1 /* Copyright (c) 2014. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
11 #include <elfutils/libdw.h>
13 #include "mc_private.h"
15 static int mc_dwarf_push_value(mc_expression_state_t state, Dwarf_Off value)
17 if (state->stack_size >= MC_EXPRESSION_STACK_SIZE)
18 return MC_EXPRESSION_E_STACK_OVERFLOW;
20 state->stack[state->stack_size++] = value;
24 static int mc_dwarf_register_to_libunwind(int dwarf_register)
26 #if defined(UNW_TARGET_X86_64)
27 // It seems for this arch, DWARF and libunwind agree in the numbering:
28 return dwarf_register;
29 #elif defined(UNW_TARGET_X86)
30 // Could't find the authoritative source of information for this.
31 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
32 switch (dwarf_register) {
52 return UNW_X86_EFLAGS;
82 xbt_die("Bad/unknown register number.");
85 #error This architecture is not supported yet.
89 int mc_dwarf_execute_expression(size_t n, const Dwarf_Op * ops,
90 mc_expression_state_t state)
92 for (int i = 0; i != n; ++i) {
94 const Dwarf_Op *op = ops + i;
95 uint8_t atom = op->atom;
134 mc_dwarf_register_to_libunwind(op->atom - DW_OP_breg0);
137 return MC_EXPRESSION_E_MISSING_STACK_CONTEXT;
138 unw_get_reg(state->cursor, register_id, &res);
139 error = mc_dwarf_push_value(state, res + op->number);
143 // Push the CFA (Canonical Frame Addresse):
144 case DW_OP_call_frame_cfa:
146 // UNW_X86_64_CFA does not return the CFA DWARF expects
147 // (it is a synonym for UNW_X86_64_RSP) so copy the cursor,
148 // unwind it once in order to find the parent SP:
151 return MC_EXPRESSION_E_MISSING_STACK_CONTEXT;
154 unw_cursor_t cursor = *(state->cursor);
158 unw_get_reg(&cursor, UNW_TDEP_SP, &res);
159 error = mc_dwarf_push_value(state, res);
167 if (!state->frame_base)
168 return MC_EXPRESSION_E_MISSING_FRAME_BASE;
170 mc_dwarf_push_value(state,
171 ((uintptr_t) state->frame_base) + op->number);
210 error = mc_dwarf_push_value(state, atom - DW_OP_lit0);
214 if (!state->object_info)
215 return MC_EXPRESSION_E_NO_BASE_ADDRESS;
216 if (state->stack_size == MC_EXPRESSION_STACK_SIZE)
217 return MC_EXPRESSION_E_STACK_OVERFLOW;
218 error = mc_dwarf_push_value(state,
219 (Dwarf_Off) (uintptr_t)
220 MC_object_base_address(state->object_info) +
234 if (state->stack_size == MC_EXPRESSION_STACK_SIZE)
235 return MC_EXPRESSION_E_STACK_OVERFLOW;
236 error = mc_dwarf_push_value(state, op->number);
239 // Stack manipulation:
241 // Push the value at the top of the stack:
243 if (state->stack_size == 0)
244 return MC_EXPRESSION_E_STACK_UNDERFLOW;
246 error = mc_dwarf_push_value(state, state->stack[state->stack_size - 1]);
250 if (state->stack_size == 0)
251 return MC_EXPRESSION_E_STACK_UNDERFLOW;
257 if (state->stack_size < 2)
258 return MC_EXPRESSION_E_STACK_UNDERFLOW;
260 uintptr_t temp = state->stack[state->stack_size - 2];
261 state->stack[state->stack_size - 2] =
262 state->stack[state->stack_size - 1];
263 state->stack[state->stack_size - 1] = temp;
268 if (state->stack_size < 2)
269 return MC_EXPRESSION_E_STACK_UNDERFLOW;
270 error = mc_dwarf_push_value(state, state->stack[state->stack_size - 2]);
276 if (state->stack_size < 2)
277 return MC_EXPRESSION_E_STACK_UNDERFLOW;
280 state->stack[state->stack_size - 2] +
281 state->stack[state->stack_size - 1];
282 state->stack[state->stack_size - 2] = result;
288 if (state->stack_size < 2)
289 return MC_EXPRESSION_E_STACK_UNDERFLOW;
292 state->stack[state->stack_size - 2] -
293 state->stack[state->stack_size - 1];
294 state->stack[state->stack_size - 2] = result;
299 case DW_OP_plus_uconst:
300 if (state->stack_size == 0)
301 return MC_EXPRESSION_E_STACK_UNDERFLOW;
302 state->stack[state->stack_size - 1] += op->number;
306 if (state->stack_size == 0)
307 return MC_EXPRESSION_E_STACK_UNDERFLOW;
308 state->stack[state->stack_size - 1] =
309 ~state->stack[state->stack_size - 1];
313 if (state->stack_size == 0)
314 return MC_EXPRESSION_E_STACK_UNDERFLOW;
316 intptr_t value = state->stack[state->stack_size - 1];
319 state->stack[state->stack_size - 1] = value;
324 if (state->stack_size < 2)
325 return MC_EXPRESSION_E_STACK_UNDERFLOW;
328 state->stack[state->stack_size - 2] -
329 state->stack[state->stack_size - 1];
330 state->stack[state->stack_size - 2] = result;
336 if (state->stack_size < 2)
337 return MC_EXPRESSION_E_STACK_UNDERFLOW;
340 state->stack[state->stack_size -
341 2] & state->stack[state->stack_size - 1];
342 state->stack[state->stack_size - 2] = result;
348 if (state->stack_size < 2)
349 return MC_EXPRESSION_E_STACK_UNDERFLOW;
352 state->stack[state->stack_size -
353 2] | state->stack[state->stack_size - 1];
354 state->stack[state->stack_size - 2] = result;
360 if (state->stack_size < 2)
361 return MC_EXPRESSION_E_STACK_UNDERFLOW;
364 state->stack[state->stack_size -
365 2] ^ state->stack[state->stack_size - 1];
366 state->stack[state->stack_size - 2] = result;
375 case DW_OP_deref_size:
376 return MC_EXPRESSION_E_UNSUPPORTED_OPERATION;
379 if (state->stack_size == 0)
380 return MC_EXPRESSION_E_STACK_UNDERFLOW;
383 uintptr_t address = (uintptr_t) state->stack[state->stack_size - 1];
385 uintptr_t* res = (uintptr_t*) mc_snapshot_read((void*) address, state->snapshot, state->process_index, &temp, sizeof(uintptr_t));
386 state->stack[state->stack_size - 1] = *res;
392 return MC_EXPRESSION_E_UNSUPPORTED_OPERATION;
403 /** \brief Resolve a location expression
404 * \deprecated Use mc_dwarf_resolve_expression
406 void mc_dwarf_resolve_location(mc_location_t location,
407 mc_expression_t expression,
408 mc_object_info_t object_info,
410 void *frame_pointer_address,
411 mc_snapshot_t snapshot, int process_index)
413 s_mc_expression_state_t state;
414 memset(&state, 0, sizeof(s_mc_expression_state_t));
415 state.frame_base = frame_pointer_address;
417 state.snapshot = snapshot;
418 state.object_info = object_info;
419 state.process_index = process_index;
421 if (expression->size >= 1
422 && expression->ops[0].atom >=DW_OP_reg0 && expression->ops[0].atom <= DW_OP_reg31) {
423 int dwarf_register = expression->ops[0].atom - DW_OP_reg0;
424 xbt_assert(c, "Missing frame context for register operation DW_OP_reg%i",
426 location->memory_location = NULL;
427 location->cursor = c;
428 location->register_id = mc_dwarf_register_to_libunwind(dwarf_register);
432 if (mc_dwarf_execute_expression(expression->size, expression->ops, &state))
433 xbt_die("Error evaluating DWARF expression");
434 if (state.stack_size == 0)
435 xbt_die("No value on the stack");
437 location->memory_location = (void*) state.stack[state.stack_size - 1];
438 location->cursor = NULL;
439 location->register_id = 0;
443 static mc_expression_t mc_find_expression(mc_location_list_t locations, unw_word_t ip) {
444 for (size_t i = 0; i != locations->size; ++i) {
445 mc_expression_t expression = locations->locations + i;
446 if ((expression->lowpc == NULL && expression->highpc == NULL)
447 || (ip && ip >= (unw_word_t) expression->lowpc
448 && ip < (unw_word_t) expression->highpc)) {
455 void mc_dwarf_resolve_locations(mc_location_t location,
456 mc_location_list_t locations,
457 mc_object_info_t object_info,
459 void *frame_pointer_address,
460 mc_snapshot_t snapshot, int process_index)
465 if (unw_get_reg(c, UNW_REG_IP, &ip))
466 xbt_die("Could not resolve IP");
469 mc_expression_t expression = mc_find_expression(locations, ip);
471 mc_dwarf_resolve_location(location,
472 expression, object_info, c,
473 frame_pointer_address, snapshot, process_index);
475 xbt_die("Could not resolve location");
479 /** \brief Find the frame base of a given frame
484 void *mc_find_frame_base(dw_frame_t frame, mc_object_info_t object_info,
485 unw_cursor_t * unw_cursor)
487 s_mc_location_t location;
488 mc_dwarf_resolve_locations(&location,
489 &frame->frame_base, object_info,
490 unw_cursor, NULL, NULL, -1);
491 switch(mc_get_location_type(&location)) {
492 case MC_LOCATION_TYPE_ADDRESS:
493 return location.memory_location;
495 case MC_LOCATION_TYPE_REGISTER: {
496 // This is a special case.
497 // The register if not the location of the frame base
498 // (a frame base cannot be located in a register)
499 // Instead, DWARF defines this to mean that the register
500 // contains the address of the frame base.
502 unw_get_reg(location.cursor, location.register_id, &word);
507 xbt_die("Cannot handle non-address frame base");
508 return NULL; // Unreachable
512 void mc_dwarf_expression_clear(mc_expression_t expression)
514 free(expression->ops);
515 expression->ops = NULL;
516 expression->size = 0;
517 expression->lowpc = NULL;
518 expression->highpc = NULL;
521 void mc_dwarf_location_list_clear(mc_location_list_t list)
523 for (size_t i = 0; i != list->size; ++i) {
524 mc_dwarf_expression_clear(list->locations + i);
526 free(list->locations);
527 list->locations = NULL;
531 void mc_dwarf_expression_init(mc_expression_t expression, size_t len,
534 expression->lowpc = NULL;
535 expression->highpc = NULL;
536 expression->size = len;
537 expression->ops = xbt_malloc(len * sizeof(Dwarf_Op));
538 memcpy(expression->ops, ops, len * sizeof(Dwarf_Op));
541 void mc_dwarf_location_list_init_from_expression(mc_location_list_t target,
542 size_t len, Dwarf_Op * ops)
545 target->locations = (mc_expression_t) xbt_malloc(sizeof(s_mc_expression_t));
546 mc_dwarf_expression_init(target->locations, len, ops);
549 void mc_dwarf_location_list_init(mc_location_list_t list, mc_object_info_t info,
550 Dwarf_Die * die, Dwarf_Attribute * attr)
552 if (list->locations) {
553 mc_dwarf_location_list_clear(list);
557 ptrdiff_t offset = 0;
558 Dwarf_Addr base, start, end;
564 offset = dwarf_getlocations(attr, offset, &base, &start, &end, &ops, &len);
567 else if (offset == -1)
568 xbt_die("Error while loading location list");
573 (mc_expression_t) realloc(list->locations,
574 list->size * sizeof(s_mc_expression_t));
575 mc_expression_t expression = list->locations + i;
576 expression->ops = NULL;
577 mc_dwarf_expression_init(expression, len, ops);
581 flags & MC_OBJECT_INFO_EXECUTABLE ? 0 : MC_object_base_address(info);
582 // If start == 0, this is not a location list:
583 expression->lowpc = start == 0 ? NULL : (char *) base + start;
584 expression->highpc = start == 0 ? NULL : (char *) base + end;