arch/ia64/kernel/time.c

   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