blob: 9587d3bcba556761de49854c95676a03a6dcecbf [file] [log] [blame]
/*
* trace stack traces
*
* Copyright (C) 2004-2008, Soeren Sandmann
* 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/irq.h>
#include <linux/fs.h>
#include <asm/stacktrace.h>
#include "trace.h"
static struct trace_array *sysprof_trace;
static int __read_mostly tracer_enabled;
/*
* 1 msec sample interval by default:
*/
static unsigned long sample_period = 1000000;
static const unsigned int sample_max_depth = 512;
static DEFINE_MUTEX(sample_timer_lock);
/*
* Per CPU hrtimers that do the profiling:
*/
static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer);
struct stack_frame {
const void __user *next_fp;
unsigned long return_address;
};
static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
{
int ret;
if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
return 0;
ret = 1;
pagefault_disable();
if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
ret = 0;
pagefault_enable();
return ret;
}
struct backtrace_info {
struct trace_array_cpu *data;
struct trace_array *tr;
int pos;
};
static void
backtrace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
/* Ignore warnings */
}
static void backtrace_warning(void *data, char *msg)
{
/* Ignore warnings */
}
static int backtrace_stack(void *data, char *name)
{
/* Don't bother with IRQ stacks for now */
return -1;
}
static void backtrace_address(void *data, unsigned long addr, int reliable)
{
struct backtrace_info *info = data;
if (info->pos < sample_max_depth && reliable) {
__trace_special(info->tr, info->data, 1, addr, 0);
info->pos++;
}
}
const static struct stacktrace_ops backtrace_ops = {
.warning = backtrace_warning,
.warning_symbol = backtrace_warning_symbol,
.stack = backtrace_stack,
.address = backtrace_address,
};
static int
trace_kernel(struct pt_regs *regs, struct trace_array *tr,
struct trace_array_cpu *data)
{
struct backtrace_info info;
unsigned long bp;
char *stack;
info.tr = tr;
info.data = data;
info.pos = 1;
__trace_special(info.tr, info.data, 1, regs->ip, 0);
stack = ((char *)regs + sizeof(struct pt_regs));
#ifdef CONFIG_FRAME_POINTER
bp = regs->bp;
#else
bp = 0;
#endif
dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, &info);
return info.pos;
}
static void timer_notify(struct pt_regs *regs, int cpu)
{
struct trace_array_cpu *data;
struct stack_frame frame;
struct trace_array *tr;
const void __user *fp;
int is_user;
int i;
if (!regs)
return;
tr = sysprof_trace;
data = tr->data[cpu];
is_user = user_mode(regs);
if (!current || current->pid == 0)
return;
if (is_user && current->state != TASK_RUNNING)
return;
__trace_special(tr, data, 0, 0, current->pid);
if (!is_user)
i = trace_kernel(regs, tr, data);
else
i = 0;
/*
* Trace user stack if we are not a kernel thread
*/
if (current->mm && i < sample_max_depth) {
regs = (struct pt_regs *)current->thread.sp0 - 1;
fp = (void __user *)regs->bp;
__trace_special(tr, data, 2, regs->ip, 0);
while (i < sample_max_depth) {
frame.next_fp = NULL;
frame.return_address = 0;
if (!copy_stack_frame(fp, &frame))
break;
if ((unsigned long)fp < regs->sp)
break;
__trace_special(tr, data, 2, frame.return_address,
(unsigned long)fp);
fp = frame.next_fp;
i++;
}
}
/*
* Special trace entry if we overflow the max depth:
*/
if (i == sample_max_depth)
__trace_special(tr, data, -1, -1, -1);
__trace_special(tr, data, 3, current->pid, i);
}
static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer)
{
/* trace here */
timer_notify(get_irq_regs(), smp_processor_id());
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_PERCPU;
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);
}
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);
}
static void stop_stack_timers(void)
{
int cpu;
for_each_online_cpu(cpu)
stop_stack_timer(cpu);
}
static void stack_reset(struct trace_array *tr)
{
int cpu;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
}
static void start_stack_trace(struct trace_array *tr)
{
mutex_lock(&sample_timer_lock);
stack_reset(tr);
start_stack_timers();
tracer_enabled = 1;
mutex_unlock(&sample_timer_lock);
}
static void stop_stack_trace(struct trace_array *tr)
{
mutex_lock(&sample_timer_lock);
stop_stack_timers();
tracer_enabled = 0;
mutex_unlock(&sample_timer_lock);
}
static void stack_trace_init(struct trace_array *tr)
{
sysprof_trace = tr;
if (tr->ctrl)
start_stack_trace(tr);
}
static 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_sysprof,
#endif
};
__init static int init_stack_trace(void)
{
return register_tracer(&stack_trace);
}
device_initcall(init_stack_trace);
#define MAX_LONG_DIGITS 22
static ssize_t
sysprof_sample_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[MAX_LONG_DIGITS];
int r;
r = sprintf(buf, "%ld\n", nsecs_to_usecs(sample_period));
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
sysprof_sample_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[MAX_LONG_DIGITS];
unsigned long val;
if (cnt > MAX_LONG_DIGITS-1)
cnt = MAX_LONG_DIGITS-1;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
val = simple_strtoul(buf, NULL, 10);
/*
* Enforce a minimum sample period of 100 usecs:
*/
if (val < 100)
val = 100;
mutex_lock(&sample_timer_lock);
stop_stack_timers();
sample_period = val * 1000;
start_stack_timers();
mutex_unlock(&sample_timer_lock);
return cnt;
}
static struct file_operations sysprof_sample_fops = {
.read = sysprof_sample_read,
.write = sysprof_sample_write,
};
void init_tracer_sysprof_debugfs(struct dentry *d_tracer)
{
struct dentry *entry;
entry = debugfs_create_file("sysprof_sample_period", 0644,
d_tracer, NULL, &sysprof_sample_fops);
if (entry)
return;
pr_warning("Could not create debugfs 'dyn_ftrace_total_info' entry\n");
}