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1 //===-- common.h ------------------------------------------------*- C++ -*-===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8
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9 // This file contains code that is common between the crash handler and the
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10 // GuardedPoolAllocator.
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11
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12 #ifndef GWP_ASAN_COMMON_H_
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13 #define GWP_ASAN_COMMON_H_
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14
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15 #include "gwp_asan/definitions.h"
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16 #include "gwp_asan/options.h"
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17
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18 #include <stddef.h>
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19 #include <stdint.h>
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20
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21 namespace gwp_asan {
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22 enum class Error {
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23 UNKNOWN,
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24 USE_AFTER_FREE,
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25 DOUBLE_FREE,
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26 INVALID_FREE,
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27 BUFFER_OVERFLOW,
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28 BUFFER_UNDERFLOW
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29 };
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30
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31 const char *ErrorToString(const Error &E);
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32
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33 static constexpr uint64_t kInvalidThreadID = UINT64_MAX;
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34 // Get the current thread ID, or kInvalidThreadID if failure. Note: This
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35 // implementation is platform-specific.
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36 uint64_t getThreadID();
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37
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38 // This struct contains all the metadata recorded about a single allocation made
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39 // by GWP-ASan. If `AllocationMetadata.Addr` is zero, the metadata is non-valid.
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40 struct AllocationMetadata {
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41 // The number of bytes used to store a compressed stack frame. On 64-bit
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42 // platforms, assuming a compression ratio of 50%, this should allow us to
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43 // store ~64 frames per trace.
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44 static constexpr size_t kStackFrameStorageBytes = 256;
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45
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46 // Maximum number of stack frames to collect on allocation/deallocation. The
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47 // actual number of collected frames may be less than this as the stack
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48 // frames are compressed into a fixed memory range.
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49 static constexpr size_t kMaxTraceLengthToCollect = 128;
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50
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51 // Records the given allocation metadata into this struct.
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207
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52 void RecordAllocation(uintptr_t Addr, size_t RequestedSize);
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150
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53 // Record that this allocation is now deallocated.
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54 void RecordDeallocation();
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55
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56 struct CallSiteInfo {
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57 // Record the current backtrace to this callsite.
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58 void RecordBacktrace(options::Backtrace_t Backtrace);
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59
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60 // The compressed backtrace to the allocation/deallocation.
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61 uint8_t CompressedTrace[kStackFrameStorageBytes];
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62 // The thread ID for this trace, or kInvalidThreadID if not available.
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63 uint64_t ThreadID = kInvalidThreadID;
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64 // The size of the compressed trace (in bytes). Zero indicates that no
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65 // trace was collected.
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66 size_t TraceSize = 0;
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67 };
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68
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69 // The address of this allocation. If zero, the rest of this struct isn't
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70 // valid, as the allocation has never occurred.
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71 uintptr_t Addr = 0;
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72 // Represents the actual size of the allocation.
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207
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73 size_t RequestedSize = 0;
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74
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75 CallSiteInfo AllocationTrace;
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76 CallSiteInfo DeallocationTrace;
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77
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78 // Whether this allocation has been deallocated yet.
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79 bool IsDeallocated = false;
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80 };
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81
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82 // This holds the state that's shared between the GWP-ASan allocator and the
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83 // crash handler. This, in conjunction with the Metadata array, forms the entire
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84 // set of information required for understanding a GWP-ASan crash.
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85 struct AllocatorState {
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207
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86 constexpr AllocatorState() {}
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87
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150
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88 // Returns whether the provided pointer is a current sampled allocation that
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89 // is owned by this pool.
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90 GWP_ASAN_ALWAYS_INLINE bool pointerIsMine(const void *Ptr) const {
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91 uintptr_t P = reinterpret_cast<uintptr_t>(Ptr);
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92 return P < GuardedPagePoolEnd && GuardedPagePool <= P;
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93 }
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94
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95 // Returns the address of the N-th guarded slot.
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96 uintptr_t slotToAddr(size_t N) const;
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97
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98 // Returns the largest allocation that is supported by this pool.
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99 size_t maximumAllocationSize() const;
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100
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101 // Gets the nearest slot to the provided address.
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102 size_t getNearestSlot(uintptr_t Ptr) const;
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103
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104 // Returns whether the provided pointer is a guard page or not. The pointer
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105 // must be within memory owned by this pool, else the result is undefined.
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106 bool isGuardPage(uintptr_t Ptr) const;
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107
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108 // The number of guarded slots that this pool holds.
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109 size_t MaxSimultaneousAllocations = 0;
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110
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111 // Pointer to the pool of guarded slots. Note that this points to the start of
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112 // the pool (which is a guard page), not a pointer to the first guarded page.
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113 uintptr_t GuardedPagePool = 0;
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114 uintptr_t GuardedPagePoolEnd = 0;
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115
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116 // Cached page size for this system in bytes.
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117 size_t PageSize = 0;
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118
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119 // The type and address of an internally-detected failure. For INVALID_FREE
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120 // and DOUBLE_FREE, these errors are detected in GWP-ASan, which will set
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121 // these values and terminate the process.
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122 Error FailureType = Error::UNKNOWN;
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123 uintptr_t FailureAddress = 0;
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124 };
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125
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126 } // namespace gwp_asan
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127 #endif // GWP_ASAN_COMMON_H_
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