Blackfin: use generic ptrace_resume code

Use the generic ptrace_resume code for PTRACE_SYSCALL, PTRACE_CONT,
PTRACE_KILL and PTRACE_SINGLESTEP.  This implies defining
arch_has_single_step in <asm/ptrace.h> and implementing the
user_enable_single_step and user_disable_single_step functions, which
also causes the breakpoint information to be cleared on fork, which
could be considered a bug fix.

Also the TIF_SYSCALL_TRACE thread flag is now cleared on PTRACE_KILL
which it previously wasn't which is consistent with all architectures
using the modern ptrace code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/ptrace.c

@@ -354,50 +354,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 		ret = put_reg(child, addr, data);
 		break;
 
-	case PTRACE_SYSCALL:	/* continue and stop at next (return from) syscall */
-	case PTRACE_CONT:	/* restart after signal. */
-		pr_debug("ptrace: syscall/cont\n");
-
-		ret = -EIO;
-		if (!valid_signal(data))
-			break;
-		if (request == PTRACE_SYSCALL)
-			set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-		else
-			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-		child->exit_code = data;
-		ptrace_disable(child);
-		pr_debug("ptrace: before wake_up_process\n");
-		wake_up_process(child);
-		ret = 0;
-		break;
-
-	/*
-	 * make the child exit.  Best I can do is send it a sigkill.
-	 * perhaps it should be put in the status that it wants to
-	 * exit.
-	 */
-	case PTRACE_KILL:
-		ret = 0;
-		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
-			break;
-		child->exit_code = SIGKILL;
-		ptrace_disable(child);
-		wake_up_process(child);
-		break;
-
-	case PTRACE_SINGLESTEP:	/* set the trap flag. */
-		pr_debug("ptrace: single step\n");
-		ret = -EIO;
-		if (!valid_signal(data))
-			break;
-		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-		ptrace_enable(child);
-		child->exit_code = data;
-		wake_up_process(child);
-		ret = 0;
-		break;
-
 	case PTRACE_GETREGS:
 		/* Get all gp regs from the child. */
 		ret = ptrace_getregs(child, datap);