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Add an option --filter-trace-tc to trace all tc-bpf progs on host by
fentry-ing on the progs.
To trace tc-bpf, we list all tc-bpf progs first. Then, for each prog, we
have to retrieve its entry function name as fentry attaching function.
Next, we do fentry on the prog.
Example:
... [<empty>] dummy
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,135 @@ | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| // Copyright 2023 Leon Hwang. | ||
|
|
||
| package pwru | ||
|
|
||
| import ( | ||
| "errors" | ||
| "fmt" | ||
| "log" | ||
|
|
||
| "github.com/cilium/ebpf" | ||
| "github.com/cilium/ebpf/btf" | ||
| "github.com/cilium/ebpf/link" | ||
| "golang.org/x/sys/unix" | ||
| ) | ||
|
|
||
| func listBpfProgs(typ ebpf.ProgramType) ([]*ebpf.Program, error) { | ||
| var ( | ||
| id ebpf.ProgramID | ||
| err error | ||
| ) | ||
|
|
||
| var progs []*ebpf.Program | ||
| for id, err = ebpf.ProgramGetNextID(id); err == nil; id, err = ebpf.ProgramGetNextID(id) { | ||
| prog, err := ebpf.NewProgramFromID(id) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| if prog.Type() == typ { | ||
| progs = append(progs, prog) | ||
| } else { | ||
| _ = prog.Close() | ||
| } | ||
| } | ||
|
|
||
| if err != nil && !errors.Is(err, unix.ENOENT) { | ||
| return nil, err | ||
| } | ||
|
|
||
| return progs, nil | ||
| } | ||
|
|
||
| func getEntryFuncName(prog *ebpf.Program) (string, error) { | ||
| info, err := prog.Info() | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to get program info: %w", err) | ||
| } | ||
|
|
||
| id, ok := info.BTFID() | ||
| if !ok { | ||
| return "", fmt.Errorf("bpf program %s does not have BTF", info.Name) | ||
| } | ||
|
|
||
| handle, err := btf.NewHandleFromID(id) | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to get BTF handle: %w", err) | ||
| } | ||
| defer handle.Close() | ||
|
|
||
| spec, err := handle.Spec(nil) | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to get BTF spec: %w", err) | ||
| } | ||
|
|
||
| iter := spec.Iterate() | ||
| for iter.Next() { | ||
| if fn, ok := iter.Type.(*btf.Func); ok { | ||
| return fn.Name, nil | ||
| } | ||
| } | ||
|
|
||
| return "", fmt.Errorf("no function found in %s bpf prog", info.Name) | ||
| } | ||
|
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||
| func TraceTC(prevColl *ebpf.Collection, spec *ebpf.CollectionSpec, | ||
| opts *ebpf.CollectionOptions, outputSkb bool, | ||
| ) (func(), error) { | ||
| progs, err := listBpfProgs(ebpf.SchedCLS) | ||
| if err != nil { | ||
| log.Fatalf("Failed to list TC bpf progs: %v", err) | ||
| } | ||
|
|
||
| // Reusing maps from previous collection is to handle the events together | ||
| // with the kprobes. | ||
| replacedMaps := map[string]*ebpf.Map{ | ||
| "events": prevColl.Maps["events"], | ||
| "print_stack_map": prevColl.Maps["print_stack_map"], | ||
| } | ||
| if outputSkb { | ||
| replacedMaps["print_skb_map"] = prevColl.Maps["print_skb_map"] | ||
| } | ||
| opts.MapReplacements = replacedMaps | ||
|
|
||
| tracings := make([]link.Link, 0, len(progs)) | ||
| for _, prog := range progs { | ||
| entryFn, err := getEntryFuncName(prog) | ||
| if err != nil { | ||
| log.Fatalf("Failed to get entry function name: %v", err) | ||
| } | ||
| spec := spec.Copy() | ||
| spec.Programs["fentry_tc"].AttachTarget = prog | ||
| spec.Programs["fentry_tc"].AttachTo = entryFn | ||
| coll, err := ebpf.NewCollectionWithOptions(spec, *opts) | ||
| if err != nil { | ||
| var ( | ||
| ve *ebpf.VerifierError | ||
| verifierLog string | ||
| ) | ||
| if errors.As(err, &ve) { | ||
| verifierLog = fmt.Sprintf("Verifier error: %+v\n", ve) | ||
| } | ||
|
|
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| log.Fatalf("Failed to load objects: %s\n%+v", verifierLog, err) | ||
| } | ||
| defer coll.Close() | ||
|
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| tracing, err := link.AttachTracing(link.TracingOptions{ | ||
| Program: coll.Programs["fentry_tc"], | ||
| }) | ||
| if err != nil { | ||
| log.Fatalf("Failed to attach tracing: %v", err) | ||
| } | ||
| tracings = append(tracings, tracing) | ||
| } | ||
|
|
||
| return func() { | ||
| for _, tracing := range tracings { | ||
| _ = tracing.Close() | ||
| } | ||
| for _, prog := range progs { | ||
| _ = prog.Close() | ||
| } | ||
| }, nil | ||
| } |
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