1 /*
2 * Copyright (C) 2016 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 #ifndef LIBMEMUNREACHABLE_HEAP_WALKER_H_
18 #define LIBMEMUNREACHABLE_HEAP_WALKER_H_
19
20 #include <signal.h>
21
22 #include "android-base/macros.h"
23
24 #include "Allocator.h"
25 #include "ScopedSignalHandler.h"
26 #include "Tarjan.h"
27
28 // A range [begin, end)
29 struct Range {
30 uintptr_t begin;
31 uintptr_t end;
32
sizeRange33 size_t size() const { return end - begin; };
34 bool operator==(const Range& other) const {
35 return this->begin == other.begin && this->end == other.end;
36 }
37 bool operator!=(const Range& other) const {
38 return !(*this == other);
39 }
40 };
41
42 // Comparator for Ranges that returns equivalence for overlapping ranges
43 struct compare_range {
operatorcompare_range44 bool operator()(const Range& a, const Range& b) const {
45 return a.end <= b.begin;
46 }
47 };
48
49 class HeapWalker {
50 public:
HeapWalker(Allocator<HeapWalker> allocator)51 HeapWalker(Allocator<HeapWalker> allocator) : allocator_(allocator),
52 allocations_(allocator), allocation_bytes_(0),
53 roots_(allocator), root_vals_(allocator),
54 segv_handler_(allocator), walking_ptr_(0) {
55 valid_allocations_range_.end = 0;
56 valid_allocations_range_.begin = ~valid_allocations_range_.end;
57
58 segv_handler_.install(SIGSEGV,
59 [=](ScopedSignalHandler& handler, int signal, siginfo_t* siginfo, void* uctx) {
60 this->HandleSegFault(handler, signal, siginfo, uctx);
61 });
62 }
63
~HeapWalker()64 ~HeapWalker() {}
65 bool Allocation(uintptr_t begin, uintptr_t end);
66 void Root(uintptr_t begin, uintptr_t end);
67 void Root(const allocator::vector<uintptr_t>& vals);
68
69 bool DetectLeaks();
70
71 bool Leaked(allocator::vector<Range>&, size_t limit, size_t* num_leaks,
72 size_t* leak_bytes);
73 size_t Allocations();
74 size_t AllocationBytes();
75
76 template<class F>
77 void ForEachPtrInRange(const Range& range, F&& f);
78
79 template<class F>
80 void ForEachAllocation(F&& f);
81
82 struct AllocationInfo {
83 bool referenced_from_root;
84 };
85
86 private:
87
88 void RecurseRoot(const Range& root);
89 bool WordContainsAllocationPtr(uintptr_t ptr, Range* range, AllocationInfo** info);
90 void HandleSegFault(ScopedSignalHandler&, int, siginfo_t*, void*);
91
92 DISALLOW_COPY_AND_ASSIGN(HeapWalker);
93 Allocator<HeapWalker> allocator_;
94 using AllocationMap = allocator::map<Range, AllocationInfo, compare_range>;
95 AllocationMap allocations_;
96 size_t allocation_bytes_;
97 Range valid_allocations_range_;
98
99 allocator::vector<Range> roots_;
100 allocator::vector<uintptr_t> root_vals_;
101
102 ScopedSignalHandler segv_handler_;
103 uintptr_t walking_ptr_;
104 };
105
106 template<class F>
ForEachPtrInRange(const Range & range,F && f)107 inline void HeapWalker::ForEachPtrInRange(const Range& range, F&& f) {
108 uintptr_t begin = (range.begin + (sizeof(uintptr_t) - 1)) & ~(sizeof(uintptr_t) - 1);
109 // TODO(ccross): we might need to consider a pointer to the end of a buffer
110 // to be inside the buffer, which means the common case of a pointer to the
111 // beginning of a buffer may keep two ranges live.
112 for (uintptr_t i = begin; i < range.end; i += sizeof(uintptr_t)) {
113 Range ref_range;
114 AllocationInfo* ref_info;
115 if (WordContainsAllocationPtr(i, &ref_range, &ref_info)) {
116 f(ref_range, ref_info);
117 }
118 }
119 }
120
121 template<class F>
ForEachAllocation(F && f)122 inline void HeapWalker::ForEachAllocation(F&& f) {
123 for (auto& it : allocations_) {
124 const Range& range = it.first;
125 HeapWalker::AllocationInfo& allocation = it.second;
126 f(range, allocation);
127 }
128 }
129
130 #endif
131