1 /*
2 * Copyright (c) 2003, 2024, 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.
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23 */
24
25 #ifndef SHARE_CLASSFILE_VERIFICATIONTYPE_HPP
26 #define SHARE_CLASSFILE_VERIFICATIONTYPE_HPP
27
28 #include "oops/instanceKlass.hpp"
29 #include "oops/oop.hpp"
30 #include "oops/symbol.hpp"
31 #include "runtime/handles.hpp"
32 #include "runtime/signature.hpp"
33
34 enum : uint {
35 // As specified in the JVM spec
36 ITEM_Top = 0,
37 ITEM_Integer = 1,
38 ITEM_Float = 2,
39 ITEM_Double = 3,
40 ITEM_Long = 4,
41 ITEM_Null = 5,
42 ITEM_UninitializedThis = 6,
43 ITEM_Object = 7,
44 ITEM_Uninitialized = 8,
45 ITEM_Bogus = (uint)-1
46 };
47
48 class ClassVerifier;
49
50 class VerificationType {
51 private:
52 // Least significant 2 bits of _sym are always 0, so we use these as
53 // the indicator that _sym is a valid pointer. Otherwise, the _data field
54 // contains encoded data (as specified below). Should the VM change
55 // and the lower 2 bits of Symbol* aren't 0, the assert in the constructor
56 // will catch this and we'll have to add a descriminator tag to this
57 // structure.
58 union {
59 Symbol* _sym;
60 uintptr_t _data;
61 } _u;
62
63 enum {
64 // These rest are not found in classfiles, but used by the verifier
65 ITEM_Boolean = 9, ITEM_Byte, ITEM_Short, ITEM_Char,
66 ITEM_Long_2nd, ITEM_Double_2nd
67 };
68
69 // Enum for the _data field
70 enum : uint {
71 // Bottom three bits determine if the type is a reference, inline type,
72 // primitive, uninitialized or a query-type.
73 TypeMask = 0x00000007,
74
75 // Topmost types encoding
76 Reference = 0x0, // _sym contains the name of an object
77 Primitive = 0x1, // see below for primitive list
78 Uninitialized = 0x2, // 0x00ffff00 contains bci
79 TypeQuery = 0x3, // Meta-types used for category testing
80
81 // Utility flags
82 ReferenceFlag = 0x00, // For reference query types
83 Category1Flag = 0x01, // One-word values
84 Category2Flag = 0x02, // First word of a two-word value
85 Category2_2ndFlag = 0x04, // Second word of a two-word value
86
87 // special reference values
88 Null = 0x00000000, // A reference with a 0 sym is null
89
90 // Primitives categories (the second byte determines the category)
91 Category1 = (Category1Flag << 1 * BitsPerByte) | Primitive,
92 Category2 = (Category2Flag << 1 * BitsPerByte) | Primitive,
93 Category2_2nd = (Category2_2ndFlag << 1 * BitsPerByte) | Primitive,
94
95 // Primitive values (type descriminator stored in most-signifcant bytes)
96 // Bogus needs the " | Primitive". Else, is_reference(Bogus) returns TRUE.
97 Bogus = (ITEM_Bogus << 2 * BitsPerByte) | Primitive,
98 Boolean = (ITEM_Boolean << 2 * BitsPerByte) | Category1,
99 Byte = (ITEM_Byte << 2 * BitsPerByte) | Category1,
100 Short = (ITEM_Short << 2 * BitsPerByte) | Category1,
101 Char = (ITEM_Char << 2 * BitsPerByte) | Category1,
102 Integer = (ITEM_Integer << 2 * BitsPerByte) | Category1,
103 Float = (ITEM_Float << 2 * BitsPerByte) | Category1,
104 Long = (ITEM_Long << 2 * BitsPerByte) | Category2,
105 Double = (ITEM_Double << 2 * BitsPerByte) | Category2,
106 Long_2nd = (ITEM_Long_2nd << 2 * BitsPerByte) | Category2_2nd,
107 Double_2nd = (ITEM_Double_2nd << 2 * BitsPerByte) | Category2_2nd,
108
109 // Used by Uninitialized (second and third bytes hold the bci)
110 BciMask = 0xffff << 1 * BitsPerByte,
111 BciForThis = ((u2)-1), // A bci of -1 is an Unintialized-This
112
113 // Query values
114 ReferenceQuery = (ReferenceFlag << 1 * BitsPerByte) | TypeQuery,
115 Category1Query = (Category1Flag << 1 * BitsPerByte) | TypeQuery,
116 Category2Query = (Category2Flag << 1 * BitsPerByte) | TypeQuery,
117 Category2_2ndQuery = (Category2_2ndFlag << 1 * BitsPerByte) | TypeQuery,
118 };
119
120 VerificationType(uintptr_t raw_data) {
121 _u._data = raw_data;
122 }
123
124 public:
125
126 VerificationType() { *this = bogus_type(); }
127
128 // Create verification types
129 static VerificationType bogus_type() { return VerificationType(Bogus); }
130 static VerificationType top_type() { return bogus_type(); } // alias
131 static VerificationType null_type() { return VerificationType(Null); }
132 static VerificationType integer_type() { return VerificationType(Integer); }
133 static VerificationType float_type() { return VerificationType(Float); }
134 static VerificationType long_type() { return VerificationType(Long); }
135 static VerificationType long2_type() { return VerificationType(Long_2nd); }
136 static VerificationType double_type() { return VerificationType(Double); }
137 static VerificationType boolean_type() { return VerificationType(Boolean); }
138 static VerificationType byte_type() { return VerificationType(Byte); }
139 static VerificationType char_type() { return VerificationType(Char); }
140 static VerificationType short_type() { return VerificationType(Short); }
141 static VerificationType double2_type()
142 { return VerificationType(Double_2nd); }
143
144 // "check" types are used for queries. A "check" type is not assignable
145 // to anything, but the specified types are assignable to a "check". For
146 // example, any category1 primitive is assignable to category1_check and
147 // any reference is assignable to reference_check.
148 static VerificationType reference_check()
149 { return VerificationType(ReferenceQuery); }
150 static VerificationType category1_check()
151 { return VerificationType(Category1Query); }
152 static VerificationType category2_check()
153 { return VerificationType(Category2Query); }
154 static VerificationType category2_2nd_check()
155 { return VerificationType(Category2_2ndQuery); }
156
157 // For reference types, store the actual Symbol
158 static VerificationType reference_type(Symbol* sh) {
159 assert(((uintptr_t)sh & TypeMask) == 0, "Symbols must be aligned");
160 // If the above assert fails in the future because oop* isn't aligned,
161 // then this type encoding system will have to change to have a tag value
162 // to discriminate between oops and primitives.
163 return VerificationType((uintptr_t)sh);
164 }
165 static VerificationType uninitialized_type(u2 bci)
166 { return VerificationType(bci << 1 * BitsPerByte | Uninitialized); }
167 static VerificationType uninitialized_this_type()
168 { return uninitialized_type(BciForThis); }
169
170 // Create based on u1 read from classfile
171 static VerificationType from_tag(u1 tag);
172
173 bool is_bogus() const { return (_u._data == Bogus); }
174 bool is_null() const { return (_u._data == Null); }
175 bool is_boolean() const { return (_u._data == Boolean); }
176 bool is_byte() const { return (_u._data == Byte); }
177 bool is_char() const { return (_u._data == Char); }
178 bool is_short() const { return (_u._data == Short); }
179 bool is_integer() const { return (_u._data == Integer); }
180 bool is_long() const { return (_u._data == Long); }
181 bool is_float() const { return (_u._data == Float); }
182 bool is_double() const { return (_u._data == Double); }
183 bool is_long2() const { return (_u._data == Long_2nd); }
184 bool is_double2() const { return (_u._data == Double_2nd); }
185 bool is_reference() const { return ((_u._data & TypeMask) == Reference); }
186 bool is_category1() const {
187 // This should return true for all one-word types, which are category1
188 // primitives, references (including uninitialized refs) and inline types.
189 // Though the 'query' types should technically return 'false' here, if we
190 // allow this to return true, we can perform the test using only
191 // 2 operations rather than 8 (3 masks, 3 compares and 2 logical 'ands').
192 // Since no one should call this on a query type anyway, this is ok.
193 assert(!is_check(), "Must not be a check type (wrong value returned)");
194 return ((_u._data & Category1) != Primitive);
195 // should only return false if it's a primitive, and the category1 flag
196 // is not set.
197 }
198 bool is_category2() const { return ((_u._data & Category2) == Category2); }
199 bool is_category2_2nd() const {
200 return ((_u._data & Category2_2nd) == Category2_2nd);
201 }
202 bool is_reference_check() const { return _u._data == ReferenceQuery; }
203 bool is_category1_check() const { return _u._data == Category1Query; }
204 bool is_category2_check() const { return _u._data == Category2Query; }
205 bool is_category2_2nd_check() const { return _u._data == Category2_2ndQuery; }
206 bool is_check() const { return (_u._data & TypeQuery) == TypeQuery; }
207
208 bool is_x_array(char sig) const {
209 return is_null() || (is_array() && (name()->char_at(1) == sig));
210 }
211 bool is_int_array() const { return is_x_array(JVM_SIGNATURE_INT); }
212 bool is_byte_array() const { return is_x_array(JVM_SIGNATURE_BYTE); }
213 bool is_bool_array() const { return is_x_array(JVM_SIGNATURE_BOOLEAN); }
214 bool is_char_array() const { return is_x_array(JVM_SIGNATURE_CHAR); }
215 bool is_short_array() const { return is_x_array(JVM_SIGNATURE_SHORT); }
216 bool is_long_array() const { return is_x_array(JVM_SIGNATURE_LONG); }
217 bool is_float_array() const { return is_x_array(JVM_SIGNATURE_FLOAT); }
218 bool is_double_array() const { return is_x_array(JVM_SIGNATURE_DOUBLE); }
219 bool is_object_array() const { return is_x_array(JVM_SIGNATURE_CLASS); }
220 bool is_array_array() const { return is_x_array(JVM_SIGNATURE_ARRAY); }
221 bool is_reference_array() const
222 { return is_object_array() || is_array_array(); }
223 bool is_nonscalar_array() const
224 { return is_object_array() || is_array_array(); }
225 bool is_object() const
226 { return (is_reference() && !is_null() && name()->utf8_length() >= 1 &&
227 name()->char_at(0) != JVM_SIGNATURE_ARRAY); }
228 bool is_array() const
229 { return (is_reference() && !is_null() && name()->utf8_length() >= 2 &&
230 name()->char_at(0) == JVM_SIGNATURE_ARRAY); }
231 bool is_uninitialized() const
232 { return ((_u._data & Uninitialized) == Uninitialized); }
233 bool is_uninitialized_this() const
234 { return is_uninitialized() && bci() == BciForThis; }
235
236 VerificationType to_category2_2nd() const {
237 assert(is_category2(), "Must be a double word");
238 return VerificationType(is_long() ? Long_2nd : Double_2nd);
239 }
240
241 u2 bci() const {
242 assert(is_uninitialized(), "Must be uninitialized type");
243 return ((_u._data & BciMask) >> 1 * BitsPerByte);
244 }
245
246 Symbol* name() const {
247 assert(!is_null() && is_reference(), "Must be a non-null reference");
248 return _u._sym;
249 }
250
251 bool equals(const VerificationType& t) const {
252 return (_u._data == t._u._data ||
253 (((is_reference() && t.is_reference())) &&
254 !is_null() && !t.is_null() && name() == t.name()));
255
256 }
257
258 bool operator ==(const VerificationType& t) const {
259 return equals(t);
260 }
261
262 bool operator !=(const VerificationType& t) const {
263 return !equals(t);
264 }
265
266 // The whole point of this type system - check to see if one type
267 // is assignable to another. Returns true if one can assign 'from' to
268 // this.
269 bool is_assignable_from(
270 const VerificationType& from, ClassVerifier* context,
271 bool from_field_is_protected, TRAPS) const {
272 if (equals(from) || is_bogus()) {
273 return true;
274 } else {
275 switch(_u._data) {
276 case Category1Query:
277 return from.is_category1();
278 case Category2Query:
279 return from.is_category2();
280 case Category2_2ndQuery:
281 return from.is_category2_2nd();
282 case ReferenceQuery:
283 return from.is_reference() || from.is_uninitialized();
284 case Boolean:
285 case Byte:
286 case Char:
287 case Short:
288 // An int can be assigned to boolean, byte, char or short values.
289 return from.is_integer();
290 default:
291 if (is_reference() && from.is_reference()) {
292 return is_reference_assignable_from(from, context,
293 from_field_is_protected,
294 THREAD);
295 } else {
296 return false;
297 }
298 }
299 }
300 }
301
302 // Check to see if one array component type is assignable to another.
303 // Same as is_assignable_from() except int primitives must be identical.
304 bool is_component_assignable_from(
305 const VerificationType& from, ClassVerifier* context,
306 bool from_field_is_protected, TRAPS) const {
307 if (equals(from) || is_bogus()) {
308 return true;
309 } else {
310 switch(_u._data) {
311 case Boolean:
312 case Byte:
313 case Char:
314 case Short:
315 return false;
316 default:
317 return is_assignable_from(from, context, from_field_is_protected, THREAD);
318 }
319 }
320 }
321
322 VerificationType get_component(ClassVerifier* context) const;
323
324 int dimensions() const {
325 assert(is_array(), "Must be an array");
326 int index = 0;
327 while (name()->char_at(index) == JVM_SIGNATURE_ARRAY) index++;
328 return index;
329 }
330
331 void print_on(outputStream* st) const;
332
333 private:
334
335 bool is_reference_assignable_from(
336 const VerificationType&, ClassVerifier*, bool from_field_is_protected,
337 TRAPS) const;
338
339 public:
340 static bool resolve_and_check_assignability(InstanceKlass* klass, Symbol* name,
341 Symbol* from_name, bool from_field_is_protected,
342 bool from_is_array, bool from_is_object,
343 TRAPS);
344 };
345
346 #endif // SHARE_CLASSFILE_VERIFICATIONTYPE_HPP