diff options
Diffstat (limited to 'pkg/sentry/vfs/mount_unsafe.go')
| -rw-r--r-- | pkg/sentry/vfs/mount_unsafe.go | 36 |
1 files changed, 13 insertions, 23 deletions
diff --git a/pkg/sentry/vfs/mount_unsafe.go b/pkg/sentry/vfs/mount_unsafe.go index cb48c37a1..0df023713 100644 --- a/pkg/sentry/vfs/mount_unsafe.go +++ b/pkg/sentry/vfs/mount_unsafe.go @@ -12,11 +12,6 @@ // See the License for the specific language governing permissions and // limitations under the License. -// +build go1.12 -// +build !go1.17 - -// Check go:linkname function signatures when updating Go version. - package vfs import ( @@ -41,6 +36,15 @@ type mountKey struct { point unsafe.Pointer // *Dentry } +var ( + mountKeyHasher = sync.MapKeyHasher(map[mountKey]struct{}(nil)) + mountKeySeed = sync.RandUintptr() +) + +func (k *mountKey) hash() uintptr { + return mountKeyHasher(gohacks.Noescape(unsafe.Pointer(k)), mountKeySeed) +} + func (mnt *Mount) parent() *Mount { return (*Mount)(atomic.LoadPointer(&mnt.key.parent)) } @@ -56,23 +60,17 @@ func (mnt *Mount) getKey() VirtualDentry { } } -func (mnt *Mount) saveKey() VirtualDentry { return mnt.getKey() } - // Invariant: mnt.key.parent == nil. vd.Ok(). func (mnt *Mount) setKey(vd VirtualDentry) { atomic.StorePointer(&mnt.key.parent, unsafe.Pointer(vd.mount)) atomic.StorePointer(&mnt.key.point, unsafe.Pointer(vd.dentry)) } -func (mnt *Mount) loadKey(vd VirtualDentry) { mnt.setKey(vd) } - // mountTable maps (mount parent, mount point) pairs to mounts. It supports // efficient concurrent lookup, even in the presence of concurrent mutators // (provided mutation is sufficiently uncommon). // // mountTable.Init() must be called on new mountTables before use. -// -// +stateify savable type mountTable struct { // mountTable is implemented as a seqcount-protected hash table that // resolves collisions with linear probing, featuring Robin Hood insertion @@ -84,8 +82,7 @@ type mountTable struct { // intrinsics and inline assembly, limiting the performance of this // approach.) - seq sync.SeqCount `state:"nosave"` - seed uint32 // for hashing keys + seq sync.SeqCount `state:"nosave"` // size holds both length (number of elements) and capacity (number of // slots): capacity is stored as its base-2 log (referred to as order) in @@ -150,7 +147,6 @@ func init() { // Init must be called exactly once on each mountTable before use. func (mt *mountTable) Init() { - mt.seed = rand32() mt.size = mtInitOrder mt.slots = newMountTableSlots(mtInitCap) } @@ -167,7 +163,7 @@ func newMountTableSlots(cap uintptr) unsafe.Pointer { // Lookup may be called even if there are concurrent mutators of mt. func (mt *mountTable) Lookup(parent *Mount, point *Dentry) *Mount { key := mountKey{parent: unsafe.Pointer(parent), point: unsafe.Pointer(point)} - hash := memhash(gohacks.Noescape(unsafe.Pointer(&key)), uintptr(mt.seed), mountKeyBytes) + hash := key.hash() loop: for { @@ -247,7 +243,7 @@ func (mt *mountTable) Insert(mount *Mount) { // * mt.seq must be in a writer critical section. // * mt must not already contain a Mount with the same mount point and parent. func (mt *mountTable) insertSeqed(mount *Mount) { - hash := memhash(unsafe.Pointer(&mount.key), uintptr(mt.seed), mountKeyBytes) + hash := mount.key.hash() // We're under the maximum load factor if: // @@ -346,7 +342,7 @@ func (mt *mountTable) Remove(mount *Mount) { // * mt.seq must be in a writer critical section. // * mt must contain mount. func (mt *mountTable) removeSeqed(mount *Mount) { - hash := memhash(unsafe.Pointer(&mount.key), uintptr(mt.seed), mountKeyBytes) + hash := mount.key.hash() tcap := uintptr(1) << (mt.size & mtSizeOrderMask) mask := tcap - 1 slots := mt.slots @@ -386,9 +382,3 @@ func (mt *mountTable) removeSeqed(mount *Mount) { off = (off + mountSlotBytes) & offmask } } - -//go:linkname memhash runtime.memhash -func memhash(p unsafe.Pointer, seed, s uintptr) uintptr - -//go:linkname rand32 runtime.fastrand -func rand32() uint32 |