[PATCH] S390: Add support for HP_TIMING_NOW.

[Stefan Liebler <stli@linux.ibm.com>]

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Hi,

this patch adds support for HP_TIMING_NOW if we build at least
with -march=z10 -mzarch.  Otherwise we are still using the
generic hp-timing.h.

Bye,
Stefan

ChangeLog:

	* sysdeps/s390/hp-timing.h: New file.

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commit 9a0d12c72043f54b7a810a5d7ee0fabdec574bb6
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Thu Sep 5 13:37:45 2019 +0200

    S390: Add support for HP_TIMING_NOW.
    
    This patch adds support for HP_TIMING_NOW if we build at least
    with -march=z10 -mzarch.  Otherwise we are still using the
    generic hp-timing.h.
    
    ChangeLog:
    
            * sysdeps/s390/hp-timing.h: New file.

diff --git a/sysdeps/s390/hp-timing.h b/sysdeps/s390/hp-timing.h
new file mode 100644
index 0000000000..b54b8dda9b
--- /dev/null
+++ b/sysdeps/s390/hp-timing.h
@@ -0,0 +1,42 @@
+/* High precision, low overhead timing functions.  s390 version.
+   Copyright (C) 2019 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 _HP_TIMING_H
+
+/* The stckf instruction is available starting with z9-109 zarch CPUs.
+   As there is no extra configure check for z9-109, the z10 one is used.  */
+#ifdef HAVE_S390_MIN_Z10_ZARCH_ASM_SUPPORT
+# define _HP_TIMING_H	1
+# include <hp-timing-common.h>
+
+/* We use 64 bit values for the times.
+   Note: Bit 51 is incremented every 0.000 001s = 1us.  */
+typedef unsigned long long int hp_timing_t;
+
+# define HP_TIMING_INLINE	(1)
+
+# define HP_TIMING_NOW(VAR)						\
+  do {									\
+    __asm__ __volatile__ ("stckf %0" : "=Q" (VAR) : : "cc");		\
+  } while (0)
+
+#else
+# include_next <hp-timing.h>
+#endif
+
+#endif	/* hp-timing.h */