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 cur_itm, new_itm, ticks;
 176
 177         if (cpu_is_offline(smp_processor_id())) {
 178                 return IRQ_HANDLED;
 179         }
 180
 181         new_itm = local_cpu_data->itm_next;
 182         cur_itm = ia64_get_itc();
 183
 184         if (!time_after(cur_itm, new_itm)) {
 185                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
 186                        cur_itm, new_itm);
 187                 ticks = 1;
 188         } else {
 189                 ticks = DIV_ROUND_UP(cur_itm - new_itm,
 190                                      local_cpu_data->itm_delta);
 191                 new_itm += ticks * local_cpu_data->itm_delta;
 192         }
 193
 194         if (smp_processor_id() != time_keeper_id)
 195                 ticks = 0;
 196
 197         legacy_timer_tick(ticks);
 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 void read_persistent_clock64(struct timespec64 *ts)
 386 {
 387         efi_gettimeofday(ts);
 388 }
 389
 390 void __init
 391 time_init (void)
 392 {
 393         register_percpu_irq(IA64_TIMER_VECTOR, timer_interrupt, IRQF_IRQPOLL,
 394                             "timer");
 395         ia64_init_itm();
 396 }
 397
 398 /*
 399  * Generic udelay assumes that if preemption is allowed and the thread
 400  * migrates to another CPU, that the ITC values are synchronized across
 401  * all CPUs.
 402  */
 403 static void
 404 ia64_itc_udelay (unsigned long usecs)
 405 {
 406         unsigned long start = ia64_get_itc();
 407         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
 408
 409         while (time_before(ia64_get_itc(), end))
 410                 cpu_relax();
 411 }
 412
 413 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
 414
 415 void
 416 udelay (unsigned long usecs)
 417 {
 418         (*ia64_udelay)(usecs);
 419 }
 420 EXPORT_SYMBOL(udelay);
 421
 422 /* IA64 doesn't cache the timezone */
 423 void update_vsyscall_tz(void)
 424 {
 425 }
 426
 427 void update_vsyscall(struct timekeeper *tk)
 428 {
 429         write_seqcount_begin(&fsyscall_gtod_data.seq);
 430
 431         /* copy vsyscall data */
 432         fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask;
 433         fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult;
 434         fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift;
 435         fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio;
 436         fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last;
 437
 438         fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
 439         fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
 440
 441         fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec
 442                                               + tk->wall_to_monotonic.tv_sec;
 443         fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec
 444                                                 + ((u64)tk->wall_to_monotonic.tv_nsec
 445                                                         << tk->tkr_mono.shift);
 446
 447         /* normalize */
 448         while (fsyscall_gtod_data.monotonic_time.snsec >=
 449                                         (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
 450                 fsyscall_gtod_data.monotonic_time.snsec -=
 451                                         ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
 452                 fsyscall_gtod_data.monotonic_time.sec++;
 453         }
 454
 455         write_seqcount_end(&fsyscall_gtod_data.seq);
 456 }
 457