1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 /* ChangeLog for this library: 30 * 31 * NDK r8d: Add android_setCpu(). 32 * 33 * NDK r8c: Add new ARM CPU features: VFPv2, VFP_D32, VFP_FP16, 34 * VFP_FMA, NEON_FMA, IDIV_ARM, IDIV_THUMB2 and iWMMXt. 35 * 36 * Rewrite the code to parse /proc/self/auxv instead of 37 * the "Features" field in /proc/cpuinfo. 38 * 39 * Dynamically allocate the buffer that hold the content 40 * of /proc/cpuinfo to deal with newer hardware. 41 * 42 * NDK r7c: Fix CPU count computation. The old method only reported the 43 * number of _active_ CPUs when the library was initialized, 44 * which could be less than the real total. 45 * 46 * NDK r5: Handle buggy kernels which report a CPU Architecture number of 7 47 * for an ARMv6 CPU (see below). 48 * 49 * Handle kernels that only report 'neon', and not 'vfpv3' 50 * (VFPv3 is mandated by the ARM architecture is Neon is implemented) 51 * 52 * Handle kernels that only report 'vfpv3d16', and not 'vfpv3' 53 * 54 * Fix x86 compilation. Report ANDROID_CPU_FAMILY_X86 in 55 * android_getCpuFamily(). 56 * 57 * NDK r4: Initial release 58 */ 59 #include <sys/system_properties.h> 60 #ifdef __arm__ 61 #include <machine/cpu-features.h> 62 #endif 63 #include <pthread.h> 64 #include "cpu-features.h" 65 #include <stdio.h> 66 #include <stdlib.h> 67 #include <fcntl.h> 68 #include <errno.h> 69 70 static pthread_once_t g_once; 71 static int g_inited; 72 static AndroidCpuFamily g_cpuFamily; 73 static uint64_t g_cpuFeatures; 74 static int g_cpuCount; 75 76 static const int android_cpufeatures_debug = 0; 77 78 #ifdef __arm__ 79 # define DEFAULT_CPU_FAMILY ANDROID_CPU_FAMILY_ARM 80 #elif defined __i386__ 81 # define DEFAULT_CPU_FAMILY ANDROID_CPU_FAMILY_X86 82 #else 83 # define DEFAULT_CPU_FAMILY ANDROID_CPU_FAMILY_UNKNOWN 84 #endif 85 86 #define D(...) \ 87 do { \ 88 if (android_cpufeatures_debug) { \ 89 printf(__VA_ARGS__); fflush(stdout); \ 90 } \ 91 } while (0) 92 93 #ifdef __i386__ 94 static __inline__ void x86_cpuid(int func, int values[4]) 95 { 96 int a, b, c, d; 97 /* We need to preserve ebx since we're compiling PIC code */ 98 /* this means we can't use "=b" for the second output register */ 99 __asm__ __volatile__ ( \ 100 "push %%ebx\n" 101 "cpuid\n" \ 102 "mov %%ebx, %1\n" 103 "pop %%ebx\n" 104 : "=a" (a), "=r" (b), "=c" (c), "=d" (d) \ 105 : "a" (func) \ 106 ); 107 values[0] = a; 108 values[1] = b; 109 values[2] = c; 110 values[3] = d; 111 } 112 #endif 113 114 /* Get the size of a file by reading it until the end. This is needed 115 * because files under /proc do not always return a valid size when 116 * using fseek(0, SEEK_END) + ftell(). Nor can they be mmap()-ed. 117 */ 118 static int 119 get_file_size(const char* pathname) 120 { 121 int fd, ret, result = 0; 122 char buffer[256]; 123 124 fd = open(pathname, O_RDONLY); 125 if (fd < 0) { 126 D("Can't open %s: %s\n", pathname, strerror(errno)); 127 return -1; 128 } 129 130 for (;;) { 131 int ret = read(fd, buffer, sizeof buffer); 132 if (ret < 0) { 133 if (errno == EINTR) 134 continue; 135 D("Error while reading %s: %s\n", pathname, strerror(errno)); 136 break; 137 } 138 if (ret == 0) 139 break; 140 141 result += ret; 142 } 143 close(fd); 144 return result; 145 } 146 147 /* Read the content of /proc/cpuinfo into a user-provided buffer. 148 * Return the length of the data, or -1 on error. Does *not* 149 * zero-terminate the content. Will not read more 150 * than 'buffsize' bytes. 151 */ 152 static int 153 read_file(const char* pathname, char* buffer, size_t buffsize) 154 { 155 int fd, count; 156 157 fd = open(pathname, O_RDONLY); 158 if (fd < 0) { 159 D("Could not open %s: %s\n", pathname, strerror(errno)); 160 return -1; 161 } 162 count = 0; 163 while (count < (int)buffsize) { 164 int ret = read(fd, buffer + count, buffsize - count); 165 if (ret < 0) { 166 if (errno == EINTR) 167 continue; 168 D("Error while reading from %s: %s\n", pathname, strerror(errno)); 169 if (count == 0) 170 count = -1; 171 break; 172 } 173 if (ret == 0) 174 break; 175 count += ret; 176 } 177 close(fd); 178 return count; 179 } 180 181 /* Extract the content of a the first occurence of a given field in 182 * the content of /proc/cpuinfo and return it as a heap-allocated 183 * string that must be freed by the caller. 184 * 185 * Return NULL if not found 186 */ 187 static char* 188 extract_cpuinfo_field(const char* buffer, int buflen, const char* field) 189 { 190 int fieldlen = strlen(field); 191 const char* bufend = buffer + buflen; 192 char* result = NULL; 193 int len, ignore; 194 const char *p, *q; 195 196 /* Look for first field occurence, and ensures it starts the line. */ 197 p = buffer; 198 bufend = buffer + buflen; 199 for (;;) { 200 p = memmem(p, bufend-p, field, fieldlen); 201 if (p == NULL) 202 goto EXIT; 203 204 if (p == buffer || p[-1] == '\n') 205 break; 206 207 p += fieldlen; 208 } 209 210 /* Skip to the first column followed by a space */ 211 p += fieldlen; 212 p = memchr(p, ':', bufend-p); 213 if (p == NULL || p[1] != ' ') 214 goto EXIT; 215 216 /* Find the end of the line */ 217 p += 2; 218 q = memchr(p, '\n', bufend-p); 219 if (q == NULL) 220 q = bufend; 221 222 /* Copy the line into a heap-allocated buffer */ 223 len = q-p; 224 result = malloc(len+1); 225 if (result == NULL) 226 goto EXIT; 227 228 memcpy(result, p, len); 229 result[len] = '\0'; 230 231 EXIT: 232 return result; 233 } 234 235 /* Like strlen(), but for constant string literals */ 236 #define STRLEN_CONST(x) ((sizeof(x)-1) 237 238 239 /* Checks that a space-separated list of items contains one given 'item'. 240 * Returns 1 if found, 0 otherwise. 241 */ 242 static int 243 has_list_item(const char* list, const char* item) 244 { 245 const char* p = list; 246 int itemlen = strlen(item); 247 248 if (list == NULL) 249 return 0; 250 251 while (*p) { 252 const char* q; 253 254 /* skip spaces */ 255 while (*p == ' ' || *p == '\t') 256 p++; 257 258 /* find end of current list item */ 259 q = p; 260 while (*q && *q != ' ' && *q != '\t') 261 q++; 262 263 if (itemlen == q-p && !memcmp(p, item, itemlen)) 264 return 1; 265 266 /* skip to next item */ 267 p = q; 268 } 269 return 0; 270 } 271 272 /* Parse an decimal integer starting from 'input', but not going further 273 * than 'limit'. Return the value into '*result'. 274 * 275 * NOTE: Does not skip over leading spaces, or deal with sign characters. 276 * NOTE: Ignores overflows. 277 * 278 * The function returns NULL in case of error (bad format), or the new 279 * position after the decimal number in case of success (which will always 280 * be <= 'limit'). 281 */ 282 static const char* 283 parse_decimal(const char* input, const char* limit, int* result) 284 { 285 const char* p = input; 286 int val = 0; 287 while (p < limit) { 288 int d = (*p - '0'); 289 if ((unsigned)d >= 10U) 290 break; 291 val = val*10 + d; 292 p++; 293 } 294 if (p == input) 295 return NULL; 296 297 *result = val; 298 return p; 299 } 300 301 /* This small data type is used to represent a CPU list / mask, as read 302 * from sysfs on Linux. See http://www.kernel.org/doc/Documentation/cputopology.txt 303 * 304 * For now, we don't expect more than 32 cores on mobile devices, so keep 305 * everything simple. 306 */ 307 typedef struct { 308 uint32_t mask; 309 } CpuList; 310 311 static __inline__ void 312 cpulist_init(CpuList* list) { 313 list->mask = 0; 314 } 315 316 static __inline__ void 317 cpulist_and(CpuList* list1, CpuList* list2) { 318 list1->mask &= list2->mask; 319 } 320 321 static __inline__ void 322 cpulist_set(CpuList* list, int index) { 323 if ((unsigned)index < 32) { 324 list->mask |= (uint32_t)(1U << index); 325 } 326 } 327 328 static __inline__ int 329 cpulist_count(CpuList* list) { 330 return __builtin_popcount(list->mask); 331 } 332 333 /* Parse a textual list of cpus and store the result inside a CpuList object. 334 * Input format is the following: 335 * - comma-separated list of items (no spaces) 336 * - each item is either a single decimal number (cpu index), or a range made 337 * of two numbers separated by a single dash (-). Ranges are inclusive. 338 * 339 * Examples: 0 340 * 2,4-127,128-143 341 * 0-1 342 */ 343 static void 344 cpulist_parse(CpuList* list, const char* line, int line_len) 345 { 346 const char* p = line; 347 const char* end = p + line_len; 348 const char* q; 349 350 /* NOTE: the input line coming from sysfs typically contains a 351 * trailing newline, so take care of it in the code below 352 */ 353 while (p < end && *p != '\n') 354 { 355 int val, start_value, end_value; 356 357 /* Find the end of current item, and put it into 'q' */ 358 q = memchr(p, ',', end-p); 359 if (q == NULL) { 360 q = end; 361 } 362 363 /* Get first value */ 364 p = parse_decimal(p, q, &start_value); 365 if (p == NULL) 366 goto BAD_FORMAT; 367 368 end_value = start_value; 369 370 /* If we're not at the end of the item, expect a dash and 371 * and integer; extract end value. 372 */ 373 if (p < q && *p == '-') { 374 p = parse_decimal(p+1, q, &end_value); 375 if (p == NULL) 376 goto BAD_FORMAT; 377 } 378 379 /* Set bits CPU list bits */ 380 for (val = start_value; val <= end_value; val++) { 381 cpulist_set(list, val); 382 } 383 384 /* Jump to next item */ 385 p = q; 386 if (p < end) 387 p++; 388 } 389 390 BAD_FORMAT: 391 ; 392 } 393 394 /* Read a CPU list from one sysfs file */ 395 static void 396 cpulist_read_from(CpuList* list, const char* filename) 397 { 398 char file[64]; 399 int filelen; 400 401 cpulist_init(list); 402 403 filelen = read_file(filename, file, sizeof file); 404 if (filelen < 0) { 405 D("Could not read %s: %s\n", filename, strerror(errno)); 406 return; 407 } 408 409 cpulist_parse(list, file, filelen); 410 } 411 412 // See <asm/hwcap.h> kernel header. 413 #define HWCAP_VFP (1 << 6) 414 #define HWCAP_IWMMXT (1 << 9) 415 #define HWCAP_NEON (1 << 12) 416 #define HWCAP_VFPv3 (1 << 13) 417 #define HWCAP_VFPv3D16 (1 << 14) 418 #define HWCAP_VFPv4 (1 << 16) 419 #define HWCAP_IDIVA (1 << 17) 420 #define HWCAP_IDIVT (1 << 18) 421 422 #define AT_HWCAP 16 423 424 #if defined(__arm__) 425 /* Compute the ELF HWCAP flags. 426 */ 427 static uint32_t 428 get_elf_hwcap(const char* cpuinfo, int cpuinfo_len) 429 { 430 /* IMPORTANT: 431 * Accessing /proc/self/auxv doesn't work anymore on all 432 * platform versions. More specifically, when running inside 433 * a regular application process, most of /proc/self/ will be 434 * non-readable, including /proc/self/auxv. This doesn't 435 * happen however if the application is debuggable, or when 436 * running under the "shell" UID, which is why this was not 437 * detected appropriately. 438 */ 439 #if 0 440 uint32_t result = 0; 441 const char filepath[] = "/proc/self/auxv"; 442 int fd = open(filepath, O_RDONLY); 443 if (fd < 0) { 444 D("Could not open %s: %s\n", filepath, strerror(errno)); 445 return 0; 446 } 447 448 struct { uint32_t tag; uint32_t value; } entry; 449 450 for (;;) { 451 int ret = read(fd, (char*)&entry, sizeof entry); 452 if (ret < 0) { 453 if (errno == EINTR) 454 continue; 455 D("Error while reading %s: %s\n", filepath, strerror(errno)); 456 break; 457 } 458 // Detect end of list. 459 if (ret == 0 || (entry.tag == 0 && entry.value == 0)) 460 break; 461 if (entry.tag == AT_HWCAP) { 462 result = entry.value; 463 break; 464 } 465 } 466 close(fd); 467 return result; 468 #else 469 // Recreate ELF hwcaps by parsing /proc/cpuinfo Features tag. 470 uint32_t hwcaps = 0; 471 472 char* cpuFeatures = extract_cpuinfo_field(cpuinfo, cpuinfo_len, "Features"); 473 474 if (cpuFeatures != NULL) { 475 D("Found cpuFeatures = '%s'\n", cpuFeatures); 476 477 if (has_list_item(cpuFeatures, "vfp")) 478 hwcaps |= HWCAP_VFP; 479 if (has_list_item(cpuFeatures, "vfpv3")) 480 hwcaps |= HWCAP_VFPv3; 481 if (has_list_item(cpuFeatures, "vfpv3d16")) 482 hwcaps |= HWCAP_VFPv3D16; 483 if (has_list_item(cpuFeatures, "vfpv4")) 484 hwcaps |= HWCAP_VFPv4; 485 if (has_list_item(cpuFeatures, "neon")) 486 hwcaps |= HWCAP_NEON; 487 if (has_list_item(cpuFeatures, "idiva")) 488 hwcaps |= HWCAP_IDIVA; 489 if (has_list_item(cpuFeatures, "idivt")) 490 hwcaps |= HWCAP_IDIVT; 491 if (has_list_item(cpuFeatures, "idiv")) 492 hwcaps |= HWCAP_IDIVA | HWCAP_IDIVT; 493 if (has_list_item(cpuFeatures, "iwmmxt")) 494 hwcaps |= HWCAP_IWMMXT; 495 496 free(cpuFeatures); 497 } 498 return hwcaps; 499 #endif 500 } 501 #endif /* __arm__ */ 502 503 /* Return the number of cpus present on a given device. 504 * 505 * To handle all weird kernel configurations, we need to compute the 506 * intersection of the 'present' and 'possible' CPU lists and count 507 * the result. 508 */ 509 static int 510 get_cpu_count(void) 511 { 512 CpuList cpus_present[1]; 513 CpuList cpus_possible[1]; 514 515 cpulist_read_from(cpus_present, "/sys/devices/system/cpu/present"); 516 cpulist_read_from(cpus_possible, "/sys/devices/system/cpu/possible"); 517 518 /* Compute the intersection of both sets to get the actual number of 519 * CPU cores that can be used on this device by the kernel. 520 */ 521 cpulist_and(cpus_present, cpus_possible); 522 523 return cpulist_count(cpus_present); 524 } 525 526 static void 527 android_cpuInitFamily(void) 528 { 529 #if defined(__ARM_ARCH__) 530 g_cpuFamily = ANDROID_CPU_FAMILY_ARM; 531 #elif defined(__i386__) 532 g_cpuFamily = ANDROID_CPU_FAMILY_X86; 533 #elif defined(_MIPS_ARCH) 534 g_cpuFamily = ANDROID_CPU_FAMILY_MIPS; 535 #else 536 g_cpuFamily = ANDROID_CPU_FAMILY_UNKNOWN; 537 #endif 538 } 539 540 static void 541 android_cpuInit(void) 542 { 543 char* cpuinfo = NULL; 544 int cpuinfo_len; 545 546 android_cpuInitFamily(); 547 548 g_cpuFeatures = 0; 549 g_cpuCount = 1; 550 g_inited = 1; 551 552 cpuinfo_len = get_file_size("/proc/cpuinfo"); 553 if (cpuinfo_len < 0) { 554 D("cpuinfo_len cannot be computed!"); 555 return; 556 } 557 cpuinfo = malloc(cpuinfo_len); 558 if (cpuinfo == NULL) { 559 D("cpuinfo buffer could not be allocated"); 560 return; 561 } 562 cpuinfo_len = read_file("/proc/cpuinfo", cpuinfo, cpuinfo_len); 563 D("cpuinfo_len is (%d):\n%.*s\n", cpuinfo_len, 564 cpuinfo_len >= 0 ? cpuinfo_len : 0, cpuinfo); 565 566 if (cpuinfo_len < 0) /* should not happen */ { 567 free(cpuinfo); 568 return; 569 } 570 571 /* Count the CPU cores, the value may be 0 for single-core CPUs */ 572 g_cpuCount = get_cpu_count(); 573 if (g_cpuCount == 0) { 574 g_cpuCount = 1; 575 } 576 577 D("found cpuCount = %d\n", g_cpuCount); 578 579 #ifdef __ARM_ARCH__ 580 { 581 char* features = NULL; 582 char* architecture = NULL; 583 584 /* Extract architecture from the "CPU Architecture" field. 585 * The list is well-known, unlike the the output of 586 * the 'Processor' field which can vary greatly. 587 * 588 * See the definition of the 'proc_arch' array in 589 * $KERNEL/arch/arm/kernel/setup.c and the 'c_show' function in 590 * same file. 591 */ 592 char* cpuArch = extract_cpuinfo_field(cpuinfo, cpuinfo_len, "CPU architecture"); 593 594 if (cpuArch != NULL) { 595 char* end; 596 long archNumber; 597 int hasARMv7 = 0; 598 599 D("found cpuArch = '%s'\n", cpuArch); 600 601 /* read the initial decimal number, ignore the rest */ 602 archNumber = strtol(cpuArch, &end, 10); 603 604 /* Here we assume that ARMv8 will be upwards compatible with v7 605 * in the future. Unfortunately, there is no 'Features' field to 606 * indicate that Thumb-2 is supported. 607 */ 608 if (end > cpuArch && archNumber >= 7) { 609 hasARMv7 = 1; 610 } 611 612 /* Unfortunately, it seems that certain ARMv6-based CPUs 613 * report an incorrect architecture number of 7! 614 * 615 * See http://code.google.com/p/android/issues/detail?id=10812 616 * 617 * We try to correct this by looking at the 'elf_format' 618 * field reported by the 'Processor' field, which is of the 619 * form of "(v7l)" for an ARMv7-based CPU, and "(v6l)" for 620 * an ARMv6-one. 621 */ 622 if (hasARMv7) { 623 char* cpuProc = extract_cpuinfo_field(cpuinfo, cpuinfo_len, 624 "Processor"); 625 if (cpuProc != NULL) { 626 D("found cpuProc = '%s'\n", cpuProc); 627 if (has_list_item(cpuProc, "(v6l)")) { 628 D("CPU processor and architecture mismatch!!\n"); 629 hasARMv7 = 0; 630 } 631 free(cpuProc); 632 } 633 } 634 635 if (hasARMv7) { 636 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_ARMv7; 637 } 638 639 /* The LDREX / STREX instructions are available from ARMv6 */ 640 if (archNumber >= 6) { 641 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_LDREX_STREX; 642 } 643 644 free(cpuArch); 645 } 646 647 /* Extract the list of CPU features from ELF hwcaps */ 648 uint32_t hwcaps = get_elf_hwcap(cpuinfo, cpuinfo_len); 649 650 if (hwcaps != 0) { 651 int has_vfp = (hwcaps & HWCAP_VFP); 652 int has_vfpv3 = (hwcaps & HWCAP_VFPv3); 653 int has_vfpv3d16 = (hwcaps & HWCAP_VFPv3D16); 654 int has_vfpv4 = (hwcaps & HWCAP_VFPv4); 655 int has_neon = (hwcaps & HWCAP_NEON); 656 int has_idiva = (hwcaps & HWCAP_IDIVA); 657 int has_idivt = (hwcaps & HWCAP_IDIVT); 658 int has_iwmmxt = (hwcaps & HWCAP_IWMMXT); 659 660 // The kernel does a poor job at ensuring consistency when 661 // describing CPU features. So lots of guessing is needed. 662 663 // 'vfpv4' implies VFPv3|VFP_FMA|FP16 664 if (has_vfpv4) 665 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv3 | 666 ANDROID_CPU_ARM_FEATURE_VFP_FP16 | 667 ANDROID_CPU_ARM_FEATURE_VFP_FMA; 668 669 // 'vfpv3' or 'vfpv3d16' imply VFPv3. Note that unlike GCC, 670 // a value of 'vfpv3' doesn't necessarily mean that the D32 671 // feature is present, so be conservative. All CPUs in the 672 // field that support D32 also support NEON, so this should 673 // not be a problem in practice. 674 if (has_vfpv3 || has_vfpv3d16) 675 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv3; 676 677 // 'vfp' is super ambiguous. Depending on the kernel, it can 678 // either mean VFPv2 or VFPv3. Make it depend on ARMv7. 679 if (has_vfp) { 680 if (g_cpuFeatures & ANDROID_CPU_ARM_FEATURE_ARMv7) 681 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv3; 682 else 683 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv2; 684 } 685 686 // Neon implies VFPv3|D32, and if vfpv4 is detected, NEON_FMA 687 if (has_neon) { 688 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv3 | 689 ANDROID_CPU_ARM_FEATURE_NEON | 690 ANDROID_CPU_ARM_FEATURE_VFP_D32; 691 if (has_vfpv4) 692 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_NEON_FMA; 693 } 694 695 // VFPv3 implies VFPv2 and ARMv7 696 if (g_cpuFeatures & ANDROID_CPU_ARM_FEATURE_VFPv3) 697 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv2 | 698 ANDROID_CPU_ARM_FEATURE_ARMv7; 699 700 // Note that some buggy kernels do not report these even when 701 // the CPU actually support the division instructions. However, 702 // assume that if 'vfpv4' is detected, then the CPU supports 703 // sdiv/udiv properly. 704 if (has_idiva || has_vfpv4) 705 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_IDIV_ARM; 706 if (has_idivt || has_vfpv4) 707 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_IDIV_THUMB2; 708 709 if (has_iwmmxt) 710 g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_iWMMXt; 711 } 712 } 713 #endif /* __ARM_ARCH__ */ 714 715 #ifdef __i386__ 716 int regs[4]; 717 718 /* According to http://en.wikipedia.org/wiki/CPUID */ 719 #define VENDOR_INTEL_b 0x756e6547 720 #define VENDOR_INTEL_c 0x6c65746e 721 #define VENDOR_INTEL_d 0x49656e69 722 723 x86_cpuid(0, regs); 724 int vendorIsIntel = (regs[1] == VENDOR_INTEL_b && 725 regs[2] == VENDOR_INTEL_c && 726 regs[3] == VENDOR_INTEL_d); 727 728 x86_cpuid(1, regs); 729 if ((regs[2] & (1 << 9)) != 0) { 730 g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_SSSE3; 731 } 732 if ((regs[2] & (1 << 23)) != 0) { 733 g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_POPCNT; 734 } 735 if (vendorIsIntel && (regs[2] & (1 << 22)) != 0) { 736 g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_MOVBE; 737 } 738 #endif 739 740 free(cpuinfo); 741 } 742 743 744 AndroidCpuFamily 745 android_getCpuFamily(void) 746 { 747 pthread_once(&g_once, android_cpuInit); 748 return g_cpuFamily; 749 } 750 751 752 uint64_t 753 android_getCpuFeatures(void) 754 { 755 pthread_once(&g_once, android_cpuInit); 756 return g_cpuFeatures; 757 } 758 759 760 int 761 android_getCpuCount(void) 762 { 763 pthread_once(&g_once, android_cpuInit); 764 return g_cpuCount; 765 } 766 767 static void 768 android_cpuInitDummy(void) 769 { 770 g_inited = 1; 771 } 772 773 int 774 android_setCpu(int cpu_count, uint64_t cpu_features) 775 { 776 /* Fail if the library was already initialized. */ 777 if (g_inited) 778 return 0; 779 780 android_cpuInitFamily(); 781 g_cpuCount = (cpu_count <= 0 ? 1 : cpu_count); 782 g_cpuFeatures = cpu_features; 783 pthread_once(&g_once, android_cpuInitDummy); 784 785 return 1; 786 } 787 788 /* 789 * Technical note: Making sense of ARM's FPU architecture versions. 790 * 791 * FPA was ARM's first attempt at an FPU architecture. There is no Android 792 * device that actually uses it since this technology was already obsolete 793 * when the project started. If you see references to FPA instructions 794 * somewhere, you can be sure that this doesn't apply to Android at all. 795 * 796 * FPA was followed by "VFP", soon renamed "VFPv1" due to the emergence of 797 * new versions / additions to it. ARM considers this obsolete right now, 798 * and no known Android device implements it either. 799 * 800 * VFPv2 added a few instructions to VFPv1, and is an *optional* extension 801 * supported by some ARMv5TE, ARMv6 and ARMv6T2 CPUs. Note that a device 802 * supporting the 'armeabi' ABI doesn't necessarily support these. 803 * 804 * VFPv3-D16 adds a few instructions on top of VFPv2 and is typically used 805 * on ARMv7-A CPUs which implement a FPU. Note that it is also mandated 806 * by the Android 'armeabi-v7a' ABI. The -D16 suffix in its name means 807 * that it provides 16 double-precision FPU registers (d0-d15) and 32 808 * single-precision ones (s0-s31) which happen to be mapped to the same 809 * register banks. 810 * 811 * VFPv3-D32 is the name of an extension to VFPv3-D16 that provides 16 812 * additional double precision registers (d16-d31). Note that there are 813 * still only 32 single precision registers. 814 * 815 * VFPv3xD is a *subset* of VFPv3-D16 that only provides single-precision 816 * registers. It is only used on ARMv7-M (i.e. on micro-controllers) which 817 * are not supported by Android. Note that it is not compatible with VFPv2. 818 * 819 * NOTE: The term 'VFPv3' usually designate either VFPv3-D16 or VFPv3-D32 820 * depending on context. For example GCC uses it for VFPv3-D32, but 821 * the Linux kernel code uses it for VFPv3-D16 (especially in 822 * /proc/cpuinfo). Always try to use the full designation when 823 * possible. 824 * 825 * NEON, a.k.a. "ARM Advanced SIMD" is an extension that provides 826 * instructions to perform parallel computations on vectors of 8, 16, 827 * 32, 64 and 128 bit quantities. NEON requires VFPv32-D32 since all 828 * NEON registers are also mapped to the same register banks. 829 * 830 * VFPv4-D16, adds a few instructions on top of VFPv3-D16 in order to 831 * perform fused multiply-accumulate on VFP registers, as well as 832 * half-precision (16-bit) conversion operations. 833 * 834 * VFPv4-D32 is VFPv4-D16 with 32, instead of 16, FPU double precision 835 * registers. 836 * 837 * VPFv4-NEON is VFPv4-D32 with NEON instructions. It also adds fused 838 * multiply-accumulate instructions that work on the NEON registers. 839 * 840 * NOTE: Similarly, "VFPv4" might either reference VFPv4-D16 or VFPv4-D32 841 * depending on context. 842 * 843 * The following information was determined by scanning the binutils-2.22 844 * sources: 845 * 846 * Basic VFP instruction subsets: 847 * 848 * #define FPU_VFP_EXT_V1xD 0x08000000 // Base VFP instruction set. 849 * #define FPU_VFP_EXT_V1 0x04000000 // Double-precision insns. 850 * #define FPU_VFP_EXT_V2 0x02000000 // ARM10E VFPr1. 851 * #define FPU_VFP_EXT_V3xD 0x01000000 // VFPv3 single-precision. 852 * #define FPU_VFP_EXT_V3 0x00800000 // VFPv3 double-precision. 853 * #define FPU_NEON_EXT_V1 0x00400000 // Neon (SIMD) insns. 854 * #define FPU_VFP_EXT_D32 0x00200000 // Registers D16-D31. 855 * #define FPU_VFP_EXT_FP16 0x00100000 // Half-precision extensions. 856 * #define FPU_NEON_EXT_FMA 0x00080000 // Neon fused multiply-add 857 * #define FPU_VFP_EXT_FMA 0x00040000 // VFP fused multiply-add 858 * 859 * FPU types (excluding NEON) 860 * 861 * FPU_VFP_V1xD (EXT_V1xD) 862 * | 863 * +--------------------------+ 864 * | | 865 * FPU_VFP_V1 (+EXT_V1) FPU_VFP_V3xD (+EXT_V2+EXT_V3xD) 866 * | | 867 * | | 868 * FPU_VFP_V2 (+EXT_V2) FPU_VFP_V4_SP_D16 (+EXT_FP16+EXT_FMA) 869 * | 870 * FPU_VFP_V3D16 (+EXT_Vx3D+EXT_V3) 871 * | 872 * +--------------------------+ 873 * | | 874 * FPU_VFP_V3 (+EXT_D32) FPU_VFP_V4D16 (+EXT_FP16+EXT_FMA) 875 * | | 876 * | FPU_VFP_V4 (+EXT_D32) 877 * | 878 * FPU_VFP_HARD (+EXT_FMA+NEON_EXT_FMA) 879 * 880 * VFP architectures: 881 * 882 * ARCH_VFP_V1xD (EXT_V1xD) 883 * | 884 * +------------------+ 885 * | | 886 * | ARCH_VFP_V3xD (+EXT_V2+EXT_V3xD) 887 * | | 888 * | ARCH_VFP_V3xD_FP16 (+EXT_FP16) 889 * | | 890 * | ARCH_VFP_V4_SP_D16 (+EXT_FMA) 891 * | 892 * ARCH_VFP_V1 (+EXT_V1) 893 * | 894 * ARCH_VFP_V2 (+EXT_V2) 895 * | 896 * ARCH_VFP_V3D16 (+EXT_V3xD+EXT_V3) 897 * | 898 * +-------------------+ 899 * | | 900 * | ARCH_VFP_V3D16_FP16 (+EXT_FP16) 901 * | 902 * +-------------------+ 903 * | | 904 * | ARCH_VFP_V4_D16 (+EXT_FP16+EXT_FMA) 905 * | | 906 * | ARCH_VFP_V4 (+EXT_D32) 907 * | | 908 * | ARCH_NEON_VFP_V4 (+EXT_NEON+EXT_NEON_FMA) 909 * | 910 * ARCH_VFP_V3 (+EXT_D32) 911 * | 912 * +-------------------+ 913 * | | 914 * | ARCH_VFP_V3_FP16 (+EXT_FP16) 915 * | 916 * ARCH_VFP_V3_PLUS_NEON_V1 (+EXT_NEON) 917 * | 918 * ARCH_NEON_FP16 (+EXT_FP16) 919 * 920 * -fpu=<name> values and their correspondance with FPU architectures above: 921 * 922 * {"vfp", FPU_ARCH_VFP_V2}, 923 * {"vfp9", FPU_ARCH_VFP_V2}, 924 * {"vfp3", FPU_ARCH_VFP_V3}, // For backwards compatbility. 925 * {"vfp10", FPU_ARCH_VFP_V2}, 926 * {"vfp10-r0", FPU_ARCH_VFP_V1}, 927 * {"vfpxd", FPU_ARCH_VFP_V1xD}, 928 * {"vfpv2", FPU_ARCH_VFP_V2}, 929 * {"vfpv3", FPU_ARCH_VFP_V3}, 930 * {"vfpv3-fp16", FPU_ARCH_VFP_V3_FP16}, 931 * {"vfpv3-d16", FPU_ARCH_VFP_V3D16}, 932 * {"vfpv3-d16-fp16", FPU_ARCH_VFP_V3D16_FP16}, 933 * {"vfpv3xd", FPU_ARCH_VFP_V3xD}, 934 * {"vfpv3xd-fp16", FPU_ARCH_VFP_V3xD_FP16}, 935 * {"neon", FPU_ARCH_VFP_V3_PLUS_NEON_V1}, 936 * {"neon-fp16", FPU_ARCH_NEON_FP16}, 937 * {"vfpv4", FPU_ARCH_VFP_V4}, 938 * {"vfpv4-d16", FPU_ARCH_VFP_V4D16}, 939 * {"fpv4-sp-d16", FPU_ARCH_VFP_V4_SP_D16}, 940 * {"neon-vfpv4", FPU_ARCH_NEON_VFP_V4}, 941 * 942 * 943 * Simplified diagram that only includes FPUs supported by Android: 944 * Only ARCH_VFP_V3D16 is actually mandated by the armeabi-v7a ABI, 945 * all others are optional and must be probed at runtime. 946 * 947 * ARCH_VFP_V3D16 (EXT_V1xD+EXT_V1+EXT_V2+EXT_V3xD+EXT_V3) 948 * | 949 * +-------------------+ 950 * | | 951 * | ARCH_VFP_V3D16_FP16 (+EXT_FP16) 952 * | 953 * +-------------------+ 954 * | | 955 * | ARCH_VFP_V4_D16 (+EXT_FP16+EXT_FMA) 956 * | | 957 * | ARCH_VFP_V4 (+EXT_D32) 958 * | | 959 * | ARCH_NEON_VFP_V4 (+EXT_NEON+EXT_NEON_FMA) 960 * | 961 * ARCH_VFP_V3 (+EXT_D32) 962 * | 963 * +-------------------+ 964 * | | 965 * | ARCH_VFP_V3_FP16 (+EXT_FP16) 966 * | 967 * ARCH_VFP_V3_PLUS_NEON_V1 (+EXT_NEON) 968 * | 969 * ARCH_NEON_FP16 (+EXT_FP16) 970 * 971 */ 972
