/*
* Lookup a catch trace for the given TCA, returning nullptr if none was
* found. Will abort if a nullptr catch trace was registered, meaning this call
* isn't allowed to throw.
*/
TCA lookup_catch_trace(TCA rip, _Unwind_Exception* exn) {
if (auto catchTraceOpt = mcg->getCatchTrace(rip)) {
if (auto catchTrace = *catchTraceOpt) return catchTrace;
// A few of our optimization passes must be aware of every path out of
// the trace, so throwing through jitted code without a catch block is
// very bad. This is indicated with a present but nullptr entry in the
// catch trace map.
const size_t kCallSize = 5;
const uint8_t kCallOpcode = 0xe8;
auto callAddr = rip - kCallSize;
TCA helperAddr = nullptr;
if (*callAddr == kCallOpcode) {
helperAddr = rip + *reinterpret_cast<int32_t*>(callAddr + 1);
}
always_assert_flog(false,
"Translated call to {} threw '{}' without "
"catch block, return address: {}\n",
getNativeFunctionName(helperAddr),
typeInfoFromUnwindException(exn).name(),
rip);
}
return nullptr;
}
bool install_catch_trace(_Unwind_Context* ctx, _Unwind_Exception* exn,
bool do_side_exit, TypedValue unwinder_tv) {
auto const rip = (TCA)_Unwind_GetIP(ctx);
auto catchTraceOpt = mcg->getCatchTrace(rip);
FTRACE(1, "No catch trace entry for ip {}; bailing\n", rip);
if (!catchTraceOpt) return false;
auto catchTrace = *catchTraceOpt;
if (!catchTrace) {
// A few of our optimization passes must be aware of every path out of the
// trace, so throwing through jitted code without a catch block is very
// bad. This is indicated with a present but nullptr entry in the catch
// trace map.
const size_t kCallSize = 5;
const uint8_t kCallOpcode = 0xe8;
auto callAddr = rip - kCallSize;
TCA helperAddr = nullptr;
std::string helperName;
if (*callAddr == kCallOpcode) {
helperAddr = rip + *reinterpret_cast<int32_t*>(callAddr + 1);
}
always_assert_flog(false,
"Translated call to {} threw '{}' without "
"catch block, return address: {}\n",
getNativeFunctionName(helperAddr),
exceptionFromUnwindException(exn)->what(),
rip);
return false;
}
FTRACE(1, "installing catch trace {} for call {} with tv {}, "
"returning _URC_INSTALL_CONTEXT\n",
catchTrace, rip, unwinder_tv.pretty());
// In theory the unwind api will let us set registers in the frame
// before executing our landing pad. In practice, trying to use
// their recommended scratch registers results in a SEGV inside
// _Unwind_SetGR, so we pass things to the handler using the
// RDS. This also simplifies the handler code because it doesn't
// have to worry about saving its arguments somewhere while
// executing the exit trace.
unwindRdsInfo->unwinderScratch = (int64_t)exn;
unwindRdsInfo->doSideExit = do_side_exit;
if (do_side_exit) {
unwindRdsInfo->unwinderTv = unwinder_tv;
}
_Unwind_SetIP(ctx, (uint64_t)catchTrace);
tl_regState = VMRegState::DIRTY;
return true;
}
// XED callback function to get a symbol from an address
static int addressToSymbol(xed_uint64_t address,
char* symbolBuffer,
xed_uint32_t bufferLength,
xed_uint64_t* offset,
void* context) {
auto name = boost::trim_copy(getNativeFunctionName((void*)address));
if (boost::starts_with(name, "0x")) {
return 0;
}
auto pos = name.find_first_of('(');
auto copyLength = pos != std::string::npos
? std::min(pos, size_t(bufferLength - 1))
: bufferLength - 1;
strncpy(symbolBuffer, name.c_str(), copyLength);
symbolBuffer[copyLength] = '\0';
*offset = 0;
return 1;
}
