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Filename : timestamp_monotonic.stp
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// timestamp tapset -- monotonic clock variants
// Copyright (C) 2011 Red Hat Inc.
//
// This file is part of systemtap, and is free software.  You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.

%{
#include <linux/sched.h>
#if defined(STAPCONF_LINUX_SCHED_HEADERS)
#include <linux/sched/clock.h>
#endif

// Since scripts can run from quite arbitrary contexts, we can only use
// cpu_clock once it was made NMI safe.  This was in commit def0a9b2 for
// HAVE_UNSTABLE_SCHED_CLOCK archs (included in 2.6.32), and commit b9f8fcd5
// for the rest (included in 2.6.33).  So before that, we'll just pretend that
// cpu_clock and local_clock don't exist.
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,32)) \
    || (!defined (CONFIG_HAVE_UNSTABLE_SCHED_CLOCK) \
        && (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,33)))
#undef STAPCONF_CPU_CLOCK
#undef STAPCONF_LOCAL_CLOCK
#endif

// If we're falling back on gettimeofday, that machinery needs to be started.
#if !defined (STAPCONF_CPU_CLOCK)
#define STAP_NEED_GETTIMEOFDAY 1
#endif
%}


/**
 * sfunction cpu_clock_ns - Number of nanoseconds on the given cpu's clock
 * @cpu: Which processor's clock to read
 *
 * Description: This function returns the number of nanoseconds on the given
 * cpu's clock.  This is always monotonic comparing on the same cpu, but may
 * have some drift between cpus (within about a jiffy).
 */
function cpu_clock_ns:long (cpu:long) %{ /* pure */ /* unprivileged */
#if defined (STAPCONF_CPU_CLOCK)
  if (likely(STAP_ARG_cpu >= 0 && STAP_ARG_cpu < NR_CPUS && cpu_online(STAP_ARG_cpu)))
    STAP_RETVALUE = cpu_clock(STAP_ARG_cpu);
  else
    {
      snprintf(CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
               "cpu %lld is not online", STAP_ARG_cpu);
      CONTEXT->last_error = CONTEXT->error_buffer;
    }
#else
  /* NOTE: we can't use do_gettimeofday because we could be called from a
   * context where xtime_lock is already held.  See bug #2525. */
  STAP_RETVALUE = _stp_gettimeofday_ns();
  if (STAP_RETVALUE < 0)
    CONTEXT->last_error = "gettimeofday not initialized";
#endif
%}

/**
 * sfunction cpu_clock_us - Number of microseconds on the given cpu's clock
 * @cpu: Which processor's clock to read
 *
 * Description: This function returns the number of microseconds on the given
 * cpu's clock.  This is always monotonic comparing on the same cpu, but may
 * have some drift between cpus (within about a jiffy).
 */
function cpu_clock_us:long (cpu:long) {
  return cpu_clock_ns(cpu) / 1000;
}

/**
 * sfunction cpu_clock_ms - Number of milliseconds on the given cpu's clock
 * @cpu: Which processor's clock to read
 *
 * Description: This function returns the number of milliseconds on the given
 * cpu's clock.  This is always monotonic comparing on the same cpu, but may
 * have some drift between cpus (within about a jiffy).
 */
function cpu_clock_ms:long (cpu:long) {
  return cpu_clock_ns(cpu) / 1000000;
}

/**
 * sfunction cpu_clock_s - Number of seconds on the given cpu's clock
 * @cpu: Which processor's clock to read
 *
 * Description: This function returns the number of seconds on the given cpu's
 * clock.  This is always monotonic comparing on the same cpu, but may have
 * some drift between cpus (within about a jiffy).
 */
function cpu_clock_s:long (cpu:long) {
  return cpu_clock_ns(cpu) / 1000000000;
}


/**
 * sfunction local_clock_ns - Number of nanoseconds on the local cpu's clock
 *
 * Description: This function returns the number of nanoseconds on the local
 * cpu's clock.  This is always monotonic comparing on the same cpu, but may
 * have some drift between cpus (within about a jiffy).
 */
function local_clock_ns:long () %{ /* pure */ /* unprivileged */
#if defined (STAPCONF_LOCAL_CLOCK)
  STAP_RETVALUE = local_clock();
#elif defined (STAPCONF_CPU_CLOCK)
  STAP_RETVALUE = cpu_clock(smp_processor_id());
#else
  /* NOTE: we can't use do_gettimeofday because we could be called from a
   * context where xtime_lock is already held.  See bug #2525. */
  STAP_RETVALUE = _stp_gettimeofday_ns();
  if (STAP_RETVALUE < 0)
    CONTEXT->last_error = "gettimeofday not initialized";
#endif
%}

/**
 * sfunction local_clock_us - Number of microseconds on the local cpu's clock
 *
 * Description: This function returns the number of microseconds on the local
 * cpu's clock.  This is always monotonic comparing on the same cpu, but may
 * have some drift between cpus (within about a jiffy).
 */
function local_clock_us:long () {
  return local_clock_ns() / 1000;
}

/**
 * sfunction local_clock_ms - Number of milliseconds on the local cpu's clock
 *
 * Description: This function returns the number of milliseconds on the local
 * cpu's clock.  This is always monotonic comparing on the same cpu, but may
 * have some drift between cpus (within about a jiffy).
 */
function local_clock_ms:long () {
  return local_clock_ns() / 1000000;
}

/**
 * sfunction local_clock_s - Number of seconds on the local cpu's clock
 *
 * Description: This function returns the number of seconds on the local cpu's
 * clock.  This is always monotonic comparing on the same cpu, but may have
 * some drift between cpus (within about a jiffy).
 */
function local_clock_s:long () {
  return local_clock_ns() / 1000000000;
}


/**
 * sfunction ktime_get_ns - Number of nanoseconds since boot
 *
 * Description: This function returns the system ktime.
 */
function ktime_get_ns:long () %{
  /* pure */ /* unprivileged */
  STAP_RETURN ((int64_t) ktime_get_ns());
%}