WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/mm/as.c

 #include <arch.h>
 #include <print.h>
 as_operations_t *as_operations = NULL;
+/** Address space lock. It protects inactive_as_with_asid_head. */
+SPINLOCK_INITIALIZE(as_lock);
+/**
+ * This list contains address spaces that are not active on any
+ * processor and that have valid ASID.
+ */
+LIST_INITIALIZE(inactive_as_with_asid_head);
 /** Kernel address space. */
 as_t *AS_KERNEL = NULL;
 static int get_area_flags(as_area_t *a);
 as_t *as_create(int flags)
+{
     as_t *as;
     as = (as_t *) malloc(sizeof(as_t), 0);
-    list_initialize(&as->as_with_asid_link);
+    link_initialize(&as->inactive_as_with_asid_link);
     spinlock_initialize(&as->lock, "as_lock");
     list_initialize(&as->as_area_head);
     if (flags & FLAG_AS_KERNEL)
         as->asid = ASID_KERNEL;
     else
         as->asid = ASID_INVALID;
+    as->refcount = 0;
     as->page_table = page_table_create(flags);
     return as;
+}
     spinlock_unlock(&AS->lock);
     return 1;
+}
-/** Install address space on CPU.
+/** Switch address spaces.
+ *
+ * @param old Old address space or NULL.
- * @param as Address space.
+ * @param new New address space.
  */
-void as_install(as_t *as)
+void as_switch(as_t *old, as_t *new)
+{
     ipl_t ipl;
-    asid_install(as);
+    bool needs_asid = false;
     ipl = interrupts_disable();
-    spinlock_lock(&as->lock);
+    spinlock_lock(&as_lock);
+    /*
+     * First, take care of the old address space.
+     */
+    if (old) {
+        spinlock_lock(&old->lock);
-    SET_PTL0_ADDRESS(as->page_table);
+        ASSERT(old->refcount);
+        if((--old->refcount == 0) && (old != AS_KERNEL)) {
+            /*
+             * The old address space is no longer active on
+             * any processor. It can be appended to the
+             * list of inactive address spaces with assigned
+             * ASID.
+             */
+             ASSERT(old->asid != ASID_INVALID);
+             list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
+        }
-    spinlock_unlock(&as->lock);
+        spinlock_unlock(&old->lock);
+    }
+    /*
+     * Second, prepare the new address space.
+     */
-    interrupts_restore(ipl);
+    spinlock_lock(&new->lock);
+    if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
+        if (new->asid != ASID_INVALID)
+            list_remove(&new->inactive_as_with_asid_link);
+        else
+            needs_asid = true;  /* defer call to asid_get() until new->lock is released */
+    }
+    SET_PTL0_ADDRESS(new->page_table);
+    spinlock_unlock(&new->lock);
+    if (needs_asid) {
+        /*
+         * Allocation of new ASID was deferred
+         * until now in order to avoid deadlock.
+         */
+        asid_t asid;
+        asid = asid_get();
+        spinlock_lock(&new->lock);
+        new->asid = asid;
+        spinlock_unlock(&new->lock);
+    }
+    spinlock_unlock(&as_lock);
+    interrupts_restore(ipl);
     /*
      * Perform architecture-specific steps.
      * (e.g. write ASID to hardware register etc.)
      */
-    as_install_arch(as);
+    as_install_arch(new);
-    AS = as;
+    AS = new;
+}
 /** Compute flags for virtual address translation subsytem.
+ *
  * The address space area must be locked.

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/as.c – Rev 822 → 823