linux-kernel - Re: [PATCH 1/2] kselftests: mm: Fix wrong __NR

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Message-ID: <db8b758e-9051-4ee0-b0e7-3b54eda0c71b@linuxfoundation.org>
Date: Mon, 23 Sep 2024 10:02:49 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: Muhammad Usama Anjum <Usama.Anjum@...labora.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Shuah Khan <shuah@...nel.org>,
 David Hildenbrand <david@...hat.com>, Peter Xu <peterx@...hat.com>,
 "Dr. David Alan Gilbert" <dgilbert@...hat.com>,
 Andrea Arcangeli <aarcange@...hat.com>, Kim Phillips <kim.phillips@....com>
Cc: kernel@...labora.com, linux-mm@...ck.org,
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
 John Hubbard <jhubbard@...dia.com>, Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 1/2] kselftests: mm: Fix wrong __NR_userfaultfd value

On 9/22/24 23:35, Muhammad Usama Anjum wrote:
> ...
> 
>>> grep -rnIF "#define __NR_userfaultfd"
>>> tools/include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
>>> arch/x86/include/generated/uapi/asm/unistd_32.h:374:#define
>>> __NR_userfaultfd 374
>>> arch/x86/include/generated/uapi/asm/unistd_64.h:327:#define
>>> __NR_userfaultfd 323
>>> arch/x86/include/generated/uapi/asm/unistd_x32.h:282:#define
>>> __NR_userfaultfd (__X32_SYSCALL_BIT + 323)
>>> arch/arm/include/generated/uapi/asm/unistd-eabi.h:347:#define
>>> __NR_userfaultfd (__NR_SYSCALL_BASE + 388)
>>> arch/arm/include/generated/uapi/asm/unistd-oabi.h:359:#define
>>> __NR_userfaultfd (__NR_SYSCALL_BASE + 388)
>>> include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
>>>
>>> The number is dependent on the architecture. The above data shows that:
>>> x86    374
>>> x86_64    323
>>
>> Correct and the generated header files do the right thing and it is good to
>> include them as this patch does.
>>
>> This is a good find and fix. I wish you explained this in your changelog.
>> Please add more details when you send v2.
> I'm sending v2
> 
>>
>> There could be other issues lurking based on what I found.
>>
>> The other two files are the problem where they hard code it to 282 without
>> taking the __NR_SYSCALL_BASE for the arch into consideration:
>>
>> tools/include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
>> include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
>>
>>>
>>> I'm unable to find the history of why it is set to 282 in unistd.h and
>>> when this problem happened.
>>
>> According to git history it is added in the following commit to
>> include/uapi/asm-generic/unistd.h:
>>
>> 09f7298100ea9767324298ab0c7979f6d7463183
>> Subject: [PATCH] userfaultfd: register uapi generic syscall (aarch64)
>>
>> and it is added in the following commit to
>> tools/include/uapi/asm-generic/unistd.h
>> 34b009cfde2b8ce20a69c7bfd6bad4ce0e7cd970
>> Subject: [PATCH] tools include: Grab copies of arm64 dependent unistd.h
>> files
>>
>> I think, the above defines from include/uapi/asm-generic/unistd.h and
>> tools/include/uapi/asm-generic/unistd.h should be removed.
>>
>> Maybe others familiar with userfaultfd can determine the best course of
>> action.
>> We might have other NR_ defines in these two files that are causing
>> problems
>> for tests and tools that we haven't uncovered yet.
> Added authors of these patches.
> 

Thank you. Would you be able top follow up on this and send patches
to remove these defines if it deemed to be the correct solution?

thanks,
-- Shuah