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

 /** Kernel address space. */
 as_t *AS_KERNEL = NULL;
 static int get_area_flags(as_area_t *a);
+static as_area_t *find_area_and_lock(as_t *as, __address va);
 /** Initialize address space subsystem. */
 void as_init(void)
+{
     as_arch_init();
  * @param page Virtual page within the area.
  * @param frame Physical frame to which page will be mapped.
  */
 void as_set_mapping(as_t *as, __address page, __address frame)
+{
-    as_area_t *a, *area = NULL;
+    as_area_t *area;
-    link_t *cur;
     ipl_t ipl;
     ipl = interrupts_disable();
     spinlock_lock(&as->lock);
-    /*
-     * First, try locate an area.
-     */
-    for (cur = as->as_area_head.next; cur != &as->as_area_head; cur = cur->next) {
-        a = list_get_instance(cur, as_area_t, link);
+    area = find_area_and_lock(as, page);
-        spinlock_lock(&a->lock);
-        if ((page >= a->base) && (page < a->base + a->size * PAGE_SIZE)) {
-            area = a;
-            break;
-        }
-        spinlock_unlock(&a->lock);
-    }
     if (!area) {
         panic("page not part of any as_area\n");
+    }
-    /*
-     * Note: area->lock is held.
-     */
     page_mapping_insert(as, page, frame, get_area_flags(area));
     spinlock_unlock(&area->lock);
     spinlock_unlock(&as->lock);
     interrupts_restore(ipl);
+ *
  * @return 0 on page fault, 1 on success.
  */
 int as_page_fault(__address page)
+{
-    link_t *cur;
-    as_area_t *a, *area = NULL;
+    as_area_t *area;
     __address frame;
     ASSERT(AS);
     spinlock_lock(&AS->lock);
-    /*
-     * Search this areas of this address space for presence of 'page'.
-     */
-    for (cur = AS->as_area_head.next; cur != &AS->as_area_head; cur = cur->next) {
-        a = list_get_instance(cur, as_area_t, link);
-        spinlock_lock(&a->lock);
-        if ((page >= a->base) && (page < a->base + a->size * PAGE_SIZE)) {
-            /*
-             * We found the area containing 'page'.
+    area = find_area_and_lock(AS, page);
-             * TODO: access checking
-             */
-            area = a;
-            break;
-        }
-        spinlock_unlock(&a->lock);
-    }
     if (!area) {
         /*
          * No area contained mapping for 'page'.
          * Signal page fault to low-level handler.
          */
         spinlock_unlock(&AS->lock);
         return 0;
+    }
     /*
-     * Note: area->lock is held.
-     */
-    /*
      * In general, there can be several reasons that
      * can have caused this fault.
+     *
      * - non-existent mapping: the area is a scratch
      *   area (e.g. stack) and so far has not been
         ASSERT(as_operations);
         ASSERT(as_operations->page_table_create);
         return as_operations->page_table_create(flags);
+}
+/** Find address space area and change it.
+ *
+ * @param as Address space.
+ * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
+ * @param size New size of the virtual memory block starting at address.
+ * @param flags Flags influencing the remap operation. Currently unused.
+ *
+ * @return address on success, (__address) -1 otherwise.
+ */
+__address as_remap(as_t *as, __address address, size_t size, int flags)
+{
+    as_area_t *area = NULL;
+    ipl_t ipl;
+    size_t pages;
+    ipl = interrupts_disable();
+    spinlock_lock(&as->lock);
+    /*
+     * Locate the area.
+     */
+    area = find_area_and_lock(as, address);
+    if (!area) {
+        spinlock_unlock(&as->lock);
+        return (__address) -1;
+    }
+    pages = SIZE2FRAMES((address - area->base) + size);
+    if (pages < area->size) {
+        int i;
+        /*
+         * Shrinking the area.
+         */
+        for (i = pages; i < area->size; i++) {
+            pte_t *pte;
+            /*
+             * Releasing physical memory.
+             * This depends on the fact that the memory was allocated using frame_alloc().
+             */
+            pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
+            if (pte) {
+                ASSERT(PTE_PRESENT(pte));
+                frame_free(ADDR2PFN(PTE_GET_FRAME(pte)));
+            }
+            page_mapping_remove(as, area->base + i*PAGE_SIZE);
+        }
+        /*
+         * Invalidate TLB's.
+         */
+        tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->size - pages);
+        tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->size - pages);
+        tlb_shootdown_finalize();
+    } else {
+        /*
+         * Growing the area.
+         */
+        area->size = size;
+    }
+    spinlock_unlock(&area->lock);
+    spinlock_unlock(&as->lock);
+    interrupts_restore(ipl);
+    return address;
+}
+/** Find address space area and lock it.
+ *
+ * The address space must be locked and interrupts must be disabled.
+ *
+ * @param as Address space.
+ * @param va Virtual address.
+ *
+ * @return Locked address space area containing va on success or NULL on failure.
+ */
+as_area_t *find_area_and_lock(as_t *as, __address va)
+{
+    link_t *cur;
+    as_area_t *a;
+    for (cur = as->as_area_head.next; cur != &as->as_area_head; cur = cur->next) {
+        a = list_get_instance(cur, as_area_t, link);
+        spinlock_lock(&a->lock);
+        if ((va >= a->base) && (va < a->base + a->size * PAGE_SIZE))
+             return a;
+        spinlock_unlock(&a->lock);
+    }
+    return NULL;
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/as.c – Rev 973 → 977