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/export.h>
10 #include <linux/kernel.h>
11 #include <linux/timex.h>
12 #include <linux/types.h>
13 #include <linux/time.h>
14
15 #include <asm/cputime.h>
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
get_vtimer(void)35 static inline u64 get_vtimer(void)
36 {
37 u64 timer;
38
39 asm volatile("stpt %0" : "=m" (timer));
40 return timer;
41 }
42
set_vtimer(u64 expires)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
virt_timer_forward(u64 elapsed)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
update_mt_scaling(void)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 /*
94 * Update process times based on virtual cpu times stored by entry.S
95 * to the lowcore fields user_timer, system_timer & steal_clock.
96 */
do_account_vtime(struct task_struct * tsk,int hardirq_offset)97 static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
98 {
99 struct thread_info *ti = task_thread_info(tsk);
100 u64 timer, clock, user, system, steal;
101 u64 user_scaled, system_scaled;
102
103 timer = S390_lowcore.last_update_timer;
104 clock = S390_lowcore.last_update_clock;
105 asm volatile(
106 " stpt %0\n" /* Store current cpu timer value */
107 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
108 " stckf %1" /* Store current tod clock value */
109 #else
110 " stck %1" /* Store current tod clock value */
111 #endif
112 : "=m" (S390_lowcore.last_update_timer),
113 "=m" (S390_lowcore.last_update_clock));
114 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
115 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
116
117 /* Update MT utilization calculation */
118 if (smp_cpu_mtid &&
119 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
120 update_mt_scaling();
121
122 user = S390_lowcore.user_timer - ti->user_timer;
123 S390_lowcore.steal_timer -= user;
124 ti->user_timer = S390_lowcore.user_timer;
125
126 system = S390_lowcore.system_timer - ti->system_timer;
127 S390_lowcore.steal_timer -= system;
128 ti->system_timer = S390_lowcore.system_timer;
129
130 user_scaled = user;
131 system_scaled = system;
132 /* Do MT utilization scaling */
133 if (smp_cpu_mtid) {
134 u64 mult = __this_cpu_read(mt_scaling_mult);
135 u64 div = __this_cpu_read(mt_scaling_div);
136
137 user_scaled = (user_scaled * mult) / div;
138 system_scaled = (system_scaled * mult) / div;
139 }
140 account_user_time(tsk, user, user_scaled);
141 account_system_time(tsk, hardirq_offset, system, system_scaled);
142
143 steal = S390_lowcore.steal_timer;
144 if ((s64) steal > 0) {
145 S390_lowcore.steal_timer = 0;
146 account_steal_time(steal);
147 }
148
149 return virt_timer_forward(user + system);
150 }
151
vtime_task_switch(struct task_struct * prev)152 void vtime_task_switch(struct task_struct *prev)
153 {
154 struct thread_info *ti;
155
156 do_account_vtime(prev, 0);
157 ti = task_thread_info(prev);
158 ti->user_timer = S390_lowcore.user_timer;
159 ti->system_timer = S390_lowcore.system_timer;
160 ti = task_thread_info(current);
161 S390_lowcore.user_timer = ti->user_timer;
162 S390_lowcore.system_timer = ti->system_timer;
163 }
164
165 /*
166 * In s390, accounting pending user time also implies
167 * accounting system time in order to correctly compute
168 * the stolen time accounting.
169 */
vtime_account_user(struct task_struct * tsk)170 void vtime_account_user(struct task_struct *tsk)
171 {
172 if (do_account_vtime(tsk, HARDIRQ_OFFSET))
173 virt_timer_expire();
174 }
175
176 /*
177 * Update process times based on virtual cpu times stored by entry.S
178 * to the lowcore fields user_timer, system_timer & steal_clock.
179 */
vtime_account_irq_enter(struct task_struct * tsk)180 void vtime_account_irq_enter(struct task_struct *tsk)
181 {
182 struct thread_info *ti = task_thread_info(tsk);
183 u64 timer, system, system_scaled;
184
185 timer = S390_lowcore.last_update_timer;
186 S390_lowcore.last_update_timer = get_vtimer();
187 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
188
189 /* Update MT utilization calculation */
190 if (smp_cpu_mtid &&
191 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
192 update_mt_scaling();
193
194 system = S390_lowcore.system_timer - ti->system_timer;
195 S390_lowcore.steal_timer -= system;
196 ti->system_timer = S390_lowcore.system_timer;
197 system_scaled = system;
198 /* Do MT utilization scaling */
199 if (smp_cpu_mtid) {
200 u64 mult = __this_cpu_read(mt_scaling_mult);
201 u64 div = __this_cpu_read(mt_scaling_div);
202
203 system_scaled = (system_scaled * mult) / div;
204 }
205 account_system_time(tsk, 0, system, system_scaled);
206
207 virt_timer_forward(system);
208 }
209 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
210
211 void vtime_account_system(struct task_struct *tsk)
212 __attribute__((alias("vtime_account_irq_enter")));
213 EXPORT_SYMBOL_GPL(vtime_account_system);
214
215 /*
216 * Sorted add to a list. List is linear searched until first bigger
217 * element is found.
218 */
list_add_sorted(struct vtimer_list * timer,struct list_head * head)219 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
220 {
221 struct vtimer_list *tmp;
222
223 list_for_each_entry(tmp, head, entry) {
224 if (tmp->expires > timer->expires) {
225 list_add_tail(&timer->entry, &tmp->entry);
226 return;
227 }
228 }
229 list_add_tail(&timer->entry, head);
230 }
231
232 /*
233 * Handler for expired virtual CPU timer.
234 */
virt_timer_expire(void)235 static void virt_timer_expire(void)
236 {
237 struct vtimer_list *timer, *tmp;
238 unsigned long elapsed;
239 LIST_HEAD(cb_list);
240
241 /* walk timer list, fire all expired timers */
242 spin_lock(&virt_timer_lock);
243 elapsed = atomic64_read(&virt_timer_elapsed);
244 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
245 if (timer->expires < elapsed)
246 /* move expired timer to the callback queue */
247 list_move_tail(&timer->entry, &cb_list);
248 else
249 timer->expires -= elapsed;
250 }
251 if (!list_empty(&virt_timer_list)) {
252 timer = list_first_entry(&virt_timer_list,
253 struct vtimer_list, entry);
254 atomic64_set(&virt_timer_current, timer->expires);
255 }
256 atomic64_sub(elapsed, &virt_timer_elapsed);
257 spin_unlock(&virt_timer_lock);
258
259 /* Do callbacks and recharge periodic timers */
260 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
261 list_del_init(&timer->entry);
262 timer->function(timer->data);
263 if (timer->interval) {
264 /* Recharge interval timer */
265 timer->expires = timer->interval +
266 atomic64_read(&virt_timer_elapsed);
267 spin_lock(&virt_timer_lock);
268 list_add_sorted(timer, &virt_timer_list);
269 spin_unlock(&virt_timer_lock);
270 }
271 }
272 }
273
init_virt_timer(struct vtimer_list * timer)274 void init_virt_timer(struct vtimer_list *timer)
275 {
276 timer->function = NULL;
277 INIT_LIST_HEAD(&timer->entry);
278 }
279 EXPORT_SYMBOL(init_virt_timer);
280
vtimer_pending(struct vtimer_list * timer)281 static inline int vtimer_pending(struct vtimer_list *timer)
282 {
283 return !list_empty(&timer->entry);
284 }
285
internal_add_vtimer(struct vtimer_list * timer)286 static void internal_add_vtimer(struct vtimer_list *timer)
287 {
288 if (list_empty(&virt_timer_list)) {
289 /* First timer, just program it. */
290 atomic64_set(&virt_timer_current, timer->expires);
291 atomic64_set(&virt_timer_elapsed, 0);
292 list_add(&timer->entry, &virt_timer_list);
293 } else {
294 /* Update timer against current base. */
295 timer->expires += atomic64_read(&virt_timer_elapsed);
296 if (likely((s64) timer->expires <
297 (s64) atomic64_read(&virt_timer_current)))
298 /* The new timer expires before the current timer. */
299 atomic64_set(&virt_timer_current, timer->expires);
300 /* Insert new timer into the list. */
301 list_add_sorted(timer, &virt_timer_list);
302 }
303 }
304
__add_vtimer(struct vtimer_list * timer,int periodic)305 static void __add_vtimer(struct vtimer_list *timer, int periodic)
306 {
307 unsigned long flags;
308
309 timer->interval = periodic ? timer->expires : 0;
310 spin_lock_irqsave(&virt_timer_lock, flags);
311 internal_add_vtimer(timer);
312 spin_unlock_irqrestore(&virt_timer_lock, flags);
313 }
314
315 /*
316 * add_virt_timer - add an oneshot virtual CPU timer
317 */
add_virt_timer(struct vtimer_list * timer)318 void add_virt_timer(struct vtimer_list *timer)
319 {
320 __add_vtimer(timer, 0);
321 }
322 EXPORT_SYMBOL(add_virt_timer);
323
324 /*
325 * add_virt_timer_int - add an interval virtual CPU timer
326 */
add_virt_timer_periodic(struct vtimer_list * timer)327 void add_virt_timer_periodic(struct vtimer_list *timer)
328 {
329 __add_vtimer(timer, 1);
330 }
331 EXPORT_SYMBOL(add_virt_timer_periodic);
332
__mod_vtimer(struct vtimer_list * timer,u64 expires,int periodic)333 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
334 {
335 unsigned long flags;
336 int rc;
337
338 BUG_ON(!timer->function);
339
340 if (timer->expires == expires && vtimer_pending(timer))
341 return 1;
342 spin_lock_irqsave(&virt_timer_lock, flags);
343 rc = vtimer_pending(timer);
344 if (rc)
345 list_del_init(&timer->entry);
346 timer->interval = periodic ? expires : 0;
347 timer->expires = expires;
348 internal_add_vtimer(timer);
349 spin_unlock_irqrestore(&virt_timer_lock, flags);
350 return rc;
351 }
352
353 /*
354 * returns whether it has modified a pending timer (1) or not (0)
355 */
mod_virt_timer(struct vtimer_list * timer,u64 expires)356 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
357 {
358 return __mod_vtimer(timer, expires, 0);
359 }
360 EXPORT_SYMBOL(mod_virt_timer);
361
362 /*
363 * returns whether it has modified a pending timer (1) or not (0)
364 */
mod_virt_timer_periodic(struct vtimer_list * timer,u64 expires)365 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
366 {
367 return __mod_vtimer(timer, expires, 1);
368 }
369 EXPORT_SYMBOL(mod_virt_timer_periodic);
370
371 /*
372 * Delete a virtual timer.
373 *
374 * returns whether the deleted timer was pending (1) or not (0)
375 */
del_virt_timer(struct vtimer_list * timer)376 int del_virt_timer(struct vtimer_list *timer)
377 {
378 unsigned long flags;
379
380 if (!vtimer_pending(timer))
381 return 0;
382 spin_lock_irqsave(&virt_timer_lock, flags);
383 list_del_init(&timer->entry);
384 spin_unlock_irqrestore(&virt_timer_lock, flags);
385 return 1;
386 }
387 EXPORT_SYMBOL(del_virt_timer);
388
389 /*
390 * Start the virtual CPU timer on the current CPU.
391 */
vtime_init(void)392 void vtime_init(void)
393 {
394 /* set initial cpu timer */
395 set_vtimer(VTIMER_MAX_SLICE);
396 /* Setup initial MT scaling values */
397 if (smp_cpu_mtid) {
398 __this_cpu_write(mt_scaling_jiffies, jiffies);
399 __this_cpu_write(mt_scaling_mult, 1);
400 __this_cpu_write(mt_scaling_div, 1);
401 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));
402 }
403 }
404