tools/perf/util/cpumap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "util.h"
   3 #include <api/fs/fs.h>
   4 #include "../perf.h"
   5 #include "cpumap.h"
   6 #include <assert.h>
   7 #include <dirent.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <linux/bitmap.h>
  11 #include "asm/bug.h"
  12
  13 #include "sane_ctype.h"
  14
  15 static int max_cpu_num;
  16 static int max_present_cpu_num;
  17 static int max_node_num;
  18 static int *cpunode_map;
  19
  20 static struct cpu_map *cpu_map__default_new(void)
  21 {
  22         struct cpu_map *cpus;
  23         int nr_cpus;
  24
  25         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
  26         if (nr_cpus < 0)
  27                 return NULL;
  28
  29         cpus = malloc(sizeof(*cpus) + nr_cpus * sizeof(int));
  30         if (cpus != NULL) {
  31                 int i;
  32                 for (i = 0; i < nr_cpus; ++i)
  33                         cpus->map[i] = i;
  34
  35                 cpus->nr = nr_cpus;
  36                 refcount_set(&cpus->refcnt, 1);
  37         }
  38
  39         return cpus;
  40 }
  41
  42 static struct cpu_map *cpu_map__trim_new(int nr_cpus, int *tmp_cpus)
  43 {
  44         size_t payload_size = nr_cpus * sizeof(int);
  45         struct cpu_map *cpus = malloc(sizeof(*cpus) + payload_size);
  46
  47         if (cpus != NULL) {
  48                 cpus->nr = nr_cpus;
  49                 memcpy(cpus->map, tmp_cpus, payload_size);
  50                 refcount_set(&cpus->refcnt, 1);
  51         }
  52
  53         return cpus;
  54 }
  55
  56 struct cpu_map *cpu_map__read(FILE *file)
  57 {
  58         struct cpu_map *cpus = NULL;
  59         int nr_cpus = 0;
  60         int *tmp_cpus = NULL, *tmp;
  61         int max_entries = 0;
  62         int n, cpu, prev;
  63         char sep;
  64
  65         sep = 0;
  66         prev = -1;
  67         for (;;) {
  68                 n = fscanf(file, "%u%c", &cpu, &sep);
  69                 if (n <= 0)
  70                         break;
  71                 if (prev >= 0) {
  72                         int new_max = nr_cpus + cpu - prev - 1;
  73
  74                         if (new_max >= max_entries) {
  75                                 max_entries = new_max + MAX_NR_CPUS / 2;
  76                                 tmp = realloc(tmp_cpus, max_entries * sizeof(int));
  77                                 if (tmp == NULL)
  78                                         goto out_free_tmp;
  79                                 tmp_cpus = tmp;
  80                         }
  81
  82                         while (++prev < cpu)
  83                                 tmp_cpus[nr_cpus++] = prev;
  84                 }
  85                 if (nr_cpus == max_entries) {
  86                         max_entries += MAX_NR_CPUS;
  87                         tmp = realloc(tmp_cpus, max_entries * sizeof(int));
  88                         if (tmp == NULL)
  89                                 goto out_free_tmp;
  90                         tmp_cpus = tmp;
  91                 }
  92
  93                 tmp_cpus[nr_cpus++] = cpu;
  94                 if (n == 2 && sep == '-')
  95                         prev = cpu;
  96                 else
  97                         prev = -1;
  98                 if (n == 1 || sep == '\n')
  99                         break;
 100         }
 101
 102         if (nr_cpus > 0)
 103                 cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
 104         else
 105                 cpus = cpu_map__default_new();
 106 out_free_tmp:
 107         free(tmp_cpus);
 108         return cpus;
 109 }
 110
 111 static struct cpu_map *cpu_map__read_all_cpu_map(void)
 112 {
 113         struct cpu_map *cpus = NULL;
 114         FILE *onlnf;
 115
 116         onlnf = fopen("/sys/devices/system/cpu/online", "r");
 117         if (!onlnf)
 118                 return cpu_map__default_new();
 119
 120         cpus = cpu_map__read(onlnf);
 121         fclose(onlnf);
 122         return cpus;
 123 }
 124
 125 struct cpu_map *cpu_map__new(const char *cpu_list)
 126 {
 127         struct cpu_map *cpus = NULL;
 128         unsigned long start_cpu, end_cpu = 0;
 129         char *p = NULL;
 130         int i, nr_cpus = 0;
 131         int *tmp_cpus = NULL, *tmp;
 132         int max_entries = 0;
 133
 134         if (!cpu_list)
 135                 return cpu_map__read_all_cpu_map();
 136
 137         /*
 138          * must handle the case of empty cpumap to cover
 139          * TOPOLOGY header for NUMA nodes with no CPU
 140          * ( e.g., because of CPU hotplug)
 141          */
 142         if (!isdigit(*cpu_list) && *cpu_list != '\0')
 143                 goto out;
 144
 145         while (isdigit(*cpu_list)) {
 146                 p = NULL;
 147                 start_cpu = strtoul(cpu_list, &p, 0);
 148                 if (start_cpu >= INT_MAX
 149                     || (*p != '\0' && *p != ',' && *p != '-'))
 150                         goto invalid;
 151
 152                 if (*p == '-') {
 153                         cpu_list = ++p;
 154                         p = NULL;
 155                         end_cpu = strtoul(cpu_list, &p, 0);
 156
 157                         if (end_cpu >= INT_MAX || (*p != '\0' && *p != ','))
 158                                 goto invalid;
 159
 160                         if (end_cpu < start_cpu)
 161                                 goto invalid;
 162                 } else {
 163                         end_cpu = start_cpu;
 164                 }
 165
 166                 for (; start_cpu <= end_cpu; start_cpu++) {
 167                         /* check for duplicates */
 168                         for (i = 0; i < nr_cpus; i++)
 169                                 if (tmp_cpus[i] == (int)start_cpu)
 170                                         goto invalid;
 171
 172                         if (nr_cpus == max_entries) {
 173                                 max_entries += MAX_NR_CPUS;
 174                                 tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 175                                 if (tmp == NULL)
 176                                         goto invalid;
 177                                 tmp_cpus = tmp;
 178                         }
 179                         tmp_cpus[nr_cpus++] = (int)start_cpu;
 180                 }
 181                 if (*p)
 182                         ++p;
 183
 184                 cpu_list = p;
 185         }
 186
 187         if (nr_cpus > 0)
 188                 cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
 189         else if (*cpu_list != '\0')
 190                 cpus = cpu_map__default_new();
 191         else
 192                 cpus = cpu_map__dummy_new();
 193 invalid:
 194         free(tmp_cpus);
 195 out:
 196         return cpus;
 197 }
 198
 199 static struct cpu_map *cpu_map__from_entries(struct cpu_map_entries *cpus)
 200 {
 201         struct cpu_map *map;
 202
 203         map = cpu_map__empty_new(cpus->nr);
 204         if (map) {
 205                 unsigned i;
 206
 207                 for (i = 0; i < cpus->nr; i++) {
 208                         /*
 209                          * Special treatment for -1, which is not real cpu number,
 210                          * and we need to use (int) -1 to initialize map[i],
 211                          * otherwise it would become 65535.
 212                          */
 213                         if (cpus->cpu[i] == (u16) -1)
 214                                 map->map[i] = -1;
 215                         else
 216                                 map->map[i] = (int) cpus->cpu[i];
 217                 }
 218         }
 219
 220         return map;
 221 }
 222
 223 static struct cpu_map *cpu_map__from_mask(struct cpu_map_mask *mask)
 224 {
 225         struct cpu_map *map;
 226         int nr, nbits = mask->nr * mask->long_size * BITS_PER_BYTE;
 227
 228         nr = bitmap_weight(mask->mask, nbits);
 229
 230         map = cpu_map__empty_new(nr);
 231         if (map) {
 232                 int cpu, i = 0;
 233
 234                 for_each_set_bit(cpu, mask->mask, nbits)
 235                         map->map[i++] = cpu;
 236         }
 237         return map;
 238
 239 }
 240
 241 struct cpu_map *cpu_map__new_data(struct cpu_map_data *data)
 242 {
 243         if (data->type == PERF_CPU_MAP__CPUS)
 244                 return cpu_map__from_entries((struct cpu_map_entries *)data->data);
 245         else
 246                 return cpu_map__from_mask((struct cpu_map_mask *)data->data);
 247 }
 248
 249 size_t cpu_map__fprintf(struct cpu_map *map, FILE *fp)
 250 {
 251 #define BUFSIZE 1024
 252         char buf[BUFSIZE];
 253
 254         cpu_map__snprint(map, buf, sizeof(buf));
 255         return fprintf(fp, "%s\n", buf);
 256 #undef BUFSIZE
 257 }
 258
 259 struct cpu_map *cpu_map__dummy_new(void)
 260 {
 261         struct cpu_map *cpus = malloc(sizeof(*cpus) + sizeof(int));
 262
 263         if (cpus != NULL) {
 264                 cpus->nr = 1;
 265                 cpus->map[0] = -1;
 266                 refcount_set(&cpus->refcnt, 1);
 267         }
 268
 269         return cpus;
 270 }
 271
 272 struct cpu_map *cpu_map__empty_new(int nr)
 273 {
 274         struct cpu_map *cpus = malloc(sizeof(*cpus) + sizeof(int) * nr);
 275
 276         if (cpus != NULL) {
 277                 int i;
 278
 279                 cpus->nr = nr;
 280                 for (i = 0; i < nr; i++)
 281                         cpus->map[i] = -1;
 282
 283                 refcount_set(&cpus->refcnt, 1);
 284         }
 285
 286         return cpus;
 287 }
 288
 289 static void cpu_map__delete(struct cpu_map *map)
 290 {
 291         if (map) {
 292                 WARN_ONCE(refcount_read(&map->refcnt) != 0,
 293                           "cpu_map refcnt unbalanced\n");
 294                 free(map);
 295         }
 296 }
 297
 298 struct cpu_map *cpu_map__get(struct cpu_map *map)
 299 {
 300         if (map)
 301                 refcount_inc(&map->refcnt);
 302         return map;
 303 }
 304
 305 void cpu_map__put(struct cpu_map *map)
 306 {
 307         if (map && refcount_dec_and_test(&map->refcnt))
 308                 cpu_map__delete(map);
 309 }
 310
 311 static int cpu__get_topology_int(int cpu, const char *name, int *value)
 312 {
 313         char path[PATH_MAX];
 314
 315         snprintf(path, PATH_MAX,
 316                 "devices/system/cpu/cpu%d/topology/%s", cpu, name);
 317
 318         return sysfs__read_int(path, value);
 319 }
 320
 321 int cpu_map__get_socket_id(int cpu)
 322 {
 323         int value, ret = cpu__get_topology_int(cpu, "physical_package_id", &value);
 324         return ret ?: value;
 325 }
 326
 327 int cpu_map__get_socket(struct cpu_map *map, int idx, void *data __maybe_unused)
 328 {
 329         int cpu;
 330
 331         if (idx > map->nr)
 332                 return -1;
 333
 334         cpu = map->map[idx];
 335
 336         return cpu_map__get_socket_id(cpu);
 337 }
 338
 339 static int cmp_ids(const void *a, const void *b)
 340 {
 341         return *(int *)a - *(int *)b;
 342 }
 343
 344 int cpu_map__build_map(struct cpu_map *cpus, struct cpu_map **res,
 345                        int (*f)(struct cpu_map *map, int cpu, void *data),
 346                        void *data)
 347 {
 348         struct cpu_map *c;
 349         int nr = cpus->nr;
 350         int cpu, s1, s2;
 351
 352         /* allocate as much as possible */
 353         c = calloc(1, sizeof(*c) + nr * sizeof(int));
 354         if (!c)
 355                 return -1;
 356
 357         for (cpu = 0; cpu < nr; cpu++) {
 358                 s1 = f(cpus, cpu, data);
 359                 for (s2 = 0; s2 < c->nr; s2++) {
 360                         if (s1 == c->map[s2])
 361                                 break;
 362                 }
 363                 if (s2 == c->nr) {
 364                         c->map[c->nr] = s1;
 365                         c->nr++;
 366                 }
 367         }
 368         /* ensure we process id in increasing order */
 369         qsort(c->map, c->nr, sizeof(int), cmp_ids);
 370
 371         refcount_set(&c->refcnt, 1);
 372         *res = c;
 373         return 0;
 374 }
 375
 376 int cpu_map__get_die_id(int cpu)
 377 {
 378         int value, ret = cpu__get_topology_int(cpu, "die_id", &value);
 379
 380         return ret ?: value;
 381 }
 382
 383 int cpu_map__get_die(struct cpu_map *map, int idx, void *data)
 384 {
 385         int cpu, die_id, s;
 386
 387         if (idx > map->nr)
 388                 return -1;
 389
 390         cpu = map->map[idx];
 391
 392         die_id = cpu_map__get_die_id(cpu);
 393         /* There is no die_id on legacy system. */
 394         if (die_id == -1)
 395                 die_id = 0;
 396
 397         s = cpu_map__get_socket(map, idx, data);
 398         if (s == -1)
 399                 return -1;
 400
 401         /*
 402          * Encode socket in bit range 15:8
 403          * die_id is relative to socket, and
 404          * we need a global id. So we combine
 405          * socket + die id
 406          */
 407         if (WARN_ONCE(die_id >> 8, "The die id number is too big.\n"))
 408                 return -1;
 409
 410         if (WARN_ONCE(s >> 8, "The socket id number is too big.\n"))
 411                 return -1;
 412
 413         return (s << 8) | (die_id & 0xff);
 414 }
 415
 416 int cpu_map__get_core_id(int cpu)
 417 {
 418         int value, ret = cpu__get_topology_int(cpu, "core_id", &value);
 419         return ret ?: value;
 420 }
 421
 422 int cpu_map__get_core(struct cpu_map *map, int idx, void *data)
 423 {
 424         int cpu, s_die;
 425
 426         if (idx > map->nr)
 427                 return -1;
 428
 429         cpu = map->map[idx];
 430
 431         cpu = cpu_map__get_core_id(cpu);
 432
 433         /* s_die is the combination of socket + die id */
 434         s_die = cpu_map__get_die(map, idx, data);
 435         if (s_die == -1)
 436                 return -1;
 437
 438         /*
 439          * encode socket in bit range 31:24
 440          * encode die id in bit range 23:16
 441          * core_id is relative to socket and die,
 442          * we need a global id. So we combine
 443          * socket + die id + core id
 444          */
 445         if (WARN_ONCE(cpu >> 16, "The core id number is too big.\n"))
 446                 return -1;
 447
 448         return (s_die << 16) | (cpu & 0xffff);
 449 }
 450
 451 int cpu_map__build_socket_map(struct cpu_map *cpus, struct cpu_map **sockp)
 452 {
 453         return cpu_map__build_map(cpus, sockp, cpu_map__get_socket, NULL);
 454 }
 455
 456 int cpu_map__build_die_map(struct cpu_map *cpus, struct cpu_map **diep)
 457 {
 458         return cpu_map__build_map(cpus, diep, cpu_map__get_die, NULL);
 459 }
 460
 461 int cpu_map__build_core_map(struct cpu_map *cpus, struct cpu_map **corep)
 462 {
 463         return cpu_map__build_map(cpus, corep, cpu_map__get_core, NULL);
 464 }
 465
 466 /* setup simple routines to easily access node numbers given a cpu number */
 467 static int get_max_num(char *path, int *max)
 468 {
 469         size_t num;
 470         char *buf;
 471         int err = 0;
 472
 473         if (filename__read_str(path, &buf, &num))
 474                 return -1;
 475
 476         buf[num] = '\0';
 477
 478         /* start on the right, to find highest node num */
 479         while (--num) {
 480                 if ((buf[num] == ',') || (buf[num] == '-')) {
 481                         num++;
 482                         break;
 483                 }
 484         }
 485         if (sscanf(&buf[num], "%d", max) < 1) {
 486                 err = -1;
 487                 goto out;
 488         }
 489
 490         /* convert from 0-based to 1-based */
 491         (*max)++;
 492
 493 out:
 494         free(buf);
 495         return err;
 496 }
 497
 498 /* Determine highest possible cpu in the system for sparse allocation */
 499 static void set_max_cpu_num(void)
 500 {
 501         const char *mnt;
 502         char path[PATH_MAX];
 503         int ret = -1;
 504
 505         /* set up default */
 506         max_cpu_num = 4096;
 507         max_present_cpu_num = 4096;
 508
 509         mnt = sysfs__mountpoint();
 510         if (!mnt)
 511                 goto out;
 512
 513         /* get the highest possible cpu number for a sparse allocation */
 514         ret = snprintf(path, PATH_MAX, "%s/devices/system/cpu/possible", mnt);
 515         if (ret == PATH_MAX) {
 516                 pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
 517                 goto out;
 518         }
 519
 520         ret = get_max_num(path, &max_cpu_num);
 521         if (ret)
 522                 goto out;
 523
 524         /* get the highest present cpu number for a sparse allocation */
 525         ret = snprintf(path, PATH_MAX, "%s/devices/system/cpu/present", mnt);
 526         if (ret == PATH_MAX) {
 527                 pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
 528                 goto out;
 529         }
 530
 531         ret = get_max_num(path, &max_present_cpu_num);
 532
 533 out:
 534         if (ret)
 535                 pr_err("Failed to read max cpus, using default of %d\n", max_cpu_num);
 536 }
 537
 538 /* Determine highest possible node in the system for sparse allocation */
 539 static void set_max_node_num(void)
 540 {
 541         const char *mnt;
 542         char path[PATH_MAX];
 543         int ret = -1;
 544
 545         /* set up default */
 546         max_node_num = 8;
 547
 548         mnt = sysfs__mountpoint();
 549         if (!mnt)
 550                 goto out;
 551
 552         /* get the highest possible cpu number for a sparse allocation */
 553         ret = snprintf(path, PATH_MAX, "%s/devices/system/node/possible", mnt);
 554         if (ret == PATH_MAX) {
 555                 pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
 556                 goto out;
 557         }
 558
 559         ret = get_max_num(path, &max_node_num);
 560
 561 out:
 562         if (ret)
 563                 pr_err("Failed to read max nodes, using default of %d\n", max_node_num);
 564 }
 565
 566 int cpu__max_node(void)
 567 {
 568         if (unlikely(!max_node_num))
 569                 set_max_node_num();
 570
 571         return max_node_num;
 572 }
 573
 574 int cpu__max_cpu(void)
 575 {
 576         if (unlikely(!max_cpu_num))
 577                 set_max_cpu_num();
 578
 579         return max_cpu_num;
 580 }
 581
 582 int cpu__max_present_cpu(void)
 583 {
 584         if (unlikely(!max_present_cpu_num))
 585                 set_max_cpu_num();
 586
 587         return max_present_cpu_num;
 588 }
 589
 590
 591 int cpu__get_node(int cpu)
 592 {
 593         if (unlikely(cpunode_map == NULL)) {
 594                 pr_debug("cpu_map not initialized\n");
 595                 return -1;
 596         }
 597
 598         return cpunode_map[cpu];
 599 }
 600
 601 static int init_cpunode_map(void)
 602 {
 603         int i;
 604
 605         set_max_cpu_num();
 606         set_max_node_num();
 607
 608         cpunode_map = calloc(max_cpu_num, sizeof(int));
 609         if (!cpunode_map) {
 610                 pr_err("%s: calloc failed\n", __func__);
 611                 return -1;
 612         }
 613
 614         for (i = 0; i < max_cpu_num; i++)
 615                 cpunode_map[i] = -1;
 616
 617         return 0;
 618 }
 619
 620 int cpu__setup_cpunode_map(void)
 621 {
 622         struct dirent *dent1, *dent2;
 623         DIR *dir1, *dir2;
 624         unsigned int cpu, mem;
 625         char buf[PATH_MAX];
 626         char path[PATH_MAX];
 627         const char *mnt;
 628         int n;
 629
 630         /* initialize globals */
 631         if (init_cpunode_map())
 632                 return -1;
 633
 634         mnt = sysfs__mountpoint();
 635         if (!mnt)
 636                 return 0;
 637
 638         n = snprintf(path, PATH_MAX, "%s/devices/system/node", mnt);
 639         if (n == PATH_MAX) {
 640                 pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
 641                 return -1;
 642         }
 643
 644         dir1 = opendir(path);
 645         if (!dir1)
 646                 return 0;
 647
 648         /* walk tree and setup map */
 649         while ((dent1 = readdir(dir1)) != NULL) {
 650                 if (dent1->d_type != DT_DIR || sscanf(dent1->d_name, "node%u", &mem) < 1)
 651                         continue;
 652
 653                 n = snprintf(buf, PATH_MAX, "%s/%s", path, dent1->d_name);
 654                 if (n == PATH_MAX) {
 655                         pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
 656                         continue;
 657                 }
 658
 659                 dir2 = opendir(buf);
 660                 if (!dir2)
 661                         continue;
 662                 while ((dent2 = readdir(dir2)) != NULL) {
 663                         if (dent2->d_type != DT_LNK || sscanf(dent2->d_name, "cpu%u", &cpu) < 1)
 664                                 continue;
 665                         cpunode_map[cpu] = mem;
 666                 }
 667                 closedir(dir2);
 668         }
 669         closedir(dir1);
 670         return 0;
 671 }
 672
 673 bool cpu_map__has(struct cpu_map *cpus, int cpu)
 674 {
 675         return cpu_map__idx(cpus, cpu) != -1;
 676 }
 677
 678 int cpu_map__idx(struct cpu_map *cpus, int cpu)
 679 {
 680         int i;
 681
 682         for (i = 0; i < cpus->nr; ++i) {
 683                 if (cpus->map[i] == cpu)
 684                         return i;
 685         }
 686
 687         return -1;
 688 }
 689
 690 int cpu_map__cpu(struct cpu_map *cpus, int idx)
 691 {
 692         return cpus->map[idx];
 693 }
 694
 695 size_t cpu_map__snprint(struct cpu_map *map, char *buf, size_t size)
 696 {
 697         int i, cpu, start = -1;
 698         bool first = true;
 699         size_t ret = 0;
 700
 701 #define COMMA first ? "" : ","
 702
 703         for (i = 0; i < map->nr + 1; i++) {
 704                 bool last = i == map->nr;
 705
 706                 cpu = last ? INT_MAX : map->map[i];
 707
 708                 if (start == -1) {
 709                         start = i;
 710                         if (last) {
 711                                 ret += snprintf(buf + ret, size - ret,
 712                                                 "%s%d", COMMA,
 713                                                 map->map[i]);
 714                         }
 715                 } else if (((i - start) != (cpu - map->map[start])) || last) {
 716                         int end = i - 1;
 717
 718                         if (start == end) {
 719                                 ret += snprintf(buf + ret, size - ret,
 720                                                 "%s%d", COMMA,
 721                                                 map->map[start]);
 722                         } else {
 723                                 ret += snprintf(buf + ret, size - ret,
 724                                                 "%s%d-%d", COMMA,
 725                                                 map->map[start], map->map[end]);
 726                         }
 727                         first = false;
 728                         start = i;
 729                 }
 730         }
 731
 732 #undef COMMA
 733
 734         pr_debug2("cpumask list: %s\n", buf);
 735         return ret;
 736 }
 737
 738 static char hex_char(unsigned char val)
 739 {
 740         if (val < 10)
 741                 return val + '0';
 742         if (val < 16)
 743                 return val - 10 + 'a';
 744         return '?';
 745 }
 746
 747 size_t cpu_map__snprint_mask(struct cpu_map *map, char *buf, size_t size)
 748 {
 749         int i, cpu;
 750         char *ptr = buf;
 751         unsigned char *bitmap;
 752         int last_cpu = cpu_map__cpu(map, map->nr - 1);
 753
 754         bitmap = zalloc((last_cpu + 7) / 8);
 755         if (bitmap == NULL) {
 756                 buf[0] = '\0';
 757                 return 0;
 758         }
 759
 760         for (i = 0; i < map->nr; i++) {
 761                 cpu = cpu_map__cpu(map, i);
 762                 bitmap[cpu / 8] |= 1 << (cpu % 8);
 763         }
 764
 765         for (cpu = last_cpu / 4 * 4; cpu >= 0; cpu -= 4) {
 766                 unsigned char bits = bitmap[cpu / 8];
 767
 768                 if (cpu % 8)
 769                         bits >>= 4;
 770                 else
 771                         bits &= 0xf;
 772
 773                 *ptr++ = hex_char(bits);
 774                 if ((cpu % 32) == 0 && cpu > 0)
 775                         *ptr++ = ',';
 776         }
 777         *ptr = '\0';
 778         free(bitmap);
 779
 780         buf[size - 1] = '\0';
 781         return ptr - buf;
 782 }
 783
 784 const struct cpu_map *cpu_map__online(void) /* thread unsafe */
 785 {
 786         static const struct cpu_map *online = NULL;
 787
 788         if (!online)
 789                 online = cpu_map__new(NULL); /* from /sys/devices/system/cpu/online */
 790
 791         return online;
 792 }