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2017-04-14time: Change k_clock clock_get() to use timespec64Deepa Dinamani
struct timespec is not y2038 safe on 32 bit machines. Replace uses of struct timespec with struct timespec64 in the kernel. The syscall interfaces themselves will be changed in a separate series. Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Cc: y2038@lists.linaro.org Cc: john.stultz@linaro.org Cc: arnd@arndb.de Link: http://lkml.kernel.org/r/1490555058-4603-4-git-send-email-deepa.kernel@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-14time: Delete do_sys_setimeofday()Deepa Dinamani
struct timespec is not y2038 safe on 32 bit machines and needs to be replaced with struct timespec64. do_sys_timeofday() is just a wrapper function. Replace all calls to this function with direct calls to do_sys_timeofday64() instead and delete do_sys_timeofday(). Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Cc: y2038@lists.linaro.org Cc: john.stultz@linaro.org Cc: arnd@arndb.de Cc: linux-alpha@vger.kernel.org Link: http://lkml.kernel.org/r/1490555058-4603-2-git-send-email-deepa.kernel@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-03sched/headers, timekeeping: Move the timer tick function prototypes to ↵Ingo Molnar
<linux/timekeeping.h> Move the update_process_times() and xtime_update() prototypes to <linux/timekeeping.h>. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-12-25clocksource: Use a plain u64 instead of cycle_tThomas Gleixner
There is no point in having an extra type for extra confusion. u64 is unambiguous. Conversion was done with the following coccinelle script: @rem@ @@ -typedef u64 cycle_t; @fix@ typedef cycle_t; @@ -cycle_t +u64 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org>
2016-11-29timekeeping: Add a fast and NMI safe boot clockJoel Fernandes
This boot clock can be used as a tracing clock and will account for suspend time. To keep it NMI safe since we're accessing from tracing, we're not using a separate timekeeper with updates to monotonic clock and boot offset protected with seqlocks. This has the following minor side effects: (1) Its possible that a timestamp be taken after the boot offset is updated but before the timekeeper is updated. If this happens, the new boot offset is added to the old timekeeping making the clock appear to update slightly earlier: CPU 0 CPU 1 timekeeping_inject_sleeptime64() __timekeeping_inject_sleeptime(tk, delta); timestamp(); timekeeping_update(tk, TK_CLEAR_NTP...); (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be partially updated. Since the tk->offs_boot update is a rare event, this should be a rare occurrence which postprocessing should be able to handle. Signed-off-by: Joel Fernandes <joelaf@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1480372524-15181-6-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-22timekeeping: Include the correct header for errno definitionsChristoph Hellwig
asm-generic headers are only defaults for architectures. We need to get the proper defintion, which goes through <linux/errno.h> and <asm/errno.h>. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: john.stultz@linaro.org Link: http://lkml.kernel.org/r/1474555697-8206-1-git-send-email-hch@lst.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-06-01time: Make settimeofday error checking work againJohn Stultz
In commit 86d3473224b0 some of the checking for a valid timeval was subtley changed which caused -EINVAL to be returned whenever the timeval was null. However, it is possible to set the timezone data while specifying a NULL timeval, which is usually done to handle systems where the RTC keeps local time instead of UTC. Thus the patch causes such systems to have the time incorrectly set. This patch addresses the issue by handling the error conditionals in the same way as was done previously. Fixes: 86d3473224b0 "time: Introduce do_sys_settimeofday64()" Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Baolin Wang <baolin.wang@linaro.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Link: http://lkml.kernel.org/r/1464807207-16530-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-04-22time: Introduce do_sys_settimeofday64()Baolin Wang
The do_sys_settimeofday() function uses a timespec, which is not year 2038 safe on 32bit systems. Thus this patch introduces do_sys_settimeofday64(), which allows us to transition users of do_sys_settimeofday() to using 64bit time types. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> [jstultz: Include errno-base.h to avoid build issue on some arches] Signed-off-by: John Stultz <john.stultz@linaro.org>
2016-03-02time: Add history to cross timestamp interface supporting slower devicesChristopher S. Hall
Another representative use case of time sync and the correlated clocksource (in addition to PTP noted above) is PTP synchronized audio. In a streaming application, as an example, samples will be sent and/or received by multiple devices with a presentation time that is in terms of the PTP master clock. Synchronizing the audio output on these devices requires correlating the audio clock with the PTP master clock. The more precise this correlation is, the better the audio quality (i.e. out of sync audio sounds bad). From an application standpoint, to correlate the PTP master clock with the audio device clock, the system clock is used as a intermediate timebase. The transforms such an application would perform are: System Clock <-> Audio clock System Clock <-> Network Device Clock [<-> PTP Master Clock] Modern Intel platforms can perform a more accurate cross timestamp in hardware (ART,audio device clock). The audio driver requires ART->system time transforms -- the same as required for the network driver. These platforms offload audio processing (including cross-timestamps) to a DSP which to ensure uninterrupted audio processing, communicates and response to the host only once every millsecond. As a result is takes up to a millisecond for the DSP to receive a request, the request is processed by the DSP, the audio output hardware is polled for completion, the result is copied into shared memory, and the host is notified. All of these operation occur on a millisecond cadence. This transaction requires about 2 ms, but under heavier workloads it may take up to 4 ms. Adding a history allows these slow devices the option of providing an ART value outside of the current interval. In this case, the callback provided is an accessor function for the previously obtained counter value. If get_system_device_crosststamp() receives a counter value previous to cycle_last, it consults the history provided as an argument in history_ref and interpolates the realtime and monotonic raw system time using the provided counter value. If there are any clock discontinuities, e.g. from calling settimeofday(), the monotonic raw time is interpolated in the usual way, but the realtime clock time is adjusted by scaling the monotonic raw adjustment. When an accessor function is used a history argument *must* be provided. The history is initialized using ktime_get_snapshot() and must be called before the counter values are read. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: kevin.b.stanton@intel.com Cc: kevin.j.clarke@intel.com Cc: hpa@zytor.com Cc: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com> [jstultz: Fixed up cycles_t/cycle_t type confusion] Signed-off-by: John Stultz <john.stultz@linaro.org>
2016-03-02time: Add driver cross timestamp interface for higher precision time ↵Christopher S. Hall
synchronization ACKNOWLEDGMENT: cross timestamp code was developed by Thomas Gleixner <tglx@linutronix.de>. It has changed considerably and any mistakes are mine. The precision with which events on multiple networked systems can be synchronized using, as an example, PTP (IEEE 1588, 802.1AS) is limited by the precision of the cross timestamps between the system clock and the device (timestamp) clock. Precision here is the degree of simultaneity when capturing the cross timestamp. Currently the PTP cross timestamp is captured in software using the PTP device driver ioctl PTP_SYS_OFFSET. Reads of the device clock are interleaved with reads of the realtime clock. At best, the precision of this cross timestamp is on the order of several microseconds due to software latencies. Sub-microsecond precision is required for industrial control and some media applications. To achieve this level of precision hardware supported cross timestamping is needed. The function get_device_system_crosstimestamp() allows device drivers to return a cross timestamp with system time properly scaled to nanoseconds. The realtime value is needed to discipline that clock using PTP and the monotonic raw value is used for applications that don't require a "real" time, but need an unadjusted clock time. The get_device_system_crosstimestamp() code calls back into the driver to ensure that the system counter is within the current timekeeping update interval. Modern Intel hardware provides an Always Running Timer (ART) which is exactly related to TSC through a known frequency ratio. The ART is routed to devices on the system and is used to precisely and simultaneously capture the device clock with the ART. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: kevin.b.stanton@intel.com Cc: kevin.j.clarke@intel.com Cc: hpa@zytor.com Cc: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com> [jstultz: Reworked to remove extra structures and simplify calling] Signed-off-by: John Stultz <john.stultz@linaro.org>
2016-03-02time: Add timekeeping snapshot code capturing system time and counterChristopher S. Hall
In the current timekeeping code there isn't any interface to atomically capture the current relationship between the system counter and system time. ktime_get_snapshot() returns this triple (counter, monotonic raw, realtime) in the system_time_snapshot struct. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: kevin.b.stanton@intel.com Cc: kevin.j.clarke@intel.com Cc: hpa@zytor.com Cc: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com> [jstultz: Moved structure definitions around to clean things up, fixed cycles_t/cycle_t confusion.] Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-10-01ntp/pps: replace getnstime_raw_and_real with 64-bit versionArnd Bergmann
There is exactly one caller of getnstime_raw_and_real in the kernel, which is the pps_get_ts function. This changes the caller and the implementation to work on timespec64 types rather than timespec, to avoid the time_t overflow on 32-bit architectures. For consistency with the other new functions (ktime_get_seconds, ktime_get_real_*, ...), I'm renaming the function to ktime_get_raw_and_real_ts64. We still need to convert from the internal 64-bit type to 32 bit types in the caller, but this conversion is now pushed out from getnstime_raw_and_real to pps_get_ts. A follow-up patch changes the remaining pps code to completely avoid the conversion. Acked-by: Richard Cochran <richardcochran@gmail.com> Acked-by: David S. Miller <davem@davemloft.net> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-08-20Merge branch 'fortglx/4.3/time' of ↵Thomas Gleixner
https://git.linaro.org/people/john.stultz/linux into timers/core - A handful or y2038 related items - A walltime to monotonic limit - Small fixes for timespec_trunc() and timer_list output
2015-08-17time: Introduce current_kernel_time64()Baolin Wang
The current_kernel_time() is not year 2038 safe on 32bit systems since it returns a timespec value. Introduce current_kernel_time64() which returns a timespec64 value. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-07-09time: Get rid of do_posix_clock_monotonic_gettimeThomas Gleixner
All users gone. Remove it before we get another one. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-05-22time: Remove read_boot_clock()Xunlei Pang
Now that we have a read_boot_clock64() function available on every architecture, and converted all the users to it, it's time to remove the (now unused) read_boot_clock() completely from the kernel. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> [jstultz: Minor commit message tweak suggested by Ingo] Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-05-22timekeeping: Provide new API to get the current time resolutionHarald Geyer
This patch series introduces a new function u32 ktime_get_resolution_ns(void) which allows to clean up some driver code. In particular the IIO subsystem has a function to provide timestamps for events but no means to get their resolution. So currently the dht11 driver tries to guess the resolution in a rather messy and convoluted way. We can do much better with the new code. This API is not designed to be exposed to user space. This has been tested on i386, sunxi and mxs. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Harald Geyer <harald@ccbib.org> [jstultz: Tweaked to make it build after upstream changes] Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-04-03time, drivers/rtc: Don't bother with rtc_resume() for the nonstop clocksourceXunlei Pang
If a system does not provide a persistent_clock(), the time will be updated on resume by rtc_resume(). With the addition of the non-stop clocksources for suspend timing, those systems set the time on resume in timekeeping_resume(), but may not provide a valid persistent_clock(). This results in the rtc_resume() logic thinking no one has set the time and it then will over-write the suspend time again, which is not necessary and only increases clock error. So, fix this for rtc_resume(). This patch also improves the name of persistent_clock_exist to make it more grammatical. Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1427945681-29972-19-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-03time: Add y2038 safe update_persistent_clock64()Xunlei Pang
As part of addressing in-kernel y2038 issues, this patch adds update_persistent_clock64() and replaces all the call sites of update_persistent_clock() with this function. This is a __weak implementation, which simply calls the existing y2038 unsafe update_persistent_clock(). This allows architecture specific implementations to be converted independently, and eventually y2038-unsafe update_persistent_clock() can be removed after all its architecture specific implementations have been converted to update_persistent_clock64(). Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1427945681-29972-4-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-03time: Add y2038 safe read_persistent_clock64()Xunlei Pang
As part of addressing in-kernel y2038 issues, this patch adds read_persistent_clock64() and replaces all the call sites of read_persistent_clock() with this function. This is a __weak implementation, which simply calls the existing y2038 unsafe read_persistent_clock(). This allows architecture specific implementations to be converted independently, and eventually the y2038 unsafe read_persistent_clock() can be removed after all its architecture specific implementations have been converted to read_persistent_clock64(). Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1427945681-29972-3-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-03time: Add y2038 safe read_boot_clock64()Xunlei Pang
As part of addressing in-kernel y2038 issues, this patch adds read_boot_clock64() and replaces all the call sites of read_boot_clock() with this function. This is a __weak implementation, which simply calls the existing y2038 unsafe read_boot_clock(). This allows architecture specific implementations to be converted independently, and eventually the y2038 unsafe read_boot_clock() can be removed after all its architecture specific implementations have been converted to read_boot_clock64(). Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1427945681-29972-2-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-27time: Add ktime_get_tai_ns()Peter Zijlstra
Because it was the only clock for which we didn't have a _ns() accessor yet. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-27time: Introduce tk_fast_rawPeter Zijlstra
Add the NMI safe CLOCK_MONOTONIC_RAW accessor.. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20150319093400.562746929@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-01-23time: Expose get_monotonic_boottime64 for in-kernel useJohn Stultz
As part of the 2038 conversion process, add a get_monotonic_boottime64 accessor so we can depracate get_monotonic_boottime. Cc: pang.xunlei <pang.xunlei@linaro.org> Cc: Arnd Bergmann <arnd.bergmann@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-01-23time: Expose getboottime64 for in-kernel usesJohn Stultz
Adds a timespec64 based getboottime64() implementation that can be used as we convert internal users of getboottime away from using timespecs. Cc: pang.xunlei <pang.xunlei@linaro.org> Cc: Arnd Bergmann <arnd.bergmann@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-12-10Merge branch 'timers-2038-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull more 2038 timer work from Thomas Gleixner: "Two more patches for the ongoing 2038 work: - New accessors to clock MONOTONIC and REALTIME seconds This is a seperate branch as Arnd has follow up work depending on this" * 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timekeeping: Provide y2038 safe accessor to the seconds portion of CLOCK_REALTIME timekeeping: Provide fast accessor to the seconds part of CLOCK_MONOTONIC
2014-11-21time: Remove timekeeping_inject_sleeptime()John Stultz
Since all users have been converted to using the 64bit timekeeping_inject_sleeptime64(), remove the old y2038 problematic timekeeping_inject_sleeptime(). Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-11-21time: Expose get_monotonic_coarse64() for in-kernel usesJohn Stultz
Adds a timespec64 based get_monotonic_coarse64() implementation that can be used as we convert internal users of get_monotonic_coarse away from using timespecs. Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-11-21time: Expose getrawmonotonic64 for in-kernel usesJohn Stultz
Adds a timespec64 based getrawmonotonic64() implementation that can be used as we convert internal users of getrawmonotonic away from using timespecs. Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-11-21time: Provide y2038 safe timekeeping_inject_sleeptime() replacementpang.xunlei
As part of addressing "y2038 problem" for in-kernel uses, this patch adds timekeeping_inject_sleeptime64() using timespec64. After this patch, timekeeping_inject_sleeptime() is deprecated and all its call sites will be fixed using the new interface, after that it can be removed. NOTE: timekeeping_inject_sleeptime() is safe actually, but we want to eliminate timespec eventually, so comes this patch. Signed-off-by: pang.xunlei <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-11-21time: Provide y2038 safe do_settimeofday() replacementpang.xunlei
The kernel uses 32-bit signed value(time_t) for seconds elapsed 1970-01-01:00:00:00, thus it will overflow at 2038-01-19 03:14:08 on 32-bit systems. This is widely known as the y2038 problem. As part of addressing "y2038 problem" for in-kernel uses, this patch adds safe do_settimeofday64() using timespec64. After this patch, do_settimeofday() is deprecated and all its call sites will be fixed using do_settimeofday64(), after that it can be removed. Signed-off-by: pang.xunlei <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-10-29timekeeping: Provide y2038 safe accessor to the seconds portion of ↵Heena Sirwani
CLOCK_REALTIME ktime_get_real_seconds() is the replacement function for get_seconds() returning the seconds portion of CLOCK_REALTIME in a time64_t. For 64bit the function is equivivalent to get_seconds(), but for 32bit it protects the readout with the timekeeper sequence count. This is required because 32-bit machines cannot access 64-bit tk->xtime_sec variable atomically. [tglx: Massaged changelog and added docbook comment ] Signed-off-by: Heena Sirwani <heenasirwani@gmail.com> Reviewed-by: Arnd Bergman <arnd@arndb.de> Cc: John Stultz <john.stultz@linaro.org> Cc: opw-kernel@googlegroups.com Link: http://lkml.kernel.org/r/7adcfaa8962b8ad58785d9a2456c3f77d93c0ffb.1414578445.git.heenasirwani@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-10-29timekeeping: Provide fast accessor to the seconds part of CLOCK_MONOTONICHeena Sirwani
This is the counterpart to get_seconds() based on CLOCK_MONOTONIC. The use case for this interface are kernel internal coarse grained timestamps which do neither require the nanoseconds fraction of current time nor the CLOCK_REALTIME properties. Such timestamps can currently only retrieved by calling ktime_get_ts64() and using the tv_sec field of the returned timespec64. That's inefficient as it involves the read of the clocksource, math operations and must be protected by the timekeeper sequence counter. To avoid the sequence counter protection we restrict the return value to unsigned 32bit on 32bit machines. This covers ~136 years of uptime and therefor an overflow is not expected to hit anytime soon. To avoid math in the function we calculate the current seconds portion of CLOCK_MONOTONIC when the timekeeper gets updated in tk_update_ktime_data() similar to the CLOCK_REALTIME counterpart xtime_sec. [ tglx: Massaged changelog, simplified and commented the update function, added docbook comment ] Signed-off-by: Heena Sirwani <heenasirwani@gmail.com> Reviewed-by: Arnd Bergman <arnd@arndb.de> Cc: John Stultz <john.stultz@linaro.org> Cc: opw-kernel@googlegroups.com Link: http://lkml.kernel.org/r/da0b63f4bdf3478909f92becb35861197da3a905.1414578445.git.heenasirwani@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-07-23timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONICThomas Gleixner
Tracers want a correlated time between the kernel instrumentation and user space. We really do not want to export sched_clock() to user space, so we need to provide something sensible for this. Using separate data structures with an non blocking sequence count based update mechanism allows us to do that. The data structure required for the readout has a sequence counter and two copies of the timekeeping data. On the update side: smp_wmb(); tkf->seq++; smp_wmb(); update(tkf->base[0], tk); smp_wmb(); tkf->seq++; smp_wmb(); update(tkf->base[1], tk); On the reader side: do { seq = tkf->seq; smp_rmb(); idx = seq & 0x01; now = now(tkf->base[idx]); smp_rmb(); } while (seq != tkf->seq) So if a NMI hits the update of base[0] it will use base[1] which is still consistent, but this timestamp is not guaranteed to be monotonic across an update. The timestamp is calculated by: now = base_mono + clock_delta * slope So if the update lowers the slope, readers who are forced to the not yet updated second array are still using the old steeper slope. tmono ^ | o n | o n | u | o |o |12345678---> reader order o = old slope u = update n = new slope So reader 6 will observe time going backwards versus reader 5. While other CPUs are likely to be able observe that, the only way for a CPU local observation is when an NMI hits in the middle of the update. Timestamps taken from that NMI context might be ahead of the following timestamps. Callers need to be aware of that and deal with it. V2: Got rid of clock monotonic raw and reorganized the data structures. Folded in the barrier fix from Mathieu. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_get_raw()Thomas Gleixner
Provide a ktime_t based interface for raw monotonic time. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Simplify timekeeping_clocktai()Thomas Gleixner
timekeeping_clocktai() is not used in fast pathes, so the extra timespec conversion is not problematic. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_get_boottime() for get_monotonic_boottime()Thomas Gleixner
get_monotonic_boottime() is not used in fast pathes, so the extra timespec conversion is not problematic. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Remove monotonic_to_bootbasedThomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_get[*]_ns() helpersThomas Gleixner
A lot of code converts either timespecs or ktime_t to nanoseconds. Provide helper functions. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Remove ktime_get_monotonic_offset()Thomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_mono_to_any()Thomas Gleixner
ktime based conversion function to map a monotonic time stamp to a different CLOCK. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_t based data for ktime_get_clocktai()Thomas Gleixner
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping; Use ktime_t based data for ktime_get_boottime()Thomas Gleixner
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_t based data for ktime_get_real()Thomas Gleixner
Speed up the readout. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_get_with_offset()Thomas Gleixner
Provide a helper function which lets us implement ktime_t based interfaces for real, boot and tai clocks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide timespec64 based interfacesThomas Gleixner
To convert callers of the core code to timespec64 we need to provide the proper interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23time: Consolidate the time accessor prototypesThomas Gleixner
Right now we have time related prototypes in 3 different header files. Move it to a single timekeeping header file and move the core internal stuff into a core private header. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>