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cmd/link, runtime, debug/gosym: move pclntab magic to internal/abi

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Change-Id: I2d3c41b0e61b994d7b04bd16a791fd226dc45269
Reviewed-on: https://go-review.googlesource.com/c/go/+/720302
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Ian Lance Taylor 2025-11-13 13:01:14 -08:00
parent 312b2034a4
commit 43cfd785e7
4 changed files with 54 additions and 25 deletions
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2
src/cmd/link/internal/ld/pcln.go
View file

@ -261,7 +261,7 @@ func (state *pclntab) generatePCHeader(ctxt *Link) {
// Write header.
// Keep in sync with runtime/symtab.go:pcHeader and package debug/gosym.
header.SetUint32(ctxt.Arch, 0, 0xfffffff1)
header.SetUint32(ctxt.Arch, 0, uint32(abi.CurrentPCLnTabMagic))
header.SetUint8(ctxt.Arch, 6, uint8(ctxt.Arch.MinLC))
header.SetUint8(ctxt.Arch, 7, uint8(ctxt.Arch.PtrSize))
off := header.SetUint(ctxt.Arch, 8, uint64(state.nfunc))

33
src/debug/gosym/pclntab.go
View file

@ -11,6 +11,7 @@ package gosym
import (
"bytes"
"encoding/binary"
"internal/abi"
"sort"
"sync"
)
@ -174,13 +175,6 @@ func (t *LineTable) isGo12() bool {
return t.version >= ver12
}
const (
go12magic = 0xfffffffb
go116magic = 0xfffffffa
go118magic = 0xfffffff0
go120magic = 0xfffffff1
)
// uintptr returns the pointer-sized value encoded at b.
// The pointer size is dictated by the table being read.
func (t *LineTable) uintptr(b []byte) uint64 {
@ -220,24 +214,29 @@ func (t *LineTable) parsePclnTab() {
}
var possibleVersion version
leMagic := binary.LittleEndian.Uint32(t.Data)
beMagic := binary.BigEndian.Uint32(t.Data)
// The magic numbers are chosen such that reading the value with
// a different endianness does not result in the same value.
// That lets us the magic number to determine the endianness.
leMagic := abi.PCLnTabMagic(binary.LittleEndian.Uint32(t.Data))
beMagic := abi.PCLnTabMagic(binary.BigEndian.Uint32(t.Data))
switch {
case leMagic == go12magic:
case leMagic == abi.Go12PCLnTabMagic:
t.binary, possibleVersion = binary.LittleEndian, ver12
case beMagic == go12magic:
case beMagic == abi.Go12PCLnTabMagic:
t.binary, possibleVersion = binary.BigEndian, ver12
case leMagic == go116magic:
case leMagic == abi.Go116PCLnTabMagic:
t.binary, possibleVersion = binary.LittleEndian, ver116
case beMagic == go116magic:
case beMagic == abi.Go116PCLnTabMagic:
t.binary, possibleVersion = binary.BigEndian, ver116
case leMagic == go118magic:
case leMagic == abi.Go118PCLnTabMagic:
t.binary, possibleVersion = binary.LittleEndian, ver118
case beMagic == go118magic:
case beMagic == abi.Go118PCLnTabMagic:
t.binary, possibleVersion = binary.BigEndian, ver118
case leMagic == go120magic:
case leMagic == abi.Go120PCLnTabMagic:
t.binary, possibleVersion = binary.LittleEndian, ver120
case beMagic == go120magic:
case beMagic == abi.Go120PCLnTabMagic:
t.binary, possibleVersion = binary.BigEndian, ver120
default:
return

30
src/internal/abi/symtab.go
View file

@ -4,6 +4,36 @@
package abi
// PCLnTabMagic is the version at the start of the PC/line table.
// This is the start of the .pclntab section, and is also runtime.pcHeader.
// The magic numbers are chosen such that reading the value with
// a different endianness does not result in the same value.
// That lets us the magic number to determine the endianness.
type PCLnTabMagic uint32
const (
// Initial PCLnTabMagic value used in Go 1.2 through Go 1.15.
Go12PCLnTabMagic PCLnTabMagic = 0xfffffffb
// PCLnTabMagic value used in Go 1.16 through Go 1.17.
// Several fields added to header (CL 241598).
Go116PCLnTabMagic PCLnTabMagic = 0xfffffffa
// PCLnTabMagic value used in Go 1.18 through Go 1.19.
// Entry PC of func data changed from address to offset (CL 351463).
Go118PCLnTabMagic PCLnTabMagic = 0xfffffff0
// PCLnTabMagic value used in Go 1.20 and later.
// A ":" was added to generated symbol names (#37762).
Go120PCLnTabMagic PCLnTabMagic = 0xfffffff1
// CurrentPCLnTabMagic is the value emitted by the current toolchain.
// This is written by the linker to the pcHeader and read by the
// runtime and debug/gosym (and external tools like Delve).
//
// Change this value when updating the pclntab version.
// Changing this exported value is OK because is an
// internal package.
CurrentPCLnTabMagic = Go120PCLnTabMagic
)
// A FuncFlag records bits about a function, passed to the runtime.
type FuncFlag uint8

14
src/runtime/symtab.go
View file

@ -374,12 +374,12 @@ func (f *_func) funcInfo() funcInfo {
// pcHeader holds data used by the pclntab lookups.
type pcHeader struct {
magic uint32 // 0xFFFFFFF1
pad1, pad2 uint8 // 0,0
minLC uint8 // min instruction size
ptrSize uint8 // size of a ptr in bytes
nfunc int // number of functions in the module
nfiles uint // number of entries in the file tab
magic abi.PCLnTabMagic // abi.Go1NNPcLnTabMagic
pad1, pad2 uint8 // 0,0
minLC uint8 // min instruction size
ptrSize uint8 // size of a ptr in bytes
nfunc int // number of functions in the module
nfiles uint // number of entries in the file tab
// The next field used to be textStart. This is no longer stored
// as it requires a relocation. Code should use the moduledata text
@ -623,7 +623,7 @@ const debugPcln = false
func moduledataverify1(datap *moduledata) {
// Check that the pclntab's format is valid.
hdr := datap.pcHeader
if hdr.magic != 0xfffffff1 || hdr.pad1 != 0 || hdr.pad2 != 0 ||
if hdr.magic != abi.CurrentPCLnTabMagic || hdr.pad1 != 0 || hdr.pad2 != 0 ||
hdr.minLC != sys.PCQuantum || hdr.ptrSize != goarch.PtrSize {
println("runtime: pcHeader: magic=", hex(hdr.magic), "pad1=", hdr.pad1, "pad2=", hdr.pad2,
"minLC=", hdr.minLC, "ptrSize=", hdr.ptrSize, "pluginpath=", datap.pluginpath)