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From: Jann Horn <jannh@google.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
	Christian Brauner <christian@brauner.io>,
	lkml <linux-kernel@vger.kernel.org>,
	linux-man <linux-man@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Oleg Nesterov <oleg@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
	David Howells <dhowells@redhat.com>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Adrian Reber <adrian@lisas.de>, Andrei Vagin <avagin@gmail.com>,
	Linux API <linux-api@vger.kernel.org>
Subject: Re: For review: documentation of clone3() system call
Date: Mon, 11 Nov 2019 16:15:58 +0100	[thread overview]
Message-ID: <CAG48ez3zpBwU6vHSuY6VoP+Uw_Jz6uxYN1Teg2wSpwZrPmAn-g@mail.gmail.com> (raw)
In-Reply-To: <87tv7awj4g.fsf@oldenburg2.str.redhat.com>

On Mon, Nov 11, 2019 at 4:03 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Michael Kerrisk:
>
> >        Another  difference  for  the  raw clone() system call is that the
> >        stack argument may be NULL, in which case the child uses a  dupli‐
> >        cate  of the parent's stack.  (Copy-on-write semantics ensure that
> >        the child gets separate copies of stack pages when either  process
> >        modifies  the  stack.)   In  this case, for correct operation, the
> >        CLONE_VM option should not be specified.  (If the child shares the
> >        parent's  memory  because of the use of the CLONE_VM flag, then no
> >        copy-on-write duplication occurs and chaos is likely to result.)
>
> I think sharing the stack also works with CLONE_VFORK with CLONE_VM, as
> long as measures are taken to preserve the return address in a register.

That basically just requires that the userspace function declaration
for clone3 includes __attribute__((returns_twice)), right?

  reply	other threads:[~2019-11-11 15:16 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-25 16:59 For review: documentation of clone3() system call Michael Kerrisk (man-pages)
2019-10-25 17:07 ` Christian Brauner
2019-11-07 12:26   ` Michael Kerrisk (man-pages)
2019-10-28 15:12 ` Jann Horn
2019-10-28 17:21   ` Christian Brauner
2019-10-28 19:09     ` Jann Horn
2019-10-29 11:27       ` Christian Brauner
2019-10-29 14:26         ` Christian Brauner
2019-10-29 14:36           ` Florian Weimer
2019-10-29 16:04             ` Christian Brauner
2019-10-29 15:20           ` Jann Horn
2019-10-29 16:05             ` Christian Brauner
2019-11-07 15:19 ` Christian Brauner
2019-11-07 16:10   ` Florian Weimer
2019-11-09  8:09   ` Michael Kerrisk (man-pages)
2019-11-09 16:53     ` Christian Brauner
2019-11-11  9:02       ` Michael Kerrisk (man-pages)
2019-11-11 11:36         ` Christian Brauner
2019-11-11 19:56           ` Michael Kerrisk (man-pages)
2019-11-11 14:55     ` Jann Horn
2019-11-11 16:58       ` Theodore Y. Ts'o
2019-11-11 20:24         ` Jann Horn
2019-11-12 23:03           ` Kees Cook
2019-11-14 12:15       ` Michael Kerrisk (man-pages)
2019-11-14 12:29         ` Christian Brauner
2019-11-11 15:03 ` Florian Weimer
2019-11-11 15:15   ` Jann Horn [this message]
2019-11-11 15:20     ` Florian Weimer

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