Quelle  dscontrol.c   Sprache: C

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
 *
 * Module Name: dscontrol - Support for execution control opcodes -
 *                          if/else/while/return
 *
 * Copyright (C) 2000 - 2025, Intel Corp.
 *
 *****************************************************************************/

#include <acpi/acpi.h>
#include "accommon.h"
#include "amlcode.h"
#include "acdispat.h"
#include "acinterp.h"
#include "acdebug.h"

#define _COMPONENT          ACPI_DISPATCHER
ACPI_MODULE_NAME("dscontrol")

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_exec_begin_control_op
 *
 * PARAMETERS:  walk_list       - The list that owns the walk stack
 *              op              - The control Op
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Handles all control ops encountered during control method
 *              execution.
 *
 ******************************************************************************/
acpi_status
acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state,
         union acpi_parse_object *op)
{
 acpi_status status = AE_OK;
 union acpi_generic_state *control_state;

 ACPI_FUNCTION_NAME(ds_exec_begin_control_op);

 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Op=%p Opcode=%2.2X State=%p\n",
     op, op->common.aml_opcode, walk_state));

 switch (op->common.aml_opcode) {
 case AML_WHILE_OP:
  /*
 * If this is an additional iteration of a while loop, continue.
 * There is no need to allocate a new control state.
 */
  if (walk_state->control_state) {
   if (walk_state->control_state->control.
       aml_predicate_start ==
       (walk_state->parser_state.aml - 1)) {

    /* Reset the state to start-of-loop */

    walk_state->control_state->common.state =
        ACPI_CONTROL_CONDITIONAL_EXECUTING;
    break;
   }
  }

  ACPI_FALLTHROUGH;

 case AML_IF_OP:
  /*
 * IF/WHILE: Create a new control state to manage these
 * constructs. We need to manage these as a stack, in order
 * to handle nesting.
 */
  control_state = acpi_ut_create_control_state();
  if (!control_state) {
   status = AE_NO_MEMORY;
   break;
  }
  /*
 * Save a pointer to the predicate for multiple executions
 * of a loop
 */
  control_state->control.aml_predicate_start =
      walk_state->parser_state.aml - 1;
  control_state->control.package_end =
      walk_state->parser_state.pkg_end;
  control_state->control.opcode = op->common.aml_opcode;
  control_state->control.loop_timeout = acpi_os_get_timer() +
      ((u64)acpi_gbl_max_loop_iterations * ACPI_100NSEC_PER_SEC);

  /* Push the control state on this walk's control stack */

  acpi_ut_push_generic_state(&walk_state->control_state,
        control_state);
  break;

 case AML_ELSE_OP:

  /* Predicate is in the state object */
  /* If predicate is true, the IF was executed, ignore ELSE part */

  if (walk_state->last_predicate) {
   status = AE_CTRL_TRUE;
  }

  break;

 case AML_RETURN_OP:

  break;

 default:

  break;
 }

 return (status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_exec_end_control_op
 *
 * PARAMETERS:  walk_list       - The list that owns the walk stack
 *              op              - The control Op
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Handles all control ops encountered during control method
 *              execution.
 *
 ******************************************************************************/

acpi_status
acpi_ds_exec_end_control_op(struct acpi_walk_state *walk_state,
       union acpi_parse_object *op)
{
 acpi_status status = AE_OK;
 union acpi_generic_state *control_state;

 ACPI_FUNCTION_NAME(ds_exec_end_control_op);

 switch (op->common.aml_opcode) {
 case AML_IF_OP:

  ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[IF_OP] Op=%p\n", op));

  /*
 * Save the result of the predicate in case there is an
 * ELSE to come
 */
  walk_state->last_predicate =
      (u8)walk_state->control_state->common.value;

  /*
 * Pop the control state that was created at the start
 * of the IF and free it
 */
  control_state =
      acpi_ut_pop_generic_state(&walk_state->control_state);
  acpi_ut_delete_generic_state(control_state);
  break;

 case AML_ELSE_OP:

  break;

 case AML_WHILE_OP:

  ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op));

  control_state = walk_state->control_state;
  if (control_state->common.value) {

   /* Predicate was true, the body of the loop was just executed */

   /*
 * This infinite loop detection mechanism allows the interpreter
 * to escape possibly infinite loops. This can occur in poorly
 * written AML when the hardware does not respond within a while
 * loop and the loop does not implement a timeout.
 */
   if (ACPI_TIME_AFTER(acpi_os_get_timer(),
         control_state->control.
         loop_timeout)) {
    status = AE_AML_LOOP_TIMEOUT;
    break;
   }

   /*
 * Go back and evaluate the predicate and maybe execute the loop
 * another time
 */
   status = AE_CTRL_PENDING;
   walk_state->aml_last_while =
       control_state->control.aml_predicate_start;
   break;
  }

  /* Predicate was false, terminate this while loop */

  ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
      "[WHILE_OP] termination! Op=%p\n", op));

  /* Pop this control state and free it */

  control_state =
      acpi_ut_pop_generic_state(&walk_state->control_state);
  acpi_ut_delete_generic_state(control_state);
  break;

 case AML_RETURN_OP:

  ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
      "[RETURN_OP] Op=%p Arg=%p\n", op,
      op->common.value.arg));

  /*
 * One optional operand -- the return value
 * It can be either an immediate operand or a result that
 * has been bubbled up the tree
 */
  if (op->common.value.arg) {

   /* Since we have a real Return(), delete any implicit return */

   acpi_ds_clear_implicit_return(walk_state);

   /* Return statement has an immediate operand */

   status =
       acpi_ds_create_operands(walk_state,
          op->common.value.arg);
   if (ACPI_FAILURE(status)) {
    return (status);
   }

   /*
 * If value being returned is a Reference (such as
 * an arg or local), resolve it now because it may
 * cease to exist at the end of the method.
 */
   status =
       acpi_ex_resolve_to_value(&walk_state->operands[0],
           walk_state);
   if (ACPI_FAILURE(status)) {
    return (status);
   }

   /*
 * Get the return value and save as the last result
 * value. This is the only place where walk_state->return_desc
 * is set to anything other than zero!
 */
   walk_state->return_desc = walk_state->operands[0];
  } else if (walk_state->result_count) {

   /* Since we have a real Return(), delete any implicit return */

   acpi_ds_clear_implicit_return(walk_state);

   /*
 * The return value has come from a previous calculation.
 *
 * If value being returned is a Reference (such as
 * an arg or local), resolve it now because it may
 * cease to exist at the end of the method.
 *
 * Allow references created by the Index operator to return
 * unchanged.
 */
   if ((ACPI_GET_DESCRIPTOR_TYPE
        (walk_state->results->results.obj_desc[0]) ==
        ACPI_DESC_TYPE_OPERAND)
       && ((walk_state->results->results.obj_desc[0])->
    common.type == ACPI_TYPE_LOCAL_REFERENCE)
       && ((walk_state->results->results.obj_desc[0])->
    reference.class != ACPI_REFCLASS_INDEX)) {
    status =
        acpi_ex_resolve_to_value(&walk_state->
            results->results.
            obj_desc[0],
            walk_state);
    if (ACPI_FAILURE(status)) {
     return (status);
    }
   }

   walk_state->return_desc =
       walk_state->results->results.obj_desc[0];
  } else {
   /* No return operand */

   if (walk_state->num_operands) {
    acpi_ut_remove_reference(walk_state->
        operands[0]);
   }

   walk_state->operands[0] = NULL;
   walk_state->num_operands = 0;
   walk_state->return_desc = NULL;
  }

  ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
      "Completed RETURN_OP State=%p, RetVal=%p\n",
      walk_state, walk_state->return_desc));

  /* End the control method execution right now */

  status = AE_CTRL_TERMINATE;
  break;

 case AML_NOOP_OP:

  /* Just do nothing! */

  break;

 case AML_BREAKPOINT_OP:

  acpi_db_signal_break_point(walk_state);

  /* Call to the OSL in case OS wants a piece of the action */

  status = acpi_os_signal(ACPI_SIGNAL_BREAKPOINT,
     "Executed AML Breakpoint opcode");
  break;

 case AML_BREAK_OP:
 case AML_CONTINUE_OP: /* ACPI 2.0 */

  /* Pop and delete control states until we find a while */

  while (walk_state->control_state &&
         (walk_state->control_state->control.opcode !=
   AML_WHILE_OP)) {
   control_state =
       acpi_ut_pop_generic_state(&walk_state->
            control_state);
   acpi_ut_delete_generic_state(control_state);
  }

  /* No while found? */

  if (!walk_state->control_state) {
   return (AE_AML_NO_WHILE);
  }

  /* Was: walk_state->aml_last_while = walk_state->control_state->Control.aml_predicate_start; */

  walk_state->aml_last_while =
      walk_state->control_state->control.package_end;

  /* Return status depending on opcode */

  if (op->common.aml_opcode == AML_BREAK_OP) {
   status = AE_CTRL_BREAK;
  } else {
   status = AE_CTRL_CONTINUE;
  }
  break;

 default:

  ACPI_ERROR((AE_INFO, "Unknown control opcode=0x%X Op=%p",
       op->common.aml_opcode, op));

  status = AE_AML_BAD_OPCODE;
  break;
 }

 return (status);
}