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Subject: Re: [PATCH v2 1/3] bcm-vk: add bcm_vk UAPI
To:     Florian Fainelli <f.fainelli@gmail.com>,
        Kees Cook <keescook@chromium.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>, linux-kernel@vger.kernel.org,
        bcm-kernel-feedback-list@broadcom.com
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 <4adbd70e-c49b-c2d4-84c7-5e910f05e449@broadcom.com>
 <20200819070044.GA1004396@kroah.com>
 <fdbb7404-03c3-22b1-d409-5b6d8745ff2b@broadcom.com>
 <202008201353.F342E59EC@keescook>
 <ec24beca-fad8-5591-f09d-b87c21a745b2@gmail.com>
From:   Scott Branden <scott.branden@broadcom.com>
Message-ID: <fc0745bd-d1a7-c2ae-c9c6-c945dbce0b52@broadcom.com>
Date:   Thu, 20 Aug 2020 14:10:22 -0700
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On 2020-08-20 1:57 p.m., Florian Fainelli wrote:
> On 8/20/20 1:55 PM, Kees Cook wrote:
>> On Thu, Aug 20, 2020 at 09:37:46AM -0700, Scott Branden wrote:
>>> On 2020-08-19 12:00 a.m., Greg Kroah-Hartman wrote:
>>>> On Tue, Aug 18, 2020 at 05:35:04PM -0700, Scott Branden wrote:
>>>>> On 2020-08-18 10:44 a.m., Greg Kroah-Hartman wrote:
>>>>>> On Tue, Aug 18, 2020 at 10:23:42AM -0700, Scott Branden wrote:
>>>>>>>>> +#define VK_FWSTS_RELOCATION_ENTRY	BIT(0)
>>>>>>>> <snip>
>>>>>>>>
>>>>>>>> I thought BIT() was not allowed in uapi .h files, this really works
>>>>>>>> properly???
>>>>>>> I did some investigation and it looks like a few other header files in include/uapi also use the BIT() macro:
>>>>>>> include/uapi/misc/uacce/uacce.h
>>>>>>> include/uapi/linux/psci.h
>>>>>>> include/uapi/linux/v4l2-subdev.h
>>>>>> Does the header install test target now fail for these?
>>>>> I do not understand the question above.  make headers_install works.
>>>>> But I guess the above headers would have similar issue with the BIT macro.
>>>> Try enabling CONFIG_UAPI_HEADER_TEST and see what happens :)
>>> I enabled CONFIG_UAPI_HEADER_TEST and then
>>> built using "make" and "make headers_install".
>>>
>>> There didn't appear to be any issue with the BIT macro in the headers.
>> FWIW, other subsystems have not been so lucky:
>>
>> https://git.kernel.org/linus/23b2c96fad21886c53f5e1a4ffedd45ddd2e85ba
>>
>> It may just be better to avoid BIT(), even if it works "by accident"(?)
>> for some header combinations...
> Since we ship a copy of unifdef.c in tree, we could certainly teach it
> to undo the BIT() definition and replace it with an appropriate constant
> definition.
That sounds appealing given the rest of the code wants us to use the BIT macro.