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Diffstat (limited to 'gcc/cp/vtable-class-hierarchy.c')
| -rw-r--r-- | gcc/cp/vtable-class-hierarchy.c | 1342 |
1 files changed, 1342 insertions, 0 deletions
diff --git a/gcc/cp/vtable-class-hierarchy.c b/gcc/cp/vtable-class-hierarchy.c new file mode 100644 index 00000000000..78611a83264 --- /dev/null +++ b/gcc/cp/vtable-class-hierarchy.c @@ -0,0 +1,1342 @@ +/* Copyright (C) 2012-2013 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 Pass - Detect corruption of vtable pointers + before using them for virtual method dispatches. */ + +/* This file is part of the vtable security feature implementation. + The vtable security feature is designed to detect when a virtual + call is about to be made through an invalid vtable pointer + (possibly due to data corruption or malicious attacks). The + compiler finds every virtual call, and inserts a verification call + before the virtual call. The verification call takes the actual + vtable pointer value in the object through which the virtual call + is being made, and compares the vtable pointer against a set of all + valid vtable pointers that the object could contain (this set is + based on the declared type of the object). If the pointer is in + the valid set, execution is allowed to continue; otherwise the + program is halted. + + There are several pieces needed in order to make this work: 1. For + every virtual class in the program (i.e. a class that contains + virtual methods), we need to build the set of all possible valid + vtables that an object of that class could point to. This includes + vtables for any class(es) that inherit from the class under + consideration. 2. For every such data set we build up, we need a + way to find and reference the data set. This is complicated by the + fact that the real vtable addresses are not known until runtime, + when the program is loaded into memory, but we need to reference the + sets at compile time when we are inserting verification calls into + the program. 3. We need to find every virtual call in the program, + and insert the verification call (with the appropriate arguments) + before the virtual call. 4. We need some runtime library pieces: + the code to build up the data sets at runtime; the code to actually + perform the verification using the data sets; and some code to set + protections on the data sets, so they themselves do not become + hacker targets. + + To find and reference the set of valid vtable pointers for any given + virtual class, we create a special global varible for each virtual + class. We refer to this as the "vtable map variable" for that + class. The vtable map variable has the type "void *", and is + initialized by the compiler to NULL. At runtime when the set of + valid vtable pointers for a virtual class, e.g. class Foo, is built, + the vtable map variable for class Foo is made to point to the set. + During compile time, when the compiler is inserting verification + calls into the program, it passes the vtable map variable for the + appropriate class to the verification call, so that at runtime the + verification call can find the appropriate data set. + + The actual set of valid vtable pointers for a virtual class, + e.g. class Foo, cannot be built until runtime, when the vtables get + loaded into memory and their addresses are known. But the knowledge + about which vtables belong in which class' hierarchy is only known + at compile time. Therefore at compile time we collect class + hierarchy and vtable information about every virtual class, and we + generate calls to build up the data sets at runtime. To build the + data sets, we call one of the functions we add to the runtime + library, __VLTRegisterPair. __VLTRegisterPair takes two arguments, + a vtable map variable and the address of a vtable. If the vtable + map variable is currently NULL, it creates a new data set (hash + table), makes the vtable map variable point to the new data set, and + inserts the vtable address into the data set. If the vtable map + variable is not NULL, it just inserts the vtable address into the + data set. In order to make sure that our data sets are built before + any verification calls happen, we create a special constructor + initialization function for each compilation unit, give it a very + high initialization priority, and insert all of our calls to + __VLTRegisterPair into our special constructor initialization + function. + + The vtable verification feature is controlled by the flag + '-fvtable-verify='. There are three flavors of this: + '-fvtable-verify=std', '-fvtable-verify=preinit', and + '-fvtable-verify=none'. If the option '-fvtable-verfy=preinit' is + used, then our constructor initialization function gets put into the + preinit array. This is necessary if there are data sets that need + to be built very early in execution. If the constructor + initialization function gets put into the preinit array, the we also + add calls to __VLTChangePermission at the beginning and end of the + function. The call at the beginning sets the permissions on the + data sets and vtable map variables to read/write, and the one at the + end makes them read-only. If the '-fvtable-verify=std' option is + used, the constructor initialization functions are executed at their + normal time, and the __VLTChangePermission calls are handled + differently (see the comments in libstdc++-v3/libsupc++/vtv_rts.cc). + The option '-fvtable-verify=none' turns off vtable verification. + + This file contains code to find and record the class hierarchies for + the virtual classes in a program, and all the vtables associated + with each such class; to generate the vtable map variables; and to + generate the constructor initialization function (with the calls to + __VLTRegisterPair, and __VLTChangePermission). The main data + structures used for collecting the class hierarchy data and + building/maintaining the vtable map variable data are defined in + gcc/vtable-verify.h, because they are used both here and in + gcc/vtable-verify.c. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "cp-tree.h" +#include "output.h" +#include "cgraph.h" +#include "tree-iterator.h" +#include "vtable-verify.h" +#include "gimple.h" + +static int num_calls_to_regset = 0; +static int num_calls_to_regpair = 0; +static int current_set_size; + +/* Mark these specially since they need to be stored in precompiled + header IR. */ +static GTY (()) vec<tree, va_gc> *vlt_saved_class_info; +static GTY (()) tree vlt_register_pairs_fndecl = NULL_TREE; +static GTY (()) tree vlt_register_set_fndecl = NULL_TREE; + +struct work_node { + struct vtv_graph_node *node; + struct work_node *next; +}; + +struct vtbl_map_node *vtable_find_or_create_map_decl (tree); + +/* As part of vtable verification the compiler generates and inserts + calls to __VLTVerifyVtablePointer, which is in libstdc++. This + function builds and initializes the function decl that is used + in generating those function calls. + + In addition to __VLTVerifyVtablePointer there is also + __VLTVerifyVtablePointerDebug which can be used in place of + __VLTVerifyVtablePointer, and which takes extra parameters and + outputs extra information, to help debug problems. The debug + version of this function is generated and used if flag_vtv_debug is + true. + + The signatures for these functions are: + + void * __VLTVerifyVtablePointer (void **, void*); + void * __VLTVerifyVtablePointerDebug (void**, void *, char *, char *); +*/ + +void +vtv_build_vtable_verify_fndecl (void) +{ + tree func_type = NULL_TREE; + + if (verify_vtbl_ptr_fndecl != NULL_TREE + && TREE_CODE (verify_vtbl_ptr_fndecl) != ERROR_MARK) + return; + + if (flag_vtv_debug) + { + func_type = build_function_type_list (const_ptr_type_node, + build_pointer_type (ptr_type_node), + const_ptr_type_node, + const_string_type_node, + const_string_type_node, + NULL_TREE); + verify_vtbl_ptr_fndecl = + build_lang_decl (FUNCTION_DECL, + get_identifier ("__VLTVerifyVtablePointerDebug"), + func_type); + } + else + { + func_type = build_function_type_list (const_ptr_type_node, + build_pointer_type (ptr_type_node), + const_ptr_type_node, + NULL_TREE); + verify_vtbl_ptr_fndecl = + build_lang_decl (FUNCTION_DECL, + get_identifier ("__VLTVerifyVtablePointer"), + func_type); + } + + TREE_NOTHROW (verify_vtbl_ptr_fndecl) = 1; + DECL_ATTRIBUTES (verify_vtbl_ptr_fndecl) + = tree_cons (get_identifier ("leaf"), NULL, + DECL_ATTRIBUTES (verify_vtbl_ptr_fndecl)); + DECL_PURE_P (verify_vtbl_ptr_fndecl) = 1; + TREE_PUBLIC (verify_vtbl_ptr_fndecl) = 1; + DECL_PRESERVE_P (verify_vtbl_ptr_fndecl) = 1; +} + +/* As part of vtable verification the compiler generates and inserts + calls to __VLTRegisterSet and __VLTRegisterPair, which are in + libsupc++. This function builds and initializes the function decls + that are used in generating those function calls. + + The signatures for these functions are: + + void __VLTRegisterSetDebug (void **, const void *, std::size_t, + size_t, void **); + + void __VLTRegisterSet (void **, const void *, std::size_t, + size_t, void **); + + void __VLTRegisterPairDebug (void **, const void *, size_t, + const void *, const char *, const char *); + + void __VLTRegisterPair (void **, const void *, size_t, const void *); +*/ + +static void +init_functions (void) +{ + tree register_set_type; + tree register_pairs_type; + + if (vlt_register_set_fndecl != NULL_TREE) + return; + + gcc_assert (vlt_register_pairs_fndecl == NULL_TREE); + gcc_assert (vlt_register_set_fndecl == NULL_TREE); + + /* Build function decl for __VLTRegisterSet*. */ + + register_set_type = build_function_type_list + (void_type_node, + build_pointer_type (ptr_type_node), + const_ptr_type_node, + size_type_node, + size_type_node, + build_pointer_type (ptr_type_node), + NULL_TREE); + + if (flag_vtv_debug) + vlt_register_set_fndecl = build_lang_decl + (FUNCTION_DECL, + get_identifier ("__VLTRegisterSetDebug"), + register_set_type); + else + vlt_register_set_fndecl = build_lang_decl + (FUNCTION_DECL, + get_identifier ("__VLTRegisterSet"), + register_set_type); + + + TREE_NOTHROW (vlt_register_set_fndecl) = 1; + DECL_ATTRIBUTES (vlt_register_set_fndecl) = + tree_cons (get_identifier ("leaf"), NULL, + DECL_ATTRIBUTES (vlt_register_set_fndecl)); + TREE_PUBLIC (vlt_register_set_fndecl) = 1; + DECL_PRESERVE_P (vlt_register_set_fndecl) = 1; + SET_DECL_LANGUAGE (vlt_register_set_fndecl, lang_cplusplus); + + /* Build function decl for __VLTRegisterPair*. */ + + if (flag_vtv_debug) + { + register_pairs_type = build_function_type_list (void_type_node, + build_pointer_type + (ptr_type_node), + const_ptr_type_node, + size_type_node, + const_ptr_type_node, + const_string_type_node, + const_string_type_node, + NULL_TREE); + + vlt_register_pairs_fndecl = build_lang_decl + (FUNCTION_DECL, + get_identifier ("__VLTRegisterPairDebug"), + register_pairs_type); + } + else + { + register_pairs_type = build_function_type_list (void_type_node, + build_pointer_type + (ptr_type_node), + const_ptr_type_node, + size_type_node, + const_ptr_type_node, + NULL_TREE); + + vlt_register_pairs_fndecl = build_lang_decl + (FUNCTION_DECL, + get_identifier ("__VLTRegisterPair"), + register_pairs_type); + } + + TREE_NOTHROW (vlt_register_pairs_fndecl) = 1; + DECL_ATTRIBUTES (vlt_register_pairs_fndecl) = + tree_cons (get_identifier ("leaf"), NULL, + DECL_ATTRIBUTES (vlt_register_pairs_fndecl)); + TREE_PUBLIC (vlt_register_pairs_fndecl) = 1; + DECL_PRESERVE_P (vlt_register_pairs_fndecl) = 1; + SET_DECL_LANGUAGE (vlt_register_pairs_fndecl, lang_cplusplus); + +} + +/* This is a helper function for + vtv_compute_class_hierarchy_transitive_closure. It adds a + vtv_graph_node to the WORKLIST, which is a linked list of + seen-but-not-yet-processed nodes. INSERTED is a bitmap, one bit + per node, to help make sure that we don't insert a node into the + worklist more than once. Each node represents a class somewhere in + our class hierarchy information. Every node in the graph gets added + to the worklist exactly once and removed from the worklist exactly + once (when all of its children have been processed). */ + +static void +add_to_worklist (struct work_node **worklist, struct vtv_graph_node *node, + sbitmap inserted) +{ + struct work_node *new_work_node; + + if (bitmap_bit_p (inserted, node->class_uid)) + return; + + new_work_node = XNEW (struct work_node); + new_work_node->next = *worklist; + new_work_node->node = node; + *worklist = new_work_node; + + bitmap_set_bit (inserted, node->class_uid); +} + +/* This is a helper function for + vtv_compute_class_hierarchy_transitive_closure. It goes through + the WORKLIST of class hierarchy nodes looking for a "leaf" node, + i.e. a node whose children in the hierarchy have all been + processed. When it finds the next leaf node, it removes it from + the linked list (WORKLIST) and returns the node. */ + +static struct vtv_graph_node * +find_and_remove_next_leaf_node (struct work_node **worklist) +{ + struct work_node *prev, *cur; + struct vtv_graph_node *ret_val = NULL; + + for (prev = NULL, cur = *worklist; cur; prev = cur, cur = cur->next) + { + if ((cur->node->children).length() == cur->node->num_processed_children) + { + if (prev == NULL) + (*worklist) = cur->next; + else + prev->next = cur->next; + + cur->next = NULL; + ret_val = cur->node; + free (cur); + return ret_val; + } + } + + return NULL; +} + +/* In our class hierarchy graph, each class node contains a bitmap, + with one bit for each class in the hierarchy. The bits are set for + classes that are descendants in the graph of the current node. + Initially the descendants bitmap is only set for immediate + descendants. This function traverses the class hierarchy graph, + bottom up, filling in the transitive closures for the descendants + as we rise up the graph. */ + +void +vtv_compute_class_hierarchy_transitive_closure (void) +{ + struct work_node *worklist = NULL; + sbitmap inserted = sbitmap_alloc (num_vtable_map_nodes); + unsigned i; + unsigned j; + + /* Note: Every node in the graph gets added to the worklist exactly + once and removed from the worklist exactly once (when all of its + children have been processed). Each node's children edges are + followed exactly once, and each node's parent edges are followed + exactly once. So this algorithm is roughly O(V + 2E), i.e. + O(E + V). */ + + /* Set-up: */ + /* Find all the "leaf" nodes in the graph, and add them to the worklist. */ + bitmap_clear (inserted); + for (j = 0; j < num_vtable_map_nodes; ++j) + { + struct vtbl_map_node *cur = vtbl_map_nodes_vec[j]; + if (cur->class_info + && ((cur->class_info->children).length() == 0) + && ! (bitmap_bit_p (inserted, cur->class_info->class_uid))) + add_to_worklist (&worklist, cur->class_info, inserted); + } + + /* Main work: pull next leaf node off work list, process it, add its + parents to the worklist, where a 'leaf' node is one that has no + children, or all of its children have been processed. */ + while (worklist) + { + struct vtv_graph_node *temp_node = + find_and_remove_next_leaf_node (&worklist); + + gcc_assert (temp_node != NULL); + temp_node->descendants = sbitmap_alloc (num_vtable_map_nodes); + bitmap_clear (temp_node->descendants); + bitmap_set_bit (temp_node->descendants, temp_node->class_uid); + for (i = 0; i < (temp_node->children).length(); ++i) + bitmap_ior (temp_node->descendants, temp_node->descendants, + temp_node->children[i]->descendants); + for (i = 0; i < (temp_node->parents).length(); ++i) + { + temp_node->parents[i]->num_processed_children = + temp_node->parents[i]->num_processed_children + 1; + if (!bitmap_bit_p (inserted, temp_node->parents[i]->class_uid)) + add_to_worklist (&worklist, temp_node->parents[i], inserted); + } + } +} + +/* Keep track of which pairs we have already created __VLTRegisterPair + calls for, to prevent creating duplicate calls within the same + compilation unit. VTABLE_DECL is the var decl for the vtable of + the (descendant) class that we are adding to our class hierarchy + data. VPTR_ADDRESS is an expression for calculating the correct + offset into the vtable (VTABLE_DECL). It is the actual vtable + pointer address that will be stored in our list of valid vtable + pointers for BASE_CLASS. BASE_CLASS is the record_type node for + the base class to whose hiearchy we want to add + VPTR_ADDRESS. (VTABLE_DECL should be the vtable for BASE_CLASS or + one of BASE_CLASS' descendents. */ + +static bool +check_and_record_registered_pairs (tree vtable_decl, tree vptr_address, + tree base_class) +{ + unsigned offset; + struct vtbl_map_node *base_vtable_map_node; + bool inserted_something = false; + + + if (TREE_CODE (vptr_address) == ADDR_EXPR + && TREE_CODE (TREE_OPERAND (vptr_address, 0)) == MEM_REF) + vptr_address = TREE_OPERAND (vptr_address, 0); + + if (TREE_OPERAND_LENGTH (vptr_address) > 1) + offset = TREE_INT_CST_LOW (TREE_OPERAND (vptr_address, 1)); + else + offset = 0; + + base_vtable_map_node = vtbl_map_get_node (TYPE_MAIN_VARIANT (base_class)); + + inserted_something = vtbl_map_node_registration_insert + (base_vtable_map_node, + vtable_decl, + offset); + return !inserted_something; +} + +/* Given an IDENTIFIER_NODE, build and return a string literal based on it. */ + +static tree +build_string_from_id (tree identifier) +{ + int len; + + gcc_assert (TREE_CODE (identifier) == IDENTIFIER_NODE); + + len = IDENTIFIER_LENGTH (identifier); + return build_string_literal (len + 1, IDENTIFIER_POINTER (identifier)); +} + +/* A class may contain secondary vtables in it, for various reasons. + This function goes through the decl chain of a class record looking + for any fields that point to secondary vtables, and adding calls to + __VLTRegisterPair for the secondary vtable pointers. + + BASE_CLASS_DECL_ARG is an expression for the address of the vtable + map variable for the BASE_CLASS (whose hierarchy we are currently + updating). BASE_CLASS is the record_type node for the base class. + RECORD_TYPE is the record_type node for the descendant class that + we are possibly adding to BASE_CLASS's hierarchy. BODY is the + function body for the constructor init function to which we are + adding our calls to __VLTRegisterPair. */ + +static void +register_construction_vtables (tree base_class, tree record_type, + vec<tree> *vtable_ptr_array) +{ + tree vtbl_var_decl; + + if (TREE_CODE (record_type) != RECORD_TYPE) + return; + + vtbl_var_decl = CLASSTYPE_VTABLES (record_type); + + if (CLASSTYPE_VBASECLASSES (record_type)) + { + tree vtt_decl; + bool already_registered = false; + tree val_vtbl_decl = NULL_TREE; + + vtt_decl = DECL_CHAIN (vtbl_var_decl); + + /* Check to see if we have found a VTT. Add its data if appropriate. */ + if (vtt_decl) + { + tree values = DECL_INITIAL (vtt_decl); + if (TREE_ASM_WRITTEN (vtt_decl) + && values != NULL_TREE + && TREE_CODE (values) == CONSTRUCTOR + && TREE_CODE (TREE_TYPE (values)) == ARRAY_TYPE) + { + unsigned HOST_WIDE_INT cnt; + constructor_elt *ce; + + /* Loop through the initialization values for this + vtable to get all the correct vtable pointer + addresses that we need to add to our set of valid + vtable pointers for the current base class. This may + result in adding more than just the element assigned + to the primary vptr of the class, so we may end up + with more vtable pointers than are strictly + necessary. */ + + for (cnt = 0; + vec_safe_iterate (CONSTRUCTOR_ELTS (values), + cnt, &ce); + cnt++) + { + tree value = ce->value; + + /* Search for the ADDR_EXPR operand within the value. */ + + while (value + && TREE_OPERAND (value, 0) + && TREE_CODE (TREE_OPERAND (value, 0)) == ADDR_EXPR) + value = TREE_OPERAND (value, 0); + + /* The VAR_DECL for the vtable should be the first + argument of the ADDR_EXPR, which is the first + argument of value.*/ + + if (TREE_OPERAND (value, 0)) + val_vtbl_decl = TREE_OPERAND (value, 0); + + while (TREE_CODE (val_vtbl_decl) != VAR_DECL + && TREE_OPERAND (val_vtbl_decl, 0)) + val_vtbl_decl = TREE_OPERAND (val_vtbl_decl, 0); + + gcc_assert (TREE_CODE (val_vtbl_decl) == VAR_DECL); + + /* Check to see if we already have this vtable pointer in + our valid set for this base class. */ + + already_registered = check_and_record_registered_pairs + (val_vtbl_decl, + value, + base_class); + + if (already_registered) + continue; + + /* Add this vtable pointer to our set of valid + pointers for the base class. */ + + vtable_ptr_array->safe_push (value); + current_set_size++; + } + } + } + } +} + +/* This function iterates through all the vtables it can find from the + BINFO of a class, to make sure we have found ALL of the vtables + that an object of that class could point to. Generate calls to + __VLTRegisterPair for those vtable pointers that we find. + + BINFO is the tree_binfo node for the BASE_CLASS. BODY is the + function body for the constructor init function to which we are + adding calls to __VLTRegisterPair. ARG1 is an expression for the + address of the vtable map variable (for the BASE_CLASS), that will + point to the updated data set. BASE_CLASS is the record_type node + for the base class whose set of valid vtable pointers we are + updating. STR1 and STR2 are all debugging information, to be passed + as parameters to __VLTRegisterPairDebug. STR1 represents the name + of the vtable map variable to be updated by the call. Similarly, + STR2 represents the name of the class whose vtable pointer is being + added to the hierarchy. */ + +static void +register_other_binfo_vtables (tree binfo, tree base_class, + vec<tree> *vtable_ptr_array) +{ + unsigned ix; + tree base_binfo; + tree vtable_decl; + bool already_registered; + + if (binfo == NULL_TREE) + return; + + for (ix = 0; BINFO_BASE_ITERATE (binfo, ix, base_binfo); ix++) + { + if ((!BINFO_PRIMARY_P (base_binfo) + || BINFO_VIRTUAL_P (base_binfo)) + && (vtable_decl = get_vtbl_decl_for_binfo (base_binfo))) + { + tree vtable_address = build_vtbl_address (base_binfo); + + already_registered = check_and_record_registered_pairs + (vtable_decl, + vtable_address, + base_class); + if (!already_registered) + { + vtable_ptr_array->safe_push (vtable_address); + current_set_size++; + } + } + + register_other_binfo_vtables (base_binfo, base_class, vtable_ptr_array); + } +} + +/* The set of valid vtable pointers for any given class are stored in + a hash table. For reasons of efficiency, that hash table size is + always a power of two. In order to try to prevent re-sizing the + hash tables very often, we pass __VLTRegisterPair an initial guess + as to the number of entries the hashtable will eventually need + (rounded up to the nearest power of two). This function takes the + class information we have collected for a particular class, + CLASS_NODE, and calculates the hash table size guess. */ + +static int +guess_num_vtable_pointers (struct vtv_graph_node *class_node) +{ + tree vtbl; + int total_num_vtbls = 0; + int num_vtbls_power_of_two = 1; + unsigned i; + + for (i = 0; i < num_vtable_map_nodes; ++i) + if (bitmap_bit_p (class_node->descendants, i)) + { + tree class_type = vtbl_map_nodes_vec[i]->class_info->class_type; + for (vtbl = CLASSTYPE_VTABLES (class_type); vtbl; + vtbl = DECL_CHAIN (vtbl)) + { + total_num_vtbls++; + if (total_num_vtbls > num_vtbls_power_of_two) + num_vtbls_power_of_two <<= 1; + } + } + return num_vtbls_power_of_two; +} + +/* A simple hash function on strings */ +/* Be careful about changing this routine. The values generated will + be stored in the calls to InitSet. So, changing this routine may + cause a binary incompatibility. */ + +static uint32_t +vtv_string_hash (const char *in) +{ + const char *s = in; + uint32_t h = 0; + + gcc_assert (in != NULL); + for ( ; *s; ++s) + h = 5 * h + *s; + return h; +} + +static char * +get_log_file_name (const char *fname) +{ + const char *tmp_dir = concat (dump_dir_name, NULL); + char *full_name; + int dir_len; + int fname_len; + + dir_len = strlen (tmp_dir); + fname_len = strlen (fname); + + full_name = XNEWVEC (char, dir_len + fname_len + 1); + strcpy (full_name, tmp_dir); + strcpy (full_name + dir_len, fname); + + return full_name; +} + +static void +write_out_current_set_data (tree base_class, int set_size) +{ + static int class_data_log_fd = -1; + char buffer[1024]; + int bytes_written __attribute__ ((unused)); + char *file_name = get_log_file_name ("vtv_class_set_sizes.log"); + + if (class_data_log_fd == -1) + class_data_log_fd = open (file_name, + O_WRONLY | O_APPEND | O_CREAT, S_IRWXU); + + if (class_data_log_fd == -1) + { + warning_at (UNKNOWN_LOCATION, 0, + "unable to open log file %<vtv_class_set_sizes.log%>: %m"); + return; + } + + snprintf (buffer, sizeof (buffer), "%s %d\n", + IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (TYPE_NAME (base_class))), + set_size); + bytes_written = write (class_data_log_fd, buffer, strlen (buffer)); +} + +static tree +build_key_buffer_arg (tree base_ptr_var_decl) +{ + const int key_type_fixed_size = 8; + uint32_t len1 = IDENTIFIER_LENGTH (DECL_NAME (base_ptr_var_decl)); + uint32_t hash_value = vtv_string_hash (IDENTIFIER_POINTER + (DECL_NAME (base_ptr_var_decl))); + void *key_buffer = xmalloc (len1 + key_type_fixed_size); + uint32_t *value_ptr = (uint32_t *) key_buffer; + tree ret_value; + + /* Set the len and hash for the string. */ + *value_ptr = len1; + value_ptr++; + *value_ptr = hash_value; + + /* Now copy the string representation of the vtbl map name... */ + memcpy ((char *) key_buffer + key_type_fixed_size, + IDENTIFIER_POINTER (DECL_NAME (base_ptr_var_decl)), + len1); + + /* ... and build a string literal from it. This will make a copy + so the key_bufffer is not needed anymore after this. */ + ret_value = build_string_literal (len1 + key_type_fixed_size, + (char *) key_buffer); + free (key_buffer); + return ret_value; +} + +static void +insert_call_to_register_set (tree class_name, + vec<tree> *vtbl_ptr_array, tree body, tree arg1, + tree arg2, tree size_hint_arg) +{ + tree call_expr; + int num_args = vtbl_ptr_array->length(); + char *array_arg_name = ACONCAT (("__vptr_array_", + IDENTIFIER_POINTER (class_name), NULL)); + tree array_arg_type = build_array_type_nelts (build_pointer_type + (build_pointer_type + (void_type_node)), + num_args); + tree array_arg = build_decl (UNKNOWN_LOCATION, VAR_DECL, + get_identifier (array_arg_name), + array_arg_type); + int k; + + vec<constructor_elt, va_gc> *array_elements; + vec_alloc (array_elements, num_args); + + tree initial = NULL_TREE; + tree arg3 = NULL_TREE; + + TREE_PUBLIC (array_arg) = 0; + DECL_EXTERNAL (array_arg) = 0; + TREE_STATIC (array_arg) = 1; + DECL_ARTIFICIAL (array_arg) = 0; + TREE_READONLY (array_arg) = 1; + DECL_IGNORED_P (array_arg) = 0; + DECL_PRESERVE_P (array_arg) = 0; + DECL_VISIBILITY (array_arg) = VISIBILITY_HIDDEN; + + for (k = 0; k < num_args; ++k) + { + CONSTRUCTOR_APPEND_ELT (array_elements, NULL_TREE, (*vtbl_ptr_array)[k]); + } + + initial = build_constructor (TREE_TYPE (array_arg), array_elements); + + TREE_CONSTANT (initial) = 1; + TREE_STATIC (initial) = 1; + DECL_INITIAL (array_arg) = initial; + relayout_decl (array_arg); + varpool_finalize_decl (array_arg); + + arg3 = build1 (ADDR_EXPR, TYPE_POINTER_TO (TREE_TYPE (array_arg)), array_arg); + + TREE_TYPE (arg3) = build_pointer_type (TREE_TYPE (array_arg)); + + call_expr = build_call_expr (vlt_register_set_fndecl, 5, arg1, + arg2, /* set_symbol_key */ + size_hint_arg, build_int_cst (size_type_node, + num_args), + arg3); + append_to_statement_list (call_expr, &body); + num_calls_to_regset++; +} + +static void +insert_call_to_register_pair (vec<tree> *vtbl_ptr_array, tree arg1, + tree arg2, tree size_hint_arg, tree str1, + tree str2, tree body) +{ + tree call_expr; + int num_args = vtbl_ptr_array->length(); + tree vtable_address = NULL_TREE; + + if (num_args == 0) + vtable_address = build_int_cst (build_pointer_type (void_type_node), 0); + else + vtable_address = (*vtbl_ptr_array)[0]; + + if (flag_vtv_debug) + call_expr = build_call_expr (vlt_register_pairs_fndecl, 6, arg1, arg2, + size_hint_arg, vtable_address, str1, str2); + else + call_expr = build_call_expr (vlt_register_pairs_fndecl, 4, arg1, arg2, + size_hint_arg, vtable_address); + + append_to_statement_list (call_expr, &body); + num_calls_to_regpair++; +} + +static void +output_set_info (tree record_type, vec<tree> vtbl_ptr_array) +{ + static int vtv_debug_log_fd = -1; + char buffer[1024]; + int bytes_written __attribute__ ((unused)); + int array_len = vtbl_ptr_array.length(); + const char *class_name = + IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (TYPE_NAME (record_type))); + char *file_name = get_log_file_name ("vtv_set_ptr_data.log"); + + if (vtv_debug_log_fd == -1) + vtv_debug_log_fd = open (file_name, + O_WRONLY | O_APPEND | O_CREAT, S_IRWXU); + if (vtv_debug_log_fd == -1) + { + warning_at (UNKNOWN_LOCATION, 0, + "unable to open log file %<vtv_set_ptr_data.log%>: %m"); + return; + } + + for (int i = 0; i < array_len; ++i) + { + const char *vptr_name = "unknown"; + int vptr_offset = 0; + + if (TREE_CODE (vtbl_ptr_array[i]) == POINTER_PLUS_EXPR) + { + tree arg0 = TREE_OPERAND (vtbl_ptr_array[i], 0); + tree arg1 = TREE_OPERAND (vtbl_ptr_array[i], 1); + + if (TREE_CODE (arg0) == ADDR_EXPR) + arg0 = TREE_OPERAND (arg0, 0); + + if (TREE_CODE (arg0) == VAR_DECL) + vptr_name = IDENTIFIER_POINTER (DECL_NAME (arg0)); + + if (TREE_CODE (arg1) == INTEGER_CST) + vptr_offset = TREE_INT_CST_LOW (arg1); + } + + snprintf (buffer, sizeof (buffer), "%s %s %s + %d\n", + main_input_filename, class_name, vptr_name, vptr_offset); + bytes_written = write (vtv_debug_log_fd, buffer, strlen(buffer)); + } + +} + +/* This function goes through our internal class hierarchy & vtable + pointer data structure and outputs calls to __VLTRegisterPair for + every class-vptr pair (for those classes whose vtable would be + output in the current compilation unit). These calls get put into + our constructor initialization function. BODY is the function + body, so far, of our constructor initialization function, to which we + add the calls. */ + +static bool +register_all_pairs (tree body) +{ + bool registered_at_least_one = false; + vec<tree> *vtbl_ptr_array = NULL; + unsigned j; + + for (j = 0; j < num_vtable_map_nodes; ++j) + { + struct vtbl_map_node *current = vtbl_map_nodes_vec[j]; + unsigned i = 0; + tree base_class = current->class_info->class_type; + tree base_ptr_var_decl = current->vtbl_map_decl; + tree arg1; + tree arg2; + tree new_type; + tree str1 = NULL_TREE; + tree str2 = NULL_TREE; + size_t size_hint; + tree size_hint_arg; + + gcc_assert (current->class_info != NULL); + + + if (flag_vtv_debug) + str1 = build_string_from_id (DECL_NAME (base_ptr_var_decl)); + + new_type = build_pointer_type (TREE_TYPE (base_ptr_var_decl)); + arg1 = build1 (ADDR_EXPR, new_type, base_ptr_var_decl); + + /* We need a fresh vector for each iteration. */ + if (vtbl_ptr_array) + vec_free (vtbl_ptr_array); + + vec_alloc (vtbl_ptr_array, 10); + + for (i = 0; i < num_vtable_map_nodes; ++i) + if (bitmap_bit_p (current->class_info->descendants, i)) + { + struct vtbl_map_node *vtbl_class_node = vtbl_map_nodes_vec[i]; + tree class_type = vtbl_class_node->class_info->class_type; + + if (class_type + && (TREE_CODE (class_type) == RECORD_TYPE)) + { + bool already_registered; + + tree binfo = TYPE_BINFO (class_type); + tree vtable_decl; + bool vtable_should_be_output = false; + + vtable_decl = CLASSTYPE_VTABLES (class_type); + + /* Handle main vtable for this class. */ + + if (vtable_decl) + { + vtable_should_be_output = TREE_ASM_WRITTEN (vtable_decl); + str2 = build_string_from_id (DECL_NAME (vtable_decl)); + } + + if (vtable_decl && vtable_should_be_output) + { + tree vtable_address = build_vtbl_address (binfo); + + already_registered = check_and_record_registered_pairs + (vtable_decl, + vtable_address, + base_class); + + + if (!already_registered) + { + vtbl_ptr_array->safe_push (vtable_address); + + /* Find and handle any 'extra' vtables associated + with this class, via virtual inheritance. */ + register_construction_vtables (base_class, class_type, + vtbl_ptr_array); + + /* Find and handle any 'extra' vtables associated + with this class, via multiple inheritance. */ + register_other_binfo_vtables (binfo, base_class, + vtbl_ptr_array); + } + } + } + } + current_set_size = vtbl_ptr_array->length(); + + /* Sometimes we need to initialize the set symbol even if we are + not adding any vtable pointers to the set in the current + compilation unit. In that case, we need to initialize the + set to our best guess as to what the eventual size of the set + hash table will be (to prevent having to re-size the hash + table later). */ + + size_hint = guess_num_vtable_pointers (current->class_info); + + /* If we have added vtable pointers to the set in this + compilation unit, adjust the size hint for the set's hash + table appropriately. */ + if (vtbl_ptr_array->length() > 0) + { + unsigned len = vtbl_ptr_array->length(); + while ((size_t) len > size_hint) + size_hint <<= 1; + } + size_hint_arg = build_int_cst (size_type_node, size_hint); + + /* Get the key-buffer argument. */ + arg2 = build_key_buffer_arg (base_ptr_var_decl); + + if (str2 == NULL_TREE) + str2 = build_string_literal (strlen ("unknown") + 1, + "unknown"); + + if (flag_vtv_debug) + output_set_info (current->class_info->class_type, + *vtbl_ptr_array); + + if (vtbl_ptr_array->length() > 1) + { + insert_call_to_register_set (current->class_name, + vtbl_ptr_array, body, arg1, arg2, + size_hint_arg); + registered_at_least_one = true; + } + else + { + + if (vtbl_ptr_array->length() > 0 + || (current->is_used + || (current->registered.size() > 0))) + { + insert_call_to_register_pair (vtbl_ptr_array, + arg1, arg2, size_hint_arg, str1, + str2, body); + registered_at_least_one = true; + } + } + + if (flag_vtv_counts && current_set_size > 0) + write_out_current_set_data (base_class, current_set_size); + + } + + return registered_at_least_one; +} + +/* Given a tree containing a class type (CLASS_TYPE), this function + finds and returns the class hierarchy node for that class in our + data structure. */ + +static struct vtv_graph_node * +find_graph_node (tree class_type) +{ + struct vtbl_map_node *vtbl_node; + + vtbl_node = vtbl_map_get_node (TYPE_MAIN_VARIANT (class_type)); + if (vtbl_node) + return vtbl_node->class_info; + + return NULL; +} + +/* Add base class/derived class pair to our internal class hierarchy + data structure. BASE_NODE is our vtv_graph_node that corresponds + to a base class. DERIVED_NODE is our vtv_graph_node that + corresponds to a class that is a descendant of the base class + (possibly the base class itself). */ + +static void +add_hierarchy_pair (struct vtv_graph_node *base_node, + struct vtv_graph_node *derived_node) +{ + (base_node->children).safe_push (derived_node); + (derived_node->parents).safe_push (base_node); +} + +/* This functions adds a new base class/derived class relationship to + our class hierarchy data structure. Both parameters are trees + representing the class types, i.e. RECORD_TYPE trees. + DERIVED_CLASS can be the same as BASE_CLASS. */ + +static void +update_class_hierarchy_information (tree base_class, + tree derived_class) +{ + struct vtv_graph_node *base_node = find_graph_node (base_class); + struct vtv_graph_node *derived_node = find_graph_node (derived_class); + + add_hierarchy_pair (base_node, derived_node); +} + + +static void +write_out_vtv_count_data (void) +{ + static int vtv_count_log_fd = -1; + char buffer[1024]; + int unused_vtbl_map_vars = 0; + int bytes_written __attribute__ ((unused)); + char *file_name = get_log_file_name ("vtv_count_data.log"); + + if (vtv_count_log_fd == -1) + vtv_count_log_fd = open (file_name, + O_WRONLY | O_APPEND | O_CREAT, S_IRWXU); + if (vtv_count_log_fd == -1) + { + warning_at (UNKNOWN_LOCATION, 0, + "unable to open log file %<vtv_count_data.log%>: %m"); + return; + } + + for (unsigned i = 0; i < num_vtable_map_nodes; ++i) + { + struct vtbl_map_node *current = vtbl_map_nodes_vec[i]; + if (!current->is_used + && current->registered.size() == 0) + unused_vtbl_map_vars++; + } + + snprintf (buffer, sizeof (buffer), "%s %d %d %d %d %d\n", + main_input_filename, total_num_virtual_calls, + total_num_verified_vcalls, num_calls_to_regset, + num_calls_to_regpair, unused_vtbl_map_vars); + + bytes_written = write (vtv_count_log_fd, buffer, strlen (buffer)); +} + +/* This function calls register_all_pairs, which actually generates + all the calls to __VLTRegisterPair (in the verification constructor + init function). It also generates the calls to + __VLTChangePermission, if the verification constructor init + function is going into the preinit array. INIT_ROUTINE_BODY is + the body of our constructior initialization function, to which we + add our function calls.*/ + +bool +vtv_register_class_hierarchy_information (tree init_routine_body) +{ + bool registered_something = false; + + init_functions (); + + if (num_vtable_map_nodes == 0) + return false; + + /* Add class hierarchy pairs to the vtable map data structure. */ + registered_something = register_all_pairs (init_routine_body); + + if (flag_vtv_counts) + write_out_vtv_count_data (); + + return registered_something; +} + + +/* Generate the special constructor function that calls + __VLTChangePermission and __VLTRegisterPairs, and give it a very + high initialization priority. */ + +void +vtv_generate_init_routine (void) +{ + tree init_routine_body; + bool vtable_classes_found = false; + + push_lang_context (lang_name_c); + + /* The priority for this init function (constructor) is carefully + chosen so that it will happen after the calls to unprotect the + memory used for vtable verification and before the memory is + protected again. */ + init_routine_body = vtv_start_verification_constructor_init_function (); + + vtable_classes_found = + vtv_register_class_hierarchy_information (init_routine_body); + + if (vtable_classes_found) + { + tree vtv_fndecl = + vtv_finish_verification_constructor_init_function (init_routine_body); + TREE_STATIC (vtv_fndecl) = 1; + TREE_USED (vtv_fndecl) = 1; + DECL_PRESERVE_P (vtv_fndecl) = 1; + if (flag_vtable_verify == VTV_PREINIT_PRIORITY) + DECL_STATIC_CONSTRUCTOR (vtv_fndecl) = 0; + + gimplify_function_tree (vtv_fndecl); + cgraph_add_new_function (vtv_fndecl, false); + + cgraph_process_new_functions (); + + if (flag_vtable_verify == VTV_PREINIT_PRIORITY) + assemble_vtv_preinit_initializer (vtv_fndecl); + + } + pop_lang_context (); +} + +/* This funtion takes a tree containing a class type (BASE_TYPE), and + it either finds the existing vtbl_map_node for that class in our + data structure, or it creates a new node and adds it to the data + structure if there is not one for the class already. As part of + this process it also creates the global vtable map variable for the + class. */ + +struct vtbl_map_node * +vtable_find_or_create_map_decl (tree base_type) +{ + char *var_name = NULL; + struct vtbl_map_node *vtable_map_node = NULL; + + /* Verify the type has an associated vtable. */ + if (!TYPE_BINFO (base_type) || !BINFO_VTABLE (TYPE_BINFO (base_type))) + return NULL; + + /* Create map lookup symbol for base class */ + var_name = get_mangled_vtable_map_var_name (base_type); + + /* We've already created the variable; just look it. */ + vtable_map_node = vtbl_map_get_node (TYPE_MAIN_VARIANT (base_type)); + + if (!vtable_map_node || (vtable_map_node->vtbl_map_decl == NULL_TREE)) + { + /* If we haven't already created the *__vtable_map global + variable for this class, do so now, and add it to the + varpool, to make sure it gets saved and written out. */ + + tree var_decl = NULL; + tree var_type = build_pointer_type (void_type_node); + tree initial_value = integer_zero_node; + + var_decl = build_decl (UNKNOWN_LOCATION, VAR_DECL, + get_identifier (var_name), var_type); + + DECL_EXTERNAL (var_decl) = 0; + TREE_STATIC (var_decl) = 1; + DECL_VISIBILITY (var_decl) = VISIBILITY_HIDDEN; + SET_DECL_ASSEMBLER_NAME (var_decl, get_identifier (var_name)); + DECL_ARTIFICIAL (var_decl) = 1; + /* We cannot mark this variable as read-only because we want to be + able to write to it at runtime. */ + TREE_READONLY (var_decl) = 0; + DECL_IGNORED_P (var_decl) = 1; + DECL_PRESERVE_P (var_decl) = 1; + + /* Put these mmap variables in thr .vtable_map_vars section, so + we can find and protect them. */ + + DECL_SECTION_NAME (var_decl) = build_string (strlen (".vtable_map_vars"), + ".vtable_map_vars"); + DECL_HAS_IMPLICIT_SECTION_NAME_P (var_decl) = true; + DECL_INITIAL (var_decl) = initial_value; + + comdat_linkage (var_decl); + + varpool_finalize_decl (var_decl); + if (!vtable_map_node) + vtable_map_node = + find_or_create_vtbl_map_node (TYPE_MAIN_VARIANT (base_type)); + if (vtable_map_node->vtbl_map_decl == NULL_TREE) + vtable_map_node->vtbl_map_decl = var_decl; + } + + gcc_assert (vtable_map_node); + return vtable_map_node; +} + +/* This function is used to build up our class hierarchy data for a + particular class. TYPE is the record_type tree node for the + class. */ + +static void +vtv_insert_single_class_info (tree type) +{ + if (flag_vtable_verify) + { + tree binfo = TYPE_BINFO (type); + tree base_binfo; + struct vtbl_map_node *own_map; + int i; + + /* First make sure to create the map for this record type. */ + own_map = vtable_find_or_create_map_decl (type); + if (own_map == NULL) + return; + + /* Go through the list of all base classes for the current + (derived) type, make sure the *__vtable_map global variable + for the base class exists, and add the base class/derived + class pair to the class hierarchy information we are + accumulating (for vtable pointer verification). */ + for (i = 0; BINFO_BASE_ITERATE (binfo, i, base_binfo); i++) + { + tree tree_val = BINFO_TYPE (base_binfo); + struct vtbl_map_node *vtable_map_node = NULL; + + vtable_map_node = vtable_find_or_create_map_decl (tree_val); + + if (vtable_map_node != NULL) + update_class_hierarchy_information (tree_val, type); + } + } +} + +/* This function adds classes we are interested in to a list of + classes. RECORD is the record_type node for the class we are + adding to the list. */ + +void +vtv_save_class_info (tree record) +{ + if (!flag_vtable_verify || TREE_CODE (record) == UNION_TYPE) + return; + + if (!vlt_saved_class_info) + vec_alloc (vlt_saved_class_info, 10); + + gcc_assert (TREE_CODE (record) == RECORD_TYPE); + + vec_safe_push (vlt_saved_class_info, record); +} + + +/* This function goes through the list of classes we saved and calls + vtv_insert_single_class_info on each one, to build up our class + hierarchy data structure. */ + +void +vtv_recover_class_info (void) +{ + tree current_class; + unsigned i; + + if (vlt_saved_class_info) + { + for (i = 0; i < vlt_saved_class_info->length(); ++i) + { + current_class = (*vlt_saved_class_info)[i]; + gcc_assert (TREE_CODE (current_class) == RECORD_TYPE); + vtv_insert_single_class_info (current_class); + } + } +} + +#include "gt-cp-vtable-class-hierarchy.h" |