1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_BITOPS_H 3 #define _LINUX_BITOPS_H 4 5 #include <asm/types.h> 6 #include <linux/bits.h> 7 #include <linux/typecheck.h> 8 9 #include <uapi/linux/kernel.h> 10 11 #define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) 12 #define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long)) 13 #define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64)) 14 #define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32)) 15 #define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char)) 16 17 #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_BYTE) 18 19 extern unsigned int __sw_hweight8(unsigned int w); 20 extern unsigned int __sw_hweight16(unsigned int w); 21 extern unsigned int __sw_hweight32(unsigned int w); 22 extern unsigned long __sw_hweight64(__u64 w); 23 24 /* 25 * Defined here because those may be needed by architecture-specific static 26 * inlines. 27 */ 28 29 #include <asm-generic/bitops/generic-non-atomic.h> 30 31 /* 32 * Many architecture-specific non-atomic bitops contain inline asm code and due 33 * to that the compiler can't optimize them to compile-time expressions or 34 * constants. In contrary, generic_*() helpers are defined in pure C and 35 * compilers optimize them just well. 36 * Therefore, to make `unsigned long foo = 0; __set_bit(BAR, &foo)` effectively 37 * equal to `unsigned long foo = BIT(BAR)`, pick the generic C alternative when 38 * the arguments can be resolved at compile time. That expression itself is a 39 * constant and doesn't bring any functional changes to the rest of cases. 40 * The casts to `uintptr_t` are needed to mitigate `-Waddress` warnings when 41 * passing a bitmap from .bss or .data (-> `!!addr` is always true). 42 */ 43 #define bitop(op, nr, addr) \ 44 ((__builtin_constant_p(nr) && \ 45 __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \ 46 (uintptr_t)(addr) != (uintptr_t)NULL && \ 47 __builtin_constant_p(*(const unsigned long *)(addr))) ? \ 48 const##op(nr, addr) : op(nr, addr)) 49 50 /* 51 * The following macros are non-atomic versions of their non-underscored 52 * counterparts. 53 */ 54 #define __set_bit(nr, addr) bitop(___set_bit, nr, addr) 55 #define __clear_bit(nr, addr) bitop(___clear_bit, nr, addr) 56 #define __change_bit(nr, addr) bitop(___change_bit, nr, addr) 57 #define __test_and_set_bit(nr, addr) bitop(___test_and_set_bit, nr, addr) 58 #define __test_and_clear_bit(nr, addr) bitop(___test_and_clear_bit, nr, addr) 59 #define __test_and_change_bit(nr, addr) bitop(___test_and_change_bit, nr, addr) 60 61 #define test_bit(nr, addr) bitop(_test_bit, nr, addr) 62 #define test_bit_acquire(nr, addr) bitop(_test_bit_acquire, nr, addr) 63 64 /* 65 * Include this here because some architectures need generic_ffs/fls in 66 * scope 67 */ 68 #include <asm/bitops.h> 69 70 /* Check that the bitops prototypes are sane */ 71 #define __check_bitop_pr(name) \ 72 static_assert(__same_type(arch_##name, generic_##name) && \ 73 __same_type(const_##name, generic_##name) && \ 74 __same_type(_##name, generic_##name)) 75 76 __check_bitop_pr(__set_bit); 77 __check_bitop_pr(__clear_bit); 78 __check_bitop_pr(__change_bit); 79 __check_bitop_pr(__test_and_set_bit); 80 __check_bitop_pr(__test_and_clear_bit); 81 __check_bitop_pr(__test_and_change_bit); 82 __check_bitop_pr(test_bit); 83 __check_bitop_pr(test_bit_acquire); 84 85 #undef __check_bitop_pr 86 87 static inline int get_bitmask_order(unsigned int count) 88 { 89 int order; 90 91 order = fls(count); 92 return order; /* We could be slightly more clever with -1 here... */ 93 } 94 95 static __always_inline unsigned long hweight_long(unsigned long w) 96 { 97 return sizeof(w) == 4 ? hweight32(w) : hweight64((__u64)w); 98 } 99 100 /** 101 * rol64 - rotate a 64-bit value left 102 * @word: value to rotate 103 * @shift: bits to roll 104 */ 105 static inline __u64 rol64(__u64 word, unsigned int shift) 106 { 107 return (word << (shift & 63)) | (word >> ((-shift) & 63)); 108 } 109 110 /** 111 * ror64 - rotate a 64-bit value right 112 * @word: value to rotate 113 * @shift: bits to roll 114 */ 115 static inline __u64 ror64(__u64 word, unsigned int shift) 116 { 117 return (word >> (shift & 63)) | (word << ((-shift) & 63)); 118 } 119 120 /** 121 * rol32 - rotate a 32-bit value left 122 * @word: value to rotate 123 * @shift: bits to roll 124 */ 125 static inline __u32 rol32(__u32 word, unsigned int shift) 126 { 127 return (word << (shift & 31)) | (word >> ((-shift) & 31)); 128 } 129 130 /** 131 * ror32 - rotate a 32-bit value right 132 * @word: value to rotate 133 * @shift: bits to roll 134 */ 135 static inline __u32 ror32(__u32 word, unsigned int shift) 136 { 137 return (word >> (shift & 31)) | (word << ((-shift) & 31)); 138 } 139 140 /** 141 * rol16 - rotate a 16-bit value left 142 * @word: value to rotate 143 * @shift: bits to roll 144 */ 145 static inline __u16 rol16(__u16 word, unsigned int shift) 146 { 147 return (word << (shift & 15)) | (word >> ((-shift) & 15)); 148 } 149 150 /** 151 * ror16 - rotate a 16-bit value right 152 * @word: value to rotate 153 * @shift: bits to roll 154 */ 155 static inline __u16 ror16(__u16 word, unsigned int shift) 156 { 157 return (word >> (shift & 15)) | (word << ((-shift) & 15)); 158 } 159 160 /** 161 * rol8 - rotate an 8-bit value left 162 * @word: value to rotate 163 * @shift: bits to roll 164 */ 165 static inline __u8 rol8(__u8 word, unsigned int shift) 166 { 167 return (word << (shift & 7)) | (word >> ((-shift) & 7)); 168 } 169 170 /** 171 * ror8 - rotate an 8-bit value right 172 * @word: value to rotate 173 * @shift: bits to roll 174 */ 175 static inline __u8 ror8(__u8 word, unsigned int shift) 176 { 177 return (word >> (shift & 7)) | (word << ((-shift) & 7)); 178 } 179 180 /** 181 * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit 182 * @value: value to sign extend 183 * @index: 0 based bit index (0<=index<32) to sign bit 184 * 185 * This is safe to use for 16- and 8-bit types as well. 186 */ 187 static __always_inline __s32 sign_extend32(__u32 value, int index) 188 { 189 __u8 shift = 31 - index; 190 return (__s32)(value << shift) >> shift; 191 } 192 193 /** 194 * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit 195 * @value: value to sign extend 196 * @index: 0 based bit index (0<=index<64) to sign bit 197 */ 198 static __always_inline __s64 sign_extend64(__u64 value, int index) 199 { 200 __u8 shift = 63 - index; 201 return (__s64)(value << shift) >> shift; 202 } 203 204 static inline unsigned int fls_long(unsigned long l) 205 { 206 if (sizeof(l) == 4) 207 return fls(l); 208 return fls64(l); 209 } 210 211 static inline int get_count_order(unsigned int count) 212 { 213 if (count == 0) 214 return -1; 215 216 return fls(--count); 217 } 218 219 /** 220 * get_count_order_long - get order after rounding @l up to power of 2 221 * @l: parameter 222 * 223 * it is same as get_count_order() but with long type parameter 224 */ 225 static inline int get_count_order_long(unsigned long l) 226 { 227 if (l == 0UL) 228 return -1; 229 return (int)fls_long(--l); 230 } 231 232 /** 233 * parity8 - get the parity of an u8 value 234 * @value: the value to be examined 235 * 236 * Determine the parity of the u8 argument. 237 * 238 * Returns: 239 * 0 for even parity, 1 for odd parity 240 * 241 * Note: This function informs you about the current parity. Example to bail 242 * out when parity is odd: 243 * 244 * if (parity8(val) == 1) 245 * return -EBADMSG; 246 * 247 * If you need to calculate a parity bit, you need to draw the conclusion from 248 * this result yourself. Example to enforce odd parity, parity bit is bit 7: 249 * 250 * if (parity8(val) == 0) 251 * val ^= BIT(7); 252 */ 253 static inline int parity8(u8 val) 254 { 255 /* 256 * One explanation of this algorithm: 257 * https://funloop.org/codex/problem/parity/README.html 258 */ 259 val ^= val >> 4; 260 return (0x6996 >> (val & 0xf)) & 1; 261 } 262 263 /** 264 * __ffs64 - find first set bit in a 64 bit word 265 * @word: The 64 bit word 266 * 267 * On 64 bit arches this is a synonym for __ffs 268 * The result is not defined if no bits are set, so check that @word 269 * is non-zero before calling this. 270 */ 271 static inline unsigned int __ffs64(u64 word) 272 { 273 #if BITS_PER_LONG == 32 274 if (((u32)word) == 0UL) 275 return __ffs((u32)(word >> 32)) + 32; 276 #elif BITS_PER_LONG != 64 277 #error BITS_PER_LONG not 32 or 64 278 #endif 279 return __ffs((unsigned long)word); 280 } 281 282 /** 283 * fns - find N'th set bit in a word 284 * @word: The word to search 285 * @n: Bit to find 286 */ 287 static inline unsigned int fns(unsigned long word, unsigned int n) 288 { 289 while (word && n--) 290 word &= word - 1; 291 292 return word ? __ffs(word) : BITS_PER_LONG; 293 } 294 295 /** 296 * assign_bit - Assign value to a bit in memory 297 * @nr: the bit to set 298 * @addr: the address to start counting from 299 * @value: the value to assign 300 */ 301 #define assign_bit(nr, addr, value) \ 302 ((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr))) 303 304 #define __assign_bit(nr, addr, value) \ 305 ((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr))) 306 307 /** 308 * __ptr_set_bit - Set bit in a pointer's value 309 * @nr: the bit to set 310 * @addr: the address of the pointer variable 311 * 312 * Example: 313 * void *p = foo(); 314 * __ptr_set_bit(bit, &p); 315 */ 316 #define __ptr_set_bit(nr, addr) \ 317 ({ \ 318 typecheck_pointer(*(addr)); \ 319 __set_bit(nr, (unsigned long *)(addr)); \ 320 }) 321 322 /** 323 * __ptr_clear_bit - Clear bit in a pointer's value 324 * @nr: the bit to clear 325 * @addr: the address of the pointer variable 326 * 327 * Example: 328 * void *p = foo(); 329 * __ptr_clear_bit(bit, &p); 330 */ 331 #define __ptr_clear_bit(nr, addr) \ 332 ({ \ 333 typecheck_pointer(*(addr)); \ 334 __clear_bit(nr, (unsigned long *)(addr)); \ 335 }) 336 337 /** 338 * __ptr_test_bit - Test bit in a pointer's value 339 * @nr: the bit to test 340 * @addr: the address of the pointer variable 341 * 342 * Example: 343 * void *p = foo(); 344 * if (__ptr_test_bit(bit, &p)) { 345 * ... 346 * } else { 347 * ... 348 * } 349 */ 350 #define __ptr_test_bit(nr, addr) \ 351 ({ \ 352 typecheck_pointer(*(addr)); \ 353 test_bit(nr, (unsigned long *)(addr)); \ 354 }) 355 356 #ifdef __KERNEL__ 357 358 #ifndef set_mask_bits 359 #define set_mask_bits(ptr, mask, bits) \ 360 ({ \ 361 const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \ 362 typeof(*(ptr)) old__, new__; \ 363 \ 364 old__ = READ_ONCE(*(ptr)); \ 365 do { \ 366 new__ = (old__ & ~mask__) | bits__; \ 367 } while (!try_cmpxchg(ptr, &old__, new__)); \ 368 \ 369 old__; \ 370 }) 371 #endif 372 373 #ifndef bit_clear_unless 374 #define bit_clear_unless(ptr, clear, test) \ 375 ({ \ 376 const typeof(*(ptr)) clear__ = (clear), test__ = (test);\ 377 typeof(*(ptr)) old__, new__; \ 378 \ 379 old__ = READ_ONCE(*(ptr)); \ 380 do { \ 381 if (old__ & test__) \ 382 break; \ 383 new__ = old__ & ~clear__; \ 384 } while (!try_cmpxchg(ptr, &old__, new__)); \ 385 \ 386 !(old__ & test__); \ 387 }) 388 #endif 389 390 #endif /* __KERNEL__ */ 391 #endif 392