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