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|
/*
* ring buffer based function tracer
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
* Based on code from the latency_tracer, that is:
*
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 Nadia Yvette Chambers
*/
#include <linux/ring_buffer.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/fs.h>
#include "trace.h"
/* function tracing enabled */
static int ftrace_function_enabled;
static struct trace_array *func_trace;
static void tracing_start_function_trace(void);
static void tracing_stop_function_trace(void);
static int function_trace_init(struct trace_array *tr)
{
func_trace = tr;
tr->trace_buffer.cpu = get_cpu();
put_cpu();
tracing_start_cmdline_record();
tracing_start_function_trace();
return 0;
}
static void function_trace_reset(struct trace_array *tr)
{
tracing_stop_function_trace();
tracing_stop_cmdline_record();
}
static void function_trace_start(struct trace_array *tr)
{
tracing_reset_online_cpus(&tr->trace_buffer);
}
/* Our option */
enum {
TRACE_FUNC_OPT_STACK = 0x1,
};
static struct tracer_flags func_flags;
static void
function_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct pt_regs *pt_regs)
{
struct trace_array *tr = func_trace;
struct trace_array_cpu *data;
unsigned long flags;
int bit;
int cpu;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
pc = preempt_count();
preempt_disable_notrace();
bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
if (bit < 0)
goto out;
cpu = smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
if (!atomic_read(&data->disabled)) {
local_save_flags(flags);
trace_function(tr, ip, parent_ip, flags, pc);
}
trace_clear_recursion(bit);
out:
preempt_enable_notrace();
}
static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct pt_regs *pt_regs)
{
struct trace_array *tr = func_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
/*
* Need to use raw, since this must be called before the
* recursive protection is performed.
*/
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
trace_function(tr, ip, parent_ip, flags, pc);
/*
* skip over 5 funcs:
* __ftrace_trace_stack,
* __trace_stack,
* function_stack_trace_call
* ftrace_list_func
* ftrace_call
*/
__trace_stack(tr, flags, 5, pc);
}
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static struct ftrace_ops trace_ops __read_mostly =
{
.func = function_trace_call,
.flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
};
static struct ftrace_ops trace_stack_ops __read_mostly =
{
.func = function_stack_trace_call,
.flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
};
static struct tracer_opt func_opts[] = {
#ifdef CONFIG_STACKTRACE
{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
{ } /* Always set a last empty entry */
};
static struct tracer_flags func_flags = {
.val = 0, /* By default: all flags disabled */
.opts = func_opts
};
static void tracing_start_function_trace(void)
{
ftrace_function_enabled = 0;
if (func_flags.val & TRACE_FUNC_OPT_STACK)
register_ftrace_function(&trace_stack_ops);
else
register_ftrace_function(&trace_ops);
ftrace_function_enabled = 1;
}
static void tracing_stop_function_trace(void)
{
ftrace_function_enabled = 0;
if (func_flags.val & TRACE_FUNC_OPT_STACK)
unregister_ftrace_function(&trace_stack_ops);
else
unregister_ftrace_function(&trace_ops);
}
static int func_set_flag(u32 old_flags, u32 bit, int set)
{
switch (bit) {
case TRACE_FUNC_OPT_STACK:
/* do nothing if already set */
if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
break;
if (set) {
unregister_ftrace_function(&trace_ops);
register_ftrace_function(&trace_stack_ops);
} else {
unregister_ftrace_function(&trace_stack_ops);
register_ftrace_function(&trace_ops);
}
break;
default:
return -EINVAL;
}
return 0;
}
static struct tracer function_trace __read_mostly =
{
.name = "function",
.init = function_trace_init,
.reset = function_trace_reset,
.start = function_trace_start,
.wait_pipe = poll_wait_pipe,
.flags = &func_flags,
.set_flag = func_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_function,
#endif
};
#ifdef CONFIG_DYNAMIC_FTRACE
static int update_count(void **data)
{
unsigned long *count = (long *)data;
if (!*count)
return 0;
if (*count != -1)
(*count)--;
return 1;
}
static void
ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data)
{
if (tracing_is_on())
return;
if (update_count(data))
tracing_on();
}
static void
ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data)
{
if (!tracing_is_on())
return;
if (update_count(data))
tracing_off();
}
static void
ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
{
if (tracing_is_on())
return;
tracing_on();
}
static void
ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
{
if (!tracing_is_on())
return;
tracing_off();
}
/*
* Skip 4:
* ftrace_stacktrace()
* function_trace_probe_call()
* ftrace_ops_list_func()
* ftrace_call()
*/
#define STACK_SKIP 4
static void
ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
{
trace_dump_stack(STACK_SKIP);
}
static void
ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
{
if (!tracing_is_on())
return;
if (update_count(data))
trace_dump_stack(STACK_SKIP);
}
static int
ftrace_probe_print(const char *name, struct seq_file *m,
unsigned long ip, void *data)
{
long count = (long)data;
seq_printf(m, "%ps:%s", (void *)ip, name);
if (count == -1)
seq_printf(m, ":unlimited\n");
else
seq_printf(m, ":count=%ld\n", count);
return 0;
}
static int
ftrace_traceon_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data)
{
return ftrace_probe_print("traceon", m, ip,
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