Change BKPT and UDF encodings on ARM.

src/include/arm_sandbox.h

+/*
+ * Copyright (c) 2012 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* @file

[Mark Seaborn, 2012/10/18 22:05:30]

We don't support Doxygen any more -- you can omit this.

+ *
+ * Minimal ARM sandbox constants.
+ *
+ * These constants are used in C code as well as assembly, hence the use of
+ * the preprocessor.
+ */
+
+#ifndef NATIVE_CLIENT_SRC_INCLUDE_ARM_SANDBOX_H_
+#define NATIVE_CLIENT_SRC_INCLUDE_ARM_SANDBOX_H_ 1
+
+// Specially chosen BKPT and UDF instructions that also correspond to

[Mark Seaborn, 2012/10/18 22:05:30]

Please use C-style comments

+// BKPT and UDF when decoded as Thumb instructions.
+//  - BKPT #0x5BE0 is used as literal pool head.
+//  - BKPT #0x5BEF is used as generic breakpoint.
+//  - UDF #0xEDEF is used as halt-fill.
+//  - UDF #0xEDE0 is used as abort-now (such as __builtin_trap).
+//  - UDF #0xEDE1 is used to always fail validation.
+// All other BKPT/UDF values are disallowed by the validator out of paranoia.
+#define NACL_INSTR_LITERAL_POOL_HEAD 0xE125BE70
+#define NACL_INSTR_BREAKPOINT        0xE125BE7F
+#define NACL_INSTR_HALT_FILL         0xE7FEDEFF
+#define NACL_INSTR_ABORT_NOW         0xE7FEDEF0
+#define NACL_INSTR_FAIL_VALIDATION   0xE7FEDEF1
+
+#endif  /* NATIVE_CLIENT_SRC_INCLUDE_ARM_SANDBOX_H_ */