Eccelerators.RiscV

tests/Rv32TrapEngineTest.lvt

namespace Eccelerators.RiscV.Tests

using Eccelerators.RiscV.Sequential
using Eccelerators.RiscV.Storage
using Eccelerators.RiscV.Presets
using Eccelerators.RiscV.Machine

/**
 * Instruction-level checks observe committed writes independently of CPU storage.
 * Every wait is bounded so a stalled bus or controller fails the test.
 */
@Test
component Rv32TrapEngineTest
{
	// Owned platform, explicit execution composition and architectural scoreboard.
	fetch: RvFetchRom<512, 9>
	loadStore: DelayedWordDevice
	core: Rv32SequentialEngine<0, true>
	registers: Rv32RegisterBank
	baseDecoder: Rv32iZmmulDecoder
	csrDecoder: Rv32ZicsrDecoder
	decoder: Rv32MachineDecoder
	integer: Rv32iIntegerUnit
	multiplier: Rv32DspMultiplier
	csrs: Rv32MachineCsrs
	observed: uint[32]
	retireCount: uint
	clearObservation: bool
	cycles: uint
	trapCount: uint
	lastTrapPc: uint
	lastTrapCause: uint
	lastTrapValue: uint
	tracePc: uint[512]
	traceWord: uint[512]
	traceRd: uint[512]
	traceValue: uint[512]

	/**
	 * Creates distinct instruction and data providers in the test clock context.
	 */
	new()
	{
		fetch = new RvFetchRom<512, 9>()
		loadStore = new DelayedWordDevice()
		registers = new Rv32RegisterBank()
		baseDecoder = new Rv32iZmmulDecoder()
		csrDecoder = new Rv32ZicsrDecoder(baseDecoder)
		decoder = new Rv32MachineDecoder(csrDecoder)
		integer = new Rv32iIntegerUnit()
		multiplier = new Rv32DspMultiplier()
		csrs = new Rv32MachineCsrs()
		core = new Rv32SequentialEngine<0, true>(registers, fetch, loadStore, decoder, integer, multiplier, csrs)
	}

	/**
	 * Samples retirement every clock; tests never read a CPU-private register array.
	 */
	process Observe()
	{
		state {
			cycles++

			assert !(core.trapped == 0b1 && core.retired == 0b1)

			if (clearObservation) {
				trapCount = 0
			} elif (core.trapped == 0b1) {
				trapCount++
				lastTrapPc = core.trapPc as uint
				lastTrapCause = core.trapCause as uint
				lastTrapValue = core.trapValue as uint
			}

			if (clearObservation) {
				retireCount = 0
			} elif (core.retired == 0b1) {
				assert retireCount < 512
				tracePc[retireCount] = core.retiredPc as uint
				traceWord[retireCount] = core.retiredInstruction as uint
				traceRd[retireCount] = core.retiredRd as uint
				traceValue[retireCount] = core.retiredValue as uint
				retireCount++

				if (core.retiredRd != 0) {
					observed[core.retiredRd as uint] = core.retiredValue as uint
				}
			}
		}
	}

	/**
	 * Programs one word with the CPU paused; writes are sampled once.
	 */
	fn Load(index: uint, word: uint)
	{
		state {
			fetch.programWrite = 0b1
			fetch.programIndex = index as logic[9]
			fetch.programData = word as logic[32]
		}

		state {
			fetch.programWrite = 0b0
		}
	}

	/**
	 * Initializes every data location that a vector can read before execution.
	 */
	fn Prepare()
	{
		core.run = 0b0
		Simulation.Wait(40)
		assert core.idle == 0b1
		var ticket = ~core.restartAck
		core.restartRequest = ticket
		var elapsed: uint = 0

		while (core.restartAck != ticket && elapsed < 100) {
			state {
				elapsed++
			}
		}

		assert core.restartAck == ticket
		clearObservation = true
		Simulation.Wait(4)
		clearObservation = false

		loadStore.clear = 0b1
		loadStore.releaseResponse = 0b0
		Simulation.Wait(4)
		loadStore.clear = 0b0

		assert core.idle == 0b1
	}

	/**
	 * Steps one attempt through retirement or trap entry, leaving the handler paused.
	 */
	fn Step()
	{
		core.stepRequest = ~core.stepRequest
		var elapsed: uint = 0

		while (core.stepAck != core.stepRequest && elapsed < 200) {
			state {
				elapsed++
			}
		}

		assert core.stepAck == core.stepRequest
		Simulation.Wait(3)
		assert core.idle == 0b1 && core.halted == 0b0
	}

	/**
	 * Installs a handler that reads saved state, skips one instruction and returns.
	 */
	fn Handler()
	{
		Load(0, 0x10000093)
		Load(1, 0x30509073)
		Load(64, 0x34102573)
		Load(65, 0x342025f3)
		Load(66, 0x34302673)
		Load(67, 0x300026f3)
		Load(68, 0x00450513)
		Load(69, 0x34151073)
		Load(70, 0x30200073)
	}

	/**
	 * Checks precise exception state, no memory effects, MRET and retirement count.
	 */
	fn CheckFault(word: uint, cause: uint, value: uint)
	{
		Prepare()
		Handler()
		Load(2, word)
		Load(3, 0xb0202a73)
		Load(4, 0x30002af3)
		Load(5, 0x00028b13)
		loadStore.releaseResponse = 0b1
		Step()
		Step()
		Step()
		assert trapCount == 1 && retireCount == 2
		assert core.pc == 256 && lastTrapPc == 8
		assert lastTrapCause == cause && lastTrapValue == value
		assert loadStore.reads == 0 && loadStore.writes == 0
		Simulation.Wait(30)
		assert trapCount == 1 && retireCount == 2 && core.pc == 256

		for (var index = 0; index < 7; index++) {
			Step()
		}

		assert trapCount == 1 && retireCount == 9 && core.pc == 12
		assert observed[10] == 12 && observed[11] == cause
		assert observed[12] == value && observed[13] == 0x1800
		Step()
		assert observed[20] == 9
		Step()
		assert observed[21] == 0x1880
		Step()
		assert observed[22] == 0
	}

	/**
	 * Checks EnvironmentCall with an actual software handler and return.
	 */
	@Test
	fn EnvironmentCall()
	{
		CheckFault(0x00000073, 11, 0x00000000)
	}

	/**
	 * Checks Breakpoint with an actual software handler and return.
	 */
	@Test
	fn Breakpoint()
	{
		CheckFault(0x00100073, 3, 0x00000008)
	}

	/**
	 * Checks IllegalInstruction with an actual software handler and return.
	 */
	@Test
	fn IllegalInstruction()
	{
		CheckFault(0xffffffff, 2, 0xffffffff)
	}

	/**
	 * Checks IllegalCsr with an actual software handler and return.
	 */
	@Test
	fn IllegalCsr()
	{
		CheckFault(0x777022f3, 2, 0x777022f3)
	}

	/**
	 * Checks ReadOnlyCsr with an actual software handler and return.
	 */
	@Test
	fn ReadOnlyCsr()
	{
		CheckFault(0xf111d2f3, 2, 0xf111d2f3)
	}

	/**
	 * Checks JumpAlignment with an actual software handler and return.
	 */
	@Test
	fn JumpAlignment()
	{
		CheckFault(0x002002ef, 0, 0x0000000a)
	}

	/**
	 * Checks IndirectJumpAlignment with an actual software handler and return.
	 */
	@Test
	fn IndirectJumpAlignment()
	{
		CheckFault(0x002002e7, 0, 0x00000002)
	}

	/**
	 * Checks TakenBranchAlignment with an actual software handler and return.
	 */
	@Test
	fn TakenBranchAlignment()
	{
		CheckFault(0x00000163, 0, 0x0000000a)
	}

	/**
	 * Checks LoadAlignment with an actual software handler and return.
	 */
	@Test
	fn LoadAlignment()
	{
		CheckFault(0x00202283, 4, 0x00000002)
	}

	/**
	 * Checks StoreAlignment with an actual software handler and return.
	 */
	@Test
	fn StoreAlignment()
	{
		CheckFault(0x00102123, 6, 0x00000002)
	}

	/**
	 * Checks LoadAccess with an actual software handler and return.
	 */
	@Test
	fn LoadAccess()
	{
		CheckFault(0x00402283, 5, 0x00000004)
	}

	/**
	 * Checks LoadAccessToZero with an actual software handler and return.
	 */
	@Test
	fn LoadAccessToZero()
	{
		CheckFault(0x00402003, 5, 0x00000004)
	}

	/**
	 * Checks StoreAccess with an actual software handler and return.
	 */
	@Test
	fn StoreAccess()
	{
		CheckFault(0x00102223, 7, 0x00000004)
	}

	/**
	 * Saves enabled MIE, clears it during entry and restores it on MRET.
	 */
	@Test
	fn InterruptEnableStack()
	{
		Prepare()
		Handler()
		Load(2, 0x30046073)
		Load(3, 0x00000073)
		Load(4, 0x30002a73)
		Step()
		Step()
		Step()
		Step()
		assert trapCount == 1 && retireCount == 3 && lastTrapPc == 12

		for (var index = 0; index < 7; index++) {
			Step()
		}

		assert observed[13] == 0x1880 && core.pc == 16
		Step()
		assert observed[20] == 0x1888
	}

	/**
	 * A failed fetch records the target PC; the preceding JALR still retires.
	 */
	@Test
	fn FetchAccess()
	{
		Prepare()
		Handler()
		Load(2, 0x7ff00293)
		Load(3, 0x00128067)
		Step()
		Step()
		Step()
		Step()
		assert retireCount == 4 && core.pc == 2048
		Step()
		assert trapCount == 1 && retireCount == 4 && core.pc == 256
		assert lastTrapPc == 2048 && lastTrapCause == 1 && lastTrapValue == 2048
		Step()
		Step()
		Step()
		assert observed[10] == 2048 && observed[11] == 1 && observed[12] == 2048
	}

	/**
	 * An exception inside a handler overwrites the machine save registers normally.
	 */
	@Test
	fn HandlerException()
	{
		Prepare()
		Handler()
		Load(2, 0x00000073)
		Load(64, 0x00100073)
		Step()
		Step()
		Step()
		Step()
		assert trapCount == 2 && retireCount == 2 && core.pc == 256
		assert lastTrapPc == 256 && lastTrapCause == 3 && lastTrapValue == 256
		Load(64, 0x34102573)
		Step()
		assert observed[10] == 256
	}

	/**
	 * Unmapped handlers trap again; step remains bounded and restart can recover.
	 */
	@Test
	fn HandlerFetchFault()
	{
		Prepare()
		Load(0, 0x000010b7)
		Load(1, 0x30509073)
		Load(2, 0x00000073)
		Step()
		Step()
		Step()
		assert core.pc == 4096 && trapCount == 1
		Step()
		assert core.pc == 4096 && trapCount == 2 && retireCount == 2
		assert lastTrapPc == 4096 && lastTrapCause == 1 && lastTrapValue == 4096
		var ticket = ~core.restartAck
		core.restartRequest = ticket
		Simulation.Wait(60)
		assert core.restartAck == ticket && core.pc == 0 && core.idle == 0b1
	}

	/**
	 * An untaken branch ignores target alignment and MRET uses normalized mepc.
	 */
	@Test
	fn ReturnAndUntakenBranch()
	{
		Prepare()
		Load(0, 0x00001163)
		Load(1, 0x34115073)
		Load(2, 0x30200073)
		Step()
		Step()
		Step()
		assert core.pc == 0 && retireCount == 3 && trapCount == 0
	}

	/**
	 * Delayed errors drain before entry; pending restart clears the resulting state.
	 */
	@Test
	fn DelayedFaultRestart()
	{
		Prepare()
		Handler()
		Load(2, 0x00102223)
		Step()
		Step()
		core.run = 0b1
		var elapsed: uint = 0

		while (loadStore.accepted == 0b0 && elapsed < 200) {
			state {
				elapsed++
			}
		}

		assert loadStore.accepted == 0b1
		core.run = 0b0
		var ticket = ~core.restartAck
		core.restartRequest = ticket
		Simulation.Wait(20)
		assert core.restartAck != ticket && trapCount == 0 && retireCount == 2
		assert loadStore.writes == 0
		loadStore.releaseResponse = 0b1
		Simulation.Wait(80)
		assert core.restartAck == ticket && core.pc == 0 && core.idle == 0b1
		assert trapCount == 1 && retireCount == 2 && loadStore.writes == 0
		Load(0, 0x34102573)
		Load(1, 0xb02025f3)
		Step()
		Step()
		assert observed[10] == 0 && observed[11] == 1
	}
}