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

#ifdef __KERNEL__

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

#define __futex_atomic_ex_table(err_reg)                        \
        "3:\n"                                                  \
        "       .pushsection __ex_table,\"a\"\n"                \
        "       .align  3\n"                                    \
        "       .long   1b, 4f, 2b, 4f\n"                       \
        "       .popsection\n"                                  \
        "       .pushsection .text.fixup,\"ax\"\n"              \
        "       .align  2\n"                                    \
        "4:     mov     %0, " err_reg "\n"                      \
        "       b       3b\n"                                   \
        "       .popsection"

#ifdef CONFIG_SMP

#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
({                                                              \
        unsigned int __ua_flags;                                \
        smp_mb();                                               \
        prefetchw(uaddr);                                       \
        __ua_flags = uaccess_save_and_enable();                 \
        __asm__ __volatile__(                                   \
        "1:     ldrex   %1, [%3]\n"                             \
        "       " insn "\n"                                     \
        "2:     strex   %2, %0, [%3]\n"                         \
        "       teq     %2, #0\n"                               \
        "       bne     1b\n"                                   \
        "       mov     %0, #0\n"                               \
        __futex_atomic_ex_table("%5")                           \
        : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
        : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
        : "cc", "memory");                                      \
        uaccess_restore(__ua_flags);                            \
})

static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
                              u32 oldval, u32 newval)
{
        unsigned int __ua_flags;
        int ret;
        u32 val;

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

        smp_mb();
        /* Prefetching cannot fault */
        prefetchw(uaddr);
        __ua_flags = uaccess_save_and_enable();
        __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
        "1:     ldrex   %1, [%4]\n"
        "       teq     %1, %2\n"
        "       ite     eq      @ explicit IT needed for the 2b label\n"
        "2:     strexeq %0, %3, [%4]\n"
        "       movne   %0, #0\n"
        "       teq     %0, #0\n"
        "       bne     1b\n"
        __futex_atomic_ex_table("%5")
        : "=&r" (ret), "=&r" (val)
        : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
        : "cc", "memory");
        uaccess_restore(__ua_flags);
        smp_mb();

        *uval = val;
        return ret;
}

#else /* !SMP, we can work around lack of atomic ops by disabling preemption */

#include <linux/preempt.h>
#include <asm/domain.h>

#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
({                                                              \
        unsigned int __ua_flags = uaccess_save_and_enable();    \
        __asm__ __volatile__(                                   \
        "1:     " TUSER(ldr) "  %1, [%3]\n"                     \
        "       " insn "\n"                                     \
        "2:     " TUSER(str) "  %0, [%3]\n"                     \
        "       mov     %0, #0\n"                               \
        __futex_atomic_ex_table("%5")                           \
        : "=&r" (ret), "=&r" (oldval), "=&r" (tmp)              \
        : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT)              \
        : "cc", "memory");                                      \
        uaccess_restore(__ua_flags);                            \
})

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

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

        preempt_disable();
        __ua_flags = uaccess_save_and_enable();
        __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
        "       .syntax unified\n"
        "1:     " TUSER(ldr) "  %1, [%4]\n"
        "       teq     %1, %2\n"
        "       it      eq      @ explicit IT needed for the 2b label\n"
        "2:     " TUSERCOND(str, eq) "  %3, [%4]\n"
        __futex_atomic_ex_table("%5")
        : "+r" (ret), "=&r" (val)
        : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
        : "cc", "memory");
        uaccess_restore(__ua_flags);

        *uval = val;
        preempt_enable();

        return ret;
}

#endif /* !SMP */

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

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

#ifndef CONFIG_SMP
        preempt_disable();
#endif

        switch (op) {
        case FUTEX_OP_SET:
                __futex_atomic_op("mov  %0, %4", ret, oldval, tmp, uaddr, oparg);
                break;
        case FUTEX_OP_ADD:
                __futex_atomic_op("add  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
                break;
        case FUTEX_OP_OR:
                __futex_atomic_op("orr  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
                break;
        case FUTEX_OP_ANDN:
                __futex_atomic_op("and  %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
                break;
        case FUTEX_OP_XOR:
                __futex_atomic_op("eor  %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
                break;
        default:
                ret = -ENOSYS;
        }

#ifndef CONFIG_SMP
        preempt_enable();
#endif

        /*
         * Store unconditionally. If ret != 0 the extra store is the least
         * of the worries but GCC cannot figure out that __futex_atomic_op()
         * is either setting ret to -EFAULT or storing the old value in
         * oldval which results in a uninitialized warning at the call site.
         */
        *oval = oldval;

        return ret;
}

#endif /* __KERNEL__ */
#endif /* _ASM_ARM_FUTEX_H */