f3b149bda7
This change splits the BinaryInfo object into a slice of Image objects containing information about the base executable and each loaded shared library (note: go plugins are shared libraries). Delve backens are supposed to call BinaryInfo.AddImage whenever they detect that a new shared library has been loaded. Member fields of BinaryInfo that are used to speed up access to dwarf (Functions, packageVars, consts, etc...) remain part of BinaryInfo and are updated to reference the correct image object. This simplifies this change. This approach has a few shortcomings: 1. Multiple shared libraries can define functions or globals with the same name and we have no way to disambiguate between them. 2. We don't have a way to handle library unloading. Both of those affect C shared libraries much more than they affect go plugins. Go plugins can't be unloaded at all and a lot of name collisions are prevented by import paths. There's only one problem that is concerning: if two plugins both import the same package they will end up with multiple definition for the same function. For example if two plugins use fmt.Printf the final in-memory image (and therefore our BinaryInfo object) will end up with two copies of fmt.Printf at different memory addresses. If a user types break fmt.Printf a breakpoint should be created at *both* locations. Allowing this is a relatively complex change that should be done in a different PR than this. For this reason I consider this approach an acceptable and sustainable stopgap. Updates #865
263 lines
8.8 KiB
Go
263 lines
8.8 KiB
Go
// Tests for loading variables that have complex location expressions. They
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// are only produced for optimized code (for both Go and C) therefore we can
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// not get the compiler to produce them reliably enough for tests.
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package proc_test
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import (
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"bytes"
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"debug/dwarf"
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"encoding/binary"
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"fmt"
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"go/constant"
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"testing"
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"github.com/go-delve/delve/pkg/dwarf/dwarfbuilder"
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"github.com/go-delve/delve/pkg/dwarf/godwarf"
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"github.com/go-delve/delve/pkg/dwarf/op"
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"github.com/go-delve/delve/pkg/proc"
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"github.com/go-delve/delve/pkg/proc/linutil"
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)
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const defaultCFA = 0xc420051d00
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func fakeBinaryInfo(t *testing.T, dwb *dwarfbuilder.Builder) *proc.BinaryInfo {
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abbrev, aranges, frame, info, line, pubnames, ranges, str, loc, err := dwb.Build()
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assertNoError(err, t, "dwarfbuilder.Build")
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dwdata, err := dwarf.New(abbrev, aranges, frame, info, line, pubnames, ranges, str)
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assertNoError(err, t, "creating dwarf")
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bi := proc.NewBinaryInfo("linux", "amd64")
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bi.LoadImageFromData(dwdata, frame, line, loc)
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return bi
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}
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// fakeMemory implements proc.MemoryReadWriter by reading from a byte slice.
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// Byte 0 of "data" is at address "base".
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type fakeMemory struct {
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base uint64
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data []byte
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}
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func newFakeMemory(base uint64, contents ...interface{}) *fakeMemory {
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mem := &fakeMemory{base: base}
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var buf bytes.Buffer
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for _, x := range contents {
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binary.Write(&buf, binary.LittleEndian, x)
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}
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mem.data = buf.Bytes()
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return mem
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}
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func (mem *fakeMemory) ReadMemory(data []byte, addr uintptr) (int, error) {
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if uint64(addr) < mem.base {
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return 0, fmt.Errorf("read out of bounds %d %#x", len(data), addr)
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}
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start := uint64(addr) - mem.base
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end := uint64(len(data)) + start
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if end > uint64(len(mem.data)) {
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panic(fmt.Errorf("read out of bounds %d %#x", len(data), addr))
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}
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copy(data, mem.data[start:end])
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return len(data), nil
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}
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func (mem *fakeMemory) WriteMemory(uintptr, []byte) (int, error) {
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return 0, fmt.Errorf("not implemented")
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}
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func uintExprCheck(t *testing.T, scope *proc.EvalScope, expr string, tgt uint64) {
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thevar, err := scope.EvalExpression(expr, normalLoadConfig)
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assertNoError(err, t, fmt.Sprintf("EvalExpression(%s)", expr))
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if thevar.Unreadable != nil {
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t.Errorf("variable %q unreadable: %v", expr, thevar.Unreadable)
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} else {
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if v, _ := constant.Uint64Val(thevar.Value); v != tgt {
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t.Errorf("expected value %x got %x for %q", tgt, v, expr)
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}
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}
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}
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func dwarfExprCheck(t *testing.T, mem proc.MemoryReadWriter, regs op.DwarfRegisters, bi *proc.BinaryInfo, testCases map[string]uint16, fn *proc.Function) *proc.EvalScope {
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scope := &proc.EvalScope{Location: proc.Location{PC: 0x40100, Fn: fn}, Regs: regs, Mem: mem, Gvar: nil, BinInfo: bi}
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for name, value := range testCases {
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uintExprCheck(t, scope, name, uint64(value))
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}
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return scope
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}
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func dwarfRegisters(bi *proc.BinaryInfo, regs *linutil.AMD64Registers) op.DwarfRegisters {
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a := proc.AMD64Arch("linux")
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dwarfRegs := a.RegistersToDwarfRegisters(bi, regs)
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dwarfRegs.CFA = defaultCFA
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dwarfRegs.FrameBase = defaultCFA
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return dwarfRegs
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}
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func TestDwarfExprRegisters(t *testing.T) {
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testCases := map[string]uint16{
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"a": 0x1234,
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"b": 0x4321,
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"c": 0x2143,
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}
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dwb := dwarfbuilder.New()
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uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
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dwb.AddSubprogram("main.main", 0x40100, 0x41000)
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dwb.Attr(dwarf.AttrFrameBase, dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa))
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dwb.AddVariable("a", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_reg0))
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dwb.AddVariable("b", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_fbreg, int(8)))
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dwb.AddVariable("c", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_regx, int(1)))
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dwb.TagClose()
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bi := fakeBinaryInfo(t, dwb)
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mainfn := bi.LookupFunc["main.main"]
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mem := newFakeMemory(defaultCFA, uint64(0), uint64(testCases["b"]), uint16(testCases["pair.v"]))
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regs := linutil.AMD64Registers{Regs: &linutil.AMD64PtraceRegs{}}
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regs.Regs.Rax = uint64(testCases["a"])
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regs.Regs.Rdx = uint64(testCases["c"])
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dwarfExprCheck(t, mem, dwarfRegisters(bi, ®s), bi, testCases, mainfn)
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}
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func TestDwarfExprComposite(t *testing.T) {
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testCases := map[string]uint16{
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"pair.k": 0x8765,
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"pair.v": 0x5678,
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"n": 42,
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}
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const stringVal = "this is a string"
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dwb := dwarfbuilder.New()
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uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
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intoff := dwb.AddBaseType("int", dwarfbuilder.DW_ATE_signed, 8)
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byteoff := dwb.AddBaseType("uint8", dwarfbuilder.DW_ATE_unsigned, 1)
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byteptroff := dwb.AddPointerType("*uint8", byteoff)
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pairoff := dwb.AddStructType("main.pair", 4)
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dwb.Attr(godwarf.AttrGoKind, uint8(25))
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dwb.AddMember("k", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(0)))
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dwb.AddMember("v", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(2)))
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dwb.TagClose()
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stringoff := dwb.AddStructType("string", 16)
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dwb.Attr(godwarf.AttrGoKind, uint8(24))
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dwb.AddMember("str", byteptroff, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(0)))
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dwb.AddMember("len", intoff, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(8)))
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dwb.TagClose()
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dwb.AddSubprogram("main.main", 0x40100, 0x41000)
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dwb.AddVariable("pair", pairoff, dwarfbuilder.LocationBlock(
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op.DW_OP_reg2, op.DW_OP_piece, uint(2),
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op.DW_OP_call_frame_cfa, op.DW_OP_consts, int(16), op.DW_OP_plus, op.DW_OP_piece, uint(2)))
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dwb.AddVariable("s", stringoff, dwarfbuilder.LocationBlock(
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op.DW_OP_reg1, op.DW_OP_piece, uint(8),
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op.DW_OP_reg0, op.DW_OP_piece, uint(8)))
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dwb.AddVariable("n", intoff, dwarfbuilder.LocationBlock(op.DW_OP_reg3))
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dwb.TagClose()
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bi := fakeBinaryInfo(t, dwb)
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mainfn := bi.LookupFunc["main.main"]
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mem := newFakeMemory(defaultCFA, uint64(0), uint64(0), uint16(testCases["pair.v"]), []byte(stringVal))
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var regs linutil.AMD64Registers
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regs.Regs = &linutil.AMD64PtraceRegs{}
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regs.Regs.Rax = uint64(len(stringVal))
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regs.Regs.Rdx = defaultCFA + 18
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regs.Regs.Rcx = uint64(testCases["pair.k"])
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regs.Regs.Rbx = uint64(testCases["n"])
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scope := dwarfExprCheck(t, mem, dwarfRegisters(bi, ®s), bi, testCases, mainfn)
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thevar, err := scope.EvalExpression("s", normalLoadConfig)
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assertNoError(err, t, fmt.Sprintf("EvalExpression(%s)", "s"))
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if thevar.Unreadable != nil {
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t.Errorf("variable \"s\" unreadable: %v", thevar.Unreadable)
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} else {
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if v := constant.StringVal(thevar.Value); v != stringVal {
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t.Errorf("expected value %q got %q", stringVal, v)
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}
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}
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}
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func TestDwarfExprLoclist(t *testing.T) {
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const before = 0x1234
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const after = 0x4321
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dwb := dwarfbuilder.New()
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uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
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dwb.AddSubprogram("main.main", 0x40100, 0x41000)
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dwb.AddVariable("a", uint16off, []dwarfbuilder.LocEntry{
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{0x40100, 0x40700, dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa)},
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{0x40700, 0x41000, dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa, op.DW_OP_consts, int(2), op.DW_OP_plus)},
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})
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dwb.TagClose()
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bi := fakeBinaryInfo(t, dwb)
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mainfn := bi.LookupFunc["main.main"]
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mem := newFakeMemory(defaultCFA, uint16(before), uint16(after))
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regs := linutil.AMD64Registers{Regs: &linutil.AMD64PtraceRegs{}}
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scope := &proc.EvalScope{Location: proc.Location{PC: 0x40100, Fn: mainfn}, Regs: dwarfRegisters(bi, ®s), Mem: mem, Gvar: nil, BinInfo: bi}
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uintExprCheck(t, scope, "a", before)
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scope.PC = 0x40800
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uintExprCheck(t, scope, "a", after)
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}
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func TestIssue1419(t *testing.T) {
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// trying to read a slice variable with a location list that tries to read
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// from registers we don't have should not cause a panic.
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dwb := dwarfbuilder.New()
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uint64off := dwb.AddBaseType("uint64", dwarfbuilder.DW_ATE_unsigned, 8)
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intoff := dwb.AddBaseType("int", dwarfbuilder.DW_ATE_signed, 8)
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intptroff := dwb.AddPointerType("*int", intoff)
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sliceoff := dwb.AddStructType("[]int", 24)
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dwb.Attr(godwarf.AttrGoKind, uint8(23))
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dwb.AddMember("array", intptroff, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(0)))
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dwb.AddMember("len", uint64off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(8)))
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dwb.AddMember("cap", uint64off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(16)))
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dwb.TagClose()
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dwb.AddSubprogram("main.main", 0x40100, 0x41000)
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dwb.AddVariable("a", sliceoff, dwarfbuilder.LocationBlock(op.DW_OP_reg2, op.DW_OP_piece, uint(8), op.DW_OP_reg2, op.DW_OP_piece, uint(8), op.DW_OP_reg2, op.DW_OP_piece, uint(8)))
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dwb.TagClose()
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bi := fakeBinaryInfo(t, dwb)
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mainfn := bi.LookupFunc["main.main"]
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mem := newFakeMemory(defaultCFA)
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scope := &proc.EvalScope{Location: proc.Location{PC: 0x40100, Fn: mainfn}, Regs: op.DwarfRegisters{}, Mem: mem, Gvar: nil, BinInfo: bi}
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va, err := scope.EvalExpression("a", normalLoadConfig)
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assertNoError(err, t, "EvalExpression(a)")
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t.Logf("%#x\n", va.Addr)
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t.Logf("%v", va)
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if va.Unreadable == nil {
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t.Fatalf("expected 'a' to be unreadable but it wasn't")
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}
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if va.Unreadable.Error() != "could not read 8 bytes from register 2 (size: 0)" {
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t.Fatalf("wrong unreadable reason for variable 'a': %v", va.Unreadable)
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}
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}
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