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// Copyright 2018 Google LLC
//
// 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 mm
import (
"bytes"
"fmt"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
)
const (
// If checkInvariants is true, perform runtime checks for invariants
// expected by the mm package. This is normally disabled since MM is a
// significant hot path in general, and some such checks (notably
// memmap.CheckTranslateResult) are very expensive.
checkInvariants = false
// If logIOErrors is true, log I/O errors that originate from MM before
// converting them to EFAULT.
logIOErrors = false
)
// String implements fmt.Stringer.String.
func (mm *MemoryManager) String() string {
return mm.DebugString(context.Background())
}
// DebugString returns a string containing information about mm for debugging.
func (mm *MemoryManager) DebugString(ctx context.Context) string {
mm.mappingMu.RLock()
defer mm.mappingMu.RUnlock()
mm.activeMu.RLock()
defer mm.activeMu.RUnlock()
return mm.debugStringLocked(ctx)
}
// Preconditions: mm.mappingMu and mm.activeMu must be locked.
func (mm *MemoryManager) debugStringLocked(ctx context.Context) string {
var b bytes.Buffer
b.WriteString("VMAs:\n")
for vseg := mm.vmas.FirstSegment(); vseg.Ok(); vseg = vseg.NextSegment() {
b.Write(mm.vmaMapsEntryLocked(ctx, vseg))
}
b.WriteString("PMAs:\n")
for pseg := mm.pmas.FirstSegment(); pseg.Ok(); pseg = pseg.NextSegment() {
b.Write(pseg.debugStringEntryLocked())
}
return string(b.Bytes())
}
// Preconditions: mm.activeMu must be locked.
func (pseg pmaIterator) debugStringEntryLocked() []byte {
var b bytes.Buffer
fmt.Fprintf(&b, "%08x-%08x ", pseg.Start(), pseg.End())
pma := pseg.ValuePtr()
if pma.vmaEffectivePerms.Read {
b.WriteByte('r')
} else {
b.WriteByte('-')
}
if pma.vmaEffectivePerms.Write {
if pma.needCOW {
b.WriteByte('c')
} else {
b.WriteByte('w')
}
} else {
b.WriteByte('-')
}
if pma.vmaEffectivePerms.Execute {
b.WriteByte('x')
} else {
b.WriteByte('-')
}
if pma.private {
b.WriteByte('p')
} else {
b.WriteByte('s')
}
fmt.Fprintf(&b, " %08x %T\n", pma.off, pma.file)
return b.Bytes()
}
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