1 files changed, 360 insertions, 0 deletions
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
new file mode 100644
index 00000000000..d0871bc0aca
--- /dev/null
+++ b/kernel/trace/trace_stack.c
@@ -0,0 +1,360 @@
+/*
+ * 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/sysctl.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+1] =
+	 { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
+static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
+
+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 DEFINE_MUTEX(stack_sysctl_mutex);
+
+int stack_tracer_enabled;
+static int last_stack_tracer_enabled;
+
+static inline void check_stack(void)
+{
+	unsigned long this_size, flags;
+	unsigned long *p, *top, *start;
+	int i;
+
+	this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
+	this_size = THREAD_SIZE - this_size;
+
+	if (this_size <= max_stack_size)
+		return;
+
+	/* we do not handle interrupt stacks yet */
+	if (!object_is_on_stack(&this_size))
+		return;
+
+	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		= 3;
+
+	save_stack_trace(&max_stack_trace);
+
+	/*
+	 * Now find where in the stack these are.
+	 */
+	i = 0;
+	start = &this_size;
+	top = (unsigned long *)
+		(((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
+
+	/*
+	 * Loop through all the entries. One of the entries may
+	 * for some reason be missed on the stack, so we may
+	 * have to account for them. If they are all there, this
+	 * loop will only happen once. This code only takes place
+	 * on a new max, so it is far from a fast path.
+	 */
+	while (i < max_stack_trace.nr_entries) {
+		int found = 0;
+
+		stack_dump_index[i] = this_size;
+		p = start;
+
+		for (; p < top && i < max_stack_trace.nr_entries; p++) {
+			if (*p == stack_dump_trace[i]) {
+				this_size = stack_dump_index[i++] =
+					(top - p) * sizeof(unsigned long);
+				found = 1;
+				/* Start the search from here */
+				start = p + 1;
+			}
+		}
+
+		if (!found)
+			i++;
+	}
+
+ out:
+	__raw_spin_unlock(&max_stack_lock);
+	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 = ftrace_preempt_disable();
+
+	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 */
+	ftrace_preempt_enable(resched);
+}
+
+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;
+
+	local_irq_save(flags);
+	__raw_spin_lock(&max_stack_lock);
+	*ptr = val;
+	__raw_spin_unlock(&max_stack_lock);
+	local_irq_restore(flags);
+
+	return count;
+}
+
+static const 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)
+{
+	long i;
+
+	(*pos)++;
+
+	if (v == SEQ_START_TOKEN)
+		i = 0;
+	else {
+		i = *(long *)v;
+		i++;
+	}
+
+	if (i >= max_stack_trace.nr_entries ||
+	    stack_dump_trace[i] == ULONG_MAX)
+		return NULL;
+
+	m->private = (void *)i;
+
+	return &m->private;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	void *t = SEQ_START_TOKEN;
+	loff_t l = 0;
+
+	local_irq_disable();
+	__raw_spin_lock(&max_stack_lock);
+
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	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, long i)
+{
+	unsigned long addr = stack_dump_trace[i];
+#ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
+
+	sprint_symbol(str, addr);
+
+	return seq_printf(m, "%s\n", str);
+#else
+	return seq_printf(m, "%p\n", (void*)addr);
+#endif
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	long i;
+	int size;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(m, "        Depth   Size      Location"
+			   "    (%d entries)\n"
+			   "        -----   ----      --------\n",
+			   max_stack_trace.nr_entries);
+		return 0;
+	}
+
+	i = *(long *)v;
+
+	if (i >= max_stack_trace.nr_entries ||
+	    stack_dump_trace[i] == ULONG_MAX)
+		return 0;
+
+	if (i+1 == max_stack_trace.nr_entries ||
+	    stack_dump_trace[i+1] == ULONG_MAX)
+		size = stack_dump_index[i];
+	else
+		size = stack_dump_index[i] - stack_dump_index[i+1];
+
+	seq_printf(m, "%3ld) %8d   %5d   ", i, stack_dump_index[i], size);
+
+	trace_lookup_stack(m, i);
+
+	return 0;
+}
+
+static const 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);
+
+	return ret;
+}
+
+static const struct file_operations stack_trace_fops = {
+	.open		= stack_trace_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+};
+
+int
+stack_trace_sysctl(struct ctl_table *table, int write,
+		   struct file *file, void __user *buffer, size_t *lenp,
+		   loff_t *ppos)
+{
+	int ret;
+
+	mutex_lock(&stack_sysctl_mutex);
+
+	ret = proc_dointvec(table, write, file, buffer, lenp, ppos);
+
+	if (ret || !write ||
+	    (last_stack_tracer_enabled == stack_tracer_enabled))
+		goto out;
+
+	last_stack_tracer_enabled = stack_tracer_enabled;
+
+	if (stack_tracer_enabled)
+		register_ftrace_function(&trace_ops);
+	else
+		unregister_ftrace_function(&trace_ops);
+
+ out:
+	mutex_unlock(&stack_sysctl_mutex);
+	return ret;
+}
+
+static __init int enable_stacktrace(char *str)
+{
+	stack_tracer_enabled = 1;
+	last_stack_tracer_enabled = 1;
+	return 1;
+}
+__setup("stacktrace", enable_stacktrace);
+
+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");
+
+	if (stack_tracer_enabled)
+		register_ftrace_function(&trace_ops);
+
+	return 0;
+}
+
+device_initcall(stack_trace_init);