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

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Date:   Mon, 10 Jan 2022 20:37:36 +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>,
        Michael Schmitz <schmitzmic@...il.com>,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>
Subject: Re: [PATCH 08/17] ptrace/m68k: Stop open coding ptrace_report_syscall

On Mon, Jan 10, 2022 at 06:54:57PM +0100, Geert Uytterhoeven wrote:

> 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@gmail.com/

Looks sane, but I'd split it in two - switch to calling syscall_trace_{enter,leave}
and then handling the return values...

The former would keep the current behaviour (modulo reporting enter vs. leave
via PTRACE_GETEVENTMSG), the latter would allow syscall number change by tracer
and/or handling of seccomp/audit/whatnot.

For exit+signal work the former would suffice, and IMO it would be a good idea
to put that one into a shared branch to be pulled both by seccomp and by signal
series.  Would reduce the conflicts...

Objections?