1 files changed, 394 insertions, 0 deletions
diff --git a/vendor/github.com/cilium/ebpf/link/perf_event.go b/vendor/github.com/cilium/ebpf/link/perf_event.go
new file mode 100644
index 000000000..0e5bd4791
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/link/perf_event.go
@@ -0,0 +1,394 @@
+package link
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"unsafe"
+
+	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/asm"
+	"github.com/cilium/ebpf/internal"
+	"github.com/cilium/ebpf/internal/sys"
+	"github.com/cilium/ebpf/internal/unix"
+)
+
+// Getting the terminology right is usually the hardest part. For posterity and
+// for staying sane during implementation:
+//
+// - trace event: Representation of a kernel runtime hook. Filesystem entries
+//   under <tracefs>/events. Can be tracepoints (static), kprobes or uprobes.
+//   Can be instantiated into perf events (see below).
+// - tracepoint: A predetermined hook point in the kernel. Exposed as trace
+//   events in (sub)directories under <tracefs>/events. Cannot be closed or
+//   removed, they are static.
+// - k(ret)probe: Ephemeral trace events based on entry or exit points of
+//   exported kernel symbols. kprobe-based (tracefs) trace events can be
+//   created system-wide by writing to the <tracefs>/kprobe_events file, or
+//   they can be scoped to the current process by creating PMU perf events.
+// - u(ret)probe: Ephemeral trace events based on user provides ELF binaries
+//   and offsets. uprobe-based (tracefs) trace events can be
+//   created system-wide by writing to the <tracefs>/uprobe_events file, or
+//   they can be scoped to the current process by creating PMU perf events.
+// - perf event: An object instantiated based on an existing trace event or
+//   kernel symbol. Referred to by fd in userspace.
+//   Exactly one eBPF program can be attached to a perf event. Multiple perf
+//   events can be created from a single trace event. Closing a perf event
+//   stops any further invocations of the attached eBPF program.
+
+var (
+	tracefsPath = "/sys/kernel/debug/tracing"
+
+	errInvalidInput = errors.New("invalid input")
+)
+
+const (
+	perfAllThreads = -1
+)
+
+type perfEventType uint8
+
+const (
+	tracepointEvent perfEventType = iota
+	kprobeEvent
+	kretprobeEvent
+	uprobeEvent
+	uretprobeEvent
+)
+
+// A perfEvent represents a perf event kernel object. Exactly one eBPF program
+// can be attached to it. It is created based on a tracefs trace event or a
+// Performance Monitoring Unit (PMU).
+type perfEvent struct {
+	// The event type determines the types of programs that can be attached.
+	typ perfEventType
+
+	// Group and name of the tracepoint/kprobe/uprobe.
+	group string
+	name  string
+
+	// PMU event ID read from sysfs. Valid IDs are non-zero.
+	pmuID uint64
+	// ID of the trace event read from tracefs. Valid IDs are non-zero.
+	tracefsID uint64
+
+	// User provided arbitrary value.
+	cookie uint64
+
+	// This is the perf event FD.
+	fd *sys.FD
+}
+
+func (pe *perfEvent) Close() error {
+	if err := pe.fd.Close(); err != nil {
+		return fmt.Errorf("closing perf event fd: %w", err)
+	}
+
+	switch pe.typ {
+	case kprobeEvent, kretprobeEvent:
+		// Clean up kprobe tracefs entry.
+		if pe.tracefsID != 0 {
+			return closeTraceFSProbeEvent(kprobeType, pe.group, pe.name)
+		}
+	case uprobeEvent, uretprobeEvent:
+		// Clean up uprobe tracefs entry.
+		if pe.tracefsID != 0 {
+			return closeTraceFSProbeEvent(uprobeType, pe.group, pe.name)
+		}
+	case tracepointEvent:
+		// Tracepoint trace events don't hold any extra resources.
+		return nil
+	}
+
+	return nil
+}
+
+// perfEventLink represents a bpf perf link.
+type perfEventLink struct {
+	RawLink
+	pe *perfEvent
+}
+
+func (pl *perfEventLink) isLink() {}
+
+// Pinning requires the underlying perf event FD to stay open.
+//
+// | PerfEvent FD | BpfLink FD | Works |
+// |--------------|------------|-------|
+// | Open         | Open       | Yes   |
+// | Closed       | Open       | No    |
+// | Open         | Closed     | No (Pin() -> EINVAL) |
+// | Closed       | Closed     | No (Pin() -> EINVAL) |
+//
+// There is currently no pretty way to recover the perf event FD
+// when loading a pinned link, so leave as not supported for now.
+func (pl *perfEventLink) Pin(string) error {
+	return fmt.Errorf("perf event link pin: %w", ErrNotSupported)
+}
+
+func (pl *perfEventLink) Unpin() error {
+	return fmt.Errorf("perf event link unpin: %w", ErrNotSupported)
+}
+
+func (pl *perfEventLink) Close() error {
+	if err := pl.pe.Close(); err != nil {
+		return fmt.Errorf("perf event link close: %w", err)
+	}
+	return pl.fd.Close()
+}
+
+func (pl *perfEventLink) Update(prog *ebpf.Program) error {
+	return fmt.Errorf("perf event link update: %w", ErrNotSupported)
+}
+
+// perfEventIoctl implements Link and handles the perf event lifecycle
+// via ioctl().
+type perfEventIoctl struct {
+	*perfEvent
+}
+
+func (pi *perfEventIoctl) isLink() {}
+
+// Since 4.15 (e87c6bc3852b "bpf: permit multiple bpf attachments for a single perf event"),
+// calling PERF_EVENT_IOC_SET_BPF appends the given program to a prog_array
+// owned by the perf event, which means multiple programs can be attached
+// simultaneously.
+//
+// Before 4.15, calling PERF_EVENT_IOC_SET_BPF more than once on a perf event
+// returns EEXIST.
+//
+// Detaching a program from a perf event is currently not possible, so a
+// program replacement mechanism cannot be implemented for perf events.
+func (pi *perfEventIoctl) Update(prog *ebpf.Program) error {
+	return fmt.Errorf("perf event ioctl update: %w", ErrNotSupported)
+}
+
+func (pi *perfEventIoctl) Pin(string) error {
+	return fmt.Errorf("perf event ioctl pin: %w", ErrNotSupported)
+}
+
+func (pi *perfEventIoctl) Unpin() error {
+	return fmt.Errorf("perf event ioctl unpin: %w", ErrNotSupported)
+}
+
+func (pi *perfEventIoctl) Info() (*Info, error) {
+	return nil, fmt.Errorf("perf event ioctl info: %w", ErrNotSupported)
+}
+
+// attach the given eBPF prog to the perf event stored in pe.
+// pe must contain a valid perf event fd.
+// prog's type must match the program type stored in pe.
+func attachPerfEvent(pe *perfEvent, prog *ebpf.Program) (Link, error) {
+	if prog == nil {
+		return nil, errors.New("cannot attach a nil program")
+	}
+	if prog.FD() < 0 {
+		return nil, fmt.Errorf("invalid program: %w", sys.ErrClosedFd)
+	}
+
+	switch pe.typ {
+	case kprobeEvent, kretprobeEvent, uprobeEvent, uretprobeEvent:
+		if t := prog.Type(); t != ebpf.Kprobe {
+			return nil, fmt.Errorf("invalid program type (expected %s): %s", ebpf.Kprobe, t)
+		}
+	case tracepointEvent:
+		if t := prog.Type(); t != ebpf.TracePoint {
+			return nil, fmt.Errorf("invalid program type (expected %s): %s", ebpf.TracePoint, t)
+		}
+	default:
+		return nil, fmt.Errorf("unknown perf event type: %d", pe.typ)
+	}
+
+	if err := haveBPFLinkPerfEvent(); err == nil {
+		return attachPerfEventLink(pe, prog)
+	}
+	return attachPerfEventIoctl(pe, prog)
+}
+
+func attachPerfEventIoctl(pe *perfEvent, prog *ebpf.Program) (*perfEventIoctl, error) {
+	if pe.cookie != 0 {
+		return nil, fmt.Errorf("cookies are not supported: %w", ErrNotSupported)
+	}
+
+	// Assign the eBPF program to the perf event.
+	err := unix.IoctlSetInt(pe.fd.Int(), unix.PERF_EVENT_IOC_SET_BPF, prog.FD())
+	if err != nil {
+		return nil, fmt.Errorf("setting perf event bpf program: %w", err)
+	}
+
+	// PERF_EVENT_IOC_ENABLE and _DISABLE ignore their given values.
+	if err := unix.IoctlSetInt(pe.fd.Int(), unix.PERF_EVENT_IOC_ENABLE, 0); err != nil {
+		return nil, fmt.Errorf("enable perf event: %s", err)
+	}
+
+	pi := &perfEventIoctl{pe}
+
+	// Close the perf event when its reference is lost to avoid leaking system resources.
+	runtime.SetFinalizer(pi, (*perfEventIoctl).Close)
+	return pi, nil
+}
+
+// Use the bpf api to attach the perf event (BPF_LINK_TYPE_PERF_EVENT, 5.15+).
+//
+// https://github.com/torvalds/linux/commit/b89fbfbb854c9afc3047e8273cc3a694650b802e
+func attachPerfEventLink(pe *perfEvent, prog *ebpf.Program) (*perfEventLink, error) {
+	fd, err := sys.LinkCreatePerfEvent(&sys.LinkCreatePerfEventAttr{
+		ProgFd:     uint32(prog.FD()),
+		TargetFd:   pe.fd.Uint(),
+		AttachType: sys.BPF_PERF_EVENT,
+		BpfCookie:  pe.cookie,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("cannot create bpf perf link: %v", err)
+	}
+
+	pl := &perfEventLink{RawLink{fd: fd}, pe}
+
+	// Close the perf event when its reference is lost to avoid leaking system resources.
+	runtime.SetFinalizer(pl, (*perfEventLink).Close)
+	return pl, nil
+}
+
+// unsafeStringPtr returns an unsafe.Pointer to a NUL-terminated copy of str.
+func unsafeStringPtr(str string) (unsafe.Pointer, error) {
+	p, err := unix.BytePtrFromString(str)
+	if err != nil {
+		return nil, err
+	}
+	return unsafe.Pointer(p), nil
+}
+
+// getTraceEventID reads a trace event's ID from tracefs given its group and name.
+// The kernel requires group and name to be alphanumeric or underscore.
+//
+// name automatically has its invalid symbols converted to underscores so the caller
+// can pass a raw symbol name, e.g. a kernel symbol containing dots.
+func getTraceEventID(group, name string) (uint64, error) {
+	name = sanitizeSymbol(name)
+	tid, err := uint64FromFile(tracefsPath, "events", group, name, "id")
+	if errors.Is(err, os.ErrNotExist) {
+		return 0, fmt.Errorf("trace event %s/%s: %w", group, name, os.ErrNotExist)
+	}
+	if err != nil {
+		return 0, fmt.Errorf("reading trace event ID of %s/%s: %w", group, name, err)
+	}
+
+	return tid, nil
+}
+
+// getPMUEventType reads a Performance Monitoring Unit's type (numeric identifier)
+// from /sys/bus/event_source/devices/<pmu>/type.
+//
+// Returns ErrNotSupported if the pmu type is not supported.
+func getPMUEventType(typ probeType) (uint64, error) {
+	et, err := uint64FromFile("/sys/bus/event_source/devices", typ.String(), "type")
+	if errors.Is(err, os.ErrNotExist) {
+		return 0, fmt.Errorf("pmu type %s: %w", typ, ErrNotSupported)
+	}
+	if err != nil {
+		return 0, fmt.Errorf("reading pmu type %s: %w", typ, err)
+	}
+
+	return et, nil
+}
+
+// openTracepointPerfEvent opens a tracepoint-type perf event. System-wide
+// [k,u]probes created by writing to <tracefs>/[k,u]probe_events are tracepoints
+// behind the scenes, and can be attached to using these perf events.
+func openTracepointPerfEvent(tid uint64, pid int) (*sys.FD, error) {
+	attr := unix.PerfEventAttr{
+		Type:        unix.PERF_TYPE_TRACEPOINT,
+		Config:      tid,
+		Sample_type: unix.PERF_SAMPLE_RAW,
+		Sample:      1,
+		Wakeup:      1,
+	}
+
+	fd, err := unix.PerfEventOpen(&attr, pid, 0, -1, unix.PERF_FLAG_FD_CLOEXEC)
+	if err != nil {
+		return nil, fmt.Errorf("opening tracepoint perf event: %w", err)
+	}
+
+	return sys.NewFD(fd)
+}
+
+// uint64FromFile reads a uint64 from a file. All elements of path are sanitized
+// and joined onto base. Returns error if base no longer prefixes the path after
+// joining all components.
+func uint64FromFile(base string, path ...string) (uint64, error) {
+	l := filepath.Join(path...)
+	p := filepath.Join(base, l)
+	if !strings.HasPrefix(p, base) {
+		return 0, fmt.Errorf("path '%s' attempts to escape base path '%s': %w", l, base, errInvalidInput)
+	}
+
+	data, err := os.ReadFile(p)
+	if err != nil {
+		return 0, fmt.Errorf("reading file %s: %w", p, err)
+	}
+
+	et := bytes.TrimSpace(data)
+	return strconv.ParseUint(string(et), 10, 64)
+}
+
+// Probe BPF perf link.
+//
+// https://elixir.bootlin.com/linux/v5.16.8/source/kernel/bpf/syscall.c#L4307
+// https://github.com/torvalds/linux/commit/b89fbfbb854c9afc3047e8273cc3a694650b802e
+var haveBPFLinkPerfEvent = internal.FeatureTest("bpf_link_perf_event", "5.15", func() error {
+	prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
+		Name: "probe_bpf_perf_link",
+		Type: ebpf.Kprobe,
+		Instructions: asm.Instructions{
+			asm.Mov.Imm(asm.R0, 0),
+			asm.Return(),
+		},
+		License: "MIT",
+	})
+	if err != nil {
+		return err
+	}
+	defer prog.Close()
+
+	_, err = sys.LinkCreatePerfEvent(&sys.LinkCreatePerfEventAttr{
+		ProgFd:     uint32(prog.FD()),
+		AttachType: sys.BPF_PERF_EVENT,
+	})
+	if errors.Is(err, unix.EINVAL) {
+		return internal.ErrNotSupported
+	}
+	if errors.Is(err, unix.EBADF) {
+		return nil
+	}
+	return err
+})
+
+// isValidTraceID implements the equivalent of a regex match
+// against "^[a-zA-Z_][0-9a-zA-Z_]*$".
+//
+// Trace event groups, names and kernel symbols must adhere to this set
+// of characters. Non-empty, first character must not be a number, all
+// characters must be alphanumeric or underscore.
+func isValidTraceID(s string) bool {
+	if len(s) < 1 {
+		return false
+	}
+	for i, c := range []byte(s) {
+		switch {
+		case c >= 'a' && c <= 'z':
+		case c >= 'A' && c <= 'Z':
+		case c == '_':
+		case i > 0 && c >= '0' && c <= '9':
+
+		default:
+			return false
+		}
+	}
+
+	return true
+}