gcc/ada/s-tarest.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --     S Y S T E M . T A S K I N G . R E S T R I C T E D . S T A G E S      --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --         Copyright (C) 1999-2014, Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 pragma Style_Checks (All_Checks);
  33 --  Turn off subprogram alpha order check, since we group soft link
  34 --  bodies and also separate off subprograms for restricted GNARLI.
  35
  36 --  This is a simplified version of the System.Tasking.Stages package,
  37 --  intended to be used in a restricted run time.
  38
  39 --  This package represents the high level tasking interface used by the
  40 --  compiler to expand Ada 95 tasking constructs into simpler run time calls.
  41
  42 pragma Polling (Off);
  43 --  Turn off polling, we do not want ATC polling to take place during
  44 --  tasking operations. It causes infinite loops and other problems.
  45
  46 with Ada.Exceptions;
  47
  48 with System.Task_Primitives.Operations;
  49 with System.Soft_Links.Tasking;
  50 with System.Storage_Elements;
  51
  52 with System.Secondary_Stack;
  53 pragma Elaborate_All (System.Secondary_Stack);
  54 --  Make sure the body of Secondary_Stack is elaborated before calling
  55 --  Init_Tasking_Soft_Links. See comments for this routine for explanation.
  56
  57 with System.Soft_Links;
  58 --  Used for the non-tasking routines (*_NT) that refer to global data. They
  59 --  are needed here before the tasking run time has been elaborated. used for
  60 --  Create_TSD This package also provides initialization routines for task
  61 --  specific data. The GNARL must call these to be sure that all non-tasking
  62 --  Ada constructs will work.
  63
  64 package body System.Tasking.Restricted.Stages is
  65
  66    package STPO renames System.Task_Primitives.Operations;
  67    package SSL  renames System.Soft_Links;
  68    package SSE  renames System.Storage_Elements;
  69    package SST  renames System.Secondary_Stack;
  70
  71    use Ada.Exceptions;
  72
  73    use Parameters;
  74    use Task_Primitives.Operations;
  75    use Task_Info;
  76
  77    Tasks_Activation_Chain : Task_Id;
  78    --  Chain of all the tasks to activate
  79
  80    Global_Task_Lock : aliased System.Task_Primitives.RTS_Lock;
  81    --  This is a global lock; it is used to execute in mutual exclusion
  82    --  from all other tasks. It is only used by Task_Lock and Task_Unlock.
  83
  84    -----------------------------------------------------------------
  85    -- Tasking versions of services needed by non-tasking programs --
  86    -----------------------------------------------------------------
  87
  88    function Get_Current_Excep return SSL.EOA;
  89    --  Task-safe version of SSL.Get_Current_Excep
  90
  91    procedure Task_Lock;
  92    --  Locks out other tasks. Preceding a section of code by Task_Lock and
  93    --  following it by Task_Unlock creates a critical region. This is used
  94    --  for ensuring that a region of non-tasking code (such as code used to
  95    --  allocate memory) is tasking safe. Note that it is valid for calls to
  96    --  Task_Lock/Task_Unlock to be nested, and this must work properly, i.e.
  97    --  only the corresponding outer level Task_Unlock will actually unlock.
  98
  99    procedure Task_Unlock;
 100    --  Releases lock previously set by call to Task_Lock. In the nested case,
 101    --  all nested locks must be released before other tasks competing for the
 102    --  tasking lock are released.
 103
 104    -----------------------
 105    -- Local Subprograms --
 106    -----------------------
 107
 108    procedure Task_Wrapper (Self_ID : Task_Id);
 109    --  This is the procedure that is called by the GNULL from the
 110    --  new context when a task is created. It waits for activation
 111    --  and then calls the task body procedure. When the task body
 112    --  procedure completes, it terminates the task.
 113
 114    procedure Terminate_Task (Self_ID : Task_Id);
 115    --  Terminate the calling task.
 116    --  This should only be called by the Task_Wrapper procedure.
 117
 118    procedure Create_Restricted_Task
 119      (Priority      : Integer;
 120       Stack_Address : System.Address;
 121       Size          : System.Parameters.Size_Type;
 122       Task_Info     : System.Task_Info.Task_Info_Type;
 123       CPU           : Integer;
 124       State         : Task_Procedure_Access;
 125       Discriminants : System.Address;
 126       Elaborated    : Access_Boolean;
 127       Task_Image    : String;
 128       Created_Task  : Task_Id);
 129    --  Code shared between Create_Restricted_Task (the concurrent version) and
 130    --  Create_Restricted_Task_Sequential. See comment of the former in the
 131    --  specification of this package.
 132
 133    procedure Activate_Tasks (Chain : Task_Id);
 134    --  Activate the list of tasks started by Chain
 135
 136    procedure Init_RTS;
 137    --  This procedure performs the initialization of the GNARL.
 138    --  It consists of initializing the environment task, global locks, and
 139    --  installing tasking versions of certain operations used by the compiler.
 140    --  Init_RTS is called during elaboration.
 141
 142    -----------------------
 143    -- Get_Current_Excep --
 144    -----------------------
 145
 146    function Get_Current_Excep return SSL.EOA is
 147    begin
 148       return STPO.Self.Common.Compiler_Data.Current_Excep'Access;
 149    end Get_Current_Excep;
 150
 151    ---------------
 152    -- Task_Lock --
 153    ---------------
 154
 155    procedure Task_Lock is
 156       Self_ID : constant Task_Id := STPO.Self;
 157
 158    begin
 159       Self_ID.Common.Global_Task_Lock_Nesting :=
 160         Self_ID.Common.Global_Task_Lock_Nesting + 1;
 161
 162       if Self_ID.Common.Global_Task_Lock_Nesting = 1 then
 163          STPO.Write_Lock (Global_Task_Lock'Access, Global_Lock => True);
 164       end if;
 165    end Task_Lock;
 166
 167    -----------------
 168    -- Task_Unlock --
 169    -----------------
 170
 171    procedure Task_Unlock is
 172       Self_ID : constant Task_Id := STPO.Self;
 173
 174    begin
 175       pragma Assert (Self_ID.Common.Global_Task_Lock_Nesting > 0);
 176       Self_ID.Common.Global_Task_Lock_Nesting :=
 177         Self_ID.Common.Global_Task_Lock_Nesting - 1;
 178
 179       if Self_ID.Common.Global_Task_Lock_Nesting = 0 then
 180          STPO.Unlock (Global_Task_Lock'Access, Global_Lock => True);
 181       end if;
 182    end Task_Unlock;
 183
 184    ------------------
 185    -- Task_Wrapper --
 186    ------------------
 187
 188    --  The task wrapper is a procedure that is called first for each task
 189    --  task body, and which in turn calls the compiler-generated task body
 190    --  procedure. The wrapper's main job is to do initialization for the task.
 191
 192    --  The variable ID in the task wrapper is used to implement the Self
 193    --  function on targets where there is a fast way to find the stack base
 194    --  of the current thread, since it should be at a fixed offset from the
 195    --  stack base.
 196
 197    procedure Task_Wrapper (Self_ID : Task_Id) is
 198       ID : Task_Id := Self_ID;
 199       pragma Volatile (ID);
 200       pragma Warnings (Off, ID);
 201       --  Variable used on some targets to implement a fast self. We turn off
 202       --  warnings because a stand alone volatile constant has to be imported,
 203       --  so we don't want warnings about ID not being referenced, and volatile
 204       --  having no effect.
 205       --
 206       --  DO NOT delete ID. As noted, it is needed on some targets.
 207
 208       use type SSE.Storage_Offset;
 209
 210       Secondary_Stack : aliased SSE.Storage_Array
 211         (1 .. Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
 212                 SSE.Storage_Offset (Parameters.Sec_Stack_Percentage) / 100);
 213       for Secondary_Stack'Alignment use Standard'Maximum_Alignment;
 214       --  This is the secondary stack data. Note that it is critical that this
 215       --  have maximum alignment, since any kind of data can be allocated here.
 216
 217       pragma Warnings (Off);
 218       Secondary_Stack_Address : System.Address := Secondary_Stack'Address;
 219       pragma Warnings (On);
 220       --  Address of secondary stack. In the fixed secondary stack case, this
 221       --  value is not modified, causing a warning, hence the bracketing with
 222       --  Warnings (Off/On).
 223
 224       Cause : Cause_Of_Termination := Normal;
 225       --  Indicates the reason why this task terminates. Normal corresponds to
 226       --  a task terminating due to completing the last statement of its body.
 227       --  If the task terminates because of an exception raised by the
 228       --  execution of its task body, then Cause is set to Unhandled_Exception.
 229       --  Aborts are not allowed in the restricted profile to which this file
 230       --  belongs.
 231
 232       EO : Exception_Occurrence;
 233       --  If the task terminates because of an exception raised by the
 234       --  execution of its task body, then EO will contain the associated
 235       --  exception occurrence. Otherwise, it will contain Null_Occurrence.
 236
 237    begin
 238       if not Parameters.Sec_Stack_Dynamic then
 239          Self_ID.Common.Compiler_Data.Sec_Stack_Addr :=
 240            Secondary_Stack'Address;
 241          SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last));
 242       end if;
 243
 244       --  Initialize low-level TCB components, that
 245       --  cannot be initialized by the creator.
 246
 247       Enter_Task (Self_ID);
 248
 249       --  Call the task body procedure
 250
 251       begin
 252          --  We are separating the following portion of the code in order to
 253          --  place the exception handlers in a different block. In this way we
 254          --  do not call Set_Jmpbuf_Address (which needs Self) before we set
 255          --  Self in Enter_Task.
 256
 257          --  Note that in the case of Ravenscar HI-E where there are no
 258          --  exception handlers, the exception handler is suppressed.
 259
 260          --  Call the task body procedure
 261
 262          Self_ID.Common.Task_Entry_Point (Self_ID.Common.Task_Arg);
 263
 264          --  Normal task termination
 265
 266          Cause := Normal;
 267          Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
 268
 269       exception
 270          when E : others =>
 271
 272             --  Task terminating because of an unhandled exception
 273
 274             Cause := Unhandled_Exception;
 275             Save_Occurrence (EO, E);
 276       end;
 277
 278       --  Look for a fall-back handler
 279
 280       --  This package is part of the restricted run time which supports
 281       --  neither task hierarchies (No_Task_Hierarchy) nor specific task
 282       --  termination handlers (No_Specific_Termination_Handlers).
 283
 284       --  As specified in ARM C.7.3 par. 9/2, "the fall-back handler applies
 285       --  only to the dependent tasks of the task". Hence, if the terminating
 286       --  tasks (Self_ID) had a fall-back handler, it would not apply to
 287       --  itself. This code is always executed by a task whose master is the
 288       --  environment task (the task termination code for the environment task
 289       --  is executed by SSL.Task_Termination_Handler), so the fall-back
 290       --  handler to execute for this task can only be defined by its parent
 291       --  (there is no grandparent).
 292
 293       declare
 294          TH : Termination_Handler := null;
 295
 296       begin
 297          if Single_Lock then
 298             Lock_RTS;
 299          end if;
 300
 301          Write_Lock (Self_ID.Common.Parent);
 302
 303          TH := Self_ID.Common.Parent.Common.Fall_Back_Handler;
 304
 305          Unlock (Self_ID.Common.Parent);
 306
 307          if Single_Lock then
 308             Unlock_RTS;
 309          end if;
 310
 311          --  Execute the task termination handler if we found it
 312
 313          if TH /= null then
 314             TH.all (Cause, Self_ID, EO);
 315          end if;
 316       end;
 317
 318       Terminate_Task (Self_ID);
 319    end Task_Wrapper;
 320
 321    -----------------------
 322    -- Restricted GNARLI --
 323    -----------------------
 324
 325    -----------------------------------
 326    -- Activate_All_Tasks_Sequential --
 327    -----------------------------------
 328
 329    procedure Activate_All_Tasks_Sequential is
 330    begin
 331       pragma Assert (Partition_Elaboration_Policy = 'S');
 332
 333       Activate_Tasks (Tasks_Activation_Chain);
 334       Tasks_Activation_Chain := Null_Task;
 335    end Activate_All_Tasks_Sequential;
 336
 337    -------------------------------
 338    -- Activate_Restricted_Tasks --
 339    -------------------------------
 340
 341    procedure Activate_Restricted_Tasks
 342      (Chain_Access : Activation_Chain_Access) is
 343    begin
 344       if Partition_Elaboration_Policy = 'S' then
 345
 346          --  In sequential elaboration policy, the chain must be empty. This
 347          --  procedure can be called if the unit has been compiled without
 348          --  partition elaboration policy, but the partition has a sequential
 349          --  elaboration policy.
 350
 351          pragma Assert (Chain_Access.T_ID = Null_Task);
 352          null;
 353       else
 354          Activate_Tasks (Chain_Access.T_ID);
 355          Chain_Access.T_ID := Null_Task;
 356       end if;
 357    end Activate_Restricted_Tasks;
 358
 359    --------------------
 360    -- Activate_Tasks --
 361    --------------------
 362
 363    --  Note that locks of activator and activated task are both locked here.
 364    --  This is necessary because C.State and Self.Wait_Count have to be
 365    --  synchronized. This is safe from deadlock because the activator is always
 366    --  created before the activated task. That satisfies our
 367    --  in-order-of-creation ATCB locking policy.
 368
 369    procedure Activate_Tasks (Chain : Task_Id) is
 370       Self_ID       : constant Task_Id := STPO.Self;
 371       C             : Task_Id;
 372       Activate_Prio : System.Any_Priority;
 373       Success       : Boolean;
 374
 375    begin
 376       pragma Assert (Self_ID = Environment_Task);
 377       pragma Assert (Self_ID.Common.Wait_Count = 0);
 378
 379       if Single_Lock then
 380          Lock_RTS;
 381       end if;
 382
 383       --  Lock self, to prevent activated tasks from racing ahead before we
 384       --  finish activating the chain.
 385
 386       Write_Lock (Self_ID);
 387
 388       --  Activate all the tasks in the chain. Creation of the thread of
 389       --  control was deferred until activation. So create it now.
 390
 391       C := Chain;
 392       while C /= null loop
 393          if C.Common.State /= Terminated then
 394             pragma Assert (C.Common.State = Unactivated);
 395
 396             Write_Lock (C);
 397
 398             Activate_Prio :=
 399               (if C.Common.Base_Priority < Get_Priority (Self_ID)
 400                then Get_Priority (Self_ID)
 401                else C.Common.Base_Priority);
 402
 403             STPO.Create_Task
 404               (C, Task_Wrapper'Address,
 405                Parameters.Size_Type
 406                  (C.Common.Compiler_Data.Pri_Stack_Info.Size),
 407                Activate_Prio, Success);
 408
 409             Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
 410
 411             if Success then
 412                C.Common.State := Runnable;
 413             else
 414                raise Program_Error;
 415             end if;
 416
 417             Unlock (C);
 418          end if;
 419
 420          C := C.Common.Activation_Link;
 421       end loop;
 422
 423       Self_ID.Common.State := Activator_Sleep;
 424
 425       --  Wait for the activated tasks to complete activation. It is unsafe to
 426       --  abort any of these tasks until the count goes to zero.
 427
 428       loop
 429          exit when Self_ID.Common.Wait_Count = 0;
 430          Sleep (Self_ID, Activator_Sleep);
 431       end loop;
 432
 433       Self_ID.Common.State := Runnable;
 434       Unlock (Self_ID);
 435
 436       if Single_Lock then
 437          Unlock_RTS;
 438       end if;
 439    end Activate_Tasks;
 440
 441    ------------------------------------
 442    -- Complete_Restricted_Activation --
 443    ------------------------------------
 444
 445    --  As in several other places, the locks of the activator and activated
 446    --  task are both locked here. This follows our deadlock prevention lock
 447    --  ordering policy, since the activated task must be created after the
 448    --  activator.
 449
 450    procedure Complete_Restricted_Activation is
 451       Self_ID   : constant Task_Id := STPO.Self;
 452       Activator : constant Task_Id := Self_ID.Common.Activator;
 453
 454    begin
 455       if Single_Lock then
 456          Lock_RTS;
 457       end if;
 458
 459       Write_Lock (Activator);
 460       Write_Lock (Self_ID);
 461
 462       --  Remove dangling reference to Activator, since a task may outlive its
 463       --  activator.
 464
 465       Self_ID.Common.Activator := null;
 466
 467       --  Wake up the activator, if it is waiting for a chain of tasks to
 468       --  activate, and we are the last in the chain to complete activation
 469
 470       if Activator.Common.State = Activator_Sleep then
 471          Activator.Common.Wait_Count := Activator.Common.Wait_Count - 1;
 472
 473          if Activator.Common.Wait_Count = 0 then
 474             Wakeup (Activator, Activator_Sleep);
 475          end if;
 476       end if;
 477
 478       Unlock (Self_ID);
 479       Unlock (Activator);
 480
 481       if Single_Lock then
 482          Unlock_RTS;
 483       end if;
 484
 485       --  After the activation, active priority should be the same as base
 486       --  priority. We must unlock the Activator first, though, since it should
 487       --  not wait if we have lower priority.
 488
 489       if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then
 490          Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 491       end if;
 492    end Complete_Restricted_Activation;
 493
 494    ------------------------------
 495    -- Complete_Restricted_Task --
 496    ------------------------------
 497
 498    procedure Complete_Restricted_Task is
 499    begin
 500       STPO.Self.Common.State := Terminated;
 501    end Complete_Restricted_Task;
 502
 503    ----------------------------
 504    -- Create_Restricted_Task --
 505    ----------------------------
 506
 507    procedure Create_Restricted_Task
 508      (Priority      : Integer;
 509       Stack_Address : System.Address;
 510       Size          : System.Parameters.Size_Type;
 511       Task_Info     : System.Task_Info.Task_Info_Type;
 512       CPU           : Integer;
 513       State         : Task_Procedure_Access;
 514       Discriminants : System.Address;
 515       Elaborated    : Access_Boolean;
 516       Task_Image    : String;
 517       Created_Task  : Task_Id)
 518    is
 519       Self_ID       : constant Task_Id := STPO.Self;
 520       Base_Priority : System.Any_Priority;
 521       Base_CPU      : System.Multiprocessors.CPU_Range;
 522       Success       : Boolean;
 523       Len           : Integer;
 524
 525    begin
 526       --  Stack is not preallocated on this target, so that Stack_Address must
 527       --  be null.
 528
 529       pragma Assert (Stack_Address = Null_Address);
 530
 531       Base_Priority :=
 532         (if Priority = Unspecified_Priority
 533          then Self_ID.Common.Base_Priority
 534          else System.Any_Priority (Priority));
 535
 536       --  Legal values of CPU are the special Unspecified_CPU value which is
 537       --  inserted by the compiler for tasks without CPU aspect, and those in
 538       --  the range of CPU_Range but no greater than Number_Of_CPUs. Otherwise
 539       --  the task is defined to have failed, and it becomes a completed task
 540       --  (RM D.16(14/3)).
 541
 542       if CPU /= Unspecified_CPU
 543         and then (CPU < Integer (System.Multiprocessors.CPU_Range'First)
 544           or else CPU > Integer (System.Multiprocessors.Number_Of_CPUs))
 545       then
 546          raise Tasking_Error with "CPU not in range";
 547
 548       --  Normal CPU affinity
 549       else
 550          --  When the application code says nothing about the task affinity
 551          --  (task without CPU aspect) then the compiler inserts the
 552          --  Unspecified_CPU value which indicates to the run-time library that
 553          --  the task will activate and execute on the same processor as its
 554          --  activating task if the activating task is assigned a processor
 555          --  (RM D.16(14/3)).
 556
 557          Base_CPU :=
 558            (if CPU = Unspecified_CPU
 559             then Self_ID.Common.Base_CPU
 560             else System.Multiprocessors.CPU_Range (CPU));
 561       end if;
 562
 563       if Single_Lock then
 564          Lock_RTS;
 565       end if;
 566
 567       Write_Lock (Self_ID);
 568
 569       --  With no task hierarchy, the parent of all non-Environment tasks that
 570       --  are created must be the Environment task. Dispatching domains are
 571       --  not allowed in Ravenscar, so the dispatching domain parameter will
 572       --  always be null.
 573
 574       Initialize_ATCB
 575         (Self_ID, State, Discriminants, Self_ID, Elaborated, Base_Priority,
 576          Base_CPU, null, Task_Info, Size, Created_Task, Success);
 577
 578       --  If we do our job right then there should never be any failures, which
 579       --  was probably said about the Titanic; so just to be safe, let's retain
 580       --  this code for now
 581
 582       if not Success then
 583          Unlock (Self_ID);
 584
 585          if Single_Lock then
 586             Unlock_RTS;
 587          end if;
 588
 589          raise Program_Error;
 590       end if;
 591
 592       Created_Task.Entry_Calls (1).Self := Created_Task;
 593
 594       Len :=
 595         Integer'Min (Created_Task.Common.Task_Image'Length, Task_Image'Length);
 596       Created_Task.Common.Task_Image_Len := Len;
 597       Created_Task.Common.Task_Image (1 .. Len) :=
 598         Task_Image (Task_Image'First .. Task_Image'First + Len - 1);
 599
 600       Unlock (Self_ID);
 601
 602       if Single_Lock then
 603          Unlock_RTS;
 604       end if;
 605
 606       --  Create TSD as early as possible in the creation of a task, since it
 607       --  may be used by the operation of Ada code within the task.
 608
 609       SSL.Create_TSD (Created_Task.Common.Compiler_Data);
 610    end Create_Restricted_Task;
 611
 612    procedure Create_Restricted_Task
 613      (Priority      : Integer;
 614       Stack_Address : System.Address;
 615       Size          : System.Parameters.Size_Type;
 616       Task_Info     : System.Task_Info.Task_Info_Type;
 617       CPU           : Integer;
 618       State         : Task_Procedure_Access;
 619       Discriminants : System.Address;
 620       Elaborated    : Access_Boolean;
 621       Chain         : in out Activation_Chain;
 622       Task_Image    : String;
 623       Created_Task  : Task_Id)
 624    is
 625    begin
 626       if Partition_Elaboration_Policy = 'S' then
 627
 628          --  A unit may have been compiled without partition elaboration
 629          --  policy, and in this case the compiler will emit calls for the
 630          --  default policy (concurrent). But if the partition policy is
 631          --  sequential, activation must be deferred.
 632
 633          Create_Restricted_Task_Sequential
 634            (Priority, Stack_Address, Size, Task_Info, CPU, State,
 635             Discriminants, Elaborated, Task_Image, Created_Task);
 636
 637       else
 638          Create_Restricted_Task
 639            (Priority, Stack_Address, Size, Task_Info, CPU, State,
 640             Discriminants, Elaborated, Task_Image, Created_Task);
 641
 642          --  Append this task to the activation chain
 643
 644          Created_Task.Common.Activation_Link := Chain.T_ID;
 645          Chain.T_ID := Created_Task;
 646       end if;
 647    end Create_Restricted_Task;
 648
 649    ---------------------------------------
 650    -- Create_Restricted_Task_Sequential --
 651    ---------------------------------------
 652
 653    procedure Create_Restricted_Task_Sequential
 654      (Priority      : Integer;
 655       Stack_Address : System.Address;
 656       Size          : System.Parameters.Size_Type;
 657       Task_Info     : System.Task_Info.Task_Info_Type;
 658       CPU           : Integer;
 659       State         : Task_Procedure_Access;
 660       Discriminants : System.Address;
 661       Elaborated    : Access_Boolean;
 662       Task_Image    : String;
 663       Created_Task  : Task_Id) is
 664    begin
 665       Create_Restricted_Task (Priority, Stack_Address, Size, Task_Info,
 666                               CPU, State, Discriminants, Elaborated,
 667                               Task_Image, Created_Task);
 668
 669       --  Append this task to the activation chain
 670
 671       Created_Task.Common.Activation_Link := Tasks_Activation_Chain;
 672       Tasks_Activation_Chain := Created_Task;
 673    end Create_Restricted_Task_Sequential;
 674
 675    ---------------------------
 676    -- Finalize_Global_Tasks --
 677    ---------------------------
 678
 679    --  This is needed to support the compiler interface; it will only be called
 680    --  by the Environment task. Instead, it will cause the Environment to block
 681    --  forever, since none of the dependent tasks are expected to terminate
 682
 683    procedure Finalize_Global_Tasks is
 684       Self_ID : constant Task_Id := STPO.Self;
 685
 686    begin
 687       pragma Assert (Self_ID = STPO.Environment_Task);
 688
 689       if Single_Lock then
 690          Lock_RTS;
 691       end if;
 692
 693       --  Handle normal task termination by the environment task, but only for
 694       --  the normal task termination. In the case of Abnormal and
 695       --  Unhandled_Exception they must have been handled before, and the task
 696       --  termination soft link must have been changed so the task termination
 697       --  routine is not executed twice.
 698
 699       --  Note that in the "normal" implementation in s-tassta.adb the task
 700       --  termination procedure for the environment task should be executed
 701       --  after termination of library-level tasks. However, this
 702       --  implementation is to be used when the Ravenscar restrictions are in
 703       --  effect, and AI-394 says that if there is a fall-back handler set for
 704       --  the partition it should be called when the first task (including the
 705       --  environment task) attempts to terminate.
 706
 707       SSL.Task_Termination_Handler.all (Ada.Exceptions.Null_Occurrence);
 708
 709       Write_Lock (Self_ID);
 710       Sleep (Self_ID, Master_Completion_Sleep);
 711       Unlock (Self_ID);
 712
 713       if Single_Lock then
 714          Unlock_RTS;
 715       end if;
 716
 717       --  Should never return from Master Completion Sleep
 718
 719       raise Program_Error;
 720    end Finalize_Global_Tasks;
 721
 722    ---------------------------
 723    -- Restricted_Terminated --
 724    ---------------------------
 725
 726    function Restricted_Terminated (T : Task_Id) return Boolean is
 727    begin
 728       return T.Common.State = Terminated;
 729    end Restricted_Terminated;
 730
 731    --------------------
 732    -- Terminate_Task --
 733    --------------------
 734
 735    procedure Terminate_Task (Self_ID : Task_Id) is
 736    begin
 737       Self_ID.Common.State := Terminated;
 738    end Terminate_Task;
 739
 740    --------------
 741    -- Init_RTS --
 742    --------------
 743
 744    procedure Init_RTS is
 745    begin
 746       Tasking.Initialize;
 747
 748       --  Initialize lock used to implement mutual exclusion between all tasks
 749
 750       STPO.Initialize_Lock (Global_Task_Lock'Access, STPO.Global_Task_Level);
 751
 752       --  Notify that the tasking run time has been elaborated so that
 753       --  the tasking version of the soft links can be used.
 754
 755       SSL.Lock_Task         := Task_Lock'Access;
 756       SSL.Unlock_Task       := Task_Unlock'Access;
 757       SSL.Adafinal          := Finalize_Global_Tasks'Access;
 758       SSL.Get_Current_Excep := Get_Current_Excep'Access;
 759
 760       --  Initialize the tasking soft links (if not done yet) that are common
 761       --  to the full and the restricted run times.
 762
 763       SSL.Tasking.Init_Tasking_Soft_Links;
 764    end Init_RTS;
 765
 766 begin
 767    Init_RTS;
 768 end System.Tasking.Restricted.Stages;