/// computePCBegin - return the address of FDE's pc
/// @ref binutils gold: ehframe.cc:222
uint32_t EhFrameHdr::computePCBegin(const EhFrame::FDE& pFDE,
const MemoryRegion& pEhFrameRegion)
{
uint8_t fde_encoding = pFDE.getCIE().getFDEEncode();
unsigned int eh_value = fde_encoding & 0x7;
// check the size to read in
if (eh_value == llvm::dwarf::DW_EH_PE_absptr) {
eh_value = DW_EH_PE_udata4;
}
size_t pc_size = 0x0;
switch (eh_value) {
case DW_EH_PE_udata2:
pc_size = 2;
break;
case DW_EH_PE_udata4:
pc_size = 4;
break;
case DW_EH_PE_udata8:
pc_size = 8;
break;
default:
// TODO
break;
}
SizeTraits<32>::Address pc = 0x0;
const uint8_t* offset = (const uint8_t*) pEhFrameRegion.start() +
pFDE.getOffset() +
pFDE.getDataStart();
std::memcpy(&pc, offset, pc_size);
// adjust the signed value
bool is_signed = (fde_encoding & llvm::dwarf::DW_EH_PE_signed) != 0x0;
if (DW_EH_PE_udata2 == eh_value && is_signed)
pc = (pc ^ 0x8000) - 0x8000;
// handle eh application
switch (fde_encoding & 0x70)
{
case DW_EH_PE_absptr:
break;
case DW_EH_PE_pcrel:
pc += m_EhFrame.addr() + pFDE.getOffset() + pFDE.getDataStart();
break;
case DW_EH_PE_datarel:
// TODO
break;
default:
// TODO
break;
}
return pc;
}
void EhFrame::addFDE(EhFrame::FDE& pFDE, bool pAlsoAddFragment)
{
pFDE.getCIE().add(pFDE);
if (pAlsoAddFragment)
addFragment(pFDE);
}