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:   Fri, 26 Mar 2021 19:17:17 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Len Brown <lenb@kernel.org>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Chang S. Bae" <chang.seok.bae@intel.com>,
        Ingo Molnar <mingo@kernel.org>, X86 ML <x86@kernel.org>,
        "Brown, Len" <len.brown@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        "Liu, Jing2" <jing2.liu@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Documentation List <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v4 22/22] x86/fpu/xstate: Introduce boot-parameters to
 control state component support
Message-ID: <20210326181641.GD27507@zn.tnic>
References: <20210221185637.19281-1-chang.seok.bae@intel.com>
 <20210221185637.19281-23-chang.seok.bae@intel.com>
 <871rc9bl3v.fsf@nanos.tec.linutronix.de>
 <CAJvTdKkOKOgnmvAiPS6mWVoyAggbOB6hBOqb_tcHYDe8+-X+FQ@mail.gmail.com>
 <CALCETrWOc7wwW=KY2dGJGy9k5Ag=KhkdGGTDZMvgRHgyQ5fDjQ@mail.gmail.com>
 <CAJvTdK=OGALDso0H+asjgkjD_VaPNZzm+LpV+msM_i5aVUm_qw@mail.gmail.com>
 <CALCETrXky0RuA5WeQ0Mxjs+e4ywk1A7vmpBxqCo=PTSBzUsz-g@mail.gmail.com>
 <CAJvTdK=_G11phL6=9Ri41fJQvhRNopok_oktgvRjTM0v6ojcbg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CAJvTdK=_G11phL6=9Ri41fJQvhRNopok_oktgvRjTM0v6ojcbg@mail.gmail.com>
Precedence: bulk

On Fri, Mar 26, 2021 at 01:53:47PM -0400, Len Brown wrote:
> At Dave's suggestion, we had a 64 *KB* sanity check on this path.
> Boris forced us to remove it, because we could not tell him
> how we chose the number 64.

The only 64 I can remember is

#define XSTATE_BUFFER_MAX_BYTES              (64 * 1024)

What does an arbitrary number have to do with signal handling and
pushing a fat frame on the sigaltstack?

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg