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

/*
 * lttng-syscalls.c
 *
 * Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * LTTng syscall 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 "lttng-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

#define PARAMS(args...)	args

/* Hijack probe callback for system calls */
#undef TP_PROBE_CB
#define TP_PROBE_CB(_template)		&syscall_entry_probe
#define SC_TRACE_EVENT(_name, _proto, _args, _struct, _assign, _printk)	\
	TRACE_EVENT(_name, PARAMS(_proto), PARAMS(_args),\
		PARAMS(_struct), PARAMS(_assign), PARAMS(_printk))
#define SC_DECLARE_EVENT_CLASS_NOARGS(_name, _struct, _assign, _printk)	\
	DECLARE_EVENT_CLASS_NOARGS(_name, PARAMS(_struct), PARAMS(_assign),\
		PARAMS(_printk))
#define SC_DEFINE_EVENT_NOARGS(_template, _name)			\
	DEFINE_EVENT_NOARGS(_template, _name)
#undef TRACE_SYSTEM
#define TRACE_SYSTEM syscalls_integers
#include "instrumentation/syscalls/headers/syscalls_integers.h"
#undef TRACE_SYSTEM
#define TRACE_SYSTEM syscalls_pointers
#include "instrumentation/syscalls/headers/syscalls_pointers.h"
#undef TRACE_SYSTEM
#undef SC_TRACE_EVENT
#undef SC_DECLARE_EVENT_CLASS_NOARGS
#undef SC_DEFINE_EVENT_NOARGS

#define TRACE_SYSTEM syscalls_unknown
#include "instrumentation/syscalls/headers/syscalls_unknown.h"
#undef TRACE_SYSTEM

/* For compat syscalls */
#undef _TRACE_SYSCALLS_integers_H
#undef _TRACE_SYSCALLS_pointers_H

/* Hijack probe callback for system calls */
#undef TP_PROBE_CB
#define TP_PROBE_CB(_template)		&syscall_entry_probe
#define SC_TRACE_EVENT(_name, _proto, _args, _struct, _assign, _printk)	\
	TRACE_EVENT(compat_##_name, PARAMS(_proto), PARAMS(_args),	\
		PARAMS(_struct), PARAMS(_assign),			\
		PARAMS(_printk))
#define SC_DECLARE_EVENT_CLASS_NOARGS(_name, _struct, _assign, _printk) \
	DECLARE_EVENT_CLASS_NOARGS(compat_##_name, PARAMS(_struct),	\
		PARAMS(_assign), PARAMS(_printk))
#define SC_DEFINE_EVENT_NOARGS(_template, _name)			\
	DEFINE_EVENT_NOARGS(compat_##_template, compat_##_name)
#define TRACE_SYSTEM compat_syscalls_integers
#include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
#undef TRACE_SYSTEM
#define TRACE_SYSTEM compat_syscalls_pointers
#include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
#undef TRACE_SYSTEM
#undef SC_TRACE_EVENT
#undef SC_DECLARE_EVENT_CLASS_NOARGS
#undef SC_DEFINE_EVENT_NOARGS
#undef TP_PROBE_CB

#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;
};

#define CREATE_SYSCALL_TABLE

#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,		\
	},

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

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

/* Create compatibility syscall table */
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 lttng_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);
	if (unlikely(is_compat_task()))
		__event_probe__compat_sys_unknown(event, id, args);
	else
		__event_probe__sys_unknown(event, id, args);
}

void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
{
	struct lttng_channel *chan = __data;
	struct lttng_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;
	}
}

/* noinline to diminish caller stack size */
static
int fill_table(const struct trace_syscall_entry *table, size_t table_len,
	struct lttng_event **chan_table, struct lttng_channel *chan, void *filter)
{
	const struct lttng_event_desc *desc;
	unsigned int i;

	/* Allocate events for each syscall, insert into table */
	for (i = 0; i < table_len; i++) {
		struct lttng_kernel_event ev;
		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] = lttng_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 lttng_channel *chan, void *filter)
{
	struct lttng_kernel_event ev;
	int ret;

	wrapper_vmalloc_sync_all();

	if (!chan->sc_table) {
		/* create syscall table mapping syscall to events */
		chan->sc_table = kzalloc(sizeof(struct lttng_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 lttng_event *)
					* ARRAY_SIZE(compat_sc_table), GFP_KERNEL);
		if (!chan->compat_sc_table)
			return -ENOMEM;
	}
#endif
	if (!chan->sc_unknown) {
		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 = lttng_event_create(chan, &ev, filter,
						    desc);
		if (!chan->sc_unknown) {
			return -EINVAL;
		}
	}

	if (!chan->sc_compat_unknown) {
		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 = lttng_event_create(chan, &ev, filter,
							   desc);
		if (!chan->sc_compat_unknown) {
			return -EINVAL;
		}
	}

	if (!chan->sc_exit) {
		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 = lttng_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 lttng_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;
	/* lttng_event destroy will be performed by lttng_session_destroy() */
	kfree(chan->sc_table);
#ifdef CONFIG_COMPAT
	kfree(chan->compat_sc_table);
#endif
	return 0;
}
Commit	Line	Data
	1	/*
	2	* lttng-syscalls.c
	3	*
	4	* Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	*
	6	* LTTng syscall probes.
	7	*
	8	* Dual LGPL v2.1/GPL v2 license.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/slab.h>
	13	#include <linux/compat.h>
	14	#include <asm/ptrace.h>
	15	#include <asm/syscall.h>
	16
	17	#include "lttng-events.h"
	18
	19	#ifndef CONFIG_COMPAT
	20	static inline int is_compat_task(void)
	21	{
	22	return 0;
	23	}
	24	#endif
	25
	26	static
	27	void syscall_entry_probe(void __data, struct pt_regs regs, long id);
	28
	29	/*
	30	* Take care of NOARGS not supported by mainline.
	31	*/
	32	#define DECLARE_EVENT_CLASS_NOARGS(name, tstruct, assign, print)
	33	#define DEFINE_EVENT_NOARGS(template, name)
	34	#define TRACE_EVENT_NOARGS(name, struct, assign, print)
	35
	36	/*
	37	* Create LTTng tracepoint probes.
	38	*/
	39	#define LTTNG_PACKAGE_BUILD
	40	#define CREATE_TRACE_POINTS
	41	#define TP_MODULE_OVERRIDE
	42	#define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers
	43
	44	#define PARAMS(args...) args
	45
	46	/* Hijack probe callback for system calls */
	47	#undef TP_PROBE_CB
	48	#define TP_PROBE_CB(_template) &syscall_entry_probe
	49	#define SC_TRACE_EVENT(_name, _proto, _args, _struct, _assign, _printk) \
	50	TRACE_EVENT(_name, PARAMS(_proto), PARAMS(_args),\
	51	PARAMS(_struct), PARAMS(_assign), PARAMS(_printk))
	52	#define SC_DECLARE_EVENT_CLASS_NOARGS(_name, _struct, _assign, _printk) \
	53	DECLARE_EVENT_CLASS_NOARGS(_name, PARAMS(_struct), PARAMS(_assign),\
	54	PARAMS(_printk))
	55	#define SC_DEFINE_EVENT_NOARGS(_template, _name) \
	56	DEFINE_EVENT_NOARGS(_template, _name)
	57	#undef TRACE_SYSTEM
	58	#define TRACE_SYSTEM syscalls_integers
	59	#include "instrumentation/syscalls/headers/syscalls_integers.h"
	60	#undef TRACE_SYSTEM
	61	#define TRACE_SYSTEM syscalls_pointers
	62	#include "instrumentation/syscalls/headers/syscalls_pointers.h"
	63	#undef TRACE_SYSTEM
	64	#undef SC_TRACE_EVENT
	65	#undef SC_DECLARE_EVENT_CLASS_NOARGS
	66	#undef SC_DEFINE_EVENT_NOARGS
	67
	68	#define TRACE_SYSTEM syscalls_unknown
	69	#include "instrumentation/syscalls/headers/syscalls_unknown.h"
	70	#undef TRACE_SYSTEM
	71
	72	/* For compat syscalls */
	73	#undef _TRACE_SYSCALLS_integers_H
	74	#undef _TRACE_SYSCALLS_pointers_H
	75
	76	/* Hijack probe callback for system calls */
	77	#undef TP_PROBE_CB
	78	#define TP_PROBE_CB(_template) &syscall_entry_probe
	79	#define SC_TRACE_EVENT(_name, _proto, _args, _struct, _assign, _printk) \
	80	TRACE_EVENT(compat_##_name, PARAMS(_proto), PARAMS(_args), \
	81	PARAMS(_struct), PARAMS(_assign), \
	82	PARAMS(_printk))
	83	#define SC_DECLARE_EVENT_CLASS_NOARGS(_name, _struct, _assign, _printk) \
	84	DECLARE_EVENT_CLASS_NOARGS(compat_##_name, PARAMS(_struct), \
	85	PARAMS(_assign), PARAMS(_printk))
	86	#define SC_DEFINE_EVENT_NOARGS(_template, _name) \
	87	DEFINE_EVENT_NOARGS(compat_##_template, compat_##_name)
	88	#define TRACE_SYSTEM compat_syscalls_integers
	89	#include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
	90	#undef TRACE_SYSTEM
	91	#define TRACE_SYSTEM compat_syscalls_pointers
	92	#include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
	93	#undef TRACE_SYSTEM
	94	#undef SC_TRACE_EVENT
	95	#undef SC_DECLARE_EVENT_CLASS_NOARGS
	96	#undef SC_DEFINE_EVENT_NOARGS
	97	#undef TP_PROBE_CB
	98
	99	#undef TP_MODULE_OVERRIDE
	100	#undef LTTNG_PACKAGE_BUILD
	101	#undef CREATE_TRACE_POINTS
	102
	103	struct trace_syscall_entry {
	104	void *func;
	105	const struct lttng_event_desc *desc;
	106	const struct lttng_event_field *fields;
	107	unsigned int nrargs;
	108	};
	109
	110	#define CREATE_SYSCALL_TABLE
	111
	112	#undef TRACE_SYSCALL_TABLE
	113	#define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs) \
	114	[ _nr ] = { \
	115	.func = __event_probe__##_template, \
	116	.nrargs = (_nrargs), \
	117	.fields = __event_fields___##_template, \
	118	.desc = &__event_desc___##_name, \
	119	},
	120
	121	static const struct trace_syscall_entry sc_table[] = {
	122	#include "instrumentation/syscalls/headers/syscalls_integers.h"
	123	#include "instrumentation/syscalls/headers/syscalls_pointers.h"
	124	};
	125
	126	#undef TRACE_SYSCALL_TABLE
	127	#define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs) \
	128	[ _nr ] = { \
	129	.func = __event_probe__##compat_##_template, \
	130	.nrargs = (_nrargs), \
	131	.fields = __event_fields___##compat_##_template,\
	132	.desc = &__event_desc___##compat_##_name, \
	133	},
	134
	135	/* Create compatibility syscall table */
	136	const struct trace_syscall_entry compat_sc_table[] = {
	137	#include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
	138	#include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
	139	};
	140
	141	#undef CREATE_SYSCALL_TABLE
	142
	143	static void syscall_entry_unknown(struct lttng_event *event,
	144	struct pt_regs *regs, unsigned int id)
	145	{
	146	unsigned long args[UNKNOWN_SYSCALL_NRARGS];
	147
	148	syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
	149	if (unlikely(is_compat_task()))
	150	__event_probe__compat_sys_unknown(event, id, args);
	151	else
	152	__event_probe__sys_unknown(event, id, args);
	153	}
	154
	155	void syscall_entry_probe(void __data, struct pt_regs regs, long id)
	156	{
	157	struct lttng_channel *chan = __data;
	158	struct lttng_event event, unknown_event;
	159	const struct trace_syscall_entry table, entry;
	160	size_t table_len;
	161
	162	if (unlikely(is_compat_task())) {
	163	table = compat_sc_table;
	164	table_len = ARRAY_SIZE(compat_sc_table);
	165	unknown_event = chan->sc_compat_unknown;
	166	} else {
	167	table = sc_table;
	168	table_len = ARRAY_SIZE(sc_table);
	169	unknown_event = chan->sc_unknown;
	170	}
	171	if (unlikely(id >= table_len)) {
	172	syscall_entry_unknown(unknown_event, regs, id);
	173	return;
	174	}
	175	if (unlikely(is_compat_task()))
	176	event = chan->compat_sc_table[id];
	177	else
	178	event = chan->sc_table[id];
	179	if (unlikely(!event)) {
	180	syscall_entry_unknown(unknown_event, regs, id);
	181	return;
	182	}
	183	entry = &table[id];
	184	WARN_ON_ONCE(!entry);
	185
	186	switch (entry->nrargs) {
	187	case 0:
	188	{
	189	void (fptr)(void __data) = entry->func;
	190
	191	fptr(event);
	192	break;
	193	}
	194	case 1:
	195	{
	196	void (fptr)(void __data, unsigned long arg0) = entry->func;
	197	unsigned long args[1];
	198
	199	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	200	fptr(event, args[0]);
	201	break;
	202	}
	203	case 2:
	204	{
	205	void (fptr)(void __data,
	206	unsigned long arg0,
	207	unsigned long arg1) = entry->func;
	208	unsigned long args[2];
	209
	210	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	211	fptr(event, args[0], args[1]);
	212	break;
	213	}
	214	case 3:
	215	{
	216	void (fptr)(void __data,
	217	unsigned long arg0,
	218	unsigned long arg1,
	219	unsigned long arg2) = entry->func;
	220	unsigned long args[3];
	221
	222	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	223	fptr(event, args[0], args[1], args[2]);
	224	break;
	225	}
	226	case 4:
	227	{
	228	void (fptr)(void __data,
	229	unsigned long arg0,
	230	unsigned long arg1,
	231	unsigned long arg2,
	232	unsigned long arg3) = entry->func;
	233	unsigned long args[4];
	234
	235	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	236	fptr(event, args[0], args[1], args[2], args[3]);
	237	break;
	238	}
	239	case 5:
	240	{
	241	void (fptr)(void __data,
	242	unsigned long arg0,
	243	unsigned long arg1,
	244	unsigned long arg2,
	245	unsigned long arg3,
	246	unsigned long arg4) = entry->func;
	247	unsigned long args[5];
	248
	249	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	250	fptr(event, args[0], args[1], args[2], args[3], args[4]);
	251	break;
	252	}
	253	case 6:
	254	{
	255	void (fptr)(void __data,
	256	unsigned long arg0,
	257	unsigned long arg1,
	258	unsigned long arg2,
	259	unsigned long arg3,
	260	unsigned long arg4,
	261	unsigned long arg5) = entry->func;
	262	unsigned long args[6];
	263
	264	syscall_get_arguments(current, regs, 0, entry->nrargs, args);
	265	fptr(event, args[0], args[1], args[2],
	266	args[3], args[4], args[5]);
	267	break;
	268	}
	269	default:
	270	break;
	271	}
	272	}
	273
	274	/* noinline to diminish caller stack size */
	275	static
	276	int fill_table(const struct trace_syscall_entry *table, size_t table_len,
	277	struct lttng_event *chan_table, struct lttng_channel chan, void *filter)
	278	{
	279	const struct lttng_event_desc *desc;
	280	unsigned int i;
	281
	282	/* Allocate events for each syscall, insert into table */
	283	for (i = 0; i < table_len; i++) {
	284	struct lttng_kernel_event ev;
	285	desc = table[i].desc;
	286
	287	if (!desc) {
	288	/* Unknown syscall */
	289	continue;
	290	}
	291	/*
	292	* Skip those already populated by previous failed
	293	* register for this channel.
	294	*/
	295	if (chan_table[i])
	296	continue;
	297	memset(&ev, 0, sizeof(ev));
	298	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	299	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	300	ev.instrumentation = LTTNG_KERNEL_NOOP;
	301	chan_table[i] = lttng_event_create(chan, &ev, filter,
	302	desc);
	303	if (!chan_table[i]) {
	304	/*
	305	* If something goes wrong in event registration
	306	* after the first one, we have no choice but to
	307	* leave the previous events in there, until
	308	* deleted by session teardown.
	309	*/
	310	return -EINVAL;
	311	}
	312	}
	313	return 0;
	314	}
	315
	316	int lttng_syscalls_register(struct lttng_channel chan, void filter)
	317	{
	318	struct lttng_kernel_event ev;
	319	int ret;
	320
	321	wrapper_vmalloc_sync_all();
	322
	323	if (!chan->sc_table) {
	324	/* create syscall table mapping syscall to events */
	325	chan->sc_table = kzalloc(sizeof(struct lttng_event *)
	326	* ARRAY_SIZE(sc_table), GFP_KERNEL);
	327	if (!chan->sc_table)
	328	return -ENOMEM;
	329	}
	330
	331	#ifdef CONFIG_COMPAT
	332	if (!chan->compat_sc_table) {
	333	/* create syscall table mapping compat syscall to events */
	334	chan->compat_sc_table = kzalloc(sizeof(struct lttng_event *)
	335	* ARRAY_SIZE(compat_sc_table), GFP_KERNEL);
	336	if (!chan->compat_sc_table)
	337	return -ENOMEM;
	338	}
	339	#endif
	340	if (!chan->sc_unknown) {
	341	const struct lttng_event_desc *desc =
	342	&__event_desc___sys_unknown;
	343
	344	memset(&ev, 0, sizeof(ev));
	345	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	346	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	347	ev.instrumentation = LTTNG_KERNEL_NOOP;
	348	chan->sc_unknown = lttng_event_create(chan, &ev, filter,
	349	desc);
	350	if (!chan->sc_unknown) {
	351	return -EINVAL;
	352	}
	353	}
	354
	355	if (!chan->sc_compat_unknown) {
	356	const struct lttng_event_desc *desc =
	357	&__event_desc___compat_sys_unknown;
	358
	359	memset(&ev, 0, sizeof(ev));
	360	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	361	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	362	ev.instrumentation = LTTNG_KERNEL_NOOP;
	363	chan->sc_compat_unknown = lttng_event_create(chan, &ev, filter,
	364	desc);
	365	if (!chan->sc_compat_unknown) {
	366	return -EINVAL;
	367	}
	368	}
	369
	370	if (!chan->sc_exit) {
	371	const struct lttng_event_desc *desc =
	372	&__event_desc___exit_syscall;
	373
	374	memset(&ev, 0, sizeof(ev));
	375	strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
	376	ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
	377	ev.instrumentation = LTTNG_KERNEL_NOOP;
	378	chan->sc_exit = lttng_event_create(chan, &ev, filter,
	379	desc);
	380	if (!chan->sc_exit) {
	381	return -EINVAL;
	382	}
	383	}
	384
	385	ret = fill_table(sc_table, ARRAY_SIZE(sc_table),
	386	chan->sc_table, chan, filter);
	387	if (ret)
	388	return ret;
	389	#ifdef CONFIG_COMPAT
	390	ret = fill_table(compat_sc_table, ARRAY_SIZE(compat_sc_table),
	391	chan->compat_sc_table, chan, filter);
	392	if (ret)
	393	return ret;
	394	#endif
	395	ret = tracepoint_probe_register("sys_enter",
	396	(void *) syscall_entry_probe, chan);
	397	if (ret)
	398	return ret;
	399	/*
	400	* We change the name of sys_exit tracepoint due to namespace
	401	* conflict with sys_exit syscall entry.
	402	*/
	403	ret = tracepoint_probe_register("sys_exit",
	404	(void *) __event_probe__exit_syscall,
	405	chan->sc_exit);
	406	if (ret) {
	407	WARN_ON_ONCE(tracepoint_probe_unregister("sys_enter",
	408	(void *) syscall_entry_probe, chan));
	409	}
	410	return ret;
	411	}
	412
	413	/*
	414	* Only called at session destruction.
	415	*/
	416	int lttng_syscalls_unregister(struct lttng_channel *chan)
	417	{
	418	int ret;
	419
	420	if (!chan->sc_table)
	421	return 0;
	422	ret = tracepoint_probe_unregister("sys_exit",
	423	(void *) __event_probe__exit_syscall,
	424	chan->sc_exit);
	425	if (ret)
	426	return ret;
	427	ret = tracepoint_probe_unregister("sys_enter",
	428	(void *) syscall_entry_probe, chan);
	429	if (ret)
	430	return ret;
	431	/* lttng_event destroy will be performed by lttng_session_destroy() */
	432	kfree(chan->sc_table);
	433	#ifdef CONFIG_COMPAT
	434	kfree(chan->compat_sc_table);
	435	#endif
	436	return 0;
	437	}