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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 #include "trace_output.h"
  15
  16 static struct trace_array *boot_trace;
  17 static bool pre_initcalls_finished;
  18
  19 /* Tells the boot tracer that the pre_smp_initcalls are finished.
  20  * So we are ready .
  21  * It doesn't enable sched events tracing however.
  22  * You have to call enable_boot_trace to do so.
  23  */
  24 void start_boot_trace(void)
  25 {
  26         pre_initcalls_finished = true;
  27 }
  28
  29 void enable_boot_trace(void)
  30 {
  31         if (pre_initcalls_finished)
  32                 tracing_start_sched_switch_record();
  33 }
  34
  35 void disable_boot_trace(void)
  36 {
  37         if (pre_initcalls_finished)
  38                 tracing_stop_sched_switch_record();
  39 }
  40
  41 static int boot_trace_init(struct trace_array *tr)
  42 {
  43         int cpu;
  44         boot_trace = tr;
  45
  46         for_each_cpu(cpu, cpu_possible_mask)
  47                 tracing_reset(tr, cpu);
  48
  49         tracing_sched_switch_assign_trace(tr);
  50         return 0;
  51 }
  52
  53 static enum print_line_t
  54 initcall_call_print_line(struct trace_iterator *iter)
  55 {
  56         struct trace_entry *entry = iter->ent;
  57         struct trace_seq *s = &iter->seq;
  58         struct trace_boot_call *field;
  59         struct boot_trace_call *call;
  60         u64 ts;
  61         unsigned long nsec_rem;
  62         int ret;
  63
  64         trace_assign_type(field, entry);
  65         call = &field->boot_call;
  66         ts = iter->ts;
  67         nsec_rem = do_div(ts, 1000000000);
  68
  69         ret = trace_seq_printf(s, "[%5ld.%09ld] calling  %s @ %i\n",
  70                         (unsigned long)ts, nsec_rem, call->func, call->caller);
  71
  72         if (!ret)
  73                 return TRACE_TYPE_PARTIAL_LINE;
  74         else
  75                 return TRACE_TYPE_HANDLED;
  76 }
  77
  78 static enum print_line_t
  79 initcall_ret_print_line(struct trace_iterator *iter)
  80 {
  81         struct trace_entry *entry = iter->ent;
  82         struct trace_seq *s = &iter->seq;
  83         struct trace_boot_ret *field;
  84         struct boot_trace_ret *init_ret;
  85         u64 ts;
  86         unsigned long nsec_rem;
  87         int ret;
  88
  89         trace_assign_type(field, entry);
  90         init_ret = &field->boot_ret;
  91         ts = iter->ts;
  92         nsec_rem = do_div(ts, 1000000000);
  93
  94         ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s "
  95                         "returned %d after %llu msecs\n",
  96                         (unsigned long) ts,
  97                         nsec_rem,
  98                         init_ret->func, init_ret->result, init_ret->duration);
  99
 100         if (!ret)
 101                 return TRACE_TYPE_PARTIAL_LINE;
 102         else
 103                 return TRACE_TYPE_HANDLED;
 104 }
 105
 106 static enum print_line_t initcall_print_line(struct trace_iterator *iter)
 107 {
 108         struct trace_entry *entry = iter->ent;
 109
 110         switch (entry->type) {
 111         case TRACE_BOOT_CALL:
 112                 return initcall_call_print_line(iter);
 113         case TRACE_BOOT_RET:
 114                 return initcall_ret_print_line(iter);
 115         default:
 116                 return TRACE_TYPE_UNHANDLED;
 117         }
 118 }
 119
 120 struct tracer boot_tracer __read_mostly =
 121 {
 122         .name           = "initcall",
 123         .init           = boot_trace_init,
 124         .reset          = tracing_reset_online_cpus,
 125         .print_line     = initcall_print_line,
 126 };
 127
 128 void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
 129 {
 130         struct ring_buffer_event *event;
 131         struct trace_boot_call *entry;
 132         unsigned long irq_flags;
 133         struct trace_array *tr = boot_trace;
 134
 135         if (!pre_initcalls_finished)
 136                 return;
 137
 138         /* Get its name now since this function could
 139          * disappear because it is in the .init section.
 140          */
 141         sprint_symbol(bt->func, (unsigned long)fn);
 142         preempt_disable();
 143
 144         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 145                                          &irq_flags);
 146         if (!event)
 147                 goto out;
 148         entry   = ring_buffer_event_data(event);
 149         tracing_generic_entry_update(&entry->ent, 0, 0);
 150         entry->ent.type = TRACE_BOOT_CALL;
 151         entry->boot_call = *bt;
 152         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 153
 154         trace_wake_up();
 155
 156  out:
 157         preempt_enable();
 158 }
 159
 160 void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
 161 {
 162         struct ring_buffer_event *event;
 163         struct trace_boot_ret *entry;
 164         unsigned long irq_flags;
 165         struct trace_array *tr = boot_trace;
 166
 167         if (!pre_initcalls_finished)
 168                 return;
 169
 170         sprint_symbol(bt->func, (unsigned long)fn);
 171         preempt_disable();
 172
 173         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 174                                          &irq_flags);
 175         if (!event)
 176                 goto out;
 177         entry   = ring_buffer_event_data(event);
 178         tracing_generic_entry_update(&entry->ent, 0, 0);
 179         entry->ent.type = TRACE_BOOT_RET;
 180         entry->boot_ret = *bt;
 181         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 182
 183         trace_wake_up();
 184
 185  out:
 186         preempt_enable();
 187 }