Remove the current PTRACE_EVENT_VFORK_DONE logic, it doesn't really
work anyway.
I failed to finish the re-implementation today, hopefully will complete
on weekend. But I have 2 questions:
1. I assume that, on every arch, we alway check TIF_NOTIFY_RESUME
and TIF_SIGPENDING before TIF_SYSCALL_TRACE, right?
IOW, can I assume that syscall_trace_leave() should not be called
before utrace_resume() or utrace_get_signal() ?
This is true (afacs) for x86, but I am not sure about other
arches.
2. We have to play tricks because there is no reporting loop
tracehook_report_vfork_done().
Why? I agree, UTRACE_EVENT(VFROKDONE) is meaningless because
we are going to return from syscall soon and the tracer can
see this event "for free".
But perhaps there is another reason I missed? And, otoh,
why do we have PT_TRACE_VFORK_DONE ? If it is in fact useful,
then perhaps UTRACE_EVENT(VFROKDONE) is useful too?
Just curious, and confused a bit.
---
kernel/ptrace.c | 55 +------------------------------------------------------
1 file changed, 1 insertion(+), 54 deletions(-)
--- PU/kernel/ptrace.c~30_KILL_VFORKDONE_LOGIC 2009-09-12 00:59:10.000000000
+0200
+++ PU/kernel/ptrace.c 2009-09-12 01:04:59.000000000 +0200
@@ -230,22 +230,6 @@ static u32 ptrace_report_clone(enum utra
struct ptrace_context *context = ptrace_context(engine);
int event;
- if ((clone_flags & CLONE_VFORK) &&
- (context->options & PTRACE_O_TRACEVFORKDONE)) {
- /*
- * Stash the child PID for a PTRACE_EVENT_VFORK_DONE report,
- * even if we don't report this clone event itself. Mark
- * that we vfork'd even if we don't actually stop here, so
- * that we'll know to do the vfork-done report. (This
- * matters when is PTRACE_O_TRACEVFORKDONE set but
- * PTRACE_O_TRACEVFORK is not set.)
- */
- int rc = utrace_control(parent, engine, UTRACE_REPORT);
- WARN_ON(rc);
- parent->ptrace_message = child->pid;
- ptrace_set_stop_event(parent, PTRACE_EVENT_VFORK);
- }
-
if (clone_flags & CLONE_UNTRACED)
return UTRACE_RESUME;
@@ -298,24 +282,6 @@ static u32 ptrace_report_syscall_entry(u
return ptrace_report_syscall(UTRACE_SYSCALL_RUN, engine, task);
}
-/*
- * Report a vfork-done event to precede another event report.
- * There is no utrace callback associated directly with vfork-done.
- * Instead, after seeing CLONE_VFORK in report_clone() we notice
- * the following syscall-exit, signal, or quiesce callback and
- * inject the PTRACE_EVENT_VFORK_DONE stop there.
- */
-static u32 ptrace_report_vfork_done(struct task_struct *task)
-{
- /*
- * We got here after a vfork, when vfork-done tracing
- * was enabled.
- */
- ptrace_set_stop_event(task, 0);
- return utrace_ptrace_event(task, PTRACE_EVENT_VFORK_DONE,
- task->ptrace_message);
-}
-
static void ptrace_wake_up(struct utrace_engine *engine,
struct task_struct *tracee,
enum utrace_resume_action action)
@@ -370,9 +336,6 @@ static u32 ptrace_resumed(struct task_st
{
enum utrace_resume_action resume = ptrace_resume_action(task);
- if (unlikely(ptrace_stop_event(task) == PTRACE_EVENT_VFORK))
- return UTRACE_SIGNAL_REPORT | ptrace_report_vfork_done(task);
-
/*
* If we're stopping, or we haven't reported any signal,
* then we're all done for now.
@@ -480,9 +443,6 @@ static u32 ptrace_report_quiesce(u32 act
if (event == 0) {
task->last_siginfo = NULL;
-
- if (unlikely(ptrace_stop_event(task) == PTRACE_EVENT_VFORK))
- return ptrace_report_vfork_done(task);
}
return ptrace_resume_action(task);
@@ -1090,20 +1050,7 @@ static int ptrace_resume(struct task_str
break;
case PTRACE_EVENT_VFORK:
- /*
- * For this event, @data is ignored. We did have a
- * utrace stop right after, so on resuming there
- * can be a normal syscall-exit stop next if needed.
- * But we may need to simulate a vfork-done stop,
- * so we leave the marker in place.
- */
- data = 0;
- event = 0;
- if (context->options & PTRACE_O_TRACEVFORKDONE) {
- ptrace_set_stop_event(child,
- PTRACE_EVENT_VFORK);
- action = UTRACE_REPORT;
- }
+ WARN_ON(1);
break;
}
