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_sched_switch_record();
  32 }
  33
  34 void disable_boot_trace(void)
  35 {
  36         if (pre_initcalls_finished)
  37                 tracing_stop_sched_switch_record();
  38 }
  39
  40 static int boot_trace_init(struct trace_array *tr)
  41 {
  42         int cpu;
  43         boot_trace = tr;
  44
  45         for_each_cpu(cpu, cpu_possible_mask)
  46                 tracing_reset(tr, cpu);
  47
  48         tracing_sched_switch_assign_trace(tr);
  49         return 0;
  50 }
  51
  52 static enum print_line_t
  53 initcall_call_print_line(struct trace_iterator *iter)
  54 {
  55         struct trace_entry *entry = iter->ent;
  56         struct trace_seq *s = &iter->seq;
  57         struct trace_boot_call *field;
  58         struct boot_trace_call *call;
  59         u64 ts;
  60         unsigned long nsec_rem;
  61         int ret;
  62
  63         trace_assign_type(field, entry);
  64         call = &field->boot_call;
  65         ts = iter->ts;
  66         nsec_rem = do_div(ts, 1000000000);
  67
  68         ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  69                         (unsigned long)ts, nsec_rem, call->func, call->caller);
  70
  71         if (!ret)
  72                 return TRACE_TYPE_PARTIAL_LINE;
  73         else
  74                 return TRACE_TYPE_HANDLED;
  75 }
  76
  77 static enum print_line_t
  78 initcall_ret_print_line(struct trace_iterator *iter)
  79 {
  80         struct trace_entry *entry = iter->ent;
  81         struct trace_seq *s = &iter->seq;
  82         struct trace_boot_ret *field;
  83         struct boot_trace_ret *init_ret;
  84         u64 ts;
  85         unsigned long nsec_rem;
  86         int ret;
  87
  88         trace_assign_type(field, entry);
  89         init_ret = &field->boot_ret;
  90         ts = iter->ts;
  91         nsec_rem = do_div(ts, 1000000000);
  92
  93         ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  94                         "returned %d after %llu msecs\n",
  95                         (unsigned long) ts,
  96                         nsec_rem,
  97                         init_ret->func, init_ret->result, init_ret->duration);
  98
  99         if (!ret)
 100                 return TRACE_TYPE_PARTIAL_LINE;
 101         else
 102                 return TRACE_TYPE_HANDLED;
 103 }
 104
 105 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
 106 {
 107         struct trace_entry *entry = iter->ent;
 108
 109         switch (entry->type) {
 110         case TRACE_BOOT_CALL:
 111                 return initcall_call_print_line(iter);
 112         case TRACE_BOOT_RET:
 113                 return initcall_ret_print_line(iter);
 114         default:
 115                 return TRACE_TYPE_UNHANDLED;
 116         }
 117 }
 118
 119 struct tracer boot_tracer __read_mostly =
 120 {
 121         .name           = "initcall",
 122         .init           = boot_trace_init,
 123         .reset          = tracing_reset_online_cpus,
 124         .print_line     = initcall_print_line,
 125 };
 126
 127 void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
 128 {
 129         struct ring_buffer_event *event;
 130         struct trace_boot_call *entry;
 131         unsigned long irq_flags;
 132         struct trace_array *tr = boot_trace;
 133
 134         if (!pre_initcalls_finished)
 135                 return;
 136
 137         /* Get its name now since this function could
 138          * disappear because it is in the .init section.
 139          */
 140         sprint_symbol(bt->func, (unsigned long)fn);
 141         preempt_disable();
 142
 143         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 144                                          &irq_flags);
 145         if (!event)
 146                 goto out;
 147         entry   = ring_buffer_event_data(event);
 148         tracing_generic_entry_update(&entry->ent, 0, 0);
 149         entry->ent.type = TRACE_BOOT_CALL;
 150         entry->boot_call = *bt;
 151         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 152
 153         trace_wake_up();
 154
 155  out:
 156         preempt_enable();
 157 }
 158
 159 void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
 160 {
 161         struct ring_buffer_event *event;
 162         struct trace_boot_ret *entry;
 163         unsigned long irq_flags;
 164         struct trace_array *tr = boot_trace;
 165
 166         if (!pre_initcalls_finished)
 167                 return;
 168
 169         sprint_symbol(bt->func, (unsigned long)fn);
 170         preempt_disable();
 171
 172         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 173                                          &irq_flags);
 174         if (!event)
 175                 goto out;
 176         entry   = ring_buffer_event_data(event);
 177         tracing_generic_entry_update(&entry->ent, 0, 0);
 178         entry->ent.type = TRACE_BOOT_RET;
 179         entry->boot_ret = *bt;
 180         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 181
 182         trace_wake_up();
 183
 184  out:
 185         preempt_enable();
 186 }