sh64: fix tracing of signals.

This follows the parisc change to ensure that tracehook_signal_handler()
is aware of when we are single-stepping in order to ptrace_notify()
appropriately. While this was implemented for 32-bit SH, sh64 neglected
to make use of TIF_SINGLESTEP when it was folded in with the 32-bit code,
resulting in ptrace_notify() never being called.

As sh64 uses all of the other abstractions already, this simply plugs in
the thread flag in the appropriate enable/disable paths and fixes up the
tracehook notification accordingly. With this in place, sh64 is brought
in line with what 32-bit is already doing.
Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/ptrace_64.c

@@ -133,6 +133,8 @@ void user_enable_single_step(struct task_struct *child)
 	struct pt_regs *regs = child->thread.uregs;
 
 	regs->sr |= SR_SSTEP;	/* auto-resetting upon exception */
+
+	set_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 void user_disable_single_step(struct task_struct *child)
@@ -140,6 +142,8 @@ void user_disable_single_step(struct task_struct *child)
 	struct pt_regs *regs = child->thread.uregs;
 
 	regs->sr &= ~SR_SSTEP;
+
+	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 static int genregs_get(struct task_struct *target,
@@ -454,6 +458,8 @@ asmlinkage long long do_syscall_trace_enter(struct pt_regs *regs)
 
 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 {
+	int step;
+
 	if (unlikely(current->audit_context))
 		audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
 				   regs->regs[9]);
@@ -461,8 +467,9 @@ asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
 	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
 		trace_sys_exit(regs, regs->regs[9]);
 
-	if (test_thread_flag(TIF_SYSCALL_TRACE))
-		tracehook_report_syscall_exit(regs, 0);
+	step = test_thread_flag(TIF_SINGLESTEP);
+	if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+		tracehook_report_syscall_exit(regs, step);
 }
 
 /* Called with interrupts disabled */

arch/sh/kernel/signal_64.c

@@ -118,7 +118,9 @@ static int do_signal(struct pt_regs *regs, sigset_t *oldset)
 			 * clear the TS_RESTORE_SIGMASK flag.
 			 */
 			current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
-			tracehook_signal_handler(signr, &info, &ka, regs, 0);
+
+			tracehook_signal_handler(signr, &info, &ka, regs,
+					test_thread_flag(TIF_SINGLESTEP));
 			return 1;
 		}
 	}