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/*
*
* Function return tracer.
* Copyright (c) 2008 Frederic Weisbecker <fweisbec@gmail.com>
* Mostly borrowed from function tracer which
* is Copyright (c) Steven Rostedt <srostedt@redhat.com>
*
*/
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/fs.h>
#include "trace.h"
static void start_return_trace(struct trace_array *tr)
{
register_ftrace_return(&trace_function_return);
}
static void stop_return_trace(struct trace_array *tr)
{
unregister_ftrace_return();
}
static void return_trace_init(struct trace_array *tr)
{
int cpu;
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
start_return_trace(tr);
}
static void return_trace_reset(struct trace_array *tr)
{
stop_return_trace(tr);
}
enum print_line_t
print_return_function(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry = iter->ent;
struct ftrace_ret_entry *field;
int ret;
if (entry->type == TRACE_FN_RET) {
trace_assign_type(field, entry);
ret = trace_seq_printf(s, "%pF -> ", (void *)field->parent_ip);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = seq_print_ip_sym(s, field->ip,
trace_flags & TRACE_ITER_SYM_MASK);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, " (%llu ns)\n",
field->rettime - field->calltime);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
else
return TRACE_TYPE_HANDLED;
}
return TRACE_TYPE_UNHANDLED;
}
static struct tracer return_trace __read_mostly =
{
.name = "return",
.init = return_trace_init,
.reset = return_trace_reset,
.print_line = print_return_function
};
static __init int init_return_trace(void)
{
return register_tracer(&return_trace);
}
device_initcall(init_return_trace);
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