kernel/trace/trace_unlikely.c

/*
 * unlikely profiler
 *
 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
 */
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/hash.h>
#include <linux/fs.h>
#include <asm/local.h>
#include "trace.h"

void ftrace_likely_update(struct ftrace_likely_data *f, int val, int expect)
{
	/* FIXME: Make this atomic! */
	if (val == expect)
		f->correct++;
	else
		f->incorrect++;
}
EXPORT_SYMBOL(ftrace_likely_update);

struct ftrace_pointer {
	void		*start;
	void		*stop;
};

static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
	struct ftrace_pointer *f = m->private;
	struct ftrace_likely_data *p = v;

	(*pos)++;

	if (v == (void *)1)
		return f->start;

	++p;

	if ((void *)p >= (void *)f->stop)
		return NULL;

	return p;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
	void *t = (void *)1;
	loff_t l = 0;

	for (; t && l < *pos; t = t_next(m, t, &l))
		;

	return t;
}

static void t_stop(struct seq_file *m, void *p)
{
}

static int t_show(struct seq_file *m, void *v)
{
	struct ftrace_likely_data *p = v;
	const char *f;
	unsigned long percent;

	if (v == (void *)1) {
		seq_printf(m, " correct incorrect  %% "
			      "       Function                "
			      "  File              Line\n"
			      " ------- ---------  - "
			      "       --------                "
			      "  ----              ----\n");
		return 0;
	}

	/* Only print the file, not the path */
	f = p->file + strlen(p->file);
	while (f >= p->file && *f != '/')
		f--;
	f++;

	if (p->correct) {
		percent = p->incorrect * 100;
		percent /= p->correct + p->incorrect;
	} else
		percent = p->incorrect ? 100 : 0;

	seq_printf(m, "%8lu %8lu %3lu ", p->correct, p->incorrect, percent);
	seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
	return 0;
}

static struct seq_operations tracing_likely_seq_ops = {
	.start		= t_start,
	.next		= t_next,
	.stop		= t_stop,
	.show		= t_show,
};

static int tracing_likely_open(struct inode *inode, struct file *file)
{
	int ret;

	ret = seq_open(file, &tracing_likely_seq_ops);
	if (!ret) {
		struct seq_file *m = file->private_data;
		m->private = (void *)inode->i_private;
	}

	return ret;
}

static struct file_operations tracing_likely_fops = {
	.open		= tracing_likely_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
};

extern unsigned long __start_likely_profile[];
extern unsigned long __stop_likely_profile[];
extern unsigned long __start_unlikely_profile[];
extern unsigned long __stop_unlikely_profile[];

static struct ftrace_pointer ftrace_likely_pos = {
	.start			= __start_likely_profile,
	.stop			= __stop_likely_profile,
};

static struct ftrace_pointer ftrace_unlikely_pos = {
	.start			= __start_unlikely_profile,
	.stop			= __stop_unlikely_profile,
};

static __init int ftrace_unlikely_init(void)
{
	struct dentry *d_tracer;
	struct dentry *entry;

	d_tracer = tracing_init_dentry();

	entry = debugfs_create_file("profile_likely", 0444, d_tracer,
				    &ftrace_likely_pos,
				    &tracing_likely_fops);
	if (!entry)
		pr_warning("Could not create debugfs 'profile_likely' entry\n");

	entry = debugfs_create_file("profile_unlikely", 0444, d_tracer,
				    &ftrace_unlikely_pos,
				    &tracing_likely_fops);
	if (!entry)
		pr_warning("Could not create debugfs"
			   " 'profile_unlikely' entry\n");

	return 0;
}

device_initcall(ftrace_unlikely_init);