From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/x86/include/asm/bitops.h | 509 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 509 insertions(+) create mode 100644 arch/x86/include/asm/bitops.h (limited to 'arch/x86/include/asm/bitops.h') diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h new file mode 100644 index 000000000..cfe3b954d --- /dev/null +++ b/arch/x86/include/asm/bitops.h @@ -0,0 +1,509 @@ +#ifndef _ASM_X86_BITOPS_H +#define _ASM_X86_BITOPS_H + +/* + * Copyright 1992, Linus Torvalds. + * + * Note: inlines with more than a single statement should be marked + * __always_inline to avoid problems with older gcc's inlining heuristics. + */ + +#ifndef _LINUX_BITOPS_H +#error only can be included directly +#endif + +#include +#include +#include +#include + +#if BITS_PER_LONG == 32 +# define _BITOPS_LONG_SHIFT 5 +#elif BITS_PER_LONG == 64 +# define _BITOPS_LONG_SHIFT 6 +#else +# error "Unexpected BITS_PER_LONG" +#endif + +#define BIT_64(n) (U64_C(1) << (n)) + +/* + * These have to be done with inline assembly: that way the bit-setting + * is guaranteed to be atomic. All bit operations return 0 if the bit + * was cleared before the operation and != 0 if it was not. + * + * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1). + */ + +#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1) +/* Technically wrong, but this avoids compilation errors on some gcc + versions. */ +#define BITOP_ADDR(x) "=m" (*(volatile long *) (x)) +#else +#define BITOP_ADDR(x) "+m" (*(volatile long *) (x)) +#endif + +#define ADDR BITOP_ADDR(addr) + +/* + * We do the locked ops that don't return the old value as + * a mask operation on a byte. + */ +#define IS_IMMEDIATE(nr) (__builtin_constant_p(nr)) +#define CONST_MASK_ADDR(nr, addr) BITOP_ADDR((void *)(addr) + ((nr)>>3)) +#define CONST_MASK(nr) (1 << ((nr) & 7)) + +/** + * set_bit - Atomically set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * This function is atomic and may not be reordered. See __set_bit() + * if you do not require the atomic guarantees. + * + * Note: there are no guarantees that this function will not be reordered + * on non x86 architectures, so if you are writing portable code, + * make sure not to rely on its reordering guarantees. + * + * Note that @nr may be almost arbitrarily large; this function is not + * restricted to acting on a single-word quantity. + */ +static __always_inline void +set_bit(long nr, volatile unsigned long *addr) +{ + if (IS_IMMEDIATE(nr)) { + asm volatile(LOCK_PREFIX "orb %1,%0" + : CONST_MASK_ADDR(nr, addr) + : "iq" ((u8)CONST_MASK(nr)) + : "memory"); + } else { + asm volatile(LOCK_PREFIX "bts %1,%0" + : BITOP_ADDR(addr) : "Ir" (nr) : "memory"); + } +} + +/** + * __set_bit - Set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * Unlike set_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static inline void __set_bit(long nr, volatile unsigned long *addr) +{ + asm volatile("bts %1,%0" : ADDR : "Ir" (nr) : "memory"); +} + +/** + * clear_bit - Clears a bit in memory + * @nr: Bit to clear + * @addr: Address to start counting from + * + * clear_bit() is atomic and may not be reordered. However, it does + * not contain a memory barrier, so if it is used for locking purposes, + * you should call smp_mb__before_atomic() and/or smp_mb__after_atomic() + * in order to ensure changes are visible on other processors. + */ +static __always_inline void +clear_bit(long nr, volatile unsigned long *addr) +{ + if (IS_IMMEDIATE(nr)) { + asm volatile(LOCK_PREFIX "andb %1,%0" + : CONST_MASK_ADDR(nr, addr) + : "iq" ((u8)~CONST_MASK(nr))); + } else { + asm volatile(LOCK_PREFIX "btr %1,%0" + : BITOP_ADDR(addr) + : "Ir" (nr)); + } +} + +/* + * clear_bit_unlock - Clears a bit in memory + * @nr: Bit to clear + * @addr: Address to start counting from + * + * clear_bit() is atomic and implies release semantics before the memory + * operation. It can be used for an unlock. + */ +static inline void clear_bit_unlock(long nr, volatile unsigned long *addr) +{ + barrier(); + clear_bit(nr, addr); +} + +static inline void __clear_bit(long nr, volatile unsigned long *addr) +{ + asm volatile("btr %1,%0" : ADDR : "Ir" (nr)); +} + +/* + * __clear_bit_unlock - Clears a bit in memory + * @nr: Bit to clear + * @addr: Address to start counting from + * + * __clear_bit() is non-atomic and implies release semantics before the memory + * operation. It can be used for an unlock if no other CPUs can concurrently + * modify other bits in the word. + * + * No memory barrier is required here, because x86 cannot reorder stores past + * older loads. Same principle as spin_unlock. + */ +static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr) +{ + barrier(); + __clear_bit(nr, addr); +} + +/** + * __change_bit - Toggle a bit in memory + * @nr: the bit to change + * @addr: the address to start counting from + * + * Unlike change_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static inline void __change_bit(long nr, volatile unsigned long *addr) +{ + asm volatile("btc %1,%0" : ADDR : "Ir" (nr)); +} + +/** + * change_bit - Toggle a bit in memory + * @nr: Bit to change + * @addr: Address to start counting from + * + * change_bit() is atomic and may not be reordered. + * Note that @nr may be almost arbitrarily large; this function is not + * restricted to acting on a single-word quantity. + */ +static inline void change_bit(long nr, volatile unsigned long *addr) +{ + if (IS_IMMEDIATE(nr)) { + asm volatile(LOCK_PREFIX "xorb %1,%0" + : CONST_MASK_ADDR(nr, addr) + : "iq" ((u8)CONST_MASK(nr))); + } else { + asm volatile(LOCK_PREFIX "btc %1,%0" + : BITOP_ADDR(addr) + : "Ir" (nr)); + } +} + +/** + * test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static inline int test_and_set_bit(long nr, volatile unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", "c"); +} + +/** + * test_and_set_bit_lock - Set a bit and return its old value for lock + * @nr: Bit to set + * @addr: Address to count from + * + * This is the same as test_and_set_bit on x86. + */ +static __always_inline int +test_and_set_bit_lock(long nr, volatile unsigned long *addr) +{ + return test_and_set_bit(nr, addr); +} + +/** + * __test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static inline int __test_and_set_bit(long nr, volatile unsigned long *addr) +{ + int oldbit; + + asm("bts %2,%1\n\t" + "sbb %0,%0" + : "=r" (oldbit), ADDR + : "Ir" (nr)); + return oldbit; +} + +/** + * test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static inline int test_and_clear_bit(long nr, volatile unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", "c"); +} + +/** + * __test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + * + * Note: the operation is performed atomically with respect to + * the local CPU, but not other CPUs. Portable code should not + * rely on this behaviour. + * KVM relies on this behaviour on x86 for modifying memory that is also + * accessed from a hypervisor on the same CPU if running in a VM: don't change + * this without also updating arch/x86/kernel/kvm.c + */ +static inline int __test_and_clear_bit(long nr, volatile unsigned long *addr) +{ + int oldbit; + + asm volatile("btr %2,%1\n\t" + "sbb %0,%0" + : "=r" (oldbit), ADDR + : "Ir" (nr)); + return oldbit; +} + +/* WARNING: non atomic and it can be reordered! */ +static inline int __test_and_change_bit(long nr, volatile unsigned long *addr) +{ + int oldbit; + + asm volatile("btc %2,%1\n\t" + "sbb %0,%0" + : "=r" (oldbit), ADDR + : "Ir" (nr) : "memory"); + + return oldbit; +} + +/** + * test_and_change_bit - Change a bit and return its old value + * @nr: Bit to change + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static inline int test_and_change_bit(long nr, volatile unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", "c"); +} + +static __always_inline int constant_test_bit(long nr, const volatile unsigned long *addr) +{ + return ((1UL << (nr & (BITS_PER_LONG-1))) & + (addr[nr >> _BITOPS_LONG_SHIFT])) != 0; +} + +static inline int variable_test_bit(long nr, volatile const unsigned long *addr) +{ + int oldbit; + + asm volatile("bt %2,%1\n\t" + "sbb %0,%0" + : "=r" (oldbit) + : "m" (*(unsigned long *)addr), "Ir" (nr)); + + return oldbit; +} + +#if 0 /* Fool kernel-doc since it doesn't do macros yet */ +/** + * test_bit - Determine whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + */ +static int test_bit(int nr, const volatile unsigned long *addr); +#endif + +#define test_bit(nr, addr) \ + (__builtin_constant_p((nr)) \ + ? constant_test_bit((nr), (addr)) \ + : variable_test_bit((nr), (addr))) + +/** + * __ffs - find first set bit in word + * @word: The word to search + * + * Undefined if no bit exists, so code should check against 0 first. + */ +static inline unsigned long __ffs(unsigned long word) +{ + asm("rep; bsf %1,%0" + : "=r" (word) + : "rm" (word)); + return word; +} + +/** + * ffz - find first zero bit in word + * @word: The word to search + * + * Undefined if no zero exists, so code should check against ~0UL first. + */ +static inline unsigned long ffz(unsigned long word) +{ + asm("rep; bsf %1,%0" + : "=r" (word) + : "r" (~word)); + return word; +} + +/* + * __fls: find last set bit in word + * @word: The word to search + * + * Undefined if no set bit exists, so code should check against 0 first. + */ +static inline unsigned long __fls(unsigned long word) +{ + asm("bsr %1,%0" + : "=r" (word) + : "rm" (word)); + return word; +} + +#undef ADDR + +#ifdef __KERNEL__ +/** + * ffs - find first set bit in word + * @x: the word to search + * + * This is defined the same way as the libc and compiler builtin ffs + * routines, therefore differs in spirit from the other bitops. + * + * ffs(value) returns 0 if value is 0 or the position of the first + * set bit if value is nonzero. The first (least significant) bit + * is at position 1. + */ +static inline int ffs(int x) +{ + int r; + +#ifdef CONFIG_X86_64 + /* + * AMD64 says BSFL won't clobber the dest reg if x==0; Intel64 says the + * dest reg is undefined if x==0, but their CPU architect says its + * value is written to set it to the same as before, except that the + * top 32 bits will be cleared. + * + * We cannot do this on 32 bits because at the very least some + * 486 CPUs did not behave this way. + */ + asm("bsfl %1,%0" + : "=r" (r) + : "rm" (x), "0" (-1)); +#elif defined(CONFIG_X86_CMOV) + asm("bsfl %1,%0\n\t" + "cmovzl %2,%0" + : "=&r" (r) : "rm" (x), "r" (-1)); +#else + asm("bsfl %1,%0\n\t" + "jnz 1f\n\t" + "movl $-1,%0\n" + "1:" : "=r" (r) : "rm" (x)); +#endif + return r + 1; +} + +/** + * fls - find last set bit in word + * @x: the word to search + * + * This is defined in a similar way as the libc and compiler builtin + * ffs, but returns the position of the most significant set bit. + * + * fls(value) returns 0 if value is 0 or the position of the last + * set bit if value is nonzero. The last (most significant) bit is + * at position 32. + */ +static inline int fls(int x) +{ + int r; + +#ifdef CONFIG_X86_64 + /* + * AMD64 says BSRL won't clobber the dest reg if x==0; Intel64 says the + * dest reg is undefined if x==0, but their CPU architect says its + * value is written to set it to the same as before, except that the + * top 32 bits will be cleared. + * + * We cannot do this on 32 bits because at the very least some + * 486 CPUs did not behave this way. + */ + asm("bsrl %1,%0" + : "=r" (r) + : "rm" (x), "0" (-1)); +#elif defined(CONFIG_X86_CMOV) + asm("bsrl %1,%0\n\t" + "cmovzl %2,%0" + : "=&r" (r) : "rm" (x), "rm" (-1)); +#else + asm("bsrl %1,%0\n\t" + "jnz 1f\n\t" + "movl $-1,%0\n" + "1:" : "=r" (r) : "rm" (x)); +#endif + return r + 1; +} + +/** + * fls64 - find last set bit in a 64-bit word + * @x: the word to search + * + * This is defined in a similar way as the libc and compiler builtin + * ffsll, but returns the position of the most significant set bit. + * + * fls64(value) returns 0 if value is 0 or the position of the last + * set bit if value is nonzero. The last (most significant) bit is + * at position 64. + */ +#ifdef CONFIG_X86_64 +static __always_inline int fls64(__u64 x) +{ + int bitpos = -1; + /* + * AMD64 says BSRQ won't clobber the dest reg if x==0; Intel64 says the + * dest reg is undefined if x==0, but their CPU architect says its + * value is written to set it to the same as before. + */ + asm("bsrq %1,%q0" + : "+r" (bitpos) + : "rm" (x)); + return bitpos + 1; +} +#else +#include +#endif + +#include + +#include + +#include + +#include + +#include + +#include + +#endif /* __KERNEL__ */ +#endif /* _ASM_X86_BITOPS_H */ -- cgit v1.2.3-54-g00ecf