Changeset 560b81c in mainline for kernel/generic/src

Timestamp:

2016-09-17T15:09:40Z (9 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

ae66564

Parents:

97b8ca9

Message:

Make sure to test the present bit of the found PTE

By design, page_mapping_find() can return true and a copy of a PTE
which is not present. It is therefore necessary to test the found PTE
by PTE_PRESENT() macro.

Location:

kernel/generic/src

Files:

• ipc/ops/pagein.c (modified) (1 diff)
• mm/as.c (modified) (1 diff)
• mm/page.c (modified) (1 diff)

kernel/generic/src/ipc/ops/pagein.c

@@ -53 +53 @@
                 bool found = page_mapping_find(AS, IPC_GET_ARG1(answer->data),
                     false, &pte);
-                if (found) {
+                if (found & PTE_PRESENT(&pte)) {
                         frame = PTE_GET_FRAME(&pte);
                         pfn_t pfn = ADDR2PFN(frame);

kernel/generic/src/mm/as.c

@@ -1457 +1457 @@
         pte_t pte;
         bool found = page_mapping_find(AS, page, false, &pte);
-        if (found) {
-                if (PTE_PRESENT(&pte)) {
-                        if (((access == PF_ACCESS_READ) && PTE_READABLE(&pte)) ||
-                            (access == PF_ACCESS_WRITE && PTE_WRITABLE(&pte)) ||
-                            (access == PF_ACCESS_EXEC && PTE_EXECUTABLE(&pte))) {
-                                page_table_unlock(AS, false);
-                                mutex_unlock(&area->lock);
-                                mutex_unlock(&AS->lock);
-                                return AS_PF_OK;
-                        }
+        if (found && PTE_PRESENT(&pte)) {
+                if (((access == PF_ACCESS_READ) && PTE_READABLE(&pte)) ||
+                    (access == PF_ACCESS_WRITE && PTE_WRITABLE(&pte)) ||
+                    (access == PF_ACCESS_EXEC && PTE_EXECUTABLE(&pte))) {
+                        page_table_unlock(AS, false);
+                        mutex_unlock(&area->lock);
+                        mutex_unlock(&AS->lock);
+                        return AS_PF_OK;
                 }
         }

kernel/generic/src/mm/page.c

@@ -142 +142 @@
  * @param[out] pte Structure that will receive a copy of the found PTE.
  *
- * @return True if the mapping was found, false otherwise.
+ * @return True if a valid PTE is returned, false otherwise. Note that
+ *         the PTE is not guaranteed to be present.
  */
 NO_TRACE bool page_mapping_find(as_t *as, uintptr_t page, bool nolock,