drivers/staging/lttng/lttng-syscalls.c - kernel/msm-4.9 - Gitiles

 /*
  * 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 "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

 #define PARAMS(args...)	args

 #undef TRACE_SYSTEM

 /* 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)
 #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 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);
 	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 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;
 	}
 }

 /* noinline to diminish caller stack size */
 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)
 {
 	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] = 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)
 {
 	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 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) {
 		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) {
 		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) {
 		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;
 }
	/*
	* 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 "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

	#define PARAMS(args...) args

	#undef TRACE_SYSTEM

	/* 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)
	#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 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);
	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 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;
	}
	}

	/* noinline to diminish caller stack size */
	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)
	{
	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] = 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)
	{
	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 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) {
	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) {
	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) {
	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;
	}