1 /*******************************************************************************
2  *
3  * Module Name: nsaccess - Top-level functions for accessing ACPI namespace
4  *
5  ******************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2022, 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 MERCHANTABILITY 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.h"
45 #include "accommon.h"
46 #include "amlcode.h"
47 #include "acnamesp.h"
48 #include "acdispat.h"
49 
50 #ifdef ACPI_ASL_COMPILER
51     #include "acdisasm.h"
52 #endif
53 
54 #define _COMPONENT          ACPI_NAMESPACE
55         ACPI_MODULE_NAME    ("nsaccess")
56 
57 
58 /*******************************************************************************
59  *
60  * FUNCTION:    AcpiNsRootInitialize
61  *
62  * PARAMETERS:  None
63  *
64  * RETURN:      Status
65  *
66  * DESCRIPTION: Allocate and initialize the default root named objects
67  *
68  * MUTEX:       Locks namespace for entire execution
69  *
70  ******************************************************************************/
71 
72 ACPI_STATUS
73 AcpiNsRootInitialize (
74     void)
75 {
76     ACPI_STATUS                 Status;
77     const ACPI_PREDEFINED_NAMES *InitVal = NULL;
78     ACPI_NAMESPACE_NODE         *NewNode;
79     ACPI_NAMESPACE_NODE         *PrevNode = NULL;
80     ACPI_OPERAND_OBJECT         *ObjDesc;
81     ACPI_STRING                 Val = NULL;
82 
83 
84     ACPI_FUNCTION_TRACE (NsRootInitialize);
85 
86 
87     Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
88     if (ACPI_FAILURE (Status))
89     {
90         return_ACPI_STATUS (Status);
91     }
92 
93     /*
94      * The global root ptr is initially NULL, so a non-NULL value indicates
95      * that AcpiNsRootInitialize() has already been called; just return.
96      */
97     if (AcpiGbl_RootNode)
98     {
99         Status = AE_OK;
100         goto UnlockAndExit;
101     }
102 
103     /*
104      * Tell the rest of the subsystem that the root is initialized
105      * (This is OK because the namespace is locked)
106      */
107     AcpiGbl_RootNode = &AcpiGbl_RootNodeStruct;
108 
109     /* Enter the predefined names in the name table */
110 
111     ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
112         "Entering predefined entries into namespace\n"));
113 
114     /*
115      * Create the initial (default) namespace.
116      * This namespace looks like something similar to this:
117      *
118      *   ACPI Namespace (from Namespace Root):
119      *    0  _GPE Scope        00203160 00
120      *    0  _PR_ Scope        002031D0 00
121      *    0  _SB_ Device       00203240 00 Notify Object: 0020ADD8
122      *    0  _SI_ Scope        002032B0 00
123      *    0  _TZ_ Device       00203320 00
124      *    0  _REV Integer      00203390 00 = 0000000000000002
125      *    0  _OS_ String       00203488 00 Len 14 "Microsoft Windows NT"
126      *    0  _GL_ Mutex        00203580 00 Object 002035F0
127      *    0  _OSI Method       00203678 00 Args 1 Len 0000 Aml 00000000
128      */
129     for (InitVal = AcpiGbl_PreDefinedNames; InitVal->Name; InitVal++)
130     {
131         Status = AE_OK;
132 
133         /* _OSI is optional for now, will be permanent later */
134 
135         if (!strcmp (InitVal->Name, "_OSI") && !AcpiGbl_CreateOsiMethod)
136         {
137             continue;
138         }
139 
140         /*
141          * Create, init, and link the new predefined name
142          * Note: No need to use AcpiNsLookup here because all the
143          * predefined names are at the root level. It is much easier to
144          * just create and link the new node(s) here.
145          */
146         NewNode = AcpiNsCreateNode (*ACPI_CAST_PTR (UINT32, InitVal->Name));
147         if (!NewNode)
148         {
149             Status = AE_NO_MEMORY;
150             goto UnlockAndExit;
151         }
152 
153         NewNode->DescriptorType = ACPI_DESC_TYPE_NAMED;
154         NewNode->Type = InitVal->Type;
155 
156         if (!PrevNode)
157         {
158             AcpiGbl_RootNodeStruct.Child = NewNode;
159         }
160         else
161         {
162             PrevNode->Peer = NewNode;
163         }
164 
165         NewNode->Parent = &AcpiGbl_RootNodeStruct;
166         PrevNode = NewNode;
167 
168         /*
169          * Name entered successfully. If entry in PreDefinedNames[] specifies
170          * an initial value, create the initial value.
171          */
172         if (InitVal->Val)
173         {
174             Status = AcpiOsPredefinedOverride (InitVal, &Val);
175             if (ACPI_FAILURE (Status))
176             {
177                 ACPI_ERROR ((AE_INFO,
178                     "Could not override predefined %s",
179                     InitVal->Name));
180             }
181 
182             if (!Val)
183             {
184                 Val = InitVal->Val;
185             }
186 
187             /*
188              * Entry requests an initial value, allocate a
189              * descriptor for it.
190              */
191             ObjDesc = AcpiUtCreateInternalObject (InitVal->Type);
192             if (!ObjDesc)
193             {
194                 Status = AE_NO_MEMORY;
195                 goto UnlockAndExit;
196             }
197 
198             /*
199              * Convert value string from table entry to
200              * internal representation. Only types actually
201              * used for initial values are implemented here.
202              */
203             switch (InitVal->Type)
204             {
205             case ACPI_TYPE_METHOD:
206 
207                 ObjDesc->Method.ParamCount = (UINT8) ACPI_TO_INTEGER (Val);
208                 ObjDesc->Common.Flags |= AOPOBJ_DATA_VALID;
209 
210 #if defined (ACPI_ASL_COMPILER)
211 
212                 /* Save the parameter count for the iASL compiler */
213 
214                 NewNode->Value = ObjDesc->Method.ParamCount;
215 #else
216                 /* Mark this as a very SPECIAL method (_OSI) */
217 
218                 ObjDesc->Method.InfoFlags = ACPI_METHOD_INTERNAL_ONLY;
219                 ObjDesc->Method.Dispatch.Implementation = AcpiUtOsiImplementation;
220 #endif
221                 break;
222 
223             case ACPI_TYPE_INTEGER:
224 
225                 ObjDesc->Integer.Value = ACPI_TO_INTEGER (Val);
226                 break;
227 
228             case ACPI_TYPE_STRING:
229 
230                 /* Build an object around the static string */
231 
232                 ObjDesc->String.Length = (UINT32) strlen (Val);
233                 ObjDesc->String.Pointer = Val;
234                 ObjDesc->Common.Flags |= AOPOBJ_STATIC_POINTER;
235                 break;
236 
237             case ACPI_TYPE_MUTEX:
238 
239                 ObjDesc->Mutex.Node = NewNode;
240                 ObjDesc->Mutex.SyncLevel = (UINT8) (ACPI_TO_INTEGER (Val) - 1);
241 
242                 /* Create a mutex */
243 
244                 Status = AcpiOsCreateMutex (&ObjDesc->Mutex.OsMutex);
245                 if (ACPI_FAILURE (Status))
246                 {
247                     AcpiUtRemoveReference (ObjDesc);
248                     goto UnlockAndExit;
249                 }
250 
251                 /* Special case for ACPI Global Lock */
252 
253                 if (strcmp (InitVal->Name, "_GL_") == 0)
254                 {
255                     AcpiGbl_GlobalLockMutex = ObjDesc;
256 
257                     /* Create additional counting semaphore for global lock */
258 
259                     Status = AcpiOsCreateSemaphore (
260                         1, 0, &AcpiGbl_GlobalLockSemaphore);
261                     if (ACPI_FAILURE (Status))
262                     {
263                         AcpiUtRemoveReference (ObjDesc);
264                         goto UnlockAndExit;
265                     }
266                 }
267                 break;
268 
269             default:
270 
271                 ACPI_ERROR ((AE_INFO, "Unsupported initial type value 0x%X",
272                     InitVal->Type));
273                 AcpiUtRemoveReference (ObjDesc);
274                 ObjDesc = NULL;
275                 continue;
276             }
277 
278             /* Store pointer to value descriptor in the Node */
279 
280             Status = AcpiNsAttachObject (NewNode, ObjDesc,
281                 ObjDesc->Common.Type);
282 
283             /* Remove local reference to the object */
284 
285             AcpiUtRemoveReference (ObjDesc);
286         }
287     }
288 
289 UnlockAndExit:
290     (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
291 
292     /* Save a handle to "_GPE", it is always present */
293 
294     if (ACPI_SUCCESS (Status))
295     {
296         Status = AcpiNsGetNode (NULL, "\\_GPE", ACPI_NS_NO_UPSEARCH,
297             &AcpiGbl_FadtGpeDevice);
298     }
299 
300     return_ACPI_STATUS (Status);
301 }
302 
303 
304 /*******************************************************************************
305  *
306  * FUNCTION:    AcpiNsLookup
307  *
308  * PARAMETERS:  ScopeInfo       - Current scope info block
309  *              Pathname        - Search pathname, in internal format
310  *                                (as represented in the AML stream)
311  *              Type            - Type associated with name
312  *              InterpreterMode - IMODE_LOAD_PASS2 => add name if not found
313  *              Flags           - Flags describing the search restrictions
314  *              WalkState       - Current state of the walk
315  *              ReturnNode      - Where the Node is placed (if found
316  *                                or created successfully)
317  *
318  * RETURN:      Status
319  *
320  * DESCRIPTION: Find or enter the passed name in the name space.
321  *              Log an error if name not found in Exec mode.
322  *
323  * MUTEX:       Assumes namespace is locked.
324  *
325  ******************************************************************************/
326 
327 ACPI_STATUS
328 AcpiNsLookup (
329     ACPI_GENERIC_STATE      *ScopeInfo,
330     char                    *Pathname,
331     ACPI_OBJECT_TYPE        Type,
332     ACPI_INTERPRETER_MODE   InterpreterMode,
333     UINT32                  Flags,
334     ACPI_WALK_STATE         *WalkState,
335     ACPI_NAMESPACE_NODE     **ReturnNode)
336 {
337     ACPI_STATUS             Status;
338     char                    *Path = Pathname;
339     char                    *ExternalPath;
340     ACPI_NAMESPACE_NODE     *PrefixNode;
341     ACPI_NAMESPACE_NODE     *CurrentNode = NULL;
342     ACPI_NAMESPACE_NODE     *ThisNode = NULL;
343     UINT32                  NumSegments;
344     UINT32                  NumCarats;
345     ACPI_NAME               SimpleName;
346     ACPI_OBJECT_TYPE        TypeToCheckFor;
347     ACPI_OBJECT_TYPE        ThisSearchType;
348     UINT32                  SearchParentFlag = ACPI_NS_SEARCH_PARENT;
349     UINT32                  LocalFlags;
350     ACPI_INTERPRETER_MODE   LocalInterpreterMode;
351 
352 
353     ACPI_FUNCTION_TRACE (NsLookup);
354 
355 
356     if (!ReturnNode)
357     {
358         return_ACPI_STATUS (AE_BAD_PARAMETER);
359     }
360 
361     LocalFlags = Flags &
362         ~(ACPI_NS_ERROR_IF_FOUND | ACPI_NS_OVERRIDE_IF_FOUND |
363           ACPI_NS_SEARCH_PARENT);
364     *ReturnNode = ACPI_ENTRY_NOT_FOUND;
365     AcpiGbl_NsLookupCount++;
366 
367     if (!AcpiGbl_RootNode)
368     {
369         return_ACPI_STATUS (AE_NO_NAMESPACE);
370     }
371 
372     /* Get the prefix scope. A null scope means use the root scope */
373 
374     if ((!ScopeInfo) ||
375         (!ScopeInfo->Scope.Node))
376     {
377         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
378             "Null scope prefix, using root node (%p)\n",
379             AcpiGbl_RootNode));
380 
381         PrefixNode = AcpiGbl_RootNode;
382     }
383     else
384     {
385         PrefixNode = ScopeInfo->Scope.Node;
386         if (ACPI_GET_DESCRIPTOR_TYPE (PrefixNode) != ACPI_DESC_TYPE_NAMED)
387         {
388             ACPI_ERROR ((AE_INFO, "%p is not a namespace node [%s]",
389                 PrefixNode, AcpiUtGetDescriptorName (PrefixNode)));
390             return_ACPI_STATUS (AE_AML_INTERNAL);
391         }
392 
393         if (!(Flags & ACPI_NS_PREFIX_IS_SCOPE))
394         {
395             /*
396              * This node might not be a actual "scope" node (such as a
397              * Device/Method, etc.)  It could be a Package or other object
398              * node. Backup up the tree to find the containing scope node.
399              */
400             while (!AcpiNsOpensScope (PrefixNode->Type) &&
401                     PrefixNode->Type != ACPI_TYPE_ANY)
402             {
403                 PrefixNode = PrefixNode->Parent;
404             }
405         }
406     }
407 
408     /* Save type. TBD: may be no longer necessary */
409 
410     TypeToCheckFor = Type;
411 
412     /*
413      * Begin examination of the actual pathname
414      */
415     if (!Pathname)
416     {
417         /* A Null NamePath is allowed and refers to the root */
418 
419         NumSegments = 0;
420         ThisNode = AcpiGbl_RootNode;
421         Path = "";
422 
423         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
424             "Null Pathname (Zero segments), Flags=%X\n", Flags));
425     }
426     else
427     {
428         /*
429          * Name pointer is valid (and must be in internal name format)
430          *
431          * Check for scope prefixes:
432          *
433          * As represented in the AML stream, a namepath consists of an
434          * optional scope prefix followed by a name segment part.
435          *
436          * If present, the scope prefix is either a Root Prefix (in
437          * which case the name is fully qualified), or one or more
438          * Parent Prefixes (in which case the name's scope is relative
439          * to the current scope).
440          */
441         if (*Path == (UINT8) AML_ROOT_PREFIX)
442         {
443             /* Pathname is fully qualified, start from the root */
444 
445             ThisNode = AcpiGbl_RootNode;
446             SearchParentFlag = ACPI_NS_NO_UPSEARCH;
447 
448             /* Point to name segment part */
449 
450             Path++;
451 
452             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
453                 "Path is absolute from root [%p]\n", ThisNode));
454         }
455         else
456         {
457             /* Pathname is relative to current scope, start there */
458 
459             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
460                 "Searching relative to prefix scope [%4.4s] (%p)\n",
461                 AcpiUtGetNodeName (PrefixNode), PrefixNode));
462 
463             /*
464              * Handle multiple Parent Prefixes (carat) by just getting
465              * the parent node for each prefix instance.
466              */
467             ThisNode = PrefixNode;
468             NumCarats = 0;
469             while (*Path == (UINT8) AML_PARENT_PREFIX)
470             {
471                 /* Name is fully qualified, no search rules apply */
472 
473                 SearchParentFlag = ACPI_NS_NO_UPSEARCH;
474 
475                 /*
476                  * Point past this prefix to the name segment
477                  * part or the next Parent Prefix
478                  */
479                 Path++;
480 
481                 /* Backup to the parent node */
482 
483                 NumCarats++;
484                 ThisNode = ThisNode->Parent;
485                 if (!ThisNode)
486                 {
487                     /*
488                      * Current scope has no parent scope. Externalize
489                      * the internal path for error message.
490                      */
491                     Status = AcpiNsExternalizeName (ACPI_UINT32_MAX, Pathname,
492                         NULL, &ExternalPath);
493                     if (ACPI_SUCCESS (Status))
494                     {
495                         ACPI_ERROR ((AE_INFO,
496                             "%s: Path has too many parent prefixes (^)",
497                             ExternalPath));
498 
499                         ACPI_FREE (ExternalPath);
500                     }
501 
502                     return_ACPI_STATUS (AE_NOT_FOUND);
503                 }
504             }
505 
506             if (SearchParentFlag == ACPI_NS_NO_UPSEARCH)
507             {
508                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
509                     "Search scope is [%4.4s], path has %u carat(s)\n",
510                     AcpiUtGetNodeName (ThisNode), NumCarats));
511             }
512         }
513 
514         /*
515          * Determine the number of ACPI name segments in this pathname.
516          *
517          * The segment part consists of either:
518          *  - A Null name segment (0)
519          *  - A DualNamePrefix followed by two 4-byte name segments
520          *  - A MultiNamePrefix followed by a byte indicating the
521          *      number of segments and the segments themselves.
522          *  - A single 4-byte name segment
523          *
524          * Examine the name prefix opcode, if any, to determine the number of
525          * segments.
526          */
527         switch (*Path)
528         {
529         case 0:
530             /*
531              * Null name after a root or parent prefixes. We already
532              * have the correct target node and there are no name segments.
533              */
534             NumSegments  = 0;
535             Type = ThisNode->Type;
536 
537             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
538                 "Prefix-only Pathname (Zero name segments), Flags=%X\n",
539                 Flags));
540             break;
541 
542         case AML_DUAL_NAME_PREFIX:
543 
544             /* More than one NameSeg, search rules do not apply */
545 
546             SearchParentFlag = ACPI_NS_NO_UPSEARCH;
547 
548             /* Two segments, point to first name segment */
549 
550             NumSegments = 2;
551             Path++;
552 
553             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
554                 "Dual Pathname (2 segments, Flags=%X)\n", Flags));
555             break;
556 
557         case AML_MULTI_NAME_PREFIX:
558 
559             /* More than one NameSeg, search rules do not apply */
560 
561             SearchParentFlag = ACPI_NS_NO_UPSEARCH;
562 
563             /* Extract segment count, point to first name segment */
564 
565             Path++;
566             NumSegments = (UINT32) (UINT8) *Path;
567             Path++;
568 
569             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
570                 "Multi Pathname (%u Segments, Flags=%X)\n",
571                 NumSegments, Flags));
572             break;
573 
574         default:
575             /*
576              * Not a Null name, no Dual or Multi prefix, hence there is
577              * only one name segment and Pathname is already pointing to it.
578              */
579             NumSegments = 1;
580 
581             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
582                 "Simple Pathname (1 segment, Flags=%X)\n", Flags));
583             break;
584         }
585 
586         ACPI_DEBUG_EXEC (AcpiNsPrintPathname (NumSegments, Path));
587     }
588 
589 
590     /*
591      * Search namespace for each segment of the name. Loop through and
592      * verify (or add to the namespace) each name segment.
593      *
594      * The object type is significant only at the last name
595      * segment. (We don't care about the types along the path, only
596      * the type of the final target object.)
597      */
598     ThisSearchType = ACPI_TYPE_ANY;
599     CurrentNode = ThisNode;
600 
601     while (NumSegments && CurrentNode)
602     {
603         NumSegments--;
604         if (!NumSegments)
605         {
606             /* This is the last segment, enable typechecking */
607 
608             ThisSearchType = Type;
609 
610             /*
611              * Only allow automatic parent search (search rules) if the caller
612              * requested it AND we have a single, non-fully-qualified NameSeg
613              */
614             if ((SearchParentFlag != ACPI_NS_NO_UPSEARCH) &&
615                 (Flags & ACPI_NS_SEARCH_PARENT))
616             {
617                 LocalFlags |= ACPI_NS_SEARCH_PARENT;
618             }
619 
620             /* Set error flag according to caller */
621 
622             if (Flags & ACPI_NS_ERROR_IF_FOUND)
623             {
624                 LocalFlags |= ACPI_NS_ERROR_IF_FOUND;
625             }
626 
627             /* Set override flag according to caller */
628 
629             if (Flags & ACPI_NS_OVERRIDE_IF_FOUND)
630             {
631                 LocalFlags |= ACPI_NS_OVERRIDE_IF_FOUND;
632             }
633         }
634 
635         /* Handle opcodes that create a new NameSeg via a full NamePath */
636 
637         LocalInterpreterMode = InterpreterMode;
638         if ((Flags & ACPI_NS_PREFIX_MUST_EXIST) && (NumSegments > 0))
639         {
640             /* Every element of the path must exist (except for the final NameSeg) */
641 
642             LocalInterpreterMode = ACPI_IMODE_EXECUTE;
643         }
644 
645         /* Extract one ACPI name from the front of the pathname */
646 
647         ACPI_MOVE_32_TO_32 (&SimpleName, Path);
648 
649         /* Try to find the single (4 character) ACPI name */
650 
651         Status = AcpiNsSearchAndEnter (SimpleName, WalkState, CurrentNode,
652             LocalInterpreterMode, ThisSearchType, LocalFlags, &ThisNode);
653         if (ACPI_FAILURE (Status))
654         {
655             if (Status == AE_NOT_FOUND)
656             {
657 #if !defined ACPI_ASL_COMPILER /* Note: iASL reports this error by itself, not needed here */
658                 if (Flags & ACPI_NS_PREFIX_MUST_EXIST)
659                 {
660                     AcpiOsPrintf (ACPI_MSG_BIOS_ERROR
661                         "Object does not exist: %4.4s\n", (char *) &SimpleName);
662                 }
663 #endif
664                 /* Name not found in ACPI namespace */
665 
666                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
667                     "Name [%4.4s] not found in scope [%4.4s] %p\n",
668                     (char *) &SimpleName, (char *) &CurrentNode->Name,
669                     CurrentNode));
670             }
671 
672 #ifdef ACPI_EXEC_APP
673             if ((Status == AE_ALREADY_EXISTS) &&
674                 (ThisNode->Flags & ANOBJ_NODE_EARLY_INIT))
675             {
676                 ThisNode->Flags &= ~ANOBJ_NODE_EARLY_INIT;
677                 Status = AE_OK;
678             }
679 #endif
680 
681 #ifdef ACPI_ASL_COMPILER
682             /*
683              * If this ACPI name already exists within the namespace as an
684              * external declaration, then mark the external as a conflicting
685              * declaration and proceed to process the current node as if it did
686              * not exist in the namespace. If this node is not processed as
687              * normal, then it could cause improper namespace resolution
688              * by failing to open a new scope.
689              */
690             if (AcpiGbl_DisasmFlag &&
691                 (Status == AE_ALREADY_EXISTS) &&
692                 ((ThisNode->Flags & ANOBJ_IS_EXTERNAL) ||
693                     (WalkState && WalkState->Opcode == AML_EXTERNAL_OP)))
694             {
695                 ThisNode->Flags &= ~ANOBJ_IS_EXTERNAL;
696                 ThisNode->Type = (UINT8)ThisSearchType;
697                 if (WalkState->Opcode != AML_EXTERNAL_OP)
698                 {
699                     AcpiDmMarkExternalConflict (ThisNode);
700                 }
701                 break;
702             }
703 #endif
704 
705             *ReturnNode = ThisNode;
706             return_ACPI_STATUS (Status);
707         }
708 
709         /* More segments to follow? */
710 
711         if (NumSegments > 0)
712         {
713             /*
714              * If we have an alias to an object that opens a scope (such as a
715              * device or processor), we need to dereference the alias here so
716              * that we can access any children of the original node (via the
717              * remaining segments).
718              */
719             if (ThisNode->Type == ACPI_TYPE_LOCAL_ALIAS)
720             {
721                 if (!ThisNode->Object)
722                 {
723                     return_ACPI_STATUS (AE_NOT_EXIST);
724                 }
725 
726                 if (AcpiNsOpensScope (((ACPI_NAMESPACE_NODE *)
727                         ThisNode->Object)->Type))
728                 {
729                     ThisNode = (ACPI_NAMESPACE_NODE *) ThisNode->Object;
730                 }
731             }
732         }
733 
734         /* Special handling for the last segment (NumSegments == 0) */
735 
736         else
737         {
738             /*
739              * Sanity typecheck of the target object:
740              *
741              * If 1) This is the last segment (NumSegments == 0)
742              *    2) And we are looking for a specific type
743              *       (Not checking for TYPE_ANY)
744              *    3) Which is not an alias
745              *    4) Which is not a local type (TYPE_SCOPE)
746              *    5) And the type of target object is known (not TYPE_ANY)
747              *    6) And target object does not match what we are looking for
748              *
749              * Then we have a type mismatch. Just warn and ignore it.
750              */
751             if ((TypeToCheckFor != ACPI_TYPE_ANY)                   &&
752                 (TypeToCheckFor != ACPI_TYPE_LOCAL_ALIAS)           &&
753                 (TypeToCheckFor != ACPI_TYPE_LOCAL_METHOD_ALIAS)    &&
754                 (TypeToCheckFor != ACPI_TYPE_LOCAL_SCOPE)           &&
755                 (ThisNode->Type != ACPI_TYPE_ANY)                   &&
756                 (ThisNode->Type != TypeToCheckFor))
757             {
758                 /* Complain about a type mismatch */
759 
760                 ACPI_WARNING ((AE_INFO,
761                     "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
762                     ACPI_CAST_PTR (char, &SimpleName),
763                     AcpiUtGetTypeName (ThisNode->Type),
764                     AcpiUtGetTypeName (TypeToCheckFor)));
765             }
766 
767             /*
768              * If this is the last name segment and we are not looking for a
769              * specific type, but the type of found object is known, use that
770              * type to (later) see if it opens a scope.
771              */
772             if (Type == ACPI_TYPE_ANY)
773             {
774                 Type = ThisNode->Type;
775             }
776         }
777 
778         /* Point to next name segment and make this node current */
779 
780         Path += ACPI_NAMESEG_SIZE;
781         CurrentNode = ThisNode;
782     }
783 
784     /* Always check if we need to open a new scope */
785 
786     if (!(Flags & ACPI_NS_DONT_OPEN_SCOPE) && (WalkState))
787     {
788         /*
789          * If entry is a type which opens a scope, push the new scope on the
790          * scope stack.
791          */
792         if (AcpiNsOpensScope (Type))
793         {
794             Status = AcpiDsScopeStackPush (ThisNode, Type, WalkState);
795             if (ACPI_FAILURE (Status))
796             {
797                 return_ACPI_STATUS (Status);
798             }
799         }
800     }
801 
802 #ifdef ACPI_EXEC_APP
803     if (Flags & ACPI_NS_EARLY_INIT)
804     {
805         ThisNode->Flags |= ANOBJ_NODE_EARLY_INIT;
806     }
807 #endif
808 
809     *ReturnNode = ThisNode;
810     return_ACPI_STATUS (AE_OK);
811 }
812