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