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1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2/******************************************************************************
3 *
4 * Module Name: tbxfroot - Find the root ACPI table (RSDT)
5 *
6 * Copyright (C) 2000 - 2023, Intel Corp.
7 *
8 *****************************************************************************/
9
10#include <acpi/acpi.h>
11#include "accommon.h"
12#include "actables.h"
13
14#define _COMPONENT ACPI_TABLES
15ACPI_MODULE_NAME("tbxfroot")
16
17/*******************************************************************************
18 *
19 * FUNCTION: acpi_tb_get_rsdp_length
20 *
21 * PARAMETERS: rsdp - Pointer to RSDP
22 *
23 * RETURN: Table length
24 *
25 * DESCRIPTION: Get the length of the RSDP
26 *
27 ******************************************************************************/
28u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp)
29{
30
31 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
32
33 /* BAD Signature */
34
35 return (0);
36 }
37
38 /* "Length" field is available if table version >= 2 */
39
40 if (rsdp->revision >= 2) {
41 return (rsdp->length);
42 } else {
43 return (ACPI_RSDP_CHECKSUM_LENGTH);
44 }
45}
46
47/*******************************************************************************
48 *
49 * FUNCTION: acpi_tb_validate_rsdp
50 *
51 * PARAMETERS: rsdp - Pointer to unvalidated RSDP
52 *
53 * RETURN: Status
54 *
55 * DESCRIPTION: Validate the RSDP (ptr)
56 *
57 ******************************************************************************/
58
59acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
60{
61
62 /*
63 * The signature and checksum must both be correct
64 *
65 * Note: Sometimes there exists more than one RSDP in memory; the valid
66 * RSDP has a valid checksum, all others have an invalid checksum.
67 */
68 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
69
70 /* Nope, BAD Signature */
71
72 return (AE_BAD_SIGNATURE);
73 }
74
75 /* Check the standard checksum */
76
77 if (acpi_ut_checksum((u8 *)rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
78 return (AE_BAD_CHECKSUM);
79 }
80
81 /* Check extended checksum if table version >= 2 */
82
83 if ((rsdp->revision >= 2) &&
84 (acpi_ut_checksum((u8 *)rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
85 return (AE_BAD_CHECKSUM);
86 }
87
88 return (AE_OK);
89}
90
91/*******************************************************************************
92 *
93 * FUNCTION: acpi_find_root_pointer
94 *
95 * PARAMETERS: table_address - Where the table pointer is returned
96 *
97 * RETURN: Status, RSDP physical address
98 *
99 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
100 * pointer structure. If it is found, set *RSDP to point to it.
101 *
102 * NOTE1: The RSDP must be either in the first 1K of the Extended
103 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
104 * Only a 32-bit physical address is necessary.
105 *
106 * NOTE2: This function is always available, regardless of the
107 * initialization state of the rest of ACPI.
108 *
109 ******************************************************************************/
110
111acpi_status ACPI_INIT_FUNCTION
112acpi_find_root_pointer(acpi_physical_address *table_address)
113{
114 u8 *table_ptr;
115 u8 *mem_rover;
116 u32 physical_address;
117 u32 ebda_window_size;
118
119 ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
120
121 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
122
123 table_ptr = acpi_os_map_memory((acpi_physical_address)
124 ACPI_EBDA_PTR_LOCATION,
125 ACPI_EBDA_PTR_LENGTH);
126 if (!table_ptr) {
127 ACPI_ERROR((AE_INFO,
128 "Could not map memory at 0x%8.8X for length %u",
129 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
130
131 return_ACPI_STATUS(AE_NO_MEMORY);
132 }
133
134 ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
135
136 /* Convert segment part to physical address */
137
138 physical_address <<= 4;
139 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
140
141 /* EBDA present? */
142
143 /*
144 * Check that the EBDA pointer from memory is sane and does not point
145 * above valid low memory
146 */
147 if (physical_address > 0x400 && physical_address < 0xA0000) {
148 /*
149 * Calculate the scan window size
150 * The EBDA is not guaranteed to be larger than a ki_b and in case
151 * that it is smaller, the scanning function would leave the low
152 * memory and continue to the VGA range.
153 */
154 ebda_window_size = ACPI_MIN(ACPI_EBDA_WINDOW_SIZE,
155 0xA0000 - physical_address);
156
157 /*
158 * 1b) Search EBDA paragraphs
159 */
160 table_ptr = acpi_os_map_memory((acpi_physical_address)
161 physical_address,
162 ebda_window_size);
163 if (!table_ptr) {
164 ACPI_ERROR((AE_INFO,
165 "Could not map memory at 0x%8.8X for length %u",
166 physical_address, ebda_window_size));
167
168 return_ACPI_STATUS(AE_NO_MEMORY);
169 }
170
171 mem_rover =
172 acpi_tb_scan_memory_for_rsdp(table_ptr, ebda_window_size);
173 acpi_os_unmap_memory(table_ptr, ebda_window_size);
174
175 if (mem_rover) {
176
177 /* Return the physical address */
178
179 physical_address +=
180 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
181
182 *table_address =
183 (acpi_physical_address)physical_address;
184 return_ACPI_STATUS(AE_OK);
185 }
186 }
187
188 /*
189 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
190 */
191 table_ptr = acpi_os_map_memory((acpi_physical_address)
192 ACPI_HI_RSDP_WINDOW_BASE,
193 ACPI_HI_RSDP_WINDOW_SIZE);
194
195 if (!table_ptr) {
196 ACPI_ERROR((AE_INFO,
197 "Could not map memory at 0x%8.8X for length %u",
198 ACPI_HI_RSDP_WINDOW_BASE,
199 ACPI_HI_RSDP_WINDOW_SIZE));
200
201 return_ACPI_STATUS(AE_NO_MEMORY);
202 }
203
204 mem_rover =
205 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
206 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
207
208 if (mem_rover) {
209
210 /* Return the physical address */
211
212 physical_address = (u32)
213 (ACPI_HI_RSDP_WINDOW_BASE +
214 ACPI_PTR_DIFF(mem_rover, table_ptr));
215
216 *table_address = (acpi_physical_address)physical_address;
217 return_ACPI_STATUS(AE_OK);
218 }
219
220 /* A valid RSDP was not found */
221
222 ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found"));
223 return_ACPI_STATUS(AE_NOT_FOUND);
224}
225
226ACPI_EXPORT_SYMBOL_INIT(acpi_find_root_pointer)
227
228/*******************************************************************************
229 *
230 * FUNCTION: acpi_tb_scan_memory_for_rsdp
231 *
232 * PARAMETERS: start_address - Starting pointer for search
233 * length - Maximum length to search
234 *
235 * RETURN: Pointer to the RSDP if found, otherwise NULL.
236 *
237 * DESCRIPTION: Search a block of memory for the RSDP signature
238 *
239 ******************************************************************************/
240u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length)
241{
242 acpi_status status;
243 u8 *mem_rover;
244 u8 *end_address;
245
246 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
247
248 end_address = start_address + length;
249
250 /* Search from given start address for the requested length */
251
252 for (mem_rover = start_address; mem_rover < end_address;
253 mem_rover += ACPI_RSDP_SCAN_STEP) {
254
255 /* The RSDP signature and checksum must both be correct */
256
257 status =
258 acpi_tb_validate_rsdp(ACPI_CAST_PTR
259 (struct acpi_table_rsdp, mem_rover));
260 if (ACPI_SUCCESS(status)) {
261
262 /* Sig and checksum valid, we have found a real RSDP */
263
264 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
265 "RSDP located at physical address %p\n",
266 mem_rover));
267 return_PTR(mem_rover);
268 }
269
270 /* No sig match or bad checksum, keep searching */
271 }
272
273 /* Searched entire block, no RSDP was found */
274
275 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
276 "Searched entire block from %p, valid RSDP was not found\n",
277 start_address));
278 return_PTR(NULL);
279}
1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2/******************************************************************************
3 *
4 * Module Name: tbxfroot - Find the root ACPI table (RSDT)
5 *
6 * Copyright (C) 2000 - 2022, Intel Corp.
7 *
8 *****************************************************************************/
9
10#include <acpi/acpi.h>
11#include "accommon.h"
12#include "actables.h"
13
14#define _COMPONENT ACPI_TABLES
15ACPI_MODULE_NAME("tbxfroot")
16
17/*******************************************************************************
18 *
19 * FUNCTION: acpi_tb_get_rsdp_length
20 *
21 * PARAMETERS: rsdp - Pointer to RSDP
22 *
23 * RETURN: Table length
24 *
25 * DESCRIPTION: Get the length of the RSDP
26 *
27 ******************************************************************************/
28u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp)
29{
30
31 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
32
33 /* BAD Signature */
34
35 return (0);
36 }
37
38 /* "Length" field is available if table version >= 2 */
39
40 if (rsdp->revision >= 2) {
41 return (rsdp->length);
42 } else {
43 return (ACPI_RSDP_CHECKSUM_LENGTH);
44 }
45}
46
47/*******************************************************************************
48 *
49 * FUNCTION: acpi_tb_validate_rsdp
50 *
51 * PARAMETERS: rsdp - Pointer to unvalidated RSDP
52 *
53 * RETURN: Status
54 *
55 * DESCRIPTION: Validate the RSDP (ptr)
56 *
57 ******************************************************************************/
58
59acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
60{
61
62 /*
63 * The signature and checksum must both be correct
64 *
65 * Note: Sometimes there exists more than one RSDP in memory; the valid
66 * RSDP has a valid checksum, all others have an invalid checksum.
67 */
68 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
69
70 /* Nope, BAD Signature */
71
72 return (AE_BAD_SIGNATURE);
73 }
74
75 /* Check the standard checksum */
76
77 if (acpi_ut_checksum((u8 *)rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
78 return (AE_BAD_CHECKSUM);
79 }
80
81 /* Check extended checksum if table version >= 2 */
82
83 if ((rsdp->revision >= 2) &&
84 (acpi_ut_checksum((u8 *)rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
85 return (AE_BAD_CHECKSUM);
86 }
87
88 return (AE_OK);
89}
90
91/*******************************************************************************
92 *
93 * FUNCTION: acpi_find_root_pointer
94 *
95 * PARAMETERS: table_address - Where the table pointer is returned
96 *
97 * RETURN: Status, RSDP physical address
98 *
99 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
100 * pointer structure. If it is found, set *RSDP to point to it.
101 *
102 * NOTE1: The RSDP must be either in the first 1K of the Extended
103 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
104 * Only a 32-bit physical address is necessary.
105 *
106 * NOTE2: This function is always available, regardless of the
107 * initialization state of the rest of ACPI.
108 *
109 ******************************************************************************/
110
111acpi_status ACPI_INIT_FUNCTION
112acpi_find_root_pointer(acpi_physical_address *table_address)
113{
114 u8 *table_ptr;
115 u8 *mem_rover;
116 u32 physical_address;
117 u32 ebda_window_size;
118
119 ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
120
121 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
122
123 table_ptr = acpi_os_map_memory((acpi_physical_address)
124 ACPI_EBDA_PTR_LOCATION,
125 ACPI_EBDA_PTR_LENGTH);
126 if (!table_ptr) {
127 ACPI_ERROR((AE_INFO,
128 "Could not map memory at 0x%8.8X for length %u",
129 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
130
131 return_ACPI_STATUS(AE_NO_MEMORY);
132 }
133
134 ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
135
136 /* Convert segment part to physical address */
137
138 physical_address <<= 4;
139 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
140
141 /* EBDA present? */
142
143 /*
144 * Check that the EBDA pointer from memory is sane and does not point
145 * above valid low memory
146 */
147 if (physical_address > 0x400 && physical_address < 0xA0000) {
148 /*
149 * Calculate the scan window size
150 * The EBDA is not guaranteed to be larger than a ki_b and in case
151 * that it is smaller, the scanning function would leave the low
152 * memory and continue to the VGA range.
153 */
154 ebda_window_size = ACPI_MIN(ACPI_EBDA_WINDOW_SIZE,
155 0xA0000 - physical_address);
156
157 /*
158 * 1b) Search EBDA paragraphs
159 */
160 table_ptr = acpi_os_map_memory((acpi_physical_address)
161 physical_address,
162 ebda_window_size);
163 if (!table_ptr) {
164 ACPI_ERROR((AE_INFO,
165 "Could not map memory at 0x%8.8X for length %u",
166 physical_address, ebda_window_size));
167
168 return_ACPI_STATUS(AE_NO_MEMORY);
169 }
170
171 mem_rover =
172 acpi_tb_scan_memory_for_rsdp(table_ptr, ebda_window_size);
173 acpi_os_unmap_memory(table_ptr, ebda_window_size);
174
175 if (mem_rover) {
176
177 /* Return the physical address */
178
179 physical_address +=
180 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
181
182 *table_address =
183 (acpi_physical_address)physical_address;
184 return_ACPI_STATUS(AE_OK);
185 }
186 }
187
188 /*
189 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
190 */
191 table_ptr = acpi_os_map_memory((acpi_physical_address)
192 ACPI_HI_RSDP_WINDOW_BASE,
193 ACPI_HI_RSDP_WINDOW_SIZE);
194
195 if (!table_ptr) {
196 ACPI_ERROR((AE_INFO,
197 "Could not map memory at 0x%8.8X for length %u",
198 ACPI_HI_RSDP_WINDOW_BASE,
199 ACPI_HI_RSDP_WINDOW_SIZE));
200
201 return_ACPI_STATUS(AE_NO_MEMORY);
202 }
203
204 mem_rover =
205 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
206 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
207
208 if (mem_rover) {
209
210 /* Return the physical address */
211
212 physical_address = (u32)
213 (ACPI_HI_RSDP_WINDOW_BASE +
214 ACPI_PTR_DIFF(mem_rover, table_ptr));
215
216 *table_address = (acpi_physical_address)physical_address;
217 return_ACPI_STATUS(AE_OK);
218 }
219
220 /* A valid RSDP was not found */
221
222 ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found"));
223 return_ACPI_STATUS(AE_NOT_FOUND);
224}
225
226ACPI_EXPORT_SYMBOL_INIT(acpi_find_root_pointer)
227
228/*******************************************************************************
229 *
230 * FUNCTION: acpi_tb_scan_memory_for_rsdp
231 *
232 * PARAMETERS: start_address - Starting pointer for search
233 * length - Maximum length to search
234 *
235 * RETURN: Pointer to the RSDP if found, otherwise NULL.
236 *
237 * DESCRIPTION: Search a block of memory for the RSDP signature
238 *
239 ******************************************************************************/
240u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length)
241{
242 acpi_status status;
243 u8 *mem_rover;
244 u8 *end_address;
245
246 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
247
248 end_address = start_address + length;
249
250 /* Search from given start address for the requested length */
251
252 for (mem_rover = start_address; mem_rover < end_address;
253 mem_rover += ACPI_RSDP_SCAN_STEP) {
254
255 /* The RSDP signature and checksum must both be correct */
256
257 status =
258 acpi_tb_validate_rsdp(ACPI_CAST_PTR
259 (struct acpi_table_rsdp, mem_rover));
260 if (ACPI_SUCCESS(status)) {
261
262 /* Sig and checksum valid, we have found a real RSDP */
263
264 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
265 "RSDP located at physical address %p\n",
266 mem_rover));
267 return_PTR(mem_rover);
268 }
269
270 /* No sig match or bad checksum, keep searching */
271 }
272
273 /* Searched entire block, no RSDP was found */
274
275 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
276 "Searched entire block from %p, valid RSDP was not found\n",
277 start_address));
278 return_PTR(NULL);
279}