Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Florian Weimer <fweimer@redhat.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     Piotr Figiel <figiel@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        paulmck <paulmck@kernel.org>, Boqun Feng <boqun.feng@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>,
        "Dmitry V. Levin" <ldv@altlinux.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Andrei Vagin <avagin@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Peter Oskolkov <posk@google.com>,
        Kamil Yurtsever <kyurtsever@google.com>,
        Chris Kennelly <ckennelly@google.com>,
        Paul Turner <pjt@google.com>, emmir <emmir@google.com>,
        linux-man <linux-man@vger.kernel.org>,
        linux-api <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2] ptrace: add PTRACE_GET_RSEQ_CONFIGURATION request
References: <20210226135156.1081606-1-figiel@google.com>
        <192824546.8190.1614353555831.JavaMail.zimbra@efficios.com>
Date:   Wed, 03 Mar 2021 18:10:27 +0100
In-Reply-To: <192824546.8190.1614353555831.JavaMail.zimbra@efficios.com>
        (Mathieu Desnoyers's message of "Fri, 26 Feb 2021 10:32:35 -0500
        (EST)")
Message-ID: <87h7lsuprw.fsf@oldenburg.str.redhat.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

* Mathieu Desnoyers:

> This way, the configuration structure can be expanded in the future. The
> rseq ABI structure is by definition fixed-size, so there is no point in
> having its size here.
>
> Florian, did I understand your request correctly, or am I missing your
> point ?

No, the idea was that if the kernel ever supports different rseq ABI
sizes on registration (it could as there's a size argument to the rseq
system call), that needs to be communicated to CRIU, so that it restores
with the right size.

I haven't thought about whether it makes sense to make the ptrace
argument struct extensible.

Thanks,
Florian