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 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 int 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_sched_switch_assign_trace(tr);
  59         return 0;
  60 }
  61
  62 static enum print_line_t
  63 initcall_call_print_line(struct trace_iterator *iter)
  64 {
  65         struct trace_entry *entry = iter->ent;
  66         struct trace_seq *s = &iter->seq;
  67         struct trace_boot_call *field;
  68         struct boot_trace_call *call;
  69         u64 ts;
  70         unsigned long nsec_rem;
  71         int ret;
  72
  73         trace_assign_type(field, entry);
  74         call = &field->boot_call;
  75         ts = iter->ts;
  76         nsec_rem = do_div(ts, 1000000000);
  77
  78         ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  79                         (unsigned long)ts, nsec_rem, call->func, call->caller);
  80
  81         if (!ret)
  82                 return TRACE_TYPE_PARTIAL_LINE;
  83         else
  84                 return TRACE_TYPE_HANDLED;
  85 }
  86
  87 static enum print_line_t
  88 initcall_ret_print_line(struct trace_iterator *iter)
  89 {
  90         struct trace_entry *entry = iter->ent;
  91         struct trace_seq *s = &iter->seq;
  92         struct trace_boot_ret *field;
  93         struct boot_trace_ret *init_ret;
  94         u64 ts;
  95         unsigned long nsec_rem;
  96         int ret;
  97
  98         trace_assign_type(field, entry);
  99         init_ret = &field->boot_ret;
 100         ts = iter->ts;
 101         nsec_rem = do_div(ts, 1000000000);
 102
 103         ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
 104                         "returned %d after %llu msecs\n",
 105                         (unsigned long) ts,
 106                         nsec_rem,
 107                         init_ret->func, init_ret->result, init_ret->duration);
 108
 109         if (!ret)
 110                 return TRACE_TYPE_PARTIAL_LINE;
 111         else
 112                 return TRACE_TYPE_HANDLED;
 113 }
 114
 115 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
 116 {
 117         struct trace_entry *entry = iter->ent;
 118
 119         switch (entry->type) {
 120         case TRACE_BOOT_CALL:
 121                 return initcall_call_print_line(iter);
 122         case TRACE_BOOT_RET:
 123                 return initcall_ret_print_line(iter);
 124         default:
 125                 return TRACE_TYPE_UNHANDLED;
 126         }
 127 }
 128
 129 struct tracer boot_tracer __read_mostly =
 130 {
 131         .name           = "initcall",
 132         .init           = boot_trace_init,
 133         .reset          = reset_boot_trace,
 134         .print_line     = initcall_print_line,
 135 };
 136
 137 void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
 138 {
 139         struct ring_buffer_event *event;
 140         struct trace_boot_call *entry;
 141         unsigned long irq_flags;
 142         struct trace_array *tr = boot_trace;
 143
 144         if (!pre_initcalls_finished)
 145                 return;
 146
 147         /* Get its name now since this function could
 148          * disappear because it is in the .init section.
 149          */
 150         sprint_symbol(bt->func, (unsigned long)fn);
 151         preempt_disable();
 152
 153         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 154                                          &irq_flags);
 155         if (!event)
 156                 goto out;
 157         entry   = ring_buffer_event_data(event);
 158         tracing_generic_entry_update(&entry->ent, 0, 0);
 159         entry->ent.type = TRACE_BOOT_CALL;
 160         entry->boot_call = *bt;
 161         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 162
 163         trace_wake_up();
 164
 165  out:
 166         preempt_enable();
 167 }
 168
 169 void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
 170 {
 171         struct ring_buffer_event *event;
 172         struct trace_boot_ret *entry;
 173         unsigned long irq_flags;
 174         struct trace_array *tr = boot_trace;
 175
 176         if (!pre_initcalls_finished)
 177                 return;
 178
 179         sprint_symbol(bt->func, (unsigned long)fn);
 180         preempt_disable();
 181
 182         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 183                                          &irq_flags);
 184         if (!event)
 185                 goto out;
 186         entry   = ring_buffer_event_data(event);
 187         tracing_generic_entry_update(&entry->ent, 0, 0);
 188         entry->ent.type = TRACE_BOOT_RET;
 189         entry->boot_ret = *bt;
 190         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 191
 192         trace_wake_up();
 193
 194  out:
 195         preempt_enable();
 196 }