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1 /******************************************************************************
2  *
3  * Module Name: tbutils   - table utilities
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2013, 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("tbutils")
50 
51 /* Local prototypes */
52 static void acpi_tb_fix_string(char *string, acpi_size length);
53 
54 static void
55 acpi_tb_cleanup_table_header(struct acpi_table_header *out_header,
56 			     struct acpi_table_header *header);
57 
58 static acpi_physical_address
59 acpi_tb_get_root_table_entry(u8 *table_entry, u32 table_entry_size);
60 
61 /*******************************************************************************
62  *
63  * FUNCTION:    acpi_tb_check_xsdt
64  *
65  * PARAMETERS:  address                    - Pointer to the XSDT
66  *
67  * RETURN:      status
68  *		AE_OK - XSDT is okay
69  *		AE_NO_MEMORY - can't map XSDT
70  *		AE_INVALID_TABLE_LENGTH - invalid table length
71  *		AE_NULL_ENTRY - XSDT has NULL entry
72  *
73  * DESCRIPTION: validate XSDT
74 ******************************************************************************/
75 
76 static acpi_status
acpi_tb_check_xsdt(acpi_physical_address address)77 acpi_tb_check_xsdt(acpi_physical_address address)
78 {
79 	struct acpi_table_header *table;
80 	u32 length;
81 	u64 xsdt_entry_address;
82 	u8 *table_entry;
83 	u32 table_count;
84 	int i;
85 
86 	table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
87 	if (!table)
88 		return AE_NO_MEMORY;
89 
90 	length = table->length;
91 	acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
92 	if (length < sizeof(struct acpi_table_header))
93 		return AE_INVALID_TABLE_LENGTH;
94 
95 	table = acpi_os_map_memory(address, length);
96 	if (!table)
97 		return AE_NO_MEMORY;
98 
99 	/* Calculate the number of tables described in XSDT */
100 	table_count =
101 		(u32) ((table->length -
102 		sizeof(struct acpi_table_header)) / sizeof(u64));
103 	table_entry =
104 		ACPI_CAST_PTR(u8, table) + sizeof(struct acpi_table_header);
105 	for (i = 0; i < table_count; i++) {
106 		ACPI_MOVE_64_TO_64(&xsdt_entry_address, table_entry);
107 		if (!xsdt_entry_address) {
108 			/* XSDT has NULL entry */
109 			break;
110 		}
111 		table_entry += sizeof(u64);
112 	}
113 	acpi_os_unmap_memory(table, length);
114 
115 	if (i < table_count)
116 		return AE_NULL_ENTRY;
117 	else
118 		return AE_OK;
119 }
120 
121 #if (!ACPI_REDUCED_HARDWARE)
122 /*******************************************************************************
123  *
124  * FUNCTION:    acpi_tb_initialize_facs
125  *
126  * PARAMETERS:  None
127  *
128  * RETURN:      Status
129  *
130  * DESCRIPTION: Create a permanent mapping for the FADT and save it in a global
131  *              for accessing the Global Lock and Firmware Waking Vector
132  *
133  ******************************************************************************/
134 
acpi_tb_initialize_facs(void)135 acpi_status acpi_tb_initialize_facs(void)
136 {
137 	acpi_status status;
138 
139 	/* If Hardware Reduced flag is set, there is no FACS */
140 
141 	if (acpi_gbl_reduced_hardware) {
142 		acpi_gbl_FACS = NULL;
143 		return (AE_OK);
144 	}
145 
146 	status = acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
147 					 ACPI_CAST_INDIRECT_PTR(struct
148 								acpi_table_header,
149 								&acpi_gbl_FACS));
150 	return (status);
151 }
152 #endif				/* !ACPI_REDUCED_HARDWARE */
153 
154 /*******************************************************************************
155  *
156  * FUNCTION:    acpi_tb_tables_loaded
157  *
158  * PARAMETERS:  None
159  *
160  * RETURN:      TRUE if required ACPI tables are loaded
161  *
162  * DESCRIPTION: Determine if the minimum required ACPI tables are present
163  *              (FADT, FACS, DSDT)
164  *
165  ******************************************************************************/
166 
acpi_tb_tables_loaded(void)167 u8 acpi_tb_tables_loaded(void)
168 {
169 
170 	if (acpi_gbl_root_table_list.current_table_count >= 3) {
171 		return (TRUE);
172 	}
173 
174 	return (FALSE);
175 }
176 
177 /*******************************************************************************
178  *
179  * FUNCTION:    acpi_tb_fix_string
180  *
181  * PARAMETERS:  string              - String to be repaired
182  *              length              - Maximum length
183  *
184  * RETURN:      None
185  *
186  * DESCRIPTION: Replace every non-printable or non-ascii byte in the string
187  *              with a question mark '?'.
188  *
189  ******************************************************************************/
190 
acpi_tb_fix_string(char * string,acpi_size length)191 static void acpi_tb_fix_string(char *string, acpi_size length)
192 {
193 
194 	while (length && *string) {
195 		if (!ACPI_IS_PRINT(*string)) {
196 			*string = '?';
197 		}
198 		string++;
199 		length--;
200 	}
201 }
202 
203 /*******************************************************************************
204  *
205  * FUNCTION:    acpi_tb_cleanup_table_header
206  *
207  * PARAMETERS:  out_header          - Where the cleaned header is returned
208  *              header              - Input ACPI table header
209  *
210  * RETURN:      Returns the cleaned header in out_header
211  *
212  * DESCRIPTION: Copy the table header and ensure that all "string" fields in
213  *              the header consist of printable characters.
214  *
215  ******************************************************************************/
216 
217 static void
acpi_tb_cleanup_table_header(struct acpi_table_header * out_header,struct acpi_table_header * header)218 acpi_tb_cleanup_table_header(struct acpi_table_header *out_header,
219 			     struct acpi_table_header *header)
220 {
221 
222 	ACPI_MEMCPY(out_header, header, sizeof(struct acpi_table_header));
223 
224 	acpi_tb_fix_string(out_header->signature, ACPI_NAME_SIZE);
225 	acpi_tb_fix_string(out_header->oem_id, ACPI_OEM_ID_SIZE);
226 	acpi_tb_fix_string(out_header->oem_table_id, ACPI_OEM_TABLE_ID_SIZE);
227 	acpi_tb_fix_string(out_header->asl_compiler_id, ACPI_NAME_SIZE);
228 }
229 
230 /*******************************************************************************
231  *
232  * FUNCTION:    acpi_tb_print_table_header
233  *
234  * PARAMETERS:  address             - Table physical address
235  *              header              - Table header
236  *
237  * RETURN:      None
238  *
239  * DESCRIPTION: Print an ACPI table header. Special cases for FACS and RSDP.
240  *
241  ******************************************************************************/
242 
243 void
acpi_tb_print_table_header(acpi_physical_address address,struct acpi_table_header * header)244 acpi_tb_print_table_header(acpi_physical_address address,
245 			   struct acpi_table_header *header)
246 {
247 	struct acpi_table_header local_header;
248 
249 	/*
250 	 * The reason that the Address is cast to a void pointer is so that we
251 	 * can use %p which will work properly on both 32-bit and 64-bit hosts.
252 	 */
253 	if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_FACS)) {
254 
255 		/* FACS only has signature and length fields */
256 
257 		ACPI_INFO((AE_INFO, "%4.4s %p %05X",
258 			   header->signature, ACPI_CAST_PTR(void, address),
259 			   header->length));
260 	} else if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_RSDP)) {
261 
262 		/* RSDP has no common fields */
263 
264 		ACPI_MEMCPY(local_header.oem_id,
265 			    ACPI_CAST_PTR(struct acpi_table_rsdp,
266 					  header)->oem_id, ACPI_OEM_ID_SIZE);
267 		acpi_tb_fix_string(local_header.oem_id, ACPI_OEM_ID_SIZE);
268 
269 		ACPI_INFO((AE_INFO, "RSDP %p %05X (v%.2d %6.6s)",
270 			   ACPI_CAST_PTR (void, address),
271 			   (ACPI_CAST_PTR(struct acpi_table_rsdp, header)->
272 			    revision >
273 			    0) ? ACPI_CAST_PTR(struct acpi_table_rsdp,
274 					       header)->length : 20,
275 			   ACPI_CAST_PTR(struct acpi_table_rsdp,
276 					 header)->revision,
277 			   local_header.oem_id));
278 	} else {
279 		/* Standard ACPI table with full common header */
280 
281 		acpi_tb_cleanup_table_header(&local_header, header);
282 
283 		ACPI_INFO((AE_INFO,
284 			   "%4.4s %p %05X (v%.2d %6.6s %8.8s %08X %4.4s %08X)",
285 			   local_header.signature, ACPI_CAST_PTR(void, address),
286 			   local_header.length, local_header.revision,
287 			   local_header.oem_id, local_header.oem_table_id,
288 			   local_header.oem_revision,
289 			   local_header.asl_compiler_id,
290 			   local_header.asl_compiler_revision));
291 
292 	}
293 }
294 
295 /*******************************************************************************
296  *
297  * FUNCTION:    acpi_tb_validate_checksum
298  *
299  * PARAMETERS:  table               - ACPI table to verify
300  *              length              - Length of entire table
301  *
302  * RETURN:      Status
303  *
304  * DESCRIPTION: Verifies that the table checksums to zero. Optionally returns
305  *              exception on bad checksum.
306  *
307  ******************************************************************************/
308 
acpi_tb_verify_checksum(struct acpi_table_header * table,u32 length)309 acpi_status acpi_tb_verify_checksum(struct acpi_table_header *table, u32 length)
310 {
311 	u8 checksum;
312 
313 	/* Compute the checksum on the table */
314 
315 	checksum = acpi_tb_checksum(ACPI_CAST_PTR(u8, table), length);
316 
317 	/* Checksum ok? (should be zero) */
318 
319 	if (checksum) {
320 		ACPI_BIOS_WARNING((AE_INFO,
321 				   "Incorrect checksum in table [%4.4s] - 0x%2.2X, "
322 				   "should be 0x%2.2X",
323 				   table->signature, table->checksum,
324 				   (u8)(table->checksum - checksum)));
325 
326 #if (ACPI_CHECKSUM_ABORT)
327 
328 		return (AE_BAD_CHECKSUM);
329 #endif
330 	}
331 
332 	return (AE_OK);
333 }
334 
335 /*******************************************************************************
336  *
337  * FUNCTION:    acpi_tb_checksum
338  *
339  * PARAMETERS:  buffer          - Pointer to memory region to be checked
340  *              length          - Length of this memory region
341  *
342  * RETURN:      Checksum (u8)
343  *
344  * DESCRIPTION: Calculates circular checksum of memory region.
345  *
346  ******************************************************************************/
347 
acpi_tb_checksum(u8 * buffer,u32 length)348 u8 acpi_tb_checksum(u8 *buffer, u32 length)
349 {
350 	u8 sum = 0;
351 	u8 *end = buffer + length;
352 
353 	while (buffer < end) {
354 		sum = (u8) (sum + *(buffer++));
355 	}
356 
357 	return (sum);
358 }
359 
360 /*******************************************************************************
361  *
362  * FUNCTION:    acpi_tb_check_dsdt_header
363  *
364  * PARAMETERS:  None
365  *
366  * RETURN:      None
367  *
368  * DESCRIPTION: Quick compare to check validity of the DSDT. This will detect
369  *              if the DSDT has been replaced from outside the OS and/or if
370  *              the DSDT header has been corrupted.
371  *
372  ******************************************************************************/
373 
acpi_tb_check_dsdt_header(void)374 void acpi_tb_check_dsdt_header(void)
375 {
376 
377 	/* Compare original length and checksum to current values */
378 
379 	if (acpi_gbl_original_dsdt_header.length != acpi_gbl_DSDT->length ||
380 	    acpi_gbl_original_dsdt_header.checksum != acpi_gbl_DSDT->checksum) {
381 		ACPI_BIOS_ERROR((AE_INFO,
382 				 "The DSDT has been corrupted or replaced - "
383 				 "old, new headers below"));
384 		acpi_tb_print_table_header(0, &acpi_gbl_original_dsdt_header);
385 		acpi_tb_print_table_header(0, acpi_gbl_DSDT);
386 
387 		ACPI_ERROR((AE_INFO,
388 			    "Please send DMI info to linux-acpi@vger.kernel.org\n"
389 			    "If system does not work as expected, please boot with acpi=copy_dsdt"));
390 
391 		/* Disable further error messages */
392 
393 		acpi_gbl_original_dsdt_header.length = acpi_gbl_DSDT->length;
394 		acpi_gbl_original_dsdt_header.checksum =
395 		    acpi_gbl_DSDT->checksum;
396 	}
397 }
398 
399 /*******************************************************************************
400  *
401  * FUNCTION:    acpi_tb_copy_dsdt
402  *
403  * PARAMETERS:  table_desc          - Installed table to copy
404  *
405  * RETURN:      None
406  *
407  * DESCRIPTION: Implements a subsystem option to copy the DSDT to local memory.
408  *              Some very bad BIOSs are known to either corrupt the DSDT or
409  *              install a new, bad DSDT. This copy works around the problem.
410  *
411  ******************************************************************************/
412 
acpi_tb_copy_dsdt(u32 table_index)413 struct acpi_table_header *acpi_tb_copy_dsdt(u32 table_index)
414 {
415 	struct acpi_table_header *new_table;
416 	struct acpi_table_desc *table_desc;
417 
418 	table_desc = &acpi_gbl_root_table_list.tables[table_index];
419 
420 	new_table = ACPI_ALLOCATE(table_desc->length);
421 	if (!new_table) {
422 		ACPI_ERROR((AE_INFO, "Could not copy DSDT of length 0x%X",
423 			    table_desc->length));
424 		return (NULL);
425 	}
426 
427 	ACPI_MEMCPY(new_table, table_desc->pointer, table_desc->length);
428 	acpi_tb_delete_table(table_desc);
429 	table_desc->pointer = new_table;
430 	table_desc->flags = ACPI_TABLE_ORIGIN_ALLOCATED;
431 
432 	ACPI_INFO((AE_INFO,
433 		   "Forced DSDT copy: length 0x%05X copied locally, original unmapped",
434 		   new_table->length));
435 
436 	return (new_table);
437 }
438 
439 /*******************************************************************************
440  *
441  * FUNCTION:    acpi_tb_install_table
442  *
443  * PARAMETERS:  address                 - Physical address of DSDT or FACS
444  *              signature               - Table signature, NULL if no need to
445  *                                        match
446  *              table_index             - Index into root table array
447  *
448  * RETURN:      None
449  *
450  * DESCRIPTION: Install an ACPI table into the global data structure. The
451  *              table override mechanism is called to allow the host
452  *              OS to replace any table before it is installed in the root
453  *              table array.
454  *
455  ******************************************************************************/
456 
457 void
acpi_tb_install_table(acpi_physical_address address,char * signature,u32 table_index)458 acpi_tb_install_table(acpi_physical_address address,
459 		      char *signature, u32 table_index)
460 {
461 	struct acpi_table_header *table;
462 	struct acpi_table_header *final_table;
463 	struct acpi_table_desc *table_desc;
464 
465 	if (!address) {
466 		ACPI_ERROR((AE_INFO,
467 			    "Null physical address for ACPI table [%s]",
468 			    signature));
469 		return;
470 	}
471 
472 	/* Map just the table header */
473 
474 	table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
475 	if (!table) {
476 		ACPI_ERROR((AE_INFO,
477 			    "Could not map memory for table [%s] at %p",
478 			    signature, ACPI_CAST_PTR(void, address)));
479 		return;
480 	}
481 
482 	/* If a particular signature is expected (DSDT/FACS), it must match */
483 
484 	if (signature && !ACPI_COMPARE_NAME(table->signature, signature)) {
485 		ACPI_BIOS_ERROR((AE_INFO,
486 				 "Invalid signature 0x%X for ACPI table, expected [%s]",
487 				 *ACPI_CAST_PTR(u32, table->signature),
488 				 signature));
489 		goto unmap_and_exit;
490 	}
491 
492 	/*
493 	 * Initialize the table entry. Set the pointer to NULL, since the
494 	 * table is not fully mapped at this time.
495 	 */
496 	table_desc = &acpi_gbl_root_table_list.tables[table_index];
497 
498 	table_desc->address = address;
499 	table_desc->pointer = NULL;
500 	table_desc->length = table->length;
501 	table_desc->flags = ACPI_TABLE_ORIGIN_MAPPED;
502 	ACPI_MOVE_32_TO_32(table_desc->signature.ascii, table->signature);
503 
504 	/*
505 	 * ACPI Table Override:
506 	 *
507 	 * Before we install the table, let the host OS override it with a new
508 	 * one if desired. Any table within the RSDT/XSDT can be replaced,
509 	 * including the DSDT which is pointed to by the FADT.
510 	 *
511 	 * NOTE: If the table is overridden, then final_table will contain a
512 	 * mapped pointer to the full new table. If the table is not overridden,
513 	 * or if there has been a physical override, then the table will be
514 	 * fully mapped later (in verify table). In any case, we must
515 	 * unmap the header that was mapped above.
516 	 */
517 	final_table = acpi_tb_table_override(table, table_desc);
518 	if (!final_table) {
519 		final_table = table;	/* There was no override */
520 	}
521 
522 	acpi_tb_print_table_header(table_desc->address, final_table);
523 
524 	/* Set the global integer width (based upon revision of the DSDT) */
525 
526 	if (table_index == ACPI_TABLE_INDEX_DSDT) {
527 		acpi_ut_set_integer_width(final_table->revision);
528 	}
529 
530 	/*
531 	 * If we have a physical override during this early loading of the ACPI
532 	 * tables, unmap the table for now. It will be mapped again later when
533 	 * it is actually used. This supports very early loading of ACPI tables,
534 	 * before virtual memory is fully initialized and running within the
535 	 * host OS. Note: A logical override has the ACPI_TABLE_ORIGIN_OVERRIDE
536 	 * flag set and will not be deleted below.
537 	 */
538 	if (final_table != table) {
539 		acpi_tb_delete_table(table_desc);
540 	}
541 
542       unmap_and_exit:
543 
544 	/* Always unmap the table header that we mapped above */
545 
546 	acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
547 }
548 
549 /*******************************************************************************
550  *
551  * FUNCTION:    acpi_tb_get_root_table_entry
552  *
553  * PARAMETERS:  table_entry         - Pointer to the RSDT/XSDT table entry
554  *              table_entry_size    - sizeof 32 or 64 (RSDT or XSDT)
555  *
556  * RETURN:      Physical address extracted from the root table
557  *
558  * DESCRIPTION: Get one root table entry. Handles 32-bit and 64-bit cases on
559  *              both 32-bit and 64-bit platforms
560  *
561  * NOTE:        acpi_physical_address is 32-bit on 32-bit platforms, 64-bit on
562  *              64-bit platforms.
563  *
564  ******************************************************************************/
565 
566 static acpi_physical_address
acpi_tb_get_root_table_entry(u8 * table_entry,u32 table_entry_size)567 acpi_tb_get_root_table_entry(u8 *table_entry, u32 table_entry_size)
568 {
569 	u64 address64;
570 
571 	/*
572 	 * Get the table physical address (32-bit for RSDT, 64-bit for XSDT):
573 	 * Note: Addresses are 32-bit aligned (not 64) in both RSDT and XSDT
574 	 */
575 	if (table_entry_size == sizeof(u32)) {
576 		/*
577 		 * 32-bit platform, RSDT: Return 32-bit table entry
578 		 * 64-bit platform, RSDT: Expand 32-bit to 64-bit and return
579 		 */
580 		return ((acpi_physical_address)
581 			(*ACPI_CAST_PTR(u32, table_entry)));
582 	} else {
583 		/*
584 		 * 32-bit platform, XSDT: Truncate 64-bit to 32-bit and return
585 		 * 64-bit platform, XSDT: Move (unaligned) 64-bit to local,
586 		 *  return 64-bit
587 		 */
588 		ACPI_MOVE_64_TO_64(&address64, table_entry);
589 
590 #if ACPI_MACHINE_WIDTH == 32
591 		if (address64 > ACPI_UINT32_MAX) {
592 
593 			/* Will truncate 64-bit address to 32 bits, issue warning */
594 
595 			ACPI_BIOS_WARNING((AE_INFO,
596 					   "64-bit Physical Address in XSDT is too large (0x%8.8X%8.8X),"
597 					   " truncating",
598 					   ACPI_FORMAT_UINT64(address64)));
599 		}
600 #endif
601 		return ((acpi_physical_address) (address64));
602 	}
603 }
604 
605 /*******************************************************************************
606  *
607  * FUNCTION:    acpi_tb_parse_root_table
608  *
609  * PARAMETERS:  rsdp                    - Pointer to the RSDP
610  *
611  * RETURN:      Status
612  *
613  * DESCRIPTION: This function is called to parse the Root System Description
614  *              Table (RSDT or XSDT)
615  *
616  * NOTE:        Tables are mapped (not copied) for efficiency. The FACS must
617  *              be mapped and cannot be copied because it contains the actual
618  *              memory location of the ACPI Global Lock.
619  *
620  ******************************************************************************/
621 
622 acpi_status __init
acpi_tb_parse_root_table(acpi_physical_address rsdp_address)623 acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
624 {
625 	struct acpi_table_rsdp *rsdp;
626 	u32 table_entry_size;
627 	u32 i;
628 	u32 table_count;
629 	struct acpi_table_header *table;
630 	acpi_physical_address address;
631 	acpi_physical_address uninitialized_var(rsdt_address);
632 	u32 length;
633 	u8 *table_entry;
634 	acpi_status status;
635 
636 	ACPI_FUNCTION_TRACE(tb_parse_root_table);
637 
638 	/*
639 	 * Map the entire RSDP and extract the address of the RSDT or XSDT
640 	 */
641 	rsdp = acpi_os_map_memory(rsdp_address, sizeof(struct acpi_table_rsdp));
642 	if (!rsdp) {
643 		return_ACPI_STATUS(AE_NO_MEMORY);
644 	}
645 
646 	acpi_tb_print_table_header(rsdp_address,
647 				   ACPI_CAST_PTR(struct acpi_table_header,
648 						 rsdp));
649 
650 	/* Differentiate between RSDT and XSDT root tables */
651 
652 	if (rsdp->revision > 1 && rsdp->xsdt_physical_address
653 			&& !acpi_rsdt_forced) {
654 		/*
655 		 * Root table is an XSDT (64-bit physical addresses). We must use the
656 		 * XSDT if the revision is > 1 and the XSDT pointer is present, as per
657 		 * the ACPI specification.
658 		 */
659 		address = (acpi_physical_address) rsdp->xsdt_physical_address;
660 		table_entry_size = sizeof(u64);
661 		rsdt_address = (acpi_physical_address)
662 					rsdp->rsdt_physical_address;
663 	} else {
664 		/* Root table is an RSDT (32-bit physical addresses) */
665 
666 		address = (acpi_physical_address) rsdp->rsdt_physical_address;
667 		table_entry_size = sizeof(u32);
668 	}
669 
670 	/*
671 	 * It is not possible to map more than one entry in some environments,
672 	 * so unmap the RSDP here before mapping other tables
673 	 */
674 	acpi_os_unmap_memory(rsdp, sizeof(struct acpi_table_rsdp));
675 
676 	if (table_entry_size == sizeof(u64)) {
677 		if (acpi_tb_check_xsdt(address) == AE_NULL_ENTRY) {
678 			/* XSDT has NULL entry, RSDT is used */
679 			address = rsdt_address;
680 			table_entry_size = sizeof(u32);
681 			ACPI_WARNING((AE_INFO, "BIOS XSDT has NULL entry, "
682 					"using RSDT"));
683 		}
684 	}
685 	/* Map the RSDT/XSDT table header to get the full table length */
686 
687 	table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
688 	if (!table) {
689 		return_ACPI_STATUS(AE_NO_MEMORY);
690 	}
691 
692 	acpi_tb_print_table_header(address, table);
693 
694 	/* Get the length of the full table, verify length and map entire table */
695 
696 	length = table->length;
697 	acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
698 
699 	if (length < sizeof(struct acpi_table_header)) {
700 		ACPI_BIOS_ERROR((AE_INFO,
701 				 "Invalid table length 0x%X in RSDT/XSDT",
702 				 length));
703 		return_ACPI_STATUS(AE_INVALID_TABLE_LENGTH);
704 	}
705 
706 	table = acpi_os_map_memory(address, length);
707 	if (!table) {
708 		return_ACPI_STATUS(AE_NO_MEMORY);
709 	}
710 
711 	/* Validate the root table checksum */
712 
713 	status = acpi_tb_verify_checksum(table, length);
714 	if (ACPI_FAILURE(status)) {
715 		acpi_os_unmap_memory(table, length);
716 		return_ACPI_STATUS(status);
717 	}
718 
719 	/* Calculate the number of tables described in the root table */
720 
721 	table_count = (u32)((table->length - sizeof(struct acpi_table_header)) /
722 			    table_entry_size);
723 	/*
724 	 * First two entries in the table array are reserved for the DSDT
725 	 * and FACS, which are not actually present in the RSDT/XSDT - they
726 	 * come from the FADT
727 	 */
728 	table_entry =
729 	    ACPI_CAST_PTR(u8, table) + sizeof(struct acpi_table_header);
730 	acpi_gbl_root_table_list.current_table_count = 2;
731 
732 	/*
733 	 * Initialize the root table array from the RSDT/XSDT
734 	 */
735 	for (i = 0; i < table_count; i++) {
736 		if (acpi_gbl_root_table_list.current_table_count >=
737 		    acpi_gbl_root_table_list.max_table_count) {
738 
739 			/* There is no more room in the root table array, attempt resize */
740 
741 			status = acpi_tb_resize_root_table_list();
742 			if (ACPI_FAILURE(status)) {
743 				ACPI_WARNING((AE_INFO,
744 					      "Truncating %u table entries!",
745 					      (unsigned) (table_count -
746 					       (acpi_gbl_root_table_list.
747 							  current_table_count -
748 							  2))));
749 				break;
750 			}
751 		}
752 
753 		/* Get the table physical address (32-bit for RSDT, 64-bit for XSDT) */
754 
755 		acpi_gbl_root_table_list.tables[acpi_gbl_root_table_list.
756 						current_table_count].address =
757 		    acpi_tb_get_root_table_entry(table_entry, table_entry_size);
758 
759 		table_entry += table_entry_size;
760 		acpi_gbl_root_table_list.current_table_count++;
761 	}
762 
763 	/*
764 	 * It is not possible to map more than one entry in some environments,
765 	 * so unmap the root table here before mapping other tables
766 	 */
767 	acpi_os_unmap_memory(table, length);
768 
769 	/*
770 	 * Complete the initialization of the root table array by examining
771 	 * the header of each table
772 	 */
773 	for (i = 2; i < acpi_gbl_root_table_list.current_table_count; i++) {
774 		acpi_tb_install_table(acpi_gbl_root_table_list.tables[i].
775 				      address, NULL, i);
776 
777 		/* Special case for FADT - get the DSDT and FACS */
778 
779 		if (ACPI_COMPARE_NAME
780 		    (&acpi_gbl_root_table_list.tables[i].signature,
781 		     ACPI_SIG_FADT)) {
782 			acpi_tb_parse_fadt(i);
783 		}
784 	}
785 
786 	return_ACPI_STATUS(AE_OK);
787 }
788