diff options
Diffstat (limited to 'arch/x86/include/asm/bitops.h')
| -rw-r--r-- | arch/x86/include/asm/bitops.h | 172 |
1 files changed, 107 insertions, 65 deletions
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 903683b07e4..afcd35d331d 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -14,6 +14,18 @@ #include <linux/compiler.h> #include <asm/alternative.h> +#include <asm/rmwcc.h> +#include <asm/barrier.h> + +#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 @@ -57,7 +69,7 @@ * restricted to acting on a single-word quantity. */ static __always_inline void -set_bit(unsigned int nr, volatile unsigned long *addr) +set_bit(long nr, volatile unsigned long *addr) { if (IS_IMMEDIATE(nr)) { asm volatile(LOCK_PREFIX "orb %1,%0" @@ -79,7 +91,7 @@ set_bit(unsigned int nr, volatile unsigned long *addr) * 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(int nr, volatile unsigned long *addr) +static inline void __set_bit(long nr, volatile unsigned long *addr) { asm volatile("bts %1,%0" : ADDR : "Ir" (nr) : "memory"); } @@ -91,11 +103,11 @@ static inline void __set_bit(int nr, volatile unsigned long *addr) * * 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() + * 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(int nr, volatile unsigned long *addr) +clear_bit(long nr, volatile unsigned long *addr) { if (IS_IMMEDIATE(nr)) { asm volatile(LOCK_PREFIX "andb %1,%0" @@ -116,13 +128,13 @@ clear_bit(int nr, volatile unsigned long *addr) * 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(unsigned nr, volatile unsigned long *addr) +static inline void clear_bit_unlock(long nr, volatile unsigned long *addr) { barrier(); clear_bit(nr, addr); } -static inline void __clear_bit(int nr, volatile unsigned long *addr) +static inline void __clear_bit(long nr, volatile unsigned long *addr) { asm volatile("btr %1,%0" : ADDR : "Ir" (nr)); } @@ -139,15 +151,12 @@ static inline void __clear_bit(int nr, volatile unsigned long *addr) * 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(unsigned nr, volatile unsigned long *addr) +static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr) { barrier(); __clear_bit(nr, 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 @@ -157,7 +166,7 @@ static inline void __clear_bit_unlock(unsigned nr, volatile unsigned long *addr) * 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(int nr, volatile unsigned long *addr) +static inline void __change_bit(long nr, volatile unsigned long *addr) { asm volatile("btc %1,%0" : ADDR : "Ir" (nr)); } @@ -171,7 +180,7 @@ static inline void __change_bit(int nr, volatile unsigned long *addr) * 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(int nr, volatile unsigned long *addr) +static inline void change_bit(long nr, volatile unsigned long *addr) { if (IS_IMMEDIATE(nr)) { asm volatile(LOCK_PREFIX "xorb %1,%0" @@ -192,14 +201,9 @@ static inline void change_bit(int nr, volatile unsigned long *addr) * This operation is atomic and cannot be reordered. * It also implies a memory barrier. */ -static inline int test_and_set_bit(int nr, volatile unsigned long *addr) +static inline int test_and_set_bit(long nr, volatile unsigned long *addr) { - int oldbit; - - asm volatile(LOCK_PREFIX "bts %2,%1\n\t" - "sbb %0,%0" : "=r" (oldbit), ADDR : "Ir" (nr) : "memory"); - - return oldbit; + GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", "c"); } /** @@ -210,7 +214,7 @@ static inline int test_and_set_bit(int nr, volatile unsigned long *addr) * This is the same as test_and_set_bit on x86. */ static __always_inline int -test_and_set_bit_lock(int nr, volatile unsigned long *addr) +test_and_set_bit_lock(long nr, volatile unsigned long *addr) { return test_and_set_bit(nr, addr); } @@ -224,7 +228,7 @@ test_and_set_bit_lock(int nr, volatile unsigned long *addr) * 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(int nr, volatile unsigned long *addr) +static inline int __test_and_set_bit(long nr, volatile unsigned long *addr) { int oldbit; @@ -243,15 +247,9 @@ static inline int __test_and_set_bit(int nr, volatile unsigned long *addr) * This operation is atomic and cannot be reordered. * It also implies a memory barrier. */ -static inline int test_and_clear_bit(int nr, volatile unsigned long *addr) +static inline int test_and_clear_bit(long nr, volatile unsigned long *addr) { - int oldbit; - - asm volatile(LOCK_PREFIX "btr %2,%1\n\t" - "sbb %0,%0" - : "=r" (oldbit), ADDR : "Ir" (nr) : "memory"); - - return oldbit; + GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", "c"); } /** @@ -262,8 +260,15 @@ static inline int test_and_clear_bit(int nr, volatile unsigned long *addr) * 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(int nr, volatile unsigned long *addr) +static inline int __test_and_clear_bit(long nr, volatile unsigned long *addr) { int oldbit; @@ -275,7 +280,7 @@ static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr) } /* WARNING: non atomic and it can be reordered! */ -static inline int __test_and_change_bit(int nr, volatile unsigned long *addr) +static inline int __test_and_change_bit(long nr, volatile unsigned long *addr) { int oldbit; @@ -295,24 +300,18 @@ static inline int __test_and_change_bit(int nr, volatile unsigned long *addr) * This operation is atomic and cannot be reordered. * It also implies a memory barrier. */ -static inline int test_and_change_bit(int nr, volatile unsigned long *addr) +static inline int test_and_change_bit(long nr, volatile unsigned long *addr) { - int oldbit; - - asm volatile(LOCK_PREFIX "btc %2,%1\n\t" - "sbb %0,%0" - : "=r" (oldbit), ADDR : "Ir" (nr) : "memory"); - - return oldbit; + GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", "c"); } -static __always_inline int constant_test_bit(unsigned int nr, const volatile unsigned long *addr) +static __always_inline int constant_test_bit(long nr, const volatile unsigned long *addr) { - return ((1UL << (nr % BITS_PER_LONG)) & - (addr[nr / BITS_PER_LONG])) != 0; + return ((1UL << (nr & (BITS_PER_LONG-1))) & + (addr[nr >> _BITOPS_LONG_SHIFT])) != 0; } -static inline int variable_test_bit(int nr, volatile const unsigned long *addr) +static inline int variable_test_bit(long nr, volatile const unsigned long *addr) { int oldbit; @@ -346,7 +345,7 @@ static int test_bit(int nr, const volatile unsigned long *addr); */ static inline unsigned long __ffs(unsigned long word) { - asm("bsf %1,%0" + asm("rep; bsf %1,%0" : "=r" (word) : "rm" (word)); return word; @@ -360,7 +359,7 @@ static inline unsigned long __ffs(unsigned long word) */ static inline unsigned long ffz(unsigned long word) { - asm("bsf %1,%0" + asm("rep; bsf %1,%0" : "=r" (word) : "r" (~word)); return word; @@ -380,6 +379,8 @@ static inline unsigned long __fls(unsigned long word) return word; } +#undef ADDR + #ifdef __KERNEL__ /** * ffs - find first set bit in word @@ -395,10 +396,24 @@ static inline unsigned long __fls(unsigned long word) static inline int ffs(int x) { int r; -#ifdef CONFIG_X86_CMOV + +#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)); + : "=&r" (r) : "rm" (x), "r" (-1)); #else asm("bsfl %1,%0\n\t" "jnz 1f\n\t" @@ -422,7 +437,21 @@ static inline int ffs(int x) static inline int fls(int x) { int r; -#ifdef CONFIG_X86_CMOV + +#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)); @@ -434,11 +463,35 @@ static inline int fls(int x) #endif return r + 1; } -#endif /* __KERNEL__ */ - -#undef ADDR -#ifdef __KERNEL__ +/** + * 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 <asm-generic/bitops/fls64.h> +#endif #include <asm-generic/bitops/find.h> @@ -450,20 +503,9 @@ static inline int fls(int x) #include <asm-generic/bitops/const_hweight.h> -#endif /* __KERNEL__ */ - -#include <asm-generic/bitops/fls64.h> - -#ifdef __KERNEL__ - -#include <asm-generic/bitops/ext2-non-atomic.h> - -#define ext2_set_bit_atomic(lock, nr, addr) \ - test_and_set_bit((nr), (unsigned long *)(addr)) -#define ext2_clear_bit_atomic(lock, nr, addr) \ - test_and_clear_bit((nr), (unsigned long *)(addr)) +#include <asm-generic/bitops/le.h> -#include <asm-generic/bitops/minix.h> +#include <asm-generic/bitops/ext2-atomic-setbit.h> #endif /* __KERNEL__ */ #endif /* _ASM_X86_BITOPS_H */ |