pkg/proc: improve stripped binary support with PIE (#3421)

Take into account static base for PIE binaries.

pkg/proc/bininfo.go

@@ -609,15 +609,15 @@ func (fn *Function) AllPCs(excludeFile string, excludeLine int) ([]uint64, error
 		return fn.cu.lineInfo.AllPCsBetween(fn.Entry, fn.End-1, excludeFile, excludeLine)
 	}
 	var pcs []uint64
-	fnFile, lastLine, _ := fn.cu.image.symTable.PCToLine(fn.Entry)
+	fnFile, lastLine, _ := fn.cu.image.symTable.PCToLine(fn.Entry - fn.cu.image.StaticBase)
-	for pc := fn.Entry; pc < fn.End; pc++ {
+	for pc := fn.Entry - fn.cu.image.StaticBase; pc < fn.End-fn.cu.image.StaticBase; pc++ {
 		f, line, pcfn := fn.cu.image.symTable.PCToLine(pc)
 		if pcfn == nil {
 			continue
 		}
 		if f == fnFile && line > lastLine {
 			lastLine = line
-			pcs = append(pcs, pc)
+			pcs = append(pcs, pc+fn.cu.image.StaticBase)
 		}
 	}
 	return pcs, nil
@@ -762,7 +762,7 @@ func (bi *BinaryInfo) EntryLineForFunc(fn *Function) (string, int) {
 
 func (bi *BinaryInfo) pcToLine(fn *Function, pc uint64) (string, int) {
 	if fn.cu.lineInfo == nil {
-		f, l, _ := fn.cu.image.symTable.PCToLine(pc)
+		f, l, _ := fn.cu.image.symTable.PCToLine(pc - fn.cu.image.StaticBase)
 		return f, l
 	}
 	f, l := fn.cu.lineInfo.PCToLine(fn.Entry, pc)
@@ -1461,7 +1461,7 @@ func loadBinaryInfoElf(bi *BinaryInfo, image *Image, path string, addr uint64, w
 			for _, f := range image.symTable.Funcs {
 				cu := &compileUnit{}
 				cu.image = image
-				fn := Function{Name: f.Name, Entry: f.Entry, End: f.End, cu: cu}
+				fn := Function{Name: f.Name, Entry: f.Entry + image.StaticBase, End: f.End + image.StaticBase, cu: cu}
 				bi.Functions = append(bi.Functions, fn)
 			}
 			for f := range image.symTable.Files {

pkg/proc/pclntab.go

@@ -1,40 +1,11 @@
 package proc
 
 import (
-	"bytes"
-	"debug/buildinfo"
 	"debug/elf"
 	"debug/gosym"
-	"encoding/binary"
 	"fmt"
-	"strings"
 )
 
-// From go/src/debug/gosym/pclntab.go
-const (
-	go12magic  = 0xfffffffb
-	go116magic = 0xfffffffa
-	go118magic = 0xfffffff0
-	go120magic = 0xfffffff1
-)
-
-// Select the magic number based on the Go version
-func magicNumber(goVersion string) []byte {
-	bs := make([]byte, 4)
-	var magic uint32
-	if strings.Compare(goVersion, "go1.20") >= 0 {
-		magic = go120magic
-	} else if strings.Compare(goVersion, "go1.18") >= 0 {
-		magic = go118magic
-	} else if strings.Compare(goVersion, "go1.16") >= 0 {
-		magic = go116magic
-	} else {
-		magic = go12magic
-	}
-	binary.LittleEndian.PutUint32(bs, magic)
-	return bs
-}
-
 func readPcLnTableElf(exe *elf.File, path string) (*gosym.Table, error) {
 	// Default section label is .gopclntab
 	sectionLabel := ".gopclntab"
@@ -42,7 +13,7 @@ func readPcLnTableElf(exe *elf.File, path string) (*gosym.Table, error) {
 	section := exe.Section(sectionLabel)
 	if section == nil {
 		// binary may be built with -pie
-		sectionLabel = ".data.rel.ro"
+		sectionLabel = ".data.rel.ro.gopclntab"
 		section = exe.Section(sectionLabel)
 		if section == nil {
 			return nil, fmt.Errorf("could not read section .gopclntab")
@@ -53,17 +24,6 @@ func readPcLnTableElf(exe *elf.File, path string) (*gosym.Table, error) {
 		return nil, fmt.Errorf("found section but could not read .gopclntab")
 	}
 
-	bi, err := buildinfo.ReadFile(path)
-	if err != nil {
-		return nil, err
-	}
-
-	// Find .gopclntab by magic number even if there is no section label
-	magic := magicNumber(bi.GoVersion)
-	pclntabIndex := bytes.Index(tableData, magic)
-	if pclntabIndex >= 0 {
-		tableData = tableData[pclntabIndex:]
-	}
 	addr := exe.Section(".text").Addr
 	lineTable := gosym.NewLineTable(tableData, addr)
 	symTable, err := gosym.NewTable([]byte{}, lineTable)

pkg/proc/proc_test.go

@@ -3169,7 +3169,6 @@ func TestDebugStripped(t *testing.T) {
 	// Currently only implemented for Linux ELF executables.
 	// TODO(derekparker): Add support for Mach-O and PE.
 	skipUnlessOn(t, "linux only", "linux")
-	skipOn(t, "does not work with PIE", "pie")
 	withTestProcessArgs("testnextprog", t, "", []string{}, protest.LinkStrip, func(p *proc.Target, grp *proc.TargetGroup, f protest.Fixture) {
 		setFunctionBreakpoint(p, t, "main.main")
 		assertNoError(grp.Continue(), t, "Continue")