Merge master.kernel.org:/home/rmk/linux-2.6-serial

[powerpc.git] / arch / s390 / kernel / process.c

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 2ff90a1..008c745 100644 (file)
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -58,10 +58,18 @@ asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
  */
 unsigned long thread_saved_pc(struct task_struct *tsk)
 {
-       struct stack_frame *sf;
+       struct stack_frame *sf, *low, *high;
 
-       sf = (struct stack_frame *) tsk->thread.ksp;
-       sf = (struct stack_frame *) sf->back_chain;
+       if (!tsk || !task_stack_page(tsk))
+               return 0;
+       low = task_stack_page(tsk);
+       high = (struct stack_frame *) task_pt_regs(tsk);
+       sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
+       if (sf <= low || sf > high)
+               return 0;
+       sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
+       if (sf <= low || sf > high)
+               return 0;
        return sf->gprs[8];
 }