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// Copyright 2022 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 gosym
import (
"encoding/binary"
"io"
"strings"
sv "golang.org/x/mod/semver"
"golang.org/x/vuln/internal/semver"
)
const (
funcSymNameGo119Lower string = "go.func.*"
funcSymNameGo120 string = "go:func.*"
)
// FuncSymName returns symbol name for Go functions used in binaries
// based on Go version. Supported Go versions are 1.18 and greater.
// If the go version is unreadable it assumes that it is a newer version
// and returns the symbol name for go version 1.20 or greater.
func FuncSymName(goVersion string) string {
// Support devel goX.Y...
v := strings.TrimPrefix(goVersion, "devel ")
v = semver.GoTagToSemver(v)
mm := sv.MajorMinor(v)
if sv.Compare(mm, "v1.20") >= 0 || mm == "" {
return funcSymNameGo120
} else if sv.Compare(mm, "v1.18") >= 0 {
return funcSymNameGo119Lower
}
return ""
}
// Additions to the original package from cmd/internal/objabi/funcdata.go
const (
pcdata_InlTreeIndex = 2
funcdata_InlTree = 3
)
// InlineTree returns the inline tree for Func f as a sequence of InlinedCalls.
// goFuncValue is the value of the gosym.FuncSymName symbol.
// baseAddr is the address of the memory region (ELF Prog) containing goFuncValue.
// progReader is a ReaderAt positioned at the start of that region.
func (t *LineTable) InlineTree(f *Func, goFuncValue, baseAddr uint64, progReader io.ReaderAt) ([]InlinedCall, error) {
if f.inlineTreeCount == 0 {
return nil, nil
}
if f.inlineTreeOffset == ^uint32(0) {
return nil, nil
}
var offset int64
if t.version >= ver118 {
offset = int64(goFuncValue - baseAddr + uint64(f.inlineTreeOffset))
} else {
offset = int64(uint64(f.inlineTreeOffset) - baseAddr)
}
r := io.NewSectionReader(progReader, offset, 1<<32) // pick a size larger than we need
ics := make([]InlinedCall, 0, f.inlineTreeCount)
for i := 0; i < f.inlineTreeCount; i++ {
if t.version >= ver120 {
var ric rawInlinedCall120
if err := binary.Read(r, t.binary, &ric); err != nil {
return nil, err
}
ics = append(ics, InlinedCall{
FuncID: ric.FuncID,
Name: t.funcName(uint32(ric.NameOff)),
ParentPC: ric.ParentPC,
})
} else {
var ric rawInlinedCall112
if err := binary.Read(r, t.binary, &ric); err != nil {
return nil, err
}
ics = append(ics, InlinedCall{
FuncID: ric.FuncID,
Name: t.funcName(uint32(ric.Func_)),
ParentPC: ric.ParentPC,
})
}
}
return ics, nil
}
// InlinedCall describes a call to an inlined function.
type InlinedCall struct {
FuncID uint8 // type of the called function
Name string // name of called function
ParentPC int32 // position of an instruction whose source position is the call site (offset from entry)
}
// rawInlinedCall112 is the encoding of entries in the FUNCDATA_InlTree table
// from Go 1.12 through 1.19. It is equivalent to runtime.inlinedCall.
type rawInlinedCall112 struct {
Parent int16 // index of parent in the inltree, or < 0
FuncID uint8 // type of the called function
_ byte
File int32 // perCU file index for inlined call. See cmd/link:pcln.go
Line int32 // line number of the call site
Func_ int32 // offset into pclntab for name of called function
ParentPC int32 // position of an instruction whose source position is the call site (offset from entry)
}
// rawInlinedCall120 is the encoding of entries in the FUNCDATA_InlTree table
// from Go 1.20. It is equivalent to runtime.inlinedCall.
type rawInlinedCall120 struct {
FuncID uint8 // type of the called function
_ [3]byte
NameOff int32 // offset into pclntab for name of called function
ParentPC int32 // position of an instruction whose source position is the call site (offset from entry)
StartLine int32 // line number of start of function (func keyword/TEXT directive)
}
func (f funcData) npcdata() uint32 { return f.field(7) }
func (f funcData) nfuncdata(numFuncFields uint32) uint32 {
return uint32(f.data[f.fieldOffset(numFuncFields-1)+3])
}
func (f funcData) funcdataOffset(i uint8, numFuncFields uint32) uint32 {
if uint32(i) >= f.nfuncdata(numFuncFields) {
return ^uint32(0)
}
var off uint32
if f.t.version >= ver118 {
off = f.fieldOffset(numFuncFields) + // skip fixed part of _func
f.npcdata()*4 + // skip pcdata
uint32(i)*4 // index of i'th FUNCDATA
} else {
off = f.fieldOffset(numFuncFields) + // skip fixed part of _func
f.npcdata()*4
off += uint32(i) * f.t.ptrsize
}
return f.t.binary.Uint32(f.data[off:])
}
func (f funcData) fieldOffset(n uint32) uint32 {
// In Go 1.18, the first field of _func changed
// from a uintptr entry PC to a uint32 entry offset.
sz0 := f.t.ptrsize
if f.t.version >= ver118 {
sz0 = 4
}
return sz0 + (n-1)*4 // subsequent fields are 4 bytes each
}
func (f funcData) pcdataOffset(i uint8, numFuncFields uint32) uint32 {
if uint32(i) >= f.npcdata() {
return ^uint32(0)
}
off := f.fieldOffset(numFuncFields) + // skip fixed part of _func
uint32(i)*4 // index of i'th PCDATA
return f.t.binary.Uint32(f.data[off:])
}
// maxInlineTreeIndexValue returns the maximum value of the inline tree index
// pc-value table in info. This is the only way to determine how many
// IndexedCalls are in an inline tree, since the data of the tree itself is not
// delimited in any way.
func (t *LineTable) maxInlineTreeIndexValue(info funcData, numFuncFields uint32) int {
if info.npcdata() <= pcdata_InlTreeIndex {
return -1
}
off := info.pcdataOffset(pcdata_InlTreeIndex, numFuncFields)
p := t.pctab[off:]
val := int32(-1)
max := int32(-1)
var pc uint64
for t.step(&p, &pc, &val, pc == 0) {
if val > max {
max = val
}
}
return int(max)
}
type inlTree struct {
inlineTreeOffset uint32 // offset from go.func.* symbol
inlineTreeCount int // number of entries in inline tree
}