/*
* trace context switch
*
* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/marker.h>
#include <linux/ftrace.h>
#include "trace.h"
static struct trace_array *ctx_trace;
static int __read_mostly tracer_enabled;
static atomic_t sched_ref;
static void
sched_switch_func(void *private, void *__rq, struct task_struct *prev,
struct task_struct *next)
{
struct trace_array **ptr = private;
struct trace_array *tr = *ptr;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
tracing_record_cmdline(prev);
tracing_record_cmdline(next);
if (!tracer_enabled)
return;
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_switch_trace(tr, data, prev, next, flags);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static notrace void
sched_switch_callback(void *probe_data, void *call_data,
const char *format, va_list *args)
{
struct task_struct *prev;
struct task_struct *next;
struct rq *__rq;
if (!atomic_read(&sched_ref))
return;
/* skip prev_pid %d next_pid %d prev_state %ld */
(void)va_arg(*args, int);
(void)va_arg(*args, int);
(void)va_arg(*args, long);
__rq = va_arg(*args, typeof(__rq));
prev = va_arg(*args, typeof(prev));
next = va_arg(*args, typeof(next));
/*
* If tracer_switch_func only points to the local
* switch func, it still needs the ptr passed to it.
*/
sched_switch_func(probe_data, __rq, prev, next);
}
static void
wakeup_func(void *private, void *__rq, struct task_struct *wakee, struct
task_struct *curr)
{
struct trace_array **ptr = private;
struct trace_array *tr = *ptr;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
if (!tracer_enabled)
return;
tracing_record_cmdline(curr);
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_wakeup_trace(tr, data, wakee, curr, flags);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static notrace void
wake_up_callback(void *probe_data, void *call_data,
const char *format, va_list *args)
{
struct task_struct *curr;
struct task_struct *task;
struct rq *__rq;
if (likely(!tracer_enabled))
return;
/* Skip pid %d state %ld */
(void)va_arg(*args, int);
(void)va_arg(*args, long);
/* now get the meat: "rq %p task %p rq->curr %p" */
__rq = va_arg(*args, typeof(__rq));
task = va_arg(*args, typeof(task));
curr = va_arg(*args, typeof(curr));
tracing_record_cmdline(task);
tracing_record_cmdline(curr);
wakeup_func(probe_data, __rq, task, curr);
}
static void sched_switch_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 int tracing_sched_register(void)
{
int ret;
ret = marker_probe_register("kernel_sched_wakeup",
"pid %d state %ld ## rq %p task %p rq->curr %p",
wake_up_callback,
&ctx_trace);
if (ret) {
pr_info("wakeup trace: Couldn't add marker"
" probe to kernel_sched_wakeup\n");
return ret;
}
ret = marker_probe_register("kernel_sched_wakeup_new",
"pid %d state %ld ## rq %p task %p rq->curr %p",
wake_up_callback,
&ctx_trace);
if (ret) {
pr_info("wakeup trace: Couldn't add marker"
" probe to kernel_sched_wakeup_new\n");
goto fail_deprobe;
}
ret = marker_probe_register("kernel_sched_schedule",
"prev_pid %d next_pid %d prev_state %ld "
"## rq %p prev %p next %p",
sched_switch_callback,
&ctx_trace);
if (ret) {
pr_info("sched trace: Couldn't add marker"
" probe to kernel_sched_schedule\n");
goto fail_deprobe_wake_new;
}
return ret;
fail_deprobe_wake_new:
marker_probe_unregister("kernel_sched_wakeup_new",
wake_up_callback,
&ctx_trace);
fail_deprobe:
marker_probe_unregister("kernel_sched_wakeup",
wake_up_callback,
&ctx_trace);
return ret;
}
static void tracing_sched_unregister(void)
{
marker_probe_unregister("kernel_sched_schedule",
sched_switch_callback,
&ctx_trace);
marker_probe_unregister("kernel_sched_wakeup_new",
wake_up_callback,
&ctx_trace);
marker_probe_unregister("kernel_sched_wakeup",
wake_up_callback,
&ctx_trace);
}
static void tracing_start_sched_switch(void)
{
long ref;
ref = atomic_inc_return(&sched_ref);
if (ref == 1)
tracing_sched_register();
}
static void tracing_stop_sched_switch(void)
{
long ref;
ref = atomic_dec_and_test(&sched_ref);
if (ref)
tracing_sched_unregister();
}
void tracing_start_cmdline_record(void)
{
tracing_start_sched_switch();
}
void tracing_stop_cmdline_record(void)
{
tracing_stop_sched_switch();
}
static void start_sched_trace(struct trace_array *tr)
{
sched_switch_reset(tr);
tracing_start_cmdline_record();
tracer_enabled = 1;
}
static void stop_sched_trace(struct trace_array *tr)
{
tracer_enabled = 0;
tracing_stop_cmdline_record();
}
static void sched_switch_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
if (tr->ctrl)
start_sched_trace(tr);
}
static void sched_switch_trace_reset(struct trace_array *tr)
{
if (tr->ctrl)
stop_sched_trace(tr);
}
static void sched_switch_trace_ctrl_update(struct trace_array *tr)
{
/* When starting a new trace, reset the buffers */
if (tr->ctrl)
start_sched_trace(tr);
else
stop_sched_trace(tr);
}
static struct tracer sched_switch_trace __read_mostly =
{
.name = "sched_switch",
.init = sched_switch_trace_init,
.reset = sched_switch_trace_reset,
.ctrl_update = sched_switch_trace_ctrl_update,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_sched_switch,
#endif
};
__init static int init_sched_switch_trace(void)
{
int ret = 0;
if (atomic_read(&sched_ref))
ret = tracing_sched_register();
if (ret) {
pr_info("error registering scheduler trace\n");
return ret;
}
return register_tracer(&sched_switch_trace);
}
device_initcall(init_sched_switch_trace);
