diff --git a/sys/i386/ibcs2/ibcs2_fcntl.c b/sys/i386/ibcs2/ibcs2_fcntl.c
index 88c9c1d8c854..61c37cc81888 100644
--- a/sys/i386/ibcs2/ibcs2_fcntl.c
+++ b/sys/i386/ibcs2/ibcs2_fcntl.c
@@ -188,14 +188,17 @@ ibcs2_open(p, uap)
 			ret = spx_open(p, uap);
 	} else
 #endif /* SPX_HACK */
+	PROC_LOCK(p);
 	if (!ret && !noctty && SESS_LEADER(p) && !(p->p_flag & P_CONTROLT)) {
 		struct filedesc *fdp = p->p_fd;
 		struct file *fp = fdp->fd_ofiles[p->p_retval[0]];
 
+		PROC_UNLOCK(p);
 		/* ignore any error, just give it a try */
 		if (fp->f_type == DTYPE_VNODE)
 			fo_ioctl(fp, TIOCSCTTY, (caddr_t) 0, p);
-	}
+	} else
+		PROC_UNLOCK(p);
 	return ret;
 }
 
diff --git a/sys/i386/ibcs2/ibcs2_ioctl.c b/sys/i386/ibcs2/ibcs2_ioctl.c
index bc188f4b13ee..1350c1ac6160 100644
--- a/sys/i386/ibcs2/ibcs2_ioctl.c
+++ b/sys/i386/ibcs2/ibcs2_ioctl.c
@@ -499,8 +499,11 @@ ibcs2_ioctl(p, uap)
 		return ioctl(p, (struct ioctl_args *)uap);
 
 	case IBCS2_TIOCGPGRP:
-		return copyout((caddr_t)&p->p_pgrp->pg_id, SCARG(uap, data),
+		PROC_LOCK(p);
+		error = copyout((caddr_t)&p->p_pgrp->pg_id, SCARG(uap, data),
 				sizeof(p->p_pgrp->pg_id));
+		PROC_UNLOCK(p);
+		return error;
 
 	case IBCS2_TIOCSPGRP:	/* XXX - is uap->data a pointer to pgid? */
 	    {
@@ -526,6 +529,7 @@ ibcs2_ioctl(p, uap)
 		  short bitx, bity;
 	        } ibcs2_jwinsize;
 
+		PROC_LOCK(p);
                 ibcs2_jwinsize.bytex = 80;
 	          /* p->p_session->s_ttyp->t_winsize.ws_col; XXX */
 	        ibcs2_jwinsize.bytey = 25;
@@ -534,6 +538,7 @@ ibcs2_ioctl(p, uap)
 		  p->p_session->s_ttyp->t_winsize.ws_xpixel;
 	        ibcs2_jwinsize.bity =
 		  p->p_session->s_ttyp->t_winsize.ws_ypixel;
+		PROC_UNLOCK(p);
 	        return copyout((caddr_t)&ibcs2_jwinsize, SCARG(uap, data),
 			       sizeof(ibcs2_jwinsize));
 	     }
diff --git a/sys/i386/ibcs2/ibcs2_misc.c b/sys/i386/ibcs2/ibcs2_misc.c
index de67da470878..b53788fb9695 100644
--- a/sys/i386/ibcs2/ibcs2_misc.c
+++ b/sys/i386/ibcs2/ibcs2_misc.c
@@ -122,6 +122,7 @@ ibcs2_ulimit(p, uap)
 		return 0;
 #endif
 	case IBCS2_GETPSIZE:
+		mtx_assert(&Giant, MA_OWNED);
 		p->p_retval[0] = p->p_rlimit[RLIMIT_RSS].rlim_cur; /* XXX */
 		return 0;
 	case IBCS2_GETDTABLESIZE:
@@ -946,7 +947,9 @@ ibcs2_pgrpsys(p, uap)
 {
 	switch (SCARG(uap, type)) {
 	case 0:			/* getpgrp */
+		PROC_LOCK(p);
 		p->p_retval[0] = p->p_pgrp->pg_id;
+		PROC_UNLOCK(p);
 		return 0;
 
 	case 1:			/* setpgrp */
@@ -956,7 +959,9 @@ ibcs2_pgrpsys(p, uap)
 		SCARG(&sa, pid) = 0;
 		SCARG(&sa, pgid) = 0;
 		setpgid(p, &sa);
+		PROC_LOCK(p);
 		p->p_retval[0] = p->p_pgrp->pg_id;
+		PROC_UNLOCK(p);
 		return 0;
 	    }
 
diff --git a/sys/i386/ibcs2/ibcs2_other.c b/sys/i386/ibcs2/ibcs2_other.c
index 3578b3a07e5d..23b97436e270 100644
--- a/sys/i386/ibcs2/ibcs2_other.c
+++ b/sys/i386/ibcs2/ibcs2_other.c
@@ -48,7 +48,9 @@ ibcs2_secure(struct proc *p, struct ibcs2_secure_args *uap)
 	switch (uap->cmd) {
 
 	case IBCS2_SECURE_GETLUID:		/* get login uid */
+		PROC_LOCK(p);
 		p->p_retval[0] = p->p_ucred->cr_uid;
+		PROC_UNLOCK(p);
 		return 0;
 
 	case IBCS2_SECURE_SETLUID:		/* set login uid */
diff --git a/sys/i386/ibcs2/ibcs2_signal.c b/sys/i386/ibcs2/ibcs2_signal.c
index f8829f149760..70b5f57e4410 100644
--- a/sys/i386/ibcs2/ibcs2_signal.c
+++ b/sys/i386/ibcs2/ibcs2_signal.c
@@ -318,13 +318,16 @@ ibcs2_sigsys(p, uap)
 			p->p_retval[0] = (int)sa.sa_handler;
 
 			/* special sigset() check */
-                        if(IBCS2_SIGCALL(SCARG(uap, sig)) == IBCS2_SIGSET_MASK)
+                        if(IBCS2_SIGCALL(SCARG(uap, sig)) == IBCS2_SIGSET_MASK) {
+				PROC_LOCK(p);
 			        /* check to make sure signal is not blocked */
                                 if(sigismember(&p->p_sigmask, signum)) {
 				        /* return SIG_HOLD and unblock signal*/
                                         p->p_retval[0] = (int)IBCS2_SIG_HOLD;
 					SIGDELSET(p->p_sigmask, signum);
 				}
+				PROC_UNLOCK(p);
+			}
 				
 			return 0;
 		}
@@ -369,7 +372,9 @@ ibcs2_sigsys(p, uap)
 			sigset_t mask;
 			struct sigsuspend_args sa;
 
+			PROC_LOCK(p);
 			mask = p->p_sigmask;
+			PROC_UNLOCK(p);
 			SIGDELSET(mask, signum);
 			SCARG(&sa, sigmask) = &mask;
 			return sigsuspend(p, &sa);
@@ -391,7 +396,9 @@ ibcs2_sigprocmask(p, uap)
 
 	if (SCARG(uap, oset) != NULL) {
 		/* Fix the return value first if needed */
+		PROC_LOCK(p);
 		bsd_to_ibcs2_sigset(&p->p_sigmask, &iss);
+		PROC_UNLOCK(p);
 		if ((error = copyout(&iss, SCARG(uap, oset), sizeof(iss))) != 0)
 			return error;
 	}
@@ -405,7 +412,7 @@ ibcs2_sigprocmask(p, uap)
 
 	ibcs2_to_bsd_sigset(&iss, &bss);
 
-	(void) splhigh();
+	PROC_LOCK(p);
 
 	switch (SCARG(uap, how)) {
 	case IBCS2_SIG_BLOCK:
@@ -427,7 +434,7 @@ ibcs2_sigprocmask(p, uap)
 		break;
 	}
 
-	(void) spl0();
+	PROC_UNLOCK(p);
 
 	return error;
 }
@@ -440,8 +447,10 @@ ibcs2_sigpending(p, uap)
 	sigset_t bss;
 	ibcs2_sigset_t iss;
 
+	PROC_LOCK(p);
 	bss = p->p_siglist;
 	SIGSETAND(bss, p->p_sigmask);
+	PROC_UNLOCK(p);
 	bsd_to_ibcs2_sigset(&bss, &iss);
 
 	return copyout(&iss, SCARG(uap, mask), sizeof(iss));
@@ -473,7 +482,9 @@ ibcs2_pause(p, uap)
 	sigset_t mask;
 	struct sigsuspend_args sa;
 
+	PROC_LOCK(p);
 	mask = p->p_sigmask;
+	PROC_UNLOCK(p);
 	SCARG(&sa, sigmask) = &mask;
 	return sigsuspend(p, &sa);
 }
diff --git a/sys/i386/ibcs2/ibcs2_util.c b/sys/i386/ibcs2/ibcs2_util.c
index 0a361fd39f30..1d710be46881 100644
--- a/sys/i386/ibcs2/ibcs2_util.c
+++ b/sys/i386/ibcs2/ibcs2_util.c
@@ -62,6 +62,7 @@ ibcs2_emul_find(p, sgp, prefix, path, pbuf, cflag)
 	struct nameidata	 ndroot;
 	struct vattr		 vat;
 	struct vattr		 vatroot;
+	struct ucred		*uc;
 	int			 error;
 	char			*ptr, *buf, *cp;
 	size_t			 sz, len;
@@ -140,14 +141,20 @@ ibcs2_emul_find(p, sgp, prefix, path, pbuf, cflag)
 			return error;
 		}
 
-		if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) {
+		PROC_LOCK(p);
+		uc = p->p_ucred;
+		crhold(uc);
+		PROC_UNLOCK(p);
+		if ((error = VOP_GETATTR(nd.ni_vp, &vat, uc, p)) != 0) {
+			crfree(uc);
 			goto done;
 		}
 
-		if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
-		    != 0) {
+		if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, uc, p)) != 0) {
+			crfree(uc);
 			goto done;
 		}
+		crfree(uc);
 
 		if (vat.va_fsid == vatroot.va_fsid &&
 		    vat.va_fileid == vatroot.va_fileid) {