1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /******************************************************************************
3 *
4 * Module Name: dscontrol - Support for execution control opcodes -
5 * if/else/while/return
6 *
7 * Copyright (C) 2000 - 2019, Intel Corp.
8 *
9 *****************************************************************************/
10
11 #include <acpi/acpi.h>
12 #include "accommon.h"
13 #include "amlcode.h"
14 #include "acdispat.h"
15 #include "acinterp.h"
16 #include "acdebug.h"
17
18 #define _COMPONENT ACPI_DISPATCHER
19 ACPI_MODULE_NAME("dscontrol")
20
21 /*******************************************************************************
22 *
23 * FUNCTION: acpi_ds_exec_begin_control_op
24 *
25 * PARAMETERS: walk_list - The list that owns the walk stack
26 * op - The control Op
27 *
28 * RETURN: Status
29 *
30 * DESCRIPTION: Handles all control ops encountered during control method
31 * execution.
32 *
33 ******************************************************************************/
34 acpi_status
35 acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state,
36 union acpi_parse_object *op)
37 {
38 acpi_status status = AE_OK;
39 union acpi_generic_state *control_state;
40
41 ACPI_FUNCTION_NAME(ds_exec_begin_control_op);
42
43 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Op=%p Opcode=%2.2X State=%p\n",
44 op, op->common.aml_opcode, walk_state));
45
46 switch (op->common.aml_opcode) {
47 case AML_WHILE_OP:
48 /*
49 * If this is an additional iteration of a while loop, continue.
50 * There is no need to allocate a new control state.
51 */
52 if (walk_state->control_state) {
53 if (walk_state->control_state->control.
54 aml_predicate_start ==
55 (walk_state->parser_state.aml - 1)) {
56
57 /* Reset the state to start-of-loop */
58
59 walk_state->control_state->common.state =
60 ACPI_CONTROL_CONDITIONAL_EXECUTING;
61 break;
62 }
63 }
64
65 /*lint -fallthrough */
66
67 case AML_IF_OP:
68 /*
69 * IF/WHILE: Create a new control state to manage these
70 * constructs. We need to manage these as a stack, in order
71 * to handle nesting.
72 */
73 control_state = acpi_ut_create_control_state();
74 if (!control_state) {
75 status = AE_NO_MEMORY;
76 break;
77 }
78 /*
79 * Save a pointer to the predicate for multiple executions
80 * of a loop
81 */
82 control_state->control.aml_predicate_start =
83 walk_state->parser_state.aml - 1;
84 control_state->control.package_end =
85 walk_state->parser_state.pkg_end;
86 control_state->control.opcode = op->common.aml_opcode;
87 control_state->control.loop_timeout = acpi_os_get_timer() +
88 (u64)(acpi_gbl_max_loop_iterations * ACPI_100NSEC_PER_SEC);
89
90 /* Push the control state on this walk's control stack */
91
92 acpi_ut_push_generic_state(&walk_state->control_state,
93 control_state);
94 break;
95
96 case AML_ELSE_OP:
97
98 /* Predicate is in the state object */
99 /* If predicate is true, the IF was executed, ignore ELSE part */
100
101 if (walk_state->last_predicate) {
102 status = AE_CTRL_TRUE;
103 }
104
105 break;
106
107 case AML_RETURN_OP:
108
109 break;
110
111 default:
112
113 break;
114 }
115
116 return (status);
117 }
118
119 /*******************************************************************************
120 *
121 * FUNCTION: acpi_ds_exec_end_control_op
122 *
123 * PARAMETERS: walk_list - The list that owns the walk stack
124 * op - The control Op
125 *
126 * RETURN: Status
127 *
128 * DESCRIPTION: Handles all control ops encountered during control method
129 * execution.
130 *
131 ******************************************************************************/
132
133 acpi_status
134 acpi_ds_exec_end_control_op(struct acpi_walk_state *walk_state,
135 union acpi_parse_object *op)
136 {
137 acpi_status status = AE_OK;
138 union acpi_generic_state *control_state;
139
140 ACPI_FUNCTION_NAME(ds_exec_end_control_op);
141
142 switch (op->common.aml_opcode) {
143 case AML_IF_OP:
144
145 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[IF_OP] Op=%p\n", op));
146
147 /*
148 * Save the result of the predicate in case there is an
149 * ELSE to come
150 */
151 walk_state->last_predicate =
152 (u8)walk_state->control_state->common.value;
153
154 /*
155 * Pop the control state that was created at the start
156 * of the IF and free it
157 */
158 control_state =
159 acpi_ut_pop_generic_state(&walk_state->control_state);
160 acpi_ut_delete_generic_state(control_state);
161 break;
162
163 case AML_ELSE_OP:
164
165 break;
166
167 case AML_WHILE_OP:
168
169 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op));
170
171 control_state = walk_state->control_state;
172 if (control_state->common.value) {
173
174 /* Predicate was true, the body of the loop was just executed */
175
176 /*
177 * This infinite loop detection mechanism allows the interpreter
178 * to escape possibly infinite loops. This can occur in poorly
179 * written AML when the hardware does not respond within a while
180 * loop and the loop does not implement a timeout.
181 */
182 if (ACPI_TIME_AFTER(acpi_os_get_timer(),
183 control_state->control.
184 loop_timeout)) {
185 status = AE_AML_LOOP_TIMEOUT;
186 break;
187 }
188
189 /*
190 * Go back and evaluate the predicate and maybe execute the loop
191 * another time
192 */
193 status = AE_CTRL_PENDING;
194 walk_state->aml_last_while =
195 control_state->control.aml_predicate_start;
196 break;
197 }
198
199 /* Predicate was false, terminate this while loop */
200
201 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
202 "[WHILE_OP] termination! Op=%p\n", op));
203
204 /* Pop this control state and free it */
205
206 control_state =
207 acpi_ut_pop_generic_state(&walk_state->control_state);
208 acpi_ut_delete_generic_state(control_state);
209 break;
210
211 case AML_RETURN_OP:
212
213 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
214 "[RETURN_OP] Op=%p Arg=%p\n", op,
215 op->common.value.arg));
216
217 /*
218 * One optional operand -- the return value
219 * It can be either an immediate operand or a result that
220 * has been bubbled up the tree
221 */
222 if (op->common.value.arg) {
223
224 /* Since we have a real Return(), delete any implicit return */
225
226 acpi_ds_clear_implicit_return(walk_state);
227
228 /* Return statement has an immediate operand */
229
230 status =
231 acpi_ds_create_operands(walk_state,
232 op->common.value.arg);
233 if (ACPI_FAILURE(status)) {
234 return (status);
235 }
236
237 /*
238 * If value being returned is a Reference (such as
239 * an arg or local), resolve it now because it may
240 * cease to exist at the end of the method.
241 */
242 status =
243 acpi_ex_resolve_to_value(&walk_state->operands[0],
244 walk_state);
245 if (ACPI_FAILURE(status)) {
246 return (status);
247 }
248
249 /*
250 * Get the return value and save as the last result
251 * value. This is the only place where walk_state->return_desc
252 * is set to anything other than zero!
253 */
254 walk_state->return_desc = walk_state->operands[0];
255 } else if (walk_state->result_count) {
256
257 /* Since we have a real Return(), delete any implicit return */
258
259 acpi_ds_clear_implicit_return(walk_state);
260
261 /*
262 * The return value has come from a previous calculation.
263 *
264 * If value being returned is a Reference (such as
265 * an arg or local), resolve it now because it may
266 * cease to exist at the end of the method.
267 *
268 * Allow references created by the Index operator to return
269 * unchanged.
270 */
271 if ((ACPI_GET_DESCRIPTOR_TYPE
272 (walk_state->results->results.obj_desc[0]) ==
273 ACPI_DESC_TYPE_OPERAND)
274 && ((walk_state->results->results.obj_desc[0])->
275 common.type == ACPI_TYPE_LOCAL_REFERENCE)
276 && ((walk_state->results->results.obj_desc[0])->
277 reference.class != ACPI_REFCLASS_INDEX)) {
278 status =
279 acpi_ex_resolve_to_value(&walk_state->
280 results->results.
281 obj_desc[0],
282 walk_state);
283 if (ACPI_FAILURE(status)) {
284 return (status);
285 }
286 }
287
288 walk_state->return_desc =
289 walk_state->results->results.obj_desc[0];
290 } else {
291 /* No return operand */
292
293 if (walk_state->num_operands) {
294 acpi_ut_remove_reference(walk_state->
295 operands[0]);
296 }
297
298 walk_state->operands[0] = NULL;
299 walk_state->num_operands = 0;
300 walk_state->return_desc = NULL;
301 }
302
303 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
304 "Completed RETURN_OP State=%p, RetVal=%p\n",
305 walk_state, walk_state->return_desc));
306
307 /* End the control method execution right now */
308
309 status = AE_CTRL_TERMINATE;
310 break;
311
312 case AML_NOOP_OP:
313
314 /* Just do nothing! */
315
316 break;
317
318 case AML_BREAKPOINT_OP:
319
320 acpi_db_signal_break_point(walk_state);
321
322 /* Call to the OSL in case OS wants a piece of the action */
323
324 status = acpi_os_signal(ACPI_SIGNAL_BREAKPOINT,
325 "Executed AML Breakpoint opcode");
326 break;
327
328 case AML_BREAK_OP:
329 case AML_CONTINUE_OP: /* ACPI 2.0 */
330
331 /* Pop and delete control states until we find a while */
332
333 while (walk_state->control_state &&
334 (walk_state->control_state->control.opcode !=
335 AML_WHILE_OP)) {
336 control_state =
337 acpi_ut_pop_generic_state(&walk_state->
338 control_state);
339 acpi_ut_delete_generic_state(control_state);
340 }
341
342 /* No while found? */
343
344 if (!walk_state->control_state) {
345 return (AE_AML_NO_WHILE);
346 }
347
348 /* Was: walk_state->aml_last_while = walk_state->control_state->Control.aml_predicate_start; */
349
350 walk_state->aml_last_while =
351 walk_state->control_state->control.package_end;
352
353 /* Return status depending on opcode */
354
355 if (op->common.aml_opcode == AML_BREAK_OP) {
356 status = AE_CTRL_BREAK;
357 } else {
358 status = AE_CTRL_CONTINUE;
359 }
360 break;
361
362 default:
363
364 ACPI_ERROR((AE_INFO, "Unknown control opcode=0x%X Op=%p",
365 op->common.aml_opcode, op));
366
367 status = AE_AML_BAD_OPCODE;
368 break;
369 }
370
371 return (status);
372 }