Changeset 0b37882 in mainline for uspace/lib/c/generic/as.c

Timestamp:

2011-02-03T21:14:23Z (13 years ago)

Author:

Martin Decky <martin@…>

Branches:

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

Children:

17aca1c, 6a343bdf, cf2af94

Parents:

d88218b (diff), ae6f303 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

memory management work

• implement as_get_mappable_page() as a new syscall (SYS_AS_GET_UNMAPPED_AREA), the kernel has a full knowledge of the address space areas, there is no need to duplicate this management in uspace)
• make sure all address space/address space area manipulating functions use proper page alignment on base addresses and sizes (discrepancy with respect to this caused inconsistent behaviour, although no fatal bugs were probably present)
• add forgotten tests (area != avoid) to check_area_conflicts()
• unify size/page conversions (use always use bitwise shifts by PAGE_WIDTH)
• new uspace heap allocator
  • basic next fit algorithm for better scalability (there is still space for optimizations)
  • support for multiple discontinuous heap areas (inspired by Jiri Tlach's implementation in lp:~jiri-tlach/helenos/nommu, but independent)
  • the "_heap" linker script symbol has been removed, the initial heap area is allocated according to as_get_mappable_page() (which uses the address of entry as the lower bound of the address space area base)
  • the hardwired 1 GB (4 GB respectivelly) heap size limit has been removed
  • the heap areas can be freely intermixed with other address space areas (e.g. mapped physical memory of devices, shared memory, etc.), the address space holes can be reused later (but still merging of adjunct address space areas is missing)
• minor cstyle changes

File:

• uspace/lib/c/generic/as.c (modified) (2 diffs)

uspace/lib/c/generic/as.c

@@ -40 +40 @@
 #include <bitops.h>
 #include <malloc.h>
-
-/** Last position allocated by as_get_mappable_page */
-static uintptr_t last_allocated = 0;
+#include "private/libc.h"
 
 /** Create address space area.
@@ -103 +101 @@
 }
 
-/** Return pointer to some unmapped area, where fits new as_area
+/** Return pointer to unmapped address space area
  *
  * @param size Requested size of the allocation.
  *
- * @return pointer to the beginning
+ * @return Pointer to the beginning of unmapped address space area.
  *
  */
 void *as_get_mappable_page(size_t size)
 {
-        if (size == 0)
-                return NULL;
-        
-        size_t sz = 1 << (fnzb(size - 1) + 1);
-        if (last_allocated == 0)
-                last_allocated = get_max_heap_addr();
-        
-        /*
-         * Make sure we allocate from naturally aligned address.
-         */
-        uintptr_t res = ALIGN_UP(last_allocated, sz);
-        last_allocated = res + ALIGN_UP(size, PAGE_SIZE);
-        
-        return ((void *) res);
+        return (void *) __SYSCALL2(SYS_AS_GET_UNMAPPED_AREA,
+            (sysarg_t) __entry, (sysarg_t) size);
 }