PowerPC: Add time vDSO support

PowerPC kernel now provides a vDSO implementation for time syscall
(commit fcb41a2030abe0eb716ef0798035ef9562097f42). This patch changes
time syscall wrapper to use the vDSO when available. It also changes
the default non vDSO time on PowerPC to use sysdeps/posix/time.c
(since gettimeofday is a vDSO call).
(cherry picked from commit 83e7640f6bf68708ecf0b09d83c670203167271e)

5 files changed, 81 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 10e84d1193..5e721365c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2013-04-30  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+	* sysdeps/unix/sysv/linux/powerpc/Versions: Add __vdso_time symbol.
+	* sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h: Add __vdso_time
+	definition.
+	(VDSO_IFUNC_RET): Cast to void * to silence compiler warning.
+	* sysdeps/unix/sysv/linux/powerpc/init-first.c
+	(_libc_vdso_platform_setup): Add __vdso_time initialization.
+	* sysdeps/unix/sysv/linux/powerpc/time.c: New file: time implementation
+	for PowerPC using vDSO where is avaliable or gettimeofday as a fallback.
+
 2013-04-26  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
 
 	* sysdeps/powerpc/power5/fpu/s_modf.c: Moved to ...
diff --git a/sysdeps/unix/sysv/linux/powerpc/Versions b/sysdeps/unix/sysv/linux/powerpc/Versions
index 396a4236c1..289c4fe9b7 100644
--- a/sysdeps/unix/sysv/linux/powerpc/Versions
+++ b/sysdeps/unix/sysv/linux/powerpc/Versions
@@ -4,5 +4,6 @@ libc {
     __vdso_clock_gettime;
     __vdso_clock_getres;
     __vdso_getcpu;
+    __vdso_time;
   }
 }
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
index e4ae630580..f7f635ea17 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
@@ -32,14 +32,16 @@ extern void *__vdso_get_tbfreq;
 
 extern void *__vdso_getcpu;
 
+extern void *__vdso_time;
+
 /* 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
+#define VDSO_IFUNC_RET(value)  ((void *) &(value))
 #else
-#define VDSO_IFUNC_RET(value)  value
+#define VDSO_IFUNC_RET(value)  ((void *) (value))
 #endif
 
 #endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/init-first.c b/sysdeps/unix/sysv/linux/powerpc/init-first.c
index 5587e2acc6..3cefd9b073 100644
--- a/sysdeps/unix/sysv/linux/powerpc/init-first.c
+++ b/sysdeps/unix/sysv/linux/powerpc/init-first.c
@@ -28,7 +28,7 @@ void *__vdso_clock_gettime;
 void *__vdso_clock_getres;
 void *__vdso_get_tbfreq;
 void *__vdso_getcpu;
-
+void *__vdso_time;
 
 static inline void
 _libc_vdso_platform_setup (void)
@@ -44,6 +44,8 @@ _libc_vdso_platform_setup (void)
   __vdso_get_tbfreq = _dl_vdso_vsym ("__kernel_get_tbfreq", &linux2615);
 
   __vdso_getcpu = _dl_vdso_vsym ("__kernel_getcpu", &linux2615);
+
+  __vdso_time = _dl_vdso_vsym ("__kernel_time", &linux2615);
 }
 
 # define VDSO_SETUP _libc_vdso_platform_setup
diff --git a/sysdeps/unix/sysv/linux/powerpc/time.c b/sysdeps/unix/sysv/linux/powerpc/time.c
new file mode 100644
index 0000000000..66b4eb3049
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/powerpc/time.c
@@ -0,0 +1,62 @@
+/* time system call for Linux/PowerPC.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifdef SHARED
+
+# include <time.h>
+# include <sysdep.h>
+# include <bits/libc-vdso.h>
+
+void *time_ifunc (void) asm ("time");
+
+static time_t
+time_syscall (time_t *t)
+{
+  struct timeval tv;
+  time_t result;
+
+  if (INLINE_VSYSCALL (gettimeofday, 2, &tv, NULL) < 0)
+    result = (time_t) -1;
+  else
+    result = (time_t) tv.tv_sec;
+
+  if (t != NULL)
+    *t = result;
+  return result;
+}
+
+void *
+time_ifunc (void)
+{
+  /* If the vDSO is not available we fall back to the syscall.  */
+  return (__vdso_time ? VDSO_IFUNC_RET (__vdso_time)
+	  : time_syscall);
+}
+asm (".type time, %gnu_indirect_function");
+
+/* This is doing "libc_hidden_def (time)" but the compiler won't
+ * let us do it in C because it doesn't know we're defining time
+ * here in this file.  */
+asm (".globl __GI_time\n"
+     "__GI_time = time");
+
+#else
+
+#include <sysdeps/posix/time.c>
+
+#endif