1 /*******************************************************************************
2  *
3  * Module Name: nsaccess - Top-level functions for accessing ACPI namespace
4  *
5  ******************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2020, 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.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 = ACPI_ALLOCATE_ZEROED (sizeof (ACPI_NAMESPACE_NODE));
147         if (!NewNode)
148         {
149             Status = AE_NO_MEMORY;
150             goto UnlockAndExit;
151         }
152 
153         ACPI_COPY_NAMESEG (NewNode->Name.Ascii, InitVal->Name);
154         NewNode->DescriptorType = ACPI_DESC_TYPE_NAMED;
155         NewNode->Type = InitVal->Type;
156 
157         if (!PrevNode)
158         {
159             AcpiGbl_RootNodeStruct.Child = NewNode;
160         }
161         else
162         {
163             PrevNode->Peer = NewNode;
164         }
165 
166         NewNode->Parent = &AcpiGbl_RootNodeStruct;
167         PrevNode = NewNode;
168 
169         /*
170          * Name entered successfully. If entry in PreDefinedNames[] specifies
171          * an initial value, create the initial value.
172          */
173         if (InitVal->Val)
174         {
175             Status = AcpiOsPredefinedOverride (InitVal, &Val);
176             if (ACPI_FAILURE (Status))
177             {
178                 ACPI_ERROR ((AE_INFO,
179                     "Could not override predefined %s",
180                     InitVal->Name));
181             }
182 
183             if (!Val)
184             {
185                 Val = InitVal->Val;
186             }
187 
188             /*
189              * Entry requests an initial value, allocate a
190              * descriptor for it.
191              */
192             ObjDesc = AcpiUtCreateInternalObject (InitVal->Type);
193             if (!ObjDesc)
194             {
195                 Status = AE_NO_MEMORY;
196                 goto UnlockAndExit;
197             }
198 
199             /*
200              * Convert value string from table entry to
201              * internal representation. Only types actually
202              * used for initial values are implemented here.
203              */
204             switch (InitVal->Type)
205             {
206             case ACPI_TYPE_METHOD:
207 
208                 ObjDesc->Method.ParamCount = (UINT8) ACPI_TO_INTEGER (Val);
209                 ObjDesc->Common.Flags |= AOPOBJ_DATA_VALID;
210 
211 #if defined (ACPI_ASL_COMPILER)
212 
213                 /* Save the parameter count for the iASL compiler */
214 
215                 NewNode->Value = ObjDesc->Method.ParamCount;
216 #else
217                 /* Mark this as a very SPECIAL method (_OSI) */
218 
219                 ObjDesc->Method.InfoFlags = ACPI_METHOD_INTERNAL_ONLY;
220                 ObjDesc->Method.Dispatch.Implementation = AcpiUtOsiImplementation;
221 #endif
222                 break;
223 
224             case ACPI_TYPE_INTEGER:
225 
226                 ObjDesc->Integer.Value = ACPI_TO_INTEGER (Val);
227                 break;
228 
229             case ACPI_TYPE_STRING:
230 
231                 /* Build an object around the static string */
232 
233                 ObjDesc->String.Length = (UINT32) strlen (Val);
234                 ObjDesc->String.Pointer = Val;
235                 ObjDesc->Common.Flags |= AOPOBJ_STATIC_POINTER;
236                 break;
237 
238             case ACPI_TYPE_MUTEX:
239 
240                 ObjDesc->Mutex.Node = NewNode;
241                 ObjDesc->Mutex.SyncLevel = (UINT8) (ACPI_TO_INTEGER (Val) - 1);
242 
243                 /* Create a mutex */
244 
245                 Status = AcpiOsCreateMutex (&ObjDesc->Mutex.OsMutex);
246                 if (ACPI_FAILURE (Status))
247                 {
248                     AcpiUtRemoveReference (ObjDesc);
249                     goto UnlockAndExit;
250                 }
251 
252                 /* Special case for ACPI Global Lock */
253 
254                 if (strcmp (InitVal->Name, "_GL_") == 0)
255                 {
256                     AcpiGbl_GlobalLockMutex = ObjDesc;
257 
258                     /* Create additional counting semaphore for global lock */
259 
260                     Status = AcpiOsCreateSemaphore (
261                         1, 0, &AcpiGbl_GlobalLockSemaphore);
262                     if (ACPI_FAILURE (Status))
263                     {
264                         AcpiUtRemoveReference (ObjDesc);
265                         goto UnlockAndExit;
266                     }
267                 }
268                 break;
269 
270             default:
271 
272                 ACPI_ERROR ((AE_INFO, "Unsupported initial type value 0x%X",
273                     InitVal->Type));
274                 AcpiUtRemoveReference (ObjDesc);
275                 ObjDesc = NULL;
276                 continue;
277             }
278 
279             /* Store pointer to value descriptor in the Node */
280 
281             Status = AcpiNsAttachObject (NewNode, ObjDesc,
282                 ObjDesc->Common.Type);
283 
284             /* Remove local reference to the object */
285 
286             AcpiUtRemoveReference (ObjDesc);
287         }
288     }
289 
290 UnlockAndExit:
291     (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
292 
293     /* Save a handle to "_GPE", it is always present */
294 
295     if (ACPI_SUCCESS (Status))
296     {
297         Status = AcpiNsGetNode (NULL, "\\_GPE", ACPI_NS_NO_UPSEARCH,
298             &AcpiGbl_FadtGpeDevice);
299     }
300 
301     return_ACPI_STATUS (Status);
302 }
303 
304 
305 /*******************************************************************************
306  *
307  * FUNCTION:    AcpiNsLookup
308  *
309  * PARAMETERS:  ScopeInfo       - Current scope info block
310  *              Pathname        - Search pathname, in internal format
311  *                                (as represented in the AML stream)
312  *              Type            - Type associated with name
313  *              InterpreterMode - IMODE_LOAD_PASS2 => add name if not found
314  *              Flags           - Flags describing the search restrictions
315  *              WalkState       - Current state of the walk
316  *              ReturnNode      - Where the Node is placed (if found
317  *                                or created successfully)
318  *
319  * RETURN:      Status
320  *
321  * DESCRIPTION: Find or enter the passed name in the name space.
322  *              Log an error if name not found in Exec mode.
323  *
324  * MUTEX:       Assumes namespace is locked.
325  *
326  ******************************************************************************/
327 
328 ACPI_STATUS
329 AcpiNsLookup (
330     ACPI_GENERIC_STATE      *ScopeInfo,
331     char                    *Pathname,
332     ACPI_OBJECT_TYPE        Type,
333     ACPI_INTERPRETER_MODE   InterpreterMode,
334     UINT32                  Flags,
335     ACPI_WALK_STATE         *WalkState,
336     ACPI_NAMESPACE_NODE     **ReturnNode)
337 {
338     ACPI_STATUS             Status;
339     char                    *Path = Pathname;
340     char                    *ExternalPath;
341     ACPI_NAMESPACE_NODE     *PrefixNode;
342     ACPI_NAMESPACE_NODE     *CurrentNode = NULL;
343     ACPI_NAMESPACE_NODE     *ThisNode = NULL;
344     UINT32                  NumSegments;
345     UINT32                  NumCarats;
346     ACPI_NAME               SimpleName;
347     ACPI_OBJECT_TYPE        TypeToCheckFor;
348     ACPI_OBJECT_TYPE        ThisSearchType;
349     UINT32                  SearchParentFlag = ACPI_NS_SEARCH_PARENT;
350     UINT32                  LocalFlags;
351     ACPI_INTERPRETER_MODE   LocalInterpreterMode;
352 
353 
354     ACPI_FUNCTION_TRACE (NsLookup);
355 
356 
357     if (!ReturnNode)
358     {
359         return_ACPI_STATUS (AE_BAD_PARAMETER);
360     }
361 
362     LocalFlags = Flags &
363         ~(ACPI_NS_ERROR_IF_FOUND | ACPI_NS_OVERRIDE_IF_FOUND |
364           ACPI_NS_SEARCH_PARENT);
365     *ReturnNode = ACPI_ENTRY_NOT_FOUND;
366     AcpiGbl_NsLookupCount++;
367 
368     if (!AcpiGbl_RootNode)
369     {
370         return_ACPI_STATUS (AE_NO_NAMESPACE);
371     }
372 
373     /* Get the prefix scope. A null scope means use the root scope */
374 
375     if ((!ScopeInfo) ||
376         (!ScopeInfo->Scope.Node))
377     {
378         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
379             "Null scope prefix, using root node (%p)\n",
380             AcpiGbl_RootNode));
381 
382         PrefixNode = AcpiGbl_RootNode;
383     }
384     else
385     {
386         PrefixNode = ScopeInfo->Scope.Node;
387         if (ACPI_GET_DESCRIPTOR_TYPE (PrefixNode) != ACPI_DESC_TYPE_NAMED)
388         {
389             ACPI_ERROR ((AE_INFO, "%p is not a namespace node [%s]",
390                 PrefixNode, AcpiUtGetDescriptorName (PrefixNode)));
391             return_ACPI_STATUS (AE_AML_INTERNAL);
392         }
393 
394         if (!(Flags & ACPI_NS_PREFIX_IS_SCOPE))
395         {
396             /*
397              * This node might not be a actual "scope" node (such as a
398              * Device/Method, etc.)  It could be a Package or other object
399              * node. Backup up the tree to find the containing scope node.
400              */
401             while (!AcpiNsOpensScope (PrefixNode->Type) &&
402                     PrefixNode->Type != ACPI_TYPE_ANY)
403             {
404                 PrefixNode = PrefixNode->Parent;
405             }
406         }
407     }
408 
409     /* Save type. TBD: may be no longer necessary */
410 
411     TypeToCheckFor = Type;
412 
413     /*
414      * Begin examination of the actual pathname
415      */
416     if (!Pathname)
417     {
418         /* A Null NamePath is allowed and refers to the root */
419 
420         NumSegments = 0;
421         ThisNode = AcpiGbl_RootNode;
422         Path = "";
423 
424         ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
425             "Null Pathname (Zero segments), Flags=%X\n", Flags));
426     }
427     else
428     {
429         /*
430          * Name pointer is valid (and must be in internal name format)
431          *
432          * Check for scope prefixes:
433          *
434          * As represented in the AML stream, a namepath consists of an
435          * optional scope prefix followed by a name segment part.
436          *
437          * If present, the scope prefix is either a Root Prefix (in
438          * which case the name is fully qualified), or one or more
439          * Parent Prefixes (in which case the name's scope is relative
440          * to the current scope).
441          */
442         if (*Path == (UINT8) AML_ROOT_PREFIX)
443         {
444             /* Pathname is fully qualified, start from the root */
445 
446             ThisNode = AcpiGbl_RootNode;
447             SearchParentFlag = ACPI_NS_NO_UPSEARCH;
448 
449             /* Point to name segment part */
450 
451             Path++;
452 
453             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
454                 "Path is absolute from root [%p]\n", ThisNode));
455         }
456         else
457         {
458             /* Pathname is relative to current scope, start there */
459 
460             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
461                 "Searching relative to prefix scope [%4.4s] (%p)\n",
462                 AcpiUtGetNodeName (PrefixNode), PrefixNode));
463 
464             /*
465              * Handle multiple Parent Prefixes (carat) by just getting
466              * the parent node for each prefix instance.
467              */
468             ThisNode = PrefixNode;
469             NumCarats = 0;
470             while (*Path == (UINT8) AML_PARENT_PREFIX)
471             {
472                 /* Name is fully qualified, no search rules apply */
473 
474                 SearchParentFlag = ACPI_NS_NO_UPSEARCH;
475 
476                 /*
477                  * Point past this prefix to the name segment
478                  * part or the next Parent Prefix
479                  */
480                 Path++;
481 
482                 /* Backup to the parent node */
483 
484                 NumCarats++;
485                 ThisNode = ThisNode->Parent;
486                 if (!ThisNode)
487                 {
488                     /*
489                      * Current scope has no parent scope. Externalize
490                      * the internal path for error message.
491                      */
492                     Status = AcpiNsExternalizeName (ACPI_UINT32_MAX, Pathname,
493                         NULL, &ExternalPath);
494                     if (ACPI_SUCCESS (Status))
495                     {
496                         ACPI_ERROR ((AE_INFO,
497                             "%s: Path has too many parent prefixes (^)",
498                             ExternalPath));
499 
500                         ACPI_FREE (ExternalPath);
501                     }
502 
503                     return_ACPI_STATUS (AE_NOT_FOUND);
504                 }
505             }
506 
507             if (SearchParentFlag == ACPI_NS_NO_UPSEARCH)
508             {
509                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
510                     "Search scope is [%4.4s], path has %u carat(s)\n",
511                     AcpiUtGetNodeName (ThisNode), NumCarats));
512             }
513         }
514 
515         /*
516          * Determine the number of ACPI name segments in this pathname.
517          *
518          * The segment part consists of either:
519          *  - A Null name segment (0)
520          *  - A DualNamePrefix followed by two 4-byte name segments
521          *  - A MultiNamePrefix followed by a byte indicating the
522          *      number of segments and the segments themselves.
523          *  - A single 4-byte name segment
524          *
525          * Examine the name prefix opcode, if any, to determine the number of
526          * segments.
527          */
528         switch (*Path)
529         {
530         case 0:
531             /*
532              * Null name after a root or parent prefixes. We already
533              * have the correct target node and there are no name segments.
534              */
535             NumSegments  = 0;
536             Type = ThisNode->Type;
537 
538             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
539                 "Prefix-only Pathname (Zero name segments), Flags=%X\n",
540                 Flags));
541             break;
542 
543         case AML_DUAL_NAME_PREFIX:
544 
545             /* More than one NameSeg, search rules do not apply */
546 
547             SearchParentFlag = ACPI_NS_NO_UPSEARCH;
548 
549             /* Two segments, point to first name segment */
550 
551             NumSegments = 2;
552             Path++;
553 
554             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
555                 "Dual Pathname (2 segments, Flags=%X)\n", Flags));
556             break;
557 
558         case AML_MULTI_NAME_PREFIX:
559 
560             /* More than one NameSeg, search rules do not apply */
561 
562             SearchParentFlag = ACPI_NS_NO_UPSEARCH;
563 
564             /* Extract segment count, point to first name segment */
565 
566             Path++;
567             NumSegments = (UINT32) (UINT8) *Path;
568             Path++;
569 
570             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
571                 "Multi Pathname (%u Segments, Flags=%X)\n",
572                 NumSegments, Flags));
573             break;
574 
575         default:
576             /*
577              * Not a Null name, no Dual or Multi prefix, hence there is
578              * only one name segment and Pathname is already pointing to it.
579              */
580             NumSegments = 1;
581 
582             ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
583                 "Simple Pathname (1 segment, Flags=%X)\n", Flags));
584             break;
585         }
586 
587         ACPI_DEBUG_EXEC (AcpiNsPrintPathname (NumSegments, Path));
588     }
589 
590 
591     /*
592      * Search namespace for each segment of the name. Loop through and
593      * verify (or add to the namespace) each name segment.
594      *
595      * The object type is significant only at the last name
596      * segment. (We don't care about the types along the path, only
597      * the type of the final target object.)
598      */
599     ThisSearchType = ACPI_TYPE_ANY;
600     CurrentNode = ThisNode;
601 
602     while (NumSegments && CurrentNode)
603     {
604         NumSegments--;
605         if (!NumSegments)
606         {
607             /* This is the last segment, enable typechecking */
608 
609             ThisSearchType = Type;
610 
611             /*
612              * Only allow automatic parent search (search rules) if the caller
613              * requested it AND we have a single, non-fully-qualified NameSeg
614              */
615             if ((SearchParentFlag != ACPI_NS_NO_UPSEARCH) &&
616                 (Flags & ACPI_NS_SEARCH_PARENT))
617             {
618                 LocalFlags |= ACPI_NS_SEARCH_PARENT;
619             }
620 
621             /* Set error flag according to caller */
622 
623             if (Flags & ACPI_NS_ERROR_IF_FOUND)
624             {
625                 LocalFlags |= ACPI_NS_ERROR_IF_FOUND;
626             }
627 
628             /* Set override flag according to caller */
629 
630             if (Flags & ACPI_NS_OVERRIDE_IF_FOUND)
631             {
632                 LocalFlags |= ACPI_NS_OVERRIDE_IF_FOUND;
633             }
634         }
635 
636         /* Handle opcodes that create a new NameSeg via a full NamePath */
637 
638         LocalInterpreterMode = InterpreterMode;
639         if ((Flags & ACPI_NS_PREFIX_MUST_EXIST) && (NumSegments > 0))
640         {
641             /* Every element of the path must exist (except for the final NameSeg) */
642 
643             LocalInterpreterMode = ACPI_IMODE_EXECUTE;
644         }
645 
646         /* Extract one ACPI name from the front of the pathname */
647 
648         ACPI_MOVE_32_TO_32 (&SimpleName, Path);
649 
650         /* Try to find the single (4 character) ACPI name */
651 
652         Status = AcpiNsSearchAndEnter (SimpleName, WalkState, CurrentNode,
653             LocalInterpreterMode, ThisSearchType, LocalFlags, &ThisNode);
654         if (ACPI_FAILURE (Status))
655         {
656             if (Status == AE_NOT_FOUND)
657             {
658 #if !defined ACPI_ASL_COMPILER /* Note: iASL reports this error by itself, not needed here */
659                 if (Flags & ACPI_NS_PREFIX_MUST_EXIST)
660                 {
661                     AcpiOsPrintf (ACPI_MSG_BIOS_ERROR
662                         "Object does not exist: %4.4s\n", (char *) &SimpleName);
663                 }
664 #endif
665                 /* Name not found in ACPI namespace */
666 
667                 ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
668                     "Name [%4.4s] not found in scope [%4.4s] %p\n",
669                     (char *) &SimpleName, (char *) &CurrentNode->Name,
670                     CurrentNode));
671             }
672 
673 #ifdef ACPI_EXEC_APP
674             if ((Status == AE_ALREADY_EXISTS) &&
675                 (ThisNode->Flags & ANOBJ_NODE_EARLY_INIT))
676             {
677                 ThisNode->Flags &= ~ANOBJ_NODE_EARLY_INIT;
678                 Status = AE_OK;
679             }
680 #endif
681 
682 #ifdef ACPI_ASL_COMPILER
683             /*
684              * If this ACPI name already exists within the namespace as an
685              * external declaration, then mark the external as a conflicting
686              * declaration and proceed to process the current node as if it did
687              * not exist in the namespace. If this node is not processed as
688              * normal, then it could cause improper namespace resolution
689              * by failing to open a new scope.
690              */
691             if (AcpiGbl_DisasmFlag &&
692                 (Status == AE_ALREADY_EXISTS) &&
693                 ((ThisNode->Flags & ANOBJ_IS_EXTERNAL) ||
694                     (WalkState && WalkState->Opcode == AML_EXTERNAL_OP)))
695             {
696                 ThisNode->Flags &= ~ANOBJ_IS_EXTERNAL;
697                 ThisNode->Type = (UINT8)ThisSearchType;
698                 if (WalkState->Opcode != AML_EXTERNAL_OP)
699                 {
700                     AcpiDmMarkExternalConflict (ThisNode);
701                 }
702                 break;
703             }
704 #endif
705 
706             *ReturnNode = ThisNode;
707             return_ACPI_STATUS (Status);
708         }
709 
710         /* More segments to follow? */
711 
712         if (NumSegments > 0)
713         {
714             /*
715              * If we have an alias to an object that opens a scope (such as a
716              * device or processor), we need to dereference the alias here so
717              * that we can access any children of the original node (via the
718              * remaining segments).
719              */
720             if (ThisNode->Type == ACPI_TYPE_LOCAL_ALIAS)
721             {
722                 if (!ThisNode->Object)
723                 {
724                     return_ACPI_STATUS (AE_NOT_EXIST);
725                 }
726 
727                 if (AcpiNsOpensScope (((ACPI_NAMESPACE_NODE *)
728                         ThisNode->Object)->Type))
729                 {
730                     ThisNode = (ACPI_NAMESPACE_NODE *) ThisNode->Object;
731                 }
732             }
733         }
734 
735         /* Special handling for the last segment (NumSegments == 0) */
736 
737         else
738         {
739             /*
740              * Sanity typecheck of the target object:
741              *
742              * If 1) This is the last segment (NumSegments == 0)
743              *    2) And we are looking for a specific type
744              *       (Not checking for TYPE_ANY)
745              *    3) Which is not an alias
746              *    4) Which is not a local type (TYPE_SCOPE)
747              *    5) And the type of target object is known (not TYPE_ANY)
748              *    6) And target object does not match what we are looking for
749              *
750              * Then we have a type mismatch. Just warn and ignore it.
751              */
752             if ((TypeToCheckFor != ACPI_TYPE_ANY)                   &&
753                 (TypeToCheckFor != ACPI_TYPE_LOCAL_ALIAS)           &&
754                 (TypeToCheckFor != ACPI_TYPE_LOCAL_METHOD_ALIAS)    &&
755                 (TypeToCheckFor != ACPI_TYPE_LOCAL_SCOPE)           &&
756                 (ThisNode->Type != ACPI_TYPE_ANY)                   &&
757                 (ThisNode->Type != TypeToCheckFor))
758             {
759                 /* Complain about a type mismatch */
760 
761                 ACPI_WARNING ((AE_INFO,
762                     "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
763                     ACPI_CAST_PTR (char, &SimpleName),
764                     AcpiUtGetTypeName (ThisNode->Type),
765                     AcpiUtGetTypeName (TypeToCheckFor)));
766             }
767 
768             /*
769              * If this is the last name segment and we are not looking for a
770              * specific type, but the type of found object is known, use that
771              * type to (later) see if it opens a scope.
772              */
773             if (Type == ACPI_TYPE_ANY)
774             {
775                 Type = ThisNode->Type;
776             }
777         }
778 
779         /* Point to next name segment and make this node current */
780 
781         Path += ACPI_NAMESEG_SIZE;
782         CurrentNode = ThisNode;
783     }
784 
785     /* Always check if we need to open a new scope */
786 
787     if (!(Flags & ACPI_NS_DONT_OPEN_SCOPE) && (WalkState))
788     {
789         /*
790          * If entry is a type which opens a scope, push the new scope on the
791          * scope stack.
792          */
793         if (AcpiNsOpensScope (Type))
794         {
795             Status = AcpiDsScopeStackPush (ThisNode, Type, WalkState);
796             if (ACPI_FAILURE (Status))
797             {
798                 return_ACPI_STATUS (Status);
799             }
800         }
801     }
802 
803 #ifdef ACPI_EXEC_APP
804     if (Flags & ACPI_NS_EARLY_INIT)
805     {
806         ThisNode->Flags |= ANOBJ_NODE_EARLY_INIT;
807     }
808 #endif
809 
810     *ReturnNode = ThisNode;
811     return_ACPI_STATUS (AE_OK);
812 }
813