Add weirdness sentry metric.

Weirdness metric contains fields to track the number of clock fallback,
partial result and vsyscalls. This metric will avoid the overhead of
having three different metrics (fallbackMetric, partialResultMetric,
vsyscallCount).

PiperOrigin-RevId: 369970218

pkg/metric/metric.go

@@ -35,6 +35,11 @@ var (
 	// ErrInitializationDone indicates that the caller tried to create a
 	// new metric after initialization.
 	ErrInitializationDone = errors.New("metric cannot be created after initialization is complete")
+
+	// WeirdnessMetric is a metric with fields created to track the number
+	// of weird occurrences such as clock fallback, partial_result and
+	// vsyscall count.
+	WeirdnessMetric *Uint64Metric
 )
 
 // Uint64Metric encapsulates a uint64 that represents some kind of metric to be
@@ -380,3 +385,16 @@ func EmitMetricUpdate() {
 
 	eventchannel.Emit(&m)
 }
+
+// CreateSentryMetrics creates the sentry metrics during kernel initialization.
+func CreateSentryMetrics() {
+	if WeirdnessMetric != nil {
+		return
+	}
+
+	WeirdnessMetric = MustCreateNewUint64Metric("/weirdness", true /* sync */, "Increment for weird occurrences of problems such as clock fallback, partial result and vsyscalls invoked in the sandbox",
+		Field{
+			name:          "weirdness_type",
+			allowedValues: []string{"fallback", "partial_result", "vsyscall_count"},
+		})
+}

pkg/sentry/fsimpl/testutil/BUILD

@@ -17,6 +17,7 @@ go_library(
         "//pkg/fspath",
         "//pkg/hostarch",
         "//pkg/memutil",
+        "//pkg/metric",
         "//pkg/sentry/fsbridge",
         "//pkg/sentry/fsimpl/tmpfs",
         "//pkg/sentry/kernel",

pkg/sentry/fsimpl/testutil/kernel.go

@@ -25,6 +25,7 @@ import (
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/fspath"
 	"gvisor.dev/gvisor/pkg/memutil"
+	"gvisor.dev/gvisor/pkg/metric"
 	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
@@ -62,6 +63,8 @@ func Boot() (*kernel.Kernel, error) {
 		return nil, fmt.Errorf("creating platform: %v", err)
 	}
 
+	metric.CreateSentryMetrics()
+
 	kernel.VFS2Enabled = true
 	k := &kernel.Kernel{
 		Platform: plat,

pkg/sentry/kernel/task_syscall.go

@@ -285,6 +285,7 @@ func (*runSyscallExit) execute(t *Task) taskRunState {
 // task's next run state.
 func (t *Task) doVsyscall(addr hostarch.Addr, sysno uintptr) taskRunState {
 	vsyscallCount.Increment()
+	metric.WeirdnessMetric.Increment("vsyscall_count")
 
 	// Grab the caller up front, to make sure there's a sensible stack.
 	caller := t.Arch().Native(uintptr(0))

pkg/sentry/syscalls/linux/error.go

@@ -39,6 +39,7 @@ var (
 // takes a variadic number of arguments.
 func incrementPartialResultMetric() {
 	partialResultMetric.Increment()
+	metric.WeirdnessMetric.Increment("partial_result")
 }
 
 // HandleIOErrorVFS2 handles special error cases for partial results. For some

pkg/sentry/time/calibrated_clock.go

@@ -103,6 +103,7 @@ func (c *CalibratedClock) resetLocked(str string, v ...interface{}) {
 	c.ready = false
 	c.ref.Reset()
 	fallbackMetric.Increment()
+	metric.WeirdnessMetric.Increment("fallback")
 }
 
 // updateParams updates the timekeeping parameters based on the passed

runsc/boot/BUILD

@@ -38,6 +38,7 @@ go_library(
         "//pkg/fspath",
         "//pkg/log",
         "//pkg/memutil",
+        "//pkg/metric",
         "//pkg/rand",
         "//pkg/refs",
         "//pkg/refsvfs2",

runsc/boot/loader.go

@@ -34,6 +34,7 @@ import (
 	"gvisor.dev/gvisor/pkg/fd"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/memutil"
+	"gvisor.dev/gvisor/pkg/metric"
 	"gvisor.dev/gvisor/pkg/rand"
 	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/refsvfs2"
@@ -217,6 +218,8 @@ func New(args Args) (*Loader, error) {
 		return nil, fmt.Errorf("setting up memory usage: %v", err)
 	}
 
+	metric.CreateSentryMetrics()
+
 	// Is this a VFSv2 kernel?
 	if args.Conf.VFS2 {
 		kernel.VFS2Enabled = true