99 lines
3.8 KiB
C++
99 lines
3.8 KiB
C++
// Copyright Epic Games, Inc. All Rights Reserved.
|
|
|
|
#pragma once
|
|
|
|
#if (defined(__AUTORTFM) && __AUTORTFM)
|
|
|
|
#include "AutoRTFMDefines.h"
|
|
#include "AutoRTFMConstants.h"
|
|
#include "FunctionMap.h"
|
|
#include "Utils.h"
|
|
|
|
namespace AutoRTFM
|
|
{
|
|
|
|
AUTORTFM_DISABLE UE_AUTORTFM_FORCEINLINE
|
|
void* FunctionMapLookupUsingMagicPrefix(void* OpenFn)
|
|
{
|
|
constexpr uint64_t UbsanMagic = 0xc105'cafe;
|
|
|
|
// We use prefix data in our custom LLVM pass to stuff some data just
|
|
// before the address of all open function pointers (that we have
|
|
// definitions for!). We verify the special Magic Prefix constant in the
|
|
// top 16-bits of the function pointer address as a magic constant check
|
|
// to give us a much higher confidence that there is actually a closed
|
|
// variant pointer residing 8-bytes before our function address.
|
|
uint64_t PrefixData;
|
|
char* CharOpenFn = reinterpret_cast<char*>(OpenFn);
|
|
memcpy(&PrefixData, CharOpenFn - sizeof(uint64_t), sizeof(uint64_t));
|
|
#if PLATFORM_LINUX
|
|
constexpr uint64_t Mask = 0xffff'0000'0000'0000;
|
|
if (AUTORTFM_LIKELY(Constants::PosOffsetMagicPrefix == (PrefixData & Mask)))
|
|
{
|
|
return reinterpret_cast<void*>(CharOpenFn + (PrefixData & ~Mask));
|
|
}
|
|
else if (AUTORTFM_LIKELY((Constants::NegOffsetMagicPrefix) == (PrefixData & Mask)))
|
|
{
|
|
// when NegOffsetMagicPrefix is matched, that means the offset was negative and we need to sign extend
|
|
return reinterpret_cast<void*>(CharOpenFn + (int64_t)(PrefixData | Mask));
|
|
}
|
|
// UBSAN adds a type hash prefix to the function as a "prologue" that
|
|
// ends preceding our Magic Prefix. They use 0xc105cafe in the
|
|
// lower 32-bits to distinguish the 64-bit word containing their type
|
|
// hash. If we see it, check the preceding 64-bit word for our prefix.
|
|
else if (AUTORTFM_UNLIKELY(UbsanMagic == (PrefixData & 0x0000'0000'ffff'ffff)))
|
|
{
|
|
memcpy(&PrefixData, reinterpret_cast<char*>(OpenFn) - sizeof(uint64_t) * 2, sizeof(uint64_t));
|
|
if (AUTORTFM_LIKELY(Constants::PosOffsetMagicPrefix == (PrefixData & Mask)))
|
|
{
|
|
return reinterpret_cast<void*>(CharOpenFn + (PrefixData & ~Mask));
|
|
}
|
|
else if (AUTORTFM_LIKELY((Constants::NegOffsetMagicPrefix) == (PrefixData & Mask)))
|
|
{
|
|
// when NegOffsetMagicPrefix is matched, that means the offset was negative and we need to sign extend
|
|
return reinterpret_cast<void*>(CharOpenFn + (int64_t)(PrefixData | Mask));
|
|
}
|
|
}
|
|
#else
|
|
memcpy(&PrefixData, reinterpret_cast<char*>(OpenFn) - sizeof(uint64_t), sizeof(uint64_t));
|
|
if (AUTORTFM_LIKELY(Constants::MagicPrefix == (PrefixData & 0xffff'0000'0000'0000)))
|
|
{
|
|
return reinterpret_cast<void*>(PrefixData & 0x0000'ffff'ffff'ffff);
|
|
}
|
|
// UBSAN adds a type hash prefix to the function as a "prologue" that
|
|
// ends preceding our Magic Prefix. They use 0xc105cafe in the
|
|
// lower 32-bits to distinguish the 64-bit word containing their type
|
|
// hash. If we see it, check the preceding 64-bit word for our prefix.
|
|
else if (AUTORTFM_UNLIKELY(UbsanMagic == (PrefixData & 0x0000'0000'ffff'ffff)))
|
|
{
|
|
memcpy(&PrefixData, reinterpret_cast<char*>(OpenFn) - sizeof(uint64_t) * 2, sizeof(uint64_t));
|
|
if (AUTORTFM_LIKELY(Constants::MagicPrefix == (PrefixData & 0xffff'0000'0000'0000)))
|
|
{
|
|
return reinterpret_cast<void*>(PrefixData & 0x0000'ffff'ffff'ffff);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
AUTORTFM_DISABLE inline void* FunctionMapLookup(void* OpenFn, const char* Where)
|
|
{
|
|
if (void* ClosedFn = FunctionMapLookupUsingMagicPrefix(OpenFn); AUTORTFM_LIKELY(ClosedFn))
|
|
{
|
|
return ClosedFn;
|
|
}
|
|
|
|
AUTORTFM_MUST_TAIL return FunctionMapLookupExhaustive(OpenFn, Where);
|
|
}
|
|
|
|
template<typename TReturnType, typename... TParameterTypes>
|
|
AUTORTFM_DISABLE auto FunctionMapLookup(TReturnType (*OpenFn)(TParameterTypes...), const char* Where) -> TReturnType (*)(TParameterTypes...)
|
|
{
|
|
return reinterpret_cast<TReturnType (*)(TParameterTypes...)>(FunctionMapLookup(reinterpret_cast<void*>(OpenFn), Where));
|
|
}
|
|
|
|
} // namespace AutoRTFM
|
|
|
|
#endif // (defined(__AUTORTFM) && __AUTORTFM)
|