[ARM] ptrace: clean up single stepping support

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

arch/arm/kernel/ptrace.c

@@ -457,13 +457,10 @@ void ptrace_cancel_bpt(struct task_struct *child)
 
 /*
  * Called by kernel/ptrace.c when detaching..
- *
- * Make sure the single step bit is not set.
  */
 void ptrace_disable(struct task_struct *child)
 {
-	child->ptrace &= ~PT_SINGLESTEP;
-	ptrace_cancel_bpt(child);
+	single_step_disable(child);
 }
 
 /*
@@ -712,9 +709,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 			else
 				clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 			child->exit_code = data;
-			/* make sure single-step breakpoint is gone. */
-			child->ptrace &= ~PT_SINGLESTEP;
-			ptrace_cancel_bpt(child);
+			single_step_disable(child);
 			wake_up_process(child);
 			ret = 0;
 			break;
@@ -725,9 +720,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 		 * exit.
 		 */
 		case PTRACE_KILL:
-			/* make sure single-step breakpoint is gone. */
-			child->ptrace &= ~PT_SINGLESTEP;
-			ptrace_cancel_bpt(child);
+			single_step_disable(child);
 			if (child->exit_state != EXIT_ZOMBIE) {
 				child->exit_code = SIGKILL;
 				wake_up_process(child);
@@ -742,7 +735,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 			ret = -EIO;
 			if (!valid_signal(data))
 				break;
-			child->ptrace |= PT_SINGLESTEP;
+			single_step_enable(child);
 			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 			child->exit_code = data;
 			/* give it a chance to run. */

arch/arm/kernel/ptrace.h

@@ -7,6 +7,45 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include <linux/ptrace.h>
+
 extern void ptrace_cancel_bpt(struct task_struct *);
 extern void ptrace_set_bpt(struct task_struct *);
 extern void ptrace_break(struct task_struct *, struct pt_regs *);
+
+/*
+ * make sure single-step breakpoint is gone.
+ */
+static inline void single_step_disable(struct task_struct *task)
+{
+	task->ptrace &= ~PT_SINGLESTEP;
+	ptrace_cancel_bpt(task);
+}
+
+static inline void single_step_enable(struct task_struct *task)
+{
+	task->ptrace |= PT_SINGLESTEP;
+}
+
+/*
+ * Send SIGTRAP if we're single-stepping
+ */
+static inline void single_step_trap(struct task_struct *task)
+{
+	if (task->ptrace & PT_SINGLESTEP) {
+		ptrace_cancel_bpt(task);
+		send_sig(SIGTRAP, task, 1);
+	}
+}
+
+static inline void single_step_clear(struct task_struct *task)
+{
+	if (task->ptrace & PT_SINGLESTEP)
+		ptrace_cancel_bpt(task);
+}
+
+static inline void single_step_set(struct task_struct *task)
+{
+	if (task->ptrace & PT_SINGLESTEP)
+		ptrace_set_bpt(task);
+}

arch/arm/kernel/signal.c

@@ -9,7 +9,6 @@
  */
 #include <linux/errno.h>
 #include <linux/signal.h>
-#include <linux/ptrace.h>
 #include <linux/personality.h>
 #include <linux/freezer.h>
 
@@ -285,11 +284,7 @@ asmlinkage int sys_sigreturn(struct pt_regs *regs)
 	if (restore_sigframe(regs, frame))
 		goto badframe;
 
-	/* Send SIGTRAP if we're single-stepping */
-	if (current->ptrace & PT_SINGLESTEP) {
-		ptrace_cancel_bpt(current);
-		send_sig(SIGTRAP, current, 1);
-	}
+	single_step_trap(current);
 
 	return regs->ARM_r0;
 
@@ -324,11 +319,7 @@ asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 	if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 		goto badframe;
 
-	/* Send SIGTRAP if we're single-stepping */
-	if (current->ptrace & PT_SINGLESTEP) {
-		ptrace_cancel_bpt(current);
-		send_sig(SIGTRAP, current, 1);
-	}
+	single_step_trap(current);
 
 	return regs->ARM_r0;
 
@@ -644,14 +635,12 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 	if (try_to_freeze())
 		goto no_signal;
 
-	if (current->ptrace & PT_SINGLESTEP)
-		ptrace_cancel_bpt(current);
+	single_step_clear(current);
 
 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 	if (signr > 0) {
 		handle_signal(signr, &ka, &info, oldset, regs, syscall);
-		if (current->ptrace & PT_SINGLESTEP)
-			ptrace_set_bpt(current);
+		single_step_set(current);
 		return 1;
 	}
 
@@ -705,8 +694,7 @@ static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 			restart_syscall(regs);
 		}
 	}
-	if (current->ptrace & PT_SINGLESTEP)
-		ptrace_set_bpt(current);
+	single_step_set(current);
 	return 0;
 }