[merge] Build failure selftest/powerpc/mm/pkey_exec_prot

[Sandipan Das]

Hi Michael,

On 04/08/20 6:38 am, Michael Ellerman wrote:
> Sandipan Das <sandipan at linux.ibm.com> writes:
>> On 03/08/20 4:32 pm, Michael Ellerman wrote:
>>> Sachin Sant <sachinp at linux.vnet.ibm.com> writes:
>>>>> On 02-Aug-2020, at 10:58 PM, Sandipan Das <sandipan at linux.ibm.com> wrote:
>>>>> On 02/08/20 4:45 pm, Sachin Sant wrote:
>>>>>> pkey_exec_prot test from linuxppc merge branch (3f68564f1f5a) fails to
>>>>>> build due to following error:
>>>>>>
>>>>>> gcc -std=gnu99 -O2 -Wall -Werror -DGIT_VERSION='"v5.8-rc7-1276-g3f68564f1f5a"' -I/home/sachin/linux/tools/testing/selftests/powerpc/include  -m64    pkey_exec_prot.c /home/sachin/linux/tools/testing/selftests/kselftest_harness.h /home/sachin/linux/tools/testing/selftests/kselftest.h ../harness.c ../utils.c  -o /home/sachin/linux/tools/testing/selftests/powerpc/mm/pkey_exec_prot
>>>>>> In file included from pkey_exec_prot.c:18:
>>>>>> /home/sachin/linux/tools/testing/selftests/powerpc/include/pkeys.h:34: error: "SYS_pkey_mprotect" redefined [-Werror]
>>>>>> #define SYS_pkey_mprotect 386
>>>>>>
>>>>>> In file included from /usr/include/sys/syscall.h:31,
>>>>>>                 from /home/sachin/linux/tools/testing/selftests/powerpc/include/utils.h:47,
>>>>>>                 from /home/sachin/linux/tools/testing/selftests/powerpc/include/pkeys.h:12,
>>>>>>                 from pkey_exec_prot.c:18:
>>>>>> /usr/include/bits/syscall.h:1583: note: this is the location of the previous definition
>>>>>> # define SYS_pkey_mprotect __NR_pkey_mprotect
>>>>>>
>>>>>> commit 128d3d021007 introduced this error.
>>>>>> selftests/powerpc: Move pkey helpers to headers
>>>>>>
>>>>>> Possibly the # defines for sys calls can be retained in pkey_exec_prot.c or
>>>>>>
>>>>>
>>>>> I am unable to reproduce this on the latest merge branch (HEAD at f59195f7faa4).
>>>>> I don't see any redefinitions in pkey_exec_prot.c either.
>>>>>
>>>>
>>>> I can still see this problem on latest merge branch.
>>>> I have following gcc version
>>>>
>>>> gcc version 8.3.1 20191121
>>>
>>> What libc version? Or just the distro & version?
>>
>> Sachin observed this on RHEL 8.2 with glibc-2.28.
>> I couldn't reproduce it on Ubuntu 20.04 and Fedora 32 and both these distros
>> are using glibc-2.31.
> 
> OK odd. Usually it's newer glibc that hits this problem.
> 
> I guess on RHEL 8.2 we're getting the asm-generic version? But that
> would be quite wrong if that's what's happening.
> 

If I let GCC dump all the headers that are being used for the source file, I always
see syscall.h being included on the RHEL 8.2 system. That is the header with the
conflicting definition.

  $ cd tools/testing/selftests/powerpc/mm
  $ gcc -H -std=gnu99 -O2 -Wall -Werror -DGIT_VERSION='"v5.8-rc7-1456-gf59195f7faa4-dirty"' \
        -I../include -m64 pkey_exec_prot.c ../../kselftest_harness.h ../../kselftest.h ../harness.c ../utils.c \
        -o pkey_exec_prot 2>&1 | grep syscall

On Ubuntu 20.04 and Fedora 32, grep doesn't find any matching text.
On RHEL 8.2, it shows the following.
  ... /usr/include/sys/syscall.h
  .... /usr/include/bits/syscall.h
  In file included from /usr/include/sys/syscall.h:31,
  /usr/include/bits/syscall.h:1583: note: this is the location of the previous definition
  In file included from /usr/include/sys/syscall.h:31,
  /usr/include/bits/syscall.h:1575: note: this is the location of the previous definition
  In file included from /usr/include/sys/syscall.h:31,
  /usr/include/bits/syscall.h:1579: note: this is the location of the previous definition
  /usr/include/bits/syscall.h
  .. /usr/include/sys/syscall.h
  ... /usr/include/bits/syscall.h
  /usr/include/bits/syscall.h
  .. /usr/include/sys/syscall.h
  ... /usr/include/bits/syscall.h
  /usr/include/bits/syscall.h

So utils.h is also including /usr/include/sys/syscall.h for glibc versions older than 2.30
because of commit 743f3544fffb ("selftests/powerpc: Add wrapper for gettid") :)

[...]
. ../include/pkeys.h
[...]
.. ../include/utils.h
[...]
... /usr/include/sys/syscall.h
.... /usr/include/asm/unistd.h
.... /usr/include/bits/syscall.h
In file included from pkey_exec_prot.c:18:
../include/pkeys.h:34: error: "SYS_pkey_mprotect" redefined [-Werror]
 #define SYS_pkey_mprotect 386

In file included from /usr/include/sys/syscall.h:31,
                 from ../include/utils.h:47,
                 from ../include/pkeys.h:12,
                 from pkey_exec_prot.c:18:
/usr/include/bits/syscall.h:1583: note: this is the location of the previous definition
 # define SYS_pkey_mprotect __NR_pkey_mprotect
[...]


- Sandipan