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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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fb7d4948c4
Now that all ARCH_WANTS_NO_INSTR architectures (arm64, loongarch, s390, x86) provide sched_clock_noinstr(), use this to provide local_clock_noinstr(). This local_clock_noinstr() will be safe to use from noinstr code with the assumption that any such noinstr code is non-preemptible (it had better be, entry code will have IRQs disabled while __cpuidle must have preemption disabled). Specifically, preempt_enable_notrace(), a common part of many a sched_clock() implementation calls out to schedule() -- even though, per the above, it will never trigger -- which frustrates noinstr validation. vmlinux.o: warning: objtool: local_clock+0xb5: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Michael Kelley <mikelley@microsoft.com> # Hyper-V Link: https://lore.kernel.org/r/20230519102715.978624636@infradead.org
114 lines
2.7 KiB
C
114 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SCHED_CLOCK_H
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#define _LINUX_SCHED_CLOCK_H
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#include <linux/smp.h>
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/*
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* Do not use outside of architecture code which knows its limitations.
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*
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* sched_clock() has no promise of monotonicity or bounded drift between
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* CPUs, use (which you should not) requires disabling IRQs.
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*
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* Please use one of the three interfaces below.
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*/
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extern u64 sched_clock(void);
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#if defined(CONFIG_ARCH_WANTS_NO_INSTR) || defined(CONFIG_GENERIC_SCHED_CLOCK)
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extern u64 sched_clock_noinstr(void);
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#else
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static __always_inline u64 sched_clock_noinstr(void)
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{
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return sched_clock();
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}
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#endif
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/*
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* See the comment in kernel/sched/clock.c
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*/
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extern u64 running_clock(void);
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extern u64 sched_clock_cpu(int cpu);
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extern void sched_clock_init(void);
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#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
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static inline void sched_clock_tick(void)
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{
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}
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static inline void clear_sched_clock_stable(void)
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{
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}
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static inline void sched_clock_idle_sleep_event(void)
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{
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}
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static inline void sched_clock_idle_wakeup_event(void)
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{
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}
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static inline u64 cpu_clock(int cpu)
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{
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return sched_clock();
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}
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static __always_inline u64 local_clock_noinstr(void)
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{
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return sched_clock_noinstr();
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}
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static __always_inline u64 local_clock(void)
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{
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return sched_clock();
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}
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#else
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extern int sched_clock_stable(void);
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extern void clear_sched_clock_stable(void);
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/*
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* When sched_clock_stable(), __sched_clock_offset provides the offset
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* between local_clock() and sched_clock().
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*/
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extern u64 __sched_clock_offset;
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extern void sched_clock_tick(void);
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extern void sched_clock_tick_stable(void);
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extern void sched_clock_idle_sleep_event(void);
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extern void sched_clock_idle_wakeup_event(void);
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/*
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* As outlined in clock.c, provides a fast, high resolution, nanosecond
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* time source that is monotonic per cpu argument and has bounded drift
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* between cpus.
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*
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* ######################### BIG FAT WARNING ##########################
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* # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can #
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* # go backwards !! #
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* ####################################################################
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*/
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static inline u64 cpu_clock(int cpu)
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{
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return sched_clock_cpu(cpu);
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}
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extern u64 local_clock_noinstr(void);
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extern u64 local_clock(void);
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#endif
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#ifdef CONFIG_IRQ_TIME_ACCOUNTING
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/*
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* An i/f to runtime opt-in for irq time accounting based off of sched_clock.
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* The reason for this explicit opt-in is not to have perf penalty with
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* slow sched_clocks.
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*/
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extern void enable_sched_clock_irqtime(void);
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extern void disable_sched_clock_irqtime(void);
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#else
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static inline void enable_sched_clock_irqtime(void) {}
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static inline void disable_sched_clock_irqtime(void) {}
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#endif
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#endif /* _LINUX_SCHED_CLOCK_H */
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