This is the temporary fix for the new step-from-clone.c test-case.
Actually kludge, not the fix. But I don't understand the rationale
behind the current behaviour yet.
So, this test does:
ptrace(PTRACE_SETOPTIONS, PTRACE_O_TRACESYSGOOD);
ptrace(PTRACE_CONT);
// tracee reports PTRACE_EVENT_FORK
ptrace(PTRACE_SINGLESTEP)
Now the tracer expects to get the notification from syscall-exit stop
for "fork ()", but at the same time it expects
assert ((status >> 8) == SIGTRAP);
This looks a bit strange to me, usually PTRACE_O_TRACESYSGOOD adds 0x80.
Yes, I understand why this happens with the vanilla kernel, without
PTRACE_SYSCALL TIF_SYSCALL_FTRACE is not set when syscall_trace_leave()
is called, we got this report due to send_sigtrap().
And send_sigtrap() means we really report the signal, I mean utrace-ptrace
should do send_sigtrap() too, not just report SIGTRAP. We need the valid
context->siginfo which indicates the tracer can change/clear ->si_signo
on resume. And of course, we can't rely on syscall_trace_leave() in this
case, we stop before return to the user-mode after syscall_trace_leave()
was already called.
Oh. I'll fix this later.
---
kernel/ptrace.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- PU/kernel/ptrace.c~55_STEP_IGNORES_TRACESYSGOOD 2009-09-23
21:52:46.000000000 +0200
+++ PU/kernel/ptrace.c 2009-09-23 22:26:59.000000000 +0200
@@ -267,8 +267,9 @@ static void push_syscall_event(struct pt
ev->ev_options = PTRACE_O_TRACE_SYSCALL;
ev->ev_resume = ptrace_resume_syscall;
- ev->ev_code = (context->options & PTRACE_O_TRACESYSGOOD) ?
- (SIGTRAP | 0x80) : SIGTRAP;
+ ev->ev_code = (context->options & PTRACE_O_TRACESYSGOOD) &&
+ (context->resume == UTRACE_RESUME) ?
+ (SIGTRAP | 0x80) : SIGTRAP;
}
static u32 ptrace_report_syscall_entry(u32 action,
@@ -952,6 +953,8 @@ static void do_ptrace_resume(struct utra
else
context->options &= ~PTRACE_O_TRACE_SYSCALL;
+ context->resume = action;
+
if (!ev_empty(context)) {
struct ptrace_event *ev = ev_pop(context);
@@ -969,7 +972,6 @@ static void do_ptrace_resume(struct utra
}
}
- context->resume = action;
ptrace_wake_up(engine, tracee, action);
}
