1 /*
2 * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // This table encapsulates the debugging information required by the
26 // serviceability agent in order to run. Specifically, we need to
27 // understand the layout of certain C data structures (offsets, in
28 // bytes, of their fields.)
29 //
30 // There are alternatives for the design of this mechanism, including
31 // parsing platform-specific debugging symbols from a debug build into
32 // a program database. While this current mechanism can be considered
33 // to be a workaround for the inability to debug arbitrary C and C++
34 // programs at the present time, it does have certain advantages.
35 // First, it is platform-independent, which will vastly simplify the
36 // initial bringup of the system both now and on future platforms.
37 // Second, it is embedded within the VM, as opposed to being in a
38 // separate program database; experience has shown that whenever
39 // portions of a system are decoupled, version skew is problematic.
40 // Third, generating a program database, for example for a product
41 // build, would probably require two builds to be done: the desired
42 // product build as well as an intermediary build with the PRODUCT
43 // flag turned on but also compiled with -g, leading to a doubling of
44 // the time required to get a serviceability agent-debuggable product
45 // build. Fourth, and very significantly, this table probably
46 // preserves more information about field types than stabs do; for
47 // example, it preserves the fact that a field is a "jlong" rather
48 // than transforming the type according to the typedef in jni_md.h,
49 // which allows the Java-side code to identify "Java-sized" fields in
50 // C++ data structures. If the symbol parsing mechanism was redone
51 // using stabs, it might still be necessary to have a table somewhere
52 // containing this information.
53 //
54 // Do not change the sizes or signedness of the integer values in
55 // these data structures; they are fixed over in the serviceability
56 // agent's Java code (for bootstrapping).
57
58 typedef struct {
59 const char* typeName; // The type name containing the given field (example: "Klass")
60 const char* fieldName; // The field name within the type (example: "_name")
61 const char* typeString; // Quoted name of the type of this field (example: "symbolOopDesc*";
62 // parsed in Java to ensure type correctness
63 int32_t isStatic; // Indicates whether following field is an offset or an address
64 uint64_t offset; // Offset of field within structure; only used for nonstatic fields
65 void* address; // Address of field; only used for static fields
66 // ("offset" can not be reused because of apparent SparcWorks compiler bug
67 // in generation of initializer data)
68 } VMStructEntry;
69
70 typedef struct {
71 const char* typeName; // Type name (example: "methodOopDesc")
72 const char* superclassName; // Superclass name, or null if none (example: "oopDesc")
73 int32_t isOopType; // Does this type represent an oop typedef? (i.e., "methodOop" or
74 // "klassOop", but NOT "methodOopDesc")
75 int32_t isIntegerType; // Does this type represent an integer type (of arbitrary size)?
76 int32_t isUnsigned; // If so, is it unsigned?
77 uint64_t size; // Size, in bytes, of the type
78 } VMTypeEntry;
79
80 typedef struct {
81 const char* name; // Name of constant (example: "_thread_in_native")
82 int32_t value; // Value of constant
83 } VMIntConstantEntry;
84
85 typedef struct {
86 const char* name; // Name of constant (example: "_thread_in_native")
87 uint64_t value; // Value of constant
88 } VMLongConstantEntry;
89
90 // This class is a friend of most classes, to be able to access
91 // private fields
92 class VMStructs {
93 public:
94 // The last entry is identified over in the serviceability agent by
95 // the fact that it has a NULL fieldName
96 static VMStructEntry localHotSpotVMStructs[];
97
98 // The last entry is identified over in the serviceability agent by
99 // the fact that it has a NULL typeName
100 static VMTypeEntry localHotSpotVMTypes[];
101
102 // Table of integer constants required by the serviceability agent.
103 // The last entry is identified over in the serviceability agent by
104 // the fact that it has a NULL typeName
105 static VMIntConstantEntry localHotSpotVMIntConstants[];
106
107 // Table of long constants required by the serviceability agent.
108 // The last entry is identified over in the serviceability agent by
109 // the fact that it has a NULL typeName
110 static VMLongConstantEntry localHotSpotVMLongConstants[];
111
112 // This is used to run any checking code necessary for validation of
113 // the data structure (debug build only)
114 static void init();
115
116 private:
117 // Look up a type in localHotSpotVMTypes using strcmp() (debug build only).
118 // Returns 1 if found, 0 if not.
119 // debug_only(static int findType(const char* typeName);)
120 static int findType(const char* typeName);
121 };