delve/pkg/proc/dwarf_expr_test.go
Alessandro Arzilli 200994bc8f
proc/*: only load floating point registers when needed (#1981)
Changes implementations of proc.Registers interface and the
op.DwarfRegisters struct so that floating point registers can be loaded
only when they are needed.
Removes the floatingPoint parameter from proc.Thread.Registers.
This accomplishes three things:

1. it simplifies the proc.Thread.Registers interface
2. it makes it impossible to accidentally create a broken set of saved
   registers or of op.DwarfRegisters by accidentally calling
   Registers(false)
3. it improves general performance of Delve by avoiding to load
   floating point registers as much as possible

Floating point registers are loaded under two circumstances:

1. When the Slice method is called with floatingPoint == true
2. When the Copy method is called

Benchmark before:

BenchmarkConditionalBreakpoints-4   	       1	4327350142 ns/op

Benchmark after:

BenchmarkConditionalBreakpoints-4   	       1	3852642917 ns/op

Updates #1549
2020-05-13 11:56:50 -07:00

326 lines
11 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"
"unsafe"
"github.com/go-delve/delve/pkg/dwarf/dwarfbuilder"
"github.com/go-delve/delve/pkg/dwarf/godwarf"
"github.com/go-delve/delve/pkg/dwarf/op"
"github.com/go-delve/delve/pkg/proc"
"github.com/go-delve/delve/pkg/proc/linutil"
)
func ptrSizeByRuntimeArch() int {
return int(unsafe.Sizeof(uintptr(0)))
}
func fakeCFA() uint64 {
ptrSize := ptrSizeByRuntimeArch()
if ptrSize == 8 {
return 0xc420051d00
}
if ptrSize == 4 {
return 0xc4251d00
}
panic(fmt.Errorf("not support ptr size %d", ptrSize))
}
func fakeBinaryInfo(t *testing.T, dwb *dwarfbuilder.Builder) (*proc.BinaryInfo, *dwarf.Data) {
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.LoadImageFromData(dwdata, frame, line, loc)
return bi, dwdata
}
// 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, BinInfo: bi}
for name, value := range testCases {
uintExprCheck(t, scope, name, uint64(value))
}
return scope
}
func dwarfRegisters(bi *proc.BinaryInfo, regs *linutil.AMD64Registers) op.DwarfRegisters {
a := proc.AMD64Arch("linux")
so := bi.PCToImage(regs.PC())
dwarfRegs := a.RegistersToDwarfRegisters(so.StaticBase, regs)
dwarfRegs.CFA = int64(fakeCFA())
dwarfRegs.FrameBase = int64(fakeCFA())
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(fakeCFA(), uint64(0), uint64(testCases["b"]))
regs := linutil.AMD64Registers{Regs: &linutil.AMD64PtraceRegs{}}
regs.Regs.Rax = uint64(testCases["a"])
regs.Regs.Rdx = uint64(testCases["c"])
dwarfExprCheck(t, mem, dwarfRegisters(bi, &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.AddPointerType("*uint8", byteoff)
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(fakeCFA(), uint64(0), uint64(0), uint16(testCases["pair.v"]), []byte(stringVal))
var regs linutil.AMD64Registers
regs.Regs = &linutil.AMD64PtraceRegs{}
regs.Regs.Rax = uint64(len(stringVal))
regs.Regs.Rdx = fakeCFA() + 18
regs.Regs.Rcx = uint64(testCases["pair.k"])
regs.Regs.Rbx = uint64(testCases["n"])
scope := dwarfExprCheck(t, mem, dwarfRegisters(bi, &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{
{Lowpc: 0x40100, Highpc: 0x40700, Loc: dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa)},
{Lowpc: 0x40700, Highpc: 0x41000, Loc: 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(fakeCFA(), uint16(before), uint16(after))
const PC = 0x40100
regs := linutil.AMD64Registers{Regs: &linutil.AMD64PtraceRegs{Rip: PC}}
scope := &proc.EvalScope{Location: proc.Location{PC: PC, Fn: mainfn}, Regs: dwarfRegisters(bi, &regs), Mem: mem, BinInfo: bi}
uintExprCheck(t, scope, "a", before)
scope.PC = 0x40800
scope.Regs.Reg(scope.Regs.PCRegNum).Uint64Val = scope.PC
uintExprCheck(t, scope, "a", after)
}
func TestIssue1419(t *testing.T) {
// trying to read a slice variable with a location list that tries to read
// from registers we don't have should not cause a panic.
dwb := dwarfbuilder.New()
uint64off := dwb.AddBaseType("uint64", dwarfbuilder.DW_ATE_unsigned, 8)
intoff := dwb.AddBaseType("int", dwarfbuilder.DW_ATE_signed, 8)
intptroff := dwb.AddPointerType("*int", intoff)
sliceoff := dwb.AddStructType("[]int", 24)
dwb.Attr(godwarf.AttrGoKind, uint8(23))
dwb.AddMember("array", intptroff, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(0)))
dwb.AddMember("len", uint64off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(8)))
dwb.AddMember("cap", uint64off, dwarfbuilder.LocationBlock(op.DW_OP_plus_uconst, uint(16)))
dwb.TagClose()
dwb.AddSubprogram("main.main", 0x40100, 0x41000)
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)))
dwb.TagClose()
bi, _ := fakeBinaryInfo(t, dwb)
mainfn := bi.LookupFunc["main.main"]
mem := newFakeMemory(fakeCFA())
scope := &proc.EvalScope{Location: proc.Location{PC: 0x40100, Fn: mainfn}, Regs: op.DwarfRegisters{}, Mem: mem, BinInfo: bi}
va, err := scope.EvalExpression("a", normalLoadConfig)
assertNoError(err, t, "EvalExpression(a)")
t.Logf("%#x\n", va.Addr)
t.Logf("%v", va)
if va.Unreadable == nil {
t.Fatalf("expected 'a' to be unreadable but it wasn't")
}
if va.Unreadable.Error() != "could not read 8 bytes from register 2 (size: 0)" {
t.Fatalf("wrong unreadable reason for variable 'a': %v", va.Unreadable)
}
}
func TestLocationCovers(t *testing.T) {
const before = 0x1234
const after = 0x4321
dwb := dwarfbuilder.New()
uint16off := dwb.AddBaseType("uint16", dwarfbuilder.DW_ATE_unsigned, 2)
dwb.AddCompileUnit("main", 0x0)
dwb.AddSubprogram("main.main", 0x40100, 0x41000)
aOff := dwb.AddVariable("a", uint16off, []dwarfbuilder.LocEntry{
{Lowpc: 0x40100, Highpc: 0x40700, Loc: dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa)},
{Lowpc: 0x40700, Highpc: 0x41000, Loc: dwarfbuilder.LocationBlock(op.DW_OP_call_frame_cfa, op.DW_OP_consts, int(2), op.DW_OP_plus)},
})
dwb.TagClose()
dwb.TagClose()
bi, dwdata := fakeBinaryInfo(t, dwb)
dwrdr := dwdata.Reader()
dwrdr.Seek(aOff)
aEntry, err := dwrdr.Next()
assertNoError(err, t, "reading 'a' entry")
ranges, err := bi.LocationCovers(aEntry, dwarf.AttrLocation)
assertNoError(err, t, "LocationCovers")
t.Logf("%x", ranges)
if fmt.Sprintf("%x", ranges) != "[[40100 40700] [40700 41000]]" {
t.Error("wrong value returned by LocationCover")
}
}
func TestIssue1636_InlineWithoutOrigin(t *testing.T) {
// Gcc (specifically GNU C++11 6.3.0) will emit DW_TAG_inlined_subroutine
// without a DW_AT_abstract_origin or a name. What is an inlined subroutine
// without a reference to an abstract origin or even a name? Regardless,
// Delve shouldn't crash.
dwb := dwarfbuilder.New()
dwb.AddCompileUnit("main", 0x0)
dwb.AddSubprogram("main.main", 0x40100, 0x41000)
dwb.TagOpen(dwarf.TagInlinedSubroutine, "")
dwb.TagClose()
dwb.TagClose()
dwb.TagClose()
fakeBinaryInfo(t, dwb)
}