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

/*
 * lttng-syscalls.c
 *
 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * LTTng sched probes.
 *
 * Dual LGPL v2.1/GPL v2 license.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/compat.h>
#include <asm/ptrace.h>
#include <asm/syscall.h>

#include "ltt-events.h"

#ifndef CONFIG_COMPAT
static inline int is_compat_task(void)
{
	return 0;
}
#endif

static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id);

/*
 * Take care of NOARGS not supported by mainline.
 */
#define DECLARE_EVENT_CLASS_NOARGS(name, tstruct, assign, print)
#define DEFINE_EVENT_NOARGS(template, name)
#define TRACE_EVENT_NOARGS(name, struct, assign, print)

/*
 * Create LTTng tracepoint probes.
 */
#define LTTNG_PACKAGE_BUILD
#define CREATE_TRACE_POINTS
#define TP_MODULE_OVERRIDE
#define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers

/* Hijack probe callback for system calls */
#define TP_PROBE_CB(_template)		&syscall_entry_probe
#include "instrumentation/syscalls/headers/syscalls_integers.h"
#include "instrumentation/syscalls/headers/syscalls_pointers.h"
#undef TP_PROBE_CB

#include "instrumentation/syscalls/headers/syscalls_unknown.h"

#undef TP_MODULE_OVERRIDE
#undef LTTNG_PACKAGE_BUILD
#undef CREATE_TRACE_POINTS

struct trace_syscall_entry {
	void *func;
	const struct lttng_event_desc *desc;
	const struct lttng_event_field *fields;
	unsigned int nrargs;
};

#undef TRACE_SYSCALL_TABLE
#define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)	\
	[ _nr ] = {						\
		.func = __event_probe__##_template,		\
		.nrargs = (_nrargs),				\
		.fields = __event_fields___##_template,		\
		.desc = &__event_desc___##_name,		\
	},

#define CREATE_SYSCALL_TABLE

static const struct trace_syscall_entry sc_table[] = {
#include "instrumentation/syscalls/headers/syscalls_integers.h"
#include "instrumentation/syscalls/headers/syscalls_pointers.h"
};

/* Create compatibility syscall table */
static const struct trace_syscall_entry compat_sc_table[] = {
#include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
#include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
};

#undef CREATE_SYSCALL_TABLE

static void syscall_entry_unknown(struct ltt_event *event,
	struct pt_regs *regs, unsigned int id)
{
	unsigned long args[UNKNOWN_SYSCALL_NRARGS];

	syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
	__event_probe__sys_unknown(event, id, args);
}

/*
 * Currently, given that the kernel syscall metadata extraction only
 * considers native system calls (not 32-bit compability ones), we
 * fall-back on the "unknown" system call tracing for 32-bit compat.
 */
static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
{
	struct ltt_channel *chan = __data;
	struct ltt_event *event, *unknown_event;
	const struct trace_syscall_entry *table, *entry;
	size_t table_len;

	if (unlikely(is_compat_task())) {
		table = compat_sc_table;
		table_len = ARRAY_SIZE(compat_sc_table);
		unknown_event = chan->sc_compat_unknown;
	} else {
		table = sc_table;
		table_len = ARRAY_SIZE(sc_table);
		unknown_event = chan->sc_unknown;
	}
	if (unlikely(id >= table_len)) {
		syscall_entry_unknown(unknown_event, regs, id);
		return;
	}
	if (unlikely(is_compat_task()))
		event = chan->compat_sc_table[id];
	else
		event = chan->sc_table[id];
	if (unlikely(!event)) {
		syscall_entry_unknown(unknown_event, regs, id);
		return;
	}
	entry = &table[id];
	WARN_ON_ONCE(!entry);

	switch (entry->nrargs) {
	case 0:
	{
		void (*fptr)(void *__data) = entry->func;

		fptr(event);
		break;
	}
	case 1:
	{
		void (*fptr)(void *__data, unsigned long arg0) = entry->func;
		unsigned long args[1];

		syscall_get_arguments(current, regs, 0, entry->nrargs, args);
		fptr(event, args[0]);
		break;
	}
	case 2:
	{
		void (*fptr)(void *__data,
			unsigned long arg0,
			unsigned long arg1) = entry->func;
		unsigned long args[2];

		syscall_get_arguments(current, regs, 0, entry->nrargs, args);
		fptr(event, args[0], args[1]);
		break;
	}
	case 3:
	{
		void (*fptr)(void *__data,
			unsigned long arg0,
			unsigned long arg1,
			unsigned long arg2) = entry->func;
		unsigned long args[3];

		syscall_get_arguments(current, regs, 0, entry->nrargs, args);
		fptr(event, args[0], args[1], args[2]);
		break;
	}
	case 4:
	{
		void (*fptr)(void *__data,
			unsigned long arg0,
			unsigned long arg1,
			unsigned long arg2,
			unsigned long arg3) = entry->func;
		unsigned long args[4];

		syscall_get_arguments(current, regs, 0, entry->nrargs, args);
		fptr(event, args[0], args[1], args[2], args[3]);
		break;
	}
	case 5:
	{
		void (*fptr)(void *__data,
			unsigned long arg0,
			unsigned long arg1,
			unsigned long arg2,
			unsigned long arg3,
			unsigned long arg4) = entry->func;
		unsigned long args[5];

		syscall_get_arguments(current, regs, 0, entry->nrargs, args);
		fptr(event, args[0], args[1], args[2], args[3], args[4]);
		break;
	}
	case 6:
	{
		void (*fptr)(void *__data,
			unsigned long arg0,
			unsigned long arg1,
			unsigned long arg2,
			unsigned long arg3,
			unsigned long arg4,
			unsigned long arg5) = entry->func;
		unsigned long args[6];

		syscall_get_arguments(current, regs, 0, entry->nrargs, args);
		fptr(event, args[0], args[1], args[2],
			args[3], args[4], args[5]);
		break;
	}
	default:
		break;
	}
}

static
int fill_table(const struct trace_syscall_entry *table, size_t table_len,
	struct ltt_event **chan_table, struct ltt_channel *chan, void *filter)
{
	unsigned int i;

	/* Allocate events for each syscall, insert into table */
	for (i = 0; i < table_len; i++) {
		struct lttng_kernel_event ev;
		const struct lttng_event_desc *desc = table[i].desc;

		if (!desc) {
			/* Unknown syscall */
			continue;
		}
		/*
		 * Skip those already populated by previous failed
		 * register for this channel.
		 */
		if (chan_table[i])
			continue;
		memset(&ev, 0, sizeof(ev));
		strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
		ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
		ev.instrumentation = LTTNG_KERNEL_NOOP;
		chan_table[i] = ltt_event_create(chan, &ev, filter,
						desc);
		if (!chan_table[i]) {
			/*
			 * If something goes wrong in event registration
			 * after the first one, we have no choice but to
			 * leave the previous events in there, until
			 * deleted by session teardown.
			 */
			return -EINVAL;
		}
	}
	return 0;
}

int lttng_syscalls_register(struct ltt_channel *chan, void *filter)
{
	int ret;

	wrapper_vmalloc_sync_all();

	if (!chan->sc_table) {
		/* create syscall table mapping syscall to events */
		chan->sc_table = kzalloc(sizeof(struct ltt_event *)
					* ARRAY_SIZE(sc_table), GFP_KERNEL);
		if (!chan->sc_table)
			return -ENOMEM;
	}

#ifdef CONFIG_COMPAT
	if (!chan->compat_sc_table) {
		/* create syscall table mapping compat syscall to events */
		chan->compat_sc_table = kzalloc(sizeof(struct ltt_event *)
					* ARRAY_SIZE(compat_sc_table), GFP_KERNEL);
		if (!chan->compat_sc_table)
			return -ENOMEM;
	}
#endif
	if (!chan->sc_unknown) {
		struct lttng_kernel_event ev;
		const struct lttng_event_desc *desc =
			&__event_desc___sys_unknown;

		memset(&ev, 0, sizeof(ev));
		strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
		ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
		ev.instrumentation = LTTNG_KERNEL_NOOP;
		chan->sc_unknown = ltt_event_create(chan, &ev, filter,
						    desc);
		if (!chan->sc_unknown) {
			return -EINVAL;
		}
	}

	if (!chan->sc_compat_unknown) {
		struct lttng_kernel_event ev;
		const struct lttng_event_desc *desc =
			&__event_desc___compat_sys_unknown;

		memset(&ev, 0, sizeof(ev));
		strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
		ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
		ev.instrumentation = LTTNG_KERNEL_NOOP;
		chan->sc_compat_unknown = ltt_event_create(chan, &ev, filter,
							   desc);
		if (!chan->sc_compat_unknown) {
			return -EINVAL;
		}
	}

	if (!chan->sc_exit) {
		struct lttng_kernel_event ev;
		const struct lttng_event_desc *desc =
			&__event_desc___exit_syscall;

		memset(&ev, 0, sizeof(ev));
		strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
		ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
		ev.instrumentation = LTTNG_KERNEL_NOOP;
		chan->sc_exit = ltt_event_create(chan, &ev, filter,
						 desc);
		if (!chan->sc_exit) {
			return -EINVAL;
		}
	}

	ret = fill_table(sc_table, ARRAY_SIZE(sc_table),
			chan->sc_table, chan, filter);
	if (ret)
		return ret;
#ifdef CONFIG_COMPAT
	ret = fill_table(compat_sc_table, ARRAY_SIZE(compat_sc_table),
			chan->compat_sc_table, chan, filter);
	if (ret)
		return ret;
#endif
	ret = tracepoint_probe_register("sys_enter",
			(void *) syscall_entry_probe, chan);
	if (ret)
		return ret;
	/*
	 * We change the name of sys_exit tracepoint due to namespace
	 * conflict with sys_exit syscall entry.
	 */
	ret = tracepoint_probe_register("sys_exit",
			(void *) __event_probe__exit_syscall,
			chan->sc_exit);
	if (ret) {
		WARN_ON_ONCE(tracepoint_probe_unregister("sys_enter",
			(void *) syscall_entry_probe, chan));
	}
	return ret;
}

/*
 * Only called at session destruction.
 */
int lttng_syscalls_unregister(struct ltt_channel *chan)
{
	int ret;

	if (!chan->sc_table)
		return 0;
	ret = tracepoint_probe_unregister("sys_exit",
			(void *) __event_probe__exit_syscall,
			chan->sc_exit);
	if (ret)
		return ret;
	ret = tracepoint_probe_unregister("sys_enter",
			(void *) syscall_entry_probe, chan);
	if (ret)
		return ret;
	/* ltt_event destroy will be performed by ltt_session_destroy() */
	kfree(chan->sc_table);
#ifdef CONFIG_COMPAT
	kfree(chan->compat_sc_table);
#endif
	return 0;
}
Commit	Line	Data
259b6cb3 MD	1	/*
	2	* lttng-syscalls.c
	3	*
	4	* Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	*
	6	* LTTng sched probes.
	7	*
	8	* Dual LGPL v2.1/GPL v2 license.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/slab.h>
6333ace3	13	#include <linux/compat.h>
259b6cb3 MD	14	#include <asm/ptrace.h>
	15	#include <asm/syscall.h>
	16
	17	#include "ltt-events.h"
	18
6333ace3 MD	19	#ifndef CONFIG_COMPAT
	20	static inline int is_compat_task(void)
	21	{
	22	return 0;
	23	}
	24	#endif
	25
259b6cb3 MD	26	static void syscall_entry_probe(void __data, struct pt_regs regs, long id);
259b6cb3 MD	27
f7bdf4db MD	28	/*
	29	* Take care of NOARGS not supported by mainline.
	30	*/
	31	#define DECLARE_EVENT_CLASS_NOARGS(name, tstruct, assign, print)
	32	#define DEFINE_EVENT_NOARGS(template, name)
	33	#define TRACE_EVENT_NOARGS(name, struct, assign, print)
	34
259b6cb3 MD	35	/*
	36	* Create LTTng tracepoint probes.
	37	*/
	38	#define LTTNG_PACKAGE_BUILD
	39	#define CREATE_TRACE_POINTS
2f804c0a MD	40	#define TP_MODULE_OVERRIDE
2f804c0a MD	41	#define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers
259b6cb3 MD	42
	43	/* Hijack probe callback for system calls */
	44	#define TP_PROBE_CB(_template) &syscall_entry_probe
177b3692 MD	45	#include "instrumentation/syscalls/headers/syscalls_integers.h"
177b3692 MD	46	#include "instrumentation/syscalls/headers/syscalls_pointers.h"
2f804c0a MD	47	#undef TP_PROBE_CB
2f804c0a MD	48
63728b02	49	#include "instrumentation/syscalls/headers/syscalls_unknown.h"
259b6cb3 MD	50
259b6cb3 MD	51	#undef TP_MODULE_OVERRIDE
259b6cb3 MD	52	#undef LTTNG_PACKAGE_BUILD
	53	#undef CREATE_TRACE_POINTS
	54
	55	struct trace_syscall_entry {
	56	void *func;
f7bdf4db	57	const struct lttng_event_desc *desc;
259b6cb3 MD	58	const struct lttng_event_field *fields;
	59	unsigned int nrargs;
	60	};
	61
259b6cb3	62	#undef TRACE_SYSCALL_TABLE
f7bdf4db	63	#define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs) \
259b6cb3	64	[ _nr ] = { \
f7bdf4db	65	.func = __event_probe__##_template, \
259b6cb3	66	.nrargs = (_nrargs), \
f7bdf4db MD	67	.fields = __event_fields___##_template, \
f7bdf4db MD	68	.desc = &__event_desc___##_name, \
259b6cb3 MD	69	},
259b6cb3 MD	70
49c50022 MD	71	#define CREATE_SYSCALL_TABLE
	72
	73	static const struct trace_syscall_entry sc_table[] = {
177b3692 MD	74	#include "instrumentation/syscalls/headers/syscalls_integers.h"
177b3692 MD	75	#include "instrumentation/syscalls/headers/syscalls_pointers.h"
259b6cb3 MD	76	};
259b6cb3 MD	77
49c50022 MD	78	/* Create compatibility syscall table */
	79	static const struct trace_syscall_entry compat_sc_table[] = {
	80	#include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
	81	#include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
	82	};
	83
259b6cb3 MD	84	#undef CREATE_SYSCALL_TABLE
259b6cb3 MD	85
b76dc1a0	86	static void syscall_entry_unknown(struct ltt_event *event,
f405cfce MD	87	struct pt_regs *regs, unsigned int id)
	88	{
	89	unsigned long args[UNKNOWN_SYSCALL_NRARGS];
f405cfce	90
f405cfce MD	91	syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
	92	__event_probe__sys_unknown(event, id, args);
	93	}
	94
6333ace3 MD	95	/*
	96	* Currently, given that the kernel syscall metadata extraction only
	97	* considers native system calls (not 32-bit compability ones), we
	98	* fall-back on the "unknown" system call tracing for 32-bit compat.
	99	*/
259b6cb3 MD	100	static void syscall_entry_probe(void __data, struct pt_regs regs, long id)
259b6cb3 MD	101	{
259b6cb3	102	struct ltt_channel *chan = __data;
49c50022 MD	103	struct ltt_event event, unknown_event;
	104	const struct trace_syscall_entry table, entry;
	105	size_t table_len;
259b6cb3	106
b76dc1a0	107	if (unlikely(is_compat_task())) {
49c50022 MD	108	table = compat_sc_table;
	109	table_len = ARRAY_SIZE(compat_sc_table);
	110	unknown_event = chan->sc_compat_unknown;
	111	} else {
	112	table = sc_table;
	113	table_len = ARRAY_SIZE(sc_table);
	114	unknown_event = chan->sc_unknown;
b76dc1a0	115	}
49c50022 MD	116	if (unlikely(id >= table_len)) {
49c50022 MD	117	syscall_entry_unknown(unknown_event, regs, id);
259b6cb3	118	return;
f405cfce	119	}
49c50022 MD	120	if (unlikely(is_compat_task()))
	121	event = chan->compat_sc_table[id];
	122	else
	123	event = chan->sc_table[id];
f405cfce	124	if (unlikely(!event)) {
49c50022	125	syscall_entry_unknown(unknown_event, regs, id);
f405cfce MD	126	return;
f405cfce MD	127	}
49c50022	128	entry = &table[id];
f405cfce	129	WARN_ON_ONCE(!entry);
259b6cb3 MD	130
	131	switch (entry->nrargs) {
	132	case 0:
	133	{
	134	void (fptr)(void __data) = entry->func;
	135
	136	fptr(event);
	137	break;
	138	}
	139	case 1:
	140	{
	141	void (fptr)(void __data, unsigned long arg0) = entry->func;
	142	unsigned long args[1];
	143
	144	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	145	fptr(event, args[0]);
	146	break;
	147	}
	148	case 2:
	149	{
	150	void (fptr)(void __data,
	151	unsigned long arg0,
	152	unsigned long arg1) = entry->func;
	153	unsigned long args[2];
	154
	155	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	156	fptr(event, args[0], args[1]);
	157	break;
	158	}
	159	case 3:
	160	{
	161	void (fptr)(void __data,
	162	unsigned long arg0,
	163	unsigned long arg1,
	164	unsigned long arg2) = entry->func;
	165	unsigned long args[3];
	166
	167	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	168	fptr(event, args[0], args[1], args[2]);
	169	break;
	170	}
	171	case 4:
	172	{
	173	void (fptr)(void __data,
	174	unsigned long arg0,
	175	unsigned long arg1,
	176	unsigned long arg2,
	177	unsigned long arg3) = entry->func;
	178	unsigned long args[4];
	179
	180	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	181	fptr(event, args[0], args[1], args[2], args[3]);
	182	break;
	183	}
	184	case 5:
	185	{
	186	void (fptr)(void __data,
	187	unsigned long arg0,
	188	unsigned long arg1,
	189	unsigned long arg2,
	190	unsigned long arg3,
	191	unsigned long arg4) = entry->func;
	192	unsigned long args[5];
	193
194	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
195	fptr(event, args[0], args[1], args[2], args[3], args[4]);
196	break;
197	}
198	case 6:
199	{
200	void (fptr)(void __data,
201	unsigned long arg0,
202	unsigned long arg1,
203	unsigned long arg2,
204	unsigned long arg3,
205	unsigned long arg4,
206	unsigned long arg5) = entry->func;
207	unsigned long args[6];
208
209	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
210	fptr(event, args[0], args[1], args[2],
211	args[3], args[4], args[5]);
212	break;
213	}
214	default:
215	break;
216	}
217	}
218
49c50022 MD	219	static
	220	int fill_table(const struct trace_syscall_entry *table, size_t table_len,
	221	struct ltt_event *chan_table, struct ltt_channel chan, void *filter)
259b6cb3 MD	222	{
259b6cb3 MD	223	unsigned int i;
49c50022 MD	224
	225	/* Allocate events for each syscall, insert into table */
	226	for (i = 0; i < table_len; i++) {
	227	struct lttng_kernel_event ev;
	228	const struct lttng_event_desc *desc = table[i].desc;
	229
	230	if (!desc) {
	231	/* Unknown syscall */
	232	continue;
	233	}
	234	/*
	235	* Skip those already populated by previous failed
	236	* register for this channel.
	237	*/
	238	if (chan_table[i])
	239	continue;
	240	memset(&ev, 0, sizeof(ev));
	241	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	242	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	243	ev.instrumentation = LTTNG_KERNEL_NOOP;
	244	chan_table[i] = ltt_event_create(chan, &ev, filter,
	245	desc);
	246	if (!chan_table[i]) {
	247	/*
	248	* If something goes wrong in event registration
	249	* after the first one, we have no choice but to
	250	* leave the previous events in there, until
	251	* deleted by session teardown.
	252	*/
	253	return -EINVAL;
	254	}
	255	}
	256	return 0;
	257	}
	258
	259	int lttng_syscalls_register(struct ltt_channel chan, void filter)
	260	{
259b6cb3 MD	261	int ret;
	262
	263	wrapper_vmalloc_sync_all();
259b6cb3 MD	264
	265	if (!chan->sc_table) {
	266	/* create syscall table mapping syscall to events */
	267	chan->sc_table = kzalloc(sizeof(struct ltt_event *)
	268	* ARRAY_SIZE(sc_table), GFP_KERNEL);
	269	if (!chan->sc_table)
	270	return -ENOMEM;
	271	}
	272
49c50022 MD	273	#ifdef CONFIG_COMPAT
	274	if (!chan->compat_sc_table) {
	275	/* create syscall table mapping compat syscall to events */
	276	chan->compat_sc_table = kzalloc(sizeof(struct ltt_event *)
	277	* ARRAY_SIZE(compat_sc_table), GFP_KERNEL);
	278	if (!chan->compat_sc_table)
	279	return -ENOMEM;
	280	}
	281	#endif
f405cfce MD	282	if (!chan->sc_unknown) {
f405cfce MD	283	struct lttng_kernel_event ev;
f405cfce MD	284	const struct lttng_event_desc *desc =
f405cfce MD	285	&__event_desc___sys_unknown;
2f804c0a	286
f405cfce MD	287	memset(&ev, 0, sizeof(ev));
	288	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	289	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	290	ev.instrumentation = LTTNG_KERNEL_NOOP;
	291	chan->sc_unknown = ltt_event_create(chan, &ev, filter,
	292	desc);
	293	if (!chan->sc_unknown) {
	294	return -EINVAL;
	295	}
	296	}
	297
b76dc1a0 MD	298	if (!chan->sc_compat_unknown) {
	299	struct lttng_kernel_event ev;
	300	const struct lttng_event_desc *desc =
	301	&__event_desc___compat_sys_unknown;
	302
	303	memset(&ev, 0, sizeof(ev));
	304	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	305	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	306	ev.instrumentation = LTTNG_KERNEL_NOOP;
	307	chan->sc_compat_unknown = ltt_event_create(chan, &ev, filter,
	308	desc);
	309	if (!chan->sc_compat_unknown) {
	310	return -EINVAL;
	311	}
	312	}
	313
2f804c0a MD	314	if (!chan->sc_exit) {
	315	struct lttng_kernel_event ev;
	316	const struct lttng_event_desc *desc =
	317	&__event_desc___exit_syscall;
	318
	319	memset(&ev, 0, sizeof(ev));
	320	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	321	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	322	ev.instrumentation = LTTNG_KERNEL_NOOP;
	323	chan->sc_exit = ltt_event_create(chan, &ev, filter,
	324	desc);
	325	if (!chan->sc_exit) {
	326	return -EINVAL;
	327	}
	328	}
	329
49c50022 MD	330	ret = fill_table(sc_table, ARRAY_SIZE(sc_table),
	331	chan->sc_table, chan, filter);
	332	if (ret)
	333	return ret;
	334	#ifdef CONFIG_COMPAT
	335	ret = fill_table(compat_sc_table, ARRAY_SIZE(compat_sc_table),
	336	chan->compat_sc_table, chan, filter);
	337	if (ret)
	338	return ret;
	339	#endif
259b6cb3 MD	340	ret = tracepoint_probe_register("sys_enter",
259b6cb3 MD	341	(void *) syscall_entry_probe, chan);
63728b02 MD	342	if (ret)
	343	return ret;
	344	/*
	345	* We change the name of sys_exit tracepoint due to namespace
	346	* conflict with sys_exit syscall entry.
	347	*/
	348	ret = tracepoint_probe_register("sys_exit",
2c01ec07	349	(void *) __event_probe__exit_syscall,
2f804c0a	350	chan->sc_exit);
63728b02 MD	351	if (ret) {
	352	WARN_ON_ONCE(tracepoint_probe_unregister("sys_enter",
	353	(void *) syscall_entry_probe, chan));
	354	}
259b6cb3 MD	355	return ret;
	356	}
	357
	358	/*
	359	* Only called at session destruction.
	360	*/
	361	int lttng_syscalls_unregister(struct ltt_channel *chan)
	362	{
	363	int ret;
	364
	365	if (!chan->sc_table)
	366	return 0;
63728b02	367	ret = tracepoint_probe_unregister("sys_exit",
2c01ec07	368	(void *) __event_probe__exit_syscall,
2f804c0a	369	chan->sc_exit);
63728b02 MD	370	if (ret)
63728b02 MD	371	return ret;
259b6cb3 MD	372	ret = tracepoint_probe_unregister("sys_enter",
	373	(void *) syscall_entry_probe, chan);
	374	if (ret)
	375	return ret;
	376	/* ltt_event destroy will be performed by ltt_session_destroy() */
	377	kfree(chan->sc_table);
49c50022 MD	378	#ifdef CONFIG_COMPAT
	379	kfree(chan->compat_sc_table);
	380	#endif
259b6cb3 MD	381	return 0;
259b6cb3 MD	382	}