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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
commit | 76cb841cb886eef6b3bee341a2266c76578724ad (patch) | |
tree | f5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /arch/x86/include/asm/bitops.h | |
parent | Initial commit. (diff) | |
download | linux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip |
Adding upstream version 4.19.249.upstream/4.19.249
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/include/asm/bitops.h')
-rw-r--r-- | arch/x86/include/asm/bitops.h | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h new file mode 100644 index 000000000..33611a74b --- /dev/null +++ b/arch/x86/include/asm/bitops.h @@ -0,0 +1,515 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#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 <linux/bitops.h> can be included directly +#endif + +#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 + * 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). + */ + +#define RLONG_ADDR(x) "m" (*(volatile long *) (x)) +#define WBYTE_ADDR(x) "+m" (*(volatile char *) (x)) + +#define ADDR RLONG_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) WBYTE_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 __ASM_SIZE(bts) " %1,%0" + : : RLONG_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 __always_inline void __set_bit(long nr, volatile unsigned long *addr) +{ + asm volatile(__ASM_SIZE(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 __ASM_SIZE(btr) " %1,%0" + : : RLONG_ADDR(addr), "Ir" (nr) : "memory"); + } +} + +/* + * 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 __always_inline void clear_bit_unlock(long nr, volatile unsigned long *addr) +{ + barrier(); + clear_bit(nr, addr); +} + +static __always_inline void __clear_bit(long nr, volatile unsigned long *addr) +{ + asm volatile(__ASM_SIZE(btr) " %1,%0" : : ADDR, "Ir" (nr) : "memory"); +} + +static __always_inline bool clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr) +{ + bool negative; + asm volatile(LOCK_PREFIX "andb %2,%1" + CC_SET(s) + : CC_OUT(s) (negative), WBYTE_ADDR(addr) + : "ir" ((char) ~(1 << nr)) : "memory"); + return negative; +} + +// Let everybody know we have it +#define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte + +/* + * __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. + */ +static __always_inline void __clear_bit_unlock(long nr, volatile unsigned long *addr) +{ + __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 __always_inline void __change_bit(long nr, volatile unsigned long *addr) +{ + asm volatile(__ASM_SIZE(btc) " %1,%0" : : ADDR, "Ir" (nr) : "memory"); +} + +/** + * 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 __always_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 __ASM_SIZE(btc) " %1,%0" + : : RLONG_ADDR(addr), "Ir" (nr) : "memory"); + } +} + +/** + * 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 __always_inline bool test_and_set_bit(long nr, volatile unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(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 bool +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 __always_inline bool __test_and_set_bit(long nr, volatile unsigned long *addr) +{ + bool oldbit; + + asm(__ASM_SIZE(bts) " %2,%1" + CC_SET(c) + : CC_OUT(c) (oldbit) + : ADDR, "Ir" (nr) : "memory"); + 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 __always_inline bool test_and_clear_bit(long nr, volatile unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(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 __always_inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr) +{ + bool oldbit; + + asm volatile(__ASM_SIZE(btr) " %2,%1" + CC_SET(c) + : CC_OUT(c) (oldbit) + : ADDR, "Ir" (nr) : "memory"); + return oldbit; +} + +/* WARNING: non atomic and it can be reordered! */ +static __always_inline bool __test_and_change_bit(long nr, volatile unsigned long *addr) +{ + bool oldbit; + + asm volatile(__ASM_SIZE(btc) " %2,%1" + CC_SET(c) + : CC_OUT(c) (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 __always_inline bool test_and_change_bit(long nr, volatile unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(btc), + *addr, "Ir", nr, "%0", c); +} + +static __always_inline bool constant_test_bit(long nr, const volatile unsigned long *addr) +{ + return ((1UL << (nr & (BITS_PER_LONG-1))) & + (addr[nr >> _BITOPS_LONG_SHIFT])) != 0; +} + +static __always_inline bool variable_test_bit(long nr, volatile const unsigned long *addr) +{ + bool oldbit; + + asm volatile(__ASM_SIZE(bt) " %2,%1" + CC_SET(c) + : CC_OUT(c) (oldbit) + : "m" (*(unsigned long *)addr), "Ir" (nr) : "memory"); + + 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 bool 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 __always_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 __always_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 __always_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 __always_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 __always_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 <asm-generic/bitops/fls64.h> +#endif + +#include <asm-generic/bitops/find.h> + +#include <asm-generic/bitops/sched.h> + +#include <asm/arch_hweight.h> + +#include <asm-generic/bitops/const_hweight.h> + +#include <asm-generic/bitops/le.h> + +#include <asm-generic/bitops/ext2-atomic-setbit.h> + +#endif /* __KERNEL__ */ +#endif /* _ASM_X86_BITOPS_H */ |