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Viewing changes to drivers/acpi/acpica/psparse.c

  • Committer: Package Import Robot
  • Author(s): Alessio Igor Bogani
  • Date: 2011-10-26 11:13:05 UTC
  • Revision ID: package-import@ubuntu.com-20111026111305-tz023xykf0i6eosh
Tags: upstream-3.2.0
Import upstream version 3.2.0

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drivers/acpi/acpica/psparse.c
 
1
/******************************************************************************
 
2
 *
 
3
 * Module Name: psparse - Parser top level AML parse routines
 
4
 *
 
5
 *****************************************************************************/
 
6
 
 
7
/*
 
8
 * Copyright (C) 2000 - 2011, 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
/*
 
45
 * Parse the AML and build an operation tree as most interpreters,
 
46
 * like Perl, do.  Parsing is done by hand rather than with a YACC
 
47
 * generated parser to tightly constrain stack and dynamic memory
 
48
 * usage.  At the same time, parsing is kept flexible and the code
 
49
 * fairly compact by parsing based on a list of AML opcode
 
50
 * templates in aml_op_info[]
 
51
 */
 
52
 
 
53
#include <acpi/acpi.h>
 
54
#include "accommon.h"
 
55
#include "acparser.h"
 
56
#include "acdispat.h"
 
57
#include "amlcode.h"
 
58
#include "acinterp.h"
 
59
 
 
60
#define _COMPONENT          ACPI_PARSER
 
61
ACPI_MODULE_NAME("psparse")
 
62
 
 
63
/*******************************************************************************
 
64
 *
 
65
 * FUNCTION:    acpi_ps_get_opcode_size
 
66
 *
 
67
 * PARAMETERS:  Opcode          - An AML opcode
 
68
 *
 
69
 * RETURN:      Size of the opcode, in bytes (1 or 2)
 
70
 *
 
71
 * DESCRIPTION: Get the size of the current opcode.
 
72
 *
 
73
 ******************************************************************************/
 
74
u32 acpi_ps_get_opcode_size(u32 opcode)
 
75
{
 
76
 
 
77
        /* Extended (2-byte) opcode if > 255 */
 
78
 
 
79
        if (opcode > 0x00FF) {
 
80
                return (2);
 
81
        }
 
82
 
 
83
        /* Otherwise, just a single byte opcode */
 
84
 
 
85
        return (1);
 
86
}
 
87
 
 
88
/*******************************************************************************
 
89
 *
 
90
 * FUNCTION:    acpi_ps_peek_opcode
 
91
 *
 
92
 * PARAMETERS:  parser_state        - A parser state object
 
93
 *
 
94
 * RETURN:      Next AML opcode
 
95
 *
 
96
 * DESCRIPTION: Get next AML opcode (without incrementing AML pointer)
 
97
 *
 
98
 ******************************************************************************/
 
99
 
 
100
u16 acpi_ps_peek_opcode(struct acpi_parse_state * parser_state)
 
101
{
 
102
        u8 *aml;
 
103
        u16 opcode;
 
104
 
 
105
        aml = parser_state->aml;
 
106
        opcode = (u16) ACPI_GET8(aml);
 
107
 
 
108
        if (opcode == AML_EXTENDED_OP_PREFIX) {
 
109
 
 
110
                /* Extended opcode, get the second opcode byte */
 
111
 
 
112
                aml++;
 
113
                opcode = (u16) ((opcode << 8) | ACPI_GET8(aml));
 
114
        }
 
115
 
 
116
        return (opcode);
 
117
}
 
118
 
 
119
/*******************************************************************************
 
120
 *
 
121
 * FUNCTION:    acpi_ps_complete_this_op
 
122
 *
 
123
 * PARAMETERS:  walk_state      - Current State
 
124
 *              Op              - Op to complete
 
125
 *
 
126
 * RETURN:      Status
 
127
 *
 
128
 * DESCRIPTION: Perform any cleanup at the completion of an Op.
 
129
 *
 
130
 ******************************************************************************/
 
131
 
 
132
acpi_status
 
133
acpi_ps_complete_this_op(struct acpi_walk_state * walk_state,
 
134
                         union acpi_parse_object * op)
 
135
{
 
136
        union acpi_parse_object *prev;
 
137
        union acpi_parse_object *next;
 
138
        const struct acpi_opcode_info *parent_info;
 
139
        union acpi_parse_object *replacement_op = NULL;
 
140
        acpi_status status = AE_OK;
 
141
 
 
142
        ACPI_FUNCTION_TRACE_PTR(ps_complete_this_op, op);
 
143
 
 
144
        /* Check for null Op, can happen if AML code is corrupt */
 
145
 
 
146
        if (!op) {
 
147
                return_ACPI_STATUS(AE_OK);      /* OK for now */
 
148
        }
 
149
 
 
150
        /* Delete this op and the subtree below it if asked to */
 
151
 
 
152
        if (((walk_state->parse_flags & ACPI_PARSE_TREE_MASK) !=
 
153
             ACPI_PARSE_DELETE_TREE)
 
154
            || (walk_state->op_info->class == AML_CLASS_ARGUMENT)) {
 
155
                return_ACPI_STATUS(AE_OK);
 
156
        }
 
157
 
 
158
        /* Make sure that we only delete this subtree */
 
159
 
 
160
        if (op->common.parent) {
 
161
                prev = op->common.parent->common.value.arg;
 
162
                if (!prev) {
 
163
 
 
164
                        /* Nothing more to do */
 
165
 
 
166
                        goto cleanup;
 
167
                }
 
168
 
 
169
                /*
 
170
                 * Check if we need to replace the operator and its subtree
 
171
                 * with a return value op (placeholder op)
 
172
                 */
 
173
                parent_info =
 
174
                    acpi_ps_get_opcode_info(op->common.parent->common.
 
175
                                            aml_opcode);
 
176
 
 
177
                switch (parent_info->class) {
 
178
                case AML_CLASS_CONTROL:
 
179
                        break;
 
180
 
 
181
                case AML_CLASS_CREATE:
 
182
 
 
183
                        /*
 
184
                         * These opcodes contain term_arg operands. The current
 
185
                         * op must be replaced by a placeholder return op
 
186
                         */
 
187
                        replacement_op =
 
188
                            acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
 
189
                        if (!replacement_op) {
 
190
                                status = AE_NO_MEMORY;
 
191
                        }
 
192
                        break;
 
193
 
 
194
                case AML_CLASS_NAMED_OBJECT:
 
195
 
 
196
                        /*
 
197
                         * These opcodes contain term_arg operands. The current
 
198
                         * op must be replaced by a placeholder return op
 
199
                         */
 
200
                        if ((op->common.parent->common.aml_opcode ==
 
201
                             AML_REGION_OP)
 
202
                            || (op->common.parent->common.aml_opcode ==
 
203
                                AML_DATA_REGION_OP)
 
204
                            || (op->common.parent->common.aml_opcode ==
 
205
                                AML_BUFFER_OP)
 
206
                            || (op->common.parent->common.aml_opcode ==
 
207
                                AML_PACKAGE_OP)
 
208
                            || (op->common.parent->common.aml_opcode ==
 
209
                                AML_BANK_FIELD_OP)
 
210
                            || (op->common.parent->common.aml_opcode ==
 
211
                                AML_VAR_PACKAGE_OP)) {
 
212
                                replacement_op =
 
213
                                    acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
 
214
                                if (!replacement_op) {
 
215
                                        status = AE_NO_MEMORY;
 
216
                                }
 
217
                        } else
 
218
                            if ((op->common.parent->common.aml_opcode ==
 
219
                                 AML_NAME_OP)
 
220
                                && (walk_state->pass_number <=
 
221
                                    ACPI_IMODE_LOAD_PASS2)) {
 
222
                                if ((op->common.aml_opcode == AML_BUFFER_OP)
 
223
                                    || (op->common.aml_opcode == AML_PACKAGE_OP)
 
224
                                    || (op->common.aml_opcode ==
 
225
                                        AML_VAR_PACKAGE_OP)) {
 
226
                                        replacement_op =
 
227
                                            acpi_ps_alloc_op(op->common.
 
228
                                                             aml_opcode);
 
229
                                        if (!replacement_op) {
 
230
                                                status = AE_NO_MEMORY;
 
231
                                        } else {
 
232
                                                replacement_op->named.data =
 
233
                                                    op->named.data;
 
234
                                                replacement_op->named.length =
 
235
                                                    op->named.length;
 
236
                                        }
 
237
                                }
 
238
                        }
 
239
                        break;
 
240
 
 
241
                default:
 
242
 
 
243
                        replacement_op =
 
244
                            acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
 
245
                        if (!replacement_op) {
 
246
                                status = AE_NO_MEMORY;
 
247
                        }
 
248
                }
 
249
 
 
250
                /* We must unlink this op from the parent tree */
 
251
 
 
252
                if (prev == op) {
 
253
 
 
254
                        /* This op is the first in the list */
 
255
 
 
256
                        if (replacement_op) {
 
257
                                replacement_op->common.parent =
 
258
                                    op->common.parent;
 
259
                                replacement_op->common.value.arg = NULL;
 
260
                                replacement_op->common.node = op->common.node;
 
261
                                op->common.parent->common.value.arg =
 
262
                                    replacement_op;
 
263
                                replacement_op->common.next = op->common.next;
 
264
                        } else {
 
265
                                op->common.parent->common.value.arg =
 
266
                                    op->common.next;
 
267
                        }
 
268
                }
 
269
 
 
270
                /* Search the parent list */
 
271
 
 
272
                else
 
273
                        while (prev) {
 
274
 
 
275
                                /* Traverse all siblings in the parent's argument list */
 
276
 
 
277
                                next = prev->common.next;
 
278
                                if (next == op) {
 
279
                                        if (replacement_op) {
 
280
                                                replacement_op->common.parent =
 
281
                                                    op->common.parent;
 
282
                                                replacement_op->common.value.
 
283
                                                    arg = NULL;
 
284
                                                replacement_op->common.node =
 
285
                                                    op->common.node;
 
286
                                                prev->common.next =
 
287
                                                    replacement_op;
 
288
                                                replacement_op->common.next =
 
289
                                                    op->common.next;
 
290
                                                next = NULL;
 
291
                                        } else {
 
292
                                                prev->common.next =
 
293
                                                    op->common.next;
 
294
                                                next = NULL;
 
295
                                        }
 
296
                                }
 
297
                                prev = next;
 
298
                        }
 
299
        }
 
300
 
 
301
      cleanup:
 
302
 
 
303
        /* Now we can actually delete the subtree rooted at Op */
 
304
 
 
305
        acpi_ps_delete_parse_tree(op);
 
306
        return_ACPI_STATUS(status);
 
307
}
 
308
 
 
309
/*******************************************************************************
 
310
 *
 
311
 * FUNCTION:    acpi_ps_next_parse_state
 
312
 *
 
313
 * PARAMETERS:  walk_state          - Current state
 
314
 *              Op                  - Current parse op
 
315
 *              callback_status     - Status from previous operation
 
316
 *
 
317
 * RETURN:      Status
 
318
 *
 
319
 * DESCRIPTION: Update the parser state based upon the return exception from
 
320
 *              the parser callback.
 
321
 *
 
322
 ******************************************************************************/
 
323
 
 
324
acpi_status
 
325
acpi_ps_next_parse_state(struct acpi_walk_state *walk_state,
 
326
                         union acpi_parse_object *op,
 
327
                         acpi_status callback_status)
 
328
{
 
329
        struct acpi_parse_state *parser_state = &walk_state->parser_state;
 
330
        acpi_status status = AE_CTRL_PENDING;
 
331
 
 
332
        ACPI_FUNCTION_TRACE_PTR(ps_next_parse_state, op);
 
333
 
 
334
        switch (callback_status) {
 
335
        case AE_CTRL_TERMINATE:
 
336
                /*
 
337
                 * A control method was terminated via a RETURN statement.
 
338
                 * The walk of this method is complete.
 
339
                 */
 
340
                parser_state->aml = parser_state->aml_end;
 
341
                status = AE_CTRL_TERMINATE;
 
342
                break;
 
343
 
 
344
        case AE_CTRL_BREAK:
 
345
 
 
346
                parser_state->aml = walk_state->aml_last_while;
 
347
                walk_state->control_state->common.value = FALSE;
 
348
                status = AE_CTRL_BREAK;
 
349
                break;
 
350
 
 
351
        case AE_CTRL_CONTINUE:
 
352
 
 
353
                parser_state->aml = walk_state->aml_last_while;
 
354
                status = AE_CTRL_CONTINUE;
 
355
                break;
 
356
 
 
357
        case AE_CTRL_PENDING:
 
358
 
 
359
                parser_state->aml = walk_state->aml_last_while;
 
360
                break;
 
361
 
 
362
#if 0
 
363
        case AE_CTRL_SKIP:
 
364
 
 
365
                parser_state->aml = parser_state->scope->parse_scope.pkg_end;
 
366
                status = AE_OK;
 
367
                break;
 
368
#endif
 
369
 
 
370
        case AE_CTRL_TRUE:
 
371
                /*
 
372
                 * Predicate of an IF was true, and we are at the matching ELSE.
 
373
                 * Just close out this package
 
374
                 */
 
375
                parser_state->aml = acpi_ps_get_next_package_end(parser_state);
 
376
                status = AE_CTRL_PENDING;
 
377
                break;
 
378
 
 
379
        case AE_CTRL_FALSE:
 
380
                /*
 
381
                 * Either an IF/WHILE Predicate was false or we encountered a BREAK
 
382
                 * opcode.  In both cases, we do not execute the rest of the
 
383
                 * package;  We simply close out the parent (finishing the walk of
 
384
                 * this branch of the tree) and continue execution at the parent
 
385
                 * level.
 
386
                 */
 
387
                parser_state->aml = parser_state->scope->parse_scope.pkg_end;
 
388
 
 
389
                /* In the case of a BREAK, just force a predicate (if any) to FALSE */
 
390
 
 
391
                walk_state->control_state->common.value = FALSE;
 
392
                status = AE_CTRL_END;
 
393
                break;
 
394
 
 
395
        case AE_CTRL_TRANSFER:
 
396
 
 
397
                /* A method call (invocation) -- transfer control */
 
398
 
 
399
                status = AE_CTRL_TRANSFER;
 
400
                walk_state->prev_op = op;
 
401
                walk_state->method_call_op = op;
 
402
                walk_state->method_call_node =
 
403
                    (op->common.value.arg)->common.node;
 
404
 
 
405
                /* Will return value (if any) be used by the caller? */
 
406
 
 
407
                walk_state->return_used =
 
408
                    acpi_ds_is_result_used(op, walk_state);
 
409
                break;
 
410
 
 
411
        default:
 
412
 
 
413
                status = callback_status;
 
414
                if ((callback_status & AE_CODE_MASK) == AE_CODE_CONTROL) {
 
415
                        status = AE_OK;
 
416
                }
 
417
                break;
 
418
        }
 
419
 
 
420
        return_ACPI_STATUS(status);
 
421
}
 
422
 
 
423
/*******************************************************************************
 
424
 *
 
425
 * FUNCTION:    acpi_ps_parse_aml
 
426
 *
 
427
 * PARAMETERS:  walk_state      - Current state
 
428
 *
 
429
 *
 
430
 * RETURN:      Status
 
431
 *
 
432
 * DESCRIPTION: Parse raw AML and return a tree of ops
 
433
 *
 
434
 ******************************************************************************/
 
435
 
 
436
acpi_status acpi_ps_parse_aml(struct acpi_walk_state *walk_state)
 
437
{
 
438
        acpi_status status;
 
439
        struct acpi_thread_state *thread;
 
440
        struct acpi_thread_state *prev_walk_list = acpi_gbl_current_walk_list;
 
441
        struct acpi_walk_state *previous_walk_state;
 
442
 
 
443
        ACPI_FUNCTION_TRACE(ps_parse_aml);
 
444
 
 
445
        ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 
446
                          "Entered with WalkState=%p Aml=%p size=%X\n",
 
447
                          walk_state, walk_state->parser_state.aml,
 
448
                          walk_state->parser_state.aml_size));
 
449
 
 
450
        if (!walk_state->parser_state.aml) {
 
451
                return_ACPI_STATUS(AE_NULL_OBJECT);
 
452
        }
 
453
 
 
454
        /* Create and initialize a new thread state */
 
455
 
 
456
        thread = acpi_ut_create_thread_state();
 
457
        if (!thread) {
 
458
                if (walk_state->method_desc) {
 
459
 
 
460
                        /* Executing a control method - additional cleanup */
 
461
 
 
462
                        acpi_ds_terminate_control_method(
 
463
                                walk_state->method_desc, walk_state);
 
464
                }
 
465
 
 
466
                acpi_ds_delete_walk_state(walk_state);
 
467
                return_ACPI_STATUS(AE_NO_MEMORY);
 
468
        }
 
469
 
 
470
        walk_state->thread = thread;
 
471
 
 
472
        /*
 
473
         * If executing a method, the starting sync_level is this method's
 
474
         * sync_level
 
475
         */
 
476
        if (walk_state->method_desc) {
 
477
                walk_state->thread->current_sync_level =
 
478
                    walk_state->method_desc->method.sync_level;
 
479
        }
 
480
 
 
481
        acpi_ds_push_walk_state(walk_state, thread);
 
482
 
 
483
        /*
 
484
         * This global allows the AML debugger to get a handle to the currently
 
485
         * executing control method.
 
486
         */
 
487
        acpi_gbl_current_walk_list = thread;
 
488
 
 
489
        /*
 
490
         * Execute the walk loop as long as there is a valid Walk State.  This
 
491
         * handles nested control method invocations without recursion.
 
492
         */
 
493
        ACPI_DEBUG_PRINT((ACPI_DB_PARSE, "State=%p\n", walk_state));
 
494
 
 
495
        status = AE_OK;
 
496
        while (walk_state) {
 
497
                if (ACPI_SUCCESS(status)) {
 
498
                        /*
 
499
                         * The parse_loop executes AML until the method terminates
 
500
                         * or calls another method.
 
501
                         */
 
502
                        status = acpi_ps_parse_loop(walk_state);
 
503
                }
 
504
 
 
505
                ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 
506
                                  "Completed one call to walk loop, %s State=%p\n",
 
507
                                  acpi_format_exception(status), walk_state));
 
508
 
 
509
                if (status == AE_CTRL_TRANSFER) {
 
510
                        /*
 
511
                         * A method call was detected.
 
512
                         * Transfer control to the called control method
 
513
                         */
 
514
                        status =
 
515
                            acpi_ds_call_control_method(thread, walk_state,
 
516
                                                        NULL);
 
517
                        if (ACPI_FAILURE(status)) {
 
518
                                status =
 
519
                                    acpi_ds_method_error(status, walk_state);
 
520
                        }
 
521
 
 
522
                        /*
 
523
                         * If the transfer to the new method method call worked, a new walk
 
524
                         * state was created -- get it
 
525
                         */
 
526
                        walk_state = acpi_ds_get_current_walk_state(thread);
 
527
                        continue;
 
528
                } else if (status == AE_CTRL_TERMINATE) {
 
529
                        status = AE_OK;
 
530
                } else if ((status != AE_OK) && (walk_state->method_desc)) {
 
531
 
 
532
                        /* Either the method parse or actual execution failed */
 
533
 
 
534
                        ACPI_ERROR_METHOD("Method parse/execution failed",
 
535
                                          walk_state->method_node, NULL,
 
536
                                          status);
 
537
 
 
538
                        /* Check for possible multi-thread reentrancy problem */
 
539
 
 
540
                        if ((status == AE_ALREADY_EXISTS) &&
 
541
                            (!(walk_state->method_desc->method.
 
542
                               info_flags & ACPI_METHOD_SERIALIZED))) {
 
543
                                /*
 
544
                                 * Method is not serialized and tried to create an object
 
545
                                 * twice. The probable cause is that the method cannot
 
546
                                 * handle reentrancy. Mark as "pending serialized" now, and
 
547
                                 * then mark "serialized" when the last thread exits.
 
548
                                 */
 
549
                                walk_state->method_desc->method.info_flags |=
 
550
                                    ACPI_METHOD_SERIALIZED_PENDING;
 
551
                        }
 
552
                }
 
553
 
 
554
                /* We are done with this walk, move on to the parent if any */
 
555
 
 
556
                walk_state = acpi_ds_pop_walk_state(thread);
 
557
 
 
558
                /* Reset the current scope to the beginning of scope stack */
 
559
 
 
560
                acpi_ds_scope_stack_clear(walk_state);
 
561
 
 
562
                /*
 
563
                 * If we just returned from the execution of a control method or if we
 
564
                 * encountered an error during the method parse phase, there's lots of
 
565
                 * cleanup to do
 
566
                 */
 
567
                if (((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) ==
 
568
                     ACPI_PARSE_EXECUTE) || (ACPI_FAILURE(status))) {
 
569
                        acpi_ds_terminate_control_method(walk_state->
 
570
                                                         method_desc,
 
571
                                                         walk_state);
 
572
                }
 
573
 
 
574
                /* Delete this walk state and all linked control states */
 
575
 
 
576
                acpi_ps_cleanup_scope(&walk_state->parser_state);
 
577
                previous_walk_state = walk_state;
 
578
 
 
579
                ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 
580
                                  "ReturnValue=%p, ImplicitValue=%p State=%p\n",
 
581
                                  walk_state->return_desc,
 
582
                                  walk_state->implicit_return_obj, walk_state));
 
583
 
 
584
                /* Check if we have restarted a preempted walk */
 
585
 
 
586
                walk_state = acpi_ds_get_current_walk_state(thread);
 
587
                if (walk_state) {
 
588
                        if (ACPI_SUCCESS(status)) {
 
589
                                /*
 
590
                                 * There is another walk state, restart it.
 
591
                                 * If the method return value is not used by the parent,
 
592
                                 * The object is deleted
 
593
                                 */
 
594
                                if (!previous_walk_state->return_desc) {
 
595
                                        /*
 
596
                                         * In slack mode execution, if there is no return value
 
597
                                         * we should implicitly return zero (0) as a default value.
 
598
                                         */
 
599
                                        if (acpi_gbl_enable_interpreter_slack &&
 
600
                                            !previous_walk_state->
 
601
                                            implicit_return_obj) {
 
602
                                                previous_walk_state->
 
603
                                                    implicit_return_obj =
 
604
                                                    acpi_ut_create_integer_object
 
605
                                                    ((u64) 0);
 
606
                                                if (!previous_walk_state->
 
607
                                                    implicit_return_obj) {
 
608
                                                        return_ACPI_STATUS
 
609
                                                            (AE_NO_MEMORY);
 
610
                                                }
 
611
                                        }
 
612
 
 
613
                                        /* Restart the calling control method */
 
614
 
 
615
                                        status =
 
616
                                            acpi_ds_restart_control_method
 
617
                                            (walk_state,
 
618
                                             previous_walk_state->
 
619
                                             implicit_return_obj);
 
620
                                } else {
 
621
                                        /*
 
622
                                         * We have a valid return value, delete any implicit
 
623
                                         * return value.
 
624
                                         */
 
625
                                        acpi_ds_clear_implicit_return
 
626
                                            (previous_walk_state);
 
627
 
 
628
                                        status =
 
629
                                            acpi_ds_restart_control_method
 
630
                                            (walk_state,
 
631
                                             previous_walk_state->return_desc);
 
632
                                }
 
633
                                if (ACPI_SUCCESS(status)) {
 
634
                                        walk_state->walk_type |=
 
635
                                            ACPI_WALK_METHOD_RESTART;
 
636
                                }
 
637
                        } else {
 
638
                                /* On error, delete any return object or implicit return */
 
639
 
 
640
                                acpi_ut_remove_reference(previous_walk_state->
 
641
                                                         return_desc);
 
642
                                acpi_ds_clear_implicit_return
 
643
                                    (previous_walk_state);
 
644
                        }
 
645
                }
 
646
 
 
647
                /*
 
648
                 * Just completed a 1st-level method, save the final internal return
 
649
                 * value (if any)
 
650
                 */
 
651
                else if (previous_walk_state->caller_return_desc) {
 
652
                        if (previous_walk_state->implicit_return_obj) {
 
653
                                *(previous_walk_state->caller_return_desc) =
 
654
                                    previous_walk_state->implicit_return_obj;
 
655
                        } else {
 
656
                                /* NULL if no return value */
 
657
 
 
658
                                *(previous_walk_state->caller_return_desc) =
 
659
                                    previous_walk_state->return_desc;
 
660
                        }
 
661
                } else {
 
662
                        if (previous_walk_state->return_desc) {
 
663
 
 
664
                                /* Caller doesn't want it, must delete it */
 
665
 
 
666
                                acpi_ut_remove_reference(previous_walk_state->
 
667
                                                         return_desc);
 
668
                        }
 
669
                        if (previous_walk_state->implicit_return_obj) {
 
670
 
 
671
                                /* Caller doesn't want it, must delete it */
 
672
 
 
673
                                acpi_ut_remove_reference(previous_walk_state->
 
674
                                                         implicit_return_obj);
 
675
                        }
 
676
                }
 
677
 
 
678
                acpi_ds_delete_walk_state(previous_walk_state);
 
679
        }
 
680
 
 
681
        /* Normal exit */
 
682
 
 
683
        acpi_ex_release_all_mutexes(thread);
 
684
        acpi_ut_delete_generic_state(ACPI_CAST_PTR
 
685
                                     (union acpi_generic_state, thread));
 
686
        acpi_gbl_current_walk_list = prev_walk_list;
 
687
        return_ACPI_STATUS(status);
 
688
}