1 files changed, 137 insertions, 0 deletions
diff --git a/pkg/sentry/kernel/task_log.go b/pkg/sentry/kernel/task_log.go
new file mode 100644
index 000000000..18efacb19
--- /dev/null
+++ b/pkg/sentry/kernel/task_log.go
@@ -0,0 +1,137 @@
+// 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 (
+	"fmt"
+	"sort"
+
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+)
+
+const (
+	// maxStackDebugBytes is the maximum number of user stack bytes that may be
+	// printed by debugDumpStack.
+	maxStackDebugBytes = 1024
+)
+
+// Infof logs an formatted info message by calling log.Infof.
+func (t *Task) Infof(fmt string, v ...interface{}) {
+	if log.IsLogging(log.Info) {
+		log.Infof(t.logPrefix.Load().(string)+fmt, v...)
+	}
+}
+
+// Warningf logs a warning string by calling log.Warningf.
+func (t *Task) Warningf(fmt string, v ...interface{}) {
+	if log.IsLogging(log.Warning) {
+		log.Warningf(t.logPrefix.Load().(string)+fmt, v...)
+	}
+}
+
+// Debugf creates a debug string that includes the task ID.
+func (t *Task) Debugf(fmt string, v ...interface{}) {
+	if log.IsLogging(log.Debug) {
+		log.Debugf(t.logPrefix.Load().(string)+fmt, v...)
+	}
+}
+
+// IsLogging returns true iff this level is being logged.
+func (t *Task) IsLogging(level log.Level) bool {
+	return log.IsLogging(level)
+}
+
+// DebugDumpState logs task state at log level debug.
+//
+// Preconditions: The caller must be running on the task goroutine.
+func (t *Task) DebugDumpState() {
+	t.debugDumpRegisters()
+	t.debugDumpStack()
+	if mm := t.MemoryManager(); mm != nil {
+		t.Debugf("Mappings:\n%s", mm)
+	}
+	t.Debugf("FDMap:\n%s", t.FDMap())
+}
+
+// debugDumpRegisters logs register state at log level debug.
+//
+// Preconditions: The caller must be running on the task goroutine.
+func (t *Task) debugDumpRegisters() {
+	if !t.IsLogging(log.Debug) {
+		return
+	}
+	regmap, err := t.Arch().RegisterMap()
+	if err != nil {
+		t.Debugf("Registers: %v", err)
+	} else {
+		t.Debugf("Registers:")
+		var regs []string
+		for reg := range regmap {
+			regs = append(regs, reg)
+		}
+		sort.Strings(regs)
+		for _, reg := range regs {
+			t.Debugf("%-8s = %016x", reg, regmap[reg])
+		}
+	}
+}
+
+// debugDumpStack logs user stack contents at log level debug.
+//
+// Preconditions: The caller must be running on the task goroutine.
+func (t *Task) debugDumpStack() {
+	if !t.IsLogging(log.Debug) {
+		return
+	}
+	m := t.MemoryManager()
+	if m == nil {
+		t.Debugf("Memory manager for task is gone, skipping application stack dump.")
+		return
+	}
+	t.Debugf("Stack:")
+	start := usermem.Addr(t.Arch().Stack())
+	// Round addr down to a 16-byte boundary.
+	start &= ^usermem.Addr(15)
+	// Print 16 bytes per line, one byte at a time.
+	for offset := uint64(0); offset < maxStackDebugBytes; offset += 16 {
+		addr, ok := start.AddLength(offset)
+		if !ok {
+			break
+		}
+		var data [16]byte
+		n, err := m.CopyIn(t, addr, data[:], usermem.IOOpts{
+			IgnorePermissions: true,
+		})
+		// Print as much of the line as we can, even if an error was
+		// encountered.
+		if n > 0 {
+			t.Debugf("%x: % x", addr, data[:n])
+		}
+		if err != nil {
+			t.Debugf("Error reading stack at address %x: %v", addr+usermem.Addr(n), err)
+			break
+		}
+	}
+}
+
+// updateLogPrefix updates the task's cached log prefix to reflect its
+// current thread ID.
+//
+// Preconditions: The task's owning TaskSet.mu must be locked.
+func (t *Task) updateLogPrefixLocked() {
+	// Use the task's TID in the root PID namespace for logging.
+	t.logPrefix.Store(fmt.Sprintf("[% 4d] ", t.tg.pidns.owner.Root.tids[t]))
+}