indirect_reference_table.cc revision 726079d3e2e50854cd6ca4c393f4529a796dba58 
1/*
2 * Copyright (C) 2009 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#include "indirect_reference_table.h"
18#include "jni_internal.h"
19#include "reference_table.h"
20#include "runtime.h"
21#include "thread.h"
22#include "utils.h"
23
24#include <cstdlib>
25
26namespace art {
27
28static void AbortMaybe() {
29  // If -Xcheck:jni is on, it'll give a more detailed error before aborting.
30  if (!Runtime::Current()->GetJavaVM()->check_jni) {
31    // Otherwise, we want to abort rather than hand back a bad reference.
32    LOG(FATAL) << "JNI ERROR (app bug): see above.";
33  }
34}
35
36IndirectReferenceTable::IndirectReferenceTable(size_t initialCount,
37    size_t maxCount, IndirectRefKind desiredKind)
38{
39  CHECK_GT(initialCount, 0U);
40  CHECK_LE(initialCount, maxCount);
41  CHECK_NE(desiredKind, kSirtOrInvalid);
42
43  table_ = reinterpret_cast<const Object**>(malloc(initialCount * sizeof(const Object*)));
44  CHECK(table_ != NULL);
45#ifndef NDEBUG
46  memset(table_, 0xd1, initialCount * sizeof(const Object*));
47#endif
48
49  slot_data_ = reinterpret_cast<IndirectRefSlot*>(calloc(initialCount, sizeof(IndirectRefSlot)));
50  CHECK(slot_data_ != NULL);
51
52  segment_state_.all = IRT_FIRST_SEGMENT;
53  alloc_entries_ = initialCount;
54  max_entries_ = maxCount;
55  kind_ = desiredKind;
56}
57
58IndirectReferenceTable::~IndirectReferenceTable() {
59  free(table_);
60  free(slot_data_);
61  table_ = NULL;
62  slot_data_ = NULL;
63  alloc_entries_ = max_entries_ = -1;
64}
65
66/*
67 * Make sure that the entry at "idx" is correctly paired with "iref".
68 */
69bool IndirectReferenceTable::CheckEntry(const char* what, IndirectRef iref, int idx) const {
70  const Object* obj = table_[idx];
71  IndirectRef checkRef = ToIndirectRef(obj, idx);
72  if (checkRef != iref) {
73    LOG(ERROR) << "JNI ERROR (app bug): attempt to " << what
74               << " stale " << kind_ << " " << iref
75               << " (should be " << checkRef << ")";
76    AbortMaybe();
77    return false;
78  }
79  return true;
80}
81
82IndirectRef IndirectReferenceTable::Add(uint32_t cookie, const Object* obj) {
83  IRTSegmentState prevState;
84  prevState.all = cookie;
85  size_t topIndex = segment_state_.parts.topIndex;
86
87  DCHECK(obj != NULL);
88  // TODO: stronger sanity check on the object (such as in heap)
89  DCHECK(IsAligned(reinterpret_cast<intptr_t>(obj), 8)) << reinterpret_cast<const void*>(obj);
90  DCHECK(table_ != NULL);
91  DCHECK_LE(alloc_entries_, max_entries_);
92  DCHECK_GE(segment_state_.parts.numHoles, prevState.parts.numHoles);
93
94  if (topIndex == alloc_entries_) {
95    /* reached end of allocated space; did we hit buffer max? */
96    if (topIndex == max_entries_) {
97      LOG(ERROR) << "JNI ERROR (app bug): " << kind_ << " table overflow "
98                 << "(max=" << max_entries_ << ")";
99      Dump();
100      LOG(FATAL); // TODO: operator<< for IndirectReferenceTable
101    }
102
103    size_t newSize = alloc_entries_ * 2;
104    if (newSize > max_entries_) {
105      newSize = max_entries_;
106    }
107    DCHECK_GT(newSize, alloc_entries_);
108
109    table_ = (const Object**) realloc(table_, newSize * sizeof(const Object*));
110    slot_data_ = (IndirectRefSlot*) realloc(slot_data_, newSize * sizeof(IndirectRefSlot));
111    if (table_ == NULL || slot_data_ == NULL) {
112      LOG(ERROR) << "JNI ERROR (app bug): unable to expand "
113                 << kind_ << " table (from "
114                 << alloc_entries_ << " to " << newSize
115                 << ", max=" << max_entries_ << ")";
116      Dump();
117      LOG(FATAL); // TODO: operator<< for IndirectReferenceTable
118    }
119
120    // Clear the newly-allocated slot_data_ elements.
121    memset(slot_data_ + alloc_entries_, 0, (newSize - alloc_entries_) * sizeof(IndirectRefSlot));
122
123    alloc_entries_ = newSize;
124  }
125
126  /*
127   * We know there's enough room in the table.  Now we just need to find
128   * the right spot.  If there's a hole, find it and fill it; otherwise,
129   * add to the end of the list.
130   */
131  IndirectRef result;
132  int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
133  if (numHoles > 0) {
134    DCHECK_GT(topIndex, 1U);
135    /* find the first hole; likely to be near the end of the list */
136    const Object** pScan = &table_[topIndex - 1];
137    DCHECK(*pScan != NULL);
138    while (*--pScan != NULL) {
139      DCHECK_GE(pScan, table_ + prevState.parts.topIndex);
140    }
141    UpdateSlotAdd(obj, pScan - table_);
142    result = ToIndirectRef(obj, pScan - table_);
143    *pScan = obj;
144    segment_state_.parts.numHoles--;
145  } else {
146    /* add to the end */
147    UpdateSlotAdd(obj, topIndex);
148    result = ToIndirectRef(obj, topIndex);
149    table_[topIndex++] = obj;
150    segment_state_.parts.topIndex = topIndex;
151  }
152  if (false) {
153    LOG(INFO) << "+++ added at " << ExtractIndex(result) << " top=" << segment_state_.parts.topIndex
154              << " holes=" << segment_state_.parts.numHoles;
155  }
156
157  DCHECK(result != NULL);
158  return result;
159}
160
161void IndirectReferenceTable::AssertEmpty() {
162  if (begin() != end()) {
163    Dump();
164    LOG(FATAL) << "Internal Error: non-empty local reference table";
165  }
166}
167
168/*
169 * Verify that the indirect table lookup is valid.
170 *
171 * Returns "false" if something looks bad.
172 */
173bool IndirectReferenceTable::GetChecked(IndirectRef iref) const {
174  if (iref == NULL) {
175    LOG(WARNING) << "Attempt to look up NULL " << kind_;
176    return false;
177  }
178  if (GetIndirectRefKind(iref) == kSirtOrInvalid) {
179    LOG(ERROR) << "JNI ERROR (app bug): invalid " << kind_ << " " << iref;
180    AbortMaybe();
181    return false;
182  }
183
184  int topIndex = segment_state_.parts.topIndex;
185  int idx = ExtractIndex(iref);
186  if (idx >= topIndex) {
187    /* bad -- stale reference? */
188    LOG(ERROR) << "JNI ERROR (app bug): accessed stale " << kind_ << " "
189               << iref << " (index " << idx << " in a table of size " << topIndex << ")";
190    AbortMaybe();
191    return false;
192  }
193
194  if (table_[idx] == NULL) {
195    LOG(ERROR) << "JNI ERROR (app bug): accessed deleted " << kind_ << " " << iref;
196    AbortMaybe();
197    return false;
198  }
199
200  if (!CheckEntry("use", iref, idx)) {
201    return false;
202  }
203
204  return true;
205}
206
207static int LinearScan(IndirectRef iref, int bottomIndex, int topIndex, const Object** table) {
208  for (int i = bottomIndex; i < topIndex; ++i) {
209    if (table[i] == reinterpret_cast<const Object*>(iref)) {
210      return i;
211    }
212  }
213  return -1;
214}
215
216bool IndirectReferenceTable::Contains(IndirectRef iref) const {
217  return LinearScan(iref, 0, segment_state_.parts.topIndex, table_) != -1;
218}
219
220/*
221 * Remove "obj" from "pRef".  We extract the table offset bits from "iref"
222 * and zap the corresponding entry, leaving a hole if it's not at the top.
223 *
224 * If the entry is not between the current top index and the bottom index
225 * specified by the cookie, we don't remove anything.  This is the behavior
226 * required by JNI's DeleteLocalRef function.
227 *
228 * Note this is NOT called when a local frame is popped.  This is only used
229 * for explicit single removals.
230 *
231 * Returns "false" if nothing was removed.
232 */
233bool IndirectReferenceTable::Remove(uint32_t cookie, IndirectRef iref) {
234  IRTSegmentState prevState;
235  prevState.all = cookie;
236  int topIndex = segment_state_.parts.topIndex;
237  int bottomIndex = prevState.parts.topIndex;
238
239  DCHECK(table_ != NULL);
240  DCHECK_LE(alloc_entries_, max_entries_);
241  DCHECK_GE(segment_state_.parts.numHoles, prevState.parts.numHoles);
242
243  int idx = ExtractIndex(iref);
244
245  JavaVMExt* vm = Runtime::Current()->GetJavaVM();
246  if (GetIndirectRefKind(iref) == kSirtOrInvalid &&
247      Thread::Current()->SirtContains(reinterpret_cast<jobject>(iref))) {
248    LOG(WARNING) << "Attempt to remove local SIRT entry from IRT, ignoring";
249    return true;
250  }
251  if (GetIndirectRefKind(iref) == kSirtOrInvalid || vm->work_around_app_jni_bugs) {
252    idx = LinearScan(iref, bottomIndex, topIndex, table_);
253    if (idx == -1) {
254      LOG(WARNING) << "trying to work around app JNI bugs, but didn't find " << iref << " in table!";
255      return false;
256    }
257  }
258
259  if (idx < bottomIndex) {
260    // Wrong segment.
261    LOG(WARNING) << "Attempt to remove index outside index area (" << idx
262                 << " vs " << bottomIndex << "-" << topIndex << ")";
263    return false;
264  }
265  if (idx >= topIndex) {
266    // Bad --- stale reference?
267    LOG(WARNING) << "Attempt to remove invalid index " << idx
268                 << " (bottom=" << bottomIndex << " top=" << topIndex << ")";
269    return false;
270  }
271
272  if (idx == topIndex-1) {
273    // Top-most entry.  Scan up and consume holes.
274
275    if (!vm->work_around_app_jni_bugs && !CheckEntry("remove", iref, idx)) {
276      return false;
277    }
278
279    table_[idx] = NULL;
280    int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
281    if (numHoles != 0) {
282      while (--topIndex > bottomIndex && numHoles != 0) {
283        if (false) {
284          LOG(INFO) << "+++ checking for hole at " << topIndex-1
285                    << " (cookie=" << cookie << ") val=" << table_[topIndex - 1];
286        }
287        if (table_[topIndex-1] != NULL) {
288          break;
289        }
290        if (false) {
291          LOG(INFO) << "+++ ate hole at " << (topIndex - 1);
292        }
293        numHoles--;
294      }
295      segment_state_.parts.numHoles = numHoles + prevState.parts.numHoles;
296      segment_state_.parts.topIndex = topIndex;
297    } else {
298      segment_state_.parts.topIndex = topIndex-1;
299      if (false) {
300        LOG(INFO) << "+++ ate last entry " << topIndex - 1;
301      }
302    }
303  } else {
304    /*
305     * Not the top-most entry.  This creates a hole.  We NULL out the
306     * entry to prevent somebody from deleting it twice and screwing up
307     * the hole count.
308     */
309    if (table_[idx] == NULL) {
310      LOG(INFO) << "--- WEIRD: removing null entry " << idx;
311      return false;
312    }
313    if (!vm->work_around_app_jni_bugs && !CheckEntry("remove", iref, idx)) {
314      return false;
315    }
316
317    table_[idx] = NULL;
318    segment_state_.parts.numHoles++;
319    if (false) {
320      LOG(INFO) << "+++ left hole at " << idx << ", holes=" << segment_state_.parts.numHoles;
321    }
322  }
323
324  return true;
325}
326
327void IndirectReferenceTable::VisitRoots(Heap::RootVisitor* visitor, void* arg) {
328  typedef IndirectReferenceTable::iterator It; // TODO: C++0x auto
329  for (It it = begin(), end = this->end(); it != end; ++it) {
330    visitor(**it, arg);
331  }
332}
333
334std::ostream& operator<<(std::ostream& os, IndirectRefKind rhs) {
335  switch (rhs) {
336  case kSirtOrInvalid:
337    os << "stack indirect reference table or invalid reference";
338    break;
339  case kLocal:
340    os << "local reference";
341    break;
342  case kGlobal:
343    os << "global reference";
344    break;
345  case kWeakGlobal:
346    os << "weak global reference";
347    break;
348  default:
349    os << "IndirectRefKind[" << static_cast<int>(rhs) << "]";
350    break;
351  }
352  return os;
353}
354
355void IndirectReferenceTable::Dump() const {
356  LOG(WARNING) << kind_ << " table dump:";
357  std::vector<const Object*> entries(table_, table_ + Capacity());
358  ReferenceTable::Dump(entries);
359}
360
361}  // namespace art
362