+++ /dev/null
-#ifndef _LTTNG_TRACE_CLOCK_H
-#define _LTTNG_TRACE_CLOCK_H
-
-/*
- * wrapper/trace-clock.h
- *
- * Contains LTTng trace clock mapping to LTTng trace clock or mainline monotonic
- * clock. This wrapper depends on CONFIG_HIGH_RES_TIMERS=y.
- *
- * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This 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; only
- * version 2.1 of the License.
- *
- * This 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 this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#ifdef CONFIG_HAVE_TRACE_CLOCK
-#include <linux/trace-clock.h>
-#else /* CONFIG_HAVE_TRACE_CLOCK */
-
-#include <linux/hardirq.h>
-#include <linux/ktime.h>
-#include <linux/time.h>
-#include <linux/hrtimer.h>
-#include <linux/percpu.h>
-#include <linux/version.h>
-#include <asm/local.h>
-#include "../lttng-kernel-version.h"
-#include "percpu-defs.h"
-#include "random.h"
-
-#if ((LTTNG_KERNEL_RANGE(3,10,0, 3,10,14) && !LTTNG_RHEL_KERNEL_RANGE(3,10,0,7,0, 3,10,14,0,0)) \
- || LTTNG_KERNEL_RANGE(3,11,0, 3,11,3))
-#error "Linux kernels 3.10 and 3.11 introduce a deadlock in the timekeeping subsystem. Fixed by commit 7bd36014460f793c19e7d6c94dab67b0afcfcb7f \"timekeeping: Fix HRTICK related deadlock from ntp lock changes\" in Linux."
-#endif
-
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
-
-DECLARE_PER_CPU(local_t, lttng_last_tsc);
-
-#if (BITS_PER_LONG == 32)
-/*
- * Fixup "src_now" using the 32 LSB from "last". We need to handle overflow and
- * underflow of the 32nd bit. "last" can be above, below or equal to the 32 LSB
- * of "src_now".
- */
-static inline u64 trace_clock_fixup(u64 src_now, u32 last)
-{
- u64 now;
-
- now = src_now & 0xFFFFFFFF00000000ULL;
- now |= (u64) last;
- /* Detect overflow or underflow between now and last. */
- if ((src_now & 0x80000000U) && !(last & 0x80000000U)) {
- /*
- * If 32nd bit transitions from 1 to 0, and we move forward in
- * time from "now" to "last", then we have an overflow.
- */
- if (((s32) now - (s32) last) < 0)
- now += 0x0000000100000000ULL;
- } else if (!(src_now & 0x80000000U) && (last & 0x80000000U)) {
- /*
- * If 32nd bit transitions from 0 to 1, and we move backward in
- * time from "now" to "last", then we have an underflow.
- */
- if (((s32) now - (s32) last) > 0)
- now -= 0x0000000100000000ULL;
- }
- return now;
-}
-#else /* #if (BITS_PER_LONG == 32) */
-/*
- * The fixup is pretty easy on 64-bit architectures: "last" is a 64-bit
- * value, so we can use last directly as current time.
- */
-static inline u64 trace_clock_fixup(u64 src_now, u64 last)
-{
- return last;
-}
-#endif /* #else #if (BITS_PER_LONG == 32) */
-
-/*
- * Always called with preemption disabled. Can be interrupted.
- */
-static inline u64 trace_clock_monotonic_wrapper(void)
-{
- u64 now;
- unsigned long last, result;
- local_t *last_tsc;
-
- /* Use fast nmi-safe monotonic clock provided by the Linux kernel. */
- last_tsc = lttng_this_cpu_ptr(<tng_last_tsc);
- last = local_read(last_tsc);
- /*
- * Read "last" before "now". It is not strictly required, but it ensures
- * that an interrupt coming in won't artificially trigger a case where
- * "now" < "last". This kind of situation should only happen if the
- * mono_fast time source goes slightly backwards.
- */
- barrier();
- now = ktime_get_mono_fast_ns();
- if (((long) now - (long) last) < 0)
- now = trace_clock_fixup(now, last);
- result = local_cmpxchg(last_tsc, last, (unsigned long) now);
- if (result == last) {
- /* Update done. */
- return now;
- } else {
- /*
- * Update not done, due to concurrent update. We can use
- * "result", since it has been sampled concurrently with our
- * time read, so it should not be far from "now".
- */
- return trace_clock_fixup(now, result);
- }
-}
-
-#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
-static inline u64 trace_clock_monotonic_wrapper(void)
-{
- ktime_t ktime;
-
- /*
- * Refuse to trace from NMIs with this wrapper, because an NMI could
- * nest over the xtime write seqlock and deadlock.
- */
- if (in_nmi())
- return (u64) -EIO;
-
- ktime = ktime_get();
- return ktime_to_ns(ktime);
-}
-#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
-
-static inline u64 trace_clock_read64(void)
-{
- return (u64) trace_clock_monotonic_wrapper();
-}
-
-static inline u64 trace_clock_freq(void)
-{
- return (u64) NSEC_PER_SEC;
-}
-
-static inline int trace_clock_uuid(char *uuid)
-{
- return wrapper_get_bootid(uuid);
-}
-
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
-static inline int get_trace_clock(void)
-{
- printk(KERN_WARNING "LTTng: Using mainline kernel monotonic fast clock, which is NMI-safe.\n");
- return 0;
-}
-#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
-static inline int get_trace_clock(void)
-{
- printk(KERN_WARNING "LTTng: Using mainline kernel monotonic clock. NMIs will not be traced.\n");
- return 0;
-}
-#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
-
-static inline void put_trace_clock(void)
-{
-}
-
-#endif /* CONFIG_HAVE_TRACE_CLOCK */
-
-#endif /* _LTTNG_TRACE_CLOCK_H */
projects / lttng-modules.git / blobdiff