/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


#include <sys/dtrace.h>
#include <sys/systrace.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/atomic.h>

#define	SYSTRACE_ARTIFICIAL_FRAMES	1

#define	SYSTRACE_SHIFT			16
#define	SYSTRACE_ISENTRY(x)		((int)(x) >> SYSTRACE_SHIFT)
#define	SYSTRACE_SYSNUM(x)		((int)(x) & ((1 << SYSTRACE_SHIFT) - 1))
#define	SYSTRACE_ENTRY(id)		((1 << SYSTRACE_SHIFT) | (id))
#define	SYSTRACE_RETURN(id)		(id)

#if ((1 << SYSTRACE_SHIFT) <= NSYSCALL)
#error 1 << SYSTRACE_SHIFT must exceed number of system calls
#endif

static dev_info_t *systrace_devi;
static dtrace_provider_id_t systrace_id;

static void
systrace_init(struct sysent *actual, systrace_sysent_t **interposed)
{
	systrace_sysent_t *sysent = *interposed;
	int i;

	if (sysent == NULL) {
		*interposed = sysent = kmem_zalloc(sizeof (systrace_sysent_t) *
		    NSYSCALL, KM_SLEEP);
	}

	for (i = 0; i < NSYSCALL; i++) {
		struct sysent *a = &actual[i];
		systrace_sysent_t *s = &sysent[i];

		if (LOADABLE_SYSCALL(a) && !LOADED_SYSCALL(a))
			continue;

		if (a->sy_callc == dtrace_systrace_syscall)
			continue;

#ifdef _SYSCALL32_IMPL
		if (a->sy_callc == dtrace_systrace_syscall32)
			continue;
#endif

		s->stsy_underlying = a->sy_callc;
	}
}

/*ARGSUSED*/
static void
systrace_provide(void *arg, const dtrace_probedesc_t *desc)
{
	int i;

	if (desc != NULL)
		return;

	systrace_init(sysent, &systrace_sysent);
#ifdef _SYSCALL32_IMPL
	systrace_init(sysent32, &systrace_sysent32);
#endif

	for (i = 0; i < NSYSCALL; i++) {
		if (systrace_sysent[i].stsy_underlying == NULL)
			continue;

		if (dtrace_probe_lookup(systrace_id, NULL,
		    syscallnames[i], "entry") != 0)
			continue;

		(void) dtrace_probe_create(systrace_id, NULL, syscallnames[i],
		    "entry", SYSTRACE_ARTIFICIAL_FRAMES,
		    (void *)((uintptr_t)SYSTRACE_ENTRY(i)));
		(void) dtrace_probe_create(systrace_id, NULL, syscallnames[i],
		    "return", SYSTRACE_ARTIFICIAL_FRAMES,
		    (void *)((uintptr_t)SYSTRACE_RETURN(i)));

		systrace_sysent[i].stsy_entry = DTRACE_IDNONE;
		systrace_sysent[i].stsy_return = DTRACE_IDNONE;
#ifdef _SYSCALL32_IMPL
		systrace_sysent32[i].stsy_entry = DTRACE_IDNONE;
		systrace_sysent32[i].stsy_return = DTRACE_IDNONE;
#endif
	}
}

/*ARGSUSED*/
static void
systrace_destroy(void *arg, dtrace_id_t id, void *parg)
{
	int sysnum = SYSTRACE_SYSNUM((uintptr_t)parg);

	/*
	 * There's nothing to do here but assert that we have actually been
	 * disabled.
	 */
	if (SYSTRACE_ISENTRY((uintptr_t)parg)) {
		ASSERT(systrace_sysent[sysnum].stsy_entry == DTRACE_IDNONE);
#ifdef _SYSCALL32_IMPL
		ASSERT(systrace_sysent32[sysnum].stsy_entry == DTRACE_IDNONE);
#endif
	} else {
		ASSERT(systrace_sysent[sysnum].stsy_return == DTRACE_IDNONE);
#ifdef _SYSCALL32_IMPL
		ASSERT(systrace_sysent32[sysnum].stsy_return == DTRACE_IDNONE);
#endif
	}
}

/*ARGSUSED*/
static int
systrace_enable(void *arg, dtrace_id_t id, void *parg)
{
	int sysnum = SYSTRACE_SYSNUM((uintptr_t)parg);
	int enabled = (systrace_sysent[sysnum].stsy_entry != DTRACE_IDNONE ||
	    systrace_sysent[sysnum].stsy_return != DTRACE_IDNONE);

	if (SYSTRACE_ISENTRY((uintptr_t)parg)) {
		systrace_sysent[sysnum].stsy_entry = id;
#ifdef _SYSCALL32_IMPL
		systrace_sysent32[sysnum].stsy_entry = id;
#endif
	} else {
		systrace_sysent[sysnum].stsy_return = id;
#ifdef _SYSCALL32_IMPL
		systrace_sysent32[sysnum].stsy_return = id;
#endif
	}

	if (enabled) {
		ASSERT(sysent[sysnum].sy_callc == dtrace_systrace_syscall);
		return (0);
	}

	(void) atomic_cas_ptr(&sysent[sysnum].sy_callc,
	    (void *)systrace_sysent[sysnum].stsy_underlying,
	    (void *)dtrace_systrace_syscall);
#ifdef _SYSCALL32_IMPL
	(void) atomic_cas_ptr(&sysent32[sysnum].sy_callc,
	    (void *)systrace_sysent32[sysnum].stsy_underlying,
	    (void *)dtrace_systrace_syscall32);
#endif
	return (0);
}

/*ARGSUSED*/
static void
systrace_disable(void *arg, dtrace_id_t id, void *parg)
{
	int sysnum = SYSTRACE_SYSNUM((uintptr_t)parg);
	int disable = (systrace_sysent[sysnum].stsy_entry == DTRACE_IDNONE ||
	    systrace_sysent[sysnum].stsy_return == DTRACE_IDNONE);

	if (disable) {
		(void) atomic_cas_ptr(&sysent[sysnum].sy_callc,
		    (void *)dtrace_systrace_syscall,
		    (void *)systrace_sysent[sysnum].stsy_underlying);

#ifdef _SYSCALL32_IMPL
		(void) atomic_cas_ptr(&sysent32[sysnum].sy_callc,
		    (void *)dtrace_systrace_syscall32,
		    (void *)systrace_sysent32[sysnum].stsy_underlying);
#endif
	}

	if (SYSTRACE_ISENTRY((uintptr_t)parg)) {
		systrace_sysent[sysnum].stsy_entry = DTRACE_IDNONE;
#ifdef _SYSCALL32_IMPL
		systrace_sysent32[sysnum].stsy_entry = DTRACE_IDNONE;
#endif
	} else {
		systrace_sysent[sysnum].stsy_return = DTRACE_IDNONE;
#ifdef _SYSCALL32_IMPL
		systrace_sysent32[sysnum].stsy_return = DTRACE_IDNONE;
#endif
	}
}

static dtrace_pattr_t systrace_attr = {
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
};

static dtrace_pops_t systrace_pops = {
	systrace_provide,
	NULL,
	systrace_enable,
	systrace_disable,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	systrace_destroy
};

static int
systrace_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
	switch (cmd) {
	case DDI_ATTACH:
		break;
	case DDI_RESUME:
		return (DDI_SUCCESS);
	default:
		return (DDI_FAILURE);
	}

	systrace_probe = (void (*)())dtrace_probe;
	membar_enter();

	if (ddi_create_minor_node(devi, "systrace", S_IFCHR, 0,
	    DDI_PSEUDO, 0) == DDI_FAILURE ||
	    dtrace_register("syscall", &systrace_attr, DTRACE_PRIV_USER, NULL,
	    &systrace_pops, NULL, &systrace_id) != 0) {
		systrace_probe = systrace_stub;
		ddi_remove_minor_node(devi, NULL);
		return (DDI_FAILURE);
	}

	ddi_report_dev(devi);
	systrace_devi = devi;

	return (DDI_SUCCESS);
}

static int
systrace_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
{
	switch (cmd) {
	case DDI_DETACH:
		break;
	case DDI_SUSPEND:
		return (DDI_SUCCESS);
	default:
		return (DDI_FAILURE);
	}

	if (dtrace_unregister(systrace_id) != 0)
		return (DDI_FAILURE);

	ddi_remove_minor_node(devi, NULL);
	systrace_probe = systrace_stub;
	return (DDI_SUCCESS);
}

/*ARGSUSED*/
static int
systrace_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
{
	int error;

	switch (infocmd) {
	case DDI_INFO_DEVT2DEVINFO:
		*result = (void *)systrace_devi;
		error = DDI_SUCCESS;
		break;
	case DDI_INFO_DEVT2INSTANCE:
		*result = (void *)0;
		error = DDI_SUCCESS;
		break;
	default:
		error = DDI_FAILURE;
	}
	return (error);
}

/*ARGSUSED*/
static int
systrace_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
{
	return (0);
}

static struct cb_ops systrace_cb_ops = {
	systrace_open,		/* open */
	nodev,			/* close */
	nulldev,		/* strategy */
	nulldev,		/* print */
	nodev,			/* dump */
	nodev,			/* read */
	nodev,			/* write */
	nodev,			/* ioctl */
	nodev,			/* devmap */
	nodev,			/* mmap */
	nodev,			/* segmap */
	nochpoll,		/* poll */
	ddi_prop_op,		/* cb_prop_op */
	0,			/* streamtab  */
	D_NEW | D_MP		/* Driver compatibility flag */
};

static struct dev_ops systrace_ops = {
	DEVO_REV,		/* devo_rev, */
	0,			/* refcnt  */
	systrace_info,		/* get_dev_info */
	nulldev,		/* identify */
	nulldev,		/* probe */
	systrace_attach,	/* attach */
	systrace_detach,	/* detach */
	nodev,			/* reset */
	&systrace_cb_ops,	/* driver operations */
	NULL,			/* bus operations */
	nodev,			/* dev power */
	ddi_quiesce_not_needed,		/* quiesce */
};

/*
 * Module linkage information for the kernel.
 */
static struct modldrv modldrv = {
	&mod_driverops,		/* module type (this is a pseudo driver) */
	"System Call Tracing",	/* name of module */
	&systrace_ops,		/* driver ops */
};

static struct modlinkage modlinkage = {
	MODREV_1,
	(void *)&modldrv,
	NULL
};

int
_init(void)
{
	return (mod_install(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
	return (mod_info(&modlinkage, modinfop));
}

int
_fini(void)
{
	return (mod_remove(&modlinkage));
}