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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"
"strings"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc/seqfile"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
const (
// devMinorBits is the number of minor bits in a device number. Linux:
// include/linux/kdev_t.h:MINORBITS
devMinorBits = 20
)
// NeedsUpdate implements seqfile.SeqSource.NeedsUpdate.
func (mm *MemoryManager) NeedsUpdate(generation int64) bool {
return true
}
// ReadSeqFileData is called by fs/proc.mapsData.ReadSeqFileData.
func (mm *MemoryManager) ReadSeqFileData(ctx context.Context, handle seqfile.SeqHandle) ([]seqfile.SeqData, int64) {
mm.mappingMu.RLock()
defer mm.mappingMu.RUnlock()
var data []seqfile.SeqData
var start usermem.Addr
if handle != nil {
start = *handle.(*usermem.Addr)
}
for vseg := mm.vmas.LowerBoundSegment(start); vseg.Ok(); vseg = vseg.NextSegment() {
// FIXME: If we use a usermem.Addr for the handle, we get
// "panic: autosave error: type usermem.Addr is not registered".
vmaAddr := vseg.End()
data = append(data, seqfile.SeqData{
Buf: mm.vmaMapsEntryLocked(ctx, vseg),
Handle: &vmaAddr,
})
}
return data, 1
}
// vmaMapsEntryLocked returns a /proc/[pid]/maps entry for the vma iterated by
// vseg, including the trailing newline.
//
// Preconditions: mm.mappingMu must be locked.
func (mm *MemoryManager) vmaMapsEntryLocked(ctx context.Context, vseg vmaIterator) []byte {
vma := vseg.ValuePtr()
private := "p"
if !vma.private {
private = "s"
}
var dev, ino uint64
if vma.id != nil {
dev = vma.id.DeviceID()
ino = vma.id.InodeID()
}
devMajor := uint32(dev >> devMinorBits)
devMinor := uint32(dev & ((1 << devMinorBits) - 1))
var b bytes.Buffer
// Do not include the guard page: fs/proc/task_mmu.c:show_map_vma() =>
// stack_guard_page_start().
fmt.Fprintf(&b, "%08x-%08x %s%s %08x %02x:%02x %d ",
vseg.Start(), vseg.End(), vma.realPerms, private, vma.off, devMajor, devMinor, ino)
// Figure out our filename or hint.
var s string
if vma.hint != "" {
s = vma.hint
} else if vma.id != nil {
// FIXME: We are holding mm.mappingMu here, which is
// consistent with Linux's holding mmap_sem in
// fs/proc/task_mmu.c:show_map_vma() => fs/seq_file.c:seq_file_path().
// However, it's not clear that fs.File.MappedName() is actually
// consistent with this lock order.
s = vma.id.MappedName(ctx)
}
if s != "" {
// Per linux, we pad until the 74th character.
if pad := 73 - b.Len(); pad > 0 {
b.WriteString(strings.Repeat(" ", pad))
}
b.WriteString(s)
}
b.WriteString("\n")
return b.Bytes()
}
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