[lttng-modules.git] / probes / lttng.c

/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
 *
 * lttng.c
 *
 * LTTng logger ABI
 *
 * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <linux/module.h>
#include <linux/tracepoint.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <wrapper/vmalloc.h>
#include <lttng-events.h>

#define TP_MODULE_NOAUTOLOAD
#define LTTNG_PACKAGE_BUILD
#define CREATE_TRACE_POINTS
#define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
#define TRACE_INCLUDE_FILE lttng
#define LTTNG_INSTRUMENTATION

#include <instrumentation/events/lttng-module/lttng.h>

/* Events written through logger are truncated at 1024 bytes */
#define LTTNG_LOGGER_COUNT_MAX	1024
#define LTTNG_LOGGER_FILE	"lttng-logger"

DEFINE_TRACE(lttng_logger);

static struct proc_dir_entry *lttng_logger_dentry;

/**
 * lttng_logger_write - write a userspace string into the trace system
 * @file: file pointer
 * @user_buf: user string
 * @count: length to copy
 * @ppos: file position
 *
 * Copy a userspace string into a trace event named "lttng:logger".
 * Copies at most @count bytes into the event "msg" dynamic array.
 * Truncates the count at LTTNG_LOGGER_COUNT_MAX. Returns the number of
 * bytes copied from the source.
 * Return -1 on error, with EFAULT errno.
 */
static
ssize_t lttng_logger_write(struct file *file, const char __user *user_buf,
		    size_t count, loff_t *ppos)
{
	int nr_pages = 1, i;
	unsigned long uaddr = (unsigned long) user_buf;
	struct page *pages[2];
	ssize_t written;
	int ret;

	/* Truncate count */
	if (unlikely(count > LTTNG_LOGGER_COUNT_MAX))
		count = LTTNG_LOGGER_COUNT_MAX;

	/* How many pages are we dealing with ? */
	if (unlikely((uaddr & PAGE_MASK) != ((uaddr + count) & PAGE_MASK)))
		nr_pages = 2;

	/* Pin userspace pages */
	ret = get_user_pages_fast(uaddr, nr_pages, 0, pages);
	if (unlikely(ret < nr_pages)) {
		if (ret > 0) {
			BUG_ON(ret != 1);
			put_page(pages[0]);
		}
		written = -EFAULT;
		goto end;
	}

	/* Trace the event */
	trace_lttng_logger(user_buf, count);
	written = count;
	*ppos += written;

	for (i = 0; i < nr_pages; i++)
		put_page(pages[i]);
end:
	return written;
}

static const struct file_operations lttng_logger_operations = {
	.write = lttng_logger_write,
};

static struct miscdevice logger_dev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "lttng-logger",
	.mode = 0666,
	.fops = &lttng_logger_operations
};

int __init lttng_logger_init(void)
{
	int ret = 0;

	wrapper_vmalloc_sync_all();

	/* /dev/lttng-logger */
	ret = misc_register(&logger_dev);
	if (ret) {
		printk(KERN_ERR "Error creating LTTng logger device\n");
		goto error;
	}

	/* /proc/lttng-logger */
	lttng_logger_dentry = proc_create_data(LTTNG_LOGGER_FILE,
				S_IRUGO | S_IWUGO, NULL,
				&lttng_logger_operations, NULL);
	if (!lttng_logger_dentry) {
		printk(KERN_ERR "Error creating LTTng logger proc file\n");
		ret = -ENOMEM;
		goto error_proc;
	}

	/* Init */
	ret = __lttng_events_init__lttng();
	if (ret)
		goto error_events;
	return ret;

error_events:
	remove_proc_entry("lttng-logger", NULL);
error_proc:
	misc_deregister(&logger_dev);
error:
	return ret;
}

void lttng_logger_exit(void)
{
	__lttng_events_exit__lttng();
	if (lttng_logger_dentry)
		remove_proc_entry("lttng-logger", NULL);
	misc_deregister(&logger_dev);
}
Commit	Line	Data
9f36eaed MJ	1	/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
9f36eaed MJ	2	*
0c956676 MD	3	* lttng.c
	4	*
	5	* LTTng logger ABI
	6	*
	7	* Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
0c956676 MD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/tracepoint.h>
	12	#include <linux/uaccess.h>
	13	#include <linux/gfp.h>
	14	#include <linux/fs.h>
	15	#include <linux/proc_fs.h>
	16	#include <linux/slab.h>
	17	#include <linux/mm.h>
4d328377	18	#include <linux/miscdevice.h>
156a3977 MD	19	#include <wrapper/vmalloc.h>
156a3977 MD	20	#include <lttng-events.h>
0c956676 MD	21
	22	#define TP_MODULE_NOAUTOLOAD
	23	#define LTTNG_PACKAGE_BUILD
	24	#define CREATE_TRACE_POINTS
c075712b	25	#define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
0c956676	26	#define TRACE_INCLUDE_FILE lttng
3bc29f0a	27	#define LTTNG_INSTRUMENTATION
0c956676	28
156a3977	29	#include <instrumentation/events/lttng-module/lttng.h>
0c956676 MD	30
	31	/* Events written through logger are truncated at 1024 bytes */
	32	#define LTTNG_LOGGER_COUNT_MAX 1024
	33	#define LTTNG_LOGGER_FILE "lttng-logger"
	34
20591cf7 MD	35	DEFINE_TRACE(lttng_logger);
20591cf7 MD	36
0c956676 MD	37	static struct proc_dir_entry *lttng_logger_dentry;
	38
	39	/**
	40	* lttng_logger_write - write a userspace string into the trace system
	41	* @file: file pointer
	42	* @user_buf: user string
	43	* @count: length to copy
	44	* @ppos: file position
	45	*
	46	* Copy a userspace string into a trace event named "lttng:logger".
	47	* Copies at most @count bytes into the event "msg" dynamic array.
	48	* Truncates the count at LTTNG_LOGGER_COUNT_MAX. Returns the number of
	49	* bytes copied from the source.
	50	* Return -1 on error, with EFAULT errno.
	51	*/
	52	static
	53	ssize_t lttng_logger_write(struct file file, const char __user user_buf,
	54	size_t count, loff_t *ppos)
	55	{
467f3a48	56	int nr_pages = 1, i;
0c956676 MD	57	unsigned long uaddr = (unsigned long) user_buf;
	58	struct page *pages[2];
	59	ssize_t written;
	60	int ret;
	61
	62	/* Truncate count */
	63	if (unlikely(count > LTTNG_LOGGER_COUNT_MAX))
	64	count = LTTNG_LOGGER_COUNT_MAX;
	65
	66	/* How many pages are we dealing with ? */
	67	if (unlikely((uaddr & PAGE_MASK) != ((uaddr + count) & PAGE_MASK)))
	68	nr_pages = 2;
	69
	70	/* Pin userspace pages */
	71	ret = get_user_pages_fast(uaddr, nr_pages, 0, pages);
	72	if (unlikely(ret < nr_pages)) {
	73	if (ret > 0) {
	74	BUG_ON(ret != 1);
	75	put_page(pages[0]);
	76	}
	77	written = -EFAULT;
	78	goto end;
	79	}
	80
	81	/* Trace the event */
	82	trace_lttng_logger(user_buf, count);
	83	written = count;
	84	*ppos += written;
	85
	86	for (i = 0; i < nr_pages; i++)
	87	put_page(pages[i]);
	88	end:
	89	return written;
	90	}
	91
	92	static const struct file_operations lttng_logger_operations = {
	93	.write = lttng_logger_write,
	94	};
	95
4d328377 SG	96	static struct miscdevice logger_dev = {
	97	.minor = MISC_DYNAMIC_MINOR,
	98	.name = "lttng-logger",
	99	.mode = 0666,
	100	.fops = &lttng_logger_operations
	101	};
	102
0c956676 MD	103	int __init lttng_logger_init(void)
	104	{
	105	int ret = 0;
	106
	107	wrapper_vmalloc_sync_all();
4d328377 SG	108
	109	/* /dev/lttng-logger */
	110	ret = misc_register(&logger_dev);
	111	if (ret) {
	112	printk(KERN_ERR "Error creating LTTng logger device\n");
	113	goto error;
	114	}
	115
	116	/* /proc/lttng-logger */
0c956676 MD	117	lttng_logger_dentry = proc_create_data(LTTNG_LOGGER_FILE,
	118	S_IRUGO \| S_IWUGO, NULL,
	119	&lttng_logger_operations, NULL);
	120	if (!lttng_logger_dentry) {
4d328377	121	printk(KERN_ERR "Error creating LTTng logger proc file\n");
0c956676	122	ret = -ENOMEM;
4d328377	123	goto error_proc;
0c956676	124	}
4d328377 SG	125
4d328377 SG	126	/* Init */
0c956676 MD	127	ret = __lttng_events_init__lttng();
	128	if (ret)
	129	goto error_events;
	130	return ret;
	131
	132	error_events:
	133	remove_proc_entry("lttng-logger", NULL);
4d328377 SG	134	error_proc:
4d328377 SG	135	misc_deregister(&logger_dev);
0c956676 MD	136	error:
	137	return ret;
	138	}
	139
32fe46fb	140	void lttng_logger_exit(void)
0c956676 MD	141	{
	142	__lttng_events_exit__lttng();
	143	if (lttng_logger_dentry)
	144	remove_proc_entry("lttng-logger", NULL);
4d328377	145	misc_deregister(&logger_dev);
0c956676	146	}