root/arch/xtensa/include/asm/futex.h
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Atomic futex routines
 *
 * Based on the PowerPC implementataion
 *
 * Copyright (C) 2013 TangoTec Ltd.
 *
 * Baruch Siach <baruch@tkos.co.il>
 */

#ifndef _ASM_XTENSA_FUTEX_H
#define _ASM_XTENSA_FUTEX_H

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

#define arch_futex_atomic_op_inuser arch_futex_atomic_op_inuser
#define futex_atomic_cmpxchg_inatomic futex_atomic_cmpxchg_inatomic
#include <asm-generic/futex.h>

#if XCHAL_HAVE_EXCLUSIVE
#define __futex_atomic_op(insn, ret, old, uaddr, arg)   \
        __asm__ __volatile(                             \
        "1:     l32ex   %[oldval], %[addr]\n"           \
                insn "\n"                               \
        "2:     s32ex   %[newval], %[addr]\n"           \
        "       getex   %[newval]\n"                    \
        "       beqz    %[newval], 1b\n"                \
        "       movi    %[newval], 0\n"                 \
        "3:\n"                                          \
        "       .section .fixup,\"ax\"\n"               \
        "       .align 4\n"                             \
        "       .literal_position\n"                    \
        "5:     movi    %[oldval], 3b\n"                \
        "       movi    %[newval], %[fault]\n"          \
        "       jx      %[oldval]\n"                    \
        "       .previous\n"                            \
        "       .section __ex_table,\"a\"\n"            \
        "       .long 1b, 5b, 2b, 5b\n"                 \
        "       .previous\n"                            \
        : [oldval] "=&r" (old), [newval] "=&r" (ret)    \
        : [addr] "r" (uaddr), [oparg] "r" (arg),        \
          [fault] "I" (-EFAULT)                         \
        : "memory")
#elif XCHAL_HAVE_S32C1I
#define __futex_atomic_op(insn, ret, old, uaddr, arg)   \
        __asm__ __volatile(                             \
        "1:     l32i    %[oldval], %[mem]\n"            \
                insn "\n"                               \
        "       wsr     %[oldval], scompare1\n"         \
        "2:     s32c1i  %[newval], %[mem]\n"            \
        "       bne     %[newval], %[oldval], 1b\n"     \
        "       movi    %[newval], 0\n"                 \
        "3:\n"                                          \
        "       .section .fixup,\"ax\"\n"               \
        "       .align 4\n"                             \
        "       .literal_position\n"                    \
        "5:     movi    %[oldval], 3b\n"                \
        "       movi    %[newval], %[fault]\n"          \
        "       jx      %[oldval]\n"                    \
        "       .previous\n"                            \
        "       .section __ex_table,\"a\"\n"            \
        "       .long 1b, 5b, 2b, 5b\n"                 \
        "       .previous\n"                            \
        : [oldval] "=&r" (old), [newval] "=&r" (ret),   \
          [mem] "+m" (*(uaddr))                         \
        : [oparg] "r" (arg), [fault] "I" (-EFAULT)      \
        : "memory")
#endif

static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
                u32 __user *uaddr)
{
#if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE
        int oldval = 0, ret;

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

        switch (op) {
        case FUTEX_OP_SET:
                __futex_atomic_op("mov %[newval], %[oparg]",
                                  ret, oldval, uaddr, oparg);
                break;
        case FUTEX_OP_ADD:
                __futex_atomic_op("add %[newval], %[oldval], %[oparg]",
                                  ret, oldval, uaddr, oparg);
                break;
        case FUTEX_OP_OR:
                __futex_atomic_op("or %[newval], %[oldval], %[oparg]",
                                  ret, oldval, uaddr, oparg);
                break;
        case FUTEX_OP_ANDN:
                __futex_atomic_op("and %[newval], %[oldval], %[oparg]",
                                  ret, oldval, uaddr, ~oparg);
                break;
        case FUTEX_OP_XOR:
                __futex_atomic_op("xor %[newval], %[oldval], %[oparg]",
                                  ret, oldval, uaddr, oparg);
                break;
        default:
                ret = -ENOSYS;
        }

        if (!ret)
                *oval = oldval;

        return ret;
#else
        return futex_atomic_op_inuser_local(op, oparg, oval, uaddr);
#endif
}

static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
                              u32 oldval, u32 newval)
{
#if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE
        unsigned long tmp;
        int ret = 0;

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

        __asm__ __volatile__ (
        "       # futex_atomic_cmpxchg_inatomic\n"
#if XCHAL_HAVE_EXCLUSIVE
        "1:     l32ex   %[tmp], %[addr]\n"
        "       s32i    %[tmp], %[uval], 0\n"
        "       bne     %[tmp], %[oldval], 2f\n"
        "       mov     %[tmp], %[newval]\n"
        "3:     s32ex   %[tmp], %[addr]\n"
        "       getex   %[tmp]\n"
        "       beqz    %[tmp], 1b\n"
#elif XCHAL_HAVE_S32C1I
        "       wsr     %[oldval], scompare1\n"
        "1:     s32c1i  %[newval], %[addr], 0\n"
        "       s32i    %[newval], %[uval], 0\n"
#endif
        "2:\n"
        "       .section .fixup,\"ax\"\n"
        "       .align 4\n"
        "       .literal_position\n"
        "4:     movi    %[tmp], 2b\n"
        "       movi    %[ret], %[fault]\n"
        "       jx      %[tmp]\n"
        "       .previous\n"
        "       .section __ex_table,\"a\"\n"
        "       .long 1b, 4b\n"
#if XCHAL_HAVE_EXCLUSIVE
        "       .long 3b, 4b\n"
#endif
        "       .previous\n"
        : [ret] "+r" (ret), [newval] "+r" (newval), [tmp] "=&r" (tmp)
        : [addr] "r" (uaddr), [oldval] "r" (oldval), [uval] "r" (uval),
          [fault] "I" (-EFAULT)
        : "memory");

        return ret;
#else
        return futex_atomic_cmpxchg_inatomic_local(uval, uaddr, oldval, newval);
#endif
}

#endif /* _ASM_XTENSA_FUTEX_H */