Decouple filemem from platform and move it to pgalloc.MemoryFile.

This is in preparation for improved page cache reclaim, which requires
greater integration between the page cache and page allocator.

PiperOrigin-RevId: 238444706
Change-Id: Id24141b3678d96c7d7dc24baddd9be555bffafe4

1 files changed, 40 insertions, 0 deletions

diff --git a/pkg/sentry/pgalloc/pgalloc_unsafe.go b/pkg/sentry/pgalloc/pgalloc_unsafe.go
new file mode 100644
index 000000000..33b0a68a8
--- /dev/null
+++ b/pkg/sentry/pgalloc/pgalloc_unsafe.go
@@ -0,0 +1,40 @@
+// 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 pgalloc
+
+import (
+	"reflect"
+	"syscall"
+	"unsafe"
+)
+
+func unsafeSlice(addr uintptr, length int) (slice []byte) {
+	sh := (*reflect.SliceHeader)(unsafe.Pointer(&slice))
+	sh.Data = addr
+	sh.Len = length
+	sh.Cap = length
+	return
+}
+
+func mincore(s []byte, buf []byte) error {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_MINCORE,
+		uintptr(unsafe.Pointer(&s[0])),
+		uintptr(len(s)),
+		uintptr(unsafe.Pointer(&buf[0]))); errno != 0 {
+		return errno
+	}
+	return nil
+}