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