1 /* 2 * lib/bitmap.c 3 * Helper functions for bitmap.h. 4 * 5 * This source code is licensed under the GNU General Public License, 6 * Version 2. See the file COPYING for more details. 7 */ 8 #include <linux/export.h> 9 #include <linux/thread_info.h> 10 #include <linux/ctype.h> 11 #include <linux/errno.h> 12 #include <linux/bitmap.h> 13 #include <linux/bitops.h> 14 #include <linux/bug.h> 15 16 #include <asm/page.h> 17 #include <asm/uaccess.h> 18 19 /* 20 * bitmaps provide an array of bits, implemented using an an 21 * array of unsigned longs. The number of valid bits in a 22 * given bitmap does _not_ need to be an exact multiple of 23 * BITS_PER_LONG. 24 * 25 * The possible unused bits in the last, partially used word 26 * of a bitmap are 'don't care'. The implementation makes 27 * no particular effort to keep them zero. It ensures that 28 * their value will not affect the results of any operation. 29 * The bitmap operations that return Boolean (bitmap_empty, 30 * for example) or scalar (bitmap_weight, for example) results 31 * carefully filter out these unused bits from impacting their 32 * results. 33 * 34 * These operations actually hold to a slightly stronger rule: 35 * if you don't input any bitmaps to these ops that have some 36 * unused bits set, then they won't output any set unused bits 37 * in output bitmaps. 38 * 39 * The byte ordering of bitmaps is more natural on little 40 * endian architectures. See the big-endian headers 41 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h 42 * for the best explanations of this ordering. 43 */ 44 45 int __bitmap_equal(const unsigned long *bitmap1, 46 const unsigned long *bitmap2, unsigned int bits) 47 { 48 unsigned int k, lim = bits/BITS_PER_LONG; 49 for (k = 0; k < lim; ++k) 50 if (bitmap1[k] != bitmap2[k]) 51 return 0; 52 53 if (bits % BITS_PER_LONG) 54 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 55 return 0; 56 57 return 1; 58 } 59 EXPORT_SYMBOL(__bitmap_equal); 60 61 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits) 62 { 63 unsigned int k, lim = bits/BITS_PER_LONG; 64 for (k = 0; k < lim; ++k) 65 dst[k] = ~src[k]; 66 67 if (bits % BITS_PER_LONG) 68 dst[k] = ~src[k]; 69 } 70 EXPORT_SYMBOL(__bitmap_complement); 71 72 /** 73 * __bitmap_shift_right - logical right shift of the bits in a bitmap 74 * @dst : destination bitmap 75 * @src : source bitmap 76 * @shift : shift by this many bits 77 * @nbits : bitmap size, in bits 78 * 79 * Shifting right (dividing) means moving bits in the MS -> LS bit 80 * direction. Zeros are fed into the vacated MS positions and the 81 * LS bits shifted off the bottom are lost. 82 */ 83 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src, 84 unsigned shift, unsigned nbits) 85 { 86 unsigned k, lim = BITS_TO_LONGS(nbits); 87 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; 88 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits); 89 for (k = 0; off + k < lim; ++k) { 90 unsigned long upper, lower; 91 92 /* 93 * If shift is not word aligned, take lower rem bits of 94 * word above and make them the top rem bits of result. 95 */ 96 if (!rem || off + k + 1 >= lim) 97 upper = 0; 98 else { 99 upper = src[off + k + 1]; 100 if (off + k + 1 == lim - 1) 101 upper &= mask; 102 upper <<= (BITS_PER_LONG - rem); 103 } 104 lower = src[off + k]; 105 if (off + k == lim - 1) 106 lower &= mask; 107 lower >>= rem; 108 dst[k] = lower | upper; 109 } 110 if (off) 111 memset(&dst[lim - off], 0, off*sizeof(unsigned long)); 112 } 113 EXPORT_SYMBOL(__bitmap_shift_right); 114 115 116 /** 117 * __bitmap_shift_left - logical left shift of the bits in a bitmap 118 * @dst : destination bitmap 119 * @src : source bitmap 120 * @shift : shift by this many bits 121 * @nbits : bitmap size, in bits 122 * 123 * Shifting left (multiplying) means moving bits in the LS -> MS 124 * direction. Zeros are fed into the vacated LS bit positions 125 * and those MS bits shifted off the top are lost. 126 */ 127 128 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src, 129 unsigned int shift, unsigned int nbits) 130 { 131 int k; 132 unsigned int lim = BITS_TO_LONGS(nbits); 133 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; 134 for (k = lim - off - 1; k >= 0; --k) { 135 unsigned long upper, lower; 136 137 /* 138 * If shift is not word aligned, take upper rem bits of 139 * word below and make them the bottom rem bits of result. 140 */ 141 if (rem && k > 0) 142 lower = src[k - 1] >> (BITS_PER_LONG - rem); 143 else 144 lower = 0; 145 upper = src[k] << rem; 146 dst[k + off] = lower | upper; 147 } 148 if (off) 149 memset(dst, 0, off*sizeof(unsigned long)); 150 } 151 EXPORT_SYMBOL(__bitmap_shift_left); 152 153 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1, 154 const unsigned long *bitmap2, unsigned int bits) 155 { 156 unsigned int k; 157 unsigned int lim = bits/BITS_PER_LONG; 158 unsigned long result = 0; 159 160 for (k = 0; k < lim; k++) 161 result |= (dst[k] = bitmap1[k] & bitmap2[k]); 162 if (bits % BITS_PER_LONG) 163 result |= (dst[k] = bitmap1[k] & bitmap2[k] & 164 BITMAP_LAST_WORD_MASK(bits)); 165 return result != 0; 166 } 167 EXPORT_SYMBOL(__bitmap_and); 168 169 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1, 170 const unsigned long *bitmap2, unsigned int bits) 171 { 172 unsigned int k; 173 unsigned int nr = BITS_TO_LONGS(bits); 174 175 for (k = 0; k < nr; k++) 176 dst[k] = bitmap1[k] | bitmap2[k]; 177 } 178 EXPORT_SYMBOL(__bitmap_or); 179 180 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1, 181 const unsigned long *bitmap2, unsigned int bits) 182 { 183 unsigned int k; 184 unsigned int nr = BITS_TO_LONGS(bits); 185 186 for (k = 0; k < nr; k++) 187 dst[k] = bitmap1[k] ^ bitmap2[k]; 188 } 189 EXPORT_SYMBOL(__bitmap_xor); 190 191 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, 192 const unsigned long *bitmap2, unsigned int bits) 193 { 194 unsigned int k; 195 unsigned int lim = bits/BITS_PER_LONG; 196 unsigned long result = 0; 197 198 for (k = 0; k < lim; k++) 199 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]); 200 if (bits % BITS_PER_LONG) 201 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] & 202 BITMAP_LAST_WORD_MASK(bits)); 203 return result != 0; 204 } 205 EXPORT_SYMBOL(__bitmap_andnot); 206 207 int __bitmap_intersects(const unsigned long *bitmap1, 208 const unsigned long *bitmap2, unsigned int bits) 209 { 210 unsigned int k, lim = bits/BITS_PER_LONG; 211 for (k = 0; k < lim; ++k) 212 if (bitmap1[k] & bitmap2[k]) 213 return 1; 214 215 if (bits % BITS_PER_LONG) 216 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 217 return 1; 218 return 0; 219 } 220 EXPORT_SYMBOL(__bitmap_intersects); 221 222 int __bitmap_subset(const unsigned long *bitmap1, 223 const unsigned long *bitmap2, unsigned int bits) 224 { 225 unsigned int k, lim = bits/BITS_PER_LONG; 226 for (k = 0; k < lim; ++k) 227 if (bitmap1[k] & ~bitmap2[k]) 228 return 0; 229 230 if (bits % BITS_PER_LONG) 231 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) 232 return 0; 233 return 1; 234 } 235 EXPORT_SYMBOL(__bitmap_subset); 236 237 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits) 238 { 239 unsigned int k, lim = bits/BITS_PER_LONG; 240 int w = 0; 241 242 for (k = 0; k < lim; k++) 243 w += hweight_long(bitmap[k]); 244 245 if (bits % BITS_PER_LONG) 246 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); 247 248 return w; 249 } 250 EXPORT_SYMBOL(__bitmap_weight); 251 252 void bitmap_set(unsigned long *map, unsigned int start, int len) 253 { 254 unsigned long *p = map + BIT_WORD(start); 255 const unsigned int size = start + len; 256 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); 257 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); 258 259 while (len - bits_to_set >= 0) { 260 *p |= mask_to_set; 261 len -= bits_to_set; 262 bits_to_set = BITS_PER_LONG; 263 mask_to_set = ~0UL; 264 p++; 265 } 266 if (len) { 267 mask_to_set &= BITMAP_LAST_WORD_MASK(size); 268 *p |= mask_to_set; 269 } 270 } 271 EXPORT_SYMBOL(bitmap_set); 272 273 void bitmap_clear(unsigned long *map, unsigned int start, int len) 274 { 275 unsigned long *p = map + BIT_WORD(start); 276 const unsigned int size = start + len; 277 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); 278 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); 279 280 while (len - bits_to_clear >= 0) { 281 *p &= ~mask_to_clear; 282 len -= bits_to_clear; 283 bits_to_clear = BITS_PER_LONG; 284 mask_to_clear = ~0UL; 285 p++; 286 } 287 if (len) { 288 mask_to_clear &= BITMAP_LAST_WORD_MASK(size); 289 *p &= ~mask_to_clear; 290 } 291 } 292 EXPORT_SYMBOL(bitmap_clear); 293 294 /** 295 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area 296 * @map: The address to base the search on 297 * @size: The bitmap size in bits 298 * @start: The bitnumber to start searching at 299 * @nr: The number of zeroed bits we're looking for 300 * @align_mask: Alignment mask for zero area 301 * @align_offset: Alignment offset for zero area. 302 * 303 * The @align_mask should be one less than a power of 2; the effect is that 304 * the bit offset of all zero areas this function finds plus @align_offset 305 * is multiple of that power of 2. 306 */ 307 unsigned long bitmap_find_next_zero_area_off(unsigned long *map, 308 unsigned long size, 309 unsigned long start, 310 unsigned int nr, 311 unsigned long align_mask, 312 unsigned long align_offset) 313 { 314 unsigned long index, end, i; 315 again: 316 index = find_next_zero_bit(map, size, start); 317 318 /* Align allocation */ 319 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset; 320 321 end = index + nr; 322 if (end > size) 323 return end; 324 i = find_next_bit(map, end, index); 325 if (i < end) { 326 start = i + 1; 327 goto again; 328 } 329 return index; 330 } 331 EXPORT_SYMBOL(bitmap_find_next_zero_area_off); 332 333 /* 334 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers, 335 * second version by Paul Jackson, third by Joe Korty. 336 */ 337 338 #define CHUNKSZ 32 339 #define nbits_to_hold_value(val) fls(val) 340 #define BASEDEC 10 /* fancier cpuset lists input in decimal */ 341 342 /** 343 * __bitmap_parse - convert an ASCII hex string into a bitmap. 344 * @buf: pointer to buffer containing string. 345 * @buflen: buffer size in bytes. If string is smaller than this 346 * then it must be terminated with a \0. 347 * @is_user: location of buffer, 0 indicates kernel space 348 * @maskp: pointer to bitmap array that will contain result. 349 * @nmaskbits: size of bitmap, in bits. 350 * 351 * Commas group hex digits into chunks. Each chunk defines exactly 32 352 * bits of the resultant bitmask. No chunk may specify a value larger 353 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value 354 * then leading 0-bits are prepended. %-EINVAL is returned for illegal 355 * characters and for grouping errors such as "1,,5", ",44", "," and "". 356 * Leading and trailing whitespace accepted, but not embedded whitespace. 357 */ 358 int __bitmap_parse(const char *buf, unsigned int buflen, 359 int is_user, unsigned long *maskp, 360 int nmaskbits) 361 { 362 int c, old_c, totaldigits, ndigits, nchunks, nbits; 363 u32 chunk; 364 const char __user __force *ubuf = (const char __user __force *)buf; 365 366 bitmap_zero(maskp, nmaskbits); 367 368 nchunks = nbits = totaldigits = c = 0; 369 do { 370 chunk = 0; 371 ndigits = totaldigits; 372 373 /* Get the next chunk of the bitmap */ 374 while (buflen) { 375 old_c = c; 376 if (is_user) { 377 if (__get_user(c, ubuf++)) 378 return -EFAULT; 379 } 380 else 381 c = *buf++; 382 buflen--; 383 if (isspace(c)) 384 continue; 385 386 /* 387 * If the last character was a space and the current 388 * character isn't '\0', we've got embedded whitespace. 389 * This is a no-no, so throw an error. 390 */ 391 if (totaldigits && c && isspace(old_c)) 392 return -EINVAL; 393 394 /* A '\0' or a ',' signal the end of the chunk */ 395 if (c == '\0' || c == ',') 396 break; 397 398 if (!isxdigit(c)) 399 return -EINVAL; 400 401 /* 402 * Make sure there are at least 4 free bits in 'chunk'. 403 * If not, this hexdigit will overflow 'chunk', so 404 * throw an error. 405 */ 406 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1)) 407 return -EOVERFLOW; 408 409 chunk = (chunk << 4) | hex_to_bin(c); 410 totaldigits++; 411 } 412 if (ndigits == totaldigits) 413 return -EINVAL; 414 if (nchunks == 0 && chunk == 0) 415 continue; 416 417 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits); 418 *maskp |= chunk; 419 nchunks++; 420 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ; 421 if (nbits > nmaskbits) 422 return -EOVERFLOW; 423 } while (buflen && c == ','); 424 425 return 0; 426 } 427 EXPORT_SYMBOL(__bitmap_parse); 428 429 /** 430 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap 431 * 432 * @ubuf: pointer to user buffer containing string. 433 * @ulen: buffer size in bytes. If string is smaller than this 434 * then it must be terminated with a \0. 435 * @maskp: pointer to bitmap array that will contain result. 436 * @nmaskbits: size of bitmap, in bits. 437 * 438 * Wrapper for __bitmap_parse(), providing it with user buffer. 439 * 440 * We cannot have this as an inline function in bitmap.h because it needs 441 * linux/uaccess.h to get the access_ok() declaration and this causes 442 * cyclic dependencies. 443 */ 444 int bitmap_parse_user(const char __user *ubuf, 445 unsigned int ulen, unsigned long *maskp, 446 int nmaskbits) 447 { 448 if (!access_ok(VERIFY_READ, ubuf, ulen)) 449 return -EFAULT; 450 return __bitmap_parse((const char __force *)ubuf, 451 ulen, 1, maskp, nmaskbits); 452 453 } 454 EXPORT_SYMBOL(bitmap_parse_user); 455 456 /** 457 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string 458 * @list: indicates whether the bitmap must be list 459 * @buf: page aligned buffer into which string is placed 460 * @maskp: pointer to bitmap to convert 461 * @nmaskbits: size of bitmap, in bits 462 * 463 * Output format is a comma-separated list of decimal numbers and 464 * ranges if list is specified or hex digits grouped into comma-separated 465 * sets of 8 digits/set. Returns the number of characters written to buf. 466 * 467 * It is assumed that @buf is a pointer into a PAGE_SIZE area and that 468 * sufficient storage remains at @buf to accommodate the 469 * bitmap_print_to_pagebuf() output. 470 */ 471 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp, 472 int nmaskbits) 473 { 474 ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf; 475 int n = 0; 476 477 if (len > 1) 478 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) : 479 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp); 480 return n; 481 } 482 EXPORT_SYMBOL(bitmap_print_to_pagebuf); 483 484 /** 485 * __bitmap_parselist - convert list format ASCII string to bitmap 486 * @buf: read nul-terminated user string from this buffer 487 * @buflen: buffer size in bytes. If string is smaller than this 488 * then it must be terminated with a \0. 489 * @is_user: location of buffer, 0 indicates kernel space 490 * @maskp: write resulting mask here 491 * @nmaskbits: number of bits in mask to be written 492 * 493 * Input format is a comma-separated list of decimal numbers and 494 * ranges. Consecutively set bits are shown as two hyphen-separated 495 * decimal numbers, the smallest and largest bit numbers set in 496 * the range. 497 * 498 * Returns 0 on success, -errno on invalid input strings. 499 * Error values: 500 * %-EINVAL: second number in range smaller than first 501 * %-EINVAL: invalid character in string 502 * %-ERANGE: bit number specified too large for mask 503 */ 504 static int __bitmap_parselist(const char *buf, unsigned int buflen, 505 int is_user, unsigned long *maskp, 506 int nmaskbits) 507 { 508 unsigned a, b; 509 int c, old_c, totaldigits, ndigits; 510 const char __user __force *ubuf = (const char __user __force *)buf; 511 int at_start, in_range; 512 513 totaldigits = c = 0; 514 bitmap_zero(maskp, nmaskbits); 515 do { 516 at_start = 1; 517 in_range = 0; 518 a = b = 0; 519 ndigits = totaldigits; 520 521 /* Get the next cpu# or a range of cpu#'s */ 522 while (buflen) { 523 old_c = c; 524 if (is_user) { 525 if (__get_user(c, ubuf++)) 526 return -EFAULT; 527 } else 528 c = *buf++; 529 buflen--; 530 if (isspace(c)) 531 continue; 532 533 /* A '\0' or a ',' signal the end of a cpu# or range */ 534 if (c == '\0' || c == ',') 535 break; 536 /* 537 * whitespaces between digits are not allowed, 538 * but it's ok if whitespaces are on head or tail. 539 * when old_c is whilespace, 540 * if totaldigits == ndigits, whitespace is on head. 541 * if whitespace is on tail, it should not run here. 542 * as c was ',' or '\0', 543 * the last code line has broken the current loop. 544 */ 545 if ((totaldigits != ndigits) && isspace(old_c)) 546 return -EINVAL; 547 548 if (c == '-') { 549 if (at_start || in_range) 550 return -EINVAL; 551 b = 0; 552 in_range = 1; 553 at_start = 1; 554 continue; 555 } 556 557 if (!isdigit(c)) 558 return -EINVAL; 559 560 b = b * 10 + (c - '0'); 561 if (!in_range) 562 a = b; 563 at_start = 0; 564 totaldigits++; 565 } 566 if (ndigits == totaldigits) 567 continue; 568 /* if no digit is after '-', it's wrong*/ 569 if (at_start && in_range) 570 return -EINVAL; 571 if (!(a <= b)) 572 return -EINVAL; 573 if (b >= nmaskbits) 574 return -ERANGE; 575 while (a <= b) { 576 set_bit(a, maskp); 577 a++; 578 } 579 } while (buflen && c == ','); 580 return 0; 581 } 582 583 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits) 584 { 585 char *nl = strchrnul(bp, '\n'); 586 int len = nl - bp; 587 588 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits); 589 } 590 EXPORT_SYMBOL(bitmap_parselist); 591 592 593 /** 594 * bitmap_parselist_user() 595 * 596 * @ubuf: pointer to user buffer containing string. 597 * @ulen: buffer size in bytes. If string is smaller than this 598 * then it must be terminated with a \0. 599 * @maskp: pointer to bitmap array that will contain result. 600 * @nmaskbits: size of bitmap, in bits. 601 * 602 * Wrapper for bitmap_parselist(), providing it with user buffer. 603 * 604 * We cannot have this as an inline function in bitmap.h because it needs 605 * linux/uaccess.h to get the access_ok() declaration and this causes 606 * cyclic dependencies. 607 */ 608 int bitmap_parselist_user(const char __user *ubuf, 609 unsigned int ulen, unsigned long *maskp, 610 int nmaskbits) 611 { 612 if (!access_ok(VERIFY_READ, ubuf, ulen)) 613 return -EFAULT; 614 return __bitmap_parselist((const char __force *)ubuf, 615 ulen, 1, maskp, nmaskbits); 616 } 617 EXPORT_SYMBOL(bitmap_parselist_user); 618 619 620 /** 621 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap 622 * @buf: pointer to a bitmap 623 * @pos: a bit position in @buf (0 <= @pos < @nbits) 624 * @nbits: number of valid bit positions in @buf 625 * 626 * Map the bit at position @pos in @buf (of length @nbits) to the 627 * ordinal of which set bit it is. If it is not set or if @pos 628 * is not a valid bit position, map to -1. 629 * 630 * If for example, just bits 4 through 7 are set in @buf, then @pos 631 * values 4 through 7 will get mapped to 0 through 3, respectively, 632 * and other @pos values will get mapped to -1. When @pos value 7 633 * gets mapped to (returns) @ord value 3 in this example, that means 634 * that bit 7 is the 3rd (starting with 0th) set bit in @buf. 635 * 636 * The bit positions 0 through @bits are valid positions in @buf. 637 */ 638 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits) 639 { 640 if (pos >= nbits || !test_bit(pos, buf)) 641 return -1; 642 643 return __bitmap_weight(buf, pos); 644 } 645 646 /** 647 * bitmap_ord_to_pos - find position of n-th set bit in bitmap 648 * @buf: pointer to bitmap 649 * @ord: ordinal bit position (n-th set bit, n >= 0) 650 * @nbits: number of valid bit positions in @buf 651 * 652 * Map the ordinal offset of bit @ord in @buf to its position in @buf. 653 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord 654 * >= weight(buf), returns @nbits. 655 * 656 * If for example, just bits 4 through 7 are set in @buf, then @ord 657 * values 0 through 3 will get mapped to 4 through 7, respectively, 658 * and all other @ord values returns @nbits. When @ord value 3 659 * gets mapped to (returns) @pos value 7 in this example, that means 660 * that the 3rd set bit (starting with 0th) is at position 7 in @buf. 661 * 662 * The bit positions 0 through @nbits-1 are valid positions in @buf. 663 */ 664 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits) 665 { 666 unsigned int pos; 667 668 for (pos = find_first_bit(buf, nbits); 669 pos < nbits && ord; 670 pos = find_next_bit(buf, nbits, pos + 1)) 671 ord--; 672 673 return pos; 674 } 675 676 /** 677 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap 678 * @dst: remapped result 679 * @src: subset to be remapped 680 * @old: defines domain of map 681 * @new: defines range of map 682 * @nbits: number of bits in each of these bitmaps 683 * 684 * Let @old and @new define a mapping of bit positions, such that 685 * whatever position is held by the n-th set bit in @old is mapped 686 * to the n-th set bit in @new. In the more general case, allowing 687 * for the possibility that the weight 'w' of @new is less than the 688 * weight of @old, map the position of the n-th set bit in @old to 689 * the position of the m-th set bit in @new, where m == n % w. 690 * 691 * If either of the @old and @new bitmaps are empty, or if @src and 692 * @dst point to the same location, then this routine copies @src 693 * to @dst. 694 * 695 * The positions of unset bits in @old are mapped to themselves 696 * (the identify map). 697 * 698 * Apply the above specified mapping to @src, placing the result in 699 * @dst, clearing any bits previously set in @dst. 700 * 701 * For example, lets say that @old has bits 4 through 7 set, and 702 * @new has bits 12 through 15 set. This defines the mapping of bit 703 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 704 * bit positions unchanged. So if say @src comes into this routine 705 * with bits 1, 5 and 7 set, then @dst should leave with bits 1, 706 * 13 and 15 set. 707 */ 708 void bitmap_remap(unsigned long *dst, const unsigned long *src, 709 const unsigned long *old, const unsigned long *new, 710 unsigned int nbits) 711 { 712 unsigned int oldbit, w; 713 714 if (dst == src) /* following doesn't handle inplace remaps */ 715 return; 716 bitmap_zero(dst, nbits); 717 718 w = bitmap_weight(new, nbits); 719 for_each_set_bit(oldbit, src, nbits) { 720 int n = bitmap_pos_to_ord(old, oldbit, nbits); 721 722 if (n < 0 || w == 0) 723 set_bit(oldbit, dst); /* identity map */ 724 else 725 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst); 726 } 727 } 728 EXPORT_SYMBOL(bitmap_remap); 729 730 /** 731 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit 732 * @oldbit: bit position to be mapped 733 * @old: defines domain of map 734 * @new: defines range of map 735 * @bits: number of bits in each of these bitmaps 736 * 737 * Let @old and @new define a mapping of bit positions, such that 738 * whatever position is held by the n-th set bit in @old is mapped 739 * to the n-th set bit in @new. In the more general case, allowing 740 * for the possibility that the weight 'w' of @new is less than the 741 * weight of @old, map the position of the n-th set bit in @old to 742 * the position of the m-th set bit in @new, where m == n % w. 743 * 744 * The positions of unset bits in @old are mapped to themselves 745 * (the identify map). 746 * 747 * Apply the above specified mapping to bit position @oldbit, returning 748 * the new bit position. 749 * 750 * For example, lets say that @old has bits 4 through 7 set, and 751 * @new has bits 12 through 15 set. This defines the mapping of bit 752 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other 753 * bit positions unchanged. So if say @oldbit is 5, then this routine 754 * returns 13. 755 */ 756 int bitmap_bitremap(int oldbit, const unsigned long *old, 757 const unsigned long *new, int bits) 758 { 759 int w = bitmap_weight(new, bits); 760 int n = bitmap_pos_to_ord(old, oldbit, bits); 761 if (n < 0 || w == 0) 762 return oldbit; 763 else 764 return bitmap_ord_to_pos(new, n % w, bits); 765 } 766 EXPORT_SYMBOL(bitmap_bitremap); 767 768 /** 769 * bitmap_onto - translate one bitmap relative to another 770 * @dst: resulting translated bitmap 771 * @orig: original untranslated bitmap 772 * @relmap: bitmap relative to which translated 773 * @bits: number of bits in each of these bitmaps 774 * 775 * Set the n-th bit of @dst iff there exists some m such that the 776 * n-th bit of @relmap is set, the m-th bit of @orig is set, and 777 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. 778 * (If you understood the previous sentence the first time your 779 * read it, you're overqualified for your current job.) 780 * 781 * In other words, @orig is mapped onto (surjectively) @dst, 782 * using the map { <n, m> | the n-th bit of @relmap is the 783 * m-th set bit of @relmap }. 784 * 785 * Any set bits in @orig above bit number W, where W is the 786 * weight of (number of set bits in) @relmap are mapped nowhere. 787 * In particular, if for all bits m set in @orig, m >= W, then 788 * @dst will end up empty. In situations where the possibility 789 * of such an empty result is not desired, one way to avoid it is 790 * to use the bitmap_fold() operator, below, to first fold the 791 * @orig bitmap over itself so that all its set bits x are in the 792 * range 0 <= x < W. The bitmap_fold() operator does this by 793 * setting the bit (m % W) in @dst, for each bit (m) set in @orig. 794 * 795 * Example [1] for bitmap_onto(): 796 * Let's say @relmap has bits 30-39 set, and @orig has bits 797 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, 798 * @dst will have bits 31, 33, 35, 37 and 39 set. 799 * 800 * When bit 0 is set in @orig, it means turn on the bit in 801 * @dst corresponding to whatever is the first bit (if any) 802 * that is turned on in @relmap. Since bit 0 was off in the 803 * above example, we leave off that bit (bit 30) in @dst. 804 * 805 * When bit 1 is set in @orig (as in the above example), it 806 * means turn on the bit in @dst corresponding to whatever 807 * is the second bit that is turned on in @relmap. The second 808 * bit in @relmap that was turned on in the above example was 809 * bit 31, so we turned on bit 31 in @dst. 810 * 811 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, 812 * because they were the 4th, 6th, 8th and 10th set bits 813 * set in @relmap, and the 4th, 6th, 8th and 10th bits of 814 * @orig (i.e. bits 3, 5, 7 and 9) were also set. 815 * 816 * When bit 11 is set in @orig, it means turn on the bit in 817 * @dst corresponding to whatever is the twelfth bit that is 818 * turned on in @relmap. In the above example, there were 819 * only ten bits turned on in @relmap (30..39), so that bit 820 * 11 was set in @orig had no affect on @dst. 821 * 822 * Example [2] for bitmap_fold() + bitmap_onto(): 823 * Let's say @relmap has these ten bits set: 824 * 40 41 42 43 45 48 53 61 74 95 825 * (for the curious, that's 40 plus the first ten terms of the 826 * Fibonacci sequence.) 827 * 828 * Further lets say we use the following code, invoking 829 * bitmap_fold() then bitmap_onto, as suggested above to 830 * avoid the possibility of an empty @dst result: 831 * 832 * unsigned long *tmp; // a temporary bitmap's bits 833 * 834 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); 835 * bitmap_onto(dst, tmp, relmap, bits); 836 * 837 * Then this table shows what various values of @dst would be, for 838 * various @orig's. I list the zero-based positions of each set bit. 839 * The tmp column shows the intermediate result, as computed by 840 * using bitmap_fold() to fold the @orig bitmap modulo ten 841 * (the weight of @relmap). 842 * 843 * @orig tmp @dst 844 * 0 0 40 845 * 1 1 41 846 * 9 9 95 847 * 10 0 40 (*) 848 * 1 3 5 7 1 3 5 7 41 43 48 61 849 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 850 * 0 9 18 27 0 9 8 7 40 61 74 95 851 * 0 10 20 30 0 40 852 * 0 11 22 33 0 1 2 3 40 41 42 43 853 * 0 12 24 36 0 2 4 6 40 42 45 53 854 * 78 102 211 1 2 8 41 42 74 (*) 855 * 856 * (*) For these marked lines, if we hadn't first done bitmap_fold() 857 * into tmp, then the @dst result would have been empty. 858 * 859 * If either of @orig or @relmap is empty (no set bits), then @dst 860 * will be returned empty. 861 * 862 * If (as explained above) the only set bits in @orig are in positions 863 * m where m >= W, (where W is the weight of @relmap) then @dst will 864 * once again be returned empty. 865 * 866 * All bits in @dst not set by the above rule are cleared. 867 */ 868 void bitmap_onto(unsigned long *dst, const unsigned long *orig, 869 const unsigned long *relmap, unsigned int bits) 870 { 871 unsigned int n, m; /* same meaning as in above comment */ 872 873 if (dst == orig) /* following doesn't handle inplace mappings */ 874 return; 875 bitmap_zero(dst, bits); 876 877 /* 878 * The following code is a more efficient, but less 879 * obvious, equivalent to the loop: 880 * for (m = 0; m < bitmap_weight(relmap, bits); m++) { 881 * n = bitmap_ord_to_pos(orig, m, bits); 882 * if (test_bit(m, orig)) 883 * set_bit(n, dst); 884 * } 885 */ 886 887 m = 0; 888 for_each_set_bit(n, relmap, bits) { 889 /* m == bitmap_pos_to_ord(relmap, n, bits) */ 890 if (test_bit(m, orig)) 891 set_bit(n, dst); 892 m++; 893 } 894 } 895 EXPORT_SYMBOL(bitmap_onto); 896 897 /** 898 * bitmap_fold - fold larger bitmap into smaller, modulo specified size 899 * @dst: resulting smaller bitmap 900 * @orig: original larger bitmap 901 * @sz: specified size 902 * @nbits: number of bits in each of these bitmaps 903 * 904 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. 905 * Clear all other bits in @dst. See further the comment and 906 * Example [2] for bitmap_onto() for why and how to use this. 907 */ 908 void bitmap_fold(unsigned long *dst, const unsigned long *orig, 909 unsigned int sz, unsigned int nbits) 910 { 911 unsigned int oldbit; 912 913 if (dst == orig) /* following doesn't handle inplace mappings */ 914 return; 915 bitmap_zero(dst, nbits); 916 917 for_each_set_bit(oldbit, orig, nbits) 918 set_bit(oldbit % sz, dst); 919 } 920 EXPORT_SYMBOL(bitmap_fold); 921 922 /* 923 * Common code for bitmap_*_region() routines. 924 * bitmap: array of unsigned longs corresponding to the bitmap 925 * pos: the beginning of the region 926 * order: region size (log base 2 of number of bits) 927 * reg_op: operation(s) to perform on that region of bitmap 928 * 929 * Can set, verify and/or release a region of bits in a bitmap, 930 * depending on which combination of REG_OP_* flag bits is set. 931 * 932 * A region of a bitmap is a sequence of bits in the bitmap, of 933 * some size '1 << order' (a power of two), aligned to that same 934 * '1 << order' power of two. 935 * 936 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). 937 * Returns 0 in all other cases and reg_ops. 938 */ 939 940 enum { 941 REG_OP_ISFREE, /* true if region is all zero bits */ 942 REG_OP_ALLOC, /* set all bits in region */ 943 REG_OP_RELEASE, /* clear all bits in region */ 944 }; 945 946 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op) 947 { 948 int nbits_reg; /* number of bits in region */ 949 int index; /* index first long of region in bitmap */ 950 int offset; /* bit offset region in bitmap[index] */ 951 int nlongs_reg; /* num longs spanned by region in bitmap */ 952 int nbitsinlong; /* num bits of region in each spanned long */ 953 unsigned long mask; /* bitmask for one long of region */ 954 int i; /* scans bitmap by longs */ 955 int ret = 0; /* return value */ 956 957 /* 958 * Either nlongs_reg == 1 (for small orders that fit in one long) 959 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) 960 */ 961 nbits_reg = 1 << order; 962 index = pos / BITS_PER_LONG; 963 offset = pos - (index * BITS_PER_LONG); 964 nlongs_reg = BITS_TO_LONGS(nbits_reg); 965 nbitsinlong = min(nbits_reg, BITS_PER_LONG); 966 967 /* 968 * Can't do "mask = (1UL << nbitsinlong) - 1", as that 969 * overflows if nbitsinlong == BITS_PER_LONG. 970 */ 971 mask = (1UL << (nbitsinlong - 1)); 972 mask += mask - 1; 973 mask <<= offset; 974 975 switch (reg_op) { 976 case REG_OP_ISFREE: 977 for (i = 0; i < nlongs_reg; i++) { 978 if (bitmap[index + i] & mask) 979 goto done; 980 } 981 ret = 1; /* all bits in region free (zero) */ 982 break; 983 984 case REG_OP_ALLOC: 985 for (i = 0; i < nlongs_reg; i++) 986 bitmap[index + i] |= mask; 987 break; 988 989 case REG_OP_RELEASE: 990 for (i = 0; i < nlongs_reg; i++) 991 bitmap[index + i] &= ~mask; 992 break; 993 } 994 done: 995 return ret; 996 } 997 998 /** 999 * bitmap_find_free_region - find a contiguous aligned mem region 1000 * @bitmap: array of unsigned longs corresponding to the bitmap 1001 * @bits: number of bits in the bitmap 1002 * @order: region size (log base 2 of number of bits) to find 1003 * 1004 * Find a region of free (zero) bits in a @bitmap of @bits bits and 1005 * allocate them (set them to one). Only consider regions of length 1006 * a power (@order) of two, aligned to that power of two, which 1007 * makes the search algorithm much faster. 1008 * 1009 * Return the bit offset in bitmap of the allocated region, 1010 * or -errno on failure. 1011 */ 1012 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order) 1013 { 1014 unsigned int pos, end; /* scans bitmap by regions of size order */ 1015 1016 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) { 1017 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1018 continue; 1019 __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1020 return pos; 1021 } 1022 return -ENOMEM; 1023 } 1024 EXPORT_SYMBOL(bitmap_find_free_region); 1025 1026 /** 1027 * bitmap_release_region - release allocated bitmap region 1028 * @bitmap: array of unsigned longs corresponding to the bitmap 1029 * @pos: beginning of bit region to release 1030 * @order: region size (log base 2 of number of bits) to release 1031 * 1032 * This is the complement to __bitmap_find_free_region() and releases 1033 * the found region (by clearing it in the bitmap). 1034 * 1035 * No return value. 1036 */ 1037 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order) 1038 { 1039 __reg_op(bitmap, pos, order, REG_OP_RELEASE); 1040 } 1041 EXPORT_SYMBOL(bitmap_release_region); 1042 1043 /** 1044 * bitmap_allocate_region - allocate bitmap region 1045 * @bitmap: array of unsigned longs corresponding to the bitmap 1046 * @pos: beginning of bit region to allocate 1047 * @order: region size (log base 2 of number of bits) to allocate 1048 * 1049 * Allocate (set bits in) a specified region of a bitmap. 1050 * 1051 * Return 0 on success, or %-EBUSY if specified region wasn't 1052 * free (not all bits were zero). 1053 */ 1054 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order) 1055 { 1056 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) 1057 return -EBUSY; 1058 return __reg_op(bitmap, pos, order, REG_OP_ALLOC); 1059 } 1060 EXPORT_SYMBOL(bitmap_allocate_region); 1061 1062 /** 1063 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. 1064 * @dst: destination buffer 1065 * @src: bitmap to copy 1066 * @nbits: number of bits in the bitmap 1067 * 1068 * Require nbits % BITS_PER_LONG == 0. 1069 */ 1070 #ifdef __BIG_ENDIAN 1071 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits) 1072 { 1073 unsigned int i; 1074 1075 for (i = 0; i < nbits/BITS_PER_LONG; i++) { 1076 if (BITS_PER_LONG == 64) 1077 dst[i] = cpu_to_le64(src[i]); 1078 else 1079 dst[i] = cpu_to_le32(src[i]); 1080 } 1081 } 1082 EXPORT_SYMBOL(bitmap_copy_le); 1083 #endif 1084