1------------------------------------------------------------------------------ 2-- -- 3-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- 4-- -- 5-- S Y S T E M . S T A C K _ C H E C K I N G -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1999-2013, 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-- This package provides a system-independent implementation of stack 33-- checking using comparison with stack base and limit. 34 35-- This package defines basic types and objects. Operations related to 36-- stack checking can be found in package System.Stack_Checking.Operations. 37 38pragma Compiler_Unit_Warning; 39 40with System.Storage_Elements; 41 42package System.Stack_Checking is 43 pragma Preelaborate; 44 pragma Elaborate_Body; 45 -- This unit has a junk null body. The reason is that historically we 46 -- used to have a real body, and it causes bootstrapping path problems 47 -- to eliminate it, since the old body may still be present in the 48 -- compilation environment for a build. 49 50 type Stack_Info is record 51 Limit : System.Address := System.Null_Address; 52 Base : System.Address := System.Null_Address; 53 Size : System.Storage_Elements.Storage_Offset := 0; 54 end record; 55 -- This record may be part of a larger data structure like the 56 -- task control block in the tasking case. 57 -- This specific layout has the advantage of being compatible with the 58 -- Intel x86 BOUNDS instruction. 59 60 type Stack_Access is access all Stack_Info; 61 -- Unique local storage associated with a specific task. This storage is 62 -- used for the stack base and limit, and is returned by Checked_Self. 63 -- Only self may write this information, it may be read by any task. 64 -- At no time the address range Limit .. Base (or Base .. Limit for 65 -- upgrowing stack) may contain any address that is part of another stack. 66 -- The Stack_Access may be part of a larger data structure. 67 68 Multi_Processor : constant Boolean := False; -- Not supported yet 69 70private 71 72 Null_Stack_Info : aliased Stack_Info := 73 (Limit => System.Null_Address, 74 Base => System.Null_Address, 75 Size => 0); 76 -- Use explicit assignment to avoid elaboration code (call to init proc) 77 78 Null_Stack : constant Stack_Access := Null_Stack_Info'Access; 79 -- Stack_Access value that will return a Stack_Base and Stack_Limit 80 -- that fail any stack check. 81 82end System.Stack_Checking; 83