[Blackfin] arch: disable single stepping when delivering a signal

When delivering a signal, disable single stepping but call
ptrace_notify if it was enabled before. The idea was taken
from the x86 port.

Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/signal.c b/arch/blackfin/kernel/signal.c
index cb9d883d493c..dbc3bbf846be 100644
--- a/arch/blackfin/kernel/signal.c
+++ b/arch/blackfin/kernel/signal.c
@@ -42,6 +42,9 @@
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
+/* Location of the trace bit in SYSCFG. */
+#define TRACE_BITS 0x0001
+
 struct fdpic_func_descriptor {
         unsigned long   text;
         unsigned long   GOT;
@@ -225,6 +228,16 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
         regs->r1 = (unsigned long)(&frame->info);
         regs->r2 = (unsigned long)(&frame->uc);
 
+        /*
+         * Clear the trace flag when entering the signal handler, but
+         * notify any tracer that was single-stepping it. The tracer
+         * may want to single-step inside the handler too.
+         */
+        if (regs->syscfg & TRACE_BITS) {
+                regs->syscfg &= ~TRACE_BITS;
+                ptrace_notify(SIGTRAP);
+        }
+
         return 0;
 
  give_sigsegv: