drivers/acpi/acpica/dscontrol.c

   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 - 2020, 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 }