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Re: [PATCH, resend] Add x86 32 bit vDSO time function support


On Mon, Jan 12, 2015 at 5:51 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Tue, Jan 6, 2015 at 6:35 AM, Adhemerval Zanella
> <azanella@linux.vnet.ibm.com> wrote:
>> Ping.
>>
>> On 09-12-2014 13:32, Adhemerval Zanella wrote:
>>> Linux 3.15 adds support for clock_gettime, gettimeofday, and time vDSO
>>> (commit id 37c975545ec63320789962bf307f000f08fabd48).  This patch adds
>>> GLIBC supports to use such symbol when they are avaiable.
>>>
>>> Along with x86 vDSO support, this patch cleanup x86_64 code by moving
>>> all common code to x86 common folder.  Only init-first.c is different
>>> between implementations.
>>>
>>> Tested on x86 and x86_64 with a 3.5.0 and a 3.16 kernel.
>>>
>>> --
>>>
>>> 2014-12-09  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
>>>           Stefani Seibold  <stefani@seibold.net>
>>>
>>>       * sysdeps/unix/sysv/linux/x86_64/Makefile [$(subdir) = elf]
>>>       (sysdep_routines): Add dl-vdso here, ...
>>>       * sysdeps/unix/sysv/linux/x86/Makefile [$(subdir) = elf]
>>>       (sysdep_routines): ... not here.
>>>       * sysdeps/unix/sysv/linux/i386/gettimeofday.c: New file: set syscall
>>>       fallback when vDSO is not presented.
>>>       * sysdeps/unix/sysv/linux/x86_64/init-first.c (__vdso_clock_gettime):
>>>       Define with libc_hidden_proto/libc_hidden_data_def definitions.
>>>       (_libc_vdso_platform_setup): Rename to __vdso_platform_setup.
>>>       * sysdeps/unix/sysv/linux/i386/init-first.c: New file: likewise.
>>>       * sysdeps/unix/sysv/linux/i386/time.c: New file: likewise.
>>>       * sysdeps/unix/sysv/linux/x86_64/bits/libc-vdso.h: Moved to ...
>>>       * sysdeps/unix/sysv/linux/x86/libc-vdso.h: ... here.
>>>       * sysdeps/unix/sysv/linux/x86_64/clock_gettime.c: Move to ...
>>>       * sysdeps/unix/sysv/linux/x86/clock_gettime.c: ... here.
>>>       * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Move to ...
>>>       * sysdeps/unix/sysv/linux/x86/gettimeofday.c: ... here.  Also added
>>>       fallback configurable symbol when vDSO is not available.
>>>       * sysdeps/unix/sysv/linux/x86_64/time.c: Move to ...
>>>       * sysdeps/unix/sysv/linux/x86/time.c: ... here.  Also refactored to
>>>       be able to redefine fallback symbol when vDSO is not available.
>>>       * sysdeps/unix/sysv/linux/x86_64/timespec_get.c: Move to ...
>>>       * sysdeps/unix/sysv/linux/x86/timespec_get.c: ... here.
>>>
>>> --
>>>
>
>>> +# include <dl-vdso.h>
>>> +# include <errno.h>
>>> +
>>> +/* If the vDSO is not available we fall back on the syscall.  */
>>> +static int
>>> +__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
>>> +{
>>> +  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
>>> +}
>>> +# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
>>> +# undef libc_ifunc_hidden_def
>>> +# define libc_ifunc_hidden_def(name)  \
>>> +  libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
>
> Why do you define __GI___gettimeofday to __gettimeofday_syscall
> instead of the ifunc version? The x86-64 ifunc  works fine.
>
> --
> H.J.

Why isn't __GI_time IFUNC

5822: 000a3360    21 FUNC    LOCAL  DEFAULT   13 __GI_time


-- 
H.J.


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