On Mon, Jan 10, 2022 at 04:26:57PM +0100, Geert Uytterhoeven wrote: > On Mon, Jan 3, 2022 at 10:33 PM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > The generic function ptrace_report_syscall does a little more > > than syscall_trace on m68k. The function ptrace_report_syscall > > stops early if PT_TRACED is not set, it sets ptrace_message, > > and returns the result of fatal_signal_pending. > > > > Setting ptrace_message to a passed in value of 0 is effectively not > > setting ptrace_message, making that additional work a noop. > > > > Returning the result of fatal_signal_pending and letting the caller > > ignore the result becomes a noop in this change. > > > > When a process is ptraced, the flag PT_PTRACED is always set in > > current->ptrace. Testing for PT_PTRACED in ptrace_report_syscall is > > just an optimization to fail early if the process is not ptraced. > > Later on in ptrace_notify, ptrace_stop will test current->ptrace under > > tasklist_lock and skip performing any work if the task is not ptraced. > > > > Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> > > Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> > > As this depends on the removal of a parameter from > ptrace_report_syscall() earlier in this series: > Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> FWIW, I would suggest taking it a bit further: make syscall_trace_enter() and syscall_trace_leave() in m68k ptrace.c unconditional, replace the calls of syscall_trace() in entry.S with syscall_trace_enter() and syscall_trace_leave() resp. and remove syscall_trace(). Geert, do you see any problems with that? The only difference is that current->ptrace_message would be set to 1 for ptrace stop on entry and 2 - on leave. Currently m68k just has it 0 all along. It is user-visible (the whole point is to let the tracer see which stop it is - entry or exit one), so somebody using PTRACE_GETEVENTMSG on syscall stops would start seeing 1 or 2 instead of "0 all along". That's how it works on all other architectures (including m68k-nommu), and I doubt that anything in userland will get broken. Behaviour of PTRACE_GETEVENTMSG for other stops (fork, etc.) remains as-is, of course.
