1 /*
2 * Copyright (c) 1997, 2023, 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 #include "precompiled.hpp"
26 #include "classfile/javaClasses.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmClasses.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "logging/log.hpp"
32 #include "logging/logTag.hpp"
33 #include "memory/oopFactory.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/instanceKlass.hpp"
36 #include "oops/klass.inline.hpp"
37 #include "oops/method.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "oops/symbol.hpp"
40 #include "prims/jvm_misc.hpp"
41 #include "prims/jvmtiExport.hpp"
42 #include "prims/nativeLookup.hpp"
43 #include "prims/unsafe.hpp"
44 #include "prims/scopedMemoryAccess.hpp"
45 #include "prims/shipilevMagic.hpp"
46 #include "runtime/arguments.hpp"
47 #include "runtime/handles.inline.hpp"
48 #include "runtime/interfaceSupport.inline.hpp"
49 #include "runtime/javaCalls.hpp"
50 #include "runtime/os.hpp"
51 #include "runtime/sharedRuntime.hpp"
52 #include "runtime/signature.hpp"
53 #include "utilities/macros.hpp"
54 #include "utilities/utf8.hpp"
55 #if INCLUDE_JFR
56 #include "jfr/jfr.hpp"
57 #endif
58
59 /*
60
61 The JNI specification defines the mapping from a Java native method name to
62 a C native library implementation function name as follows:
63
64 The mapping produces a native method name by concatenating the following components
65 derived from a `native` method declaration:
66
67 1. the prefix Java_
68 2. given the binary name, in internal form, of the class which declares the native method:
69 the result of escaping the name.
70 3. an underscore ("_")
71 4. the escaped method name
72 5. if the native method declaration is overloaded: two underscores ("__") followed by the
73 escaped parameter descriptor (JVMS 4.3.3) of the method declaration.
74
75 Escaping leaves every alphanumeric ASCII character (A-Za-z0-9) unchanged, and replaces each
76 UTF-16 code unit n the table below with the corresponding escape sequence. If the name to be
77 escaped contains a surrogate pair, then the high-surrogate code unit and the low-surrogate code
78 unit are escaped separately. The result of escaping is a string consisting only of the ASCII
79 characters A-Za-z0-9 and underscore.
80
81 ------------------------------ ------------------------------------
82 UTF-16 code unit Escape sequence
83 ------------------------------ ------------------------------------
84 Forward slash (/, U+002F) _
85 Underscore (_, U+005F) _1
86 Semicolon (;, U+003B) _2
87 Left square bracket ([, U+005B) _3
88 Any UTF-16 code unit \u_WXYZ_ that does not _0wxyz where w, x, y, and z are the lower-case
89 represent alphanumeric ASCII (A-Za-z0-9), forms of the hexadecimal digits W, X, Y, and Z.
90 forward slash, underscore, semicolon, (For example, U+ABCD becomes _0abcd.)
91 or left square bracket
92 ------------------------------ ------------------------------------
93
94 Note that escape sequences can safely begin _0, _1, etc, because class and method
95 names in Java source code never begin with a number. However, that is not the case in
96 class files that were not generated from Java source code.
97
98 To preserve the 1:1 mapping to a native method name, the VM checks the resulting name as
99 follows. If the process of escaping any precursor string from the native method declaration
100 (class or method name, or argument type) causes a "0", "1", "2", or "3" character
101 from the precursor string to appear unchanged in the result *either* immediately after an
102 underscore *or* at the beginning of the escaped string (where it will follow an underscore
103 in the fully assembled name), then the escaping process is said to have "failed".
104 In such cases, no native library search is performed, and the attempt to link the native
105 method invocation will throw UnsatisfiedLinkError.
106
107
108 For example:
109
110 package/my_class/method
111
112 and
113
114 package/my/1class/method
115
116 both map to
117
118 Java_package_my_1class_method
119
120 To address this potential conflict we need only check if the character after
121 / is a digit 0..3, or if the first character after an injected '_' separator
122 is a digit 0..3. If we encounter an invalid identifier we reset the
123 stringStream and return false. Otherwise the stringStream contains the mapped
124 name and we return true.
125
126 */
127 static bool map_escaped_name_on(stringStream* st, Symbol* name, int begin, int end) {
128 char* bytes = (char*)name->bytes() + begin;
129 char* end_bytes = (char*)name->bytes() + end;
130 bool check_escape_char = true; // initially true as first character here follows '_'
131 while (bytes < end_bytes) {
132 jchar c;
133 bytes = UTF8::next(bytes, &c);
134 if (c <= 0x7f && isalnum(c)) {
135 if (check_escape_char && (c >= '0' && c <= '3')) {
136 // This is a non-Java identifier and we won't escape it to
137 // ensure no name collisions with a Java identifier.
138 if (log_is_enabled(Debug, jni, resolve)) {
139 ResourceMark rm;
140 log_debug(jni, resolve)("[Lookup of native method with non-Java identifier rejected: %s]",
141 name->as_C_string());
142 }
143 st->reset(); // restore to "" on error
144 return false;
145 }
146 st->put((char) c);
147 check_escape_char = false;
148 } else {
149 check_escape_char = false;
150 if (c == '_') st->print("_1");
151 else if (c == '/') {
152 st->print("_");
153 // Following a / we must have non-escape character
154 check_escape_char = true;
155 }
156 else if (c == ';') st->print("_2");
157 else if (c == '[') st->print("_3");
158 else st->print("_%.5x", c);
159 }
160 }
161 return true;
162 }
163
164
165 static bool map_escaped_name_on(stringStream* st, Symbol* name) {
166 return map_escaped_name_on(st, name, 0, name->utf8_length());
167 }
168
169
170 char* NativeLookup::pure_jni_name(const methodHandle& method) {
171 stringStream st;
172 // Prefix
173 st.print("Java_");
174 // Klass name
175 if (!map_escaped_name_on(&st, method->klass_name())) {
176 return nullptr;
177 }
178 st.print("_");
179 // Method name
180 if (!map_escaped_name_on(&st, method->name())) {
181 return nullptr;
182 }
183 return st.as_string();
184 }
185
186 char* NativeLookup::long_jni_name(const methodHandle& method) {
187 // Signatures ignore the wrapping parentheses and the trailing return type
188 stringStream st;
189 Symbol* signature = method->signature();
190 st.print("__");
191 // find ')'
192 int end;
193 for (end = 0; end < signature->utf8_length() && signature->char_at(end) != JVM_SIGNATURE_ENDFUNC; end++);
194 // skip first '('
195 if (!map_escaped_name_on(&st, signature, 1, end)) {
196 return nullptr;
197 }
198
199 return st.as_string();
200 }
201
202 extern "C" {
203 void JNICALL JVM_RegisterMethodHandleMethods(JNIEnv *env, jclass unsafecls);
204 void JNICALL JVM_RegisterReferencesMethods(JNIEnv *env, jclass unsafecls);
205 void JNICALL JVM_RegisterUpcallHandlerMethods(JNIEnv *env, jclass unsafecls);
206 void JNICALL JVM_RegisterUpcallLinkerMethods(JNIEnv *env, jclass unsafecls);
207 void JNICALL JVM_RegisterNativeEntryPointMethods(JNIEnv *env, jclass unsafecls);
208 void JNICALL JVM_RegisterPerfMethods(JNIEnv *env, jclass perfclass);
209 void JNICALL JVM_RegisterWhiteBoxMethods(JNIEnv *env, jclass wbclass);
210 void JNICALL JVM_RegisterVectorSupportMethods(JNIEnv *env, jclass vsclass);
211 #if INCLUDE_JVMCI
212 jobject JNICALL JVM_GetJVMCIRuntime(JNIEnv *env, jclass c);
213 void JNICALL JVM_RegisterJVMCINatives(JNIEnv *env, jclass compilerToVMClass);
214 #endif
215 }
216
217 #define CC (char*) /* cast a literal from (const char*) */
218 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
219
220 static JNINativeMethod lookup_special_native_methods[] = {
221 { CC"Java_jdk_internal_misc_Unsafe_registerNatives", nullptr, FN_PTR(JVM_RegisterJDKInternalMiscUnsafeMethods) },
222 { CC"Java_java_lang_invoke_MethodHandleNatives_registerNatives", nullptr, FN_PTR(JVM_RegisterMethodHandleMethods) },
223 { CC"Java_jdk_internal_foreign_abi_UpcallStubs_registerNatives", nullptr, FN_PTR(JVM_RegisterUpcallHandlerMethods) },
224 { CC"Java_jdk_internal_foreign_abi_UpcallLinker_registerNatives", nullptr, FN_PTR(JVM_RegisterUpcallLinkerMethods) },
225 { CC"Java_jdk_internal_foreign_abi_NativeEntryPoint_registerNatives", nullptr, FN_PTR(JVM_RegisterNativeEntryPointMethods) },
226 { CC"Java_jdk_internal_perf_Perf_registerNatives", nullptr, FN_PTR(JVM_RegisterPerfMethods) },
227 { CC"Java_sun_hotspot_WhiteBox_registerNatives", nullptr, FN_PTR(JVM_RegisterWhiteBoxMethods) },
228 { CC"Java_jdk_test_whitebox_WhiteBox_registerNatives", nullptr, FN_PTR(JVM_RegisterWhiteBoxMethods) },
229 { CC"Java_jdk_internal_vm_vector_VectorSupport_registerNatives", nullptr, FN_PTR(JVM_RegisterVectorSupportMethods)},
230 #if INCLUDE_JVMCI
231 { CC"Java_jdk_vm_ci_runtime_JVMCI_initializeRuntime", nullptr, FN_PTR(JVM_GetJVMCIRuntime) },
232 { CC"Java_jdk_vm_ci_hotspot_CompilerToVM_registerNatives", nullptr, FN_PTR(JVM_RegisterJVMCINatives) },
233 #endif
234 #if INCLUDE_JFR
235 { CC"Java_jdk_jfr_internal_JVM_registerNatives", nullptr, FN_PTR(jfr_register_natives) },
236 #endif
237 { CC"Java_jdk_internal_misc_ScopedMemoryAccess_registerNatives", nullptr, FN_PTR(JVM_RegisterJDKInternalMiscScopedMemoryAccessMethods) },
238 { CC"Java_net_shipilev_Magic_registerNatives", nullptr, FN_PTR(JVM_RegisterNetShipilevMagicMethods) },
239 };
240
241 static address lookup_special_native(const char* jni_name) {
242 int count = sizeof(lookup_special_native_methods) / sizeof(JNINativeMethod);
243 for (int i = 0; i < count; i++) {
244 // NB: To ignore the jni prefix and jni postfix strstr is used matching.
245 if (strstr(jni_name, lookup_special_native_methods[i].name) != nullptr) {
246 return CAST_FROM_FN_PTR(address, lookup_special_native_methods[i].fnPtr);
247 }
248 }
249 return nullptr;
250 }
251
252 address NativeLookup::lookup_style(const methodHandle& method, char* pure_name, const char* long_name, int args_size, bool os_style, TRAPS) {
253 address entry;
254 const char* jni_name = compute_complete_jni_name(pure_name, long_name, args_size, os_style);
255
256
257 // If the loader is null we have a system class, so we attempt a lookup in
258 // the native Java library. This takes care of any bootstrapping problems.
259 // Note: It is critical for bootstrapping that Java_java_lang_ClassLoader_findNative
260 // gets found the first time around - otherwise an infinite loop can occur. This is
261 // another VM/library dependency
262 Handle loader(THREAD, method->method_holder()->class_loader());
263 if (loader.is_null()) {
264 entry = lookup_special_native(jni_name);
265 if (entry == nullptr) {
266 entry = (address) os::dll_lookup(os::native_java_library(), jni_name);
267 }
268 if (entry != nullptr) {
269 return entry;
270 }
271 }
272
273 // Otherwise call static method findNative in ClassLoader
274 Klass* klass = vmClasses::ClassLoader_klass();
275 Handle name_arg = java_lang_String::create_from_str(jni_name, CHECK_NULL);
276
277 JavaValue result(T_LONG);
278 JavaCalls::call_static(&result,
279 klass,
280 vmSymbols::findNative_name(),
281 vmSymbols::classloader_string_long_signature(),
282 // Arguments
283 loader,
284 name_arg,
285 CHECK_NULL);
286 entry = (address) (intptr_t) result.get_jlong();
287
288 if (entry == nullptr) {
289 // findNative didn't find it, if there are any agent libraries look in them
290 AgentLibrary* agent;
291 for (agent = Arguments::agents(); agent != nullptr; agent = agent->next()) {
292 entry = (address) os::dll_lookup(agent->os_lib(), jni_name);
293 if (entry != nullptr) {
294 return entry;
295 }
296 }
297 }
298
299 return entry;
300 }
301
302 const char* NativeLookup::compute_complete_jni_name(const char* pure_name, const char* long_name, int args_size, bool os_style) {
303 stringStream st;
304 if (os_style) {
305 os::print_jni_name_prefix_on(&st, args_size);
306 }
307
308 st.print_raw(pure_name);
309 st.print_raw(long_name);
310 if (os_style) {
311 os::print_jni_name_suffix_on(&st, args_size);
312 }
313
314 return st.as_string();
315 }
316
317 // Check all the formats of native implementation name to see if there is one
318 // for the specified method.
319 address NativeLookup::lookup_entry(const methodHandle& method, TRAPS) {
320 address entry = nullptr;
321 // Compute pure name
322 char* pure_name = pure_jni_name(method);
323 if (pure_name == nullptr) {
324 // JNI name mapping rejected this method so return
325 // null to indicate UnsatisfiedLinkError should be thrown.
326 return nullptr;
327 }
328
329 // Compute argument size
330 int args_size = 1 // JNIEnv
331 + (method->is_static() ? 1 : 0) // class for static methods
332 + method->size_of_parameters(); // actual parameters
333
334 // 1) Try JNI short style
335 entry = lookup_style(method, pure_name, "", args_size, true, CHECK_NULL);
336 if (entry != nullptr) return entry;
337
338 // Compute long name
339 char* long_name = long_jni_name(method);
340 if (long_name == nullptr) {
341 // JNI name mapping rejected this method so return
342 // null to indicate UnsatisfiedLinkError should be thrown.
343 return nullptr;
344 }
345
346 // 2) Try JNI long style
347 entry = lookup_style(method, pure_name, long_name, args_size, true, CHECK_NULL);
348 if (entry != nullptr) return entry;
349
350 // 3) Try JNI short style without os prefix/suffix
351 entry = lookup_style(method, pure_name, "", args_size, false, CHECK_NULL);
352 if (entry != nullptr) return entry;
353
354 // 4) Try JNI long style without os prefix/suffix
355 entry = lookup_style(method, pure_name, long_name, args_size, false, CHECK_NULL);
356
357 return entry; // null indicates not found
358 }
359
360 // Check if there are any JVM TI prefixes which have been applied to the native method name.
361 // If any are found, remove them before attempting the look up of the
362 // native implementation again.
363 // See SetNativeMethodPrefix in the JVM TI Spec for more details.
364 address NativeLookup::lookup_entry_prefixed(const methodHandle& method, TRAPS) {
365 #if INCLUDE_JVMTI
366 ResourceMark rm(THREAD);
367
368 int prefix_count;
369 char** prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
370 char* in_name = method->name()->as_C_string();
371 char* wrapper_name = in_name;
372 // last applied prefix will be first -- go backwards
373 for (int i = prefix_count-1; i >= 0; i--) {
374 char* prefix = prefixes[i];
375 size_t prefix_len = strlen(prefix);
376 if (strncmp(prefix, wrapper_name, prefix_len) == 0) {
377 // has this prefix remove it
378 wrapper_name += prefix_len;
379 }
380 }
381 if (wrapper_name != in_name) {
382 // we have a name for a wrapping method
383 int wrapper_name_len = (int)strlen(wrapper_name);
384 TempNewSymbol wrapper_symbol = SymbolTable::probe(wrapper_name, wrapper_name_len);
385 if (wrapper_symbol != nullptr) {
386 Klass* k = method->method_holder();
387 Method* wrapper_method = k->lookup_method(wrapper_symbol, method->signature());
388 if (wrapper_method != nullptr && !wrapper_method->is_native()) {
389 // we found a wrapper method, use its native entry
390 method->set_is_prefixed_native();
391 return lookup_entry(methodHandle(THREAD, wrapper_method), THREAD);
392 }
393 }
394 }
395 #endif // INCLUDE_JVMTI
396 return nullptr;
397 }
398
399 address NativeLookup::lookup_base(const methodHandle& method, TRAPS) {
400 address entry = nullptr;
401 ResourceMark rm(THREAD);
402
403 entry = lookup_entry(method, CHECK_NULL);
404 if (entry != nullptr) return entry;
405
406 // standard native method resolution has failed. Check if there are any
407 // JVM TI prefixes which have been applied to the native method name.
408 entry = lookup_entry_prefixed(method, CHECK_NULL);
409 if (entry != nullptr) return entry;
410
411 // Native function not found, throw UnsatisfiedLinkError
412 stringStream ss;
413 ss.print("'");
414 method->print_external_name(&ss);
415 ss.print("'");
416 THROW_MSG_0(vmSymbols::java_lang_UnsatisfiedLinkError(), ss.as_string());
417 }
418
419
420 address NativeLookup::lookup(const methodHandle& method, TRAPS) {
421 if (!method->has_native_function()) {
422 address entry = lookup_base(method, CHECK_NULL);
423 method->set_native_function(entry,
424 Method::native_bind_event_is_interesting);
425 // -verbose:jni printing
426 if (log_is_enabled(Debug, jni, resolve)) {
427 ResourceMark rm(THREAD);
428 log_debug(jni, resolve)("[Dynamic-linking native method %s.%s ... JNI]",
429 method->method_holder()->external_name(),
430 method->name()->as_C_string());
431 }
432 }
433 return method->native_function();
434 }