Re: [PATCH 06/15] Add internal IFUNC call workaround

[Andreas Jaeger <aj at suse dot com>]

On 12/23/2012 04:02 AM, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> Avoid problems with internal hidden IFUNC calls on i386.
> See http://www.sourceware.org/bugzilla/show_bug.cgi?id=14961
> for more details

This patch could go in separately but please explain via email why this 
is needed.

> This actually improves performance on x86-64 because the
> call will go directly instead of through the PLT.
>
> 2012-12-22  Hongjiu Lu <hongjiu.lu@intel.com>
>
> 	* nptl/pthreadP.h (extern void __pthread_disable_asynccancel):
> 	* nptl/sysdeps/unix/sysv/linux/i386/i686/multiarch/Implies:
> 	* nptl/sysdeps/unix/sysv/linux/x86/multiarch/nptl-init.c:
> 	* nptl/sysdeps/unix/sysv/linux/x86_64/multiarch/Implies:

the ChangeLog entry is wrong - nptl has its own ChangeLog file and thus 
you do not need to add "nptl/" at the front. Also, the first and third 
entry contain no content about the change.

Could you resend this with proper ChangeLog and rationale, please?

Andreas

> ---
>   nptl/pthreadP.h                                    |    2 ++
>   .../unix/sysv/linux/i386/i686/multiarch/Implies    |    1 +
>   .../unix/sysv/linux/x86/multiarch/nptl-init.c      |   15 +++++++++++++++
>   .../unix/sysv/linux/x86_64/multiarch/Implies       |    1 +
>   4 files changed, 19 insertions(+), 0 deletions(-)
>   create mode 100644 nptl/sysdeps/unix/sysv/linux/i386/i686/multiarch/Implies
>   create mode 100644 nptl/sysdeps/unix/sysv/linux/x86/multiarch/nptl-init.c
>   create mode 100644 nptl/sysdeps/unix/sysv/linux/x86_64/multiarch/Implies
>
> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
> index fa89cbf..5cff300 100644
> --- a/nptl/pthreadP.h
> +++ b/nptl/pthreadP.h
> @@ -492,7 +492,9 @@ extern void __pthread_disable_asynccancel (int oldtype)
>   #if defined NOT_IN_libc && defined IS_IN_libpthread
>   hidden_proto (__pthread_mutex_init)
>   hidden_proto (__pthread_mutex_destroy)
> +# ifndef __pthread_mutex_lock
>   hidden_proto (__pthread_mutex_lock)
> +# endif
>   hidden_proto (__pthread_mutex_unlock)
>   hidden_proto (__pthread_rwlock_rdlock)
>   hidden_proto (__pthread_rwlock_wrlock)
> diff --git a/nptl/sysdeps/unix/sysv/linux/i386/i686/multiarch/Implies b/nptl/sysdeps/unix/sysv/linux/i386/i686/multiarch/Implies
> new file mode 100644
> index 0000000..a8518c7
> --- /dev/null
> +++ b/nptl/sysdeps/unix/sysv/linux/i386/i686/multiarch/Implies
> @@ -0,0 +1 @@
> +unix/sysv/linux/x86/multiarch
> diff --git a/nptl/sysdeps/unix/sysv/linux/x86/multiarch/nptl-init.c b/nptl/sysdeps/unix/sysv/linux/x86/multiarch/nptl-init.c
> new file mode 100644
> index 0000000..1d52a68
> --- /dev/null
> +++ b/nptl/sysdeps/unix/sysv/linux/x86/multiarch/nptl-init.c
> @@ -0,0 +1,15 @@
> +/* __pthread_initialize_minimal_internal () has
> +
> +   GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
> +
> +   This doesn't work with hidden IFUNC function.  See
> +
> +   http://www.sourceware.org/bugzilla/show_bug.cgi?id=14961
> +
> +   for details.  The work around is not to mark __pthread_mutex_lock
> +   hidden.  It also helps x86-64 since we now use the real function
> +   address at run-time, instead of its PLT entry.  */
> +
> +#define __pthread_mutex_lock __GI___pthread_mutex_lock
> +
> +#include <nptl/nptl-init.c>
> diff --git a/nptl/sysdeps/unix/sysv/linux/x86_64/multiarch/Implies b/nptl/sysdeps/unix/sysv/linux/x86_64/multiarch/Implies
> new file mode 100644
> index 0000000..a8518c7
> --- /dev/null
> +++ b/nptl/sysdeps/unix/sysv/linux/x86_64/multiarch/Implies
> @@ -0,0 +1 @@
> +unix/sysv/linux/x86/multiarch


--
 Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
  SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
   GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg)
    GPG fingerprint = 93A3 365E CE47 B889 DF7F  FED1 389A 563C C272 A126