have to call enable_boot_trace to do so.
  24  */
  25 void start_boot_trace(void)
  26 {
  27         pre_initcalls_finished = true;
  28 }
  29
  30 void enable_boot_trace(void)
  31 {
  32         if (boot_trace && pre_initcalls_finished)
  33                 tracing_start_sched_switch_record();
  34 }
  35
  36 void disable_boot_trace(void)
  37 {
  38         if (boot_trace && pre_initcalls_finished)
  39                 tracing_stop_sched_switch_record();
  40 }
  41
  42 static int boot_trace_init(struct trace_array *tr)
  43 {
  44         boot_trace = tr;
  45
  46         if (!tr)
  47                 return 0;
  48
  49         tracing_reset_online_cpus(tr);
  50
  51         tracing_sched_switch_assign_trace(tr);
  52         return 0;
  53 }
  54
  55 static enum print_line_t
  56 initcall_call_print_line(struct trace_iterator *iter)
  57 {
  58         struct trace_entry *entry = iter->ent;
  59         struct trace_seq *s = &iter->seq;
  60         struct trace_boot_call *field;
  61         struct boot_trace_call *call;
  62         u64 ts;
  63         unsigned long nsec_rem;
  64         int ret;
  65
  66         trace_assign_type(field, entry);
  67         call = &field->boot_call;
  68         ts = iter->ts;
  69         nsec_rem = do_div(ts, NSEC_PER_SEC);
  70
  71         ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  72                         (unsigned long)ts, nsec_rem, call->func, call->caller);
  73
  74         if (!ret)
  75                 return TRACE_TYPE_PARTIAL_LINE;
  76         else
  77                 return TRACE_TYPE_HANDLED;
  78 }
  79
  80 static enum print_line_t
  81 initcall_ret_print_line(struct trace_iterator *iter)
  82 {
  83         struct trace_entry *entry = iter->ent;
  84         struct trace_seq *s = &iter->seq;
  85         struct trace_boot_ret *field;
  86         struct boot_trace_ret *init_ret;
  87         u64 ts;
  88         unsigned long nsec_rem;
  89         int ret;
  90
  91         trace_assign_type(field, entry);
  92         init_ret = &field->boot_ret;
  93         ts = iter->ts;
  94         nsec_rem = do_div(ts, NSEC_PER_SEC);
  95
  96         ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  97                         "returned %d after %llu msecs\n",
  98                         (unsigned long) ts,
  99                         nsec_rem,
 100                         init_ret->func, init_ret->result, init_ret->duration);
 101
 102         if (!ret)
 103                 return TRACE_TYPE_PARTIAL_LINE;
 104         else
 105                 return TRACE_TYPE_HANDLED;
 106 }
 107
 108 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
 109 {
 110         struct trace_entry *entry = iter->ent;
 111
 112         switch (entry->type) {
 113         case TRACE_BOOT_CALL:
 114                 return initcall_call_print_line(iter);
 115         case TRACE_BOOT_RET:
 116                 return initcall_ret_print_line(iter);
 117         default:
 118                 return TRACE_TYPE_UNHANDLED;
 119         }
 120 }
 121
 122 struct tracer boot_tracer __read_mostly =
 123 {
 124         .name           = "initcall",
 125         .init           = boot_trace_init,
 126         .reset          = tracing_reset_online_cpus,
 127         .print_line     = initcall_print_line,
 128 };
 129
 130 void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
 131 {
 132         struct ring_buffer_event *event;
 133         struct ring_buffer *buffer;
 134         struct trace_boot_call *entry;
 135         struct trace_array *tr = boot_trace;
 136
 137         if (!tr || !pre_initcalls_finished)
 138                 return;
 139
 140         /* Get its name now since this function could
 141          * disappear because it is in the .init section.
 142          */
 143         sprint_symbol(bt->func, (unsigned long)fn);
 144         preempt_disable();
 145
 146         buffer = tr->buffer;
 147         event = trace_buffer_lock_reserve(buffer, TRACE_BOOT_CALL,
 148                                           sizeof(*entry), 0, 0);
 149         if (!event)
 150                 goto out;
 151         entry   = ring_buffer_event_data(event);
 152         entry->boot_call = *bt;
 153         trace_buffer_unlock_commit(buffer, event, 0, 0);
 154  out:
 155         preempt_enable();
 156 }
 157
 158 void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
 159 {
 160         struct ring_buffer_event *event;
 161         struct ring_buffer *buffer;
 162         struct trace_boot_ret *entry;
 163         struct trace_array *tr = boot_trace;
 164
 165         if (!tr || !pre_initcalls_finished)
 166                 return;
 167
 168         sprint_symbol(bt->func, (unsigned long)fn);
 169         preempt_disable();
 170
 171         buffer = tr->buffer;
 172         event = trace_buffer_lock_reserve(buffer, TRACE_BOOT_RET,
 173                                           sizeof(*entry), 0, 0);
 174         if (!event)
 175                 goto out;
 176         entry   = ring_buffer_event_data(event);
 177         entry->boot_ret = *bt;
 178         trace_buffer_unlock_commit(buffer, event, 0, 0);
 179  out:
 180         preempt_enable();
 181 }