m68k: Simplify the singlestepping handling in signals

Instead of checking the return value of do_signal() we can just do
the work (raise SIGTRAP and clear SR.T1) directly in handle_signal(),
when setting the sigframe up.  Simplifies the assembler glue and is
closer to the way we do it on other targets.

Note that do_delayed_trace does *not* disappear; it's still needed
to deal with single-stepping through syscall, since 68040 doesn't
raise the trace exception at all if the trap exception is pending.
We hit it after returning from sys_...() if TIF_DELAYED_TRACE is
set; all that has changed is that we don't reuse it for "single-step
into the handler" codepath.

As the result, do_signal() doesn't need to return anything anymore.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

2 files changed, 8 insertions, 9 deletions

diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index 3a15a03297a..4e49f577769 100644
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -178,11 +178,7 @@ do_signal_return:
         addql   #4,%sp
         RESTORE_SWITCH_STACK
         addql   #4,%sp
-        tstl    %d0
-        jeq     resume_userspace
-        | when single stepping into handler stop at the first insn
-        btst    #6,%curptr@(TASK_INFO+TINFO_FLAGS+2)
-        jeq     resume_userspace
+        jbra    resume_userspace
 
 do_delayed_trace:
         bclr    #7,%sp@(PT_OFF_SR)      | clear trace bit in SR
diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index fa8200d03de..a18b251fe59 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -978,6 +978,11 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
         if (!(ka->sa.sa_flags & SA_NODEFER))
                 sigaddset(&current->blocked,sig);
         recalc_sigpending();
+
+        if (test_thread_flag(TIF_DELAYED_TRACE)) {
+                regs->sr &= ~0x8000;
+                send_sig(SIGTRAP, current, 1);
+        }
 }
 
 /*
@@ -985,7 +990,7 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
  * want to handle. Thus you cannot kill init even with a SIGKILL even by
  * mistake.
  */
-asmlinkage int do_signal(struct pt_regs *regs)
+asmlinkage void do_signal(struct pt_regs *regs)
 {
         siginfo_t info;
         struct k_sigaction ka;
@@ -1004,7 +1009,7 @@ asmlinkage int do_signal(struct pt_regs *regs)
                 /* Whee!  Actually deliver the signal.  */
                 handle_signal(signr, &ka, &info, oldset, regs);
                 clear_thread_flag(TIF_RESTORE_SIGMASK);
-                return 1;
+                return;
         }
 
         /* Did we come from a system call? */
@@ -1017,6 +1022,4 @@ asmlinkage int do_signal(struct pt_regs *regs)
                 clear_thread_flag(TIF_RESTORE_SIGMASK);
                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
         }
-
-        return 0;
 }