func (b *Binutils) openELF(name string, start, limit, offset uint64) (plugin.ObjFile, error) {
ef, err := elf.Open(name)
if err != nil {
return nil, fmt.Errorf("Parsing %s: %v", name, err)
}
defer ef.Close()
var stextOffset *uint64
var pageAligned = func(addr uint64) bool { return addr%4096 == 0 }
if strings.Contains(name, "vmlinux") || !pageAligned(start) || !pageAligned(limit) || !pageAligned(offset) {
// Reading all Symbols is expensive, and we only rarely need it so
// we don't want to do it every time. But if _stext happens to be
// page-aligned but isn't the same as Vaddr, we would symbolize
// wrong. So if the name the addresses aren't page aligned, or if
// the name is "vmlinux" we read _stext. We can be wrong if: (1)
// someone passes a kernel path that doesn't contain "vmlinux" AND
// (2) _stext is page-aligned AND (3) _stext is not at Vaddr
symbols, err := ef.Symbols()
if err != nil {
return nil, err
}
for _, s := range symbols {
if s.Name == "_stext" {
// The kernel may use _stext as the mapping start address.
stextOffset = &s.Value
break
}
}
}
base, err := elfexec.GetBase(&ef.FileHeader, nil, stextOffset, start, limit, offset)
if err != nil {
return nil, fmt.Errorf("Could not identify base for %s: %v", name, err)
}
buildID := ""
if f, err := os.Open(name); err == nil {
if id, err := elfexec.GetBuildID(f); err == nil {
buildID = fmt.Sprintf("%x", id)
}
}
if b.fast || (!b.addr2lineFound && !b.llvmSymbolizerFound) {
return &fileNM{file: file{b, name, base, buildID}}, nil
}
return &fileAddr2Line{file: file{b, name, base, buildID}}, nil
}
// Open satisfies the plugin.ObjTool interface.
func (b *Binutils) Open(name string, start, limit, offset uint64) (plugin.ObjFile, error) {
if b.addr2line == "" {
// Update the command invocations if not initialized.
b.SetTools("")
}
// Make sure file is a supported executable.
// The pprof driver uses Open to sniff the difference
// between an executable and a profile.
// For now, only ELF is supported.
// Could read the first few bytes of the file and
// use a table of prefixes if we need to support other
// systems at some point.
f, err := os.Open(name)
if err != nil {
// For testing, do not require file name to exist.
if strings.Contains(b.addr2line, "testdata/") {
return &fileAddr2Line{file: file{b: b, name: name}}, nil
}
return nil, err
}
defer f.Close()
ef, err := elf.NewFile(f)
if err != nil {
return nil, fmt.Errorf("Parsing %s: %v", name, err)
}
var stextOffset *uint64
var pageAligned = func(addr uint64) bool { return addr%4096 == 0 }
if strings.Contains(name, "vmlinux") || !pageAligned(start) || !pageAligned(limit) || !pageAligned(offset) {
// Reading all Symbols is expensive, and we only rarely need it so
// we don't want to do it every time. But if _stext happens to be
// page-aligned but isn't the same as Vaddr, we would symbolize
// wrong. So if the name the addresses aren't page aligned, or if
// the name is "vmlinux" we read _stext. We can be wrong if: (1)
// someone passes a kernel path that doesn't contain "vmlinux" AND
// (2) _stext is page-aligned AND (3) _stext is not at Vaddr
symbols, err := ef.Symbols()
if err != nil {
return nil, err
}
for _, s := range symbols {
if s.Name == "_stext" {
// The kernel may use _stext as the mapping start address.
stextOffset = &s.Value
break
}
}
}
base, err := elfexec.GetBase(&ef.FileHeader, nil, stextOffset, start, limit, offset)
if err != nil {
return nil, fmt.Errorf("Could not identify base for %s: %v", name, err)
}
// Find build ID, while we have the file open.
buildID := ""
if id, err := elfexec.GetBuildID(f); err == nil {
buildID = fmt.Sprintf("%x", id)
}
if b.fast {
return &fileNM{file: file{b, name, base, buildID}}, nil
}
return &fileAddr2Line{file: file{b, name, base, buildID}}, nil
}