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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 {
enum class Error {
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 Size);
// 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 Size = 0;
CallSiteInfo AllocationTrace;
CallSiteInfo DeallocationTrace;
// Whether this allocation has been deallocated yet.
bool IsDeallocated = 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 {
// 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;
// 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;
};
} // namespace gwp_asan
#endif // GWP_ASAN_COMMON_H_
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