initial commit

src/jehanne/cmd/profile/profile.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"bytes"
+	"debug/elf"
+	"encoding/binary"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"sort"
+)
+
+type Header struct {
+	Sz   byte
+	_    byte
+	Core uint16
+	_    uint16
+	Ver  byte
+	Sig  byte
+	Time uint64
+}
+
+type pc uint64
+
+type Record struct {
+	Header
+	pcs []pc
+}
+
+
+type Symbol struct {
+	Addr uint64
+	Name string
+}
+
+type Symbols []*Symbol
+
+func (s Symbols) Len() int      { return len(s) }
+func (s Symbols) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+type ByAddress struct{ Symbols }
+
+func (s ByAddress) Less(i, j int) bool { return s.Symbols[i].Addr < s.Symbols[j].Addr }
+
+var (
+	profile     = flag.String("profile", "", "name of file containing profile data")
+	debug       = flag.Bool("d", false, "Debug printing")
+	kernel      = flag.String("kernel", "", "kernel to profile against")
+	symbolTable []*Symbol
+)
+
+func loadSymbols(kernel *elf.File) {
+	syms, err := kernel.Symbols()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	for _, sym := range syms {
+		value := sym.Value | 0xffffffff00000000
+		symbolTable = append(symbolTable, &Symbol{value, sym.Name})
+	}
+	sort.Sort(ByAddress{symbolTable})
+}
+
+func findFunction(pc pc) string {
+	addr := uint64(pc)
+	var prevSym *Symbol
+	for _, sym := range symbolTable {
+		if sym.Addr > addr && prevSym != nil {
+			return prevSym.Name
+		}
+		prevSym = sym
+	}
+	return "*** Not Found ***"
+}
+
+func main() {
+	flag.Parse()
+	kernelElf, err := elf.Open(*kernel)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	loadSymbols(kernelElf)
+
+	backtraces, err := ioutil.ReadFile(*profile)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	b := bytes.NewBuffer(backtraces)
+	var numRecords int
+	var records []Record
+	for {
+		var h Header
+		if err := binary.Read(b, binary.LittleEndian, &h); err != nil {
+			if err == io.EOF {
+				break
+			}
+			fmt.Fprintf(os.Stderr, "header: %v\n", err)
+			os.Exit(1)
+		}
+		if *debug {
+			fmt.Fprintf(os.Stderr, "%d: %v\n", numRecords, h)
+		}
+
+		if h.Sig != 0xee {
+			fmt.Fprintf(os.Stderr, "Record %d: sig is 0x%x, not 0xee", numRecords, h.Sig)
+			os.Exit(1)
+		}
+		pcs := make([]pc, h.Sz)
+		if err := binary.Read(b, binary.LittleEndian, pcs); err != nil {
+			fmt.Fprintf(os.Stderr, "data: %v\n", err)
+			os.Exit(1)
+		}
+		numRecords++
+		records = append(records, Record{Header: h, pcs: pcs})
+	}
+
+	for _, r := range records {
+		fmt.Printf("0x%x: ", r.Time)
+		for _, pc := range r.pcs {
+			fmt.Printf("[0x%x, %s] ", pc, findFunction(pc))
+		}
+		fmt.Printf("\n")
+	}
+}