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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         if (pre_initcalls_finished)
  31                 tracing_start_cmdline_record();
  32 }
  33
  34 void disable_boot_trace(void)
  35 {
  36         if (pre_initcalls_finished)
  37                 tracing_stop_cmdline_record();
  38 }
  39
  40 void reset_boot_trace(struct trace_array *tr)
  41 {
  42         disable_boot_trace();
  43 }
  44
  45 static void boot_trace_init(struct trace_array *tr)
  46 {
  47         int cpu;
  48         boot_trace = tr;
  49
  50         for_each_cpu_mask(cpu, cpu_possible_map)
  51                 tracing_reset(tr, cpu);
  52
  53         sched_switch_trace.init(tr);
  54 }
  55
  56 static void boot_trace_ctrl_update(struct trace_array *tr)
  57 {
  58         if (tr->ctrl)
  59                 enable_boot_trace();
  60         else
  61                 disable_boot_trace();
  62 }
  63
  64 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
  65 {
  66         int ret;
  67         struct trace_entry *entry = iter->ent;
  68         struct trace_boot *field = (struct trace_boot *)entry;
  69         struct boot_trace *it = &field->initcall;
  70         struct trace_seq *s = &iter->seq;
  71         struct timespec calltime = ktime_to_timespec(it->calltime);
  72         struct timespec rettime = ktime_to_timespec(it->rettime);
  73
  74         if (entry->type == TRACE_BOOT) {
  75                 ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  76                                           calltime.tv_sec,
  77                                           calltime.tv_nsec,
  78                                           it->func, it->caller);
  79                 if (!ret)
  80                         return TRACE_TYPE_PARTIAL_LINE;
  81
  82                 ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  83                                           "returned %d after %lld msecs\n",
  84                                           rettime.tv_sec,
  85                                           rettime.tv_nsec,
  86                                           it->func, it->result, it->duration);
  87
  88                 if (!ret)
  89                         return TRACE_TYPE_PARTIAL_LINE;
  90                 return TRACE_TYPE_HANDLED;
  91         }
  92         return TRACE_TYPE_UNHANDLED;
  93 }
  94
  95 struct tracer boot_tracer __read_mostly =
  96 {
  97         .name           = "initcall",
  98         .init           = boot_trace_init,
  99         .reset          = reset_boot_trace,
 100         .ctrl_update    = boot_trace_ctrl_update,
 101         .print_line     = initcall_print_line,
 102 };
 103
 104 void trace_boot(struct boot_trace *it, initcall_t fn)
 105 {
 106         struct ring_buffer_event *event;
 107         struct trace_boot *entry;
 108         struct trace_array_cpu *data;
 109         unsigned long irq_flags;
 110         struct trace_array *tr = boot_trace;
 111
 112         if (!pre_initcalls_finished)
 113                 return;
 114
 115         /* Get its name now since this function could
 116          * disappear because it is in the .init section.
 117          */
 118         sprint_symbol(it->func, (unsigned long)fn);
 119         preempt_disable();
 120         data = tr->data[smp_processor_id()];
 121
 122         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 123                                          &irq_flags);
 124         if (!event)
 125                 goto out;
 126         entry   = ring_buffer_event_data(event);
 127         tracing_generic_entry_update(&entry->ent, 0, 0);
 128         entry->ent.type = TRACE_BOOT;
 129         entry->initcall = *it;
 130         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 131
 132         trace_wake_up();
 133
 134  out:
 135         preempt_enable();
 136 }