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Date:   Wed, 11 Jul 2018 10:27:39 +0200
From:   Pavel Machek <pavel@ucw.cz>
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@amacapital.net>,
        Balbir Singh <bsingharora@gmail.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.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@chromiun.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Subject: Re: [RFC PATCH v2 05/27] Documentation/x86: Add CET description
Message-ID: <20180711082739.GA18919@amd>
References: <20180710222639.8241-1-yu-cheng.yu@intel.com>
 <20180710222639.8241-6-yu-cheng.yu@intel.com>
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On Tue 2018-07-10 15:26:17, Yu-cheng Yu wrote:
> Explain how CET works and the no_cet_shstk/no_cet_ibt kernel
> parameters.
>=20

> --- /dev/null
> +++ b/Documentation/x86/intel_cet.txt
> @@ -0,0 +1,250 @@
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +Control Flow Enforcement Technology (CET)
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

We normally use .rst for this kind of formatted text.


> +[6] The implementation of the SHSTK
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +
> +SHSTK size
> +----------
> +
> +A task's SHSTK is allocated from memory to a fixed size that can
> +support 32 KB nested function calls; that is 256 KB for a 64-bit
> +application and 128 KB for a 32-bit application.  The system admin
> +can change the default size.

How does admin change that? We already have ulimit for stack size,
should those be somehow tied together?

$ ulimit -a
=2E..
stack size              (kbytes, -s) 8192


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