[IA64] Don't forget to initialize PKStk for kernel-threads

Kernel-threads had both pUStk and pKStk set to FALSE, which was
unintentional.  I don't think the bug has shown any ill effects, but
it's clearly wrong and could come around to bite us later, so let's
fix it now.  Depends on the previous patch to clean up C usage of the
global/root-function predicates.
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/process.c

@@ -40,6 +40,8 @@
 #include <asm/unwind.h>
 #include <asm/user.h>
 
+#include "entry.h"
+
 #ifdef CONFIG_PERFMON
 # include <asm/perfmon.h>
 #endif
@@ -667,7 +669,7 @@ kernel_thread (int (*fn)(void *), void *arg, unsigned long flags)
 	regs.pt.cr_ifs = 1UL << 63;		/* mark as valid, empty frame */
 	regs.sw.ar_fpsr = regs.pt.ar_fpsr = ia64_getreg(_IA64_REG_AR_FPSR);
 	regs.sw.ar_bspstore = (unsigned long) current + IA64_RBS_OFFSET;
-
+	regs.sw.pr = (1 << PRED_KERNEL_STACK);
 	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs.pt, 0, NULL, NULL);
 }
 EXPORT_SYMBOL(kernel_thread);