linux-kernel - Re: [PATCH v15 15/23] x86/sgx: Add wrappers for ENCLS leaf functions

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Message-ID: <20181106120341.GA11465@linux.intel.com>
Date:   Tue, 6 Nov 2018 14:03:41 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-sgx@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>,
        sean.j.christopherson@...el.com, nhorman@...hat.com,
        npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...el.com,
        mark.shanahan@...el.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, suresh.b.siddha@...el.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v15 15/23] x86/sgx: Add wrappers for ENCLS leaf functions

On Mon, Nov 05, 2018 at 10:39:46PM +0200, Andy Shevchenko wrote:
> On Mon, Nov 5, 2018 at 7:30 PM Jarkko Sakkinen
> <jarkko.sakkinen@...ux.intel.com> wrote:
> >
> > On Sat, Nov 03, 2018 at 03:17:35PM +0200, Andy Shevchenko wrote:
> > > On Sat, Nov 3, 2018 at 1:18 AM Jarkko Sakkinen
> > > <jarkko.sakkinen@...ux.intel.com> wrote:
> > > >
> > > > ENCLS is an umbrella instruction for a variety of cpl0 SGX functions.
> > > > The ENCLS function that is executed is specified in EAX, with each
> > > > function potentially having more leaf-specific operands beyond EAX.
> > > > ENCLS introduces its own (positive value) error codes that (some)
> > > > leafs use to return failure information in EAX.  Leafs that return
> > > > an error code also modify RFLAGS.  And finally, ENCLS generates
> > > > ENCLS-specific non-fatal #GPs and #PFs, i.e. a bug-free kernel may
> > > > encounter faults on ENCLS that must be handled gracefully.
> > > >
> > > > Because of the complexity involved in encoding ENCLS and handling its
> > > > assortment of failure paths, executing any given leaf is not a simple
> > > > matter of emitting ENCLS.
> > > >
> > > > To enable adding support for ENCLS leafs with minimal fuss, add a
> > > > two-layer macro system along with an encoding scheme to allow wrappers
> > > > to return trap numbers along ENCLS-specific error codes.  The bottom
> > > > layer of the macro system splits between the leafs that return an
> > > > error code and those that do not.  The second layer generates the
> > > > correct input/output annotations based on the number of operands for
> > > > each leaf function.
> > >
> > > > +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
> > >
> > > > +/**
> > >
> > > I dunno if kernel-doc script still complains about this.
> >
> > Is there a way to ask for make htmldocs to do only a subset of docs?
> > Still kind of trying to figure out what would be  a good flow for
> > working with Sphinx.
> 
> What I'm telling here is about Copyright notice, which in my
> understanding is not a part of kernel-doc formatting. Though I might
> be mistaken.
> I remember some USB code has that and I saw a warning.
> 
> -- 
> With Best Regards,
> Andy Shevchenko

I'll remove it because I don't find it in other headers under arch/x86.

/Jarkko