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elf: Add kprobe EventNameOption for unique eventName per Module #293

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38 changes: 34 additions & 4 deletions elf/module.go
Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,8 @@ type Module struct {
schedPrograms map[string]*SchedProgram
xdpPrograms map[string]*XDPProgram

kprobeEvOpts EventNameOption

compatProbe bool // try to be automatically convert function names depending on kernel versions (SyS_ and __x64_sys_)
}

Expand All @@ -150,6 +152,10 @@ type Kprobe struct {
efd int
}

// EventNameOption is a function type which take eventName
// then return the new eventName string
type EventNameOption func(eventName string) string

type Uprobe struct {
Name string
insns *C.struct_bpf_insn
Expand Down Expand Up @@ -331,6 +337,30 @@ func (b *Module) EnableOptionCompatProbe() {
b.compatProbe = true
}

// TrySetKprobeEventNameOpts Try to set kprobe EventNameOption function.
// If Module.kprobeEvOpts already set, return error.
func (b *Module) TrySetKprobeEventNameOpts(evOpts EventNameOption) error {
if b.kprobeEvOpts != nil {
return fmt.Errorf("kprobe eventname option is already set. this might corrupt")
}
// To prevent any error, detour safeEventName function to remove illegal characters.
b.kprobeEvOpts = func(eventName string) string {
return safeEventName(evOpts(eventName))
}
return nil
}

func (b *Module) kprobeEventName(originalEventName string) string {
var eventName string
if b.kprobeEvOpts != nil {
eventName = b.kprobeEvOpts(originalEventName)
} else {
eventName = originalEventName
}
return eventName
}


// EnableKprobe enables a kprobe/kretprobe identified by secName.
// For kretprobes, you can configure the maximum number of instances
// of the function that can be probed simultaneously with maxactive.
Expand All @@ -356,7 +386,7 @@ func (b *Module) EnableKprobe(secName string, maxactive int) error {
probeType = "p"
funcName = strings.TrimPrefix(secName, "kprobe/")
}
eventName := probeType + funcName
eventName := b.kprobeEventName(probeType + funcName)

kprobeId, err := writeKprobeEvent(probeType, eventName, funcName, maxactiveStr)
// fallback without maxactive
Expand Down Expand Up @@ -745,10 +775,10 @@ func (b *Module) closeProbes() error {
var err error
if isKretprobe {
funcName = strings.TrimPrefix(name, "kretprobe/")
err = disableKprobe("r" + funcName)
err = disableKprobe(b.kprobeEventName("r" + funcName))
} else {
funcName = strings.TrimPrefix(name, "kprobe/")
err = disableKprobe("p" + funcName)
err = disableKprobe(b.kprobeEventName("p" + funcName))
}
if err != nil {
return fmt.Errorf("error clearing probe: %v", err)
Expand Down Expand Up @@ -923,4 +953,4 @@ func (b *Module) CloseExt(options map[string]CloseOptions) error {
return err
}
return nil
}
}
4 changes: 4 additions & 0 deletions elf/module_unsupported.go
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,10 @@ func (b *Module) EnableTracepoint(secName string) error {
return errNotSupported
}

func (b *Module) TrySetKprobeEventNameOpts(evOpts EventNameOption) error {
return errNotSupported
}

func (b *Module) IterMaps() <-chan *Map {
return nil
}
Expand Down