xref: /freebsd/contrib/llvm-project/compiler-rt/lib/gwp_asan/common.h (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
1 //===-- common.h ------------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // This file contains code that is common between the crash handler and the
10 // GuardedPoolAllocator.
11 
12 #ifndef GWP_ASAN_COMMON_H_
13 #define GWP_ASAN_COMMON_H_
14 
15 #include "gwp_asan/definitions.h"
16 #include "gwp_asan/options.h"
17 
18 #include <stddef.h>
19 #include <stdint.h>
20 
21 namespace gwp_asan {
22 enum class Error {
23   UNKNOWN,
24   USE_AFTER_FREE,
25   DOUBLE_FREE,
26   INVALID_FREE,
27   BUFFER_OVERFLOW,
28   BUFFER_UNDERFLOW
29 };
30 
31 const char *ErrorToString(const Error &E);
32 
33 static constexpr uint64_t kInvalidThreadID = UINT64_MAX;
34 // Get the current thread ID, or kInvalidThreadID if failure. Note: This
35 // implementation is platform-specific.
36 uint64_t getThreadID();
37 
38 // This struct contains all the metadata recorded about a single allocation made
39 // by GWP-ASan. If `AllocationMetadata.Addr` is zero, the metadata is non-valid.
40 struct AllocationMetadata {
41   // The number of bytes used to store a compressed stack frame. On 64-bit
42   // platforms, assuming a compression ratio of 50%, this should allow us to
43   // store ~64 frames per trace.
44   static constexpr size_t kStackFrameStorageBytes = 256;
45 
46   // Maximum number of stack frames to collect on allocation/deallocation. The
47   // actual number of collected frames may be less than this as the stack
48   // frames are compressed into a fixed memory range.
49   static constexpr size_t kMaxTraceLengthToCollect = 128;
50 
51   // Records the given allocation metadata into this struct.
52   void RecordAllocation(uintptr_t Addr, size_t RequestedSize);
53   // Record that this allocation is now deallocated.
54   void RecordDeallocation();
55 
56   struct CallSiteInfo {
57     // Record the current backtrace to this callsite.
58     void RecordBacktrace(options::Backtrace_t Backtrace);
59 
60     // The compressed backtrace to the allocation/deallocation.
61     uint8_t CompressedTrace[kStackFrameStorageBytes];
62     // The thread ID for this trace, or kInvalidThreadID if not available.
63     uint64_t ThreadID = kInvalidThreadID;
64     // The size of the compressed trace (in bytes). Zero indicates that no
65     // trace was collected.
66     size_t TraceSize = 0;
67   };
68 
69   // The address of this allocation. If zero, the rest of this struct isn't
70   // valid, as the allocation has never occurred.
71   uintptr_t Addr = 0;
72   // Represents the actual size of the allocation.
73   size_t RequestedSize = 0;
74 
75   CallSiteInfo AllocationTrace;
76   CallSiteInfo DeallocationTrace;
77 
78   // Whether this allocation has been deallocated yet.
79   bool IsDeallocated = false;
80 };
81 
82 // This holds the state that's shared between the GWP-ASan allocator and the
83 // crash handler. This, in conjunction with the Metadata array, forms the entire
84 // set of information required for understanding a GWP-ASan crash.
85 struct AllocatorState {
86   constexpr AllocatorState() {}
87 
88   // Returns whether the provided pointer is a current sampled allocation that
89   // is owned by this pool.
90   GWP_ASAN_ALWAYS_INLINE bool pointerIsMine(const void *Ptr) const {
91     uintptr_t P = reinterpret_cast<uintptr_t>(Ptr);
92     return P < GuardedPagePoolEnd && GuardedPagePool <= P;
93   }
94 
95   // Returns the address of the N-th guarded slot.
96   uintptr_t slotToAddr(size_t N) const;
97 
98   // Returns the largest allocation that is supported by this pool.
99   size_t maximumAllocationSize() const;
100 
101   // Gets the nearest slot to the provided address.
102   size_t getNearestSlot(uintptr_t Ptr) const;
103 
104   // Returns whether the provided pointer is a guard page or not. The pointer
105   // must be within memory owned by this pool, else the result is undefined.
106   bool isGuardPage(uintptr_t Ptr) const;
107 
108   // The number of guarded slots that this pool holds.
109   size_t MaxSimultaneousAllocations = 0;
110 
111   // Pointer to the pool of guarded slots. Note that this points to the start of
112   // the pool (which is a guard page), not a pointer to the first guarded page.
113   uintptr_t GuardedPagePool = 0;
114   uintptr_t GuardedPagePoolEnd = 0;
115 
116   // Cached page size for this system in bytes.
117   size_t PageSize = 0;
118 
119   // The type and address of an internally-detected failure. For INVALID_FREE
120   // and DOUBLE_FREE, these errors are detected in GWP-ASan, which will set
121   // these values and terminate the process.
122   Error FailureType = Error::UNKNOWN;
123   uintptr_t FailureAddress = 0;
124 };
125 
126 } // namespace gwp_asan
127 #endif // GWP_ASAN_COMMON_H_
128