path: root/kernel/trace/trace_kprobe.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Kprobes-based tracing events
 *
 * Created by Masami Hiramatsu <mhiramat@redhat.com>
 *
 */
#define pr_fmt(fmt)	"trace_kprobe: " fmt

#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/rculist.h>
#include <linux/error-injection.h>

#include "trace_dynevent.h"
#include "trace_kprobe_selftest.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"

#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096

static int trace_kprobe_create(int argc, const char **argv);
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_kprobe_release(struct dyn_event *ev);
static bool trace_kprobe_is_busy(struct dyn_event *ev);
static bool trace_kprobe_match(const char *system, const char *event,
			       struct dyn_event *ev);

static struct dyn_event_operations trace_kprobe_ops = {
	.create = trace_kprobe_create,
	.show = trace_kprobe_show,
	.is_busy = trace_kprobe_is_busy,
	.free = trace_kprobe_release,
	.match = trace_kprobe_match,
};

/*
 * Kprobe event core functions
 */
struct trace_kprobe {
	struct dyn_event	devent;
	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
	unsigned long __percpu *nhit;
	const char		*symbol;	/* symbol name */
	struct trace_probe	tp;
};

static bool is_trace_kprobe(struct dyn_event *ev)
{
	return ev->ops == &trace_kprobe_ops;
}

static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
{
	return container_of(ev, struct trace_kprobe, devent);
}

/**
 * for_each_trace_kprobe - iterate over the trace_kprobe list
 * @pos:	the struct trace_kprobe * for each entry
 * @dpos:	the struct dyn_event * to use as a loop cursor
 */
#define for_each_trace_kprobe(pos, dpos)	\
	for_each_dyn_event(dpos)		\
		if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))

#define SIZEOF_TRACE_KPROBE(n)				\
	(offsetof(struct trace_kprobe, tp.args) +	\
	(sizeof(struct probe_arg) * (n)))

static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
{
	return tk->rp.handler != NULL;
}

static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
{
	return tk->symbol ? tk->symbol : "unknown";
}

static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
{
	return tk->rp.kp.offset;
}

static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
{
	return !!(kprobe_gone(&tk->rp.kp));
}

static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
						 struct module *mod)
{
	int len = strlen(mod->name);
	const char *name = trace_kprobe_symbol(tk);
	return strncmp(mod->name, name, len) == 0 && name[len] == ':';
}

static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
{
	char *p;
	bool ret;

	if (!tk->symbol)
		return false;
	p = strchr(tk->symbol, ':');
	if (!p)
		return true;
	*p = '\0';
	mutex_lock(&module_mutex);
	ret = !!find_module(tk->symbol);
	mutex_unlock(&module_mutex);
	*p = ':';

	return ret;
}

static bool trace_kprobe_is_busy(struct dyn_event *ev)
{
	struct trace_kprobe *tk = to_trace_kprobe(ev);

	return trace_probe_is_enabled(&tk->tp);
}

static bool trace_kprobe_match(const char *system, const char *event,
			       struct dyn_event *ev)
{
	struct trace_kprobe *tk = to_trace_kprobe(ev);

	return strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
	    (!system || strcmp(tk->tp.call.class->system, system) == 0);
}

static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
{
	unsigned long nhit = 0;
	int cpu;

	for_each_possible_cpu(cpu)
		nhit += *per_cpu_ptr(tk->nhit, cpu);

	return nhit;
}

/* Return 0 if it fails to find the symbol address */
static nokprobe_inline
unsigned long trace_kprobe_address(struct trace_kprobe *tk)
{
	unsigned long addr;

	if (tk->sy