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 #include <asm/alternative.h> 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 " stckf %1" /* Store current tod clock value */ 134 : "=Q" (S390_lowcore.last_update_timer), 135 "=Q" (S390_lowcore.last_update_clock) 136 : : "cc"); 137 clock = S390_lowcore.last_update_clock - clock; 138 timer -= S390_lowcore.last_update_timer; 139 140 if (hardirq_count()) 141 S390_lowcore.hardirq_timer += timer; 142 else 143 S390_lowcore.system_timer += timer; 144 145 /* Update MT utilization calculation */ 146 if (smp_cpu_mtid && 147 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 148 update_mt_scaling(); 149 150 /* Calculate cputime delta */ 151 user = update_tsk_timer(&tsk->thread.user_timer, 152 READ_ONCE(S390_lowcore.user_timer)); 153 guest = update_tsk_timer(&tsk->thread.guest_timer, 154 READ_ONCE(S390_lowcore.guest_timer)); 155 system = update_tsk_timer(&tsk->thread.system_timer, 156 READ_ONCE(S390_lowcore.system_timer)); 157 hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, 158 READ_ONCE(S390_lowcore.hardirq_timer)); 159 softirq = update_tsk_timer(&tsk->thread.softirq_timer, 160 READ_ONCE(S390_lowcore.softirq_timer)); 161 S390_lowcore.steal_timer += 162 clock - user - guest - system - hardirq - softirq; 163 164 /* Push account value */ 165 if (user) { 166 account_user_time(tsk, cputime_to_nsecs(user)); 167 tsk->utimescaled += cputime_to_nsecs(scale_vtime(user)); 168 } 169 170 if (guest) { 171 account_guest_time(tsk, cputime_to_nsecs(guest)); 172 tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest)); 173 } 174 175 if (system) 176 account_system_index_scaled(tsk, system, CPUTIME_SYSTEM); 177 if (hardirq) 178 account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ); 179 if (softirq) 180 account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ); 181 182 return virt_timer_forward(user + guest + system + hardirq + softirq); 183 } 184 185 void vtime_task_switch(struct task_struct *prev) 186 { 187 do_account_vtime(prev); 188 prev->thread.user_timer = S390_lowcore.user_timer; 189 prev->thread.guest_timer = S390_lowcore.guest_timer; 190 prev->thread.system_timer = S390_lowcore.system_timer; 191 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer; 192 prev->thread.softirq_timer = S390_lowcore.softirq_timer; 193 S390_lowcore.user_timer = current->thread.user_timer; 194 S390_lowcore.guest_timer = current->thread.guest_timer; 195 S390_lowcore.system_timer = current->thread.system_timer; 196 S390_lowcore.hardirq_timer = current->thread.hardirq_timer; 197 S390_lowcore.softirq_timer = current->thread.softirq_timer; 198 } 199 200 /* 201 * In s390, accounting pending user time also implies 202 * accounting system time in order to correctly compute 203 * the stolen time accounting. 204 */ 205 void vtime_flush(struct task_struct *tsk) 206 { 207 u64 steal, avg_steal; 208 209 if (do_account_vtime(tsk)) 210 virt_timer_expire(); 211 212 steal = S390_lowcore.steal_timer; 213 avg_steal = S390_lowcore.avg_steal_timer / 2; 214 if ((s64) steal > 0) { 215 S390_lowcore.steal_timer = 0; 216 account_steal_time(cputime_to_nsecs(steal)); 217 avg_steal += steal; 218 } 219 S390_lowcore.avg_steal_timer = avg_steal; 220 } 221 222 static u64 vtime_delta(void) 223 { 224 u64 timer = S390_lowcore.last_update_timer; 225 226 S390_lowcore.last_update_timer = get_vtimer(); 227 228 return timer - S390_lowcore.last_update_timer; 229 } 230 231 /* 232 * Update process times based on virtual cpu times stored by entry.S 233 * to the lowcore fields user_timer, system_timer & steal_clock. 234 */ 235 void vtime_account_kernel(struct task_struct *tsk) 236 { 237 u64 delta = vtime_delta(); 238 239 if (tsk->flags & PF_VCPU) 240 S390_lowcore.guest_timer += delta; 241 else 242 S390_lowcore.system_timer += delta; 243 244 virt_timer_forward(delta); 245 } 246 EXPORT_SYMBOL_GPL(vtime_account_kernel); 247 248 void vtime_account_softirq(struct task_struct *tsk) 249 { 250 u64 delta = vtime_delta(); 251 252 S390_lowcore.softirq_timer += delta; 253 254 virt_timer_forward(delta); 255 } 256 257 void vtime_account_hardirq(struct task_struct *tsk) 258 { 259 u64 delta = vtime_delta(); 260 261 S390_lowcore.hardirq_timer += delta; 262 263 virt_timer_forward(delta); 264 } 265 266 /* 267 * Sorted add to a list. List is linear searched until first bigger 268 * element is found. 269 */ 270 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 271 { 272 struct vtimer_list *tmp; 273 274 list_for_each_entry(tmp, head, entry) { 275 if (tmp->expires > timer->expires) { 276 list_add_tail(&timer->entry, &tmp->entry); 277 return; 278 } 279 } 280 list_add_tail(&timer->entry, head); 281 } 282 283 /* 284 * Handler for expired virtual CPU timer. 285 */ 286 static void virt_timer_expire(void) 287 { 288 struct vtimer_list *timer, *tmp; 289 unsigned long elapsed; 290 LIST_HEAD(cb_list); 291 292 /* walk timer list, fire all expired timers */ 293 spin_lock(&virt_timer_lock); 294 elapsed = atomic64_read(&virt_timer_elapsed); 295 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 296 if (timer->expires < elapsed) 297 /* move expired timer to the callback queue */ 298 list_move_tail(&timer->entry, &cb_list); 299 else 300 timer->expires -= elapsed; 301 } 302 if (!list_empty(&virt_timer_list)) { 303 timer = list_first_entry(&virt_timer_list, 304 struct vtimer_list, entry); 305 atomic64_set(&virt_timer_current, timer->expires); 306 } 307 atomic64_sub(elapsed, &virt_timer_elapsed); 308 spin_unlock(&virt_timer_lock); 309 310 /* Do callbacks and recharge periodic timers */ 311 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 312 list_del_init(&timer->entry); 313 timer->function(timer->data); 314 if (timer->interval) { 315 /* Recharge interval timer */ 316 timer->expires = timer->interval + 317 atomic64_read(&virt_timer_elapsed); 318 spin_lock(&virt_timer_lock); 319 list_add_sorted(timer, &virt_timer_list); 320 spin_unlock(&virt_timer_lock); 321 } 322 } 323 } 324 325 void init_virt_timer(struct vtimer_list *timer) 326 { 327 timer->function = NULL; 328 INIT_LIST_HEAD(&timer->entry); 329 } 330 EXPORT_SYMBOL(init_virt_timer); 331 332 static inline int vtimer_pending(struct vtimer_list *timer) 333 { 334 return !list_empty(&timer->entry); 335 } 336 337 static void internal_add_vtimer(struct vtimer_list *timer) 338 { 339 if (list_empty(&virt_timer_list)) { 340 /* First timer, just program it. */ 341 atomic64_set(&virt_timer_current, timer->expires); 342 atomic64_set(&virt_timer_elapsed, 0); 343 list_add(&timer->entry, &virt_timer_list); 344 } else { 345 /* Update timer against current base. */ 346 timer->expires += atomic64_read(&virt_timer_elapsed); 347 if (likely((s64) timer->expires < 348 (s64) atomic64_read(&virt_timer_current))) 349 /* The new timer expires before the current timer. */ 350 atomic64_set(&virt_timer_current, timer->expires); 351 /* Insert new timer into the list. */ 352 list_add_sorted(timer, &virt_timer_list); 353 } 354 } 355 356 static void __add_vtimer(struct vtimer_list *timer, int periodic) 357 { 358 unsigned long flags; 359 360 timer->interval = periodic ? timer->expires : 0; 361 spin_lock_irqsave(&virt_timer_lock, flags); 362 internal_add_vtimer(timer); 363 spin_unlock_irqrestore(&virt_timer_lock, flags); 364 } 365 366 /* 367 * add_virt_timer - add a oneshot virtual CPU timer 368 */ 369 void add_virt_timer(struct vtimer_list *timer) 370 { 371 __add_vtimer(timer, 0); 372 } 373 EXPORT_SYMBOL(add_virt_timer); 374 375 /* 376 * add_virt_timer_int - add an interval virtual CPU timer 377 */ 378 void add_virt_timer_periodic(struct vtimer_list *timer) 379 { 380 __add_vtimer(timer, 1); 381 } 382 EXPORT_SYMBOL(add_virt_timer_periodic); 383 384 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 385 { 386 unsigned long flags; 387 int rc; 388 389 BUG_ON(!timer->function); 390 391 if (timer->expires == expires && vtimer_pending(timer)) 392 return 1; 393 spin_lock_irqsave(&virt_timer_lock, flags); 394 rc = vtimer_pending(timer); 395 if (rc) 396 list_del_init(&timer->entry); 397 timer->interval = periodic ? expires : 0; 398 timer->expires = expires; 399 internal_add_vtimer(timer); 400 spin_unlock_irqrestore(&virt_timer_lock, flags); 401 return rc; 402 } 403 404 /* 405 * returns whether it has modified a pending timer (1) or not (0) 406 */ 407 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 408 { 409 return __mod_vtimer(timer, expires, 0); 410 } 411 EXPORT_SYMBOL(mod_virt_timer); 412 413 /* 414 * returns whether it has modified a pending timer (1) or not (0) 415 */ 416 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 417 { 418 return __mod_vtimer(timer, expires, 1); 419 } 420 EXPORT_SYMBOL(mod_virt_timer_periodic); 421 422 /* 423 * Delete a virtual timer. 424 * 425 * returns whether the deleted timer was pending (1) or not (0) 426 */ 427 int del_virt_timer(struct vtimer_list *timer) 428 { 429 unsigned long flags; 430 431 if (!vtimer_pending(timer)) 432 return 0; 433 spin_lock_irqsave(&virt_timer_lock, flags); 434 list_del_init(&timer->entry); 435 spin_unlock_irqrestore(&virt_timer_lock, flags); 436 return 1; 437 } 438 EXPORT_SYMBOL(del_virt_timer); 439 440 /* 441 * Start the virtual CPU timer on the current CPU. 442 */ 443 void vtime_init(void) 444 { 445 /* set initial cpu timer */ 446 set_vtimer(VTIMER_MAX_SLICE); 447 /* Setup initial MT scaling values */ 448 if (smp_cpu_mtid) { 449 __this_cpu_write(mt_scaling_jiffies, jiffies); 450 __this_cpu_write(mt_scaling_mult, 1); 451 __this_cpu_write(mt_scaling_div, 1); 452 stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 453 } 454 } 455