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 stcctm5(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, steal; 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 steal = S390_lowcore.steal_timer; 186 if ((s64) steal > 0) { 187 S390_lowcore.steal_timer = 0; 188 account_steal_time(cputime_to_nsecs(steal)); 189 } 190 191 return virt_timer_forward(user + guest + system + hardirq + softirq); 192 } 193 194 void vtime_task_switch(struct task_struct *prev) 195 { 196 do_account_vtime(prev); 197 prev->thread.user_timer = S390_lowcore.user_timer; 198 prev->thread.guest_timer = S390_lowcore.guest_timer; 199 prev->thread.system_timer = S390_lowcore.system_timer; 200 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer; 201 prev->thread.softirq_timer = S390_lowcore.softirq_timer; 202 S390_lowcore.user_timer = current->thread.user_timer; 203 S390_lowcore.guest_timer = current->thread.guest_timer; 204 S390_lowcore.system_timer = current->thread.system_timer; 205 S390_lowcore.hardirq_timer = current->thread.hardirq_timer; 206 S390_lowcore.softirq_timer = current->thread.softirq_timer; 207 } 208 209 /* 210 * In s390, accounting pending user time also implies 211 * accounting system time in order to correctly compute 212 * the stolen time accounting. 213 */ 214 void vtime_flush(struct task_struct *tsk) 215 { 216 if (do_account_vtime(tsk)) 217 virt_timer_expire(); 218 } 219 220 /* 221 * Update process times based on virtual cpu times stored by entry.S 222 * to the lowcore fields user_timer, system_timer & steal_clock. 223 */ 224 void vtime_account_irq_enter(struct task_struct *tsk) 225 { 226 u64 timer; 227 228 timer = S390_lowcore.last_update_timer; 229 S390_lowcore.last_update_timer = get_vtimer(); 230 timer -= S390_lowcore.last_update_timer; 231 232 if ((tsk->flags & PF_VCPU) && (irq_count() == 0)) 233 S390_lowcore.guest_timer += timer; 234 else if (hardirq_count()) 235 S390_lowcore.hardirq_timer += timer; 236 else if (in_serving_softirq()) 237 S390_lowcore.softirq_timer += timer; 238 else 239 S390_lowcore.system_timer += timer; 240 241 virt_timer_forward(timer); 242 } 243 EXPORT_SYMBOL_GPL(vtime_account_irq_enter); 244 245 void vtime_account_system(struct task_struct *tsk) 246 __attribute__((alias("vtime_account_irq_enter"))); 247 EXPORT_SYMBOL_GPL(vtime_account_system); 248 249 /* 250 * Sorted add to a list. List is linear searched until first bigger 251 * element is found. 252 */ 253 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 254 { 255 struct vtimer_list *tmp; 256 257 list_for_each_entry(tmp, head, entry) { 258 if (tmp->expires > timer->expires) { 259 list_add_tail(&timer->entry, &tmp->entry); 260 return; 261 } 262 } 263 list_add_tail(&timer->entry, head); 264 } 265 266 /* 267 * Handler for expired virtual CPU timer. 268 */ 269 static void virt_timer_expire(void) 270 { 271 struct vtimer_list *timer, *tmp; 272 unsigned long elapsed; 273 LIST_HEAD(cb_list); 274 275 /* walk timer list, fire all expired timers */ 276 spin_lock(&virt_timer_lock); 277 elapsed = atomic64_read(&virt_timer_elapsed); 278 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 279 if (timer->expires < elapsed) 280 /* move expired timer to the callback queue */ 281 list_move_tail(&timer->entry, &cb_list); 282 else 283 timer->expires -= elapsed; 284 } 285 if (!list_empty(&virt_timer_list)) { 286 timer = list_first_entry(&virt_timer_list, 287 struct vtimer_list, entry); 288 atomic64_set(&virt_timer_current, timer->expires); 289 } 290 atomic64_sub(elapsed, &virt_timer_elapsed); 291 spin_unlock(&virt_timer_lock); 292 293 /* Do callbacks and recharge periodic timers */ 294 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 295 list_del_init(&timer->entry); 296 timer->function(timer->data); 297 if (timer->interval) { 298 /* Recharge interval timer */ 299 timer->expires = timer->interval + 300 atomic64_read(&virt_timer_elapsed); 301 spin_lock(&virt_timer_lock); 302 list_add_sorted(timer, &virt_timer_list); 303 spin_unlock(&virt_timer_lock); 304 } 305 } 306 } 307 308 void init_virt_timer(struct vtimer_list *timer) 309 { 310 timer->function = NULL; 311 INIT_LIST_HEAD(&timer->entry); 312 } 313 EXPORT_SYMBOL(init_virt_timer); 314 315 static inline int vtimer_pending(struct vtimer_list *timer) 316 { 317 return !list_empty(&timer->entry); 318 } 319 320 static void internal_add_vtimer(struct vtimer_list *timer) 321 { 322 if (list_empty(&virt_timer_list)) { 323 /* First timer, just program it. */ 324 atomic64_set(&virt_timer_current, timer->expires); 325 atomic64_set(&virt_timer_elapsed, 0); 326 list_add(&timer->entry, &virt_timer_list); 327 } else { 328 /* Update timer against current base. */ 329 timer->expires += atomic64_read(&virt_timer_elapsed); 330 if (likely((s64) timer->expires < 331 (s64) atomic64_read(&virt_timer_current))) 332 /* The new timer expires before the current timer. */ 333 atomic64_set(&virt_timer_current, timer->expires); 334 /* Insert new timer into the list. */ 335 list_add_sorted(timer, &virt_timer_list); 336 } 337 } 338 339 static void __add_vtimer(struct vtimer_list *timer, int periodic) 340 { 341 unsigned long flags; 342 343 timer->interval = periodic ? timer->expires : 0; 344 spin_lock_irqsave(&virt_timer_lock, flags); 345 internal_add_vtimer(timer); 346 spin_unlock_irqrestore(&virt_timer_lock, flags); 347 } 348 349 /* 350 * add_virt_timer - add a oneshot virtual CPU timer 351 */ 352 void add_virt_timer(struct vtimer_list *timer) 353 { 354 __add_vtimer(timer, 0); 355 } 356 EXPORT_SYMBOL(add_virt_timer); 357 358 /* 359 * add_virt_timer_int - add an interval virtual CPU timer 360 */ 361 void add_virt_timer_periodic(struct vtimer_list *timer) 362 { 363 __add_vtimer(timer, 1); 364 } 365 EXPORT_SYMBOL(add_virt_timer_periodic); 366 367 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 368 { 369 unsigned long flags; 370 int rc; 371 372 BUG_ON(!timer->function); 373 374 if (timer->expires == expires && vtimer_pending(timer)) 375 return 1; 376 spin_lock_irqsave(&virt_timer_lock, flags); 377 rc = vtimer_pending(timer); 378 if (rc) 379 list_del_init(&timer->entry); 380 timer->interval = periodic ? expires : 0; 381 timer->expires = expires; 382 internal_add_vtimer(timer); 383 spin_unlock_irqrestore(&virt_timer_lock, flags); 384 return rc; 385 } 386 387 /* 388 * returns whether it has modified a pending timer (1) or not (0) 389 */ 390 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 391 { 392 return __mod_vtimer(timer, expires, 0); 393 } 394 EXPORT_SYMBOL(mod_virt_timer); 395 396 /* 397 * returns whether it has modified a pending timer (1) or not (0) 398 */ 399 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 400 { 401 return __mod_vtimer(timer, expires, 1); 402 } 403 EXPORT_SYMBOL(mod_virt_timer_periodic); 404 405 /* 406 * Delete a virtual timer. 407 * 408 * returns whether the deleted timer was pending (1) or not (0) 409 */ 410 int del_virt_timer(struct vtimer_list *timer) 411 { 412 unsigned long flags; 413 414 if (!vtimer_pending(timer)) 415 return 0; 416 spin_lock_irqsave(&virt_timer_lock, flags); 417 list_del_init(&timer->entry); 418 spin_unlock_irqrestore(&virt_timer_lock, flags); 419 return 1; 420 } 421 EXPORT_SYMBOL(del_virt_timer); 422 423 /* 424 * Start the virtual CPU timer on the current CPU. 425 */ 426 void vtime_init(void) 427 { 428 /* set initial cpu timer */ 429 set_vtimer(VTIMER_MAX_SLICE); 430 /* Setup initial MT scaling values */ 431 if (smp_cpu_mtid) { 432 __this_cpu_write(mt_scaling_jiffies, jiffies); 433 __this_cpu_write(mt_scaling_mult, 1); 434 __this_cpu_write(mt_scaling_div, 1); 435 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 436 } 437 } 438