/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2000 Peter Wemm <peter@FreeBSD.org>
 * Copyright 2026 The FreeBSD Foundation
 * All rights reserved.
 *
 * Portions of this software were developed by
 * Konstantin Belousov <kib@FreeBSD.org> under sponsorship from
 * the FreeBSD Foundation.
 */

#include <machine/asm.h>
/*
 * With thanks to John Dyson for the original version of this.
 */

#include <SYS.h>

/*
 *              8    12      16       20          24         28
 * rfork_thread(fdp, pdflags rfflags, stack_addr, start_fnc, start_arg);
 *
 * fdp                  Pointer for the resulting fd location
 * pdflags              Flags as to pdfork.
 * rfflags:             Flags as to rfork.
 * stack_addr:          Top of stack for thread.
 * start_fnc:           Address of thread function to call in child.
 * start_arg:           Argument to pass to the thread function in child.
 */

ENTRY(pdrfork_thread)
        pushl   %ebp
        movl    %esp, %ebp
        pushl   %esi

        /*
         * Push thread info onto the new thread's stack
         */
        movl    20(%ebp), %esi  # get stack addr

        subl    $4, %esi
        movl    28(%ebp), %eax  # get start argument
        movl    %eax, (%esi)

        subl    $4, %esi
        movl    24(%ebp), %eax  # get start thread address
        movl    %eax, (%esi)

        /*
         * Prepare and execute the thread creation syscall
         */
        pushl   16(%ebp)
        pushl   12(%ebp)
        pushl   8(%ebp)
        pushl   $0
        _SYSCALL(pdrfork)
        jb      2f

        /*
         * Check to see if we are in the parent or child
         */
        cmpl    $0, %edx
        jnz     1f
        addl    $16, %esp
        popl    %esi
        movl    %ebp, %esp
        popl    %ebp
        ret
        .p2align 2

        /*
         * If we are in the child (new thread), then
         * set-up the call to the internal subroutine.  If it
         * returns, then call __exit.
         */
1:
        movl    %esi,%esp
        popl    %eax
        call    *%eax
        addl    $4, %esp

        /*
         * Exit system call
         */
        pushl   %eax
        pushl   $0
        _SYSCALL(exit)

        /*
         * Branch here if the thread creation fails:
         */
2:
        addl    $16, %esp
        popl    %esi
        movl    %ebp, %esp
        popl    %ebp
        jmp     HIDENAME(cerror)
END(pdrfork_thread)

        .section .note.GNU-stack,"",%progbits