Re: [PATCH] Add missing VDSO_{NAME,HASH}_* macros and use them for PREPARE_VERSION_KNOWN

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 24/05/2019 04:23, Tobias Klauser wrote:
> Thank you for the review.
> 
> On 2019-05-23 at 21:36:01 +0200, Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
>> On 16/05/2019 08:59, Tobias Klauser wrote:
>>> Define all currently used Linux versions used for
>>> PREPARE_VERSION{,_KNOWN} in sysdeps/unix/sysv/linux/dl-vdso.h and use
>>> them instead of duplicating the versions and precomputed hashes across
>>> architecture specific files.
>>>
>>> 2019-05-16  Tobias Klauser  <tklauser@distanz.ch>
>>>
>>> 	* sysdeps/unix/sysv/linux/aarch64/gettimeofday.c (INIT_ARCH): Use
>>> 	PREPARE_VERSION_KNOWN.
>>> 	* sysdeps/unix/sysv/linux/aarch64/init-first.c: Likewise.
>>> 	* sysdeps/unix/sysv/linux/dl-vdso.h (VDSO_NAME_LINUX_2_6_39): New
>>> 	define.
>>> 	(VDSO_HASH_LINUX_2_6_39): Likewise.
>>> 	(VDSO_NAME_LINUX_4_9): Likewise.
>>> 	(VDSO_HASH_LINUX_4_9): Likewise.
>>> 	* sysdeps/unix/sysv/linux/m68k/init-first.c (_libc_vdso_platform_setup):
>>> 	Use PREPARE_VERSION_KNOWN.
>>> 	* sysdeps/unix/sysv/linux/powerpc/gettimeofday.c (INIT_ARCH): Likewise.
>>> 	* sysdeps/unix/sysv/linux/powerpc/init-first.c
>>> 	(_libc_vdso_platform_setup): Likewise.
>>> 	* sysdeps/unix/sysv/linux/powerpc/time.c (INIT_ARCH): Likewise.
>>> 	* sysdeps/unix/sysv/linux/s390/init-first.c (_libc_vdso_platform_setup):
>>> 	Likewise.
>>> 	* sysdeps/unix/sysv/linux/x86_64/init-first.c (__vdso_platform_setup):
>>> 	Likewise.
>>
>>
>> LGTM, I assume you checked a build against affected architectures.  As a side
>> note I think also should just remove PREPARE_VERSION macro and replace it with
>> a more sane interface:
> 
> I (cross-)compile tested on all architectures and ran the test suite on
> x86_64.
> 
>> --
>> static inline struct r_found_version
>> prepare_version_base (const char *name, ElfW(Word) hash)
>> {
>>   assert (hash == _dl_elf_hash (name));
>>   return (struct r_found_version) { name, hash, 1, NULL };
>> }
>> #define prepare_version(vname) \
>>   prepare_version_base (VDSO_NAME_##vname, VDSO_HASH_##vname)
>> --
> 
> Should I add this to a v2 of this patch? Or should I send a follow-up
> patch with the change?

I don't have a preference here. Refactor the vDSO code is something
I have in mind for some time.

> 
>>> ---
>>>  sysdeps/unix/sysv/linux/aarch64/gettimeofday.c | 4 ++--
>>>  sysdeps/unix/sysv/linux/aarch64/init-first.c   | 4 ++--
>>>  sysdeps/unix/sysv/linux/dl-vdso.h              | 4 ++++
>>>  sysdeps/unix/sysv/linux/m68k/init-first.c      | 2 +-
>>>  sysdeps/unix/sysv/linux/powerpc/gettimeofday.c | 4 ++--
>>>  sysdeps/unix/sysv/linux/powerpc/init-first.c   | 2 +-
>>>  sysdeps/unix/sysv/linux/powerpc/time.c         | 4 ++--
>>>  sysdeps/unix/sysv/linux/s390/init-first.c      | 2 +-
>>>  sysdeps/unix/sysv/linux/x86_64/init-first.c    | 2 +-
>>>  9 files changed, 16 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c b/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
>>> index 6c008ed9357f..9180b50bf7c3 100644
>>> --- a/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
>>> +++ b/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
>>> @@ -38,13 +38,13 @@ __gettimeofday_vsyscall (struct timeval *tv, struct timezone *tz)
>>>    return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
>>>  }
>>>  
>>> -/* PREPARE_VERSION will need an __LP64__ ifdef when ILP32 support
>>> +/* PREPARE_VERSION_KNOWN will need an __LP64__ ifdef when ILP32 support
>>>     goes in.  See _libc_vdso_platform_setup in
>>>     sysdeps/unix/sysv/linux/aarch64/init-first.c.  */
>>>  
>>>  # undef INIT_ARCH
>>>  # define INIT_ARCH() \
>>> -	   PREPARE_VERSION (linux_version, "LINUX_2.6.39", 123718537); \
>>> +	   PREPARE_VERSION_KNOWN (linux_version, LINUX_2_6_39); \
>>>  	   void *vdso_gettimeofday = \
>>>  	     _dl_vdso_vsym ("__kernel_gettimeofday", &linux_version);
>>
>> Also a side note, this vsdo setup is not required. The init-first.c
>> already setups the VDSO_SYMBOL(gettimeofday). So a possible followup
>> cleanup would be:
>>
>> --
>> # undef INIT_ARCH
>> # define INIT_ARCH()
>>
>> static inline void *
>> gettimeofday_vdso (void)
>> { 
>>   __typeof (VDSO_SYMBOL(gettimeofday)) vdsop = VDSO_SYMBOL(gettimeofday);
>>   PTR_DEMANGLE (vdsop);
>>   return vdsop != NULL ? vdsop : (void *) __gettimeofday_vsyscall;
>> }
>>
>> libc_ifunc_hidden (__redirect___gettimeofday, __gettimeofday,
>>                    gettimeofday_vdso ())
>> --
> 
> Thanks, will send a follow-up patch.
>