1 /* 2 * Virtual cpu timer based timer functions. 3 * 4 * Copyright IBM Corp. 2004, 2012 5 * Author(s): Jan Glauber <jan.glauber@de.ibm.com> 6 */ 7 8 #include <linux/kernel_stat.h> 9 #include <linux/sched/cputime.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 16 #include <asm/vtimer.h> 17 #include <asm/vtime.h> 18 #include <asm/cpu_mf.h> 19 #include <asm/smp.h> 20 21 #include "entry.h" 22 23 static void virt_timer_expire(void); 24 25 static LIST_HEAD(virt_timer_list); 26 static DEFINE_SPINLOCK(virt_timer_lock); 27 static atomic64_t virt_timer_current; 28 static atomic64_t virt_timer_elapsed; 29 30 DEFINE_PER_CPU(u64, mt_cycles[8]); 31 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 }; 32 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 }; 33 static DEFINE_PER_CPU(u64, mt_scaling_jiffies); 34 35 static inline u64 get_vtimer(void) 36 { 37 u64 timer; 38 39 asm volatile("stpt %0" : "=m" (timer)); 40 return timer; 41 } 42 43 static inline void set_vtimer(u64 expires) 44 { 45 u64 timer; 46 47 asm volatile( 48 " stpt %0\n" /* Store current cpu timer value */ 49 " spt %1" /* Set new value imm. afterwards */ 50 : "=m" (timer) : "m" (expires)); 51 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer; 52 S390_lowcore.last_update_timer = expires; 53 } 54 55 static inline int virt_timer_forward(u64 elapsed) 56 { 57 BUG_ON(!irqs_disabled()); 58 59 if (list_empty(&virt_timer_list)) 60 return 0; 61 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed); 62 return elapsed >= atomic64_read(&virt_timer_current); 63 } 64 65 static void update_mt_scaling(void) 66 { 67 u64 cycles_new[8], *cycles_old; 68 u64 delta, fac, mult, div; 69 int i; 70 71 stcctm5(smp_cpu_mtid + 1, cycles_new); 72 cycles_old = this_cpu_ptr(mt_cycles); 73 fac = 1; 74 mult = div = 0; 75 for (i = 0; i <= smp_cpu_mtid; i++) { 76 delta = cycles_new[i] - cycles_old[i]; 77 div += delta; 78 mult *= i + 1; 79 mult += delta * fac; 80 fac *= i + 1; 81 } 82 div *= fac; 83 if (div > 0) { 84 /* Update scaling factor */ 85 __this_cpu_write(mt_scaling_mult, mult); 86 __this_cpu_write(mt_scaling_div, div); 87 memcpy(cycles_old, cycles_new, 88 sizeof(u64) * (smp_cpu_mtid + 1)); 89 } 90 __this_cpu_write(mt_scaling_jiffies, jiffies_64); 91 } 92 93 static inline u64 update_tsk_timer(unsigned long *tsk_vtime, u64 new) 94 { 95 u64 delta; 96 97 delta = new - *tsk_vtime; 98 *tsk_vtime = new; 99 return delta; 100 } 101 102 103 static inline u64 scale_vtime(u64 vtime) 104 { 105 u64 mult = __this_cpu_read(mt_scaling_mult); 106 u64 div = __this_cpu_read(mt_scaling_div); 107 108 if (smp_cpu_mtid) 109 return vtime * mult / div; 110 return vtime; 111 } 112 113 static void account_system_index_scaled(struct task_struct *p, 114 u64 cputime, u64 scaled, 115 enum cpu_usage_stat index) 116 { 117 p->stimescaled += cputime_to_nsecs(scaled); 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, scale_vtime(system), 180 CPUTIME_SYSTEM); 181 if (hardirq) 182 account_system_index_scaled(tsk, hardirq, scale_vtime(hardirq), 183 CPUTIME_IRQ); 184 if (softirq) 185 account_system_index_scaled(tsk, softirq, scale_vtime(softirq), 186 CPUTIME_SOFTIRQ); 187 188 steal = S390_lowcore.steal_timer; 189 if ((s64) steal > 0) { 190 S390_lowcore.steal_timer = 0; 191 account_steal_time(cputime_to_nsecs(steal)); 192 } 193 194 return virt_timer_forward(user + guest + system + hardirq + softirq); 195 } 196 197 void vtime_task_switch(struct task_struct *prev) 198 { 199 do_account_vtime(prev); 200 prev->thread.user_timer = S390_lowcore.user_timer; 201 prev->thread.guest_timer = S390_lowcore.guest_timer; 202 prev->thread.system_timer = S390_lowcore.system_timer; 203 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer; 204 prev->thread.softirq_timer = S390_lowcore.softirq_timer; 205 S390_lowcore.user_timer = current->thread.user_timer; 206 S390_lowcore.guest_timer = current->thread.guest_timer; 207 S390_lowcore.system_timer = current->thread.system_timer; 208 S390_lowcore.hardirq_timer = current->thread.hardirq_timer; 209 S390_lowcore.softirq_timer = current->thread.softirq_timer; 210 } 211 212 /* 213 * In s390, accounting pending user time also implies 214 * accounting system time in order to correctly compute 215 * the stolen time accounting. 216 */ 217 void vtime_flush(struct task_struct *tsk) 218 { 219 if (do_account_vtime(tsk)) 220 virt_timer_expire(); 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_irq_enter(struct task_struct *tsk) 228 { 229 u64 timer; 230 231 timer = S390_lowcore.last_update_timer; 232 S390_lowcore.last_update_timer = get_vtimer(); 233 timer -= S390_lowcore.last_update_timer; 234 235 if ((tsk->flags & PF_VCPU) && (irq_count() == 0)) 236 S390_lowcore.guest_timer += timer; 237 else if (hardirq_count()) 238 S390_lowcore.hardirq_timer += timer; 239 else if (in_serving_softirq()) 240 S390_lowcore.softirq_timer += timer; 241 else 242 S390_lowcore.system_timer += timer; 243 244 virt_timer_forward(timer); 245 } 246 EXPORT_SYMBOL_GPL(vtime_account_irq_enter); 247 248 void vtime_account_system(struct task_struct *tsk) 249 __attribute__((alias("vtime_account_irq_enter"))); 250 EXPORT_SYMBOL_GPL(vtime_account_system); 251 252 /* 253 * Sorted add to a list. List is linear searched until first bigger 254 * element is found. 255 */ 256 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 257 { 258 struct vtimer_list *tmp; 259 260 list_for_each_entry(tmp, head, entry) { 261 if (tmp->expires > timer->expires) { 262 list_add_tail(&timer->entry, &tmp->entry); 263 return; 264 } 265 } 266 list_add_tail(&timer->entry, head); 267 } 268 269 /* 270 * Handler for expired virtual CPU timer. 271 */ 272 static void virt_timer_expire(void) 273 { 274 struct vtimer_list *timer, *tmp; 275 unsigned long elapsed; 276 LIST_HEAD(cb_list); 277 278 /* walk timer list, fire all expired timers */ 279 spin_lock(&virt_timer_lock); 280 elapsed = atomic64_read(&virt_timer_elapsed); 281 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 282 if (timer->expires < elapsed) 283 /* move expired timer to the callback queue */ 284 list_move_tail(&timer->entry, &cb_list); 285 else 286 timer->expires -= elapsed; 287 } 288 if (!list_empty(&virt_timer_list)) { 289 timer = list_first_entry(&virt_timer_list, 290 struct vtimer_list, entry); 291 atomic64_set(&virt_timer_current, timer->expires); 292 } 293 atomic64_sub(elapsed, &virt_timer_elapsed); 294 spin_unlock(&virt_timer_lock); 295 296 /* Do callbacks and recharge periodic timers */ 297 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 298 list_del_init(&timer->entry); 299 timer->function(timer->data); 300 if (timer->interval) { 301 /* Recharge interval timer */ 302 timer->expires = timer->interval + 303 atomic64_read(&virt_timer_elapsed); 304 spin_lock(&virt_timer_lock); 305 list_add_sorted(timer, &virt_timer_list); 306 spin_unlock(&virt_timer_lock); 307 } 308 } 309 } 310 311 void init_virt_timer(struct vtimer_list *timer) 312 { 313 timer->function = NULL; 314 INIT_LIST_HEAD(&timer->entry); 315 } 316 EXPORT_SYMBOL(init_virt_timer); 317 318 static inline int vtimer_pending(struct vtimer_list *timer) 319 { 320 return !list_empty(&timer->entry); 321 } 322 323 static void internal_add_vtimer(struct vtimer_list *timer) 324 { 325 if (list_empty(&virt_timer_list)) { 326 /* First timer, just program it. */ 327 atomic64_set(&virt_timer_current, timer->expires); 328 atomic64_set(&virt_timer_elapsed, 0); 329 list_add(&timer->entry, &virt_timer_list); 330 } else { 331 /* Update timer against current base. */ 332 timer->expires += atomic64_read(&virt_timer_elapsed); 333 if (likely((s64) timer->expires < 334 (s64) atomic64_read(&virt_timer_current))) 335 /* The new timer expires before the current timer. */ 336 atomic64_set(&virt_timer_current, timer->expires); 337 /* Insert new timer into the list. */ 338 list_add_sorted(timer, &virt_timer_list); 339 } 340 } 341 342 static void __add_vtimer(struct vtimer_list *timer, int periodic) 343 { 344 unsigned long flags; 345 346 timer->interval = periodic ? timer->expires : 0; 347 spin_lock_irqsave(&virt_timer_lock, flags); 348 internal_add_vtimer(timer); 349 spin_unlock_irqrestore(&virt_timer_lock, flags); 350 } 351 352 /* 353 * add_virt_timer - add a oneshot virtual CPU timer 354 */ 355 void add_virt_timer(struct vtimer_list *timer) 356 { 357 __add_vtimer(timer, 0); 358 } 359 EXPORT_SYMBOL(add_virt_timer); 360 361 /* 362 * add_virt_timer_int - add an interval virtual CPU timer 363 */ 364 void add_virt_timer_periodic(struct vtimer_list *timer) 365 { 366 __add_vtimer(timer, 1); 367 } 368 EXPORT_SYMBOL(add_virt_timer_periodic); 369 370 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 371 { 372 unsigned long flags; 373 int rc; 374 375 BUG_ON(!timer->function); 376 377 if (timer->expires == expires && vtimer_pending(timer)) 378 return 1; 379 spin_lock_irqsave(&virt_timer_lock, flags); 380 rc = vtimer_pending(timer); 381 if (rc) 382 list_del_init(&timer->entry); 383 timer->interval = periodic ? expires : 0; 384 timer->expires = expires; 385 internal_add_vtimer(timer); 386 spin_unlock_irqrestore(&virt_timer_lock, flags); 387 return rc; 388 } 389 390 /* 391 * returns whether it has modified a pending timer (1) or not (0) 392 */ 393 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 394 { 395 return __mod_vtimer(timer, expires, 0); 396 } 397 EXPORT_SYMBOL(mod_virt_timer); 398 399 /* 400 * returns whether it has modified a pending timer (1) or not (0) 401 */ 402 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 403 { 404 return __mod_vtimer(timer, expires, 1); 405 } 406 EXPORT_SYMBOL(mod_virt_timer_periodic); 407 408 /* 409 * Delete a virtual timer. 410 * 411 * returns whether the deleted timer was pending (1) or not (0) 412 */ 413 int del_virt_timer(struct vtimer_list *timer) 414 { 415 unsigned long flags; 416 417 if (!vtimer_pending(timer)) 418 return 0; 419 spin_lock_irqsave(&virt_timer_lock, flags); 420 list_del_init(&timer->entry); 421 spin_unlock_irqrestore(&virt_timer_lock, flags); 422 return 1; 423 } 424 EXPORT_SYMBOL(del_virt_timer); 425 426 /* 427 * Start the virtual CPU timer on the current CPU. 428 */ 429 void vtime_init(void) 430 { 431 /* set initial cpu timer */ 432 set_vtimer(VTIMER_MAX_SLICE); 433 /* Setup initial MT scaling values */ 434 if (smp_cpu_mtid) { 435 __this_cpu_write(mt_scaling_jiffies, jiffies); 436 __this_cpu_write(mt_scaling_mult, 1); 437 __this_cpu_write(mt_scaling_div, 1); 438 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 439 } 440 } 441