122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
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#include "Luau/CodeBlockUnwind.h"
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#include "Luau/CodeAllocator.h"
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#include "Luau/UnwindBuilder.h"
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#include <string.h>
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#include <stdlib.h>
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#if defined(_WIN32) && defined(_M_X64)
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#ifndef WIN32_LEAN_AND_MEAN
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#define WIN32_LEAN_AND_MEAN
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#endif
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#ifndef NOMINMAX
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#define NOMINMAX
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#endif
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#include <Windows.h>
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#elif defined(__linux__) || defined(__APPLE__)
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// Defined in unwind.h which may not be easily discoverable on various platforms
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extern "C" void __register_frame(const void*);
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extern "C" void __deregister_frame(const void*);
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extern "C" void __unw_add_dynamic_fde() __attribute__((weak));
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#endif
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#if defined(__APPLE__) && defined(__aarch64__)
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#include <sys/sysctl.h>
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#endif
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namespace Luau
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{
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namespace CodeGen
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{
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#if defined(__linux__) || defined(__APPLE__)
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static void visitFdeEntries(char* pos, void (*cb)(const void*))
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{
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// When using glibc++ unwinder, we need to call __register_frame/__deregister_frame on the entire .eh_frame data
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// When using libc++ unwinder (libunwind), each FDE has to be handled separately
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// libc++ unwinder is the macOS unwinder, but on Linux the unwinder depends on the library the executable is linked with
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// __unw_add_dynamic_fde is specific to libc++ unwinder, as such we determine the library based on its existence
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if (__unw_add_dynamic_fde == nullptr)
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return cb(pos);
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for (;;)
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{
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unsigned partLength;
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memcpy(&partLength, pos, sizeof(partLength));
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if (partLength == 0) // Zero-length section signals completion
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break;
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unsigned partId;
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memcpy(&partId, pos + 4, sizeof(partId));
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if (partId != 0) // Skip CIE part
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cb(pos); // CIE is found using an offset in FDE
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pos += partLength + 4;
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}
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}
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#endif
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void* createBlockUnwindInfo(void* context, uint8_t* block, size_t blockSize, size_t& beginOffset)
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{
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UnwindBuilder* unwind = (UnwindBuilder*)context;
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// All unwinding related data is placed together at the start of the block
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size_t unwindSize = unwind->getSize();
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unwindSize = (unwindSize + (kCodeAlignment - 1)) & ~(kCodeAlignment - 1); // Match code allocator alignment
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LUAU_ASSERT(blockSize >= unwindSize);
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char* unwindData = (char*)block;
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unwind->finalize(unwindData, unwindSize, block, blockSize);
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#if defined(_WIN32) && defined(_M_X64)
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if (!RtlAddFunctionTable((RUNTIME_FUNCTION*)block, uint32_t(unwind->getFunctionCount()), uintptr_t(block)))
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{
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LUAU_ASSERT(!"Failed to allocate function table");
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return nullptr;
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}
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#elif defined(__linux__) || defined(__APPLE__)
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visitFdeEntries(unwindData, __register_frame);
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#endif
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beginOffset = unwindSize + unwind->getBeginOffset();
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return block;
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}
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void destroyBlockUnwindInfo(void* context, void* unwindData)
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{
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#if defined(_WIN32) && defined(_M_X64)
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if (!RtlDeleteFunctionTable((RUNTIME_FUNCTION*)unwindData))
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LUAU_ASSERT(!"Failed to deallocate function table");
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#elif defined(__linux__) || defined(__APPLE__)
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visitFdeEntries((char*)unwindData, __deregister_frame);
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#endif
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}
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bool isUnwindSupported()
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{
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#if defined(_WIN32) && defined(_M_X64)
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return true;
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#elif defined(__APPLE__) && defined(__aarch64__)
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char ver[256];
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size_t verLength = sizeof(ver);
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// libunwind on macOS 12 and earlier (which maps to osrelease 21) assumes JIT frames use pointer authentication without a way to override that
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return sysctlbyname("kern.osrelease", ver, &verLength, NULL, 0) == 0 && atoi(ver) >= 22;
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#elif defined(__linux__) || defined(__APPLE__)
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return true;
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#else
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return false;
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#endif
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}
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} // namespace CodeGen
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} // namespace Luau
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