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apply fix for instrumenting stripped binaries
ported from: odigos-io/opentelemetry-go-instrumentation#56
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,116 @@ | ||
| // Copyright The OpenTelemetry Authors | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package process | ||
|
|
||
| import ( | ||
| "debug/elf" | ||
| "errors" | ||
| "fmt" | ||
|
|
||
| "go.opentelemetry.io/auto/pkg/log" | ||
| ) | ||
|
|
||
| func FindFunctionsUnStripped(elfF *elf.File, relevantFuncs map[string]interface{}) ([]*Func, error) { | ||
| symbols, err := elfF.Symbols() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| var result []*Func | ||
| for _, f := range symbols { | ||
| if _, exists := relevantFuncs[f.Name]; exists { | ||
| offset, err := getFuncOffsetUnstripped(elfF, f) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| returns, err := findFuncReturnsUnstripped(elfF, f, offset) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| log.Logger.V(0).Info("found relevant function for instrumentation", "function", f.Name, "returns", len(returns)) | ||
| function := &Func{ | ||
| Name: f.Name, | ||
| Offset: offset, | ||
| ReturnOffsets: returns, | ||
| } | ||
|
|
||
| result = append(result, function) | ||
| } | ||
| } | ||
|
|
||
| return result, nil | ||
| } | ||
|
|
||
| func getFuncOffsetUnstripped(f *elf.File, symbol elf.Symbol) (uint64, error) { | ||
| var sections []*elf.Section | ||
|
|
||
| for i := range f.Sections { | ||
| if f.Sections[i].Flags == elf.SHF_ALLOC+elf.SHF_EXECINSTR { | ||
| sections = append(sections, f.Sections[i]) | ||
| } | ||
| } | ||
|
|
||
| if len(sections) == 0 { | ||
| return 0, fmt.Errorf("function %q not found in file", symbol) | ||
| } | ||
|
|
||
| var execSection *elf.Section | ||
| for m := range sections { | ||
| sectionStart := sections[m].Addr | ||
| sectionEnd := sectionStart + sections[m].Size | ||
| if symbol.Value >= sectionStart && symbol.Value < sectionEnd { | ||
| execSection = sections[m] | ||
| break | ||
| } | ||
| } | ||
|
|
||
| if execSection == nil { | ||
| return 0, errors.New("could not find symbol in executable sections of binary") | ||
| } | ||
|
|
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| return uint64(symbol.Value - execSection.Addr + execSection.Offset), nil | ||
| } | ||
|
|
||
| func findFuncReturnsUnstripped(elfFile *elf.File, sym elf.Symbol, functionOffset uint64) ([]uint64, error) { | ||
| textSection := elfFile.Section(".text") | ||
| if textSection == nil { | ||
| return nil, errors.New("could not find .text section in binary") | ||
| } | ||
|
|
||
| lowPC := sym.Value | ||
| highPC := lowPC + sym.Size | ||
| offset := lowPC - textSection.Addr | ||
| buf := make([]byte, int(highPC-lowPC)) | ||
|
|
||
| readBytes, err := textSection.ReadAt(buf, int64(offset)) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("could not read text section: %w", err) | ||
| } | ||
| data := buf[:readBytes] | ||
| instructionIndices, err := findRetInstructions(data) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("error while scanning instructions: %w", err) | ||
| } | ||
|
|
||
| // Add the function lowPC to each index to obtain the actual locations | ||
| newLocations := make([]uint64, len(instructionIndices)) | ||
| for i, instructionIndex := range instructionIndices { | ||
| newLocations[i] = instructionIndex + functionOffset | ||
| } | ||
|
|
||
| return newLocations, nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,104 @@ | ||
| // Copyright The OpenTelemetry Authors | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package process | ||
|
|
||
| import ( | ||
| "debug/elf" | ||
| "debug/gosym" | ||
| "fmt" | ||
|
|
||
| "go.opentelemetry.io/auto/pkg/log" | ||
| ) | ||
|
|
||
| func FindFunctionsStripped(elfF *elf.File, relevantFuncs map[string]interface{}) ([]*Func, error) { | ||
| var pclndat []byte | ||
| if sec := elfF.Section(".gopclntab"); sec != nil { | ||
| var err error | ||
| pclndat, err = sec.Data() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| } | ||
|
|
||
| sec := elfF.Section(".gosymtab") | ||
| if sec == nil { | ||
| return nil, fmt.Errorf("%s section not found in target binary, make sure this is a Go application", ".gosymtab") | ||
| } | ||
| symTabRaw, err := sec.Data() | ||
| pcln := gosym.NewLineTable(pclndat, elfF.Section(".text").Addr) | ||
| symTab, err := gosym.NewTable(symTabRaw, pcln) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| var result []*Func | ||
| for _, f := range symTab.Funcs { | ||
| if _, exists := relevantFuncs[f.Name]; exists { | ||
| start, returns, err := findFuncOffsetStripped(&f, elfF) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
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| log.Logger.V(0).Info("found relevant function for instrumentation", "function", f.Name, "returns", len(returns)) | ||
| function := &Func{ | ||
| Name: f.Name, | ||
| Offset: start, | ||
| ReturnOffsets: returns, | ||
| } | ||
|
|
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| result = append(result, function) | ||
| } | ||
| } | ||
|
|
||
| return result, nil | ||
| } | ||
|
|
||
| func findFuncOffsetStripped(f *gosym.Func, elfF *elf.File) (uint64, []uint64, error) { | ||
| off := f.Value | ||
| for _, prog := range elfF.Progs { | ||
| if prog.Type != elf.PT_LOAD || (prog.Flags&elf.PF_X) == 0 { | ||
| continue | ||
| } | ||
|
|
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| // For more info on this calculation: stackoverflow.com/a/40249502 | ||
| if prog.Vaddr <= f.Value && f.Value < (prog.Vaddr+prog.Memsz) { | ||
| off = f.Value - prog.Vaddr + prog.Off | ||
|
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| funcLen := f.End - f.Entry | ||
| data := make([]byte, funcLen) | ||
| _, err := prog.ReadAt(data, int64(f.Value-prog.Vaddr)) | ||
| if err != nil { | ||
| log.Logger.Error(err, "error while finding function return") | ||
| return 0, nil, err | ||
| } | ||
|
|
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| instructionIndices, err := findRetInstructions(data) | ||
| if err != nil { | ||
| log.Logger.Error(err, "error while finding function returns") | ||
| return 0, nil, err | ||
| } | ||
|
|
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| newLocations := make([]uint64, len(instructionIndices)) | ||
| for i, instructionIndex := range instructionIndices { | ||
| newLocations[i] = instructionIndex + off | ||
| } | ||
|
|
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| return off, newLocations, nil | ||
| } | ||
|
|
||
| } | ||
|
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| return 0, nil, fmt.Errorf("prog not found") | ||
| } |