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------------------------------------------------------------------------------
-- --
-- GNAT 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 --
-- --
-- S p e c --
-- --
-- Copyright (C) 1999-2007, 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, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, 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 package provides a implementation of stack checking operations using
-- comparison with stack base and limit.
pragma Restrictions (No_Elaboration_Code);
-- We want to guarantee the absence of elaboration code because the binder
-- does not handle references to this package.
pragma Polling (Off);
-- Turn off polling, we do not want polling to take place during stack
-- checking operations. It causes infinite loops and other problems.
with System.Storage_Elements;
package System.Stack_Checking.Operations is
pragma Preelaborate;
procedure Update_Stack_Cache (Stack : Stack_Access);
-- Set the stack cache for the current task. Note that this is only for
-- optimization purposes, nothing can be assumed about the contents of the
-- cache at any time, see Set_Stack_Info.
--
-- The stack cache should contain the bounds of the current task. But
-- because the RTS is not aware of task switches, the stack cache may be
-- incorrect. So when the stack pointer is not within the bounds of the
-- stack cache, Stack_Check first update the cache (which is a costly
-- operation hence the need of a cache).
procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access);
-- Invalidate cache entries for the task T that owns Any_Stack. This causes
-- the Set_Stack_Info function to be called during the next stack check
-- done by T. This can be used to interrupt task T asynchronously.
-- Stack_Check should be called in loops for this to work reliably.
function Stack_Check (Stack_Address : System.Address) return Stack_Access;
-- This version of Stack_Check should not be inlined
procedure Notify_Stack_Attributes
(Initial_SP : System.Address;
Size : System.Storage_Elements.Storage_Offset);
-- Register Initial_SP as the initial stack pointer value for the current
-- task when it starts and Size as the associated stack area size. This
-- should be called once, after the soft-links have been initialized and
-- prior to the first "Stack_Check" call.
private
Cache : aliased Stack_Access := Null_Stack;
pragma Export (C, Cache, "_gnat_stack_cache");
pragma Export (C, Stack_Check, "_gnat_stack_check");
end System.Stack_Checking.Operations;
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