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