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 * $FreeBSD$ 27 */ 28 29/* 30 * Functions for calling x86 BIOS functions from the BSD kernel 31 */ 32 33#include <machine/asmacros.h> 34 35#include "assym.s" 36 37 .data 38 ALIGN_DATA 39bioscall_frame: .long 0 40bioscall_stack: .long 0 41 42 .text 43/* 44 * bios32(regs, offset, segment) 45 * struct bios_regs *regs; 46 * u_int offset; 47 * u_short segment; 48 */ 49ENTRY(bios32) 50 pushl %ebp 51 movl 16(%esp),%ebp 52 mov %bp,bioscall_vector+4 53 movl 12(%esp),%ebp 54 movl %ebp,bioscall_vector 55 movl 8(%esp),%ebp 56 pushl %ebx 57 pushl %esi 58 pushl %edi 59 movl 0(%ebp),%eax 60 movl 4(%ebp),%ebx 61 movl 8(%ebp),%ecx 62 movl 12(%ebp),%edx 63 movl 16(%ebp),%esi 64 movl 20(%ebp),%edi 65 pushl %ebp 66 lcall *bioscall_vector 67 popl %ebp 68 movl %eax,0(%ebp) 69 movl %ebx,4(%ebp) 70 movl %ecx,8(%ebp) 71 movl %edx,12(%ebp) 72 movl %esi,16(%ebp) 73 movl %edi,20(%ebp) 74 movl $0,%eax /* presume success */ 75 jnc 1f 76 movl $1,%eax /* nope */ 771: 78 popl %edi 79 popl %esi 80 popl %ebx 81 popl %ebp 82 ret 83 84 85/* 86 * bios16_call(regs, stack) 87 * struct bios_regs *regs; 88 * char *stack; 89 */ 90ENTRY(bios16_call) 91 pushl %ebp 92 movl %esp,%ebp 93 addl $4,%ebp /* frame pointer */ 94 movl %ebp,bioscall_frame /* ... save it */ 95 pushl %ebx 96 pushl %esi 97 pushl %edi 98/* 99 * the problem with a full 32-bit stack segment is that 16-bit code 100 * tends to do a pushf, which only pushes %sp, not %esp. This value 101 * is then popped off (into %esp) which causes a page fault because 102 * it is the wrong address. 103 * 104 * the reverse problem happens for 16-bit stack addresses; the kernel 105 * code attempts to get the address of something on the stack, and the 106 * value returned is the address relative to %ss, not %ds. 107 * 108 * we fix this by installing a temporary stack at page 0, so the 109 * addresses are always valid in both 32 bit and 16 bit modes. 110 */ 111 movl %esp,bioscall_stack /* save current stack location */ 112 movl 8(%ebp),%esp /* switch to page 0 stack */ 113 114 movl 4(%ebp),%ebp /* regs */ 115 116 movl 0(%ebp),%eax 117 movl 4(%ebp),%ebx 118 movl 8(%ebp),%ecx 119 movl 12(%ebp),%edx 120 movl 16(%ebp),%esi 121 movl 20(%ebp),%edi 122 123 pushl $BC32SEL 124 leal CNAME(bios16_jmp),%ebp 125 andl $PAGE_MASK,%ebp 126 pushl %ebp /* reload %cs and */ 127 lret /* ...continue below */ 128 .globl CNAME(bios16_jmp) 129CNAME(bios16_jmp): 130 lcallw *bioscall_vector /* 16-bit call */ 131 132 jc 1f 133 pushl $0 /* success */ 134 jmp 2f 1351: 136 pushl $1 /* failure */ 1372: 138 movl bioscall_frame,%ebp 139 140 movl 4(%ebp),%ebp /* regs */ 141 142 movl %eax,0(%ebp) 143 movl %ebx,4(%ebp) 144 movl %ecx,8(%ebp) 145 movl %edx,12(%ebp) 146 movl %esi,16(%ebp) 147 movl %edi,20(%ebp) 148 149 popl %eax /* recover return value */ 150 movl bioscall_stack,%esp /* return to normal stack */ 151 152 popl %edi 153 popl %esi 154 popl %ebx 155 popl %ebp 156 157 movl (%esp),%ecx 158 pushl %ecx /* return address */ 159 movl $KCSEL,4(%esp) 160 lret /* reload %cs on the way out */ 161