From aaaf607148436993af968c6fb0f92a759e8fdccb Mon Sep 17 00:00:00 2001
From: Colin Percival <cperciva@FreeBSD.org>
Date: Fri, 31 Dec 2010 17:42:25 +0000
Subject: [PATCH] Make i386_set_ldt work on i386/XEN, step 5/5.

When cleaning up a thread, reset its LDT to the default LDT.

Note: Casting the LDT pointer to an int and storing it in pc_currentldt is
wildly bogus, but is harmless since pc_currentldt is a write-only variable.

MFC after:	3 days
---
 sys/i386/i386/sys_machdep.c | 5 +++++
 sys/i386/include/segments.h | 1 +
 2 files changed, 6 insertions(+)

diff --git a/sys/i386/i386/sys_machdep.c b/sys/i386/i386/sys_machdep.c
index b47679ab775..3fb231b7866 100644
--- a/sys/i386/i386/sys_machdep.c
+++ b/sys/i386/i386/sys_machdep.c
@@ -523,8 +523,13 @@ user_ldt_free(struct thread *td)
 	}
 
 	if (td == PCPU_GET(curthread)) {
+#ifdef XEN
+		i386_reset_ldt(&default_proc_ldt);
+		PCPU_SET(currentldt, (int)&default_proc_ldt);
+#else
 		lldt(_default_ldt);
 		PCPU_SET(currentldt, _default_ldt);
+#endif
 	}
 
 	mdp->md_ldt = NULL;
diff --git a/sys/i386/include/segments.h b/sys/i386/include/segments.h
index deeaf76ccbc..1c1ddee864f 100644
--- a/sys/i386/include/segments.h
+++ b/sys/i386/include/segments.h
@@ -257,6 +257,7 @@ struct region_descriptor {
 #ifdef _KERNEL
 extern int	_default_ldt;
 #ifdef XEN
+extern struct proc_ldt default_proc_ldt;
 extern union descriptor *gdt;
 extern union descriptor *ldt;
 #else