1 /* $NetBSD: db_memrw.c,v 1.21 2001/09/05 13:21:09 tsutsui Exp $ */ 2 3 /*- 4 * Copyright (c) 1996 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Gordon W. Ross and Jeremy Cooper. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Interface to the debugger for virtual memory read/write. 41 * This file is shared by DDB and KGDB, and must work even 42 * when only KGDB is included (thus no db_printf calls). 43 * 44 * To write in the text segment, we have to first make 45 * the page writable, do the write, then restore the PTE. 46 * For writes outside the text segment, and all reads, 47 * just do the access -- if it causes a fault, the debugger 48 * will recover with a longjmp to an appropriate place. 49 * 50 * ALERT! If you want to access device registers with a 51 * specific size, then the read/write functions have to 52 * make sure to do the correct sized pointer access. 53 */ 54 55 #include <sys/param.h> 56 #include <sys/systm.h> 57 #include <sys/proc.h> 58 59 #include <uvm/uvm_extern.h> 60 61 #include <machine/db_machdep.h> 62 #include <machine/pte.h> 63 64 #include <sun3/sun3/machdep.h> 65 66 #include <ddb/db_access.h> 67 68 extern char etext[]; /* defined by the linker */ 69 extern char kernel_text[]; /* locore.s */ 70 71 static void db_write_text __P((char *, size_t size, char *)); 72 73 74 /* 75 * Read bytes from kernel address space for debugger. 76 * This used to check for valid PTEs, but now that 77 * traps in DDB work correctly, "Just Do It!" 78 */ 79 void 80 db_read_bytes(addr, size, data) 81 db_addr_t addr; 82 size_t size; 83 char *data; 84 { 85 char *src = (char*)addr; 86 87 if (size == 4) { 88 *((int*)data) = *((int*)src); 89 return; 90 } 91 92 if (size == 2) { 93 *((short*)data) = *((short*)src); 94 return; 95 } 96 97 while (size > 0) { 98 --size; 99 *data++ = *src++; 100 } 101 } 102 103 /* 104 * Write bytes somewhere in kernel text. 105 * Makes text page writable temporarily. 106 */ 107 static void 108 db_write_text(dst, size, data) 109 char *dst; 110 size_t size; 111 char *data; 112 { 113 int oldpte, tmppte; 114 vaddr_t pgva, prevpg; 115 116 /* Prevent restoring a garbage PTE. */ 117 if (size <= 0) 118 return; 119 120 pgva = m68k_trunc_page((long)dst); 121 122 goto firstpage; 123 do { 124 125 /* 126 * If we are on a new page, restore the PTE 127 * for the previous page, and make the new 128 * page writable. 129 */ 130 pgva = m68k_trunc_page((long)dst); 131 if (pgva != prevpg) { 132 /* 133 * Restore old PTE. No cache flush, 134 * because the tmp PTE has no-cache. 135 */ 136 set_pte(prevpg, oldpte); 137 138 firstpage: 139 /* 140 * Flush the VAC to prevent a cache hit 141 * on the old, read-only PTE. 142 */ 143 #ifdef HAVECACHE 144 if (cache_size) 145 cache_flush_page(pgva); 146 #endif 147 oldpte = get_pte(pgva); 148 if ((oldpte & PG_VALID) == 0) { 149 printf(" address %p not a valid page\n", dst); 150 return; 151 } 152 153 /* 154 * Make the pte writable and non-cached. 155 */ 156 tmppte = oldpte; 157 #ifdef _SUN3_ 158 tmppte |= (PG_WRITE | PG_NC); 159 #endif 160 #ifdef _SUN3X_ 161 tmppte &= ~MMU_SHORT_PTE_WP; 162 tmppte |= MMU_SHORT_PTE_CI; 163 #endif 164 165 set_pte(pgva, tmppte); 166 prevpg = pgva; 167 } 168 169 /* Now we can write in this page of kernel text... */ 170 *dst++ = *data++; 171 172 } while (--size > 0); 173 174 /* Restore old PTE for the last page touched. */ 175 set_pte(prevpg, oldpte); 176 177 /* Finally, clear the instruction cache. */ 178 ICIA(); 179 } 180 181 /* 182 * Write bytes to kernel address space for debugger. 183 */ 184 void 185 db_write_bytes(addr, size, data) 186 db_addr_t addr; 187 size_t size; 188 char *data; 189 { 190 char *dst = (char *)addr; 191 192 /* If any part is in kernel text, use db_write_text() */ 193 if ((dst < etext) && ((dst + size) > kernel_text)) { 194 db_write_text(dst, size, data); 195 return; 196 } 197 198 if (size == 4) { 199 *((int*)dst) = *((int*)data); 200 return; 201 } 202 203 if (size == 2) { 204 *((short*)dst) = *((short*)data); 205 return; 206 } 207 208 while (size > 0) { 209 --size; 210 *dst++ = *data++; 211 } 212 } 213 214