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Attach tracing of tc-bpf concurrently
When there are many tc-bpf progs to trace, it'll be very slow to attach tracing one by one. At this commit, I change the attaching way from serial to concurrent in order to accelerate the attaching progress for tracing tc-bpf progs. Signed-off-by: Leon Hwang <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,138 @@ | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| /* Copyright 2024 Authors of Cilium */ | ||
|
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||
| package pwru | ||
|
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||
| import ( | ||
| "errors" | ||
| "fmt" | ||
| "log" | ||
| "sync" | ||
|
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| "github.com/cilium/ebpf" | ||
| "github.com/cilium/ebpf/link" | ||
| "golang.org/x/sync/errgroup" | ||
| ) | ||
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| type tcTracer struct { | ||
| sync.Mutex | ||
| links []link.Link | ||
| } | ||
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| func (t *tcTracer) close() { | ||
| t.Lock() | ||
| defer t.Unlock() | ||
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| for _, l := range t.links { | ||
| _ = l.Close() | ||
| } | ||
| } | ||
|
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| func (t *tcTracer) addLink(l link.Link) { | ||
| t.Lock() | ||
| defer t.Unlock() | ||
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| t.links = append(t.links, l) | ||
| } | ||
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| func (t *tcTracer) trace(spec *ebpf.CollectionSpec, | ||
| opts *ebpf.CollectionOptions, prog *ebpf.Program, n2a BpfProgName2Addr, | ||
| ) error { | ||
| entryFn, name, err := getEntryFuncName(prog) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to get entry function name: %w", err) | ||
| } | ||
|
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| // The addr may hold the wrong rip value, because two addresses could | ||
| // have one same symbol. As discussed before, that doesn't affect the | ||
| // symbol resolution because even a "wrong" rip can be matched to the | ||
| // right symbol. However, this could make a difference when we want to | ||
| // distinguish which exact bpf prog is called. | ||
| // -- @jschwinger233 | ||
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| addr, ok := n2a[entryFn] | ||
| if !ok { | ||
| addr, ok = n2a[name] | ||
| if !ok { | ||
| return fmt.Errorf("failed to find address for function %s of bpf prog %s", name, prog) | ||
| } | ||
| } | ||
|
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| spec = spec.Copy() | ||
| if err := spec.RewriteConstants(map[string]any{ | ||
| "BPF_PROG_ADDR": addr, | ||
| }); err != nil { | ||
| return fmt.Errorf("failed to rewrite bpf prog addr: %w", err) | ||
| } | ||
|
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| 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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| return fmt.Errorf("failed to load objects: %s\n%w", verifierLog, err) | ||
| } | ||
| defer coll.Close() | ||
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| tracing, err := link.AttachTracing(link.TracingOptions{ | ||
| Program: coll.Programs["fentry_tc"], | ||
| }) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to attach tracing: %w", err) | ||
| } | ||
|
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| t.addLink(tracing) | ||
|
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| return nil | ||
| } | ||
|
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| func TraceTC(coll *ebpf.Collection, spec *ebpf.CollectionSpec, | ||
| opts *ebpf.CollectionOptions, outputSkb bool, n2a BpfProgName2Addr, | ||
| ) func() { | ||
| progs, err := listBpfProgs(ebpf.SchedCLS) | ||
| if err != nil { | ||
| log.Fatalf("Failed to list TC bpf progs: %v", err) | ||
| } | ||
|
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| // Reusing maps from previous collection is to handle the events together | ||
| // with the kprobes. | ||
| replacedMaps := map[string]*ebpf.Map{ | ||
| "events": coll.Maps["events"], | ||
| "print_stack_map": coll.Maps["print_stack_map"], | ||
| } | ||
| if outputSkb { | ||
| replacedMaps["print_skb_map"] = coll.Maps["print_skb_map"] | ||
| } | ||
| opts.MapReplacements = replacedMaps | ||
|
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| var tt tcTracer | ||
| tt.links = make([]link.Link, 0, len(progs)) | ||
|
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| var errg errgroup.Group | ||
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| for _, prog := range progs { | ||
| prog := prog | ||
| errg.Go(func() error { | ||
| return tt.trace(spec, opts, prog, n2a) | ||
| }) | ||
| } | ||
|
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| if err := errg.Wait(); err != nil { | ||
| log.Fatalf("Failed to trace TC: %v", err) | ||
| } | ||
|
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| return func() { | ||
| tt.close() | ||
|
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| for _, prog := range progs { | ||
| _ = prog.Close() | ||
| } | ||
| } | ||
| } |