Changeset d0485c6 in mainline for kernel/generic

Timestamp:

2006-12-01T22:10:40Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

3d76996

Parents:

7bf7ef7

Message:

Introduce page colors. So far, only sparc64 uses correct page color bits. Other architectures have a dummy define
specifying zero bits for a page color.

There is a new check of page color in as_area_share(). Because of lack of support for this in the userspace, the
check has been #ifef'ed out.

Location:

kernel/generic

Files:

• include/mm/page.h (modified) (1 diff)
• src/mm/as.c (modified) (2 diffs)

kernel/generic/include/mm/page.h

@@ -67 +67 @@
 #define PAGE_GLOBAL             (1<<PAGE_GLOBAL_SHIFT)
 
+
+/**
+ * Macro for computing page color.
+ */
+#define PAGE_COLOR(va)          (((va) >> PAGE_WIDTH) & ((1 << PAGE_COLOR_BITS) - 1))
+
 /** Page fault access type. */
 enum pf_access {

kernel/generic/src/mm/as.c

@@ -551 +551 @@
  * @param dst_flags_mask Destination address space area flags mask.
  *
- * @return Zero on success or ENOENT if there is no such task or
- *         if there is no such address space area,
- *         EPERM if there was a problem in accepting the area or
- *         ENOMEM if there was a problem in allocating destination
- *         address space area. ENOTSUP is returned if an attempt
- *         to share non-anonymous address space area is detected.
+ * @return Zero on success or ENOENT if there is no such task or if there is no
+ * such address space area, EPERM if there was a problem in accepting the area
+ * or ENOMEM if there was a problem in allocating destination address space
+ * area. ENOTSUP is returned if the address space area backend does not support
+ * sharing. It can be also returned if the architecture uses virtually indexed
+ * caches and the source and destination areas start at pages with different
+ * page colors.
  */
 int as_area_share(as_t *src_as, uintptr_t src_base, size_t acc_size,
@@ -581 +582 @@
         }
         
+#if 0   /* disable the check for now */
+#ifdef CONFIG_VIRT_IDX_CACHE
+        if (PAGE_COLOR(src_area->base) != PAGE_COLOR(dst_base)) {
+                /*
+                 * Refuse to create illegal address alias.
+                 */
+                mutex_unlock(&src_area->lock);
+                mutex_unlock(&src_as->lock);
+                interrupts_restore(ipl);
+                return ENOTSUP;
+        }
+#endif /* CONFIG_VIRT_IDX_CACHE */
+#endif
+
         if (!src_area->backend || !src_area->backend->share) {
                 /*