1 /* SPDX-License-Identifier: BSD-3-Clause 2 * Copyright(c) 2010-2014 Intel Corporation 3 */ 4 5 #ifndef __INCLUDE_RTE_BITMAP_H__ 6 #define __INCLUDE_RTE_BITMAP_H__ 7 8 /** 9 * @file 10 * RTE Bitmap 11 * 12 * The bitmap component provides a mechanism to manage large arrays of bits 13 * through bit get/set/clear and bit array scan operations. 14 * 15 * The bitmap scan operation is optimized for 64-bit CPUs using 64/128 byte cache 16 * lines. The bitmap is hierarchically organized using two arrays (array1 and 17 * array2), with each bit in array1 being associated with a full cache line 18 * (512/1024 bits) of bitmap bits, which are stored in array2: the bit in array1 19 * is set only when there is at least one bit set within its associated array2 20 * bits, otherwise the bit in array1 is cleared. The read and write operations 21 * for array1 and array2 are always done in slabs of 64 bits. 22 * 23 * This bitmap is not thread safe. For lock free operation on a specific bitmap 24 * instance, a single writer thread performing bit set/clear operations is 25 * allowed, only the writer thread can do bitmap scan operations, while there 26 * can be several reader threads performing bit get operations in parallel with 27 * the writer thread. When the use of locking primitives is acceptable, the 28 * serialization of the bit set/clear and bitmap scan operations needs to be 29 * enforced by the caller, while the bit get operation does not require locking 30 * the bitmap. 31 */ 32 33 #include <string.h> 34 35 #include <rte_common.h> 36 #include <rte_config.h> 37 #include <rte_debug.h> 38 #include <rte_memory.h> 39 #include <rte_branch_prediction.h> 40 #include <rte_prefetch.h> 41 42 #ifdef __cplusplus 43 extern "C" { 44 #endif 45 46 /* Slab */ 47 #define RTE_BITMAP_SLAB_BIT_SIZE 64 48 #define RTE_BITMAP_SLAB_BIT_SIZE_LOG2 6 49 #define RTE_BITMAP_SLAB_BIT_MASK (RTE_BITMAP_SLAB_BIT_SIZE - 1) 50 51 /* Cache line (CL) */ 52 #define RTE_BITMAP_CL_BIT_SIZE (RTE_CACHE_LINE_SIZE * 8) 53 #define RTE_BITMAP_CL_BIT_SIZE_LOG2 (RTE_CACHE_LINE_SIZE_LOG2 + 3) 54 #define RTE_BITMAP_CL_BIT_MASK (RTE_BITMAP_CL_BIT_SIZE - 1) 55 56 #define RTE_BITMAP_CL_SLAB_SIZE (RTE_BITMAP_CL_BIT_SIZE / RTE_BITMAP_SLAB_BIT_SIZE) 57 #define RTE_BITMAP_CL_SLAB_SIZE_LOG2 (RTE_BITMAP_CL_BIT_SIZE_LOG2 - RTE_BITMAP_SLAB_BIT_SIZE_LOG2) 58 #define RTE_BITMAP_CL_SLAB_MASK (RTE_BITMAP_CL_SLAB_SIZE - 1) 59 60 /** Bitmap data structure */ 61 struct rte_bitmap { 62 /* Context for array1 and array2 */ 63 uint64_t *array1; /**< Bitmap array1 */ 64 uint64_t *array2; /**< Bitmap array2 */ 65 uint32_t array1_size; /**< Number of 64-bit slabs in array1 that are actually used */ 66 uint32_t array2_size; /**< Number of 64-bit slabs in array2 */ 67 68 /* Context for the "scan next" operation */ 69 uint32_t index1; /**< Bitmap scan: Index of current array1 slab */ 70 uint32_t offset1; /**< Bitmap scan: Offset of current bit within current array1 slab */ 71 uint32_t index2; /**< Bitmap scan: Index of current array2 slab */ 72 uint32_t go2; /**< Bitmap scan: Go/stop condition for current array2 cache line */ 73 74 /* Storage space for array1 and array2 */ 75 uint8_t memory[]; 76 }; 77 78 static inline void 79 __rte_bitmap_index1_inc(struct rte_bitmap *bmp) 80 { 81 bmp->index1 = (bmp->index1 + 1) & (bmp->array1_size - 1); 82 } 83 84 static inline uint64_t 85 __rte_bitmap_mask1_get(struct rte_bitmap *bmp) 86 { 87 return (~1llu) << bmp->offset1; 88 } 89 90 static inline void 91 __rte_bitmap_index2_set(struct rte_bitmap *bmp) 92 { 93 bmp->index2 = (((bmp->index1 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2) + bmp->offset1) << RTE_BITMAP_CL_SLAB_SIZE_LOG2); 94 } 95 96 static inline uint32_t 97 __rte_bitmap_get_memory_footprint(uint32_t n_bits, 98 uint32_t *array1_byte_offset, uint32_t *array1_slabs, 99 uint32_t *array2_byte_offset, uint32_t *array2_slabs) 100 { 101 uint32_t n_slabs_context, n_slabs_array1, n_cache_lines_context_and_array1; 102 uint32_t n_cache_lines_array2; 103 uint32_t n_bytes_total; 104 105 n_cache_lines_array2 = (n_bits + RTE_BITMAP_CL_BIT_SIZE - 1) / RTE_BITMAP_CL_BIT_SIZE; 106 n_slabs_array1 = (n_cache_lines_array2 + RTE_BITMAP_SLAB_BIT_SIZE - 1) / RTE_BITMAP_SLAB_BIT_SIZE; 107 n_slabs_array1 = rte_align32pow2(n_slabs_array1); 108 n_slabs_context = (sizeof(struct rte_bitmap) + (RTE_BITMAP_SLAB_BIT_SIZE / 8) - 1) / (RTE_BITMAP_SLAB_BIT_SIZE / 8); 109 n_cache_lines_context_and_array1 = (n_slabs_context + n_slabs_array1 + RTE_BITMAP_CL_SLAB_SIZE - 1) / RTE_BITMAP_CL_SLAB_SIZE; 110 n_bytes_total = (n_cache_lines_context_and_array1 + n_cache_lines_array2) * RTE_CACHE_LINE_SIZE; 111 112 if (array1_byte_offset) { 113 *array1_byte_offset = n_slabs_context * (RTE_BITMAP_SLAB_BIT_SIZE / 8); 114 } 115 if (array1_slabs) { 116 *array1_slabs = n_slabs_array1; 117 } 118 if (array2_byte_offset) { 119 *array2_byte_offset = n_cache_lines_context_and_array1 * RTE_CACHE_LINE_SIZE; 120 } 121 if (array2_slabs) { 122 *array2_slabs = n_cache_lines_array2 * RTE_BITMAP_CL_SLAB_SIZE; 123 } 124 125 return n_bytes_total; 126 } 127 128 static inline void 129 __rte_bitmap_scan_init(struct rte_bitmap *bmp) 130 { 131 bmp->index1 = bmp->array1_size - 1; 132 bmp->offset1 = RTE_BITMAP_SLAB_BIT_SIZE - 1; 133 __rte_bitmap_index2_set(bmp); 134 bmp->index2 += RTE_BITMAP_CL_SLAB_SIZE; 135 136 bmp->go2 = 0; 137 } 138 139 /** 140 * Bitmap memory footprint calculation 141 * 142 * @param n_bits 143 * Number of bits in the bitmap 144 * @return 145 * Bitmap memory footprint measured in bytes on success, 0 on error 146 */ 147 static inline uint32_t 148 rte_bitmap_get_memory_footprint(uint32_t n_bits) { 149 /* Check input arguments */ 150 if (n_bits == 0) { 151 return 0; 152 } 153 154 return __rte_bitmap_get_memory_footprint(n_bits, NULL, NULL, NULL, NULL); 155 } 156 157 /** 158 * Bitmap initialization 159 * 160 * @param n_bits 161 * Number of pre-allocated bits in array2. 162 * @param mem 163 * Base address of array1 and array2. 164 * @param mem_size 165 * Minimum expected size of bitmap. 166 * @return 167 * Handle to bitmap instance. 168 */ 169 static inline struct rte_bitmap * 170 rte_bitmap_init(uint32_t n_bits, uint8_t *mem, uint32_t mem_size) 171 { 172 struct rte_bitmap *bmp; 173 uint32_t array1_byte_offset, array1_slabs, array2_byte_offset, array2_slabs; 174 uint32_t size; 175 176 /* Check input arguments */ 177 if (n_bits == 0) { 178 return NULL; 179 } 180 181 if ((mem == NULL) || (((uintptr_t) mem) & RTE_CACHE_LINE_MASK)) { 182 return NULL; 183 } 184 185 size = __rte_bitmap_get_memory_footprint(n_bits, 186 &array1_byte_offset, &array1_slabs, 187 &array2_byte_offset, &array2_slabs); 188 if (size > mem_size) 189 return NULL; 190 191 /* Setup bitmap */ 192 memset(mem, 0, size); 193 bmp = (struct rte_bitmap *) mem; 194 195 bmp->array1 = (uint64_t *) &mem[array1_byte_offset]; 196 bmp->array1_size = array1_slabs; 197 bmp->array2 = (uint64_t *) &mem[array2_byte_offset]; 198 bmp->array2_size = array2_slabs; 199 200 __rte_bitmap_scan_init(bmp); 201 202 return bmp; 203 } 204 205 /** 206 * Bitmap clear slab overhead bits. 207 * 208 * @param slabs 209 * Slab array. 210 * @param slab_size 211 * Number of 64-bit slabs in the slabs array. 212 * @param pos 213 * The start bit position in the slabs to be cleared. 214 */ 215 static inline void 216 __rte_bitmap_clear_slab_overhead_bits(uint64_t *slabs, uint32_t slab_size, 217 uint32_t pos) 218 { 219 uint32_t i; 220 uint32_t index = pos / RTE_BITMAP_SLAB_BIT_SIZE; 221 uint32_t offset = pos & RTE_BITMAP_SLAB_BIT_MASK; 222 223 if (offset) { 224 for (i = offset; i < RTE_BITMAP_SLAB_BIT_SIZE; i++) 225 slabs[index] &= ~(1llu << i); 226 index++; 227 } 228 if (index < slab_size) 229 memset(&slabs[index], 0, sizeof(slabs[0]) * 230 (slab_size - index)); 231 } 232 233 /** 234 * Bitmap initialization with all bits set 235 * 236 * @param n_bits 237 * Number of pre-allocated bits in array2. 238 * @param mem 239 * Base address of array1 and array2. 240 * @param mem_size 241 * Minimum expected size of bitmap. 242 * @return 243 * Handle to bitmap instance. 244 */ 245 static inline struct rte_bitmap * 246 rte_bitmap_init_with_all_set(uint32_t n_bits, uint8_t *mem, uint32_t mem_size) 247 { 248 struct rte_bitmap *bmp; 249 uint32_t array1_byte_offset, array1_slabs; 250 uint32_t array2_byte_offset, array2_slabs; 251 uint32_t size; 252 253 /* Check input arguments */ 254 if (!n_bits || !mem || (((uintptr_t) mem) & RTE_CACHE_LINE_MASK)) 255 return NULL; 256 257 size = __rte_bitmap_get_memory_footprint(n_bits, 258 &array1_byte_offset, &array1_slabs, 259 &array2_byte_offset, &array2_slabs); 260 if (size < mem_size) 261 return NULL; 262 263 /* Setup bitmap */ 264 bmp = (struct rte_bitmap *) mem; 265 bmp->array1 = (uint64_t *) &mem[array1_byte_offset]; 266 bmp->array1_size = array1_slabs; 267 bmp->array2 = (uint64_t *) &mem[array2_byte_offset]; 268 bmp->array2_size = array2_slabs; 269 270 __rte_bitmap_scan_init(bmp); 271 272 memset(bmp->array1, 0xff, bmp->array1_size * sizeof(bmp->array1[0])); 273 memset(bmp->array2, 0xff, bmp->array2_size * sizeof(bmp->array2[0])); 274 /* Clear overhead bits. */ 275 __rte_bitmap_clear_slab_overhead_bits(bmp->array1, bmp->array1_size, 276 bmp->array2_size >> RTE_BITMAP_CL_SLAB_SIZE_LOG2); 277 __rte_bitmap_clear_slab_overhead_bits(bmp->array2, bmp->array2_size, 278 n_bits); 279 return bmp; 280 } 281 282 /** 283 * Bitmap free 284 * 285 * @param bmp 286 * Handle to bitmap instance 287 * @return 288 * 0 upon success, error code otherwise 289 */ 290 static inline int 291 rte_bitmap_free(struct rte_bitmap *bmp) 292 { 293 /* Check input arguments */ 294 if (bmp == NULL) { 295 return -1; 296 } 297 298 return 0; 299 } 300 301 /** 302 * Bitmap reset 303 * 304 * @param bmp 305 * Handle to bitmap instance 306 */ 307 static inline void 308 rte_bitmap_reset(struct rte_bitmap *bmp) 309 { 310 memset(bmp->array1, 0, bmp->array1_size * sizeof(uint64_t)); 311 memset(bmp->array2, 0, bmp->array2_size * sizeof(uint64_t)); 312 __rte_bitmap_scan_init(bmp); 313 } 314 315 /** 316 * Bitmap location prefetch into CPU L1 cache 317 * 318 * @param bmp 319 * Handle to bitmap instance 320 * @param pos 321 * Bit position 322 */ 323 static inline void 324 rte_bitmap_prefetch0(struct rte_bitmap *bmp, uint32_t pos) 325 { 326 uint64_t *slab2; 327 uint32_t index2; 328 329 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 330 slab2 = bmp->array2 + index2; 331 rte_prefetch0((void *) slab2); 332 } 333 334 /** 335 * Bitmap bit get 336 * 337 * @param bmp 338 * Handle to bitmap instance 339 * @param pos 340 * Bit position 341 * @return 342 * 0 when bit is cleared, non-zero when bit is set 343 */ 344 static inline uint64_t 345 rte_bitmap_get(struct rte_bitmap *bmp, uint32_t pos) 346 { 347 uint64_t *slab2; 348 uint32_t index2, offset2; 349 350 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 351 offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK; 352 slab2 = bmp->array2 + index2; 353 return (*slab2) & (1llu << offset2); 354 } 355 356 /** 357 * Bitmap bit set 358 * 359 * @param bmp 360 * Handle to bitmap instance 361 * @param pos 362 * Bit position 363 */ 364 static inline void 365 rte_bitmap_set(struct rte_bitmap *bmp, uint32_t pos) 366 { 367 uint64_t *slab1, *slab2; 368 uint32_t index1, index2, offset1, offset2; 369 370 /* Set bit in array2 slab and set bit in array1 slab */ 371 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 372 offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK; 373 index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2); 374 offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK; 375 slab2 = bmp->array2 + index2; 376 slab1 = bmp->array1 + index1; 377 378 *slab2 |= 1llu << offset2; 379 *slab1 |= 1llu << offset1; 380 } 381 382 /** 383 * Bitmap slab set 384 * 385 * @param bmp 386 * Handle to bitmap instance 387 * @param pos 388 * Bit position identifying the array2 slab 389 * @param slab 390 * Value to be assigned to the 64-bit slab in array2 391 */ 392 static inline void 393 rte_bitmap_set_slab(struct rte_bitmap *bmp, uint32_t pos, uint64_t slab) 394 { 395 uint64_t *slab1, *slab2; 396 uint32_t index1, index2, offset1; 397 398 /* Set bits in array2 slab and set bit in array1 slab */ 399 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 400 index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2); 401 offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK; 402 slab2 = bmp->array2 + index2; 403 slab1 = bmp->array1 + index1; 404 405 *slab2 |= slab; 406 *slab1 |= 1llu << offset1; 407 } 408 409 #if RTE_BITMAP_CL_SLAB_SIZE == 8 410 static inline uint64_t 411 __rte_bitmap_line_not_empty(uint64_t *slab2) 412 { 413 uint64_t v1, v2, v3, v4; 414 415 v1 = slab2[0] | slab2[1]; 416 v2 = slab2[2] | slab2[3]; 417 v3 = slab2[4] | slab2[5]; 418 v4 = slab2[6] | slab2[7]; 419 v1 |= v2; 420 v3 |= v4; 421 422 return v1 | v3; 423 } 424 425 #elif RTE_BITMAP_CL_SLAB_SIZE == 16 426 static inline uint64_t 427 __rte_bitmap_line_not_empty(uint64_t *slab2) 428 { 429 uint64_t v1, v2, v3, v4, v5, v6, v7, v8; 430 431 v1 = slab2[0] | slab2[1]; 432 v2 = slab2[2] | slab2[3]; 433 v3 = slab2[4] | slab2[5]; 434 v4 = slab2[6] | slab2[7]; 435 v5 = slab2[8] | slab2[9]; 436 v6 = slab2[10] | slab2[11]; 437 v7 = slab2[12] | slab2[13]; 438 v8 = slab2[14] | slab2[15]; 439 v1 |= v2; 440 v3 |= v4; 441 v5 |= v6; 442 v7 |= v8; 443 444 return v1 | v3 | v5 | v7; 445 } 446 447 #endif /* RTE_BITMAP_CL_SLAB_SIZE */ 448 449 /** 450 * Bitmap bit clear 451 * 452 * @param bmp 453 * Handle to bitmap instance 454 * @param pos 455 * Bit position 456 */ 457 static inline void 458 rte_bitmap_clear(struct rte_bitmap *bmp, uint32_t pos) 459 { 460 uint64_t *slab1, *slab2; 461 uint32_t index1, index2, offset1, offset2; 462 463 /* Clear bit in array2 slab */ 464 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 465 offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK; 466 slab2 = bmp->array2 + index2; 467 468 /* Return if array2 slab is not all-zeros */ 469 *slab2 &= ~(1llu << offset2); 470 if (*slab2){ 471 return; 472 } 473 474 /* Check the entire cache line of array2 for all-zeros */ 475 index2 &= ~ RTE_BITMAP_CL_SLAB_MASK; 476 slab2 = bmp->array2 + index2; 477 if (__rte_bitmap_line_not_empty(slab2)) { 478 return; 479 } 480 481 /* The array2 cache line is all-zeros, so clear bit in array1 slab */ 482 index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2); 483 offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK; 484 slab1 = bmp->array1 + index1; 485 *slab1 &= ~(1llu << offset1); 486 487 return; 488 } 489 490 static inline int 491 __rte_bitmap_scan_search(struct rte_bitmap *bmp) 492 { 493 uint64_t value1; 494 uint32_t i; 495 496 /* Check current array1 slab */ 497 value1 = bmp->array1[bmp->index1]; 498 value1 &= __rte_bitmap_mask1_get(bmp); 499 500 if (rte_bsf64_safe(value1, &bmp->offset1)) 501 return 1; 502 503 __rte_bitmap_index1_inc(bmp); 504 bmp->offset1 = 0; 505 506 /* Look for another array1 slab */ 507 for (i = 0; i < bmp->array1_size; i ++, __rte_bitmap_index1_inc(bmp)) { 508 value1 = bmp->array1[bmp->index1]; 509 510 if (rte_bsf64_safe(value1, &bmp->offset1)) 511 return 1; 512 } 513 514 return 0; 515 } 516 517 static inline void 518 __rte_bitmap_scan_read_init(struct rte_bitmap *bmp) 519 { 520 __rte_bitmap_index2_set(bmp); 521 bmp->go2 = 1; 522 rte_prefetch1((void *)(bmp->array2 + bmp->index2 + 8)); 523 } 524 525 static inline int 526 __rte_bitmap_scan_read(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab) 527 { 528 uint64_t *slab2; 529 530 slab2 = bmp->array2 + bmp->index2; 531 for ( ; bmp->go2 ; bmp->index2 ++, slab2 ++, bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK) { 532 if (*slab2) { 533 *pos = bmp->index2 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 534 *slab = *slab2; 535 536 bmp->index2 ++; 537 slab2 ++; 538 bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK; 539 return 1; 540 } 541 } 542 543 return 0; 544 } 545 546 /** 547 * Bitmap scan (with automatic wrap-around) 548 * 549 * @param bmp 550 * Handle to bitmap instance 551 * @param pos 552 * When function call returns 1, pos contains the position of the next set 553 * bit, otherwise not modified 554 * @param slab 555 * When function call returns 1, slab contains the value of the entire 64-bit 556 * slab where the bit indicated by pos is located. Slabs are always 64-bit 557 * aligned, so the position of the first bit of the slab (this bit is not 558 * necessarily set) is pos / 64. Once a slab has been returned by the bitmap 559 * scan operation, the internal pointers of the bitmap are updated to point 560 * after this slab, so the same slab will not be returned again if it 561 * contains more than one bit which is set. When function call returns 0, 562 * slab is not modified. 563 * @return 564 * 0 if there is no bit set in the bitmap, 1 otherwise 565 */ 566 static inline int 567 rte_bitmap_scan(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab) 568 { 569 /* Return data from current array2 line if available */ 570 if (__rte_bitmap_scan_read(bmp, pos, slab)) { 571 return 1; 572 } 573 574 /* Look for non-empty array2 line */ 575 if (__rte_bitmap_scan_search(bmp)) { 576 __rte_bitmap_scan_read_init(bmp); 577 __rte_bitmap_scan_read(bmp, pos, slab); 578 return 1; 579 } 580 581 /* Empty bitmap */ 582 return 0; 583 } 584 585 #ifdef __cplusplus 586 } 587 #endif 588 589 #endif /* __INCLUDE_RTE_BITMAP_H__ */ 590