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cmd/asm, cmd/link, runtime: introduce FuncInfo flag bits

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The runtime traceback code has its own definition of which functions
mark the top frame of a stack, separate from the TOPFRAME bits that
exist in the assembly and are passed along in DWARF information.
It's error-prone and redundant to have two different sources of truth.
This CL provides the actual TOPFRAME bits to the runtime, so that
the runtime can use those bits instead of reinventing its own category.

This CL also adds a new bit, SPWRITE, which marks functions that
write directly to SP (anything but adding and subtracting constants).
Such functions must stop a traceback, because the traceback has no
way to rederive the SP on entry. Again, the runtime has its own definition
which is mostly correct, but also missing some functions. During ordinary
goroutine context switches, such functions do not appear on the stack,
so the incompleteness in the runtime usually doesn't matter.
But profiling signals can arrive at any moment, and the runtime may
crash during traceback if it attempts to unwind an SP-writing frame
and gets out-of-sync with the actual stack. The runtime contains code
to try to detect likely candidates but again it is incomplete.
Deriving the SPWRITE bit automatically from the actual assembly code
provides the complete truth, and passing it to the runtime lets the
runtime use it.

This CL is part of a stack adding windows/arm64
support (#36439), intended to land in the Go 1.17 cycle.
This CL is, however, not windows/arm64-specific.
It is cleanup meant to make the port (and future ports) easier.

Change-Id: I227f53b23ac5b3dabfcc5e8ee3f00df4e113cf58
Reviewed-on: https://go-review.googlesource.com/c/go/+/288800
Trust: Russ Cox <rsc@golang.org>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Russ Cox 2021-01-28 15:21:33 -05:00
parent aa0388f2ed
commit 4dd77bdc91
24 changed files with 209 additions and 101 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/cmd/asm/internal/asm/endtoend_test.go
View file

@ -36,6 +36,7 @@ func testEndToEnd(t *testing.T, goarch, file string) {
var ok bool
testOut = new(bytes.Buffer) // The assembler writes test output to this buffer.
ctxt.Bso = bufio.NewWriter(os.Stdout)
ctxt.IsAsm = true
defer ctxt.Bso.Flush()
failed := false
ctxt.DiagFunc = func(format string, args ...interface{}) {
@ -278,6 +279,7 @@ func testErrors(t *testing.T, goarch, file string) {
var ok bool
testOut = new(bytes.Buffer) // The assembler writes test output to this buffer.
ctxt.Bso = bufio.NewWriter(os.Stdout)
ctxt.IsAsm = true
defer ctxt.Bso.Flush()
failed := false
var errBuf bytes.Buffer

2
src/cmd/asm/internal/flags/flags.go
View file

@ -32,11 +32,13 @@ var (
D MultiFlag
I MultiFlag
PrintOut int
DebugV bool
)
func init() {
flag.Var(&D, "D", "predefined symbol with optional simple value -D=identifier=value; can be set multiple times")
flag.Var(&I, "I", "include directory; can be set multiple times")
flag.BoolVar(&DebugV, "v", false, "print debug output")
objabi.AddVersionFlag() // -V
objabi.Flagcount("S", "print assembly and machine code", &PrintOut)
}

1
src/cmd/asm/main.go
View file

@ -36,6 +36,7 @@ func main() {
ctxt := obj.Linknew(architecture.LinkArch)
ctxt.Debugasm = flags.PrintOut
ctxt.Debugvlog = flags.DebugV
ctxt.Flag_dynlink = *flags.Dynlink
ctxt.Flag_linkshared = *flags.Linkshared
ctxt.Flag_shared = *flags.Shared || *flags.Dynlink

2
src/cmd/compile/internal/test/fixedbugs_test.go
View file

@ -75,7 +75,7 @@ func TestIssue16214(t *testing.T) {
cmd := exec.Command(testenv.GoToolPath(t), "tool", "compile", "-S", "-o", filepath.Join(dir, "out.o"), src)
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("fail to run go tool compile: %v", err)
t.Fatalf("go tool compile: %v\n%s", err, out)
}
if strings.Contains(string(out), "unknown line number") {

4
src/cmd/compile/internal/test/global_test.go
View file

@ -50,7 +50,7 @@ func main() {
cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", dst, src)
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("could not build target: %v", err)
t.Fatalf("could not build target: %v\n%s", err, out)
}
// Check destination to see if scanf code was included.
@ -95,7 +95,7 @@ func main() {
cmd := exec.Command(testenv.GoToolPath(t), "build", "-gcflags", "-S", "-o", filepath.Join(dir, "test"), src)
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("could not build target: %v", err)
t.Fatalf("could not build target: %v\n%s", err, out)
}
patterns := []string{

60
src/cmd/internal/goobj/funcinfo.go
View file

@ -19,9 +19,10 @@ type CUFileIndex uint32
//
// TODO: make each pcdata a separate symbol?
type FuncInfo struct {
Args uint32
Locals uint32
FuncID objabi.FuncID
Args uint32
Locals uint32
FuncID objabi.FuncID
FuncFlag objabi.FuncFlag
Pcsp SymRef
Pcfile SymRef
@ -35,6 +36,9 @@ type FuncInfo struct {
}
func (a *FuncInfo) Write(w *bytes.Buffer) {
writeUint8 := func(x uint8) {
w.WriteByte(x)
}
var b [4]byte
writeUint32 := func(x uint32) {
binary.LittleEndian.PutUint32(b[:], x)
@ -47,8 +51,10 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
writeUint32(a.Args)
writeUint32(a.Locals)
writeUint32(uint32(a.FuncID))
writeUint8(uint8(a.FuncID))
writeUint8(uint8(a.FuncFlag))
writeUint8(0) // pad to uint32 boundary
writeUint8(0)
writeSymRef(a.Pcsp)
writeSymRef(a.Pcfile)
writeSymRef(a.Pcline)
@ -72,46 +78,6 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
}
}
func (a *FuncInfo) Read(b []byte) {
readUint32 := func() uint32 {
x := binary.LittleEndian.Uint32(b)
b = b[4:]
return x
}
readSymIdx := func() SymRef {
return SymRef{readUint32(), readUint32()}
}
a.Args = readUint32()
a.Locals = readUint32()
a.FuncID = objabi.FuncID(readUint32())
a.Pcsp = readSymIdx()
a.Pcfile = readSymIdx()
a.Pcline = readSymIdx()
a.Pcinline = readSymIdx()
a.Pcdata = make([]SymRef, readUint32())
for i := range a.Pcdata {
a.Pcdata[i] = readSymIdx()
}
funcdataofflen := readUint32()
a.Funcdataoff = make([]uint32, funcdataofflen)
for i := range a.Funcdataoff {
a.Funcdataoff[i] = readUint32()
}
filelen := readUint32()
a.File = make([]CUFileIndex, filelen)
for i := range a.File {
a.File[i] = CUFileIndex(readUint32())
}
inltreelen := readUint32()
a.InlTree = make([]InlTreeNode, inltreelen)
for i := range a.InlTree {
b = a.InlTree[i].Read(b)
}
}
// FuncInfoLengths is a cache containing a roadmap of offsets and
// lengths for things within a serialized FuncInfo. Each length field
// stores the number of items (e.g. files, inltree nodes, etc), and the
@ -159,7 +125,9 @@ func (*FuncInfo) ReadArgs(b []byte) uint32 { return binary.LittleEndian.Uint32(b
func (*FuncInfo) ReadLocals(b []byte) uint32 { return binary.LittleEndian.Uint32(b[4:]) }
func (*FuncInfo) ReadFuncID(b []byte) uint32 { return binary.LittleEndian.Uint32(b[8:]) }
func (*FuncInfo) ReadFuncID(b []byte) objabi.FuncID { return objabi.FuncID(b[8]) }
func (*FuncInfo) ReadFuncFlag(b []byte) objabi.FuncFlag { return objabi.FuncFlag(b[9]) }
func (*FuncInfo) ReadPcsp(b []byte) SymRef {
return SymRef{binary.LittleEndian.Uint32(b[12:]), binary.LittleEndian.Uint32(b[16:])}

2
src/cmd/internal/goobj/objfile.go
View file

@ -298,7 +298,6 @@ const (
SymFlagNoSplit
SymFlagReflectMethod
SymFlagGoType
SymFlagTopFrame
)
// Sym.Flag2
@ -332,7 +331,6 @@ func (s *Sym) Leaf() bool { return s.Flag()&SymFlagLeaf != 0 }
func (s *Sym) NoSplit() bool { return s.Flag()&SymFlagNoSplit != 0 }
func (s *Sym) ReflectMethod() bool { return s.Flag()&SymFlagReflectMethod != 0 }
func (s *Sym) IsGoType() bool { return s.Flag()&SymFlagGoType != 0 }
func (s *Sym) TopFrame() bool { return s.Flag()&SymFlagTopFrame != 0 }
func (s *Sym) UsedInIface() bool { return s.Flag2()&SymFlagUsedInIface != 0 }
func (s *Sym) IsItab() bool { return s.Flag2()&SymFlagItab != 0 }

16
src/cmd/internal/obj/arm/obj5.go
View file

@ -34,6 +34,7 @@ import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"log"
)
var progedit_tlsfallback *obj.LSym
@ -613,6 +614,21 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
p.From.Reg = REGSP
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := c.cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
}

16
src/cmd/internal/obj/arm64/obj7.go
View file

@ -35,6 +35,7 @@ import (
"cmd/internal/objabi"
"cmd/internal/src"
"cmd/internal/sys"
"log"
"math"
)
@ -970,6 +971,21 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
p = q5
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := c.cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
}

23
src/cmd/internal/obj/link.go
View file

@ -454,6 +454,7 @@ type FuncInfo struct {
Locals int32
Align int32
FuncID objabi.FuncID
FuncFlag objabi.FuncFlag
Text *Prog
Autot map[*LSym]struct{}
Pcln Pcln
@ -619,10 +620,6 @@ const (
// target of an inline during compilation
AttrWasInlined
// TopFrame means that this function is an entry point and unwinders should not
// keep unwinding beyond this frame.
AttrTopFrame
// Indexed indicates this symbol has been assigned with an index (when using the
// new object file format).
AttrIndexed
@ -663,7 +660,6 @@ func (a *Attribute) NeedCtxt() bool { return a.load()&AttrNeedCtxt !=
func (a *Attribute) NoFrame() bool { return a.load()&AttrNoFrame != 0 }
func (a *Attribute) Static() bool { return a.load()&AttrStatic != 0 }
func (a *Attribute) WasInlined() bool { return a.load()&AttrWasInlined != 0 }
func (a *Attribute) TopFrame() bool { return a.load()&AttrTopFrame != 0 }
func (a *Attribute) Indexed() bool { return a.load()&AttrIndexed != 0 }
func (a *Attribute) UsedInIface() bool { return a.load()&AttrUsedInIface != 0 }
func (a *Attribute) ContentAddressable() bool { return a.load()&AttrContentAddressable != 0 }
@ -713,14 +709,13 @@ var textAttrStrings = [...]struct {
{bit: AttrNoFrame, s: "NOFRAME"},
{bit: AttrStatic, s: "STATIC"},
{bit: AttrWasInlined, s: ""},
{bit: AttrTopFrame, s: "TOPFRAME"},
{bit: AttrIndexed, s: ""},
{bit: AttrContentAddressable, s: ""},
{bit: AttrABIWrapper, s: "ABIWRAPPER"},
}
// TextAttrString formats a for printing in as part of a TEXT prog.
func (a Attribute) TextAttrString() string {
// String formats a for printing in as part of a TEXT prog.
func (a Attribute) String() string {
var s string
for _, x := range textAttrStrings {
if a&x.bit != 0 {
@ -746,6 +741,18 @@ func (a Attribute) TextAttrString() string {
return s
}
// TextAttrString formats the symbol attributes for printing in as part of a TEXT prog.
func (s *LSym) TextAttrString() string {
attr := s.Attribute.String()
if s.Func().FuncFlag&objabi.FuncFlag_TOPFRAME != 0 {
if attr != "" {
attr += "|"
}
attr += "TOPFRAME"
}
return attr
}
func (s *LSym) String() string {
return s.Name
}

16
src/cmd/internal/obj/mips/obj0.go
View file

@ -35,6 +35,7 @@ import (
"cmd/internal/sys"
"encoding/binary"
"fmt"
"log"
"math"
)
@ -536,6 +537,21 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
p.From.Reg = REGSP
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := c.cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
if c.ctxt.Arch.Family == sys.MIPS {

12
src/cmd/internal/obj/objfile.go
View file

@ -330,9 +330,6 @@ func (w *writer) Sym(s *LSym) {
if s.ReflectMethod() {
flag |= goobj.SymFlagReflectMethod
}
if s.TopFrame() {
flag |= goobj.SymFlagTopFrame
}
if strings.HasPrefix(s.Name, "type.") && s.Name[5] != '.' && s.Type == objabi.SRODATA {
flag |= goobj.SymFlagGoType
}
@ -673,9 +670,10 @@ func genFuncInfoSyms(ctxt *Link) {
continue
}
o := goobj.FuncInfo{
Args: uint32(fn.Args),
Locals: uint32(fn.Locals),
FuncID: objabi.FuncID(fn.FuncID),
Args: uint32(fn.Args),
Locals: uint32(fn.Locals),
FuncID: fn.FuncID,
FuncFlag: fn.FuncFlag,
}
pc := &fn.Pcln
o.Pcsp = makeSymRef(preparePcSym(pc.Pcsp))
@ -788,7 +786,7 @@ func (ctxt *Link) writeSymDebugNamed(s *LSym, name string) {
if s.NoSplit() {
fmt.Fprintf(ctxt.Bso, "nosplit ")
}
if s.TopFrame() {
if s.Func() != nil && s.Func().FuncFlag&objabi.FuncFlag_TOPFRAME != 0 {
fmt.Fprintf(ctxt.Bso, "topframe ")
}
fmt.Fprintf(ctxt.Bso, "size=%d", s.Size)

10
src/cmd/internal/obj/plist.go
View file

@ -134,6 +134,7 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int) {
}
name := strings.Replace(s.Name, "\"\"", ctxt.Pkgpath, -1)
s.Func().FuncID = objabi.GetFuncID(name, flag&WRAPPER != 0)
s.Func().FuncFlag = toFuncFlag(flag)
s.Set(AttrOnList, true)
s.Set(AttrDuplicateOK, flag&DUPOK != 0)
s.Set(AttrNoSplit, flag&NOSPLIT != 0)
@ -142,7 +143,6 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int) {
s.Set(AttrABIWrapper, flag&ABIWRAPPER != 0)
s.Set(AttrNeedCtxt, flag&NEEDCTXT != 0)
s.Set(AttrNoFrame, flag&NOFRAME != 0)
s.Set(AttrTopFrame, flag&TOPFRAME != 0)
s.Type = objabi.STEXT
ctxt.Text = append(ctxt.Text, s)
@ -150,6 +150,14 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int) {
ctxt.dwarfSym(s)
}
func toFuncFlag(flag int) objabi.FuncFlag {
var out objabi.FuncFlag
if flag&TOPFRAME != 0 {
out |= objabi.FuncFlag_TOPFRAME
}
return out
}
func (ctxt *Link) Globl(s *LSym, size int64, flag int) {
if s.OnList() {
ctxt.Diag("symbol %s listed multiple times", s.Name)

16
src/cmd/internal/obj/ppc64/obj9.go
View file

@ -34,6 +34,7 @@ import (
"cmd/internal/objabi"
"cmd/internal/src"
"cmd/internal/sys"
"log"
)
func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
@ -984,6 +985,21 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
p.From.Reg = REGSP
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 && p.As != ACMPU {
f := c.cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
}

16
src/cmd/internal/obj/riscv/obj.go
View file

@ -25,6 +25,7 @@ import (
"cmd/internal/objabi"
"cmd/internal/sys"
"fmt"
"log"
)
func buildop(ctxt *obj.Link) {}
@ -716,6 +717,21 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
p.Spadj = int32(-p.From.Offset)
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
f.FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
// Rewrite MOV pseudo-instructions. This cannot be done in

16
src/cmd/internal/obj/s390x/objz.go
View file

@ -33,6 +33,7 @@ import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"log"
"math"
)
@ -545,6 +546,21 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
p.From.Reg = REGSP
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := c.cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s\n", c.cursym.Name)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
if wasSplit {
c.stacksplitPost(pLast, pPre, pPreempt, autosize) // emit post part of split check

2
src/cmd/internal/obj/util.go
View file

@ -187,7 +187,7 @@ func (p *Prog) WriteInstructionString(w io.Writer) {
// In short, print one of these two:
// TEXT foo(SB), DUPOK|NOSPLIT, $0
// TEXT foo(SB), $0
s := p.From.Sym.Attribute.TextAttrString()
s := p.From.Sym.TextAttrString()
if s != "" {
fmt.Fprintf(w, "%s%s", sep, s)
sep = ", "

15
src/cmd/internal/obj/x86/obj6.go
View file

@ -35,6 +35,7 @@ import (
"cmd/internal/objabi"
"cmd/internal/src"
"cmd/internal/sys"
"log"
"math"
"strings"
)
@ -839,6 +840,20 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
switch p.As {
default:
if p.To.Type == obj.TYPE_REG && p.To.Reg == REG_SP && p.As != ACMPL && p.As != ACMPQ {
f := cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
f.FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
continue
case APUSHL, APUSHFL:

11
src/cmd/internal/objabi/funcid.go
View file

@ -6,13 +6,22 @@ package objabi
import "strings"
// A FuncFlag records bits about a function, passed to the runtime.
type FuncFlag uint8
// Note: This list must match the list in runtime/symtab.go.
const (
FuncFlag_TOPFRAME = 1 << iota
FuncFlag_SPWRITE
)
// A FuncID identifies particular functions that need to be treated
// specially by the runtime.
// Note that in some situations involving plugins, there may be multiple
// copies of a particular special runtime function.
// Note: this list must match the list in runtime/symtab.go.
type FuncID uint8
// Note: this list must match the list in runtime/symtab.go.
const (
FuncID_normal FuncID = iota // not a special function
FuncID_asmcgocall

4
src/cmd/link/internal/ld/dwarf.go
View file

@ -1454,7 +1454,7 @@ func (d *dwctxt) writeframes(fs loader.Sym) dwarfSecInfo {
// Emit a FDE, Section 6.4.1.
// First build the section contents into a byte buffer.
deltaBuf = deltaBuf[:0]
if haslr && d.ldr.AttrTopFrame(fn) {
if haslr && fi.TopFrame() {
// Mark the link register as having an undefined value.
// This stops call stack unwinders progressing any further.
// TODO: similar mark on non-LR architectures.
@ -1480,7 +1480,7 @@ func (d *dwctxt) writeframes(fs loader.Sym) dwarfSecInfo {
spdelta += int64(d.arch.PtrSize)
}
if haslr && !d.ldr.AttrTopFrame(fn) {
if haslr && !fi.TopFrame() {
// TODO(bryanpkc): This is imprecise. In general, the instruction
// that stores the return address to the stack frame is not the
// same one that allocates the frame.

9
src/cmd/link/internal/ld/pcln.go
View file

@ -796,7 +796,14 @@ func writeFuncs(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, inlSym
}
off = uint32(sb.SetUint8(ctxt.Arch, int64(off), uint8(funcID)))
off += 2 // pad
// flag uint8
var flag objabi.FuncFlag
if fi.Valid() {
flag = fi.FuncFlag()
}
off = uint32(sb.SetUint8(ctxt.Arch, int64(off), uint8(flag)))
off += 1 // pad
// nfuncdata must be the final entry.
funcdata, funcdataoff = funcData(fi, 0, funcdata, funcdataoff)

37
src/cmd/link/internal/loader/loader.go
View file

@ -241,7 +241,6 @@ type Loader struct {
attrExternal Bitmap // external symbols, indexed by ext sym index
attrReadOnly map[Sym]bool // readonly data for this sym
attrTopFrame map[Sym]struct{} // top frame symbols
attrSpecial map[Sym]struct{} // "special" frame symbols
attrCgoExportDynamic map[Sym]struct{} // "cgo_export_dynamic" symbols
attrCgoExportStatic map[Sym]struct{} // "cgo_export_static" symbols
@ -349,7 +348,6 @@ func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorRepor
plt: make(map[Sym]int32),
got: make(map[Sym]int32),
dynid: make(map[Sym]int32),
attrTopFrame: make(map[Sym]struct{}),
attrSpecial: make(map[Sym]struct{}),
attrCgoExportDynamic: make(map[Sym]struct{}),
attrCgoExportStatic: make(map[Sym]struct{}),
@ -1009,24 +1007,6 @@ func (l *Loader) SetAttrExternal(i Sym, v bool) {
}
}
// AttrTopFrame returns true for a function symbol that is an entry
// point, meaning that unwinders should stop when they hit this
// function.
func (l *Loader) AttrTopFrame(i Sym) bool {
_, ok := l.attrTopFrame[i]
return ok
}
// SetAttrTopFrame sets the "top frame" property for a symbol (see
// AttrTopFrame).
func (l *Loader) SetAttrTopFrame(i Sym, v bool) {
if v {
l.attrTopFrame[i] = struct{}{}
} else {
delete(l.attrTopFrame, i)
}
}
// AttrSpecial returns true for a symbols that do not have their
// address (i.e. Value) computed by the usual mechanism of
// data.go:dodata() & data.go:address().
@ -1905,7 +1885,11 @@ func (fi *FuncInfo) Locals() int {
}
func (fi *FuncInfo) FuncID() objabi.FuncID {
return objabi.FuncID((*goobj.FuncInfo)(nil).ReadFuncID(fi.data))
return (*goobj.FuncInfo)(nil).ReadFuncID(fi.data)
}
func (fi *FuncInfo) FuncFlag() objabi.FuncFlag {
return (*goobj.FuncInfo)(nil).ReadFuncFlag(fi.data)
}
func (fi *FuncInfo) Pcsp() Sym {
@ -1992,6 +1976,13 @@ func (fi *FuncInfo) File(k int) goobj.CUFileIndex {
return (*goobj.FuncInfo)(nil).ReadFile(fi.data, fi.lengths.FileOff, uint32(k))
}
// TopFrame returns true if the function associated with this FuncInfo
// is an entry point, meaning that unwinders should stop when they hit
// this function.
func (fi *FuncInfo) TopFrame() bool {
return (fi.FuncFlag() & objabi.FuncFlag_TOPFRAME) != 0
}
type InlTreeNode struct {
Parent int32
File goobj.CUFileIndex
@ -2151,9 +2142,6 @@ func (st *loadState) preloadSyms(r *oReader, kind int) {
}
gi := st.addSym(name, v, r, i, kind, osym)
r.syms[i] = gi
if osym.TopFrame() {
l.SetAttrTopFrame(gi, true)
}
if osym.Local() {
l.SetAttrLocal(gi, true)
}
@ -2411,7 +2399,6 @@ func (l *Loader) CopyAttributes(src Sym, dst Sym) {
// when copying attributes from a dupOK ABI wrapper symbol to
// the real target symbol (which may not be marked dupOK).
}
l.SetAttrTopFrame(dst, l.AttrTopFrame(src))
l.SetAttrSpecial(dst, l.AttrSpecial(src))
l.SetAttrCgoExportDynamic(dst, l.AttrCgoExportDynamic(src))
l.SetAttrCgoExportStatic(dst, l.AttrCgoExportStatic(src))

9
src/runtime/runtime2.go
View file

@ -833,10 +833,11 @@ type _func struct {
pcfile uint32
pcln uint32
npcdata uint32
cuOffset uint32 // runtime.cutab offset of this function's CU
funcID funcID // set for certain special runtime functions
_ [2]byte // pad
nfuncdata uint8 // must be last
cuOffset uint32 // runtime.cutab offset of this function's CU
funcID funcID // set for certain special runtime functions
flag funcFlag
_ [1]byte // pad
nfuncdata uint8 // must be last, must end on a uint32-aligned boundary
}
// Pseudo-Func that is returned for PCs that occur in inlined code.

9
src/runtime/symtab.go
View file

@ -332,6 +332,15 @@ const (
funcID_wrapper // any autogenerated code (hash/eq algorithms, method wrappers, etc.)
)
// A FuncFlag holds bits about a function.
// This list must match the list in cmd/internal/objabi/funcid.go.
type funcFlag uint8
const (
funcFlag_TOPFRAME funcFlag = 1 << iota
funcFlag_SPWRITE
)
// pcHeader holds data used by the pclntab lookups.
type pcHeader struct {
magic uint32 // 0xFFFFFFFA