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, u64 cputime, 114 enum cpu_usage_stat index) 115 { 116 p->stimescaled += cputime_to_nsecs(scale_vtime(cputime)); 117 account_system_index_time(p, cputime_to_nsecs(cputime), index); 118 } 119 120 /* 121 * Update process times based on virtual cpu times stored by entry.S 122 * to the lowcore fields user_timer, system_timer & steal_clock. 123 */ 124 static int do_account_vtime(struct task_struct *tsk) 125 { 126 u64 timer, clock, user, guest, system, hardirq, softirq, steal; 127 128 timer = S390_lowcore.last_update_timer; 129 clock = S390_lowcore.last_update_clock; 130 asm volatile( 131 " stpt %0\n" /* Store current cpu timer value */ 132 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES 133 " stckf %1" /* Store current tod clock value */ 134 #else 135 " stck %1" /* Store current tod clock value */ 136 #endif 137 : "=m" (S390_lowcore.last_update_timer), 138 "=m" (S390_lowcore.last_update_clock)); 139 clock = S390_lowcore.last_update_clock - clock; 140 timer -= S390_lowcore.last_update_timer; 141 142 if (hardirq_count()) 143 S390_lowcore.hardirq_timer += timer; 144 else 145 S390_lowcore.system_timer += timer; 146 147 /* Update MT utilization calculation */ 148 if (smp_cpu_mtid && 149 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 150 update_mt_scaling(); 151 152 /* Calculate cputime delta */ 153 user = update_tsk_timer(&tsk->thread.user_timer, 154 READ_ONCE(S390_lowcore.user_timer)); 155 guest = update_tsk_timer(&tsk->thread.guest_timer, 156 READ_ONCE(S390_lowcore.guest_timer)); 157 system = update_tsk_timer(&tsk->thread.system_timer, 158 READ_ONCE(S390_lowcore.system_timer)); 159 hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, 160 READ_ONCE(S390_lowcore.hardirq_timer)); 161 softirq = update_tsk_timer(&tsk->thread.softirq_timer, 162 READ_ONCE(S390_lowcore.softirq_timer)); 163 S390_lowcore.steal_timer += 164 clock - user - guest - system - hardirq - softirq; 165 166 /* Push account value */ 167 if (user) { 168 account_user_time(tsk, cputime_to_nsecs(user)); 169 tsk->utimescaled += cputime_to_nsecs(scale_vtime(user)); 170 } 171 172 if (guest) { 173 account_guest_time(tsk, cputime_to_nsecs(guest)); 174 tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest)); 175 } 176 177 if (system) 178 account_system_index_scaled(tsk, system, CPUTIME_SYSTEM); 179 if (hardirq) 180 account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ); 181 if (softirq) 182 account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ); 183 184 steal = S390_lowcore.steal_timer; 185 if ((s64) steal > 0) { 186 S390_lowcore.steal_timer = 0; 187 account_steal_time(cputime_to_nsecs(steal)); 188 } 189 190 return virt_timer_forward(user + guest + system + hardirq + softirq); 191 } 192 193 void vtime_task_switch(struct task_struct *prev) 194 { 195 do_account_vtime(prev); 196 prev->thread.user_timer = S390_lowcore.user_timer; 197 prev->thread.guest_timer = S390_lowcore.guest_timer; 198 prev->thread.system_timer = S390_lowcore.system_timer; 199 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer; 200 prev->thread.softirq_timer = S390_lowcore.softirq_timer; 201 S390_lowcore.user_timer = current->thread.user_timer; 202 S390_lowcore.guest_timer = current->thread.guest_timer; 203 S390_lowcore.system_timer = current->thread.system_timer; 204 S390_lowcore.hardirq_timer = current->thread.hardirq_timer; 205 S390_lowcore.softirq_timer = current->thread.softirq_timer; 206 } 207 208 /* 209 * In s390, accounting pending user time also implies 210 * accounting system time in order to correctly compute 211 * the stolen time accounting. 212 */ 213 void vtime_flush(struct task_struct *tsk) 214 { 215 if (do_account_vtime(tsk)) 216 virt_timer_expire(); 217 } 218 219 /* 220 * Update process times based on virtual cpu times stored by entry.S 221 * to the lowcore fields user_timer, system_timer & steal_clock. 222 */ 223 void vtime_account_irq_enter(struct task_struct *tsk) 224 { 225 u64 timer; 226 227 timer = S390_lowcore.last_update_timer; 228 S390_lowcore.last_update_timer = get_vtimer(); 229 timer -= S390_lowcore.last_update_timer; 230 231 if ((tsk->flags & PF_VCPU) && (irq_count() == 0)) 232 S390_lowcore.guest_timer += timer; 233 else if (hardirq_count()) 234 S390_lowcore.hardirq_timer += timer; 235 else if (in_serving_softirq()) 236 S390_lowcore.softirq_timer += timer; 237 else 238 S390_lowcore.system_timer += timer; 239 240 virt_timer_forward(timer); 241 } 242 EXPORT_SYMBOL_GPL(vtime_account_irq_enter); 243 244 void vtime_account_system(struct task_struct *tsk) 245 __attribute__((alias("vtime_account_irq_enter"))); 246 EXPORT_SYMBOL_GPL(vtime_account_system); 247 248 /* 249 * Sorted add to a list. List is linear searched until first bigger 250 * element is found. 251 */ 252 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 253 { 254 struct vtimer_list *tmp; 255 256 list_for_each_entry(tmp, head, entry) { 257 if (tmp->expires > timer->expires) { 258 list_add_tail(&timer->entry, &tmp->entry); 259 return; 260 } 261 } 262 list_add_tail(&timer->entry, head); 263 } 264 265 /* 266 * Handler for expired virtual CPU timer. 267 */ 268 static void virt_timer_expire(void) 269 { 270 struct vtimer_list *timer, *tmp; 271 unsigned long elapsed; 272 LIST_HEAD(cb_list); 273 274 /* walk timer list, fire all expired timers */ 275 spin_lock(&virt_timer_lock); 276 elapsed = atomic64_read(&virt_timer_elapsed); 277 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 278 if (timer->expires < elapsed) 279 /* move expired timer to the callback queue */ 280 list_move_tail(&timer->entry, &cb_list); 281 else 282 timer->expires -= elapsed; 283 } 284 if (!list_empty(&virt_timer_list)) { 285 timer = list_first_entry(&virt_timer_list, 286 struct vtimer_list, entry); 287 atomic64_set(&virt_timer_current, timer->expires); 288 } 289 atomic64_sub(elapsed, &virt_timer_elapsed); 290 spin_unlock(&virt_timer_lock); 291 292 /* Do callbacks and recharge periodic timers */ 293 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 294 list_del_init(&timer->entry); 295 timer->function(timer->data); 296 if (timer->interval) { 297 /* Recharge interval timer */ 298 timer->expires = timer->interval + 299 atomic64_read(&virt_timer_elapsed); 300 spin_lock(&virt_timer_lock); 301 list_add_sorted(timer, &virt_timer_list); 302 spin_unlock(&virt_timer_lock); 303 } 304 } 305 } 306 307 void init_virt_timer(struct vtimer_list *timer) 308 { 309 timer->function = NULL; 310 INIT_LIST_HEAD(&timer->entry); 311 } 312 EXPORT_SYMBOL(init_virt_timer); 313 314 static inline int vtimer_pending(struct vtimer_list *timer) 315 { 316 return !list_empty(&timer->entry); 317 } 318 319 static void internal_add_vtimer(struct vtimer_list *timer) 320 { 321 if (list_empty(&virt_timer_list)) { 322 /* First timer, just program it. */ 323 atomic64_set(&virt_timer_current, timer->expires); 324 atomic64_set(&virt_timer_elapsed, 0); 325 list_add(&timer->entry, &virt_timer_list); 326 } else { 327 /* Update timer against current base. */ 328 timer->expires += atomic64_read(&virt_timer_elapsed); 329 if (likely((s64) timer->expires < 330 (s64) atomic64_read(&virt_timer_current))) 331 /* The new timer expires before the current timer. */ 332 atomic64_set(&virt_timer_current, timer->expires); 333 /* Insert new timer into the list. */ 334 list_add_sorted(timer, &virt_timer_list); 335 } 336 } 337 338 static void __add_vtimer(struct vtimer_list *timer, int periodic) 339 { 340 unsigned long flags; 341 342 timer->interval = periodic ? timer->expires : 0; 343 spin_lock_irqsave(&virt_timer_lock, flags); 344 internal_add_vtimer(timer); 345 spin_unlock_irqrestore(&virt_timer_lock, flags); 346 } 347 348 /* 349 * add_virt_timer - add a oneshot virtual CPU timer 350 */ 351 void add_virt_timer(struct vtimer_list *timer) 352 { 353 __add_vtimer(timer, 0); 354 } 355 EXPORT_SYMBOL(add_virt_timer); 356 357 /* 358 * add_virt_timer_int - add an interval virtual CPU timer 359 */ 360 void add_virt_timer_periodic(struct vtimer_list *timer) 361 { 362 __add_vtimer(timer, 1); 363 } 364 EXPORT_SYMBOL(add_virt_timer_periodic); 365 366 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 367 { 368 unsigned long flags; 369 int rc; 370 371 BUG_ON(!timer->function); 372 373 if (timer->expires == expires && vtimer_pending(timer)) 374 return 1; 375 spin_lock_irqsave(&virt_timer_lock, flags); 376 rc = vtimer_pending(timer); 377 if (rc) 378 list_del_init(&timer->entry); 379 timer->interval = periodic ? expires : 0; 380 timer->expires = expires; 381 internal_add_vtimer(timer); 382 spin_unlock_irqrestore(&virt_timer_lock, flags); 383 return rc; 384 } 385 386 /* 387 * returns whether it has modified a pending timer (1) or not (0) 388 */ 389 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 390 { 391 return __mod_vtimer(timer, expires, 0); 392 } 393 EXPORT_SYMBOL(mod_virt_timer); 394 395 /* 396 * returns whether it has modified a pending timer (1) or not (0) 397 */ 398 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 399 { 400 return __mod_vtimer(timer, expires, 1); 401 } 402 EXPORT_SYMBOL(mod_virt_timer_periodic); 403 404 /* 405 * Delete a virtual timer. 406 * 407 * returns whether the deleted timer was pending (1) or not (0) 408 */ 409 int del_virt_timer(struct vtimer_list *timer) 410 { 411 unsigned long flags; 412 413 if (!vtimer_pending(timer)) 414 return 0; 415 spin_lock_irqsave(&virt_timer_lock, flags); 416 list_del_init(&timer->entry); 417 spin_unlock_irqrestore(&virt_timer_lock, flags); 418 return 1; 419 } 420 EXPORT_SYMBOL(del_virt_timer); 421 422 /* 423 * Start the virtual CPU timer on the current CPU. 424 */ 425 void vtime_init(void) 426 { 427 /* set initial cpu timer */ 428 set_vtimer(VTIMER_MAX_SLICE); 429 /* Setup initial MT scaling values */ 430 if (smp_cpu_mtid) { 431 __this_cpu_write(mt_scaling_jiffies, jiffies); 432 __this_cpu_write(mt_scaling_mult, 1); 433 __this_cpu_write(mt_scaling_div, 1); 434 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 435 } 436 } 437