Hi Al, CC Michael/m68k, On Mon, Jan 10, 2022 at 5:20 PM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > 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. In fact Michael did so in "[PATCH v7 1/2] m68k/kernel - wire up syscall_trace_enter/leave for m68k"[1], but that's still stuck... [1] https://lore.kernel.org/r/1624924520-17567-2-git-send-email-schmitzmic@xxxxxxxxx/ Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
