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------------------------------------------------------------------------------
-- --
-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . S T A C K _ C H E C K I N G . O P E R A T I O N S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1999-2004 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 2, or (at your option) any later ver- --
-- sion. GNARL 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. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNARL; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
-- This is the VxWorks version of this package.
-- This file should be kept synchronized with the general implementation
-- provided by s-stchop.adb.
pragma Restrictions (No_Elaboration_Code);
-- We want to guarantee the absence of elaboration code because the
-- binder does not handle references to this package.
with Ada.Exceptions;
with System.Storage_Elements; use System.Storage_Elements;
with System.Parameters; use System.Parameters;
with System.Soft_Links;
with Interfaces.C;
with System.OS_Interface;
package body System.Stack_Checking.Operations is
-- In order to have stack checking working appropriately on
-- VxWorks we need to extract the stack size information from the
-- VxWorks kernel itself. It means that the library for showing
-- task-related information needs to be linked into the VxWorks
-- system, when using stack checking. The TaskShow library can be
-- linked into the VxWorks system by either:
-- * defining INCLUDE_SHOW_ROUTINES in config.h when using
-- configuration header files, or
-- * selecting INCLUDE_TASK_SHOW when using the Tornado project
-- facility.
function Set_Stack_Info (Stack : access Stack_Access) return Stack_Access;
-- The function Set_Stack_Info is the actual function that updates
-- the cache containing a pointer to the Stack_Info. It may also
-- be used for detecting asynchronous abort in combination with
-- Invalidate_Self_Cache.
-- Set_Stack_Info should do the following things in order:
-- 1) Get the Stack_Access value for the current task
-- 2) Set Stack.all to the value obtained in 1)
-- 3) Optionally Poll to check for asynchronous abort
-- This order is important because if at any time a write to
-- the stack cache is pending, that write should be followed
-- by a Poll to prevent loosing signals.
-- Note: This function must be compiled with Polling turned off
-- Note: on systems like VxWorks and OS/2 with real thread-local storage,
-- Set_Stack_Info should return an access value for such local
-- storage. In those cases the cache will always be up-to-date.
-- The following constants should be imported from some system-specific
-- constants package. The constants must be static for performance reasons.
----------------------------
-- Invalidate_Stack_Cache --
----------------------------
procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access) is
pragma Warnings (Off, Any_Stack);
begin
Cache := Null_Stack;
end Invalidate_Stack_Cache;
--------------------
-- Set_Stack_Info --
--------------------
function Set_Stack_Info
(Stack : access Stack_Access) return Stack_Access
is
-- Task descriptor that is handled internally by the VxWorks kernel
type Task_Descriptor is record
T_Id : Interfaces.C.int; -- task identifier
Td_Name : System.Address; -- task name
Td_Priority : Interfaces.C.int; -- task priority
Td_Status : Interfaces.C.int; -- task status
Td_Options : Interfaces.C.int; -- task option bits (see below)
Td_Entry : System.Address; -- original entry point of task
Td_Sp : System.Address; -- saved stack pointer
Td_PStackBase : System.Address; -- the bottom of the stack
Td_PStackLimit : System.Address; -- the effective end of the stack
Td_PStackEnd : System.Address; -- the actual end of the stack
Td_StackSize : Interfaces.C.int; -- size of stack in bytes
Td_StackCurrent : Interfaces.C.int; -- current stack usage in bytes
Td_StackHigh : Interfaces.C.int; -- maximum stack usage in bytes
Td_StackMargin : Interfaces.C.int; -- current stack margin in bytes
Td_ErrorStatus : Interfaces.C.int; -- most recent task error status
Td_Delay : Interfaces.C.int; -- delay/timeout ticks
end record;
-- This VxWorks procedure fills in a specified task descriptor
-- for a specified task.
procedure TaskInfoGet (T_Id : System.OS_Interface.t_id;
Task_Desc : access Task_Descriptor);
pragma Import (C, TaskInfoGet, "taskInfoGet");
My_Stack : Stack_Access;
Task_Desc : aliased Task_Descriptor;
begin
-- The order of steps 1 .. 3 is important, see specification.
-- 1) Get the Stack_Access value for the current task
My_Stack := Soft_Links.Get_Stack_Info.all;
if My_Stack.Base = Null_Address then
-- First invocation. Ask the VxWorks kernel about stack
-- values.
TaskInfoGet (System.OS_Interface.taskIdSelf, Task_Desc'Access);
My_Stack.Size := System.Storage_Elements.Storage_Offset
(Task_Desc.Td_StackSize);
My_Stack.Base := Task_Desc.Td_PStackBase;
My_Stack.Limit := Task_Desc.Td_PStackLimit;
end if;
-- 2) Set Stack.all to the value obtained in 1)
Stack.all := My_Stack;
-- 3) Optionally Poll to check for asynchronous abort
if Soft_Links.Check_Abort_Status.all /= 0 then
raise Standard'Abort_Signal;
end if;
return My_Stack; -- Never trust the cached value, but return local copy!
end Set_Stack_Info;
--------------------
-- Set_Stack_Size --
--------------------
-- Specify the stack size for the current frame.
procedure Set_Stack_Size
(Stack_Size : System.Storage_Elements.Storage_Offset)
is
My_Stack : Stack_Access;
Frame_Address : constant System.Address := My_Stack'Address;
begin
My_Stack := Stack_Check (Frame_Address);
if Stack_Grows_Down then
My_Stack.Limit := My_Stack.Base - Stack_Size;
else
My_Stack.Limit := My_Stack.Base + Stack_Size;
end if;
end Set_Stack_Size;
-----------------
-- Stack_Check --
-----------------
function Stack_Check
(Stack_Address : System.Address) return Stack_Access
is
type Frame_Marker is null record;
Marker : Frame_Marker;
Cached_Stack : constant Stack_Access := Cache;
Frame_Address : constant System.Address := Marker'Address;
begin
-- This function first does a "cheap" check which is correct
-- if it succeeds. In case of failure, the full check is done.
-- Ideally the cheap check should be done in an optimized manner,
-- or be inlined.
if (Stack_Grows_Down and then
(Frame_Address <= Cached_Stack.Base
and
Stack_Address > Cached_Stack.Limit))
or else
(not Stack_Grows_Down and then
(Frame_Address >= Cached_Stack.Base
and
Stack_Address < Cached_Stack.Limit))
then
-- Cached_Stack is valid as it passed the stack check
return Cached_Stack;
end if;
Full_Check :
declare
My_Stack : constant Stack_Access := Set_Stack_Info (Cache'Access);
-- At this point Stack.all might already be invalid, so
-- it is essential to use our local copy of Stack!
begin
if (Stack_Grows_Down and then
Stack_Address < My_Stack.Limit)
or else
(not Stack_Grows_Down and then
Stack_Address > My_Stack.Limit)
then
Ada.Exceptions.Raise_Exception
(E => Storage_Error'Identity,
Message => "stack overflow detected");
end if;
return My_Stack;
end Full_Check;
end Stack_Check;
------------------------
-- Update_Stack_Cache --
------------------------
procedure Update_Stack_Cache (Stack : Stack_Access) is
begin
if not Multi_Processor then
Cache := Stack;
end if;
end Update_Stack_Cache;
end System.Stack_Checking.Operations;
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