[PATCH] uml: maintain own LDT entries

Patch imlements full LDT handling in SKAS:
 * UML holds it's own LDT table, used to deliver data on
   modify_ldt(READ)
 * UML disables the default_ldt, inherited from the host (SKAS3)
   or resets LDT entries, set by host's clib and inherited in
   SKAS0
 * A new global variable skas_needs_stub is inserted, that
   can be used to decide, whether stub-pages must be supported
   or not.
 * Uses the syscall-stub to replace missing PTRACE_LDT (therefore,
   write_ldt_entry needs to be modified)

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/kernel/skas/mem.c b/arch/um/kernel/skas/mem.c
index 147466d..88ab96c 100644
--- a/arch/um/kernel/skas/mem.c
+++ b/arch/um/kernel/skas/mem.c
@@ -20,7 +20,7 @@
 	*task_size_out = CONFIG_HOST_TASK_SIZE;
 #else
 	*host_size_out = top;
-	if (proc_mm && ptrace_faultinfo)
+	if (!skas_needs_stub)
 		*task_size_out = top;
 	else *task_size_out = CONFIG_STUB_START & PGDIR_MASK;
 #endif