Support detailed syscalls with 0 arguments

[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 <asm/ptrace.h>
#include <asm/syscall.h>

#include "ltt-events.h"

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

/* Hijack probe callback for system calls */
#define TP_PROBE_CB(_template)		&syscall_entry_probe
#define TP_MODULE_OVERRIDE

#define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers

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

#undef TP_MODULE_OVERRIDE
#undef TP_PROBE_CB
#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;
};

static int sc_table_desc_filled;

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

#undef CREATE_SYSCALL_TABLE

static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
{
	struct trace_syscall_entry *entry;
	struct ltt_channel *chan = __data;
	struct ltt_event *event;

	if (unlikely(id >= ARRAY_SIZE(sc_table)))
		return;
	entry = &sc_table[id];
	if (unlikely(!entry->func))
		return;
	event = chan->sc_table[id];
	WARN_ON_ONCE(!event);

	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;
	}
}

int lttng_syscalls_register(struct ltt_channel *chan, void *filter)
{
	unsigned int i;
	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;
	}

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

		if (!desc)
			continue;
		/*
		 * Skip those already populated by previous failed
		 * register for this channel.
		 */
		if (chan->sc_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->sc_table[i] = ltt_event_create(chan, &ev, filter,
						     desc);
		if (!chan->sc_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;
		}
	}
	ret = tracepoint_probe_register("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_enter",
			(void *) syscall_entry_probe, chan);
	if (ret)
		return ret;
	/* ltt_event destroy will be performed by ltt_session_destroy() */
	kfree(chan->sc_table);
	return 0;
}