delve/pkg/proc/dwarf_expr_test.go
aarzilli 74c98bc961 proc: support position independent executables (PIE)
Support for position independent executables (PIE) on the native linux
backend, the gdbserver backend on linux and the core backend.
Also implemented in the windows native backend, but it can't be tested
because go doesn't support PIE on windows yet.
2018-10-11 11:21:27 -07:00

225 lines
7.3 KiB
Go

// Tests for loading variables that have complex location expressions. They
// are only produced for optimized code (for both Go and C) therefore we can
// not get the compiler to produce them reliably enough for tests.
package proc_test
import (
"bytes"
"debug/dwarf"
"encoding/binary"
"fmt"
"go/constant"
"testing"
"github.com/derekparker/delve/pkg/dwarf/dwarfbuilder"
"github.com/derekparker/delve/pkg/dwarf/godwarf"
"github.com/derekparker/delve/pkg/dwarf/op"
"github.com/derekparker/delve/pkg/proc"
"github.com/derekparker/delve/pkg/proc/core"
)
const defaultCFA = 0xc420051d00
func fakeBinaryInfo(t *testing.T, dwb *dwarfbuilder.Builder) *proc.BinaryInfo {
abbrev, aranges, frame, info, line, pubnames, ranges, str, loc, err := dwb.Build()
assertNoError(err, t, "dwarfbuilder.Build")
dwdata, err := dwarf.New(abbrev, aranges, frame, info, line, pubnames, ranges, str)
assertNoError(err, t, "creating dwarf")
bi := proc.NewBinaryInfo("linux", "amd64")
bi.LoadFromData(dwdata, frame, line, loc)
return bi
}
// fakeMemory implements proc.MemoryReadWriter by reading from a byte slice.
// Byte 0 of "data" is at address "base".
type fakeMemory struct {
base uint64
data []byte
}
func newFakeMemory(base uint64, contents ...interface{}) *fakeMemory {
mem := &fakeMemory{base: base}
var buf bytes.Buffer
for _, x := range contents {
binary.Write(&buf, binary.LittleEndian, x)
}
mem.data = buf.Bytes()
return mem
}
func (mem *fakeMemory) ReadMemory(data []byte, addr uintptr) (int, error) {
if uint64(addr) < mem.base {
return 0, fmt.Errorf("read out of bounds %d %#x", len(data), addr)
}
start := uint64(addr) - mem.base
end := uint64(len(data)) + start
if end > uint64(len(mem.data)) {
panic(fmt.Errorf("read out of bounds %d %#x", len(data), addr))
}
copy(data, mem.data[start:end])
return len(data), nil
}
func (mem *fakeMemory) WriteMemory(uintptr, []byte) (int, error) {
return 0, fmt.Errorf("not implemented")
}
func uintExprCheck(t *testing.T, scope *proc.EvalScope, expr string, tgt uint64) {
thevar, err := scope.EvalExpression(expr, normalLoadConfig)
assertNoError(err, t, fmt.Sprintf("EvalExpression(%s)", expr))
if thevar.Unreadable != nil {
t.Errorf("variable %q unreadable: %v", expr, thevar.Unreadable)
} else {
if v, _ := constant.Uint64Val(thevar.Value); v != tgt {
t.Errorf("expected value %x got %x for %q", tgt, v, expr)
}
}
}
func dwarfExprCheck(t *testing.T, mem proc.MemoryReadWriter, regs op.DwarfRegisters, bi *proc.BinaryInfo, testCases map[string]uint16, fn *proc.Function) *proc.EvalScope {
scope := &proc.EvalScope{Location: proc.Location{PC: 0x40100, Fn: fn}, Regs: regs, Mem: mem, Gvar: nil, BinInfo: bi}
for name, value := range testCases {
uintExprCheck(t, scope, name, uint64(value))
}
return scope
}
func dwarfRegisters(regs *core.Registers) op.DwarfRegisters {
a := proc.AMD64Arch("linux")
dwarfRegs := a.RegistersToDwarfRegisters(regs, 0)
dwarfRegs.CFA = defaultCFA
dwarfRegs.FrameBase = defaultCFA
return dwarfRegs
}
func TestDwarfExprRegisters(t *testing.T) {
testCases := map[string]uint16{
"a": 0x1234,
"b": 0x4321,
"c": 0x2143,
}
dwb := dwarfbuilder.New()
uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
dwb.AddSubprogram("main.main", 0x40100, 0x41000)
dwb.Attr(dwarf.AttrFrameBase, dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa))
dwb.AddVariable("a", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_reg0))
dwb.AddVariable("b", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_fbreg, int(8)))
dwb.AddVariable("c", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_regx, int(1)))
dwb.TagClose()
bi := fakeBinaryInfo(t, dwb)
mainfn := bi.LookupFunc["main.main"]
mem := newFakeMemory(defaultCFA, uint64(0), uint64(testCases["b"]), uint16(testCases["pair.v"]))
regs := core.Registers{LinuxCoreRegisters: &core.LinuxCoreRegisters{}}
regs.Rax = uint64(testCases["a"])
regs.Rdx = uint64(testCases["c"])
dwarfExprCheck(t, mem, dwarfRegisters(&regs), bi, testCases, mainfn)
}
func TestDwarfExprComposite(t *testing.T) {
testCases := map[string]uint16{
"pair.k": 0x8765,
"pair.v": 0x5678,
"n": 42,
}
const stringVal = "this is a string"
dwb := dwarfbuilder.New()
uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
intoff := dwb.AddBaseType("int", dwarfbuilder.DW_ATE_signed, 8)
byteoff := dwb.AddBaseType("uint8", dwarfbuilder.DW_ATE_unsigned, 1)
byteptroff := dwb.TagOpen(dwarf.TagPointerType, "*uint8")
dwb.Attr(godwarf.AttrGoKind, uint8(22))
dwb.Attr(dwarf.AttrType, byteoff)
dwb.TagClose()
pairoff := dwb.AddStructType("main.pair", 4)
dwb.Attr(godwarf.AttrGoKind, uint8(25))
dwb.AddMember("k", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(0)))
dwb.AddMember("v", uint16off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(2)))
dwb.TagClose()
stringoff := dwb.AddStructType("string", 16)
dwb.Attr(godwarf.AttrGoKind, uint8(24))
dwb.AddMember("str", byteptroff, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(0)))
dwb.AddMember("len", intoff, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(8)))
dwb.TagClose()
dwb.AddSubprogram("main.main", 0x40100, 0x41000)
dwb.AddVariable("pair", pairoff, dwarfbuilder.LocationBlock(
op.DW_OP_reg2, op.DW_OP_piece, uint(2),
op.DW_OP_call_frame_cfa, op.DW_OP_consts, int(16), op.DW_OP_plus, op.DW_OP_piece, uint(2)))
dwb.AddVariable("s", stringoff, dwarfbuilder.LocationBlock(
op.DW_OP_reg1, op.DW_OP_piece, uint(8),
op.DW_OP_reg0, op.DW_OP_piece, uint(8)))
dwb.AddVariable("n", intoff, dwarfbuilder.LocationBlock(op.DW_OP_reg3))
dwb.TagClose()
bi := fakeBinaryInfo(t, dwb)
mainfn := bi.LookupFunc["main.main"]
mem := newFakeMemory(defaultCFA, uint64(0), uint64(0), uint16(testCases["pair.v"]), []byte(stringVal))
var regs core.Registers
regs.LinuxCoreRegisters = &core.LinuxCoreRegisters{}
regs.Rax = uint64(len(stringVal))
regs.Rdx = defaultCFA + 18
regs.Rcx = uint64(testCases["pair.k"])
regs.Rbx = uint64(testCases["n"])
scope := dwarfExprCheck(t, mem, dwarfRegisters(&regs), bi, testCases, mainfn)
thevar, err := scope.EvalExpression("s", normalLoadConfig)
assertNoError(err, t, fmt.Sprintf("EvalExpression(%s)", "s"))
if thevar.Unreadable != nil {
t.Errorf("variable \"s\" unreadable: %v", thevar.Unreadable)
} else {
if v := constant.StringVal(thevar.Value); v != stringVal {
t.Errorf("expected value %q got %q", stringVal, v)
}
}
}
func TestDwarfExprLoclist(t *testing.T) {
const before = 0x1234
const after = 0x4321
dwb := dwarfbuilder.New()
uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
dwb.AddSubprogram("main.main", 0x40100, 0x41000)
dwb.AddVariable("a", uint16off, []dwarfbuilder.LocEntry{
{0x40100, 0x40700, dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa)},
{0x40700, 0x41000, dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa, op.DW_OP_consts, int(2), op.DW_OP_plus)},
})
dwb.TagClose()
bi := fakeBinaryInfo(t, dwb)
mainfn := bi.LookupFunc["main.main"]
mem := newFakeMemory(defaultCFA, uint16(before), uint16(after))
regs := core.Registers{LinuxCoreRegisters: &core.LinuxCoreRegisters{}}
scope := &proc.EvalScope{Location: proc.Location{PC: 0x40100, Fn: mainfn}, Regs: dwarfRegisters(&regs), Mem: mem, Gvar: nil, BinInfo: bi}
uintExprCheck(t, scope, "a", before)
scope.PC = 0x40800
uintExprCheck(t, scope, "a", after)
}