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" : "=m" (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 : "=m" (timer) : "m" (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 : "=m" (S390_lowcore.last_update_timer), 139 "=m" (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 /* 226 * Update process times based on virtual cpu times stored by entry.S 227 * to the lowcore fields user_timer, system_timer & steal_clock. 228 */ 229 void vtime_account_irq_enter(struct task_struct *tsk) 230 { 231 u64 timer; 232 233 timer = S390_lowcore.last_update_timer; 234 S390_lowcore.last_update_timer = get_vtimer(); 235 timer -= S390_lowcore.last_update_timer; 236 237 if ((tsk->flags & PF_VCPU) && (irq_count() == 0)) 238 S390_lowcore.guest_timer += timer; 239 else if (hardirq_count()) 240 S390_lowcore.hardirq_timer += timer; 241 else if (in_serving_softirq()) 242 S390_lowcore.softirq_timer += timer; 243 else 244 S390_lowcore.system_timer += timer; 245 246 virt_timer_forward(timer); 247 } 248 EXPORT_SYMBOL_GPL(vtime_account_irq_enter); 249 250 void vtime_account_system(struct task_struct *tsk) 251 __attribute__((alias("vtime_account_irq_enter"))); 252 EXPORT_SYMBOL_GPL(vtime_account_system); 253 254 /* 255 * Sorted add to a list. List is linear searched until first bigger 256 * element is found. 257 */ 258 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 259 { 260 struct vtimer_list *tmp; 261 262 list_for_each_entry(tmp, head, entry) { 263 if (tmp->expires > timer->expires) { 264 list_add_tail(&timer->entry, &tmp->entry); 265 return; 266 } 267 } 268 list_add_tail(&timer->entry, head); 269 } 270 271 /* 272 * Handler for expired virtual CPU timer. 273 */ 274 static void virt_timer_expire(void) 275 { 276 struct vtimer_list *timer, *tmp; 277 unsigned long elapsed; 278 LIST_HEAD(cb_list); 279 280 /* walk timer list, fire all expired timers */ 281 spin_lock(&virt_timer_lock); 282 elapsed = atomic64_read(&virt_timer_elapsed); 283 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 284 if (timer->expires < elapsed) 285 /* move expired timer to the callback queue */ 286 list_move_tail(&timer->entry, &cb_list); 287 else 288 timer->expires -= elapsed; 289 } 290 if (!list_empty(&virt_timer_list)) { 291 timer = list_first_entry(&virt_timer_list, 292 struct vtimer_list, entry); 293 atomic64_set(&virt_timer_current, timer->expires); 294 } 295 atomic64_sub(elapsed, &virt_timer_elapsed); 296 spin_unlock(&virt_timer_lock); 297 298 /* Do callbacks and recharge periodic timers */ 299 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 300 list_del_init(&timer->entry); 301 timer->function(timer->data); 302 if (timer->interval) { 303 /* Recharge interval timer */ 304 timer->expires = timer->interval + 305 atomic64_read(&virt_timer_elapsed); 306 spin_lock(&virt_timer_lock); 307 list_add_sorted(timer, &virt_timer_list); 308 spin_unlock(&virt_timer_lock); 309 } 310 } 311 } 312 313 void init_virt_timer(struct vtimer_list *timer) 314 { 315 timer->function = NULL; 316 INIT_LIST_HEAD(&timer->entry); 317 } 318 EXPORT_SYMBOL(init_virt_timer); 319 320 static inline int vtimer_pending(struct vtimer_list *timer) 321 { 322 return !list_empty(&timer->entry); 323 } 324 325 static void internal_add_vtimer(struct vtimer_list *timer) 326 { 327 if (list_empty(&virt_timer_list)) { 328 /* First timer, just program it. */ 329 atomic64_set(&virt_timer_current, timer->expires); 330 atomic64_set(&virt_timer_elapsed, 0); 331 list_add(&timer->entry, &virt_timer_list); 332 } else { 333 /* Update timer against current base. */ 334 timer->expires += atomic64_read(&virt_timer_elapsed); 335 if (likely((s64) timer->expires < 336 (s64) atomic64_read(&virt_timer_current))) 337 /* The new timer expires before the current timer. */ 338 atomic64_set(&virt_timer_current, timer->expires); 339 /* Insert new timer into the list. */ 340 list_add_sorted(timer, &virt_timer_list); 341 } 342 } 343 344 static void __add_vtimer(struct vtimer_list *timer, int periodic) 345 { 346 unsigned long flags; 347 348 timer->interval = periodic ? timer->expires : 0; 349 spin_lock_irqsave(&virt_timer_lock, flags); 350 internal_add_vtimer(timer); 351 spin_unlock_irqrestore(&virt_timer_lock, flags); 352 } 353 354 /* 355 * add_virt_timer - add a oneshot virtual CPU timer 356 */ 357 void add_virt_timer(struct vtimer_list *timer) 358 { 359 __add_vtimer(timer, 0); 360 } 361 EXPORT_SYMBOL(add_virt_timer); 362 363 /* 364 * add_virt_timer_int - add an interval virtual CPU timer 365 */ 366 void add_virt_timer_periodic(struct vtimer_list *timer) 367 { 368 __add_vtimer(timer, 1); 369 } 370 EXPORT_SYMBOL(add_virt_timer_periodic); 371 372 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 373 { 374 unsigned long flags; 375 int rc; 376 377 BUG_ON(!timer->function); 378 379 if (timer->expires == expires && vtimer_pending(timer)) 380 return 1; 381 spin_lock_irqsave(&virt_timer_lock, flags); 382 rc = vtimer_pending(timer); 383 if (rc) 384 list_del_init(&timer->entry); 385 timer->interval = periodic ? expires : 0; 386 timer->expires = expires; 387 internal_add_vtimer(timer); 388 spin_unlock_irqrestore(&virt_timer_lock, flags); 389 return rc; 390 } 391 392 /* 393 * returns whether it has modified a pending timer (1) or not (0) 394 */ 395 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 396 { 397 return __mod_vtimer(timer, expires, 0); 398 } 399 EXPORT_SYMBOL(mod_virt_timer); 400 401 /* 402 * returns whether it has modified a pending timer (1) or not (0) 403 */ 404 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 405 { 406 return __mod_vtimer(timer, expires, 1); 407 } 408 EXPORT_SYMBOL(mod_virt_timer_periodic); 409 410 /* 411 * Delete a virtual timer. 412 * 413 * returns whether the deleted timer was pending (1) or not (0) 414 */ 415 int del_virt_timer(struct vtimer_list *timer) 416 { 417 unsigned long flags; 418 419 if (!vtimer_pending(timer)) 420 return 0; 421 spin_lock_irqsave(&virt_timer_lock, flags); 422 list_del_init(&timer->entry); 423 spin_unlock_irqrestore(&virt_timer_lock, flags); 424 return 1; 425 } 426 EXPORT_SYMBOL(del_virt_timer); 427 428 /* 429 * Start the virtual CPU timer on the current CPU. 430 */ 431 void vtime_init(void) 432 { 433 /* set initial cpu timer */ 434 set_vtimer(VTIMER_MAX_SLICE); 435 /* Setup initial MT scaling values */ 436 if (smp_cpu_mtid) { 437 __this_cpu_write(mt_scaling_jiffies, jiffies); 438 __this_cpu_write(mt_scaling_mult, 1); 439 __this_cpu_write(mt_scaling_div, 1); 440 stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 441 } 442 } 443