1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * lib/bitmap.c 4 * Helper functions for bitmap.h. 5 */ 6 7 #include <linux/bitmap.h> 8 #include <linux/bitops.h> 9 #include <linux/ctype.h> 10 #include <linux/device.h> 11 #include <linux/export.h> 12 #include <linux/slab.h> 13 14 /** 15 * DOC: bitmap introduction 16 * 17 * bitmaps provide an array of bits, implemented using an 18 * array of unsigned longs. The number of valid bits in a 19 * given bitmap does _not_ need to be an exact multiple of 20 * BITS_PER_LONG. 21 * 22 * The possible unused bits in the last, partially used word 23 * of a bitmap are 'don't care'. The implementation makes 24 * no particular effort to keep them zero. It ensures that 25 * their value will not affect the results of any operation. 26 * The bitmap operations that return Boolean (bitmap_empty, 27 * for example) or scalar (bitmap_weight, for example) results 28 * carefully filter out these unused bits from impacting their 29 * results. 30 * 31 * The byte ordering of bitmaps is more natural on little 32 * endian architectures. See the big-endian headers 33 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h 34 * for the best explanations of this ordering. 35 */ 36 37 bool __bitmap_equal(const unsigned long *bitmap1, 38 const unsigned long *bitmap2, unsigned int bits) 39 { 40 unsigned int k, lim = bits/BITS_PER_LONG; 41 for (k = 0; k < lim; ++k) 42 if (bitmap1[k] != bitmap2[k]) 43 return false; 44 45 if (bits % BITS_PER_LONG) 46 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 47 return false; 48 49 return true; 50 } 51 EXPORT_SYMBOL(__bitmap_equal); 52 53 bool __bitmap_or_equal(const unsigned long *bitmap1, 54 const unsigned long *bitmap2, 55 const unsigned long *bitmap3, 56 unsigned int bits) 57 { 58 unsigned int k, lim = bits / BITS_PER_LONG; 59 unsigned long tmp; 60 61 for (k = 0; k < lim; ++k) { 62 if ((bitmap1[k] | bitmap2[k]) != bitmap3[k]) 63 return false; 64 } 65 66 if (!(bits % BITS_PER_LONG)) 67 return true; 68 69 tmp = (bitmap1[k] | bitmap2[k]) ^ bitmap3[k]; 70 return (tmp & BITMAP_LAST_WORD_MASK(bits)) == 0; 71 } 72 EXPORT_SYMBOL(__bitmap_or_equal); 73 74 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits) 75 { 76 unsigned int k, lim = BITS_TO_LONGS(bits); 77 for (k = 0; k < lim; ++k) 78 dst[k] = ~src[k]; 79 } 80 EXPORT_SYMBOL(__bitmap_complement); 81 82 /** 83 * __bitmap_shift_right - logical right shift of the bits in a bitmap 84 * @dst : destination bitmap 85 * @src : source bitmap 86 * @shift : shift by this many bits 87 * @nbits : bitmap size, in bits 88 * 89 * Shifting right (dividing) means moving bits in the MS -> LS bit 90 * direction. Zeros are fed into the vacated MS positions and the 91 * LS bits shifted off the bottom are lost. 92 */ 93 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src, 94 unsigned shift, unsigned nbits) 95 { 96 unsigned k, lim = BITS_TO_LONGS(nbits); 97 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; 98 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits); 99 for (k = 0; off + k < lim; ++k) { 100 unsigned long upper, lower; 101 102 /* 103 * If shift is not word aligned, take lower rem bits of 104 * word above and make them the top rem bits of result. 105 */ 106 if (!rem || off + k + 1 >= lim) 107 upper = 0; 108 else { 109 upper = src[off + k + 1]; 110 if (off + k + 1 == lim - 1) 111 upper &= mask; 112 upper <<= (BITS_PER_LONG - rem); 113 } 114 lower = src[off + k]; 115 if (off + k == lim - 1) 116 lower &= mask; 117 lower >>= rem; 118 dst[k] = lower | upper; 119 } 120 if (off) 121 memset(&dst[lim - off], 0, off*sizeof(unsigned long)); 122 } 123 EXPORT_SYMBOL(__bitmap_shift_right); 124 125 126 /** 127 * __bitmap_shift_left - logical left shift of the bits in a bitmap 128 * @dst : destination bitmap 129 * @src : source bitmap 130 * @shift : shift by this many bits 131 * @nbits : bitmap size, in bits 132 * 133 * Shifting left (multiplying) means moving bits in the LS -> MS 134 * direction. Zeros are fed into the vacated LS bit positions 135 * and those MS bits shifted off the top are lost. 136 */ 137 138 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src, 139 unsigned int shift, unsigned int nbits) 140 { 141 int k; 142 unsigned int lim = BITS_TO_LONGS(nbits); 143 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; 144 for (k = lim - off - 1; k >= 0; --k) { 145 unsigned long upper, lower; 146 147 /* 148 * If shift is not word aligned, take upper rem bits of 149 * word below and make them the bottom rem bits of result. 150 */ 151 if (rem && k > 0) 152 lower = src[k - 1] >> (BITS_PER_LONG - rem); 153 else 154 lower = 0; 155 upper = src[k] << rem; 156 dst[k + off] = lower | upper; 157 } 158 if (off) 159 memset(dst, 0, off*sizeof(unsigned long)); 160 } 161 EXPORT_SYMBOL(__bitmap_shift_left); 162 163 /** 164 * bitmap_cut() - remove bit region from bitmap and right shift remaining bits 165 * @dst: destination bitmap, might overlap with src 166 * @src: source bitmap 167 * @first: start bit of region to be removed 168 * @cut: number of bits to remove 169 * @nbits: bitmap size, in bits 170 * 171 * Set the n-th bit of @dst iff the n-th bit of @src is set and 172 * n is less than @first, or the m-th bit of @src is set for any 173 * m such that @first <= n < nbits, and m = n + @cut. 174 * 175 * In pictures, example for a big-endian 32-bit architecture: 176 * 177 * The @src bitmap is:: 178 * 179 * 31 63 180 * | | 181 * 10000000 11000001 11110010 00010101 10000000 11000001 01110010 00010101 182 * | | | | 183 * 16 14 0 32 184 * 185 * if @cut is 3, and @first is 14, bits 14-16 in @src are cut and @dst is:: 186 * 187 * 31 63 188 * | | 189 * 10110000 00011000 00110010 00010101 00010000 00011000 00101110 01000010 190 * | | | 191 * 14 (bit 17 0 32 192 * from @src) 193 * 194 * Note that @dst and @src might overlap partially or entirely. 195 * 196 * This is implemented in the obvious way, with a shift and carry 197 * step for each moved bit. Optimisation is left as an exercise 198 * for the compiler. 199 */ 200 void bitmap_cut(unsigned long *dst, const unsigned long *src, 201 unsigned int first, unsigned int cut, unsigned int nbits) 202 { 203 unsigned int len = BITS_TO_LONGS(nbits); 204 unsigned long keep = 0, carry; 205 int i; 206 207 if (first % BITS_PER_LONG) { 208 keep = src[first / BITS_PER_LONG] & 209 (~0UL >> (BITS_PER_LONG - first % BITS_PER_LONG)); 210 } 211 212 memmove(dst, src, len * sizeof(*dst)); 213 214 while (cut--) { 215 for (i = first / BITS_PER_LONG; i < len; i++) { 216 if (i < len - 1) 217 carry = dst[i + 1] & 1UL; 218 else 219 carry = 0; 220 221 dst[i] = (dst[i] >> 1) | (carry << (BITS_PER_LONG - 1)); 222 } 223 } 224 225 dst[first / BITS_PER_LONG] &= ~0UL << (first % BITS_PER_LONG); 226 dst[first / BITS_PER_LONG] |= keep; 227 } 228 EXPORT_SYMBOL(bitmap_cut); 229 230 bool __bitmap_and(unsigned long *dst, const unsigned long *bitmap1, 231 const unsigned long *bitmap2, unsigned int bits) 232 { 233 unsigned int k; 234 unsigned int lim = bits/BITS_PER_LONG; 235 unsigned long result = 0; 236 237 for (k = 0; k < lim; k++) 238 result |= (dst[k] = bitmap1[k] & bitmap2[k]); 239 if (bits % BITS_PER_LONG) 240 result |= (dst[k] = bitmap1[k] & bitmap2[k] & 241 BITMAP_LAST_WORD_MASK(bits)); 242 return result != 0; 243 } 244 EXPORT_SYMBOL(__bitmap_and); 245 246 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1, 247 const unsigned long *bitmap2, unsigned int bits) 248 { 249 unsigned int k; 250 unsigned int nr = BITS_TO_LONGS(bits); 251 252 for (k = 0; k < nr; k++) 253 dst[k] = bitmap1[k] | bitmap2[k]; 254 } 255 EXPORT_SYMBOL(__bitmap_or); 256 257 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1, 258 const unsigned long *bitmap2, unsigned int bits) 259 { 260 unsigned int k; 261 unsigned int nr = BITS_TO_LONGS(bits); 262 263 for (k = 0; k < nr; k++) 264 dst[k] = bitmap1[k] ^ bitmap2[k]; 265 } 266 EXPORT_SYMBOL(__bitmap_xor); 267 268 bool __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, 269 const unsigned long *bitmap2, unsigned int bits) 270 { 271 unsigned int k; 272 unsigned int lim = bits/BITS_PER_LONG; 273 unsigned long result = 0; 274 275 for (k = 0; k < lim; k++) 276 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]); 277 if (bits % BITS_PER_LONG) 278 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] & 279 BITMAP_LAST_WORD_MASK(bits)); 280 return result != 0; 281 } 282 EXPORT_SYMBOL(__bitmap_andnot); 283 284 void __bitmap_replace(unsigned long *dst, 285 const unsigned long *old, const unsigned long *new, 286 const unsigned long *mask, unsigned int nbits) 287 { 288 unsigned int k; 289 unsigned int nr = BITS_TO_LONGS(nbits); 290 291 for (k = 0; k < nr; k++) 292 dst[k] = (old[k] & ~mask[k]) | (new[k] & mask[k]); 293 } 294 EXPORT_SYMBOL(__bitmap_replace); 295 296 bool __bitmap_intersects(const unsigned long *bitmap1, 297 const unsigned long *bitmap2, unsigned int bits) 298 { 299 unsigned int k, lim = bits/BITS_PER_LONG; 300 for (k = 0; k < lim; ++k) 301 if (bitmap1[k] & bitmap2[k]) 302 return true; 303 304 if (bits % BITS_PER_LONG) 305 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 306 return true; 307 return false; 308 } 309 EXPORT_SYMBOL(__bitmap_intersects); 310 311 bool __bitmap_subset(const unsigned long *bitmap1, 312 const unsigned long *bitmap2, unsigned int bits) 313 { 314 unsigned int k, lim = bits/BITS_PER_LONG; 315 for (k = 0; k < lim; ++k) 316 if (bitmap1[k] & ~bitmap2[k]) 317 return false; 318 319 if (bits % BITS_PER_LONG) 320 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 321 return false; 322 return true; 323 } 324 EXPORT_SYMBOL(__bitmap_subset); 325 326 #define BITMAP_WEIGHT(FETCH, bits) \ 327 ({ \ 328 unsigned int __bits = (bits), idx, w = 0; \ 329 \ 330 for (idx = 0; idx < __bits / BITS_PER_LONG; idx++) \ 331 w += hweight_long(FETCH); \ 332 \ 333 if (__bits % BITS_PER_LONG) \ 334 w += hweight_long((FETCH) & BITMAP_LAST_WORD_MASK(__bits)); \ 335 \ 336 w; \ 337 }) 338 339 unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits) 340 { 341 return BITMAP_WEIGHT(bitmap[idx], bits); 342 } 343 EXPORT_SYMBOL(__bitmap_weight); 344 345 unsigned int __bitmap_weight_and(const unsigned long *bitmap1, 346 const unsigned long *bitmap2, unsigned int bits) 347 { 348 return BITMAP_WEIGHT(bitmap1[idx] & bitmap2[idx], bits); 349 } 350 EXPORT_SYMBOL(__bitmap_weight_and); 351 352 unsigned int __bitmap_weight_andnot(const unsigned long *bitmap1, 353 const unsigned long *bitmap2, unsigned int bits) 354 { 355 return BITMAP_WEIGHT(bitmap1[idx] & ~bitmap2[idx], bits); 356 } 357 EXPORT_SYMBOL(__bitmap_weight_andnot); 358 359 unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitmap1, 360 const unsigned long *bitmap2, unsigned int bits) 361 { 362 return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] | bitmap2[idx]; dst[idx]; }), bits); 363 } 364 EXPORT_SYMBOL(__bitmap_weighted_or); 365 366 unsigned int __bitmap_weighted_xor(unsigned long *dst, const unsigned long *bitmap1, 367 const unsigned long *bitmap2, unsigned int bits) 368 { 369 return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] ^ bitmap2[idx]; dst[idx]; }), bits); 370 } 371 EXPORT_SYMBOL(__bitmap_weighted_xor); 372 373 void __bitmap_set(unsigned long *map, unsigned int start, int len) 374 { 375 unsigned long *p = map + BIT_WORD(start); 376 const unsigned int size = start + len; 377 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); 378 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); 379 380 while (len - bits_to_set >= 0) { 381 *p |= mask_to_set; 382 len -= bits_to_set; 383 bits_to_set = BITS_PER_LONG; 384 mask_to_set = ~0UL; 385 p++; 386 } 387 if (len) { 388 mask_to_set &= BITMAP_LAST_WORD_MASK(size); 389 *p |= mask_to_set; 390 } 391 } 392 EXPORT_SYMBOL(__bitmap_set); 393 394 void __bitmap_clear(unsigned long *map, unsigned int start, int len) 395 { 396 unsigned long *p = map + BIT_WORD(start); 397 const unsigned int size = start + len; 398 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); 399 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); 400 401 while (len - bits_to_clear >= 0) { 402 *p &= ~mask_to_clear; 403 len -= bits_to_clear; 404 bits_to_clear = BITS_PER_LONG; 405 mask_to_clear = ~0UL; 406 p++; 407 } 408 if (len) { 409 mask_to_clear &= BITMAP_LAST_WORD_MASK(size); 410 *p &= ~mask_to_clear; 411 } 412 } 413 EXPORT_SYMBOL(__bitmap_clear); 414 415 /** 416 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area 417 * @map: The address to base the search on 418 * @size: The bitmap size in bits 419 * @start: The bitnumber to start searching at 420 * @nr: The number of zeroed bits we're looking for 421 * @align_mask: Alignment mask for zero area 422 * @align_offset: Alignment offset for zero area. 423 * 424 * The @align_mask should be one less than a power of 2; the effect is that 425 * the bit offset of all zero areas this function finds plus @align_offset 426 * is multiple of that power of 2. 427 */ 428 unsigned long bitmap_find_next_zero_area_off(unsigned long *map, 429 unsigned long size, 430 unsigned long start, 431 unsigned int nr, 432 unsigned long align_mask, 433 unsigned long align_offset) 434 { 435 unsigned long index, end, i; 436 again: 437 index = find_next_zero_bit(map, size, start); 438 439 /* Align allocation */ 440 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset; 441 442 end = index + nr; 443 if (end > size) 444 return end; 445 i = find_next_bit(map, end, index); 446 if (i < end) { 447 start = i + 1; 448 goto again; 449 } 450 return index; 451 } 452 EXPORT_SYMBOL(bitmap_find_next_zero_area_off); 453 454 /** 455 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap 456 * @buf: pointer to a bitmap 457 * @pos: a bit position in @buf (0 <= @pos < @nbits) 458 * @nbits: number of valid bit positions in @buf 459 * 460 * Map the bit at position @pos in @buf (of length @nbits) to the 461 * ordinal of which set bit it is. If it is not set or if @pos 462 * is not a valid bit position, map to -1. 463 * 464 * If for example, just bits 4 through 7 are set in @buf, then @pos 465 * values 4 through 7 will get mapped to 0 through 3, respectively, 466 * and other @pos values will get mapped to -1. When @pos value 7 467 * gets mapped to (returns) @ord value 3 in this example, that means 468 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 469 * 470 * The bit positions 0 through @bits are valid positions in @buf. 471 */ 472 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits) 473 { 474 if (pos >= nbits || !test_bit(pos, buf)) 475 return -1; 476 477 return bitmap_weight(buf, pos); 478 } 479 480 /** 481 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 482 * @dst: remapped result 483 * @src: subset to be remapped 484 * @old: defines domain of map 485 * @new: defines range of map 486 * @nbits: number of bits in each of these bitmaps 487 * 488 * Let @old and @new define a mapping of bit positions, such that 489 * whatever position is held by the n-th set bit in @old is mapped 490 * to the n-th set bit in @new. In the more general case, allowing 491 * for the possibility that the weight 'w' of @new is less than the 492 * weight of @old, map the position of the n-th set bit in @old to 493 * the position of the m-th set bit in @new, where m == n % w. 494 * 495 * If either of the @old and @new bitmaps are empty, or if @src and 496 * @dst point to the same location, then this routine copies @src 497 * to @dst. 498 * 499 * The positions of unset bits in @old are mapped to themselves 500 * (the identity map). 501 * 502 * Apply the above specified mapping to @src, placing the result in 503 * @dst, clearing any bits previously set in @dst. 504 * 505 * For example, lets say that @old has bits 4 through 7 set, and 506 * @new has bits 12 through 15 set. This defines the mapping of bit 507 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 508 * bit positions unchanged. So if say @src comes into this routine 509 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 510 * 13 and 15 set. 511 */ 512 void bitmap_remap(unsigned long *dst, const unsigned long *src, 513 const unsigned long *old, const unsigned long *new, 514 unsigned int nbits) 515 { 516 unsigned int oldbit, w; 517 518 if (dst == src) /* following doesn't handle inplace remaps */ 519 return; 520 bitmap_zero(dst, nbits); 521 522 w = bitmap_weight(new, nbits); 523 for_each_set_bit(oldbit, src, nbits) { 524 int n = bitmap_pos_to_ord(old, oldbit, nbits); 525 526 if (n < 0 || w == 0) 527 set_bit(oldbit, dst); /* identity map */ 528 else 529 set_bit(find_nth_bit(new, nbits, n % w), dst); 530 } 531 } 532 EXPORT_SYMBOL(bitmap_remap); 533 534 /** 535 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 536 * @oldbit: bit position to be mapped 537 * @old: defines domain of map 538 * @new: defines range of map 539 * @bits: number of bits in each of these bitmaps 540 * 541 * Let @old and @new define a mapping of bit positions, such that 542 * whatever position is held by the n-th set bit in @old is mapped 543 * to the n-th set bit in @new. In the more general case, allowing 544 * for the possibility that the weight 'w' of @new is less than the 545 * weight of @old, map the position of the n-th set bit in @old to 546 * the position of the m-th set bit in @new, where m == n % w. 547 * 548 * The positions of unset bits in @old are mapped to themselves 549 * (the identity map). 550 * 551 * Apply the above specified mapping to bit position @oldbit, returning 552 * the new bit position. 553 * 554 * For example, lets say that @old has bits 4 through 7 set, and 555 * @new has bits 12 through 15 set. This defines the mapping of bit 556 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 557 * bit positions unchanged. So if say @oldbit is 5, then this routine 558 * returns 13. 559 */ 560 int bitmap_bitremap(int oldbit, const unsigned long *old, 561 const unsigned long *new, int bits) 562 { 563 int w = bitmap_weight(new, bits); 564 int n = bitmap_pos_to_ord(old, oldbit, bits); 565 if (n < 0 || w == 0) 566 return oldbit; 567 else 568 return find_nth_bit(new, bits, n % w); 569 } 570 EXPORT_SYMBOL(bitmap_bitremap); 571 572 #ifdef CONFIG_NUMA 573 /** 574 * bitmap_onto - translate one bitmap relative to another 575 * @dst: resulting translated bitmap 576 * @orig: original untranslated bitmap 577 * @relmap: bitmap relative to which translated 578 * @bits: number of bits in each of these bitmaps 579 * 580 * Set the n-th bit of @dst iff there exists some m such that the 581 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 582 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 583 * (If you understood the previous sentence the first time your 584 * read it, you're overqualified for your current job.) 585 * 586 * In other words, @orig is mapped onto (surjectively) @dst, 587 * using the map { <n, m> | the n-th bit of @relmap is the 588 * m-th set bit of @relmap }. 589 * 590 * Any set bits in @orig above bit number W, where W is the 591 * weight of (number of set bits in) @relmap are mapped nowhere. 592 * In particular, if for all bits m set in @orig, m >= W, then 593 * @dst will end up empty. In situations where the possibility 594 * of such an empty result is not desired, one way to avoid it is 595 * to use the bitmap_fold() operator, below, to first fold the 596 * @orig bitmap over itself so that all its set bits x are in the 597 * range 0 <= x < W. The bitmap_fold() operator does this by 598 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 599 * 600 * Example [1] for bitmap_onto(): 601 * Let's say @relmap has bits 30-39 set, and @orig has bits 602 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 603 * @dst will have bits 31, 33, 35, 37 and 39 set. 604 * 605 * When bit 0 is set in @orig, it means turn on the bit in 606 * @dst corresponding to whatever is the first bit (if any) 607 * that is turned on in @relmap. Since bit 0 was off in the 608 * above example, we leave off that bit (bit 30) in @dst. 609 * 610 * When bit 1 is set in @orig (as in the above example), it 611 * means turn on the bit in @dst corresponding to whatever 612 * is the second bit that is turned on in @relmap. The second 613 * bit in @relmap that was turned on in the above example was 614 * bit 31, so we turned on bit 31 in @dst. 615 * 616 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 617 * because they were the 4th, 6th, 8th and 10th set bits 618 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 619 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 620 * 621 * When bit 11 is set in @orig, it means turn on the bit in 622 * @dst corresponding to whatever is the twelfth bit that is 623 * turned on in @relmap. In the above example, there were 624 * only ten bits turned on in @relmap (30..39), so that bit 625 * 11 was set in @orig had no affect on @dst. 626 * 627 * Example [2] for bitmap_fold() + bitmap_onto(): 628 * Let's say @relmap has these ten bits set:: 629 * 630 * 40 41 42 43 45 48 53 61 74 95 631 * 632 * (for the curious, that's 40 plus the first ten terms of the 633 * Fibonacci sequence.) 634 * 635 * Further lets say we use the following code, invoking 636 * bitmap_fold() then bitmap_onto, as suggested above to 637 * avoid the possibility of an empty @dst result:: 638 * 639 * unsigned long *tmp; // a temporary bitmap's bits 640 * 641 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 642 * bitmap_onto(dst, tmp, relmap, bits); 643 * 644 * Then this table shows what various values of @dst would be, for 645 * various @orig's. I list the zero-based positions of each set bit. 646 * The tmp column shows the intermediate result, as computed by 647 * using bitmap_fold() to fold the @orig bitmap modulo ten 648 * (the weight of @relmap): 649 * 650 * =============== ============== ================= 651 * @orig tmp @dst 652 * 0 0 40 653 * 1 1 41 654 * 9 9 95 655 * 10 0 40 [#f1]_ 656 * 1 3 5 7 1 3 5 7 41 43 48 61 657 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 658 * 0 9 18 27 0 9 8 7 40 61 74 95 659 * 0 10 20 30 0 40 660 * 0 11 22 33 0 1 2 3 40 41 42 43 661 * 0 12 24 36 0 2 4 6 40 42 45 53 662 * 78 102 211 1 2 8 41 42 74 [#f1]_ 663 * =============== ============== ================= 664 * 665 * .. [#f1] 666 * 667 * For these marked lines, if we hadn't first done bitmap_fold() 668 * into tmp, then the @dst result would have been empty. 669 * 670 * If either of @orig or @relmap is empty (no set bits), then @dst 671 * will be returned empty. 672 * 673 * If (as explained above) the only set bits in @orig are in positions 674 * m where m >= W, (where W is the weight of @relmap) then @dst will 675 * once again be returned empty. 676 * 677 * All bits in @dst not set by the above rule are cleared. 678 */ 679 void bitmap_onto(unsigned long *dst, const unsigned long *orig, 680 const unsigned long *relmap, unsigned int bits) 681 { 682 unsigned int n, m; /* same meaning as in above comment */ 683 684 if (dst == orig) /* following doesn't handle inplace mappings */ 685 return; 686 bitmap_zero(dst, bits); 687 688 /* 689 * The following code is a more efficient, but less 690 * obvious, equivalent to the loop: 691 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 692 * n = find_nth_bit(orig, bits, m); 693 * if (test_bit(m, orig)) 694 * set_bit(n, dst); 695 * } 696 */ 697 698 m = 0; 699 for_each_set_bit(n, relmap, bits) { 700 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 701 if (test_bit(m, orig)) 702 set_bit(n, dst); 703 m++; 704 } 705 } 706 707 /** 708 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 709 * @dst: resulting smaller bitmap 710 * @orig: original larger bitmap 711 * @sz: specified size 712 * @nbits: number of bits in each of these bitmaps 713 * 714 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 715 * Clear all other bits in @dst. See further the comment and 716 * Example [2] for bitmap_onto() for why and how to use this. 717 */ 718 void bitmap_fold(unsigned long *dst, const unsigned long *orig, 719 unsigned int sz, unsigned int nbits) 720 { 721 unsigned int oldbit; 722 723 if (dst == orig) /* following doesn't handle inplace mappings */ 724 return; 725 bitmap_zero(dst, nbits); 726 727 for_each_set_bit(oldbit, orig, nbits) 728 set_bit(oldbit % sz, dst); 729 } 730 #endif /* CONFIG_NUMA */ 731 732 unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags) 733 { 734 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long), 735 flags); 736 } 737 EXPORT_SYMBOL(bitmap_alloc); 738 739 unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags) 740 { 741 return bitmap_alloc(nbits, flags | __GFP_ZERO); 742 } 743 EXPORT_SYMBOL(bitmap_zalloc); 744 745 unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node) 746 { 747 return kmalloc_array_node(BITS_TO_LONGS(nbits), sizeof(unsigned long), 748 flags, node); 749 } 750 EXPORT_SYMBOL(bitmap_alloc_node); 751 752 unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node) 753 { 754 return bitmap_alloc_node(nbits, flags | __GFP_ZERO, node); 755 } 756 EXPORT_SYMBOL(bitmap_zalloc_node); 757 758 void bitmap_free(const unsigned long *bitmap) 759 { 760 kfree(bitmap); 761 } 762 EXPORT_SYMBOL(bitmap_free); 763 764 static void devm_bitmap_free(void *data) 765 { 766 unsigned long *bitmap = data; 767 768 bitmap_free(bitmap); 769 } 770 771 unsigned long *devm_bitmap_alloc(struct device *dev, 772 unsigned int nbits, gfp_t flags) 773 { 774 unsigned long *bitmap; 775 int ret; 776 777 bitmap = bitmap_alloc(nbits, flags); 778 if (!bitmap) 779 return NULL; 780 781 ret = devm_add_action_or_reset(dev, devm_bitmap_free, bitmap); 782 if (ret) 783 return NULL; 784 785 return bitmap; 786 } 787 EXPORT_SYMBOL_GPL(devm_bitmap_alloc); 788 789 unsigned long *devm_bitmap_zalloc(struct device *dev, 790 unsigned int nbits, gfp_t flags) 791 { 792 return devm_bitmap_alloc(dev, nbits, flags | __GFP_ZERO); 793 } 794 EXPORT_SYMBOL_GPL(devm_bitmap_zalloc); 795 796 #if BITS_PER_LONG == 64 797 /** 798 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap 799 * @bitmap: array of unsigned longs, the destination bitmap 800 * @buf: array of u32 (in host byte order), the source bitmap 801 * @nbits: number of bits in @bitmap 802 */ 803 void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits) 804 { 805 unsigned int i, halfwords; 806 807 halfwords = DIV_ROUND_UP(nbits, 32); 808 for (i = 0; i < halfwords; i++) { 809 bitmap[i/2] = (unsigned long) buf[i]; 810 if (++i < halfwords) 811 bitmap[i/2] |= ((unsigned long) buf[i]) << 32; 812 } 813 814 /* Clear tail bits in last word beyond nbits. */ 815 if (nbits % BITS_PER_LONG) 816 bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits); 817 } 818 EXPORT_SYMBOL(bitmap_from_arr32); 819 820 /** 821 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits 822 * @buf: array of u32 (in host byte order), the dest bitmap 823 * @bitmap: array of unsigned longs, the source bitmap 824 * @nbits: number of bits in @bitmap 825 */ 826 void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits) 827 { 828 unsigned int i, halfwords; 829 830 halfwords = DIV_ROUND_UP(nbits, 32); 831 for (i = 0; i < halfwords; i++) { 832 buf[i] = (u32) (bitmap[i/2] & UINT_MAX); 833 if (++i < halfwords) 834 buf[i] = (u32) (bitmap[i/2] >> 32); 835 } 836 837 /* Clear tail bits in last element of array beyond nbits. */ 838 if (nbits % BITS_PER_LONG) 839 buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31)); 840 } 841 EXPORT_SYMBOL(bitmap_to_arr32); 842 #endif 843 844 #if BITS_PER_LONG == 32 845 /** 846 * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap 847 * @bitmap: array of unsigned longs, the destination bitmap 848 * @buf: array of u64 (in host byte order), the source bitmap 849 * @nbits: number of bits in @bitmap 850 */ 851 void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits) 852 { 853 int n; 854 855 for (n = nbits; n > 0; n -= 64) { 856 u64 val = *buf++; 857 858 *bitmap++ = val; 859 if (n > 32) 860 *bitmap++ = val >> 32; 861 } 862 863 /* 864 * Clear tail bits in the last word beyond nbits. 865 * 866 * Negative index is OK because here we point to the word next 867 * to the last word of the bitmap, except for nbits == 0, which 868 * is tested implicitly. 869 */ 870 if (nbits % BITS_PER_LONG) 871 bitmap[-1] &= BITMAP_LAST_WORD_MASK(nbits); 872 } 873 EXPORT_SYMBOL(bitmap_from_arr64); 874 875 /** 876 * bitmap_to_arr64 - copy the contents of bitmap to a u64 array of bits 877 * @buf: array of u64 (in host byte order), the dest bitmap 878 * @bitmap: array of unsigned longs, the source bitmap 879 * @nbits: number of bits in @bitmap 880 */ 881 void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits) 882 { 883 const unsigned long *end = bitmap + BITS_TO_LONGS(nbits); 884 885 while (bitmap < end) { 886 *buf = *bitmap++; 887 if (bitmap < end) 888 *buf |= (u64)(*bitmap++) << 32; 889 buf++; 890 } 891 892 /* Clear tail bits in the last element of array beyond nbits. */ 893 if (nbits % 64) 894 buf[-1] &= GENMASK_ULL((nbits - 1) % 64, 0); 895 } 896 EXPORT_SYMBOL(bitmap_to_arr64); 897 #endif 898