From patchwork Mon Jul 4 13:45:09 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Liebler X-Patchwork-Id: 13614 Received: (qmail 9253 invoked by alias); 4 Jul 2016 13:53:23 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 9234 invoked by uid 89); 4 Jul 2016 13:53:23 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.6 required=5.0 tests=AWL, BAYES_00, RCVD_IN_DNSWL_LOW, RP_MATCHES_RCVD, SPF_HELO_PASS, SPF_PASS autolearn=ham version=3.3.2 spammy=inhibit X-HELO: plane.gmane.org To: libc-alpha@sourceware.org From: Stefan Liebler Subject: Re: [PATCH 3/8] i386, x86: Use libc_ifunc macro for time, gettimeofday. Date: Mon, 4 Jul 2016 15:45:09 +0200 Lines: 239 Message-ID: References: <1466682952-6301-1-git-send-email-stli@linux.vnet.ibm.com> <1466682952-6301-3-git-send-email-stli@linux.vnet.ibm.com> Mime-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 In-Reply-To: On 07/04/2016 10:54 AM, Florian Weimer wrote: > On 06/23/2016 01:55 PM, Stefan Liebler wrote: >> This patch uses the libc_ifunc macro to create already existing ifunc >> functions >> time and gettimeofday on intel. This way, the libc_hidden_def macro >> can be used >> instead of the libc_ifunc_hidden_def one which was only used here. >> Thus the >> macro is removed from libc-symbols.h. >> On i386, the __GI_* symbols do not target the ifunc symbol and thus the >> redirection construct has to be applied here. > > I'm not sure if I understand what is going on here. > sysdeps/unix/sysv/linux/x86/gettimeofday.c is compiled straight for > x86_64, but wrapped on i386, right? Yes you are right, e.g. ...: -x86_64 compiles sysdeps/unix/sysv/linux/x86/gettimeofday.c -i686 compiles sysdeps/unix/sysv/linux/i386/gettimeofday.c > > I wonder if it possible to avoid some of the preprocessor magic by > introducing a separate x86_64 file. Do you mean moving x86/gettimeofday.c to x86_64/gettimeofday.c and get rid of #include ? I think it won't save much of the preprocessor stuff. The redirection of __gettimeofday in sys/time.h and the redifinition of libc_hidden_def are needed. We can only save the define/undef __gettimeofday around inclusion of x86/gettimeofday.c. But then we have to duplicate the code. In file sysdeps/unix/sysv/linux/i386/time.c we can't save anything. > > Thanks, > Florian > The attached patch only updates the typo in ChangeLog. From a8ea51a141f137447a6a483cb820bcc12b265675 Mon Sep 17 00:00:00 2001 From: Stefan Liebler Date: Mon, 4 Jul 2016 15:33:56 +0200 Subject: [PATCH 3/8] i386, x86: Use libc_ifunc macro for time, gettimeofday. This patch uses the libc_ifunc macro to create already existing ifunc functions time and gettimeofday on intel. This way, the libc_hidden_def macro can be used instead of the libc_ifunc_hidden_def one which was only used here. Thus the macro is removed from libc-symbols.h. On i386, the __GI_* symbols do not target the ifunc symbol and thus the redirection construct has to be applied here. ChangeLog: * sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday): Use libc_ifunc macro. Use libc_hidden_def instead of libc_ifunc_hidden_def. * sysdeps/unix/sysv/linux/x86/time.c (time): Likewise. * sysdeps/unix/sysv/linux/i386/gettimeofday.c (__gettimeofday): Redirect ifunced function in header and create a copy of the prototype for using as ifunc function. Add appropriate aliases to the real symbol names. * sysdeps/unix/sysv/linux/i386/time.c (time): Likewise. * include/libc-symbols.h (libc_ifunc_hidden_def, libc_ifunc_hidden_def1): Delete macro. --- include/libc-symbols.h | 15 --------------- sysdeps/unix/sysv/linux/i386/gettimeofday.c | 19 ++++++++++++++++--- sysdeps/unix/sysv/linux/i386/time.c | 15 ++++++++++++--- sysdeps/unix/sysv/linux/x86/gettimeofday.c | 20 ++++++-------------- sysdeps/unix/sysv/linux/x86/time.c | 18 +++++------------- 5 files changed, 39 insertions(+), 48 deletions(-) diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 5938eae..b0ea8f4 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -730,21 +730,6 @@ for linking") #define libm_ifunc_init() #define libm_ifunc(name, expr) __ifunc (name, expr, void, libm_ifunc_init) -#ifdef HAVE_ASM_SET_DIRECTIVE -# define libc_ifunc_hidden_def1(local, name) \ - __asm__ (".globl " #local "\n\t" \ - ".hidden " #local "\n\t" \ - ".set " #local ", " #name); -#else -# define libc_ifunc_hidden_def1(local, name) \ - __asm__ (".globl " #local "\n\t" \ - ".hidden " #local "\n\t" \ - #local " = " #name); -#endif - -#define libc_ifunc_hidden_def(name) \ - libc_ifunc_hidden_def1 (__GI_##name, name) - /* Add the compiler optimization to inhibit loop transformation to library calls. This is used to avoid recursive calls in memset and memmove default implementations. */ diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c index 965bb81..fc6cfdd 100644 --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c @@ -16,14 +16,27 @@ License along with the GNU C Library; if not, see . */ +#ifdef SHARED +# define __gettimeofday __redirect___gettimeofday +#endif + #include #ifdef SHARED +# undef __gettimeofday -# undef libc_ifunc_hidden_def -# define libc_ifunc_hidden_def(name) \ - libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall) +extern __typeof (__redirect___gettimeofday) __libc___gettimeofday; +# define __gettimeofday __libc___gettimeofday +# undef libc_hidden_def +# define libc_hidden_def(name) \ + __hidden_ver1 (__gettimeofday_syscall, __GI___gettimeofday, \ + __gettimeofday_syscall); #endif #include + +#ifdef SHARED +# undef __gettimeofday +strong_alias (__libc___gettimeofday, __gettimeofday) +#endif diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c index 62b78b2..bacbf84 100644 --- a/sysdeps/unix/sysv/linux/i386/time.c +++ b/sysdeps/unix/sysv/linux/i386/time.c @@ -17,10 +17,19 @@ . */ #ifdef SHARED +# define time __redirect_time +#endif + +#include + +#ifdef SHARED +# undef time + +extern __typeof (__redirect_time) time; -# undef libc_ifunc_hidden_def -# define libc_ifunc_hidden_def(name) \ - libc_ifunc_hidden_def1 (__GI_##name, __time_syscall) +# undef libc_hidden_def +# define libc_hidden_def(name) \ + __hidden_ver1 (__time_syscall, __GI_time, __time_syscall); #endif #include diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c index 36f7c26..02f8d6e 100644 --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c @@ -29,20 +29,12 @@ __gettimeofday_syscall (struct timeval *tv, struct timezone *tz) return INLINE_SYSCALL (gettimeofday, 2, tv, tz); } -void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday"); - -void * -gettimeofday_ifunc (void) -{ - PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); - - /* If the vDSO is not available we fall back to syscall. */ - return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26) - ?: (void*) (&__gettimeofday_syscall)); -} -asm (".type __gettimeofday, %gnu_indirect_function"); - -libc_ifunc_hidden_def(__gettimeofday) +# undef INIT_ARCH +# define INIT_ARCH() PREPARE_VERSION_KNOWN (linux26, LINUX_2_6) +/* If the vDSO is not available we fall back to syscall. */ +libc_ifunc (__gettimeofday, (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26) + ?: &__gettimeofday_syscall)) +libc_hidden_def (__gettimeofday) #else diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c index f5f7f91..957d586 100644 --- a/sysdeps/unix/sysv/linux/x86/time.c +++ b/sysdeps/unix/sysv/linux/x86/time.c @@ -30,20 +30,12 @@ __time_syscall (time_t *t) return INTERNAL_SYSCALL (time, err, 1, t); } -void *time_ifunc (void) __asm__ ("time"); - -void * -time_ifunc (void) -{ - PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); - +#undef INIT_ARCH +#define INIT_ARCH() PREPARE_VERSION_KNOWN (linux26, LINUX_2_6); /* If the vDSO is not available we fall back on the syscall. */ - return _dl_vdso_vsym ("__vdso_time", &linux26) - ?: (void*) &__time_syscall; -} -asm (".type time, %gnu_indirect_function"); - -libc_ifunc_hidden_def(time) +libc_ifunc (time, (_dl_vdso_vsym ("__vdso_time", &linux26) + ?: &__time_syscall)) +libc_hidden_def (time) #else -- 2.3.0