mn10300: signal stack fix

This fixes a signal stack handling problem in the MN10300 arch.  When new
threads are cloned with CLONE_VM, they don't inherit the alternate signal
stack.  They do share the signal flags, though.  When deciding whether to
use an alternate stack, the arch code needs to check to make sure the task
struct contains a valid alternate stack.  This patch fixes the MN10300
arch by using the sas_ss_flags() test provided by sched.h rather than the
on_sig_stack() test which is insufficient by itself.

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/mn10300/kernel/signal.c b/arch/mn10300/kernel/signal.c
index a21f43bc68e269cf412e6ae3b0c0293c0dcd96c0..717db14c2cc32d8905a45e6cfae4bf2a00d38abd 100644 (file)
--- a/arch/mn10300/kernel/signal.c
+++ b/arch/mn10300/kernel/signal.c
@@ -264,7 +264,7 @@ static inline void __user *get_sigframe(struct k_sigaction *ka,
 
        /* this is the X/Open sanctioned signal stack switching.  */
        if (ka->sa.sa_flags & SA_ONSTACK) {
-               if (!on_sig_stack(sp))
+               if (sas_ss_flags(sp) == 0)
                        sp = current->sas_ss_sp + current->sas_ss_size;
        }