On 11/16, Roland McGrath wrote:
>
> Whatever temporary hacks are fine by me one way or the other.
> They will just be coming out later along with assorted other cleanup.
> We certainly do want to get this right in the utrace layer.
Yes. But imho it is always good to test/review the patches against
the working kernel. The patch I sent is very simple, and can be
easily reverted once we improve utrace.
IOW, I am asking you to apply my patch for now and revert your
change to have the working tree, then discuss the "right" fix.
> The change we talked about before seems simple enough and should cover this
> without new kludges in the ptrace layer. I did this (commit f19442c).
I don't think this can work.
tracehook_report_syscall_exit(step)
if (step || UTRACE_EVENT(SYSCALL_EXIT))
utrace_report_syscall_exit(step);
and,
utrace_report_syscall_exit(step)
if (step)
send_sigtrap();
The problems is: we can trust "bool step", and in fact we do
not need it at all.
Once again. The tracee sleeps in SYSCALL_ENTER. The tracer resumes
the tracee via utrace_control(UTRACE_SINGLESTEP).
By the time the resumed tracee passes tracehook_report_syscall_exit()
step == F, utrace_control() does not set TIF_SINGLESTEP.
So, I think we should do something like
tracehook_report_syscall_exit(step)
// do not use step at all
if (task_utrace_flags() != 0)
utrace_report_syscall_exit();
// this code below is only for old ptrace
if (step && (task_ptrace(current) & PT_PTRACED))
send_sigtrap();
ptrace_report_syscall();
and,
utrace_report_syscall_exit()
if (UTRACE_EVENT(SYSCALL_EXIT))
REPORT(report_syscall_exit);
if (utrace->resume == UTRACE_SINGLESTEP ||
utrace->resume == UTRACE_BLOCKSTEP)
send_sigtrap();
What do you think?
Oleg.
