1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Virtual cpu timer based timer functions. 4 * 5 * Copyright IBM Corp. 2004, 2012 6 * Author(s): Jan Glauber <jan.glauber@de.ibm.com> 7 */ 8 9 #include <linux/kernel_stat.h> 10 #include <linux/sched/cputime.h> 11 #include <linux/export.h> 12 #include <linux/kernel.h> 13 #include <linux/timex.h> 14 #include <linux/types.h> 15 #include <linux/time.h> 16 17 #include <asm/vtimer.h> 18 #include <asm/vtime.h> 19 #include <asm/cpu_mf.h> 20 #include <asm/smp.h> 21 22 #include "entry.h" 23 24 static void virt_timer_expire(void); 25 26 static LIST_HEAD(virt_timer_list); 27 static DEFINE_SPINLOCK(virt_timer_lock); 28 static atomic64_t virt_timer_current; 29 static atomic64_t virt_timer_elapsed; 30 31 DEFINE_PER_CPU(u64, mt_cycles[8]); 32 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 }; 33 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 }; 34 static DEFINE_PER_CPU(u64, mt_scaling_jiffies); 35 36 static inline u64 get_vtimer(void) 37 { 38 u64 timer; 39 40 asm volatile("stpt %0" : "=Q" (timer)); 41 return timer; 42 } 43 44 static inline void set_vtimer(u64 expires) 45 { 46 u64 timer; 47 48 asm volatile( 49 " stpt %0\n" /* Store current cpu timer value */ 50 " spt %1" /* Set new value imm. afterwards */ 51 : "=Q" (timer) : "Q" (expires)); 52 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer; 53 S390_lowcore.last_update_timer = expires; 54 } 55 56 static inline int virt_timer_forward(u64 elapsed) 57 { 58 BUG_ON(!irqs_disabled()); 59 60 if (list_empty(&virt_timer_list)) 61 return 0; 62 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed); 63 return elapsed >= atomic64_read(&virt_timer_current); 64 } 65 66 static void update_mt_scaling(void) 67 { 68 u64 cycles_new[8], *cycles_old; 69 u64 delta, fac, mult, div; 70 int i; 71 72 stcctm(MT_DIAG, smp_cpu_mtid + 1, cycles_new); 73 cycles_old = this_cpu_ptr(mt_cycles); 74 fac = 1; 75 mult = div = 0; 76 for (i = 0; i <= smp_cpu_mtid; i++) { 77 delta = cycles_new[i] - cycles_old[i]; 78 div += delta; 79 mult *= i + 1; 80 mult += delta * fac; 81 fac *= i + 1; 82 } 83 div *= fac; 84 if (div > 0) { 85 /* Update scaling factor */ 86 __this_cpu_write(mt_scaling_mult, mult); 87 __this_cpu_write(mt_scaling_div, div); 88 memcpy(cycles_old, cycles_new, 89 sizeof(u64) * (smp_cpu_mtid + 1)); 90 } 91 __this_cpu_write(mt_scaling_jiffies, jiffies_64); 92 } 93 94 static inline u64 update_tsk_timer(unsigned long *tsk_vtime, u64 new) 95 { 96 u64 delta; 97 98 delta = new - *tsk_vtime; 99 *tsk_vtime = new; 100 return delta; 101 } 102 103 104 static inline u64 scale_vtime(u64 vtime) 105 { 106 u64 mult = __this_cpu_read(mt_scaling_mult); 107 u64 div = __this_cpu_read(mt_scaling_div); 108 109 if (smp_cpu_mtid) 110 return vtime * mult / div; 111 return vtime; 112 } 113 114 static void account_system_index_scaled(struct task_struct *p, u64 cputime, 115 enum cpu_usage_stat index) 116 { 117 p->stimescaled += cputime_to_nsecs(scale_vtime(cputime)); 118 account_system_index_time(p, cputime_to_nsecs(cputime), index); 119 } 120 121 /* 122 * Update process times based on virtual cpu times stored by entry.S 123 * to the lowcore fields user_timer, system_timer & steal_clock. 124 */ 125 static int do_account_vtime(struct task_struct *tsk) 126 { 127 u64 timer, clock, user, guest, system, hardirq, softirq; 128 129 timer = S390_lowcore.last_update_timer; 130 clock = S390_lowcore.last_update_clock; 131 asm volatile( 132 " stpt %0\n" /* Store current cpu timer value */ 133 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES 134 " stckf %1" /* Store current tod clock value */ 135 #else 136 " stck %1" /* Store current tod clock value */ 137 #endif 138 : "=Q" (S390_lowcore.last_update_timer), 139 "=Q" (S390_lowcore.last_update_clock)); 140 clock = S390_lowcore.last_update_clock - clock; 141 timer -= S390_lowcore.last_update_timer; 142 143 if (hardirq_count()) 144 S390_lowcore.hardirq_timer += timer; 145 else 146 S390_lowcore.system_timer += timer; 147 148 /* Update MT utilization calculation */ 149 if (smp_cpu_mtid && 150 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 151 update_mt_scaling(); 152 153 /* Calculate cputime delta */ 154 user = update_tsk_timer(&tsk->thread.user_timer, 155 READ_ONCE(S390_lowcore.user_timer)); 156 guest = update_tsk_timer(&tsk->thread.guest_timer, 157 READ_ONCE(S390_lowcore.guest_timer)); 158 system = update_tsk_timer(&tsk->thread.system_timer, 159 READ_ONCE(S390_lowcore.system_timer)); 160 hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, 161 READ_ONCE(S390_lowcore.hardirq_timer)); 162 softirq = update_tsk_timer(&tsk->thread.softirq_timer, 163 READ_ONCE(S390_lowcore.softirq_timer)); 164 S390_lowcore.steal_timer += 165 clock - user - guest - system - hardirq - softirq; 166 167 /* Push account value */ 168 if (user) { 169 account_user_time(tsk, cputime_to_nsecs(user)); 170 tsk->utimescaled += cputime_to_nsecs(scale_vtime(user)); 171 } 172 173 if (guest) { 174 account_guest_time(tsk, cputime_to_nsecs(guest)); 175 tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest)); 176 } 177 178 if (system) 179 account_system_index_scaled(tsk, system, CPUTIME_SYSTEM); 180 if (hardirq) 181 account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ); 182 if (softirq) 183 account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ); 184 185 return virt_timer_forward(user + guest + system + hardirq + softirq); 186 } 187 188 void vtime_task_switch(struct task_struct *prev) 189 { 190 do_account_vtime(prev); 191 prev->thread.user_timer = S390_lowcore.user_timer; 192 prev->thread.guest_timer = S390_lowcore.guest_timer; 193 prev->thread.system_timer = S390_lowcore.system_timer; 194 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer; 195 prev->thread.softirq_timer = S390_lowcore.softirq_timer; 196 S390_lowcore.user_timer = current->thread.user_timer; 197 S390_lowcore.guest_timer = current->thread.guest_timer; 198 S390_lowcore.system_timer = current->thread.system_timer; 199 S390_lowcore.hardirq_timer = current->thread.hardirq_timer; 200 S390_lowcore.softirq_timer = current->thread.softirq_timer; 201 } 202 203 /* 204 * In s390, accounting pending user time also implies 205 * accounting system time in order to correctly compute 206 * the stolen time accounting. 207 */ 208 void vtime_flush(struct task_struct *tsk) 209 { 210 u64 steal, avg_steal; 211 212 if (do_account_vtime(tsk)) 213 virt_timer_expire(); 214 215 steal = S390_lowcore.steal_timer; 216 avg_steal = S390_lowcore.avg_steal_timer / 2; 217 if ((s64) steal > 0) { 218 S390_lowcore.steal_timer = 0; 219 account_steal_time(steal); 220 avg_steal += steal; 221 } 222 S390_lowcore.avg_steal_timer = avg_steal; 223 } 224 225 static u64 vtime_delta(void) 226 { 227 u64 timer = S390_lowcore.last_update_timer; 228 229 S390_lowcore.last_update_timer = get_vtimer(); 230 231 return timer - S390_lowcore.last_update_timer; 232 } 233 234 /* 235 * Update process times based on virtual cpu times stored by entry.S 236 * to the lowcore fields user_timer, system_timer & steal_clock. 237 */ 238 void vtime_account_kernel(struct task_struct *tsk) 239 { 240 u64 delta = vtime_delta(); 241 242 if (tsk->flags & PF_VCPU) 243 S390_lowcore.guest_timer += delta; 244 else 245 S390_lowcore.system_timer += delta; 246 247 virt_timer_forward(delta); 248 } 249 EXPORT_SYMBOL_GPL(vtime_account_kernel); 250 251 void vtime_account_softirq(struct task_struct *tsk) 252 { 253 u64 delta = vtime_delta(); 254 255 S390_lowcore.softirq_timer += delta; 256 257 virt_timer_forward(delta); 258 } 259 260 void vtime_account_hardirq(struct task_struct *tsk) 261 { 262 u64 delta = vtime_delta(); 263 264 S390_lowcore.hardirq_timer += delta; 265 266 virt_timer_forward(delta); 267 } 268 269 /* 270 * Sorted add to a list. List is linear searched until first bigger 271 * element is found. 272 */ 273 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 274 { 275 struct vtimer_list *tmp; 276 277 list_for_each_entry(tmp, head, entry) { 278 if (tmp->expires > timer->expires) { 279 list_add_tail(&timer->entry, &tmp->entry); 280 return; 281 } 282 } 283 list_add_tail(&timer->entry, head); 284 } 285 286 /* 287 * Handler for expired virtual CPU timer. 288 */ 289 static void virt_timer_expire(void) 290 { 291 struct vtimer_list *timer, *tmp; 292 unsigned long elapsed; 293 LIST_HEAD(cb_list); 294 295 /* walk timer list, fire all expired timers */ 296 spin_lock(&virt_timer_lock); 297 elapsed = atomic64_read(&virt_timer_elapsed); 298 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 299 if (timer->expires < elapsed) 300 /* move expired timer to the callback queue */ 301 list_move_tail(&timer->entry, &cb_list); 302 else 303 timer->expires -= elapsed; 304 } 305 if (!list_empty(&virt_timer_list)) { 306 timer = list_first_entry(&virt_timer_list, 307 struct vtimer_list, entry); 308 atomic64_set(&virt_timer_current, timer->expires); 309 } 310 atomic64_sub(elapsed, &virt_timer_elapsed); 311 spin_unlock(&virt_timer_lock); 312 313 /* Do callbacks and recharge periodic timers */ 314 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 315 list_del_init(&timer->entry); 316 timer->function(timer->data); 317 if (timer->interval) { 318 /* Recharge interval timer */ 319 timer->expires = timer->interval + 320 atomic64_read(&virt_timer_elapsed); 321 spin_lock(&virt_timer_lock); 322 list_add_sorted(timer, &virt_timer_list); 323 spin_unlock(&virt_timer_lock); 324 } 325 } 326 } 327 328 void init_virt_timer(struct vtimer_list *timer) 329 { 330 timer->function = NULL; 331 INIT_LIST_HEAD(&timer->entry); 332 } 333 EXPORT_SYMBOL(init_virt_timer); 334 335 static inline int vtimer_pending(struct vtimer_list *timer) 336 { 337 return !list_empty(&timer->entry); 338 } 339 340 static void internal_add_vtimer(struct vtimer_list *timer) 341 { 342 if (list_empty(&virt_timer_list)) { 343 /* First timer, just program it. */ 344 atomic64_set(&virt_timer_current, timer->expires); 345 atomic64_set(&virt_timer_elapsed, 0); 346 list_add(&timer->entry, &virt_timer_list); 347 } else { 348 /* Update timer against current base. */ 349 timer->expires += atomic64_read(&virt_timer_elapsed); 350 if (likely((s64) timer->expires < 351 (s64) atomic64_read(&virt_timer_current))) 352 /* The new timer expires before the current timer. */ 353 atomic64_set(&virt_timer_current, timer->expires); 354 /* Insert new timer into the list. */ 355 list_add_sorted(timer, &virt_timer_list); 356 } 357 } 358 359 static void __add_vtimer(struct vtimer_list *timer, int periodic) 360 { 361 unsigned long flags; 362 363 timer->interval = periodic ? timer->expires : 0; 364 spin_lock_irqsave(&virt_timer_lock, flags); 365 internal_add_vtimer(timer); 366 spin_unlock_irqrestore(&virt_timer_lock, flags); 367 } 368 369 /* 370 * add_virt_timer - add a oneshot virtual CPU timer 371 */ 372 void add_virt_timer(struct vtimer_list *timer) 373 { 374 __add_vtimer(timer, 0); 375 } 376 EXPORT_SYMBOL(add_virt_timer); 377 378 /* 379 * add_virt_timer_int - add an interval virtual CPU timer 380 */ 381 void add_virt_timer_periodic(struct vtimer_list *timer) 382 { 383 __add_vtimer(timer, 1); 384 } 385 EXPORT_SYMBOL(add_virt_timer_periodic); 386 387 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 388 { 389 unsigned long flags; 390 int rc; 391 392 BUG_ON(!timer->function); 393 394 if (timer->expires == expires && vtimer_pending(timer)) 395 return 1; 396 spin_lock_irqsave(&virt_timer_lock, flags); 397 rc = vtimer_pending(timer); 398 if (rc) 399 list_del_init(&timer->entry); 400 timer->interval = periodic ? expires : 0; 401 timer->expires = expires; 402 internal_add_vtimer(timer); 403 spin_unlock_irqrestore(&virt_timer_lock, flags); 404 return rc; 405 } 406 407 /* 408 * returns whether it has modified a pending timer (1) or not (0) 409 */ 410 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 411 { 412 return __mod_vtimer(timer, expires, 0); 413 } 414 EXPORT_SYMBOL(mod_virt_timer); 415 416 /* 417 * returns whether it has modified a pending timer (1) or not (0) 418 */ 419 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 420 { 421 return __mod_vtimer(timer, expires, 1); 422 } 423 EXPORT_SYMBOL(mod_virt_timer_periodic); 424 425 /* 426 * Delete a virtual timer. 427 * 428 * returns whether the deleted timer was pending (1) or not (0) 429 */ 430 int del_virt_timer(struct vtimer_list *timer) 431 { 432 unsigned long flags; 433 434 if (!vtimer_pending(timer)) 435 return 0; 436 spin_lock_irqsave(&virt_timer_lock, flags); 437 list_del_init(&timer->entry); 438 spin_unlock_irqrestore(&virt_timer_lock, flags); 439 return 1; 440 } 441 EXPORT_SYMBOL(del_virt_timer); 442 443 /* 444 * Start the virtual CPU timer on the current CPU. 445 */ 446 void vtime_init(void) 447 { 448 /* set initial cpu timer */ 449 set_vtimer(VTIMER_MAX_SLICE); 450 /* Setup initial MT scaling values */ 451 if (smp_cpu_mtid) { 452 __this_cpu_write(mt_scaling_jiffies, jiffies); 453 __this_cpu_write(mt_scaling_mult, 1); 454 __this_cpu_write(mt_scaling_div, 1); 455 stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 456 } 457 } 458