Update.

2001-04-21  Ulrich Drepper  <drepper@redhat.com>

	* elf/dl-support.c: Include cpuclock-init.h.  Use CPUCLOCK_VARDEF and
	CPUCLOCK_INIT if defined.
	* sysdeps/generic/dl-sysdep.c: Likewise.
	* sysdeps/generic/cpuclock-init.h: New file.
	* sysdeps/unix/i386/i586/cpuclock-init.h: New file.
	* sysdeps/unix/i386/i586/Versions: New file.
	* sysdeps/unix/i386/i586/clock_settime.c: New file.
	* sysdeps/unix/i386/i586/clock_gettime.c: Handle thread CPU clock
	separately by calling __pthread_clock_gettime if this function is
	available.  Subtract offset from tsc value before computing time value.

4 files changed, 156 insertions, 8 deletions

diff --git a/sysdeps/unix/i386/i586/Versions b/sysdeps/unix/i386/i586/Versions
new file mode 100644
index 0000000000..4242ca448a
--- /dev/null
+++ b/sysdeps/unix/i386/i586/Versions
@@ -0,0 +1,5 @@
+ld {
+  GLIBC_2.2.3 {
+    _dl_cpuclock_offset;
+  }
+}
diff --git a/sysdeps/unix/i386/i586/clock_gettime.c b/sysdeps/unix/i386/i586/clock_gettime.c
index 85dcdcfe68..5e28370acf 100644
--- a/sysdeps/unix/i386/i586/clock_gettime.c
+++ b/sysdeps/unix/i386/i586/clock_gettime.c
@@ -19,6 +19,9 @@
 #include <time.h>
 #include <libc-internal.h>
 
+#include "cpuclock-init.h"
+
+
 /* This implementation uses the TSC register in modern (i586 and up) IA-32
    processors (most modern clones also provide it).  Since we need the
    resolution of the clock and since determining this is not cheap, we
@@ -33,17 +36,42 @@
 static unsigned long long int freq;
 
 
-/* We add an limitation here: we assume that the machine is not up as
-   long as it takes to wrap-around the 64-bit timestamp counter.  On a
-   4GHz machine it would take 136 years of uptime to wrap around so
-   this "limitation" is not severe.
+/* We need the starting time for the process.  */
+CPUCLOCK_VARDECL (_dl_cpuclock_offset);
+
+
+/* This function is defined in the thread library.  */
+extern int __pthread_clock_gettime (unsigned long long int freq,
+				    struct timespec *tp)
+     __attribute__ ((__weak__));
+
 
-   We use this clock also as the monotonic clock since we don't allow
-   setting the CPU-time clock.  If this should ever change we will have
-   to separate the two.  */
+/* We add an limitation here: we assume that the process is not
+   running as long as it takes to wrap-around the 64-bit timestamp
+   counter.  On a 4GHz machine it would take 136 years of uptime to
+   wrap around so this "limitation" is not severe.  */
 #define EXTRA_CLOCK_CASES \
-  case CLOCK_PROCESS_CPUTIME_ID:					      \
   case CLOCK_THREAD_CPUTIME_ID:						      \
+    if (__pthread_clock_gettime != NULL)				      \
+      {									      \
+	if (__builtin_expect (freq == 0, 0))				      \
+	  {								      \
+	    /* This can only happen if we haven't initialized the `freq'      \
+	       variable yet.  Do this now. We don't have to protect this      \
+	       code against multiple execution since all of them should	      \
+	       lead to the same result.  */				      \
+	    freq = __get_clockfreq ();					      \
+	    if (__builtin_expect (freq == 0, 0))			      \
+	      /* Something went wrong.  */				      \
+	      break;							      \
+	  }								      \
+									      \
+	retval = __pthread_clock_gettime (freq, tp);			      \
+	break;								      \
+      }									      \
+    /* FALLTHROUGH */							      \
+									      \
+  case CLOCK_PROCESS_CPUTIME_ID:					      \
     {									      \
       unsigned long long int tsc;					      \
 									      \
@@ -62,6 +90,9 @@ static unsigned long long int freq;
       /* Get the current counter.  */					      \
       asm volatile ("rdtsc" : "=A" (tsc));				      \
 									      \
+      /* Compute the offset since the start time of the process.  */	      \
+      tsc -= _dl_cpuclock_offset;					      \
+									      \
       /* Compute the seconds.  */					      \
       tp->tv_sec = tsc / freq;						      \
 									      \
diff --git a/sysdeps/unix/i386/i586/clock_settime.c b/sysdeps/unix/i386/i586/clock_settime.c
new file mode 100644
index 0000000000..465a68f694
--- /dev/null
+++ b/sysdeps/unix/i386/i586/clock_settime.c
@@ -0,0 +1,85 @@
+/* Copyright (C) 2001 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 Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <time.h>
+
+#include "cpuclock-init.h"
+
+
+/* This implementation uses the TSC register in modern (i586 and up) IA-32
+   processors (most modern clones also provide it).  Since we need the
+   resolution of the clock and since determining this is not cheap, we
+   cache the value.  But this means that systems with processors running
+   at different speeds or process migration to machines with slower or
+   faster processors will not work without changes.  */
+
+
+/* Clock frequency of the processor.  We make it a 64-bit variable
+   because some jokers are already playing with processors with more
+   than 4GHz.  */
+static unsigned long long int freq;
+
+
+/* We need the starting time for the process.  */
+CPUCLOCK_VARDECL (_dl_cpuclock_offset);
+
+
+/* This function is defined in the thread library.  */
+extern void __pthread_clock_settime (unsigned long long int offset)
+     __attribute__ ((__weak__));
+
+
+/* We add an limitation here: we assume that the process is not
+   running as long as it takes to wrap-around the 64-bit timestamp
+   counter.  On a 4GHz machine it would take 136 years of uptime to
+   wrap around so this "limitation" is not severe.  */
+#define EXTRA_CLOCK_CASES \
+  case CLOCK_PROCESS_CPUTIME_ID:					      \
+  case CLOCK_THREAD_CPUTIME_ID:						      \
+    {									      \
+      unsigned long long int tsc;					      \
+      unsigned long long int usertime;					      \
+									      \
+      /* First thing is to get the current time.  */			      \
+      asm volatile ("rdtsc" : "=A" (tsc));				      \
+									      \
+      if (__builtin_expect (freq == 0, 0))				      \
+	{								      \
+	  /* This can only happen if we haven't initialized the `freq'	      \
+	     variable yet.  Do this now. We don't have to protect this	      \
+	     code against multiple execution since all of them should	      \
+	     lead to the same result.  */				      \
+	  freq = __get_clockfreq ();					      \
+	  if (__builtin_expect (freq == 0, 0))				      \
+	    /* Something went wrong.  */				      \
+	    break;							      \
+	}								      \
+									      \
+      /* Convert the user-provided time into CPU ticks.  */		      \
+      usertime = tp->tv_sec * freq + (tp->tv_nsec * freq) / 1000000000ull;    \
+									      \
+      /* Determine the offset and use it as the new base value.  */	      \
+      if (clock_id != CLOCK_THREAD_CPUTIME_ID				      \
+	  || __pthread_clock_settime == NULL)				      \
+	_dl_cpuclock_offset = tsc - usertime;				      \
+      else								      \
+	__pthread_clock_settime (tsc - usertime);			      \
+    }									      \
+  break;
+
+#include <sysdeps/unix/clock_settime.c>
diff --git a/sysdeps/unix/i386/i586/cpuclock-init.h b/sysdeps/unix/i386/i586/cpuclock-init.h
new file mode 100644
index 0000000000..ff1ff9752a
--- /dev/null
+++ b/sysdeps/unix/i386/i586/cpuclock-init.h
@@ -0,0 +1,27 @@
+/* x86 TSC based CPU clock initialization code.
+   Copyright (C) 2001 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 Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/* The TSC value has 64 bits.  */
+#define CPUCLOCK_VARDEF(name) unsigned long long int name
+
+/* A declaration.  */
+#define CPUCLOCK_VARDECL(name) extern unsigned long long int name
+
+/* Reading the TSC value is a simple instruction.  */
+#define CPUCLOCK_INIT(name) asm volatile ("rdtsc" : "=A" (name))