diff options
Diffstat (limited to 'vendor/github.com/cilium/ebpf/link/perf_event.go')
-rw-r--r-- | vendor/github.com/cilium/ebpf/link/perf_event.go | 394 |
1 files changed, 0 insertions, 394 deletions
diff --git a/vendor/github.com/cilium/ebpf/link/perf_event.go b/vendor/github.com/cilium/ebpf/link/perf_event.go deleted file mode 100644 index 0e5bd4791..000000000 --- a/vendor/github.com/cilium/ebpf/link/perf_event.go +++ /dev/null @@ -1,394 +0,0 @@ -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 -} |