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/*
* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
*
*/
#include <linux/stacktrace.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include "trace.h"
#define STACK_TRACE_ENTRIES 500
static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES] =
{ [0 ... (STACK_TRACE_ENTRIES-1)] = ULONG_MAX };
static struct stack_trace max_stack_trace = {
.max_entries = STACK_TRACE_ENTRIES,
.entries = stack_dump_trace,
};
static unsigned long max_stack_size;
static raw_spinlock_t max_stack_lock =
(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
static int stack_trace_disabled __read_mostly;
static DEFINE_PER_CPU(int, trace_active);
static inline void check_stack(void)
{
unsigned long this_size;
unsigned long flags;
this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
this_size = THREAD_SIZE - this_size;
if (this_size <= max_stack_size)
return;
raw_local_irq_save(flags);
__raw_spin_lock(&max_stack_lock);
/* a race could have already updated it */
if (this_size <= max_stack_size)
goto out;
max_stack_size = this_size;
max_stack_trace.nr_entries = 0;
max_stack_trace.skip = 1;
save_stack_trace(&max_stack_trace);
out:
__raw_spin_unlock(&max_stack_lock);
raw_local_irq_restore(flags);
}
static void
stack_trace_call(unsigned long ip, unsigned long parent_ip)
{
int cpu, resched;
if (unlikely(!ftrace_enabled || stack_trace_disabled))
return;
resched = need_resched();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
/* no atomic needed, we only modify this variable by this cpu */
if (per_cpu(trace_active, cpu)++ != 0)
goto out;
check_stack();
out:
per_cpu(trace_active, cpu)--;
/* prevent recursion in schedule */
if (resched)
preempt_enable_no_resched_notrace();
else
preempt_enable_notrace();
}
static struct ftrace_ops trace_ops __read_mostly =
{
.func = stack_trace_call,
};
static ssize_t
stack_max_size_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
unsigned long *ptr = filp->private_data;
char buf[64];
int r;
r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
if (r > sizeof(buf))
r = sizeof(buf);
return simple_read_from_buffer(ubuf, count, ppos, buf, r);
}
static ssize_t
stack_max_size_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
long *ptr = filp->private_data;
unsigned long val, flags;
char buf[64];
int ret;
if (count >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, count))
return -EFAULT;
buf[count] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
raw_local_irq_save(flags);
__raw_spin_lock(&max_stack_lock);
*ptr = val;
__raw_spin_unlock(&max_stack_lock);
raw_local_irq_restore(flags);
return count;
}
static struct file_operations stack_max_size_fops = {
.open = tracing_open_generic,
.read = stack_max_size_read,
.write = stack_max_size_write,
};
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
unsigned long *t = m->private;
(*pos)++;
if (!t || *t == ULONG_MAX)
return NULL;
t++;
m->private = t;
return t;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
unsigned long *t = m->private;
loff_t l = 0;
local_irq_disable();
__raw_spin_lock(&max_stack_lock);
for (; t && l < *pos; t = t_next(m, t, &l))
;
return t;
}
static void t_stop(struct seq_file *m, void *p)
{
__raw_spin_unlock(&max_stack_lock);
local_irq_enable();
}
static int trace_lookup_stack(struct seq_file *m, unsigned long addr)
{
#ifdef CONFIG_KALLSYMS
char str[KSYM_SYMBOL_LEN];
sprint_symbol(str, addr);
return seq_printf(m, "[<%p>] %s\n", (void*)addr, str);
#else
return seq_printf(m, "%p\n", (void*)addr);
#endif
}
static int t_show(struct seq_file *m, void *v)
{
unsigned long *t = v;
if (!t || *t == ULONG_MAX)
return 0;
trace_lookup_stack(m, *t);
return 0;
}
static struct seq_operations stack_trace_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int stack_trace_open(struct inode *inode, struct file *file)
{
int ret;
ret = seq_open(file, &stack_trace_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = stack_dump_trace;
}
return ret;
}
static struct file_operations stack_trace_fops = {
.open = stack_trace_open,
.read = seq_read,
.llseek = seq_lseek,
};
static __init int stack_trace_init(void)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
entry = debugfs_create_file("stack_max_size", 0644, d_tracer,
&max_stack_size, &stack_max_size_fops);
if (!entry)
pr_warning("Could not create debugfs 'stack_max_size' entry\n");
entry = debugfs_create_file("stack_trace", 0444, d_tracer,
NULL, &stack_trace_fops);
if (!entry)
pr_warning("Could not create debugfs 'stack_trace' entry\n");
register_ftrace_function(&trace_ops);
return 0;
}
device_initcall(stack_trace_init);
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