lazy ksymbols: fix address search

helpers/kernel_symbols.go

@@ -51,6 +51,22 @@ func symbolKey(owner, name string) string {
  return owner + "_" + name
 }
 
+// parses ksymbol line file file. returns in order the symbols "type", "name", "order"
+func parseSymbolLine(line []string) (string, string, string) {
+ symbolType := strings.Clone(line[1])
+ symbolName := strings.Clone(line[2])
+
+ symbolOwner := "system"
+ if len(line) > 3 {
+ // When a symbol is contained in a kernel module, it will be specified
+ // within square brackets, otherwise it's part of the system
+ symbolOwner = strings.Clone(line[3])
+ symbolOwner = strings.TrimPrefix(symbolOwner, "[")
+ symbolOwner = strings.TrimSuffix(symbolOwner, "]")
+ }
+ return symbolType, symbolName, symbolOwner
+}
+
 // fullKernelSymbolTable
 
 type fullKernelSymbolTable struct {
@@ -116,17 +132,8 @@ func (k *fullKernelSymbolTable) Refresh() error {
  if err != nil {
  continue
  }
- symbolType := strings.Clone(line[1])
- symbolName := strings.Clone(line[2])
-
- symbolOwner := "system"
- if len(line) > 3 {
- // When a symbol is contained in a kernel module, it will be specified
- // within square brackets, otherwise it's part of the system
- symbolOwner = strings.Clone(line[3])
- symbolOwner = strings.TrimPrefix(symbolOwner, "[")
- symbolOwner = strings.TrimSuffix(symbolOwner, "]")
- }
+
+ symbolType, symbolName, symbolOwner := parseSymbolLine(line)
 
  symbolKey := symbolOwner + "_" + symbolName
  symbol := &KernelSymbol{symbolName, symbolType, symbolAddr, symbolOwner}
@@ -199,17 +206,8 @@ func (k *lazyKernelSymbols) GetSymbolByName(owner string, name string) (*KernelS
  if err != nil {
  continue
  }
- symbolType := strings.Clone(line[1])
- symbolName := strings.Clone(line[2])
-
- symbolOwner := "system"
- if len(line) > 3 {
- // When a symbol is contained in a kernel module, it will be specified
- // within square brackets, otherwise it's part of the system
- symbolOwner = strings.Clone(line[3])
- symbolOwner = strings.TrimPrefix(symbolOwner, "[")
- symbolOwner = strings.TrimSuffix(symbolOwner, "]")
- }
+
+ symbolType, symbolName, symbolOwner := parseSymbolLine(line)
 
  if name == symbolName && owner == symbolOwner {
  symbolKey := symbolKey(symbolOwner, symbolName)
@@ -233,8 +231,10 @@ func (k *lazyKernelSymbols) GetSymbolByAddr(addr uint64) (*KernelSymbol, error)
  err error
  )
 
- // since kallsyms is sorted in address ascending order, use binary search
- i := sort.Search(len(k.fileContent), func(i int) bool {
+ fileLen := len(k.fileContent)
+ found := false
+ // kallsyms are almost sorted by address, start search with binary search
+ i := sort.Search(fileLen, func(i int) bool {
  line := strings.Fields(k.fileContent[i])
  if len(line) < 3 {
  return false
@@ -243,6 +243,34 @@ func (k *lazyKernelSymbols) GetSymbolByAddr(addr uint64) (*KernelSymbol, error)
  if err != nil {
  return false
  }
+ if symbolAddr == addr {
+ found = true
+
+ symbolType, symbolName, symbolOwner := parseSymbolLine(line)
+
+ symbolKey := symbolKey(symbolOwner, symbolName)
+ symbol = &KernelSymbol{symbolName, symbolType, symbolAddr, symbolOwner}
+ k.symbolMap[symbolKey] = symbol
+ k.symbolAddrMap[symbolAddr] = symbol
+ return true
+ }
+ return symbolAddr > addr
+ })
+
+ if i < len(k.fileContent) && found {
+ return symbol, nil
+ }
+
+ // symbols may be out of order near the end of the ksymbols, search linearly in reverse
+ for i := fileLen - 1; i > 0; i-- {
+ line := strings.Fields(k.fileContent[i])
+ if len(line) < 3 {
+ continue
+ }
+ symbolAddr, err = strconv.ParseUint(line[0], 16, 64)
+ if err != nil {
+ continue
+ }
  if symbolAddr == addr {
  symbolType := strings.Clone(line[1])
  symbolName := strings.Clone(line[2])
@@ -257,19 +285,13 @@ func (k *lazyKernelSymbols) GetSymbolByAddr(addr uint64) (*KernelSymbol, error)
  }
 
  symbolKey := symbolKey(symbolOwner, symbolName)
- symbol = &KernelSymbol{symbolName, symbolType, symbolAddr, symbolOwner}
+ symbol := &KernelSymbol{symbolName, symbolType, symbolAddr, symbolOwner}
  k.symbolMap[symbolKey] = symbol
  k.symbolAddrMap[symbolAddr] = symbol
- return true
+ return symbol, nil
  }
- return symbolAddr > addr
- })
-
- if i < len(k.fileContent) && symbolAddr == addr {
- return symbol, nil
- } else {
- return nil, SymbolNotFoundAtAddress(addr)
  }
+ return nil, SymbolNotFoundAtAddress(addr)
 }
 
 func (k *lazyKernelSymbols) Refresh() error {
@@ -306,17 +328,8 @@ func (k *lazyKernelSymbols) getSymbolByAddrNotBinary(addr uint64) (*KernelSymbol
  if symbolAddr != addr {
  continue
  }
- symbolType := strings.Clone(line[1])
- symbolName := strings.Clone(line[2])
-
- symbolOwner := "system"
- if len(line) > 3 {
- // When a symbol is contained in a kernel module, it will be specified
- // within square brackets, otherwise it's part of the system
- symbolOwner = strings.Clone(line[3])
- symbolOwner = strings.TrimPrefix(symbolOwner, "[")
- symbolOwner = strings.TrimSuffix(symbolOwner, "]")
- }
+
+ symbolType, symbolName, symbolOwner := parseSymbolLine(line)
 
  symbolKey := symbolKey(symbolOwner, symbolName)
  symbol := &KernelSymbol{symbolName, symbolType, symbolAddr, symbolOwner}