1/*- 2 * Copyright (c) 1997 Jonathan Lemon 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27/* 28 * Functions for calling x86 BIOS functions from the BSD kernel 29 */ 30 31#include <machine/asmacros.h> 32 33#include "assym.inc" 34 35 .data 36 ALIGN_DATA 37bioscall_frame: .long 0 38bioscall_stack: .long 0 39 40 .text 41/* 42 * bios32(regs, offset, segment) 43 * struct bios_regs *regs; 44 * u_int offset; 45 * u_short segment; 46 */ 47ENTRY(bios32) 48 pushl %ebp 49 movl 16(%esp),%ebp 50 mov %bp,bioscall_vector+4 51 movl 12(%esp),%ebp 52 movl %ebp,bioscall_vector 53 movl 8(%esp),%ebp 54 pushl %ebx 55 pushl %esi 56 pushl %edi 57 movl 0(%ebp),%eax 58 movl 4(%ebp),%ebx 59 movl 8(%ebp),%ecx 60 movl 12(%ebp),%edx 61 movl 16(%ebp),%esi 62 movl 20(%ebp),%edi 63 pushl %ebp 64 lcall *bioscall_vector 65 popl %ebp 66 movl %eax,0(%ebp) 67 movl %ebx,4(%ebp) 68 movl %ecx,8(%ebp) 69 movl %edx,12(%ebp) 70 movl %esi,16(%ebp) 71 movl %edi,20(%ebp) 72 movl $0,%eax /* presume success */ 73 jnc 1f 74 movl $1,%eax /* nope */ 751: 76 popl %edi 77 popl %esi 78 popl %ebx 79 popl %ebp 80 ret 81 82 83/* 84 * bios16_call(regs, stack) 85 * struct bios_regs *regs; 86 * char *stack; 87 */ 88ENTRY(bios16_call) 89 pushl %ebp 90 movl %esp,%ebp 91 addl $4,%ebp /* frame pointer */ 92 movl %ebp,bioscall_frame /* ... save it */ 93 pushl %ebx 94 pushl %esi 95 pushl %edi 96/* 97 * the problem with a full 32-bit stack segment is that 16-bit code 98 * tends to do a pushf, which only pushes %sp, not %esp. This value 99 * is then popped off (into %esp) which causes a page fault because 100 * it is the wrong address. 101 * 102 * the reverse problem happens for 16-bit stack addresses; the kernel 103 * code attempts to get the address of something on the stack, and the 104 * value returned is the address relative to %ss, not %ds. 105 * 106 * we fix this by installing a temporary stack at page 0, so the 107 * addresses are always valid in both 32 bit and 16 bit modes. 108 */ 109 movl %esp,bioscall_stack /* save current stack location */ 110 movl 8(%ebp),%esp /* switch to page 0 stack */ 111 112 movl 4(%ebp),%ebp /* regs */ 113 114 movl 0(%ebp),%eax 115 movl 4(%ebp),%ebx 116 movl 8(%ebp),%ecx 117 movl 12(%ebp),%edx 118 movl 16(%ebp),%esi 119 movl 20(%ebp),%edi 120 121 pushl $BC32SEL 122 leal CNAME(bios16_jmp),%ebp 123 andl $PAGE_MASK,%ebp 124 pushl %ebp /* reload %cs and */ 125 lret /* ...continue below */ 126 .globl CNAME(bios16_jmp) 127CNAME(bios16_jmp): 128 lcallw *bioscall_vector /* 16-bit call */ 129 130 jc 1f 131 pushl $0 /* success */ 132 jmp 2f 1331: 134 pushl $1 /* failure */ 1352: 136 movl bioscall_frame,%ebp 137 138 movl 4(%ebp),%ebp /* regs */ 139 140 movl %eax,0(%ebp) 141 movl %ebx,4(%ebp) 142 movl %ecx,8(%ebp) 143 movl %edx,12(%ebp) 144 movl %esi,16(%ebp) 145 movl %edi,20(%ebp) 146 147 popl %eax /* recover return value */ 148 movl bioscall_stack,%esp /* return to normal stack */ 149 150 popl %edi 151 popl %esi 152 popl %ebx 153 popl %ebp 154 155 movl (%esp),%ecx 156 pushl %ecx /* return address */ 157 movl $KCSEL,4(%esp) 158 lret /* reload %cs on the way out */ 159