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;
From:   Valentin Schneider <vschneid@redhat.com>
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org,
        bpf@vger.kernel.org, x86@kernel.org, rcu@vger.kernel.org,
        linux-kselftest@vger.kernel.org,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Neeraj Upadhyay <quic_neeraju@quicinc.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Boqun Feng <boqun.feng@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Zqiang <qiang.zhang1211@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Uladzislau Rezki <urezki@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Jason Baron <jbaron@akamai.com>,
        Kees Cook <keescook@chromium.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Juerg Haefliger <juerg.haefliger@canonical.com>,
        Nicolas Saenz Julienne <nsaenz@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Nadav Amit <namit@vmware.com>,
        Dan Carpenter <error27@gmail.com>,
        Chuang Wang <nashuiliang@gmail.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Petr Mladek <pmladek@suse.com>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>, Song Liu <song@kernel.org>,
        Julian Pidancet <julian.pidancet@oracle.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Dionna Glaze <dionnaglaze@google.com>,
        Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <linux@weissschuh.net>,
        Juri Lelli <juri.lelli@redhat.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        Yair Podemsky <ypodemsk@redhat.com>
Subject: Re: [RFC PATCH v2 12/20] objtool: Warn about non __ro_after_init
 static key usage in .noinstr
In-Reply-To: <20230728160247.multb2csnpa22fgx@treble>
References: <20230720163056.2564824-1-vschneid@redhat.com>
 <20230720163056.2564824-13-vschneid@redhat.com>
 <20230728160247.multb2csnpa22fgx@treble>
Date:   Mon, 31 Jul 2023 12:18:10 +0100
Message-ID: <xhsmh7cqgs51p.mognet@vschneid.remote.csb>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On 28/07/23 11:02, Josh Poimboeuf wrote:
> On Thu, Jul 20, 2023 at 05:30:48PM +0100, Valentin Schneider wrote:
>> Later commits will depend on having no runtime-mutable text in early entry
>> code. (ab)use the .noinstr section as a marker of early entry code and warn
>> about static keys used in it that can be flipped at runtime.
>
> Similar to my comment on patch 13, this could also use a short
> justification for adding the feature, i.e. why runtime-mutable text
> isn't going to be allowed in .noinstr.
>
> Also, please add a short description of the warning (and why it exists)
> to tools/objtool/Documentation/objtool.txt.
>

I had missed this, thanks for the pointer.

> --
> Josh