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[PATCH] PowerPC - Add a function to read the Time Base frequency
- From: "Tulio Magno Quites Machado Filho" <tuliom at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Fri, 24 Aug 2012 15:35:51 -0300
- Subject: [PATCH] PowerPC - Add a function to read the Time Base frequency
Programs that directly read the Time Base register need to get
access to the frequency at which it is updated to properly calculate the
time passed between 2 reads.
librt already has __get_clockfreq that reads this value from the vdso or
from /proc/cpuinfo. The new function reuses the available one without
exposing it.
Notice that this patch does include __get_clockfreq implementation into
the PowerPC build of libc. However, it will remain out of libc for other
architectures.
2012-08-22 Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
* manual/platform.texi (PowerPC): Documents __ppc_get_timebase_freq.
* sysdeps/powerpc/sys/platform/ppc.h: Include the operating
system header.
* sysdeps/unix/sysv/linux/powerpc/Makefile (sysdep_headers):
Likewise.
(sydep_routines): Add the new and the internal functions.
* sysdeps/unix/sysv/linux/powerpc/bits/ppc.h: New file.
* sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/Versions
(GLIBC_2.17): Add the new function.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/nptl/libc.abilist
(GLIBC_2.17): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions
(GLIBC_2.17): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/nptl/libc.abilist
(GLIBC_2.17): Likewise.
* sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq.c: New file.
---
manual/platform.texi | 8 +++
sysdeps/powerpc/sys/platform/ppc.h | 1 +
sysdeps/unix/sysv/linux/powerpc/Makefile | 6 ++
sysdeps/unix/sysv/linux/powerpc/bits/ppc.h | 33 ++++++++++
.../unix/sysv/linux/powerpc/get_timebase_freq.c | 26 ++++++++
sysdeps/unix/sysv/linux/powerpc/powerpc32/Versions | 3 +
.../linux/powerpc/powerpc32/fpu/nptl/libc.abilist | 1 +
sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions | 3 +
.../sysv/linux/powerpc/powerpc64/nptl/libc.abilist | 1 +
.../unix/sysv/linux/powerpc/test-gettimebasefreq.c | 62 ++++++++++++++++++++
10 files changed, 144 insertions(+), 0 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/powerpc/bits/ppc.h
create mode 100644 sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
create mode 100644 sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq.c
diff --git a/manual/platform.texi b/manual/platform.texi
index 02b5c55..e387ff4 100644
--- a/manual/platform.texi
+++ b/manual/platform.texi
@@ -26,3 +26,11 @@ different from the processor frequency. More information is available in
without requiring assistance from the operating system, so it is very
efficient.
@end deftypefun
+
+@deftypefun {uint64_t} __ppc_get_timebase_freq (void)
+Read the current frequency at which the Time Base Register is updated.
+
+This frequency is not related to the processor clock or the bus clock.
+It is also possible that this frequency is not constant. More information is
+available in @cite{Power ISA 2.06b - Book II - Section 5.2}.
+@end deftypefun
diff --git a/sysdeps/powerpc/sys/platform/ppc.h b/sysdeps/powerpc/sys/platform/ppc.h
index 165652c..3780f57 100644
--- a/sysdeps/powerpc/sys/platform/ppc.h
+++ b/sysdeps/powerpc/sys/platform/ppc.h
@@ -20,6 +20,7 @@
#define _SYS_PLATFORM_PPC_H 1
#include <stdint.h>
+#include <bits/ppc.h>
/* Read the Time Base Register. */
static inline uint64_t
diff --git a/sysdeps/unix/sysv/linux/powerpc/Makefile b/sysdeps/unix/sysv/linux/powerpc/Makefile
index f6dccd9..6bdf4dc 100644
--- a/sysdeps/unix/sysv/linux/powerpc/Makefile
+++ b/sysdeps/unix/sysv/linux/powerpc/Makefile
@@ -16,3 +16,9 @@ endif
ifeq ($(subdir),elf)
sysdep_routines += dl-vdso
endif
+
+ifeq ($(subdir),misc)
+sysdep_headers += bits/ppc.h
+sysdep_routines += get_clockfreq get_timebase_freq
+tests += test-gettimebasefreq
+endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/ppc.h b/sysdeps/unix/sysv/linux/powerpc/bits/ppc.h
new file mode 100644
index 0000000..76542d9
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/ppc.h
@@ -0,0 +1,33 @@
+/* Facilities specific to the PowerPC architecture on Linux
+ Copyright (C) 2012 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/>. */
+
+#ifndef _BITS_PPC_H
+#define _BITS_PPC_H
+
+#ifndef _SYS_PLATFORM_PPC_H
+# error "Never include this file directly; use <sys/platform/ppc.h> instead."
+#endif
+
+__BEGIN_DECLS
+
+/* Read the time base frequency. */
+extern uint64_t __ppc_get_timebase_freq (void);
+
+__END_DECLS
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
new file mode 100644
index 0000000..f62ed86
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
@@ -0,0 +1,26 @@
+/* Get the frequency of the time base.
+ Copyright (C) 2012 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/>. */
+
+#include <libc-internal.h>
+
+uint64_t
+__get_timebase_freq (void)
+{
+ return (uint64_t) __get_clockfreq ();
+}
+weak_alias (__get_timebase_freq, __ppc_get_timebase_freq)
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/Versions b/sysdeps/unix/sysv/linux/powerpc/powerpc32/Versions
index 6fa0119..8d1c3a5 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/Versions
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/Versions
@@ -30,4 +30,7 @@ libc {
GLIBC_2.11 {
fallocate64;
}
+ GLIBC_2.17 {
+ __ppc_get_timebase_freq;
+ }
}
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/nptl/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/nptl/libc.abilist
index 75123b9..ab96361 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/nptl/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/nptl/libc.abilist
@@ -1775,6 +1775,7 @@ GLIBC_2.16
GLIBC_2.17
GLIBC_2.17 A
secure_getenv F
+ __ppc_get_timebase_freq F
GLIBC_2.2
GLIBC_2.2 A
_IO_adjust_wcolumn F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions b/sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions
index 8334741..3ff01d1 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions
@@ -19,4 +19,7 @@ libc {
setcontext;
swapcontext;
}
+ GLIBC_2.17 {
+ __ppc_get_timebase_freq;
+ }
}
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/nptl/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/nptl/libc.abilist
index e2484d3..a60b72a 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/nptl/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/nptl/libc.abilist
@@ -81,6 +81,7 @@ GLIBC_2.16
GLIBC_2.17
GLIBC_2.17 A
secure_getenv F
+ __ppc_get_timebase_freq F
GLIBC_2.3
GLIBC_2.3 A
_Exit F
diff --git a/sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq.c b/sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq.c
new file mode 100644
index 0000000..a3f3bd6
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq.c
@@ -0,0 +1,62 @@
+/* Check __ppc_get_timebase_freq() for architecture changes
+ Copyright (C) 2012 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/>. */
+
+/* Test if __ppc_get_timebase_freq() works and is different from zero. A read
+ failure might indicate a Linux Kernel change.
+ This test also use the frequency to compute the real elapsed time. */
+
+#include <inttypes.h>
+#include <stdio.h>
+
+#include <sys/platform/ppc.h>
+
+/* Maximum value of the Time Base Register: 2^60 - 1. */
+#define MAX_TB 0xFFFFFFFFFFFFFFF
+
+static int
+do_test (void)
+{
+ uint64_t t1, t2, f, diff;
+
+ t1 = __ppc_get_timebase ();
+ printf ("t1 = %"PRIu64"\n", t1);
+
+ f = __ppc_get_timebase_freq ();
+ printf ("Time Base frequency = %"PRIu64" Hz\n", f);
+
+ if (f == 0) {
+ printf ("Fail: The time base frequency can't be zero.");
+ return 1;
+ }
+
+ t2 = __ppc_get_timebase ();
+ printf ("t2 = %"PRIu64"\n", t2);
+
+ if (t2 > t1) {
+ diff = t2 - t1;
+ } else {
+ diff = (MAX_TB - t2) + t1;
+ }
+
+ printf ("Elapsed time = %1.2f usecs\n", (double) diff * 1000000 / f );
+
+ return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
--
1.7.7.6