printk wants to store various timestamps (MONOTONIC, REALTIME, BOOTTIME) to
make correlation of dmesg from several systems easier.
Provide an interface to retrieve all three timestamps in one go.
There are some caveats:
1) Boot time and late sleep time injection
Boot time is a racy access on 32bit systems if the sleep time injection
happens late during resume and not in timekeeping_resume(). That could be
avoided by expanding struct tk_read_base with boot offset for 32bit and
adding more overhead to the update. As this is a hard to observe once per
resume event which can be filtered with reasonable effort using the
accurate mono/real timestamps, it's probably not worth the trouble.
Aside of that it might be possible on 32 and 64 bit to observe the
following when the sleep time injection happens late:
CPU 0 CPU 1
timekeeping_resume()
ktime_get_fast_timestamps()
mono, real = __ktime_get_real_fast()
inject_sleep_time()
update boot offset
boot = mono + bootoffset;
That means that boot time already has the sleep time adjustment, but
real time does not. On the next readout both are in sync again.
Preventing this for 64bit is not really feasible without destroying the
careful cache layout of the timekeeper because the sequence count and
struct tk_read_base would then need two cache lines instead of one.
2) Suspend/resume timestamps
Access to the time keeper clock source is disabled accross the innermost
steps of suspend/resume. The accessors still work, but the timestamps
are frozen until time keeping is resumed which happens very early.
For regular suspend/resume there is no observable difference vs. sched
clock, but it might affect some of the nasty low level debug printks.
OTOH, access to sched clock is not guaranteed accross suspend/resume on
all systems either so it depends on the hardware in use.
If that turns out to be a real problem then this could be mitigated by
using sched clock in a similar way as during early boot. But it's not as
trivial as on early boot because it needs some careful protection
against the clock monotonic timestamp jumping backwards on resume.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20200814115512.159981360@linutronix.de
Make kernel doc comments actually work and fix the syncronized typo. [ tglx: Added the missing /** and fixed up formatting ] Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200609081726.5657-1-kurt@linutronix.de
Somewhere in all the patchsets before, this cleanup got lost. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Link: https://lkml.kernel.org/r/20190624091539.13512-1-Jason@zx2c4.com
This further unifies the accessors for the fast and coarse functions, so that the same types of functions are available for each. There was also a bit of confusion with the documentation, which prior advertised a function that has never existed. Finally, the vanilla ktime_get_coarse() was omitted from the API originally, so this fills this oversight. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Link: https://lkml.kernel.org/r/20190621203249.3909-3-Jason@zx2c4.com
This makes boot uniformly boottime and tai uniformly clocktai, to address the remaining oversights. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Link: https://lkml.kernel.org/r/20190621203249.3909-2-Jason@zx2c4.com
There are no more remaining users of these deprecated wrappers, so let's remove them before new users have a chance to make it in. See Documentation/core-api/timekeeping.rst for replacements when porting old drivers that contain calls to this function. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: John Stultz <john.stultz@linaro.org>
Pull timekeeping updates from Thomas Gleixner:
"The timers and timekeeping departement provides:
- Another large y2038 update with further preparations for providing
the y2038 safe timespecs closer to the syscalls.
- An overhaul of the SHCMT clocksource driver
- SPDX license identifier updates
- Small cleanups and fixes all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
tick/sched : Remove redundant cpu_online() check
clocksource/drivers/dw_apb: Add reset control
clocksource: Remove obsolete CLOCKSOURCE_OF_DECLARE
clocksource/drivers: Unify the names to timer-* format
clocksource/drivers/sh_cmt: Add R-Car gen3 support
dt-bindings: timer: renesas: cmt: document R-Car gen3 support
clocksource/drivers/sh_cmt: Properly line-wrap sh_cmt_of_table[] initializer
clocksource/drivers/sh_cmt: Fix clocksource width for 32-bit machines
clocksource/drivers/sh_cmt: Fixup for 64-bit machines
clocksource/drivers/sh_tmu: Convert to SPDX identifiers
clocksource/drivers/sh_mtu2: Convert to SPDX identifiers
clocksource/drivers/sh_cmt: Convert to SPDX identifiers
clocksource/drivers/renesas-ostm: Convert to SPDX identifiers
clocksource: Convert to using %pOFn instead of device_node.name
tick/broadcast: Remove redundant check
RISC-V: Request newstat syscalls
y2038: signal: Change rt_sigtimedwait to use __kernel_timespec
y2038: socket: Change recvmmsg to use __kernel_timespec
y2038: sched: Change sched_rr_get_interval to use __kernel_timespec
y2038: utimes: Rework #ifdef guards for compat syscalls
...
It is read_persistent_wall_and_boot_offset() and not
read_persistent_clock_and_boot_offset()
Fixes: 3eca993740b8eb40f51 ("timekeeping: Replace read_boot_clock64() with read_persistent_wall_and_boot_offset()")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Link: https://lkml.kernel.org/r/20180903081533.34366-1-borntraeger@de.ibm.com
After many small patches, at least some of the deprecated interfaces have no remaining users any more and can be removed: current_kernel_time do_settimeofday get_monotonic_boottime get_monotonic_boottime64 get_monotonic_coarse get_monotonic_coarse64 getrawmonotonic64 ktime_get_real_ts timekeeping_clocktai timespec_trunc timespec_valid_strict time_to_tm For many of the remaining time functions, we are missing one or two patches that failed to make it into 4.19, they will be removed in the following merge window. The replacement functions for the removed interfaces are documented in Documentation/core-api/timekeeping.rst. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Pull documentation update from Jonathan Corbet: "This was a moderately busy cycle for docs, with the usual collection of small fixes and updates. We also have new ktime_get_*() docs from Arnd, some kernel-doc fixes, a new set of Italian translations (non so se vale la pena, ma non fa male - speriamo bene), and some extensive early memory-management documentation improvements from Mike Rapoport" * tag 'docs-4.19' of git://git.lwn.net/linux: (52 commits) Documentation: corrections to console/console.txt Documentation: add ioctl number entry for v4l2-subdev.h Remove gendered language from management style documentation scripts/kernel-doc: Escape all literal braces in regexes docs/mm: add description of boot time memory management docs/mm: memblock: add overview documentation docs/mm: memblock: add kernel-doc description for memblock types docs/mm: memblock: add kernel-doc comments for memblock_add[_node] docs/mm: memblock: update kernel-doc comments mm/memblock: add a name for memblock flags enumeration docs/mm: bootmem: add overview documentation docs/mm: bootmem: add kernel-doc description of 'struct bootmem_data' docs/mm: bootmem: fix kernel-doc warnings docs/mm: nobootmem: fixup kernel-doc comments mm/bootmem: drop duplicated kernel-doc comments Documentation: vm.txt: Adding 'nr_hugepages_mempolicy' parameter description. doc:it_IT: translation for kernel-hacking docs: Fix the reference labels in Locking.rst doc: tracing: Fix a typo of trace_stat mm: Introduce new type vm_fault_t ...