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diff --git a/contrib/llvm-project/compiler-rt/lib/gwp_asan/common.h b/contrib/llvm-project/compiler-rt/lib/gwp_asan/common.h
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+//===-- common.h ------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// This file contains code that is common between the crash handler and the
+// GuardedPoolAllocator.
+
+#ifndef GWP_ASAN_COMMON_H_
+#define GWP_ASAN_COMMON_H_
+
+#include "gwp_asan/definitions.h"
+#include "gwp_asan/options.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+namespace gwp_asan {
+
+// Magic header that resides in the AllocatorState so that GWP-ASan bugreports
+// can be understood by tools at different versions. Out-of-process crash
+// handlers, like crashpad on Fuchsia, take the raw contents of the
+// AllocationMetatada array and the AllocatorState, and shove them into the
+// minidump. Online unpacking of these structs needs to know from which version
+// of GWP-ASan it's extracting the information, as the structures are not
+// stable.
+struct AllocatorVersionMagic {
+  // The values are copied into the structure at runtime, during
+  // `GuardedPoolAllocator::init()` so that GWP-ASan remains completely in the
+  // `.bss` segment.
+  static constexpr uint8_t kAllocatorVersionMagic[4] = {'A', 'S', 'A', 'N'};
+  uint8_t Magic[4] = {};
+  // Update the version number when the AllocatorState or AllocationMetadata
+  // change.
+  static constexpr uint16_t kAllocatorVersion = 2;
+  uint16_t Version = 0;
+  uint16_t Reserved = 0;
+};
+
+enum class Error : uint8_t {
+  UNKNOWN,
+  USE_AFTER_FREE,
+  DOUBLE_FREE,
+  INVALID_FREE,
+  BUFFER_OVERFLOW,
+  BUFFER_UNDERFLOW
+};
+
+const char *ErrorToString(const Error &E);
+
+static constexpr uint64_t kInvalidThreadID = UINT64_MAX;
+// Get the current thread ID, or kInvalidThreadID if failure. Note: This
+// implementation is platform-specific.
+uint64_t getThreadID();
+
+// This struct contains all the metadata recorded about a single allocation made
+// by GWP-ASan. If `AllocationMetadata.Addr` is zero, the metadata is non-valid.
+struct AllocationMetadata {
+  // The number of bytes used to store a compressed stack frame. On 64-bit
+  // platforms, assuming a compression ratio of 50%, this should allow us to
+  // store ~64 frames per trace.
+  static constexpr size_t kStackFrameStorageBytes = 256;
+
+  // Maximum number of stack frames to collect on allocation/deallocation. The
+  // actual number of collected frames may be less than this as the stack
+  // frames are compressed into a fixed memory range.
+  static constexpr size_t kMaxTraceLengthToCollect = 128;
+
+  // Records the given allocation metadata into this struct.
+  void RecordAllocation(uintptr_t Addr, size_t RequestedSize);
+  // Record that this allocation is now deallocated.
+  void RecordDeallocation();
+
+  struct CallSiteInfo {
+    // Record the current backtrace to this callsite.
+    void RecordBacktrace(options::Backtrace_t Backtrace);
+
+    // The compressed backtrace to the allocation/deallocation.
+    uint8_t CompressedTrace[kStackFrameStorageBytes];
+    // The thread ID for this trace, or kInvalidThreadID if not available.
+    uint64_t ThreadID = kInvalidThreadID;
+    // The size of the compressed trace (in bytes). Zero indicates that no
+    // trace was collected.
+    size_t TraceSize = 0;
+  };
+
+  // The address of this allocation. If zero, the rest of this struct isn't
+  // valid, as the allocation has never occurred.
+  uintptr_t Addr = 0;
+  // Represents the actual size of the allocation.
+  size_t RequestedSize = 0;
+
+  CallSiteInfo AllocationTrace;
+  CallSiteInfo DeallocationTrace;
+
+  // Whether this allocation has been deallocated yet.
+  bool IsDeallocated = false;
+
+  // In recoverable mode, whether this allocation has had a crash associated
+  // with it. This has certain side effects, like meaning this allocation will
+  // permanently occupy a slot, and won't ever have another crash reported from
+  // it.
+  bool HasCrashed = false;
+};
+
+// This holds the state that's shared between the GWP-ASan allocator and the
+// crash handler. This, in conjunction with the Metadata array, forms the entire
+// set of information required for understanding a GWP-ASan crash.
+struct AllocatorState {
+  constexpr AllocatorState() {}
+  AllocatorVersionMagic VersionMagic{};
+
+  // Returns whether the provided pointer is a current sampled allocation that
+  // is owned by this pool.
+  GWP_ASAN_ALWAYS_INLINE bool pointerIsMine(const void *Ptr) const {
+    uintptr_t P = reinterpret_cast<uintptr_t>(Ptr);
+    return P < GuardedPagePoolEnd && GuardedPagePool <= P;
+  }
+
+  // Returns the address of the N-th guarded slot.
+  uintptr_t slotToAddr(size_t N) const;
+
+  // Returns the largest allocation that is supported by this pool.
+  size_t maximumAllocationSize() const;
+
+  // Gets the nearest slot to the provided address.
+  size_t getNearestSlot(uintptr_t Ptr) const;
+
+  // Returns whether the provided pointer is a guard page or not. The pointer
+  // must be within memory owned by this pool, else the result is undefined.
+  bool isGuardPage(uintptr_t Ptr) const;
+
+  // Returns the address that's used by __gwp_asan_get_internal_crash_address()
+  // and GPA::raiseInternallyDetectedError() to communicate that the SEGV in
+  // question comes from an internally-detected error.
+  uintptr_t internallyDetectedErrorFaultAddress() const;
+
+  // The number of guarded slots that this pool holds.
+  size_t MaxSimultaneousAllocations = 0;
+
+  // Pointer to the pool of guarded slots. Note that this points to the start of
+  // the pool (which is a guard page), not a pointer to the first guarded page.
+  uintptr_t GuardedPagePool = 0;
+  uintptr_t GuardedPagePoolEnd = 0;
+
+  // Cached page size for this system in bytes.
+  size_t PageSize = 0;
+
+  // The type and address of an internally-detected failure. For INVALID_FREE
+  // and DOUBLE_FREE, these errors are detected in GWP-ASan, which will set
+  // these values and terminate the process.
+  Error FailureType = Error::UNKNOWN;
+  uintptr_t FailureAddress = 0;
+};
+
+// Below are various compile-time checks that the layout of the internal
+// GWP-ASan structures are undisturbed. If they are disturbed, the version magic
+// number needs to be increased by one, and the asserts need to be updated.
+// Out-of-process crash handlers, like breakpad/crashpad, may copy the internal
+// GWP-ASan structures into a minidump for offline reconstruction of the crash.
+// In order to accomplish this, the offline reconstructor needs to know the
+// version of GWP-ASan internal structures that it's unpacking (along with the
+// architecture-specific layout info, which is left as an exercise to the crash
+// handler).
+static_assert(offsetof(AllocatorState, VersionMagic) == 0, "");
+static_assert(sizeof(AllocatorVersionMagic) == 8, "");
+#if defined(__x86_64__)
+static_assert(sizeof(AllocatorState) == 56, "");
+static_assert(offsetof(AllocatorState, FailureAddress) == 48, "");
+static_assert(sizeof(AllocationMetadata) == 568, "");
+static_assert(offsetof(AllocationMetadata, IsDeallocated) == 560, "");
+#elif defined(__aarch64__)
+static_assert(sizeof(AllocatorState) == 56, "");
+static_assert(offsetof(AllocatorState, FailureAddress) == 48, "");
+static_assert(sizeof(AllocationMetadata) == 568, "");
+static_assert(offsetof(AllocationMetadata, IsDeallocated) == 560, "");
+#elif defined(__i386__)
+static_assert(sizeof(AllocatorState) == 32, "");
+static_assert(offsetof(AllocatorState, FailureAddress) == 28, "");
+static_assert(sizeof(AllocationMetadata) == 548, "");
+static_assert(offsetof(AllocationMetadata, IsDeallocated) == 544, "");
+#elif defined(__arm__)
+static_assert(sizeof(AllocatorState) == 32, "");
+static_assert(offsetof(AllocatorState, FailureAddress) == 28, "");
+static_assert(sizeof(AllocationMetadata) == 560, "");
+static_assert(offsetof(AllocationMetadata, IsDeallocated) == 552, "");
+#endif // defined($ARCHITECTURE)
+
+} // namespace gwp_asan
+#endif // GWP_ASAN_COMMON_H_