On 04/08/20 5:53 pm, Michael Ellerman wrote:
> Sandipan Das <sandi...@linux.ibm.com> writes:
>> On 04/08/20 6:38 am, Michael Ellerman wrote:
>>> Sandipan Das <sandi...@linux.ibm.com> writes:
>>>> On 03/08/20 4:32 pm, Michael Ellerman wrote:
>>>>> Sachin Sant <sach...@linux.vnet.ibm.com> writes:
>>>>>>> On 02-Aug-2020, at 10:58 PM, Sandipan Das <sandi...@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")
>> :)
>
> Haha, of course. :facepalm_emoji:
>
>> [...]
>> . ../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
>
> Aha, that explains why redefining gives us an error, because we're
> defining it to the literal 386 whereas the system header is defining it
> to the __NR value.
>
> Is there a reason to use the SYS_ name?
>
That's just something I borrowed from the pkey tests under selftests/vm
... but without the #ifndefs
> Typically we just use the __NR value directly, and that would avoid any
> problems with redefinition I think, as long as we're using the same
> value as the system header (which we always should be).
>
Agreed. David Laight suggested this too. Will send v4 with these changes.
- Sandipan
> eg:
>
> diff --git a/tools/testing/selftests/powerpc/include/pkeys.h
> b/tools/testing/selftests/powerpc/include/pkeys.h
> index 6ba95039a034..3312cb1b058d 100644
> --- a/tools/testing/selftests/powerpc/include/pkeys.h
> +++ b/tools/testing/selftests/powerpc/include/pkeys.h
> @@ -31,9 +31,9 @@
>
> #define SI_PKEY_OFFSET 0x20
>
> -#define SYS_pkey_mprotect 386
> -#define SYS_pkey_alloc 384
> -#define SYS_pkey_free 385
> +#define __NR_pkey_mprotect 386
> +#define __NR_pkey_alloc 384
> +#define __NR_pkey_free 385
>
> #define PKEY_BITS_PER_PKEY 2
> #define NR_PKEYS 32
> @@ -62,17 +62,17 @@ void pkey_set_rights(int pkey, unsigned long rights)
>
> int sys_pkey_mprotect(void *addr, size_t len, int prot, int pkey)
> {
> - return syscall(SYS_pkey_mprotect, addr, len, prot, pkey);
> + return syscall(__NR_pkey_mprotect, addr, len, prot, pkey);
> }
>
> int sys_pkey_alloc(unsigned long flags, unsigned long rights)
> {
> - return syscall(SYS_pkey_alloc, flags, rights);
> + return syscall(__NR_pkey_alloc, flags, rights);
> }
>
> int sys_pkey_free(int pkey)
> {
> - return syscall(SYS_pkey_free, pkey);
> + return syscall(__NR_pkey_free, pkey);
> }
>
> int pkeys_unsupported(void)
>
