linux-kernel - Re: [PATCH v12 05/13] x86/sgx: architectural structures

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Date:   Tue, 10 Jul 2018 11:06:57 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     "H. Peter Anvin" <hpa@...or.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        sean.j.christopherson@...el.com, nhorman@...hat.com,
        npmccallum@...hat.com, linux-sgx@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v12 05/13] x86/sgx: architectural structures

On Fri, Jul 6, 2018 at 12:50 AM,  <hpa@...or.com> wrote:
> On July 5, 2018 1:09:12 PM PDT, Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> wrote:
>>On Thu, Jul 05, 2018 at 08:31:42AM -0700, Dave Hansen wrote:
>>> On 07/03/2018 11:19 AM, Jarkko Sakkinen wrote:
>>> > +struct sgx_secs {
>>> > +  uint64_t size;
>>> > +  uint64_t base;
>>> > +  uint32_t ssaframesize;
>>> > +  uint32_t miscselect;
>>> > +  uint8_t reserved1[SGX_SECS_RESERVED1_SIZE];
>>> > +  uint64_t attributes;
>>> > +  uint64_t xfrm;
>>> > +  uint32_t mrenclave[8];
>>> > +  uint8_t reserved2[SGX_SECS_RESERVED2_SIZE];
>>> > +  uint32_t mrsigner[8];
>>> > +  uint8_t reserved3[SGX_SECS_RESERVED3_SIZE];
>>> > +  uint16_t isvvprodid;
>>> > +  uint16_t isvsvn;
>>> > +  uint8_t reserved4[SGX_SECS_RESERVED4_SIZE];
>>> > +} __packed __aligned(4096);
>>>
>>> Why are the uint* versions in use here?  Those are for userspace ABI,
>>> but this is entirely for in-kernel-use, right?
>>>
>>> We've used u8/16/32/64 in arch code in a bunch of places.  They're at
>>> least a bit more compact and easier to read.  It's this:
>>>
>>>      u8      foo;
>>>      u64     bar;
>>>
>>> vs. this:
>>>
>>>      uint8_t  foo;
>>>      uint64_t bar;
>>
>>The reason was that with in-kernel LE these were in fact used by
>>user space code. Now they can be changed to those that you
>>suggested.

> For things exported to user space use __u* and __s* types... the _t types would actually violate the C standard with respect to namespace pollution.

Hmm... Coding style 5(d) allows to use uintNN_t in new code (as a
variation of uNN choice).


-- 
With Best Regards,
Andy Shevchenko