/*      $NetBSD: startprog32.S,v 1.3 2023/04/20 00:42:24 manu Exp $     */
/*      NetBSD: startprog.S,v 1.4 2016/12/04 08:21:08 maxv Exp  */

/*
* Ported to boot 386BSD by Julian Elischer ([email protected]) Sept 1992
*
* Mach Operating System
* Copyright (c) 1992, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
*  Software Distribution Coordinator  or  [email protected]
*  School of Computer Science
*  Carnegie Mellon University
*  Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/

/*
*   Copyright 1988, 1989, 1990, 1991, 1992
*    by Intel Corporation, Santa Clara, California.
*
*                 All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice appears in all
* copies and that both the copyright notice and this permission notice
* appear in supporting documentation, and that the name of Intel
* not be used in advertising or publicity pertaining to distribution
* of the software without specific, written prior permission.
*
* INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
* IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
* NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include <machine/asm.h>
#include <machine/specialreg.h>

#define CODE_SEGMENT    0x08
#define DATA_SEGMENT    0x10

       .align  16
       .globl _C_LABEL(startprog32)
_C_LABEL(startprog32):
       .quad 0

       .globl _C_LABEL(startprog32_size)
_C_LABEL(startprog32_size):
       .long startprog32_end - _C_LABEL(startprog32_start)

       .text
       .p2align 4,,15

/*
* startprog32(entry,argc,argv,stack,kern_start,kern_load,kern_size,loadaddr)
*/
ENTRY(startprog32_start)
start:
       pushl   %ebp
       movl    %esp, %ebp

       /*
        * 8(%ebp): kernel entry address
        * 12(%ebp): argc
        * 16(%ebp): argv
        * 20(%ebp): stack address
        * 24(%ebp): kernel start address
        * 28(%ebp): loaded kernel address
        * 32(%ebp): loaded kernel size
        * 36(%ebp): loaded start address
        */

       cli

       movl    8(%ebp), %ebx   /* %ebx: entry address */
       movl    36(%ebp), %edx  /* %edx: loaded start address */

       /* Prepare a new stack */
       movl    20(%ebp), %eax  /* stack */
       subl    $4, %eax
       movl    %eax, %edi

       /* Push some number of args onto the stack */
       movl    12(%ebp), %ecx  /* argc */
       movl    %ecx, %eax
       decl    %eax
       shl     $2, %eax
       addl    16(%ebp), %eax  /* ptr to last arg */
       movl    %eax, %esi

       std                     /* backwards */
       rep
       movsl                   /* copy %ds:(%esi) -> %es:(%edi) */
       cld
       mov     %edi, %esp      /* set new stack pointer */

       /* Copy kernel */
       movl    24(%ebp), %edi  /* dest */
       movl    28(%ebp), %esi  /* src */
       movl    32(%ebp), %ecx  /* size */

       /* skip copy if same source and destination */
       cmpl    %edi,%esi
       jz      .Lcopy_done

#if defined(NO_OVERLAP)
       movl    %ecx, %eax
#else
       movl    %edi, %eax
       subl    %esi, %eax
       cmpl    %ecx, %eax      /* overlapping? */
       movl    %ecx, %eax
       jb      .Lbackwards
#endif
       /* nope, copy forwards. */
       shrl    $2, %ecx        /* copy by words */
       rep
       movsl
       and     $3, %eax        /* any bytes left? */
       jnz     .Ltrailing
       jmp     .Lcopy_done

Ltrailing:
       cmp     $2, %eax
       jb      1f
       movw    (%esi), %ax
       movw    %ax, (%edi)
       je      .Lcopy_done
       movb    2(%esi), %al
       movb    %al, 2(%edi)
       jmp     .Lcopy_done
1:      movb    (%esi), %al
       movb    %al, (%edi)
       jmp     .Lcopy_done

#if !defined(NO_OVERLAP)
Lbackwards:
       addl    %ecx, %edi      /* copy backwards. */
       addl    %ecx, %esi
       and     $3, %eax        /* any fractional bytes? */
       jnz     .Lback_align
Lback_aligned:
       shrl    $2, %ecx
       subl    $4, %esi
       subl    $4, %edi
       std
       rep
       movsl
       cld
       jmp     .Lcopy_done

Lback_align:
       sub     %eax, %esi
       sub     %eax, %edi
       cmp     $2, %eax
       jb      1f
       je      2f
       movb    2(%esi), %al
       movb    %al, 2(%edi)
2:      movw    (%esi), %ax
       movw    %ax, (%edi)
       jmp     .Lback_aligned
1:      movb    (%esi), %al
       movb    %al, (%edi)
       jmp     .Lback_aligned
#endif
       /* End of copy kernel */
Lcopy_done:
       cld                     /* LynxOS depends on it */

       /* Prepare jump address */
       lea     (start32a - start)(%edx), %eax
       movl    %eax, (start32r - start)(%edx)

       /* Setup GDT */
       lea     (gdt - start)(%edx), %eax
       movl    %eax, (gdtrr - start)(%edx)
       lgdt    (gdtr - start)(%edx)

       /* Jump to set %cs */
       ljmp    *(start32r - start)(%edx)

       .align  4
start32a:
       movl    $DATA_SEGMENT, %eax
       movw    %ax, %ds
       movw    %ax, %es
       movw    %ax, %fs
       movw    %ax, %gs
       movw    %ax, %ss

       /* Already set new stack pointer */
       movl    %esp, %ebp

       /* Disable Paging in CR0 */
       movl    %cr0, %eax
       andl    $(~CR0_PG), %eax
       movl    %eax, %cr0

       /* Disable PAE in CR4 */
       movl    %cr4, %eax
       andl    $(~CR4_PAE), %eax
       movl    %eax, %cr4

       jmp     start32b

       .align  4
start32b:
       xor     %eax, %eax
       movl    %ebx, (start32r - start)(%edx)
       ljmp    *(start32r - start)(%edx)

       .align  16
start32r:
       .long   0
       .long   CODE_SEGMENT
       .align  16
gdt:
       .long   0, 0
       .byte   0xff, 0xff, 0x00, 0x00, 0x00, 0x9f, 0xcf, 0x00
       .byte   0xff, 0xff, 0x00, 0x00, 0x00, 0x93, 0xcf, 0x00
gdtr:
       .word   gdtr - gdt
gdtrr:
       .quad
start32end:
       /* Space for the stack */
       .align  16
       .space  8192
startprog32_end:

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