1 /****************************************************************************** 2 * 3 * Module Name: dscontrol - Support for execution control opcodes - 4 * if/else/while/return 5 * 6 *****************************************************************************/ 7 8 /* 9 * Copyright (C) 2000 - 2017, Intel Corp. 10 * All rights reserved. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions, and the following disclaimer, 17 * without modification. 18 * 2. Redistributions in binary form must reproduce at minimum a disclaimer 19 * substantially similar to the "NO WARRANTY" disclaimer below 20 * ("Disclaimer") and any redistribution must be conditioned upon 21 * including a substantially similar Disclaimer requirement for further 22 * binary redistribution. 23 * 3. Neither the names of the above-listed copyright holders nor the names 24 * of any contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * Alternatively, this software may be distributed under the terms of the 28 * GNU General Public License ("GPL") version 2 as published by the Free 29 * Software Foundation. 30 * 31 * NO WARRANTY 32 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 33 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 34 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR 35 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 36 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 41 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 42 * POSSIBILITY OF SUCH DAMAGES. 43 */ 44 45 #include <acpi/acpi.h> 46 #include "accommon.h" 47 #include "amlcode.h" 48 #include "acdispat.h" 49 #include "acinterp.h" 50 #include "acdebug.h" 51 52 #define _COMPONENT ACPI_DISPATCHER 53 ACPI_MODULE_NAME("dscontrol") 54 55 /******************************************************************************* 56 * 57 * FUNCTION: acpi_ds_exec_begin_control_op 58 * 59 * PARAMETERS: walk_list - The list that owns the walk stack 60 * op - The control Op 61 * 62 * RETURN: Status 63 * 64 * DESCRIPTION: Handles all control ops encountered during control method 65 * execution. 66 * 67 ******************************************************************************/ 68 acpi_status 69 acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state, 70 union acpi_parse_object *op) 71 { 72 acpi_status status = AE_OK; 73 union acpi_generic_state *control_state; 74 75 ACPI_FUNCTION_NAME(ds_exec_begin_control_op); 76 77 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Op=%p Opcode=%2.2X State=%p\n", 78 op, op->common.aml_opcode, walk_state)); 79 80 switch (op->common.aml_opcode) { 81 case AML_WHILE_OP: 82 /* 83 * If this is an additional iteration of a while loop, continue. 84 * There is no need to allocate a new control state. 85 */ 86 if (walk_state->control_state) { 87 if (walk_state->control_state->control. 88 aml_predicate_start == 89 (walk_state->parser_state.aml - 1)) { 90 91 /* Reset the state to start-of-loop */ 92 93 walk_state->control_state->common.state = 94 ACPI_CONTROL_CONDITIONAL_EXECUTING; 95 break; 96 } 97 } 98 99 /*lint -fallthrough */ 100 101 case AML_IF_OP: 102 /* 103 * IF/WHILE: Create a new control state to manage these 104 * constructs. We need to manage these as a stack, in order 105 * to handle nesting. 106 */ 107 control_state = acpi_ut_create_control_state(); 108 if (!control_state) { 109 status = AE_NO_MEMORY; 110 break; 111 } 112 /* 113 * Save a pointer to the predicate for multiple executions 114 * of a loop 115 */ 116 control_state->control.aml_predicate_start = 117 walk_state->parser_state.aml - 1; 118 control_state->control.package_end = 119 walk_state->parser_state.pkg_end; 120 control_state->control.opcode = op->common.aml_opcode; 121 122 /* Push the control state on this walk's control stack */ 123 124 acpi_ut_push_generic_state(&walk_state->control_state, 125 control_state); 126 break; 127 128 case AML_ELSE_OP: 129 130 /* Predicate is in the state object */ 131 /* If predicate is true, the IF was executed, ignore ELSE part */ 132 133 if (walk_state->last_predicate) { 134 status = AE_CTRL_TRUE; 135 } 136 137 break; 138 139 case AML_RETURN_OP: 140 141 break; 142 143 default: 144 145 break; 146 } 147 148 return (status); 149 } 150 151 /******************************************************************************* 152 * 153 * FUNCTION: acpi_ds_exec_end_control_op 154 * 155 * PARAMETERS: walk_list - The list that owns the walk stack 156 * op - The control Op 157 * 158 * RETURN: Status 159 * 160 * DESCRIPTION: Handles all control ops encountered during control method 161 * execution. 162 * 163 ******************************************************************************/ 164 165 acpi_status 166 acpi_ds_exec_end_control_op(struct acpi_walk_state *walk_state, 167 union acpi_parse_object *op) 168 { 169 acpi_status status = AE_OK; 170 union acpi_generic_state *control_state; 171 172 ACPI_FUNCTION_NAME(ds_exec_end_control_op); 173 174 switch (op->common.aml_opcode) { 175 case AML_IF_OP: 176 177 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[IF_OP] Op=%p\n", op)); 178 179 /* 180 * Save the result of the predicate in case there is an 181 * ELSE to come 182 */ 183 walk_state->last_predicate = 184 (u8)walk_state->control_state->common.value; 185 186 /* 187 * Pop the control state that was created at the start 188 * of the IF and free it 189 */ 190 control_state = 191 acpi_ut_pop_generic_state(&walk_state->control_state); 192 acpi_ut_delete_generic_state(control_state); 193 break; 194 195 case AML_ELSE_OP: 196 197 break; 198 199 case AML_WHILE_OP: 200 201 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op)); 202 203 control_state = walk_state->control_state; 204 if (control_state->common.value) { 205 206 /* Predicate was true, the body of the loop was just executed */ 207 208 /* 209 * This loop counter mechanism allows the interpreter to escape 210 * possibly infinite loops. This can occur in poorly written AML 211 * when the hardware does not respond within a while loop and the 212 * loop does not implement a timeout. 213 */ 214 control_state->control.loop_count++; 215 if (control_state->control.loop_count > 216 acpi_gbl_max_loop_iterations) { 217 status = AE_AML_INFINITE_LOOP; 218 break; 219 } 220 221 /* 222 * Go back and evaluate the predicate and maybe execute the loop 223 * another time 224 */ 225 status = AE_CTRL_PENDING; 226 walk_state->aml_last_while = 227 control_state->control.aml_predicate_start; 228 break; 229 } 230 231 /* Predicate was false, terminate this while loop */ 232 233 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, 234 "[WHILE_OP] termination! Op=%p\n", op)); 235 236 /* Pop this control state and free it */ 237 238 control_state = 239 acpi_ut_pop_generic_state(&walk_state->control_state); 240 acpi_ut_delete_generic_state(control_state); 241 break; 242 243 case AML_RETURN_OP: 244 245 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, 246 "[RETURN_OP] Op=%p Arg=%p\n", op, 247 op->common.value.arg)); 248 249 /* 250 * One optional operand -- the return value 251 * It can be either an immediate operand or a result that 252 * has been bubbled up the tree 253 */ 254 if (op->common.value.arg) { 255 256 /* Since we have a real Return(), delete any implicit return */ 257 258 acpi_ds_clear_implicit_return(walk_state); 259 260 /* Return statement has an immediate operand */ 261 262 status = 263 acpi_ds_create_operands(walk_state, 264 op->common.value.arg); 265 if (ACPI_FAILURE(status)) { 266 return (status); 267 } 268 269 /* 270 * If value being returned is a Reference (such as 271 * an arg or local), resolve it now because it may 272 * cease to exist at the end of the method. 273 */ 274 status = 275 acpi_ex_resolve_to_value(&walk_state->operands[0], 276 walk_state); 277 if (ACPI_FAILURE(status)) { 278 return (status); 279 } 280 281 /* 282 * Get the return value and save as the last result 283 * value. This is the only place where walk_state->return_desc 284 * is set to anything other than zero! 285 */ 286 walk_state->return_desc = walk_state->operands[0]; 287 } else if (walk_state->result_count) { 288 289 /* Since we have a real Return(), delete any implicit return */ 290 291 acpi_ds_clear_implicit_return(walk_state); 292 293 /* 294 * The return value has come from a previous calculation. 295 * 296 * If value being returned is a Reference (such as 297 * an arg or local), resolve it now because it may 298 * cease to exist at the end of the method. 299 * 300 * Allow references created by the Index operator to return 301 * unchanged. 302 */ 303 if ((ACPI_GET_DESCRIPTOR_TYPE 304 (walk_state->results->results.obj_desc[0]) == 305 ACPI_DESC_TYPE_OPERAND) 306 && ((walk_state->results->results.obj_desc[0])-> 307 common.type == ACPI_TYPE_LOCAL_REFERENCE) 308 && ((walk_state->results->results.obj_desc[0])-> 309 reference.class != ACPI_REFCLASS_INDEX)) { 310 status = 311 acpi_ex_resolve_to_value(&walk_state-> 312 results->results. 313 obj_desc[0], 314 walk_state); 315 if (ACPI_FAILURE(status)) { 316 return (status); 317 } 318 } 319 320 walk_state->return_desc = 321 walk_state->results->results.obj_desc[0]; 322 } else { 323 /* No return operand */ 324 325 if (walk_state->num_operands) { 326 acpi_ut_remove_reference(walk_state-> 327 operands[0]); 328 } 329 330 walk_state->operands[0] = NULL; 331 walk_state->num_operands = 0; 332 walk_state->return_desc = NULL; 333 } 334 335 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, 336 "Completed RETURN_OP State=%p, RetVal=%p\n", 337 walk_state, walk_state->return_desc)); 338 339 /* End the control method execution right now */ 340 341 status = AE_CTRL_TERMINATE; 342 break; 343 344 case AML_NOOP_OP: 345 346 /* Just do nothing! */ 347 348 break; 349 350 case AML_BREAK_POINT_OP: 351 352 acpi_db_signal_break_point(walk_state); 353 354 /* Call to the OSL in case OS wants a piece of the action */ 355 356 status = acpi_os_signal(ACPI_SIGNAL_BREAKPOINT, 357 "Executed AML Breakpoint opcode"); 358 break; 359 360 case AML_BREAK_OP: 361 case AML_CONTINUE_OP: /* ACPI 2.0 */ 362 363 /* Pop and delete control states until we find a while */ 364 365 while (walk_state->control_state && 366 (walk_state->control_state->control.opcode != 367 AML_WHILE_OP)) { 368 control_state = 369 acpi_ut_pop_generic_state(&walk_state-> 370 control_state); 371 acpi_ut_delete_generic_state(control_state); 372 } 373 374 /* No while found? */ 375 376 if (!walk_state->control_state) { 377 return (AE_AML_NO_WHILE); 378 } 379 380 /* Was: walk_state->aml_last_while = walk_state->control_state->Control.aml_predicate_start; */ 381 382 walk_state->aml_last_while = 383 walk_state->control_state->control.package_end; 384 385 /* Return status depending on opcode */ 386 387 if (op->common.aml_opcode == AML_BREAK_OP) { 388 status = AE_CTRL_BREAK; 389 } else { 390 status = AE_CTRL_CONTINUE; 391 } 392 break; 393 394 default: 395 396 ACPI_ERROR((AE_INFO, "Unknown control opcode=0x%X Op=%p", 397 op->common.aml_opcode, op)); 398 399 status = AE_AML_BAD_OPCODE; 400 break; 401 } 402 403 return (status); 404 } 405