CodeVerify.h revision 228a6b01918304f2cd1213c722e028a6e25252bb 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * Dalvik bytecode verifier.
19 */
20#ifndef _DALVIK_CODEVERIFY
21#define _DALVIK_CODEVERIFY
22
23#include "analysis/VerifySubs.h"
24
25
26/*
27 * Enumeration for register type values.  The "hi" piece of a 64-bit value
28 * MUST immediately follow the "lo" piece in the enumeration, so we can check
29 * that hi==lo+1.
30 *
31 * Assignment of constants:
32 *   [-MAXINT,-32768)   : integer
33 *   [-32768,-128)      : short
34 *   [-128,0)           : byte
35 *   0                  : zero
36 *   1                  : one
37 *   [2,128)            : posbyte
38 *   [128,32768)        : posshort
39 *   [32768,65536)      : char
40 *   [65536,MAXINT]     : integer
41 *
42 * Allowed "implicit" widening conversions:
43 *   zero -> boolean, posbyte, byte, posshort, short, char, integer, ref (null)
44 *   one -> boolean, posbyte, byte, posshort, short, char, integer
45 *   boolean -> posbyte, byte, posshort, short, char, integer
46 *   posbyte -> posshort, short, integer, char
47 *   byte -> short, integer
48 *   posshort -> integer, char
49 *   short -> integer
50 *   char -> integer
51 *
52 * In addition, all of the above can convert to "float".
53 *
54 * We're more careful with integer values than the spec requires.  The
55 * motivation is to restrict byte/char/short to the correct range of values.
56 * For example, if a method takes a byte argument, we don't want to allow
57 * the code to load the constant "1024" and pass it in.
58 */
59enum {
60    kRegTypeUnknown = 0,    /* initial state; use value=0 so calloc works */
61    kRegTypeUninit = 1,     /* MUST be odd to distinguish from pointer */
62    kRegTypeConflict,       /* merge clash makes this reg's type unknowable */
63
64    /*
65     * Category-1nr types.  The order of these is chiseled into a couple
66     * of tables, so don't add, remove, or reorder if you can avoid it.
67     */
68#define kRegType1nrSTART    kRegTypeFloat
69    kRegTypeFloat,
70    kRegTypeZero,           /* 32-bit 0, could be Boolean, Int, Float, or Ref */
71    kRegTypeOne,            /* 32-bit 1, could be Boolean, Int, Float */
72    kRegTypeBoolean,        /* must be 0 or 1 */
73    kRegTypePosByte,        /* byte, known positive (can become char) */
74    kRegTypeByte,
75    kRegTypePosShort,       /* short, known positive (can become char) */
76    kRegTypeShort,
77    kRegTypeChar,
78    kRegTypeInteger,
79#define kRegType1nrEND      kRegTypeInteger
80
81    kRegTypeLongLo,         /* lower-numbered register; endian-independent */
82    kRegTypeLongHi,
83    kRegTypeDoubleLo,
84    kRegTypeDoubleHi,
85
86    /*
87     * Enumeration max; this is used with "full" (32-bit) RegType values.
88     *
89     * Anything larger than this is a ClassObject or uninit ref.  Mask off
90     * all but the low 8 bits; if you're left with kRegTypeUninit, pull
91     * the uninit index out of the high 24.  Because kRegTypeUninit has an
92     * odd value, there is no risk of a particular ClassObject pointer bit
93     * pattern being confused for it (assuming our class object allocator
94     * uses word alignment).
95     */
96    kRegTypeMAX
97};
98#define kRegTypeUninitMask  0xff
99#define kRegTypeUninitShift 8
100
101/*
102 * RegType holds information about the type of data held in a register.
103 * For most types it's a simple enum.  For reference types it holds a
104 * pointer to the ClassObject, and for uninitialized references it holds
105 * an index into the UninitInstanceMap.
106 */
107typedef u4 RegType;
108
109/*
110 * Table that maps uninitialized instances to classes, based on the
111 * address of the new-instance instruction.
112 */
113typedef struct UninitInstanceMap {
114    int numEntries;
115    struct {
116        int             addr;   /* code offset, or -1 for method arg ("this") */
117        ClassObject*    clazz;  /* class created at this address */
118    } map[1];
119} UninitInstanceMap;
120#define kUninitThisArgAddr  (-1)
121#define kUninitThisArgSlot  0
122
123/*
124 * Various bits of data generated by the verifier, wrapped up in a package
125 * for ease of use by the register map generator.
126 */
127typedef struct VerifierData {
128    /*
129     * The method we're working on.
130     */
131    const Method*   method;
132
133    /*
134     * Number of code units of instructions in the method.  A cache of the
135     * value calculated by dvmGetMethodInsnsSize().
136     */
137    u4              insnsSize;
138
139    /*
140     * Number of registers we track for each instruction.  This is equal
141     * to the method's declared "registersSize".  (Does not include the
142     * pending return value.)
143     */
144    u4              insnRegCount;
145
146    /*
147     * Instruction widths and flags, one entry per code unit.
148     */
149    InsnFlags*      insnFlags;
150
151    /*
152     * Uninitialized instance map, used for tracking the movement of
153     * objects that have been allocated but not initialized.
154     */
155    UninitInstanceMap* uninitMap;
156
157    /*
158     * Array of SRegType arrays, one entry per code unit.  We only need
159     * entries for code units that hold the start of an "interesting"
160     * instruction.  For register map generation, we're only interested
161     * in GC points.
162     */
163    RegType**       addrRegs;
164} VerifierData;
165
166
167/* table with static merge logic for primitive types */
168extern const char gDvmMergeTab[kRegTypeMAX][kRegTypeMAX];
169
170
171/*
172 * Returns "true" if the flags indicate that this address holds the start
173 * of an instruction.
174 */
175INLINE bool dvmInsnIsOpcode(const InsnFlags* insnFlags, int addr) {
176    return (insnFlags[addr] & kInsnFlagWidthMask) != 0;
177}
178
179/*
180 * Extract the unsigned 16-bit instruction width from "flags".
181 */
182INLINE int dvmInsnGetWidth(const InsnFlags* insnFlags, int addr) {
183    return insnFlags[addr] & kInsnFlagWidthMask;
184}
185
186/*
187 * Changed?
188 */
189INLINE bool dvmInsnIsChanged(const InsnFlags* insnFlags, int addr) {
190    return (insnFlags[addr] & kInsnFlagChanged) != 0;
191}
192INLINE void dvmInsnSetChanged(InsnFlags* insnFlags, int addr, bool changed)
193{
194    if (changed)
195        insnFlags[addr] |= kInsnFlagChanged;
196    else
197        insnFlags[addr] &= ~kInsnFlagChanged;
198}
199
200/*
201 * Visited?
202 */
203INLINE bool dvmInsnIsVisited(const InsnFlags* insnFlags, int addr) {
204    return (insnFlags[addr] & kInsnFlagVisited) != 0;
205}
206INLINE void dvmInsnSetVisited(InsnFlags* insnFlags, int addr, bool changed)
207{
208    if (changed)
209        insnFlags[addr] |= kInsnFlagVisited;
210    else
211        insnFlags[addr] &= ~kInsnFlagVisited;
212}
213
214/*
215 * Visited or changed?
216 */
217INLINE bool dvmInsnIsVisitedOrChanged(const InsnFlags* insnFlags, int addr) {
218    return (insnFlags[addr] & (kInsnFlagVisited|kInsnFlagChanged)) != 0;
219}
220
221/*
222 * In a "try" block?
223 */
224INLINE bool dvmInsnIsInTry(const InsnFlags* insnFlags, int addr) {
225    return (insnFlags[addr] & kInsnFlagInTry) != 0;
226}
227INLINE void dvmInsnSetInTry(InsnFlags* insnFlags, int addr, bool inTry)
228{
229    assert(inTry);
230    //if (inTry)
231        insnFlags[addr] |= kInsnFlagInTry;
232    //else
233    //    insnFlags[addr] &= ~kInsnFlagInTry;
234}
235
236/*
237 * Instruction is a branch target or exception handler?
238 */
239INLINE bool dvmInsnIsBranchTarget(const InsnFlags* insnFlags, int addr) {
240    return (insnFlags[addr] & kInsnFlagBranchTarget) != 0;
241}
242INLINE void dvmInsnSetBranchTarget(InsnFlags* insnFlags, int addr,
243    bool isBranch)
244{
245    assert(isBranch);
246    //if (isBranch)
247        insnFlags[addr] |= kInsnFlagBranchTarget;
248    //else
249    //    insnFlags[addr] &= ~kInsnFlagBranchTarget;
250}
251
252/*
253 * Instruction is a GC point?
254 */
255INLINE bool dvmInsnIsGcPoint(const InsnFlags* insnFlags, int addr) {
256    return (insnFlags[addr] & kInsnFlagGcPoint) != 0;
257}
258INLINE void dvmInsnSetGcPoint(InsnFlags* insnFlags, int addr,
259    bool isGcPoint)
260{
261    assert(isGcPoint);
262    //if (isGcPoint)
263        insnFlags[addr] |= kInsnFlagGcPoint;
264    //else
265    //    insnFlags[addr] &= ~kInsnFlagGcPoint;
266}
267
268
269/*
270 * Create a new UninitInstanceMap.
271 */
272UninitInstanceMap* dvmCreateUninitInstanceMap(const Method* meth,
273    const InsnFlags* insnFlags, int newInstanceCount);
274
275/*
276 * Release the storage associated with an UninitInstanceMap.
277 */
278void dvmFreeUninitInstanceMap(UninitInstanceMap* uninitMap);
279
280/*
281 * Associate a class with an address.  Returns the map slot index, or -1
282 * if the address isn't listed in the map (shouldn't happen) or if a
283 * different class is already associated with the address (shouldn't
284 * happen either).
285 */
286//int dvmSetUninitInstance(UninitInstanceMap* uninitMap, int addr,
287//    ClassObject* clazz);
288
289/*
290 * Return the class associated with an uninitialized reference.  Pass in
291 * the map index.
292 */
293//ClassObject* dvmGetUninitInstance(const UninitInstanceMap* uninitMap, int idx);
294
295/*
296 * Clear the class associated with an uninitialized reference.  Pass in
297 * the map index.
298 */
299//void dvmClearUninitInstance(UninitInstanceMap* uninitMap, int idx);
300
301
302/*
303 * Verify bytecode in "meth".  "insnFlags" should be populated with
304 * instruction widths and "in try" flags.
305 */
306bool dvmVerifyCodeFlow(VerifierData* vdata);
307
308#endif /*_DALVIK_CODEVERIFY*/
309