// SPDX-License-Identifier: GPL-2.0-only /* * linux/arch/ia64/kernel/time.c * * Copyright (C) 1998-2003 Hewlett-Packard Co * Stephane Eranian <eranian@hpl.hp.com> * David Mosberger <davidm@hpl.hp.com> * Copyright (C) 1999 Don Dugger <don.dugger@intel.com> * Copyright (C) 1999-2000 VA Linux Systems * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com> */ #include <linux/cpu.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/profile.h> #include <linux/sched.h> #include <linux/time.h> #include <linux/nmi.h> #include <linux/interrupt.h> #include <linux/efi.h> #include <linux/timex.h> #include <linux/timekeeper_internal.h> #include <linux/platform_device.h> #include <linux/sched/cputime.h> #include <asm/delay.h> #include <asm/efi.h> #include <asm/hw_irq.h> #include <asm/ptrace.h> #include <asm/sal.h> #include <asm/sections.h> #include "fsyscall_gtod_data.h" #include "irq.h" static u64 itc_get_cycles(struct clocksource *cs); struct fsyscall_gtod_data_t fsyscall_gtod_data; struct itc_jitter_data_t itc_jitter_data; volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */ #ifdef CONFIG_IA64_DEBUG_IRQ unsigned long last_cli_ip; EXPORT_SYMBOL(last_cli_ip); #endif static struct clocksource clocksource_itc = { .name = "itc", .rating = 350, .read = itc_get_cycles, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; static struct clocksource *itc_clocksource; #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE #include <linux/kernel_stat.h> extern u64 cycle_to_nsec(u64 cyc); void vtime_flush(struct task_struct *tsk) { struct thread_info *ti = task_thread_info(tsk); u64 delta; if (ti->utime) account_user_time(tsk, cycle_to_nsec(ti->utime)); if (ti->gtime) account_guest_time(tsk, cycle_to_nsec(ti->gtime)); if (ti->idle_time) account_idle_time(cycle_to_nsec(ti->idle_time)); if (ti->stime) { delta = cycle_to_nsec(ti->stime); account_system_index_time(tsk, delta, CPUTIME_SYSTEM); } if (ti->hardirq_time) { delta = cycle_to_nsec(ti->hardirq_time); account_system_index_time(tsk, delta, CPUTIME_IRQ); } if (ti->softirq_time) { delta = cycle_to_nsec(ti->softirq_time); account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ); } ti->utime = 0; ti->gtime = 0; ti->idle_time = 0; ti->stime = 0; ti->hardirq_time = 0; ti->softirq_time = 0; } /* * Called from the context switch with interrupts disabled, to charge all * accumulated times to the current process, and to prepare accounting on * the next process. */ void arch_vtime_task_switch(struct task_struct *prev) { struct thread_info *pi = task_thread_info(prev); struct thread_info *ni = task_thread_info(current); ni->ac_stamp = pi->ac_stamp; ni->ac_stime = ni->ac_utime = 0; } /* * Account time for a transition between system, hard irq or soft irq state. * Note that this function is called with interrupts enabled. */ static __u64 vtime_delta(struct task_struct *tsk) { struct thread_info *ti = task_thread_info(tsk); __u64 now, delta_stime; WARN_ON_ONCE(!irqs_disabled()); now = ia64_get_itc(); delta_stime = now - ti->ac_stamp; ti->ac_stamp = now; return delta_stime; } void vtime_account_kernel(struct task_struct *tsk) { struct thread_info *ti = task_thread_info(tsk); __u64 stime = vtime_delta(tsk); if (tsk->flags & PF_VCPU) ti->gtime += stime; else ti->stime += stime; } EXPORT_SYMBOL_GPL(vtime_account_kernel); void vtime_account_idle(struct task_struct *tsk) { struct thread_info *ti = task_thread_info(tsk); ti->idle_time += vtime_delta(tsk); } void vtime_account_softirq(struct task_struct *tsk) { struct thread_info *ti = task_thread_info(tsk); ti->softirq_time += vtime_delta(tsk); } void vtime_account_hardirq(struct task_struct *tsk) { struct thread_info *ti = task_thread_info(tsk); ti->hardirq_time += vtime_delta(tsk); } #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ static irqreturn_t timer_interrupt (int irq, void *dev_id) { unsigned long new_itm; if (cpu_is_offline(smp_processor_id())) { return IRQ_HANDLED; } new_itm = local_cpu_data->itm_next; if (!time_after(ia64_get_itc(), new_itm)) printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n", ia64_get_itc(), new_itm); while (1) { new_itm += local_cpu_data->itm_delta; legacy_timer_tick(smp_processor_id() == time_keeper_id); local_cpu_data->itm_next = new_itm; if (time_after(new_itm, ia64_get_itc())) break; /* * Allow IPIs to interrupt the timer loop. */ local_irq_enable(); local_irq_disable(); } do { /* * If we're too close to the next clock tick for * comfort, we increase the safety margin by * intentionally dropping the next tick(s). We do NOT * update itm.next because that would force us to call * xtime_update() which in turn would let our clock run * too fast (with the potentially devastating effect * of losing monotony of time). */ while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2)) new_itm += local_cpu_data->itm_delta; ia64_set_itm(new_itm); /* double check, in case we got hit by a (slow) PMI: */ } while (time_after_eq(ia64_get_itc(), new_itm)); return IRQ_HANDLED; } /* * Encapsulate access to the itm structure for SMP. */ void ia64_cpu_local_tick (void) { int cpu = smp_processor_id(); unsigned long shift = 0, delta; /* arrange for the cycle counter to generate a timer interrupt: */ ia64_set_itv(IA64_TIMER_VECTOR); delta = local_cpu_data->itm_delta; /* * Stagger the timer tick for each CPU so they don't occur all at (almost) the * same time: */ if (cpu) { unsigned long hi = 1UL << ia64_fls(cpu); shift = (2*(cpu - hi) + 1) * delta/hi/2; } local_cpu_data->itm_next = ia64_get_itc() + delta + shift; ia64_set_itm(local_cpu_data->itm_next); } static int nojitter; static int __init nojitter_setup(char *str) { nojitter = 1; printk("Jitter checking for ITC timers disabled\n"); return 1; } __setup("nojitter", nojitter_setup); void ia64_init_itm(void) { unsigned long platform_base_freq, itc_freq; struct pal_freq_ratio itc_ratio, proc_ratio; long status, platform_base_drift, itc_drift; /* * According to SAL v2.6, we need to use a SAL call to determine the platform base * frequency and then a PAL call to determine the frequency ratio between the ITC * and the base frequency. */ status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM, &platform_base_freq, &platform_base_drift); if (status != 0) { printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status)); } else { status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio); if (status != 0) printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status); } if (status != 0) { /* invent "random" values */ printk(KERN_ERR "SAL/PAL failed to obtain frequency info---inventing reasonable values\n"); platform_base_freq = 100000000; platform_base_drift = -1; /* no drift info */ itc_ratio.num = 3; itc_ratio.den = 1; } if (platform_base_freq < 40000000) { printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n", platform_base_freq); platform_base_freq = 75000000; platform_base_drift = -1; } if (!proc_ratio.den) proc_ratio.den = 1; /* avoid division by zero */ if (!itc_ratio.den) itc_ratio.den = 1; /* avoid division by zero */ itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den; local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ; printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, " "ITC freq=%lu.%03luMHz", smp_processor_id(), platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000, itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000); if (platform_base_drift != -1) { itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den; printk("+/-%ldppm\n", itc_drift); } else { itc_drift = -1; printk("\n"); } local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den; local_cpu_data->itc_freq = itc_freq; local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC; local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT) + itc_freq/2)/itc_freq; if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) { #ifdef CONFIG_SMP /* On IA64 in an SMP configuration ITCs are never accurately synchronized. * Jitter compensation requires a cmpxchg which may limit * the scalability of the syscalls for retrieving time. * The ITC synchronization is usually successful to within a few * ITC ticks but this is not a sure thing. If you need to improve * timer performance in SMP situations then boot the kernel with the * "nojitter" option. However, doing so may result in time fluctuating (maybe * even going backward) if the ITC offsets between the individual CPUs * are too large. */ if (!nojitter) itc_jitter_data.itc_jitter = 1; #endif } else /* * ITC is drifty and we have not synchronized the ITCs in smpboot.c. * ITC values may fluctuate significantly between processors. * Clock should not be used for hrtimers. Mark itc as only * useful for boot and testing. * * Note that jitter compensation is off! There is no point of * synchronizing ITCs since they may be large differentials * that change over time. * * The only way to fix this would be to repeatedly sync the * ITCs. Until that time we have to avoid ITC. */ clocksource_itc.rating = 50; /* avoid softlock up message when cpu is unplug and plugged again. */ touch_softlockup_watchdog(); /* Setup the CPU local timer tick */ ia64_cpu_local_tick(); if (!itc_clocksource) { clocksource_register_hz(&clocksource_itc, local_cpu_data->itc_freq); itc_clocksource = &clocksource_itc; } } static u64 itc_get_cycles(struct clocksource *cs) { unsigned long lcycle, now, ret; if (!itc_jitter_data.itc_jitter) return get_cycles(); lcycle = itc_jitter_data.itc_lastcycle; now = get_cycles(); if (lcycle && time_after(lcycle, now)) return lcycle; /* * Keep track of the last timer value returned. * In an SMP environment, you could lose out in contention of * cmpxchg. If so, your cmpxchg returns new value which the * winner of contention updated to. Use the new value instead. */ ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now); if (unlikely(ret != lcycle)) return ret; return now; } void read_persistent_clock64(struct timespec64 *ts) { efi_gettimeofday(ts); } void __init time_init (void) { register_percpu_irq(IA64_TIMER_VECTOR, timer_interrupt, IRQF_IRQPOLL, "timer"); ia64_init_itm(); } /* * Generic udelay assumes that if preemption is allowed and the thread * migrates to another CPU, that the ITC values are synchronized across * all CPUs. */ static void ia64_itc_udelay (unsigned long usecs) { unsigned long start = ia64_get_itc(); unsigned long end = start + usecs*local_cpu_data->cyc_per_usec; while (time_before(ia64_get_itc(), end)) cpu_relax(); } void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay; void udelay (unsigned long usecs) { (*ia64_udelay)(usecs); } EXPORT_SYMBOL(udelay); /* IA64 doesn't cache the timezone */ void update_vsyscall_tz(void) { } void update_vsyscall(struct timekeeper *tk) { write_seqcount_begin(&fsyscall_gtod_data.seq); /* copy vsyscall data */ fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask; fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult; fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift; fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio; fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last; fsyscall_gtod_data.wall_time.sec = tk->xtime_sec; fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec; fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec + ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift); /* normalize */ while (fsyscall_gtod_data.monotonic_time.snsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) { fsyscall_gtod_data.monotonic_time.snsec -= ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift; fsyscall_gtod_data.monotonic_time.sec++; } write_seqcount_end(&fsyscall_gtod_data.seq); }