diff --git a/dwtest/dwloc_test.go b/dwtest/dwloc_test.go
new file mode 100644
index 0000000..a4e85c9
--- /dev/null
+++ b/dwtest/dwloc_test.go
@@ -0,0 +1,263 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dwtest_test
+
+// This file contains a set of DWARF variable location generation
+// tests that are intended to compliment the existing linker DWARF
+// tests. The tests make use of a harness / utility program
+// "dwdumploc" that is built during test setup and then
+// invoked (fork+exec) in testpoints. We do things this way (as
+// opposed to just incorporating all of the source code from
+// testdata/dwdumploc.go into this file) so that the dumper code can
+// import packages from Delve without needing to vendor everything
+// into the Go distribution itself.
+//
+// Notes on GOARCH/GOOS support: this test is guarded to execute only
+// on arch/os combinations supported by Delve (see the testpoint
+// below); as Delve evolves we may need to update accordingly.
+//
+// This test requires network support (the harness build has to
+// download packages), so only runs in "long" test mode at the moment,
+// and since we don't currently have longtest builders for every
+// arch/os pair that Delve supports (ex: no linux/arm64 longtest
+// builder, Issue #49649), this is something to keep in mind when
+// running trybots etc.
+//
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"golang.org/x/debug/internal/testenv"
+)
+
+// copyFilesForHarness copies various files into the build dir for the
+// harness, including the main package, go.mod, and a copy of the
+// dwtest package (the latter is why we are doing an explicit copy as
+// opposed to just building directly from sources in testdata).
+// Return value is the path to a build directory for the harness
+// build.
+func copyFilesForHarness(t *testing.T) string {
+	mkdir := func(d string) {
+		if err := os.Mkdir(d, 0777); err != nil {
+			t.Fatalf("mkdir failed: %v", err)
+		}
+	}
+	cp := func(from, to string) {
+		var payload []byte
+		payload, err := ioutil.ReadFile(from)
+		if err != nil {
+			t.Fatalf("ioutil.ReadFile failed: %v", err)
+		}
+		if err = ioutil.WriteFile(to, payload, 0644); err != nil {
+			t.Fatalf("ioutil.WriteFile failed: %v", err)
+		}
+	}
+	join := filepath.Join
+	bd := join(t.TempDir(), "build")
+	bdt := join(bd, "dwtest")
+	mkdir(bd)
+	mkdir(bdt)
+	cp(join("testdata", "dwdumploc.go"), join(bd, "main.go"))
+	cp(join("testdata", "go.mod.txt"), join(bd, "go.mod"))
+	cp(join("testdata", "go.sum.txt"), join(bd, "go.sum"))
+	cp("dwtest.go", join(bdt, "dwtest.go"))
+	return bd
+}
+
+// buildHarness builds the helper program "dwdumploc.exe".
+func buildHarness(t *testing.T) string {
+
+	// Copy source files into build dir.
+	bd := copyFilesForHarness(t)
+
+	// Run build.
+	harnessPath := filepath.Join(t.TempDir(), "dumpdwloc.exe")
+	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", harnessPath)
+	cmd.Dir = bd
+	if b, err := cmd.CombinedOutput(); err != nil {
+		t.Fatalf("build failed (%v): %s", err, b)
+	}
+	return harnessPath
+}
+
+// runHarness runs our previously built harness exec on a Go binary
+// 'exePath' for function 'fcn' and returns the results. Stderr from
+// the harness is printed to test stderr. Note: to debug the harness,
+// try adding "-v=2" to the exec.Command below.
+func runHarness(t *testing.T, harnessPath string, exePath string, fcn string) string {
+	cmd := exec.Command(harnessPath, "-m", exePath, "-f", fcn)
+	var b bytes.Buffer
+	cmd.Stderr = os.Stderr
+	cmd.Stdout = &b
+	if err := cmd.Run(); err != nil {
+		t.Fatalf("running 'harness -m %s -f %s': %v", exePath, fcn, err)
+	}
+	return strings.TrimSpace(string(b.Bytes()))
+}
+
+// gobuild is a helper to bulid a Go program from source code,
+// so that we can inspect selected bits of DWARF in the resulting binary.
+// Return value is binary path.
+func gobuild(t *testing.T, sourceCode string, pname string) string {
+	spath := filepath.Join(t.TempDir(), pname+".go")
+	if err := ioutil.WriteFile(spath, []byte(sourceCode), 0644); err != nil {
+		t.Fatalf("write to %s failed: %s", spath, err)
+	}
+	epath := filepath.Join(t.TempDir(), pname+".exe")
+
+	// A note on this build: Delve currently has problems digesting
+	// PIE binaries on Windows; until this can be straightened out,
+	// default to "exe" buildmode.
+	cmd := exec.Command(testenv.GoToolPath(t), "build", "-buildmode=exe", "-o", epath, spath)
+	if b, err := cmd.CombinedOutput(); err != nil {
+		t.Logf("%% build output: %s\n", b)
+		t.Fatalf("build failed: %s", err)
+	}
+	return epath
+}
+
+const programSourceCode = `
+package main
+
+import "context"
+
+var G int
+
+//go:noinline
+func another(x int) {
+	println(G)
+}
+
+//go:noinline
+func docall(f func()) {
+	f()
+}
+
+//go:noinline
+func Issue47354(s string) {
+	docall(func() {
+		println("s is", s)
+	})
+	G++
+	another(int(s[0]))
+}
+
+type DB int
+type driverConn int
+type Result interface {
+	Foo()
+}
+
+//go:noinline
+func (db *DB) Issue46845(ctx context.Context, dc *driverConn, release func(error), query string, args []interface{}) (res Result, err error) {
+	defer func() {
+		release(err)
+        println(len(args))
+	}()
+	return nil, nil
+}
+
+func main() {
+	Issue47354("poo")
+	var d DB
+	d.Issue46845(context.Background(), nil, func(error) {}, "foo", nil)
+}
+
+`
+
+func testIssue47354(t *testing.T, harnessPath string, ppath string) {
+	expected := map[string]string{
+		"amd64": "1: in-param \"s\" loc=\"{ [0: S=8 RAX] [1: S=8 RBX] }\"",
+		"arm64": "1: in-param \"s\" loc=\"{ [0: S=8 R0] [1: S=8 R1] }\"",
+	}
+	fname := "Issue47354"
+	got := runHarness(t, harnessPath, ppath, "main."+fname)
+	want := expected[runtime.GOARCH]
+	if got != want {
+		t.Errorf("failed Issue47354 arch %s:\ngot: %q\nwant: %q",
+			runtime.GOARCH, got, want)
+	}
+}
+
+func testIssue46845(t *testing.T, harnessPath string, ppath string) {
+
+	// NB: note the "addr=0x1000" for the stack-based parameter "args"
+	// below. This is not an accurate stack location, it's just an
+	// artifact of the way we call into Delve.
+	expected := map[string]string{
+		"amd64": `
+1: in-param "db" loc="{ [0: S=0 RAX] }"
+2: in-param "ctx" loc="{ [0: S=8 RBX] [1: S=8 RCX] }"
+3: in-param "dc" loc="{ [0: S=0 RDI] }"
+4: in-param "release" loc="{ [0: S=0 RSI] }"
+5: in-param "query" loc="{ [0: S=8 R8] [1: S=8 R9] }"
+6: in-param "args" loc="{ [0: S=8 addr=0x1000] [1: S=8 addr=0x1008] [2: S=8 addr=0x1010] }"
+7: out-param "res" loc="<not available>"
+8: out-param "err" loc="<not available>"
+`,
+		"arm64": `
+1: in-param "db" loc="{ [0: S=0 R0] }"
+2: in-param "ctx" loc="{ [0: S=8 R1] [1: S=8 R2] }"
+3: in-param "dc" loc="{ [0: S=0 R3] }"
+4: in-param "release" loc="{ [0: S=0 R4] }"
+5: in-param "query" loc="{ [0: S=8 R5] [1: S=8 R6] }"
+6: in-param "args" loc="{ [0: S=8 R7] [1: S=8 R8] [2: S=8 R9] }"
+7: out-param "res" loc="<not available>"
+8: out-param "err" loc="<not available>"
+`,
+	}
+	fname := "(*DB).Issue46845"
+	got := runHarness(t, harnessPath, ppath, "main."+fname)
+	want := strings.TrimSpace(expected[runtime.GOARCH])
+	if got != want {
+		t.Errorf("failed Issue47354 arch %s:\ngot: %s\nwant: %s",
+			runtime.GOARCH, got, want)
+	}
+}
+
+func TestDwarfVariableLocations(t *testing.T) {
+	testenv.NeedsGo1Point(t, 18)
+	testenv.MustHaveGoBuild(t)
+	testenv.MustHaveExternalNetwork(t)
+
+	// A note on the guard below:
+	// - Delve doesn't officially support darwin/arm64, but I've run
+	//   this test by hand on darwin/arm64 and it seems to work, so
+	//   it is included for the moment
+	// - the harness code currently only supports amd64 + arm64. If more
+	//   archs are added (ex: 386) the harness will need to be updated.
+	pair := runtime.GOOS + "/" + runtime.GOARCH
+	switch pair {
+	case "linux/amd64", "linux/arm64", "windows/amd64",
+		"darwin/amd64", "darwin/arm64":
+	default:
+		t.Skipf("unsupported OS/ARCH pair %s (this tests supports only OS values supported by Delve", pair)
+	}
+
+	// Build test harness.
+	harnessPath := buildHarness(t)
+
+	// Build program to inspect. NB: we're building at default (with
+	// optimization); it might also be worth doing a "-l -N" build
+	// to verify the location expressions in that case.
+	ppath := gobuild(t, programSourceCode, "prog")
+
+	// Sub-tests for each function we want to inspect.
+	t.Run("Issue47354", func(t *testing.T) {
+		t.Parallel()
+		testIssue47354(t, harnessPath, ppath)
+	})
+	t.Run("Issue46845", func(t *testing.T) {
+		t.Parallel()
+		testIssue46845(t, harnessPath, ppath)
+	})
+}
diff --git a/dwtest/dwtest.go b/dwtest/dwtest.go
new file mode 100644
index 0000000..de9498d
--- /dev/null
+++ b/dwtest/dwtest.go
@@ -0,0 +1,200 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Except for this comment and the import path, this file is a verbatim
+// copy of the file with the same name in $GOROOT/src/cmd/link/internal/dwtest.
+
+package dwtest
+
+import (
+	"debug/dwarf"
+	"errors"
+	"fmt"
+	"os"
+)
+
+// Helper type for supporting queries on DIEs within a DWARF
+// .debug_info section. Invoke the populate() method below passing in
+// a dwarf.Reader, which will read in all DIEs and keep track of
+// parent/child relationships. Queries can then be made to ask for
+// DIEs by name or by offset. This will hopefully reduce boilerplate
+// for future test writing.
+
+type Examiner struct {
+	dies        []*dwarf.Entry
+	idxByOffset map[dwarf.Offset]int
+	kids        map[int][]int
+	parent      map[int]int
+	byname      map[string][]int
+}
+
+// Populate the Examiner using the DIEs read from rdr.
+func (ex *Examiner) Populate(rdr *dwarf.Reader) error {
+	ex.idxByOffset = make(map[dwarf.Offset]int)
+	ex.kids = make(map[int][]int)
+	ex.parent = make(map[int]int)
+	ex.byname = make(map[string][]int)
+	var nesting []int
+	for entry, err := rdr.Next(); entry != nil; entry, err = rdr.Next() {
+		if err != nil {
+			return err
+		}
+		if entry.Tag == 0 {
+			// terminator
+			if len(nesting) == 0 {
+				return errors.New("nesting stack underflow")
+			}
+			nesting = nesting[:len(nesting)-1]
+			continue
+		}
+		idx := len(ex.dies)
+		ex.dies = append(ex.dies, entry)
+		if _, found := ex.idxByOffset[entry.Offset]; found {
+			return errors.New("DIE clash on offset")
+		}
+		ex.idxByOffset[entry.Offset] = idx
+		if name, ok := entry.Val(dwarf.AttrName).(string); ok {
+			ex.byname[name] = append(ex.byname[name], idx)
+		}
+		if len(nesting) > 0 {
+			parent := nesting[len(nesting)-1]
+			ex.kids[parent] = append(ex.kids[parent], idx)
+			ex.parent[idx] = parent
+		}
+		if entry.Children {
+			nesting = append(nesting, idx)
+		}
+	}
+	if len(nesting) > 0 {
+		return errors.New("unterminated child sequence")
+	}
+	return nil
+}
+
+func (e *Examiner) DIEs() []*dwarf.Entry {
+	return e.dies
+}
+
+func indent(ilevel int) {
+	for i := 0; i < ilevel; i++ {
+		fmt.Printf("  ")
+	}
+}
+
+// For debugging new tests
+func (ex *Examiner) DumpEntry(idx int, dumpKids bool, ilevel int) {
+	if idx >= len(ex.dies) {
+		fmt.Fprintf(os.Stderr, "DumpEntry: bad DIE %d: index out of range\n", idx)
+		return
+	}
+	entry := ex.dies[idx]
+	indent(ilevel)
+	fmt.Printf("0x%x: %v\n", idx, entry.Tag)
+	for _, f := range entry.Field {
+		indent(ilevel)
+		fmt.Printf("at=%v val=0x%x\n", f.Attr, f.Val)
+	}
+	if dumpKids {
+		ksl := ex.kids[idx]
+		for _, k := range ksl {
+			ex.DumpEntry(k, true, ilevel+2)
+		}
+	}
+}
+
+// Given a DIE offset, return the previously read dwarf.Entry, or nil
+func (ex *Examiner) EntryFromOffset(off dwarf.Offset) *dwarf.Entry {
+	if idx, found := ex.idxByOffset[off]; found && idx != -1 {
+		return ex.entryFromIdx(idx)
+	}
+	return nil
+}
+
+// Return the ID that Examiner uses to refer to the DIE at offset off
+func (ex *Examiner) IdxFromOffset(off dwarf.Offset) int {
+	if idx, found := ex.idxByOffset[off]; found {
+		return idx
+	}
+	return -1
+}
+
+// Return the dwarf.Entry pointer for the DIE with id 'idx'
+func (ex *Examiner) entryFromIdx(idx int) *dwarf.Entry {
+	if idx >= len(ex.dies) || idx < 0 {
+		return nil
+	}
+	return ex.dies[idx]
+}
+
+// Returns a list of child entries for a die with ID 'idx'
+func (ex *Examiner) Children(idx int) []*dwarf.Entry {
+	sl := ex.kids[idx]
+	ret := make([]*dwarf.Entry, len(sl))
+	for i, k := range sl {
+		ret[i] = ex.entryFromIdx(k)
+	}
+	return ret
+}
+
+// Returns parent DIE for DIE 'idx', or nil if the DIE is top level
+func (ex *Examiner) Parent(idx int) *dwarf.Entry {
+	p, found := ex.parent[idx]
+	if !found {
+		return nil
+	}
+	return ex.entryFromIdx(p)
+}
+
+// ParentCU returns the enclosing compilation unit DIE for the DIE
+// with a given index, or nil if for some reason we can't establish a
+// parent.
+func (ex *Examiner) ParentCU(idx int) *dwarf.Entry {
+	for {
+		parentDie := ex.Parent(idx)
+		if parentDie == nil {
+			return nil
+		}
+		if parentDie.Tag == dwarf.TagCompileUnit {
+			return parentDie
+		}
+		idx = ex.IdxFromOffset(parentDie.Offset)
+	}
+}
+
+// FileRef takes a given DIE by index and a numeric file reference
+// (presumably from a decl_file or call_file attribute), looks up the
+// reference in the .debug_line file table, and returns the proper
+// string for it. We need to know which DIE is making the reference
+// so as to find the right compilation unit.
+func (ex *Examiner) FileRef(dw *dwarf.Data, dieIdx int, fileRef int64) (string, error) {
+
+	// Find the parent compilation unit DIE for the specified DIE.
+	cuDie := ex.ParentCU(dieIdx)
+	if cuDie == nil {
+		return "", fmt.Errorf("no parent CU DIE for DIE with idx %d?", dieIdx)
+	}
+	// Construct a line reader and then use it to get the file string.
+	lr, lrerr := dw.LineReader(cuDie)
+	if lrerr != nil {
+		return "", fmt.Errorf("d.LineReader: %v", lrerr)
+	}
+	files := lr.Files()
+	if fileRef < 0 || int(fileRef) > len(files)-1 {
+		return "", fmt.Errorf("Examiner.FileRef: malformed file reference %d", fileRef)
+	}
+	return files[fileRef].Name, nil
+}
+
+// Return a list of all DIEs with name 'name'. When searching for DIEs
+// by name, keep in mind that the returned results will include child
+// DIEs such as params/variables. For example, asking for all DIEs named
+// "p" for even a small program will give you 400-500 entries.
+func (ex *Examiner) Named(name string) []*dwarf.Entry {
+	sl := ex.byname[name]
+	ret := make([]*dwarf.Entry, len(sl))
+	for i, k := range sl {
+		ret[i] = ex.entryFromIdx(k)
+	}
+	return ret
+}
diff --git a/dwtest/testdata/dwdumploc.go b/dwtest/testdata/dwdumploc.go
new file mode 100644
index 0000000..69ee702
--- /dev/null
+++ b/dwtest/testdata/dwdumploc.go
@@ -0,0 +1,486 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// This file is the source code for a test helper binary 'dwdumploc',
+// which is built and then run by the tests in cmd/link/internal/dwtest.
+// It is set up to import packages "op" and "proc" from Delve (so
+// as to use Delve's DWARF location expression parser), and the
+// "dwtest" package from cmd/link/internal/dwtest (for general
+// DWARF examination/inspection).
+//
+// Given an input Go binary and a function name, this program
+// visits the DWARF for the function and dumps out the location expressions
+// for the function's input parameters on entry to the func. Example:
+//
+// ./dumpdwloc.exe -m ./dumpdwloc.exe -f main.locateFuncDetails
+// 1: in-param "executable" loc="{ [0: S=8 RAX] [1: S=8 RBX] }"
+// 2: in-param "fcn" loc="{ [0: S=8 RCX] [1: S=8 RDI] }"
+// 3: out-param "~r0" loc="<not available>"
+// 4: out-param "~r1" loc="<not available>"
+//
+// Since location expressions can refer to machine registers, dump
+// output for location expressions are architecture-dependent.  The
+// dumper tool currently supports two archs: amd64 and arm64.
+//
+
+import (
+	"debug/dwarf"
+	"debug/elf"
+	"debug/macho"
+	"debug/pe"
+	"dwdumploc/dwtest"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"runtime"
+	"strings"
+
+	"github.com/go-delve/delve/pkg/dwarf/op"
+	"github.com/go-delve/delve/pkg/proc"
+)
+
+var verbflag = flag.Int("v", 0, "Verbose trace output level")
+var fcnflag = flag.String("f", "", "name of function to display")
+var moduleflag = flag.String("m", "", "load module to read")
+
+func verb(vlevel int, s string, a ...interface{}) {
+	if *verbflag >= vlevel {
+		fmt.Fprintf(os.Stderr, s, a...)
+		fmt.Fprintf(os.Stderr, "\n")
+	}
+}
+
+func warn(s string, a ...interface{}) {
+	fmt.Fprintf(os.Stderr, s, a...)
+	fmt.Fprintf(os.Stderr, "\n")
+}
+
+func usage(msg string) {
+	if len(msg) > 0 {
+		fmt.Fprintf(os.Stderr, "error: %s\n", msg)
+	}
+	fmt.Fprintf(os.Stderr, "usage: dwdumploc [flags] -m <binary> -f <fcn>\n")
+	flag.PrintDefaults()
+	os.Exit(2)
+}
+
+type finfo struct {
+	name     string
+	dwOffset dwarf.Offset
+	dwLoPC   uint64
+	dwHiPC   uint64
+	valid    bool
+	dwx      *dwtest.Examiner
+}
+
+// opener defines an interface for opening DWARF info in a Go binary.
+type opener interface {
+	// Open examines binary pointed to by 'path', returning a pointer
+	// to debug/dwarf.Data for it. If something goes wrong opening the
+	// binary (file missing, or maybe not a supported binary) a
+	// suitable error will be returned in the first error return. If
+	// something goes wrong reading the DWARF, a suitable error will
+	// be returned in the second error return.
+	Open(path string) (*dwarf.Data, error, error)
+	Which() string
+}
+
+// Remark: the boilerplate for three scenarios below (Elf, Macho, and
+// PE) seems like it should be an ideal scenario where you could use
+// generics, but my attempts at this were not especially successful.
+// The sticking point is that each of elf.Open/macho.Open etc return a
+// different thing, and I couldn't quite figure out how to get this to
+// work with generics. TODO: make another attempt.
+
+// elfOpener implements the opener interface for ELF
+// (https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) binaries
+//
+type elfOpener struct {
+}
+
+func (eo *elfOpener) Open(path string) (*dwarf.Data, error, error) {
+	f, err := elf.Open(path)
+	if err != nil {
+		return nil, err, nil
+	}
+	d, err := f.DWARF()
+	if err != nil {
+		return nil, nil, err
+	}
+	return d, nil, nil
+}
+
+func (eo *elfOpener) Which() string {
+	return "elf"
+}
+
+// machoOpener implements the opener for macos/darwin Macho-O
+// (https://en.wikipedia.org/wiki/Mach-O) binaries.
+type machoOpener struct {
+}
+
+func (mo *machoOpener) Open(path string) (*dwarf.Data, error, error) {
+	f, err := macho.Open(path)
+	if err != nil {
+		return nil, err, nil
+	}
+	d, err := f.DWARF()
+	if err != nil {
+		return nil, nil, err
+	}
+	return d, nil, nil
+}
+
+func (mo *machoOpener) Which() string {
+	return "macho"
+}
+
+// peOpener implements the opener interface for Windows PE
+// (https://en.wikipedia.org/wiki/Portable_Executable) binaries.
+type peOpener struct {
+}
+
+func (po *peOpener) Open(path string) (*dwarf.Data, error, error) {
+	f, err := pe.Open(path)
+	if err != nil {
+		return nil, err, nil
+	}
+	d, err := f.DWARF()
+	if err != nil {
+		return nil, nil, err
+	}
+	return d, nil, nil
+}
+
+func (po *peOpener) Which() string {
+	return "pe"
+}
+
+// openDwarf tries to open the Go binary 'path' as an ELF file,
+// a Macho file, or a PE file in turn. If an open succeeds, it
+// returns a dwarf.Data for the binary; if they all fail, it returns
+// an error.
+func openDwarf(path string) (*dwarf.Data, error) {
+	eo := elfOpener{}
+	mo := machoOpener{}
+	po := peOpener{}
+	var eoo opener = &eo
+	var moo opener = &mo
+	var poo opener = &po
+	openers := []opener{eoo, moo, poo}
+	postmortem := ""
+	for k, o := range openers {
+		d, errf, errd := o.Open(path)
+		if d != nil {
+			return d, nil
+		}
+		if errd != nil {
+			return nil, errd
+		}
+		postmortem += fmt.Sprintf("\tattempt %d (%s) failed: %v\n", k, o.Which(), errf)
+	}
+	return nil, fmt.Errorf("init failed:\n%s", postmortem)
+}
+
+// locateFuncDetails walks the DWARF for Go binary 'executable'
+// looking for a subprogram DIE for function 'fcn'. If it finds a
+// function of the right name, it fills in info from the DWARF into
+// a "finfo" struct and returns it, or returns an empty struct
+// and an error if something went wrong.
+func locateFuncDetails(executable string, fcn string) (finfo, error) {
+	rrv := finfo{}
+
+	if inf, err := os.Open(executable); err != nil {
+		return rrv, fmt.Errorf("unable to open input executable %s: %v", executable, err)
+	} else {
+		inf.Close()
+	}
+
+	verb(1, "loading DWARF for %s", executable)
+	d, err := openDwarf(executable)
+	if err != nil {
+		return finfo{}, err
+	}
+	verb(1, "DWARF loaded for %s", executable)
+
+	// Construct dwtest.Examiner helper object, to make
+	// inspection of the DWARF easier.
+	rdr := d.Reader()
+	dwx := dwtest.Examiner{}
+	if err := dwx.Populate(rdr); err != nil {
+		return finfo{}, fmt.Errorf("error reading DWARF: %v", err)
+	}
+
+	// Walk DIEs looking for subprogram DIEs.
+	dies := dwx.DIEs()
+	for idx := 0; idx < len(dies); idx++ {
+		die := dies[idx]
+		off := die.Offset
+		if die.Tag == dwarf.TagCompileUnit {
+			if name, ok := die.Val(dwarf.AttrName).(string); ok {
+				verb(2, "compilation unit: %s", name)
+			}
+			continue
+		}
+		if die.Tag != dwarf.TagSubprogram {
+			// TODO: skip children
+			continue
+		}
+		// Name has to match the function we're looking for.
+		name, ok := die.Val(dwarf.AttrName).(string)
+		if !ok {
+			continue
+		}
+		if name != fcn {
+			// TODO: skip children
+			continue
+		}
+
+		verb(1, "found function %s at offset %x", fcn, off)
+		rrv.dwOffset = off
+		if lopc, ok := die.Val(dwarf.AttrLowpc).(uint64); ok {
+			rrv.dwLoPC = lopc
+		} else {
+			return finfo{}, fmt.Errorf("target function seems to be missing LowPC attribute")
+		}
+		if hipc, ok := die.Val(dwarf.AttrHighpc).(uint64); ok {
+			rrv.dwHiPC = hipc
+		} else {
+			return finfo{}, fmt.Errorf("target function seems to be missing HighPC attribute")
+		}
+		rrv.dwx = &dwx
+		rrv.name = fcn
+		rrv.valid = true
+		return rrv, nil
+	}
+	return finfo{}, fmt.Errorf("could not locate target function in DWARF")
+}
+
+var AMD64DWARFRegisters = map[int]string{
+	0:  "RAX",
+	1:  "RDX",
+	2:  "RCX",
+	3:  "RBX",
+	4:  "RSI",
+	5:  "RDI",
+	6:  "RBP",
+	7:  "RSP",
+	8:  "R8",
+	9:  "R9",
+	10: "R10",
+	11: "R11",
+	12: "R12",
+	13: "R13",
+	14: "R14",
+	15: "R15",
+	17: "X0",
+	18: "X1",
+	19: "X2",
+	20: "X3",
+	21: "X4",
+	22: "X5",
+	23: "X6",
+	24: "X7",
+	25: "X8",
+	26: "X9",
+	27: "X10",
+	28: "X11",
+	29: "X12",
+	30: "X13",
+	31: "X14",
+	32: "X15",
+}
+
+var ARM64DWARFRegisters = map[int]string{
+	// int
+	0:  "R0",
+	1:  "R1",
+	2:  "R2",
+	3:  "R3",
+	4:  "R4",
+	5:  "R5",
+	6:  "R6",
+	7:  "R7",
+	8:  "R8",
+	9:  "R9",
+	10: "R10",
+	11: "R11",
+	12: "R12",
+	13: "R13",
+	14: "R14",
+	15: "R15",
+	16: "R16",
+	17: "R17",
+	18: "R18",
+	19: "R19",
+	20: "R20",
+	21: "R21",
+	22: "R22",
+	23: "R23",
+	24: "R24",
+	25: "R25",
+	26: "R26",
+	27: "R27",
+	28: "R28",
+	29: "R29",
+	30: "R30",
+
+	// float
+	64: "F0",
+	65: "F1",
+	66: "F2",
+	67: "F3",
+	68: "F4",
+	69: "F5",
+	70: "F6",
+	71: "F7",
+	72: "F8",
+	73: "F9",
+	74: "F10",
+	75: "F11",
+	76: "F12",
+	77: "F13",
+	78: "F14",
+	79: "F15",
+	80: "F16",
+	81: "F17",
+	82: "F18",
+	83: "F19",
+	84: "F20",
+	85: "F21",
+	86: "F22",
+	87: "F23",
+	88: "F24",
+	89: "F25",
+	90: "F26",
+	91: "F27",
+	92: "F28",
+	93: "F29",
+	94: "F30",
+	95: "F31",
+}
+
+func regString(dwreg int) string {
+	var v string
+	switch runtime.GOARCH {
+	case "amd64":
+		v = AMD64DWARFRegisters[dwreg]
+	case "arm64":
+		v = ARM64DWARFRegisters[dwreg]
+	default:
+		panic(fmt.Sprintf("no support for arch %s", runtime.GOARCH))
+	}
+	if v != "" {
+		return v
+	}
+	return fmt.Sprintf("reg=%d", dwreg)
+}
+
+func pstring(addr int64, pcs []op.Piece, err error) (string, error) {
+	if err != nil {
+		serr := fmt.Sprintf("%s", err)
+		if strings.HasPrefix(serr, "could not find loclist entry") {
+			return "<not available>", nil
+		}
+		return "", err
+	}
+	if pcs == nil {
+		return fmt.Sprintf("addr=%x", addr), nil
+	}
+	r := "{"
+	for k, p := range pcs {
+		r += fmt.Sprintf(" [%d: S=%d", k, p.Size)
+		if p.Kind == op.RegPiece {
+			r += fmt.Sprintf(" %s]", regString(int(p.Val)))
+		} else {
+			r += fmt.Sprintf(" addr=0x%x]", p.Val)
+		}
+	}
+	r += " }"
+	return r, nil
+}
+
+// processParams initializes a 'proc.BinaryInfo' object for the binary
+// in question and then walks the formal parameters of the selected
+// function, invoking the Location method on each param to read its
+// location expression. Results are dumped to stdout, and an error is
+// returned if something goes wrong.
+func processParams(executable string, fi *finfo) error {
+	const _cfa = 0x1000
+	bi := proc.NewBinaryInfo(runtime.GOOS, runtime.GOARCH)
+	if err := bi.LoadBinaryInfo(executable, 0, []string{}); err != nil {
+		return err
+	}
+
+	// Walk subprogram DIE's children.
+	pidx := fi.dwx.IdxFromOffset(fi.dwOffset)
+	childDies := fi.dwx.Children(pidx)
+	idx := 0
+	for _, e := range childDies {
+		if e.Tag != dwarf.TagFormalParameter {
+			continue
+		}
+		if e.Val(dwarf.AttrName) == nil {
+			continue
+		}
+		idx++
+		name := e.Val(dwarf.AttrName).(string)
+		var isrvar bool
+		if e.Tag == dwarf.TagFormalParameter {
+			isrvar = e.Val(dwarf.AttrVarParam).(bool)
+		}
+		addr, pieces, _, err := bi.Location(e, dwarf.AttrLocation, fi.dwLoPC, op.DwarfRegisters{CFA: _cfa, FrameBase: _cfa}, nil)
+		pdump, err := pstring(addr, pieces, err)
+		if err != nil {
+			if fmt.Sprintf("%s", err) == "empty OP stack" {
+				pdump = "<not available>"
+			} else {
+				return fmt.Errorf("bad return from bi.Location at pc 0x%x: %q\n", fi.dwLoPC, err)
+			}
+		}
+		wh := "in"
+		if isrvar {
+			wh = "out"
+		}
+		fmt.Printf("%d: %s-param %q loc=%q\n", idx, wh, name, pdump)
+
+	}
+	return nil
+
+}
+
+// examineFile kicks off the search for DWARF info for 'fcn' within
+// Go binary 'executable', printing results to stdout if possible.
+func examineFile(executable string, fcn string) {
+	verb(1, "examineFile(%s,%s)", executable, fcn)
+	fi, err := locateFuncDetails(executable, fcn)
+	if err != nil {
+		log.Fatalf("error: %v\n", err)
+	}
+	if !fi.valid {
+		log.Fatalf("could not locate target function %s in executable %s", fcn, executable)
+
+	}
+	if err := processParams(executable, &fi); err != nil {
+		log.Fatalf("error: %v\n", err)
+	}
+}
+
+func main() {
+	log.SetFlags(0)
+	log.SetPrefix("dwdumploc: ")
+	flag.Parse()
+	verb(1, "in main")
+	if *fcnflag == "" || *moduleflag == "" {
+		usage("please supply -f and -m options")
+	}
+	if flag.NArg() != 0 {
+		usage("unexpected additional arguments")
+	}
+	examineFile(*moduleflag, *fcnflag)
+	verb(1, "leaving main")
+}
diff --git a/dwtest/testdata/go.mod.txt b/dwtest/testdata/go.mod.txt
new file mode 100644
index 0000000..2140a8c
--- /dev/null
+++ b/dwtest/testdata/go.mod.txt
@@ -0,0 +1,14 @@
+module dwdumploc
+
+go 1.18
+
+require github.com/go-delve/delve v1.7.2
+
+require (
+	github.com/aquasecurity/libbpfgo v0.1.2-0.20210708203834-4928d36fafac // indirect
+	github.com/hashicorp/golang-lru v0.5.4 // indirect
+	github.com/konsorten/go-windows-terminal-sequences v1.0.3 // indirect
+	github.com/sirupsen/logrus v1.6.0 // indirect
+	golang.org/x/arch v0.0.0-20190927153633-4e8777c89be4 // indirect
+	golang.org/x/sys v0.0.0-20210514084401-e8d321eab015 // indirect
+)
diff --git a/dwtest/testdata/go.sum.txt b/dwtest/testdata/go.sum.txt
new file mode 100644
index 0000000..47790ab
--- /dev/null
+++ b/dwtest/testdata/go.sum.txt
@@ -0,0 +1,317 @@
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diff --git a/internal/testenv/testenv.go b/internal/testenv/testenv.go
new file mode 100644
index 0000000..a48d7de
--- /dev/null
+++ b/internal/testenv/testenv.go
@@ -0,0 +1,133 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The helper functions in this package are copied from the original
+// versions from the file of the same name in $GOROOT/src/internal.
+
+package testenv
+
+import (
+	"errors"
+	"fmt"
+	"go/build"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+// HasGoBuild reports whether the current system can build programs
+// with ``go build'' and then run them with os.StartProcess or
+// exec.Command.
+func HasGoBuild() bool {
+	if os.Getenv("GO_GCFLAGS") != "" {
+		// It's too much work to require every caller of the go command
+		// to pass along "-gcflags="+os.Getenv("GO_GCFLAGS").
+		// For now, if $GO_GCFLAGS is set, report that we simply can't
+		// run go build.
+		return false
+	}
+	switch runtime.GOOS {
+	case "android", "js", "ios":
+		return false
+	}
+	return true
+}
+
+// MustHaveGoBuild checks that the current system can build programs with ``go build''
+// and then run them with os.StartProcess or exec.Command.
+// If not, MustHaveGoBuild calls t.Skip with an explanation.
+func MustHaveGoBuild(t testing.TB) {
+	if os.Getenv("GO_GCFLAGS") != "" {
+		t.Skipf("skipping test: 'go build' not compatible with setting $GO_GCFLAGS")
+	}
+	if !HasGoBuild() {
+		t.Skipf("skipping test: 'go build' not available on %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+}
+
+// GoToolPath reports the path to the Go tool.
+// It is a convenience wrapper around GoTool.
+// If the tool is unavailable GoToolPath calls t.Skip.
+// If the tool should be available and isn't, GoToolPath calls t.Fatal.
+func GoToolPath(t testing.TB) string {
+	MustHaveGoBuild(t)
+	path, err := GoTool()
+	if err != nil {
+		t.Fatal(err)
+	}
+	return path
+}
+
+// GoTool reports the path to the Go tool.
+func GoTool() (string, error) {
+	if !HasGoBuild() {
+		return "", errors.New("platform cannot run go tool")
+	}
+	var exeSuffix string
+	if runtime.GOOS == "windows" {
+		exeSuffix = ".exe"
+	}
+	path := filepath.Join(runtime.GOROOT(), "bin", "go"+exeSuffix)
+	if _, err := os.Stat(path); err == nil {
+		return path, nil
+	}
+	goBin, err := exec.LookPath("go" + exeSuffix)
+	if err != nil {
+		return "", errors.New("cannot find go tool: " + err.Error())
+	}
+	return goBin, nil
+}
+
+// HasExternalNetwork reports whether the current system can use
+// external (non-localhost) networks.
+func HasExternalNetwork() bool {
+	return !testing.Short() && runtime.GOOS != "js"
+}
+
+// MustHaveExternalNetwork checks that the current system can use
+// external (non-localhost) networks.
+// If not, MustHaveExternalNetwork calls t.Skip with an explanation.
+func MustHaveExternalNetwork(t testing.TB) {
+	if runtime.GOOS == "js" {
+		t.Skipf("skipping test: no external network on %s", runtime.GOOS)
+	}
+	if testing.Short() {
+		t.Skipf("skipping test: no external network in -short mode")
+	}
+}
+
+// Go1Point returns the x in Go 1.x.
+func Go1Point() int {
+	for i := len(build.Default.ReleaseTags) - 1; i >= 0; i-- {
+		var version int
+		if _, err := fmt.Sscanf(build.Default.ReleaseTags[i], "go1.%d", &version); err != nil {
+			continue
+		}
+		return version
+	}
+	panic("bad release tags")
+}
+
+// Testing is an abstraction of a *testing.T.
+type Testing interface {
+	Skipf(format string, args ...interface{})
+	Fatalf(format string, args ...interface{})
+}
+
+type helperer interface {
+	Helper()
+}
+
+// NeedsGo1Point skips t if the Go version used to run the test is
+// older than 1.x.
+func NeedsGo1Point(t Testing, x int) {
+	if t, ok := t.(helperer); ok {
+		t.Helper()
+	}
+	if Go1Point() < x {
+		t.Skipf("running Go version %q is version 1.%d, older than required 1.%d", runtime.Version(), Go1Point(), x)
+	}
+}