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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
  12 #include "trace.h"
  13
  14 static struct trace_array *boot_trace;
  15 static int trace_boot_enabled;
  16
  17
  18 /* Should be started after do_pre_smp_initcalls() in init/main.c */
  19 void start_boot_trace(void)
  20 {
  21         trace_boot_enabled = 1;
  22 }
  23
  24 void stop_boot_trace(struct trace_array *tr)
  25 {
  26         trace_boot_enabled = 0;
  27 }
  28
  29 static void boot_trace_init(struct trace_array *tr)
  30 {
  31         int cpu;
  32         boot_trace = tr;
  33
  34         trace_boot_enabled = 0;
  35
  36         for_each_cpu_mask(cpu, cpu_possible_map)
  37                 tracing_reset(tr, cpu);
  38 }
  39
  40 static void boot_trace_ctrl_update(struct trace_array *tr)
  41 {
  42         if (tr->ctrl)
  43                 start_boot_trace();
  44         else
  45                 stop_boot_trace(tr);
  46 }
  47
  48 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
  49 {
  50         int ret;
  51         struct trace_entry *entry = iter->ent;
  52         struct trace_boot *field = (struct trace_boot *)entry;
  53         struct boot_trace *it = &field->initcall;
  54         struct trace_seq *s = &iter->seq;
  55
  56         if (entry->type == TRACE_BOOT) {
  57                 ret = trace_seq_printf(s, "%pF called from %i "
  58                                        "returned %d after %lld msecs\n",
  59                                        it->func, it->caller, it->result,
  60                                        it->duration);
  61                 if (ret)
  62                         return TRACE_TYPE_HANDLED;
  63                 else
  64                         return TRACE_TYPE_PARTIAL_LINE;
  65         }
  66         return TRACE_TYPE_UNHANDLED;
  67 }
  68
  69 struct tracer boot_tracer __read_mostly =
  70 {
  71         .name           = "initcall",
  72         .init           = boot_trace_init,
  73         .reset          = stop_boot_trace,
  74         .ctrl_update    = boot_trace_ctrl_update,
  75         .print_line     = initcall_print_line,
  76 };
  77
  78
  79 void trace_boot(struct boot_trace *it)
  80 {
  81         struct ring_buffer_event *event;
  82         struct trace_boot *entry;
  83         struct trace_array_cpu *data;
  84         unsigned long irq_flags;
  85         struct trace_array *tr = boot_trace;
  86
  87         if (!trace_boot_enabled)
  88                 return;
  89
  90         preempt_disable();
  91         data = tr->data[smp_processor_id()];
  92
  93         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
  94                                          &irq_flags);
  95         if (!event)
  96                 goto out;
  97         entry   = ring_buffer_event_data(event);
  98         tracing_generic_entry_update(&entry->ent, 0);
  99         entry->ent.type = TRACE_BOOT;
 100         entry->initcall = *it;
 101         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 102
 103         trace_wake_up();
 104
 105  out:
 106         preempt_enable();
 107 }