Store capability PTE traps don't actually trap

[PeterRugg]

sail-cheri-riscv/src/cheri_pte.sail

Lines 144 to 164 in c93d5ef

	let ptw_sc = if e.CapWrite() == 0b1 then PTW_SC_OK else PTW_SC_TRAP;
	let (succ, ext_ptw') : (bool, ext_ptw) =
	match (base_succ, ac) {
	/* Base translation exceptions take priority over CHERI exceptions */
	(false, _) => (false, init_ext_ptw),
	(true, Read(Cap)) => (true, ext_ptw_lc_join(ext_ptw, ptw_lc)),
	(true, Write(Cap)) => (true, ext_ptw_sc_join(ext_ptw, ptw_sc)),
	(true, ReadWrite(Data, Cap)) => (true, ext_ptw_sc_join(ext_ptw, ptw_sc)),
	(true, ReadWrite(Cap, Data)) => (true, ext_ptw_lc_join(ext_ptw, ptw_lc)),
	(true, ReadWrite(Cap, Cap)) => (true, ext_ptw_sc_join(ext_ptw_lc_join(ext_ptw, ptw_lc), ptw_sc)),
	(true, Read(Data)) => (true, ext_ptw),
	(true, Write(Data)) => (true, ext_ptw),
	(true, ReadWrite(Data, Data)) => (true, ext_ptw),
	(true, Execute()) => (true, ext_ptw)
	};
	if succ
	then PTE_Check_Success(ext_ptw')
	else PTE_Check_Failure(ext_ptw', if ext_ptw'.ptw_sc == PTW_SC_TRAP then EPTWF_CAP_ERR else EPTWF_NO_PERM)

The ptw_sc value has no way of influencing succ, meaning no exception gets thrown.