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;
Date:   Mon, 12 Oct 2020 22:15:11 +0300
From:   Cyrill Gorcunov <gorcunov@gmail.com>
To:     Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc:     x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Balbir Singh <bsingharora@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Eugene Syromiatnikov <esyr@redhat.com>,
        Florian Weimer <fweimer@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        Dave Martin <Dave.Martin@arm.com>,
        Weijiang Yang <weijiang.yang@intel.com>,
        Pengfei Xu <pengfei.xu@intel.com>
Subject: Re: [PATCH v14 1/7] x86/cet/ibt: Add Kconfig option for user-mode
 Indirect Branch Tracking
Message-ID: <20201012191511.GC14048@grain>
References: <20201012154530.28382-1-yu-cheng.yu@intel.com>
 <20201012154530.28382-2-yu-cheng.yu@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20201012154530.28382-2-yu-cheng.yu@intel.com>
User-Agent: Mutt/1.14.6 (2020-07-11)
Precedence: bulk

On Mon, Oct 12, 2020 at 08:45:24AM -0700, Yu-cheng Yu wrote:
...
> +	  the application support it.  When this feature is enabled,
> +	  legacy non-IBT applications continue to work, but without
> +	  IBT protection.
> +	  Support for this feature is only known to be present on
> +	  processors released in 2020 or later.  CET features are also
> +	  known to increase kernel text size by 3.7 KB.

It seems the last sentence is redundant - new features always bloat
the kernel code and precise size may differ depending on compiler
and options. Surely this can be patched on top.