Changeset fd4d8c0 in mainline for generic/src/mm/as.c

Timestamp:

2006-05-25T21:21:58Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

b31d188

Parents:

baafe71

Message:

Modify as_area_share() to accept destination area flags bitmask from the sender
(i.e. the sender can limit access mode to the shared area for the recipient).
Modify IPC_M_AS_AREA_SEND code to support this. Arguments for sender: arg1=as_area,
arg2=size, arg3=flags_mask.

The mechanism seems to work, but the page fault handlers need to be altered to
distinguish between faults under different access modes.

File:

• generic/src/mm/as.c (modified) (3 diffs)

generic/src/mm/as.c

@@ -459 +459 @@
  * sh_info of the source area.
  * 
- * @param src_as Pointer to source address space
+ * @param src_as Pointer to source address space.
  * @param src_base Base address of the source address space area.
- * @param acc_size Expected size of the source area
- * @param dst_base Target base address
+ * @param acc_size Expected size of the source area.
+ * @param dst_base Target base address.
+ * @param dst_flags_mask Destination address space area flags mask.
  *
  * @return Zero on success or ENOENT if there is no such task or
@@ -472 +473 @@
  */
 int as_area_share(as_t *src_as, __address src_base, size_t acc_size,
-                  __address dst_base)
+                  __address dst_base, int dst_flags_mask)
 {
         ipl_t ipl;
@@ -568 +569 @@
          * attribute set which prevents race condition with
          * preliminary as_page_fault() calls.
-         */
-        dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL, &anon_backend, NULL);
+         * The flags of the source area are masked against dst_flags_mask
+         * to support sharing in less privileged mode.
+         */
+        dst_area = as_area_create(AS, src_flags & dst_flags_mask, src_size, dst_base,
+                                  AS_AREA_ATTR_PARTIAL, &anon_backend, NULL);
         if (!dst_area) {
                 /*