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      1 /* $NetBSD: pnpbioscall.S,v 1.3 2018/07/14 14:29:40 maxv Exp $ */
      2 /*
      3  * Copyright (c) 1999
      4  * 	Matthias Drochner.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions, and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include <machine/asm.h>
     29 __KERNEL_RCSID(0, "$NetBSD: pnpbioscall.S,v 1.3 2018/07/14 14:29:40 maxv Exp $");
     30 
     31 #include "assym.h"
     32 #include <machine/segments.h>
     33 
     34 	.data
     35 saveesp:
     36 	.space	4
     37 
     38 ENTRY(pnpbioscall)
     39 	pushl	%ebp
     40 	movl	%esp, %ebp
     41 	/*
     42 	 * disable interrupts - our handlers can't deal with frames of the
     43 	 * segment we are calling, and the BIOS can't use our IDT anyway
     44 	 */
     45 	pushfl
     46 	cli
     47 
     48 	/* call pnpbiostramp() */
     49 	lcall	$GSEL(GPNPBIOSTRAMP_SEL, SEL_KPL), $0
     50 
     51 	popfl
     52 	popl	%ebp
     53 	ret
     54 
     55 ENTRY(pnpbiostramp)
     56 	pushl	%ebx
     57 
     58 	/* save current stack pointer */
     59 	movl	%esp, %eax
     60 	movl	%eax, saveesp
     61 
     62 	/* switch to new stack */
     63 	movl	8(%ebp), %esp /* call argument */
     64 	movl	$GSEL(GPNPBIOSSCRATCH_SEL, SEL_KPL), %eax
     65 	mov	%ax, %ss
     66 
     67 	/* fake the call return address (16-bit frame) */
     68 	mov	%cs, %ax
     69 	push	%ax
     70 	movl	$(1f - _C_LABEL(pnpbiostramp)), %eax
     71 	push	%ax
     72 
     73 	/* do a long jump */
     74 	pushl	$GSEL(GPNPBIOSCODE_SEL, SEL_KPL)
     75 	pushl	(_C_LABEL(pnpbios_entry))
     76 #if 1
     77 	/* paranoia: don't pass our ds */
     78 	movl	$GSEL(GPNPBIOSSCRATCH_SEL, SEL_KPL), %eax
     79 	mov	%ax, %ds
     80 #endif
     81 	lret
     82 
     83 1:	/* returned from BIOS call */
     84 	movl	$GSEL(GDATA_SEL, SEL_KPL), %ebx
     85 #if 1
     86 	mov	%bx, %ds
     87 #endif
     88 	/* back to old stack */
     89 	mov	%bx, %ss
     90 	movl	saveesp, %ebx
     91 	movl	%ebx, %esp
     92 
     93 	popl	%ebx
     94 	lret
     95 	.globl _C_LABEL(epnpbiostramp)
     96 _C_LABEL(epnpbiostramp):
     97