/* SPDX-License-Identifier: GPL-2.0 */
#ifndef ASM_X86_CMPXCHG_H
#define ASM_X86_CMPXCHG_H

#include <linux/compiler.h>
#include <asm/cpufeatures.h>
#include <asm/alternative.h> /* Provides LOCK_PREFIX */

/*
 * Non-existent functions to indicate usage errors at link time
 * (or compile-time if the compiler implements __compiletime_error().
 */
extern void __xchg_wrong_size(void)
        __compiletime_error("Bad argument size for xchg");
extern void __cmpxchg_wrong_size(void)
        __compiletime_error("Bad argument size for cmpxchg");
extern void __xadd_wrong_size(void)
        __compiletime_error("Bad argument size for xadd");
extern void __add_wrong_size(void)
        __compiletime_error("Bad argument size for add");

/*
 * Constants for operation sizes. On 32-bit, the 64-bit size it set to
 * -1 because sizeof will never return -1, thereby making those switch
 * case statements guaranteed dead code which the compiler will
 * eliminate, and allowing the "missing symbol in the default case" to
 * indicate a usage error.
 */
#define __X86_CASE_B    1
#define __X86_CASE_W    2
#define __X86_CASE_L    4
#ifdef CONFIG_64BIT
#define __X86_CASE_Q    8
#else
#define __X86_CASE_Q    -1              /* sizeof will never return -1 */
#endif

/* 
 * An exchange-type operation, which takes a value and a pointer, and
 * returns the old value.
 */
#define __xchg_op(ptr, arg, op, lock)                                   \
        ({                                                              \
                __typeof__ (*(ptr)) __ret = (arg);                      \
                switch (sizeof(*(ptr))) {                               \
                case __X86_CASE_B:                                      \
                        asm_inline volatile (lock #op "b %b0, %1"       \
                                      : "+q" (__ret), "+m" (*(ptr))     \
                                      : : "memory", "cc");              \
                        break;                                          \
                case __X86_CASE_W:                                      \
                        asm_inline volatile (lock #op "w %w0, %1"       \
                                      : "+r" (__ret), "+m" (*(ptr))     \
                                      : : "memory", "cc");              \
                        break;                                          \
                case __X86_CASE_L:                                      \
                        asm_inline volatile (lock #op "l %0, %1"        \
                                      : "+r" (__ret), "+m" (*(ptr))     \
                                      : : "memory", "cc");              \
                        break;                                          \
                case __X86_CASE_Q:                                      \
                        asm_inline volatile (lock #op "q %q0, %1"       \
                                      : "+r" (__ret), "+m" (*(ptr))     \
                                      : : "memory", "cc");              \
                        break;                                          \
                default:                                                \
                        __ ## op ## _wrong_size();                      \
                }                                                       \
                __ret;                                                  \
        })

/*
 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway.
 * Since this is generally used to protect other memory information, we
 * use "asm volatile" and "memory" clobbers to prevent gcc from moving
 * information around.
 */
#define arch_xchg(ptr, v)       __xchg_op((ptr), (v), xchg, "")

/*
 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 * store NEW in MEM.  Return the initial value in MEM.  Success is
 * indicated by comparing RETURN with OLD.
 */
#define __raw_cmpxchg(ptr, old, new, size, lock)                        \
({                                                                      \
        __typeof__(*(ptr)) __ret;                                       \
        __typeof__(*(ptr)) __old = (old);                               \
        __typeof__(*(ptr)) __new = (new);                               \
        switch (size) {                                                 \
        case __X86_CASE_B:                                              \
        {                                                               \
                volatile u8 *__ptr = (volatile u8 *)(ptr);              \
                asm_inline volatile(lock "cmpxchgb %2, %1"              \
                             : "=a" (__ret), "+m" (*__ptr)              \
                             : "q" (__new), "0" (__old)                 \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        case __X86_CASE_W:                                              \
        {                                                               \
                volatile u16 *__ptr = (volatile u16 *)(ptr);            \
                asm_inline volatile(lock "cmpxchgw %2, %1"              \
                             : "=a" (__ret), "+m" (*__ptr)              \
                             : "r" (__new), "0" (__old)                 \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        case __X86_CASE_L:                                              \
        {                                                               \
                volatile u32 *__ptr = (volatile u32 *)(ptr);            \
                asm_inline volatile(lock "cmpxchgl %2, %1"              \
                             : "=a" (__ret), "+m" (*__ptr)              \
                             : "r" (__new), "0" (__old)                 \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        case __X86_CASE_Q:                                              \
        {                                                               \
                volatile u64 *__ptr = (volatile u64 *)(ptr);            \
                asm_inline volatile(lock "cmpxchgq %2, %1"              \
                             : "=a" (__ret), "+m" (*__ptr)              \
                             : "r" (__new), "0" (__old)                 \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        default:                                                        \
                __cmpxchg_wrong_size();                                 \
        }                                                               \
        __ret;                                                          \
})

#define __cmpxchg(ptr, old, new, size)                                  \
        __raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX)

#define __sync_cmpxchg(ptr, old, new, size)                             \
        __raw_cmpxchg((ptr), (old), (new), (size), "lock ")

#define __cmpxchg_local(ptr, old, new, size)                            \
        __raw_cmpxchg((ptr), (old), (new), (size), "")

#ifdef CONFIG_X86_32
# include <asm/cmpxchg_32.h>
#else
# include <asm/cmpxchg_64.h>
#endif

#define arch_cmpxchg(ptr, old, new)                                     \
        __cmpxchg(ptr, old, new, sizeof(*(ptr)))

#define arch_sync_cmpxchg(ptr, old, new)                                \
        __sync_cmpxchg(ptr, old, new, sizeof(*(ptr)))

#define arch_cmpxchg_local(ptr, old, new)                               \
        __cmpxchg_local(ptr, old, new, sizeof(*(ptr)))


#define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock)                \
({                                                                      \
        bool success;                                                   \
        __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);              \
        __typeof__(*(_ptr)) __old = *_old;                              \
        __typeof__(*(_ptr)) __new = (_new);                             \
        switch (size) {                                                 \
        case __X86_CASE_B:                                              \
        {                                                               \
                volatile u8 *__ptr = (volatile u8 *)(_ptr);             \
                asm_inline volatile(lock "cmpxchgb %[new], %[ptr]"      \
                             : "=@ccz" (success),                       \
                               [ptr] "+m" (*__ptr),                     \
                               [old] "+a" (__old)                       \
                             : [new] "q" (__new)                        \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        case __X86_CASE_W:                                              \
        {                                                               \
                volatile u16 *__ptr = (volatile u16 *)(_ptr);           \
                asm_inline volatile(lock "cmpxchgw %[new], %[ptr]"      \
                             : "=@ccz" (success),                       \
                               [ptr] "+m" (*__ptr),                     \
                               [old] "+a" (__old)                       \
                             : [new] "r" (__new)                        \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        case __X86_CASE_L:                                              \
        {                                                               \
                volatile u32 *__ptr = (volatile u32 *)(_ptr);           \
                asm_inline volatile(lock "cmpxchgl %[new], %[ptr]"      \
                             : "=@ccz" (success),                       \
                               [ptr] "+m" (*__ptr),                     \
                               [old] "+a" (__old)                       \
                             : [new] "r" (__new)                        \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        case __X86_CASE_Q:                                              \
        {                                                               \
                volatile u64 *__ptr = (volatile u64 *)(_ptr);           \
                asm_inline volatile(lock "cmpxchgq %[new], %[ptr]"      \
                             : "=@ccz" (success),                       \
                               [ptr] "+m" (*__ptr),                     \
                               [old] "+a" (__old)                       \
                             : [new] "r" (__new)                        \
                             : "memory");                               \
                break;                                                  \
        }                                                               \
        default:                                                        \
                __cmpxchg_wrong_size();                                 \
        }                                                               \
        if (unlikely(!success))                                         \
                *_old = __old;                                          \
        likely(success);                                                \
})

#define __try_cmpxchg(ptr, pold, new, size)                             \
        __raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)

#define __sync_try_cmpxchg(ptr, pold, new, size)                        \
        __raw_try_cmpxchg((ptr), (pold), (new), (size), "lock ")

#define __try_cmpxchg_local(ptr, pold, new, size)                       \
        __raw_try_cmpxchg((ptr), (pold), (new), (size), "")

#define arch_try_cmpxchg(ptr, pold, new)                                \
        __try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))

#define arch_sync_try_cmpxchg(ptr, pold, new)                           \
        __sync_try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))

#define arch_try_cmpxchg_local(ptr, pold, new)                          \
        __try_cmpxchg_local((ptr), (pold), (new), sizeof(*(ptr)))

/*
 * xadd() adds "inc" to "*ptr" and atomically returns the previous
 * value of "*ptr".
 *
 * xadd() is locked when multiple CPUs are online
 */
#define __xadd(ptr, inc, lock)  __xchg_op((ptr), (inc), xadd, lock)
#define xadd(ptr, inc)          __xadd((ptr), (inc), LOCK_PREFIX)

#endif  /* ASM_X86_CMPXCHG_H */