Add LuaJIT interpreter

This PR contains an interpreter for LuaJIT code, which is primarily
useful in practice due to OpenResty. It has been used in Parca/Polar
Signals since Nov. 2024.

A thorough explanation of the approach used as well as an introduction
to Lua internals can be found at the accompanying blog post:
https://www.polarsignals.com/blog/posts/2024/11/13/lua-unwinding .

Author: umanwizard

Makefile

@@ -30,8 +30,8 @@ endif
 export TARGET_ARCH
 export CGO_ENABLED = 0
 export GOARCH = $(TARGET_ARCH)
-export CC = $(ARCH_PREFIX)-linux-gnu-gcc
-export OBJCOPY = $(ARCH_PREFIX)-linux-gnu-objcopy
+# export CC = $(ARCH_PREFIX)-linux-gnu-gcc
+# export OBJCOPY = $(ARCH_PREFIX)-linux-gnu-objcopy
 
 BRANCH = $(shell git rev-parse --abbrev-ref HEAD | tr -d '-' | tr '[:upper:]' '[:lower:]')
 COMMIT_SHORT_SHA = $(shell git rev-parse --short=8 HEAD)

interpreter/go/go_test.go

@@ -33,7 +33,7 @@ func BenchmarkGolang(b *testing.B) {
 	if err != nil {
 		b.Fatalf("Failed to create hostID: %v", err)
 	}
-	loaderInfo := interpreter.NewLoaderInfo(hostFileID, elfRef)
+	loaderInfo := interpreter.NewLoaderInfo(hostFileID, elfRef, nil)
 	rm := remotememory.NewProcessVirtualMemory(libpfPID)
 
 	b.ReportAllocs()

interpreter/instancestubs.go

@@ -4,11 +4,16 @@
 package interpreter // import "go.opentelemetry.io/ebpf-profiler/interpreter"
 
 import (
+	"unsafe"
+
+	"go.opentelemetry.io/ebpf-profiler/host"
 	"go.opentelemetry.io/ebpf-profiler/libc"
 	"go.opentelemetry.io/ebpf-profiler/libpf"
+	"go.opentelemetry.io/ebpf-profiler/lpm"
 	"go.opentelemetry.io/ebpf-profiler/metrics"
 	"go.opentelemetry.io/ebpf-profiler/process"
 	"go.opentelemetry.io/ebpf-profiler/reporter"
+	"go.opentelemetry.io/ebpf-profiler/util"
 )
 
 // InstanceStubs provides empty implementations of Instance hooks that are
@@ -36,3 +41,32 @@ func (is *InstanceStubs) GetAndResetMetrics() ([]metrics.Metric, error) {
 func (is *InstanceStubs) ReleaseResources() error {
 	return nil
 }
+
+type EbpfHandlerStubs struct{}
+
+func (m *EbpfHandlerStubs) UpdatePidInterpreterMapping(_ libpf.PID,
+	pfx lpm.Prefix, _ uint8, _ host.FileID, _ uint64) error {
+	return nil
+}
+
+func (m *EbpfHandlerStubs) DeletePidInterpreterMapping(_ libpf.PID, _ lpm.Prefix) error {
+	return nil
+}
+
+func (m *EbpfHandlerStubs) CoredumpTest() bool {
+	return false
+}
+
+func (m *EbpfHandlerStubs) UpdateProcData(libpf.InterpreterType, libpf.PID,
+	unsafe.Pointer) error {
+	return nil
+}
+
+func (m *EbpfHandlerStubs) DeleteProcData(libpf.InterpreterType, libpf.PID) error {
+	return nil
+}
+
+func (m *EbpfHandlerStubs) UpdateInterpreterOffsets(ebpfProgIndex uint16, fileID host.FileID,
+	offsetRanges []util.Range) error {
+	return nil
+}

interpreter/loaderinfo.go

@@ -9,6 +9,7 @@ import (
 	"go.opentelemetry.io/ebpf-profiler/host"
 	"go.opentelemetry.io/ebpf-profiler/libpf"
 	"go.opentelemetry.io/ebpf-profiler/libpf/pfelf"
+	sdtypes "go.opentelemetry.io/ebpf-profiler/nativeunwind/stackdeltatypes"
 	"go.opentelemetry.io/ebpf-profiler/util"
 )
 
@@ -19,13 +20,17 @@ type LoaderInfo struct {
 	fileID host.FileID
 	// elfRef provides a cached access to the ELF file.
 	elfRef *pfelf.Reference
+	// deltas contains the stack deltas for the executable.
+	deltas sdtypes.StackDeltaArray
 }
 
 // NewLoaderInfo returns a populated LoaderInfo struct.
-func NewLoaderInfo(fileID host.FileID, elfRef *pfelf.Reference) *LoaderInfo {
+func NewLoaderInfo(fileID host.FileID, elfRef *pfelf.Reference,
+	deltas sdtypes.StackDeltaArray) *LoaderInfo {
 	return &LoaderInfo{
 		fileID: fileID,
 		elfRef: elfRef,
+		deltas: deltas,
 	}
 }
 
@@ -60,3 +65,8 @@ func (i *LoaderInfo) FileID() host.FileID {
 func (i *LoaderInfo) FileName() string {
 	return i.elfRef.FileName()
 }
+
+// Deltas returns the stack deltas for the executable of this LoaderInfo.
+func (i *LoaderInfo) Deltas() sdtypes.StackDeltaArray {
+	return i.deltas
+}

interpreter/luajit/bc.go

@@ -0,0 +1,196 @@
+// Copyright 2024 The Parca Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+package luajit // import "go.opentelemetry.io/ebpf-profiler/interpreter/luajit"
+
+// See https://github.com/openresty/luajit2/blob/7952882d/src/lj_bc.h#L34
+
+var bcMode = []uint16{
+	0x3183, 0x3183, 0x3983, 0x3983, 0x2183, 0x2183, 0x2503, 0x2503,
+	0x2483, 0x2483, 0x2403, 0x2403, 0xb181, 0xb181, 0xb180, 0xb180,
+	0xb303, 0xb303, 0xb181, 0xb181, 0x8181, 0x2981, 0x5499, 0x5c99,
+	0x6499, 0x6c99, 0x7499, 0x5499, 0x5c99, 0x6499, 0x6c99, 0x7499,
+	0x5199, 0x5999, 0x6199, 0x6999, 0x7199, 0x7999, 0x4221, 0xb501,
+	0xb701, 0xb381, 0xb481, 0xb401, 0xb102, 0xb281, 0xb185, 0xb505,
+	0xb485, 0xb405, 0xb684, 0x1601, 0x1301, 0x1581, 0x0501, 0x0d03,
+	0x0199, 0x0519, 0x0319, 0x0199, 0x099b, 0x0d1b, 0x0b1b, 0x0c82,
+	0x099b, 0x4b32, 0x4b32, 0x4b02, 0x4b02, 0x4b32, 0x4b32, 0xb332,
+	0xb682, 0xb302, 0xb304, 0xb304, 0xb304, 0xb682, 0xb682, 0xb682,
+	0xb682, 0xb302, 0xb682, 0xb682, 0xb302, 0xb684, 0xb684, 0xb304,
+	0xb684, 0xb004, 0xb004, 0xb304, 0xb004, 0xb004, 0xb304, 0xb004,
+	0xb004}
+
+func bcOp(ins uint32) uint32 {
+	return ins & 0xff
+}
+
+func bcModeMM(op uint32) uint32 {
+	return uint32(bcMode[op] >> 11)
+}
+
+func bcModeA(op uint32) uint32 {
+	return uint32(bcMode[op] & 7)
+}
+
+func bcA(ins uint32) uint32 {
+	return (ins >> 8) & 0xff
+}
+
+func bcB(ins uint32) uint32 {
+	return ins >> 24
+}
+
+func bcC(ins uint32) uint32 {
+	return (ins >> 16) & 0xff
+}
+
+func bcD(ins uint32) uint32 {
+	return ins >> 16
+}
+
+// Return the register used to store the function called at pc or metaname if it's a metamethod
+func getSlotOrMetaname(ins uint32) (slot uint32, metaname string) {
+	op := bcOp(ins)
+	mm := bcModeMM(op)
+	if mm == MMcall {
+		slot := bcA(ins)
+		if bcOp(ins) == BC_ITERC {
+			slot -= 3
+		}
+		return slot, ""
+	} else if mm != MMMax {
+		return 0, ljMetaNames[mm]
+	}
+	return 0, ""
+}
+func bcModeAIsBase(op uint32) bool {
+	return bcModeA(op) == BCMbase
+}
+func bcModeAIsDst(op uint32) bool {
+	return bcModeA(op) == BCMdst
+}
+
+var ljMetaNames = []string{
+	"index", "newindex", "gc",
+	"mode", "eq", "len", "lt", "le", "concat",
+	"call", "add", "sub", "mul", "div", "mod", "pow", "unm",
+	"metatable", "tostring", "new", "pairs",
+	"ipairs",
+}
+
+const (
+	BCMdst  = 1
+	BCMbase = 2
+	MMcall  = 9
+	MMMax   = 0x16
+)
+
+//nolint:stylecheck
+const (
+	BC_ISLT = iota
+	BC_ISGE
+	BC_ISLE
+	BC_ISGT
+	BC_ISEQV
+	BC_ISNEV
+	BC_ISEQS
+	BC_ISNES
+	BC_ISEQN
+	BC_ISNEN
+	BC_ISEQP
+	BC_ISNEP
+	BC_ISTC
+	BC_ISFC
+	BC_IST
+	BC_ISF
+	BC_ISTYPE
+	BC_ISNUM
+	BC_MOV
+	BC_NOT
+	BC_UNM
+	BC_LEN
+	BC_ADDVN
+	BC_SUBVN
+	BC_MULVN
+	BC_DIVVN
+	BC_MODVN
+	BC_ADDNV
+	BC_SUBNV
+	BC_MULNV
+	BC_DIVNV
+	BC_MODNV
+	BC_ADDVV
+	BC_SUBVV
+	BC_MULVV
+	BC_DIVVV
+	BC_MODVV
+	BC_POW
+	BC_CAT
+	BC_KSTR
+	BC_KCDATA
+	BC_KSHORT
+	BC_KNUM
+	BC_KPRI
+	BC_KNIL
+	BC_UGET
+	BC_USETV
+	BC_USETS
+	BC_USETN
+	BC_USETP
+	BC_UCLO
+	BC_FNEW
+	BC_TNEW
+	BC_TDUP
+	BC_GGET
+	BC_GSET
+	BC_TGETV
+	BC_TGETS
+	BC_TGETB
+	BC_TGETR
+	BC_TSETV
+	BC_TSETS
+	BC_TSETB
+	BC_TSETM
+	BC_TSETR
+	BC_CALLM
+	BC_CALL
+	BC_CALLMT
+	BC_CALLT
+	BC_ITERC
+	BC_ITERN
+	BC_VARG
+	BC_ISNEXT
+	BC_RETM
+	BC_RET
+	BC_RET0
+	BC_RET1
+	BC_FORI
+	BC_JFORI
+	BC_FORL
+	BC_IFORL
+	BC_JFORL
+	BC_ITERL
+	BC_IITERL
+	BC_JITERL
+	BC_LOOP
+	BC_ILOOP
+	BC_JLOOP
+	BC_JMP
+	BC_FUNCF
+	BC_IFUNCF
+	BC_JFUNCF
+	BC_FUNCV
+	BC_IFUNCV
+	BC_JFUNCV
+	BC_FUNCC
+	BC_FUNCCW
+	BC__MAX
+)