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