Add documentation for the dynamic code modifications.

src/trusted/validator_ragel/unreviewed/validator_internal.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.
  */
 
 /*
  * This file contains common parts of x86-32 and x86-64 insternals (inline
  * functions and defines).
  */
@@ skipping 352 matching lines @@
  * in a current instruction.
  */
 static FORCEINLINE void rel8_operand(const uint8_t *rip,
                                      const uint8_t* codeblock_start,
                                      bitmap_word *jump_dests,
                                      size_t jumpdests_size,
                                      uint32_t *instruction_info_collected) {
   int8_t offset = (uint8_t) (rip[-1]);
   size_t jump_dest = offset + (rip - codeblock_start);
 
-  if (!MarkJumpTarget(jump_dest, jump_dests, jumpdests_size)) {
-    *instruction_info_collected |= DIRECT_JUMP_OUT_OF_RANGE;
-  }
+  if (!MarkJumpTarget(jump_dest, jump_dests, jumpdests_size))
+    *instruction_info_collected |= RELATIVE_8BIT | DIRECT_JUMP_OUT_OF_RANGE;
+  else
+    *instruction_info_collected |= RELATIVE_8BIT;
 }
 
 /*
  * Process rel32_operand.  Note: rip points to the beginning of the next
  * instruction here and x86 encoding guarantees rel32 field is the last one
  * in a current instruction.
  */
 static FORCEINLINE void rel32_operand(const uint8_t *rip,
                                       const uint8_t* codeblock_start,
                                       bitmap_word *jump_dests,
                                       size_t jumpdests_size,
                                       uint32_t *instruction_info_collected) {
   int32_t offset = (rip[-4] + 256U * (rip[-3] + 256U * (
                                        rip[-2] + 256U * ((uint32_t) rip[-1]))));
   size_t jump_dest = offset + (rip - codeblock_start);
 
-  if (!MarkJumpTarget(jump_dest, jump_dests, jumpdests_size)) {
-    *instruction_info_collected |= DIRECT_JUMP_OUT_OF_RANGE;
-  }
+  if (!MarkJumpTarget(jump_dest, jump_dests, jumpdests_size))
+    *instruction_info_collected |= RELATIVE_32BIT | DIRECT_JUMP_OUT_OF_RANGE;
+  else
+    *instruction_info_collected |= RELATIVE_32BIT;
 }
 
 static INLINE void check_access(ptrdiff_t instruction_start,
                                 enum register_name base,
                                 enum register_name index,
                                 uint8_t restricted_register,
                                 bitmap_word *valid_targets,
                                 uint32_t *instruction_info_collected) {
   if ((base == REG_RIP) || (base == REG_R15) ||
       (base == REG_RSP) || (base == REG_RBP)) {
@@ skipping 153 matching lines @@
       *instruction_info_collected |= RESTRICTED_RBP_UNPROCESSED;
     }
   /* Take 2 bits of operand type from operand_states as *restricted_register,
    * make sure operand_states denotes a register (12th bit == 0).  */
   } else if ((operand_states & 0x7000) == (OperandSandboxRestricted << 13)) {
     *restricted_register = (operand_states & 0x0f00) >> 8;
   }
 }
 
 #endif  /* NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_RAGEL_VALIDATOR_INTERNAL_H_ */