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