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Linux/arch/ia64/kernel/time.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * linux/arch/ia64/kernel/time.c
  4  *
  5  * Copyright (C) 1998-2003 Hewlett-Packard Co
  6  *      Stephane Eranian <eranian@hpl.hp.com>
  7  *      David Mosberger <davidm@hpl.hp.com>
  8  * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
  9  * Copyright (C) 1999-2000 VA Linux Systems
 10  * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
 11  */
 12 
 13 #include <linux/cpu.h>
 14 #include <linux/init.h>
 15 #include <linux/kernel.h>
 16 #include <linux/module.h>
 17 #include <linux/profile.h>
 18 #include <linux/sched.h>
 19 #include <linux/time.h>
 20 #include <linux/nmi.h>
 21 #include <linux/interrupt.h>
 22 #include <linux/efi.h>
 23 #include <linux/timex.h>
 24 #include <linux/timekeeper_internal.h>
 25 #include <linux/platform_device.h>
 26 #include <linux/sched/cputime.h>
 27 
 28 #include <asm/machvec.h>
 29 #include <asm/delay.h>
 30 #include <asm/hw_irq.h>
 31 #include <asm/ptrace.h>
 32 #include <asm/sal.h>
 33 #include <asm/sections.h>
 34 
 35 #include "fsyscall_gtod_data.h"
 36 
 37 static u64 itc_get_cycles(struct clocksource *cs);
 38 
 39 struct fsyscall_gtod_data_t fsyscall_gtod_data;
 40 
 41 struct itc_jitter_data_t itc_jitter_data;
 42 
 43 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
 44 
 45 #ifdef CONFIG_IA64_DEBUG_IRQ
 46 
 47 unsigned long last_cli_ip;
 48 EXPORT_SYMBOL(last_cli_ip);
 49 
 50 #endif
 51 
 52 static struct clocksource clocksource_itc = {
 53         .name           = "itc",
 54         .rating         = 350,
 55         .read           = itc_get_cycles,
 56         .mask           = CLOCKSOURCE_MASK(64),
 57         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 58 };
 59 static struct clocksource *itc_clocksource;
 60 
 61 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 62 
 63 #include <linux/kernel_stat.h>
 64 
 65 extern u64 cycle_to_nsec(u64 cyc);
 66 
 67 void vtime_flush(struct task_struct *tsk)
 68 {
 69         struct thread_info *ti = task_thread_info(tsk);
 70         u64 delta;
 71 
 72         if (ti->utime)
 73                 account_user_time(tsk, cycle_to_nsec(ti->utime));
 74 
 75         if (ti->gtime)
 76                 account_guest_time(tsk, cycle_to_nsec(ti->gtime));
 77 
 78         if (ti->idle_time)
 79                 account_idle_time(cycle_to_nsec(ti->idle_time));
 80 
 81         if (ti->stime) {
 82                 delta = cycle_to_nsec(ti->stime);
 83                 account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
 84         }
 85 
 86         if (ti->hardirq_time) {
 87                 delta = cycle_to_nsec(ti->hardirq_time);
 88                 account_system_index_time(tsk, delta, CPUTIME_IRQ);
 89         }
 90 
 91         if (ti->softirq_time) {
 92                 delta = cycle_to_nsec(ti->softirq_time);
 93                 account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
 94         }
 95 
 96         ti->utime = 0;
 97         ti->gtime = 0;
 98         ti->idle_time = 0;
 99         ti->stime = 0;
100         ti->hardirq_time = 0;
101         ti->softirq_time = 0;
102 }
103 
104 /*
105  * Called from the context switch with interrupts disabled, to charge all
106  * accumulated times to the current process, and to prepare accounting on
107  * the next process.
108  */
109 void arch_vtime_task_switch(struct task_struct *prev)
110 {
111         struct thread_info *pi = task_thread_info(prev);
112         struct thread_info *ni = task_thread_info(current);
113 
114         ni->ac_stamp = pi->ac_stamp;
115         ni->ac_stime = ni->ac_utime = 0;
116 }
117 
118 /*
119  * Account time for a transition between system, hard irq or soft irq state.
120  * Note that this function is called with interrupts enabled.
121  */
122 static __u64 vtime_delta(struct task_struct *tsk)
123 {
124         struct thread_info *ti = task_thread_info(tsk);
125         __u64 now, delta_stime;
126 
127         WARN_ON_ONCE(!irqs_disabled());
128 
129         now = ia64_get_itc();
130         delta_stime = now - ti->ac_stamp;
131         ti->ac_stamp = now;
132 
133         return delta_stime;
134 }
135 
136 void vtime_account_system(struct task_struct *tsk)
137 {
138         struct thread_info *ti = task_thread_info(tsk);
139         __u64 stime = vtime_delta(tsk);
140 
141         if ((tsk->flags & PF_VCPU) && !irq_count())
142                 ti->gtime += stime;
143         else if (hardirq_count())
144                 ti->hardirq_time += stime;
145         else if (in_serving_softirq())
146                 ti->softirq_time += stime;
147         else
148                 ti->stime += stime;
149 }
150 EXPORT_SYMBOL_GPL(vtime_account_system);
151 
152 void vtime_account_idle(struct task_struct *tsk)
153 {
154         struct thread_info *ti = task_thread_info(tsk);
155 
156         ti->idle_time += vtime_delta(tsk);
157 }
158 
159 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
160 
161 static irqreturn_t
162 timer_interrupt (int irq, void *dev_id)
163 {
164         unsigned long new_itm;
165 
166         if (cpu_is_offline(smp_processor_id())) {
167                 return IRQ_HANDLED;
168         }
169 
170         platform_timer_interrupt(irq, dev_id);
171 
172         new_itm = local_cpu_data->itm_next;
173 
174         if (!time_after(ia64_get_itc(), new_itm))
175                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
176                        ia64_get_itc(), new_itm);
177 
178         profile_tick(CPU_PROFILING);
179 
180         while (1) {
181                 update_process_times(user_mode(get_irq_regs()));
182 
183                 new_itm += local_cpu_data->itm_delta;
184 
185                 if (smp_processor_id() == time_keeper_id)
186                         xtime_update(1);
187 
188                 local_cpu_data->itm_next = new_itm;
189 
190                 if (time_after(new_itm, ia64_get_itc()))
191                         break;
192 
193                 /*
194                  * Allow IPIs to interrupt the timer loop.
195                  */
196                 local_irq_enable();
197                 local_irq_disable();
198         }
199 
200         do {
201                 /*
202                  * If we're too close to the next clock tick for
203                  * comfort, we increase the safety margin by
204                  * intentionally dropping the next tick(s).  We do NOT
205                  * update itm.next because that would force us to call
206                  * xtime_update() which in turn would let our clock run
207                  * too fast (with the potentially devastating effect
208                  * of losing monotony of time).
209                  */
210                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
211                         new_itm += local_cpu_data->itm_delta;
212                 ia64_set_itm(new_itm);
213                 /* double check, in case we got hit by a (slow) PMI: */
214         } while (time_after_eq(ia64_get_itc(), new_itm));
215         return IRQ_HANDLED;
216 }
217 
218 /*
219  * Encapsulate access to the itm structure for SMP.
220  */
221 void
222 ia64_cpu_local_tick (void)
223 {
224         int cpu = smp_processor_id();
225         unsigned long shift = 0, delta;
226 
227         /* arrange for the cycle counter to generate a timer interrupt: */
228         ia64_set_itv(IA64_TIMER_VECTOR);
229 
230         delta = local_cpu_data->itm_delta;
231         /*
232          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
233          * same time:
234          */
235         if (cpu) {
236                 unsigned long hi = 1UL << ia64_fls(cpu);
237                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
238         }
239         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
240         ia64_set_itm(local_cpu_data->itm_next);
241 }
242 
243 static int nojitter;
244 
245 static int __init nojitter_setup(char *str)
246 {
247         nojitter = 1;
248         printk("Jitter checking for ITC timers disabled\n");
249         return 1;
250 }
251 
252 __setup("nojitter", nojitter_setup);
253 
254 
255 void ia64_init_itm(void)
256 {
257         unsigned long platform_base_freq, itc_freq;
258         struct pal_freq_ratio itc_ratio, proc_ratio;
259         long status, platform_base_drift, itc_drift;
260 
261         /*
262          * According to SAL v2.6, we need to use a SAL call to determine the platform base
263          * frequency and then a PAL call to determine the frequency ratio between the ITC
264          * and the base frequency.
265          */
266         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
267                                     &platform_base_freq, &platform_base_drift);
268         if (status != 0) {
269                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
270         } else {
271                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
272                 if (status != 0)
273                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
274         }
275         if (status != 0) {
276                 /* invent "random" values */
277                 printk(KERN_ERR
278                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
279                 platform_base_freq = 100000000;
280                 platform_base_drift = -1;       /* no drift info */
281                 itc_ratio.num = 3;
282                 itc_ratio.den = 1;
283         }
284         if (platform_base_freq < 40000000) {
285                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
286                        platform_base_freq);
287                 platform_base_freq = 75000000;
288                 platform_base_drift = -1;
289         }
290         if (!proc_ratio.den)
291                 proc_ratio.den = 1;     /* avoid division by zero */
292         if (!itc_ratio.den)
293                 itc_ratio.den = 1;      /* avoid division by zero */
294 
295         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
296 
297         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
298         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
299                "ITC freq=%lu.%03luMHz", smp_processor_id(),
300                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
301                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
302 
303         if (platform_base_drift != -1) {
304                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
305                 printk("+/-%ldppm\n", itc_drift);
306         } else {
307                 itc_drift = -1;
308                 printk("\n");
309         }
310 
311         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
312         local_cpu_data->itc_freq = itc_freq;
313         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
314         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
315                                         + itc_freq/2)/itc_freq;
316 
317         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
318 #ifdef CONFIG_SMP
319                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
320                  * Jitter compensation requires a cmpxchg which may limit
321                  * the scalability of the syscalls for retrieving time.
322                  * The ITC synchronization is usually successful to within a few
323                  * ITC ticks but this is not a sure thing. If you need to improve
324                  * timer performance in SMP situations then boot the kernel with the
325                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
326                  * even going backward) if the ITC offsets between the individual CPUs
327                  * are too large.
328                  */
329                 if (!nojitter)
330                         itc_jitter_data.itc_jitter = 1;
331 #endif
332         } else
333                 /*
334                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
335                  * ITC values may fluctuate significantly between processors.
336                  * Clock should not be used for hrtimers. Mark itc as only
337                  * useful for boot and testing.
338                  *
339                  * Note that jitter compensation is off! There is no point of
340                  * synchronizing ITCs since they may be large differentials
341                  * that change over time.
342                  *
343                  * The only way to fix this would be to repeatedly sync the
344                  * ITCs. Until that time we have to avoid ITC.
345                  */
346                 clocksource_itc.rating = 50;
347 
348         /* avoid softlock up message when cpu is unplug and plugged again. */
349         touch_softlockup_watchdog();
350 
351         /* Setup the CPU local timer tick */
352         ia64_cpu_local_tick();
353 
354         if (!itc_clocksource) {
355                 clocksource_register_hz(&clocksource_itc,
356                                                 local_cpu_data->itc_freq);
357                 itc_clocksource = &clocksource_itc;
358         }
359 }
360 
361 static u64 itc_get_cycles(struct clocksource *cs)
362 {
363         unsigned long lcycle, now, ret;
364 
365         if (!itc_jitter_data.itc_jitter)
366                 return get_cycles();
367 
368         lcycle = itc_jitter_data.itc_lastcycle;
369         now = get_cycles();
370         if (lcycle && time_after(lcycle, now))
371                 return lcycle;
372 
373         /*
374          * Keep track of the last timer value returned.
375          * In an SMP environment, you could lose out in contention of
376          * cmpxchg. If so, your cmpxchg returns new value which the
377          * winner of contention updated to. Use the new value instead.
378          */
379         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
380         if (unlikely(ret != lcycle))
381                 return ret;
382 
383         return now;
384 }
385 
386 
387 static struct irqaction timer_irqaction = {
388         .handler =      timer_interrupt,
389         .flags =        IRQF_IRQPOLL,
390         .name =         "timer"
391 };
392 
393 void read_persistent_clock64(struct timespec64 *ts)
394 {
395         efi_gettimeofday(ts);
396 }
397 
398 void __init
399 time_init (void)
400 {
401         register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
402         ia64_init_itm();
403 }
404 
405 /*
406  * Generic udelay assumes that if preemption is allowed and the thread
407  * migrates to another CPU, that the ITC values are synchronized across
408  * all CPUs.
409  */
410 static void
411 ia64_itc_udelay (unsigned long usecs)
412 {
413         unsigned long start = ia64_get_itc();
414         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
415 
416         while (time_before(ia64_get_itc(), end))
417                 cpu_relax();
418 }
419 
420 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
421 
422 void
423 udelay (unsigned long usecs)
424 {
425         (*ia64_udelay)(usecs);
426 }
427 EXPORT_SYMBOL(udelay);
428 
429 /* IA64 doesn't cache the timezone */
430 void update_vsyscall_tz(void)
431 {
432 }
433 
434 void update_vsyscall(struct timekeeper *tk)
435 {
436         write_seqcount_begin(&fsyscall_gtod_data.seq);
437 
438         /* copy vsyscall data */
439         fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask;
440         fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult;
441         fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift;
442         fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio;
443         fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last;
444 
445         fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
446         fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
447 
448         fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec
449                                               + tk->wall_to_monotonic.tv_sec;
450         fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec
451                                                 + ((u64)tk->wall_to_monotonic.tv_nsec
452                                                         << tk->tkr_mono.shift);
453 
454         /* normalize */
455         while (fsyscall_gtod_data.monotonic_time.snsec >=
456                                         (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
457                 fsyscall_gtod_data.monotonic_time.snsec -=
458                                         ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
459                 fsyscall_gtod_data.monotonic_time.sec++;
460         }
461 
462         write_seqcount_end(&fsyscall_gtod_data.seq);
463 }
464 
465 

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