trace.c

Kernel code of linux kernel

	entry = iter->ent;

	SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
	SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
	SEQ_PUT_HEX_FIELD_RET(s, entry->t);

	switch (entry->type) {
	case TRACE_FN:
		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.ip);
		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
		break;
	case TRACE_CTX:
	case TRACE_WAKE:
		S = entry->ctx.prev_state < sizeof(state_to_char) ?
			state_to_char[entry->ctx.prev_state] : 'X';
		T = entry->ctx.next_state < sizeof(state_to_char) ?
			state_to_char[entry->ctx.next_state] : 'X';
		if (entry->type == TRACE_WAKE)
			S = '+';
		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.prev_pid);
		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.prev_prio);
		SEQ_PUT_HEX_FIELD_RET(s, S);
		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.next_pid);
		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.next_prio);
		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
		SEQ_PUT_HEX_FIELD_RET(s, T);
		break;
	case TRACE_SPECIAL:
	case TRACE_STACK:
		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg1);
		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg2);
		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg3);
		break;
	}
	SEQ_PUT_FIELD_RET(s, newline);

	return 1;
}

static int print_bin_fmt(struct trace_iterator *iter)
{
	struct trace_seq *s = &iter->seq;
	struct trace_entry *entry;

	entry = iter->ent;

	SEQ_PUT_FIELD_RET(s, entry->pid);
	SEQ_PUT_FIELD_RET(s, entry->cpu);
	SEQ_PUT_FIELD_RET(s, entry->t);

	switch (entry->type) {
	case TRACE_FN:
		SEQ_PUT_FIELD_RET(s, entry->fn.ip);
		SEQ_PUT_FIELD_RET(s, entry->fn.parent_ip);
		break;
	case TRACE_CTX:
		SEQ_PUT_FIELD_RET(s, entry->ctx.prev_pid);
		SEQ_PUT_FIELD_RET(s, entry->ctx.prev_prio);
		SEQ_PUT_FIELD_RET(s, entry->ctx.prev_state);
		SEQ_PUT_FIELD_RET(s, entry->ctx.next_pid);
		SEQ_PUT_FIELD_RET(s, entry->ctx.next_prio);
		SEQ_PUT_FIELD_RET(s, entry->ctx.next_state);
		break;
	case TRACE_SPECIAL:
	case TRACE_STACK:
		SEQ_PUT_FIELD_RET(s, entry->special.arg1);
		SEQ_PUT_FIELD_RET(s, entry->special.arg2);
		SEQ_PUT_FIELD_RET(s, entry->special.arg3);
		break;
	}
	return 1;
}

static int trace_empty(struct trace_iterator *iter)
{
	struct trace_array_cpu *data;
	int cpu;

	for_each_tracing_cpu(cpu) {
		data = iter->tr->data[cpu];

		if (head_page(data) && data->trace_idx &&
		    (data->trace_tail != data->trace_head ||
		     data->trace_tail_idx != data->trace_head_idx))
			return 0;
	}
	return 1;
}

static int print_trace_line(struct trace_iterator *iter)
{
	if (iter->trace && iter->trace->print_line)
		return iter->trace->print_line(iter);

	if (trace_flags & TRACE_ITER_BIN)
		return print_bin_fmt(iter);

	if (trace_flags & TRACE_ITER_HEX)
		return print_hex_fmt(iter);

	if (trace_flags & TRACE_ITER_RAW)
		return print_raw_fmt(iter);

	if (iter->iter_flags & TRACE_FILE_LAT_FMT)
		return print_lat_fmt(iter, iter->idx, iter->cpu);

	return print_trace_fmt(iter);
}

static int s_show(struct seq_file *m, void *v)
{
	struct trace_iterator *iter = v;

	if (iter->ent == NULL) {
		if (iter->tr) {
			seq_printf(m, "# tracer: %s\n", iter->trace->name);
			seq_puts(m, "#\n");
		}
		if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
			/* print nothing if the buffers are empty */
			if (trace_empty(iter))
				return 0;
			print_trace_header(m, iter);
			if (!(trace_flags & TRACE_ITER_VERBOSE))
				print_lat_help_header(m);
		} else {
			if (!(trace_flags & TRACE_ITER_VERBOSE))
				print_func_help_header(m);
		}
	} else {
		print_trace_line(iter);
		trace_print_seq(m, &iter->seq);
	}

	return 0;
}

static struct seq_operations tracer_seq_ops = {
	.start		= s_start,
	.next		= s_next,
	.stop		= s_stop,
	.show		= s_show,
};

static struct trace_iterator *
__tracing_open(struct inode *inode, struct file *file, int *ret)
{
	struct trace_iterator *iter;

	if (tracing_disabled) {
		*ret = -ENODEV;
		return NULL;
	}

	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
	if (!iter) {
		*ret = -ENOMEM;
		goto out;
	}

	mutex_lock(&trace_types_lock);
	if (current_trace && current_trace->print_max)
		iter->tr = &max_tr;
	else
		iter->tr = inode->i_private;
	iter->trace = current_trace;
	iter->pos = -1;

	/* TODO stop tracer */
	*ret = seq_open(file, &tracer_seq_ops);
	if (!*ret) {
		struct seq_file *m = file->private_data;
		m->private = iter;

		/* stop the trace while dumping */
		if (iter->tr->ctrl) {
			tracer_enabled = 0;
			ftrace_function_enabled = 0;
		}

		if (iter->trace && iter->trace->open)
			iter->trace->open(iter);
	} else {
		kfree(iter);
		iter = NULL;
	}
	mutex_unlock(&trace_types_lock);

 out:
	return iter;
}

int tracing_open_generic(struct inode *inode, struct file *filp)
{
	if (tracing_disabled)
		return -ENODEV;

	filp->private_data = inode->i_private;
	return 0;
}

int tracing_release(struct inode *inode, struct file *file)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	struct trace_iterator *iter = m->private;

	mutex_lock(&trace_types_lock);
	if (iter->trace && iter->trace->close)
		iter->trace->close(iter);

	/* reenable tracing if it was previously enabled */
	if (iter->tr->ctrl) {
		tracer_enabled = 1;
		/*
		 * It is safe to enable function tracing even if it
		 * isn't used
		 */
		ftrace_function_enabled = 1;
	}
	mutex_unlock(&trace_types_lock);

	seq_release(inode, file);
	kfree(iter);
	return 0;
}

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

	__tracing_open(inode, file, &ret);

	return ret;
}

static int tracing_lt_open(struct inode *inode, struct file *file)
{
	struct trace_iterator *iter;
	int ret;

	iter = __tracing_open(inode, file, &ret);

	if (!ret)
		iter->iter_flags |= TRACE_FILE_LAT_FMT;

	return ret;
}


static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
	struct tracer *t = m->private;

	(*pos)++;

	if (t)
		t = t->next;

	m->private = t;

	return t;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
	struct tracer *t = m->private;
	loff_t l = 0;

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

	return t;
}

static void t_stop(struct seq_file *m, void *p)
{
	mutex_unlock(&trace_types_lock);
}

static int t_show(struct seq_file *m, void *v)
{
	struct tracer *t = v;

	if (!t)
		return 0;

	seq_printf(m, "%s", t->name);
	if (t->next)
		seq_putc(m, ' ');
	else
		seq_putc(m, '\n');

	return 0;
}

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

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

	if (tracing_disabled)
		return -ENODEV;

	ret = seq_open(file, &show_traces_seq_ops);
	if (!ret) {
		struct seq_file *m = file->private_data;
		m->private = trace_types;
	}

	return ret;
}

static struct file_operations tracing_fops = {
	.open		= tracing_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= tracing_release,
};

static struct file_operations tracing_lt_fops = {
	.open		= tracing_lt_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= tracing_release,
};

static struct file_operations show_traces_fops = {
	.open		= show_traces_open,
	.read		= seq_read,
	.release	= seq_release,
};

/*
 * Only trace on a CPU if the bitmask is set:
 */
static cpumask_t tracing_cpumask = CPU_MASK_ALL;

/*
 * When tracing/tracing_cpu_mask is modified then this holds
 * the new bitmask we are about to install:
 */
static cpumask_t tracing_cpumask_new;

/*
 * The tracer itself will not take this lock, but still we want
 * to provide a consistent cpumask to user-space:
 */
static DEFINE_MUTEX(tracing_cpumask_update_lock);

/*
 * Temporary storage for the character representation of the
 * CPU bitmask (and one more byte for the newline):
 */
static char mask_str[NR_CPUS + 1];

static ssize_t
tracing_cpumask_read(struct file *filp, char __user *ubuf,
		     size_t count, loff_t *ppos)
{
	int len;

	mutex_lock(&tracing_cpumask_update_lock);

	len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
	if (count - len < 2) {
		count = -EINVAL;
		goto out_err;
	}
	len += sprintf(mask_str + len, "\n");
	count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);

out_err:
	mutex_unlock(&tracing_cpumask_update_lock);

	return count;
}

static ssize_t
tracing_cpumask_write(struct file *filp, const char __user *ubuf,
		      size_t count, loff_t *ppos)
{
	int err, cpu;

	mutex_lock(&tracing_cpumask_update_lock);
	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
	if (err)
		goto err_unlock;

	raw_local_irq_disable();
	__raw_spin_lock(&ftrace_max_lock);
	for_each_tracing_cpu(cpu) {
		/*
		 * Increase/decrease the disabled counter if we are
		 * about to flip a bit in the cpumask:
		 */
		if (cpu_isset(cpu, tracing_cpumask) &&
				!cpu_isset(cpu, tracing_cpumask_new)) {
			atomic_inc(&global_trace.data[cpu]->disabled);
		}
		if (!cpu_isset(cpu, tracing_cpumask) &&
				cpu_isset(cpu, tracing_cpumask_new)) {
			atomic_dec(&global_trace.data[cpu]->disabled);
		}
	}
	__raw_spin_unlock(&ftrace_max_lock);
	raw_local_irq_enable();

	tracing_cpumask = tracing_cpumask_new;

	mutex_unlock(&tracing_cpumask_update_lock);

	return count;

err_unlock:
	mutex_unlock(&tracing_cpumask_update_lock);

	return err;
}

static struct file_operations tracing_cpumask_fops = {
	.open		= tracing_open_generic,
	.read		= tracing_cpumask_read,
	.write		= tracing_cpumask_write,
};

static ssize_t
tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
		       size_t cnt, loff_t *ppos)
{
	char *buf;
	int r = 0;
	int len = 0;
	int i;

	/* calulate max size */
	for (i = 0; trace_options[i]; i++) {
		len += strlen(trace_options[i]);
		len += 3; /* "no" and space */
	}

	/* +2 for \n and \0 */
	buf = kmalloc(len + 2, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	for (i = 0; trace_options[i]; i++) {
		if (trace_flags & (1 << i))
			r += sprintf(buf + r, "%s ", trace_options[i]);
		else
			r += sprintf(buf + r, "no%s ", trace_options[i]);
	}

	r += sprintf(buf + r, "\n");
	WARN_ON(r >= len + 2);

	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);

	kfree(buf);

	return r;
}

static ssize_t
tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf,
			size_t cnt, loff_t *ppos)
{
	char buf[64];
	char *cmp = buf;
	int neg = 0;
	int i;

	if (cnt >= sizeof(buf))
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, cnt))
		return -EFAULT;

	buf[cnt] = 0;

	if (strncmp(buf, "no", 2) == 0) {
		neg = 1;
		cmp += 2;
	}

	for (i = 0; trace_options[i]; i++) {
		int len = strlen(trace_options[i]);

		if (strncmp(cmp, trace_options[i], len) == 0) {
			if (neg)
				trace_flags &= ~(1 << i);
			else
				trace_flags |= (1 << i);
			break;
		}
	}
	/*
	 * If no option could be set, return an error:
	 */
	if (!trace_options[i])
		return -EINVAL;

	filp->f_pos += cnt;

	return cnt;
}

static struct file_operations tracing_iter_fops = {
	.open		= tracing_open_generic,
	.read		= tracing_iter_ctrl_read,
	.write		= tracing_iter_ctrl_write,
};

static const char readme_msg[] =
	"tracing mini-HOWTO:\n\n"
	"# mkdir /debug\n"
	"# mount -t debugfs nodev /debug\n\n"
	"# cat /debug/tracing/available_tracers\n"
	"wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
	"# cat /debug/tracing/current_tracer\n"
	"none\n"
	"# echo sched_switch > /debug/tracing/current_tracer\n"
	"# cat /debug/tracing/current_tracer\n"
	"sched_switch\n"
	"# cat /debug/tracing/iter_ctrl\n"
	"noprint-parent nosym-offset nosym-addr noverbose\n"
	"# echo print-parent > /debug/tracing/iter_ctrl\n"
	"# echo 1 > /debug/tracing/tracing_enabled\n"
	"# cat /debug/tracing/trace > /tmp/trace.txt\n"
	"echo 0 > /debug/tracing/tracing_enabled\n"
;

static ssize_t
tracing_readme_read(struct file *filp, char __user *ubuf,
		       size_t cnt, loff_t *ppos)
{
	return simple_read_from_buffer(ubuf, cnt, ppos,
					readme_msg, strlen(readme_msg));
}

static struct file_operations tracing_readme_fops = {
	.open		= tracing_open_generic,
	.read		= tracing_readme_read,
};

static ssize_t
tracing_ctrl_read(struct file *filp, char __user *ubuf,
		  size_t cnt, loff_t *ppos)
{
	struct trace_array *tr = filp->private_data;
	char buf[64];
	int r;

	r = sprintf(buf, "%ld\n", tr->ctrl);
	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static ssize_t
tracing_ctrl_write(struct file *filp, const char __user *ubuf,
		   size_t cnt, loff_t *ppos)
{
	struct trace_array *tr = filp->private_data;
	char buf[64];
	long val;
	int ret;