Load Pair of capabilities and Branch calculates an address from the source Capability register, loads from memory two capabilities, a target capability and a data capability. The instruction writes the data capability to the destination Capability register and branches to the target capability.
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | Cn | Ct | ||||||||
| opc<1> | opc<0> | ||||||||||||||||||||||||||||||
integer t = UInt(Ct); integer n = UInt(Cn); BranchType branch_type = BranchType_INDIR;
| <Ct> |
Is the capability name of the transfer register, encoded in the "Ct" field. |
| <Cn|CSP> |
Is the capability name of the base register or stack pointer, encoded in the "Cn" field. |
CheckCapabilitiesEnabled(); Capability base; Capability data; Capability target; if n == 31 then CheckSPAlignment(); base = CSP[]; else base = C[n]; 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[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); 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);
Internal version only: isa v32.13, AdvSIMD v29.04, pseudocode morello-2022-01_rc2, capabilities morello-2022-01_rc2 ; Build timestamp: 2022-01-11T11:23
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