[ARM] Add identifying number for non-rt sigframe

GDB couldn't reliably tell the difference between the old and new
non-rt sigframes, so provide it with a number at the beginning which
will never appear in the old sigframe, and hence provide gdb with a
reliable way to tell the two apart.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 962851144099..c0ba8afee42f 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -470,6 +470,11 @@ setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *reg
         if (!frame)
                 return 1;
 
+        /*
+         * Set uc.uc_flags to a value which sc.trap_no would never have.
+         */
+        __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
+
         err |= setup_sigframe(frame, regs, set);
         if (err == 0)
                 err = setup_return(regs, ka, frame->retcode, frame, usig);