arch/powerpc/oprofile/cell/spu_task_sync.c

   1 /*
   2  * Cell Broadband Engine OProfile Support
   3  *
   4  * (C) Copyright IBM Corporation 2006
   5  *
   6  * Author: Maynard Johnson <maynardj@us.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the License, or (at your option) any later version.
  12  */
  13
  14 /* The purpose of this file is to handle SPU event task switching
  15  * and to record SPU context information into the OProfile
  16  * event buffer.
  17  *
  18  * Additionally, the spu_sync_buffer function is provided as a helper
  19  * for recoding actual SPU program counter samples to the event buffer.
  20  */
  21 #include <linux/dcookies.h>
  22 #include <linux/kref.h>
  23 #include <linux/mm.h>
  24 #include <linux/fs.h>
  25 #include <linux/module.h>
  26 #include <linux/notifier.h>
  27 #include <linux/numa.h>
  28 #include <linux/oprofile.h>
  29 #include <linux/spinlock.h>
  30 #include "pr_util.h"
  31
  32 #define RELEASE_ALL 9999
  33
  34 static DEFINE_SPINLOCK(buffer_lock);
  35 static DEFINE_SPINLOCK(cache_lock);
  36 static int num_spu_nodes;
  37 int spu_prof_num_nodes;
  38
  39 struct spu_buffer spu_buff[MAX_NUMNODES * SPUS_PER_NODE];
  40 struct delayed_work spu_work;
  41 static unsigned max_spu_buff;
  42
  43 static void spu_buff_add(unsigned long int value, int spu)
  44 {
  45         /* spu buff is a circular buffer.  Add entries to the
  46          * head.  Head is the index to store the next value.
  47          * The buffer is full when there is one available entry
  48          * in the queue, i.e. head and tail can't be equal.
  49          * That way we can tell the difference between the
  50          * buffer being full versus empty.
  51          *
  52          *  ASSUPTION: the buffer_lock is held when this function
  53          *             is called to lock the buffer, head and tail.
  54          */
  55         int full = 1;
  56
  57         if (spu_buff[spu].head >= spu_buff[spu].tail) {
  58                 if ((spu_buff[spu].head - spu_buff[spu].tail)
  59                     <  (max_spu_buff - 1))
  60                         full = 0;
  61
  62         } else if (spu_buff[spu].tail > spu_buff[spu].head) {
  63                 if ((spu_buff[spu].tail - spu_buff[spu].head)
  64                     > 1)
  65                         full = 0;
  66         }
  67
  68         if (!full) {
  69                 spu_buff[spu].buff[spu_buff[spu].head] = value;
  70                 spu_buff[spu].head++;
  71
  72                 if (spu_buff[spu].head >= max_spu_buff)
  73                         spu_buff[spu].head = 0;
  74         } else {
  75                 /* From the user's perspective make the SPU buffer
  76                  * size management/overflow look like we are using
  77                  * per cpu buffers.  The user uses the same
  78                  * per cpu parameter to adjust the SPU buffer size.
  79                  * Increment the sample_lost_overflow to inform
  80                  * the user the buffer size needs to be increased.
  81                  */
  82                 oprofile_cpu_buffer_inc_smpl_lost();
  83         }
  84 }
  85
  86 /* This function copies the per SPU buffers to the
  87  * OProfile kernel buffer.
  88  */
  89 void sync_spu_buff(void)
  90 {
  91         int spu;
  92         unsigned long flags;
  93         int curr_head;
  94
  95         for (spu = 0; spu < num_spu_nodes; spu++) {
  96                 /* In case there was an issue and the buffer didn't
  97                  * get created skip it.
  98                  */
  99                 if (spu_buff[spu].buff == NULL)
 100                         continue;
 101
 102                 /* Hold the lock to make sure the head/tail
 103                  * doesn't change while spu_buff_add() is
 104                  * deciding if the buffer is full or not.
 105                  * Being a little paranoid.
 106                  */
 107                 spin_lock_irqsave(&buffer_lock, flags);
 108                 curr_head = spu_buff[spu].head;
 109                 spin_unlock_irqrestore(&buffer_lock, flags);
 110
 111                 /* Transfer the current contents to the kernel buffer.
 112                  * data can still be added to the head of the buffer.
 113                  */
 114                 oprofile_put_buff(spu_buff[spu].buff,
 115                                   spu_buff[spu].tail,
 116                                   curr_head, max_spu_buff);
 117
 118                 spin_lock_irqsave(&buffer_lock, flags);
 119                 spu_buff[spu].tail = curr_head;
 120                 spin_unlock_irqrestore(&buffer_lock, flags);
 121         }
 122
 123 }
 124
 125 static void wq_sync_spu_buff(struct work_struct *work)
 126 {
 127         /* move data from spu buffers to kernel buffer */
 128         sync_spu_buff();
 129
 130         /* only reschedule if profiling is not done */
 131         if (spu_prof_running)
 132                 schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
 133 }
 134
 135 /* Container for caching information about an active SPU task. */
 136 struct cached_info {
 137         struct vma_to_fileoffset_map *map;
 138         struct spu *the_spu;    /* needed to access pointer to local_store */
 139         struct kref cache_ref;
 140 };
 141
 142 static struct cached_info *spu_info[MAX_NUMNODES * 8];
 143
 144 static void destroy_cached_info(struct kref *kref)
 145 {
 146         struct cached_info *info;
 147
 148         info = container_of(kref, struct cached_info, cache_ref);
 149         vma_map_free(info->map);
 150         kfree(info);
 151         module_put(THIS_MODULE);
 152 }
 153
 154 /* Return the cached_info for the passed SPU number.
 155  * ATTENTION:  Callers are responsible for obtaining the
 156  *             cache_lock if needed prior to invoking this function.
 157  */
 158 static struct cached_info *get_cached_info(struct spu *the_spu, int spu_num)
 159 {
 160         struct kref *ref;
 161         struct cached_info *ret_info;
 162
 163         if (spu_num >= num_spu_nodes) {
 164                 printk(KERN_ERR "SPU_PROF: "
 165                        "%s, line %d: Invalid index %d into spu info cache\n",
 166                        __func__, __LINE__, spu_num);
 167                 ret_info = NULL;
 168                 goto out;
 169         }
 170         if (!spu_info[spu_num] && the_spu) {
 171                 ref = spu_get_profile_private_kref(the_spu->ctx);
 172                 if (ref) {
 173                         spu_info[spu_num] = container_of(ref, struct cached_info, cache_ref);
 174                         kref_get(&spu_info[spu_num]->cache_ref);
 175                 }
 176         }
 177
 178         ret_info = spu_info[spu_num];
 179  out:
 180         return ret_info;
 181 }
 182
 183
 184 /* Looks for cached info for the passed spu.  If not found, the
 185  * cached info is created for the passed spu.
 186  * Returns 0 for success; otherwise, -1 for error.
 187  */
 188 static int
 189 prepare_cached_spu_info(struct spu *spu, unsigned long objectId)
 190 {
 191         unsigned long flags;
 192         struct vma_to_fileoffset_map *new_map;
 193         int retval = 0;
 194         struct cached_info *info;
 195
 196         /* We won't bother getting cache_lock here since
 197          * don't do anything with the cached_info that's returned.
 198          */
 199         info = get_cached_info(spu, spu->number);
 200
 201         if (info) {
 202                 pr_debug("Found cached SPU info.\n");
 203                 goto out;
 204         }
 205
 206         /* Create cached_info and set spu_info[spu->number] to point to it.
 207          * spu->number is a system-wide value, not a per-node value.
 208          */
 209         info = kzalloc(sizeof(struct cached_info), GFP_KERNEL);
 210         if (!info) {
 211                 printk(KERN_ERR "SPU_PROF: "
 212                        "%s, line %d: create vma_map failed\n",
 213                        __func__, __LINE__);
 214                 retval = -ENOMEM;
 215                 goto err_alloc;
 216         }
 217         new_map = create_vma_map(spu, objectId);
 218         if (!new_map) {
 219                 printk(KERN_ERR "SPU_PROF: "
 220                        "%s, line %d: create vma_map failed\n",
 221                        __func__, __LINE__);
 222                 retval = -ENOMEM;
 223                 goto err_alloc;
 224         }
 225
 226         pr_debug("Created vma_map\n");
 227         info->map = new_map;
 228         info->the_spu = spu;
 229         kref_init(&info->cache_ref);
 230         spin_lock_irqsave(&cache_lock, flags);
 231         spu_info[spu->number] = info;
 232         /* Increment count before passing off ref to SPUFS. */
 233         kref_get(&info->cache_ref);
 234
 235         /* We increment the module refcount here since SPUFS is
 236          * responsible for the final destruction of the cached_info,
 237          * and it must be able to access the destroy_cached_info()
 238          * function defined in the OProfile module.  We decrement
 239          * the module refcount in destroy_cached_info.
 240          */
 241         try_module_get(THIS_MODULE);
 242         spu_set_profile_private_kref(spu->ctx, &info->cache_ref,
 243                                 destroy_cached_info);
 244         spin_unlock_irqrestore(&cache_lock, flags);
 245         goto out;
 246
 247 err_alloc:
 248         kfree(info);
 249 out:
 250         return retval;
 251 }
 252
 253 /*
 254  * NOTE:  The caller is responsible for locking the
 255  *        cache_lock prior to calling this function.
 256  */
 257 static int release_cached_info(int spu_index)
 258 {
 259         int index, end;
 260
 261         if (spu_index == RELEASE_ALL) {
 262                 end = num_spu_nodes;
 263                 index = 0;
 264         } else {
 265                 if (spu_index >= num_spu_nodes) {
 266                         printk(KERN_ERR "SPU_PROF: "
 267                                 "%s, line %d: "
 268                                 "Invalid index %d into spu info cache\n",
 269                                 __func__, __LINE__, spu_index);
 270                         goto out;
 271                 }
 272                 end = spu_index + 1;
 273                 index = spu_index;
 274         }
 275         for (; index < end; index++) {
 276                 if (spu_info[index]) {
 277                         kref_put(&spu_info[index]->cache_ref,
 278                                  destroy_cached_info);
 279                         spu_info[index] = NULL;
 280                 }
 281         }
 282
 283 out:
 284         return 0;
 285 }
 286
 287 /* The source code for fast_get_dcookie was "borrowed"
 288  * from drivers/oprofile/buffer_sync.c.
 289  */
 290
 291 /* Optimisation. We can manage without taking the dcookie sem
 292  * because we cannot reach this code without at least one
 293  * dcookie user still being registered (namely, the reader
 294  * of the event buffer).
 295  */
 296 static inline unsigned long fast_get_dcookie(struct path *path)
 297 {
 298         unsigned long cookie;
 299
 300         if (path->dentry->d_flags & DCACHE_COOKIE)
 301                 return (unsigned long)path->dentry;
 302         get_dcookie(path, &cookie);
 303         return cookie;
 304 }
 305
 306 /* Look up the dcookie for the task's first VM_EXECUTABLE mapping,
 307  * which corresponds loosely to "application name". Also, determine
 308  * the offset for the SPU ELF object.  If computed offset is
 309  * non-zero, it implies an embedded SPU object; otherwise, it's a
 310  * separate SPU binary, in which case we retrieve it's dcookie.
 311  * For the embedded case, we must determine if SPU ELF is embedded
 312  * in the executable application or another file (i.e., shared lib).
 313  * If embedded in a shared lib, we must get the dcookie and return
 314  * that to the caller.
 315  */
 316 static unsigned long
 317 get_exec_dcookie_and_offset(struct spu *spu, unsigned int *offsetp,
 318                             unsigned long *spu_bin_dcookie,
 319                             unsigned long spu_ref)
 320 {
 321         unsigned long app_cookie = 0;
 322         unsigned int my_offset = 0;
 323         struct file *app = NULL;
 324         struct vm_area_struct *vma;
 325         struct mm_struct *mm = spu->mm;
 326
 327         if (!mm)
 328                 goto out;
 329
 330         down_read(&mm->mmap_sem);
 331
 332         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 333                 if (!vma->vm_file)
 334                         continue;
 335                 if (!(vma->vm_flags & VM_EXECUTABLE))
 336                         continue;
 337                 app_cookie = fast_get_dcookie(&vma->vm_file->f_path);
 338                 pr_debug("got dcookie for %s\n",
 339                          vma->vm_file->f_dentry->d_name.name);
 340                 app = vma->vm_file;
 341                 break;
 342         }
 343
 344         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 345                 if (vma->vm_start > spu_ref || vma->vm_end <= spu_ref)
 346                         continue;
 347                 my_offset = spu_ref - vma->vm_start;
 348                 if (!vma->vm_file)
 349                         goto fail_no_image_cookie;
 350
 351                 pr_debug("Found spu ELF at %X(object-id:%lx) for file %s\n",
 352                          my_offset, spu_ref,
 353                          vma->vm_file->f_dentry->d_name.name);
 354                 *offsetp = my_offset;
 355                 break;
 356         }
 357
 358         *spu_bin_dcookie = fast_get_dcookie(&vma->vm_file->f_path);
 359         pr_debug("got dcookie for %s\n", vma->vm_file->f_dentry->d_name.name);
 360
 361         up_read(&mm->mmap_sem);
 362
 363 out:
 364         return app_cookie;
 365
 366 fail_no_image_cookie:
 367         up_read(&mm->mmap_sem);
 368
 369         printk(KERN_ERR "SPU_PROF: "
 370                 "%s, line %d: Cannot find dcookie for SPU binary\n",
 371                 __func__, __LINE__);
 372         goto out;
 373 }
 374
 375
 376
 377 /* This function finds or creates cached context information for the
 378  * passed SPU and records SPU context information into the OProfile
 379  * event buffer.
 380  */
 381 static int process_context_switch(struct spu *spu, unsigned long objectId)
 382 {
 383         unsigned long flags;
 384         int retval;
 385         unsigned int offset = 0;
 386         unsigned long spu_cookie = 0, app_dcookie;
 387
 388         retval = prepare_cached_spu_info(spu, objectId);
 389         if (retval)
 390                 goto out;
 391
 392         /* Get dcookie first because a mutex_lock is taken in that
 393          * code path, so interrupts must not be disabled.
 394          */
 395         app_dcookie = get_exec_dcookie_and_offset(spu, &offset, &spu_cookie, objectId);
 396         if (!app_dcookie || !spu_cookie) {
 397                 retval  = -ENOENT;
 398                 goto out;
 399         }
 400
 401         /* Record context info in event buffer */
 402         spin_lock_irqsave(&buffer_lock, flags);
 403         spu_buff_add(ESCAPE_CODE, spu->number);
 404         spu_buff_add(SPU_CTX_SWITCH_CODE, spu->number);
 405         spu_buff_add(spu->number, spu->number);
 406         spu_buff_add(spu->pid, spu->number);
 407         spu_buff_add(spu->tgid, spu->number);
 408         spu_buff_add(app_dcookie, spu->number);
 409         spu_buff_add(spu_cookie, spu->number);
 410         spu_buff_add(offset, spu->number);
 411
 412         /* Set flag to indicate SPU PC data can now be written out.  If
 413          * the SPU program counter data is seen before an SPU context
 414          * record is seen, the postprocessing will fail.
 415          */
 416         spu_buff[spu->number].ctx_sw_seen = 1;
 417
 418         spin_unlock_irqrestore(&buffer_lock, flags);
 419         smp_wmb();      /* insure spu event buffer updates are written */
 420                         /* don't want entries intermingled... */
 421 out:
 422         return retval;
 423 }
 424
 425 /*
 426  * This function is invoked on either a bind_context or unbind_context.
 427  * If called for an unbind_context, the val arg is 0; otherwise,
 428  * it is the object-id value for the spu context.
 429  * The data arg is of type 'struct spu *'.
 430  */
 431 static int spu_active_notify(struct notifier_block *self, unsigned long val,
 432                                 void *data)
 433 {
 434         int retval;
 435         unsigned long flags;
 436         struct spu *the_spu = data;
 437
 438         pr_debug("SPU event notification arrived\n");
 439         if (!val) {
 440                 spin_lock_irqsave(&cache_lock, flags);
 441                 retval = release_cached_info(the_spu->number);
 442                 spin_unlock_irqrestore(&cache_lock, flags);
 443         } else {
 444                 retval = process_context_switch(the_spu, val);
 445         }
 446         return retval;
 447 }
 448
 449 static struct notifier_block spu_active = {
 450         .notifier_call = spu_active_notify,
 451 };
 452
 453 static int number_of_online_nodes(void)
 454 {
 455         u32 cpu; u32 tmp;
 456         int nodes = 0;
 457         for_each_online_cpu(cpu) {
 458                 tmp = cbe_cpu_to_node(cpu) + 1;
 459                 if (tmp > nodes)
 460                         nodes++;
 461         }
 462         return nodes;
 463 }
 464
 465 static int oprofile_spu_buff_create(void)
 466 {
 467         int spu;
 468
 469         max_spu_buff = oprofile_get_cpu_buffer_size();
 470
 471         for (spu = 0; spu < num_spu_nodes; spu++) {
 472                 /* create circular buffers to store the data in.
 473                  * use locks to manage accessing the buffers
 474                  */
 475                 spu_buff[spu].head = 0;
 476                 spu_buff[spu].tail = 0;
 477
 478                 /*
 479                  * Create a buffer for each SPU.  Can't reliably
 480                  * create a single buffer for all spus due to not
 481                  * enough contiguous kernel memory.
 482                  */
 483
 484                 spu_buff[spu].buff = kzalloc((max_spu_buff
 485                                               * sizeof(unsigned long)),
 486                                              GFP_KERNEL);
 487
 488                 if (!spu_buff[spu].buff) {
 489                         printk(KERN_ERR "SPU_PROF: "
 490                                "%s, line %d:  oprofile_spu_buff_create "
 491                        "failed to allocate spu buffer %d.\n",
 492                                __func__, __LINE__, spu);
 493
 494                         /* release the spu buffers that have been allocated */
 495                         while (spu >= 0) {
 496                                 kfree(spu_buff[spu].buff);
 497                                 spu_buff[spu].buff = 0;
 498                                 spu--;
 499                         }
 500                         return -ENOMEM;
 501                 }
 502         }
 503         return 0;
 504 }
 505
 506 /* The main purpose of this function is to synchronize
 507  * OProfile with SPUFS by registering to be notified of
 508  * SPU task switches.
 509  *
 510  * NOTE: When profiling SPUs, we must ensure that only
 511  * spu_sync_start is invoked and not the generic sync_start
 512  * in drivers/oprofile/oprof.c.  A return value of
 513  * SKIP_GENERIC_SYNC or SYNC_START_ERROR will
 514  * accomplish this.
 515  */
 516 int spu_sync_start(void)
 517 {
 518         int spu;
 519         int ret = SKIP_GENERIC_SYNC;
 520         int register_ret;
 521         unsigned long flags = 0;
 522
 523         spu_prof_num_nodes = number_of_online_nodes();
 524         num_spu_nodes = spu_prof_num_nodes * 8;
 525         INIT_DELAYED_WORK(&spu_work, wq_sync_spu_buff);
 526
 527         /* create buffer for storing the SPU data to put in
 528          * the kernel buffer.
 529          */
 530         ret = oprofile_spu_buff_create();
 531         if (ret)
 532                 goto out;
 533
 534         spin_lock_irqsave(&buffer_lock, flags);
 535         for (spu = 0; spu < num_spu_nodes; spu++) {
 536                 spu_buff_add(ESCAPE_CODE, spu);
 537                 spu_buff_add(SPU_PROFILING_CODE, spu);
 538                 spu_buff_add(num_spu_nodes, spu);
 539         }
 540         spin_unlock_irqrestore(&buffer_lock, flags);
 541
 542         for (spu = 0; spu < num_spu_nodes; spu++) {
 543                 spu_buff[spu].ctx_sw_seen = 0;
 544                 spu_buff[spu].last_guard_val = 0;
 545         }
 546
 547         /* Register for SPU events  */
 548         register_ret = spu_switch_event_register(&spu_active);
 549         if (register_ret) {
 550                 ret = SYNC_START_ERROR;
 551                 goto out;
 552         }
 553
 554         pr_debug("spu_sync_start -- running.\n");
 555 out:
 556         return ret;
 557 }
 558
 559 /* Record SPU program counter samples to the oprofile event buffer. */
 560 void spu_sync_buffer(int spu_num, unsigned int *samples,
 561                      int num_samples)
 562 {
 563         unsigned long long file_offset;
 564         unsigned long flags;
 565         int i;
 566         struct vma_to_fileoffset_map *map;
 567         struct spu *the_spu;
 568         unsigned long long spu_num_ll = spu_num;
 569         unsigned long long spu_num_shifted = spu_num_ll << 32;
 570         struct cached_info *c_info;
 571
 572         /* We need to obtain the cache_lock here because it's
 573          * possible that after getting the cached_info, the SPU job
 574          * corresponding to this cached_info may end, thus resulting
 575          * in the destruction of the cached_info.
 576          */
 577         spin_lock_irqsave(&cache_lock, flags);
 578         c_info = get_cached_info(NULL, spu_num);
 579         if (!c_info) {
 580                 /* This legitimately happens when the SPU task ends before all
 581                  * samples are recorded.
 582                  * No big deal -- so we just drop a few samples.
 583                  */
 584                 pr_debug("SPU_PROF: No cached SPU contex "
 585                           "for SPU #%d. Dropping samples.\n", spu_num);
 586                 goto out;
 587         }
 588
 589         map = c_info->map;
 590         the_spu = c_info->the_spu;
 591         spin_lock(&buffer_lock);
 592         for (i = 0; i < num_samples; i++) {
 593                 unsigned int sample = *(samples+i);
 594                 int grd_val = 0;
 595                 file_offset = 0;
 596                 if (sample == 0)
 597                         continue;
 598                 file_offset = vma_map_lookup( map, sample, the_spu, &grd_val);
 599
 600                 /* If overlays are used by this SPU application, the guard
 601                  * value is non-zero, indicating which overlay section is in
 602                  * use.  We need to discard samples taken during the time
 603                  * period which an overlay occurs (i.e., guard value changes).
 604                  */
 605                 if (grd_val && grd_val != spu_buff[spu_num].last_guard_val) {
 606                         spu_buff[spu_num].last_guard_val = grd_val;
 607                         /* Drop the rest of the samples. */
 608                         break;
 609                 }
 610
 611                 /* We must ensure that the SPU context switch has been written
 612                  * out before samples for the SPU.  Otherwise, the SPU context
 613                  * information is not available and the postprocessing of the
 614                  * SPU PC will fail with no available anonymous map information.
 615                  */
 616                 if (spu_buff[spu_num].ctx_sw_seen)
 617                         spu_buff_add((file_offset | spu_num_shifted),
 618                                          spu_num);
 619         }
 620         spin_unlock(&buffer_lock);
 621 out:
 622         spin_unlock_irqrestore(&cache_lock, flags);
 623 }
 624
 625
 626 int spu_sync_stop(void)
 627 {
 628         unsigned long flags = 0;
 629         int ret;
 630         int k;
 631
 632         ret = spu_switch_event_unregister(&spu_active);
 633
 634         if (ret)
 635                 printk(KERN_ERR "SPU_PROF: "
 636                        "%s, line %d: spu_switch_event_unregister "      \
 637                        "returned %d\n",
 638                        __func__, __LINE__, ret);
 639
 640         /* flush any remaining data in the per SPU buffers */
 641         sync_spu_buff();
 642
 643         spin_lock_irqsave(&cache_lock, flags);
 644         ret = release_cached_info(RELEASE_ALL);
 645         spin_unlock_irqrestore(&cache_lock, flags);
 646
 647         /* remove scheduled work queue item rather then waiting
 648          * for every queued entry to execute.  Then flush pending
 649          * system wide buffer to event buffer.
 650          */
 651         cancel_delayed_work(&spu_work);
 652
 653         for (k = 0; k < num_spu_nodes; k++) {
 654                 spu_buff[k].ctx_sw_seen = 0;
 655
 656                 /*
 657                  * spu_sys_buff will be null if there was a problem
 658                  * allocating the buffer.  Only delete if it exists.
 659                  */
 660                 kfree(spu_buff[k].buff);
 661                 spu_buff[k].buff = 0;
 662         }
 663         pr_debug("spu_sync_stop -- done.\n");
 664         return ret;
 665 }
 666