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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 int trace_boot_enabled;
  17
  18
  19 /* Should be started after do_pre_smp_initcalls() in init/main.c */
  20 void start_boot_trace(void)
  21 {
  22         trace_boot_enabled = 1;
  23 }
  24
  25 void stop_boot_trace(struct trace_array *tr)
  26 {
  27         trace_boot_enabled = 0;
  28 }
  29
  30 static void boot_trace_init(struct trace_array *tr)
  31 {
  32         int cpu;
  33         boot_trace = tr;
  34
  35         trace_boot_enabled = 0;
  36
  37         for_each_cpu_mask(cpu, cpu_possible_map)
  38                 tracing_reset(tr, cpu);
  39 }
  40
  41 static void boot_trace_ctrl_update(struct trace_array *tr)
  42 {
  43         if (tr->ctrl)
  44                 start_boot_trace();
  45         else
  46                 stop_boot_trace(tr);
  47 }
  48
  49 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
  50 {
  51         int ret;
  52         struct trace_entry *entry = iter->ent;
  53         struct trace_boot *field = (struct trace_boot *)entry;
  54         struct boot_trace *it = &field->initcall;
  55         struct trace_seq *s = &iter->seq;
  56         struct timespec calltime = ktime_to_timespec(it->calltime);
  57         struct timespec rettime = ktime_to_timespec(it->rettime);
  58
  59         if (entry->type == TRACE_BOOT) {
  60                 ret = trace_seq_printf(s, "[%5ld.%06ld] calling  %s @ %i\n",
  61                                           calltime.tv_sec,
  62                                           calltime.tv_nsec,
  63                                           it->func, it->caller);
  64                 if (!ret)
  65                         return TRACE_TYPE_PARTIAL_LINE;
  66
  67                 ret = trace_seq_printf(s, "[%5ld.%06ld] initcall %s "
  68                                           "returned %d after %lld msecs\n",
  69                                           rettime.tv_sec,
  70                                           rettime.tv_nsec,
  71                                           it->func, it->result, it->duration);
  72
  73                 if (!ret)
  74                         return TRACE_TYPE_PARTIAL_LINE;
  75                 return TRACE_TYPE_HANDLED;
  76         }
  77         return TRACE_TYPE_UNHANDLED;
  78 }
  79
  80 struct tracer boot_tracer __read_mostly =
  81 {
  82         .name           = "initcall",
  83         .init           = boot_trace_init,
  84         .reset          = stop_boot_trace,
  85         .ctrl_update    = boot_trace_ctrl_update,
  86         .print_line     = initcall_print_line,
  87 };
  88
  89 void trace_boot(struct boot_trace *it, initcall_t fn)
  90 {
  91         struct ring_buffer_event *event;
  92         struct trace_boot *entry;
  93         struct trace_array_cpu *data;
  94         unsigned long irq_flags;
  95         struct trace_array *tr = boot_trace;
  96
  97         if (!trace_boot_enabled)
  98                 return;
  99
 100         /* Get its name now since this function could
 101          * disappear because it is in the .init section.
 102          */
 103         sprint_symbol(it->func, (unsigned long)fn);
 104         preempt_disable();
 105         data = tr->data[smp_processor_id()];
 106
 107         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 108                                          &irq_flags);
 109         if (!event)
 110                 goto out;
 111         entry   = ring_buffer_event_data(event);
 112         tracing_generic_entry_update(&entry->ent, 0, 0);
 113         entry->ent.type = TRACE_BOOT;
 114         entry->initcall = *it;
 115         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 116
 117         trace_wake_up();
 118
 119  out:
 120         preempt_enable();
 121 }