include/linux/bitops.h

   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  * __ffs64 - find first set bit in a 64 bit word
 234  * @word: The 64 bit word
 235  *
 236  * On 64 bit arches this is a synonym for __ffs
 237  * The result is not defined if no bits are set, so check that @word
 238  * is non-zero before calling this.
 239  */
 240 static inline unsigned int __ffs64(u64 word)
 241 {
 242 #if BITS_PER_LONG == 32
 243         if (((u32)word) == 0UL)
 244                 return __ffs((u32)(word >> 32)) + 32;
 245 #elif BITS_PER_LONG != 64
 246 #error BITS_PER_LONG not 32 or 64
 247 #endif
 248         return __ffs((unsigned long)word);
 249 }
 250
 251 /**
 252  * fns - find N'th set bit in a word
 253  * @word: The word to search
 254  * @n: Bit to find
 255  */
 256 static inline unsigned int fns(unsigned long word, unsigned int n)
 257 {
 258         while (word && n--)
 259                 word &= word - 1;
 260
 261         return word ? __ffs(word) : BITS_PER_LONG;
 262 }
 263
 264 /**
 265  * assign_bit - Assign value to a bit in memory
 266  * @nr: the bit to set
 267  * @addr: the address to start counting from
 268  * @value: the value to assign
 269  */
 270 #define assign_bit(nr, addr, value)                                     \
 271         ((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr)))
 272
 273 #define __assign_bit(nr, addr, value)                                   \
 274         ((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr)))
 275
 276 /**
 277  * __ptr_set_bit - Set bit in a pointer's value
 278  * @nr: the bit to set
 279  * @addr: the address of the pointer variable
 280  *
 281  * Example:
 282  *      void *p = foo();
 283  *      __ptr_set_bit(bit, &p);
 284  */
 285 #define __ptr_set_bit(nr, addr)                         \
 286         ({                                              \
 287                 typecheck_pointer(*(addr));             \
 288                 __set_bit(nr, (unsigned long *)(addr)); \
 289         })
 290
 291 /**
 292  * __ptr_clear_bit - Clear bit in a pointer's value
 293  * @nr: the bit to clear
 294  * @addr: the address of the pointer variable
 295  *
 296  * Example:
 297  *      void *p = foo();
 298  *      __ptr_clear_bit(bit, &p);
 299  */
 300 #define __ptr_clear_bit(nr, addr)                         \
 301         ({                                                \
 302                 typecheck_pointer(*(addr));               \
 303                 __clear_bit(nr, (unsigned long *)(addr)); \
 304         })
 305
 306 /**
 307  * __ptr_test_bit - Test bit in a pointer's value
 308  * @nr: the bit to test
 309  * @addr: the address of the pointer variable
 310  *
 311  * Example:
 312  *      void *p = foo();
 313  *      if (__ptr_test_bit(bit, &p)) {
 314  *              ...
 315  *      } else {
 316  *              ...
 317  *      }
 318  */
 319 #define __ptr_test_bit(nr, addr)                       \
 320         ({                                             \
 321                 typecheck_pointer(*(addr));            \
 322                 test_bit(nr, (unsigned long *)(addr)); \
 323         })
 324
 325 #ifdef __KERNEL__
 326
 327 #ifndef set_mask_bits
 328 #define set_mask_bits(ptr, mask, bits)  \
 329 ({                                                              \
 330         const typeof(*(ptr)) mask__ = (mask), bits__ = (bits);  \
 331         typeof(*(ptr)) old__, new__;                            \
 332                                                                 \
 333         old__ = READ_ONCE(*(ptr));                              \
 334         do {                                                    \
 335                 new__ = (old__ & ~mask__) | bits__;             \
 336         } while (!try_cmpxchg(ptr, &old__, new__));             \
 337                                                                 \
 338         old__;                                                  \
 339 })
 340 #endif
 341
 342 #ifndef bit_clear_unless
 343 #define bit_clear_unless(ptr, clear, test)      \
 344 ({                                                              \
 345         const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
 346         typeof(*(ptr)) old__, new__;                            \
 347                                                                 \
 348         old__ = READ_ONCE(*(ptr));                              \
 349         do {                                                    \
 350                 if (old__ & test__)                             \
 351                         break;                                  \
 352                 new__ = old__ & ~clear__;                       \
 353         } while (!try_cmpxchg(ptr, &old__, new__));             \
 354                                                                 \
 355         !(old__ & test__);                                      \
 356 })
 357 #endif
 358
 359 #endif /* __KERNEL__ */
 360 #endif