Move platform.File in memmap

The subsequent systrap changes will need to import memmap from
the platform package.

PiperOrigin-RevId: 323409486

pkg/sentry/fs/fsutil/BUILD

@@ -8,7 +8,6 @@ go_template_instance(
     out = "dirty_set_impl.go",
     imports = {
         "memmap": "gvisor.dev/gvisor/pkg/sentry/memmap",
-        "platform": "gvisor.dev/gvisor/pkg/sentry/platform",
     },
     package = "fsutil",
     prefix = "Dirty",
@@ -25,14 +24,14 @@ go_template_instance(
     name = "frame_ref_set_impl",
     out = "frame_ref_set_impl.go",
     imports = {
-        "platform": "gvisor.dev/gvisor/pkg/sentry/platform",
+        "memmap": "gvisor.dev/gvisor/pkg/sentry/memmap",
     },
     package = "fsutil",
     prefix = "FrameRef",
     template = "//pkg/segment:generic_set",
     types = {
         "Key": "uint64",
-        "Range": "platform.FileRange",
+        "Range": "memmap.FileRange",
         "Value": "uint64",
         "Functions": "FrameRefSetFunctions",
     },
@@ -43,7 +42,6 @@ go_template_instance(
     out = "file_range_set_impl.go",
     imports = {
         "memmap": "gvisor.dev/gvisor/pkg/sentry/memmap",
-        "platform": "gvisor.dev/gvisor/pkg/sentry/platform",
     },
     package = "fsutil",
     prefix = "FileRange",
@@ -86,7 +84,6 @@ go_library(
         "//pkg/sentry/kernel/time",
         "//pkg/sentry/memmap",
         "//pkg/sentry/pgalloc",
-        "//pkg/sentry/platform",
         "//pkg/sentry/socket/unix/transport",
         "//pkg/sentry/usage",
         "//pkg/state",

pkg/sentry/fs/fsutil/dirty_set.go

@@ -20,7 +20,6 @@ import (
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
@@ -159,7 +158,7 @@ func (ds *DirtySet) AllowClean(mr memmap.MappableRange) {
 // repeatedly until all bytes have been written. max is the true size of the
 // cached object; offsets beyond max will not be passed to writeAt, even if
 // they are marked dirty.
-func SyncDirty(ctx context.Context, mr memmap.MappableRange, cache *FileRangeSet, dirty *DirtySet, max uint64, mem platform.File, writeAt func(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error)) error {
+func SyncDirty(ctx context.Context, mr memmap.MappableRange, cache *FileRangeSet, dirty *DirtySet, max uint64, mem memmap.File, writeAt func(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error)) error {
 	var changedDirty bool
 	defer func() {
 		if changedDirty {
@@ -194,7 +193,7 @@ func SyncDirty(ctx context.Context, mr memmap.MappableRange, cache *FileRangeSet
 // successful partial write, SyncDirtyAll will call it repeatedly until all
 // bytes have been written. max is the true size of the cached object; offsets
 // beyond max will not be passed to writeAt, even if they are marked dirty.
-func SyncDirtyAll(ctx context.Context, cache *FileRangeSet, dirty *DirtySet, max uint64, mem platform.File, writeAt func(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error)) error {
+func SyncDirtyAll(ctx context.Context, cache *FileRangeSet, dirty *DirtySet, max uint64, mem memmap.File, writeAt func(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error)) error {
 	dseg := dirty.FirstSegment()
 	for dseg.Ok() {
 		if err := syncDirtyRange(ctx, dseg.Range(), cache, max, mem, writeAt); err != nil {
@@ -210,7 +209,7 @@ func SyncDirtyAll(ctx context.Context, cache *FileRangeSet, dirty *DirtySet, max
 }
 
 // Preconditions: mr must be page-aligned.
-func syncDirtyRange(ctx context.Context, mr memmap.MappableRange, cache *FileRangeSet, max uint64, mem platform.File, writeAt func(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error)) error {
+func syncDirtyRange(ctx context.Context, mr memmap.MappableRange, cache *FileRangeSet, max uint64, mem memmap.File, writeAt func(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error)) error {
 	for cseg := cache.LowerBoundSegment(mr.Start); cseg.Ok() && cseg.Start() < mr.End; cseg = cseg.NextSegment() {
 		wbr := cseg.Range().Intersect(mr)
 		if max < wbr.Start {

pkg/sentry/fs/fsutil/file_range_set.go

@@ -23,13 +23,12 @@ import (
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // FileRangeSet maps offsets into a memmap.Mappable to offsets into a
-// platform.File. It is used to implement Mappables that store data in
+// memmap.File. It is used to implement Mappables that store data in
 // sparsely-allocated memory.
 //
 // type FileRangeSet <generated by go_generics>
@@ -65,20 +64,20 @@ func (FileRangeSetFunctions) Split(mr memmap.MappableRange, frstart uint64, spli
 }
 
 // FileRange returns the FileRange mapped by seg.
-func (seg FileRangeIterator) FileRange() platform.FileRange {
+func (seg FileRangeIterator) FileRange() memmap.FileRange {
 	return seg.FileRangeOf(seg.Range())
 }
 
 // FileRangeOf returns the FileRange mapped by mr.
 //
 // Preconditions: seg.Range().IsSupersetOf(mr). mr.Length() != 0.
-func (seg FileRangeIterator) FileRangeOf(mr memmap.MappableRange) platform.FileRange {
+func (seg FileRangeIterator) FileRangeOf(mr memmap.MappableRange) memmap.FileRange {
 	frstart := seg.Value() + (mr.Start - seg.Start())
-	return platform.FileRange{frstart, frstart + mr.Length()}
+	return memmap.FileRange{frstart, frstart + mr.Length()}
 }
 
 // Fill attempts to ensure that all memmap.Mappable offsets in required are
-// mapped to a platform.File offset, by allocating from mf with the given
+// mapped to a memmap.File offset, by allocating from mf with the given
 // memory usage kind and invoking readAt to store data into memory. (If readAt
 // returns a successful partial read, Fill will call it repeatedly until all
 // bytes have been read.) EOF is handled consistently with the requirements of
@@ -141,7 +140,7 @@ func (frs *FileRangeSet) Fill(ctx context.Context, required, optional memmap.Map
 }
 
 // Drop removes segments for memmap.Mappable offsets in mr, freeing the
-// corresponding platform.FileRanges.
+// corresponding memmap.FileRanges.
 //
 // Preconditions: mr must be page-aligned.
 func (frs *FileRangeSet) Drop(mr memmap.MappableRange, mf *pgalloc.MemoryFile) {
@@ -154,7 +153,7 @@ func (frs *FileRangeSet) Drop(mr memmap.MappableRange, mf *pgalloc.MemoryFile) {
 }
 
 // DropAll removes all segments in mr, freeing the corresponding
-// platform.FileRanges.
+// memmap.FileRanges.
 func (frs *FileRangeSet) DropAll(mf *pgalloc.MemoryFile) {
 	for seg := frs.FirstSegment(); seg.Ok(); seg = seg.NextSegment() {
 		mf.DecRef(seg.FileRange())

pkg/sentry/fs/fsutil/frame_ref_set.go

@@ -17,7 +17,7 @@ package fsutil
 import (
 	"math"
 
-	"gvisor.dev/gvisor/pkg/sentry/platform"
+	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 )
 
@@ -39,7 +39,7 @@ func (FrameRefSetFunctions) ClearValue(val *uint64) {
 }
 
 // Merge implements segment.Functions.Merge.
-func (FrameRefSetFunctions) Merge(_ platform.FileRange, val1 uint64, _ platform.FileRange, val2 uint64) (uint64, bool) {
+func (FrameRefSetFunctions) Merge(_ memmap.FileRange, val1 uint64, _ memmap.FileRange, val2 uint64) (uint64, bool) {
 	if val1 != val2 {
 		return 0, false
 	}
@@ -47,13 +47,13 @@ func (FrameRefSetFunctions) Merge(_ platform.FileRange, val1 uint64, _ platform.
 }
 
 // Split implements segment.Functions.Split.
-func (FrameRefSetFunctions) Split(_ platform.FileRange, val uint64, _ uint64) (uint64, uint64) {
+func (FrameRefSetFunctions) Split(_ memmap.FileRange, val uint64, _ uint64) (uint64, uint64) {
 	return val, val
 }
 
 // IncRefAndAccount adds a reference on the range fr. All newly inserted segments
 // are accounted as host page cache memory mappings.
-func (refs *FrameRefSet) IncRefAndAccount(fr platform.FileRange) {
+func (refs *FrameRefSet) IncRefAndAccount(fr memmap.FileRange) {
 	seg, gap := refs.Find(fr.Start)
 	for {
 		switch {
@@ -74,7 +74,7 @@ func (refs *FrameRefSet) IncRefAndAccount(fr platform.FileRange) {
 
 // DecRefAndAccount removes a reference on the range fr and untracks segments
 // that are removed from memory accounting.
-func (refs *FrameRefSet) DecRefAndAccount(fr platform.FileRange) {
+func (refs *FrameRefSet) DecRefAndAccount(fr memmap.FileRange) {
 	seg := refs.FindSegment(fr.Start)
 
 	for seg.Ok() && seg.Start() < fr.End {

pkg/sentry/fs/fsutil/host_file_mapper.go

@@ -21,7 +21,6 @@ import (
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
@@ -126,7 +125,7 @@ func (f *HostFileMapper) DecRefOn(mr memmap.MappableRange) {
 // offsets in fr or until the next call to UnmapAll.
 //
 // Preconditions: The caller must hold a reference on all offsets in fr.
-func (f *HostFileMapper) MapInternal(fr platform.FileRange, fd int, write bool) (safemem.BlockSeq, error) {
+func (f *HostFileMapper) MapInternal(fr memmap.FileRange, fd int, write bool) (safemem.BlockSeq, error) {
 	chunks := ((fr.End + chunkMask) >> chunkShift) - (fr.Start >> chunkShift)
 	f.mapsMu.Lock()
 	defer f.mapsMu.Unlock()
@@ -146,7 +145,7 @@ func (f *HostFileMapper) MapInternal(fr platform.FileRange, fd int, write bool)
 }
 
 // Preconditions: f.mapsMu must be locked.
-func (f *HostFileMapper) forEachMappingBlockLocked(fr platform.FileRange, fd int, write bool, fn func(safemem.Block)) error {
+func (f *HostFileMapper) forEachMappingBlockLocked(fr memmap.FileRange, fd int, write bool, fn func(safemem.Block)) error {
 	prot := syscall.PROT_READ
 	if write {
 		prot |= syscall.PROT_WRITE

pkg/sentry/fs/fsutil/host_mappable.go

@@ -21,18 +21,17 @@ import (
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
-// HostMappable implements memmap.Mappable and platform.File over a
+// HostMappable implements memmap.Mappable and memmap.File over a
 // CachedFileObject.
 //
 // Lock order (compare the lock order model in mm/mm.go):
 //   truncateMu ("fs locks")
 //     mu ("memmap.Mappable locks not taken by Translate")
-//       ("platform.File locks")
+//       ("memmap.File locks")
 //   	     backingFile ("CachedFileObject locks")
 //
 // +stateify savable
@@ -124,24 +123,24 @@ func (h *HostMappable) NotifyChangeFD() error {
 	return nil
 }
 
-// MapInternal implements platform.File.MapInternal.
+// MapInternal implements memmap.File.MapInternal.
-func (h *HostMappable) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+func (h *HostMappable) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
 	return h.hostFileMapper.MapInternal(fr, h.backingFile.FD(), at.Write)
 }
 
-// FD implements platform.File.FD.
+// FD implements memmap.File.FD.
 func (h *HostMappable) FD() int {
 	return h.backingFile.FD()
 }
 
-// IncRef implements platform.File.IncRef.
+// IncRef implements memmap.File.IncRef.
-func (h *HostMappable) IncRef(fr platform.FileRange) {
+func (h *HostMappable) IncRef(fr memmap.FileRange) {
 	mr := memmap.MappableRange{Start: fr.Start, End: fr.End}
 	h.hostFileMapper.IncRefOn(mr)
 }
 
-// DecRef implements platform.File.DecRef.
+// DecRef implements memmap.File.DecRef.
-func (h *HostMappable) DecRef(fr platform.FileRange) {
+func (h *HostMappable) DecRef(fr memmap.FileRange) {
 	mr := memmap.MappableRange{Start: fr.Start, End: fr.End}
 	h.hostFileMapper.DecRefOn(mr)
 }

pkg/sentry/fs/fsutil/inode_cached.go

@@ -26,7 +26,6 @@ import (
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/usermem"
@@ -934,7 +933,7 @@ func maxFillRange(required, optional memmap.MappableRange) memmap.MappableRange
 
 // InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable.
 func (c *CachingInodeOperations) InvalidateUnsavable(ctx context.Context) error {
-	// Whether we have a host fd (and consequently what platform.File is
+	// Whether we have a host fd (and consequently what memmap.File is
 	// mapped) can change across save/restore, so invalidate all translations
 	// unconditionally.
 	c.mapsMu.Lock()
@@ -999,10 +998,10 @@ func (c *CachingInodeOperations) Evict(ctx context.Context, er pgalloc.Evictable
 	}
 }
 
-// IncRef implements platform.File.IncRef. This is used when we directly map an
+// IncRef implements memmap.File.IncRef. This is used when we directly map an
-// underlying host fd and CachingInodeOperations is used as the platform.File
+// underlying host fd and CachingInodeOperations is used as the memmap.File
 // during translation.
-func (c *CachingInodeOperations) IncRef(fr platform.FileRange) {
+func (c *CachingInodeOperations) IncRef(fr memmap.FileRange) {
 	// Hot path. Avoid defers.
 	c.dataMu.Lock()
 	seg, gap := c.refs.Find(fr.Start)
@@ -1024,10 +1023,10 @@ func (c *CachingInodeOperations) IncRef(fr platform.FileRange) {
 	}
 }
 
-// DecRef implements platform.File.DecRef. This is used when we directly map an
+// DecRef implements memmap.File.DecRef. This is used when we directly map an
-// underlying host fd and CachingInodeOperations is used as the platform.File
+// underlying host fd and CachingInodeOperations is used as the memmap.File
 // during translation.
-func (c *CachingInodeOperations) DecRef(fr platform.FileRange) {
+func (c *CachingInodeOperations) DecRef(fr memmap.FileRange) {
 	// Hot path. Avoid defers.
 	c.dataMu.Lock()
 	seg := c.refs.FindSegment(fr.Start)
@@ -1046,15 +1045,15 @@ func (c *CachingInodeOperations) DecRef(fr platform.FileRange) {
 	c.dataMu.Unlock()
 }
 
-// MapInternal implements platform.File.MapInternal. This is used when we
+// MapInternal implements memmap.File.MapInternal. This is used when we
 // directly map an underlying host fd and CachingInodeOperations is used as the
-// platform.File during translation.
+// memmap.File during translation.
-func (c *CachingInodeOperations) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+func (c *CachingInodeOperations) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
 	return c.hostFileMapper.MapInternal(fr, c.backingFile.FD(), at.Write)
 }
 
-// FD implements platform.File.FD. This is used when we directly map an
+// FD implements memmap.File.FD. This is used when we directly map an
-// underlying host fd and CachingInodeOperations is used as the platform.File
+// underlying host fd and CachingInodeOperations is used as the memmap.File
 // during translation.
 func (c *CachingInodeOperations) FD() int {
 	return c.backingFile.FD()

pkg/sentry/fsimpl/gofer/regular_file.go

@@ -29,7 +29,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/syserror"
@@ -221,12 +220,12 @@ func (fd *regularFileFD) pwriteLocked(ctx context.Context, src usermem.IOSequenc
 			return 0, syserror.EINVAL
 		}
 		mr := memmap.MappableRange{pgstart, pgend}
-		var freed []platform.FileRange
+		var freed []memmap.FileRange
 		d.dataMu.Lock()
 		cseg := d.cache.LowerBoundSegment(mr.Start)
 		for cseg.Ok() && cseg.Start() < mr.End {
 			cseg = d.cache.Isolate(cseg, mr)
-			freed = append(freed, platform.FileRange{cseg.Value(), cseg.Value() + cseg.Range().Length()})
+			freed = append(freed, memmap.FileRange{cseg.Value(), cseg.Value() + cseg.Range().Length()})
 			cseg = d.cache.Remove(cseg).NextSegment()
 		}
 		d.dataMu.Unlock()
@@ -821,7 +820,7 @@ func maxFillRange(required, optional memmap.MappableRange) memmap.MappableRange
 
 // InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable.
 func (d *dentry) InvalidateUnsavable(ctx context.Context) error {
-	// Whether we have a host fd (and consequently what platform.File is
+	// Whether we have a host fd (and consequently what memmap.File is
 	// mapped) can change across save/restore, so invalidate all translations
 	// unconditionally.
 	d.mapsMu.Lock()
@@ -869,8 +868,8 @@ func (d *dentry) Evict(ctx context.Context, er pgalloc.EvictableRange) {
 	}
 }
 
-// dentryPlatformFile implements platform.File. It exists solely because dentry
+// dentryPlatformFile implements memmap.File. It exists solely because dentry
-// cannot implement both vfs.DentryImpl.IncRef and platform.File.IncRef.
+// cannot implement both vfs.DentryImpl.IncRef and memmap.File.IncRef.
 //
 // dentryPlatformFile is only used when a host FD representing the remote file
 // is available (i.e. dentry.handle.fd >= 0), and that FD is used for
@@ -878,7 +877,7 @@ func (d *dentry) Evict(ctx context.Context, er pgalloc.EvictableRange) {
 type dentryPlatformFile struct {
 	*dentry
 
-	// fdRefs counts references on platform.File offsets. fdRefs is protected
+	// fdRefs counts references on memmap.File offsets. fdRefs is protected
 	// by dentry.dataMu.
 	fdRefs fsutil.FrameRefSet
 
@@ -890,29 +889,29 @@ type dentryPlatformFile struct {
 	hostFileMapperInitOnce sync.Once
 }
 
-// IncRef implements platform.File.IncRef.
+// IncRef implements memmap.File.IncRef.
-func (d *dentryPlatformFile) IncRef(fr platform.FileRange) {
+func (d *dentryPlatformFile) IncRef(fr memmap.FileRange) {
 	d.dataMu.Lock()
 	d.fdRefs.IncRefAndAccount(fr)
 	d.dataMu.Unlock()
 }
 
-// DecRef implements platform.File.DecRef.
+// DecRef implements memmap.File.DecRef.
-func (d *dentryPlatformFile) DecRef(fr platform.FileRange) {
+func (d *dentryPlatformFile) DecRef(fr memmap.FileRange) {
 	d.dataMu.Lock()
 	d.fdRefs.DecRefAndAccount(fr)
 	d.dataMu.Unlock()
 }
 
-// MapInternal implements platform.File.MapInternal.
+// MapInternal implements memmap.File.MapInternal.
-func (d *dentryPlatformFile) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+func (d *dentryPlatformFile) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
 	d.handleMu.RLock()
 	bs, err := d.hostFileMapper.MapInternal(fr, int(d.handle.fd), at.Write)
 	d.handleMu.RUnlock()
 	return bs, err
 }
 
-// FD implements platform.File.FD.
+// FD implements memmap.File.FD.
 func (d *dentryPlatformFile) FD() int {
 	d.handleMu.RLock()
 	fd := d.handle.fd

pkg/sentry/fsimpl/host/BUILD

@@ -34,7 +34,6 @@ go_library(
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/memmap",
-        "//pkg/sentry/platform",
         "//pkg/sentry/socket/control",
         "//pkg/sentry/socket/unix",
         "//pkg/sentry/socket/unix/transport",

pkg/sentry/fsimpl/host/mmap.go

@@ -19,13 +19,12 @@ import (
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
-// inodePlatformFile implements platform.File. It exists solely because inode
+// inodePlatformFile implements memmap.File. It exists solely because inode
-// cannot implement both kernfs.Inode.IncRef and platform.File.IncRef.
+// cannot implement both kernfs.Inode.IncRef and memmap.File.IncRef.
 //
 // inodePlatformFile should only be used if inode.canMap is true.
 type inodePlatformFile struct {
@@ -34,7 +33,7 @@ type inodePlatformFile struct {
 	// fdRefsMu protects fdRefs.
 	fdRefsMu sync.Mutex
 
-	// fdRefs counts references on platform.File offsets. It is used solely for
+	// fdRefs counts references on memmap.File offsets. It is used solely for
 	// memory accounting.
 	fdRefs fsutil.FrameRefSet
 
@@ -45,32 +44,32 @@ type inodePlatformFile struct {
 	fileMapperInitOnce sync.Once
 }
 
-// IncRef implements platform.File.IncRef.
+// IncRef implements memmap.File.IncRef.
 //
 // Precondition: i.inode.canMap must be true.
-func (i *inodePlatformFile) IncRef(fr platform.FileRange) {
+func (i *inodePlatformFile) IncRef(fr memmap.FileRange) {
 	i.fdRefsMu.Lock()
 	i.fdRefs.IncRefAndAccount(fr)
 	i.fdRefsMu.Unlock()
 }
 
-// DecRef implements platform.File.DecRef.
+// DecRef implements memmap.File.DecRef.
 //
 // Precondition: i.inode.canMap must be true.
-func (i *inodePlatformFile) DecRef(fr platform.FileRange) {
+func (i *inodePlatformFile) DecRef(fr memmap.FileRange) {
 	i.fdRefsMu.Lock()
 	i.fdRefs.DecRefAndAccount(fr)
 	i.fdRefsMu.Unlock()
 }
 
-// MapInternal implements platform.File.MapInternal.
+// MapInternal implements memmap.File.MapInternal.
 //
 // Precondition: i.inode.canMap must be true.
-func (i *inodePlatformFile) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+func (i *inodePlatformFile) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
 	return i.fileMapper.MapInternal(fr, i.hostFD, at.Write)
 }
 
-// FD implements platform.File.FD.
+// FD implements memmap.File.FD.
 func (i *inodePlatformFile) FD() int {
 	return i.hostFD
 }

pkg/sentry/kernel/shm/BUILD

@@ -20,7 +20,6 @@ go_library(
         "//pkg/sentry/kernel/time",
         "//pkg/sentry/memmap",
         "//pkg/sentry/pgalloc",
-        "//pkg/sentry/platform",
         "//pkg/sentry/usage",
         "//pkg/sync",
         "//pkg/syserror",

pkg/sentry/kernel/shm/shm.go

@@ -45,7 +45,6 @@ import (
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
@@ -370,7 +369,7 @@ type Shm struct {
 
 	// fr is the offset into mfp.MemoryFile() that backs this contents of this
 	// segment. Immutable.
-	fr platform.FileRange
+	fr memmap.FileRange
 
 	// mu protects all fields below.
 	mu sync.Mutex `state:"nosave"`

pkg/sentry/kernel/timekeeper.go

@@ -21,8 +21,8 @@ import (
 
 	"gvisor.dev/gvisor/pkg/log"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
+	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	sentrytime "gvisor.dev/gvisor/pkg/sentry/time"
 	"gvisor.dev/gvisor/pkg/sync"
 )
@@ -90,7 +90,7 @@ type Timekeeper struct {
 // NewTimekeeper does not take ownership of paramPage.
 //
 // SetClocks must be called on the returned Timekeeper before it is usable.
-func NewTimekeeper(mfp pgalloc.MemoryFileProvider, paramPage platform.FileRange) (*Timekeeper, error) {
+func NewTimekeeper(mfp pgalloc.MemoryFileProvider, paramPage memmap.FileRange) (*Timekeeper, error) {
 	return &Timekeeper{
 		params: NewVDSOParamPage(mfp, paramPage),
 	}, nil

pkg/sentry/kernel/vdso.go

@@ -19,8 +19,8 @@ import (
 
 	"gvisor.dev/gvisor/pkg/binary"
 	"gvisor.dev/gvisor/pkg/safemem"
+	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
@@ -58,7 +58,7 @@ type vdsoParams struct {
 type VDSOParamPage struct {
 	// The parameter page is fr, allocated from mfp.MemoryFile().
 	mfp pgalloc.MemoryFileProvider
-	fr  platform.FileRange
+	fr  memmap.FileRange
 
 	// seq is the current sequence count written to the page.
 	//
@@ -81,7 +81,7 @@ type VDSOParamPage struct {
 // * VDSOParamPage must be the only writer to fr.
 //
 // * mfp.MemoryFile().MapInternal(fr) must return a single safemem.Block.
-func NewVDSOParamPage(mfp pgalloc.MemoryFileProvider, fr platform.FileRange) *VDSOParamPage {
+func NewVDSOParamPage(mfp pgalloc.MemoryFileProvider, fr memmap.FileRange) *VDSOParamPage {
 	return &VDSOParamPage{mfp: mfp, fr: fr}
 }
 

pkg/sentry/memmap/BUILD

@@ -28,9 +28,21 @@ go_template_instance(
     },
 )
 
+go_template_instance(
+    name = "file_range",
+    out = "file_range.go",
+    package = "memmap",
+    prefix = "File",
+    template = "//pkg/segment:generic_range",
+    types = {
+        "T": "uint64",
+    },
+)
+
 go_library(
     name = "memmap",
     srcs = [
+        "file_range.go",
         "mappable_range.go",
         "mapping_set.go",
         "mapping_set_impl.go",
@@ -40,7 +52,7 @@ go_library(
     deps = [
         "//pkg/context",
         "//pkg/log",
-        "//pkg/sentry/platform",
+        "//pkg/safemem",
         "//pkg/syserror",
         "//pkg/usermem",
     ],

pkg/sentry/memmap/memmap.go

@@ -19,12 +19,12 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/context"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
+	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Mappable represents a memory-mappable object, a mutable mapping from uint64
-// offsets to (platform.File, uint64 File offset) pairs.
+// offsets to (File, uint64 File offset) pairs.
 //
 // See mm/mm.go for Mappable's place in the lock order.
 //
@@ -74,7 +74,7 @@ type Mappable interface {
 	// Translations are valid until invalidated by a callback to
 	// MappingSpace.Invalidate or until the caller removes its mapping of the
 	// translated range. Mappable implementations must ensure that at least one
-	// reference is held on all pages in a platform.File that may be the result
+	// reference is held on all pages in a File that may be the result
 	// of a valid Translation.
 	//
 	// Preconditions: required.Length() > 0. optional.IsSupersetOf(required).
@@ -100,7 +100,7 @@ type Translation struct {
 	Source MappableRange
 
 	// File is the mapped file.
-	File platform.File
+	File File
 
 	// Offset is the offset into File at which this Translation begins.
 	Offset uint64
@@ -110,9 +110,9 @@ type Translation struct {
 	Perms usermem.AccessType
 }
 
-// FileRange returns the platform.FileRange represented by t.
+// FileRange returns the FileRange represented by t.
-func (t Translation) FileRange() platform.FileRange {
+func (t Translation) FileRange() FileRange {
-	return platform.FileRange{t.Offset, t.Offset + t.Source.Length()}
+	return FileRange{t.Offset, t.Offset + t.Source.Length()}
 }
 
 // CheckTranslateResult returns an error if (ts, terr) does not satisfy all
@@ -361,3 +361,49 @@ type MMapOpts struct {
 	// TODO(jamieliu): Replace entirely with MappingIdentity?
 	Hint string
 }
+
+// File represents a host file that may be mapped into an platform.AddressSpace.
+type File interface {
+	// All pages in a File are reference-counted.
+
+	// IncRef increments the reference count on all pages in fr.
+	//
+	// Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() >
+	// 0. At least one reference must be held on all pages in fr. (The File
+	// interface does not provide a way to acquire an initial reference;
+	// implementors may define mechanisms for doing so.)
+	IncRef(fr FileRange)
+
+	// DecRef decrements the reference count on all pages in fr.
+	//
+	// Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() >
+	// 0. At least one reference must be held on all pages in fr.
+	DecRef(fr FileRange)
+
+	// MapInternal returns a mapping of the given file offsets in the invoking
+	// process' address space for reading and writing.
+	//
+	// Note that fr.Start and fr.End need not be page-aligned.
+	//
+	// Preconditions: fr.Length() > 0. At least one reference must be held on
+	// all pages in fr.
+	//
+	// Postconditions: The returned mapping is valid as long as at least one
+	// reference is held on the mapped pages.
+	MapInternal(fr FileRange, at usermem.AccessType) (safemem.BlockSeq, error)
+
+	// FD returns the file descriptor represented by the File.
+	//
+	// The only permitted operation on the returned file descriptor is to map
+	// pages from it consistent with the requirements of AddressSpace.MapFile.
+	FD() int
+}
+
+// FileRange represents a range of uint64 offsets into a File.
+//
+// type FileRange <generated using go_generics>
+
+// String implements fmt.Stringer.String.
+func (fr FileRange) String() string {
+	return fmt.Sprintf("[%#x, %#x)", fr.Start, fr.End)
+}

pkg/sentry/mm/BUILD

@@ -7,14 +7,14 @@ go_template_instance(
     name = "file_refcount_set",
     out = "file_refcount_set.go",
     imports = {
-        "platform": "gvisor.dev/gvisor/pkg/sentry/platform",
+        "memmap": "gvisor.dev/gvisor/pkg/sentry/memmap",
     },
     package = "mm",
     prefix = "fileRefcount",
     template = "//pkg/segment:generic_set",
     types = {
         "Key": "uint64",
-        "Range": "platform.FileRange",
+        "Range": "memmap.FileRange",
         "Value": "int32",
         "Functions": "fileRefcountSetFunctions",
     },

pkg/sentry/mm/aio_context.go

@@ -20,7 +20,6 @@ import (
 	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
@@ -243,7 +242,7 @@ type aioMappable struct {
 	refs.AtomicRefCount
 
 	mfp pgalloc.MemoryFileProvider
-	fr  platform.FileRange
+	fr  memmap.FileRange
 }
 
 var aioRingBufferSize = uint64(usermem.Addr(linux.AIORingSize).MustRoundUp())

pkg/sentry/mm/mm.go

@@ -25,7 +25,7 @@
 //           Locks taken by memmap.Mappable.Translate
 //             mm.privateRefs.mu
 //               platform.AddressSpace locks
-//                 platform.File locks
+//                 memmap.File locks
 //         mm.aioManager.mu
 //           mm.AIOContext.mu
 //
@@ -396,7 +396,7 @@ type pma struct {
 	// file is the file mapped by this pma. Only pmas for which file ==
 	// MemoryManager.mfp.MemoryFile() may be saved. pmas hold a reference to
 	// the corresponding file range while they exist.
-	file platform.File `state:"nosave"`
+	file memmap.File `state:"nosave"`
 
 	// off is the offset into file at which this pma begins.
 	//
@@ -436,7 +436,7 @@ type pma struct {
 	private bool
 
 	// If internalMappings is not empty, it is the cached return value of
-	// file.MapInternal for the platform.FileRange mapped by this pma.
+	// file.MapInternal for the memmap.FileRange mapped by this pma.
 	internalMappings safemem.BlockSeq `state:"nosave"`
 }
 
@@ -469,10 +469,10 @@ func (fileRefcountSetFunctions) MaxKey() uint64 {
 func (fileRefcountSetFunctions) ClearValue(_ *int32) {
 }
 
-func (fileRefcountSetFunctions) Merge(_ platform.FileRange, rc1 int32, _ platform.FileRange, rc2 int32) (int32, bool) {
+func (fileRefcountSetFunctions) Merge(_ memmap.FileRange, rc1 int32, _ memmap.FileRange, rc2 int32) (int32, bool) {
 	return rc1, rc1 == rc2
 }
 
-func (fileRefcountSetFunctions) Split(_ platform.FileRange, rc int32, _ uint64) (int32, int32) {
+func (fileRefcountSetFunctions) Split(_ memmap.FileRange, rc int32, _ uint64) (int32, int32) {
 	return rc, rc
 }

pkg/sentry/mm/pma.go

@@ -21,7 +21,6 @@ import (
 	"gvisor.dev/gvisor/pkg/safecopy"
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
@@ -604,7 +603,7 @@ func (mm *MemoryManager) invalidateLocked(ar usermem.AddrRange, invalidatePrivat
 	}
 }
 
-// Pin returns the platform.File ranges currently mapped by addresses in ar in
+// Pin returns the memmap.File ranges currently mapped by addresses in ar in
 // mm, acquiring a reference on the returned ranges which the caller must
 // release by calling Unpin. If not all addresses are mapped, Pin returns a
 // non-nil error. Note that Pin may return both a non-empty slice of
@@ -674,15 +673,15 @@ type PinnedRange struct {
 	Source usermem.AddrRange
 
 	// File is the mapped file.
-	File platform.File
+	File memmap.File
 
 	// Offset is the offset into File at which this PinnedRange begins.
 	Offset uint64
 }
 
-// FileRange returns the platform.File offsets mapped by pr.
+// FileRange returns the memmap.File offsets mapped by pr.
-func (pr PinnedRange) FileRange() platform.FileRange {
+func (pr PinnedRange) FileRange() memmap.FileRange {
-	return platform.FileRange{pr.Offset, pr.Offset + uint64(pr.Source.Length())}
+	return memmap.FileRange{pr.Offset, pr.Offset + uint64(pr.Source.Length())}
 }
 
 // Unpin releases the reference held by prs.
@@ -857,7 +856,7 @@ func (mm *MemoryManager) vecInternalMappingsLocked(ars usermem.AddrRangeSeq) saf
 }
 
 // incPrivateRef acquires a reference on private pages in fr.
-func (mm *MemoryManager) incPrivateRef(fr platform.FileRange) {
+func (mm *MemoryManager) incPrivateRef(fr memmap.FileRange) {
 	mm.privateRefs.mu.Lock()
 	defer mm.privateRefs.mu.Unlock()
 	refSet := &mm.privateRefs.refs
@@ -878,8 +877,8 @@ func (mm *MemoryManager) incPrivateRef(fr platform.FileRange) {
 }
 
 // decPrivateRef releases a reference on private pages in fr.
-func (mm *MemoryManager) decPrivateRef(fr platform.FileRange) {
+func (mm *MemoryManager) decPrivateRef(fr memmap.FileRange) {
-	var freed []platform.FileRange
+	var freed []memmap.FileRange
 
 	mm.privateRefs.mu.Lock()
 	refSet := &mm.privateRefs.refs
@@ -951,7 +950,7 @@ func (pmaSetFunctions) Merge(ar1 usermem.AddrRange, pma1 pma, ar2 usermem.AddrRa
 
 	// Discard internal mappings instead of trying to merge them, since merging
 	// them requires an allocation and getting them again from the
-	// platform.File might not.
+	// memmap.File might not.
 	pma1.internalMappings = safemem.BlockSeq{}
 	return pma1, true
 }
@@ -1012,12 +1011,12 @@ func (pseg pmaIterator) getInternalMappingsLocked() error {
 	return nil
 }
 
-func (pseg pmaIterator) fileRange() platform.FileRange {
+func (pseg pmaIterator) fileRange() memmap.FileRange {
 	return pseg.fileRangeOf(pseg.Range())
 }
 
 // Preconditions: pseg.Range().IsSupersetOf(ar). ar.Length != 0.
-func (pseg pmaIterator) fileRangeOf(ar usermem.AddrRange) platform.FileRange {
+func (pseg pmaIterator) fileRangeOf(ar usermem.AddrRange) memmap.FileRange {
 	if checkInvariants {
 		if !pseg.Ok() {
 			panic("terminal pma iterator")
@@ -1032,5 +1031,5 @@ func (pseg pmaIterator) fileRangeOf(ar usermem.AddrRange) platform.FileRange {
 
 	pma := pseg.ValuePtr()
 	pstart := pseg.Start()
-	return platform.FileRange{pma.off + uint64(ar.Start-pstart), pma.off + uint64(ar.End-pstart)}
+	return memmap.FileRange{pma.off + uint64(ar.Start-pstart), pma.off + uint64(ar.End-pstart)}
 }