/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2012 ARM Ltd.
 */
#ifndef __ASM_FUTEX_H
#define __ASM_FUTEX_H

#include <linux/futex.h>
#include <linux/uaccess.h>

#include <asm/errno.h>

#define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */

#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
do {                                                                    \
        unsigned int loops = FUTEX_MAX_LOOPS;                           \
                                                                        \
        uaccess_enable_privileged();                                    \
        asm volatile(                                                   \
"       prfm    pstl1strm, %2\n"                                        \
"1:     ldxr    %w1, %2\n"                                              \
        insn "\n"                                                       \
"2:     stlxr   %w0, %w3, %2\n"                                         \
"       cbz     %w0, 3f\n"                                              \
"       sub     %w4, %w4, %w0\n"                                        \
"       cbnz    %w4, 1b\n"                                              \
"       mov     %w0, %w6\n"                                             \
"3:\n"                                                                  \
"       dmb     ish\n"                                                  \
        _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0)                           \
        _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w0)                           \
        : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp),      \
          "+r" (loops)                                                  \
        : "r" (oparg), "Ir" (-EAGAIN)                                   \
        : "memory");                                                    \
        uaccess_disable_privileged();                                   \
} while (0)

static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
{
        int oldval = 0, ret, tmp;
        u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);

        if (!access_ok(_uaddr, sizeof(u32)))
                return -EFAULT;

        switch (op) {
        case FUTEX_OP_SET:
                __futex_atomic_op("mov  %w3, %w5",
                                  ret, oldval, uaddr, tmp, oparg);
                break;
        case FUTEX_OP_ADD:
                __futex_atomic_op("add  %w3, %w1, %w5",
                                  ret, oldval, uaddr, tmp, oparg);
                break;
        case FUTEX_OP_OR:
                __futex_atomic_op("orr  %w3, %w1, %w5",
                                  ret, oldval, uaddr, tmp, oparg);
                break;
        case FUTEX_OP_ANDN:
                __futex_atomic_op("and  %w3, %w1, %w5",
                                  ret, oldval, uaddr, tmp, ~oparg);
                break;
        case FUTEX_OP_XOR:
                __futex_atomic_op("eor  %w3, %w1, %w5",
                                  ret, oldval, uaddr, tmp, oparg);
                break;
        default:
                ret = -ENOSYS;
        }

        if (!ret)
                *oval = oldval;

        return ret;
}

static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
                              u32 oldval, u32 newval)
{
        int ret = 0;
        unsigned int loops = FUTEX_MAX_LOOPS;
        u32 val, tmp;
        u32 __user *uaddr;

        if (!access_ok(_uaddr, sizeof(u32)))
                return -EFAULT;

        uaddr = __uaccess_mask_ptr(_uaddr);
        uaccess_enable_privileged();
        asm volatile("// futex_atomic_cmpxchg_inatomic\n"
"       prfm    pstl1strm, %2\n"
"1:     ldxr    %w1, %2\n"
"       sub     %w3, %w1, %w5\n"
"       cbnz    %w3, 4f\n"
"2:     stlxr   %w3, %w6, %2\n"
"       cbz     %w3, 3f\n"
"       sub     %w4, %w4, %w3\n"
"       cbnz    %w4, 1b\n"
"       mov     %w0, %w7\n"
"3:\n"
"       dmb     ish\n"
"4:\n"
        _ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w0)
        _ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w0)
        : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
        : "r" (oldval), "r" (newval), "Ir" (-EAGAIN)
        : "memory");
        uaccess_disable_privileged();

        if (!ret)
                *uval = val;

        return ret;
}

#endif /* __ASM_FUTEX_H */