1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . S T A C K _ C H E C K I N G --
9 -- Copyright (C) 1999-2009, Free Software Foundation, Inc. --
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. --
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. --
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/>. --
27 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
30 ------------------------------------------------------------------------------
32 -- This package provides a system-independent implementation of stack
33 -- checking using comparison with stack base and limit.
35 -- This package defines basic types and objects. Operations related to
36 -- stack checking can be found in package System.Stack_Checking.Operations.
38 pragma Warnings (Off);
42 with System.Storage_Elements;
44 package System.Stack_Checking is
46 pragma Elaborate_Body;
47 -- This unit has a junk null body. The reason is that historically we
48 -- used to have a real body, and it causes bootstrapping path problems
49 -- to eliminate it, since the old body may still be present in the
50 -- compilation environment for a build.
52 type Stack_Info is record
53 Limit : System.Address := System.Null_Address;
54 Base : System.Address := System.Null_Address;
55 Size : System.Storage_Elements.Storage_Offset := 0;
57 -- This record may be part of a larger data structure like the
58 -- task control block in the tasking case.
59 -- This specific layout has the advantage of being compatible with the
60 -- Intel x86 BOUNDS instruction.
62 type Stack_Access is access all Stack_Info;
63 -- Unique local storage associated with a specific task. This storage is
64 -- used for the stack base and limit, and is returned by Checked_Self.
65 -- Only self may write this information, it may be read by any task.
66 -- At no time the address range Limit .. Base (or Base .. Limit for
67 -- upgrowing stack) may contain any address that is part of another stack.
68 -- The Stack_Access may be part of a larger data structure.
70 Multi_Processor : constant Boolean := False; -- Not supported yet
74 Null_Stack_Info : aliased Stack_Info :=
75 (Limit => System.Null_Address,
76 Base => System.Null_Address,
78 -- Use explicit assignment to avoid elaboration code (call to init proc)
80 Null_Stack : constant Stack_Access := Null_Stack_Info'Access;
81 -- Stack_Access value that will return a Stack_Base and Stack_Limit
82 -- that fail any stack check.
84 end System.Stack_Checking;