PowerPC: gettimeofday optimization by using IFUNC

(backported from commit ef26eece6331a1f6d959818e37c438cc7ce68e53)

3 files changed, 52 insertions, 13 deletions

diff --git a/ChangeLog b/ChangeLog
index c070d94b76..af4974afd6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-03-15  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+	* sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h (VDSO_IFUNC_RET): Add
+	macro to return vdso values correctly in IFUNC implementations.
+	* sysdeps/unix/sysv/linux/powerpc/gettimeofday.c (__gettimeofday):
+	Optimization by using IFUNC.
+
 2013-03-08  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
 
 	* sysdeps/ieee754/ldbl-128ibm/math_ldbl.h (ldbl_pack): Rename to
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
index cda8491d94..e4ae630580 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
@@ -32,6 +32,16 @@ extern void *__vdso_get_tbfreq;
 
 extern void *__vdso_getcpu;
 
+/* This macro is needed for PPC64 to return a skeleton OPD entry of a vDSO
+   symbol.  This works because _dl_vdso_vsym always return the function
+   address, and no vDSO symbols use the TOC or chain pointers from the OPD
+   so we can allow them to be garbage.  */
+#if defined(__PPC64__) || defined(__powerpc64__)
+#define VDSO_IFUNC_RET(value)  &value
+#else
+#define VDSO_IFUNC_RET(value)  value
+#endif
+
 #endif
 
 #endif /* _LIBC_VDSO_H */
diff --git a/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c b/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
index 737613516f..4f4abbd1d5 100644
--- a/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
@@ -15,26 +15,48 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <sysdep.h>
-#include <bp-checks.h>
-#include <stddef.h>
 #include <sys/time.h>
-#include <time.h>
-#include <hp-timing.h>
 
-#include <bits/libc-vdso.h>
+#ifdef SHARED
 
-/* Get the current time of day and timezone information,
-   putting it into *TV and *TZ.  If TZ is NULL, *TZ is not filled.
-   Returns 0 on success, -1 on errors.  */
+# include <dl-vdso.h>
+# include <bits/libc-vdso.h>
+
+void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
+
+static int
+__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
+{
+  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
+}
+
+void *
+gettimeofday_ifunc (void)
+{
+  /* If the vDSO is not available we fall back syscall.  */
+  return (__vdso_gettimeofday ? VDSO_IFUNC_RET (__vdso_gettimeofday)
+	  : __gettimeofday_syscall);
+}
+asm (".type __gettimeofday, %gnu_indirect_function");
+
+/* This is doing "libc_hidden_def (__gettimeofday)" but the compiler won't
+   let us do it in C because it doesn't know we're defining __gettimeofday
+   here in this file.  */
+asm (".globl __GI___gettimeofday\n"
+     "__GI___gettimeofday = __gettimeofday");
+
+#else
+
+# include <sysdep.h>
+# include <errno.h>
 
 int
-__gettimeofday (tv, tz)
-     struct timeval *tv;
-     struct timezone *tz;
+__gettimeofday (struct timeval *tv, struct timezone *tz)
 {
-  return INLINE_VSYSCALL (gettimeofday, 2, CHECK_1 (tv), CHECK_1 (tz));
+  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
 }
 libc_hidden_def (__gettimeofday)
+
+#endif
 weak_alias (__gettimeofday, gettimeofday)
 libc_hidden_weak (gettimeofday)