78 lines
2.1 KiB
Go
78 lines
2.1 KiB
Go
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package link
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import (
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"fmt"
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"github.com/cilium/ebpf"
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)
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// TracepointOptions defines additional parameters that will be used
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// when loading Tracepoints.
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type TracepointOptions struct {
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// Arbitrary value that can be fetched from an eBPF program
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// via `bpf_get_attach_cookie()`.
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//
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// Needs kernel 5.15+.
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Cookie uint64
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}
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// Tracepoint attaches the given eBPF program to the tracepoint with the given
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// group and name. See /sys/kernel/debug/tracing/events to find available
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// tracepoints. The top-level directory is the group, the event's subdirectory
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// is the name. Example:
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//
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// tp, err := Tracepoint("syscalls", "sys_enter_fork", prog, nil)
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//
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// Losing the reference to the resulting Link (tp) will close the Tracepoint
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// and prevent further execution of prog. The Link must be Closed during
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// program shutdown to avoid leaking system resources.
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//
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// Note that attaching eBPF programs to syscalls (sys_enter_*/sys_exit_*) is
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// only possible as of kernel 4.14 (commit cf5f5ce).
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func Tracepoint(group, name string, prog *ebpf.Program, opts *TracepointOptions) (Link, error) {
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if group == "" || name == "" {
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return nil, fmt.Errorf("group and name cannot be empty: %w", errInvalidInput)
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}
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if prog == nil {
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return nil, fmt.Errorf("prog cannot be nil: %w", errInvalidInput)
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}
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if !isValidTraceID(group) || !isValidTraceID(name) {
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return nil, fmt.Errorf("group and name '%s/%s' must be alphanumeric or underscore: %w", group, name, errInvalidInput)
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}
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if prog.Type() != ebpf.TracePoint {
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return nil, fmt.Errorf("eBPF program type %s is not a Tracepoint: %w", prog.Type(), errInvalidInput)
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}
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tid, err := getTraceEventID(group, name)
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if err != nil {
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return nil, err
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}
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fd, err := openTracepointPerfEvent(tid, perfAllThreads)
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if err != nil {
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return nil, err
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}
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var cookie uint64
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if opts != nil {
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cookie = opts.Cookie
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}
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pe := &perfEvent{
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typ: tracepointEvent,
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group: group,
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name: name,
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tracefsID: tid,
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cookie: cookie,
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fd: fd,
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}
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lnk, err := attachPerfEvent(pe, prog)
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if err != nil {
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pe.Close()
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return nil, err
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}
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return lnk, nil
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}
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