fasttrap.c

Sun Solaris 10 中的 DTrace 组件的源代码。请参看: http://www.sun.com/software/solaris/observability.jsp

static void *
fasttrap_meta_provide(void *arg, dtrace_helper_provdesc_t *dhpv, pid_t pid)
{
	fasttrap_provider_t *provider;

	/*
	 * A 32-bit unsigned integer (like a pid for example) can be
	 * expressed in 10 or fewer decimal digits. Make sure that we'll
	 * have enough space for the provider name.
	 */
	if (strlen(dhpv->dthpv_provname) + 10 >=
	    sizeof (provider->ftp_name)) {
		cmn_err(CE_WARN, "failed to instantiate provider %s: "
		    "name too long to accomodate pid", dhpv->dthpv_provname);
		return (NULL);
	}

	/*
	 * Don't let folks spoof the true pid provider.
	 */
	if (strcmp(dhpv->dthpv_provname, FASTTRAP_PID_NAME) == 0) {
		cmn_err(CE_WARN, "failed to instantiate provider %s: "
		    "%s is an invalid name", dhpv->dthpv_provname,
		    FASTTRAP_PID_NAME);
		return (NULL);
	}

	/*
	 * The highest stability class that fasttrap supports is ISA; cap
	 * the stability of the new provider accordingly.
	 */
	if (dhpv->dthpv_pattr.dtpa_provider.dtat_class >= DTRACE_CLASS_COMMON)
		dhpv->dthpv_pattr.dtpa_provider.dtat_class = DTRACE_CLASS_ISA;
	if (dhpv->dthpv_pattr.dtpa_mod.dtat_class >= DTRACE_CLASS_COMMON)
		dhpv->dthpv_pattr.dtpa_mod.dtat_class = DTRACE_CLASS_ISA;
	if (dhpv->dthpv_pattr.dtpa_func.dtat_class >= DTRACE_CLASS_COMMON)
		dhpv->dthpv_pattr.dtpa_func.dtat_class = DTRACE_CLASS_ISA;
	if (dhpv->dthpv_pattr.dtpa_name.dtat_class >= DTRACE_CLASS_COMMON)
		dhpv->dthpv_pattr.dtpa_name.dtat_class = DTRACE_CLASS_ISA;
	if (dhpv->dthpv_pattr.dtpa_args.dtat_class >= DTRACE_CLASS_COMMON)
		dhpv->dthpv_pattr.dtpa_args.dtat_class = DTRACE_CLASS_ISA;

	if ((provider = fasttrap_provider_lookup(pid, dhpv->dthpv_provname,
	    &dhpv->dthpv_pattr)) == NULL) {
		cmn_err(CE_WARN, "failed to instantiate provider %s for "
		    "process %u",  dhpv->dthpv_provname, (uint_t)pid);
		return (NULL);
	}

	/*
	 * We elevate the consumer count here to ensure that this provider
	 * isn't removed until after the meta provider has been told to
	 * remove it.
	 */
	provider->ftp_ccount++;

	mutex_exit(&provider->ftp_mtx);

	return (provider);
}

/*ARGSUSED*/
static void
fasttrap_meta_create_probe(void *arg, void *parg,
    dtrace_helper_probedesc_t *dhpb)
{
	fasttrap_provider_t *provider = parg;
	fasttrap_probe_t *pp;
	fasttrap_tracepoint_t *tp;
	size_t size;
	int i;

	mutex_enter(&provider->ftp_mtx);

	if (dtrace_probe_lookup(provider->ftp_provid, dhpb->dthpb_mod,
	    dhpb->dthpb_func, dhpb->dthpb_name) != 0) {
		mutex_exit(&provider->ftp_mtx);
		return;
	}

	atomic_add_32(&fasttrap_total, dhpb->dthpb_noffs);

	if (fasttrap_total > fasttrap_max) {
		atomic_add_32(&fasttrap_total, -dhpb->dthpb_noffs);
		mutex_exit(&provider->ftp_mtx);
		return;
	}

	size = sizeof (fasttrap_probe_t) +
	    sizeof (pp->ftp_tps[0]) * (dhpb->dthpb_noffs - 1);
	pp = kmem_zalloc(size, KM_SLEEP);

	pp->ftp_prov = provider;
	pp->ftp_pid = provider->ftp_pid;
	pp->ftp_ntps = dhpb->dthpb_noffs;
#ifdef __sparc
	pp->ftp_type = DTFTP_POST_OFFSETS;
#else
	pp->ftp_type = DTFTP_OFFSETS;
#endif
	pp->ftp_nargs = dhpb->dthpb_xargc;
	pp->ftp_xtypes = dhpb->dthpb_xtypes;
	pp->ftp_ntypes = dhpb->dthpb_ntypes;

	for (i = 0; i < pp->ftp_ntps; i++) {
		tp = kmem_zalloc(sizeof (fasttrap_tracepoint_t), KM_SLEEP);

		tp->ftt_prov = provider;
		tp->ftt_pc = dhpb->dthpb_base + dhpb->dthpb_offs[i];
		tp->ftt_pid = provider->ftp_pid;

		pp->ftp_tps[i].fit_tp = tp;
		pp->ftp_tps[i].fit_id.fti_probe = pp;
	}

	/*
	 * If the arguments are shuffled around we set the argument remapping
	 * table. Later, when the probe fires, we only remap the arguments
	 * if the table is non-NULL.
	 */
	for (i = 0; i < dhpb->dthpb_xargc; i++) {
		if (dhpb->dthpb_args[i] != i) {
			pp->ftp_argmap = dhpb->dthpb_args;
			break;
		}
	}

	/*
	 * The probe is fully constructed -- register it with DTrace.
	 */
	pp->ftp_id = dtrace_probe_create(provider->ftp_provid, dhpb->dthpb_mod,
	    dhpb->dthpb_func, dhpb->dthpb_name, FASTTRAP_OFFSET_AFRAMES, pp);

	mutex_exit(&provider->ftp_mtx);
}

/*ARGSUSED*/
static void
fasttrap_meta_remove(void *arg, dtrace_helper_provdesc_t *dhpv, pid_t pid)
{
	fasttrap_provider_t *provider;

	if ((provider = fasttrap_provider_lookup(pid,
	    dhpv->dthpv_provname, NULL)) != NULL) {
		/*
		 * Drop the consumer count now that we're done with this
		 * provider. If there are no other consumers retire it now.
		 */
		if (--provider->ftp_ccount == 0)
			fasttrap_provider_retire(provider);
		else
			mutex_exit(&provider->ftp_mtx);
	}
}

static dtrace_mops_t fasttrap_mops = {
	fasttrap_meta_create_probe,
	fasttrap_meta_provide,
	fasttrap_meta_remove
};

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

/*ARGSUSED*/
static int
fasttrap_ioctl(dev_t dev, int cmd, intptr_t arg, int md, cred_t *cr, int *rv)
{
	if (!dtrace_attached())
		return (EAGAIN);

	if (cmd == FASTTRAPIOC_MAKEPROBE) {
		fasttrap_probe_spec_t *uprobe = (void *)arg;
		fasttrap_probe_spec_t *probe;
		uint64_t noffs;
		size_t size;
		int ret;
		char *c;

		if (copyin(&uprobe->ftps_noffs, &noffs,
		    sizeof (uprobe->ftps_noffs)))
			return (EFAULT);

		/*
		 * Probes must have at least one tracepoint.
		 */
		if (noffs == 0)
			return (EINVAL);

		size = sizeof (fasttrap_probe_spec_t) +
		    sizeof (probe->ftps_offs[0]) * (noffs - 1);

		if (size > 1024 * 1024)
			return (ENOMEM);

		probe = kmem_alloc(size, KM_SLEEP);

		if (copyin(uprobe, probe, size) != 0) {
			kmem_free(probe, size);
			return (EFAULT);
		}

		/*
		 * Verify that the function and module strings contain no
		 * funny characters.
		 */
		for (c = &probe->ftps_func[0]; *c != '\0'; c++) {
			if (*c < 0x20 || 0x7f <= *c) {
				ret = EINVAL;
				goto err;
			}
		}

		for (c = &probe->ftps_mod[0]; *c != '\0'; c++) {
			if (*c < 0x20 || 0x7f <= *c) {
				ret = EINVAL;
				goto err;
			}
		}

		if (!PRIV_POLICY_CHOICE(cr, PRIV_ALL, B_FALSE)) {
			proc_t *p;
			pid_t pid = probe->ftps_pid;

			mutex_enter(&pidlock);
			/*
			 * Report an error if the process doesn't exist
			 * or is actively being birthed.
			 */
			if ((p = prfind(pid)) == NULL || p->p_stat == SIDL) {
				mutex_exit(&pidlock);
				return (ESRCH);
			}
			mutex_enter(&p->p_lock);
			mutex_exit(&pidlock);

			if ((ret = priv_proc_cred_perm(cr, p, NULL,
			    VREAD | VWRITE)) != 0) {
				mutex_exit(&p->p_lock);
				return (ret);
			}

			mutex_exit(&p->p_lock);
		}

		ret = fasttrap_add_probe(probe);
err:
		kmem_free(probe, size);

		return (ret);

	} else if (cmd == FASTTRAPIOC_GETINSTR) {
		fasttrap_instr_query_t instr;
		fasttrap_tracepoint_t *tp;
		uint_t index;
		int ret;

		if (copyin((void *)arg, &instr, sizeof (instr)) != 0)
			return (EFAULT);

		if (!PRIV_POLICY_CHOICE(cr, PRIV_ALL, B_FALSE)) {
			proc_t *p;
			pid_t pid = instr.ftiq_pid;

			mutex_enter(&pidlock);
			/*
			 * Report an error if the process doesn't exist
			 * or is actively being birthed.
			 */
			if ((p = prfind(pid)) == NULL || p->p_stat == SIDL) {
				mutex_exit(&pidlock);
				return (ESRCH);
			}
			mutex_enter(&p->p_lock);
			mutex_exit(&pidlock);

			if ((ret = priv_proc_cred_perm(cr, p, NULL,
			    VREAD)) != 0) {
				mutex_exit(&p->p_lock);
				return (ret);
			}

			mutex_exit(&p->p_lock);
		}

		index = FASTTRAP_TPOINTS_INDEX(instr.ftiq_pid, instr.ftiq_pc);

		mutex_enter(&fasttrap_tpoints.fth_table[index].ftb_mtx);
		tp = fasttrap_tpoints.fth_table[index].ftb_data;
		while (tp != NULL) {
			if (instr.ftiq_pid == tp->ftt_pid &&
			    instr.ftiq_pc == tp->ftt_pc &&
			    !tp->ftt_prov->ftp_defunct)
				break;

			tp = tp->ftt_next;
		}

		if (tp == NULL) {
			mutex_exit(&fasttrap_tpoints.fth_table[index].ftb_mtx);
			return (ENOENT);
		}

		bcopy(&tp->ftt_instr, &instr.ftiq_instr,
		    sizeof (instr.ftiq_instr));
		mutex_exit(&fasttrap_tpoints.fth_table[index].ftb_mtx);

		if (copyout(&instr, (void *)arg, sizeof (instr)) != 0)
			return (EFAULT);

		return (0);
	}

	return (EINVAL);
}

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

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

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

static int
fasttrap_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
	ulong_t nent;

	switch (cmd) {
	case DDI_ATTACH:
		break;
	case DDI_RESUME:
		return (DDI_SUCCESS);
	default:
		return (DDI_FAILURE);
	}

	if (ddi_create_minor_node(devi, "fasttrap", S_IFCHR, 0,
	    DDI_PSEUDO, NULL) == DDI_FAILURE ||
	    dtrace_register("fasttrap", &fasttrap_attr, DTRACE_PRIV_USER, 0,
	    &fasttrap_pops, NULL, &fasttrap_id) != 0) {
		ddi_remove_minor_node(devi, NULL);
		return (DDI_FAILURE);
	}

	ddi_report_dev(devi);
	fasttrap_devi = devi;

	/*
	 * Install our hooks into fork(2), exec(2), and exit(2).
	 */
	dtrace_fasttrap_fork_ptr = &fasttrap_fork;
	dtrace_fasttrap_exit_ptr = &fasttrap_exec_exit;
	dtrace_fasttrap_exec_ptr = &fasttrap_exec_exit;

	fasttrap_max = ddi_getprop(DDI_DEV_T_ANY, devi, DDI_PROP_DONTPASS,
	    "fasttrap-max-probes", FASTTRAP_MAX_DEFAULT);
	fasttrap_total = 0;

	/*
	 * Conjure up the tracepoints hashtable...
	 */
	nent = ddi_getprop(DDI_DEV_T_ANY, devi, DDI_PROP_DONTPASS,
	    "fasttrap-hash-size", FASTTRAP_TPOINTS_DEFAULT_SIZE);

	if (nent <= 0 || nent > 0x1000000)
		nent = FASTTRAP_TPOINTS_DEFAULT_SIZE;

	if ((nent & (nent - 1)) == 0)
		fasttrap_tpoints.fth_nent = nent;
	else
		fasttrap_tpoints.fth_nent = 1 << fasttrap_highbit(nent);
	ASSERT(fasttrap_tpoints.fth_nent > 0);
	fasttrap_tpoints.fth_mask = fasttrap_tpoints.fth_nent - 1;
	fasttrap_tpoints.fth_table = kmem_zalloc(fasttrap_tpoints.fth_nent *
	    sizeof (fasttrap_bucket_t), KM_SLEEP);

	/*
	 * ... and the providers hash table.
	 */
	nent = FASTTRAP_PROVIDERS_DEFAULT_SIZE;
	if ((nent & (nent - 1)) == 0)
		fasttrap_provs.fth_nent = nent;
	else
		fasttrap_provs.fth_nent = 1 << fasttrap_highbit(nent);
	ASSERT(fasttrap_provs.fth_nent > 0);
	fasttrap_provs.fth_mask = fasttrap_provs.fth_nent - 1;

	fasttrap_provs.fth_table = kmem_zalloc(fasttrap_provs.fth_nent *
	    sizeof (fasttrap_bucket_t), KM_SLEEP);

	(void) dtrace_meta_register("fasttrap", &fasttrap_mops, NULL,
	    &fasttrap_meta_id);

	return (DDI_SUCCESS);
}

static int
fasttrap_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
{
	int i, fail = 0;
	timeout_id_t tmp;

	switch (cmd) {
	case DDI_DETACH:
		break;
	case DDI_SUSPEND:
		return (DDI_SUCCESS);
	default:
		return (DDI_FAILURE);
	}

	/*
	 * Unregister the meta-provider to make sure no new fasttrap-
	 * managed providers come along while we're trying to close up
	 * shop. If we fail to detach, we'll need to re-register as a
	 * meta-provider. We can fail to unregister as a meta-provider
	 * if providers we manage still exist.
	 */
	if (fasttrap_meta_id != DTRACE_METAPROVNONE &&
	    dtrace_meta_unregister(fasttrap_meta_id) != 0)
		return (DDI_FAILURE);

	/*
	 * Prevent any new timeouts from running by setting fasttrap_timeout
	 * to a non-zero value, and wait for the current timeout to complete.
	 */
	mutex_enter(&fasttrap_cleanup_mtx);
	fasttrap_cleanup_work = 0;

	while (fasttrap_timeout != (timeout_id_t)1) {
		tmp = fasttrap_timeout;
		fasttrap_timeout = (timeout_id_t)1;

		if (tmp != 0) {
			mutex_exit(&fasttrap_cleanup_mtx);
			(void) untimeout(tmp);
			mutex_enter(&fasttrap_cleanup_mtx);
		}
	}

	fasttrap_cleanup_work = 0;
	mutex_exit(&fasttrap_cleanup_mtx);

	/*
	 * Iterate over all of our providers. If there's still a process
	 * that corresponds to that pid, fail to detach.
	 */
	for (i = 0; i < fasttrap_provs.fth_nent; i++) {
		fasttrap_provider_t **fpp, *fp;
		fasttrap_bucket_t *bucket = &fasttrap_provs.fth_table[i];