arm: 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 and the single stepping disable only happens if the
tracee process isn't a zombie yet, which is consistent with all
architectures using the modern ptrace code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 12 insertions, 62 deletions

diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 08f899fb76a6..3f562a7c0a99 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -452,12 +452,23 @@ void ptrace_cancel_bpt(struct task_struct *child)
                 clear_breakpoint(child, &child->thread.debug.bp[i]);
 }
 
+void user_disable_single_step(struct task_struct *task)
+{
+        task->ptrace &= ~PT_SINGLESTEP;
+        ptrace_cancel_bpt(task);
+}
+
+void user_enable_single_step(struct task_struct *task)
+{
+        task->ptrace |= PT_SINGLESTEP;
+}
+
 /*
  * Called by kernel/ptrace.c when detaching..
  */
 void ptrace_disable(struct task_struct *child)
 {
-        single_step_disable(child);
+        user_disable_single_step(child);
 }
 
 /*
@@ -753,53 +764,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                         ret = ptrace_write_user(child, addr, data);
                         break;
 
-                /*
-                 * continue/restart and stop at next (return from) syscall
-                 */
-                case PTRACE_SYSCALL:
-                case PTRACE_CONT:
-                        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;
-                        single_step_disable(child);
-                        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:
-                        single_step_disable(child);
-                        if (child->exit_state != EXIT_ZOMBIE) {
-                                child->exit_code = SIGKILL;
-                                wake_up_process(child);
-                        }
-                        ret = 0;
-                        break;
-
-                /*
-                 * execute single instruction.
-                 */
-                case PTRACE_SINGLESTEP:
-                        ret = -EIO;
-                        if (!valid_signal(data))
-                                break;
-                        single_step_enable(child);
-                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-                        child->exit_code = data;
-                        /* give it a chance to run. */
-                        wake_up_process(child);
-                        ret = 0;
-                        break;
-
                 case PTRACE_GETREGS:
                         ret = ptrace_getregs(child, (void __user *)data);
                         break;
diff --git a/arch/arm/kernel/ptrace.h b/arch/arm/kernel/ptrace.h
index def3b6184a79..3926605b82ea 100644
--- a/arch/arm/kernel/ptrace.h
+++ b/arch/arm/kernel/ptrace.h
@@ -14,20 +14,6 @@ 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)