// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
 *
 * Module Name: exmutex - ASL Mutex Acquire/Release functions
 *
 * Copyright (C) 2000 - 2021, Intel Corp.
 *
 *****************************************************************************/

#include <acpi/acpi.h>
#include "accommon.h"
#include "acinterp.h"
#include "acevents.h"

#define _COMPONENT          ACPI_EXECUTER
ACPI_MODULE_NAME("exmutex")

/* Local prototypes */
static void
acpi_ex_link_mutex(union acpi_operand_object *obj_desc,
                   struct acpi_thread_state *thread);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_unlink_mutex
 *
 * PARAMETERS:  obj_desc            - The mutex to be unlinked
 *
 * RETURN:      None
 *
 * DESCRIPTION: Remove a mutex from the "AcquiredMutex" list
 *
 ******************************************************************************/

void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc)
{
        struct acpi_thread_state *thread = obj_desc->mutex.owner_thread;

        if (!thread) {
                return;
        }

        /* Doubly linked list */

        if (obj_desc->mutex.next) {
                (obj_desc->mutex.next)->mutex.prev = obj_desc->mutex.prev;
        }

        if (obj_desc->mutex.prev) {
                (obj_desc->mutex.prev)->mutex.next = obj_desc->mutex.next;

                /*
                 * Migrate the previous sync level associated with this mutex to
                 * the previous mutex on the list so that it may be preserved.
                 * This handles the case where several mutexes have been acquired
                 * at the same level, but are not released in opposite order.
                 */
                (obj_desc->mutex.prev)->mutex.original_sync_level =
                    obj_desc->mutex.original_sync_level;
        } else {
                thread->acquired_mutex_list = obj_desc->mutex.next;
        }
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_link_mutex
 *
 * PARAMETERS:  obj_desc            - The mutex to be linked
 *              thread              - Current executing thread object
 *
 * RETURN:      None
 *
 * DESCRIPTION: Add a mutex to the "AcquiredMutex" list for this walk
 *
 ******************************************************************************/

static void
acpi_ex_link_mutex(union acpi_operand_object *obj_desc,
                   struct acpi_thread_state *thread)
{
        union acpi_operand_object *list_head;

        list_head = thread->acquired_mutex_list;

        /* This object will be the first object in the list */

        obj_desc->mutex.prev = NULL;
        obj_desc->mutex.next = list_head;

        /* Update old first object to point back to this object */

        if (list_head) {
                list_head->mutex.prev = obj_desc;
        }

        /* Update list head */

        thread->acquired_mutex_list = obj_desc;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_acquire_mutex_object
 *
 * PARAMETERS:  timeout             - Timeout in milliseconds
 *              obj_desc            - Mutex object
 *              thread_id           - Current thread state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Acquire an AML mutex, low-level interface. Provides a common
 *              path that supports multiple acquires by the same thread.
 *
 * MUTEX:       Interpreter must be locked
 *
 * NOTE: This interface is called from three places:
 * 1) From acpi_ex_acquire_mutex, via an AML Acquire() operator
 * 2) From acpi_ex_acquire_global_lock when an AML Field access requires the
 *    global lock
 * 3) From the external interface, acpi_acquire_global_lock
 *
 ******************************************************************************/

acpi_status
acpi_ex_acquire_mutex_object(u16 timeout,
                             union acpi_operand_object *obj_desc,
                             acpi_thread_id thread_id)
{
        acpi_status status;

        ACPI_FUNCTION_TRACE_PTR(ex_acquire_mutex_object, obj_desc);

        if (!obj_desc) {
                return_ACPI_STATUS(AE_BAD_PARAMETER);
        }

        /* Support for multiple acquires by the owning thread */

        if (obj_desc->mutex.thread_id == thread_id) {
                /*
                 * The mutex is already owned by this thread, just increment the
                 * acquisition depth
                 */
                obj_desc->mutex.acquisition_depth++;
                return_ACPI_STATUS(AE_OK);
        }

        /* Acquire the mutex, wait if necessary. Special case for Global Lock */

        if (obj_desc == acpi_gbl_global_lock_mutex) {
                status = acpi_ev_acquire_global_lock(timeout);
        } else {
                status =
                    acpi_ex_system_wait_mutex(obj_desc->mutex.os_mutex,
                                              timeout);
        }

        if (ACPI_FAILURE(status)) {

                /* Includes failure from a timeout on time_desc */

                return_ACPI_STATUS(status);
        }

        /* Acquired the mutex: update mutex object */

        obj_desc->mutex.thread_id = thread_id;
        obj_desc->mutex.acquisition_depth = 1;
        obj_desc->mutex.original_sync_level = 0;
        obj_desc->mutex.owner_thread = NULL;    /* Used only for AML Acquire() */

        return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_acquire_mutex
 *
 * PARAMETERS:  time_desc           - Timeout integer
 *              obj_desc            - Mutex object
 *              walk_state          - Current method execution state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Acquire an AML mutex
 *
 ******************************************************************************/

acpi_status
acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
                      union acpi_operand_object *obj_desc,
                      struct acpi_walk_state *walk_state)
{
        acpi_status status;

        ACPI_FUNCTION_TRACE_PTR(ex_acquire_mutex, obj_desc);

        if (!obj_desc) {
                return_ACPI_STATUS(AE_BAD_PARAMETER);
        }

        /* Must have a valid thread state struct */

        if (!walk_state->thread) {
                ACPI_ERROR((AE_INFO,
                            "Cannot acquire Mutex [%4.4s], null thread info",
                            acpi_ut_get_node_name(obj_desc->mutex.node)));
                return_ACPI_STATUS(AE_AML_INTERNAL);
        }

        /*
         * Current sync level must be less than or equal to the sync level
         * of the mutex. This mechanism provides some deadlock prevention.
         */
        if (walk_state->thread->current_sync_level > obj_desc->mutex.sync_level) {
                ACPI_ERROR((AE_INFO,
                            "Cannot acquire Mutex [%4.4s], "
                            "current SyncLevel is too large (%u)",
                            acpi_ut_get_node_name(obj_desc->mutex.node),
                            walk_state->thread->current_sync_level));
                return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
        }

        ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                          "Acquiring: Mutex SyncLevel %u, Thread SyncLevel %u, "
                          "Depth %u TID %p\n",
                          obj_desc->mutex.sync_level,
                          walk_state->thread->current_sync_level,
                          obj_desc->mutex.acquisition_depth,
                          walk_state->thread));

        status = acpi_ex_acquire_mutex_object((u16)time_desc->integer.value,
                                              obj_desc,
                                              walk_state->thread->thread_id);

        if (ACPI_SUCCESS(status) && obj_desc->mutex.acquisition_depth == 1) {

                /* Save Thread object, original/current sync levels */

                obj_desc->mutex.owner_thread = walk_state->thread;
                obj_desc->mutex.original_sync_level =
                    walk_state->thread->current_sync_level;
                walk_state->thread->current_sync_level =
                    obj_desc->mutex.sync_level;

                /* Link the mutex to the current thread for force-unlock at method exit */

                acpi_ex_link_mutex(obj_desc, walk_state->thread);
        }

        ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                          "Acquired: Mutex SyncLevel %u, Thread SyncLevel %u, Depth %u\n",
                          obj_desc->mutex.sync_level,
                          walk_state->thread->current_sync_level,
                          obj_desc->mutex.acquisition_depth));

        return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_release_mutex_object
 *
 * PARAMETERS:  obj_desc            - The object descriptor for this op
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Release a previously acquired Mutex, low level interface.
 *              Provides a common path that supports multiple releases (after
 *              previous multiple acquires) by the same thread.
 *
 * MUTEX:       Interpreter must be locked
 *
 * NOTE: This interface is called from three places:
 * 1) From acpi_ex_release_mutex, via an AML Acquire() operator
 * 2) From acpi_ex_release_global_lock when an AML Field access requires the
 *    global lock
 * 3) From the external interface, acpi_release_global_lock
 *
 ******************************************************************************/

acpi_status acpi_ex_release_mutex_object(union acpi_operand_object *obj_desc)
{
        acpi_status status = AE_OK;

        ACPI_FUNCTION_TRACE(ex_release_mutex_object);

        if (obj_desc->mutex.acquisition_depth == 0) {
                return_ACPI_STATUS(AE_NOT_ACQUIRED);
        }

        /* Match multiple Acquires with multiple Releases */

        obj_desc->mutex.acquisition_depth--;
        if (obj_desc->mutex.acquisition_depth != 0) {

                /* Just decrement the depth and return */

                return_ACPI_STATUS(AE_OK);
        }

        if (obj_desc->mutex.owner_thread) {

                /* Unlink the mutex from the owner's list */

                acpi_ex_unlink_mutex(obj_desc);
                obj_desc->mutex.owner_thread = NULL;
        }

        /* Release the mutex, special case for Global Lock */

        if (obj_desc == acpi_gbl_global_lock_mutex) {
                status = acpi_ev_release_global_lock();
        } else {
                acpi_os_release_mutex(obj_desc->mutex.os_mutex);
        }

        /* Clear mutex info */

        obj_desc->mutex.thread_id = 0;
        return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_release_mutex
 *
 * PARAMETERS:  obj_desc            - The object descriptor for this op
 *              walk_state          - Current method execution state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Release a previously acquired Mutex.
 *
 ******************************************************************************/

acpi_status
acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                      struct acpi_walk_state *walk_state)
{
        u8 previous_sync_level;
        struct acpi_thread_state *owner_thread;
        acpi_status status = AE_OK;

        ACPI_FUNCTION_TRACE(ex_release_mutex);

        if (!obj_desc) {
                return_ACPI_STATUS(AE_BAD_PARAMETER);
        }

        owner_thread = obj_desc->mutex.owner_thread;

        /* The mutex must have been previously acquired in order to release it */

        if (!owner_thread) {
                ACPI_ERROR((AE_INFO,
                            "Cannot release Mutex [%4.4s], not acquired",
                            acpi_ut_get_node_name(obj_desc->mutex.node)));
                return_ACPI_STATUS(AE_AML_MUTEX_NOT_ACQUIRED);
        }

        /* Must have a valid thread ID */

        if (!walk_state->thread) {
                ACPI_ERROR((AE_INFO,
                            "Cannot release Mutex [%4.4s], null thread info",
                            acpi_ut_get_node_name(obj_desc->mutex.node)));
                return_ACPI_STATUS(AE_AML_INTERNAL);
        }

        /*
         * The Mutex is owned, but this thread must be the owner.
         * Special case for Global Lock, any thread can release
         */
        if ((owner_thread->thread_id != walk_state->thread->thread_id) &&
            (obj_desc != acpi_gbl_global_lock_mutex)) {
                ACPI_ERROR((AE_INFO,
                            "Thread %u cannot release Mutex [%4.4s] acquired by thread %u",
                            (u32)walk_state->thread->thread_id,
                            acpi_ut_get_node_name(obj_desc->mutex.node),
                            (u32)owner_thread->thread_id));
                return_ACPI_STATUS(AE_AML_NOT_OWNER);
        }

        /*
         * The sync level of the mutex must be equal to the current sync level. In
         * other words, the current level means that at least one mutex at that
         * level is currently being held. Attempting to release a mutex of a
         * different level can only mean that the mutex ordering rule is being
         * violated. This behavior is clarified in ACPI 4.0 specification.
         */
        if (obj_desc->mutex.sync_level != owner_thread->current_sync_level) {
                ACPI_ERROR((AE_INFO,
                            "Cannot release Mutex [%4.4s], SyncLevel mismatch: "
                            "mutex %u current %u",
                            acpi_ut_get_node_name(obj_desc->mutex.node),
                            obj_desc->mutex.sync_level,
                            walk_state->thread->current_sync_level));
                return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
        }

        /*
         * Get the previous sync_level from the head of the acquired mutex list.
         * This handles the case where several mutexes at the same level have been
         * acquired, but are not released in reverse order.
         */
        previous_sync_level =
            owner_thread->acquired_mutex_list->mutex.original_sync_level;

        ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                          "Releasing: Object SyncLevel %u, Thread SyncLevel %u, "
                          "Prev SyncLevel %u, Depth %u TID %p\n",
                          obj_desc->mutex.sync_level,
                          walk_state->thread->current_sync_level,
                          previous_sync_level,
                          obj_desc->mutex.acquisition_depth,
                          walk_state->thread));

        status = acpi_ex_release_mutex_object(obj_desc);
        if (ACPI_FAILURE(status)) {
                return_ACPI_STATUS(status);
        }

        if (obj_desc->mutex.acquisition_depth == 0) {

                /* Restore the previous sync_level */

                owner_thread->current_sync_level = previous_sync_level;
        }

        ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                          "Released: Object SyncLevel %u, Thread SyncLevel, %u, "
                          "Prev SyncLevel %u, Depth %u\n",
                          obj_desc->mutex.sync_level,
                          walk_state->thread->current_sync_level,
                          previous_sync_level,
                          obj_desc->mutex.acquisition_depth));

        return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_release_all_mutexes
 *
 * PARAMETERS:  thread              - Current executing thread object
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Release all mutexes held by this thread
 *
 * NOTE: This function is called as the thread is exiting the interpreter.
 * Mutexes are not released when an individual control method is exited, but
 * only when the parent thread actually exits the interpreter. This allows one
 * method to acquire a mutex, and a different method to release it, as long as
 * this is performed underneath a single parent control method.
 *
 ******************************************************************************/

void acpi_ex_release_all_mutexes(struct acpi_thread_state *thread)
{
        union acpi_operand_object *next = thread->acquired_mutex_list;
        union acpi_operand_object *obj_desc;

        ACPI_FUNCTION_TRACE(ex_release_all_mutexes);

        /* Traverse the list of owned mutexes, releasing each one */

        while (next) {
                obj_desc = next;
                ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                                  "Mutex [%4.4s] force-release, SyncLevel %u Depth %u\n",
                                  obj_desc->mutex.node->name.ascii,
                                  obj_desc->mutex.sync_level,
                                  obj_desc->mutex.acquisition_depth));

                /* Release the mutex, special case for Global Lock */

                if (obj_desc == acpi_gbl_global_lock_mutex) {

                        /* Ignore errors */

                        (void)acpi_ev_release_global_lock();
                } else {
                        acpi_os_release_mutex(obj_desc->mutex.os_mutex);
                }

                /* Update Thread sync_level (Last mutex is the important one) */

                thread->current_sync_level =
                    obj_desc->mutex.original_sync_level;

                /* Mark mutex unowned */

                next = obj_desc->mutex.next;

                obj_desc->mutex.prev = NULL;
                obj_desc->mutex.next = NULL;
                obj_desc->mutex.acquisition_depth = 0;
                obj_desc->mutex.owner_thread = NULL;
                obj_desc->mutex.thread_id = 0;
        }

        return_VOID;
}