sentry: pending signals S/R optimization.

Almost all of the hundreds of pending signal queues are empty upon save.

PiperOrigin-RevId: 201380318
Change-Id: I40747072435299de681d646e0862efac0637e172

pkg/sentry/kernel/BUILD

@@ -13,7 +13,7 @@ go_stateify(
         "ipc_namespace.go",
         "kernel.go",
         "pending_signals.go",
-        "pending_signals_list.go",
+        "pending_signals_state.go",
         "process_group_list.go",
         "ptrace.go",
         "rseq.go",
@@ -46,7 +46,10 @@ go_stateify(
         "version.go",
     ],
     out = "kernel_state.go",
-    imports = ["gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"],
+    imports = [
+        "gvisor.googlesource.com/gvisor/pkg/sentry/arch",
+        "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs",
+    ],
     package = "kernel",
 )
 
@@ -117,6 +120,7 @@ go_library(
         "kernel_state.go",
         "pending_signals.go",
         "pending_signals_list.go",
+        "pending_signals_state.go",
         "process_group_list.go",
         "ptrace.go",
         "rseq.go",

pkg/sentry/kernel/pending_signals.go

@@ -44,11 +44,11 @@ type pendingSignals struct {
 	// Note that signals is zero-indexed, but signal 1 is the first valid
 	// signal, so signals[0] contains signals with signo 1 etc. This offset is
 	// usually handled by using Signal.index().
-	signals [linux.SignalMaximum]pendingSignalQueue
+	signals [linux.SignalMaximum]pendingSignalQueue `state:".([]*arch.SignalInfo)"`
 
 	// Bit i of pendingSet is set iff there is at least one signal with signo
 	// i+1 pending.
-	pendingSet linux.SignalSet
+	pendingSet linux.SignalSet `state:"manual"`
 }
 
 // pendingSignalQueue holds a pendingSignalList for a single signal number.

pkg/sentry/kernel/pending_signals_state.go

@@ -0,0 +1,37 @@
+// Copyright 2018 Google Inc.
+//
+// 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 kernel
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
+)
+
+// saveSignals is invoked by stateify.
+func (p *pendingSignals) saveSignals() []*arch.SignalInfo {
+	var pending []*arch.SignalInfo
+	for _, q := range p.signals {
+		for ps := q.pendingSignalList.Front(); ps != nil; ps = ps.Next() {
+			pending = append(pending, ps.SignalInfo)
+		}
+	}
+	return pending
+}
+
+// loadSignals is invoked by stateify.
+func (p *pendingSignals) loadSignals(pending []*arch.SignalInfo) {
+	for _, si := range pending {
+		p.enqueue(si)
+	}
+}