linux/arch/x86/include/asm/bitops.h
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   1#ifndef _ASM_X86_BITOPS_H
   2#define _ASM_X86_BITOPS_H
   3
   4/*
   5 * Copyright 1992, Linus Torvalds.
   6 */
   7
   8#ifndef _LINUX_BITOPS_H
   9#error only <linux/bitops.h> can be included directly
  10#endif
  11
  12#include <linux/compiler.h>
  13#include <asm/alternative.h>
  14
  15/*
  16 * These have to be done with inline assembly: that way the bit-setting
  17 * is guaranteed to be atomic. All bit operations return 0 if the bit
  18 * was cleared before the operation and != 0 if it was not.
  19 *
  20 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
  21 */
  22
  23#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1)
  24/* Technically wrong, but this avoids compilation errors on some gcc
  25   versions. */
  26#define BITOP_ADDR(x) "=m" (*(volatile long *) (x))
  27#else
  28#define BITOP_ADDR(x) "+m" (*(volatile long *) (x))
  29#endif
  30
  31#define ADDR                            BITOP_ADDR(addr)
  32
  33/*
  34 * We do the locked ops that don't return the old value as
  35 * a mask operation on a byte.
  36 */
  37#define IS_IMMEDIATE(nr)                (__builtin_constant_p(nr))
  38#define CONST_MASK_ADDR(nr, addr)       BITOP_ADDR((void *)(addr) + ((nr)>>3))
  39#define CONST_MASK(nr)                  (1 << ((nr) & 7))
  40
  41/**
  42 * set_bit - Atomically set a bit in memory
  43 * @nr: the bit to set
  44 * @addr: the address to start counting from
  45 *
  46 * This function is atomic and may not be reordered.  See __set_bit()
  47 * if you do not require the atomic guarantees.
  48 *
  49 * Note: there are no guarantees that this function will not be reordered
  50 * on non x86 architectures, so if you are writing portable code,
  51 * make sure not to rely on its reordering guarantees.
  52 *
  53 * Note that @nr may be almost arbitrarily large; this function is not
  54 * restricted to acting on a single-word quantity.
  55 */
  56static inline void set_bit(unsigned int nr, volatile unsigned long *addr)
  57{
  58        if (IS_IMMEDIATE(nr)) {
  59                asm volatile(LOCK_PREFIX "orb %1,%0"
  60                        : CONST_MASK_ADDR(nr, addr)
  61                        : "iq" ((u8)CONST_MASK(nr))
  62                        : "memory");
  63        } else {
  64                asm volatile(LOCK_PREFIX "bts %1,%0"
  65                        : BITOP_ADDR(addr) : "Ir" (nr) : "memory");
  66        }
  67}
  68
  69/**
  70 * __set_bit - Set a bit in memory
  71 * @nr: the bit to set
  72 * @addr: the address to start counting from
  73 *
  74 * Unlike set_bit(), this function is non-atomic and may be reordered.
  75 * If it's called on the same region of memory simultaneously, the effect
  76 * may be that only one operation succeeds.
  77 */
  78static inline void __set_bit(int nr, volatile unsigned long *addr)
  79{
  80        asm volatile("bts %1,%0" : ADDR : "Ir" (nr) : "memory");
  81}
  82
  83/**
  84 * clear_bit - Clears a bit in memory
  85 * @nr: Bit to clear
  86 * @addr: Address to start counting from
  87 *
  88 * clear_bit() is atomic and may not be reordered.  However, it does
  89 * not contain a memory barrier, so if it is used for locking purposes,
  90 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
  91 * in order to ensure changes are visible on other processors.
  92 */
  93static inline void clear_bit(int nr, volatile unsigned long *addr)
  94{
  95        if (IS_IMMEDIATE(nr)) {
  96                asm volatile(LOCK_PREFIX "andb %1,%0"
  97                        : CONST_MASK_ADDR(nr, addr)
  98                        : "iq" ((u8)~CONST_MASK(nr)));
  99        } else {
 100                asm volatile(LOCK_PREFIX "btr %1,%0"
 101                        : BITOP_ADDR(addr)
 102                        : "Ir" (nr));
 103        }
 104}
 105
 106/*
 107 * clear_bit_unlock - Clears a bit in memory
 108 * @nr: Bit to clear
 109 * @addr: Address to start counting from
 110 *
 111 * clear_bit() is atomic and implies release semantics before the memory
 112 * operation. It can be used for an unlock.
 113 */
 114static inline void clear_bit_unlock(unsigned nr, volatile unsigned long *addr)
 115{
 116        barrier();
 117        clear_bit(nr, addr);
 118}
 119
 120static inline void __clear_bit(int nr, volatile unsigned long *addr)
 121{
 122        asm volatile("btr %1,%0" : ADDR : "Ir" (nr));
 123}
 124
 125/*
 126 * __clear_bit_unlock - Clears a bit in memory
 127 * @nr: Bit to clear
 128 * @addr: Address to start counting from
 129 *
 130 * __clear_bit() is non-atomic and implies release semantics before the memory
 131 * operation. It can be used for an unlock if no other CPUs can concurrently
 132 * modify other bits in the word.
 133 *
 134 * No memory barrier is required here, because x86 cannot reorder stores past
 135 * older loads. Same principle as spin_unlock.
 136 */
 137static inline void __clear_bit_unlock(unsigned nr, volatile unsigned long *addr)
 138{
 139        barrier();
 140        __clear_bit(nr, addr);
 141}
 142
 143#define smp_mb__before_clear_bit()      barrier()
 144#define smp_mb__after_clear_bit()       barrier()
 145
 146/**
 147 * __change_bit - Toggle a bit in memory
 148 * @nr: the bit to change
 149 * @addr: the address to start counting from
 150 *
 151 * Unlike change_bit(), this function is non-atomic and may be reordered.
 152 * If it's called on the same region of memory simultaneously, the effect
 153 * may be that only one operation succeeds.
 154 */
 155static inline void __change_bit(int nr, volatile unsigned long *addr)
 156{
 157        asm volatile("btc %1,%0" : ADDR : "Ir" (nr));
 158}
 159
 160/**
 161 * change_bit - Toggle a bit in memory
 162 * @nr: Bit to change
 163 * @addr: Address to start counting from
 164 *
 165 * change_bit() is atomic and may not be reordered.
 166 * Note that @nr may be almost arbitrarily large; this function is not
 167 * restricted to acting on a single-word quantity.
 168 */
 169static inline void change_bit(int nr, volatile unsigned long *addr)
 170{
 171        asm volatile(LOCK_PREFIX "btc %1,%0" : ADDR : "Ir" (nr));
 172}
 173
 174/**
 175 * test_and_set_bit - Set a bit and return its old value
 176 * @nr: Bit to set
 177 * @addr: Address to count from
 178 *
 179 * This operation is atomic and cannot be reordered.
 180 * It also implies a memory barrier.
 181 */
 182static inline int test_and_set_bit(int nr, volatile unsigned long *addr)
 183{
 184        int oldbit;
 185
 186        asm volatile(LOCK_PREFIX "bts %2,%1\n\t"
 187                     "sbb %0,%0" : "=r" (oldbit), ADDR : "Ir" (nr) : "memory");
 188
 189        return oldbit;
 190}
 191
 192/**
 193 * test_and_set_bit_lock - Set a bit and return its old value for lock
 194 * @nr: Bit to set
 195 * @addr: Address to count from
 196 *
 197 * This is the same as test_and_set_bit on x86.
 198 */
 199static inline int test_and_set_bit_lock(int nr, volatile unsigned long *addr)
 200{
 201        return test_and_set_bit(nr, addr);
 202}
 203
 204/**
 205 * __test_and_set_bit - Set a bit and return its old value
 206 * @nr: Bit to set
 207 * @addr: Address to count from
 208 *
 209 * This operation is non-atomic and can be reordered.
 210 * If two examples of this operation race, one can appear to succeed
 211 * but actually fail.  You must protect multiple accesses with a lock.
 212 */
 213static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
 214{
 215        int oldbit;
 216
 217        asm("bts %2,%1\n\t"
 218            "sbb %0,%0"
 219            : "=r" (oldbit), ADDR
 220            : "Ir" (nr));
 221        return oldbit;
 222}
 223
 224/**
 225 * test_and_clear_bit - Clear a bit and return its old value
 226 * @nr: Bit to clear
 227 * @addr: Address to count from
 228 *
 229 * This operation is atomic and cannot be reordered.
 230 * It also implies a memory barrier.
 231 */
 232static inline int test_and_clear_bit(int nr, volatile unsigned long *addr)
 233{
 234        int oldbit;
 235
 236        asm volatile(LOCK_PREFIX "btr %2,%1\n\t"
 237                     "sbb %0,%0"
 238                     : "=r" (oldbit), ADDR : "Ir" (nr) : "memory");
 239
 240        return oldbit;
 241}
 242
 243/**
 244 * __test_and_clear_bit - Clear a bit and return its old value
 245 * @nr: Bit to clear
 246 * @addr: Address to count from
 247 *
 248 * This operation is non-atomic and can be reordered.
 249 * If two examples of this operation race, one can appear to succeed
 250 * but actually fail.  You must protect multiple accesses with a lock.
 251 */
 252static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
 253{
 254        int oldbit;
 255
 256        asm volatile("btr %2,%1\n\t"
 257                     "sbb %0,%0"
 258                     : "=r" (oldbit), ADDR
 259                     : "Ir" (nr));
 260        return oldbit;
 261}
 262
 263/* WARNING: non atomic and it can be reordered! */
 264static inline int __test_and_change_bit(int nr, volatile unsigned long *addr)
 265{
 266        int oldbit;
 267
 268        asm volatile("btc %2,%1\n\t"
 269                     "sbb %0,%0"
 270                     : "=r" (oldbit), ADDR
 271                     : "Ir" (nr) : "memory");
 272
 273        return oldbit;
 274}
 275
 276/**
 277 * test_and_change_bit - Change a bit and return its old value
 278 * @nr: Bit to change
 279 * @addr: Address to count from
 280 *
 281 * This operation is atomic and cannot be reordered.
 282 * It also implies a memory barrier.
 283 */
 284static inline int test_and_change_bit(int nr, volatile unsigned long *addr)
 285{
 286        int oldbit;
 287
 288        asm volatile(LOCK_PREFIX "btc %2,%1\n\t"
 289                     "sbb %0,%0"
 290                     : "=r" (oldbit), ADDR : "Ir" (nr) : "memory");
 291
 292        return oldbit;
 293}
 294
 295static inline int constant_test_bit(int nr, const volatile unsigned long *addr)
 296{
 297        return ((1UL << (nr % BITS_PER_LONG)) &
 298                (((unsigned long *)addr)[nr / BITS_PER_LONG])) != 0;
 299}
 300
 301static inline int variable_test_bit(int nr, volatile const unsigned long *addr)
 302{
 303        int oldbit;
 304
 305        asm volatile("bt %2,%1\n\t"
 306                     "sbb %0,%0"
 307                     : "=r" (oldbit)
 308                     : "m" (*(unsigned long *)addr), "Ir" (nr));
 309
 310        return oldbit;
 311}
 312
 313#if 0 /* Fool kernel-doc since it doesn't do macros yet */
 314/**
 315 * test_bit - Determine whether a bit is set
 316 * @nr: bit number to test
 317 * @addr: Address to start counting from
 318 */
 319static int test_bit(int nr, const volatile unsigned long *addr);
 320#endif
 321
 322#define test_bit(nr, addr)                      \
 323        (__builtin_constant_p((nr))             \
 324         ? constant_test_bit((nr), (addr))      \
 325         : variable_test_bit((nr), (addr)))
 326
 327/**
 328 * __ffs - find first set bit in word
 329 * @word: The word to search
 330 *
 331 * Undefined if no bit exists, so code should check against 0 first.
 332 */
 333static inline unsigned long __ffs(unsigned long word)
 334{
 335        asm("bsf %1,%0"
 336                : "=r" (word)
 337                : "rm" (word));
 338        return word;
 339}
 340
 341/**
 342 * ffz - find first zero bit in word
 343 * @word: The word to search
 344 *
 345 * Undefined if no zero exists, so code should check against ~0UL first.
 346 */
 347static inline unsigned long ffz(unsigned long word)
 348{
 349        asm("bsf %1,%0"
 350                : "=r" (word)
 351                : "r" (~word));
 352        return word;
 353}
 354
 355/*
 356 * __fls: find last set bit in word
 357 * @word: The word to search
 358 *
 359 * Undefined if no set bit exists, so code should check against 0 first.
 360 */
 361static inline unsigned long __fls(unsigned long word)
 362{
 363        asm("bsr %1,%0"
 364            : "=r" (word)
 365            : "rm" (word));
 366        return word;
 367}
 368
 369#ifdef __KERNEL__
 370/**
 371 * ffs - find first set bit in word
 372 * @x: the word to search
 373 *
 374 * This is defined the same way as the libc and compiler builtin ffs
 375 * routines, therefore differs in spirit from the other bitops.
 376 *
 377 * ffs(value) returns 0 if value is 0 or the position of the first
 378 * set bit if value is nonzero. The first (least significant) bit
 379 * is at position 1.
 380 */
 381static inline int ffs(int x)
 382{
 383        int r;
 384#ifdef CONFIG_X86_CMOV
 385        asm("bsfl %1,%0\n\t"
 386            "cmovzl %2,%0"
 387            : "=r" (r) : "rm" (x), "r" (-1));
 388#else
 389        asm("bsfl %1,%0\n\t"
 390            "jnz 1f\n\t"
 391            "movl $-1,%0\n"
 392            "1:" : "=r" (r) : "rm" (x));
 393#endif
 394        return r + 1;
 395}
 396
 397/**
 398 * fls - find last set bit in word
 399 * @x: the word to search
 400 *
 401 * This is defined in a similar way as the libc and compiler builtin
 402 * ffs, but returns the position of the most significant set bit.
 403 *
 404 * fls(value) returns 0 if value is 0 or the position of the last
 405 * set bit if value is nonzero. The last (most significant) bit is
 406 * at position 32.
 407 */
 408static inline int fls(int x)
 409{
 410        int r;
 411#ifdef CONFIG_X86_CMOV
 412        asm("bsrl %1,%0\n\t"
 413            "cmovzl %2,%0"
 414            : "=&r" (r) : "rm" (x), "rm" (-1));
 415#else
 416        asm("bsrl %1,%0\n\t"
 417            "jnz 1f\n\t"
 418            "movl $-1,%0\n"
 419            "1:" : "=r" (r) : "rm" (x));
 420#endif
 421        return r + 1;
 422}
 423#endif /* __KERNEL__ */
 424
 425#undef ADDR
 426
 427#ifdef __KERNEL__
 428
 429#include <asm-generic/bitops/sched.h>
 430
 431#define ARCH_HAS_FAST_MULTIPLIER 1
 432
 433#include <asm-generic/bitops/hweight.h>
 434
 435#endif /* __KERNEL__ */
 436
 437#include <asm-generic/bitops/fls64.h>
 438
 439#ifdef __KERNEL__
 440
 441#include <asm-generic/bitops/ext2-non-atomic.h>
 442
 443#define ext2_set_bit_atomic(lock, nr, addr)                     \
 444        test_and_set_bit((nr), (unsigned long *)(addr))
 445#define ext2_clear_bit_atomic(lock, nr, addr)                   \
 446        test_and_clear_bit((nr), (unsigned long *)(addr))
 447
 448#include <asm-generic/bitops/minix.h>
 449
 450#endif /* __KERNEL__ */
 451#endif /* _ASM_X86_BITOPS_H */
 452
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