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 #include "trace_output.h"
  15
  16 static struct trace_array *boot_trace;
  17 static bool pre_initcalls_finished;
  18
  19 /* Tells the boot tracer that the pre_smp_initcalls are finished.
  20  * So we are ready .
  21  * It doesn't enable sched events tracing however.
  22  * You have to call enable_boot_trace to do so.
  23  */
  24 void start_boot_trace(void)
  25 {
  26         pre_initcalls_finished = true;
  27 }
  28
  29 void enable_boot_trace(void)
  30 {
  31         if (boot_trace && pre_initcalls_finished)
  32                 tracing_start_sched_switch_record();
  33 }
  34
  35 void disable_boot_trace(void)
  36 {
  37         if (boot_trace && pre_initcalls_finished)
  38                 tracing_stop_sched_switch_record();
  39 }
  40
  41 static int boot_trace_init(struct trace_array *tr)
  42 {
  43         int cpu;
  44         boot_trace = tr;
  45
  46         if (!tr)
  47                 return 0;
  48
  49         for_each_cpu(cpu, cpu_possible_mask)
  50                 tracing_reset(tr, cpu);
  51
  52         tracing_sched_switch_assign_trace(tr);
  53         return 0;
  54 }
  55
  56 static enum print_line_t
  57 initcall_call_print_line(struct trace_iterator *iter)
  58 {
  59         struct trace_entry *entry = iter->ent;
  60         struct trace_seq *s = &iter->seq;
  61         struct trace_boot_call *field;
  62         struct boot_trace_call *call;
  63         u64 ts;
  64         unsigned long nsec_rem;
  65         int ret;
  66
  67         trace_assign_type(field, entry);
  68         call = &field->boot_call;
  69         ts = iter->ts;
  70         nsec_rem = do_div(ts, 1000000000);
  71
  72         ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  73                         (unsigned long)ts, nsec_rem, call->func, call->caller);
  74
  75         if (!ret)
  76                 return TRACE_TYPE_PARTIAL_LINE;
  77         else
  78                 return TRACE_TYPE_HANDLED;
  79 }
  80
  81 static enum print_line_t
  82 initcall_ret_print_line(struct trace_iterator *iter)
  83 {
  84         struct trace_entry *entry = iter->ent;
  85         struct trace_seq *s = &iter->seq;
  86         struct trace_boot_ret *field;
  87         struct boot_trace_ret *init_ret;
  88         u64 ts;
  89         unsigned long nsec_rem;
  90         int ret;
  91
  92         trace_assign_type(field, entry);
  93         init_ret = &field->boot_ret;
  94         ts = iter->ts;
  95         nsec_rem = do_div(ts, 1000000000);
  96
  97         ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  98                         "returned %d after %llu msecs\n",
  99                         (unsigned long) ts,
 100                         nsec_rem,
 101                         init_ret->func, init_ret->result, init_ret->duration);
 102
 103         if (!ret)
 104                 return TRACE_TYPE_PARTIAL_LINE;
 105         else
 106                 return TRACE_TYPE_HANDLED;
 107 }
 108
 109 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
 110 {
 111         struct trace_entry *entry = iter->ent;
 112
 113         switch (entry->type) {
 114         case TRACE_BOOT_CALL:
 115                 return initcall_call_print_line(iter);
 116         case TRACE_BOOT_RET:
 117                 return initcall_ret_print_line(iter);
 118         default:
 119                 return TRACE_TYPE_UNHANDLED;
 120         }
 121 }
 122
 123 struct tracer boot_tracer __read_mostly =
 124 {
 125         .name           = "initcall",
 126         .init           = boot_trace_init,
 127         .reset          = tracing_reset_online_cpus,
 128         .print_line     = initcall_print_line,
 129 };
 130
 131 void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
 132 {
 133         struct ring_buffer_event *event;
 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         event = trace_buffer_lock_reserve(tr, TRACE_BOOT_CALL,
 147                                           sizeof(*entry), 0, 0);
 148         if (!event)
 149                 goto out;
 150         entry   = ring_buffer_event_data(event);
 151         entry->boot_call = *bt;
 152         trace_buffer_unlock_commit(tr, event, 0, 0);
 153  out:
 154         preempt_enable();
 155 }
 156
 157 void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
 158 {
 159         struct ring_buffer_event *event;
 160         struct trace_boot_ret *entry;
 161         struct trace_array *tr = boot_trace;
 162
 163         if (!tr || !pre_initcalls_finished)
 164                 return;
 165
 166         sprint_symbol(bt->func, (unsigned long)fn);
 167         preempt_disable();
 168
 169         event = trace_buffer_lock_reserve(tr, TRACE_BOOT_RET,
 170                                           sizeof(*entry), 0, 0);
 171         if (!event)
 172                 goto out;
 173         entry   = ring_buffer_event_data(event);
 174         entry->boot_ret = *bt;
 175         trace_buffer_unlock_commit(tr, event, 0, 0);
 176  out:
 177         preempt_enable();
 178 }