1 /*- 2 * Copyright 2015 Toomas Soome <tsoome@me.com> 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 * Chain loader to load BIOS boot block either from MBR or PBR. 29 * 30 * Note the boot block location 0000:7c000 conflicts with loader, so we need to 31 * read in to temporary space and relocate on exec, when btx is stopped. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include <stand.h> 38 #include <sys/param.h> 39 #include <sys/linker.h> 40 #include <sys/diskmbr.h> 41 42 #include "bootstrap.h" 43 #include "libi386/libi386.h" 44 #include "btxv86.h" 45 46 /* 47 * The MBR/VBR is located in first sector of disk/partition. 48 * Read 512B to temporary location and set up relocation. Then 49 * exec relocator. 50 */ 51 #define SECTOR_SIZE (512) 52 53 COMMAND_SET(chain, "chain", "chain load boot block from device", command_chain); 54 55 static int 56 command_chain(int argc, char *argv[]) 57 { 58 int fd, len, size = SECTOR_SIZE; 59 struct stat st; 60 vm_offset_t mem = 0x100000; 61 struct i386_devdesc *rootdev; 62 63 if (argc == 1) { 64 command_errmsg = "no device or file name specified"; 65 return (CMD_ERROR); 66 } 67 if (argc != 2) { 68 command_errmsg = "invalid trailing arguments"; 69 return (CMD_ERROR); 70 } 71 72 fd = open(argv[1], O_RDONLY); 73 if (fd == -1) { 74 command_errmsg = "open failed"; 75 return (CMD_ERROR); 76 } 77 78 len = strlen(argv[1]); 79 if (argv[1][len-1] != ':') { 80 if (fstat(fd, &st) == -1) { 81 command_errmsg = "stat failed"; 82 close(fd); 83 return (CMD_ERROR); 84 } 85 size = st.st_size; 86 } else if (strncmp(argv[1], "disk", 4) != 0) { 87 command_errmsg = "can only use disk device"; 88 close(fd); 89 return (CMD_ERROR); 90 } 91 92 i386_getdev((void **)(&rootdev), argv[1], NULL); 93 if (rootdev == NULL) { 94 command_errmsg = "can't determine root device"; 95 close(fd); 96 return (CMD_ERROR); 97 } 98 99 if (archsw.arch_readin(fd, mem, size) != size) { 100 command_errmsg = "failed to read disk"; 101 close(fd); 102 return (CMD_ERROR); 103 } 104 close(fd); 105 106 if (argv[1][len-1] == ':' && 107 *((uint16_t *)PTOV(mem + DOSMAGICOFFSET)) != DOSMAGIC) { 108 command_errmsg = "wrong magic"; 109 return (CMD_ERROR); 110 } 111 112 relocater_data[0].src = mem; 113 relocater_data[0].dest = 0x7C00; 114 relocater_data[0].size = size; 115 116 relocator_edx = bd_unit2bios(rootdev); 117 relocator_esi = relocater_size; 118 relocator_ds = 0; 119 relocator_es = 0; 120 relocator_fs = 0; 121 relocator_gs = 0; 122 relocator_ss = 0; 123 relocator_cs = 0; 124 relocator_sp = 0x7C00; 125 relocator_ip = 0x7C00; 126 relocator_a20_enabled = 0; 127 128 i386_copyin(relocater, 0x600, relocater_size); 129 130 dev_cleanup(); 131 132 __exec((void *)0x600); 133 134 panic("exec returned"); 135 return (CMD_ERROR); /* not reached */ 136 } 137