Changeset 609a417 in mainline

Timestamp:

2012-07-01T22:28:15Z (12 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

7d68da80

Parents:

0d8269b

Message:

Add write memory barriers to pt_mapping_insert() so that setting a new
page table level is separated from marking it present in the previous
level.

This is to make sure that a concurrent hardware page table walk or
pt_page_find() will see the new level only after it is fully
initialized.

File:

• kernel/genarch/src/mm/page_pt.c (modified) (5 diffs)

kernel/genarch/src/mm/page_pt.c

@@ -43 +43 @@
 #include <arch/mm/page.h>
 #include <arch/mm/as.h>
+#include <arch/barrier.h>
 #include <typedefs.h>
 #include <arch/asm.h>
@@ -86 +87 @@
                 SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));
                 SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page),
-                    PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
+                    PAGE_NOT_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
                     PAGE_WRITE);
+                write_barrier();
+                SET_PTL1_PRESENT(ptl0, PTL0_INDEX(page));
         }
         
@@ -98 +101 @@
                 SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));
                 SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page),
-                    PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
+                    PAGE_NOT_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
                     PAGE_WRITE);
+                write_barrier();
+                SET_PTL2_PRESENT(ptl1, PTL1_INDEX(page));       
         }
         
@@ -110 +115 @@
                 SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));
                 SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page),
-                    PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
+                    PAGE_NOT_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
                     PAGE_WRITE);
+                write_barrier();
+                SET_PTL3_PRESENT(ptl2, PTL2_INDEX(page));
         }
         
@@ -117 +124 @@
         
         SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);
-        SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);
+        SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags | PAGE_NOT_PRESENT);
+        write_barrier();
+        SET_FRAME_PRESENT(ptl3, PTL3_INDEX(page));
 }