Index: i386/sys_machdep.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/i386/sys_machdep.c,v
retrieving revision 1.92.2.1
diff -u -r1.92.2.1 sys_machdep.c
--- i386/sys_machdep.c	5 Feb 2005 01:02:49 -0000	1.92.2.1
+++ i386/sys_machdep.c	25 Apr 2005 21:57:57 -0000
@@ -75,6 +75,7 @@
 #ifdef SMP
 static void set_user_ldt_rv(struct thread *);
 #endif
+static int i386_allocbase_ldt(struct thread *td, int sel, uint32_t base);
 
 #ifndef _SYS_SYSPROTO_H_
 struct sysarch_args {
@@ -88,14 +89,16 @@
 	struct thread *td;
 	register struct sysarch_args *uap;
 {
-	int error;
+	int error, sel;
+	uint32_t base;
+	struct proc_ldt *pldt;
+	union descriptor *dp;
 
 	mtx_lock(&Giant);
 	switch(uap->op) {
 	case I386_GET_LDT:
 		error = i386_get_ldt(td, uap->parms);
 		break;
-
 	case I386_SET_LDT:
 		error = i386_set_ldt(td, uap->parms);
 		break;
@@ -108,6 +111,51 @@
 	case I386_VM86:
 		error = vm86_sysarch(td, uap->parms);
 		break;
+	case I386_GET_FSBASE:
+		base = 0;
+		sel = td->td_pcb->pcb_fsbase;
+		pldt = td->td_proc->p_md.md_ldt;
+		if (sel != 0 && sel < pldt->ldt_len) {
+			dp = &((union descriptor *)(pldt->ldt_base))[sel];
+			base = dp->sd.sd_hibase << 24 | dp->sd.sd_lobase;
+		}
+		error = copyout(&base, uap->parms, sizeof(base));
+		break;
+	case I386_SET_FSBASE:
+		error = copyin(uap->parms, &base, sizeof(base));
+		if (error)
+			break;
+		sel = i386_allocbase_ldt(td, td->td_pcb->pcb_fsbase, base);
+		if (sel) {
+			td->td_pcb->pcb_fsbase = sel;
+			td->td_frame->tf_fs = LSEL(sel, SEL_UPL);
+		} else {
+			error = EINVAL;
+		}
+		break;
+	case I386_GET_GSBASE:
+		base = 0;
+		sel = td->td_pcb->pcb_gsbase;
+		pldt = td->td_proc->p_md.md_ldt;
+		if (sel != 0 && sel < pldt->ldt_len) {
+			dp = &((union descriptor *)(pldt->ldt_base))[sel];
+			base = dp->sd.sd_hibase << 24 | dp->sd.sd_lobase;
+		}
+		error = copyout(&base, uap->parms, sizeof(base));
+		break;
+	case I386_SET_GSBASE:
+		error = copyin(uap->parms, &base, sizeof(base));
+		if (error)
+			break;
+		sel = i386_allocbase_ldt(td, td->td_pcb->pcb_gsbase, base);
+		if (sel) {
+			td->td_pcb->pcb_gsbase = sel;
+			td->td_pcb->pcb_gs = LSEL(sel, SEL_UPL);
+			load_gs(td->td_pcb->pcb_gs);
+		} else {
+			error = EINVAL;
+		}
+		break;
 	default:
 		error = EINVAL;
 		break;
@@ -679,3 +727,64 @@
 	}
 	return (0);
 }
+
+static int
+i386_allocbase_ldt(struct thread *td, int sel, uint32_t base)
+{
+	struct mdproc *mdp = &td->td_proc->p_md;
+	struct proc_ldt *pldt = 0;
+	union descriptor *dp;
+	union descriptor sdu;
+	int error = 0;
+
+	sdu.sd.sd_lobase = base & 0xffffff;
+	sdu.sd.sd_hibase = (base >> 24) & 0xff;
+	sdu.sd.sd_lolimit = 0xffff;	/* 4GB limit, wraps around */
+	sdu.sd.sd_hilimit = 0xf;
+	sdu.sd.sd_type  = SDT_MEMRWA;
+	sdu.sd.sd_dpl   = SEL_UPL;
+	sdu.sd.sd_p     = 1;
+	sdu.sd.sd_xx    = 0;
+	sdu.sd.sd_def32 = 1;
+	sdu.sd.sd_gran  = 1;
+
+	/* Create LDT if needed, starting with a free slot */
+	pldt = mdp->md_ldt;
+	if (pldt == NULL) {
+		error = i386_ldt_grow(td, NLDT+1);
+		if (error)
+			return (0);
+		pldt = mdp->md_ldt;
+	}
+	/* Use specific slot if requested, growing ldt if needed */
+	if (sel) {
+		if (sel >= pldt->ldt_len) {
+			error = i386_ldt_grow(td, pldt->ldt_len+1);
+			if (error)
+				return (0);
+		}
+		mtx_lock_spin(&sched_lock);
+		i386_set_ldt_data(td, sel, 1, &sdu);
+		mtx_unlock_spin(&sched_lock);
+		return (sel);
+	}
+	/* Allocate first free slot, and make more room if needed */
+again:
+	mtx_lock_spin(&sched_lock);
+	dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
+	for (sel = NLDT; sel < pldt->ldt_len; ++sel) {
+		if (dp->sd.sd_type == SDT_SYSNULL)
+			break;
+		dp++;
+	}
+	if (sel >= pldt->ldt_len) {
+		mtx_unlock_spin(&sched_lock);
+		error = i386_ldt_grow(td, pldt->ldt_len+1);
+		if (error)
+			return (0);
+		goto again;
+	}
+	i386_set_ldt_data(td, sel, 1, &sdu);
+	mtx_unlock_spin(&sched_lock);
+	return (sel);
+}
Index: include/pcb.h
===================================================================
RCS file: /home/ncvs/src/sys/i386/include/pcb.h,v
retrieving revision 1.52.2.1
diff -u -r1.52.2.1 pcb.h
--- include/pcb.h	18 Apr 2005 21:21:47 -0000	1.52.2.1
+++ include/pcb.h	25 Apr 2005 21:33:02 -0000
@@ -71,6 +71,8 @@
 	int	pcb_psl;	/* process status long */
 	void	(*pcb_switchout)(void);	/* Special switchout function. */
 	u_long	pcb_vm86[2];	/* vm86bios scratch space */
+	int	pcb_fsbase;
+	int	pcb_gsbase;
 };
 
 #ifdef _KERNEL