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 /* Use STORE CLOCK by default, STORE CLOCK FAST if available. */ 132 alternative_io("stpt %0\n .insn s,0xb2050000,%1\n", 133 "stpt %0\n .insn s,0xb27c0000,%1\n", 134 25, 135 ASM_OUTPUT2("=Q" (S390_lowcore.last_update_timer), 136 "=Q" (S390_lowcore.last_update_clock)), 137 ASM_NO_INPUT_CLOBBER("cc")); 138 clock = S390_lowcore.last_update_clock - clock; 139 timer -= S390_lowcore.last_update_timer; 140 141 if (hardirq_count()) 142 S390_lowcore.hardirq_timer += timer; 143 else 144 S390_lowcore.system_timer += timer; 145 146 /* Update MT utilization calculation */ 147 if (smp_cpu_mtid && 148 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 149 update_mt_scaling(); 150 151 /* Calculate cputime delta */ 152 user = update_tsk_timer(&tsk->thread.user_timer, 153 READ_ONCE(S390_lowcore.user_timer)); 154 guest = update_tsk_timer(&tsk->thread.guest_timer, 155 READ_ONCE(S390_lowcore.guest_timer)); 156 system = update_tsk_timer(&tsk->thread.system_timer, 157 READ_ONCE(S390_lowcore.system_timer)); 158 hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, 159 READ_ONCE(S390_lowcore.hardirq_timer)); 160 softirq = update_tsk_timer(&tsk->thread.softirq_timer, 161 READ_ONCE(S390_lowcore.softirq_timer)); 162 S390_lowcore.steal_timer += 163 clock - user - guest - system - hardirq - softirq; 164 165 /* Push account value */ 166 if (user) { 167 account_user_time(tsk, cputime_to_nsecs(user)); 168 tsk->utimescaled += cputime_to_nsecs(scale_vtime(user)); 169 } 170 171 if (guest) { 172 account_guest_time(tsk, cputime_to_nsecs(guest)); 173 tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest)); 174 } 175 176 if (system) 177 account_system_index_scaled(tsk, system, CPUTIME_SYSTEM); 178 if (hardirq) 179 account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ); 180 if (softirq) 181 account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ); 182 183 return virt_timer_forward(user + guest + system + hardirq + softirq); 184 } 185 186 void vtime_task_switch(struct task_struct *prev) 187 { 188 do_account_vtime(prev); 189 prev->thread.user_timer = S390_lowcore.user_timer; 190 prev->thread.guest_timer = S390_lowcore.guest_timer; 191 prev->thread.system_timer = S390_lowcore.system_timer; 192 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer; 193 prev->thread.softirq_timer = S390_lowcore.softirq_timer; 194 S390_lowcore.user_timer = current->thread.user_timer; 195 S390_lowcore.guest_timer = current->thread.guest_timer; 196 S390_lowcore.system_timer = current->thread.system_timer; 197 S390_lowcore.hardirq_timer = current->thread.hardirq_timer; 198 S390_lowcore.softirq_timer = current->thread.softirq_timer; 199 } 200 201 /* 202 * In s390, accounting pending user time also implies 203 * accounting system time in order to correctly compute 204 * the stolen time accounting. 205 */ 206 void vtime_flush(struct task_struct *tsk) 207 { 208 u64 steal, avg_steal; 209 210 if (do_account_vtime(tsk)) 211 virt_timer_expire(); 212 213 steal = S390_lowcore.steal_timer; 214 avg_steal = S390_lowcore.avg_steal_timer / 2; 215 if ((s64) steal > 0) { 216 S390_lowcore.steal_timer = 0; 217 account_steal_time(steal); 218 avg_steal += steal; 219 } 220 S390_lowcore.avg_steal_timer = avg_steal; 221 } 222 223 static u64 vtime_delta(void) 224 { 225 u64 timer = S390_lowcore.last_update_timer; 226 227 S390_lowcore.last_update_timer = get_vtimer(); 228 229 return timer - S390_lowcore.last_update_timer; 230 } 231 232 /* 233 * Update process times based on virtual cpu times stored by entry.S 234 * to the lowcore fields user_timer, system_timer & steal_clock. 235 */ 236 void vtime_account_kernel(struct task_struct *tsk) 237 { 238 u64 delta = vtime_delta(); 239 240 if (tsk->flags & PF_VCPU) 241 S390_lowcore.guest_timer += delta; 242 else 243 S390_lowcore.system_timer += delta; 244 245 virt_timer_forward(delta); 246 } 247 EXPORT_SYMBOL_GPL(vtime_account_kernel); 248 249 void vtime_account_softirq(struct task_struct *tsk) 250 { 251 u64 delta = vtime_delta(); 252 253 S390_lowcore.softirq_timer += delta; 254 255 virt_timer_forward(delta); 256 } 257 258 void vtime_account_hardirq(struct task_struct *tsk) 259 { 260 u64 delta = vtime_delta(); 261 262 S390_lowcore.hardirq_timer += delta; 263 264 virt_timer_forward(delta); 265 } 266 267 /* 268 * Sorted add to a list. List is linear searched until first bigger 269 * element is found. 270 */ 271 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 272 { 273 struct vtimer_list *tmp; 274 275 list_for_each_entry(tmp, head, entry) { 276 if (tmp->expires > timer->expires) { 277 list_add_tail(&timer->entry, &tmp->entry); 278 return; 279 } 280 } 281 list_add_tail(&timer->entry, head); 282 } 283 284 /* 285 * Handler for expired virtual CPU timer. 286 */ 287 static void virt_timer_expire(void) 288 { 289 struct vtimer_list *timer, *tmp; 290 unsigned long elapsed; 291 LIST_HEAD(cb_list); 292 293 /* walk timer list, fire all expired timers */ 294 spin_lock(&virt_timer_lock); 295 elapsed = atomic64_read(&virt_timer_elapsed); 296 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 297 if (timer->expires < elapsed) 298 /* move expired timer to the callback queue */ 299 list_move_tail(&timer->entry, &cb_list); 300 else 301 timer->expires -= elapsed; 302 } 303 if (!list_empty(&virt_timer_list)) { 304 timer = list_first_entry(&virt_timer_list, 305 struct vtimer_list, entry); 306 atomic64_set(&virt_timer_current, timer->expires); 307 } 308 atomic64_sub(elapsed, &virt_timer_elapsed); 309 spin_unlock(&virt_timer_lock); 310 311 /* Do callbacks and recharge periodic timers */ 312 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 313 list_del_init(&timer->entry); 314 timer->function(timer->data); 315 if (timer->interval) { 316 /* Recharge interval timer */ 317 timer->expires = timer->interval + 318 atomic64_read(&virt_timer_elapsed); 319 spin_lock(&virt_timer_lock); 320 list_add_sorted(timer, &virt_timer_list); 321 spin_unlock(&virt_timer_lock); 322 } 323 } 324 } 325 326 void init_virt_timer(struct vtimer_list *timer) 327 { 328 timer->function = NULL; 329 INIT_LIST_HEAD(&timer->entry); 330 } 331 EXPORT_SYMBOL(init_virt_timer); 332 333 static inline int vtimer_pending(struct vtimer_list *timer) 334 { 335 return !list_empty(&timer->entry); 336 } 337 338 static void internal_add_vtimer(struct vtimer_list *timer) 339 { 340 if (list_empty(&virt_timer_list)) { 341 /* First timer, just program it. */ 342 atomic64_set(&virt_timer_current, timer->expires); 343 atomic64_set(&virt_timer_elapsed, 0); 344 list_add(&timer->entry, &virt_timer_list); 345 } else { 346 /* Update timer against current base. */ 347 timer->expires += atomic64_read(&virt_timer_elapsed); 348 if (likely((s64) timer->expires < 349 (s64) atomic64_read(&virt_timer_current))) 350 /* The new timer expires before the current timer. */ 351 atomic64_set(&virt_timer_current, timer->expires); 352 /* Insert new timer into the list. */ 353 list_add_sorted(timer, &virt_timer_list); 354 } 355 } 356 357 static void __add_vtimer(struct vtimer_list *timer, int periodic) 358 { 359 unsigned long flags; 360 361 timer->interval = periodic ? timer->expires : 0; 362 spin_lock_irqsave(&virt_timer_lock, flags); 363 internal_add_vtimer(timer); 364 spin_unlock_irqrestore(&virt_timer_lock, flags); 365 } 366 367 /* 368 * add_virt_timer - add a oneshot virtual CPU timer 369 */ 370 void add_virt_timer(struct vtimer_list *timer) 371 { 372 __add_vtimer(timer, 0); 373 } 374 EXPORT_SYMBOL(add_virt_timer); 375 376 /* 377 * add_virt_timer_int - add an interval virtual CPU timer 378 */ 379 void add_virt_timer_periodic(struct vtimer_list *timer) 380 { 381 __add_vtimer(timer, 1); 382 } 383 EXPORT_SYMBOL(add_virt_timer_periodic); 384 385 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 386 { 387 unsigned long flags; 388 int rc; 389 390 BUG_ON(!timer->function); 391 392 if (timer->expires == expires && vtimer_pending(timer)) 393 return 1; 394 spin_lock_irqsave(&virt_timer_lock, flags); 395 rc = vtimer_pending(timer); 396 if (rc) 397 list_del_init(&timer->entry); 398 timer->interval = periodic ? expires : 0; 399 timer->expires = expires; 400 internal_add_vtimer(timer); 401 spin_unlock_irqrestore(&virt_timer_lock, flags); 402 return rc; 403 } 404 405 /* 406 * returns whether it has modified a pending timer (1) or not (0) 407 */ 408 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 409 { 410 return __mod_vtimer(timer, expires, 0); 411 } 412 EXPORT_SYMBOL(mod_virt_timer); 413 414 /* 415 * returns whether it has modified a pending timer (1) or not (0) 416 */ 417 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 418 { 419 return __mod_vtimer(timer, expires, 1); 420 } 421 EXPORT_SYMBOL(mod_virt_timer_periodic); 422 423 /* 424 * Delete a virtual timer. 425 * 426 * returns whether the deleted timer was pending (1) or not (0) 427 */ 428 int del_virt_timer(struct vtimer_list *timer) 429 { 430 unsigned long flags; 431 432 if (!vtimer_pending(timer)) 433 return 0; 434 spin_lock_irqsave(&virt_timer_lock, flags); 435 list_del_init(&timer->entry); 436 spin_unlock_irqrestore(&virt_timer_lock, flags); 437 return 1; 438 } 439 EXPORT_SYMBOL(del_virt_timer); 440 441 /* 442 * Start the virtual CPU timer on the current CPU. 443 */ 444 void vtime_init(void) 445 { 446 /* set initial cpu timer */ 447 set_vtimer(VTIMER_MAX_SLICE); 448 /* Setup initial MT scaling values */ 449 if (smp_cpu_mtid) { 450 __this_cpu_write(mt_scaling_jiffies, jiffies); 451 __this_cpu_write(mt_scaling_mult, 1); 452 __this_cpu_write(mt_scaling_div, 1); 453 stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 454 } 455 } 456