root/arch/ia64/kernel/time.c

DEFINITIONS

1. vtime_flush
2. arch_vtime_task_switch
3. vtime_delta
4. vtime_account_system
5. vtime_account_idle
6. timer_interrupt
7. ia64_cpu_local_tick
8. nojitter_setup
9. ia64_init_itm
10. itc_get_cycles
11. read_persistent_clock64
12. time_init
13. ia64_itc_udelay
14. udelay
15. update_vsyscall_tz
16. update_vsyscall

   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/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         new_itm = local_cpu_data->itm_next;
 170 
 171         if (!time_after(ia64_get_itc(), new_itm))
 172                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
 173                        ia64_get_itc(), new_itm);
 174 
 175         profile_tick(CPU_PROFILING);
 176 
 177         while (1) {
 178                 update_process_times(user_mode(get_irq_regs()));
 179 
 180                 new_itm += local_cpu_data->itm_delta;
 181 
 182                 if (smp_processor_id() == time_keeper_id)
 183                         xtime_update(1);
 184 
 185                 local_cpu_data->itm_next = new_itm;
 186 
 187                 if (time_after(new_itm, ia64_get_itc()))
 188                         break;
 189 
 190                 /*
 191                  * Allow IPIs to interrupt the timer loop.
 192                  */
 193                 local_irq_enable();
 194                 local_irq_disable();
 195         }
 196 
 197         do {
 198                 /*
 199                  * If we're too close to the next clock tick for
 200                  * comfort, we increase the safety margin by
 201                  * intentionally dropping the next tick(s).  We do NOT
 202                  * update itm.next because that would force us to call
 203                  * xtime_update() which in turn would let our clock run
 204                  * too fast (with the potentially devastating effect
 205                  * of losing monotony of time).
 206                  */
 207                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
 208                         new_itm += local_cpu_data->itm_delta;
 209                 ia64_set_itm(new_itm);
 210                 /* double check, in case we got hit by a (slow) PMI: */
 211         } while (time_after_eq(ia64_get_itc(), new_itm));
 212         return IRQ_HANDLED;
 213 }
 214 
 215 /*
 216  * Encapsulate access to the itm structure for SMP.
 217  */
 218 void
 219 ia64_cpu_local_tick (void)
 220 {
 221         int cpu = smp_processor_id();
 222         unsigned long shift = 0, delta;
 223 
 224         /* arrange for the cycle counter to generate a timer interrupt: */
 225         ia64_set_itv(IA64_TIMER_VECTOR);
 226 
 227         delta = local_cpu_data->itm_delta;
 228         /*
 229          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
 230          * same time:
 231          */
 232         if (cpu) {
 233                 unsigned long hi = 1UL << ia64_fls(cpu);
 234                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
 235         }
 236         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
 237         ia64_set_itm(local_cpu_data->itm_next);
 238 }
 239 
 240 static int nojitter;
 241 
 242 static int __init nojitter_setup(char *str)
 243 {
 244         nojitter = 1;
 245         printk("Jitter checking for ITC timers disabled\n");
 246         return 1;
 247 }
 248 
 249 __setup("nojitter", nojitter_setup);
 250 
 251 
 252 void ia64_init_itm(void)
 253 {
 254         unsigned long platform_base_freq, itc_freq;
 255         struct pal_freq_ratio itc_ratio, proc_ratio;
 256         long status, platform_base_drift, itc_drift;
 257 
 258         /*
 259          * According to SAL v2.6, we need to use a SAL call to determine the platform base
 260          * frequency and then a PAL call to determine the frequency ratio between the ITC
 261          * and the base frequency.
 262          */
 263         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
 264                                     &platform_base_freq, &platform_base_drift);
 265         if (status != 0) {
 266                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
 267         } else {
 268                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
 269                 if (status != 0)
 270                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
 271         }
 272         if (status != 0) {
 273                 /* invent "random" values */
 274                 printk(KERN_ERR
 275                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
 276                 platform_base_freq = 100000000;
 277                 platform_base_drift = -1;       /* no drift info */
 278                 itc_ratio.num = 3;
 279                 itc_ratio.den = 1;
 280         }
 281         if (platform_base_freq < 40000000) {
 282                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
 283                        platform_base_freq);
 284                 platform_base_freq = 75000000;
 285                 platform_base_drift = -1;
 286         }
 287         if (!proc_ratio.den)
 288                 proc_ratio.den = 1;     /* avoid division by zero */
 289         if (!itc_ratio.den)
 290                 itc_ratio.den = 1;      /* avoid division by zero */
 291 
 292         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
 293 
 294         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
 295         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
 296                "ITC freq=%lu.%03luMHz", smp_processor_id(),
 297                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
 298                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
 299 
 300         if (platform_base_drift != -1) {
 301                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
 302                 printk("+/-%ldppm\n", itc_drift);
 303         } else {
 304                 itc_drift = -1;
 305                 printk("\n");
 306         }
 307 
 308         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
 309         local_cpu_data->itc_freq = itc_freq;
 310         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
 311         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
 312                                         + itc_freq/2)/itc_freq;
 313 
 314         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
 315 #ifdef CONFIG_SMP
 316                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
 317                  * Jitter compensation requires a cmpxchg which may limit
 318                  * the scalability of the syscalls for retrieving time.
 319                  * The ITC synchronization is usually successful to within a few
 320                  * ITC ticks but this is not a sure thing. If you need to improve
 321                  * timer performance in SMP situations then boot the kernel with the
 322                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
 323                  * even going backward) if the ITC offsets between the individual CPUs
 324                  * are too large.
 325                  */
 326                 if (!nojitter)
 327                         itc_jitter_data.itc_jitter = 1;
 328 #endif
 329         } else
 330                 /*
 331                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
 332                  * ITC values may fluctuate significantly between processors.
 333                  * Clock should not be used for hrtimers. Mark itc as only
 334                  * useful for boot and testing.
 335                  *
 336                  * Note that jitter compensation is off! There is no point of
 337                  * synchronizing ITCs since they may be large differentials
 338                  * that change over time.
 339                  *
 340                  * The only way to fix this would be to repeatedly sync the
 341                  * ITCs. Until that time we have to avoid ITC.
 342                  */
 343                 clocksource_itc.rating = 50;
 344 
 345         /* avoid softlock up message when cpu is unplug and plugged again. */
 346         touch_softlockup_watchdog();
 347 
 348         /* Setup the CPU local timer tick */
 349         ia64_cpu_local_tick();
 350 
 351         if (!itc_clocksource) {
 352                 clocksource_register_hz(&clocksource_itc,
 353                                                 local_cpu_data->itc_freq);
 354                 itc_clocksource = &clocksource_itc;
 355         }
 356 }
 357 
 358 static u64 itc_get_cycles(struct clocksource *cs)
 359 {
 360         unsigned long lcycle, now, ret;
 361 
 362         if (!itc_jitter_data.itc_jitter)
 363                 return get_cycles();
 364 
 365         lcycle = itc_jitter_data.itc_lastcycle;
 366         now = get_cycles();
 367         if (lcycle && time_after(lcycle, now))
 368                 return lcycle;
 369 
 370         /*
 371          * Keep track of the last timer value returned.
 372          * In an SMP environment, you could lose out in contention of
 373          * cmpxchg. If so, your cmpxchg returns new value which the
 374          * winner of contention updated to. Use the new value instead.
 375          */
 376         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
 377         if (unlikely(ret != lcycle))
 378                 return ret;
 379 
 380         return now;
 381 }
 382 
 383 
 384 static struct irqaction timer_irqaction = {
 385         .handler =      timer_interrupt,
 386         .flags =        IRQF_IRQPOLL,
 387         .name =         "timer"
 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_irqaction);
 399         ia64_init_itm();
 400 }
 401 
 402 /*
 403  * Generic udelay assumes that if preemption is allowed and the thread
 404  * migrates to another CPU, that the ITC values are synchronized across
 405  * all CPUs.
 406  */
 407 static void
 408 ia64_itc_udelay (unsigned long usecs)
 409 {
 410         unsigned long start = ia64_get_itc();
 411         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
 412 
 413         while (time_before(ia64_get_itc(), end))
 414                 cpu_relax();
 415 }
 416 
 417 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
 418 
 419 void
 420 udelay (unsigned long usecs)
 421 {
 422         (*ia64_udelay)(usecs);
 423 }
 424 EXPORT_SYMBOL(udelay);
 425 
 426 /* IA64 doesn't cache the timezone */
 427 void update_vsyscall_tz(void)
 428 {
 429 }
 430 
 431 void update_vsyscall(struct timekeeper *tk)
 432 {
 433         write_seqcount_begin(&fsyscall_gtod_data.seq);
 434 
 435         /* copy vsyscall data */
 436         fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask;
 437         fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult;
 438         fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift;
 439         fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio;
 440         fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last;
 441 
 442         fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
 443         fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
 444 
 445         fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec
 446                                               + tk->wall_to_monotonic.tv_sec;
 447         fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec
 448                                                 + ((u64)tk->wall_to_monotonic.tv_nsec
 449                                                         << tk->tkr_mono.shift);
 450 
 451         /* normalize */
 452         while (fsyscall_gtod_data.monotonic_time.snsec >=
 453                                         (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
 454                 fsyscall_gtod_data.monotonic_time.snsec -=
 455                                         ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
 456                 fsyscall_gtod_data.monotonic_time.sec++;
 457         }
 458 
 459         write_seqcount_end(&fsyscall_gtod_data.seq);
 460 }
 461