diff options
Diffstat (limited to 'system/lib/libcxxabi/src/cxa_personality.cpp')
-rw-r--r-- | system/lib/libcxxabi/src/cxa_personality.cpp | 987 |
1 files changed, 987 insertions, 0 deletions
diff --git a/system/lib/libcxxabi/src/cxa_personality.cpp b/system/lib/libcxxabi/src/cxa_personality.cpp new file mode 100644 index 00000000..e49278c0 --- /dev/null +++ b/system/lib/libcxxabi/src/cxa_personality.cpp @@ -0,0 +1,987 @@ +//===------------------------- cxa_exception.cpp --------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +// +// This file implements the "Exception Handling APIs" +// http://www.codesourcery.com/public/cxx-abi/abi-eh.html +// http://www.intel.com/design/itanium/downloads/245358.htm +// +//===----------------------------------------------------------------------===// + +#include "unwind.h" +#include "cxa_exception.hpp" +#include "cxa_handlers.hpp" +#include "private_typeinfo.h" +#include <typeinfo> +#include <stdlib.h> +#include <assert.h> + +/* + Exception Header Layout: + ++---------------------------+-----------------------------+---------------+ +| __cxa_exception | _Unwind_Exception CLNGC++\0 | thrown object | ++---------------------------+-----------------------------+---------------+ + ^ + | + +-------------------------------------------------------+ + | ++---------------------------+-----------------------------+ +| __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 | ++---------------------------+-----------------------------+ + + Exception Handling Table Layout: + ++-----------------+--------+ +| lpStartEncoding | (char) | ++---------+-------+--------+---------------+-----------------------+ +| lpStart | (encoded wtih lpStartEncoding) | defaults to funcStart | ++---------+-----+--------+-----------------+---------------+-------+ +| ttypeEncoding | (char) | Encoding of the type_info table | ++---------------+-+------+----+----------------------------+----------------+ +| classInfoOffset | (ULEB128) | Offset to type_info table, defaults to null | ++-----------------++--------+-+----------------------------+----------------+ +| callSiteEncoding | (char) | Encoding for Call Site Table | ++------------------+--+-----+-----+------------------------+--------------------------+ +| callSiteTableLength | (ULEB128) | Call Site Table length, used to find Action table | ++---------------------+-----------+------------------------------------------------+--+ +| Beginning of Call Site Table If the current ip lies within the | +| ... (start, length) range of one of these | +| call sites, there may be action needed. | +| +-------------+---------------------------------+------------------------------+ | +| | start | (encoded with callSiteEncoding) | offset relative to funcStart | | +| | length | (encoded with callSiteEncoding) | lenght of code fragment | | +| | landingPad | (encoded with callSiteEncoding) | offset relative to lpStart | | +| | actionEntry | (ULEB128) | Action Table Index 1-based | | +| | | | actionEntry == 0 -> cleanup | | +| +-------------+---------------------------------+------------------------------+ | +| ... | ++---------------------------------------------------------------------+------------+ +| Beginning of Action Table ttypeIndex == 0 : cleanup | +| ... ttypeIndex > 0 : catch | +| ttypeIndex < 0 : exception spec | +| +--------------+-----------+--------------------------------------+ | +| | ttypeIndex | (SLEB128) | Index into type_info Table (1-based) | | +| | actionOffset | (SLEB128) | Offset into next Action Table entry | | +| +--------------+-----------+--------------------------------------+ | +| ... | ++---------------------------------------------------------------------+-----------------+ +| type_info Table, but classInfoOffset does *not* point here! | +| +----------------+------------------------------------------------+-----------------+ | +| | Nth type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == N | | +| +----------------+------------------------------------------------+-----------------+ | +| ... | +| +----------------+------------------------------------------------+-----------------+ | +| | 1st type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == 1 | | +| +----------------+------------------------------------------------+-----------------+ | +| +---------------------------------------+-----------+------------------------------+ | +| | 1st ttypeIndex for 1st exception spec | (ULEB128) | classInfoOffset points here! | | +| | ... | (ULEB128) | | | +| | Mth ttypeIndex for 1st exception spec | (ULEB128) | | | +| | 0 | (ULEB128) | | | +| +---------------------------------------+------------------------------------------+ | +| ... | +| +---------------------------------------+------------------------------------------+ | +| | 0 | (ULEB128) | throw() | | +| +---------------------------------------+------------------------------------------+ | +| ... | +| +---------------------------------------+------------------------------------------+ | +| | 1st ttypeIndex for Nth exception spec | (ULEB128) | | | +| | ... | (ULEB128) | | | +| | Mth ttypeIndex for Nth exception spec | (ULEB128) | | | +| | 0 | (ULEB128) | | | +| +---------------------------------------+------------------------------------------+ | ++---------------------------------------------------------------------------------------+ + +Notes: + +* ttypeIndex in the Action Table, and in the exception spec table, is an index, + not a byte count, if positive. It is a negative index offset of + classInfoOffset and the sizeof entry depends on ttypeEncoding. + But if ttypeIndex is negative, it is a positive 1-based byte offset into the + type_info Table. + And if ttypeIndex is zero, it refers to a catch (...). + +* landingPad can be 0, this implies there is nothing to be done. + +* landingPad != 0 and actionEntry == 0 implies a cleanup needs to be done + @landingPad. + +* A cleanup can also be found under landingPad != 0 and actionEntry != 0 in + the Action Table with ttypeIndex == 0. +*/ + +namespace __cxxabiv1 +{ + +extern "C" +{ + +// private API + +// Heavily borrowed from llvm/examples/ExceptionDemo/ExceptionDemo.cpp + +// DWARF Constants +enum +{ + DW_EH_PE_absptr = 0x00, + DW_EH_PE_uleb128 = 0x01, + DW_EH_PE_udata2 = 0x02, + DW_EH_PE_udata4 = 0x03, + DW_EH_PE_udata8 = 0x04, + DW_EH_PE_sleb128 = 0x09, + DW_EH_PE_sdata2 = 0x0A, + DW_EH_PE_sdata4 = 0x0B, + DW_EH_PE_sdata8 = 0x0C, + DW_EH_PE_pcrel = 0x10, + DW_EH_PE_textrel = 0x20, + DW_EH_PE_datarel = 0x30, + DW_EH_PE_funcrel = 0x40, + DW_EH_PE_aligned = 0x50, + DW_EH_PE_indirect = 0x80, + DW_EH_PE_omit = 0xFF +}; + +/// Read a uleb128 encoded value and advance pointer +/// See Variable Length Data Appendix C in: +/// @link http://dwarfstd.org/Dwarf4.pdf @unlink +/// @param data reference variable holding memory pointer to decode from +/// @returns decoded value +static +uintptr_t +readULEB128(const uint8_t** data) +{ + uintptr_t result = 0; + uintptr_t shift = 0; + unsigned char byte; + const uint8_t *p = *data; + do + { + byte = *p++; + result |= static_cast<uintptr_t>(byte & 0x7F) << shift; + shift += 7; + } while (byte & 0x80); + *data = p; + return result; +} + +/// Read a sleb128 encoded value and advance pointer +/// See Variable Length Data Applendix C in: +/// @link http://dwarfstd.org/Dwarf4.pdf @unlink +/// @param data reference variable holding memory pointer to decode from +/// @returns decoded value +static +uintptr_t +readSLEB128(const uint8_t** data) +{ + uintptr_t result = 0; + uintptr_t shift = 0; + unsigned char byte; + const uint8_t *p = *data; + do + { + byte = *p++; + result |= static_cast<uintptr_t>(byte & 0x7F) << shift; + shift += 7; + } while (byte & 0x80); + *data = p; + if ((byte & 0x40) && (shift < (sizeof(result) << 3))) + result |= static_cast<uintptr_t>(~0) << shift; + return result; +} + +/// Read a pointer encoded value and advance pointer +/// See Variable Length Data in: +/// @link http://dwarfstd.org/Dwarf3.pdf @unlink +/// @param data reference variable holding memory pointer to decode from +/// @param encoding dwarf encoding type +/// @returns decoded value +static +uintptr_t +readEncodedPointer(const uint8_t** data, uint8_t encoding) +{ + uintptr_t result = 0; + if (encoding == DW_EH_PE_omit) + return result; + const uint8_t* p = *data; + // first get value + switch (encoding & 0x0F) + { + case DW_EH_PE_absptr: + result = *((uintptr_t*)p); + p += sizeof(uintptr_t); + break; + case DW_EH_PE_uleb128: + result = readULEB128(&p); + break; + case DW_EH_PE_sleb128: + result = readSLEB128(&p); + break; + case DW_EH_PE_udata2: + result = *((uint16_t*)p); + p += sizeof(uint16_t); + break; + case DW_EH_PE_udata4: + result = *((uint32_t*)p); + p += sizeof(uint32_t); + break; + case DW_EH_PE_udata8: + result = *((uint64_t*)p); + p += sizeof(uint64_t); + break; + case DW_EH_PE_sdata2: + result = *((int16_t*)p); + p += sizeof(int16_t); + break; + case DW_EH_PE_sdata4: + result = *((int32_t*)p); + p += sizeof(int32_t); + break; + case DW_EH_PE_sdata8: + result = *((int64_t*)p); + p += sizeof(int64_t); + break; + default: + // not supported + abort(); + break; + } + // then add relative offset + switch (encoding & 0x70) + { + case DW_EH_PE_absptr: + // do nothing + break; + case DW_EH_PE_pcrel: + if (result) + result += (uintptr_t)(*data); + break; + case DW_EH_PE_textrel: + case DW_EH_PE_datarel: + case DW_EH_PE_funcrel: + case DW_EH_PE_aligned: + default: + // not supported + abort(); + break; + } + // then apply indirection + if (result && (encoding & DW_EH_PE_indirect)) + result = *((uintptr_t*)result); + *data = p; + return result; +} + +static +void +call_terminate(bool native_exception, _Unwind_Exception* unwind_exception) +{ + __cxa_begin_catch(unwind_exception); + if (native_exception) + { + // Use the stored terminate_handler if possible + __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; + std::__terminate(exception_header->terminateHandler); + } + std::terminate(); +} + +static +const __shim_type_info* +get_shim_type_info(int64_t ttypeIndex, const uint8_t* classInfo, + uint8_t ttypeEncoding, bool native_exception, + _Unwind_Exception* unwind_exception) +{ + if (classInfo == 0) + { + // this should not happen. Indicates corrupted eh_table. + call_terminate(native_exception, unwind_exception); + } + switch (ttypeEncoding & 0x0F) + { + case DW_EH_PE_absptr: + ttypeIndex *= sizeof(void*); + break; + case DW_EH_PE_udata2: + case DW_EH_PE_sdata2: + ttypeIndex *= 2; + break; + case DW_EH_PE_udata4: + case DW_EH_PE_sdata4: + ttypeIndex *= 4; + break; + case DW_EH_PE_udata8: + case DW_EH_PE_sdata8: + ttypeIndex *= 8; + break; + default: + // this should not happen. Indicates corrupted eh_table. + call_terminate(native_exception, unwind_exception); + } + classInfo -= ttypeIndex; + return (const __shim_type_info*)readEncodedPointer(&classInfo, ttypeEncoding); +} + +/* + This is checking a thrown exception type, excpType, against a posibly empty + list of catchType's which make up an exception spec. + + An exception spec acts like a catch handler, but in reverse. This "catch + handler" will catch an excpType if and only if none of the catchType's in + the list will catch a excpType. If any catchType in the list can catch an + excpType, then this exception spec does not catch the excpType. +*/ +static +bool +exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo, + uint8_t ttypeEncoding, const __shim_type_info* excpType, + void* adjustedPtr, _Unwind_Exception* unwind_exception) +{ + if (classInfo == 0) + { + // this should not happen. Indicates corrupted eh_table. + call_terminate(false, unwind_exception); + } + // specIndex is negative of 1-based byte offset into classInfo; + specIndex = -specIndex; + --specIndex; + const uint8_t* temp = classInfo + specIndex; + // If any type in the spec list can catch excpType, return false, else return true + // adjustments to adjustedPtr are ignored. + while (true) + { + uint64_t ttypeIndex = readULEB128(&temp); + if (ttypeIndex == 0) + break; + const __shim_type_info* catchType = get_shim_type_info(ttypeIndex, + classInfo, + ttypeEncoding, + true, + unwind_exception); + void* tempPtr = adjustedPtr; + if (catchType->can_catch(excpType, tempPtr)) + return false; + } + return true; +} + +static +void* +get_thrown_object_ptr(_Unwind_Exception* unwind_exception) +{ + // Even for foreign exceptions, the exception object is *probably* at unwind_exception + 1 + // Regardless, this library is prohibited from touching a foreign exception + void* adjustedPtr = unwind_exception + 1; + if (unwind_exception->exception_class == kOurDependentExceptionClass) + adjustedPtr = ((__cxa_dependent_exception*)adjustedPtr - 1)->primaryException; + return adjustedPtr; +} + +/* + There are 3 types of scans needed: + + 1. Scan for handler with native or foreign exception. If handler found, + save state and return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND. + May also report an error on invalid input. + May terminate for invalid exception table. + _UA_SEARCH_PHASE + + 2. Scan for handler with foreign exception. Must return _URC_HANDLER_FOUND, + or call terminate. + _UA_CLEANUP_PHASE && _UA_HANDLER_FRAME && !native_exception + + 3. Scan for cleanups. If a handler is found and this isn't forced unwind, + then terminate, otherwise ignore the handler and keep looking for cleanup. + If a cleanup is found, return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND. + May also report an error on invalid input. + May terminate for invalid exception table. + _UA_CLEANUP_PHASE && !_UA_HANDLER_FRAME +*/ + +namespace +{ + +struct scan_results +{ + int64_t ttypeIndex; // > 0 catch handler, < 0 exception spec handler, == 0 a cleanup + const uint8_t* actionRecord; // Currently unused. Retained to ease future maintenance. + const uint8_t* languageSpecificData; // Needed only for __cxa_call_unexpected + uintptr_t landingPad; // null -> nothing found, else something found + void* adjustedPtr; // Used in cxa_exception.cpp + _Unwind_Reason_Code reason; // One of _URC_FATAL_PHASE1_ERROR, + // _URC_FATAL_PHASE2_ERROR, + // _URC_CONTINUE_UNWIND, + // _URC_HANDLER_FOUND +}; + +} // unnamed namespace + +static +void +scan_eh_tab(scan_results& results, _Unwind_Action actions, bool native_exception, + _Unwind_Exception* unwind_exception, _Unwind_Context* context) +{ + // Initialize results to found nothing but an error + results.ttypeIndex = 0; + results.actionRecord = 0; + results.languageSpecificData = 0; + results.landingPad = 0; + results.adjustedPtr = 0; + results.reason = _URC_FATAL_PHASE1_ERROR; + // Check for consistent actions + if (actions & _UA_SEARCH_PHASE) + { + // Do Phase 1 + if (actions & (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME | _UA_FORCE_UNWIND)) + { + // None of these flags should be set during Phase 1 + // Client error + results.reason = _URC_FATAL_PHASE1_ERROR; + return; + } + } + else if (actions & _UA_CLEANUP_PHASE) + { + if ((actions & _UA_HANDLER_FRAME) && (actions & _UA_FORCE_UNWIND)) + { + // _UA_HANDLER_FRAME should only be set if phase 1 found a handler. + // If _UA_FORCE_UNWIND is set, phase 1 shouldn't have happened. + // Client error + results.reason = _URC_FATAL_PHASE2_ERROR; + return; + } + } + else // Niether _UA_SEARCH_PHASE nor _UA_CLEANUP_PHASE is set + { + // One of these should be set. + // Client error + results.reason = _URC_FATAL_PHASE1_ERROR; + return; + } + // Start scan by getting exception table address + const uint8_t* lsda = (const uint8_t*)_Unwind_GetLanguageSpecificData(context); + if (lsda == 0) + { + // There is no exception table + results.reason = _URC_CONTINUE_UNWIND; + return; + } + results.languageSpecificData = lsda; + // Get the current instruction pointer and offset it before next + // instruction in the current frame which threw the exception. + uintptr_t ip = _Unwind_GetIP(context) - 1; + // Get beginning current frame's code (as defined by the + // emitted dwarf code) + uintptr_t funcStart = _Unwind_GetRegionStart(context); + uintptr_t ipOffset = ip - funcStart; + const uint8_t* classInfo = NULL; + // Note: See JITDwarfEmitter::EmitExceptionTable(...) for corresponding + // dwarf emission + // Parse LSDA header. + uint8_t lpStartEncoding = *lsda++; + const uint8_t* lpStart = (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding); + if (lpStart == 0) + lpStart = (const uint8_t*)funcStart; + uint8_t ttypeEncoding = *lsda++; + if (ttypeEncoding != DW_EH_PE_omit) + { + // Calculate type info locations in emitted dwarf code which + // were flagged by type info arguments to llvm.eh.selector + // intrinsic + uintptr_t classInfoOffset = readULEB128(&lsda); + classInfo = lsda + classInfoOffset; + } + // Walk call-site table looking for range that + // includes current PC. + uint8_t callSiteEncoding = *lsda++; + uint32_t callSiteTableLength = readULEB128(&lsda); + const uint8_t* callSiteTableStart = lsda; + const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength; + const uint8_t* actionTableStart = callSiteTableEnd; + const uint8_t* callSitePtr = callSiteTableStart; + while (true) + { + // There is one entry per call site. + // The call sites are non-overlapping in [start, start+length) + // The call sites are ordered in increasing value of start + uintptr_t start = readEncodedPointer(&callSitePtr, callSiteEncoding); + uintptr_t length = readEncodedPointer(&callSitePtr, callSiteEncoding); + uintptr_t landingPad = readEncodedPointer(&callSitePtr, callSiteEncoding); + uintptr_t actionEntry = readULEB128(&callSitePtr); + if ((start <= ipOffset) && (ipOffset < (start + length))) + { + // Found the call site containing ip. + if (landingPad == 0) + { + // No handler here + results.reason = _URC_CONTINUE_UNWIND; + return; + } + landingPad = (uintptr_t)lpStart + landingPad; + if (actionEntry == 0) + { + // Found a cleanup + // If this is a type 1 or type 2 search, there are no handlers + // If this is a type 3 search, you want to install the cleanup. + if ((actions & _UA_CLEANUP_PHASE) && !(actions & _UA_HANDLER_FRAME)) + { + results.ttypeIndex = 0; // Redundant but clarifying + results.landingPad = landingPad; + results.reason = _URC_HANDLER_FOUND; + return; + } + // No handler here + results.reason = _URC_CONTINUE_UNWIND; + return; + } + // Convert 1-based byte offset into + const uint8_t* action = actionTableStart + (actionEntry - 1); + // Scan action entries until you find a matching handler, cleanup, or the end of action list + while (true) + { + const uint8_t* actionRecord = action; + int64_t ttypeIndex = readSLEB128(&action); + if (ttypeIndex > 0) + { + // Found a catch, does it actually catch? + // First check for catch (...) + const __shim_type_info* catchType = + get_shim_type_info(ttypeIndex, classInfo, + ttypeEncoding, native_exception, + unwind_exception); + if (catchType == 0) + { + // Found catch (...) catches everything, including foreign exceptions + // If this is a type 1 search save state and return _URC_HANDLER_FOUND + // If this is a type 2 search save state and return _URC_HANDLER_FOUND + // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1! + // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan + if ((actions & _UA_SEARCH_PHASE) || (actions & _UA_HANDLER_FRAME)) + { + // Save state and return _URC_HANDLER_FOUND + results.ttypeIndex = ttypeIndex; + results.actionRecord = actionRecord; + results.landingPad = landingPad; + results.adjustedPtr = get_thrown_object_ptr(unwind_exception); + results.reason = _URC_HANDLER_FOUND; + return; + } + else if (!(actions & _UA_FORCE_UNWIND)) + { + // It looks like the exception table has changed + // on us. Likely stack corruption! + call_terminate(native_exception, unwind_exception); + } + } + // Else this is a catch (T) clause and will never + // catch a foreign exception + else if (native_exception) + { + __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; + void* adjustedPtr = get_thrown_object_ptr(unwind_exception); + const __shim_type_info* excpType = + static_cast<const __shim_type_info*>(exception_header->exceptionType); + if (adjustedPtr == 0 || excpType == 0) + { + // Something very bad happened + call_terminate(native_exception, unwind_exception); + } + if (catchType->can_catch(excpType, adjustedPtr)) + { + // Found a matching handler + // If this is a type 1 search save state and return _URC_HANDLER_FOUND + // If this is a type 3 search and !_UA_FORCE_UNWIND, we should have found this in phase 1! + // If this is a type 3 search and _UA_FORCE_UNWIND, ignore handler and continue scan + if (actions & _UA_SEARCH_PHASE) + { + // Save state and return _URC_HANDLER_FOUND + results.ttypeIndex = ttypeIndex; + results.actionRecord = actionRecord; + results.landingPad = landingPad; + results.adjustedPtr = adjustedPtr; + results.reason = _URC_HANDLER_FOUND; + return; + } + else if (!(actions & _UA_FORCE_UNWIND)) + { + // It looks like the exception table has changed + // on us. Likely stack corruption! + call_terminate(native_exception, unwind_exception); + } + } + } + // Scan next action ... + } + else if (ttypeIndex < 0) + { + // Found an exception spec. If this is a foreign exception, + // it is always caught. + if (native_exception) + { + // Does the exception spec catch this native exception? + __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; + void* adjustedPtr = get_thrown_object_ptr(unwind_exception); + const __shim_type_info* excpType = + static_cast<const __shim_type_info*>(exception_header->exceptionType); + if (adjustedPtr == 0 || excpType == 0) + { + // Something very bad happened + call_terminate(native_exception, unwind_exception); + } + if (exception_spec_can_catch(ttypeIndex, classInfo, + ttypeEncoding, excpType, + adjustedPtr, unwind_exception)) + { + // native exception caught by exception spec + // If this is a type 1 search, save state and return _URC_HANDLER_FOUND + // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1! + // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan + if (actions & _UA_SEARCH_PHASE) + { + // Save state and return _URC_HANDLER_FOUND + results.ttypeIndex = ttypeIndex; + results.actionRecord = actionRecord; + results.landingPad = landingPad; + results.adjustedPtr = adjustedPtr; + results.reason = _URC_HANDLER_FOUND; + return; + } + else if (!(actions & _UA_FORCE_UNWIND)) + { + // It looks like the exception table has changed + // on us. Likely stack corruption! + call_terminate(native_exception, unwind_exception); + } + } + } + else + { + // foreign exception caught by exception spec + // If this is a type 1 search, save state and return _URC_HANDLER_FOUND + // If this is a type 2 search, save state and return _URC_HANDLER_FOUND + // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1! + // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan + if ((actions & _UA_SEARCH_PHASE) || (actions & _UA_HANDLER_FRAME)) + { + // Save state and return _URC_HANDLER_FOUND + results.ttypeIndex = ttypeIndex; + results.actionRecord = actionRecord; + results.landingPad = landingPad; + results.adjustedPtr = get_thrown_object_ptr(unwind_exception); + results.reason = _URC_HANDLER_FOUND; + return; + } + else if (!(actions & _UA_FORCE_UNWIND)) + { + // It looks like the exception table has changed + // on us. Likely stack corruption! + call_terminate(native_exception, unwind_exception); + } + } + // Scan next action ... + } + else // ttypeIndex == 0 + { + // Found a cleanup + // If this is a type 1 search, ignore it and continue scan + // If this is a type 2 search, ignore it and continue scan + // If this is a type 3 search, save state and return _URC_HANDLER_FOUND + if ((actions & _UA_CLEANUP_PHASE) && !(actions & _UA_HANDLER_FRAME)) + { + // Save state and return _URC_HANDLER_FOUND + results.ttypeIndex = ttypeIndex; + results.actionRecord = actionRecord; + results.landingPad = landingPad; + results.adjustedPtr = get_thrown_object_ptr(unwind_exception); + results.reason = _URC_HANDLER_FOUND; + return; + } + } + const uint8_t* temp = action; + int64_t actionOffset = readSLEB128(&temp); + if (actionOffset == 0) + { + // End of action list, no matching handler or cleanup found + results.reason = _URC_CONTINUE_UNWIND; + return; + } + // Go to next action + action += actionOffset; + } // there is no break out of this loop, only return + } + else if (ipOffset < start) + { + // There is no call site for this ip + // Something bad has happened. We should never get here. + // Possible stack corruption. + call_terminate(native_exception, unwind_exception); + } + } // there is no break out of this loop, only return +} + +// public API + +/* +The personality function branches on actions like so: + +_UA_SEARCH_PHASE + + If _UA_CLEANUP_PHASE or _UA_HANDLER_FRAME or _UA_FORCE_UNWIND there's + an error from above, return _URC_FATAL_PHASE1_ERROR. + + Scan for anything that could stop unwinding: + + 1. A catch clause that will catch this exception + (will never catch foreign). + 2. A catch (...) (will always catch foreign). + 3. An exception spec that will catch this exception + (will always catch foreign). + If a handler is found + If not foreign + Save state in header + return _URC_HANDLER_FOUND + Else a handler not found + return _URC_CONTINUE_UNWIND + +_UA_CLEANUP_PHASE + + If _UA_HANDLER_FRAME + If _UA_FORCE_UNWIND + How did this happen? return _URC_FATAL_PHASE2_ERROR + If foreign + Do _UA_SEARCH_PHASE to recover state + else + Recover state from header + Transfer control to landing pad. return _URC_INSTALL_CONTEXT + + Else + + This branch handles both normal C++ non-catching handlers (cleanups) + and forced unwinding. + Scan for anything that can not stop unwinding: + + 1. A cleanup. + + If a cleanup is found + transfer control to it. return _URC_INSTALL_CONTEXT + Else a cleanup is not found: return _URC_CONTINUE_UNWIND +*/ + +_Unwind_Reason_Code +__gxx_personality_v0(int version, _Unwind_Action actions, uint64_t exceptionClass, + _Unwind_Exception* unwind_exception, _Unwind_Context* context) +{ + if (version != 1 || unwind_exception == 0 || context == 0) + return _URC_FATAL_PHASE1_ERROR; + bool native_exception = (exceptionClass & get_vendor_and_language) == + (kOurExceptionClass & get_vendor_and_language); + scan_results results; + if (actions & _UA_SEARCH_PHASE) + { + // Phase 1 search: All we're looking for in phase 1 is a handler that + // halts unwinding + scan_eh_tab(results, actions, native_exception, unwind_exception, context); + if (results.reason == _URC_HANDLER_FOUND) + { + // Found one. Can we cache the results somewhere to optimize phase 2? + if (native_exception) + { + __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; + exception_header->handlerSwitchValue = static_cast<int>(results.ttypeIndex); + exception_header->actionRecord = results.actionRecord; + exception_header->languageSpecificData = results.languageSpecificData; + exception_header->catchTemp = reinterpret_cast<void*>(results.landingPad); + exception_header->adjustedPtr = results.adjustedPtr; + } + return _URC_HANDLER_FOUND; + } + // Did not find a catching-handler. Return the results of the scan + // (normally _URC_CONTINUE_UNWIND, but could have been _URC_FATAL_PHASE1_ERROR + // if we were called improperly). + return results.reason; + } + if (actions & _UA_CLEANUP_PHASE) + { + // Phase 2 search: + // Did we find a catching handler in phase 1? + if (actions & _UA_HANDLER_FRAME) + { + // Yes, phase 1 said we have a catching handler here. + // Did we cache the results of the scan? + if (native_exception) + { + // Yes, reload the results from the cache. + __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; + results.ttypeIndex = exception_header->handlerSwitchValue; + results.actionRecord = exception_header->actionRecord; + results.languageSpecificData = exception_header->languageSpecificData; + results.landingPad = reinterpret_cast<uintptr_t>(exception_header->catchTemp); + results.adjustedPtr = exception_header->adjustedPtr; + } + else + { + // No, do the scan again to reload the results. + scan_eh_tab(results, actions, native_exception, unwind_exception, context); + // Phase 1 told us we would find a handler. Now in Phase 2 we + // didn't find a handler. The eh table should not be changing! + if (results.reason != _URC_HANDLER_FOUND) + call_terminate(native_exception, unwind_exception); + } + // Jump to the handler + _Unwind_SetGR(context, __builtin_eh_return_data_regno(0), (uintptr_t)unwind_exception); + _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), results.ttypeIndex); + _Unwind_SetIP(context, results.landingPad); + return _URC_INSTALL_CONTEXT; + } + // Either we didn't do a phase 1 search (due to forced unwinding), or + // phase 1 reported no catching-handlers. + // Search for a (non-catching) cleanup + scan_eh_tab(results, actions, native_exception, unwind_exception, context); + if (results.reason == _URC_HANDLER_FOUND) + { + // Found a non-catching handler. Jump to it: + _Unwind_SetGR(context, __builtin_eh_return_data_regno(0), (uintptr_t)unwind_exception); + _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), results.ttypeIndex); + _Unwind_SetIP(context, results.landingPad); + return _URC_INSTALL_CONTEXT; + } + // Did not find a cleanup. Return the results of the scan + // (normally _URC_CONTINUE_UNWIND, but could have been _URC_FATAL_PHASE2_ERROR + // if we were called improperly). + return results.reason; + } + // We were called improperly: neither a phase 1 or phase 2 search + return _URC_FATAL_PHASE1_ERROR; +} + +__attribute__((noreturn)) +void +__cxa_call_unexpected(void* arg) +{ + _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(arg); + if (unwind_exception == 0) + call_terminate(false, unwind_exception); + __cxa_begin_catch(unwind_exception); + bool native_old_exception = + (unwind_exception->exception_class & get_vendor_and_language) == + (kOurExceptionClass & get_vendor_and_language); + std::unexpected_handler u_handler; + std::terminate_handler t_handler; + __cxa_exception* old_exception_header = 0; + int64_t ttypeIndex; + const uint8_t* lsda; + if (native_old_exception) + { + old_exception_header = (__cxa_exception*)(unwind_exception+1) - 1; + t_handler = old_exception_header->terminateHandler; + u_handler = old_exception_header->unexpectedHandler; + // If std::__unexpected(u_handler) rethrows the same exception, + |