From 77ec8d509468a3495e5ab1b1d44a627285b8ad1b Mon Sep 17 00:00:00 2001 From: Robert Mustacchi Date: Mon, 6 Jun 2011 10:42:07 -0700 Subject: HVM-296 bitops.h shouldn't have code in it HVM-297 Clean up bitops.h --- kvm_bitops.h | 264 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 264 insertions(+) create mode 100644 kvm_bitops.h (limited to 'kvm_bitops.h') diff --git a/kvm_bitops.h b/kvm_bitops.h new file mode 100644 index 0000000..bd3435e --- /dev/null +++ b/kvm_bitops.h @@ -0,0 +1,264 @@ +#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. + */ + +#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) +#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, 8 * sizeof(long)) + +/* + * 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 + +/* + * 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((uintptr_t)(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. + */ +inline void set_bit(unsigned int nr, volatile unsigned long *addr); + +/** + * __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. + */ +inline void __set_bit(int nr, volatile unsigned long *addr); + +/** + * 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_clear_bit() and/or smp_mb__after_clear_bit() + * in order to ensure changes are visible on other processors. + */ +inline void clear_bit(int nr, volatile unsigned long *addr); + +/* + * 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. + */ +inline void clear_bit_unlock(unsigned nr, volatile unsigned long *addr); + +inline void __clear_bit(int nr, volatile unsigned long *addr); + +/* + * __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. + */ +inline void __clear_bit_unlock(unsigned nr, volatile unsigned long *addr); + +#define smp_mb__before_clear_bit() barrier() +#define smp_mb__after_clear_bit() barrier() + +/** + * __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. + */ +inline void __change_bit(int nr, volatile unsigned long *addr); + +/** + * 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. + */ +inline void change_bit(int nr, volatile unsigned long *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 atomic and cannot be reordered. + * It also implies a memory barrier. + */ +inline int test_and_set_bit(int nr, volatile unsigned long *addr); + +/** + * 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. + */ +inline int test_and_set_bit_lock(int nr, volatile unsigned long *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. + */ +inline int __test_and_set_bit(int nr, volatile unsigned long *addr); + +/** + * 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. + */ +inline int test_and_clear_bit(int nr, volatile unsigned long *addr); + +/** + * __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. + */ +inline int __test_and_clear_bit(int nr, volatile unsigned long *addr); + +/* WARNING: non atomic and it can be reordered! */ +inline int __test_and_change_bit(int nr, volatile unsigned long *addr); + +/** + * 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. + */ +inline int test_and_change_bit(int nr, volatile unsigned long *addr); + +inline int constant_test_bit(unsigned int nr, const volatile unsigned long *addr); + +inline int variable_test_bit(int nr, volatile const unsigned long *addr); + +#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 + */ +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. + */ +inline unsigned long __ffs(unsigned long 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. + */ +inline unsigned long ffz(unsigned long 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. + */ +inline unsigned long __fls(unsigned long word); + +#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. + */ +inline int ffs(int x); + +/** + * 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. + */ +inline int fls(int x); + +#endif /* __KERNEL__ */ + +#endif /* _ASM_X86_BITOPS_H */ -- cgit v1.2.3