1/* $OpenBSD: db_memrw.c,v 1.9 2024/02/23 18:19:02 cheloha Exp $ */ 2/* $NetBSD: db_memrw.c,v 1.1 2003/04/26 18:39:27 fvdl Exp $ */ 3 4/*- 5 * Copyright (c) 1996, 2000 The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Gordon W. Ross and Jason R. Thorpe. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33/* 34 * Interface to the debugger for virtual memory read/write. 35 * 36 * To write in the text segment, we have to first make 37 * the page writable, do the write, then restore the PTE. 38 * For writes outside the text segment, and all reads, 39 * just do the access -- if it causes a fault, the debugger 40 * will recover with a longjmp to an appropriate place. 41 * 42 * ALERT! If you want to access device registers with a 43 * specific size, then the read/write functions have to 44 * make sure to do the correct sized pointer access. 45 * 46 * Modified for i386 from hp300 version by 47 * Jason R. Thorpe <thorpej@zembu.com>. 48 * 49 * Basic copy to amd64 by fvdl. 50 */ 51 52#include <sys/param.h> 53#include <sys/systm.h> 54 55#include <uvm/uvm_extern.h> 56 57#include <machine/db_machdep.h> 58 59/* 60 * Read bytes from kernel address space for debugger. 61 */ 62void 63db_read_bytes(vaddr_t addr, size_t size, void *datap) 64{ 65 char *data = datap, *src; 66 67 src = (char *)addr; 68 69 if (size == 8) { 70 *((long *)data) = *((long *)src); 71 return; 72 } 73 74 if (size == 4) { 75 *((int *)data) = *((int *)src); 76 return; 77 } 78 79 if (size == 2) { 80 *((short *)data) = *((short *)src); 81 return; 82 } 83 84 while (size-- > 0) 85 *data++ = *src++; 86} 87 88/* 89 * Write bytes somewhere in the kernel text. Make the text 90 * pages writable temporarily. 91 */ 92static void 93db_write_text(vaddr_t addr, size_t size, char *data) 94{ 95 pt_entry_t *pte, oldpte, tmppte; 96 vaddr_t pgva; 97 size_t limit; 98 char *dst; 99 100 if (size == 0) 101 return; 102 103 dst = (char *)addr; 104 105 do { 106 /* 107 * Get the PTE for the page. 108 */ 109 pte = kvtopte(addr); 110 oldpte = *pte; 111 112 if ((oldpte & PG_V) == 0) { 113 printf(" address %p not a valid page\n", dst); 114 return; 115 } 116 117 /* 118 * Get the VA for the page. 119 */ 120 if (oldpte & PG_PS) 121 pgva = (vaddr_t)dst & PG_LGFRAME; 122 else 123 pgva = trunc_page((vaddr_t)dst); 124 125 /* 126 * Compute number of bytes that can be written 127 * with this mapping and subtract it from the 128 * total size. 129 */ 130 if (oldpte & PG_PS) 131 limit = NBPD_L2 - ((vaddr_t)dst & (NBPD_L2 - 1)); 132 else 133 limit = PAGE_SIZE - ((vaddr_t)dst & PGOFSET); 134 if (limit > size) 135 limit = size; 136 size -= limit; 137 138 tmppte = (oldpte & ~PG_KR) | PG_KW; 139 *pte = tmppte; 140 pmap_update_pg(pgva); 141 142 /* 143 * Page is now writable. Do as much access as we 144 * can in this page. 145 */ 146 for (; limit > 0; limit--) 147 *dst++ = *data++; 148 149 /* 150 * Restore the old PTE. 151 */ 152 *pte = oldpte; 153 154 pmap_update_pg(pgva); 155 156 } while (size != 0); 157} 158 159/* 160 * Write bytes to kernel address space for debugger. 161 */ 162void 163db_write_bytes(vaddr_t addr, size_t size, void *datap) 164{ 165 extern char etext; 166 char *data = datap, *dst; 167 168 /* If any part is in kernel text, use db_write_text() */ 169 if (addr >= KERNBASE && addr < (vaddr_t)&etext) { 170 db_write_text(addr, size, data); 171 return; 172 } 173 174 dst = (char *)addr; 175 176 if (size == 8) { 177 *((long *)dst) = *((long *)data); 178 return; 179 } 180 181 if (size == 4) { 182 *((int *)dst) = *((int *)data); 183 return; 184 } 185 186 if (size == 2) { 187 *((short *)dst) = *((short *)data); 188 return; 189 } 190 191 while (size-- > 0) 192 *dst++ = *data++; 193} 194