linux-kernel - Re: [PATCH 08/17] ptrace/m68k: Stop open coding ptrace_report

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Message-ID: <Ydxd7b37r6Mmce5l@zeniv-ca.linux.org.uk>
Date:   Mon, 10 Jan 2022 16:25:17 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [PATCH 08/17] ptrace/m68k: Stop open coding ptrace_report_syscall

On Mon, Jan 10, 2022 at 04:20:03PM +0000, Al Viro wrote:

> 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.

Actually, the current behaviour is "report what the last PTRACE_GETEVENTMSG
has reported, whatever kind of stop that used to be for".  So I very much
doubt that anything could break there.