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AArch32 Functions.System Pseudocode
Library pseudocode for aarch32/functions/system/AArch32.ExceptionReturn
// AArch32.ExceptionReturn() // ========================= AArch32.ExceptionReturn(bits(32) new_pc, bits(32) spsr) SynchronizeContext(); // Attempts to change to an illegal mode or state will invoke the Illegal Execution state // mechanism SetPSTATEFromPSR(spsr); ClearExclusiveLocal(ProcessorID()); SendEventLocal(); if PSTATE.IL == '1' then // If the exception return is illegal, PC[1:0] are UNKNOWN new_pc<1:0> = bits(2) UNKNOWN; else // LR[1:0] or LR[0] are treated as being 0, depending on the target instruction set state if PSTATE.T == '1' then new_pc<0> = '0'; // T32 else new_pc<1:0> = '00'; // A32 BranchTo(new_pc, BranchType_ERET);
Library pseudocode for aarch32/functions/system/AArch32.ExecutingATS1xPInstr
// AArch32.ExecutingATS1xPInstr() // ============================== // Return TRUE if current instruction is AT S1CPR/WP boolean AArch32.ExecutingATS1xPInstr() if !HavePrivATExt() then return FALSE; instr = ThisInstr(); if instr<24+:4> == '1110' && instr<8+:4> == '1110' then op1 = instr<21+:3>; CRn = instr<16+:4>; CRm = instr<0+:4>; op2 = instr<5+:3>; return (op1 == '000' && CRn == '0111' && CRm == '1001' && op2 IN {'000','001'}); else return FALSE;
Library pseudocode for aarch32/functions/system/AArch32.ExecutingCP10or11Instr
// AArch32.ExecutingCP10or11Instr() // ================================ boolean AArch32.ExecutingCP10or11Instr() instr = ThisInstr(); instr_set = CurrentInstrSet(); assert instr_set IN {InstrSet_A32, InstrSet_T32}; if instr_set == InstrSet_A32 then return ((instr<27:24> == '1110' || instr<27:25> == '110') && instr<11:8> == '101x'); else // InstrSet_T32 return (instr<31:28> == '111x' && (instr<27:24> == '1110' || instr<27:25> == '110') && instr<11:8> == '101x');
Library pseudocode for aarch32/functions/system/AArch32.ExecutingLSMInstr
// AArch32.ExecutingLSMInstr() // =========================== // Returns TRUE if processor is executing a Load/Store Multiple instruction boolean AArch32.ExecutingLSMInstr() instr = ThisInstr(); instr_set = CurrentInstrSet(); assert instr_set IN {InstrSet_A32, InstrSet_T32}; if instr_set == InstrSet_A32 then return (instr<28+:4> != '1111' && instr<25+:3> == '100'); else // InstrSet_T32 if ThisInstrLength() == 16 then return (instr<12+:4> == '1100'); else return (instr<25+:7> == '1110100' && instr<22> == '0');
Library pseudocode for aarch32/functions/system/AArch32.ITAdvance
// AArch32.ITAdvance() // =================== AArch32.ITAdvance() if PSTATE.IT<2:0> == '000' then PSTATE.IT = '00000000'; else PSTATE.IT<4:0> = LSL(PSTATE.IT<4:0>, 1); return;
Library pseudocode for aarch32/functions/system/AArch32.SysRegRead
// Read from a 32-bit AArch32 System register and return the register's contents. bits(32) AArch32.SysRegRead(integer cp_num, bits(32) instr);
Library pseudocode for aarch32/functions/system/AArch32.SysRegRead64
// Read from a 64-bit AArch32 System register and return the register's contents. bits(64) AArch32.SysRegRead64(integer cp_num, bits(32) instr);
Library pseudocode for aarch32/functions/system/AArch32.SysRegReadCanWriteAPSR
// AArch32.SysRegReadCanWriteAPSR() // ================================ // Determines whether the AArch32 System register read instruction can write to APSR flags. boolean AArch32.SysRegReadCanWriteAPSR(integer cp_num, bits(32) instr) assert UsingAArch32(); assert (cp_num IN {14,15}); assert cp_num == UInt(instr<11:8>); opc1 = UInt(instr<23:21>); opc2 = UInt(instr<7:5>); CRn = UInt(instr<19:16>); CRm = UInt(instr<3:0>); if cp_num == 14 && opc1 == 0 && CRn == 0 && CRm == 1 && opc2 == 0 then // DBGDSCRint return TRUE; return FALSE;
Library pseudocode for aarch32/functions/system/AArch32.SysRegWrite
// Write to a 32-bit AArch32 System register. AArch32.SysRegWrite(integer cp_num, bits(32) instr, bits(32) val);
Library pseudocode for aarch32/functions/system/AArch32.SysRegWrite64
// Write to a 64-bit AArch32 System register. AArch32.SysRegWrite64(integer cp_num, bits(32) instr, bits(64) val);
Library pseudocode for aarch32/functions/system/AArch32.WriteMode
// AArch32.WriteMode() // =================== // Function for dealing with writes to PSTATE.M from AArch32 state only. // This ensures that PSTATE.EL and PSTATE.SP are always valid. AArch32.WriteMode(bits(5) mode) (valid,el) = ELFromM32(mode); assert valid; PSTATE.M = mode; PSTATE.EL = el; PSTATE.nRW = '1'; PSTATE.SP = (if mode IN {M32_User,M32_System} then '0' else '1'); return;
Library pseudocode for aarch32/functions/system/AArch32.WriteModeByInstr
// AArch32.WriteModeByInstr() // ========================== // Function for dealing with writes to PSTATE.M from an AArch32 instruction, and ensuring that // illegal state changes are correctly flagged in PSTATE.IL. AArch32.WriteModeByInstr(bits(5) mode) (valid,el) = ELFromM32(mode); // 'valid' is set to FALSE if' mode' is invalid for this implementation or the current value // of SCR.NS/SCR_EL3.NS. Additionally, it is illegal for an instruction to write 'mode' to // PSTATE.EL if it would result in any of: // * A change to a mode that would cause entry to a higher Exception level. if UInt(el) > UInt(PSTATE.EL) then valid = FALSE; // * A change to or from Hyp mode. if (PSTATE.M == M32_Hyp || mode == M32_Hyp) && PSTATE.M != mode then valid = FALSE; // * When EL2 is implemented, the value of HCR.TGE is '1', a change to a Non-secure EL1 mode. if PSTATE.M == M32_Monitor && HaveEL(EL2) && el == EL1 && SCR.NS == '1' && HCR.TGE == '1' then valid = FALSE; if !valid then PSTATE.IL = '1'; else AArch32.WriteMode(mode);
Library pseudocode for aarch32/functions/system/BadMode
// BadMode() // ========= boolean BadMode(bits(5) mode) // Return TRUE if 'mode' encodes a mode that is not valid for this implementation case mode of when M32_Monitor valid = HaveAArch32EL(EL3); when M32_Hyp valid = HaveAArch32EL(EL2); when M32_FIQ, M32_IRQ, M32_Svc, M32_Abort, M32_Undef, M32_System // If EL3 is implemented and using AArch32, then these modes are EL3 modes in Secure // state, and EL1 modes in Non-secure state. If EL3 is not implemented or is using // AArch64, then these modes are EL1 modes. // Therefore it is sufficient to test this implementation supports EL1 using AArch32. valid = HaveAArch32EL(EL1); when M32_User valid = HaveAArch32EL(EL0); otherwise valid = FALSE; // Passed an illegal mode value return !valid;
Library pseudocode for aarch32/functions/system/BankedRegisterAccessValid
// BankedRegisterAccessValid() // =========================== // Checks for MRS (Banked register) or MSR (Banked register) accesses to registers // other than the SPSRs that are invalid. This includes ELR_hyp accesses. BankedRegisterAccessValid(bits(5) SYSm, bits(5) mode) case SYSm of when '000xx', '00100' // R8_usr to R12_usr if mode != M32_FIQ then UNPREDICTABLE; when '00101' // SP_usr if mode == M32_System then UNPREDICTABLE; when '00110' // LR_usr if mode IN {M32_Hyp,M32_System} then UNPREDICTABLE; when '010xx', '0110x', '01110' // R8_fiq to R12_fiq, SP_fiq, LR_fiq if mode == M32_FIQ then UNPREDICTABLE; when '1000x' // LR_irq, SP_irq if mode == M32_IRQ then UNPREDICTABLE; when '1001x' // LR_svc, SP_svc if mode == M32_Svc then UNPREDICTABLE; when '1010x' // LR_abt, SP_abt if mode == M32_Abort then UNPREDICTABLE; when '1011x' // LR_und, SP_und if mode == M32_Undef then UNPREDICTABLE; when '1110x' // LR_mon, SP_mon if !HaveEL(EL3) || !IsSecure() || mode == M32_Monitor then UNPREDICTABLE; when '11110' // ELR_hyp, only from Monitor or Hyp mode if !HaveEL(EL2) || !(mode IN {M32_Monitor,M32_Hyp}) then UNPREDICTABLE; when '11111' // SP_hyp, only from Monitor mode if !HaveEL(EL2) || mode != M32_Monitor then UNPREDICTABLE; otherwise UNPREDICTABLE; return;
Library pseudocode for aarch32/functions/system/CPSRWriteByInstr
// CPSRWriteByInstr() // ================== // Update PSTATE.<N,Z,C,V,Q,GE,E,A,I,F,M> from a CPSR value written by an MSR instruction. CPSRWriteByInstr(bits(32) value, bits(4) bytemask) privileged = PSTATE.EL != EL0; // PSTATE.<A,I,F,M> are not writable at EL0 // Write PSTATE from 'value', ignoring bytes masked by 'bytemask' if bytemask<3> == '1' then PSTATE.<N,Z,C,V,Q> = value<31:27>; // Bits <26:24> are ignored if bytemask<2> == '1' then // Bit <23> is RES0 if privileged then PSTATE.PAN = value<22>; // Bits <20> are RES0 PSTATE.GE = value<19:16>; PSTATE.DIT = value<21>; if bytemask<1> == '1' then // Bits <15:10> are RES0 PSTATE.E = value<9>; // PSTATE.E is writable at EL0 if privileged then PSTATE.A = value<8>; if bytemask<0> == '1' then if privileged then PSTATE.<I,F> = value<7:6>; // Bit <5> is RES0 // AArch32.WriteModeByInstr() sets PSTATE.IL to 1 if this is an illegal mode change. AArch32.WriteModeByInstr(value<4:0>); return;
Library pseudocode for aarch32/functions/system/ConditionPassed
// ConditionPassed() // ================= boolean ConditionPassed() return ConditionHolds(AArch32.CurrentCond());
Library pseudocode for aarch32/functions/system/InITBlock
// InITBlock() // =========== boolean InITBlock() if CurrentInstrSet() == InstrSet_T32 then return PSTATE.IT<3:0> != '0000'; else return FALSE;
Library pseudocode for aarch32/functions/system/LastInITBlock
// LastInITBlock() // =============== boolean LastInITBlock() return (PSTATE.IT<3:0> == '1000');
Library pseudocode for aarch32/functions/system/SPSRWriteByInstr
// SPSRWriteByInstr() // ================== SPSRWriteByInstr(bits(32) value, bits(4) bytemask) new_spsr = SPSR[]; if bytemask<3> == '1' then new_spsr<31:24> = value<31:24>; // N,Z,C,V,Q flags, IT[1:0],J bits if bytemask<2> == '1' then new_spsr<23:16> = value<23:16>; // IL bit, GE[3:0] flags if bytemask<1> == '1' then new_spsr<15:8> = value<15:8>; // IT[7:2] bits, E bit, A interrupt mask if bytemask<0> == '1' then new_spsr<7:0> = value<7:0>; // I,F interrupt masks, T bit, Mode bits SPSR[] = new_spsr; // UNPREDICTABLE if User or System mode return;
Library pseudocode for aarch32/functions/system/SPSRaccessValid
// SPSRaccessValid() // ================= // Checks for MRS (Banked register) or MSR (Banked register) accesses to the SPSRs // that are UNPREDICTABLE SPSRaccessValid(bits(5) SYSm, bits(5) mode) case SYSm of when '01110' // SPSR_fiq if mode == M32_FIQ then UNPREDICTABLE; when '10000' // SPSR_irq if mode == M32_IRQ then UNPREDICTABLE; when '10010' // SPSR_svc if mode == M32_Svc then UNPREDICTABLE; when '10100' // SPSR_abt if mode == M32_Abort then UNPREDICTABLE; when '10110' // SPSR_und if mode == M32_Undef then UNPREDICTABLE; when '11100' // SPSR_mon if !HaveEL(EL3) || mode == M32_Monitor || !IsSecure() then UNPREDICTABLE; when '11110' // SPSR_hyp if !HaveEL(EL2) || mode != M32_Monitor then UNPREDICTABLE; otherwise UNPREDICTABLE; return;
Library pseudocode for aarch32/functions/system/SelectInstrSet
// SelectInstrSet() // ================ SelectInstrSet(InstrSet iset) assert CurrentInstrSet() IN {InstrSet_A32, InstrSet_T32}; assert iset IN {InstrSet_A32, InstrSet_T32}; PSTATE.T = if iset == InstrSet_A32 then '0' else '1'; return;