Operation

CheckCapabilitiesEnabled(); Capability base; Capability data; Capability target; if n == 31 then CheckSPAlignment(); base = CSP[]; else base = C[n]; boolean wb_unknown = FALSE; integer linkoffset = 4; Capability link; if IsInC64() then linkoffset = linkoffset + 1; link = CapAdd(PCC[], linkoffset); if CCTLR[].SBL == '1' then link = CapSetObjectType(link, CAP_SEAL_TYPE_RB); if t == 30 then Constraint c = ConstrainUnpredictable(Unpredictable_LINKTRANSFEROVERLAPLD); assert c IN {Constraint_UNKNOWN, Constraint_UNDEF, Constraint_NOP}; case c of when Constraint_UNKNOWN wb_unknown = TRUE; // writeback is UNKNOWN when Constraint_UNDEF UNDEFINED; when Constraint_NOP EndOfInstruction(); if t == 29 then if CapIsTagSet(base) && CapIsSealed(base) && CapGetObjectType(base) == CAP_SEAL_TYPE_LPB then base = CapUnseal(base); VirtualAddress vabase = VAFromCapability(base); bits(64) addr = VAddress(vabase); VACheckAddress(vabase, addr, CAPABILITY_DBYTES*2, CAP_PERM_LOAD, AccType_NORMAL); data = MemC[addr, AccType_NORMAL]; target = MemC[addr + CAPABILITY_DBYTES, AccType_NORMAL]; data = CapSquashPostLoadCap(data, vabase); target = CapSquashPostLoadCap(target, vabase); C[30] = link; C[29] = data; else VirtualAddress vabase = VAFromCapability(base); bits(64) addr = VAddress(vabase); VACheckAddress(vabase, addr, CAPABILITY_DBYTES*2, CAP_PERM_LOAD, AccType_NORMAL); data = MemC[addr, AccType_NORMAL]; target = MemC[addr + CAPABILITY_DBYTES, AccType_NORMAL]; data = CapSquashPostLoadCap(data, vabase); target = CapSquashPostLoadCap(target, vabase); if wb_unknown then C[30] = Capability UNKNOWN; C[t] = Capability UNKNOWN; else C[30] = link; C[t] = data; if !IsInRestricted() && !CapCheckPermissions(target, CAP_PERM_EXECUTIVE) then target = CapWithTagClear(target); if CapIsTagSet(target) && CapIsSealed(target) && CapGetObjectType(target) == CAP_SEAL_TYPE_RB then target = CapUnseal(target); BranchXToCapability(target, branch_type);