1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 2 /****************************************************************************** 3 * 4 * Module Name: dscontrol - Support for execution control opcodes - 5 * if/else/while/return 6 * 7 * Copyright (C) 2000 - 2023, Intel Corp. 8 * 9 *****************************************************************************/ 10 11 #include <acpi/acpi.h> 12 #include "accommon.h" 13 #include "amlcode.h" 14 #include "acdispat.h" 15 #include "acinterp.h" 16 #include "acdebug.h" 17 18 #define _COMPONENT ACPI_DISPATCHER 19 ACPI_MODULE_NAME("dscontrol") 20 21 /******************************************************************************* 22 * 23 * FUNCTION: acpi_ds_exec_begin_control_op 24 * 25 * PARAMETERS: walk_list - The list that owns the walk stack 26 * op - The control Op 27 * 28 * RETURN: Status 29 * 30 * DESCRIPTION: Handles all control ops encountered during control method 31 * execution. 32 * 33 ******************************************************************************/ 34 acpi_status 35 acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state, 36 union acpi_parse_object *op) 37 { 38 acpi_status status = AE_OK; 39 union acpi_generic_state *control_state; 40 41 ACPI_FUNCTION_NAME(ds_exec_begin_control_op); 42 43 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Op=%p Opcode=%2.2X State=%p\n", 44 op, op->common.aml_opcode, walk_state)); 45 46 switch (op->common.aml_opcode) { 47 case AML_WHILE_OP: 48 /* 49 * If this is an additional iteration of a while loop, continue. 50 * There is no need to allocate a new control state. 51 */ 52 if (walk_state->control_state) { 53 if (walk_state->control_state->control. 54 aml_predicate_start == 55 (walk_state->parser_state.aml - 1)) { 56 57 /* Reset the state to start-of-loop */ 58 59 walk_state->control_state->common.state = 60 ACPI_CONTROL_CONDITIONAL_EXECUTING; 61 break; 62 } 63 } 64 65 ACPI_FALLTHROUGH; 66 67 case AML_IF_OP: 68 /* 69 * IF/WHILE: Create a new control state to manage these 70 * constructs. We need to manage these as a stack, in order 71 * to handle nesting. 72 */ 73 control_state = acpi_ut_create_control_state(); 74 if (!control_state) { 75 status = AE_NO_MEMORY; 76 break; 77 } 78 /* 79 * Save a pointer to the predicate for multiple executions 80 * of a loop 81 */ 82 control_state->control.aml_predicate_start = 83 walk_state->parser_state.aml - 1; 84 control_state->control.package_end = 85 walk_state->parser_state.pkg_end; 86 control_state->control.opcode = op->common.aml_opcode; 87 control_state->control.loop_timeout = acpi_os_get_timer() + 88 ((u64)acpi_gbl_max_loop_iterations * ACPI_100NSEC_PER_SEC); 89 90 /* Push the control state on this walk's control stack */ 91 92 acpi_ut_push_generic_state(&walk_state->control_state, 93 control_state); 94 break; 95 96 case AML_ELSE_OP: 97 98 /* Predicate is in the state object */ 99 /* If predicate is true, the IF was executed, ignore ELSE part */ 100 101 if (walk_state->last_predicate) { 102 status = AE_CTRL_TRUE; 103 } 104 105 break; 106 107 case AML_RETURN_OP: 108 109 break; 110 111 default: 112 113 break; 114 } 115 116 return (status); 117 } 118 119 /******************************************************************************* 120 * 121 * FUNCTION: acpi_ds_exec_end_control_op 122 * 123 * PARAMETERS: walk_list - The list that owns the walk stack 124 * op - The control Op 125 * 126 * RETURN: Status 127 * 128 * DESCRIPTION: Handles all control ops encountered during control method 129 * execution. 130 * 131 ******************************************************************************/ 132 133 acpi_status 134 acpi_ds_exec_end_control_op(struct acpi_walk_state *walk_state, 135 union acpi_parse_object *op) 136 { 137 acpi_status status = AE_OK; 138 union acpi_generic_state *control_state; 139 140 ACPI_FUNCTION_NAME(ds_exec_end_control_op); 141 142 switch (op->common.aml_opcode) { 143 case AML_IF_OP: 144 145 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[IF_OP] Op=%p\n", op)); 146 147 /* 148 * Save the result of the predicate in case there is an 149 * ELSE to come 150 */ 151 walk_state->last_predicate = 152 (u8)walk_state->control_state->common.value; 153 154 /* 155 * Pop the control state that was created at the start 156 * of the IF and free it 157 */ 158 control_state = 159 acpi_ut_pop_generic_state(&walk_state->control_state); 160 acpi_ut_delete_generic_state(control_state); 161 break; 162 163 case AML_ELSE_OP: 164 165 break; 166 167 case AML_WHILE_OP: 168 169 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op)); 170 171 control_state = walk_state->control_state; 172 if (control_state->common.value) { 173 174 /* Predicate was true, the body of the loop was just executed */ 175 176 /* 177 * This infinite loop detection mechanism allows the interpreter 178 * to escape possibly infinite loops. This can occur in poorly 179 * written AML when the hardware does not respond within a while 180 * loop and the loop does not implement a timeout. 181 */ 182 if (ACPI_TIME_AFTER(acpi_os_get_timer(), 183 control_state->control. 184 loop_timeout)) { 185 status = AE_AML_LOOP_TIMEOUT; 186 break; 187 } 188 189 /* 190 * Go back and evaluate the predicate and maybe execute the loop 191 * another time 192 */ 193 status = AE_CTRL_PENDING; 194 walk_state->aml_last_while = 195 control_state->control.aml_predicate_start; 196 break; 197 } 198 199 /* Predicate was false, terminate this while loop */ 200 201 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, 202 "[WHILE_OP] termination! Op=%p\n", op)); 203 204 /* Pop this control state and free it */ 205 206 control_state = 207 acpi_ut_pop_generic_state(&walk_state->control_state); 208 acpi_ut_delete_generic_state(control_state); 209 break; 210 211 case AML_RETURN_OP: 212 213 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, 214 "[RETURN_OP] Op=%p Arg=%p\n", op, 215 op->common.value.arg)); 216 217 /* 218 * One optional operand -- the return value 219 * It can be either an immediate operand or a result that 220 * has been bubbled up the tree 221 */ 222 if (op->common.value.arg) { 223 224 /* Since we have a real Return(), delete any implicit return */ 225 226 acpi_ds_clear_implicit_return(walk_state); 227 228 /* Return statement has an immediate operand */ 229 230 status = 231 acpi_ds_create_operands(walk_state, 232 op->common.value.arg); 233 if (ACPI_FAILURE(status)) { 234 return (status); 235 } 236 237 /* 238 * If value being returned is a Reference (such as 239 * an arg or local), resolve it now because it may 240 * cease to exist at the end of the method. 241 */ 242 status = 243 acpi_ex_resolve_to_value(&walk_state->operands[0], 244 walk_state); 245 if (ACPI_FAILURE(status)) { 246 return (status); 247 } 248 249 /* 250 * Get the return value and save as the last result 251 * value. This is the only place where walk_state->return_desc 252 * is set to anything other than zero! 253 */ 254 walk_state->return_desc = walk_state->operands[0]; 255 } else if (walk_state->result_count) { 256 257 /* Since we have a real Return(), delete any implicit return */ 258 259 acpi_ds_clear_implicit_return(walk_state); 260 261 /* 262 * The return value has come from a previous calculation. 263 * 264 * If value being returned is a Reference (such as 265 * an arg or local), resolve it now because it may 266 * cease to exist at the end of the method. 267 * 268 * Allow references created by the Index operator to return 269 * unchanged. 270 */ 271 if ((ACPI_GET_DESCRIPTOR_TYPE 272 (walk_state->results->results.obj_desc[0]) == 273 ACPI_DESC_TYPE_OPERAND) 274 && ((walk_state->results->results.obj_desc[0])-> 275 common.type == ACPI_TYPE_LOCAL_REFERENCE) 276 && ((walk_state->results->results.obj_desc[0])-> 277 reference.class != ACPI_REFCLASS_INDEX)) { 278 status = 279 acpi_ex_resolve_to_value(&walk_state-> 280 results->results. 281 obj_desc[0], 282 walk_state); 283 if (ACPI_FAILURE(status)) { 284 return (status); 285 } 286 } 287 288 walk_state->return_desc = 289 walk_state->results->results.obj_desc[0]; 290 } else { 291 /* No return operand */ 292 293 if (walk_state->num_operands) { 294 acpi_ut_remove_reference(walk_state-> 295 operands[0]); 296 } 297 298 walk_state->operands[0] = NULL; 299 walk_state->num_operands = 0; 300 walk_state->return_desc = NULL; 301 } 302 303 ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, 304 "Completed RETURN_OP State=%p, RetVal=%p\n", 305 walk_state, walk_state->return_desc)); 306 307 /* End the control method execution right now */ 308 309 status = AE_CTRL_TERMINATE; 310 break; 311 312 case AML_NOOP_OP: 313 314 /* Just do nothing! */ 315 316 break; 317 318 case AML_BREAKPOINT_OP: 319 320 acpi_db_signal_break_point(walk_state); 321 322 /* Call to the OSL in case OS wants a piece of the action */ 323 324 status = acpi_os_signal(ACPI_SIGNAL_BREAKPOINT, 325 "Executed AML Breakpoint opcode"); 326 break; 327 328 case AML_BREAK_OP: 329 case AML_CONTINUE_OP: /* ACPI 2.0 */ 330 331 /* Pop and delete control states until we find a while */ 332 333 while (walk_state->control_state && 334 (walk_state->control_state->control.opcode != 335 AML_WHILE_OP)) { 336 control_state = 337 acpi_ut_pop_generic_state(&walk_state-> 338 control_state); 339 acpi_ut_delete_generic_state(control_state); 340 } 341 342 /* No while found? */ 343 344 if (!walk_state->control_state) { 345 return (AE_AML_NO_WHILE); 346 } 347 348 /* Was: walk_state->aml_last_while = walk_state->control_state->Control.aml_predicate_start; */ 349 350 walk_state->aml_last_while = 351 walk_state->control_state->control.package_end; 352 353 /* Return status depending on opcode */ 354 355 if (op->common.aml_opcode == AML_BREAK_OP) { 356 status = AE_CTRL_BREAK; 357 } else { 358 status = AE_CTRL_CONTINUE; 359 } 360 break; 361 362 default: 363 364 ACPI_ERROR((AE_INFO, "Unknown control opcode=0x%X Op=%p", 365 op->common.aml_opcode, op)); 366 367 status = AE_AML_BAD_OPCODE; 368 break; 369 } 370 371 return (status); 372 } 373