path: root/kernel/trace/trace_uprobe.c

// SPDX-License-Identifier: GPL-2.0
/*
 * uprobes-based tracing events
 *
 * Copyright (C) IBM Corporation, 2010-2012
 * Author:	Srikar Dronamraju <srikar@linux.vnet.ibm.com>
 */
#define pr_fmt(fmt)	"trace_uprobe: " fmt

#include <linux/security.h>
#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/uprobes.h>
#include <linux/namei.h>
#include <linux/string.h>
#include <linux/rculist.h>

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

#define UPROBE_EVENT_SYSTEM	"uprobes"

struct uprobe_trace_entry_head {
	struct trace_entry	ent;
	unsigned long		vaddr[];
};

#define SIZEOF_TRACE_ENTRY(is_return)			\
	(sizeof(struct uprobe_trace_entry_head) +	\
	 sizeof(unsigned long) * (is_return ? 2 : 1))

#define DATAOF_TRACE_ENTRY(entry, is_return)		\
	((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))

static int trace_uprobe_create(int argc, const char **argv);
static int trace_uprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_uprobe_release(struct dyn_event *ev);
static bool trace_uprobe_is_busy(struct dyn_event *ev);
static bool trace_uprobe_match(const char *system, const char *event,
			int argc, const char **argv, struct dyn_event *ev);

static struct dyn_event_operations trace_uprobe_ops = {
	.create = trace_uprobe_create,
	.show = trace_uprobe_show,
	.is_busy = trace_uprobe_is_busy,
	.free = trace_uprobe_release,
	.match = trace_uprobe_match,
};

/*
 * uprobe event core functions
 */
struct trace_uprobe {
	struct dyn_event		devent;
	struct uprobe_consumer		consumer;
	struct path			path;
	struct inode			*inode;
	char				*filename;
	unsigned long			offset;
	unsigned long			ref_ctr_offset;
	unsigned long			nhit;
	struct trace_probe		tp;
};

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

static struct trace_uprobe *to_trace_uprobe(struct dyn_event *ev)
{
	return container_of(ev, struct trace_uprobe, devent);
}

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

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

static int register_uprobe_event(struct trace_uprobe *tu);
static int unregister_uprobe_event(struct trace_uprobe *tu);

struct uprobe_dispatch_data {
	struct trace_uprobe	*tu;
	unsigned long		bp_addr;
};

static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
static int uretprobe_dispatcher(struct uprobe_consumer *con,
				unsigned long func, struct pt_regs *regs);

#ifdef CONFIG_STACK_GROWSUP
static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
{
	return addr - (n * sizeof(long));
}
#else
static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
{
	return addr + (n * sizeof(long));
}
#endif

static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
{
	unsigned long ret;
	unsigned long addr = user_stack_pointer(regs);

	addr = adjust_stack_addr(addr, n);

	if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
		return 0;

	return ret;
}

/*
 * Uprobes-specific fetch functions
 */
static nokprobe_inline int
probe_mem_read(void *dest, void *src, size_t size)
{
	void __user *vaddr = (void __force __user *)src;

	return copy_from_user(dest, vaddr, size) ? -EFAULT : 0;
}

static nokprobe_inline int
probe_mem_read_user(void *dest, void *src, size_t size)
{
	return probe_mem_read(dest, src, size);
}

/*
 * Fetch a null-terminated string. Caller MUST