xref: /freebsd/sys/contrib/dev/acpica/components/tables/tbutils.c (revision dd21556857e8d40f66bf5ad54754d9d52669ebf7)
1 /******************************************************************************
2  *
3  * Module Name: tbutils - ACPI Table utilities
4  *
5  *****************************************************************************/
6 
7 /******************************************************************************
8  *
9  * 1. Copyright Notice
10  *
11  * Some or all of this work - Copyright (c) 1999 - 2024, Intel Corp.
12  * All rights reserved.
13  *
14  * 2. License
15  *
16  * 2.1. This is your license from Intel Corp. under its intellectual property
17  * rights. You may have additional license terms from the party that provided
18  * you this software, covering your right to use that party's intellectual
19  * property rights.
20  *
21  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
22  * copy of the source code appearing in this file ("Covered Code") an
23  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
24  * base code distributed originally by Intel ("Original Intel Code") to copy,
25  * make derivatives, distribute, use and display any portion of the Covered
26  * Code in any form, with the right to sublicense such rights; and
27  *
28  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
29  * license (with the right to sublicense), under only those claims of Intel
30  * patents that are infringed by the Original Intel Code, to make, use, sell,
31  * offer to sell, and import the Covered Code and derivative works thereof
32  * solely to the minimum extent necessary to exercise the above copyright
33  * license, and in no event shall the patent license extend to any additions
34  * to or modifications of the Original Intel Code. No other license or right
35  * is granted directly or by implication, estoppel or otherwise;
36  *
37  * The above copyright and patent license is granted only if the following
38  * conditions are met:
39  *
40  * 3. Conditions
41  *
42  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
43  * Redistribution of source code of any substantial portion of the Covered
44  * Code or modification with rights to further distribute source must include
45  * the above Copyright Notice, the above License, this list of Conditions,
46  * and the following Disclaimer and Export Compliance provision. In addition,
47  * Licensee must cause all Covered Code to which Licensee contributes to
48  * contain a file documenting the changes Licensee made to create that Covered
49  * Code and the date of any change. Licensee must include in that file the
50  * documentation of any changes made by any predecessor Licensee. Licensee
51  * must include a prominent statement that the modification is derived,
52  * directly or indirectly, from Original Intel Code.
53  *
54  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
55  * Redistribution of source code of any substantial portion of the Covered
56  * Code or modification without rights to further distribute source must
57  * include the following Disclaimer and Export Compliance provision in the
58  * documentation and/or other materials provided with distribution. In
59  * addition, Licensee may not authorize further sublicense of source of any
60  * portion of the Covered Code, and must include terms to the effect that the
61  * license from Licensee to its licensee is limited to the intellectual
62  * property embodied in the software Licensee provides to its licensee, and
63  * not to intellectual property embodied in modifications its licensee may
64  * make.
65  *
66  * 3.3. Redistribution of Executable. Redistribution in executable form of any
67  * substantial portion of the Covered Code or modification must reproduce the
68  * above Copyright Notice, and the following Disclaimer and Export Compliance
69  * provision in the documentation and/or other materials provided with the
70  * distribution.
71  *
72  * 3.4. Intel retains all right, title, and interest in and to the Original
73  * Intel Code.
74  *
75  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
76  * Intel shall be used in advertising or otherwise to promote the sale, use or
77  * other dealings in products derived from or relating to the Covered Code
78  * without prior written authorization from Intel.
79  *
80  * 4. Disclaimer and Export Compliance
81  *
82  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
83  * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
84  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
85  * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
86  * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
87  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
88  * PARTICULAR PURPOSE.
89  *
90  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
91  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
92  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
93  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
94  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
95  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
96  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
97  * LIMITED REMEDY.
98  *
99  * 4.3. Licensee shall not export, either directly or indirectly, any of this
100  * software or system incorporating such software without first obtaining any
101  * required license or other approval from the U. S. Department of Commerce or
102  * any other agency or department of the United States Government. In the
103  * event Licensee exports any such software from the United States or
104  * re-exports any such software from a foreign destination, Licensee shall
105  * ensure that the distribution and export/re-export of the software is in
106  * compliance with all laws, regulations, orders, or other restrictions of the
107  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
108  * any of its subsidiaries will export/re-export any technical data, process,
109  * software, or service, directly or indirectly, to any country for which the
110  * United States government or any agency thereof requires an export license,
111  * other governmental approval, or letter of assurance, without first obtaining
112  * such license, approval or letter.
113  *
114  *****************************************************************************
115  *
116  * Alternatively, you may choose to be licensed under the terms of the
117  * following license:
118  *
119  * Redistribution and use in source and binary forms, with or without
120  * modification, are permitted provided that the following conditions
121  * are met:
122  * 1. Redistributions of source code must retain the above copyright
123  *    notice, this list of conditions, and the following disclaimer,
124  *    without modification.
125  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
126  *    substantially similar to the "NO WARRANTY" disclaimer below
127  *    ("Disclaimer") and any redistribution must be conditioned upon
128  *    including a substantially similar Disclaimer requirement for further
129  *    binary redistribution.
130  * 3. Neither the names of the above-listed copyright holders nor the names
131  *    of any contributors may be used to endorse or promote products derived
132  *    from this software without specific prior written permission.
133  *
134  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
135  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
136  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
137  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
138  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
139  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
140  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
141  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
142  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
143  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
144  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
145  *
146  * Alternatively, you may choose to be licensed under the terms of the
147  * GNU General Public License ("GPL") version 2 as published by the Free
148  * Software Foundation.
149  *
150  *****************************************************************************/
151 
152 #include <contrib/dev/acpica/include/acpi.h>
153 #include <contrib/dev/acpica/include/accommon.h>
154 #include <contrib/dev/acpica/include/actables.h>
155 
156 #define _COMPONENT          ACPI_TABLES
157         ACPI_MODULE_NAME    ("tbutils")
158 
159 
160 /* Local prototypes */
161 
162 static ACPI_PHYSICAL_ADDRESS
163 AcpiTbGetRootTableEntry (
164     UINT8                   *TableEntry,
165     UINT32                  TableEntrySize);
166 
167 
168 /*******************************************************************************
169  *
170  * FUNCTION:    AcpiTbInitializeFacs
171  *
172  * PARAMETERS:  None
173  *
174  * RETURN:      Status
175  *
176  * DESCRIPTION: Create a permanent mapping for the FADT and save it in a global
177  *              for accessing the Global Lock and Firmware Waking Vector
178  *
179  ******************************************************************************/
180 
181 ACPI_STATUS
182 AcpiTbInitializeFacs (
183     void)
184 {
185     ACPI_TABLE_FACS         *Facs;
186 
187     if (AcpiGbl_FADT.XFacs &&
188          (!AcpiGbl_FADT.Facs || !AcpiGbl_Use32BitFacsAddresses))
189     {
190         (void) AcpiGetTableByIndex (AcpiGbl_XFacsIndex,
191             ACPI_CAST_INDIRECT_PTR (ACPI_TABLE_HEADER, &Facs));
192         AcpiGbl_FACS = Facs;
193     }
194     else if (AcpiGbl_FADT.Facs)
195     {
196         (void) AcpiGetTableByIndex (AcpiGbl_FacsIndex,
197             ACPI_CAST_INDIRECT_PTR (ACPI_TABLE_HEADER, &Facs));
198         AcpiGbl_FACS = Facs;
199     }
200 
201     /* If there is no FACS, just continue. There was already an error msg */
202 
203     return (AE_OK);
204 }
205 
206 
207 /*******************************************************************************
208  *
209  * FUNCTION:    AcpiTbCheckDsdtHeader
210  *
211  * PARAMETERS:  None
212  *
213  * RETURN:      None
214  *
215  * DESCRIPTION: Quick compare to check validity of the DSDT. This will detect
216  *              if the DSDT has been replaced from outside the OS and/or if
217  *              the DSDT header has been corrupted.
218  *
219  ******************************************************************************/
220 
221 void
222 AcpiTbCheckDsdtHeader (
223     void)
224 {
225 
226     /* Compare original length and checksum to current values */
227 
228     if (AcpiGbl_OriginalDsdtHeader.Length != AcpiGbl_DSDT->Length ||
229         AcpiGbl_OriginalDsdtHeader.Checksum != AcpiGbl_DSDT->Checksum)
230     {
231         ACPI_BIOS_ERROR ((AE_INFO,
232             "The DSDT has been corrupted or replaced - "
233             "old, new headers below"));
234 
235         AcpiTbPrintTableHeader (0, &AcpiGbl_OriginalDsdtHeader);
236         AcpiTbPrintTableHeader (0, AcpiGbl_DSDT);
237 
238         /* Disable further error messages */
239 
240         AcpiGbl_OriginalDsdtHeader.Length = AcpiGbl_DSDT->Length;
241         AcpiGbl_OriginalDsdtHeader.Checksum = AcpiGbl_DSDT->Checksum;
242     }
243 }
244 
245 
246 /*******************************************************************************
247  *
248  * FUNCTION:    AcpiTbCopyDsdt
249  *
250  * PARAMETERS:  TableIndex          - Index of installed table to copy
251  *
252  * RETURN:      The copied DSDT
253  *
254  * DESCRIPTION: Implements a subsystem option to copy the DSDT to local memory.
255  *              Some very bad BIOSs are known to either corrupt the DSDT or
256  *              install a new, bad DSDT. This copy works around the problem.
257  *
258  ******************************************************************************/
259 
260 ACPI_TABLE_HEADER *
261 AcpiTbCopyDsdt (
262     UINT32                  TableIndex)
263 {
264     ACPI_TABLE_HEADER       *NewTable;
265     ACPI_TABLE_DESC         *TableDesc;
266 
267 
268     TableDesc = &AcpiGbl_RootTableList.Tables[TableIndex];
269 
270     NewTable = ACPI_ALLOCATE (TableDesc->Length);
271     if (!NewTable)
272     {
273         ACPI_ERROR ((AE_INFO, "Could not copy DSDT of length 0x%X",
274             TableDesc->Length));
275         return (NULL);
276     }
277 
278     memcpy (NewTable, TableDesc->Pointer, TableDesc->Length);
279     AcpiTbUninstallTable (TableDesc);
280 
281     AcpiTbInitTableDescriptor (
282         &AcpiGbl_RootTableList.Tables[AcpiGbl_DsdtIndex],
283         ACPI_PTR_TO_PHYSADDR (NewTable),
284         ACPI_TABLE_ORIGIN_INTERNAL_VIRTUAL, NewTable);
285 
286     ACPI_INFO ((
287         "Forced DSDT copy: length 0x%05X copied locally, original unmapped",
288         NewTable->Length));
289 
290     return (NewTable);
291 }
292 
293 
294 /*******************************************************************************
295  *
296  * FUNCTION:    AcpiTbGetRootTableEntry
297  *
298  * PARAMETERS:  TableEntry          - Pointer to the RSDT/XSDT table entry
299  *              TableEntrySize      - sizeof 32 or 64 (RSDT or XSDT)
300  *
301  * RETURN:      Physical address extracted from the root table
302  *
303  * DESCRIPTION: Get one root table entry. Handles 32-bit and 64-bit cases on
304  *              both 32-bit and 64-bit platforms
305  *
306  * NOTE:        ACPI_PHYSICAL_ADDRESS is 32-bit on 32-bit platforms, 64-bit on
307  *              64-bit platforms.
308  *
309  ******************************************************************************/
310 
311 static ACPI_PHYSICAL_ADDRESS
312 AcpiTbGetRootTableEntry (
313     UINT8                   *TableEntry,
314     UINT32                  TableEntrySize)
315 {
316     UINT32                  Address32;
317     UINT64                  Address64;
318 
319 
320     /*
321      * Get the table physical address (32-bit for RSDT, 64-bit for XSDT):
322      * Note: Addresses are 32-bit aligned (not 64) in both RSDT and XSDT
323      */
324     if (TableEntrySize == ACPI_RSDT_ENTRY_SIZE)
325     {
326         /*
327          * 32-bit platform, RSDT: Return 32-bit table entry
328          * 64-bit platform, RSDT: Expand 32-bit to 64-bit and return
329          */
330         ACPI_MOVE_32_TO_32(&Address32, TableEntry);
331         return Address32;
332     }
333     else
334     {
335         /*
336          * 32-bit platform, XSDT: Truncate 64-bit to 32-bit and return
337          * 64-bit platform, XSDT: Move (unaligned) 64-bit to local,
338          *  return 64-bit
339          */
340         ACPI_MOVE_64_TO_64 (&Address64, TableEntry);
341 
342 #if ACPI_MACHINE_WIDTH == 32
343         if (Address64 > ACPI_UINT32_MAX)
344         {
345             /* Will truncate 64-bit address to 32 bits, issue warning */
346 
347             ACPI_BIOS_WARNING ((AE_INFO,
348                 "64-bit Physical Address in XSDT is too large (0x%8.8X%8.8X),"
349                 " truncating",
350                 ACPI_FORMAT_UINT64 (Address64)));
351         }
352 #endif
353         return ((ACPI_PHYSICAL_ADDRESS) (Address64));
354     }
355 }
356 
357 
358 /*******************************************************************************
359  *
360  * FUNCTION:    AcpiTbParseRootTable
361  *
362  * PARAMETERS:  RsdpAddress         - Pointer to the RSDP
363  *
364  * RETURN:      Status
365  *
366  * DESCRIPTION: This function is called to parse the Root System Description
367  *              Table (RSDT or XSDT)
368  *
369  * NOTE:        Tables are mapped (not copied) for efficiency. The FACS must
370  *              be mapped and cannot be copied because it contains the actual
371  *              memory location of the ACPI Global Lock.
372  *
373  ******************************************************************************/
374 
375 ACPI_STATUS ACPI_INIT_FUNCTION
376 AcpiTbParseRootTable (
377     ACPI_PHYSICAL_ADDRESS   RsdpAddress)
378 {
379     ACPI_TABLE_RSDP         *Rsdp;
380     UINT32                  TableEntrySize;
381     UINT32                  i;
382     UINT32                  TableCount;
383     ACPI_TABLE_HEADER       *Table;
384     ACPI_PHYSICAL_ADDRESS   Address;
385     UINT32                  Length;
386     UINT8                   *TableEntry;
387     ACPI_STATUS             Status;
388     UINT32                  TableIndex;
389 
390 
391     ACPI_FUNCTION_TRACE (TbParseRootTable);
392 
393 
394     /* Map the entire RSDP and extract the address of the RSDT or XSDT */
395 
396     Rsdp = AcpiOsMapMemory (RsdpAddress, sizeof (ACPI_TABLE_RSDP));
397     if (!Rsdp)
398     {
399         return_ACPI_STATUS (AE_NO_MEMORY);
400     }
401 
402     AcpiTbPrintTableHeader (RsdpAddress,
403         ACPI_CAST_PTR (ACPI_TABLE_HEADER, Rsdp));
404 
405     /* Use XSDT if present and not overridden. Otherwise, use RSDT */
406 
407     if ((Rsdp->Revision > 1) &&
408         Rsdp->XsdtPhysicalAddress &&
409         !AcpiGbl_DoNotUseXsdt)
410     {
411         /*
412          * RSDP contains an XSDT (64-bit physical addresses). We must use
413          * the XSDT if the revision is > 1 and the XSDT pointer is present,
414          * as per the ACPI specification.
415          */
416         Address = (ACPI_PHYSICAL_ADDRESS) Rsdp->XsdtPhysicalAddress;
417         TableEntrySize = ACPI_XSDT_ENTRY_SIZE;
418     }
419     else
420     {
421         /* Root table is an RSDT (32-bit physical addresses) */
422 
423         Address = (ACPI_PHYSICAL_ADDRESS) Rsdp->RsdtPhysicalAddress;
424         TableEntrySize = ACPI_RSDT_ENTRY_SIZE;
425     }
426 
427     /*
428      * It is not possible to map more than one entry in some environments,
429      * so unmap the RSDP here before mapping other tables
430      */
431     AcpiOsUnmapMemory (Rsdp, sizeof (ACPI_TABLE_RSDP));
432 
433     /* Map the RSDT/XSDT table header to get the full table length */
434 
435     Table = AcpiOsMapMemory (Address, sizeof (ACPI_TABLE_HEADER));
436     if (!Table)
437     {
438         return_ACPI_STATUS (AE_NO_MEMORY);
439     }
440 
441     AcpiTbPrintTableHeader (Address, Table);
442 
443     /*
444      * Validate length of the table, and map entire table.
445      * Minimum length table must contain at least one entry.
446      */
447     Length = Table->Length;
448     AcpiOsUnmapMemory (Table, sizeof (ACPI_TABLE_HEADER));
449 
450     if (Length < (sizeof (ACPI_TABLE_HEADER) + TableEntrySize))
451     {
452         ACPI_BIOS_ERROR ((AE_INFO,
453             "Invalid table length 0x%X in RSDT/XSDT", Length));
454         return_ACPI_STATUS (AE_INVALID_TABLE_LENGTH);
455     }
456 
457     Table = AcpiOsMapMemory (Address, Length);
458     if (!Table)
459     {
460         return_ACPI_STATUS (AE_NO_MEMORY);
461     }
462 
463     /* Validate the root table checksum */
464 
465     Status = AcpiUtVerifyChecksum (Table, Length);
466     if (ACPI_FAILURE (Status))
467     {
468         AcpiOsUnmapMemory (Table, Length);
469         return_ACPI_STATUS (Status);
470     }
471 
472     /* Get the number of entries and pointer to first entry */
473 
474     TableCount = (UINT32) ((Table->Length - sizeof (ACPI_TABLE_HEADER)) /
475         TableEntrySize);
476     TableEntry = ACPI_ADD_PTR (UINT8, Table, sizeof (ACPI_TABLE_HEADER));
477 
478     /* Initialize the root table array from the RSDT/XSDT */
479 
480     for (i = 0; i < TableCount; i++)
481     {
482         /* Get the table physical address (32-bit for RSDT, 64-bit for XSDT) */
483 
484         Address = AcpiTbGetRootTableEntry (TableEntry, TableEntrySize);
485 
486         /* Skip NULL entries in RSDT/XSDT */
487 
488         if (!Address)
489         {
490             goto NextTable;
491         }
492 
493         Status = AcpiTbInstallStandardTable (Address,
494             ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL, NULL, FALSE, TRUE,
495             &TableIndex);
496 
497         if (ACPI_SUCCESS (Status) &&
498             ACPI_COMPARE_NAMESEG (
499                 &AcpiGbl_RootTableList.Tables[TableIndex].Signature,
500                 ACPI_SIG_FADT))
501         {
502             AcpiGbl_FadtIndex = TableIndex;
503             AcpiTbParseFadt ();
504         }
505 
506 NextTable:
507 
508         TableEntry += TableEntrySize;
509     }
510 
511     AcpiOsUnmapMemory (Table, Length);
512     return_ACPI_STATUS (AE_OK);
513 }
514 
515 
516 /*******************************************************************************
517  *
518  * FUNCTION:    AcpiTbGetTable
519  *
520  * PARAMETERS:  TableDesc           - Table descriptor
521  *              OutTable            - Where the pointer to the table is returned
522  *
523  * RETURN:      Status and pointer to the requested table
524  *
525  * DESCRIPTION: Increase a reference to a table descriptor and return the
526  *              validated table pointer.
527  *              If the table descriptor is an entry of the root table list,
528  *              this API must be invoked with ACPI_MTX_TABLES acquired.
529  *
530  ******************************************************************************/
531 
532 ACPI_STATUS
533 AcpiTbGetTable (
534     ACPI_TABLE_DESC        *TableDesc,
535     ACPI_TABLE_HEADER      **OutTable)
536 {
537     ACPI_STATUS            Status;
538 
539 
540     ACPI_FUNCTION_TRACE (AcpiTbGetTable);
541 
542 
543     if (TableDesc->ValidationCount == 0)
544     {
545         /* Table need to be "VALIDATED" */
546 
547         Status = AcpiTbValidateTable (TableDesc);
548         if (ACPI_FAILURE (Status))
549         {
550             return_ACPI_STATUS (Status);
551         }
552     }
553 
554     if (TableDesc->ValidationCount < ACPI_MAX_TABLE_VALIDATIONS)
555     {
556         TableDesc->ValidationCount++;
557 
558         /*
559          * Detect ValidationCount overflows to ensure that the warning
560          * message will only be printed once.
561          */
562         if (TableDesc->ValidationCount >= ACPI_MAX_TABLE_VALIDATIONS)
563         {
564             ACPI_WARNING((AE_INFO,
565                 "Table %p, Validation count overflows\n", TableDesc));
566         }
567     }
568 
569     *OutTable = TableDesc->Pointer;
570     return_ACPI_STATUS (AE_OK);
571 }
572 
573 
574 /*******************************************************************************
575  *
576  * FUNCTION:    AcpiTbPutTable
577  *
578  * PARAMETERS:  TableDesc           - Table descriptor
579  *
580  * RETURN:      None
581  *
582  * DESCRIPTION: Decrease a reference to a table descriptor and release the
583  *              validated table pointer if no references.
584  *              If the table descriptor is an entry of the root table list,
585  *              this API must be invoked with ACPI_MTX_TABLES acquired.
586  *
587  ******************************************************************************/
588 
589 void
590 AcpiTbPutTable (
591     ACPI_TABLE_DESC        *TableDesc)
592 {
593 
594     ACPI_FUNCTION_TRACE (AcpiTbPutTable);
595 
596 
597     if (TableDesc->ValidationCount < ACPI_MAX_TABLE_VALIDATIONS)
598     {
599         TableDesc->ValidationCount--;
600 
601         /*
602          * Detect ValidationCount underflows to ensure that the warning
603          * message will only be printed once.
604          */
605         if (TableDesc->ValidationCount >= ACPI_MAX_TABLE_VALIDATIONS)
606         {
607             ACPI_WARNING ((AE_INFO,
608                 "Table %p, Validation count underflows\n", TableDesc));
609             return_VOID;
610         }
611     }
612 
613     if (TableDesc->ValidationCount == 0)
614     {
615         /* Table need to be "INVALIDATED" */
616 
617         AcpiTbInvalidateTable (TableDesc);
618     }
619 
620     return_VOID;
621 }
622