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/* Copyright (C) 2013-2015 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* Virtual Table Pointer Security. */
#ifndef VTABLE_VERIFY_H
#define VTABLE_VERIFY_H
#include "sbitmap.h"
#include "hash-table.h"
/* The function decl used to create calls to __VLTVtableVerify. It must
be global because it needs to be initialized in the C++ front end, but
used in the middle end (in the vtable verification pass). */
extern tree verify_vtbl_ptr_fndecl;
/* Global variable keeping track of how many vtable map variables we
have created. */
extern unsigned num_vtable_map_nodes;
/* Keep track of how many virtual calls we are actually verifying. */
extern int total_num_virtual_calls;
extern int total_num_verified_vcalls;
/* Each vtable map variable corresponds to a virtual class. Each
vtable map variable has a hash table associated with it, that keeps
track of the vtable pointers for which we have generated a call to
__VLTRegisterPair (with the current vtable map variable). This is
the hash table node that is used for each entry in this hash table
of vtable pointers.
Sometimes there are multiple valid vtable pointer entries that use
the same vtable pointer decl with different offsets. Therefore,
for each vtable pointer in the hash table, there is also an array
of offsets used with that vtable. */
struct vtable_registration
{
tree vtable_decl; /* The var decl of the vtable. */
vec<unsigned> offsets; /* The offsets array. */
};
struct registration_hasher : typed_noop_remove <struct vtable_registration>
{
typedef struct vtable_registration value_type;
typedef struct vtable_registration compare_type;
static inline hashval_t hash (const value_type *);
static inline bool equal (const value_type *, const compare_type *);
};
typedef hash_table<registration_hasher> register_table_type;
typedef register_table_type::iterator registration_iterator_type;
/* This struct is used to represent the class hierarchy information
that we need. Each vtable map variable has an associated class
hierarchy node (struct vtv_graph_node). Note: In this struct,
'children' means immediate descendants in the class hierarchy;
'descendant' means any descendant however many levels deep. */
struct vtv_graph_node {
tree class_type; /* The record_type of the class. */
unsigned class_uid; /* A unique, monotonically
ascending id for class node.
Each vtable map node also has
an id. The class uid is the
same as the vtable map node id
for nodes corresponding to the
same class. */
unsigned num_processed_children; /* # of children for whom we have
computed the class hierarchy
transitive closure. */
vec<struct vtv_graph_node *> parents; /* Vector of parents in the graph. */
vec<struct vtv_graph_node *> children; /* Vector of children in the graph.*/
sbitmap descendants; /* Bitmap representing all this node's
descendants in the graph. */
};
/* This is the node used for our hashtable of vtable map variable
information. When we create a vtable map variable (var decl) we
put it into one of these nodes; create a corresponding
vtv_graph_node for our class hierarchy info and store that in this
node; generate a unique (monotonically ascending) id for both the
vtbl_map_node and the vtv_graph_node; and insert the node into two
data structures (to make it easy to find in several different
ways): 1). A hash table ("vtbl_map_hash" in vtable-verify.c).
This gives us an easy way to check to see if we already have a node
for the vtable map variable or not; and 2). An array (vector) of
vtbl_map_nodes, where the array index corresponds to the unique id
of the vtbl_map_node, which gives us an easy way to use bitmaps to
represent and find the vtable map nodes. */
struct vtbl_map_node {
tree vtbl_map_decl; /* The var decl for the vtable map
variable. */
tree class_name; /* The DECL_ASSEMBLER_NAME of the
class. */
struct vtv_graph_node *class_info; /* Our class hierarchy info for the
class. */
unsigned uid; /* The unique id for the vtable map
variable. */
struct vtbl_map_node *next, *prev; /* Pointers for the linked list
structure. */
register_table_type *registered; /* Hashtable of vtable pointers for which
we have generated a _VLTRegisterPair
call with this vtable map variable. */
bool is_used; /* Boolean indicating if we used this vtable map
variable in a call to __VLTVerifyVtablePointer. */
};
/* Controls debugging for vtable verification. */
extern bool vtv_debug;
/* The global vector of vtbl_map_nodes. */
extern vec<struct vtbl_map_node *> vtbl_map_nodes_vec;
extern struct vtbl_map_node *vtbl_map_get_node (tree);
extern struct vtbl_map_node *find_or_create_vtbl_map_node (tree);
extern void vtbl_map_node_class_insert (struct vtbl_map_node *, unsigned);
extern bool vtbl_map_node_registration_find (struct vtbl_map_node *,
tree, unsigned);
extern bool vtbl_map_node_registration_insert (struct vtbl_map_node *,
tree, unsigned);
#endif /* VTABLE_VERIFY_H */
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