linux-kernel - Re: [PATCH v2 1/6] selftests/mm: mseal, self_elf: fix missing __NR

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Date: Mon, 17 Jun 2024 20:11:54 +0200
From: David Hildenbrand <david@...hat.com>
To: John Hubbard <jhubbard@...dia.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Jeff Xu <jeffxu@...omium.org>,
 Shuah Khan <shuah@...nel.org>
Cc: Andrei Vagin <avagin@...gle.com>,
 Axel Rasmussen <axelrasmussen@...gle.com>,
 Christian Brauner <brauner@...nel.org>, Kees Cook <kees@...nel.org>,
 Kent Overstreet <kent.overstreet@...ux.dev>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>,
 Muhammad Usama Anjum <usama.anjum@...labora.com>,
 Peter Xu <peterx@...hat.com>, Rich Felker <dalias@...c.org>,
 linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/6] selftests/mm: mseal, self_elf: fix missing
 __NR_mseal

On 14.06.24 20:02, John Hubbard wrote:
> On 6/14/24 5:41 AM, David Hildenbrand wrote:
>> On 14.06.24 14:28, David Hildenbrand wrote:
>>> On 14.06.24 04:30, John Hubbard wrote:
>>>> The selftests/mm build isn't exactly "broken", according to the current
>>>> documentation, which still claims that one must run "make headers",
>>>> before building the kselftests. However, according to the new plan to
>>>> get rid of that requirement [1], they are future-broken: attempting to
>>>> build selftests/mm *without* first running "make headers" will fail due
>>>> to not finding __NR_mseal.
>>>>
>>>> Therefore,  add ./usr/include/asm/unistd_[32|x32|64].h (created via
>>>> "make headers") to tools/uapi/, and change the selftests/mm files that
>>>> require __NR_mseal to include from the correct location. The way to do
>>>> so is to include <linux/unistd.h> instead of just <unistd.h>.
>>>>
>>>> [1] commit e076eaca5906 ("selftests: break the dependency upon local
>>>> header files")
>>>>
>>>> Fixes: 4926c7a52de7 ("selftest mm/mseal memory sealing")
>>>> Cc: Jeff Xu <jeffxu@...omium.org>
>>>> Cc: David Hildenbrand <david@...hat.com>
>>>> Signed-off-by: John Hubbard <jhubbard@...dia.com>
>>>> ---
>>>
>>> If it works, great
>>
>> ... thinking again, are some of these headers arch-specific (IOW,
>> generating them per-arch would result in something slightly different)?
> 
> Oh wow, yes they are. I'm guilty of x86-centric thinking (again).
> 
> hmm, this is going to make it really a lot of trouble to do this
> approach. But there's no point in turning back now, so I guess I'd
> better fire up the cross-compilers and generate for all the arches.
> 

Cross compilers might not be required.

At least for me, at simple

rm -rf usr/include
export ARCH=s390
make headers
make headers_install

Installed the proper s390 headers, and "usr/include/asm" would contain 
the s390 specifics.

Some scripting would be required to make this much easier to 
generate+wire up for all archs semi-automatically.

>>
>> In tools/include/uapi/asm-generic/unistd.h, we already do have
>> __NR_mseal ...
> 
> Yes, but it doesn't get used in selftests/mm, with the way headers are
> set up right now.

Right

-- 
Cheers,

David / dhildenb