Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2012-2016 by the PaX Team <pageexec@freemail.hu> |
| 3 | * Copyright 2016 by Emese Revfy <re.emese@gmail.com> |
| 4 | * Licensed under the GPL v2 |
| 5 | * |
| 6 | * Note: the choice of the license means that the compilation process is |
| 7 | * NOT 'eligible' as defined by gcc's library exception to the GPL v3, |
| 8 | * but for the kernel it doesn't matter since it doesn't link against |
| 9 | * any of the gcc libraries |
| 10 | * |
| 11 | * This gcc plugin helps generate a little bit of entropy from program state, |
| 12 | * used throughout the uptime of the kernel. Here is an instrumentation example: |
| 13 | * |
| 14 | * before: |
| 15 | * void __latent_entropy test(int argc, char *argv[]) |
| 16 | * { |
| 17 | * if (argc <= 1) |
| 18 | * printf("%s: no command arguments :(\n", *argv); |
| 19 | * else |
| 20 | * printf("%s: %d command arguments!\n", *argv, args - 1); |
| 21 | * } |
| 22 | * |
| 23 | * after: |
| 24 | * void __latent_entropy test(int argc, char *argv[]) |
| 25 | * { |
| 26 | * // latent_entropy_execute() 1. |
| 27 | * unsigned long local_entropy; |
| 28 | * // init_local_entropy() 1. |
| 29 | * void *local_entropy_frameaddr; |
| 30 | * // init_local_entropy() 3. |
| 31 | * unsigned long tmp_latent_entropy; |
| 32 | * |
| 33 | * // init_local_entropy() 2. |
| 34 | * local_entropy_frameaddr = __builtin_frame_address(0); |
| 35 | * local_entropy = (unsigned long) local_entropy_frameaddr; |
| 36 | * |
| 37 | * // init_local_entropy() 4. |
| 38 | * tmp_latent_entropy = latent_entropy; |
| 39 | * // init_local_entropy() 5. |
| 40 | * local_entropy ^= tmp_latent_entropy; |
| 41 | * |
| 42 | * // latent_entropy_execute() 3. |
| 43 | * if (argc <= 1) { |
| 44 | * // perturb_local_entropy() |
| 45 | * local_entropy += 4623067384293424948; |
| 46 | * printf("%s: no command arguments :(\n", *argv); |
| 47 | * // perturb_local_entropy() |
| 48 | * } else { |
| 49 | * local_entropy ^= 3896280633962944730; |
| 50 | * printf("%s: %d command arguments!\n", *argv, args - 1); |
| 51 | * } |
| 52 | * |
| 53 | * // latent_entropy_execute() 4. |
| 54 | * tmp_latent_entropy = rol(tmp_latent_entropy, local_entropy); |
| 55 | * latent_entropy = tmp_latent_entropy; |
| 56 | * } |
| 57 | * |
| 58 | * TODO: |
| 59 | * - add ipa pass to identify not explicitly marked candidate functions |
| 60 | * - mix in more program state (function arguments/return values, |
| 61 | * loop variables, etc) |
| 62 | * - more instrumentation control via attribute parameters |
| 63 | * |
| 64 | * BUGS: |
| 65 | * - none known |
| 66 | * |
| 67 | * Options: |
| 68 | * -fplugin-arg-latent_entropy_plugin-disable |
| 69 | * |
| 70 | * Attribute: __attribute__((latent_entropy)) |
| 71 | * The latent_entropy gcc attribute can be only on functions and variables. |
| 72 | * If it is on a function then the plugin will instrument it. If the attribute |
| 73 | * is on a variable then the plugin will initialize it with a random value. |
| 74 | * The variable must be an integer, an integer array type or a structure |
| 75 | * with integer fields. |
| 76 | */ |
| 77 | |
| 78 | #include "gcc-common.h" |
| 79 | |
Kees Cook | da7389a | 2016-10-31 10:40:13 -0700 | [diff] [blame] | 80 | __visible int plugin_is_GPL_compatible; |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 81 | |
| 82 | static GTY(()) tree latent_entropy_decl; |
| 83 | |
| 84 | static struct plugin_info latent_entropy_plugin_info = { |
| 85 | .version = "201606141920vanilla", |
| 86 | .help = "disable\tturn off latent entropy instrumentation\n", |
| 87 | }; |
| 88 | |
| 89 | static unsigned HOST_WIDE_INT seed; |
| 90 | /* |
| 91 | * get_random_seed() (this is a GCC function) generates the seed. |
| 92 | * This is a simple random generator without any cryptographic security because |
| 93 | * the entropy doesn't come from here. |
| 94 | */ |
| 95 | static unsigned HOST_WIDE_INT get_random_const(void) |
| 96 | { |
| 97 | unsigned int i; |
| 98 | unsigned HOST_WIDE_INT ret = 0; |
| 99 | |
| 100 | for (i = 0; i < 8 * sizeof(ret); i++) { |
| 101 | ret = (ret << 1) | (seed & 1); |
| 102 | seed >>= 1; |
| 103 | if (ret & 1) |
| 104 | seed ^= 0xD800000000000000ULL; |
| 105 | } |
| 106 | |
| 107 | return ret; |
| 108 | } |
| 109 | |
| 110 | static tree tree_get_random_const(tree type) |
| 111 | { |
| 112 | unsigned long long mask; |
| 113 | |
| 114 | mask = 1ULL << (TREE_INT_CST_LOW(TYPE_SIZE(type)) - 1); |
| 115 | mask = 2 * (mask - 1) + 1; |
| 116 | |
| 117 | if (TYPE_UNSIGNED(type)) |
| 118 | return build_int_cstu(type, mask & get_random_const()); |
| 119 | return build_int_cst(type, mask & get_random_const()); |
| 120 | } |
| 121 | |
| 122 | static tree handle_latent_entropy_attribute(tree *node, tree name, |
| 123 | tree args __unused, |
| 124 | int flags __unused, |
| 125 | bool *no_add_attrs) |
| 126 | { |
| 127 | tree type; |
| 128 | #if BUILDING_GCC_VERSION <= 4007 |
| 129 | VEC(constructor_elt, gc) *vals; |
| 130 | #else |
| 131 | vec<constructor_elt, va_gc> *vals; |
| 132 | #endif |
| 133 | |
| 134 | switch (TREE_CODE(*node)) { |
| 135 | default: |
| 136 | *no_add_attrs = true; |
| 137 | error("%qE attribute only applies to functions and variables", |
| 138 | name); |
| 139 | break; |
| 140 | |
| 141 | case VAR_DECL: |
| 142 | if (DECL_INITIAL(*node)) { |
| 143 | *no_add_attrs = true; |
| 144 | error("variable %qD with %qE attribute must not be initialized", |
| 145 | *node, name); |
| 146 | break; |
| 147 | } |
| 148 | |
| 149 | if (!TREE_STATIC(*node)) { |
| 150 | *no_add_attrs = true; |
| 151 | error("variable %qD with %qE attribute must not be local", |
| 152 | *node, name); |
| 153 | break; |
| 154 | } |
| 155 | |
| 156 | type = TREE_TYPE(*node); |
| 157 | switch (TREE_CODE(type)) { |
| 158 | default: |
| 159 | *no_add_attrs = true; |
| 160 | error("variable %qD with %qE attribute must be an integer or a fixed length integer array type or a fixed sized structure with integer fields", |
| 161 | *node, name); |
| 162 | break; |
| 163 | |
| 164 | case RECORD_TYPE: { |
| 165 | tree fld, lst = TYPE_FIELDS(type); |
| 166 | unsigned int nelt = 0; |
| 167 | |
| 168 | for (fld = lst; fld; nelt++, fld = TREE_CHAIN(fld)) { |
| 169 | tree fieldtype; |
| 170 | |
| 171 | fieldtype = TREE_TYPE(fld); |
| 172 | if (TREE_CODE(fieldtype) == INTEGER_TYPE) |
| 173 | continue; |
| 174 | |
| 175 | *no_add_attrs = true; |
| 176 | error("structure variable %qD with %qE attribute has a non-integer field %qE", |
| 177 | *node, name, fld); |
| 178 | break; |
| 179 | } |
| 180 | |
| 181 | if (fld) |
| 182 | break; |
| 183 | |
| 184 | #if BUILDING_GCC_VERSION <= 4007 |
| 185 | vals = VEC_alloc(constructor_elt, gc, nelt); |
| 186 | #else |
| 187 | vec_alloc(vals, nelt); |
| 188 | #endif |
| 189 | |
| 190 | for (fld = lst; fld; fld = TREE_CHAIN(fld)) { |
| 191 | tree random_const, fld_t = TREE_TYPE(fld); |
| 192 | |
| 193 | random_const = tree_get_random_const(fld_t); |
| 194 | CONSTRUCTOR_APPEND_ELT(vals, fld, random_const); |
| 195 | } |
| 196 | |
| 197 | /* Initialize the fields with random constants */ |
| 198 | DECL_INITIAL(*node) = build_constructor(type, vals); |
| 199 | break; |
| 200 | } |
| 201 | |
| 202 | /* Initialize the variable with a random constant */ |
| 203 | case INTEGER_TYPE: |
| 204 | DECL_INITIAL(*node) = tree_get_random_const(type); |
| 205 | break; |
| 206 | |
| 207 | case ARRAY_TYPE: { |
| 208 | tree elt_type, array_size, elt_size; |
| 209 | unsigned int i, nelt; |
| 210 | HOST_WIDE_INT array_size_int, elt_size_int; |
| 211 | |
| 212 | elt_type = TREE_TYPE(type); |
| 213 | elt_size = TYPE_SIZE_UNIT(TREE_TYPE(type)); |
| 214 | array_size = TYPE_SIZE_UNIT(type); |
| 215 | |
| 216 | if (TREE_CODE(elt_type) != INTEGER_TYPE || !array_size |
| 217 | || TREE_CODE(array_size) != INTEGER_CST) { |
| 218 | *no_add_attrs = true; |
| 219 | error("array variable %qD with %qE attribute must be a fixed length integer array type", |
| 220 | *node, name); |
| 221 | break; |
| 222 | } |
| 223 | |
| 224 | array_size_int = TREE_INT_CST_LOW(array_size); |
| 225 | elt_size_int = TREE_INT_CST_LOW(elt_size); |
| 226 | nelt = array_size_int / elt_size_int; |
| 227 | |
| 228 | #if BUILDING_GCC_VERSION <= 4007 |
| 229 | vals = VEC_alloc(constructor_elt, gc, nelt); |
| 230 | #else |
| 231 | vec_alloc(vals, nelt); |
| 232 | #endif |
| 233 | |
| 234 | for (i = 0; i < nelt; i++) { |
| 235 | tree cst = size_int(i); |
| 236 | tree rand_cst = tree_get_random_const(elt_type); |
| 237 | |
| 238 | CONSTRUCTOR_APPEND_ELT(vals, cst, rand_cst); |
| 239 | } |
| 240 | |
| 241 | /* |
| 242 | * Initialize the elements of the array with random |
| 243 | * constants |
| 244 | */ |
| 245 | DECL_INITIAL(*node) = build_constructor(type, vals); |
| 246 | break; |
| 247 | } |
| 248 | } |
| 249 | break; |
| 250 | |
| 251 | case FUNCTION_DECL: |
| 252 | break; |
| 253 | } |
| 254 | |
| 255 | return NULL_TREE; |
| 256 | } |
| 257 | |
| 258 | static struct attribute_spec latent_entropy_attr = { |
| 259 | .name = "latent_entropy", |
| 260 | .min_length = 0, |
| 261 | .max_length = 0, |
| 262 | .decl_required = true, |
| 263 | .type_required = false, |
| 264 | .function_type_required = false, |
| 265 | .handler = handle_latent_entropy_attribute, |
| 266 | #if BUILDING_GCC_VERSION >= 4007 |
| 267 | .affects_type_identity = false |
| 268 | #endif |
| 269 | }; |
| 270 | |
| 271 | static void register_attributes(void *event_data __unused, void *data __unused) |
| 272 | { |
| 273 | register_attribute(&latent_entropy_attr); |
| 274 | } |
| 275 | |
| 276 | static bool latent_entropy_gate(void) |
| 277 | { |
| 278 | tree list; |
| 279 | |
| 280 | /* don't bother with noreturn functions for now */ |
| 281 | if (TREE_THIS_VOLATILE(current_function_decl)) |
| 282 | return false; |
| 283 | |
| 284 | /* gcc-4.5 doesn't discover some trivial noreturn functions */ |
| 285 | if (EDGE_COUNT(EXIT_BLOCK_PTR_FOR_FN(cfun)->preds) == 0) |
| 286 | return false; |
| 287 | |
| 288 | list = DECL_ATTRIBUTES(current_function_decl); |
| 289 | return lookup_attribute("latent_entropy", list) != NULL_TREE; |
| 290 | } |
| 291 | |
| 292 | static tree create_var(tree type, const char *name) |
| 293 | { |
| 294 | tree var; |
| 295 | |
| 296 | var = create_tmp_var(type, name); |
| 297 | add_referenced_var(var); |
| 298 | mark_sym_for_renaming(var); |
| 299 | return var; |
| 300 | } |
| 301 | |
| 302 | /* |
| 303 | * Set up the next operation and its constant operand to use in the latent |
| 304 | * entropy PRNG. When RHS is specified, the request is for perturbing the |
| 305 | * local latent entropy variable, otherwise it is for perturbing the global |
| 306 | * latent entropy variable where the two operands are already given by the |
| 307 | * local and global latent entropy variables themselves. |
| 308 | * |
| 309 | * The operation is one of add/xor/rol when instrumenting the local entropy |
| 310 | * variable and one of add/xor when perturbing the global entropy variable. |
| 311 | * Rotation is not used for the latter case because it would transmit less |
| 312 | * entropy to the global variable than the other two operations. |
| 313 | */ |
| 314 | static enum tree_code get_op(tree *rhs) |
| 315 | { |
| 316 | static enum tree_code op; |
| 317 | unsigned HOST_WIDE_INT random_const; |
| 318 | |
| 319 | random_const = get_random_const(); |
| 320 | |
| 321 | switch (op) { |
| 322 | case BIT_XOR_EXPR: |
| 323 | op = PLUS_EXPR; |
| 324 | break; |
| 325 | |
| 326 | case PLUS_EXPR: |
| 327 | if (rhs) { |
| 328 | op = LROTATE_EXPR; |
| 329 | /* |
| 330 | * This code limits the value of random_const to |
Kees Cook | 9988f4d | 2016-12-16 12:59:31 -0800 | [diff] [blame] | 331 | * the size of a long for the rotation |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 332 | */ |
Kees Cook | 9988f4d | 2016-12-16 12:59:31 -0800 | [diff] [blame] | 333 | random_const %= TYPE_PRECISION(long_unsigned_type_node); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 334 | break; |
| 335 | } |
| 336 | |
| 337 | case LROTATE_EXPR: |
| 338 | default: |
| 339 | op = BIT_XOR_EXPR; |
| 340 | break; |
| 341 | } |
| 342 | if (rhs) |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 343 | *rhs = build_int_cstu(long_unsigned_type_node, random_const); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 344 | return op; |
| 345 | } |
| 346 | |
| 347 | static gimple create_assign(enum tree_code code, tree lhs, tree op1, |
| 348 | tree op2) |
| 349 | { |
| 350 | return gimple_build_assign_with_ops(code, lhs, op1, op2); |
| 351 | } |
| 352 | |
| 353 | static void perturb_local_entropy(basic_block bb, tree local_entropy) |
| 354 | { |
| 355 | gimple_stmt_iterator gsi; |
| 356 | gimple assign; |
| 357 | tree rhs; |
| 358 | enum tree_code op; |
| 359 | |
| 360 | op = get_op(&rhs); |
| 361 | assign = create_assign(op, local_entropy, local_entropy, rhs); |
| 362 | gsi = gsi_after_labels(bb); |
| 363 | gsi_insert_before(&gsi, assign, GSI_NEW_STMT); |
| 364 | update_stmt(assign); |
| 365 | } |
| 366 | |
| 367 | static void __perturb_latent_entropy(gimple_stmt_iterator *gsi, |
| 368 | tree local_entropy) |
| 369 | { |
| 370 | gimple assign; |
| 371 | tree temp; |
| 372 | enum tree_code op; |
| 373 | |
| 374 | /* 1. create temporary copy of latent_entropy */ |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 375 | temp = create_var(long_unsigned_type_node, "temp_latent_entropy"); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 376 | |
| 377 | /* 2. read... */ |
| 378 | add_referenced_var(latent_entropy_decl); |
| 379 | mark_sym_for_renaming(latent_entropy_decl); |
| 380 | assign = gimple_build_assign(temp, latent_entropy_decl); |
| 381 | gsi_insert_before(gsi, assign, GSI_NEW_STMT); |
| 382 | update_stmt(assign); |
| 383 | |
| 384 | /* 3. ...modify... */ |
| 385 | op = get_op(NULL); |
| 386 | assign = create_assign(op, temp, temp, local_entropy); |
| 387 | gsi_insert_after(gsi, assign, GSI_NEW_STMT); |
| 388 | update_stmt(assign); |
| 389 | |
| 390 | /* 4. ...write latent_entropy */ |
| 391 | assign = gimple_build_assign(latent_entropy_decl, temp); |
| 392 | gsi_insert_after(gsi, assign, GSI_NEW_STMT); |
| 393 | update_stmt(assign); |
| 394 | } |
| 395 | |
| 396 | static bool handle_tail_calls(basic_block bb, tree local_entropy) |
| 397 | { |
| 398 | gimple_stmt_iterator gsi; |
| 399 | |
| 400 | for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { |
| 401 | gcall *call; |
| 402 | gimple stmt = gsi_stmt(gsi); |
| 403 | |
| 404 | if (!is_gimple_call(stmt)) |
| 405 | continue; |
| 406 | |
| 407 | call = as_a_gcall(stmt); |
| 408 | if (!gimple_call_tail_p(call)) |
| 409 | continue; |
| 410 | |
| 411 | __perturb_latent_entropy(&gsi, local_entropy); |
| 412 | return true; |
| 413 | } |
| 414 | |
| 415 | return false; |
| 416 | } |
| 417 | |
| 418 | static void perturb_latent_entropy(tree local_entropy) |
| 419 | { |
| 420 | edge_iterator ei; |
| 421 | edge e, last_bb_e; |
| 422 | basic_block last_bb; |
| 423 | |
| 424 | gcc_assert(single_pred_p(EXIT_BLOCK_PTR_FOR_FN(cfun))); |
| 425 | last_bb_e = single_pred_edge(EXIT_BLOCK_PTR_FOR_FN(cfun)); |
| 426 | |
| 427 | FOR_EACH_EDGE(e, ei, last_bb_e->src->preds) { |
| 428 | if (ENTRY_BLOCK_PTR_FOR_FN(cfun) == e->src) |
| 429 | continue; |
| 430 | if (EXIT_BLOCK_PTR_FOR_FN(cfun) == e->src) |
| 431 | continue; |
| 432 | |
| 433 | handle_tail_calls(e->src, local_entropy); |
| 434 | } |
| 435 | |
| 436 | last_bb = single_pred(EXIT_BLOCK_PTR_FOR_FN(cfun)); |
| 437 | if (!handle_tail_calls(last_bb, local_entropy)) { |
| 438 | gimple_stmt_iterator gsi = gsi_last_bb(last_bb); |
| 439 | |
| 440 | __perturb_latent_entropy(&gsi, local_entropy); |
| 441 | } |
| 442 | } |
| 443 | |
| 444 | static void init_local_entropy(basic_block bb, tree local_entropy) |
| 445 | { |
| 446 | gimple assign, call; |
| 447 | tree frame_addr, rand_const, tmp, fndecl, udi_frame_addr; |
| 448 | enum tree_code op; |
| 449 | unsigned HOST_WIDE_INT rand_cst; |
| 450 | gimple_stmt_iterator gsi = gsi_after_labels(bb); |
| 451 | |
| 452 | /* 1. create local_entropy_frameaddr */ |
| 453 | frame_addr = create_var(ptr_type_node, "local_entropy_frameaddr"); |
| 454 | |
| 455 | /* 2. local_entropy_frameaddr = __builtin_frame_address() */ |
| 456 | fndecl = builtin_decl_implicit(BUILT_IN_FRAME_ADDRESS); |
| 457 | call = gimple_build_call(fndecl, 1, integer_zero_node); |
| 458 | gimple_call_set_lhs(call, frame_addr); |
| 459 | gsi_insert_before(&gsi, call, GSI_NEW_STMT); |
| 460 | update_stmt(call); |
| 461 | |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 462 | udi_frame_addr = fold_convert(long_unsigned_type_node, frame_addr); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 463 | assign = gimple_build_assign(local_entropy, udi_frame_addr); |
| 464 | gsi_insert_after(&gsi, assign, GSI_NEW_STMT); |
| 465 | update_stmt(assign); |
| 466 | |
| 467 | /* 3. create temporary copy of latent_entropy */ |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 468 | tmp = create_var(long_unsigned_type_node, "temp_latent_entropy"); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 469 | |
| 470 | /* 4. read the global entropy variable into local entropy */ |
| 471 | add_referenced_var(latent_entropy_decl); |
| 472 | mark_sym_for_renaming(latent_entropy_decl); |
| 473 | assign = gimple_build_assign(tmp, latent_entropy_decl); |
| 474 | gsi_insert_after(&gsi, assign, GSI_NEW_STMT); |
| 475 | update_stmt(assign); |
| 476 | |
| 477 | /* 5. mix local_entropy_frameaddr into local entropy */ |
| 478 | assign = create_assign(BIT_XOR_EXPR, local_entropy, local_entropy, tmp); |
| 479 | gsi_insert_after(&gsi, assign, GSI_NEW_STMT); |
| 480 | update_stmt(assign); |
| 481 | |
| 482 | rand_cst = get_random_const(); |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 483 | rand_const = build_int_cstu(long_unsigned_type_node, rand_cst); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 484 | op = get_op(NULL); |
| 485 | assign = create_assign(op, local_entropy, local_entropy, rand_const); |
| 486 | gsi_insert_after(&gsi, assign, GSI_NEW_STMT); |
| 487 | update_stmt(assign); |
| 488 | } |
| 489 | |
| 490 | static bool create_latent_entropy_decl(void) |
| 491 | { |
| 492 | varpool_node_ptr node; |
| 493 | |
| 494 | if (latent_entropy_decl != NULL_TREE) |
| 495 | return true; |
| 496 | |
| 497 | FOR_EACH_VARIABLE(node) { |
| 498 | tree name, var = NODE_DECL(node); |
| 499 | |
| 500 | if (DECL_NAME_LENGTH(var) < sizeof("latent_entropy") - 1) |
| 501 | continue; |
| 502 | |
| 503 | name = DECL_NAME(var); |
| 504 | if (strcmp(IDENTIFIER_POINTER(name), "latent_entropy")) |
| 505 | continue; |
| 506 | |
| 507 | latent_entropy_decl = var; |
| 508 | break; |
| 509 | } |
| 510 | |
| 511 | return latent_entropy_decl != NULL_TREE; |
| 512 | } |
| 513 | |
| 514 | static unsigned int latent_entropy_execute(void) |
| 515 | { |
| 516 | basic_block bb; |
| 517 | tree local_entropy; |
| 518 | |
| 519 | if (!create_latent_entropy_decl()) |
| 520 | return 0; |
| 521 | |
| 522 | /* prepare for step 2 below */ |
| 523 | gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun))); |
| 524 | bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)); |
| 525 | if (!single_pred_p(bb)) { |
| 526 | split_edge(single_succ_edge(ENTRY_BLOCK_PTR_FOR_FN(cfun))); |
| 527 | gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun))); |
| 528 | bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)); |
| 529 | } |
| 530 | |
| 531 | /* 1. create the local entropy variable */ |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 532 | local_entropy = create_var(long_unsigned_type_node, "local_entropy"); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 533 | |
| 534 | /* 2. initialize the local entropy variable */ |
| 535 | init_local_entropy(bb, local_entropy); |
| 536 | |
| 537 | bb = bb->next_bb; |
| 538 | |
| 539 | /* |
| 540 | * 3. instrument each BB with an operation on the |
| 541 | * local entropy variable |
| 542 | */ |
| 543 | while (bb != EXIT_BLOCK_PTR_FOR_FN(cfun)) { |
| 544 | perturb_local_entropy(bb, local_entropy); |
| 545 | bb = bb->next_bb; |
| 546 | }; |
| 547 | |
| 548 | /* 4. mix local entropy into the global entropy variable */ |
| 549 | perturb_latent_entropy(local_entropy); |
| 550 | return 0; |
| 551 | } |
| 552 | |
| 553 | static void latent_entropy_start_unit(void *gcc_data __unused, |
| 554 | void *user_data __unused) |
| 555 | { |
| 556 | tree type, id; |
| 557 | int quals; |
| 558 | |
| 559 | seed = get_random_seed(false); |
| 560 | |
| 561 | if (in_lto_p) |
| 562 | return; |
| 563 | |
Kees Cook | 58bea414 | 2016-10-19 00:08:04 +0200 | [diff] [blame] | 564 | /* extern volatile unsigned long latent_entropy */ |
| 565 | quals = TYPE_QUALS(long_unsigned_type_node) | TYPE_QUAL_VOLATILE; |
| 566 | type = build_qualified_type(long_unsigned_type_node, quals); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 567 | id = get_identifier("latent_entropy"); |
| 568 | latent_entropy_decl = build_decl(UNKNOWN_LOCATION, VAR_DECL, id, type); |
| 569 | |
| 570 | TREE_STATIC(latent_entropy_decl) = 1; |
| 571 | TREE_PUBLIC(latent_entropy_decl) = 1; |
| 572 | TREE_USED(latent_entropy_decl) = 1; |
| 573 | DECL_PRESERVE_P(latent_entropy_decl) = 1; |
| 574 | TREE_THIS_VOLATILE(latent_entropy_decl) = 1; |
| 575 | DECL_EXTERNAL(latent_entropy_decl) = 1; |
| 576 | DECL_ARTIFICIAL(latent_entropy_decl) = 1; |
| 577 | lang_hooks.decls.pushdecl(latent_entropy_decl); |
| 578 | } |
| 579 | |
| 580 | #define PASS_NAME latent_entropy |
| 581 | #define PROPERTIES_REQUIRED PROP_gimple_leh | PROP_cfg |
| 582 | #define TODO_FLAGS_FINISH TODO_verify_ssa | TODO_verify_stmts | TODO_dump_func \ |
| 583 | | TODO_update_ssa |
| 584 | #include "gcc-generate-gimple-pass.h" |
| 585 | |
Kees Cook | da7389a | 2016-10-31 10:40:13 -0700 | [diff] [blame] | 586 | __visible int plugin_init(struct plugin_name_args *plugin_info, |
| 587 | struct plugin_gcc_version *version) |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 588 | { |
| 589 | bool enabled = true; |
| 590 | const char * const plugin_name = plugin_info->base_name; |
| 591 | const int argc = plugin_info->argc; |
| 592 | const struct plugin_argument * const argv = plugin_info->argv; |
| 593 | int i; |
| 594 | |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 595 | static const struct ggc_root_tab gt_ggc_r_gt_latent_entropy[] = { |
| 596 | { |
| 597 | .base = &latent_entropy_decl, |
| 598 | .nelt = 1, |
| 599 | .stride = sizeof(latent_entropy_decl), |
| 600 | .cb = >_ggc_mx_tree_node, |
| 601 | .pchw = >_pch_nx_tree_node |
| 602 | }, |
| 603 | LAST_GGC_ROOT_TAB |
| 604 | }; |
| 605 | |
Kees Cook | 5a45a4c | 2017-01-13 14:09:35 -0800 | [diff] [blame] | 606 | PASS_INFO(latent_entropy, "optimized", 1, PASS_POS_INSERT_BEFORE); |
| 607 | |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 608 | if (!plugin_default_version_check(version, &gcc_version)) { |
| 609 | error(G_("incompatible gcc/plugin versions")); |
| 610 | return 1; |
| 611 | } |
| 612 | |
| 613 | for (i = 0; i < argc; ++i) { |
| 614 | if (!(strcmp(argv[i].key, "disable"))) { |
| 615 | enabled = false; |
| 616 | continue; |
| 617 | } |
Masanari Iida | 9165dab | 2016-09-17 23:44:17 +0900 | [diff] [blame] | 618 | error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); |
Emese Revfy | 38addce | 2016-06-20 20:41:19 +0200 | [diff] [blame] | 619 | } |
| 620 | |
| 621 | register_callback(plugin_name, PLUGIN_INFO, NULL, |
| 622 | &latent_entropy_plugin_info); |
| 623 | if (enabled) { |
| 624 | register_callback(plugin_name, PLUGIN_START_UNIT, |
| 625 | &latent_entropy_start_unit, NULL); |
| 626 | register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, |
| 627 | NULL, (void *)>_ggc_r_gt_latent_entropy); |
| 628 | register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, |
| 629 | &latent_entropy_pass_info); |
| 630 | } |
| 631 | register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, |
| 632 | NULL); |
| 633 | |
| 634 | return 0; |
| 635 | } |