Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: i56a14606:Fastmail
User-Agent: Cyrus-JMAP/3.9.0-alpha0-237-g62623e8e3f-fm-20230327.001-g62623e8e
Mime-Version: 1.0
Message-Id: <b0d8da28-2499-48db-be17-7d126697e303@app.fastmail.com>
In-Reply-To: <20230328164811.2451-2-gregory.price@memverge.com>
References: <20230328164811.2451-1-gregory.price@memverge.com>
 <20230328164811.2451-2-gregory.price@memverge.com>
Date:   Tue, 28 Mar 2023 20:46:06 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Gregory Price" <gourry.memverge@gmail.com>,
        linux-kernel@vger.kernel.org
Cc:     linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Linux-Arch <linux-arch@vger.kernel.org>,
        "Oleg Nesterov" <oleg@redhat.com>, avagin@gmail.com,
        "Peter Zijlstra" <peterz@infradead.org>,
        "Andy Lutomirski" <luto@kernel.org>, krisman@collabora.com,
        "Thomas Gleixner" <tglx@linutronix.de>,
        "Jonathan Corbet" <corbet@lwn.net>, shuah <shuah@kernel.org>,
        "Catalin Marinas" <catalin.marinas@arm.com>,
        "Will Deacon" <will@kernel.org>,
        "Mark Rutland" <mark.rutland@arm.com>, tongtiangen@huawei.com,
        "Robin Murphy" <robin.murphy@arm.com>,
        "Gregory Price" <gregory.price@memverge.com>
Subject: Re: [PATCH v14 1/4] asm-generic,arm64: create task variant of access_ok
Content-Type: text/plain
Precedence: bulk

On Tue, Mar 28, 2023, at 18:48, Gregory Price wrote:
> On arm64, access_ok makes adjustments to pointers based on whether
> memory tagging is enabled for a task (ARM MTE). When leveraging ptrace,
> it's possible for a task to enable/disable various kernel features (such
> as syscall user dispatch) which require user points as arguments.
>
> To enable Task A to set these features via ptrace with Task B's
> pointers, a task variant of access_ok is required for architectures with
> features such as memory tagging.
>
> If the architecture does not implement task_access_ok, the operation
> reduces to access_ok and the task argument is discarded.
>
> Signed-off-by: Gregory Price <gregory.price@memverge.com>

For asm-generic:

Acked-by: Arnd Bergmann <arnd@arndb.de>