ARM validator: fix sandbox escape with SP update at the end of the last bundle

src/trusted/validator_arm/model.h

Index: src/trusted/validator_arm/model.h
diff --git a/src/trusted/validator_arm/model.h b/src/trusted/validator_arm/model.h
index 9d704c937a2fadfb6e9372692a6000e065d3d135..55c2f272e42011f90e934a240ce5a0f56b70c1de 100644
--- a/src/trusted/validator_arm/model.h
+++ b/src/trusted/validator_arm/model.h
@@ -286,6 +286,9 @@ static const uint32_t kHaltFill = NACL_INSTR_ARM_HALT_FILL;
 static const uint32_t kAbortNow = NACL_INSTR_ARM_ABORT_NOW;
 static const uint32_t kFailValidation = NACL_INSTR_ARM_FAIL_VALIDATION;
 
+// Not-so-special instructions.
+static const uint32_t kNop = NACL_INSTR_ARM_NOP;

[Mark Seaborn, 2012/11/13 00:30:18]

Would it make sense for the code to refer to NACL_INSTR_ARM_NOP rather than
kNop?  Why have an alias?  Having a single name could be better for greppability
of the code.

[JF, 2012/11/13 00:49:42]

It's following the pattern above of having validator names for the macros.

+
 // Models an instruction, either a 32-bit ARM instruction of unspecified type,
 // or one word (16-bit) and two word (32-bit) THUMB instructions.
 //