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Linux/arch/s390/kernel/perf_cpum_sf.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Performance event support for the System z CPU-measurement Sampling Facility
  4  *
  5  * Copyright IBM Corp. 2013, 2018
  6  * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
  7  */
  8 #define KMSG_COMPONENT  "cpum_sf"
  9 #define pr_fmt(fmt)     KMSG_COMPONENT ": " fmt
 10 
 11 #include <linux/kernel.h>
 12 #include <linux/kernel_stat.h>
 13 #include <linux/perf_event.h>
 14 #include <linux/percpu.h>
 15 #include <linux/pid.h>
 16 #include <linux/notifier.h>
 17 #include <linux/export.h>
 18 #include <linux/slab.h>
 19 #include <linux/mm.h>
 20 #include <linux/moduleparam.h>
 21 #include <asm/cpu_mf.h>
 22 #include <asm/irq.h>
 23 #include <asm/debug.h>
 24 #include <asm/timex.h>
 25 
 26 /* Minimum number of sample-data-block-tables:
 27  * At least one table is required for the sampling buffer structure.
 28  * A single table contains up to 511 pointers to sample-data-blocks.
 29  */
 30 #define CPUM_SF_MIN_SDBT        1
 31 
 32 /* Number of sample-data-blocks per sample-data-block-table (SDBT):
 33  * A table contains SDB pointers (8 bytes) and one table-link entry
 34  * that points to the origin of the next SDBT.
 35  */
 36 #define CPUM_SF_SDB_PER_TABLE   ((PAGE_SIZE - 8) / 8)
 37 
 38 /* Maximum page offset for an SDBT table-link entry:
 39  * If this page offset is reached, a table-link entry to the next SDBT
 40  * must be added.
 41  */
 42 #define CPUM_SF_SDBT_TL_OFFSET  (CPUM_SF_SDB_PER_TABLE * 8)
 43 static inline int require_table_link(const void *sdbt)
 44 {
 45         return ((unsigned long) sdbt & ~PAGE_MASK) == CPUM_SF_SDBT_TL_OFFSET;
 46 }
 47 
 48 /* Minimum and maximum sampling buffer sizes:
 49  *
 50  * This number represents the maximum size of the sampling buffer taking
 51  * the number of sample-data-block-tables into account.  Note that these
 52  * numbers apply to the basic-sampling function only.
 53  * The maximum number of SDBs is increased by CPUM_SF_SDB_DIAG_FACTOR if
 54  * the diagnostic-sampling function is active.
 55  *
 56  * Sampling buffer size         Buffer characteristics
 57  * ---------------------------------------------------
 58  *       64KB               ==    16 pages (4KB per page)
 59  *                                 1 page  for SDB-tables
 60  *                                15 pages for SDBs
 61  *
 62  *  32MB                    ==  8192 pages (4KB per page)
 63  *                                16 pages for SDB-tables
 64  *                              8176 pages for SDBs
 65  */
 66 static unsigned long __read_mostly CPUM_SF_MIN_SDB = 15;
 67 static unsigned long __read_mostly CPUM_SF_MAX_SDB = 8176;
 68 static unsigned long __read_mostly CPUM_SF_SDB_DIAG_FACTOR = 1;
 69 
 70 struct sf_buffer {
 71         unsigned long    *sdbt;     /* Sample-data-block-table origin */
 72         /* buffer characteristics (required for buffer increments) */
 73         unsigned long  num_sdb;     /* Number of sample-data-blocks */
 74         unsigned long num_sdbt;     /* Number of sample-data-block-tables */
 75         unsigned long    *tail;     /* last sample-data-block-table */
 76 };
 77 
 78 struct aux_buffer {
 79         struct sf_buffer sfb;
 80         unsigned long head;        /* index of SDB of buffer head */
 81         unsigned long alert_mark;  /* index of SDB of alert request position */
 82         unsigned long empty_mark;  /* mark of SDB not marked full */
 83         unsigned long *sdb_index;  /* SDB address for fast lookup */
 84         unsigned long *sdbt_index; /* SDBT address for fast lookup */
 85 };
 86 
 87 struct cpu_hw_sf {
 88         /* CPU-measurement sampling information block */
 89         struct hws_qsi_info_block qsi;
 90         /* CPU-measurement sampling control block */
 91         struct hws_lsctl_request_block lsctl;
 92         struct sf_buffer sfb;       /* Sampling buffer */
 93         unsigned int flags;         /* Status flags */
 94         struct perf_event *event;   /* Scheduled perf event */
 95         struct perf_output_handle handle; /* AUX buffer output handle */
 96 };
 97 static DEFINE_PER_CPU(struct cpu_hw_sf, cpu_hw_sf);
 98 
 99 /* Debug feature */
100 static debug_info_t *sfdbg;
101 
102 /*
103  * sf_disable() - Switch off sampling facility
104  */
105 static int sf_disable(void)
106 {
107         struct hws_lsctl_request_block sreq;
108 
109         memset(&sreq, 0, sizeof(sreq));
110         return lsctl(&sreq);
111 }
112 
113 /*
114  * sf_buffer_available() - Check for an allocated sampling buffer
115  */
116 static int sf_buffer_available(struct cpu_hw_sf *cpuhw)
117 {
118         return !!cpuhw->sfb.sdbt;
119 }
120 
121 /*
122  * deallocate sampling facility buffer
123  */
124 static void free_sampling_buffer(struct sf_buffer *sfb)
125 {
126         unsigned long *sdbt, *curr;
127 
128         if (!sfb->sdbt)
129                 return;
130 
131         sdbt = sfb->sdbt;
132         curr = sdbt;
133 
134         /* Free the SDBT after all SDBs are processed... */
135         while (1) {
136                 if (!*curr || !sdbt)
137                         break;
138 
139                 /* Process table-link entries */
140                 if (is_link_entry(curr)) {
141                         curr = get_next_sdbt(curr);
142                         if (sdbt)
143                                 free_page((unsigned long) sdbt);
144 
145                         /* If the origin is reached, sampling buffer is freed */
146                         if (curr == sfb->sdbt)
147                                 break;
148                         else
149                                 sdbt = curr;
150                 } else {
151                         /* Process SDB pointer */
152                         if (*curr) {
153                                 free_page(*curr);
154                                 curr++;
155                         }
156                 }
157         }
158 
159         debug_sprintf_event(sfdbg, 5,
160                             "free_sampling_buffer: freed sdbt=%p\n", sfb->sdbt);
161         memset(sfb, 0, sizeof(*sfb));
162 }
163 
164 static int alloc_sample_data_block(unsigned long *sdbt, gfp_t gfp_flags)
165 {
166         unsigned long sdb, *trailer;
167 
168         /* Allocate and initialize sample-data-block */
169         sdb = get_zeroed_page(gfp_flags);
170         if (!sdb)
171                 return -ENOMEM;
172         trailer = trailer_entry_ptr(sdb);
173         *trailer = SDB_TE_ALERT_REQ_MASK;
174 
175         /* Link SDB into the sample-data-block-table */
176         *sdbt = sdb;
177 
178         return 0;
179 }
180 
181 /*
182  * realloc_sampling_buffer() - extend sampler memory
183  *
184  * Allocates new sample-data-blocks and adds them to the specified sampling
185  * buffer memory.
186  *
187  * Important: This modifies the sampling buffer and must be called when the
188  *            sampling facility is disabled.
189  *
190  * Returns zero on success, non-zero otherwise.
191  */
192 static int realloc_sampling_buffer(struct sf_buffer *sfb,
193                                    unsigned long num_sdb, gfp_t gfp_flags)
194 {
195         int i, rc;
196         unsigned long *new, *tail;
197 
198         if (!sfb->sdbt || !sfb->tail)
199                 return -EINVAL;
200 
201         if (!is_link_entry(sfb->tail))
202                 return -EINVAL;
203 
204         /* Append to the existing sampling buffer, overwriting the table-link
205          * register.
206          * The tail variables always points to the "tail" (last and table-link)
207          * entry in an SDB-table.
208          */
209         tail = sfb->tail;
210 
211         /* Do a sanity check whether the table-link entry points to
212          * the sampling buffer origin.
213          */
214         if (sfb->sdbt != get_next_sdbt(tail)) {
215                 debug_sprintf_event(sfdbg, 3, "realloc_sampling_buffer: "
216                                     "sampling buffer is not linked: origin=%p"
217                                     "tail=%p\n",
218                                     (void *) sfb->sdbt, (void *) tail);
219                 return -EINVAL;
220         }
221 
222         /* Allocate remaining SDBs */
223         rc = 0;
224         for (i = 0; i < num_sdb; i++) {
225                 /* Allocate a new SDB-table if it is full. */
226                 if (require_table_link(tail)) {
227                         new = (unsigned long *) get_zeroed_page(gfp_flags);
228                         if (!new) {
229                                 rc = -ENOMEM;
230                                 break;
231                         }
232                         sfb->num_sdbt++;
233                         /* Link current page to tail of chain */
234                         *tail = (unsigned long)(void *) new + 1;
235                         tail = new;
236                 }
237 
238                 /* Allocate a new sample-data-block.
239                  * If there is not enough memory, stop the realloc process
240                  * and simply use what was allocated.  If this is a temporary
241                  * issue, a new realloc call (if required) might succeed.
242                  */
243                 rc = alloc_sample_data_block(tail, gfp_flags);
244                 if (rc)
245                         break;
246                 sfb->num_sdb++;
247                 tail++;
248         }
249 
250         /* Link sampling buffer to its origin */
251         *tail = (unsigned long) sfb->sdbt + 1;
252         sfb->tail = tail;
253 
254         debug_sprintf_event(sfdbg, 4, "realloc_sampling_buffer: new buffer"
255                             " settings: sdbt=%lu sdb=%lu\n",
256                             sfb->num_sdbt, sfb->num_sdb);
257         return rc;
258 }
259 
260 /*
261  * allocate_sampling_buffer() - allocate sampler memory
262  *
263  * Allocates and initializes a sampling buffer structure using the
264  * specified number of sample-data-blocks (SDB).  For each allocation,
265  * a 4K page is used.  The number of sample-data-block-tables (SDBT)
266  * are calculated from SDBs.
267  * Also set the ALERT_REQ mask in each SDBs trailer.
268  *
269  * Returns zero on success, non-zero otherwise.
270  */
271 static int alloc_sampling_buffer(struct sf_buffer *sfb, unsigned long num_sdb)
272 {
273         int rc;
274 
275         if (sfb->sdbt)
276                 return -EINVAL;
277 
278         /* Allocate the sample-data-block-table origin */
279         sfb->sdbt = (unsigned long *) get_zeroed_page(GFP_KERNEL);
280         if (!sfb->sdbt)
281                 return -ENOMEM;
282         sfb->num_sdb = 0;
283         sfb->num_sdbt = 1;
284 
285         /* Link the table origin to point to itself to prepare for
286          * realloc_sampling_buffer() invocation.
287          */
288         sfb->tail = sfb->sdbt;
289         *sfb->tail = (unsigned long)(void *) sfb->sdbt + 1;
290 
291         /* Allocate requested number of sample-data-blocks */
292         rc = realloc_sampling_buffer(sfb, num_sdb, GFP_KERNEL);
293         if (rc) {
294                 free_sampling_buffer(sfb);
295                 debug_sprintf_event(sfdbg, 4, "alloc_sampling_buffer: "
296                         "realloc_sampling_buffer failed with rc=%i\n", rc);
297         } else
298                 debug_sprintf_event(sfdbg, 4,
299                         "alloc_sampling_buffer: tear=%p dear=%p\n",
300                         sfb->sdbt, (void *) *sfb->sdbt);
301         return rc;
302 }
303 
304 static void sfb_set_limits(unsigned long min, unsigned long max)
305 {
306         struct hws_qsi_info_block si;
307 
308         CPUM_SF_MIN_SDB = min;
309         CPUM_SF_MAX_SDB = max;
310 
311         memset(&si, 0, sizeof(si));
312         if (!qsi(&si))
313                 CPUM_SF_SDB_DIAG_FACTOR = DIV_ROUND_UP(si.dsdes, si.bsdes);
314 }
315 
316 static unsigned long sfb_max_limit(struct hw_perf_event *hwc)
317 {
318         return SAMPL_DIAG_MODE(hwc) ? CPUM_SF_MAX_SDB * CPUM_SF_SDB_DIAG_FACTOR
319                                     : CPUM_SF_MAX_SDB;
320 }
321 
322 static unsigned long sfb_pending_allocs(struct sf_buffer *sfb,
323                                         struct hw_perf_event *hwc)
324 {
325         if (!sfb->sdbt)
326                 return SFB_ALLOC_REG(hwc);
327         if (SFB_ALLOC_REG(hwc) > sfb->num_sdb)
328                 return SFB_ALLOC_REG(hwc) - sfb->num_sdb;
329         return 0;
330 }
331 
332 static int sfb_has_pending_allocs(struct sf_buffer *sfb,
333                                    struct hw_perf_event *hwc)
334 {
335         return sfb_pending_allocs(sfb, hwc) > 0;
336 }
337 
338 static void sfb_account_allocs(unsigned long num, struct hw_perf_event *hwc)
339 {
340         /* Limit the number of SDBs to not exceed the maximum */
341         num = min_t(unsigned long, num, sfb_max_limit(hwc) - SFB_ALLOC_REG(hwc));
342         if (num)
343                 SFB_ALLOC_REG(hwc) += num;
344 }
345 
346 static void sfb_init_allocs(unsigned long num, struct hw_perf_event *hwc)
347 {
348         SFB_ALLOC_REG(hwc) = 0;
349         sfb_account_allocs(num, hwc);
350 }
351 
352 static void deallocate_buffers(struct cpu_hw_sf *cpuhw)
353 {
354         if (cpuhw->sfb.sdbt)
355                 free_sampling_buffer(&cpuhw->sfb);
356 }
357 
358 static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc)
359 {
360         unsigned long n_sdb, freq, factor;
361         size_t sample_size;
362 
363         /* Calculate sampling buffers using 4K pages
364          *
365          *    1. Determine the sample data size which depends on the used
366          *       sampling functions, for example, basic-sampling or
367          *       basic-sampling with diagnostic-sampling.
368          *
369          *    2. Use the sampling frequency as input.  The sampling buffer is
370          *       designed for almost one second.  This can be adjusted through
371          *       the "factor" variable.
372          *       In any case, alloc_sampling_buffer() sets the Alert Request
373          *       Control indicator to trigger a measurement-alert to harvest
374          *       sample-data-blocks (sdb).
375          *
376          *    3. Compute the number of sample-data-blocks and ensure a minimum
377          *       of CPUM_SF_MIN_SDB.  Also ensure the upper limit does not
378          *       exceed a "calculated" maximum.  The symbolic maximum is
379          *       designed for basic-sampling only and needs to be increased if
380          *       diagnostic-sampling is active.
381          *       See also the remarks for these symbolic constants.
382          *
383          *    4. Compute the number of sample-data-block-tables (SDBT) and
384          *       ensure a minimum of CPUM_SF_MIN_SDBT (one table can manage up
385          *       to 511 SDBs).
386          */
387         sample_size = sizeof(struct hws_basic_entry);
388         freq = sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc));
389         factor = 1;
390         n_sdb = DIV_ROUND_UP(freq, factor * ((PAGE_SIZE-64) / sample_size));
391         if (n_sdb < CPUM_SF_MIN_SDB)
392                 n_sdb = CPUM_SF_MIN_SDB;
393 
394         /* If there is already a sampling buffer allocated, it is very likely
395          * that the sampling facility is enabled too.  If the event to be
396          * initialized requires a greater sampling buffer, the allocation must
397          * be postponed.  Changing the sampling buffer requires the sampling
398          * facility to be in the disabled state.  So, account the number of
399          * required SDBs and let cpumsf_pmu_enable() resize the buffer just
400          * before the event is started.
401          */
402         sfb_init_allocs(n_sdb, hwc);
403         if (sf_buffer_available(cpuhw))
404                 return 0;
405 
406         debug_sprintf_event(sfdbg, 3,
407                             "allocate_buffers: rate=%lu f=%lu sdb=%lu/%lu"
408                             " sample_size=%lu cpuhw=%p\n",
409                             SAMPL_RATE(hwc), freq, n_sdb, sfb_max_limit(hwc),
410                             sample_size, cpuhw);
411 
412         return alloc_sampling_buffer(&cpuhw->sfb,
413                                      sfb_pending_allocs(&cpuhw->sfb, hwc));
414 }
415 
416 static unsigned long min_percent(unsigned int percent, unsigned long base,
417                                  unsigned long min)
418 {
419         return min_t(unsigned long, min, DIV_ROUND_UP(percent * base, 100));
420 }
421 
422 static unsigned long compute_sfb_extent(unsigned long ratio, unsigned long base)
423 {
424         /* Use a percentage-based approach to extend the sampling facility
425          * buffer.  Accept up to 5% sample data loss.
426          * Vary the extents between 1% to 5% of the current number of
427          * sample-data-blocks.
428          */
429         if (ratio <= 5)
430                 return 0;
431         if (ratio <= 25)
432                 return min_percent(1, base, 1);
433         if (ratio <= 50)
434                 return min_percent(1, base, 1);
435         if (ratio <= 75)
436                 return min_percent(2, base, 2);
437         if (ratio <= 100)
438                 return min_percent(3, base, 3);
439         if (ratio <= 250)
440                 return min_percent(4, base, 4);
441 
442         return min_percent(5, base, 8);
443 }
444 
445 static void sfb_account_overflows(struct cpu_hw_sf *cpuhw,
446                                   struct hw_perf_event *hwc)
447 {
448         unsigned long ratio, num;
449 
450         if (!OVERFLOW_REG(hwc))
451                 return;
452 
453         /* The sample_overflow contains the average number of sample data
454          * that has been lost because sample-data-blocks were full.
455          *
456          * Calculate the total number of sample data entries that has been
457          * discarded.  Then calculate the ratio of lost samples to total samples
458          * per second in percent.
459          */
460         ratio = DIV_ROUND_UP(100 * OVERFLOW_REG(hwc) * cpuhw->sfb.num_sdb,
461                              sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc)));
462 
463         /* Compute number of sample-data-blocks */
464         num = compute_sfb_extent(ratio, cpuhw->sfb.num_sdb);
465         if (num)
466                 sfb_account_allocs(num, hwc);
467 
468         debug_sprintf_event(sfdbg, 5, "sfb: overflow: overflow=%llu ratio=%lu"
469                             " num=%lu\n", OVERFLOW_REG(hwc), ratio, num);
470         OVERFLOW_REG(hwc) = 0;
471 }
472 
473 /* extend_sampling_buffer() - Extend sampling buffer
474  * @sfb:        Sampling buffer structure (for local CPU)
475  * @hwc:        Perf event hardware structure
476  *
477  * Use this function to extend the sampling buffer based on the overflow counter
478  * and postponed allocation extents stored in the specified Perf event hardware.
479  *
480  * Important: This function disables the sampling facility in order to safely
481  *            change the sampling buffer structure.  Do not call this function
482  *            when the PMU is active.
483  */
484 static void extend_sampling_buffer(struct sf_buffer *sfb,
485                                    struct hw_perf_event *hwc)
486 {
487         unsigned long num, num_old;
488         int rc;
489 
490         num = sfb_pending_allocs(sfb, hwc);
491         if (!num)
492                 return;
493         num_old = sfb->num_sdb;
494 
495         /* Disable the sampling facility to reset any states and also
496          * clear pending measurement alerts.
497          */
498         sf_disable();
499 
500         /* Extend the sampling buffer.
501          * This memory allocation typically happens in an atomic context when
502          * called by perf.  Because this is a reallocation, it is fine if the
503          * new SDB-request cannot be satisfied immediately.
504          */
505         rc = realloc_sampling_buffer(sfb, num, GFP_ATOMIC);
506         if (rc)
507                 debug_sprintf_event(sfdbg, 5, "sfb: extend: realloc "
508                                     "failed with rc=%i\n", rc);
509 
510         if (sfb_has_pending_allocs(sfb, hwc))
511                 debug_sprintf_event(sfdbg, 5, "sfb: extend: "
512                                     "req=%lu alloc=%lu remaining=%lu\n",
513                                     num, sfb->num_sdb - num_old,
514                                     sfb_pending_allocs(sfb, hwc));
515 }
516 
517 
518 /* Number of perf events counting hardware events */
519 static atomic_t num_events;
520 /* Used to avoid races in calling reserve/release_cpumf_hardware */
521 static DEFINE_MUTEX(pmc_reserve_mutex);
522 
523 #define PMC_INIT      0
524 #define PMC_RELEASE   1
525 #define PMC_FAILURE   2
526 static void setup_pmc_cpu(void *flags)
527 {
528         int err;
529         struct cpu_hw_sf *cpusf = this_cpu_ptr(&cpu_hw_sf);
530 
531         err = 0;
532         switch (*((int *) flags)) {
533         case PMC_INIT:
534                 memset(cpusf, 0, sizeof(*cpusf));
535                 err = qsi(&cpusf->qsi);
536                 if (err)
537                         break;
538                 cpusf->flags |= PMU_F_RESERVED;
539                 err = sf_disable();
540                 if (err)
541                         pr_err("Switching off the sampling facility failed "
542                                "with rc=%i\n", err);
543                 debug_sprintf_event(sfdbg, 5,
544                                     "setup_pmc_cpu: initialized: cpuhw=%p\n", cpusf);
545                 break;
546         case PMC_RELEASE:
547                 cpusf->flags &= ~PMU_F_RESERVED;
548                 err = sf_disable();
549                 if (err) {
550                         pr_err("Switching off the sampling facility failed "
551                                "with rc=%i\n", err);
552                 } else
553                         deallocate_buffers(cpusf);
554                 debug_sprintf_event(sfdbg, 5,
555                                     "setup_pmc_cpu: released: cpuhw=%p\n", cpusf);
556                 break;
557         }
558         if (err)
559                 *((int *) flags) |= PMC_FAILURE;
560 }
561 
562 static void release_pmc_hardware(void)
563 {
564         int flags = PMC_RELEASE;
565 
566         irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
567         on_each_cpu(setup_pmc_cpu, &flags, 1);
568 }
569 
570 static int reserve_pmc_hardware(void)
571 {
572         int flags = PMC_INIT;
573 
574         on_each_cpu(setup_pmc_cpu, &flags, 1);
575         if (flags & PMC_FAILURE) {
576                 release_pmc_hardware();
577                 return -ENODEV;
578         }
579         irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
580 
581         return 0;
582 }
583 
584 static void hw_perf_event_destroy(struct perf_event *event)
585 {
586         /* Release PMC if this is the last perf event */
587         if (!atomic_add_unless(&num_events, -1, 1)) {
588                 mutex_lock(&pmc_reserve_mutex);
589                 if (atomic_dec_return(&num_events) == 0)
590                         release_pmc_hardware();
591                 mutex_unlock(&pmc_reserve_mutex);
592         }
593 }
594 
595 static void hw_init_period(struct hw_perf_event *hwc, u64 period)
596 {
597         hwc->sample_period = period;
598         hwc->last_period = hwc->sample_period;
599         local64_set(&hwc->period_left, hwc->sample_period);
600 }
601 
602 static void hw_reset_registers(struct hw_perf_event *hwc,
603                                unsigned long *sdbt_origin)
604 {
605         /* (Re)set to first sample-data-block-table */
606         TEAR_REG(hwc) = (unsigned long) sdbt_origin;
607 }
608 
609 static unsigned long hw_limit_rate(const struct hws_qsi_info_block *si,
610                                    unsigned long rate)
611 {
612         return clamp_t(unsigned long, rate,
613                        si->min_sampl_rate, si->max_sampl_rate);
614 }
615 
616 static u32 cpumsf_pid_type(struct perf_event *event,
617                            u32 pid, enum pid_type type)
618 {
619         struct task_struct *tsk;
620 
621         /* Idle process */
622         if (!pid)
623                 goto out;
624 
625         tsk = find_task_by_pid_ns(pid, &init_pid_ns);
626         pid = -1;
627         if (tsk) {
628                 /*
629                  * Only top level events contain the pid namespace in which
630                  * they are created.
631                  */
632                 if (event->parent)
633                         event = event->parent;
634                 pid = __task_pid_nr_ns(tsk, type, event->ns);
635                 /*
636                  * See also 1d953111b648
637                  * "perf/core: Don't report zero PIDs for exiting tasks".
638                  */
639                 if (!pid && !pid_alive(tsk))
640                         pid = -1;
641         }
642 out:
643         return pid;
644 }
645 
646 static void cpumsf_output_event_pid(struct perf_event *event,
647                                     struct perf_sample_data *data,
648                                     struct pt_regs *regs)
649 {
650         u32 pid;
651         struct perf_event_header header;
652         struct perf_output_handle handle;
653 
654         /*
655          * Obtain the PID from the basic-sampling data entry and
656          * correct the data->tid_entry.pid value.
657          */
658         pid = data->tid_entry.pid;
659 
660         /* Protect callchain buffers, tasks */
661         rcu_read_lock();
662 
663         perf_prepare_sample(&header, data, event, regs);
664         if (perf_output_begin(&handle, event, header.size))
665                 goto out;
666 
667         /* Update the process ID (see also kernel/events/core.c) */
668         data->tid_entry.pid = cpumsf_pid_type(event, pid, PIDTYPE_TGID);
669         data->tid_entry.tid = cpumsf_pid_type(event, pid, PIDTYPE_PID);
670 
671         perf_output_sample(&handle, &header, data, event);
672         perf_output_end(&handle);
673 out:
674         rcu_read_unlock();
675 }
676 
677 static int __hw_perf_event_init(struct perf_event *event)
678 {
679         struct cpu_hw_sf *cpuhw;
680         struct hws_qsi_info_block si;
681         struct perf_event_attr *attr = &event->attr;
682         struct hw_perf_event *hwc = &event->hw;
683         unsigned long rate;
684         int cpu, err;
685 
686         /* Reserve CPU-measurement sampling facility */
687         err = 0;
688         if (!atomic_inc_not_zero(&num_events)) {
689                 mutex_lock(&pmc_reserve_mutex);
690                 if (atomic_read(&num_events) == 0 && reserve_pmc_hardware())
691                         err = -EBUSY;
692                 else
693                         atomic_inc(&num_events);
694                 mutex_unlock(&pmc_reserve_mutex);
695         }
696         event->destroy = hw_perf_event_destroy;
697 
698         if (err)
699                 goto out;
700 
701         /* Access per-CPU sampling information (query sampling info) */
702         /*
703          * The event->cpu value can be -1 to count on every CPU, for example,
704          * when attaching to a task.  If this is specified, use the query
705          * sampling info from the current CPU, otherwise use event->cpu to
706          * retrieve the per-CPU information.
707          * Later, cpuhw indicates whether to allocate sampling buffers for a
708          * particular CPU (cpuhw!=NULL) or each online CPU (cpuw==NULL).
709          */
710         memset(&si, 0, sizeof(si));
711         cpuhw = NULL;
712         if (event->cpu == -1)
713                 qsi(&si);
714         else {
715                 /* Event is pinned to a particular CPU, retrieve the per-CPU
716                  * sampling structure for accessing the CPU-specific QSI.
717                  */
718                 cpuhw = &per_cpu(cpu_hw_sf, event->cpu);
719                 si = cpuhw->qsi;
720         }
721 
722         /* Check sampling facility authorization and, if not authorized,
723          * fall back to other PMUs.  It is safe to check any CPU because
724          * the authorization is identical for all configured CPUs.
725          */
726         if (!si.as) {
727                 err = -ENOENT;
728                 goto out;
729         }
730 
731         /* Always enable basic sampling */
732         SAMPL_FLAGS(hwc) = PERF_CPUM_SF_BASIC_MODE;
733 
734         /* Check if diagnostic sampling is requested.  Deny if the required
735          * sampling authorization is missing.
736          */
737         if (attr->config == PERF_EVENT_CPUM_SF_DIAG) {
738                 if (!si.ad) {
739                         err = -EPERM;
740                         goto out;
741                 }
742                 SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_DIAG_MODE;
743         }
744 
745         /* Check and set other sampling flags */
746         if (attr->config1 & PERF_CPUM_SF_FULL_BLOCKS)
747                 SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_FULL_BLOCKS;
748 
749         /* The sampling information (si) contains information about the
750          * min/max sampling intervals and the CPU speed.  So calculate the
751          * correct sampling interval and avoid the whole period adjust
752          * feedback loop.
753          */
754         rate = 0;
755         if (attr->freq) {
756                 if (!attr->sample_freq) {
757                         err = -EINVAL;
758                         goto out;
759                 }
760                 rate = freq_to_sample_rate(&si, attr->sample_freq);
761                 rate = hw_limit_rate(&si, rate);
762                 attr->freq = 0;
763                 attr->sample_period = rate;
764         } else {
765                 /* The min/max sampling rates specifies the valid range
766                  * of sample periods.  If the specified sample period is
767                  * out of range, limit the period to the range boundary.
768                  */
769                 rate = hw_limit_rate(&si, hwc->sample_period);
770 
771                 /* The perf core maintains a maximum sample rate that is
772                  * configurable through the sysctl interface.  Ensure the
773                  * sampling rate does not exceed this value.  This also helps
774                  * to avoid throttling when pushing samples with
775                  * perf_event_overflow().
776                  */
777                 if (sample_rate_to_freq(&si, rate) >
778                       sysctl_perf_event_sample_rate) {
779                         err = -EINVAL;
780                         debug_sprintf_event(sfdbg, 1, "Sampling rate exceeds maximum perf sample rate\n");
781                         goto out;
782                 }
783         }
784         SAMPL_RATE(hwc) = rate;
785         hw_init_period(hwc, SAMPL_RATE(hwc));
786 
787         /* Initialize sample data overflow accounting */
788         hwc->extra_reg.reg = REG_OVERFLOW;
789         OVERFLOW_REG(hwc) = 0;
790 
791         /* Use AUX buffer. No need to allocate it by ourself */
792         if (attr->config == PERF_EVENT_CPUM_SF_DIAG)
793                 return 0;
794 
795         /* Allocate the per-CPU sampling buffer using the CPU information
796          * from the event.  If the event is not pinned to a particular
797          * CPU (event->cpu == -1; or cpuhw == NULL), allocate sampling
798          * buffers for each online CPU.
799          */
800         if (cpuhw)
801                 /* Event is pinned to a particular CPU */
802                 err = allocate_buffers(cpuhw, hwc);
803         else {
804                 /* Event is not pinned, allocate sampling buffer on
805                  * each online CPU
806                  */
807                 for_each_online_cpu(cpu) {
808                         cpuhw = &per_cpu(cpu_hw_sf, cpu);
809                         err = allocate_buffers(cpuhw, hwc);
810                         if (err)
811                                 break;
812                 }
813         }
814 
815         /* If PID/TID sampling is active, replace the default overflow
816          * handler to extract and resolve the PIDs from the basic-sampling
817          * data entries.
818          */
819         if (event->attr.sample_type & PERF_SAMPLE_TID)
820                 if (is_default_overflow_handler(event))
821                         event->overflow_handler = cpumsf_output_event_pid;
822 out:
823         return err;
824 }
825 
826 static int cpumsf_pmu_event_init(struct perf_event *event)
827 {
828         int err;
829 
830         /* No support for taken branch sampling */
831         if (has_branch_stack(event))
832                 return -EOPNOTSUPP;
833 
834         switch (event->attr.type) {
835         case PERF_TYPE_RAW:
836                 if ((event->attr.config != PERF_EVENT_CPUM_SF) &&
837                     (event->attr.config != PERF_EVENT_CPUM_SF_DIAG))
838                         return -ENOENT;
839                 break;
840         case PERF_TYPE_HARDWARE:
841                 /* Support sampling of CPU cycles in addition to the
842                  * counter facility.  However, the counter facility
843                  * is more precise and, hence, restrict this PMU to
844                  * sampling events only.
845                  */
846                 if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES)
847                         return -ENOENT;
848                 if (!is_sampling_event(event))
849                         return -ENOENT;
850                 break;
851         default:
852                 return -ENOENT;
853         }
854 
855         /* Check online status of the CPU to which the event is pinned */
856         if (event->cpu >= 0 && !cpu_online(event->cpu))
857                         return -ENODEV;
858 
859         /* Force reset of idle/hv excludes regardless of what the
860          * user requested.
861          */
862         if (event->attr.exclude_hv)
863                 event->attr.exclude_hv = 0;
864         if (event->attr.exclude_idle)
865                 event->attr.exclude_idle = 0;
866 
867         err = __hw_perf_event_init(event);
868         if (unlikely(err))
869                 if (event->destroy)
870                         event->destroy(event);
871         return err;
872 }
873 
874 static void cpumsf_pmu_enable(struct pmu *pmu)
875 {
876         struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
877         struct hw_perf_event *hwc;
878         int err;
879 
880         if (cpuhw->flags & PMU_F_ENABLED)
881                 return;
882 
883         if (cpuhw->flags & PMU_F_ERR_MASK)
884                 return;
885 
886         /* Check whether to extent the sampling buffer.
887          *
888          * Two conditions trigger an increase of the sampling buffer for a
889          * perf event:
890          *    1. Postponed buffer allocations from the event initialization.
891          *    2. Sampling overflows that contribute to pending allocations.
892          *
893          * Note that the extend_sampling_buffer() function disables the sampling
894          * facility, but it can be fully re-enabled using sampling controls that
895          * have been saved in cpumsf_pmu_disable().
896          */
897         if (cpuhw->event) {
898                 hwc = &cpuhw->event->hw;
899                 if (!(SAMPL_DIAG_MODE(hwc))) {
900                         /*
901                          * Account number of overflow-designated
902                          * buffer extents
903                          */
904                         sfb_account_overflows(cpuhw, hwc);
905                         if (sfb_has_pending_allocs(&cpuhw->sfb, hwc))
906                                 extend_sampling_buffer(&cpuhw->sfb, hwc);
907                 }
908         }
909 
910         /* (Re)enable the PMU and sampling facility */
911         cpuhw->flags |= PMU_F_ENABLED;
912         barrier();
913 
914         err = lsctl(&cpuhw->lsctl);
915         if (err) {
916                 cpuhw->flags &= ~PMU_F_ENABLED;
917                 pr_err("Loading sampling controls failed: op=%i err=%i\n",
918                         1, err);
919                 return;
920         }
921 
922         /* Load current program parameter */
923         lpp(&S390_lowcore.lpp);
924 
925         debug_sprintf_event(sfdbg, 6, "pmu_enable: es=%i cs=%i ed=%i cd=%i "
926                             "tear=%p dear=%p\n", cpuhw->lsctl.es, cpuhw->lsctl.cs,
927                             cpuhw->lsctl.ed, cpuhw->lsctl.cd,
928                             (void *) cpuhw->lsctl.tear, (void *) cpuhw->lsctl.dear);
929 }
930 
931 static void cpumsf_pmu_disable(struct pmu *pmu)
932 {
933         struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
934         struct hws_lsctl_request_block inactive;
935         struct hws_qsi_info_block si;
936         int err;
937 
938         if (!(cpuhw->flags & PMU_F_ENABLED))
939                 return;
940 
941         if (cpuhw->flags & PMU_F_ERR_MASK)
942                 return;
943 
944         /* Switch off sampling activation control */
945         inactive = cpuhw->lsctl;
946         inactive.cs = 0;
947         inactive.cd = 0;
948 
949         err = lsctl(&inactive);
950         if (err) {
951                 pr_err("Loading sampling controls failed: op=%i err=%i\n",
952                         2, err);
953                 return;
954         }
955 
956         /* Save state of TEAR and DEAR register contents */
957         if (!qsi(&si)) {
958                 /* TEAR/DEAR values are valid only if the sampling facility is
959                  * enabled.  Note that cpumsf_pmu_disable() might be called even
960                  * for a disabled sampling facility because cpumsf_pmu_enable()
961                  * controls the enable/disable state.
962                  */
963                 if (si.es) {
964                         cpuhw->lsctl.tear = si.tear;
965                         cpuhw->lsctl.dear = si.dear;
966                 }
967         } else
968                 debug_sprintf_event(sfdbg, 3, "cpumsf_pmu_disable: "
969                                     "qsi() failed with err=%i\n", err);
970 
971         cpuhw->flags &= ~PMU_F_ENABLED;
972 }
973 
974 /* perf_exclude_event() - Filter event
975  * @event:      The perf event
976  * @regs:       pt_regs structure
977  * @sde_regs:   Sample-data-entry (sde) regs structure
978  *
979  * Filter perf events according to their exclude specification.
980  *
981  * Return non-zero if the event shall be excluded.
982  */
983 static int perf_exclude_event(struct perf_event *event, struct pt_regs *regs,
984                               struct perf_sf_sde_regs *sde_regs)
985 {
986         if (event->attr.exclude_user && user_mode(regs))
987                 return 1;
988         if (event->attr.exclude_kernel && !user_mode(regs))
989                 return 1;
990         if (event->attr.exclude_guest && sde_regs->in_guest)
991                 return 1;
992         if (event->attr.exclude_host && !sde_regs->in_guest)
993                 return 1;
994         return 0;
995 }
996 
997 /* perf_push_sample() - Push samples to perf
998  * @event:      The perf event
999  * @sample:     Hardware sample data
1000  *
1001  * Use the hardware sample data to create perf event sample.  The sample
1002  * is the pushed to the event subsystem and the function checks for
1003  * possible event overflows.  If an event overflow occurs, the PMU is
1004  * stopped.
1005  *
1006  * Return non-zero if an event overflow occurred.
1007  */
1008 static int perf_push_sample(struct perf_event *event,
1009                             struct hws_basic_entry *basic)
1010 {
1011         int overflow;
1012         struct pt_regs regs;
1013         struct perf_sf_sde_regs *sde_regs;
1014         struct perf_sample_data data;
1015 
1016         /* Setup perf sample */
1017         perf_sample_data_init(&data, 0, event->hw.last_period);
1018 
1019         /* Setup pt_regs to look like an CPU-measurement external interrupt
1020          * using the Program Request Alert code.  The regs.int_parm_long
1021          * field which is unused contains additional sample-data-entry related
1022          * indicators.
1023          */
1024         memset(&regs, 0, sizeof(regs));
1025         regs.int_code = 0x1407;
1026         regs.int_parm = CPU_MF_INT_SF_PRA;
1027         sde_regs = (struct perf_sf_sde_regs *) &regs.int_parm_long;
1028 
1029         psw_bits(regs.psw).ia   = basic->ia;
1030         psw_bits(regs.psw).dat  = basic->T;
1031         psw_bits(regs.psw).wait = basic->W;
1032         psw_bits(regs.psw).pstate = basic->P;
1033         psw_bits(regs.psw).as   = basic->AS;
1034 
1035         /*
1036          * Use the hardware provided configuration level to decide if the
1037          * sample belongs to a guest or host. If that is not available,
1038          * fall back to the following heuristics:
1039          * A non-zero guest program parameter always indicates a guest
1040          * sample. Some early samples or samples from guests without
1041          * lpp usage would be misaccounted to the host. We use the asn
1042          * value as an addon heuristic to detect most of these guest samples.
1043          * If the value differs from 0xffff (the host value), we assume to
1044          * be a KVM guest.
1045          */
1046         switch (basic->CL) {
1047         case 1: /* logical partition */
1048                 sde_regs->in_guest = 0;
1049                 break;
1050         case 2: /* virtual machine */
1051                 sde_regs->in_guest = 1;
1052                 break;
1053         default: /* old machine, use heuristics */
1054                 if (basic->gpp || basic->prim_asn != 0xffff)
1055                         sde_regs->in_guest = 1;
1056                 break;
1057         }
1058 
1059         /*
1060          * Store the PID value from the sample-data-entry to be
1061          * processed and resolved by cpumsf_output_event_pid().
1062          */
1063         data.tid_entry.pid = basic->hpp & LPP_PID_MASK;
1064 
1065         overflow = 0;
1066         if (perf_exclude_event(event, &regs, sde_regs))
1067                 goto out;
1068         if (perf_event_overflow(event, &data, &regs)) {
1069                 overflow = 1;
1070                 event->pmu->stop(event, 0);
1071         }
1072         perf_event_update_userpage(event);
1073 out:
1074         return overflow;
1075 }
1076 
1077 static void perf_event_count_update(struct perf_event *event, u64 count)
1078 {
1079         local64_add(count, &event->count);
1080 }
1081 
1082 static void debug_sample_entry(struct hws_basic_entry *sample,
1083                                struct hws_trailer_entry *te)
1084 {
1085         debug_sprintf_event(sfdbg, 4, "hw_collect_samples: Found unknown "
1086                             "sampling data entry: te->f=%i basic.def=%04x (%p)\n",
1087                             te->f, sample->def, sample);
1088 }
1089 
1090 /* hw_collect_samples() - Walk through a sample-data-block and collect samples
1091  * @event:      The perf event
1092  * @sdbt:       Sample-data-block table
1093  * @overflow:   Event overflow counter
1094  *
1095  * Walks through a sample-data-block and collects sampling data entries that are
1096  * then pushed to the perf event subsystem.  Depending on the sampling function,
1097  * there can be either basic-sampling or combined-sampling data entries.  A
1098  * combined-sampling data entry consists of a basic- and a diagnostic-sampling
1099  * data entry.  The sampling function is determined by the flags in the perf
1100  * event hardware structure.  The function always works with a combined-sampling
1101  * data entry but ignores the the diagnostic portion if it is not available.
1102  *
1103  * Note that the implementation focuses on basic-sampling data entries and, if
1104  * such an entry is not valid, the entire combined-sampling data entry is
1105  * ignored.
1106  *
1107  * The overflow variables counts the number of samples that has been discarded
1108  * due to a perf event overflow.
1109  */
1110 static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
1111                                unsigned long long *overflow)
1112 {
1113         struct hws_trailer_entry *te;
1114         struct hws_basic_entry *sample;
1115 
1116         te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);
1117         sample = (struct hws_basic_entry *) *sdbt;
1118         while ((unsigned long *) sample < (unsigned long *) te) {
1119                 /* Check for an empty sample */
1120                 if (!sample->def)
1121                         break;
1122 
1123                 /* Update perf event period */
1124                 perf_event_count_update(event, SAMPL_RATE(&event->hw));
1125 
1126                 /* Check whether sample is valid */
1127                 if (sample->def == 0x0001) {
1128                         /* If an event overflow occurred, the PMU is stopped to
1129                          * throttle event delivery.  Remaining sample data is
1130                          * discarded.
1131                          */
1132                         if (!*overflow) {
1133                                 /* Check whether sample is consistent */
1134                                 if (sample->I == 0 && sample->W == 0) {
1135                                         /* Deliver sample data to perf */
1136                                         *overflow = perf_push_sample(event,
1137                                                                      sample);
1138                                 }
1139                         } else
1140                                 /* Count discarded samples */
1141                                 *overflow += 1;
1142                 } else {
1143                         debug_sample_entry(sample, te);
1144                         /* Sample slot is not yet written or other record.
1145                          *
1146                          * This condition can occur if the buffer was reused
1147                          * from a combined basic- and diagnostic-sampling.
1148                          * If only basic-sampling is then active, entries are
1149                          * written into the larger diagnostic entries.
1150                          * This is typically the case for sample-data-blocks
1151                          * that are not full.  Stop processing if the first
1152                          * invalid format was detected.
1153                          */
1154                         if (!te->f)
1155                                 break;
1156                 }
1157 
1158                 /* Reset sample slot and advance to next sample */
1159                 sample->def = 0;
1160                 sample++;
1161         }
1162 }
1163 
1164 /* hw_perf_event_update() - Process sampling buffer
1165  * @event:      The perf event
1166  * @flush_all:  Flag to also flush partially filled sample-data-blocks
1167  *
1168  * Processes the sampling buffer and create perf event samples.
1169  * The sampling buffer position are retrieved and saved in the TEAR_REG
1170  * register of the specified perf event.
1171  *
1172  * Only full sample-data-blocks are processed.  Specify the flash_all flag
1173  * to also walk through partially filled sample-data-blocks.  It is ignored
1174  * if PERF_CPUM_SF_FULL_BLOCKS is set.  The PERF_CPUM_SF_FULL_BLOCKS flag
1175  * enforces the processing of full sample-data-blocks only (trailer entries
1176  * with the block-full-indicator bit set).
1177  */
1178 static void hw_perf_event_update(struct perf_event *event, int flush_all)
1179 {
1180         struct hw_perf_event *hwc = &event->hw;
1181         struct hws_trailer_entry *te;
1182         unsigned long *sdbt;
1183         unsigned long long event_overflow, sampl_overflow, num_sdb, te_flags;
1184         int done;
1185 
1186         /*
1187          * AUX buffer is used when in diagnostic sampling mode.
1188          * No perf events/samples are created.
1189          */
1190         if (SAMPL_DIAG_MODE(&event->hw))
1191                 return;
1192 
1193         if (flush_all && SDB_FULL_BLOCKS(hwc))
1194                 flush_all = 0;
1195 
1196         sdbt = (unsigned long *) TEAR_REG(hwc);
1197         done = event_overflow = sampl_overflow = num_sdb = 0;
1198         while (!done) {
1199                 /* Get the trailer entry of the sample-data-block */
1200                 te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);
1201 
1202                 /* Leave loop if no more work to do (block full indicator) */
1203                 if (!te->f) {
1204                         done = 1;
1205                         if (!flush_all)
1206                                 break;
1207                 }
1208 
1209                 /* Check the sample overflow count */
1210                 if (te->overflow)
1211                         /* Account sample overflows and, if a particular limit
1212                          * is reached, extend the sampling buffer.
1213                          * For details, see sfb_account_overflows().
1214                          */
1215                         sampl_overflow += te->overflow;
1216 
1217                 /* Timestamps are valid for full sample-data-blocks only */
1218                 debug_sprintf_event(sfdbg, 6, "hw_perf_event_update: sdbt=%p "
1219                                     "overflow=%llu timestamp=0x%llx\n",
1220                                     sdbt, te->overflow,
1221                                     (te->f) ? trailer_timestamp(te) : 0ULL);
1222 
1223                 /* Collect all samples from a single sample-data-block and
1224                  * flag if an (perf) event overflow happened.  If so, the PMU
1225                  * is stopped and remaining samples will be discarded.
1226                  */
1227                 hw_collect_samples(event, sdbt, &event_overflow);
1228                 num_sdb++;
1229 
1230                 /* Reset trailer (using compare-double-and-swap) */
1231                 do {
1232                         te_flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
1233                         te_flags |= SDB_TE_ALERT_REQ_MASK;
1234                 } while (!cmpxchg_double(&te->flags, &te->overflow,
1235                                          te->flags, te->overflow,
1236                                          te_flags, 0ULL));
1237 
1238                 /* Advance to next sample-data-block */
1239                 sdbt++;
1240                 if (is_link_entry(sdbt))
1241                         sdbt = get_next_sdbt(sdbt);
1242 
1243                 /* Update event hardware registers */
1244                 TEAR_REG(hwc) = (unsigned long) sdbt;
1245 
1246                 /* Stop processing sample-data if all samples of the current
1247                  * sample-data-block were flushed even if it was not full.
1248                  */
1249                 if (flush_all && done)
1250                         break;
1251 
1252                 /* If an event overflow happened, discard samples by
1253                  * processing any remaining sample-data-blocks.
1254                  */
1255                 if (event_overflow)
1256                         flush_all = 1;
1257         }
1258 
1259         /* Account sample overflows in the event hardware structure */
1260         if (sampl_overflow)
1261                 OVERFLOW_REG(hwc) = DIV_ROUND_UP(OVERFLOW_REG(hwc) +
1262                                                  sampl_overflow, 1 + num_sdb);
1263         if (sampl_overflow || event_overflow)
1264                 debug_sprintf_event(sfdbg, 4, "hw_perf_event_update: "
1265                                     "overflow stats: sample=%llu event=%llu\n",
1266                                     sampl_overflow, event_overflow);
1267 }
1268 
1269 #define AUX_SDB_INDEX(aux, i) ((i) % aux->sfb.num_sdb)
1270 #define AUX_SDB_NUM(aux, start, end) (end >= start ? end - start + 1 : 0)
1271 #define AUX_SDB_NUM_ALERT(aux) AUX_SDB_NUM(aux, aux->head, aux->alert_mark)
1272 #define AUX_SDB_NUM_EMPTY(aux) AUX_SDB_NUM(aux, aux->head, aux->empty_mark)
1273 
1274 /*
1275  * Get trailer entry by index of SDB.
1276  */
1277 static struct hws_trailer_entry *aux_sdb_trailer(struct aux_buffer *aux,
1278                                                  unsigned long index)
1279 {
1280         unsigned long sdb;
1281 
1282         index = AUX_SDB_INDEX(aux, index);
1283         sdb = aux->sdb_index[index];
1284         return (struct hws_trailer_entry *)trailer_entry_ptr(sdb);
1285 }
1286 
1287 /*
1288  * Finish sampling on the cpu. Called by cpumsf_pmu_del() with pmu
1289  * disabled. Collect the full SDBs in AUX buffer which have not reached
1290  * the point of alert indicator. And ignore the SDBs which are not
1291  * full.
1292  *
1293  * 1. Scan SDBs to see how much data is there and consume them.
1294  * 2. Remove alert indicator in the buffer.
1295  */
1296 static void aux_output_end(struct perf_output_handle *handle)
1297 {
1298         unsigned long i, range_scan, idx;
1299         struct aux_buffer *aux;
1300         struct hws_trailer_entry *te;
1301 
1302         aux = perf_get_aux(handle);
1303         if (!aux)
1304                 return;
1305 
1306         range_scan = AUX_SDB_NUM_ALERT(aux);
1307         for (i = 0, idx = aux->head; i < range_scan; i++, idx++) {
1308                 te = aux_sdb_trailer(aux, idx);
1309                 if (!(te->flags & SDB_TE_BUFFER_FULL_MASK))
1310                         break;
1311         }
1312         /* i is num of SDBs which are full */
1313         perf_aux_output_end(handle, i << PAGE_SHIFT);
1314 
1315         /* Remove alert indicators in the buffer */
1316         te = aux_sdb_trailer(aux, aux->alert_mark);
1317         te->flags &= ~SDB_TE_ALERT_REQ_MASK;
1318 
1319         debug_sprintf_event(sfdbg, 6, "aux_output_end: collect %lx SDBs\n", i);
1320 }
1321 
1322 /*
1323  * Start sampling on the CPU. Called by cpumsf_pmu_add() when an event
1324  * is first added to the CPU or rescheduled again to the CPU. It is called
1325  * with pmu disabled.
1326  *
1327  * 1. Reset the trailer of SDBs to get ready for new data.
1328  * 2. Tell the hardware where to put the data by reset the SDBs buffer
1329  *    head(tear/dear).
1330  */
1331 static int aux_output_begin(struct perf_output_handle *handle,
1332                             struct aux_buffer *aux,
1333                             struct cpu_hw_sf *cpuhw)
1334 {
1335         unsigned long range;
1336         unsigned long i, range_scan, idx;
1337         unsigned long head, base, offset;
1338         struct hws_trailer_entry *te;
1339 
1340         if (WARN_ON_ONCE(handle->head & ~PAGE_MASK))
1341                 return -EINVAL;
1342 
1343         aux->head = handle->head >> PAGE_SHIFT;
1344         range = (handle->size + 1) >> PAGE_SHIFT;
1345         if (range <= 1)
1346                 return -ENOMEM;
1347 
1348         /*
1349          * SDBs between aux->head and aux->empty_mark are already ready
1350          * for new data. range_scan is num of SDBs not within them.
1351          */
1352         if (range > AUX_SDB_NUM_EMPTY(aux)) {
1353                 range_scan = range - AUX_SDB_NUM_EMPTY(aux);
1354                 idx = aux->empty_mark + 1;
1355                 for (i = 0; i < range_scan; i++, idx++) {
1356                         te = aux_sdb_trailer(aux, idx);
1357                         te->flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
1358                         te->flags = te->flags & ~SDB_TE_ALERT_REQ_MASK;
1359                         te->overflow = 0;
1360                 }
1361                 /* Save the position of empty SDBs */
1362                 aux->empty_mark = aux->head + range - 1;
1363         }
1364 
1365         /* Set alert indicator */
1366         aux->alert_mark = aux->head + range/2 - 1;
1367         te = aux_sdb_trailer(aux, aux->alert_mark);
1368         te->flags = te->flags | SDB_TE_ALERT_REQ_MASK;
1369 
1370         /* Reset hardware buffer head */
1371         head = AUX_SDB_INDEX(aux, aux->head);
1372         base = aux->sdbt_index[head / CPUM_SF_SDB_PER_TABLE];
1373         offset = head % CPUM_SF_SDB_PER_TABLE;
1374         cpuhw->lsctl.tear = base + offset * sizeof(unsigned long);
1375         cpuhw->lsctl.dear = aux->sdb_index[head];
1376 
1377         debug_sprintf_event(sfdbg, 6, "aux_output_begin: "
1378                             "head->alert_mark->empty_mark (num_alert, range)"
1379                             "[%lx -> %lx -> %lx] (%lx, %lx) "
1380                             "tear index %lx, tear %lx dear %lx\n",
1381                             aux->head, aux->alert_mark, aux->empty_mark,
1382                             AUX_SDB_NUM_ALERT(aux), range,
1383                             head / CPUM_SF_SDB_PER_TABLE,
1384                             cpuhw->lsctl.tear,
1385                             cpuhw->lsctl.dear);
1386 
1387         return 0;
1388 }
1389 
1390 /*
1391  * Set alert indicator on SDB at index @alert_index while sampler is running.
1392  *
1393  * Return true if successfully.
1394  * Return false if full indicator is already set by hardware sampler.
1395  */
1396 static bool aux_set_alert(struct aux_buffer *aux, unsigned long alert_index,
1397                           unsigned long long *overflow)
1398 {
1399         unsigned long long orig_overflow, orig_flags, new_flags;
1400         struct hws_trailer_entry *te;
1401 
1402         te = aux_sdb_trailer(aux, alert_index);
1403         do {
1404                 orig_flags = te->flags;
1405                 orig_overflow = te->overflow;
1406                 *overflow = orig_overflow;
1407                 if (orig_flags & SDB_TE_BUFFER_FULL_MASK) {
1408                         /*
1409                          * SDB is already set by hardware.
1410                          * Abort and try to set somewhere
1411                          * behind.
1412                          */
1413                         return false;
1414                 }
1415                 new_flags = orig_flags | SDB_TE_ALERT_REQ_MASK;
1416         } while (!cmpxchg_double(&te->flags, &te->overflow,
1417                                  orig_flags, orig_overflow,
1418                                  new_flags, 0ULL));
1419         return true;
1420 }
1421 
1422 /*
1423  * aux_reset_buffer() - Scan and setup SDBs for new samples
1424  * @aux:        The AUX buffer to set
1425  * @range:      The range of SDBs to scan started from aux->head
1426  * @overflow:   Set to overflow count
1427  *
1428  * Set alert indicator on the SDB at index of aux->alert_mark. If this SDB is
1429  * marked as empty, check if it is already set full by the hardware sampler.
1430  * If yes, that means new data is already there before we can set an alert
1431  * indicator. Caller should try to set alert indicator to some position behind.
1432  *
1433  * Scan the SDBs in AUX buffer from behind aux->empty_mark. They are used
1434  * previously and have already been consumed by user space. Reset these SDBs
1435  * (clear full indicator and alert indicator) for new data.
1436  * If aux->alert_mark fall in this area, just set it. Overflow count is
1437  * recorded while scanning.
1438  *
1439  * SDBs between aux->head and aux->empty_mark are already reset at last time.
1440  * and ready for new samples. So scanning on this area could be skipped.
1441  *
1442  * Return true if alert indicator is set successfully and false if not.
1443  */
1444 static bool aux_reset_buffer(struct aux_buffer *aux, unsigned long range,
1445                              unsigned long long *overflow)
1446 {
1447         unsigned long long orig_overflow, orig_flags, new_flags;
1448         unsigned long i, range_scan, idx;
1449         struct hws_trailer_entry *te;
1450 
1451         if (range <= AUX_SDB_NUM_EMPTY(aux))
1452                 /*
1453                  * No need to scan. All SDBs in range are marked as empty.
1454                  * Just set alert indicator. Should check race with hardware
1455                  * sampler.
1456                  */
1457                 return aux_set_alert(aux, aux->alert_mark, overflow);
1458 
1459         if (aux->alert_mark <= aux->empty_mark)
1460                 /*
1461                  * Set alert indicator on empty SDB. Should check race
1462                  * with hardware sampler.
1463                  */
1464                 if (!aux_set_alert(aux, aux->alert_mark, overflow))
1465                         return false;
1466 
1467         /*
1468          * Scan the SDBs to clear full and alert indicator used previously.
1469          * Start scanning from one SDB behind empty_mark. If the new alert
1470          * indicator fall into this range, set it.
1471          */
1472         range_scan = range - AUX_SDB_NUM_EMPTY(aux);
1473         idx = aux->empty_mark + 1;
1474         for (i = 0; i < range_scan; i++, idx++) {
1475                 te = aux_sdb_trailer(aux, idx);
1476                 do {
1477                         orig_flags = te->flags;
1478                         orig_overflow = te->overflow;
1479                         new_flags = orig_flags & ~SDB_TE_BUFFER_FULL_MASK;
1480                         if (idx == aux->alert_mark)
1481                                 new_flags |= SDB_TE_ALERT_REQ_MASK;
1482                         else
1483                                 new_flags &= ~SDB_TE_ALERT_REQ_MASK;
1484                 } while (!cmpxchg_double(&te->flags, &te->overflow,
1485                                          orig_flags, orig_overflow,
1486                                          new_flags, 0ULL));
1487                 *overflow += orig_overflow;
1488         }
1489 
1490         /* Update empty_mark to new position */
1491         aux->empty_mark = aux->head + range - 1;
1492 
1493         return true;
1494 }
1495 
1496 /*
1497  * Measurement alert handler for diagnostic mode sampling.
1498  */
1499 static void hw_collect_aux(struct cpu_hw_sf *cpuhw)
1500 {
1501         struct aux_buffer *aux;
1502         int done = 0;
1503         unsigned long range = 0, size;
1504         unsigned long long overflow = 0;
1505         struct perf_output_handle *handle = &cpuhw->handle;
1506         unsigned long num_sdb;
1507 
1508         aux = perf_get_aux(handle);
1509         if (WARN_ON_ONCE(!aux))
1510                 return;
1511 
1512         /* Inform user space new data arrived */
1513         size = AUX_SDB_NUM_ALERT(aux) << PAGE_SHIFT;
1514         perf_aux_output_end(handle, size);
1515         num_sdb = aux->sfb.num_sdb;
1516 
1517         while (!done) {
1518                 /* Get an output handle */
1519                 aux = perf_aux_output_begin(handle, cpuhw->event);
1520                 if (handle->size == 0) {
1521                         pr_err("The AUX buffer with %lu pages for the "
1522                                "diagnostic-sampling mode is full\n",
1523                                 num_sdb);
1524                         debug_sprintf_event(sfdbg, 1, "AUX buffer used up\n");
1525                         break;
1526                 }
1527                 if (WARN_ON_ONCE(!aux))
1528                         return;
1529 
1530                 /* Update head and alert_mark to new position */
1531                 aux->head = handle->head >> PAGE_SHIFT;
1532                 range = (handle->size + 1) >> PAGE_SHIFT;
1533                 if (range == 1)
1534                         aux->alert_mark = aux->head;
1535                 else
1536                         aux->alert_mark = aux->head + range/2 - 1;
1537 
1538                 if (aux_reset_buffer(aux, range, &overflow)) {
1539                         if (!overflow) {
1540                                 done = 1;
1541                                 break;
1542                         }
1543                         size = range << PAGE_SHIFT;
1544                         perf_aux_output_end(&cpuhw->handle, size);
1545                         pr_err("Sample data caused the AUX buffer with %lu "
1546                                "pages to overflow\n", num_sdb);
1547                         debug_sprintf_event(sfdbg, 1, "head %lx range %lx "
1548                                             "overflow %llx\n",
1549                                             aux->head, range, overflow);
1550                 } else {
1551                         size = AUX_SDB_NUM_ALERT(aux) << PAGE_SHIFT;
1552                         perf_aux_output_end(&cpuhw->handle, size);
1553                         debug_sprintf_event(sfdbg, 6, "head %lx alert %lx "
1554                                             "already full, try another\n",
1555                                             aux->head, aux->alert_mark);
1556                 }
1557         }
1558 
1559         if (done)
1560                 debug_sprintf_event(sfdbg, 6, "aux_reset_buffer: "
1561                                     "[%lx -> %lx -> %lx] (%lx, %lx)\n",
1562                                     aux->head, aux->alert_mark, aux->empty_mark,
1563                                     AUX_SDB_NUM_ALERT(aux), range);
1564 }
1565 
1566 /*
1567  * Callback when freeing AUX buffers.
1568  */
1569 static void aux_buffer_free(void *data)
1570 {
1571         struct aux_buffer *aux = data;
1572         unsigned long i, num_sdbt;
1573 
1574         if (!aux)
1575                 return;
1576 
1577         /* Free SDBT. SDB is freed by the caller */
1578         num_sdbt = aux->sfb.num_sdbt;
1579         for (i = 0; i < num_sdbt; i++)
1580                 free_page(aux->sdbt_index[i]);
1581 
1582         kfree(aux->sdbt_index);
1583         kfree(aux->sdb_index);
1584         kfree(aux);
1585 
1586         debug_sprintf_event(sfdbg, 4, "aux_buffer_free: free "
1587                             "%lu SDBTs\n", num_sdbt);
1588 }
1589 
1590 static void aux_sdb_init(unsigned long sdb)
1591 {
1592         struct hws_trailer_entry *te;
1593 
1594         te = (struct hws_trailer_entry *)trailer_entry_ptr(sdb);
1595 
1596         /* Save clock base */
1597         te->clock_base = 1;
1598         memcpy(&te->progusage2, &tod_clock_base[1], 8);
1599 }
1600 
1601 /*
1602  * aux_buffer_setup() - Setup AUX buffer for diagnostic mode sampling
1603  * @event:      Event the buffer is setup for, event->cpu == -1 means current
1604  * @pages:      Array of pointers to buffer pages passed from perf core
1605  * @nr_pages:   Total pages
1606  * @snapshot:   Flag for snapshot mode
1607  *
1608  * This is the callback when setup an event using AUX buffer. Perf tool can
1609  * trigger this by an additional mmap() call on the event. Unlike the buffer
1610  * for basic samples, AUX buffer belongs to the event. It is scheduled with
1611  * the task among online cpus when it is a per-thread event.
1612  *
1613  * Return the private AUX buffer structure if success or NULL if fails.
1614  */
1615 static void *aux_buffer_setup(struct perf_event *event, void **pages,
1616                               int nr_pages, bool snapshot)
1617 {
1618         struct sf_buffer *sfb;
1619         struct aux_buffer *aux;
1620         unsigned long *new, *tail;
1621         int i, n_sdbt;
1622 
1623         if (!nr_pages || !pages)
1624                 return NULL;
1625 
1626         if (nr_pages > CPUM_SF_MAX_SDB * CPUM_SF_SDB_DIAG_FACTOR) {
1627                 pr_err("AUX buffer size (%i pages) is larger than the "
1628                        "maximum sampling buffer limit\n",
1629                        nr_pages);
1630                 return NULL;
1631         } else if (nr_pages < CPUM_SF_MIN_SDB * CPUM_SF_SDB_DIAG_FACTOR) {
1632                 pr_err("AUX buffer size (%i pages) is less than the "
1633                        "minimum sampling buffer limit\n",
1634                        nr_pages);
1635                 return NULL;
1636         }
1637 
1638         /* Allocate aux_buffer struct for the event */
1639         aux = kmalloc(sizeof(struct aux_buffer), GFP_KERNEL);
1640         if (!aux)
1641                 goto no_aux;
1642         sfb = &aux->sfb;
1643 
1644         /* Allocate sdbt_index for fast reference */
1645         n_sdbt = (nr_pages + CPUM_SF_SDB_PER_TABLE - 1) / CPUM_SF_SDB_PER_TABLE;
1646         aux->sdbt_index = kmalloc_array(n_sdbt, sizeof(void *), GFP_KERNEL);
1647         if (!aux->sdbt_index)
1648                 goto no_sdbt_index;
1649 
1650         /* Allocate sdb_index for fast reference */
1651         aux->sdb_index = kmalloc_array(nr_pages, sizeof(void *), GFP_KERNEL);
1652         if (!aux->sdb_index)
1653                 goto no_sdb_index;
1654 
1655         /* Allocate the first SDBT */
1656         sfb->num_sdbt = 0;
1657         sfb->sdbt = (unsigned long *) get_zeroed_page(GFP_KERNEL);
1658         if (!sfb->sdbt)
1659                 goto no_sdbt;
1660         aux->sdbt_index[sfb->num_sdbt++] = (unsigned long)sfb->sdbt;
1661         tail = sfb->tail = sfb->sdbt;
1662 
1663         /*
1664          * Link the provided pages of AUX buffer to SDBT.
1665          * Allocate SDBT if needed.
1666          */
1667         for (i = 0; i < nr_pages; i++, tail++) {
1668                 if (require_table_link(tail)) {
1669                         new = (unsigned long *) get_zeroed_page(GFP_KERNEL);
1670                         if (!new)
1671                                 goto no_sdbt;
1672                         aux->sdbt_index[sfb->num_sdbt++] = (unsigned long)new;
1673                         /* Link current page to tail of chain */
1674                         *tail = (unsigned long)(void *) new + 1;
1675                         tail = new;
1676                 }
1677                 /* Tail is the entry in a SDBT */
1678                 *tail = (unsigned long)pages[i];
1679                 aux->sdb_index[i] = (unsigned long)pages[i];
1680                 aux_sdb_init((unsigned long)pages[i]);
1681         }
1682         sfb->num_sdb = nr_pages;
1683 
1684         /* Link the last entry in the SDBT to the first SDBT */
1685         *tail = (unsigned long) sfb->sdbt + 1;
1686         sfb->tail = tail;
1687 
1688         /*
1689          * Initial all SDBs are zeroed. Mark it as empty.
1690          * So there is no need to clear the full indicator
1691          * when this event is first added.
1692          */
1693         aux->empty_mark = sfb->num_sdb - 1;
1694 
1695         debug_sprintf_event(sfdbg, 4, "aux_buffer_setup: setup %lu SDBTs"
1696                             " and %lu SDBs\n",
1697                             sfb->num_sdbt, sfb->num_sdb);
1698 
1699         return aux;
1700 
1701 no_sdbt:
1702         /* SDBs (AUX buffer pages) are freed by caller */
1703         for (i = 0; i < sfb->num_sdbt; i++)
1704                 free_page(aux->sdbt_index[i]);
1705         kfree(aux->sdb_index);
1706 no_sdb_index:
1707         kfree(aux->sdbt_index);
1708 no_sdbt_index:
1709         kfree(aux);
1710 no_aux:
1711         return NULL;
1712 }
1713 
1714 static void cpumsf_pmu_read(struct perf_event *event)
1715 {
1716         /* Nothing to do ... updates are interrupt-driven */
1717 }
1718 
1719 /* Activate sampling control.
1720  * Next call of pmu_enable() starts sampling.
1721  */
1722 static void cpumsf_pmu_start(struct perf_event *event, int flags)
1723 {
1724         struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
1725 
1726         if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
1727                 return;
1728 
1729         if (flags & PERF_EF_RELOAD)
1730                 WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
1731 
1732         perf_pmu_disable(event->pmu);
1733         event->hw.state = 0;
1734         cpuhw->lsctl.cs = 1;
1735         if (SAMPL_DIAG_MODE(&event->hw))
1736                 cpuhw->lsctl.cd = 1;
1737         perf_pmu_enable(event->pmu);
1738 }
1739 
1740 /* Deactivate sampling control.
1741  * Next call of pmu_enable() stops sampling.
1742  */
1743 static void cpumsf_pmu_stop(struct perf_event *event, int flags)
1744 {
1745         struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
1746 
1747         if (event->hw.state & PERF_HES_STOPPED)
1748                 return;
1749 
1750         perf_pmu_disable(event->pmu);
1751         cpuhw->lsctl.cs = 0;
1752         cpuhw->lsctl.cd = 0;
1753         event->hw.state |= PERF_HES_STOPPED;
1754 
1755         if ((flags & PERF_EF_UPDATE) && !(event->hw.state & PERF_HES_UPTODATE)) {
1756                 hw_perf_event_update(event, 1);
1757                 event->hw.state |= PERF_HES_UPTODATE;
1758         }
1759         perf_pmu_enable(event->pmu);
1760 }
1761 
1762 static int cpumsf_pmu_add(struct perf_event *event, int flags)
1763 {
1764         struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
1765         struct aux_buffer *aux;
1766         int err;
1767 
1768         if (cpuhw->flags & PMU_F_IN_USE)
1769                 return -EAGAIN;
1770 
1771         if (!SAMPL_DIAG_MODE(&event->hw) && !cpuhw->sfb.sdbt)
1772                 return -EINVAL;
1773 
1774         err = 0;
1775         perf_pmu_disable(event->pmu);
1776 
1777         event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
1778 
1779         /* Set up sampling controls.  Always program the sampling register
1780          * using the SDB-table start.  Reset TEAR_REG event hardware register
1781          * that is used by hw_perf_event_update() to store the sampling buffer
1782          * position after samples have been flushed.
1783          */
1784         cpuhw->lsctl.s = 0;
1785         cpuhw->lsctl.h = 1;
1786         cpuhw->lsctl.interval = SAMPL_RATE(&event->hw);
1787         if (!SAMPL_DIAG_MODE(&event->hw)) {
1788                 cpuhw->lsctl.tear = (unsigned long) cpuhw->sfb.sdbt;
1789                 cpuhw->lsctl.dear = *(unsigned long *) cpuhw->sfb.sdbt;
1790                 hw_reset_registers(&event->hw, cpuhw->sfb.sdbt);
1791         }
1792 
1793         /* Ensure sampling functions are in the disabled state.  If disabled,
1794          * switch on sampling enable control. */
1795         if (WARN_ON_ONCE(cpuhw->lsctl.es == 1 || cpuhw->lsctl.ed == 1)) {
1796                 err = -EAGAIN;
1797                 goto out;
1798         }
1799         if (SAMPL_DIAG_MODE(&event->hw)) {
1800                 aux = perf_aux_output_begin(&cpuhw->handle, event);
1801                 if (!aux) {
1802                         err = -EINVAL;
1803                         goto out;
1804                 }
1805                 err = aux_output_begin(&cpuhw->handle, aux, cpuhw);
1806                 if (err)
1807                         goto out;
1808                 cpuhw->lsctl.ed = 1;
1809         }
1810         cpuhw->lsctl.es = 1;
1811 
1812         /* Set in_use flag and store event */
1813         cpuhw->event = event;
1814         cpuhw->flags |= PMU_F_IN_USE;
1815 
1816         if (flags & PERF_EF_START)
1817                 cpumsf_pmu_start(event, PERF_EF_RELOAD);
1818 out:
1819         perf_event_update_userpage(event);
1820         perf_pmu_enable(event->pmu);
1821         return err;
1822 }
1823 
1824 static void cpumsf_pmu_del(struct perf_event *event, int flags)
1825 {
1826         struct cpu_hw_sf *cpuhw = this_cpu_ptr(&cpu_hw_sf);
1827 
1828         perf_pmu_disable(event->pmu);
1829         cpumsf_pmu_stop(event, PERF_EF_UPDATE);
1830 
1831         cpuhw->lsctl.es = 0;
1832         cpuhw->lsctl.ed = 0;
1833         cpuhw->flags &= ~PMU_F_IN_USE;
1834         cpuhw->event = NULL;
1835 
1836         if (SAMPL_DIAG_MODE(&event->hw))
1837                 aux_output_end(&cpuhw->handle);
1838         perf_event_update_userpage(event);
1839         perf_pmu_enable(event->pmu);
1840 }
1841 
1842 CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC, PERF_EVENT_CPUM_SF);
1843 CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC_DIAG, PERF_EVENT_CPUM_SF_DIAG);
1844 
1845 /* Attribute list for CPU_SF.
1846  *
1847  * The availablitiy depends on the CPU_MF sampling facility authorization
1848  * for basic + diagnositic samples. This is determined at initialization
1849  * time by the sampling facility device driver.
1850  * If the authorization for basic samples is turned off, it should be
1851  * also turned off for diagnostic sampling.
1852  *
1853  * During initialization of the device driver, check the authorization
1854  * level for diagnostic sampling and installs the attribute
1855  * file for diagnostic sampling if necessary.
1856  *
1857  * For now install a placeholder to reference all possible attributes:
1858  * SF_CYCLES_BASIC and SF_CYCLES_BASIC_DIAG.
1859  * Add another entry for the final NULL pointer.
1860  */
1861 enum {
1862         SF_CYCLES_BASIC_ATTR_IDX = 0,
1863         SF_CYCLES_BASIC_DIAG_ATTR_IDX,
1864         SF_CYCLES_ATTR_MAX
1865 };
1866 
1867 static struct attribute *cpumsf_pmu_events_attr[SF_CYCLES_ATTR_MAX + 1] = {
1868         [SF_CYCLES_BASIC_ATTR_IDX] = CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC)
1869 };
1870 
1871 PMU_FORMAT_ATTR(event, "config:0-63");
1872 
1873 static struct attribute *cpumsf_pmu_format_attr[] = {
1874         &format_attr_event.attr,
1875         NULL,
1876 };
1877 
1878 static struct attribute_group cpumsf_pmu_events_group = {
1879         .name = "events",
1880         .attrs = cpumsf_pmu_events_attr,
1881 };
1882 static struct attribute_group cpumsf_pmu_format_group = {
1883         .name = "format",
1884         .attrs = cpumsf_pmu_format_attr,
1885 };
1886 static const struct attribute_group *cpumsf_pmu_attr_groups[] = {
1887         &cpumsf_pmu_events_group,
1888         &cpumsf_pmu_format_group,
1889         NULL,
1890 };
1891 
1892 static struct pmu cpumf_sampling = {
1893         .pmu_enable   = cpumsf_pmu_enable,
1894         .pmu_disable  = cpumsf_pmu_disable,
1895 
1896         .event_init   = cpumsf_pmu_event_init,
1897         .add          = cpumsf_pmu_add,
1898         .del          = cpumsf_pmu_del,
1899 
1900         .start        = cpumsf_pmu_start,
1901         .stop         = cpumsf_pmu_stop,
1902         .read         = cpumsf_pmu_read,
1903 
1904         .attr_groups  = cpumsf_pmu_attr_groups,
1905 
1906         .setup_aux    = aux_buffer_setup,
1907         .free_aux     = aux_buffer_free,
1908 };
1909 
1910 static void cpumf_measurement_alert(struct ext_code ext_code,
1911                                     unsigned int alert, unsigned long unused)
1912 {
1913         struct cpu_hw_sf *cpuhw;
1914 
1915         if (!(alert & CPU_MF_INT_SF_MASK))
1916                 return;
1917         inc_irq_stat(IRQEXT_CMS);
1918         cpuhw = this_cpu_ptr(&cpu_hw_sf);
1919 
1920         /* Measurement alerts are shared and might happen when the PMU
1921          * is not reserved.  Ignore these alerts in this case. */
1922         if (!(cpuhw->flags & PMU_F_RESERVED))
1923                 return;
1924 
1925         /* The processing below must take care of multiple alert events that
1926          * might be indicated concurrently. */
1927 
1928         /* Program alert request */
1929         if (alert & CPU_MF_INT_SF_PRA) {
1930                 if (cpuhw->flags & PMU_F_IN_USE)
1931                         if (SAMPL_DIAG_MODE(&cpuhw->event->hw))
1932                                 hw_collect_aux(cpuhw);
1933                         else
1934                                 hw_perf_event_update(cpuhw->event, 0);
1935                 else
1936                         WARN_ON_ONCE(!(cpuhw->flags & PMU_F_IN_USE));
1937         }
1938 
1939         /* Report measurement alerts only for non-PRA codes */
1940         if (alert != CPU_MF_INT_SF_PRA)
1941                 debug_sprintf_event(sfdbg, 6, "measurement alert: 0x%x\n", alert);
1942 
1943         /* Sampling authorization change request */
1944         if (alert & CPU_MF_INT_SF_SACA)
1945                 qsi(&cpuhw->qsi);
1946 
1947         /* Loss of sample data due to high-priority machine activities */
1948         if (alert & CPU_MF_INT_SF_LSDA) {
1949                 pr_err("Sample data was lost\n");
1950                 cpuhw->flags |= PMU_F_ERR_LSDA;
1951                 sf_disable();
1952         }
1953 
1954         /* Invalid sampling buffer entry */
1955         if (alert & (CPU_MF_INT_SF_IAE|CPU_MF_INT_SF_ISE)) {
1956                 pr_err("A sampling buffer entry is incorrect (alert=0x%x)\n",
1957                        alert);
1958                 cpuhw->flags |= PMU_F_ERR_IBE;
1959                 sf_disable();
1960         }
1961 }
1962 static int cpusf_pmu_setup(unsigned int cpu, int flags)
1963 {
1964         /* Ignore the notification if no events are scheduled on the PMU.
1965          * This might be racy...
1966          */
1967         if (!atomic_read(&num_events))
1968                 return 0;
1969 
1970         local_irq_disable();
1971         setup_pmc_cpu(&flags);
1972         local_irq_enable();
1973         return 0;
1974 }
1975 
1976 static int s390_pmu_sf_online_cpu(unsigned int cpu)
1977 {
1978         return cpusf_pmu_setup(cpu, PMC_INIT);
1979 }
1980 
1981 static int s390_pmu_sf_offline_cpu(unsigned int cpu)
1982 {
1983         return cpusf_pmu_setup(cpu, PMC_RELEASE);
1984 }
1985 
1986 static int param_get_sfb_size(char *buffer, const struct kernel_param *kp)
1987 {
1988         if (!cpum_sf_avail())
1989                 return -ENODEV;
1990         return sprintf(buffer, "%lu,%lu", CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB);
1991 }
1992 
1993 static int param_set_sfb_size(const char *val, const struct kernel_param *kp)
1994 {
1995         int rc;
1996         unsigned long min, max;
1997 
1998         if (!cpum_sf_avail())
1999                 return -ENODEV;
2000         if (!val || !strlen(val))
2001                 return -EINVAL;
2002 
2003         /* Valid parameter values: "min,max" or "max" */
2004         min = CPUM_SF_MIN_SDB;
2005         max = CPUM_SF_MAX_SDB;
2006         if (strchr(val, ','))
2007                 rc = (sscanf(val, "%lu,%lu", &min, &max) == 2) ? 0 : -EINVAL;
2008         else
2009                 rc = kstrtoul(val, 10, &max);
2010 
2011         if (min < 2 || min >= max || max > get_num_physpages())
2012                 rc = -EINVAL;
2013         if (rc)
2014                 return rc;
2015 
2016         sfb_set_limits(min, max);
2017         pr_info("The sampling buffer limits have changed to: "
2018                 "min=%lu max=%lu (diag=x%lu)\n",
2019                 CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB, CPUM_SF_SDB_DIAG_FACTOR);
2020         return 0;
2021 }
2022 
2023 #define param_check_sfb_size(name, p) __param_check(name, p, void)
2024 static const struct kernel_param_ops param_ops_sfb_size = {
2025         .set = param_set_sfb_size,
2026         .get = param_get_sfb_size,
2027 };
2028 
2029 #define RS_INIT_FAILURE_QSI       0x0001
2030 #define RS_INIT_FAILURE_BSDES     0x0002
2031 #define RS_INIT_FAILURE_ALRT      0x0003
2032 #define RS_INIT_FAILURE_PERF      0x0004
2033 static void __init pr_cpumsf_err(unsigned int reason)
2034 {
2035         pr_err("Sampling facility support for perf is not available: "
2036                "reason=%04x\n", reason);
2037 }
2038 
2039 static int __init init_cpum_sampling_pmu(void)
2040 {
2041         struct hws_qsi_info_block si;
2042         int err;
2043 
2044         if (!cpum_sf_avail())
2045                 return -ENODEV;
2046 
2047         memset(&si, 0, sizeof(si));
2048         if (qsi(&si)) {
2049                 pr_cpumsf_err(RS_INIT_FAILURE_QSI);
2050                 return -ENODEV;
2051         }
2052 
2053         if (!si.as && !si.ad)
2054                 return -ENODEV;
2055 
2056         if (si.bsdes != sizeof(struct hws_basic_entry)) {
2057                 pr_cpumsf_err(RS_INIT_FAILURE_BSDES);
2058                 return -EINVAL;
2059         }
2060 
2061         if (si.ad) {
2062                 sfb_set_limits(CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB);
2063                 /* Sampling of diagnostic data authorized,
2064                  * install event into attribute list of PMU device.
2065                  */
2066                 cpumsf_pmu_events_attr[SF_CYCLES_BASIC_DIAG_ATTR_IDX] =
2067                         CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC_DIAG);
2068         }
2069 
2070         sfdbg = debug_register(KMSG_COMPONENT, 2, 1, 80);
2071         if (!sfdbg) {
2072                 pr_err("Registering for s390dbf failed\n");
2073                 return -ENOMEM;
2074         }
2075         debug_register_view(sfdbg, &debug_sprintf_view);
2076 
2077         err = register_external_irq(EXT_IRQ_MEASURE_ALERT,
2078                                     cpumf_measurement_alert);
2079         if (err) {
2080                 pr_cpumsf_err(RS_INIT_FAILURE_ALRT);
2081                 debug_unregister(sfdbg);
2082                 goto out;
2083         }
2084 
2085         err = perf_pmu_register(&cpumf_sampling, "cpum_sf", PERF_TYPE_RAW);
2086         if (err) {
2087                 pr_cpumsf_err(RS_INIT_FAILURE_PERF);
2088                 unregister_external_irq(EXT_IRQ_MEASURE_ALERT,
2089                                         cpumf_measurement_alert);
2090                 debug_unregister(sfdbg);
2091                 goto out;
2092         }
2093 
2094         cpuhp_setup_state(CPUHP_AP_PERF_S390_SF_ONLINE, "perf/s390/sf:online",
2095                           s390_pmu_sf_online_cpu, s390_pmu_sf_offline_cpu);
2096 out:
2097         return err;
2098 }
2099 arch_initcall(init_cpum_sampling_pmu);
2100 core_param(cpum_sfb_size, CPUM_SF_MAX_SDB, sfb_size, 0640);
2101 

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