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Linux/arch/ia64/kernel/time.c

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  1 /*
  2  * linux/arch/ia64/kernel/time.c
  3  *
  4  * Copyright (C) 1998-2003 Hewlett-Packard Co
  5  *      Stephane Eranian <eranian@hpl.hp.com>
  6  *      David Mosberger <davidm@hpl.hp.com>
  7  * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
  8  * Copyright (C) 1999-2000 VA Linux Systems
  9  * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
 10  */
 11 
 12 #include <linux/cpu.h>
 13 #include <linux/init.h>
 14 #include <linux/kernel.h>
 15 #include <linux/module.h>
 16 #include <linux/profile.h>
 17 #include <linux/sched.h>
 18 #include <linux/time.h>
 19 #include <linux/nmi.h>
 20 #include <linux/interrupt.h>
 21 #include <linux/efi.h>
 22 #include <linux/timex.h>
 23 #include <linux/timekeeper_internal.h>
 24 #include <linux/platform_device.h>
 25 #include <linux/sched/cputime.h>
 26 
 27 #include <asm/machvec.h>
 28 #include <asm/delay.h>
 29 #include <asm/hw_irq.h>
 30 #include <asm/ptrace.h>
 31 #include <asm/sal.h>
 32 #include <asm/sections.h>
 33 
 34 #include "fsyscall_gtod_data.h"
 35 
 36 static u64 itc_get_cycles(struct clocksource *cs);
 37 
 38 struct fsyscall_gtod_data_t fsyscall_gtod_data;
 39 
 40 struct itc_jitter_data_t itc_jitter_data;
 41 
 42 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
 43 
 44 #ifdef CONFIG_IA64_DEBUG_IRQ
 45 
 46 unsigned long last_cli_ip;
 47 EXPORT_SYMBOL(last_cli_ip);
 48 
 49 #endif
 50 
 51 static struct clocksource clocksource_itc = {
 52         .name           = "itc",
 53         .rating         = 350,
 54         .read           = itc_get_cycles,
 55         .mask           = CLOCKSOURCE_MASK(64),
 56         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 57 };
 58 static struct clocksource *itc_clocksource;
 59 
 60 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 61 
 62 #include <linux/kernel_stat.h>
 63 
 64 extern u64 cycle_to_nsec(u64 cyc);
 65 
 66 void vtime_flush(struct task_struct *tsk)
 67 {
 68         struct thread_info *ti = task_thread_info(tsk);
 69         u64 delta;
 70 
 71         if (ti->utime)
 72                 account_user_time(tsk, cycle_to_nsec(ti->utime));
 73 
 74         if (ti->gtime)
 75                 account_guest_time(tsk, cycle_to_nsec(ti->gtime));
 76 
 77         if (ti->idle_time)
 78                 account_idle_time(cycle_to_nsec(ti->idle_time));
 79 
 80         if (ti->stime) {
 81                 delta = cycle_to_nsec(ti->stime);
 82                 account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
 83         }
 84 
 85         if (ti->hardirq_time) {
 86                 delta = cycle_to_nsec(ti->hardirq_time);
 87                 account_system_index_time(tsk, delta, CPUTIME_IRQ);
 88         }
 89 
 90         if (ti->softirq_time) {
 91                 delta = cycle_to_nsec(ti->softirq_time));
 92                 account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
 93         }
 94 
 95         ti->utime = 0;
 96         ti->gtime = 0;
 97         ti->idle_time = 0;
 98         ti->stime = 0;
 99         ti->hardirq_time = 0;
100         ti->softirq_time = 0;
101 }
102 
103 /*
104  * Called from the context switch with interrupts disabled, to charge all
105  * accumulated times to the current process, and to prepare accounting on
106  * the next process.
107  */
108 void arch_vtime_task_switch(struct task_struct *prev)
109 {
110         struct thread_info *pi = task_thread_info(prev);
111         struct thread_info *ni = task_thread_info(current);
112 
113         ni->ac_stamp = pi->ac_stamp;
114         ni->ac_stime = ni->ac_utime = 0;
115 }
116 
117 /*
118  * Account time for a transition between system, hard irq or soft irq state.
119  * Note that this function is called with interrupts enabled.
120  */
121 static __u64 vtime_delta(struct task_struct *tsk)
122 {
123         struct thread_info *ti = task_thread_info(tsk);
124         __u64 now, delta_stime;
125 
126         WARN_ON_ONCE(!irqs_disabled());
127 
128         now = ia64_get_itc();
129         delta_stime = now - ti->ac_stamp;
130         ti->ac_stamp = now;
131 
132         return delta_stime;
133 }
134 
135 void vtime_account_system(struct task_struct *tsk)
136 {
137         struct thread_info *ti = task_thread_info(tsk);
138         __u64 stime = vtime_delta(tsk);
139 
140         if ((tsk->flags & PF_VCPU) && !irq_count())
141                 ti->gtime += stime;
142         else if (hardirq_count())
143                 ti->hardirq_time += stime;
144         else if (in_serving_softirq())
145                 ti->softirq_time += stime;
146         else
147                 ti->stime += stime;
148 }
149 EXPORT_SYMBOL_GPL(vtime_account_system);
150 
151 void vtime_account_idle(struct task_struct *tsk)
152 {
153         struct thread_info *ti = task_thread_info(tsk);
154 
155         ti->idle_time += vtime_delta(tsk);
156 }
157 
158 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
159 
160 static irqreturn_t
161 timer_interrupt (int irq, void *dev_id)
162 {
163         unsigned long new_itm;
164 
165         if (cpu_is_offline(smp_processor_id())) {
166                 return IRQ_HANDLED;
167         }
168 
169         platform_timer_interrupt(irq, dev_id);
170 
171         new_itm = local_cpu_data->itm_next;
172 
173         if (!time_after(ia64_get_itc(), new_itm))
174                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
175                        ia64_get_itc(), new_itm);
176 
177         profile_tick(CPU_PROFILING);
178 
179         while (1) {
180                 update_process_times(user_mode(get_irq_regs()));
181 
182                 new_itm += local_cpu_data->itm_delta;
183 
184                 if (smp_processor_id() == time_keeper_id)
185                         xtime_update(1);
186 
187                 local_cpu_data->itm_next = new_itm;
188 
189                 if (time_after(new_itm, ia64_get_itc()))
190                         break;
191 
192                 /*
193                  * Allow IPIs to interrupt the timer loop.
194                  */
195                 local_irq_enable();
196                 local_irq_disable();
197         }
198 
199         do {
200                 /*
201                  * If we're too close to the next clock tick for
202                  * comfort, we increase the safety margin by
203                  * intentionally dropping the next tick(s).  We do NOT
204                  * update itm.next because that would force us to call
205                  * xtime_update() which in turn would let our clock run
206                  * too fast (with the potentially devastating effect
207                  * of losing monotony of time).
208                  */
209                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
210                         new_itm += local_cpu_data->itm_delta;
211                 ia64_set_itm(new_itm);
212                 /* double check, in case we got hit by a (slow) PMI: */
213         } while (time_after_eq(ia64_get_itc(), new_itm));
214         return IRQ_HANDLED;
215 }
216 
217 /*
218  * Encapsulate access to the itm structure for SMP.
219  */
220 void
221 ia64_cpu_local_tick (void)
222 {
223         int cpu = smp_processor_id();
224         unsigned long shift = 0, delta;
225 
226         /* arrange for the cycle counter to generate a timer interrupt: */
227         ia64_set_itv(IA64_TIMER_VECTOR);
228 
229         delta = local_cpu_data->itm_delta;
230         /*
231          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
232          * same time:
233          */
234         if (cpu) {
235                 unsigned long hi = 1UL << ia64_fls(cpu);
236                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
237         }
238         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
239         ia64_set_itm(local_cpu_data->itm_next);
240 }
241 
242 static int nojitter;
243 
244 static int __init nojitter_setup(char *str)
245 {
246         nojitter = 1;
247         printk("Jitter checking for ITC timers disabled\n");
248         return 1;
249 }
250 
251 __setup("nojitter", nojitter_setup);
252 
253 
254 void ia64_init_itm(void)
255 {
256         unsigned long platform_base_freq, itc_freq;
257         struct pal_freq_ratio itc_ratio, proc_ratio;
258         long status, platform_base_drift, itc_drift;
259 
260         /*
261          * According to SAL v2.6, we need to use a SAL call to determine the platform base
262          * frequency and then a PAL call to determine the frequency ratio between the ITC
263          * and the base frequency.
264          */
265         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
266                                     &platform_base_freq, &platform_base_drift);
267         if (status != 0) {
268                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
269         } else {
270                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
271                 if (status != 0)
272                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
273         }
274         if (status != 0) {
275                 /* invent "random" values */
276                 printk(KERN_ERR
277                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
278                 platform_base_freq = 100000000;
279                 platform_base_drift = -1;       /* no drift info */
280                 itc_ratio.num = 3;
281                 itc_ratio.den = 1;
282         }
283         if (platform_base_freq < 40000000) {
284                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
285                        platform_base_freq);
286                 platform_base_freq = 75000000;
287                 platform_base_drift = -1;
288         }
289         if (!proc_ratio.den)
290                 proc_ratio.den = 1;     /* avoid division by zero */
291         if (!itc_ratio.den)
292                 itc_ratio.den = 1;      /* avoid division by zero */
293 
294         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
295 
296         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
297         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
298                "ITC freq=%lu.%03luMHz", smp_processor_id(),
299                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
300                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
301 
302         if (platform_base_drift != -1) {
303                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
304                 printk("+/-%ldppm\n", itc_drift);
305         } else {
306                 itc_drift = -1;
307                 printk("\n");
308         }
309 
310         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
311         local_cpu_data->itc_freq = itc_freq;
312         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
313         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
314                                         + itc_freq/2)/itc_freq;
315 
316         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
317 #ifdef CONFIG_SMP
318                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
319                  * Jitter compensation requires a cmpxchg which may limit
320                  * the scalability of the syscalls for retrieving time.
321                  * The ITC synchronization is usually successful to within a few
322                  * ITC ticks but this is not a sure thing. If you need to improve
323                  * timer performance in SMP situations then boot the kernel with the
324                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
325                  * even going backward) if the ITC offsets between the individual CPUs
326                  * are too large.
327                  */
328                 if (!nojitter)
329                         itc_jitter_data.itc_jitter = 1;
330 #endif
331         } else
332                 /*
333                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
334                  * ITC values may fluctuate significantly between processors.
335                  * Clock should not be used for hrtimers. Mark itc as only
336                  * useful for boot and testing.
337                  *
338                  * Note that jitter compensation is off! There is no point of
339                  * synchronizing ITCs since they may be large differentials
340                  * that change over time.
341                  *
342                  * The only way to fix this would be to repeatedly sync the
343                  * ITCs. Until that time we have to avoid ITC.
344                  */
345                 clocksource_itc.rating = 50;
346 
347         /* avoid softlock up message when cpu is unplug and plugged again. */
348         touch_softlockup_watchdog();
349 
350         /* Setup the CPU local timer tick */
351         ia64_cpu_local_tick();
352 
353         if (!itc_clocksource) {
354                 clocksource_register_hz(&clocksource_itc,
355                                                 local_cpu_data->itc_freq);
356                 itc_clocksource = &clocksource_itc;
357         }
358 }
359 
360 static u64 itc_get_cycles(struct clocksource *cs)
361 {
362         unsigned long lcycle, now, ret;
363 
364         if (!itc_jitter_data.itc_jitter)
365                 return get_cycles();
366 
367         lcycle = itc_jitter_data.itc_lastcycle;
368         now = get_cycles();
369         if (lcycle && time_after(lcycle, now))
370                 return lcycle;
371 
372         /*
373          * Keep track of the last timer value returned.
374          * In an SMP environment, you could lose out in contention of
375          * cmpxchg. If so, your cmpxchg returns new value which the
376          * winner of contention updated to. Use the new value instead.
377          */
378         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
379         if (unlikely(ret != lcycle))
380                 return ret;
381 
382         return now;
383 }
384 
385 
386 static struct irqaction timer_irqaction = {
387         .handler =      timer_interrupt,
388         .flags =        IRQF_IRQPOLL,
389         .name =         "timer"
390 };
391 
392 void read_persistent_clock64(struct timespec64 *ts)
393 {
394         efi_gettimeofday(ts);
395 }
396 
397 void __init
398 time_init (void)
399 {
400         register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
401         ia64_init_itm();
402 }
403 
404 /*
405  * Generic udelay assumes that if preemption is allowed and the thread
406  * migrates to another CPU, that the ITC values are synchronized across
407  * all CPUs.
408  */
409 static void
410 ia64_itc_udelay (unsigned long usecs)
411 {
412         unsigned long start = ia64_get_itc();
413         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
414 
415         while (time_before(ia64_get_itc(), end))
416                 cpu_relax();
417 }
418 
419 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
420 
421 void
422 udelay (unsigned long usecs)
423 {
424         (*ia64_udelay)(usecs);
425 }
426 EXPORT_SYMBOL(udelay);
427 
428 /* IA64 doesn't cache the timezone */
429 void update_vsyscall_tz(void)
430 {
431 }
432 
433 void update_vsyscall_old(struct timespec *wall, struct timespec *wtm,
434                          struct clocksource *c, u32 mult, u64 cycle_last)
435 {
436         write_seqcount_begin(&fsyscall_gtod_data.seq);
437 
438         /* copy fsyscall clock data */
439         fsyscall_gtod_data.clk_mask = c->mask;
440         fsyscall_gtod_data.clk_mult = mult;
441         fsyscall_gtod_data.clk_shift = c->shift;
442         fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio;
443         fsyscall_gtod_data.clk_cycle_last = cycle_last;
444 
445         /* copy kernel time structures */
446         fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
447         fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
448         fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
449                                                         + wall->tv_sec;
450         fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
451                                                         + wall->tv_nsec;
452 
453         /* normalize */
454         while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
455                 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
456                 fsyscall_gtod_data.monotonic_time.tv_sec++;
457         }
458 
459         write_seqcount_end(&fsyscall_gtod_data.seq);
460 }
461 
462 

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