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------------------------------------------------------------------------------

--                                                                          --

--                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --

--                                                                          --

--     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --

--                                                                          --

--                                  B o d y                                 --

--                                                                          --

--         Copyright (C) 1992-2009, Free Software Foundation, Inc.          --

--                                                                          --

-- GNARL is free software; you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNARL was developed by the GNARL team at Florida State University.       --

-- Extensive contributions were provided by Ada Core Technologies, Inc.     --

--                                                                          --

------------------------------------------------------------------------------

--  This is a GNU/Linux (GNU/LinuxThreads) version of this package

--  This package contains all the GNULL primitives that interface directly with

--  the underlying OS.

pragma Polling (Off);

--  Turn off polling, we do not want ATC polling to take place during tasking

--  operations. It causes infinite loops and other problems.

with Ada.Unchecked_Conversion;

with Ada.Unchecked_Deallocation;

with Interfaces.C;

with System.Task_Info;

with System.Tasking.Debug;

with System.Interrupt_Management;

with System.OS_Primitives;

with System.Stack_Checking.Operations;

with System.Soft_Links;

--  We use System.Soft_Links instead of System.Tasking.Initialization

--  because the later is a higher level package that we shouldn't depend on.

--  For example when using the restricted run time, it is replaced by

--  System.Tasking.Restricted.Stages.

package body System.Task_Primitives.Operations is

   package SSL renames System.Soft_Links;

   package SC renames System.Stack_Checking.Operations;

   use System.Tasking.Debug;

   use System.Tasking;

   use Interfaces.C;

   use System.OS_Interface;

   use System.Parameters;

   use System.OS_Primitives;

   use System.Task_Info;

   ----------------

   -- Local Data --

   ----------------

   --  The followings are logically constants, but need to be initialized

   --  at run time.

   Single_RTS_Lock : aliased RTS_Lock;

   --  This is a lock to allow only one thread of control in the RTS at

   --  a time; it is used to execute in mutual exclusion from all other tasks.

   --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List

   ATCB_Key : aliased pthread_key_t;

   --  Key used to find the Ada Task_Id associated with a thread

   Environment_Task_Id : Task_Id;

   --  A variable to hold Task_Id for the environment task

   Unblocked_Signal_Mask : aliased sigset_t;

   --  The set of signals that should be unblocked in all tasks

   --  The followings are internal configuration constants needed

   Next_Serial_Number : Task_Serial_Number := 100;

   --  We start at 100 (reserve some special values for using in error checks)

   Time_Slice_Val : Integer;

   pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");

   Dispatching_Policy : Character;

   pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");

   --  The following are effectively constants, but they need to be initialized

   --  by calling a pthread_ function.

   Mutex_Attr   : aliased pthread_mutexattr_t;

   Cond_Attr    : aliased pthread_condattr_t;

   Foreign_Task_Elaborated : aliased Boolean := True;

   --  Used to identified fake tasks (i.e., non-Ada Threads)

   Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;

   --  Whether to use an alternate signal stack for stack overflows

   Abort_Handler_Installed : Boolean := False;

   --  True if a handler for the abort signal is installed

   --------------------

   -- Local Packages --

   --------------------

   package Specific is

      procedure Initialize (Environment_Task : Task_Id);

      pragma Inline (Initialize);

      --  Initialize various data needed by this package

      function Is_Valid_Task return Boolean;

      pragma Inline (Is_Valid_Task);

      --  Does executing thread have a TCB?

      procedure Set (Self_Id : Task_Id);

      pragma Inline (Set);

      --  Set the self id for the current task

      function Self return Task_Id;

      pragma Inline (Self);

      --  Return a pointer to the Ada Task Control Block of the calling task

   end Specific;

   package body Specific is separate;

   --  The body of this package is target specific

   ---------------------------------

   -- Support for foreign threads --

   ---------------------------------

   function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;

   --  Allocate and Initialize a new ATCB for the current Thread

   function Register_Foreign_Thread

     (Thread : Thread_Id) return Task_Id is separate;

   -----------------------

   -- Local Subprograms --

   -----------------------

   subtype unsigned_long is Interfaces.C.unsigned_long;

   procedure Abort_Handler (signo : Signal);

   function To_pthread_t is new Ada.Unchecked_Conversion

     (unsigned_long, System.OS_Interface.pthread_t);

   -------------------

   -- Abort_Handler --

   -------------------

   procedure Abort_Handler (signo : Signal) is

      pragma Unreferenced (signo);

      Self_Id : constant Task_Id := Self;

      Result  : Interfaces.C.int;

      Old_Set : aliased sigset_t;

   begin

      --  It's not safe to raise an exception when using GCC ZCX mechanism.

      --  Note that we still need to install a signal handler, since in some

      --  cases (e.g. shutdown of the Server_Task in System.Interrupts) we

      --  need to send the Abort signal to a task.

      if ZCX_By_Default and then GCC_ZCX_Support then

         return;

      end if;

      if Self_Id.Deferral_Level = 0

        and then Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level

        and then not Self_Id.Aborting

      then

         Self_Id.Aborting := True;

         --  Make sure signals used for RTS internal purpose are unmasked

         Result :=

           pthread_sigmask

             (SIG_UNBLOCK,

              Unblocked_Signal_Mask'Access,

              Old_Set'Access);

         pragma Assert (Result = 0);

         raise Standard'Abort_Signal;

      end if;

   end Abort_Handler;

   --------------

   -- Lock_RTS --

   --------------

   procedure Lock_RTS is

   begin

      Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);

   end Lock_RTS;

   ----------------

   -- Unlock_RTS --

   ----------------

   procedure Unlock_RTS is

   begin

      Unlock (Single_RTS_Lock'Access, Global_Lock => True);

   end Unlock_RTS;

   -----------------

   -- Stack_Guard --

   -----------------

   --  The underlying thread system extends the memory (up to 2MB) when needed

   procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is

      pragma Unreferenced (T);

      pragma Unreferenced (On);

   begin

      null;

   end Stack_Guard;

   --------------------

   -- Get_Thread_Id  --

   --------------------

   function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is

   begin

      return T.Common.LL.Thread;

   end Get_Thread_Id;

   ----------

   -- Self --

   ----------

   function Self return Task_Id renames Specific.Self;

   ---------------------

   -- Initialize_Lock --

   ---------------------

   --  Note: mutexes and cond_variables needed per-task basis are initialized

   --  in Initialize_TCB and the Storage_Error is handled. Other mutexes (such

   --  as RTS_Lock, Memory_Lock...) used in RTS is initialized before any

   --  status change of RTS. Therefore raising Storage_Error in the following

   --  routines should be able to be handled safely.

   procedure Initialize_Lock

     (Prio : System.Any_Priority;

      L    : not null access Lock)

   is

      pragma Unreferenced (Prio);

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_init (L, Mutex_Attr'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = ENOMEM then

         raise Storage_Error with "Failed to allocate a lock";

      end if;

   end Initialize_Lock;

   procedure Initialize_Lock

     (L     : not null access RTS_Lock;

      Level : Lock_Level)

   is

      pragma Unreferenced (Level);

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_init (L, Mutex_Attr'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = ENOMEM then

         raise Storage_Error;

      end if;

   end Initialize_Lock;

   -------------------

   -- Finalize_Lock --

   -------------------

   procedure Finalize_Lock (L : not null access Lock) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_destroy (L);

      pragma Assert (Result = 0);

   end Finalize_Lock;

   procedure Finalize_Lock (L : not null access RTS_Lock) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_destroy (L);

      pragma Assert (Result = 0);

   end Finalize_Lock;

   ----------------

   -- Write_Lock --

   ----------------

   procedure Write_Lock

     (L                 : not null access Lock;

      Ceiling_Violation : out Boolean)

   is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_lock (L);

      Ceiling_Violation := Result = EINVAL;

      --  Assume the cause of EINVAL is a priority ceiling violation

      pragma Assert (Result = 0 or else Result = EINVAL);

   end Write_Lock;

   procedure Write_Lock

     (L           : not null access RTS_Lock;

      Global_Lock : Boolean := False)

   is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock or else Global_Lock then

         Result := pthread_mutex_lock (L);

         pragma Assert (Result = 0);

      end if;

   end Write_Lock;

   procedure Write_Lock (T : Task_Id) is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock then

         Result := pthread_mutex_lock (T.Common.LL.L'Access);

         pragma Assert (Result = 0);

      end if;

   end Write_Lock;

   ---------------

   -- Read_Lock --

   ---------------

   procedure Read_Lock

     (L                 : not null access Lock;

      Ceiling_Violation : out Boolean)

   is

   begin

      Write_Lock (L, Ceiling_Violation);

   end Read_Lock;

   ------------

   -- Unlock --

   ------------

   procedure Unlock (L : not null access Lock) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_unlock (L);

      pragma Assert (Result = 0);

   end Unlock;

   procedure Unlock

     (L           : not null access RTS_Lock;

      Global_Lock : Boolean := False)

   is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock or else Global_Lock then

         Result := pthread_mutex_unlock (L);

         pragma Assert (Result = 0);

      end if;

   end Unlock;

   procedure Unlock (T : Task_Id) is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock then

         Result := pthread_mutex_unlock (T.Common.LL.L'Access);

         pragma Assert (Result = 0);

      end if;

   end Unlock;

   -----------------

   -- Set_Ceiling --

   -----------------

   --  Dynamic priority ceilings are not supported by the underlying system

   procedure Set_Ceiling

     (L    : not null access Lock;

      Prio : System.Any_Priority)

   is

      pragma Unreferenced (L, Prio);

   begin

      null;

   end Set_Ceiling;

   -----------

   -- Sleep --

   -----------

   procedure Sleep

     (Self_ID  : Task_Id;

      Reason   : System.Tasking.Task_States)

   is

      pragma Unreferenced (Reason);

      Result : Interfaces.C.int;

   begin

      pragma Assert (Self_ID = Self);

      Result :=

        pthread_cond_wait

          (cond  => Self_ID.Common.LL.CV'Access,

           mutex => (if Single_Lock

                     then Single_RTS_Lock'Access

                     else Self_ID.Common.LL.L'Access));

      --  EINTR is not considered a failure

      pragma Assert (Result = 0 or else Result = EINTR);

   end Sleep;

   -----------------

   -- Timed_Sleep --

   -----------------

   --  This is for use within the run-time system, so abort is

   --  assumed to be already deferred, and the caller should be

   --  holding its own ATCB lock.

   procedure Timed_Sleep

     (Self_ID  : Task_Id;

      Time     : Duration;

      Mode     : ST.Delay_Modes;

      Reason   : System.Tasking.Task_States;

      Timedout : out Boolean;

      Yielded  : out Boolean)

   is

      pragma Unreferenced (Reason);

      Base_Time  : constant Duration := Monotonic_Clock;

      Check_Time : Duration := Base_Time;

      Abs_Time   : Duration;

      Request    : aliased timespec;

      Result     : Interfaces.C.int;

   begin

      Timedout := True;

      Yielded := False;

      Abs_Time :=

        (if Mode = Relative

         then Duration'Min (Time, Max_Sensible_Delay) + Check_Time

         else Duration'Min (Check_Time + Max_Sensible_Delay, Time));

      if Abs_Time > Check_Time then

         Request := To_Timespec (Abs_Time);

         loop

            exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;

            Result :=

              pthread_cond_timedwait

                (cond    => Self_ID.Common.LL.CV'Access,

                 mutex   => (if Single_Lock

                             then Single_RTS_Lock'Access

                             else Self_ID.Common.LL.L'Access),

                 abstime => Request'Access);

            Check_Time := Monotonic_Clock;

            exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;

            if Result = 0 or else Result = EINTR then

               --  Somebody may have called Wakeup for us

               Timedout := False;

               exit;

            end if;

            pragma Assert (Result = ETIMEDOUT);

         end loop;

      end if;

   end Timed_Sleep;

   -----------------

   -- Timed_Delay --

   -----------------

   --  This is for use in implementing delay statements, so we assume the

   --  caller is abort-deferred but is holding no locks.

   procedure Timed_Delay

     (Self_ID : Task_Id;

      Time    : Duration;

      Mode    : ST.Delay_Modes)

   is

      Base_Time  : constant Duration := Monotonic_Clock;

      Check_Time : Duration := Base_Time;

      Abs_Time   : Duration;

      Request    : aliased timespec;

      Result : Interfaces.C.int;

      pragma Warnings (Off, Result);

   begin

      if Single_Lock then

         Lock_RTS;

      end if;

      Write_Lock (Self_ID);

      Abs_Time :=

        (if Mode = Relative

         then Time + Check_Time

         else Duration'Min (Check_Time + Max_Sensible_Delay, Time));

      if Abs_Time > Check_Time then

         Request := To_Timespec (Abs_Time);

         Self_ID.Common.State := Delay_Sleep;

         loop

            exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;

            Result :=

              pthread_cond_timedwait

                (cond    => Self_ID.Common.LL.CV'Access,

                 mutex   => (if Single_Lock

                             then Single_RTS_Lock'Access

                             else Self_ID.Common.LL.L'Access),

                 abstime => Request'Access);

            Check_Time := Monotonic_Clock;

            exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;

            pragma Assert (Result = 0 or else

              Result = ETIMEDOUT or else

              Result = EINTR);

         end loop;

         Self_ID.Common.State := Runnable;

      end if;

      Unlock (Self_ID);

      if Single_Lock then

         Unlock_RTS;

      end if;

      Result := sched_yield;

   end Timed_Delay;

   ---------------------

   -- Monotonic_Clock --

   ---------------------

   function Monotonic_Clock return Duration is

      use Interfaces;

      type timeval is array (1 .. 2) of C.long;

      procedure timeval_to_duration

        (T    : not null access timeval;

         sec  : not null access C.long;

         usec : not null access C.long);

      pragma Import (C, timeval_to_duration, "__gnat_timeval_to_duration");

      Micro  : constant := 10**6;

      sec    : aliased C.long;

      usec   : aliased C.long;

      TV     : aliased timeval;

      Result : int;

      function gettimeofday

        (Tv : access timeval;

         Tz : System.Address := System.Null_Address) return int;

      pragma Import (C, gettimeofday, "gettimeofday");

   begin

      Result := gettimeofday (TV'Access, System.Null_Address);

      pragma Assert (Result = 0);

      timeval_to_duration (TV'Access, sec'Access, usec'Access);

      return Duration (sec) + Duration (usec) / Micro;

   end Monotonic_Clock;

   -------------------

   -- RT_Resolution --

   -------------------

   function RT_Resolution return Duration is

   begin

      return 10#1.0#E-6;

   end RT_Resolution;

   ------------

   -- Wakeup --

   ------------

   procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is

      pragma Unreferenced (Reason);

      Result : Interfaces.C.int;

   begin

      Result := pthread_cond_signal (T.Common.LL.CV'Access);

      pragma Assert (Result = 0);

   end Wakeup;

   -----------

   -- Yield --

   -----------

   procedure Yield (Do_Yield : Boolean := True) is

      Result : Interfaces.C.int;

      pragma Unreferenced (Result);

   begin

      if Do_Yield then

         Result := sched_yield;

      end if;

   end Yield;

   ------------------

   -- Set_Priority --

   ------------------

   procedure Set_Priority

     (T                   : Task_Id;

      Prio                : System.Any_Priority;

      Loss_Of_Inheritance : Boolean := False)

   is

      pragma Unreferenced (Loss_Of_Inheritance);

      Result : Interfaces.C.int;

      Param  : aliased struct_sched_param;

      function Get_Policy (Prio : System.Any_Priority) return Character;

      pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");

      --  Get priority specific dispatching policy

      Priority_Specific_Policy : constant Character := Get_Policy (Prio);

      --  Upper case first character of the policy name corresponding to the

      --  task as set by a Priority_Specific_Dispatching pragma.

   begin

      T.Common.Current_Priority := Prio;

      --  Priorities are 1 .. 99 on GNU/Linux, so we map 0 .. 98 to 1 .. 99

      Param.sched_priority := Interfaces.C.int (Prio) + 1;

      if Dispatching_Policy = 'R'

        or else Priority_Specific_Policy = 'R'

        or else Time_Slice_Val > 0

      then

         Result :=

           pthread_setschedparam

             (T.Common.LL.Thread, SCHED_RR, Param'Access);

      elsif Dispatching_Policy = 'F'

        or else Priority_Specific_Policy = 'F'

        or else Time_Slice_Val = 0

      then

         Result :=

           pthread_setschedparam

             (T.Common.LL.Thread, SCHED_FIFO, Param'Access);

      else

         Param.sched_priority := 0;

         Result :=

           pthread_setschedparam

             (T.Common.LL.Thread,

              SCHED_OTHER, Param'Access);

      end if;

      pragma Assert (Result = 0 or else Result = EPERM);

   end Set_Priority;

   ------------------

   -- Get_Priority --

   ------------------

   function Get_Priority (T : Task_Id) return System.Any_Priority is

   begin

      return T.Common.Current_Priority;

   end Get_Priority;

   ----------------

   -- Enter_Task --

   ----------------

   procedure Enter_Task (Self_ID : Task_Id) is

   begin

      if Self_ID.Common.Task_Info /= null

        and then Self_ID.Common.Task_Info.CPU_Affinity = No_CPU

      then

         raise Invalid_CPU_Number;

      end if;

      Self_ID.Common.LL.Thread := pthread_self;

      Self_ID.Common.LL.LWP := lwp_self;

      Specific.Set (Self_ID);

      if Use_Alternate_Stack then

         declare

            Stack  : aliased stack_t;

            Result : Interfaces.C.int;

         begin

            Stack.ss_sp    := Self_ID.Common.Task_Alternate_Stack;

            Stack.ss_size  := Alternate_Stack_Size;

            Stack.ss_flags := 0;

            Result := sigaltstack (Stack'Access, null);

            pragma Assert (Result = 0);

         end;

      end if;

   end Enter_Task;

   --------------

   -- New_ATCB --

   --------------

   function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is

   begin

      return new Ada_Task_Control_Block (Entry_Num);

   end New_ATCB;

   -------------------

   -- Is_Valid_Task --

   -------------------

   function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;

   -----------------------------

   -- Register_Foreign_Thread --

   -----------------------------

   function Register_Foreign_Thread return Task_Id is

   begin

      if Is_Valid_Task then

         return Self;

      else

         return Register_Foreign_Thread (pthread_self);

      end if;

   end Register_Foreign_Thread;

   --------------------

   -- Initialize_TCB --

   --------------------

   procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is

      Result : Interfaces.C.int;

   begin

      --  Give the task a unique serial number

      Self_ID.Serial_Number := Next_Serial_Number;

      Next_Serial_Number := Next_Serial_Number + 1;

      pragma Assert (Next_Serial_Number /= 0);

      Self_ID.Common.LL.Thread := To_pthread_t (-1);

      if not Single_Lock then