Update vendored runc to v1.0.0.0-rc94

Note that this is the code in containerd that uses runc (as almost
a library). Please see the other commit for the update to runc binary
itself.

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

vendor/github.com/cilium/ebpf/link/perf_event.go

@@ -0,0 +1,253 @@
+package link
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"strconv"
+	"strings"
+	"unsafe"
+
+	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/internal"
+	"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.
+// - 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"
+
+	// 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.
+	rgxTraceEvent = regexp.MustCompile("^[a-zA-Z_][0-9a-zA-Z_]*$")
+
+	errInvalidInput = errors.New("invalid input")
+)
+
+const (
+	perfAllThreads = -1
+)
+
+// 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 {
+
+	// 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
+
+	// True for kretprobes/uretprobes.
+	ret bool
+
+	fd       *internal.FD
+	progType ebpf.ProgramType
+}
+
+func (pe *perfEvent) isLink() {}
+
+func (pe *perfEvent) Pin(string) error {
+	return fmt.Errorf("pin perf event: %w", ErrNotSupported)
+}
+
+func (pe *perfEvent) Unpin() error {
+	return fmt.Errorf("unpin perf event: %w", ErrNotSupported)
+}
+
+// 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 (pe *perfEvent) Update(prog *ebpf.Program) error {
+	return fmt.Errorf("can't replace eBPF program in perf event: %w", ErrNotSupported)
+}
+
+func (pe *perfEvent) Close() error {
+	if pe.fd == nil {
+		return nil
+	}
+
+	pfd, err := pe.fd.Value()
+	if err != nil {
+		return fmt.Errorf("getting perf event fd: %w", err)
+	}
+
+	err = unix.IoctlSetInt(int(pfd), unix.PERF_EVENT_IOC_DISABLE, 0)
+	if err != nil {
+		return fmt.Errorf("disabling perf event: %w", err)
+	}
+
+	err = pe.fd.Close()
+	if err != nil {
+		return fmt.Errorf("closing perf event fd: %w", err)
+	}
+
+	switch t := pe.progType; t {
+	case ebpf.Kprobe:
+		// For kprobes created using tracefs, clean up the <tracefs>/kprobe_events entry.
+		if pe.tracefsID != 0 {
+			return closeTraceFSKprobeEvent(pe.group, pe.name)
+		}
+	case ebpf.TracePoint:
+		// Tracepoint trace events don't hold any extra resources.
+		return nil
+	}
+
+	return nil
+}
+
+// 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 (pe *perfEvent) attach(prog *ebpf.Program) error {
+	if prog == nil {
+		return errors.New("cannot attach a nil program")
+	}
+	if pe.fd == nil {
+		return errors.New("cannot attach to nil perf event")
+	}
+	if t := prog.Type(); t != pe.progType {
+		return fmt.Errorf("invalid program type (expected %s): %s", pe.progType, t)
+	}
+	if prog.FD() < 0 {
+		return fmt.Errorf("invalid program: %w", internal.ErrClosedFd)
+	}
+
+	// The ioctl below will fail when the fd is invalid.
+	kfd, _ := pe.fd.Value()
+
+	// Assign the eBPF program to the perf event.
+	err := unix.IoctlSetInt(int(kfd), unix.PERF_EVENT_IOC_SET_BPF, prog.FD())
+	if err != nil {
+		return fmt.Errorf("setting perf event bpf program: %w", err)
+	}
+
+	// PERF_EVENT_IOC_ENABLE and _DISABLE ignore their given values.
+	if err := unix.IoctlSetInt(int(kfd), unix.PERF_EVENT_IOC_ENABLE, 0); err != nil {
+		return fmt.Errorf("enable perf event: %s", err)
+	}
+
+	// Close the perf event when its reference is lost to avoid leaking system resources.
+	runtime.SetFinalizer(pe, (*perfEvent).Close)
+	return 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.
+// group and name must be alphanumeric or underscore, as required by the kernel.
+func getTraceEventID(group, name string) (uint64, error) {
+	tid, err := uint64FromFile(tracefsPath, "events", group, name, "id")
+	if errors.Is(err, ErrNotSupported) {
+		return 0, fmt.Errorf("trace event %s/%s: %w", group, name, ErrNotSupported)
+	}
+	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.
+func getPMUEventType(pmu string) (uint64, error) {
+	et, err := uint64FromFile("/sys/bus/event_source/devices", pmu, "type")
+	if errors.Is(err, ErrNotSupported) {
+		return 0, fmt.Errorf("pmu type %s: %w", pmu, ErrNotSupported)
+	}
+	if err != nil {
+		return 0, fmt.Errorf("reading pmu type %s: %w", pmu, err)
+	}
+
+	return et, nil
+}
+
+// openTracepointPerfEvent opens a tracepoint-type perf event. System-wide
+// kprobes created by writing to <tracefs>/kprobe_events are tracepoints
+// behind the scenes, and can be attached to using these perf events.
+func openTracepointPerfEvent(tid uint64) (*internal.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, perfAllThreads, 0, -1, unix.PERF_FLAG_FD_CLOEXEC)
+	if err != nil {
+		return nil, fmt.Errorf("opening tracepoint perf event: %w", err)
+	}
+
+	return internal.NewFD(uint32(fd)), nil
+}
+
+// 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) {
+
+	// Resolve leaf path separately for error feedback. Makes the join onto
+	// base more readable (can't mix with variadic args).
+	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 := ioutil.ReadFile(p)
+	if os.IsNotExist(err) {
+		// Only echo leaf path, the base path can be prepended at the call site
+		// if more verbosity is required.
+		return 0, fmt.Errorf("symbol %s: %w", l, ErrNotSupported)
+	}
+	if err != nil {
+		return 0, fmt.Errorf("reading file %s: %w", p, err)
+	}
+
+	et := bytes.TrimSpace(data)
+	return strconv.ParseUint(string(et), 10, 64)
+}