dscontrol.c

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/******************************************************************************
 *
 * Module Name: dscontrol - Support for execution control opcodes -
 *                          if/else/while/return
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2012, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

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

        /*lint -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;

        /* 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 loop counter 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.
             */
            control_state->control.loop_count++;
            if (control_state->control.loop_count >
                ACPI_MAX_LOOP_ITERATIONS) {
                status = AE_AML_INFINITE_LOOP;
                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_BREAK_POINT_OP:

        /*
         * Set the single-step flag. This will cause the debugger (if present)
         * to break to the console within the AML debugger at the start of the
         * next AML instruction.
         */
        ACPI_DEBUGGER_EXEC(acpi_gbl_cm_single_step = TRUE);
        ACPI_DEBUGGER_EXEC(acpi_os_printf
                   ("**break** Executed AML BreakPoint opcode\n"));

        /* 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);
}