/*
* trace stack traces
*
* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
*/
#include <linux/kallsyms.h>
#include <linux/debugfs.h>
#include <linux/hrtimer.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/fs.h>
#include "trace.h"
static struct trace_array *ctx_trace;
static int __read_mostly tracer_enabled;
static const unsigned long sample_period = 1000000;
/*
* Per CPU hrtimers that do the profiling:
*/
static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer);
static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer)
{
/* trace here */
panic_timeout++;
hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
return HRTIMER_RESTART;
}
static void start_stack_timer(int cpu)
{
struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = stack_trace_timer_fn;
hrtimer->cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL);
}
static void start_stack_timers(void)
{
cpumask_t saved_mask = current->cpus_allowed;
int cpu;
for_each_online_cpu(cpu) {
set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
start_stack_timer(cpu);
printk("started timer on cpu%d\n", cpu);
}
set_cpus_allowed_ptr(current, &saved_mask);
}
static void stop_stack_timer(int cpu)
{
struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
hrtimer_cancel(hrtimer);
printk("cancelled timer on cpu%d\n", cpu);
}
static void stop_stack_timers(void)
{
int cpu;
for_each_online_cpu(cpu)
stop_stack_timer(cpu);
}
static notrace void stack_reset(struct trace_array *tr)
{
int cpu;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
tracing_reset(tr->data[cpu]);
}
static notrace void start_stack_trace(struct trace_array *tr)
{
stack_reset(tr);
start_stack_timers();
tracer_enabled = 1;
}
static notrace void stop_stack_trace(struct trace_array *tr)
{
stop_stack_timers();
tracer_enabled = 0;
}
static notrace void stack_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
if (tr->ctrl)
start_stack_trace(tr);
}
static notrace void stack_trace_reset(struct trace_array *tr)
{
if (tr->ctrl)
stop_stack_trace(tr);
}
static void stack_trace_ctrl_update(struct trace_array *tr)
{
/* When starting a new trace, reset the buffers */
if (tr->ctrl)
start_stack_trace(tr);
else
stop_stack_trace(tr);
}
static struct tracer stack_trace __read_mostly =
{
.name = "sysprof",
.init = stack_trace_init,
.reset = stack_trace_reset,
.ctrl_update = stack_trace_ctrl_update,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_stack,
#endif
};
__init static int init_stack_trace(void)
{
return register_tracer(&stack_trace);
}
device_initcall(init_stack_trace);
