github.com/kubeshark/ebpf@v0.9.2/link/tracepoint.go (about)

     1  package link
     2  
     3  import (
     4  	"fmt"
     5  
     6  	"github.com/kubeshark/ebpf"
     7  )
     8  
     9  // TracepointOptions defines additional parameters that will be used
    10  // when loading Tracepoints.
    11  type TracepointOptions struct {
    12  	// Arbitrary value that can be fetched from an eBPF program
    13  	// via `bpf_get_attach_cookie()`.
    14  	//
    15  	// Needs kernel 5.15+.
    16  	Cookie uint64
    17  }
    18  
    19  // Tracepoint attaches the given eBPF program to the tracepoint with the given
    20  // group and name. See /sys/kernel/debug/tracing/events to find available
    21  // tracepoints. The top-level directory is the group, the event's subdirectory
    22  // is the name. Example:
    23  //
    24  //	tp, err := Tracepoint("syscalls", "sys_enter_fork", prog, nil)
    25  //
    26  // Losing the reference to the resulting Link (tp) will close the Tracepoint
    27  // and prevent further execution of prog. The Link must be Closed during
    28  // program shutdown to avoid leaking system resources.
    29  //
    30  // Note that attaching eBPF programs to syscalls (sys_enter_*/sys_exit_*) is
    31  // only possible as of kernel 4.14 (commit cf5f5ce).
    32  func Tracepoint(group, name string, prog *ebpf.Program, opts *TracepointOptions) (Link, error) {
    33  	if group == "" || name == "" {
    34  		return nil, fmt.Errorf("group and name cannot be empty: %w", errInvalidInput)
    35  	}
    36  	if prog == nil {
    37  		return nil, fmt.Errorf("prog cannot be nil: %w", errInvalidInput)
    38  	}
    39  	if !isValidTraceID(group) || !isValidTraceID(name) {
    40  		return nil, fmt.Errorf("group and name '%s/%s' must be alphanumeric or underscore: %w", group, name, errInvalidInput)
    41  	}
    42  	if prog.Type() != ebpf.TracePoint {
    43  		return nil, fmt.Errorf("eBPF program type %s is not a Tracepoint: %w", prog.Type(), errInvalidInput)
    44  	}
    45  
    46  	tid, err := getTraceEventID(group, name)
    47  	if err != nil {
    48  		return nil, err
    49  	}
    50  
    51  	fd, err := openTracepointPerfEvent(tid, perfAllThreads)
    52  	if err != nil {
    53  		return nil, err
    54  	}
    55  
    56  	var cookie uint64
    57  	if opts != nil {
    58  		cookie = opts.Cookie
    59  	}
    60  
    61  	pe := &perfEvent{
    62  		typ:       tracepointEvent,
    63  		group:     group,
    64  		name:      name,
    65  		tracefsID: tid,
    66  		cookie:    cookie,
    67  		fd:        fd,
    68  	}
    69  
    70  	lnk, err := attachPerfEvent(pe, prog)
    71  	if err != nil {
    72  		pe.Close()
    73  		return nil, err
    74  	}
    75  
    76  	return lnk, nil
    77  }