1 files changed, 77 insertions, 0 deletions
diff --git a/pkg/ring0/pagetables/pagetables_amd64.go b/pkg/ring0/pagetables/pagetables_amd64.go
new file mode 100644
index 000000000..a217f404c
--- /dev/null
+++ b/pkg/ring0/pagetables/pagetables_amd64.go
@@ -0,0 +1,77 @@
+// Copyright 2018 The gVisor Authors.
+//
+// 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 pagetables
+
+// Address constraints.
+//
+// The lowerTop and upperBottom currently apply to four-level pagetables;
+// additional refactoring would be necessary to support five-level pagetables.
+const (
+	lowerTop    = 0x00007fffffffffff
+	upperBottom = 0xffff800000000000
+
+	pteShift = 12
+	pmdShift = 21
+	pudShift = 30
+	pgdShift = 39
+
+	pteMask = 0x1ff << pteShift
+	pmdMask = 0x1ff << pmdShift
+	pudMask = 0x1ff << pudShift
+	pgdMask = 0x1ff << pgdShift
+
+	pteSize = 1 << pteShift
+	pmdSize = 1 << pmdShift
+	pudSize = 1 << pudShift
+	pgdSize = 1 << pgdShift
+
+	executeDisable = 1 << 63
+	entriesPerPage = 512
+)
+
+// InitArch does some additional initialization related to the architecture.
+//
+// +checkescape:hard,stack
+//go:nosplit
+func (p *PageTables) InitArch(allocator Allocator) {
+	if p.upperSharedPageTables != nil {
+		p.cloneUpperShared()
+	}
+}
+
+//go:nosplit
+func pgdIndex(upperStart uintptr) uintptr {
+	if upperStart&(pgdSize-1) != 0 {
+		panic("upperStart should be pgd size aligned")
+	}
+	if upperStart >= upperBottom {
+		return entriesPerPage/2 + (upperStart-upperBottom)/pgdSize
+	}
+	if upperStart < lowerTop {
+		return upperStart / pgdSize
+	}
+	panic("upperStart should be in canonical range")
+}
+
+// cloneUpperShared clone the upper from the upper shared page tables.
+//
+//go:nosplit
+func (p *PageTables) cloneUpperShared() {
+	start := pgdIndex(p.upperStart)
+	copy(p.root[start:entriesPerPage], p.upperSharedPageTables.root[start:entriesPerPage])
+}
+
+// PTEs is a collection of entries.
+type PTEs [entriesPerPage]PTE