File : s-stache.ads
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 -- --
19 -- --
20 -- --
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
38 pragma Compiler_Unit_Warning;
39
40 with System.Storage_Elements;
41
42 package 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
70 private
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
82 end System.Stack_Checking;