sh: Fix ptrace hw_breakpoint handling

Since commit 34d0b5af50a063cded842716633501b38ff815fb it is no longer
possible to debug an application using singlestep. The old commit
converted singlestep handling via ptrace to hw_breakpoints. The
hw_breakpoint is disabled when an event is triggered and not re-enabled
again. This patch re-enables the existing hw_breakpoint before the
existing breakpoint is reused.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
Cc: stable@kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/ptrace_32.c

@@ -101,6 +101,8 @@ static int set_single_step(struct task_struct *tsk, unsigned long addr)
 
 		attr = bp->attr;
 		attr.bp_addr = addr;
+		/* reenable breakpoint */
+		attr.disabled = false;
 		err = modify_user_hw_breakpoint(bp, &attr);
 		if (unlikely(err))
 			return err;