feat: invoke host call (#217)

Author: danielvladco

internal/polkavm/host_call/common.go

@@ -79,6 +79,15 @@ const (
 	OK   Code = 0
 )
 
+// Inner pvm invocations have their own set of result codes
+const (
+	HALT  = 0 // The invocation completed and halted normally.
+	PANIC = 1 // The invocation completed with a panic.
+	FAULT = 2 // The invocation completed with a page fault.
+	HOST  = 3 // The invocation completed with a host-call fault.
+	OOG   = 4 // The invocation completed by running out of gas.
+)
+
 func (r Code) String() string {
 	switch r {
 	case NONE:
@@ -107,7 +116,7 @@ func (r Code) String() string {
 	return "unknown"
 }
 
-func readNumber[U interface{ ~uint32 | ~uint64 }](mem Memory, addr uint32, length int) (u U, err error) {
+func readNumber[U interface{ ~uint32 | ~uint64 | ~int64 }](mem Memory, addr uint32, length int) (u U, err error) {
 	b := make([]byte, length)
 	if err = mem.Read(addr, b); err != nil {
 		return

internal/polkavm/host_call/refine_functions.go

@@ -1,15 +1,20 @@
 package host_call
 
 import (
+	"bytes"
+	"errors"
+	"log"
 	"math"
 
 	"github.com/eigerco/strawberry/internal/block"
 	"github.com/eigerco/strawberry/internal/common"
 	"github.com/eigerco/strawberry/internal/crypto"
 	"github.com/eigerco/strawberry/internal/jamtime"
 	. "github.com/eigerco/strawberry/internal/polkavm"
+	"github.com/eigerco/strawberry/internal/polkavm/interpreter"
 	"github.com/eigerco/strawberry/internal/service"
 	"github.com/eigerco/strawberry/internal/work"
+	"github.com/eigerco/strawberry/pkg/serialization/codec/jam"
 )
 
 // HistoricalLookup ΩH(ϱ, ω, µ, (m, e), s, d, t)
@@ -366,7 +371,91 @@ func Invoke(
 	mem Memory,
 	ctxPair RefineContextPair,
 ) (Gas, Registers, Memory, RefineContextPair, error) {
-	return gas, regs, mem, ctxPair, nil
+	if gas < InvokeCost {
+		return gas, regs, mem, ctxPair, ErrOutOfGas
+	}
+	gas -= InvokeCost
+	// let [n, o] = ω7,8
+	pvmKey, addr := regs[A0], regs[A1]
+
+	// let (g, w) = (g, w) ∶ E8(g) ⌢ E#8(w) = μo⋅⋅⋅+112 if No⋅⋅⋅+112 ⊂ V∗μ
+	invokeGas, err := readNumber[Gas](mem, uint32(addr), 8)
+	if err != nil {
+		return gas, withCode(regs, OOB), mem, ctxPair, nil
+	}
+	var invokeRegs Registers // w
+	for i := range 13 {
+		invokeReg, err := readNumber[uint64](mem, uint32(addr+(uint64(i+1)*8)), 8)
+		if err != nil {
+			return gas, withCode(regs, OOB), mem, ctxPair, nil
+		}
+		invokeRegs[i] = invokeReg
+	}
+
+	// let (c, i′, g′, w′, u′) = Ψ(m[n]p, m[n]i, g, w, m[n]u)
+	pvm, ok := ctxPair.IntegratedPVMMap[pvmKey]
+	if !ok { // if n ∉ m
+		return gas, withCode(regs, WHO), mem, ctxPair, nil // (WHO, ω8, μ, m)
+	}
+	updateIntegratedPVM := func(isHostCall bool, resultInstr uint32, resultMem Memory) {
+		pvm.Ram = resultMem
+		if isHostCall {
+			// m*[n]i = i′ + 1 if c ∈ {̵h} × NR
+			pvm.InstructionCounter = resultInstr + 1
+		} else {
+			// m*[n]i = i′
+			pvm.InstructionCounter = resultInstr
+		}
+		ctxPair.IntegratedPVMMap[pvmKey] = pvm
+	}
+
+	// we only parse the code and jump table as we are not expected to invoke a full program
+	program := &Program{}
+	if err := ParseCodeAndJumpTable(uint32(len(pvm.Code)), NewReader(bytes.NewReader(pvm.Code)), program); err != nil {
+		return gas, withCode(regs, PANIC), mem, ctxPair, nil
+	}
+
+	log.Println("invokeGas", invokeGas)
+	log.Println("invokeRegs", invokeRegs)
+	resultInstr, resultGas, resultRegs, resultMem, hostCall, invokeErr := interpreter.Invoke(program, nil, pvm.InstructionCounter, invokeGas, invokeRegs, pvm.Ram)
+
+	if bb, err := jam.Marshal([14]uint64(append([]uint64{uint64(resultGas)}, resultRegs[:]...))); err != nil {
+		return gas, withCode(regs, OOB), mem, ctxPair, nil // (OOB, ω8, μ, m)
+	} else if err := mem.Write(uint32(addr), bb); err != nil {
+		return gas, withCode(regs, OOB), mem, ctxPair, nil // (OOB, ω8, μ, m)
+	}
+	if invokeErr != nil {
+		if errors.Is(invokeErr, ErrOutOfGas) {
+			updateIntegratedPVM(false, resultInstr, resultMem)
+			return gas, withCode(regs, OOG), mem, ctxPair, nil // (OOG, ω8, μ*, m*)
+		}
+		if errors.Is(invokeErr, ErrHalt) {
+			updateIntegratedPVM(false, resultInstr, resultMem)
+			return gas, withCode(regs, HALT), mem, ctxPair, nil // (HALT, ω8, μ*, m*)
+		}
+		if errors.Is(invokeErr, ErrHostCall) {
+			updateIntegratedPVM(true, resultInstr, resultMem)
+			regs[A1] = uint64(hostCall)
+			return gas, withCode(regs, HOST), mem, ctxPair, nil // (HOST, h, μ*, m*)
+		}
+		pageFault := &ErrPageFault{}
+		if errors.As(invokeErr, &pageFault) {
+			updateIntegratedPVM(false, resultInstr, resultMem)
+			regs[A1] = uint64(pageFault.Address)
+			return gas, withCode(regs, FAULT), mem, ctxPair, nil
+		}
+		panicErr := &ErrPanic{}
+		if errors.As(invokeErr, &panicErr) {
+			updateIntegratedPVM(false, resultInstr, resultMem)
+			return gas, withCode(regs, PANIC), mem, ctxPair, nil
+		}
+
+		// must never occur
+		panic(invokeErr)
+	}
+
+	updateIntegratedPVM(false, resultInstr, resultMem)
+	return gas, withCode(regs, HALT), mem, ctxPair, nil // (HALT, ω8, μ*, m*)
 }
 
 // Expunge ΩX(ϱ, ω, µ, (m, e))

internal/polkavm/host_call/refine_functions_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/eigerco/strawberry/internal/polkavm/host_call"
 	"github.com/eigerco/strawberry/internal/polkavm/interpreter"
 	"github.com/eigerco/strawberry/internal/service"
+	"github.com/eigerco/strawberry/pkg/serialization/codec/jam"
 )
 
 var initialGas = uint64(100)
@@ -603,6 +604,103 @@ func TestVoid(t *testing.T) {
 	assert.Equal(t, expectedGasRemaining, gasRemaining)
 }
 
+func TestInvoke(t *testing.T) {
+	pp := &polkavm.Program{
+		Instructions: []polkavm.Instruction{
+			{Opcode: polkavm.Ecalli, Imm: []uint32{0}, Offset: 0, Length: 1},
+			{Opcode: polkavm.JumpIndirect, Imm: []uint32{0}, Reg: []polkavm.Reg{polkavm.RA}, Offset: 1, Length: 2},
+		},
+	}
+
+	memoryMap, err := polkavm.NewMemoryMap(0, 128*1024, 0, 0)
+	require.NoError(t, err)
+
+	mem := memoryMap.NewMemory(nil, nil, nil)
+
+	bb, err := jam.Marshal([14]uint64{
+		10000, // gas
+		0,     // regs
+		0,
+		0,
+		0,
+		0,
+		0,
+		0,
+		1,
+		2,
+		0,
+		0,
+		0,
+		0,
+	})
+	require.NoError(t, err)
+
+	addr := memoryMap.RWDataAddress
+	if err := mem.Write(addr, bb); err != nil {
+		t.Fatal(err)
+	}
+
+	pvmKey := uint64(0)
+
+	ctxPair := polkavm.RefineContextPair{
+		IntegratedPVMMap: map[uint64]polkavm.IntegratedPVM{pvmKey: {
+			Code:               addInstrProgram,
+			Ram:                polkavm.Memory{}, // we don't use memory in tests yet
+			InstructionCounter: 0,
+		}},
+	}
+
+	initialRegs := polkavm.Registers{
+		polkavm.RA: polkavm.VmAddressReturnToHost,
+		polkavm.SP: uint64(memoryMap.StackAddressHigh),
+		polkavm.A0: pvmKey,
+		polkavm.A1: uint64(addr),
+	}
+
+	hostCall := func(hc uint32, gasCounter polkavm.Gas, regs polkavm.Registers,
+		mm polkavm.Memory, x struct{},
+	) (polkavm.Gas, polkavm.Registers, polkavm.Memory, struct{}, error) {
+		gasOut, regsOut, memOut, ctxOut, err := host_call.Invoke(gasCounter, regs, mm, ctxPair)
+		require.NoError(t, err)
+		ctxPair = ctxOut
+		return gasOut, regsOut, memOut, x, err
+	}
+
+	gasRemaining, regsOut, _, _, err := interpreter.InvokeHostCall(
+		pp,
+		memoryMap,
+		0,
+		initialGas,
+		initialRegs,
+		mem,
+		hostCall,
+		struct{}{},
+	)
+	require.ErrorIs(t, err, polkavm.ErrHalt)
+
+	assert.Equal(t, uint64(host_call.PANIC), regsOut[polkavm.A0])
+
+	expectedGasRemaining := polkavm.Gas(initialGas) -
+		host_call.InvokeCost -
+		polkavm.GasCosts[polkavm.Ecalli] -
+		polkavm.GasCosts[polkavm.JumpIndirect]
+	assert.Equal(t, expectedGasRemaining, gasRemaining)
+
+	invokeResult := make([]byte, 112)
+	err = mem.Read(addr, invokeResult)
+	require.NoError(t, err)
+
+	invokeGasAndRegs := [14]uint64{}
+	err = jam.Unmarshal(invokeResult, &invokeGasAndRegs)
+	require.NoError(t, err)
+
+	assert.Equal(t, uint32(3), ctxPair.IntegratedPVMMap[pvmKey].InstructionCounter)
+	assert.Equal(t, uint64(9998), invokeGasAndRegs[0])
+	assert.Equal(t, []uint64{0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 0, 0, 0}, invokeGasAndRegs[1:])
+}
+
+var addInstrProgram = []byte{0, 0, 3, 8, 135, 9, 1} // copied from testvectors
+
 func TestExpunge(t *testing.T) {
 	pp := &polkavm.Program{
 		Instructions: []polkavm.Instruction{