1 | /* Copyright (C) 2012-2024 Free Software Foundation, Inc. |
2 | |
3 | This file is part of GCC. |
4 | |
5 | GCC is free software; you can redistribute it and/or modify it |
6 | under the terms of the GNU General Public License as published by |
7 | the Free Software Foundation; either version 3, or (at your option) |
8 | any later version. |
9 | |
10 | GCC is distributed in the hope that it will be useful, but |
11 | WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU General Public License |
16 | along with GCC; see the file COPYING3. If not see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | /* Virtual Table Pointer Security Pass - Detect corruption of vtable pointers |
20 | before using them for virtual method dispatches. */ |
21 | |
22 | /* This file is part of the vtable security feature implementation. |
23 | The vtable security feature is designed to detect when a virtual |
24 | call is about to be made through an invalid vtable pointer |
25 | (possibly due to data corruption or malicious attacks). The |
26 | compiler finds every virtual call, and inserts a verification call |
27 | before the virtual call. The verification call takes the actual |
28 | vtable pointer value in the object through which the virtual call |
29 | is being made, and compares the vtable pointer against a set of all |
30 | valid vtable pointers that the object could contain (this set is |
31 | based on the declared type of the object). If the pointer is in |
32 | the valid set, execution is allowed to continue; otherwise the |
33 | program is halted. |
34 | |
35 | There are several pieces needed in order to make this work: 1. For |
36 | every virtual class in the program (i.e. a class that contains |
37 | virtual methods), we need to build the set of all possible valid |
38 | vtables that an object of that class could point to. This includes |
39 | vtables for any class(es) that inherit from the class under |
40 | consideration. 2. For every such data set we build up, we need a |
41 | way to find and reference the data set. This is complicated by the |
42 | fact that the real vtable addresses are not known until runtime, |
43 | when the program is loaded into memory, but we need to reference the |
44 | sets at compile time when we are inserting verification calls into |
45 | the program. 3. We need to find every virtual call in the program, |
46 | and insert the verification call (with the appropriate arguments) |
47 | before the virtual call. 4. We need some runtime library pieces: |
48 | the code to build up the data sets at runtime; the code to actually |
49 | perform the verification using the data sets; and some code to set |
50 | protections on the data sets, so they themselves do not become |
51 | hacker targets. |
52 | |
53 | To find and reference the set of valid vtable pointers for any given |
54 | virtual class, we create a special global varible for each virtual |
55 | class. We refer to this as the "vtable map variable" for that |
56 | class. The vtable map variable has the type "void *", and is |
57 | initialized by the compiler to NULL. At runtime when the set of |
58 | valid vtable pointers for a virtual class, e.g. class Foo, is built, |
59 | the vtable map variable for class Foo is made to point to the set. |
60 | During compile time, when the compiler is inserting verification |
61 | calls into the program, it passes the vtable map variable for the |
62 | appropriate class to the verification call, so that at runtime the |
63 | verification call can find the appropriate data set. |
64 | |
65 | The actual set of valid vtable pointers for a virtual class, |
66 | e.g. class Foo, cannot be built until runtime, when the vtables get |
67 | loaded into memory and their addresses are known. But the knowledge |
68 | about which vtables belong in which class' hierarchy is only known |
69 | at compile time. Therefore at compile time we collect class |
70 | hierarchy and vtable information about every virtual class, and we |
71 | generate calls to build up the data sets at runtime. To build the |
72 | data sets, we call one of the functions we add to the runtime |
73 | library, __VLTRegisterPair. __VLTRegisterPair takes two arguments, |
74 | a vtable map variable and the address of a vtable. If the vtable |
75 | map variable is currently NULL, it creates a new data set (hash |
76 | table), makes the vtable map variable point to the new data set, and |
77 | inserts the vtable address into the data set. If the vtable map |
78 | variable is not NULL, it just inserts the vtable address into the |
79 | data set. In order to make sure that our data sets are built before |
80 | any verification calls happen, we create a special constructor |
81 | initialization function for each compilation unit, give it a very |
82 | high initialization priority, and insert all of our calls to |
83 | __VLTRegisterPair into our special constructor initialization |
84 | function. |
85 | |
86 | The vtable verification feature is controlled by the flag |
87 | '-fvtable-verify='. There are three flavors of this: |
88 | '-fvtable-verify=std', '-fvtable-verify=preinit', and |
89 | '-fvtable-verify=none'. If the option '-fvtable-verfy=preinit' is |
90 | used, then our constructor initialization function gets put into the |
91 | preinit array. This is necessary if there are data sets that need |
92 | to be built very early in execution. If the constructor |
93 | initialization function gets put into the preinit array, the we also |
94 | add calls to __VLTChangePermission at the beginning and end of the |
95 | function. The call at the beginning sets the permissions on the |
96 | data sets and vtable map variables to read/write, and the one at the |
97 | end makes them read-only. If the '-fvtable-verify=std' option is |
98 | used, the constructor initialization functions are executed at their |
99 | normal time, and the __VLTChangePermission calls are handled |
100 | differently (see the comments in libstdc++-v3/libsupc++/vtv_rts.cc). |
101 | The option '-fvtable-verify=none' turns off vtable verification. |
102 | |
103 | This file contains code to find and record the class hierarchies for |
104 | the virtual classes in a program, and all the vtables associated |
105 | with each such class; to generate the vtable map variables; and to |
106 | generate the constructor initialization function (with the calls to |
107 | __VLTRegisterPair, and __VLTChangePermission). The main data |
108 | structures used for collecting the class hierarchy data and |
109 | building/maintaining the vtable map variable data are defined in |
110 | gcc/vtable-verify.h, because they are used both here and in |
111 | gcc/vtable-verify.cc. */ |
112 | |
113 | #include "config.h" |
114 | #include "system.h" |
115 | #include "coretypes.h" |
116 | #include "vtable-verify.h" |
117 | #include "cp-tree.h" |
118 | #include "stringpool.h" |
119 | #include "cgraph.h" |
120 | #include "output.h" |
121 | #include "tree-iterator.h" |
122 | #include "gimplify.h" |
123 | #include "stor-layout.h" |
124 | |
125 | static int num_calls_to_regset = 0; |
126 | static int num_calls_to_regpair = 0; |
127 | static int current_set_size; |
128 | |
129 | /* Mark these specially since they need to be stored in precompiled |
130 | header IR. */ |
131 | static GTY (()) vec<tree, va_gc> *vlt_saved_class_info; |
132 | static GTY (()) tree vlt_register_pairs_fndecl = NULL_TREE; |
133 | static GTY (()) tree vlt_register_set_fndecl = NULL_TREE; |
134 | |
135 | struct work_node { |
136 | struct vtv_graph_node *node; |
137 | struct work_node *next; |
138 | }; |
139 | |
140 | struct vtbl_map_node *vtable_find_or_create_map_decl (tree); |
141 | |
142 | /* As part of vtable verification the compiler generates and inserts |
143 | calls to __VLTVerifyVtablePointer, which is in libstdc++. This |
144 | function builds and initializes the function decl that is used |
145 | in generating those function calls. |
146 | |
147 | In addition to __VLTVerifyVtablePointer there is also |
148 | __VLTVerifyVtablePointerDebug which can be used in place of |
149 | __VLTVerifyVtablePointer, and which takes extra parameters and |
150 | outputs extra information, to help debug problems. The debug |
151 | version of this function is generated and used if flag_vtv_debug is |
152 | true. |
153 | |
154 | The signatures for these functions are: |
155 | |
156 | void * __VLTVerifyVtablePointer (void **, void*); |
157 | void * __VLTVerifyVtablePointerDebug (void**, void *, char *, char *); |
158 | */ |
159 | |
160 | void |
161 | vtv_build_vtable_verify_fndecl (void) |
162 | { |
163 | tree func_type = NULL_TREE; |
164 | |
165 | if (verify_vtbl_ptr_fndecl != NULL_TREE |
166 | && TREE_CODE (verify_vtbl_ptr_fndecl) != ERROR_MARK) |
167 | return; |
168 | |
169 | if (flag_vtv_debug) |
170 | { |
171 | func_type = build_function_type_list (const_ptr_type_node, |
172 | build_pointer_type (ptr_type_node), |
173 | const_ptr_type_node, |
174 | const_string_type_node, |
175 | const_string_type_node, |
176 | NULL_TREE); |
177 | verify_vtbl_ptr_fndecl = |
178 | build_lang_decl (FUNCTION_DECL, |
179 | get_identifier ("__VLTVerifyVtablePointerDebug" ), |
180 | func_type); |
181 | } |
182 | else |
183 | { |
184 | func_type = build_function_type_list (const_ptr_type_node, |
185 | build_pointer_type (ptr_type_node), |
186 | const_ptr_type_node, |
187 | NULL_TREE); |
188 | verify_vtbl_ptr_fndecl = |
189 | build_lang_decl (FUNCTION_DECL, |
190 | get_identifier ("__VLTVerifyVtablePointer" ), |
191 | func_type); |
192 | } |
193 | |
194 | TREE_NOTHROW (verify_vtbl_ptr_fndecl) = 1; |
195 | DECL_ATTRIBUTES (verify_vtbl_ptr_fndecl) |
196 | = tree_cons (get_identifier ("leaf" ), NULL, |
197 | DECL_ATTRIBUTES (verify_vtbl_ptr_fndecl)); |
198 | DECL_PURE_P (verify_vtbl_ptr_fndecl) = 1; |
199 | TREE_PUBLIC (verify_vtbl_ptr_fndecl) = 1; |
200 | DECL_PRESERVE_P (verify_vtbl_ptr_fndecl) = 1; |
201 | } |
202 | |
203 | /* As part of vtable verification the compiler generates and inserts |
204 | calls to __VLTRegisterSet and __VLTRegisterPair, which are in |
205 | libsupc++. This function builds and initializes the function decls |
206 | that are used in generating those function calls. |
207 | |
208 | The signatures for these functions are: |
209 | |
210 | void __VLTRegisterSetDebug (void **, const void *, std::size_t, |
211 | size_t, void **); |
212 | |
213 | void __VLTRegisterSet (void **, const void *, std::size_t, |
214 | size_t, void **); |
215 | |
216 | void __VLTRegisterPairDebug (void **, const void *, size_t, |
217 | const void *, const char *, const char *); |
218 | |
219 | void __VLTRegisterPair (void **, const void *, size_t, const void *); |
220 | */ |
221 | |
222 | static void |
223 | init_functions (void) |
224 | { |
225 | tree register_set_type; |
226 | tree register_pairs_type; |
227 | |
228 | if (vlt_register_set_fndecl != NULL_TREE) |
229 | return; |
230 | |
231 | gcc_assert (vlt_register_pairs_fndecl == NULL_TREE); |
232 | gcc_assert (vlt_register_set_fndecl == NULL_TREE); |
233 | |
234 | /* Build function decl for __VLTRegisterSet*. */ |
235 | |
236 | register_set_type = build_function_type_list |
237 | (void_type_node, |
238 | build_pointer_type (ptr_type_node), |
239 | const_ptr_type_node, |
240 | size_type_node, |
241 | size_type_node, |
242 | build_pointer_type (ptr_type_node), |
243 | NULL_TREE); |
244 | |
245 | if (flag_vtv_debug) |
246 | vlt_register_set_fndecl = build_lang_decl |
247 | (FUNCTION_DECL, |
248 | get_identifier ("__VLTRegisterSetDebug" ), |
249 | register_set_type); |
250 | else |
251 | vlt_register_set_fndecl = build_lang_decl |
252 | (FUNCTION_DECL, |
253 | get_identifier ("__VLTRegisterSet" ), |
254 | register_set_type); |
255 | |
256 | |
257 | TREE_NOTHROW (vlt_register_set_fndecl) = 1; |
258 | DECL_ATTRIBUTES (vlt_register_set_fndecl) = |
259 | tree_cons (get_identifier ("leaf" ), NULL, |
260 | DECL_ATTRIBUTES (vlt_register_set_fndecl)); |
261 | DECL_EXTERNAL(vlt_register_set_fndecl) = 1; |
262 | TREE_PUBLIC (vlt_register_set_fndecl) = 1; |
263 | DECL_PRESERVE_P (vlt_register_set_fndecl) = 1; |
264 | SET_DECL_LANGUAGE (vlt_register_set_fndecl, lang_cplusplus); |
265 | |
266 | /* Build function decl for __VLTRegisterPair*. */ |
267 | |
268 | if (flag_vtv_debug) |
269 | { |
270 | register_pairs_type = build_function_type_list (void_type_node, |
271 | build_pointer_type |
272 | (ptr_type_node), |
273 | const_ptr_type_node, |
274 | size_type_node, |
275 | const_ptr_type_node, |
276 | const_string_type_node, |
277 | const_string_type_node, |
278 | NULL_TREE); |
279 | |
280 | vlt_register_pairs_fndecl = build_lang_decl |
281 | (FUNCTION_DECL, |
282 | get_identifier ("__VLTRegisterPairDebug" ), |
283 | register_pairs_type); |
284 | } |
285 | else |
286 | { |
287 | register_pairs_type = build_function_type_list (void_type_node, |
288 | build_pointer_type |
289 | (ptr_type_node), |
290 | const_ptr_type_node, |
291 | size_type_node, |
292 | const_ptr_type_node, |
293 | NULL_TREE); |
294 | |
295 | vlt_register_pairs_fndecl = build_lang_decl |
296 | (FUNCTION_DECL, |
297 | get_identifier ("__VLTRegisterPair" ), |
298 | register_pairs_type); |
299 | } |
300 | |
301 | TREE_NOTHROW (vlt_register_pairs_fndecl) = 1; |
302 | DECL_ATTRIBUTES (vlt_register_pairs_fndecl) = |
303 | tree_cons (get_identifier ("leaf" ), NULL, |
304 | DECL_ATTRIBUTES (vlt_register_pairs_fndecl)); |
305 | DECL_EXTERNAL(vlt_register_pairs_fndecl) = 1; |
306 | TREE_PUBLIC (vlt_register_pairs_fndecl) = 1; |
307 | DECL_PRESERVE_P (vlt_register_pairs_fndecl) = 1; |
308 | SET_DECL_LANGUAGE (vlt_register_pairs_fndecl, lang_cplusplus); |
309 | |
310 | } |
311 | |
312 | /* This is a helper function for |
313 | vtv_compute_class_hierarchy_transitive_closure. It adds a |
314 | vtv_graph_node to the WORKLIST, which is a linked list of |
315 | seen-but-not-yet-processed nodes. INSERTED is a bitmap, one bit |
316 | per node, to help make sure that we don't insert a node into the |
317 | worklist more than once. Each node represents a class somewhere in |
318 | our class hierarchy information. Every node in the graph gets added |
319 | to the worklist exactly once and removed from the worklist exactly |
320 | once (when all of its children have been processed). */ |
321 | |
322 | static void |
323 | add_to_worklist (struct work_node **worklist, struct vtv_graph_node *node, |
324 | sbitmap inserted) |
325 | { |
326 | struct work_node *new_work_node; |
327 | |
328 | if (bitmap_bit_p (map: inserted, bitno: node->class_uid)) |
329 | return; |
330 | |
331 | new_work_node = XNEW (struct work_node); |
332 | new_work_node->next = *worklist; |
333 | new_work_node->node = node; |
334 | *worklist = new_work_node; |
335 | |
336 | bitmap_set_bit (map: inserted, bitno: node->class_uid); |
337 | } |
338 | |
339 | /* This is a helper function for |
340 | vtv_compute_class_hierarchy_transitive_closure. It goes through |
341 | the WORKLIST of class hierarchy nodes looking for a "leaf" node, |
342 | i.e. a node whose children in the hierarchy have all been |
343 | processed. When it finds the next leaf node, it removes it from |
344 | the linked list (WORKLIST) and returns the node. */ |
345 | |
346 | static struct vtv_graph_node * |
347 | find_and_remove_next_leaf_node (struct work_node **worklist) |
348 | { |
349 | struct work_node *prev, *cur; |
350 | struct vtv_graph_node *ret_val = NULL; |
351 | |
352 | for (prev = NULL, cur = *worklist; cur; prev = cur, cur = cur->next) |
353 | { |
354 | if ((cur->node->children).length() == cur->node->num_processed_children) |
355 | { |
356 | if (prev == NULL) |
357 | (*worklist) = cur->next; |
358 | else |
359 | prev->next = cur->next; |
360 | |
361 | cur->next = NULL; |
362 | ret_val = cur->node; |
363 | free (ptr: cur); |
364 | return ret_val; |
365 | } |
366 | } |
367 | |
368 | return NULL; |
369 | } |
370 | |
371 | /* In our class hierarchy graph, each class node contains a bitmap, |
372 | with one bit for each class in the hierarchy. The bits are set for |
373 | classes that are descendants in the graph of the current node. |
374 | Initially the descendants bitmap is only set for immediate |
375 | descendants. This function traverses the class hierarchy graph, |
376 | bottom up, filling in the transitive closures for the descendants |
377 | as we rise up the graph. */ |
378 | |
379 | void |
380 | vtv_compute_class_hierarchy_transitive_closure (void) |
381 | { |
382 | struct work_node *worklist = NULL; |
383 | sbitmap inserted = sbitmap_alloc (num_vtable_map_nodes); |
384 | unsigned i; |
385 | unsigned j; |
386 | |
387 | /* Note: Every node in the graph gets added to the worklist exactly |
388 | once and removed from the worklist exactly once (when all of its |
389 | children have been processed). Each node's children edges are |
390 | followed exactly once, and each node's parent edges are followed |
391 | exactly once. So this algorithm is roughly O(V + 2E), i.e. |
392 | O(E + V). */ |
393 | |
394 | /* Set-up: */ |
395 | /* Find all the "leaf" nodes in the graph, and add them to the worklist. */ |
396 | bitmap_clear (inserted); |
397 | for (j = 0; j < num_vtable_map_nodes; ++j) |
398 | { |
399 | struct vtbl_map_node *cur = vtbl_map_nodes_vec[j]; |
400 | if (cur->class_info |
401 | && ((cur->class_info->children).length() == 0) |
402 | && ! (bitmap_bit_p (map: inserted, bitno: cur->class_info->class_uid))) |
403 | add_to_worklist (worklist: &worklist, node: cur->class_info, inserted); |
404 | } |
405 | |
406 | /* Main work: pull next leaf node off work list, process it, add its |
407 | parents to the worklist, where a 'leaf' node is one that has no |
408 | children, or all of its children have been processed. */ |
409 | while (worklist) |
410 | { |
411 | struct vtv_graph_node *temp_node = |
412 | find_and_remove_next_leaf_node (worklist: &worklist); |
413 | |
414 | gcc_assert (temp_node != NULL); |
415 | temp_node->descendants = sbitmap_alloc (num_vtable_map_nodes); |
416 | bitmap_clear (temp_node->descendants); |
417 | bitmap_set_bit (map: temp_node->descendants, bitno: temp_node->class_uid); |
418 | for (i = 0; i < (temp_node->children).length(); ++i) |
419 | bitmap_ior (temp_node->descendants, temp_node->descendants, |
420 | temp_node->children[i]->descendants); |
421 | for (i = 0; i < (temp_node->parents).length(); ++i) |
422 | { |
423 | temp_node->parents[i]->num_processed_children = |
424 | temp_node->parents[i]->num_processed_children + 1; |
425 | if (!bitmap_bit_p (map: inserted, bitno: temp_node->parents[i]->class_uid)) |
426 | add_to_worklist (worklist: &worklist, node: temp_node->parents[i], inserted); |
427 | } |
428 | } |
429 | } |
430 | |
431 | /* Keep track of which pairs we have already created __VLTRegisterPair |
432 | calls for, to prevent creating duplicate calls within the same |
433 | compilation unit. VTABLE_DECL is the var decl for the vtable of |
434 | the (descendant) class that we are adding to our class hierarchy |
435 | data. VPTR_ADDRESS is an expression for calculating the correct |
436 | offset into the vtable (VTABLE_DECL). It is the actual vtable |
437 | pointer address that will be stored in our list of valid vtable |
438 | pointers for BASE_CLASS. BASE_CLASS is the record_type node for |
439 | the base class to whose hiearchy we want to add |
440 | VPTR_ADDRESS. (VTABLE_DECL should be the vtable for BASE_CLASS or |
441 | one of BASE_CLASS' descendents. */ |
442 | |
443 | static bool |
444 | check_and_record_registered_pairs (tree vtable_decl, tree vptr_address, |
445 | tree base_class) |
446 | { |
447 | unsigned offset; |
448 | struct vtbl_map_node *base_vtable_map_node; |
449 | bool inserted_something = false; |
450 | |
451 | |
452 | if (TREE_CODE (vptr_address) == ADDR_EXPR |
453 | && TREE_CODE (TREE_OPERAND (vptr_address, 0)) == MEM_REF) |
454 | vptr_address = TREE_OPERAND (vptr_address, 0); |
455 | |
456 | if (TREE_OPERAND_LENGTH (vptr_address) > 1) |
457 | offset = TREE_INT_CST_LOW (TREE_OPERAND (vptr_address, 1)); |
458 | else |
459 | offset = 0; |
460 | |
461 | base_vtable_map_node = vtbl_map_get_node (TYPE_MAIN_VARIANT (base_class)); |
462 | |
463 | inserted_something = vtbl_map_node_registration_insert |
464 | (base_vtable_map_node, |
465 | vtable_decl, |
466 | offset); |
467 | return !inserted_something; |
468 | } |
469 | |
470 | /* A class may contain secondary vtables in it, for various reasons. |
471 | This function goes through the decl chain of a class record looking |
472 | for any fields that point to secondary vtables, and adding calls to |
473 | __VLTRegisterPair for the secondary vtable pointers. |
474 | |
475 | BASE_CLASS_DECL_ARG is an expression for the address of the vtable |
476 | map variable for the BASE_CLASS (whose hierarchy we are currently |
477 | updating). BASE_CLASS is the record_type node for the base class. |
478 | RECORD_TYPE is the record_type node for the descendant class that |
479 | we are possibly adding to BASE_CLASS's hierarchy. BODY is the |
480 | function body for the constructor init function to which we are |
481 | adding our calls to __VLTRegisterPair. */ |
482 | |
483 | static void |
484 | register_construction_vtables (tree base_class, tree record_type, |
485 | vec<tree> *vtable_ptr_array) |
486 | { |
487 | tree vtbl_var_decl; |
488 | |
489 | if (TREE_CODE (record_type) != RECORD_TYPE) |
490 | return; |
491 | |
492 | vtbl_var_decl = CLASSTYPE_VTABLES (record_type); |
493 | |
494 | if (CLASSTYPE_VBASECLASSES (record_type)) |
495 | { |
496 | tree vtt_decl; |
497 | bool already_registered = false; |
498 | tree val_vtbl_decl = NULL_TREE; |
499 | |
500 | vtt_decl = DECL_CHAIN (vtbl_var_decl); |
501 | |
502 | /* Check to see if we have found a VTT. Add its data if appropriate. */ |
503 | if (vtt_decl) |
504 | { |
505 | tree values = DECL_INITIAL (vtt_decl); |
506 | if (TREE_ASM_WRITTEN (vtt_decl) |
507 | && values != NULL_TREE |
508 | && TREE_CODE (values) == CONSTRUCTOR |
509 | && TREE_CODE (TREE_TYPE (values)) == ARRAY_TYPE) |
510 | { |
511 | unsigned HOST_WIDE_INT cnt; |
512 | constructor_elt *ce; |
513 | |
514 | /* Loop through the initialization values for this |
515 | vtable to get all the correct vtable pointer |
516 | addresses that we need to add to our set of valid |
517 | vtable pointers for the current base class. This may |
518 | result in adding more than just the element assigned |
519 | to the primary vptr of the class, so we may end up |
520 | with more vtable pointers than are strictly |
521 | necessary. */ |
522 | |
523 | for (cnt = 0; |
524 | vec_safe_iterate (CONSTRUCTOR_ELTS (values), |
525 | ix: cnt, ptr: &ce); |
526 | cnt++) |
527 | { |
528 | tree value = ce->value; |
529 | |
530 | /* Search for the ADDR_EXPR operand within the value. */ |
531 | |
532 | while (value |
533 | && TREE_OPERAND (value, 0) |
534 | && TREE_CODE (TREE_OPERAND (value, 0)) == ADDR_EXPR) |
535 | value = TREE_OPERAND (value, 0); |
536 | |
537 | /* The VAR_DECL for the vtable should be the first |
538 | argument of the ADDR_EXPR, which is the first |
539 | argument of value.*/ |
540 | |
541 | if (TREE_OPERAND (value, 0)) |
542 | val_vtbl_decl = TREE_OPERAND (value, 0); |
543 | |
544 | while (!VAR_P (val_vtbl_decl) |
545 | && TREE_OPERAND (val_vtbl_decl, 0)) |
546 | val_vtbl_decl = TREE_OPERAND (val_vtbl_decl, 0); |
547 | |
548 | gcc_assert (VAR_P (val_vtbl_decl)); |
549 | |
550 | /* Check to see if we already have this vtable pointer in |
551 | our valid set for this base class. */ |
552 | |
553 | already_registered = check_and_record_registered_pairs |
554 | (vtable_decl: val_vtbl_decl, |
555 | vptr_address: value, |
556 | base_class); |
557 | |
558 | if (already_registered) |
559 | continue; |
560 | |
561 | /* Add this vtable pointer to our set of valid |
562 | pointers for the base class. */ |
563 | |
564 | vtable_ptr_array->safe_push (obj: value); |
565 | current_set_size++; |
566 | } |
567 | } |
568 | } |
569 | } |
570 | } |
571 | |
572 | /* This function iterates through all the vtables it can find from the |
573 | BINFO of a class, to make sure we have found ALL of the vtables |
574 | that an object of that class could point to. Generate calls to |
575 | __VLTRegisterPair for those vtable pointers that we find. |
576 | |
577 | BINFO is the tree_binfo node for the BASE_CLASS. BODY is the |
578 | function body for the constructor init function to which we are |
579 | adding calls to __VLTRegisterPair. ARG1 is an expression for the |
580 | address of the vtable map variable (for the BASE_CLASS), that will |
581 | point to the updated data set. BASE_CLASS is the record_type node |
582 | for the base class whose set of valid vtable pointers we are |
583 | updating. STR1 and STR2 are all debugging information, to be passed |
584 | as parameters to __VLTRegisterPairDebug. STR1 represents the name |
585 | of the vtable map variable to be updated by the call. Similarly, |
586 | STR2 represents the name of the class whose vtable pointer is being |
587 | added to the hierarchy. */ |
588 | |
589 | static void |
590 | register_other_binfo_vtables (tree binfo, tree base_class, |
591 | vec<tree> *vtable_ptr_array) |
592 | { |
593 | unsigned ix; |
594 | tree base_binfo; |
595 | tree vtable_decl; |
596 | bool already_registered; |
597 | |
598 | if (binfo == NULL_TREE) |
599 | return; |
600 | |
601 | for (ix = 0; BINFO_BASE_ITERATE (binfo, ix, base_binfo); ix++) |
602 | { |
603 | if ((!BINFO_PRIMARY_P (base_binfo) |
604 | || BINFO_VIRTUAL_P (base_binfo)) |
605 | && (vtable_decl = get_vtbl_decl_for_binfo (base_binfo))) |
606 | { |
607 | tree vtable_address = build_vtbl_address (base_binfo); |
608 | |
609 | already_registered = check_and_record_registered_pairs |
610 | (vtable_decl, |
611 | vptr_address: vtable_address, |
612 | base_class); |
613 | if (!already_registered) |
614 | { |
615 | vtable_ptr_array->safe_push (obj: vtable_address); |
616 | current_set_size++; |
617 | } |
618 | } |
619 | |
620 | register_other_binfo_vtables (binfo: base_binfo, base_class, vtable_ptr_array); |
621 | } |
622 | } |
623 | |
624 | /* The set of valid vtable pointers for any given class are stored in |
625 | a hash table. For reasons of efficiency, that hash table size is |
626 | always a power of two. In order to try to prevent re-sizing the |
627 | hash tables very often, we pass __VLTRegisterPair an initial guess |
628 | as to the number of entries the hashtable will eventually need |
629 | (rounded up to the nearest power of two). This function takes the |
630 | class information we have collected for a particular class, |
631 | CLASS_NODE, and calculates the hash table size guess. */ |
632 | |
633 | static int |
634 | guess_num_vtable_pointers (struct vtv_graph_node *class_node) |
635 | { |
636 | tree vtbl; |
637 | int total_num_vtbls = 0; |
638 | int num_vtbls_power_of_two = 1; |
639 | unsigned i; |
640 | |
641 | for (i = 0; i < num_vtable_map_nodes; ++i) |
642 | if (bitmap_bit_p (map: class_node->descendants, bitno: i)) |
643 | { |
644 | tree class_type = vtbl_map_nodes_vec[i]->class_info->class_type; |
645 | for (vtbl = CLASSTYPE_VTABLES (class_type); vtbl; |
646 | vtbl = DECL_CHAIN (vtbl)) |
647 | { |
648 | total_num_vtbls++; |
649 | if (total_num_vtbls > num_vtbls_power_of_two) |
650 | num_vtbls_power_of_two <<= 1; |
651 | } |
652 | } |
653 | return num_vtbls_power_of_two; |
654 | } |
655 | |
656 | /* A simple hash function on strings */ |
657 | /* Be careful about changing this routine. The values generated will |
658 | be stored in the calls to InitSet. So, changing this routine may |
659 | cause a binary incompatibility. */ |
660 | |
661 | static uint32_t |
662 | vtv_string_hash (const char *in) |
663 | { |
664 | const char *s = in; |
665 | uint32_t h = 0; |
666 | |
667 | gcc_assert (in != NULL); |
668 | for ( ; *s; ++s) |
669 | h = 5 * h + *s; |
670 | return h; |
671 | } |
672 | |
673 | static char * |
674 | get_log_file_name (const char *fname) |
675 | { |
676 | const char *tmp_dir = concat (dump_dir_name, NULL); |
677 | char *full_name; |
678 | int dir_len; |
679 | int fname_len; |
680 | |
681 | dir_len = strlen (s: tmp_dir); |
682 | fname_len = strlen (s: fname); |
683 | |
684 | full_name = XNEWVEC (char, dir_len + fname_len + 1); |
685 | strcpy (dest: full_name, src: tmp_dir); |
686 | strcpy (dest: full_name + dir_len, src: fname); |
687 | |
688 | return full_name; |
689 | } |
690 | |
691 | static void |
692 | write_out_current_set_data (tree base_class, int set_size) |
693 | { |
694 | static int class_data_log_fd = -1; |
695 | char buffer[1024]; |
696 | int bytes_written __attribute__ ((unused)); |
697 | char *file_name = get_log_file_name (fname: "vtv_class_set_sizes.log" ); |
698 | |
699 | if (class_data_log_fd == -1) |
700 | class_data_log_fd = open (file: file_name, |
701 | O_WRONLY | O_APPEND | O_CREAT, S_IRWXU); |
702 | |
703 | if (class_data_log_fd == -1) |
704 | { |
705 | warning_at (UNKNOWN_LOCATION, 0, |
706 | "unable to open log file %<vtv_class_set_sizes.log%>: %m" ); |
707 | return; |
708 | } |
709 | |
710 | snprintf (s: buffer, maxlen: sizeof (buffer), format: "%s %d\n" , |
711 | IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (TYPE_NAME (base_class))), |
712 | set_size); |
713 | bytes_written = write (fd: class_data_log_fd, buf: buffer, n: strlen (s: buffer)); |
714 | } |
715 | |
716 | static tree |
717 | build_key_buffer_arg (tree base_ptr_var_decl) |
718 | { |
719 | const int key_type_fixed_size = 8; |
720 | uint32_t len1 = IDENTIFIER_LENGTH (DECL_NAME (base_ptr_var_decl)); |
721 | uint32_t hash_value = vtv_string_hash (IDENTIFIER_POINTER |
722 | (DECL_NAME (base_ptr_var_decl))); |
723 | void *key_buffer = xmalloc (len1 + key_type_fixed_size); |
724 | uint32_t *value_ptr = (uint32_t *) key_buffer; |
725 | tree ret_value; |
726 | |
727 | /* Set the len and hash for the string. */ |
728 | *value_ptr = len1; |
729 | value_ptr++; |
730 | *value_ptr = hash_value; |
731 | |
732 | /* Now copy the string representation of the vtbl map name... */ |
733 | memcpy (dest: (char *) key_buffer + key_type_fixed_size, |
734 | IDENTIFIER_POINTER (DECL_NAME (base_ptr_var_decl)), |
735 | n: len1); |
736 | |
737 | /* ... and build a string literal from it. This will make a copy |
738 | so the key_bufffer is not needed anymore after this. */ |
739 | ret_value = build_string_literal (len1 + key_type_fixed_size, |
740 | (char *) key_buffer); |
741 | free (ptr: key_buffer); |
742 | return ret_value; |
743 | } |
744 | |
745 | static void |
746 | insert_call_to_register_set (tree class_name, |
747 | vec<tree> *vtbl_ptr_array, tree body, tree arg1, |
748 | tree arg2, tree size_hint_arg) |
749 | { |
750 | tree call_expr; |
751 | int num_args = vtbl_ptr_array->length(); |
752 | char *array_arg_name = ACONCAT (("__vptr_array_" , |
753 | IDENTIFIER_POINTER (class_name), NULL)); |
754 | tree array_arg_type = build_array_type_nelts (build_pointer_type |
755 | (build_pointer_type |
756 | (void_type_node)), |
757 | num_args); |
758 | tree array_arg = build_decl (UNKNOWN_LOCATION, VAR_DECL, |
759 | get_identifier (array_arg_name), |
760 | array_arg_type); |
761 | int k; |
762 | |
763 | vec<constructor_elt, va_gc> *array_elements; |
764 | vec_alloc (v&: array_elements, nelems: num_args); |
765 | |
766 | tree initial = NULL_TREE; |
767 | tree arg3 = NULL_TREE; |
768 | |
769 | TREE_PUBLIC (array_arg) = 0; |
770 | DECL_EXTERNAL (array_arg) = 0; |
771 | TREE_STATIC (array_arg) = 1; |
772 | DECL_ARTIFICIAL (array_arg) = 0; |
773 | TREE_READONLY (array_arg) = 1; |
774 | DECL_IGNORED_P (array_arg) = 0; |
775 | DECL_PRESERVE_P (array_arg) = 0; |
776 | DECL_VISIBILITY (array_arg) = VISIBILITY_HIDDEN; |
777 | |
778 | for (k = 0; k < num_args; ++k) |
779 | { |
780 | CONSTRUCTOR_APPEND_ELT (array_elements, NULL_TREE, (*vtbl_ptr_array)[k]); |
781 | } |
782 | |
783 | initial = build_constructor (TREE_TYPE (array_arg), array_elements); |
784 | |
785 | TREE_CONSTANT (initial) = 1; |
786 | TREE_STATIC (initial) = 1; |
787 | DECL_INITIAL (array_arg) = initial; |
788 | relayout_decl (array_arg); |
789 | varpool_node::finalize_decl (decl: array_arg); |
790 | |
791 | arg3 = build1 (ADDR_EXPR, TYPE_POINTER_TO (TREE_TYPE (array_arg)), array_arg); |
792 | |
793 | TREE_TYPE (arg3) = build_pointer_type (TREE_TYPE (array_arg)); |
794 | |
795 | call_expr = build_call_expr (vlt_register_set_fndecl, 5, arg1, |
796 | arg2, /* set_symbol_key */ |
797 | size_hint_arg, build_int_cst (size_type_node, |
798 | num_args), |
799 | arg3); |
800 | append_to_statement_list (call_expr, &body); |
801 | num_calls_to_regset++; |
802 | } |
803 | |
804 | static void |
805 | insert_call_to_register_pair (vec<tree> *vtbl_ptr_array, tree arg1, |
806 | tree arg2, tree size_hint_arg, tree str1, |
807 | tree str2, tree body) |
808 | { |
809 | tree call_expr; |
810 | int num_args = vtbl_ptr_array->length(); |
811 | tree vtable_address = NULL_TREE; |
812 | |
813 | if (num_args == 0) |
814 | vtable_address = build_int_cst (build_pointer_type (void_type_node), 0); |
815 | else |
816 | vtable_address = (*vtbl_ptr_array)[0]; |
817 | |
818 | if (flag_vtv_debug) |
819 | call_expr = build_call_expr (vlt_register_pairs_fndecl, 6, arg1, arg2, |
820 | size_hint_arg, vtable_address, str1, str2); |
821 | else |
822 | call_expr = build_call_expr (vlt_register_pairs_fndecl, 4, arg1, arg2, |
823 | size_hint_arg, vtable_address); |
824 | |
825 | append_to_statement_list (call_expr, &body); |
826 | num_calls_to_regpair++; |
827 | } |
828 | |
829 | static void |
830 | output_set_info (tree record_type, vec<tree> vtbl_ptr_array) |
831 | { |
832 | static int vtv_debug_log_fd = -1; |
833 | char buffer[1024]; |
834 | int bytes_written __attribute__ ((unused)); |
835 | int array_len = vtbl_ptr_array.length(); |
836 | const char *class_name = |
837 | IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (TYPE_NAME (record_type))); |
838 | char *file_name = get_log_file_name (fname: "vtv_set_ptr_data.log" ); |
839 | |
840 | if (vtv_debug_log_fd == -1) |
841 | vtv_debug_log_fd = open (file: file_name, |
842 | O_WRONLY | O_APPEND | O_CREAT, S_IRWXU); |
843 | if (vtv_debug_log_fd == -1) |
844 | { |
845 | warning_at (UNKNOWN_LOCATION, 0, |
846 | "unable to open log file %<vtv_set_ptr_data.log%>: %m" ); |
847 | return; |
848 | } |
849 | |
850 | for (int i = 0; i < array_len; ++i) |
851 | { |
852 | const char *vptr_name = "unknown" ; |
853 | int vptr_offset = 0; |
854 | |
855 | if (TREE_CODE (vtbl_ptr_array[i]) == POINTER_PLUS_EXPR) |
856 | { |
857 | tree arg0 = TREE_OPERAND (vtbl_ptr_array[i], 0); |
858 | tree arg1 = TREE_OPERAND (vtbl_ptr_array[i], 1); |
859 | |
860 | if (TREE_CODE (arg0) == ADDR_EXPR) |
861 | arg0 = TREE_OPERAND (arg0, 0); |
862 | |
863 | if (VAR_P (arg0)) |
864 | vptr_name = IDENTIFIER_POINTER (DECL_NAME (arg0)); |
865 | |
866 | if (TREE_CODE (arg1) == INTEGER_CST) |
867 | vptr_offset = TREE_INT_CST_LOW (arg1); |
868 | } |
869 | |
870 | snprintf (s: buffer, maxlen: sizeof (buffer), format: "%s %s %s + %d\n" , |
871 | main_input_filename, class_name, vptr_name, vptr_offset); |
872 | bytes_written = write (fd: vtv_debug_log_fd, buf: buffer, n: strlen(s: buffer)); |
873 | } |
874 | |
875 | } |
876 | |
877 | /* This function goes through our internal class hierarchy & vtable |
878 | pointer data structure and outputs calls to __VLTRegisterPair for |
879 | every class-vptr pair (for those classes whose vtable would be |
880 | output in the current compilation unit). These calls get put into |
881 | our constructor initialization function. BODY is the function |
882 | body, so far, of our constructor initialization function, to which we |
883 | add the calls. */ |
884 | |
885 | static bool |
886 | register_all_pairs (tree body) |
887 | { |
888 | bool registered_at_least_one = false; |
889 | vec<tree> *vtbl_ptr_array = NULL; |
890 | unsigned j; |
891 | |
892 | for (j = 0; j < num_vtable_map_nodes; ++j) |
893 | { |
894 | struct vtbl_map_node *current = vtbl_map_nodes_vec[j]; |
895 | unsigned i = 0; |
896 | tree base_class = current->class_info->class_type; |
897 | tree base_ptr_var_decl = current->vtbl_map_decl; |
898 | tree arg1; |
899 | tree arg2; |
900 | tree new_type; |
901 | tree str1 = NULL_TREE; |
902 | tree str2 = NULL_TREE; |
903 | size_t size_hint; |
904 | tree size_hint_arg; |
905 | |
906 | gcc_assert (current->class_info != NULL); |
907 | |
908 | |
909 | if (flag_vtv_debug) |
910 | str1 = build_string_literal (DECL_NAME (base_ptr_var_decl)); |
911 | |
912 | new_type = build_pointer_type (TREE_TYPE (base_ptr_var_decl)); |
913 | arg1 = build1 (ADDR_EXPR, new_type, base_ptr_var_decl); |
914 | |
915 | /* We need a fresh vector for each iteration. */ |
916 | if (vtbl_ptr_array) |
917 | vec_free (v&: vtbl_ptr_array); |
918 | |
919 | vec_alloc (v&: vtbl_ptr_array, nelems: 10); |
920 | |
921 | for (i = 0; i < num_vtable_map_nodes; ++i) |
922 | if (bitmap_bit_p (map: current->class_info->descendants, bitno: i)) |
923 | { |
924 | struct vtbl_map_node *vtbl_class_node = vtbl_map_nodes_vec[i]; |
925 | tree class_type = vtbl_class_node->class_info->class_type; |
926 | |
927 | if (class_type |
928 | && (TREE_CODE (class_type) == RECORD_TYPE)) |
929 | { |
930 | bool already_registered; |
931 | |
932 | tree binfo = TYPE_BINFO (class_type); |
933 | tree vtable_decl; |
934 | bool vtable_should_be_output = false; |
935 | |
936 | vtable_decl = CLASSTYPE_VTABLES (class_type); |
937 | |
938 | /* Handle main vtable for this class. */ |
939 | |
940 | if (vtable_decl) |
941 | { |
942 | vtable_should_be_output = TREE_ASM_WRITTEN (vtable_decl); |
943 | str2 = build_string_literal (DECL_NAME (vtable_decl)); |
944 | } |
945 | |
946 | if (vtable_decl && vtable_should_be_output) |
947 | { |
948 | tree vtable_address = build_vtbl_address (binfo); |
949 | |
950 | already_registered = check_and_record_registered_pairs |
951 | (vtable_decl, |
952 | vptr_address: vtable_address, |
953 | base_class); |
954 | |
955 | |
956 | if (!already_registered) |
957 | { |
958 | vtbl_ptr_array->safe_push (obj: vtable_address); |
959 | |
960 | /* Find and handle any 'extra' vtables associated |
961 | with this class, via virtual inheritance. */ |
962 | register_construction_vtables (base_class, record_type: class_type, |
963 | vtable_ptr_array: vtbl_ptr_array); |
964 | |
965 | /* Find and handle any 'extra' vtables associated |
966 | with this class, via multiple inheritance. */ |
967 | register_other_binfo_vtables (binfo, base_class, |
968 | vtable_ptr_array: vtbl_ptr_array); |
969 | } |
970 | } |
971 | } |
972 | } |
973 | current_set_size = vtbl_ptr_array->length(); |
974 | |
975 | /* Sometimes we need to initialize the set symbol even if we are |
976 | not adding any vtable pointers to the set in the current |
977 | compilation unit. In that case, we need to initialize the |
978 | set to our best guess as to what the eventual size of the set |
979 | hash table will be (to prevent having to re-size the hash |
980 | table later). */ |
981 | |
982 | size_hint = guess_num_vtable_pointers (class_node: current->class_info); |
983 | |
984 | /* If we have added vtable pointers to the set in this |
985 | compilation unit, adjust the size hint for the set's hash |
986 | table appropriately. */ |
987 | if (vtbl_ptr_array->length() > 0) |
988 | { |
989 | unsigned len = vtbl_ptr_array->length(); |
990 | while ((size_t) len > size_hint) |
991 | size_hint <<= 1; |
992 | } |
993 | size_hint_arg = build_int_cst (size_type_node, size_hint); |
994 | |
995 | /* Get the key-buffer argument. */ |
996 | arg2 = build_key_buffer_arg (base_ptr_var_decl); |
997 | |
998 | if (str2 == NULL_TREE) |
999 | str2 = build_string_literal (p: "unknown" ); |
1000 | |
1001 | if (flag_vtv_debug) |
1002 | output_set_info (record_type: current->class_info->class_type, |
1003 | vtbl_ptr_array: *vtbl_ptr_array); |
1004 | |
1005 | if (vtbl_ptr_array->length() > 1) |
1006 | { |
1007 | insert_call_to_register_set (class_name: current->class_name, |
1008 | vtbl_ptr_array, body, arg1, arg2, |
1009 | size_hint_arg); |
1010 | registered_at_least_one = true; |
1011 | } |
1012 | else |
1013 | { |
1014 | |
1015 | if (vtbl_ptr_array->length() > 0 |
1016 | || (current->is_used |
1017 | || (current->registered->size() > 0))) |
1018 | { |
1019 | insert_call_to_register_pair (vtbl_ptr_array, |
1020 | arg1, arg2, size_hint_arg, str1, |
1021 | str2, body); |
1022 | registered_at_least_one = true; |
1023 | } |
1024 | } |
1025 | |
1026 | if (flag_vtv_counts && current_set_size > 0) |
1027 | write_out_current_set_data (base_class, set_size: current_set_size); |
1028 | |
1029 | } |
1030 | |
1031 | return registered_at_least_one; |
1032 | } |
1033 | |
1034 | /* Given a tree containing a class type (CLASS_TYPE), this function |
1035 | finds and returns the class hierarchy node for that class in our |
1036 | data structure. */ |
1037 | |
1038 | static struct vtv_graph_node * |
1039 | find_graph_node (tree class_type) |
1040 | { |
1041 | struct vtbl_map_node *vtbl_node; |
1042 | |
1043 | vtbl_node = vtbl_map_get_node (TYPE_MAIN_VARIANT (class_type)); |
1044 | if (vtbl_node) |
1045 | return vtbl_node->class_info; |
1046 | |
1047 | return NULL; |
1048 | } |
1049 | |
1050 | /* Add base class/derived class pair to our internal class hierarchy |
1051 | data structure. BASE_NODE is our vtv_graph_node that corresponds |
1052 | to a base class. DERIVED_NODE is our vtv_graph_node that |
1053 | corresponds to a class that is a descendant of the base class |
1054 | (possibly the base class itself). */ |
1055 | |
1056 | static void |
1057 | add_hierarchy_pair (struct vtv_graph_node *base_node, |
1058 | struct vtv_graph_node *derived_node) |
1059 | { |
1060 | (base_node->children).safe_push (obj: derived_node); |
1061 | (derived_node->parents).safe_push (obj: base_node); |
1062 | } |
1063 | |
1064 | /* This functions adds a new base class/derived class relationship to |
1065 | our class hierarchy data structure. Both parameters are trees |
1066 | representing the class types, i.e. RECORD_TYPE trees. |
1067 | DERIVED_CLASS can be the same as BASE_CLASS. */ |
1068 | |
1069 | static void |
1070 | update_class_hierarchy_information (tree base_class, |
1071 | tree derived_class) |
1072 | { |
1073 | struct vtv_graph_node *base_node = find_graph_node (class_type: base_class); |
1074 | struct vtv_graph_node *derived_node = find_graph_node (class_type: derived_class); |
1075 | |
1076 | add_hierarchy_pair (base_node, derived_node); |
1077 | } |
1078 | |
1079 | |
1080 | static void |
1081 | write_out_vtv_count_data (void) |
1082 | { |
1083 | static int vtv_count_log_fd = -1; |
1084 | char buffer[1024]; |
1085 | int unused_vtbl_map_vars = 0; |
1086 | int bytes_written __attribute__ ((unused)); |
1087 | char *file_name = get_log_file_name (fname: "vtv_count_data.log" ); |
1088 | |
1089 | if (vtv_count_log_fd == -1) |
1090 | vtv_count_log_fd = open (file: file_name, |
1091 | O_WRONLY | O_APPEND | O_CREAT, S_IRWXU); |
1092 | if (vtv_count_log_fd == -1) |
1093 | { |
1094 | warning_at (UNKNOWN_LOCATION, 0, |
1095 | "unable to open log file %<vtv_count_data.log%>: %m" ); |
1096 | return; |
1097 | } |
1098 | |
1099 | for (unsigned i = 0; i < num_vtable_map_nodes; ++i) |
1100 | { |
1101 | struct vtbl_map_node *current = vtbl_map_nodes_vec[i]; |
1102 | if (!current->is_used |
1103 | && current->registered->size() == 0) |
1104 | unused_vtbl_map_vars++; |
1105 | } |
1106 | |
1107 | snprintf (s: buffer, maxlen: sizeof (buffer), format: "%s %d %d %d %d %d\n" , |
1108 | main_input_filename, total_num_virtual_calls, |
1109 | total_num_verified_vcalls, num_calls_to_regset, |
1110 | num_calls_to_regpair, unused_vtbl_map_vars); |
1111 | |
1112 | bytes_written = write (fd: vtv_count_log_fd, buf: buffer, n: strlen (s: buffer)); |
1113 | } |
1114 | |
1115 | /* This function calls register_all_pairs, which actually generates |
1116 | all the calls to __VLTRegisterPair (in the verification constructor |
1117 | init function). It also generates the calls to |
1118 | __VLTChangePermission, if the verification constructor init |
1119 | function is going into the preinit array. INIT_ROUTINE_BODY is |
1120 | the body of our constructior initialization function, to which we |
1121 | add our function calls.*/ |
1122 | |
1123 | bool |
1124 | vtv_register_class_hierarchy_information (tree init_routine_body) |
1125 | { |
1126 | bool registered_something = false; |
1127 | |
1128 | init_functions (); |
1129 | |
1130 | if (num_vtable_map_nodes == 0) |
1131 | return false; |
1132 | |
1133 | /* Add class hierarchy pairs to the vtable map data structure. */ |
1134 | registered_something = register_all_pairs (body: init_routine_body); |
1135 | |
1136 | if (flag_vtv_counts) |
1137 | write_out_vtv_count_data (); |
1138 | |
1139 | return registered_something; |
1140 | } |
1141 | |
1142 | |
1143 | /* Generate the special constructor function that calls |
1144 | __VLTChangePermission and __VLTRegisterPairs, and give it a very |
1145 | high initialization priority. */ |
1146 | |
1147 | void |
1148 | vtv_generate_init_routine (void) |
1149 | { |
1150 | tree init_routine_body; |
1151 | bool vtable_classes_found = false; |
1152 | |
1153 | push_lang_context (lang_name_c); |
1154 | |
1155 | /* The priority for this init function (constructor) is carefully |
1156 | chosen so that it will happen after the calls to unprotect the |
1157 | memory used for vtable verification and before the memory is |
1158 | protected again. */ |
1159 | init_routine_body = vtv_start_verification_constructor_init_function (); |
1160 | |
1161 | vtable_classes_found = |
1162 | vtv_register_class_hierarchy_information (init_routine_body); |
1163 | |
1164 | if (vtable_classes_found) |
1165 | { |
1166 | tree vtv_fndecl = |
1167 | vtv_finish_verification_constructor_init_function (init_routine_body); |
1168 | TREE_STATIC (vtv_fndecl) = 1; |
1169 | TREE_USED (vtv_fndecl) = 1; |
1170 | DECL_PRESERVE_P (vtv_fndecl) = 1; |
1171 | /* We are running too late to generate any meaningful debug information |
1172 | for this routine. */ |
1173 | DECL_IGNORED_P (vtv_fndecl) = 1; |
1174 | if (flag_vtable_verify == VTV_PREINIT_PRIORITY && !TARGET_PECOFF) |
1175 | DECL_STATIC_CONSTRUCTOR (vtv_fndecl) = 0; |
1176 | |
1177 | gimplify_function_tree (vtv_fndecl); |
1178 | cgraph_node::add_new_function (fndecl: vtv_fndecl, lowered: false); |
1179 | |
1180 | if (flag_vtable_verify == VTV_PREINIT_PRIORITY && !TARGET_PECOFF) |
1181 | { |
1182 | tree vtv_var |
1183 | = build_decl (BUILTINS_LOCATION, VAR_DECL, |
1184 | get_identifier ("__vtv_preinit" ), |
1185 | build_pointer_type (TREE_TYPE (vtv_fndecl))); |
1186 | TREE_STATIC (vtv_var) = 1; |
1187 | DECL_ARTIFICIAL (vtv_var) = 1; |
1188 | DECL_INITIAL (vtv_var) = build_fold_addr_expr (vtv_fndecl); |
1189 | set_decl_section_name (vtv_var, ".preinit_array" ); |
1190 | |
1191 | varpool_node::add (decl: vtv_var); |
1192 | } |
1193 | } |
1194 | pop_lang_context (); |
1195 | } |
1196 | |
1197 | /* This funtion takes a tree containing a class type (BASE_TYPE), and |
1198 | it either finds the existing vtbl_map_node for that class in our |
1199 | data structure, or it creates a new node and adds it to the data |
1200 | structure if there is not one for the class already. As part of |
1201 | this process it also creates the global vtable map variable for the |
1202 | class. */ |
1203 | |
1204 | struct vtbl_map_node * |
1205 | vtable_find_or_create_map_decl (tree base_type) |
1206 | { |
1207 | char *var_name = NULL; |
1208 | struct vtbl_map_node *vtable_map_node = NULL; |
1209 | |
1210 | /* Verify the type has an associated vtable. */ |
1211 | if (!TYPE_BINFO (base_type) || !BINFO_VTABLE (TYPE_BINFO (base_type))) |
1212 | return NULL; |
1213 | |
1214 | /* Create map lookup symbol for base class */ |
1215 | var_name = get_mangled_vtable_map_var_name (base_type); |
1216 | |
1217 | /* We've already created the variable; just look it. */ |
1218 | vtable_map_node = vtbl_map_get_node (TYPE_MAIN_VARIANT (base_type)); |
1219 | |
1220 | if (!vtable_map_node || (vtable_map_node->vtbl_map_decl == NULL_TREE)) |
1221 | { |
1222 | /* If we haven't already created the *__vtable_map global |
1223 | variable for this class, do so now, and add it to the |
1224 | varpool, to make sure it gets saved and written out. */ |
1225 | |
1226 | tree var_decl = NULL; |
1227 | tree var_type = build_pointer_type (void_type_node); |
1228 | tree initial_value = integer_zero_node; |
1229 | |
1230 | var_decl = build_decl (UNKNOWN_LOCATION, VAR_DECL, |
1231 | get_identifier (var_name), var_type); |
1232 | |
1233 | DECL_EXTERNAL (var_decl) = 0; |
1234 | TREE_STATIC (var_decl) = 1; |
1235 | DECL_VISIBILITY (var_decl) = VISIBILITY_HIDDEN; |
1236 | SET_DECL_ASSEMBLER_NAME (var_decl, get_identifier (var_name)); |
1237 | DECL_ARTIFICIAL (var_decl) = 1; |
1238 | /* We cannot mark this variable as read-only because we want to be |
1239 | able to write to it at runtime. */ |
1240 | TREE_READONLY (var_decl) = 0; |
1241 | DECL_IGNORED_P (var_decl) = 1; |
1242 | DECL_PRESERVE_P (var_decl) = 1; |
1243 | |
1244 | /* Put these mmap variables in thr .vtable_map_vars section, so |
1245 | we can find and protect them. */ |
1246 | |
1247 | set_decl_section_name (var_decl, ".vtable_map_vars" ); |
1248 | symtab_node::get (decl: var_decl)->implicit_section = true; |
1249 | DECL_INITIAL (var_decl) = initial_value; |
1250 | |
1251 | comdat_linkage (var_decl); |
1252 | |
1253 | varpool_node::finalize_decl (decl: var_decl); |
1254 | if (!vtable_map_node) |
1255 | vtable_map_node = |
1256 | find_or_create_vtbl_map_node (TYPE_MAIN_VARIANT (base_type)); |
1257 | if (vtable_map_node->vtbl_map_decl == NULL_TREE) |
1258 | vtable_map_node->vtbl_map_decl = var_decl; |
1259 | } |
1260 | |
1261 | gcc_assert (vtable_map_node); |
1262 | return vtable_map_node; |
1263 | } |
1264 | |
1265 | /* This function is used to build up our class hierarchy data for a |
1266 | particular class. TYPE is the record_type tree node for the |
1267 | class. */ |
1268 | |
1269 | static void |
1270 | vtv_insert_single_class_info (tree type) |
1271 | { |
1272 | if (flag_vtable_verify) |
1273 | { |
1274 | tree binfo = TYPE_BINFO (type); |
1275 | tree base_binfo; |
1276 | struct vtbl_map_node *own_map; |
1277 | int i; |
1278 | |
1279 | /* First make sure to create the map for this record type. */ |
1280 | own_map = vtable_find_or_create_map_decl (base_type: type); |
1281 | if (own_map == NULL) |
1282 | return; |
1283 | |
1284 | /* Go through the list of all base classes for the current |
1285 | (derived) type, make sure the *__vtable_map global variable |
1286 | for the base class exists, and add the base class/derived |
1287 | class pair to the class hierarchy information we are |
1288 | accumulating (for vtable pointer verification). */ |
1289 | for (i = 0; BINFO_BASE_ITERATE (binfo, i, base_binfo); i++) |
1290 | { |
1291 | tree tree_val = BINFO_TYPE (base_binfo); |
1292 | struct vtbl_map_node *vtable_map_node = NULL; |
1293 | |
1294 | vtable_map_node = vtable_find_or_create_map_decl (base_type: tree_val); |
1295 | |
1296 | if (vtable_map_node != NULL) |
1297 | update_class_hierarchy_information (base_class: tree_val, derived_class: type); |
1298 | } |
1299 | } |
1300 | } |
1301 | |
1302 | /* This function adds classes we are interested in to a list of |
1303 | classes. RECORD is the record_type node for the class we are |
1304 | adding to the list. */ |
1305 | |
1306 | void |
1307 | vtv_save_class_info (tree record) |
1308 | { |
1309 | if (!flag_vtable_verify || TREE_CODE (record) == UNION_TYPE) |
1310 | return; |
1311 | |
1312 | if (!vlt_saved_class_info) |
1313 | vec_alloc (v&: vlt_saved_class_info, nelems: 10); |
1314 | |
1315 | gcc_assert (TREE_CODE (record) == RECORD_TYPE); |
1316 | |
1317 | vec_safe_push (v&: vlt_saved_class_info, obj: record); |
1318 | } |
1319 | |
1320 | |
1321 | /* This function goes through the list of classes we saved and calls |
1322 | vtv_insert_single_class_info on each one, to build up our class |
1323 | hierarchy data structure. */ |
1324 | |
1325 | void |
1326 | vtv_recover_class_info (void) |
1327 | { |
1328 | tree current_class; |
1329 | unsigned i; |
1330 | |
1331 | if (vlt_saved_class_info) |
1332 | { |
1333 | for (i = 0; i < vlt_saved_class_info->length(); ++i) |
1334 | { |
1335 | current_class = (*vlt_saved_class_info)[i]; |
1336 | gcc_assert (TREE_CODE (current_class) == RECORD_TYPE); |
1337 | vtv_insert_single_class_info (type: current_class); |
1338 | } |
1339 | } |
1340 | } |
1341 | |
1342 | #include "gt-cp-vtable-class-hierarchy.h" |
1343 | |