starfive-tech/linux.git/kernel/time, branch visionfive_v1_5.13

timers: Move clearing of base::timer_running under base:: Lock

2021-08-12T11:32:21+00:00

commit bb7262b295472eb6858b5c49893954794027cd84 upstream. syzbot reported KCSAN data races vs. timer_base::timer_running being set to NULL without holding base::lock in expire_timers(). This looks innocent and most reads are clearly not problematic, but Frederic identified an issue which is: int data = 0; void timer_func(struct timer_list *t) { data = 1; } CPU 0 CPU 1 ------------------------------ -------------------------- base = lock_timer_base(timer, &flags); raw_spin_unlock(&base->lock); if (base->running_timer != timer) call_timer_fn(timer, fn, baseclk); ret = detach_if_pending(timer, base, true); base->running_timer = NULL; raw_spin_unlock_irqrestore(&base->lock, flags); raw_spin_lock(&base->lock); x = data; If the timer has previously executed on CPU 1 and then CPU 0 can observe base->running_timer == NULL and returns, assuming the timer has completed, but it's not guaranteed on all architectures. The comment for del_timer_sync() makes that guarantee. Moving the assignment under base->lock prevents this. For non-RT kernel it's performance wise completely irrelevant whether the store happens before or after taking the lock. For an RT kernel moving the store under the lock requires an extra unlock/lock pair in the case that there is a waiter for the timer, but that's not the end of the world. Reported-by: syzbot+aa7c2385d46c5eba0b89@syzkaller.appspotmail.com Reported-by: syzbot+abea4558531bae1ba9fe@syzkaller.appspotmail.com Fixes: 030dcdd197d7 ("timers: Prepare support for PREEMPT_RT") Signed-off-by: Thomas Gleixner Tested-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/87lfea7gw8.fsf@nanos.tec.linutronix.de Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

posix-cpu-timers: Fix rearm racing against process tick

2021-07-28T12:37:39+00:00

commit 1a3402d93c73bf6bb4df6d7c2aac35abfc3c50e2 upstream. Since the process wide cputime counter is started locklessly from posix_cpu_timer_rearm(), it can be concurrently stopped by operations on other timers from the same thread group, such as in the following unlucky scenario: CPU 0 CPU 1 ----- ----- timer_settime(TIMER B) posix_cpu_timer_rearm(TIMER A) cpu_clock_sample_group() (pct->timers_active already true) handle_posix_cpu_timers() check_process_timers() stop_process_timers() pct->timers_active = false arm_timer(TIMER A) tick -> run_posix_cpu_timers() // sees !pct->timers_active, ignore // our TIMER A Fix this with simply locking process wide cputime counting start and timer arm in the same block. Acked-by: Peter Zijlstra (Intel) Signed-off-by: Frederic Weisbecker Fixes: 60f2ceaa8111 ("posix-cpu-timers: Remove unnecessary locking around cpu_clock_sample_group") Cc: stable@vger.kernel.org Cc: Oleg Nesterov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman

timers: Fix get_next_timer_interrupt() with no timers pending

2021-07-28T12:37:27+00:00

[ Upstream commit aebacb7f6ca1926918734faae14d1f0b6fae5cb7 ] 31cd0e119d50 ("timers: Recalculate next timer interrupt only when necessary") subtly altered get_next_timer_interrupt()'s behaviour. The function no longer consistently returns KTIME_MAX with no timers pending. In order to decide if there are any timers pending we check whether the next expiry will happen NEXT_TIMER_MAX_DELTA jiffies from now. Unfortunately, the next expiry time and the timer base clock are no longer updated in unison. The former changes upon certain timer operations (enqueue, expire, detach), whereas the latter keeps track of jiffies as they move forward. Ultimately breaking the logic above. A simplified example: - Upon entering get_next_timer_interrupt() with: jiffies = 1 base->clk = 0; base->next_expiry = NEXT_TIMER_MAX_DELTA; 'base->next_expiry == base->clk + NEXT_TIMER_MAX_DELTA', the function returns KTIME_MAX. - 'base->clk' is updated to the jiffies value. - The next time we enter get_next_timer_interrupt(), taking into account no timer operations happened: base->clk = 1; base->next_expiry = NEXT_TIMER_MAX_DELTA; 'base->next_expiry != base->clk + NEXT_TIMER_MAX_DELTA', the function returns a valid expire time, which is incorrect. This ultimately might unnecessarily rearm sched's timer on nohz_full setups, and add latency to the system[1]. So, introduce 'base->timers_pending'[2], update it every time 'base->next_expiry' changes, and use it in get_next_timer_interrupt(). [1] See tick_nohz_stop_tick(). [2] A quick pahole check on x86_64 and arm64 shows it doesn't make 'struct timer_base' any bigger. Fixes: 31cd0e119d50 ("timers: Recalculate next timer interrupt only when necessary") Signed-off-by: Nicolas Saenz Julienne Signed-off-by: Frederic Weisbecker Signed-off-by: Sasha Levin

clocksource: Check per-CPU clock synchronization when marked unstable

2021-07-14T15:06:36+00:00

[ Upstream commit 7560c02bdffb7c52d1457fa551b9e745d4b9e754 ] Some sorts of per-CPU clock sources have a history of going out of synchronization with each other. However, this problem has purportedy been solved in the past ten years. Except that it is all too possible that the problem has instead simply been made less likely, which might mean that some of the occasional "Marking clocksource 'tsc' as unstable" messages might be due to desynchronization. How would anyone know? Therefore apply CPU-to-CPU synchronization checking to newly unstable clocksource that are marked with the new CLOCK_SOURCE_VERIFY_PERCPU flag. Lists of desynchronized CPUs are printed, with the caveat that if it is the reporting CPU that is itself desynchronized, it will appear that all the other clocks are wrong. Just like in real life. Reported-by: Chris Mason Signed-off-by: Paul E. McKenney Signed-off-by: Thomas Gleixner Acked-by: Feng Tang Link: https://lore.kernel.org/r/20210527190124.440372-2-paulmck@kernel.org Signed-off-by: Sasha Levin

clocksource: Retry clock read if long delays detected

2021-07-14T15:06:36+00:00

[ Upstream commit db3a34e17433de2390eb80d436970edcebd0ca3e ] When the clocksource watchdog marks a clock as unstable, this might be due to that clock being unstable or it might be due to delays that happen to occur between the reads of the two clocks. Yes, interrupts are disabled across those two reads, but there are no shortage of things that can delay interrupts-disabled regions of code ranging from SMI handlers to vCPU preemption. It would be good to have some indication as to why the clock was marked unstable. Therefore, re-read the watchdog clock on either side of the read from the clock under test. If the watchdog clock shows an excessive time delta between its pair of reads, the reads are retried. The maximum number of retries is specified by a new kernel boot parameter clocksource.max_cswd_read_retries, which defaults to three, that is, up to four reads, one initial and up to three retries. If more than one retry was required, a message is printed on the console (the occasional single retry is expected behavior, especially in guest OSes). If the maximum number of retries is exceeded, the clock under test will be marked unstable. However, the probability of this happening due to various sorts of delays is quite small. In addition, the reason (clock-read delays) for the unstable marking will be apparent. Reported-by: Chris Mason Signed-off-by: Paul E. McKenney Signed-off-by: Thomas Gleixner Acked-by: Feng Tang Link: https://lore.kernel.org/r/20210527190124.440372-1-paulmck@kernel.org Signed-off-by: Sasha Levin

tick/nohz: Only check for RCU deferred wakeup on user/guest entry when needed

2021-05-31T08:14:49+00:00

Checking for and processing RCU-nocb deferred wakeup upon user/guest entry is only relevant when nohz_full runs on the local CPU, otherwise the periodic tick should take care of it. Make sure we don't needlessly pollute these fast-paths as a -3% performance regression on a will-it-scale.per_process_ops has been reported so far. Fixes: 47b8ff194c1f (entry: Explicitly flush pending rcuog wakeup before last rescheduling point) Fixes: 4ae7dc97f726 (entry/kvm: Explicitly flush pending rcuog wakeup before last rescheduling point) Reported-by: kernel test robot Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Paul E. McKenney Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210527113441.465489-1-frederic@kernel.org

alarmtimer: Check RTC features instead of ops

2021-05-11T19:28:04+00:00

RTC drivers used to leave .set_alarm() NULL in order to signal the RTC device doesn't support alarms. The drivers are now clearing the RTC_FEATURE_ALARM bit for that purpose in order to keep the rtc_class_ops structure const. So now, .set_alarm() is set unconditionally and this possibly causes the alarmtimer code to select an RTC device that doesn't support alarms. Test RTC_FEATURE_ALARM instead of relying on ops->set_alarm to determine whether alarms are available. Fixes: 7ae41220ef58 ("rtc: introduce features bitfield") Signed-off-by: Alexandre Belloni Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210511014516.563031-1-alexandre.belloni@bootlin.com

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2021-05-01T17:14:08+00:00

Pull kvm updates from Paolo Bonzini: "This is a large update by KVM standards, including AMD PSP (Platform Security Processor, aka "AMD Secure Technology") and ARM CoreSight (debug and trace) changes. ARM: - CoreSight: Add support for ETE and TRBE - Stage-2 isolation for the host kernel when running in protected mode - Guest SVE support when running in nVHE mode - Force W^X hypervisor mappings in nVHE mode - ITS save/restore for guests using direct injection with GICv4.1 - nVHE panics now produce readable backtraces - Guest support for PTP using the ptp_kvm driver - Performance improvements in the S2 fault handler x86: - AMD PSP driver changes - Optimizations and cleanup of nested SVM code - AMD: Support for virtual SPEC_CTRL - Optimizations of the new MMU code: fast invalidation, zap under read lock, enable/disably dirty page logging under read lock - /dev/kvm API for AMD SEV live migration (guest API coming soon) - support SEV virtual machines sharing the same encryption context - support SGX in virtual machines - add a few more statistics - improved directed yield heuristics - Lots and lots of cleanups Generic: - Rework of MMU notifier interface, simplifying and optimizing the architecture-specific code - a handful of "Get rid of oprofile leftovers" patches - Some selftests improvements" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (379 commits) KVM: selftests: Speed up set_memory_region_test selftests: kvm: Fix the check of return value KVM: x86: Take advantage of kvm_arch_dy_has_pending_interrupt() KVM: SVM: Skip SEV cache flush if no ASIDs have been used KVM: SVM: Remove an unnecessary prototype declaration of sev_flush_asids() KVM: SVM: Drop redundant svm_sev_enabled() helper KVM: SVM: Move SEV VMCB tracking allocation to sev.c KVM: SVM: Explicitly check max SEV ASID during sev_hardware_setup() KVM: SVM: Unconditionally invoke sev_hardware_teardown() KVM: SVM: Enable SEV/SEV-ES functionality by default (when supported) KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD_SEV=y KVM: SVM: Append "_enabled" to module-scoped SEV/SEV-ES control variables KVM: SEV: Mask CPUID[0x8000001F].eax according to supported features KVM: SVM: Move SEV module params/variables to sev.c KVM: SVM: Disable SEV/SEV-ES if NPT is disabled KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails KVM: SVM: Zero out the VMCB array used to track SEV ASID association x86/sev: Drop redundant and potentially misleading 'sev_enabled' KVM: x86: Move reverse CPUID helpers to separate header file KVM: x86: Rename GPR accessors to make mode-aware variants the defaults ...

Merge tag 'pm-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2021-04-26T22:10:25+00:00

Pull power management updates from Rafael Wysocki: "These add some new hardware support (for example, IceLake-D idle states in intel_idle), fix some issues (for example, the handling of negative "sleep length" values in cpuidle governors), add new functionality to the existing drivers (for example, scale-invariance support in the ACPI CPPC cpufreq driver) and clean up code all over. Specifics: - Add idle states table for IceLake-D to the intel_idle driver and update IceLake-X C6 data in it (Artem Bityutskiy). - Fix the C7 idle state on Tegra114 in the tegra cpuidle driver and drop the unused do_idle() firmware call from it (Dmitry Osipenko). - Fix cpuidle-qcom-spm Kconfig entry (He Ying). - Fix handling of possible negative tick_nohz_get_next_hrtimer() return values of in cpuidle governors (Rafael Wysocki). - Add support for frequency-invariance to the ACPI CPPC cpufreq driver and update the frequency-invariance engine (FIE) to use it as needed (Viresh Kumar). - Simplify the default delay_us setting in the ACPI CPPC cpufreq driver (Tom Saeger). - Clean up frequency-related computations in the intel_pstate cpufreq driver (Rafael Wysocki). - Fix TBG parent setting for load levels in the armada-37xx cpufreq driver and drop the CPU PM clock .set_parent method for armada-37xx (Marek Behún). - Fix multiple issues in the armada-37xx cpufreq driver (Pali Rohár). - Fix handling of dev_pm_opp_of_cpumask_add_table() return values in cpufreq-dt to take the -EPROBE_DEFER one into acconut as appropriate (Quanyang Wang). - Fix format string in ia64-acpi-cpufreq (Sergei Trofimovich). - Drop the unused for_each_policy() macro from cpufreq (Shaokun Zhang). - Simplify computations in the schedutil cpufreq governor to avoid unnecessary overhead (Yue Hu). - Fix typos in the s5pv210 cpufreq driver (Bhaskar Chowdhury). - Fix cpufreq documentation links in Kconfig (Alexander Monakov). - Fix PCI device power state handling in pci_enable_device_flags() to avoid issuse in some cases when the device depends on an ACPI power resource (Rafael Wysocki). - Add missing documentation of pm_runtime_resume_and_get() (Alan Stern). - Add missing static inline stub for pm_runtime_has_no_callbacks() to pm_runtime.h and drop the unused try_to_freeze_nowarn() definition (YueHaibing). - Drop duplicate struct device declaration from pm.h and fix a structure type declaration in intel_rapl.h (Wan Jiabing). - Use dev_set_name() instead of an open-coded equivalent of it in the wakeup sources code and drop a redundant local variable initialization from it (Andy Shevchenko, Colin Ian King). - Use crc32 instead of md5 for e820 memory map integrity check during resume from hibernation on x86 (Chris von Recklinghausen). - Fix typos in comments in the system-wide and hibernation support code (Lu Jialin). - Modify the generic power domains (genpd) code to avoid resuming devices in the "prepare" phase of system-wide suspend and hibernation (Ulf Hansson). - Add Hygon Fam18h RAPL support to the intel_rapl power capping driver (Pu Wen). - Add MAINTAINERS entry for the dynamic thermal power management (DTPM) code (Daniel Lezcano). - Add devm variants of operating performance points (OPP) API functions and switch over some users of the OPP framework to the new resource-managed API (Yangtao Li and Dmitry Osipenko). - Update devfreq core: * Register devfreq devices as cooling devices on demand (Daniel Lezcano). * Add missing unlock opeation in devfreq_add_device() (Lukasz Luba). * Use the next frequency as resume_freq instead of the previous frequency when using the opp-suspend property (Dong Aisheng). * Check get_dev_status in devfreq_update_stats() (Dong Aisheng). * Fix set_freq path for the userspace governor in Kconfig (Dong Aisheng). * Remove invalid description of get_target_freq() (Dong Aisheng). - Update devfreq drivers: * imx8m-ddrc: Remove imx8m_ddrc_get_dev_status() and unneeded of_match_ptr() (Dong Aisheng, Fabio Estevam). * rk3399_dmc: dt-bindings: Add rockchip,pmu phandle and drop references to undefined symbols (Enric Balletbo i Serra, Gaël PORTAY). * rk3399_dmc: Use dev_err_probe() to simplify the code (Krzysztof Kozlowski). * imx-bus: Remove unneeded of_match_ptr() (Fabio Estevam). - Fix kernel-doc warnings in three places (Pierre-Louis Bossart). - Fix typo in the pm-graph utility code (Ricardo Ribalda)" * tag 'pm-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (74 commits) PM: wakeup: remove redundant assignment to variable retval PM: hibernate: x86: Use crc32 instead of md5 for hibernation e820 integrity check cpufreq: Kconfig: fix documentation links PM: wakeup: use dev_set_name() directly PM: runtime: Add documentation for pm_runtime_resume_and_get() cpufreq: intel_pstate: Simplify intel_pstate_update_perf_limits() cpufreq: armada-37xx: Fix module unloading cpufreq: armada-37xx: Remove cur_frequency variable cpufreq: armada-37xx: Fix determining base CPU frequency cpufreq: armada-37xx: Fix driver cleanup when registration failed clk: mvebu: armada-37xx-periph: Fix workaround for switching from L1 to L0 clk: mvebu: armada-37xx-periph: Fix switching CPU freq from 250 Mhz to 1 GHz cpufreq: armada-37xx: Fix the AVS value for load L1 clk: mvebu: armada-37xx-periph: remove .set_parent method for CPU PM clock cpufreq: armada-37xx: Fix setting TBG parent for load levels cpuidle: Fix ARM_QCOM_SPM_CPUIDLE configuration cpuidle: tegra: Remove do_idle firmware call cpuidle: tegra: Fix C7 idling state on Tegra114 PM: sleep: fix typos in comments cpufreq: Remove unused for_each_policy macro ...

Merge tag 'timers-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-04-26T16:54:03+00:00

Pull timer updates from Thomas Gleixner: "The time and timers updates contain: Core changes: - Allow runtime power management when the clocksource is changed. - A correctness fix for clock_adjtime32() so that the return value on success is not overwritten by the result of the copy to user. - Allow late installment of broadcast clockevent devices which was broken because nothing switched them over to oneshot mode. This went unnoticed so far because clockevent devices used to be built in, but now people started to make them modular. - Debugfs related simplifications - Small cleanups and improvements here and there Driver changes: - The usual set of device tree binding updates for a wide range of drivers/devices. - The usual updates and improvements for drivers all over the place but nothing outstanding. - No new clocksource/event drivers. They'll come back next time" * tag 'timers-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) posix-timers: Preserve return value in clock_adjtime32() tick/broadcast: Allow late registered device to enter oneshot mode tick: Use tick_check_replacement() instead of open coding it time/timecounter: Mark 1st argument of timecounter_cyc2time() as const dt-bindings: timer: nuvoton,npcm7xx: Add wpcm450-timer clocksource/drivers/arm_arch_timer: Add __ro_after_init and __init clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940 clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue clocksource/drivers/dw_apb_timer_of: Add handling for potential memory leak clocksource/drivers/npcm: Add support for WPCM450 clocksource/drivers/sh_cmt: Don't use CMTOUT_IE with R-Car Gen2/3 clocksource/drivers/pistachio: Fix trivial typo clocksource/drivers/ingenic_ost: Fix return value check in ingenic_ost_probe() clocksource/drivers/timer-ti-dm: Add missing set_state_oneshot_stopped clocksource/drivers/timer-ti-dm: Fix posted mode status check order dt-bindings: timer: renesas,cmt: Document R8A77961 dt-bindings: timer: renesas,cmt: Add r8a779a0 CMT support clocksource/drivers/ingenic-ost: Add support for the JZ4760B clocksource/drivers/ingenic: Add support for the JZ4760 dt-bindings: timer: ingenic: Add compatible strings for JZ4760(B) ...