/*      $NetBSD: atomic.S,v 1.38 2025/09/06 02:53:21 riastradh Exp $    */

/*-
 * Copyright (c) 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe, and by Andrew Doran.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <machine/asm.h>
/*
 * __HAVE_ constants should not be in <machine/types.h>
 * because we can't use them from assembly. OTOH we
 * only need __HAVE_ATOMIC64_OPS here, and we don't.
 */
#ifdef _KERNEL
#define ALIAS(f, t)     STRONG_ALIAS(f,t)
#else
#define ALIAS(f, t)     WEAK_ALIAS(f,t)
#endif

#ifdef _HARDKERNEL
#include "opt_xen.h"
#include <machine/frameasm.h>
#define LOCK                    HOTPATCH(HP_NAME_NOLOCK, 1); lock
#define HOTPATCH_CAS_64         HOTPATCH(HP_NAME_CAS_64, 49);
#else
#define LOCK                    lock
#define HOTPATCH_CAS_64         /* nothing */
#endif

        .text

ENTRY(_atomic_add_32)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        LOCK
        addl    %eax, (%edx)
        ret
END(_atomic_add_32)

ENTRY(_atomic_add_32_nv)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        movl    %eax, %ecx
        LOCK
        xaddl   %eax, (%edx)
        addl    %ecx, %eax
        ret
END(_atomic_add_32_nv)

ENTRY(_atomic_and_32)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        LOCK
        andl    %eax, (%edx)
        ret
END(_atomic_and_32)

ENTRY(_atomic_and_32_nv)
        movl    4(%esp), %edx
        movl    (%edx), %eax
0:
        movl    %eax, %ecx
        andl    8(%esp), %ecx
        LOCK
        cmpxchgl %ecx, (%edx)
        jnz     1f
        movl    %ecx, %eax
        ret
1:
        jmp     0b
END(_atomic_and_32_nv)

ENTRY(_atomic_dec_32)
        movl    4(%esp), %edx
        LOCK
        decl    (%edx)
        ret
END(_atomic_dec_32)

ENTRY(_atomic_dec_32_nv)
        movl    4(%esp), %edx
        movl    $-1, %eax
        LOCK
        xaddl   %eax, (%edx)
        decl    %eax
        ret
END(_atomic_dec_32_nv)

ENTRY(_atomic_inc_32)
        movl    4(%esp), %edx
        LOCK
        incl    (%edx)
        ret
END(_atomic_inc_32)

ENTRY(_atomic_inc_32_nv)
        movl    4(%esp), %edx
        movl    $1, %eax
        LOCK
        xaddl   %eax, (%edx)
        incl    %eax
        ret
END(_atomic_inc_32_nv)

ENTRY(_atomic_or_32)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        LOCK
        orl     %eax, (%edx)
        ret
END(_atomic_or_32)

ENTRY(_atomic_or_32_nv)
        movl    4(%esp), %edx
        movl    (%edx), %eax
0:
        movl    %eax, %ecx
        orl     8(%esp), %ecx
        LOCK
        cmpxchgl %ecx, (%edx)
        jnz     1f
        movl    %ecx, %eax
        ret
1:
        jmp     0b
END(_atomic_or_32_nv)

ENTRY(_atomic_swap_32)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        xchgl   %eax, (%edx)
        ret
END(_atomic_swap_32)

ENTRY(_atomic_cas_32)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        movl    12(%esp), %ecx
        LOCK
        cmpxchgl %ecx, (%edx)
        /* %eax now contains the old value */
        ret
END(_atomic_cas_32)

ENTRY(_atomic_cas_32_ni)
        movl    4(%esp), %edx
        movl    8(%esp), %eax
        movl    12(%esp), %ecx
        cmpxchgl %ecx, (%edx)
        /* %eax now contains the old value */
        ret
END(_atomic_cas_32_ni)

ENTRY(_membar_acquire)
        /*
         * Every load from normal memory is a load-acquire on x86, so
         * there is never any need for explicit barriers to order
         * load-before-anything.
         */
        ret
END(_membar_acquire)

ENTRY(_membar_release)
        /*
         * Every store to normal memory is a store-release on x86, so
         * there is never any need for explicit barriers to order
         * anything-before-store.
         */
        ret
END(_membar_release)

ENTRY(_membar_sync)
        /*
         * MFENCE, or a serializing instruction like a locked ADDL,
         * is necessary to order store-before-load.  Every other
         * ordering -- load-before-anything, anything-before-store --
         * is already guaranteed without explicit barriers.
         *
         * Empirically it turns out locked ADDL is cheaper than MFENCE,
         * so we use that, with an offset below the return address on
         * the stack to avoid a false dependency with RET.  (It might
         * even be better to use a much lower offset, say -128, to
         * avoid false dependencies for subsequent callees of the
         * caller.)
         *
         * https://pvk.ca/Blog/2014/10/19/performance-optimisation-~-writing-an-essay/
         * https://shipilev.net/blog/2014/on-the-fence-with-dependencies/
         * https://www.agner.org/optimize/instruction_tables.pdf
         *
         * Sync with paravirt_membar_sync in
         * sys/arch/i386/i386/cpufunc.S.
         */
        LOCK
        addl    $0, -4(%esp)
        ret
END(_membar_sync)

#if defined(__HAVE_ATOMIC64_OPS) || defined(_KERNEL)
#ifdef XENPV
STRONG_ALIAS(_atomic_cas_64,_atomic_cas_cx8)
#else
ENTRY(_atomic_cas_64)
        HOTPATCH_CAS_64
        /* 49 bytes of instructions */
#ifdef _HARDKERNEL
        pushf
        cli
#endif
        pushl   %edi
        pushl   %ebx
        movl    12(%esp), %edi
        movl    16(%esp), %eax
        movl    20(%esp), %edx
        movl    24(%esp), %ebx
        movl    28(%esp), %ecx
        cmpl    0(%edi), %eax
        jne     2f
        cmpl    4(%edi), %edx
        jne     2f
        movl    %ebx, 0(%edi)
        movl    %ecx, 4(%edi)
1:
        popl    %ebx
        popl    %edi
#ifdef _HARDKERNEL
        popf
#endif
        ret
2:
        movl    0(%edi), %eax
        movl    4(%edi), %edx
        jmp     1b
END(_atomic_cas_64)
#endif /* !XENPV */

ENTRY(_atomic_cas_cx8)
        /* 49 bytes of instructions */
        pushl   %edi
        pushl   %ebx
        movl    12(%esp), %edi
        movl    16(%esp), %eax
        movl    20(%esp), %edx
        movl    24(%esp), %ebx
        movl    28(%esp), %ecx
        LOCK
        cmpxchg8b (%edi)
        popl    %ebx
        popl    %edi
        ret
#ifdef _HARDKERNEL
        .space  20, 0xCC
#endif
END(_atomic_cas_cx8)
LABEL(_atomic_cas_cx8_end)
#endif /* __HAVE_ATOMIC64_OPS || _KERNEL */

ALIAS(atomic_add_32,_atomic_add_32)
ALIAS(atomic_add_int,_atomic_add_32)
ALIAS(atomic_add_long,_atomic_add_32)
ALIAS(atomic_add_ptr,_atomic_add_32)

ALIAS(atomic_add_32_nv,_atomic_add_32_nv)
ALIAS(atomic_add_int_nv,_atomic_add_32_nv)
ALIAS(atomic_add_long_nv,_atomic_add_32_nv)
ALIAS(atomic_add_ptr_nv,_atomic_add_32_nv)

ALIAS(atomic_and_32,_atomic_and_32)
ALIAS(atomic_and_uint,_atomic_and_32)
ALIAS(atomic_and_ulong,_atomic_and_32)
ALIAS(atomic_and_ptr,_atomic_and_32)

ALIAS(atomic_and_32_nv,_atomic_and_32_nv)
ALIAS(atomic_and_uint_nv,_atomic_and_32_nv)
ALIAS(atomic_and_ulong_nv,_atomic_and_32_nv)
ALIAS(atomic_and_ptr_nv,_atomic_and_32_nv)

ALIAS(atomic_dec_32,_atomic_dec_32)
ALIAS(atomic_dec_uint,_atomic_dec_32)
ALIAS(atomic_dec_ulong,_atomic_dec_32)
ALIAS(atomic_dec_ptr,_atomic_dec_32)

ALIAS(atomic_dec_32_nv,_atomic_dec_32_nv)
ALIAS(atomic_dec_uint_nv,_atomic_dec_32_nv)
ALIAS(atomic_dec_ulong_nv,_atomic_dec_32_nv)
ALIAS(atomic_dec_ptr_nv,_atomic_dec_32_nv)

ALIAS(atomic_inc_32,_atomic_inc_32)
ALIAS(atomic_inc_uint,_atomic_inc_32)
ALIAS(atomic_inc_ulong,_atomic_inc_32)
ALIAS(atomic_inc_ptr,_atomic_inc_32)

ALIAS(atomic_inc_32_nv,_atomic_inc_32_nv)
ALIAS(atomic_inc_uint_nv,_atomic_inc_32_nv)
ALIAS(atomic_inc_ulong_nv,_atomic_inc_32_nv)
ALIAS(atomic_inc_ptr_nv,_atomic_inc_32_nv)

ALIAS(atomic_or_32,_atomic_or_32)
ALIAS(atomic_or_uint,_atomic_or_32)
ALIAS(atomic_or_ulong,_atomic_or_32)
ALIAS(atomic_or_ptr,_atomic_or_32)

ALIAS(atomic_or_32_nv,_atomic_or_32_nv)
ALIAS(atomic_or_uint_nv,_atomic_or_32_nv)
ALIAS(atomic_or_ulong_nv,_atomic_or_32_nv)
ALIAS(atomic_or_ptr_nv,_atomic_or_32_nv)

ALIAS(atomic_swap_32,_atomic_swap_32)
ALIAS(atomic_swap_uint,_atomic_swap_32)
ALIAS(atomic_swap_ulong,_atomic_swap_32)
ALIAS(atomic_swap_ptr,_atomic_swap_32)

ALIAS(atomic_cas_32,_atomic_cas_32)
ALIAS(atomic_cas_uint,_atomic_cas_32)
ALIAS(atomic_cas_ulong,_atomic_cas_32)
ALIAS(atomic_cas_ptr,_atomic_cas_32)

ALIAS(atomic_cas_32_ni,_atomic_cas_32_ni)
ALIAS(atomic_cas_uint_ni,_atomic_cas_32_ni)
ALIAS(atomic_cas_ulong_ni,_atomic_cas_32_ni)
ALIAS(atomic_cas_ptr_ni,_atomic_cas_32_ni)

#if defined(__HAVE_ATOMIC64_OPS) || defined(_KERNEL)
ALIAS(atomic_cas_64,_atomic_cas_64)
ALIAS(atomic_cas_64_ni,_atomic_cas_64)
ALIAS(__sync_val_compare_and_swap_8,_atomic_cas_64)
#endif /* __HAVE_ATOMIC64_OPS || _KERNEL */

ALIAS(membar_acquire,_membar_acquire)
ALIAS(membar_release,_membar_release)
ALIAS(membar_sync,_membar_sync)

ALIAS(membar_consumer,_membar_acquire)
ALIAS(membar_producer,_membar_release)
ALIAS(membar_enter,_membar_sync)
ALIAS(membar_exit,_membar_release)
ALIAS(membar_sync,_membar_sync)

STRONG_ALIAS(_atomic_add_int,_atomic_add_32)
STRONG_ALIAS(_atomic_add_long,_atomic_add_32)
STRONG_ALIAS(_atomic_add_ptr,_atomic_add_32)

STRONG_ALIAS(_atomic_add_int_nv,_atomic_add_32_nv)
STRONG_ALIAS(_atomic_add_long_nv,_atomic_add_32_nv)
STRONG_ALIAS(_atomic_add_ptr_nv,_atomic_add_32_nv)

STRONG_ALIAS(_atomic_and_uint,_atomic_and_32)
STRONG_ALIAS(_atomic_and_ulong,_atomic_and_32)
STRONG_ALIAS(_atomic_and_ptr,_atomic_and_32)

STRONG_ALIAS(_atomic_and_uint_nv,_atomic_and_32_nv)
STRONG_ALIAS(_atomic_and_ulong_nv,_atomic_and_32_nv)
STRONG_ALIAS(_atomic_and_ptr_nv,_atomic_and_32_nv)

STRONG_ALIAS(_atomic_dec_uint,_atomic_dec_32)
STRONG_ALIAS(_atomic_dec_ulong,_atomic_dec_32)
STRONG_ALIAS(_atomic_dec_ptr,_atomic_dec_32)

STRONG_ALIAS(_atomic_dec_uint_nv,_atomic_dec_32_nv)
STRONG_ALIAS(_atomic_dec_ulong_nv,_atomic_dec_32_nv)
STRONG_ALIAS(_atomic_dec_ptr_nv,_atomic_dec_32_nv)

STRONG_ALIAS(_atomic_inc_uint,_atomic_inc_32)
STRONG_ALIAS(_atomic_inc_ulong,_atomic_inc_32)
STRONG_ALIAS(_atomic_inc_ptr,_atomic_inc_32)

STRONG_ALIAS(_atomic_inc_uint_nv,_atomic_inc_32_nv)
STRONG_ALIAS(_atomic_inc_ulong_nv,_atomic_inc_32_nv)
STRONG_ALIAS(_atomic_inc_ptr_nv,_atomic_inc_32_nv)

STRONG_ALIAS(_atomic_or_uint,_atomic_or_32)
STRONG_ALIAS(_atomic_or_ulong,_atomic_or_32)
STRONG_ALIAS(_atomic_or_ptr,_atomic_or_32)

STRONG_ALIAS(_atomic_or_uint_nv,_atomic_or_32_nv)
STRONG_ALIAS(_atomic_or_ulong_nv,_atomic_or_32_nv)
STRONG_ALIAS(_atomic_or_ptr_nv,_atomic_or_32_nv)

STRONG_ALIAS(_atomic_swap_uint,_atomic_swap_32)
STRONG_ALIAS(_atomic_swap_ulong,_atomic_swap_32)
STRONG_ALIAS(_atomic_swap_ptr,_atomic_swap_32)

STRONG_ALIAS(_atomic_cas_uint,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_ulong,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_ptr,_atomic_cas_32)

STRONG_ALIAS(_atomic_cas_uint_ni,_atomic_cas_32_ni)
STRONG_ALIAS(_atomic_cas_ulong_ni,_atomic_cas_32_ni)
STRONG_ALIAS(_atomic_cas_ptr_ni,_atomic_cas_32_ni)

STRONG_ALIAS(_membar_consumer,_membar_acquire)
STRONG_ALIAS(_membar_producer,_membar_release)
STRONG_ALIAS(_membar_enter,_membar_sync)
STRONG_ALIAS(_membar_exit,_membar_release)