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-rw-r--r--pkg/sentry/fsimpl/sys/BUILD54
-rw-r--r--pkg/sentry/fsimpl/sys/dir_refs.go118
-rw-r--r--pkg/sentry/fsimpl/sys/sys_state_autogen.go34
-rw-r--r--pkg/sentry/fsimpl/sys/sys_test.go89
4 files changed, 152 insertions, 143 deletions
diff --git a/pkg/sentry/fsimpl/sys/BUILD b/pkg/sentry/fsimpl/sys/BUILD
deleted file mode 100644
index 906cd52cb..000000000
--- a/pkg/sentry/fsimpl/sys/BUILD
+++ /dev/null
@@ -1,54 +0,0 @@
-load("//tools:defs.bzl", "go_library", "go_test")
-load("//tools/go_generics:defs.bzl", "go_template_instance")
-
-licenses(["notice"])
-
-go_template_instance(
- name = "dir_refs",
- out = "dir_refs.go",
- package = "sys",
- prefix = "dir",
- template = "//pkg/refs_vfs2:refs_template",
- types = {
- "T": "dir",
- },
-)
-
-go_library(
- name = "sys",
- srcs = [
- "dir_refs.go",
- "kcov.go",
- "sys.go",
- ],
- visibility = ["//pkg/sentry:internal"],
- deps = [
- "//pkg/abi/linux",
- "//pkg/context",
- "//pkg/coverage",
- "//pkg/log",
- "//pkg/refs",
- "//pkg/sentry/arch",
- "//pkg/sentry/fsimpl/kernfs",
- "//pkg/sentry/kernel",
- "//pkg/sentry/kernel/auth",
- "//pkg/sentry/memmap",
- "//pkg/sentry/vfs",
- "//pkg/syserror",
- "//pkg/usermem",
- ],
-)
-
-go_test(
- name = "sys_test",
- srcs = ["sys_test.go"],
- deps = [
- ":sys",
- "//pkg/abi/linux",
- "//pkg/sentry/fsimpl/testutil",
- "//pkg/sentry/kernel",
- "//pkg/sentry/kernel/auth",
- "//pkg/sentry/vfs",
- "@com_github_google_go_cmp//cmp:go_default_library",
- ],
-)
diff --git a/pkg/sentry/fsimpl/sys/dir_refs.go b/pkg/sentry/fsimpl/sys/dir_refs.go
new file mode 100644
index 000000000..89609b198
--- /dev/null
+++ b/pkg/sentry/fsimpl/sys/dir_refs.go
@@ -0,0 +1,118 @@
+package sys
+
+import (
+ "fmt"
+ "runtime"
+ "sync/atomic"
+
+ "gvisor.dev/gvisor/pkg/log"
+ refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+)
+
+// ownerType is used to customize logging. Note that we use a pointer to T so
+// that we do not copy the entire object when passed as a format parameter.
+var dirownerType *dir
+
+// Refs implements refs.RefCounter. It keeps a reference count using atomic
+// operations and calls the destructor when the count reaches zero.
+//
+// Note that the number of references is actually refCount + 1 so that a default
+// zero-value Refs object contains one reference.
+//
+// TODO(gvisor.dev/issue/1486): Store stack traces when leak check is enabled in
+// a map with 16-bit hashes, and store the hash in the top 16 bits of refCount.
+// This will allow us to add stack trace information to the leak messages
+// without growing the size of Refs.
+//
+// +stateify savable
+type dirRefs struct {
+ // refCount is composed of two fields:
+ //
+ // [32-bit speculative references]:[32-bit real references]
+ //
+ // Speculative references are used for TryIncRef, to avoid a CompareAndSwap
+ // loop. See IncRef, DecRef and TryIncRef for details of how these fields are
+ // used.
+ refCount int64
+}
+
+func (r *dirRefs) finalize() {
+ var note string
+ switch refs_vfs1.GetLeakMode() {
+ case refs_vfs1.NoLeakChecking:
+ return
+ case refs_vfs1.UninitializedLeakChecking:
+ note = "(Leak checker uninitialized): "
+ }
+ if n := r.ReadRefs(); n != 0 {
+ log.Warningf("%sRefs %p owned by %T garbage collected with ref count of %d (want 0)", note, r, dirownerType, n)
+ }
+}
+
+// EnableLeakCheck checks for reference leaks when Refs gets garbage collected.
+func (r *dirRefs) EnableLeakCheck() {
+ if refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking {
+ runtime.SetFinalizer(r, (*dirRefs).finalize)
+ }
+}
+
+// ReadRefs returns the current number of references. The returned count is
+// inherently racy and is unsafe to use without external synchronization.
+func (r *dirRefs) ReadRefs() int64 {
+
+ return atomic.LoadInt64(&r.refCount) + 1
+}
+
+// IncRef implements refs.RefCounter.IncRef.
+//
+//go:nosplit
+func (r *dirRefs) IncRef() {
+ if v := atomic.AddInt64(&r.refCount, 1); v <= 0 {
+ panic(fmt.Sprintf("Incrementing non-positive ref count %p owned by %T", r, dirownerType))
+ }
+}
+
+// TryIncRef implements refs.RefCounter.TryIncRef.
+//
+// To do this safely without a loop, a speculative reference is first acquired
+// on the object. This allows multiple concurrent TryIncRef calls to distinguish
+// other TryIncRef calls from genuine references held.
+//
+//go:nosplit
+func (r *dirRefs) TryIncRef() bool {
+ const speculativeRef = 1 << 32
+ v := atomic.AddInt64(&r.refCount, speculativeRef)
+ if int32(v) < 0 {
+
+ atomic.AddInt64(&r.refCount, -speculativeRef)
+ return false
+ }
+
+ atomic.AddInt64(&r.refCount, -speculativeRef+1)
+ return true
+}
+
+// DecRef implements refs.RefCounter.DecRef.
+//
+// Note that speculative references are counted here. Since they were added
+// prior to real references reaching zero, they will successfully convert to
+// real references. In other words, we see speculative references only in the
+// following case:
+//
+// A: TryIncRef [speculative increase => sees non-negative references]
+// B: DecRef [real decrease]
+// A: TryIncRef [transform speculative to real]
+//
+//go:nosplit
+func (r *dirRefs) DecRef(destroy func()) {
+ switch v := atomic.AddInt64(&r.refCount, -1); {
+ case v < -1:
+ panic(fmt.Sprintf("Decrementing non-positive ref count %p, owned by %T", r, dirownerType))
+
+ case v == -1:
+
+ if destroy != nil {
+ destroy()
+ }
+ }
+}
diff --git a/pkg/sentry/fsimpl/sys/sys_state_autogen.go b/pkg/sentry/fsimpl/sys/sys_state_autogen.go
new file mode 100644
index 000000000..347a46318
--- /dev/null
+++ b/pkg/sentry/fsimpl/sys/sys_state_autogen.go
@@ -0,0 +1,34 @@
+// automatically generated by stateify.
+
+package sys
+
+import (
+ "gvisor.dev/gvisor/pkg/state"
+)
+
+func (x *dirRefs) StateTypeName() string {
+ return "pkg/sentry/fsimpl/sys.dirRefs"
+}
+
+func (x *dirRefs) StateFields() []string {
+ return []string{
+ "refCount",
+ }
+}
+
+func (x *dirRefs) beforeSave() {}
+
+func (x *dirRefs) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.refCount)
+}
+
+func (x *dirRefs) afterLoad() {}
+
+func (x *dirRefs) StateLoad(m state.Source) {
+ m.Load(0, &x.refCount)
+}
+
+func init() {
+ state.Register((*dirRefs)(nil))
+}
diff --git a/pkg/sentry/fsimpl/sys/sys_test.go b/pkg/sentry/fsimpl/sys/sys_test.go
deleted file mode 100644
index 9fd38b295..000000000
--- a/pkg/sentry/fsimpl/sys/sys_test.go
+++ /dev/null
@@ -1,89 +0,0 @@
-// Copyright 2019 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package sys_test
-
-import (
- "fmt"
- "testing"
-
- "github.com/google/go-cmp/cmp"
- "gvisor.dev/gvisor/pkg/abi/linux"
- "gvisor.dev/gvisor/pkg/sentry/fsimpl/sys"
- "gvisor.dev/gvisor/pkg/sentry/fsimpl/testutil"
- "gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/kernel/auth"
- "gvisor.dev/gvisor/pkg/sentry/vfs"
-)
-
-func newTestSystem(t *testing.T) *testutil.System {
- k, err := testutil.Boot()
- if err != nil {
- t.Fatalf("Failed to create test kernel: %v", err)
- }
- ctx := k.SupervisorContext()
- creds := auth.CredentialsFromContext(ctx)
- k.VFS().MustRegisterFilesystemType(sys.Name, sys.FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{
- AllowUserMount: true,
- })
-
- mns, err := k.VFS().NewMountNamespace(ctx, creds, "", sys.Name, &vfs.GetFilesystemOptions{})
- if err != nil {
- t.Fatalf("Failed to create new mount namespace: %v", err)
- }
- return testutil.NewSystem(ctx, t, k.VFS(), mns)
-}
-
-func TestReadCPUFile(t *testing.T) {
- s := newTestSystem(t)
- defer s.Destroy()
- k := kernel.KernelFromContext(s.Ctx)
- maxCPUCores := k.ApplicationCores()
-
- expected := fmt.Sprintf("0-%d\n", maxCPUCores-1)
-
- for _, fname := range []string{"online", "possible", "present"} {
- pop := s.PathOpAtRoot(fmt.Sprintf("devices/system/cpu/%s", fname))
- fd, err := s.VFS.OpenAt(s.Ctx, s.Creds, pop, &vfs.OpenOptions{})
- if err != nil {
- t.Fatalf("OpenAt(pop:%+v) = %+v failed: %v", pop, fd, err)
- }
- defer fd.DecRef(s.Ctx)
- content, err := s.ReadToEnd(fd)
- if err != nil {
- t.Fatalf("Read failed: %v", err)
- }
- if diff := cmp.Diff(expected, content); diff != "" {
- t.Fatalf("Read returned unexpected data:\n--- want\n+++ got\n%v", diff)
- }
- }
-}
-
-func TestSysRootContainsExpectedEntries(t *testing.T) {
- s := newTestSystem(t)
- defer s.Destroy()
- pop := s.PathOpAtRoot("/")
- s.AssertAllDirentTypes(s.ListDirents(pop), map[string]testutil.DirentType{
- "block": linux.DT_DIR,
- "bus": linux.DT_DIR,
- "class": linux.DT_DIR,
- "dev": linux.DT_DIR,
- "devices": linux.DT_DIR,
- "firmware": linux.DT_DIR,
- "fs": linux.DT_DIR,
- "kernel": linux.DT_DIR,
- "module": linux.DT_DIR,
- "power": linux.DT_DIR,
- })
-}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-14 20:03:58 +0000