1 /****************************************************************************** 2 * 3 * Module Name: tbxfroot - Find the root ACPI table (RSDT) 4 * 5 *****************************************************************************/ 6 7 /* 8 * Copyright (C) 2000 - 2017, Intel Corp. 9 * All rights reserved. 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 * without modification. 17 * 2. Redistributions in binary form must reproduce at minimum a disclaimer 18 * substantially similar to the "NO WARRANTY" disclaimer below 19 * ("Disclaimer") and any redistribution must be conditioned upon 20 * including a substantially similar Disclaimer requirement for further 21 * binary redistribution. 22 * 3. Neither the names of the above-listed copyright holders nor the names 23 * of any contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * Alternatively, this software may be distributed under the terms of the 27 * GNU General Public License ("GPL") version 2 as published by the Free 28 * Software Foundation. 29 * 30 * NO WARRANTY 31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR 34 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 35 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 40 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 41 * POSSIBILITY OF SUCH DAMAGES. 42 */ 43 44 #include <acpi/acpi.h> 45 #include "accommon.h" 46 #include "actables.h" 47 48 #define _COMPONENT ACPI_TABLES 49 ACPI_MODULE_NAME("tbxfroot") 50 51 /******************************************************************************* 52 * 53 * FUNCTION: acpi_tb_get_rsdp_length 54 * 55 * PARAMETERS: rsdp - Pointer to RSDP 56 * 57 * RETURN: Table length 58 * 59 * DESCRIPTION: Get the length of the RSDP 60 * 61 ******************************************************************************/ 62 u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp) 63 { 64 65 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { 66 67 /* BAD Signature */ 68 69 return (0); 70 } 71 72 /* "Length" field is available if table version >= 2 */ 73 74 if (rsdp->revision >= 2) { 75 return (rsdp->length); 76 } else { 77 return (ACPI_RSDP_CHECKSUM_LENGTH); 78 } 79 } 80 81 /******************************************************************************* 82 * 83 * FUNCTION: acpi_tb_validate_rsdp 84 * 85 * PARAMETERS: rsdp - Pointer to unvalidated RSDP 86 * 87 * RETURN: Status 88 * 89 * DESCRIPTION: Validate the RSDP (ptr) 90 * 91 ******************************************************************************/ 92 93 acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp) 94 { 95 96 /* 97 * The signature and checksum must both be correct 98 * 99 * Note: Sometimes there exists more than one RSDP in memory; the valid 100 * RSDP has a valid checksum, all others have an invalid checksum. 101 */ 102 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { 103 104 /* Nope, BAD Signature */ 105 106 return (AE_BAD_SIGNATURE); 107 } 108 109 /* Check the standard checksum */ 110 111 if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) { 112 return (AE_BAD_CHECKSUM); 113 } 114 115 /* Check extended checksum if table version >= 2 */ 116 117 if ((rsdp->revision >= 2) && 118 (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) { 119 return (AE_BAD_CHECKSUM); 120 } 121 122 return (AE_OK); 123 } 124 125 /******************************************************************************* 126 * 127 * FUNCTION: acpi_find_root_pointer 128 * 129 * PARAMETERS: table_address - Where the table pointer is returned 130 * 131 * RETURN: Status, RSDP physical address 132 * 133 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor 134 * pointer structure. If it is found, set *RSDP to point to it. 135 * 136 * NOTE1: The RSDP must be either in the first 1K of the Extended 137 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) 138 * Only a 32-bit physical address is necessary. 139 * 140 * NOTE2: This function is always available, regardless of the 141 * initialization state of the rest of ACPI. 142 * 143 ******************************************************************************/ 144 145 acpi_status ACPI_INIT_FUNCTION 146 acpi_find_root_pointer(acpi_physical_address *table_address) 147 { 148 u8 *table_ptr; 149 u8 *mem_rover; 150 u32 physical_address; 151 152 ACPI_FUNCTION_TRACE(acpi_find_root_pointer); 153 154 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ 155 156 table_ptr = acpi_os_map_memory((acpi_physical_address) 157 ACPI_EBDA_PTR_LOCATION, 158 ACPI_EBDA_PTR_LENGTH); 159 if (!table_ptr) { 160 ACPI_ERROR((AE_INFO, 161 "Could not map memory at 0x%8.8X for length %u", 162 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); 163 164 return_ACPI_STATUS(AE_NO_MEMORY); 165 } 166 167 ACPI_MOVE_16_TO_32(&physical_address, table_ptr); 168 169 /* Convert segment part to physical address */ 170 171 physical_address <<= 4; 172 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH); 173 174 /* EBDA present? */ 175 176 if (physical_address > 0x400) { 177 /* 178 * 1b) Search EBDA paragraphs (EBDA is required to be a 179 * minimum of 1K length) 180 */ 181 table_ptr = acpi_os_map_memory((acpi_physical_address) 182 physical_address, 183 ACPI_EBDA_WINDOW_SIZE); 184 if (!table_ptr) { 185 ACPI_ERROR((AE_INFO, 186 "Could not map memory at 0x%8.8X for length %u", 187 physical_address, ACPI_EBDA_WINDOW_SIZE)); 188 189 return_ACPI_STATUS(AE_NO_MEMORY); 190 } 191 192 mem_rover = 193 acpi_tb_scan_memory_for_rsdp(table_ptr, 194 ACPI_EBDA_WINDOW_SIZE); 195 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE); 196 197 if (mem_rover) { 198 199 /* Return the physical address */ 200 201 physical_address += 202 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr); 203 204 *table_address = 205 (acpi_physical_address)physical_address; 206 return_ACPI_STATUS(AE_OK); 207 } 208 } 209 210 /* 211 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh 212 */ 213 table_ptr = acpi_os_map_memory((acpi_physical_address) 214 ACPI_HI_RSDP_WINDOW_BASE, 215 ACPI_HI_RSDP_WINDOW_SIZE); 216 217 if (!table_ptr) { 218 ACPI_ERROR((AE_INFO, 219 "Could not map memory at 0x%8.8X for length %u", 220 ACPI_HI_RSDP_WINDOW_BASE, 221 ACPI_HI_RSDP_WINDOW_SIZE)); 222 223 return_ACPI_STATUS(AE_NO_MEMORY); 224 } 225 226 mem_rover = 227 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); 228 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); 229 230 if (mem_rover) { 231 232 /* Return the physical address */ 233 234 physical_address = (u32) 235 (ACPI_HI_RSDP_WINDOW_BASE + 236 ACPI_PTR_DIFF(mem_rover, table_ptr)); 237 238 *table_address = (acpi_physical_address)physical_address; 239 return_ACPI_STATUS(AE_OK); 240 } 241 242 /* A valid RSDP was not found */ 243 244 ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found")); 245 return_ACPI_STATUS(AE_NOT_FOUND); 246 } 247 248 ACPI_EXPORT_SYMBOL_INIT(acpi_find_root_pointer) 249 250 /******************************************************************************* 251 * 252 * FUNCTION: acpi_tb_scan_memory_for_rsdp 253 * 254 * PARAMETERS: start_address - Starting pointer for search 255 * length - Maximum length to search 256 * 257 * RETURN: Pointer to the RSDP if found, otherwise NULL. 258 * 259 * DESCRIPTION: Search a block of memory for the RSDP signature 260 * 261 ******************************************************************************/ 262 u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length) 263 { 264 acpi_status status; 265 u8 *mem_rover; 266 u8 *end_address; 267 268 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp); 269 270 end_address = start_address + length; 271 272 /* Search from given start address for the requested length */ 273 274 for (mem_rover = start_address; mem_rover < end_address; 275 mem_rover += ACPI_RSDP_SCAN_STEP) { 276 277 /* The RSDP signature and checksum must both be correct */ 278 279 status = 280 acpi_tb_validate_rsdp(ACPI_CAST_PTR 281 (struct acpi_table_rsdp, mem_rover)); 282 if (ACPI_SUCCESS(status)) { 283 284 /* Sig and checksum valid, we have found a real RSDP */ 285 286 ACPI_DEBUG_PRINT((ACPI_DB_INFO, 287 "RSDP located at physical address %p\n", 288 mem_rover)); 289 return_PTR(mem_rover); 290 } 291 292 /* No sig match or bad checksum, keep searching */ 293 } 294 295 /* Searched entire block, no RSDP was found */ 296 297 ACPI_DEBUG_PRINT((ACPI_DB_INFO, 298 "Searched entire block from %p, valid RSDP was not found\n", 299 start_address)); 300 return_PTR(NULL); 301 } 302