i386: Fix race in multiprocessor ktssfeat-smp2-works

2 files changed, 43 insertions, 41 deletions

diff --git a/i386/i386/io_perm.c b/i386/i386/io_perm.c
index 6db60f73..d9c646fe 100644
--- a/i386/i386/io_perm.c
+++ b/i386/i386/io_perm.c
@@ -266,9 +266,7 @@ i386_io_perm_modify (task_t target_task, io_perm_t io_perm, boolean_t enable)
 
   if (!iopb)
     {
-      simple_unlock (&target_task->machine.iopb_lock);
       iopb = (unsigned char *) kmem_cache_alloc (&machine_task_iopb_cache);
-      simple_lock (&target_task->machine.iopb_lock);
       if (target_task->machine.iopb)
 	{
 	  if (iopb)
@@ -308,9 +306,6 @@ i386_io_perm_modify (task_t target_task, io_perm_t io_perm, boolean_t enable)
       target_task->machine.iopb_size = iopb_size;
     }
 
-#if NCPUS>1
-#warning SMP support missing (notify all CPUs running threads in that of the I/O bitmap change).
-#endif
   if (target_task == current_task())
     update_ktss_iopb (iopb, target_task->machine.iopb_size);
 
diff --git a/i386/i386/pcb.c b/i386/i386/pcb.c
index ef300537..556bf5a3 100644
--- a/i386/i386/pcb.c
+++ b/i386/i386/pcb.c
@@ -48,6 +48,7 @@
 #include <i386/user_ldt.h>
 #include <i386/db_interface.h>
 #include <i386/fpu.h>
+#include <i386/spl.h>
 #include "eflags.h"
 #include "gdt.h"
 #include "ldt.h"
@@ -122,8 +123,8 @@ vm_offset_t stack_detach(thread_t thread)
 #define	curr_gdt(mycpu)		(mp_gdt[mycpu])
 #define	curr_ktss(mycpu)	(mp_ktss[mycpu])
 #else
-#define	curr_gdt(mycpu)		((void)(mycpu), gdt)
-#define	curr_ktss(mycpu)	((void)(mycpu), (struct task_tss *)&ktss)
+#define	curr_gdt(mycpu)		(gdt)
+#define	curr_ktss(mycpu)	((struct task_tss *)&ktss)
 #endif
 
 #define	gdt_desc_p(mycpu,sel) \
@@ -131,6 +132,8 @@ vm_offset_t stack_detach(thread_t thread)
 
 void switch_ktss(pcb_t pcb)
 {
+	spl_t s = splhigh();
+
 	int			mycpu = cpu_number();
     {
 	vm_offset_t		pcb_stack_top;
@@ -222,21 +225,20 @@ void switch_ktss(pcb_t pcb)
         pcb->ims.user_gdt, sizeof pcb->ims.user_gdt);
 #endif /* MACH_PV_DESCRIPTORS */
 
-	db_load_context(pcb);
+	db_set_debug_state(pcb, &pcb->ims.ids)
 
 	/*
 	 * Load the floating-point context, if necessary.
 	 */
 	fpu_load_context(pcb);
 
+	splx(s);
 }
 
-/* If NEW_IOPB is not null, the SIZE denotes the number of bytes in
-   the new bitmap.  Expects iopb_lock to be held.  */
-void
-update_ktss_iopb (unsigned char *new_iopb, io_port_t size)
+static void
+update_ktss_iopb_per_cpu (unsigned char *new_iopb, io_port_t size, int cpu)
 {
-  struct task_tss *tss = curr_ktss (cpu_number ());
+  struct task_tss *tss = curr_ktss (cpu);
 
   if (new_iopb && size > 0)
     {
@@ -249,6 +251,24 @@ update_ktss_iopb (unsigned char *new_iopb, io_port_t size)
     tss->tss.io_bit_map_offset = IOPB_INVAL;
 }
 
+/* If NEW_IOPB is not null, the SIZE denotes the number of bytes in
+   the new bitmap.  Expects iopb_lock to be held per TASK.  */
+void
+update_ktss_iopb (unsigned char *new_iopb, io_port_t size)
+{
+#if NCPUS > 1
+  int slot;
+
+  for (slot = 0; slot < NCPUS; slot++)
+    {
+      if (machine_slot[slot].is_cpu)
+	update_ktss_iopb_per_cpu (new_iopb, size, slot);
+    }
+#else
+  update_ktss_iopb_per_cpu (new_iopb, size, cpu_number());
+#endif
+}
+
 /*
  *	stack_handoff:
  *
@@ -259,8 +279,12 @@ void stack_handoff(
 	thread_t	old,
 	thread_t	new)
 {
-	int		mycpu = cpu_number();
 	vm_offset_t	stack;
+	task_t old_task, new_task;
+	int mycpu;
+	spl_t s;
+
+	mycpu = cpu_number();
 
 	/*
 	 *	Save FP registers if in use.
@@ -270,8 +294,6 @@ void stack_handoff(
 	/*
 	 *	Switch address maps if switching tasks.
 	 */
-    {
-	task_t old_task, new_task;
 
 	if ((old_task = old->task) != (new_task = new->task)) {
 		PMAP_DEACTIVATE_USER(vm_map_pmap(old_task->map),
@@ -279,20 +301,12 @@ void stack_handoff(
 		PMAP_ACTIVATE_USER(vm_map_pmap(new_task->map),
 				   new, mycpu);
 
+		s = splhigh();
 		simple_lock (&new_task->machine.iopb_lock);
-#if NCPUS>1
-#warning SMP support missing (avoid races with io_perm_modify).
-#else
-		/* This optimization only works on a single processor
-		   machine, where old_task's iopb can not change while
-		   we are switching.  */
-		if (old_task->machine.iopb || new_task->machine.iopb)
-#endif
-		  update_ktss_iopb (new_task->machine.iopb,
-				    new_task->machine.iopb_size);
+		update_ktss_iopb (new_task->machine.iopb, new_task->machine.iopb_size);
 		simple_unlock (&new_task->machine.iopb_lock);
+		splx(s);
 	}
-    }
 
 	/*
 	 *	Load the rest of the user state for the new thread
@@ -335,6 +349,10 @@ thread_t switch_context(
 	continuation_t	continuation,
 	thread_t	new)
 {
+	task_t old_task, new_task;
+	int	mycpu = cpu_number();
+	spl_t s;
+
 	/*
 	 *	Save FP registers if in use.
 	 */
@@ -343,9 +361,6 @@ thread_t switch_context(
 	/*
 	 *	Switch address maps if switching tasks.
 	 */
-    {
-	task_t old_task, new_task;
-	int	mycpu = cpu_number();
 
 	if ((old_task = old->task) != (new_task = new->task)) {
 		PMAP_DEACTIVATE_USER(vm_map_pmap(old_task->map),
@@ -353,20 +368,12 @@ thread_t switch_context(
 		PMAP_ACTIVATE_USER(vm_map_pmap(new_task->map),
 				   new, mycpu);
 
+		s = splhigh();
 		simple_lock (&new_task->machine.iopb_lock);
-#if NCPUS>1
-#warning SMP support missing (avoid races with io_perm_modify).
-#else
-		/* This optimization only works on a single processor
-		   machine, where old_task's iopb can not change while
-		   we are switching.  */
-		if (old_task->machine.iopb || new_task->machine.iopb)
-#endif
-		  update_ktss_iopb (new_task->machine.iopb,
-				    new_task->machine.iopb_size);
+		update_ktss_iopb (new_task->machine.iopb, new_task->machine.iopb_size);
 		simple_unlock (&new_task->machine.iopb_lock);
+		splx(s);
 	}
-    }
 
 	/*
 	 *	Load the rest of the user state for the new thread