1 /*
2 * Copyright (c) 2003, 2008, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * Copyright 2003 Wily Technology, Inc.
28 */
29
30 #include <jni.h>
31 #include <jvmti.h>
32
33 #include "JPLISAssert.h"
34 #include "Reentrancy.h"
35 #include "JPLISAgent.h"
36
37 /*
38 * This module provides some utility functions to support the "same thread" re-entrancy management.
39 * Uses JVMTI TLS to store a single bit per thread.
40 * Non-zero means the thread is already inside; zero means the thread is not inside.
41 */
42
43 /*
44 * Local prototypes
45 */
46
47 /* Wrapper around set that does the set then re-fetches to make sure it worked.
48 * Degenerates to a simple set when assertions are disabled.
49 * This routine is only here because of a bug in the JVMTI where set to 0 fails.
50 */
51 jvmtiError
52 confirmingTLSSet( jvmtiEnv * jvmtienv,
53 jthread thread,
54 const void * newValue);
55
56 /* Confirmation routine only; used to assure that the TLS slot holds the value we expect it to. */
57 void
58 assertTLSValue( jvmtiEnv * jvmtienv,
59 jthread thread,
60 const void * expected);
61
62
63 #define JPLIS_CURRENTLY_INSIDE_TOKEN ((void *) 0x7EFFC0BB)
64 #define JPLIS_CURRENTLY_OUTSIDE_TOKEN ((void *) 0)
65
66
67 jvmtiError
68 confirmingTLSSet( jvmtiEnv * jvmtienv,
69 jthread thread,
70 const void * newValue) {
71 jvmtiError error;
72
73 error = (*jvmtienv)->SetThreadLocalStorage(
74 jvmtienv,
75 thread,
76 newValue);
77 check_phase_ret_blob(error, error);
78
79 #if JPLISASSERT_ENABLEASSERTIONS
80 assertTLSValue( jvmtienv,
81 thread,
82 newValue);
83 #endif
84
85 return error;
86 }
87
88 void
89 assertTLSValue( jvmtiEnv * jvmtienv,
90 jthread thread,
91 const void * expected) {
92 jvmtiError error;
93 #if defined _WIN32 && _MSC_VER >= 1900
94 void * test = (void *)(uintptr_t) 0x99999999;
95 #else
96 void * test = (void *) 0x99999999;
97 #endif
98
99 /* now check if we do a fetch we get what we wrote */
100 error = (*jvmtienv)->GetThreadLocalStorage(
101 jvmtienv,
102 thread,
103 &test);
104 check_phase_ret(error);
105 jplis_assert(error == JVMTI_ERROR_NONE);
106 jplis_assert(test == expected);
107 }
108
109 jboolean
110 tryToAcquireReentrancyToken( jvmtiEnv * jvmtienv,
111 jthread thread) {
112 jboolean result = JNI_FALSE;
113 jvmtiError error = JVMTI_ERROR_NONE;
114 void * storedValue = NULL;
115
116 error = (*jvmtienv)->GetThreadLocalStorage(
117 jvmtienv,
118 thread,
119 &storedValue);
120 check_phase_ret_false(error);
121 jplis_assert(error == JVMTI_ERROR_NONE);
122 if ( error == JVMTI_ERROR_NONE ) {
123 /* if this thread is already inside, just return false and short-circuit */
124 if ( storedValue == JPLIS_CURRENTLY_INSIDE_TOKEN ) {
125 result = JNI_FALSE;
126 }
127 else {
128 /* stuff in the sentinel and return true */
129 #if JPLISASSERT_ENABLEASSERTIONS
130 assertTLSValue( jvmtienv,
131 thread,
132 JPLIS_CURRENTLY_OUTSIDE_TOKEN);
133 #endif
134 error = confirmingTLSSet ( jvmtienv,
135 thread,
136 JPLIS_CURRENTLY_INSIDE_TOKEN);
137 check_phase_ret_false(error);
138 jplis_assert(error == JVMTI_ERROR_NONE);
139 if ( error != JVMTI_ERROR_NONE ) {
140 result = JNI_FALSE;
141 }
142 else {
143 result = JNI_TRUE;
144 }
145 }
146 }
147 return result;
148 }
149
150
151 void
152 releaseReentrancyToken( jvmtiEnv * jvmtienv,
153 jthread thread) {
154 jvmtiError error = JVMTI_ERROR_NONE;
155
156 /* assert we hold the token */
157 #if JPLISASSERT_ENABLEASSERTIONS
158 assertTLSValue( jvmtienv,
159 thread,
160 JPLIS_CURRENTLY_INSIDE_TOKEN);
161 #endif
162
163 error = confirmingTLSSet( jvmtienv,
164 thread,
165 JPLIS_CURRENTLY_OUTSIDE_TOKEN);
166 check_phase_ret(error);
167 jplis_assert(error == JVMTI_ERROR_NONE);
168
169 }