Split the per-process Local Descriptor Table out of the PCB and into

struct mdproc.

Submitted by:	Andrew R. Reiter <arr@watson.org>
Silence on:	-current

17 files changed, 215 insertions, 172 deletions

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 55d4c0d..d63afbd 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -246,7 +246,8 @@ sw1b:
 	/* XXX FIXME: we should be restoring the local APIC TPR */
 #endif /* SMP */
 
-	cmpl	$0, PCB_USERLDT(%edx)	/* if there is one */
+	movl	TD_PROC(%ecx), %eax	/* load struct proc from CURTHREAD */
+	cmpl    $0, P_MD+MD_LDT(%eax)   /* see if md_ldt == 0 */
 	jnz	1f			/* then use it */
 	movl	_default_ldt,%eax	/* We will use the default */
 	cmpl	PCPU(CURRENTLDT),%eax	/* check to see if already loaded */
@@ -255,9 +256,11 @@ sw1b:
 	movl	%eax,PCPU(CURRENTLDT)	/* store what we have */
 	jmp	2f
 
-1:	pushl	%edx			/* call a non-trusting routine */
-	call	set_user_ldt		/* to check and load the ldt */
-	popl	%edx
+1:	pushl	%edx			/* save edx */
+	pushl	P_MD+MD_LDT(%eax)	/* passing p_md -> set_user_ldt */
+	call	set_user_ldt		/* check and load the ldt */
+	popl	%eax			/* get p_md off stack */
+	popl	%edx			/* restore edx */
 2:
 
 	/* This must be done after loading the user LDT. */
diff --git a/sys/amd64/amd64/genassym.c b/sys/amd64/amd64/genassym.c
index 5e0d93a..9f41665 100644
--- a/sys/amd64/amd64/genassym.c
+++ b/sys/amd64/amd64/genassym.c
@@ -63,6 +63,7 @@
 #include <vm/pmap.h>
 #include <vm/vm_map.h>
 #include <sys/user.h>
+#include <sys/proc.h>
 #include <net/if.h>
 #include <netinet/in.h>
 #include <nfs/nfsproto.h>
@@ -76,6 +77,7 @@
 #include <machine/sigframe.h>
 #include <machine/globaldata.h>
 #include <machine/vm86.h>
+#include <machine/proc.h>
 
 ASSYM(P_VMSPACE, offsetof(struct proc, p_vmspace));
 ASSYM(VM_PMAP, offsetof(struct vmspace, vm_pmap));
@@ -92,6 +94,9 @@ ASSYM(TD_KSE, offsetof(struct thread, td_kse));
 ASSYM(TD_PROC, offsetof(struct thread, td_proc));
 ASSYM(TD_INTR_NESTING_LEVEL, offsetof(struct thread, td_intr_nesting_level));
 
+ASSYM(P_MD, offsetof(struct proc, p_md));
+ASSYM(MD_LDT, offsetof(struct mdproc, md_ldt));
+
 ASSYM(KE_FLAGS, offsetof(struct kse, ke_flags));
 
 ASSYM(KEF_ASTPENDING, KEF_ASTPENDING);
@@ -126,7 +131,6 @@ ASSYM(PCB_EBX, offsetof(struct pcb, pcb_ebx));
 ASSYM(PCB_EIP, offsetof(struct pcb, pcb_eip));
 ASSYM(TSS_ESP0, offsetof(struct i386tss, tss_esp0));
 
-ASSYM(PCB_USERLDT, offsetof(struct pcb, pcb_ldt));
 ASSYM(PCB_GS, offsetof(struct pcb, pcb_gs));
 ASSYM(PCB_DR0, offsetof(struct pcb, pcb_dr0));
 ASSYM(PCB_DR1, offsetof(struct pcb, pcb_dr1));
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 6711515..213559c 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -103,6 +103,7 @@
 #include <machine/md_var.h>
 #include <machine/pc/bios.h>
 #include <machine/pcb_ext.h>		/* pcb.h included via sys/user.h */
+#include <machine/proc.h>
 #include <machine/globals.h>
 #ifdef PERFMON
 #include <machine/perfmon.h>
@@ -880,8 +881,8 @@ setregs(td, entry, stack, ps_strings)
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
-	if (pcb->pcb_ldt)
-		user_ldt_free(pcb);
+	if (td->td_proc->p_md.md_ldt)
+		user_ldt_free(td);
   
 	bzero((char *)regs, sizeof(struct trapframe));
 	regs->tf_eip = entry;
diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s
index 55d4c0d..d63afbd 100644
--- a/sys/amd64/amd64/swtch.s
+++ b/sys/amd64/amd64/swtch.s
@@ -246,7 +246,8 @@ sw1b:
 	/* XXX FIXME: we should be restoring the local APIC TPR */
 #endif /* SMP */
 
-	cmpl	$0, PCB_USERLDT(%edx)	/* if there is one */
+	movl	TD_PROC(%ecx), %eax	/* load struct proc from CURTHREAD */
+	cmpl    $0, P_MD+MD_LDT(%eax)   /* see if md_ldt == 0 */
 	jnz	1f			/* then use it */
 	movl	_default_ldt,%eax	/* We will use the default */
 	cmpl	PCPU(CURRENTLDT),%eax	/* check to see if already loaded */
@@ -255,9 +256,11 @@ sw1b:
 	movl	%eax,PCPU(CURRENTLDT)	/* store what we have */
 	jmp	2f
 
-1:	pushl	%edx			/* call a non-trusting routine */
-	call	set_user_ldt		/* to check and load the ldt */
-	popl	%edx
+1:	pushl	%edx			/* save edx */
+	pushl	P_MD+MD_LDT(%eax)	/* passing p_md -> set_user_ldt */
+	call	set_user_ldt		/* check and load the ldt */
+	popl	%eax			/* get p_md off stack */
+	popl	%edx			/* restore edx */
 2:
 
 	/* This must be done after loading the user LDT. */
diff --git a/sys/amd64/amd64/sys_machdep.c b/sys/amd64/amd64/sys_machdep.c
index 4c53d5a..a88acc9 100644
--- a/sys/amd64/amd64/sys_machdep.c
+++ b/sys/amd64/amd64/sys_machdep.c
@@ -54,6 +54,7 @@
 
 #include <machine/cpu.h>
 #include <machine/pcb_ext.h>	/* pcb.h included by sys/user.h */
+#include <machine/proc.h>
 #include <machine/sysarch.h>
 
 #include <vm/vm_kern.h>		/* for kernel_map */
@@ -70,7 +71,7 @@ static int i386_set_ldt	__P((struct thread *, char *));
 static int i386_get_ioperm	__P((struct thread *, char *));
 static int i386_set_ioperm	__P((struct thread *, char *));
 #ifdef SMP
-static void set_user_ldt_rv	__P((struct pcb *));
+static void set_user_ldt_rv	__P((struct thread *));
 #endif
 
 #ifndef _SYS_SYSPROTO_H_
@@ -256,15 +257,15 @@ done:
  * curproc but before sched_lock's owner is updated in mi_switch().
  */   
 void
-set_user_ldt(struct pcb *pcb)
+set_user_ldt(struct mdproc *mdp)
 {
-	struct pcb_ldt *pcb_ldt;
+	struct proc_ldt *pldt;
 
-	pcb_ldt = pcb->pcb_ldt;
+	pldt = mdp->md_ldt;
 #ifdef SMP
-	gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pcb_ldt->ldt_sd;
+	gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd;
 #else
-	gdt[GUSERLDT_SEL].sd = pcb_ldt->ldt_sd;
+	gdt[GUSERLDT_SEL].sd = pldt->ldt_sd;
 #endif
 	lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
 	PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
@@ -272,14 +273,14 @@ set_user_ldt(struct pcb *pcb)
 
 #ifdef SMP
 static void
-set_user_ldt_rv(struct pcb *pcb)
+set_user_ldt_rv(struct thread *td)
 {
 
-	if (pcb != PCPU_GET(curpcb))
+	if (td != PCPU_GET(curthread))
 		return;
 
 	mtx_lock_spin(&sched_lock);
-	set_user_ldt(pcb);
+	set_user_ldt(&td->td_proc->p_md);
 	mtx_unlock_spin(&sched_lock);
 }
 #endif
@@ -288,15 +289,15 @@ set_user_ldt_rv(struct pcb *pcb)
  * Must be called with either sched_lock free or held but not recursed.
  * If it does not return NULL, it will return with it owned.
  */
-struct pcb_ldt *
-user_ldt_alloc(struct pcb *pcb, int len)
+struct proc_ldt *
+user_ldt_alloc(struct mdproc *mdp, int len)
 {
-	struct pcb_ldt *pcb_ldt, *new_ldt;
+	struct proc_ldt *pldt, *new_ldt;
 
 	if (mtx_owned(&sched_lock))
 		mtx_unlock_spin(&sched_lock);
 	mtx_assert(&sched_lock, MA_NOTOWNED);
-	MALLOC(new_ldt, struct pcb_ldt *, sizeof(struct pcb_ldt),
+	MALLOC(new_ldt, struct proc_ldt *, sizeof(struct proc_ldt),
 		M_SUBPROC, M_WAITOK);
 
 	new_ldt->ldt_len = len = NEW_MAX_LD(len);
@@ -314,11 +315,11 @@ user_ldt_alloc(struct pcb *pcb, int len)
 	gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
 	ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);
 
-	if ((pcb_ldt = pcb->pcb_ldt)) {
-		if (len > pcb_ldt->ldt_len)
-			len = pcb_ldt->ldt_len;
-		bcopy(pcb_ldt->ldt_base, new_ldt->ldt_base,
-			len * sizeof(union descriptor));
+	if ((pldt = mdp->md_ldt)) {
+		if (len > pldt->ldt_len)
+			len = pldt->ldt_len;
+		bcopy(pldt->ldt_base, new_ldt->ldt_base,
+		    len * sizeof(union descriptor));
 	} else {
 		bcopy(ldt, new_ldt->ldt_base, sizeof(ldt));
 	}
@@ -327,30 +328,31 @@ user_ldt_alloc(struct pcb *pcb, int len)
 
 /*
  * Must be called either with sched_lock free or held but not recursed.
- * If pcb->pcb_ldt is not NULL, it will return with sched_lock released.
+ * If md_ldt is not NULL, it will return with sched_lock released.
  */
 void
-user_ldt_free(struct pcb *pcb)
+user_ldt_free(struct thread *td)
 {
-	struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
+	struct mdproc *mdp = &td->td_proc->p_md;
+	struct proc_ldt *pldt = mdp->md_ldt;
 
-	if (pcb_ldt == NULL)
+	if (pldt == NULL)
 		return;
 
 	if (!mtx_owned(&sched_lock))
 		mtx_lock_spin(&sched_lock);
 	mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
-	if (pcb == PCPU_GET(curpcb)) {
+	if (td == PCPU_GET(curthread)) {
 		lldt(_default_ldt);
 		PCPU_SET(currentldt, _default_ldt);
 	}
 
-	pcb->pcb_ldt = NULL;
-	if (--pcb_ldt->ldt_refcnt == 0) {
+	mdp->md_ldt = NULL;
+	if (--pldt->ldt_refcnt == 0) {
 		mtx_unlock_spin(&sched_lock);
-		kmem_free(kernel_map, (vm_offset_t)pcb_ldt->ldt_base,
-			pcb_ldt->ldt_len * sizeof(union descriptor));
-		FREE(pcb_ldt, M_SUBPROC);
+		kmem_free(kernel_map, (vm_offset_t)pldt->ldt_base,
+			pldt->ldt_len * sizeof(union descriptor));
+		FREE(pldt, M_SUBPROC);
 	} else
 		mtx_unlock_spin(&sched_lock);
 }
@@ -361,8 +363,7 @@ i386_get_ldt(td, args)
 	char *args;
 {
 	int error = 0;
-	struct pcb *pcb = td->td_pcb;
-	struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
+	struct proc_ldt *pldt = td->td_proc->p_md.md_ldt;
 	int nldt, num;
 	union descriptor *lp;
 	struct i386_ldt_args ua, *uap = &ua;
@@ -379,10 +380,10 @@ i386_get_ldt(td, args)
 	if ((uap->start < 0) || (uap->num <= 0))
 		return(EINVAL);
 
-	if (pcb_ldt) {
-		nldt = pcb_ldt->ldt_len;
+	if (pldt) {
+		nldt = pldt->ldt_len;
 		num = min(uap->num, nldt);
-		lp = &((union descriptor *)(pcb_ldt->ldt_base))[uap->start];
+		lp = &((union descriptor *)(pldt->ldt_base))[uap->start];
 	} else {
 		nldt = sizeof(ldt)/sizeof(ldt[0]);
 		num = min(uap->num, nldt);
@@ -405,8 +406,8 @@ i386_set_ldt(td, args)
 {
 	int error = 0, i, n;
 	int largest_ld;
-	struct pcb *pcb = td->td_pcb;
-	struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
+	struct mdproc *mdp = &td->td_proc->p_md;
+	struct proc_ldt *pldt = mdp->md_ldt;
 	struct i386_ldt_args ua, *uap = &ua;
 	caddr_t old_ldt_base;
 	int old_ldt_len;
@@ -431,16 +432,16 @@ i386_set_ldt(td, args)
 		return(EINVAL);
 
 	/* allocate user ldt */
-	if (!pcb_ldt || largest_ld >= pcb_ldt->ldt_len) {
-		struct pcb_ldt *new_ldt = user_ldt_alloc(pcb, largest_ld);
+	if (!pldt || largest_ld >= pldt->ldt_len) {
+		struct proc_ldt *new_ldt = user_ldt_alloc(mdp, largest_ld);
 		if (new_ldt == NULL)
 			return ENOMEM;
-		if (pcb_ldt) {
-			old_ldt_base = pcb_ldt->ldt_base;
-			old_ldt_len = pcb_ldt->ldt_len;
-			pcb_ldt->ldt_sd = new_ldt->ldt_sd;
-			pcb_ldt->ldt_base = new_ldt->ldt_base;
-			pcb_ldt->ldt_len = new_ldt->ldt_len;
+		if (pldt) {
+			old_ldt_base = pldt->ldt_base;
+			old_ldt_len = pldt->ldt_len;
+			pldt->ldt_sd = new_ldt->ldt_sd;
+			pldt->ldt_base = new_ldt->ldt_base;
+			pldt->ldt_len = new_ldt->ldt_len;
 			mtx_unlock_spin(&sched_lock);
 			kmem_free(kernel_map, (vm_offset_t)old_ldt_base,
 				old_ldt_len * sizeof(union descriptor));
@@ -449,16 +450,17 @@ i386_set_ldt(td, args)
 			mtx_lock_spin(&sched_lock);
 #endif
 		} else {
-			pcb->pcb_ldt = pcb_ldt = new_ldt;
+			mdp->md_ldt = pldt = new_ldt;
 #ifdef SMP
 			mtx_unlock_spin(&sched_lock);
 #endif
 		}
 #ifdef SMP
 		/* signal other cpus to reload ldt */
-		smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, NULL, pcb);
+		smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 
+		    NULL, td);
 #else
-		set_user_ldt(pcb);
+		set_user_ldt(mdp);
 		mtx_unlock_spin(&sched_lock);
 #endif
 	}
@@ -532,7 +534,7 @@ i386_set_ldt(td, args)
 	/* Fill in range */
 	savecrit = critical_enter();
 	error = copyin(uap->descs, 
-	    &((union descriptor *)(pcb_ldt->ldt_base))[uap->start],
+	    &((union descriptor *)(pldt->ldt_base))[uap->start],
 	    uap->num * sizeof(union descriptor));
 	if (!error)
 		td->td_retval[0] = uap->start;
diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index e993e31..59898e3 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -125,6 +125,7 @@ cpu_fork(td1, p2, flags)
 	register struct proc *p1;
 	struct thread *td2;
 	struct pcb *pcb2;
+	struct mdproc *mdp2;
 #ifdef DEV_NPX
 	int savecrit;
 #endif
@@ -134,15 +135,15 @@ cpu_fork(td1, p2, flags)
 	if ((flags & RFPROC) == 0) {
 		if ((flags & RFMEM) == 0) {
 			/* unshare user LDT */
-			struct pcb *pcb1 = td1->td_pcb;
-			struct pcb_ldt *pcb_ldt = pcb1->pcb_ldt;
-			if (pcb_ldt && pcb_ldt->ldt_refcnt > 1) {
-				pcb_ldt = user_ldt_alloc(pcb1,pcb_ldt->ldt_len);
-				if (pcb_ldt == NULL)
+			struct mdproc *mdp1 = &td1->td_proc->p_md;
+			struct proc_ldt *pldt = mdp1->md_ldt;
+			if (pldt && pldt->ldt_refcnt > 1) {
+				pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
+				if (pldt == NULL)
 					panic("could not copy LDT");
-				pcb1->pcb_ldt = pcb_ldt;
-				set_user_ldt(pcb1);
-				user_ldt_free(pcb1);
+				mdp1->md_ldt = pldt;
+				set_user_ldt(mdp1);
+				user_ldt_free(td1);
 			}
 		}
 		return;
@@ -162,9 +163,13 @@ cpu_fork(td1, p2, flags)
 	pcb2 = (struct pcb *)(td2->td_kstack + KSTACK_PAGES * PAGE_SIZE) - 1;
 	td2->td_pcb = pcb2;
 
-	/* Copy p1's pcb. */
+	/* Copy p1's pcb */
 	bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
 
+	/* Point mdproc and then copy over td1's contents */
+	mdp2 = &td2->td_proc->p_md;
+	bcopy(&td1->td_proc->p_md, mdp2, sizeof(*mdp2));
+
 	/*
 	 * Create a new fresh stack for the new process.
 	 * Copy the trap frame for the return to user mode as if from a
@@ -191,7 +196,6 @@ cpu_fork(td1, p2, flags)
 	pcb2->pcb_eip = (int)fork_trampoline;
 	/*-
 	 * pcb2->pcb_dr*:	cloned above.
-	 * pcb2->pcb_ldt:	duplicated below, if necessary.
 	 * pcb2->pcb_savefpu:	cloned above.
 	 * pcb2->pcb_flags:	cloned above.
 	 * pcb2->pcb_onfault:	cloned above (always NULL here?).
@@ -206,13 +210,13 @@ cpu_fork(td1, p2, flags)
 
         /* Copy the LDT, if necessary. */
 	mtx_lock_spin(&sched_lock);
-        if (pcb2->pcb_ldt != 0) {
+        if (mdp2->md_ldt != 0) {
 		if (flags & RFMEM) {
-			pcb2->pcb_ldt->ldt_refcnt++;
+			mdp2->md_ldt->ldt_refcnt++;
 		} else {
-			pcb2->pcb_ldt = user_ldt_alloc(pcb2,
-				pcb2->pcb_ldt->ldt_len);
-			if (pcb2->pcb_ldt == NULL)
+			mdp2->md_ldt = user_ldt_alloc(mdp2,
+			    mdp2->md_ldt->ldt_len);
+			if (mdp2->md_ldt == NULL)
 				panic("could not copy LDT");
 		}
         }
@@ -254,7 +258,7 @@ cpu_exit(td)
 	register struct thread *td;
 {
 	struct pcb *pcb = td->td_pcb; 
-
+	struct mdproc *mdp = &td->td_proc->p_md;
 #ifdef DEV_NPX
 	npxexit(td);
 #endif
@@ -267,8 +271,8 @@ cpu_exit(td)
 		    ctob(IOPAGES + 1));
 		pcb->pcb_ext = 0;
 	}
-	if (pcb->pcb_ldt)
-		user_ldt_free(pcb);
+	if (mdp->md_ldt)
+		user_ldt_free(td);
         if (pcb->pcb_flags & PCB_DBREGS) {
                 /*
                  * disable all hardware breakpoints
diff --git a/sys/amd64/include/pcb.h b/sys/amd64/include/pcb.h
index 21d95c5..9eb0f81 100644
--- a/sys/amd64/include/pcb.h
+++ b/sys/amd64/include/pcb.h
@@ -61,7 +61,6 @@ struct pcb {
 	int     pcb_dr6;
 	int     pcb_dr7;
 
-	struct	pcb_ldt *pcb_ldt;	/* per process (user) LDT */
 	union	savefpu	pcb_save;
 	u_char	pcb_flags;
 #define	FP_SOFTFP	0x01	/* process using software fltng pnt emulator */
diff --git a/sys/amd64/include/pcb_ext.h b/sys/amd64/include/pcb_ext.h
index c6f9fc0..3256f99 100644
--- a/sys/amd64/include/pcb_ext.h
+++ b/sys/amd64/include/pcb_ext.h
@@ -43,20 +43,9 @@ struct pcb_ext {
 	struct	vm86_kernel ext_vm86;	/* vm86 area */
 };
 
-struct pcb_ldt {
-	caddr_t	ldt_base;
-	int	ldt_len;
-	int	ldt_refcnt;
-	u_long	ldt_active;
-	struct	segment_descriptor ldt_sd;
-};
-
 #ifdef _KERNEL
 
 int i386_extend_pcb __P((struct thread *));
-void set_user_ldt __P((struct pcb *));
-struct pcb_ldt *user_ldt_alloc __P((struct pcb *, int));
-void user_ldt_free __P((struct pcb *));
 
 #endif
 
diff --git a/sys/amd64/include/proc.h b/sys/amd64/include/proc.h
index 9e9e449..911f6b8 100644
--- a/sys/amd64/include/proc.h
+++ b/sys/amd64/include/proc.h
@@ -38,6 +38,15 @@
 #define	_MACHINE_PROC_H_
 
 #include <machine/globals.h>
+#include <machine/segments.h>
+
+struct proc_ldt {
+        caddr_t ldt_base;
+        int     ldt_len;
+        int     ldt_refcnt;
+        u_long  ldt_active;
+        struct  segment_descriptor ldt_sd;
+};
 
 /*
  * Machine-dependent part of the proc structure for i386.
@@ -46,6 +55,15 @@ struct mdthread {
 };
 
 struct mdproc {
+	struct proc_ldt *md_ldt;	/* per-process ldt */
 };
 
+#ifdef	_KERNEL
+
+void 	set_user_ldt __P((struct mdproc *));
+struct 	proc_ldt *user_ldt_alloc __P((struct mdproc *, int));
+void 	user_ldt_free __P((struct thread *));
+
+#endif	/* _KERNEL */
+
 #endif /* !_MACHINE_PROC_H_ */
diff --git a/sys/i386/i386/genassym.c b/sys/i386/i386/genassym.c
index 5e0d93a..9f41665 100644
--- a/sys/i386/i386/genassym.c
+++ b/sys/i386/i386/genassym.c
@@ -63,6 +63,7 @@
 #include <vm/pmap.h>
 #include <vm/vm_map.h>
 #include <sys/user.h>
+#include <sys/proc.h>
 #include <net/if.h>
 #include <netinet/in.h>
 #include <nfs/nfsproto.h>
@@ -76,6 +77,7 @@
 #include <machine/sigframe.h>
 #include <machine/globaldata.h>
 #include <machine/vm86.h>
+#include <machine/proc.h>
 
 ASSYM(P_VMSPACE, offsetof(struct proc, p_vmspace));
 ASSYM(VM_PMAP, offsetof(struct vmspace, vm_pmap));
@@ -92,6 +94,9 @@ ASSYM(TD_KSE, offsetof(struct thread, td_kse));
 ASSYM(TD_PROC, offsetof(struct thread, td_proc));
 ASSYM(TD_INTR_NESTING_LEVEL, offsetof(struct thread, td_intr_nesting_level));
 
+ASSYM(P_MD, offsetof(struct proc, p_md));
+ASSYM(MD_LDT, offsetof(struct mdproc, md_ldt));
+
 ASSYM(KE_FLAGS, offsetof(struct kse, ke_flags));
 
 ASSYM(KEF_ASTPENDING, KEF_ASTPENDING);
@@ -126,7 +131,6 @@ ASSYM(PCB_EBX, offsetof(struct pcb, pcb_ebx));
 ASSYM(PCB_EIP, offsetof(struct pcb, pcb_eip));
 ASSYM(TSS_ESP0, offsetof(struct i386tss, tss_esp0));
 
-ASSYM(PCB_USERLDT, offsetof(struct pcb, pcb_ldt));
 ASSYM(PCB_GS, offsetof(struct pcb, pcb_gs));
 ASSYM(PCB_DR0, offsetof(struct pcb, pcb_dr0));
 ASSYM(PCB_DR1, offsetof(struct pcb, pcb_dr1));
diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index 6711515..213559c 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -103,6 +103,7 @@
 #include <machine/md_var.h>
 #include <machine/pc/bios.h>
 #include <machine/pcb_ext.h>		/* pcb.h included via sys/user.h */
+#include <machine/proc.h>
 #include <machine/globals.h>
 #ifdef PERFMON
 #include <machine/perfmon.h>
@@ -880,8 +881,8 @@ setregs(td, entry, stack, ps_strings)
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
-	if (pcb->pcb_ldt)
-		user_ldt_free(pcb);
+	if (td->td_proc->p_md.md_ldt)
+		user_ldt_free(td);
   
 	bzero((char *)regs, sizeof(struct trapframe));
 	regs->tf_eip = entry;
diff --git a/sys/i386/i386/swtch.s b/sys/i386/i386/swtch.s
index 55d4c0d..d63afbd 100644
--- a/sys/i386/i386/swtch.s
+++ b/sys/i386/i386/swtch.s
@@ -246,7 +246,8 @@ sw1b:
 	/* XXX FIXME: we should be restoring the local APIC TPR */
 #endif /* SMP */
 
-	cmpl	$0, PCB_USERLDT(%edx)	/* if there is one */
+	movl	TD_PROC(%ecx), %eax	/* load struct proc from CURTHREAD */
+	cmpl    $0, P_MD+MD_LDT(%eax)   /* see if md_ldt == 0 */
 	jnz	1f			/* then use it */
 	movl	_default_ldt,%eax	/* We will use the default */
 	cmpl	PCPU(CURRENTLDT),%eax	/* check to see if already loaded */
@@ -255,9 +256,11 @@ sw1b:
 	movl	%eax,PCPU(CURRENTLDT)	/* store what we have */
 	jmp	2f
 
-1:	pushl	%edx			/* call a non-trusting routine */
-	call	set_user_ldt		/* to check and load the ldt */
-	popl	%edx
+1:	pushl	%edx			/* save edx */
+	pushl	P_MD+MD_LDT(%eax)	/* passing p_md -> set_user_ldt */
+	call	set_user_ldt		/* check and load the ldt */
+	popl	%eax			/* get p_md off stack */
+	popl	%edx			/* restore edx */
 2:
 
 	/* This must be done after loading the user LDT. */
diff --git a/sys/i386/i386/sys_machdep.c b/sys/i386/i386/sys_machdep.c
index 4c53d5a..a88acc9 100644
--- a/sys/i386/i386/sys_machdep.c
+++ b/sys/i386/i386/sys_machdep.c
@@ -54,6 +54,7 @@
 
 #include <machine/cpu.h>
 #include <machine/pcb_ext.h>	/* pcb.h included by sys/user.h */
+#include <machine/proc.h>
 #include <machine/sysarch.h>
 
 #include <vm/vm_kern.h>		/* for kernel_map */
@@ -70,7 +71,7 @@ static int i386_set_ldt	__P((struct thread *, char *));
 static int i386_get_ioperm	__P((struct thread *, char *));
 static int i386_set_ioperm	__P((struct thread *, char *));
 #ifdef SMP
-static void set_user_ldt_rv	__P((struct pcb *));
+static void set_user_ldt_rv	__P((struct thread *));
 #endif
 
 #ifndef _SYS_SYSPROTO_H_
@@ -256,15 +257,15 @@ done:
  * curproc but before sched_lock's owner is updated in mi_switch().
  */   
 void
-set_user_ldt(struct pcb *pcb)
+set_user_ldt(struct mdproc *mdp)
 {
-	struct pcb_ldt *pcb_ldt;
+	struct proc_ldt *pldt;
 
-	pcb_ldt = pcb->pcb_ldt;
+	pldt = mdp->md_ldt;
 #ifdef SMP
-	gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pcb_ldt->ldt_sd;
+	gdt[PCPU_GET(cpuid) * NGDT + GUSERLDT_SEL].sd = pldt->ldt_sd;
 #else
-	gdt[GUSERLDT_SEL].sd = pcb_ldt->ldt_sd;
+	gdt[GUSERLDT_SEL].sd = pldt->ldt_sd;
 #endif
 	lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
 	PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
@@ -272,14 +273,14 @@ set_user_ldt(struct pcb *pcb)
 
 #ifdef SMP
 static void
-set_user_ldt_rv(struct pcb *pcb)
+set_user_ldt_rv(struct thread *td)
 {
 
-	if (pcb != PCPU_GET(curpcb))
+	if (td != PCPU_GET(curthread))
 		return;
 
 	mtx_lock_spin(&sched_lock);
-	set_user_ldt(pcb);
+	set_user_ldt(&td->td_proc->p_md);
 	mtx_unlock_spin(&sched_lock);
 }
 #endif
@@ -288,15 +289,15 @@ set_user_ldt_rv(struct pcb *pcb)
  * Must be called with either sched_lock free or held but not recursed.
  * If it does not return NULL, it will return with it owned.
  */
-struct pcb_ldt *
-user_ldt_alloc(struct pcb *pcb, int len)
+struct proc_ldt *
+user_ldt_alloc(struct mdproc *mdp, int len)
 {
-	struct pcb_ldt *pcb_ldt, *new_ldt;
+	struct proc_ldt *pldt, *new_ldt;
 
 	if (mtx_owned(&sched_lock))
 		mtx_unlock_spin(&sched_lock);
 	mtx_assert(&sched_lock, MA_NOTOWNED);
-	MALLOC(new_ldt, struct pcb_ldt *, sizeof(struct pcb_ldt),
+	MALLOC(new_ldt, struct proc_ldt *, sizeof(struct proc_ldt),
 		M_SUBPROC, M_WAITOK);
 
 	new_ldt->ldt_len = len = NEW_MAX_LD(len);
@@ -314,11 +315,11 @@ user_ldt_alloc(struct pcb *pcb, int len)
 	gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
 	ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);
 
-	if ((pcb_ldt = pcb->pcb_ldt)) {
-		if (len > pcb_ldt->ldt_len)
-			len = pcb_ldt->ldt_len;
-		bcopy(pcb_ldt->ldt_base, new_ldt->ldt_base,
-			len * sizeof(union descriptor));
+	if ((pldt = mdp->md_ldt)) {
+		if (len > pldt->ldt_len)
+			len = pldt->ldt_len;
+		bcopy(pldt->ldt_base, new_ldt->ldt_base,
+		    len * sizeof(union descriptor));
 	} else {
 		bcopy(ldt, new_ldt->ldt_base, sizeof(ldt));
 	}
@@ -327,30 +328,31 @@ user_ldt_alloc(struct pcb *pcb, int len)
 
 /*
  * Must be called either with sched_lock free or held but not recursed.
- * If pcb->pcb_ldt is not NULL, it will return with sched_lock released.
+ * If md_ldt is not NULL, it will return with sched_lock released.
  */
 void
-user_ldt_free(struct pcb *pcb)
+user_ldt_free(struct thread *td)
 {
-	struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
+	struct mdproc *mdp = &td->td_proc->p_md;
+	struct proc_ldt *pldt = mdp->md_ldt;
 
-	if (pcb_ldt == NULL)
+	if (pldt == NULL)
 		return;
 
 	if (!mtx_owned(&sched_lock))
 		mtx_lock_spin(&sched_lock);
 	mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
-	if (pcb == PCPU_GET(curpcb)) {
+	if (td == PCPU_GET(curthread)) {
 		lldt(_default_ldt);
 		PCPU_SET(currentldt, _default_ldt);
 	}
 
-	pcb->pcb_ldt = NULL;
-	if (--pcb_ldt->ldt_refcnt == 0) {
+	mdp->md_ldt = NULL;
+	if (--pldt->ldt_refcnt == 0) {
 		mtx_unlock_spin(&sched_lock);
-		kmem_free(kernel_map, (vm_offset_t)pcb_ldt->ldt_base,
-			pcb_ldt->ldt_len * sizeof(union descriptor));
-		FREE(pcb_ldt, M_SUBPROC);
+		kmem_free(kernel_map, (vm_offset_t)pldt->ldt_base,
+			pldt->ldt_len * sizeof(union descriptor));
+		FREE(pldt, M_SUBPROC);
 	} else
 		mtx_unlock_spin(&sched_lock);
 }
@@ -361,8 +363,7 @@ i386_get_ldt(td, args)
 	char *args;
 {
 	int error = 0;
-	struct pcb *pcb = td->td_pcb;
-	struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
+	struct proc_ldt *pldt = td->td_proc->p_md.md_ldt;
 	int nldt, num;
 	union descriptor *lp;
 	struct i386_ldt_args ua, *uap = &ua;
@@ -379,10 +380,10 @@ i386_get_ldt(td, args)
 	if ((uap->start < 0) || (uap->num <= 0))
 		return(EINVAL);
 
-	if (pcb_ldt) {
-		nldt = pcb_ldt->ldt_len;
+	if (pldt) {
+		nldt = pldt->ldt_len;
 		num = min(uap->num, nldt);
-		lp = &((union descriptor *)(pcb_ldt->ldt_base))[uap->start];
+		lp = &((union descriptor *)(pldt->ldt_base))[uap->start];
 	} else {
 		nldt = sizeof(ldt)/sizeof(ldt[0]);
 		num = min(uap->num, nldt);
@@ -405,8 +406,8 @@ i386_set_ldt(td, args)
 {
 	int error = 0, i, n;
 	int largest_ld;
-	struct pcb *pcb = td->td_pcb;
-	struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
+	struct mdproc *mdp = &td->td_proc->p_md;
+	struct proc_ldt *pldt = mdp->md_ldt;
 	struct i386_ldt_args ua, *uap = &ua;
 	caddr_t old_ldt_base;
 	int old_ldt_len;
@@ -431,16 +432,16 @@ i386_set_ldt(td, args)
 		return(EINVAL);
 
 	/* allocate user ldt */
-	if (!pcb_ldt || largest_ld >= pcb_ldt->ldt_len) {
-		struct pcb_ldt *new_ldt = user_ldt_alloc(pcb, largest_ld);
+	if (!pldt || largest_ld >= pldt->ldt_len) {
+		struct proc_ldt *new_ldt = user_ldt_alloc(mdp, largest_ld);
 		if (new_ldt == NULL)
 			return ENOMEM;
-		if (pcb_ldt) {
-			old_ldt_base = pcb_ldt->ldt_base;
-			old_ldt_len = pcb_ldt->ldt_len;
-			pcb_ldt->ldt_sd = new_ldt->ldt_sd;
-			pcb_ldt->ldt_base = new_ldt->ldt_base;
-			pcb_ldt->ldt_len = new_ldt->ldt_len;
+		if (pldt) {
+			old_ldt_base = pldt->ldt_base;
+			old_ldt_len = pldt->ldt_len;
+			pldt->ldt_sd = new_ldt->ldt_sd;
+			pldt->ldt_base = new_ldt->ldt_base;
+			pldt->ldt_len = new_ldt->ldt_len;
 			mtx_unlock_spin(&sched_lock);
 			kmem_free(kernel_map, (vm_offset_t)old_ldt_base,
 				old_ldt_len * sizeof(union descriptor));
@@ -449,16 +450,17 @@ i386_set_ldt(td, args)
 			mtx_lock_spin(&sched_lock);
 #endif
 		} else {
-			pcb->pcb_ldt = pcb_ldt = new_ldt;
+			mdp->md_ldt = pldt = new_ldt;
 #ifdef SMP
 			mtx_unlock_spin(&sched_lock);
 #endif
 		}
 #ifdef SMP
 		/* signal other cpus to reload ldt */
-		smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, NULL, pcb);
+		smp_rendezvous(NULL, (void (*)(void *))set_user_ldt_rv, 
+		    NULL, td);
 #else
-		set_user_ldt(pcb);
+		set_user_ldt(mdp);
 		mtx_unlock_spin(&sched_lock);
 #endif
 	}
@@ -532,7 +534,7 @@ i386_set_ldt(td, args)
 	/* Fill in range */
 	savecrit = critical_enter();
 	error = copyin(uap->descs, 
-	    &((union descriptor *)(pcb_ldt->ldt_base))[uap->start],
+	    &((union descriptor *)(pldt->ldt_base))[uap->start],
 	    uap->num * sizeof(union descriptor));
 	if (!error)
 		td->td_retval[0] = uap->start;
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index e993e31..59898e3 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -125,6 +125,7 @@ cpu_fork(td1, p2, flags)
 	register struct proc *p1;
 	struct thread *td2;
 	struct pcb *pcb2;
+	struct mdproc *mdp2;
 #ifdef DEV_NPX
 	int savecrit;
 #endif
@@ -134,15 +135,15 @@ cpu_fork(td1, p2, flags)
 	if ((flags & RFPROC) == 0) {
 		if ((flags & RFMEM) == 0) {
 			/* unshare user LDT */
-			struct pcb *pcb1 = td1->td_pcb;
-			struct pcb_ldt *pcb_ldt = pcb1->pcb_ldt;
-			if (pcb_ldt && pcb_ldt->ldt_refcnt > 1) {
-				pcb_ldt = user_ldt_alloc(pcb1,pcb_ldt->ldt_len);
-				if (pcb_ldt == NULL)
+			struct mdproc *mdp1 = &td1->td_proc->p_md;
+			struct proc_ldt *pldt = mdp1->md_ldt;
+			if (pldt && pldt->ldt_refcnt > 1) {
+				pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
+				if (pldt == NULL)
 					panic("could not copy LDT");
-				pcb1->pcb_ldt = pcb_ldt;
-				set_user_ldt(pcb1);
-				user_ldt_free(pcb1);
+				mdp1->md_ldt = pldt;
+				set_user_ldt(mdp1);
+				user_ldt_free(td1);
 			}
 		}
 		return;
@@ -162,9 +163,13 @@ cpu_fork(td1, p2, flags)
 	pcb2 = (struct pcb *)(td2->td_kstack + KSTACK_PAGES * PAGE_SIZE) - 1;
 	td2->td_pcb = pcb2;
 
-	/* Copy p1's pcb. */
+	/* Copy p1's pcb */
 	bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
 
+	/* Point mdproc and then copy over td1's contents */
+	mdp2 = &td2->td_proc->p_md;
+	bcopy(&td1->td_proc->p_md, mdp2, sizeof(*mdp2));
+
 	/*
 	 * Create a new fresh stack for the new process.
 	 * Copy the trap frame for the return to user mode as if from a
@@ -191,7 +196,6 @@ cpu_fork(td1, p2, flags)
 	pcb2->pcb_eip = (int)fork_trampoline;
 	/*-
 	 * pcb2->pcb_dr*:	cloned above.
-	 * pcb2->pcb_ldt:	duplicated below, if necessary.
 	 * pcb2->pcb_savefpu:	cloned above.
 	 * pcb2->pcb_flags:	cloned above.
 	 * pcb2->pcb_onfault:	cloned above (always NULL here?).
@@ -206,13 +210,13 @@ cpu_fork(td1, p2, flags)
 
         /* Copy the LDT, if necessary. */
 	mtx_lock_spin(&sched_lock);
-        if (pcb2->pcb_ldt != 0) {
+        if (mdp2->md_ldt != 0) {
 		if (flags & RFMEM) {
-			pcb2->pcb_ldt->ldt_refcnt++;
+			mdp2->md_ldt->ldt_refcnt++;
 		} else {
-			pcb2->pcb_ldt = user_ldt_alloc(pcb2,
-				pcb2->pcb_ldt->ldt_len);
-			if (pcb2->pcb_ldt == NULL)
+			mdp2->md_ldt = user_ldt_alloc(mdp2,
+			    mdp2->md_ldt->ldt_len);
+			if (mdp2->md_ldt == NULL)
 				panic("could not copy LDT");
 		}
         }
@@ -254,7 +258,7 @@ cpu_exit(td)
 	register struct thread *td;
 {
 	struct pcb *pcb = td->td_pcb; 
-
+	struct mdproc *mdp = &td->td_proc->p_md;
 #ifdef DEV_NPX
 	npxexit(td);
 #endif
@@ -267,8 +271,8 @@ cpu_exit(td)
 		    ctob(IOPAGES + 1));
 		pcb->pcb_ext = 0;
 	}
-	if (pcb->pcb_ldt)
-		user_ldt_free(pcb);
+	if (mdp->md_ldt)
+		user_ldt_free(td);
         if (pcb->pcb_flags & PCB_DBREGS) {
                 /*
                  * disable all hardware breakpoints
diff --git a/sys/i386/include/pcb.h b/sys/i386/include/pcb.h
index 21d95c5..9eb0f81 100644
--- a/sys/i386/include/pcb.h
+++ b/sys/i386/include/pcb.h
@@ -61,7 +61,6 @@ struct pcb {
 	int     pcb_dr6;
 	int     pcb_dr7;
 
-	struct	pcb_ldt *pcb_ldt;	/* per process (user) LDT */
 	union	savefpu	pcb_save;
 	u_char	pcb_flags;
 #define	FP_SOFTFP	0x01	/* process using software fltng pnt emulator */
diff --git a/sys/i386/include/pcb_ext.h b/sys/i386/include/pcb_ext.h
index c6f9fc0..3256f99 100644
--- a/sys/i386/include/pcb_ext.h
+++ b/sys/i386/include/pcb_ext.h
@@ -43,20 +43,9 @@ struct pcb_ext {
 	struct	vm86_kernel ext_vm86;	/* vm86 area */
 };
 
-struct pcb_ldt {
-	caddr_t	ldt_base;
-	int	ldt_len;
-	int	ldt_refcnt;
-	u_long	ldt_active;
-	struct	segment_descriptor ldt_sd;
-};
-
 #ifdef _KERNEL
 
 int i386_extend_pcb __P((struct thread *));
-void set_user_ldt __P((struct pcb *));
-struct pcb_ldt *user_ldt_alloc __P((struct pcb *, int));
-void user_ldt_free __P((struct pcb *));
 
 #endif
 
diff --git a/sys/i386/include/proc.h b/sys/i386/include/proc.h
index 9e9e449..911f6b8 100644
--- a/sys/i386/include/proc.h
+++ b/sys/i386/include/proc.h
@@ -38,6 +38,15 @@
 #define	_MACHINE_PROC_H_
 
 #include <machine/globals.h>
+#include <machine/segments.h>
+
+struct proc_ldt {
+        caddr_t ldt_base;
+        int     ldt_len;
+        int     ldt_refcnt;
+        u_long  ldt_active;
+        struct  segment_descriptor ldt_sd;
+};
 
 /*
  * Machine-dependent part of the proc structure for i386.
@@ -46,6 +55,15 @@ struct mdthread {
 };
 
 struct mdproc {
+	struct proc_ldt *md_ldt;	/* per-process ldt */
 };
 
+#ifdef	_KERNEL
+
+void 	set_user_ldt __P((struct mdproc *));
+struct 	proc_ldt *user_ldt_alloc __P((struct mdproc *, int));
+void 	user_ldt_free __P((struct thread *));
+
+#endif	/* _KERNEL */
+
 #endif /* !_MACHINE_PROC_H_ */