COMPILER_RT_ABI _Unwind_Reason_Code
__gcc_personality_v0(int version, _Unwind_Action actions,
uint64_t exceptionClass, struct _Unwind_Exception* exceptionObject,
struct _Unwind_Context *context)
#endif
{
/* Since C does not have catch clauses, there is nothing to do during */
/* phase 1 (the search phase). */
if ( actions & _UA_SEARCH_PHASE )
return _URC_CONTINUE_UNWIND;
/* There is nothing to do if there is no LSDA for this frame. */
const uint8_t* lsda = (uint8_t*)_Unwind_GetLanguageSpecificData(context);
if ( lsda == (uint8_t*) 0 )
return _URC_CONTINUE_UNWIND;
uintptr_t pc = _Unwind_GetIP(context)-1;
uintptr_t funcStart = _Unwind_GetRegionStart(context);
uintptr_t pcOffset = pc - funcStart;
/* Parse LSDA header. */
uint8_t lpStartEncoding = *lsda++;
if (lpStartEncoding != DW_EH_PE_omit) {
readEncodedPointer(&lsda, lpStartEncoding);
}
uint8_t ttypeEncoding = *lsda++;
if (ttypeEncoding != DW_EH_PE_omit) {
readULEB128(&lsda);
}
/* 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* p=callSiteTableStart;
while (p < callSiteTableEnd) {
uintptr_t start = readEncodedPointer(&p, callSiteEncoding);
uintptr_t length = readEncodedPointer(&p, callSiteEncoding);
uintptr_t landingPad = readEncodedPointer(&p, callSiteEncoding);
readULEB128(&p); /* action value not used for C code */
if ( landingPad == 0 )
continue; /* no landing pad for this entry */
if ( (start <= pcOffset) && (pcOffset < (start+length)) ) {
/* Found landing pad for the PC.
* Set Instruction Pointer to so we re-enter function
* at landing pad. The landing pad is created by the compiler
* to take two parameters in registers.
*/
_Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
(uintptr_t)exceptionObject);
_Unwind_SetGR(context, __builtin_eh_return_data_regno(1), 0);
_Unwind_SetIP(context, (funcStart + landingPad));
return _URC_INSTALL_CONTEXT;
}
}
/* No landing pad found, continue unwinding. */
return _URC_CONTINUE_UNWIND;
}
static
const __shim_type_info*
get_shim_type_info(uint64_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);
}
static int dlCallback(struct dl_phdr_info *info, size_t size, void *data)
{
CBData* cbdata = static_cast<CBData*>(data);
bool addrMatch = false;
void* maxAddr = 0;
const eh_frame_hdr* ehdr = 0;
if (cbdata->info->dwarf_section) // we already have a match
return 0;
//std::cout << "Looking into " << info->dlpi_name << std::endl;
if (size < offsetof(struct dl_phdr_info, dlpi_phnum))
return 0;
for (int i = 0; i < info->dlpi_phnum; i++)
{
const ElfW(Phdr)* phdr = &info->dlpi_phdr[i];
/*
if (strstr(info->dlpi_name, "cxxdarwin"))
{
std::cout << "type: " << phdr->p_type << "; vaddr: " << phdr->p_vaddr << std::endl;
}
*/
if (phdr->p_type == PT_LOAD)
{
void* from = reinterpret_cast<void*>(uintptr_t(info->dlpi_addr) + uintptr_t(phdr->p_vaddr));
void* to = reinterpret_cast<char*>(from) + phdr->p_memsz;
if (cbdata->addr >= from && cbdata->addr < to)
addrMatch = true;
if (to > maxAddr)
maxAddr = to; // TODO: could this be improved? libunwind does the same
}
else if (phdr->p_type == PT_GNU_EH_FRAME)
{
//std::cout << "Found .eh_frame_hdr in " << info->dlpi_name << std::endl;
ehdr = reinterpret_cast<eh_frame_hdr*>(uintptr_t(info->dlpi_addr) + phdr->p_vaddr);
// cbdata->info->dwarf_section_length = phdr->p_memsz;
}
}
if (addrMatch && ehdr)
{
//std::cout << "*** Match found! " << info->dlpi_name << std::endl;
// Now we find .eh_frame from .eh_frame_hdr
if (ehdr->version != 1)
return 0;
cbdata->info->dwarf_section = reinterpret_cast<void*>(readEncodedPointer(ehdr));
cbdata->info->dwarf_section_length = uintptr_t(maxAddr) - uintptr_t(cbdata->info->dwarf_section);
}
return 0;
}
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 =
(reinterpret_cast<uint64_t>(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,
// these values get overwritten by the rethrow. So save them now:
#ifndef __ARM_EABI_UNWINDER__
ttypeIndex = old_exception_header->handlerSwitchValue;
lsda = old_exception_header->languageSpecificData;
#endif
}
else
{
t_handler = std::get_terminate();
u_handler = std::get_unexpected();
}
try
{
std::__unexpected(u_handler);
}
catch (...)
{
// If the old exception is foreign, then all we can do is terminate.
// We have no way to recover the needed old exception spec. There's
// no way to pass that information here. And the personality routine
// can't call us directly and do anything but terminate() if we throw
// from here.
if (native_old_exception)
{
// Have:
// old_exception_header->languageSpecificData
// old_exception_header->actionRecord
// Need
// const uint8_t* classInfo
// uint8_t ttypeEncoding
uint8_t lpStartEncoding = *lsda++;
const uint8_t* lpStart = (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding);
(void)lpStart; // purposefully unused. Just needed to increment lsda.
uint8_t ttypeEncoding = *lsda++;
if (ttypeEncoding == DW_EH_PE_omit)
std::__terminate(t_handler);
uintptr_t classInfoOffset = readULEB128(&lsda);
const uint8_t* classInfo = lsda + classInfoOffset;
// Is this new exception catchable by the exception spec at ttypeIndex?
// The answer is obviously yes if the new and old exceptions are the same exception
// If no
// throw;
__cxa_eh_globals* globals = __cxa_get_globals_fast();
__cxa_exception* new_exception_header = globals->caughtExceptions;
if (new_exception_header == 0)
// This shouldn't be able to happen!
std::__terminate(t_handler);
bool native_new_exception =
(reinterpret_cast<uint64_t>(new_exception_header->unwindHeader.exception_class) & get_vendor_and_language) ==
(kOurExceptionClass & get_vendor_and_language);
void* adjustedPtr;
if (native_new_exception && (new_exception_header != old_exception_header))
{
const __shim_type_info* excpType =
static_cast<const __shim_type_info*>(new_exception_header->exceptionType);
adjustedPtr =
reinterpret_cast<uint64_t>(new_exception_header->unwindHeader.exception_class) == kOurDependentExceptionClass ?
((__cxa_dependent_exception*)new_exception_header)->primaryException :
new_exception_header + 1;
if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
excpType, adjustedPtr, unwind_exception))
{
// We need to __cxa_end_catch, but for the old exception,
// not the new one. This is a little tricky ...
// Disguise new_exception_header as a rethrown exception, but
// don't actually rethrow it. This means you can temporarily
// end the catch clause enclosing new_exception_header without
// __cxa_end_catch destroying new_exception_header.
new_exception_header->handlerCount = -new_exception_header->handlerCount;
globals->uncaughtExceptions += 1;
// Call __cxa_end_catch for new_exception_header
__cxa_end_catch();
// Call __cxa_end_catch for old_exception_header
__cxa_end_catch();
// Renter this catch clause with new_exception_header
__cxa_begin_catch(&new_exception_header->unwindHeader);
// Rethrow new_exception_header
throw;
}
}
// Will a std::bad_exception be catchable by the exception spec at
// ttypeIndex?
// If no
// throw std::bad_exception();
const __shim_type_info* excpType =
static_cast<const __shim_type_info*>(&typeid(std::bad_exception));
std::bad_exception be;
adjustedPtr = &be;
if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
excpType, adjustedPtr, unwind_exception))
{
// We need to __cxa_end_catch for both the old exception and the
// new exception. Technically we should do it in that order.
// But it is expedient to do it in the opposite order:
// Call __cxa_end_catch for new_exception_header
__cxa_end_catch();
// Throw std::bad_exception will __cxa_end_catch for
// old_exception_header
throw be;
}
}
}
std::__terminate(t_handler);
}
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 // Neither _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);
#if __arm__
if (ip == uintptr_t(-1))
{
// no action
results.reason = _URC_CONTINUE_UNWIND;
return;
}
else if (ip == 0)
call_terminate(native_exception, unwind_exception);
// ip is 1-based index into call site table
#else // __arm__
uintptr_t ipOffset = ip - funcStart;
#endif // __arm__
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++;
#if __arm__
(void)callSiteEncoding; // On arm callSiteEncoding is never used
#endif
uint32_t callSiteTableLength = static_cast<uint32_t>(readULEB128(&lsda));
const uint8_t* callSiteTableStart = lsda;
const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength;
const uint8_t* actionTableStart = callSiteTableEnd;
const uint8_t* callSitePtr = callSiteTableStart;
while (callSitePtr < callSiteTableEnd)
{
// There is one entry per call site.
#if !__arm__
// 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)))
#else // __arm__
// ip is 1-based index into this table
uintptr_t landingPad = readULEB128(&callSitePtr);
uintptr_t actionEntry = readULEB128(&callSitePtr);
if (--ip == 0)
#endif // __arm__
{
// Found the call site containing ip.
#if !__arm__
if (landingPad == 0)
{
// No handler here
results.reason = _URC_CONTINUE_UNWIND;
return;
}
landingPad = (uintptr_t)lpStart + landingPad;
#else // __arm__
++landingPad;
#endif // __arm__
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(static_cast<uint64_t>(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
}
#if !__arm__
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);
}
#endif // !__arm__
} // there might be some tricky cases which break out of this loop
// It is possible that no eh table entry specify how to handle
// this exception. By spec, terminate it immediately.
call_terminate(native_exception, unwind_exception);
}