Add example to run as unprotected VM bootloader.
Bug: 223166344
Test: Ran unprotected VM under crosvm.
Change-Id: I4e130bf79852f3cd04883fa8474258f8a5bbe69b
diff --git a/vmbase/example/idmap.S b/vmbase/example/idmap.S
new file mode 100644
index 0000000..f1df6cc
--- /dev/null
+++ b/vmbase/example/idmap.S
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * 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
+ *
+ * https://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.
+ */
+
+.set .L_TT_TYPE_BLOCK, 0x1
+.set .L_TT_TYPE_PAGE, 0x3
+.set .L_TT_TYPE_TABLE, 0x3
+
+/* Access flag. */
+.set .L_TT_AF, 0x1 << 10
+/* Not global. */
+.set .L_TT_NG, 0x1 << 11
+.set .L_TT_RO, 0x2 << 6
+.set .L_TT_XN, 0x3 << 53
+
+.set .L_TT_MT_DEV, 0x0 << 2 // MAIR #0 (DEV_nGnRE)
+.set .L_TT_MT_MEM, (0x1 << 2) | (0x3 << 8) // MAIR #1 (MEM_WBWA), inner shareable
+
+.set .L_BLOCK_RO, .L_TT_TYPE_BLOCK | .L_TT_MT_MEM | .L_TT_AF | .L_TT_RO | .L_TT_XN
+.set .L_BLOCK_DEV, .L_TT_TYPE_BLOCK | .L_TT_MT_DEV | .L_TT_AF | .L_TT_XN
+.set .L_BLOCK_MEM, .L_TT_TYPE_BLOCK | .L_TT_MT_MEM | .L_TT_AF | .L_TT_XN | .L_TT_NG
+.set .L_BLOCK_MEM_XIP, .L_TT_TYPE_BLOCK | .L_TT_MT_MEM | .L_TT_AF | .L_TT_NG | .L_TT_RO
+
+.section ".rodata.idmap", "a", %progbits
+.global idmap
+.align 12
+idmap:
+ /* level 1 */
+ .quad .L_BLOCK_DEV | 0x0 // 1 GB of device mappings
+ .quad .L_BLOCK_DEV | 0x40000000 // Another 1 GB of device mapppings
+ .quad .L_TT_TYPE_TABLE + 0f // up to 1 GB of DRAM
+ .fill 509, 8, 0x0 // 509 GB of remaining VA space
+
+ /* level 2 */
+0: .quad .L_BLOCK_RO | 0x80000000 // DT provided by VMM
+ .quad .L_BLOCK_MEM_XIP | 0x80200000 // 2 MB of DRAM containing image
+ .quad .L_BLOCK_MEM | 0x80400000 // 2 MB of writable DRAM
+ .fill 509, 8, 0x0