linux-kernel - Re: [PATCH 1/2] fork: add clone6

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Message-ID: <CALCETrU0wXuefHFzRNrQjQ+xgTz6tbPa-sLcBV=dV58QEcA6HQ@mail.gmail.com>
Date:   Tue, 28 May 2019 07:15:37 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Christian Brauner <christian@...uner.io>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Jann Horn <jannh@...gle.com>,
        Florian Weimer <fweimer@...hat.com>,
        Oleg Nesterov <oleg@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        David Howells <dhowells@...hat.com>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Adrian Reber <adrian@...as.de>,
        Andrei Vagin <avagin@...il.com>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [PATCH 1/2] fork: add clone6

On Tue, May 28, 2019 at 3:08 AM Christian Brauner <christian@...uner.io> wrote:
>
> On Mon, May 27, 2019 at 12:27:08PM -0700, Linus Torvalds wrote:
> > On Mon, May 27, 2019 at 3:42 AM Christian Brauner <christian@...uner.io> wrote:
> > >
> > > Hm, still pondering whether having one unsigned int argument passed
> > > through registers that captures all the flags from the old clone() would
> > > be a good idea.
> >
> > That sounds like a reasonable thing to do.
> >
> > Maybe we could continue to call the old flags CLONE_XYZ and continue
> > to pass them in as "flags" argument, and then we have CLONE_EXT_XYZ
> > flags for a new 64-bit flag field that comes in through memory in the
> > new clone_args thing?
>
> Hm. I think I'll try a first version without an additional register
> flags argument. And here's why: I'm not sure it buys us a lot especially
> if we're giving up on making this convenient for seccomp anyway.
> And with that out of the way (at least for the moment) I would really
> like to make this interface consistent. But we can revisit this when I
> have the code.
>

Seems reasonable.  Once the interface is nailed down, we can see if it
makes sense to break out some flags into a register.  I would guess
that all the unsharing flags are a good candidate.