[PATCH 55] implement the stacked SYSCALL_EXIT event

[Oleg Nesterov]

Change ptrace_resume() to report the artificial SYSCALL_EXIT stop
when needed.

This is trivial, but I am not sure yet what should we do with the
stacked JCTL stops.

ptrace_report_clone() is not exactly right too, will be fixed later.

This and the next patches add another switch(->ev_name), I'll try
to merge them into the single switch() later.

---

 kernel/ptrace.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- PU/kernel/ptrace.c~55_STACKED_EVENTS        2009-10-01 23:06:36.000000000 
+0200
+++ PU/kernel/ptrace.c  2009-10-01 23:32:55.000000000 +0200
@@ -891,6 +891,20 @@ static void do_ptrace_resume(struct utra
                break;
        }
 
+       if (request == PTRACE_SYSCALL) {
+               switch (context->ev_name) {
+               case PTRACE_EVENT_EXEC:
+               case PTRACE_EVENT_FORK:
+               case PTRACE_EVENT_CLONE:
+               case PTRACE_EVENT_VFORK_DONE:
+                       context->ev_name = PTRACE_EVENT_SYSCALL;
+                       context->ev_code = (context->options & 
PTRACE_O_TRACESYSGOOD) ?
+                                               (SIGTRAP | 0x80) : SIGTRAP;
+                       do_ptrace_notify_stop(context, tracee);
+                       return;
+               }
+       }
+
        context->ev_name = 0;
        context->resume = action;
        ptrace_wake_up(engine, tracee, action);