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   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 }
  31
  32 void disable_boot_trace(void)
  33 {
  34 }
  35
  36 void reset_boot_trace(struct trace_array *tr)
  37 {
  38         disable_boot_trace();
  39 }
  40
  41 static void boot_trace_init(struct trace_array *tr)
  42 {
  43         int cpu;
  44         boot_trace = tr;
  45
  46         for_each_cpu_mask(cpu, cpu_possible_map)
  47                 tracing_reset(tr, cpu);
  48 }
  49
  50 static void boot_trace_ctrl_update(struct trace_array *tr)
  51 {
  52         if (tr->ctrl)
  53                 enable_boot_trace();
  54         else
  55                 disable_boot_trace();
  56 }
  57
  58 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
  59 {
  60         int ret;
  61         struct trace_entry *entry = iter->ent;
  62         struct trace_boot *field = (struct trace_boot *)entry;
  63         struct boot_trace *it = &field->initcall;
  64         struct trace_seq *s = &iter->seq;
  65         struct timespec calltime = ktime_to_timespec(it->calltime);
  66         struct timespec rettime = ktime_to_timespec(it->rettime);
  67
  68         if (entry->type == TRACE_BOOT) {
  69                 ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  70                                           calltime.tv_sec,
  71                                           calltime.tv_nsec,
  72                                           it->func, it->caller);
  73                 if (!ret)
  74                         return TRACE_TYPE_PARTIAL_LINE;
  75
  76                 ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  77                                           "returned %d after %lld msecs\n",
  78                                           rettime.tv_sec,
  79                                           rettime.tv_nsec,
  80                                           it->func, it->result, it->duration);
  81
  82                 if (!ret)
  83                         return TRACE_TYPE_PARTIAL_LINE;
  84                 return TRACE_TYPE_HANDLED;
  85         }
  86         return TRACE_TYPE_UNHANDLED;
  87 }
  88
  89 struct tracer boot_tracer __read_mostly =
  90 {
  91         .name           = "initcall",
  92         .init           = boot_trace_init,
  93         .reset          = reset_boot_trace,
  94         .ctrl_update    = boot_trace_ctrl_update,
  95         .print_line     = initcall_print_line,
  96 };
  97
  98 void trace_boot(struct boot_trace *it, initcall_t fn)
  99 {
 100         struct ring_buffer_event *event;
 101         struct trace_boot *entry;
 102         struct trace_array_cpu *data;
 103         unsigned long irq_flags;
 104         struct trace_array *tr = boot_trace;
 105
 106         if (!pre_initcalls_finished)
 107                 return;
 108
 109         /* Get its name now since this function could
 110          * disappear because it is in the .init section.
 111          */
 112         sprint_symbol(it->func, (unsigned long)fn);
 113         preempt_disable();
 114         data = tr->data[smp_processor_id()];
 115
 116         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 117                                          &irq_flags);
 118         if (!event)
 119                 goto out;
 120         entry   = ring_buffer_event_data(event);
 121         tracing_generic_entry_update(&entry->ent, 0, 0);
 122         entry->ent.type = TRACE_BOOT;
 123         entry->initcall = *it;
 124         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 125
 126         trace_wake_up();
 127
 128  out:
 129         preempt_enable();
 130 }