LXR linux/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 - 2021, 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
  19ACPI_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 ******************************************************************************/
  34acpi_status
  35acpi_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                ACPI_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
 133acpi_status
 134acpi_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}
 373