1 /* Copyright (c) 2008-2020. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/simgrid/util.hpp"
8 #include "xbt/string.hpp"
9 #include "xbt/sysdep.h"
10 #include <simgrid/config.h>
12 #include "src/mc/inspect/ObjectInformation.hpp"
13 #include "src/mc/inspect/Variable.hpp"
14 #include "src/mc/inspect/mc_dwarf.hpp"
15 #include "src/mc/mc_private.hpp"
16 #include "src/mc/remote/RemoteSimulation.hpp"
25 #include <boost/range/algorithm.hpp>
27 #include <elfutils/libdw.h>
29 #include <boost/algorithm/string/predicate.hpp>
31 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dwarf, mc, "DWARF processing");
33 /** @brief The default DW_TAG_lower_bound for a given DW_AT_language.
35 * The default for a given language is defined in the DWARF spec.
37 * @param language constant as defined by the DWARf spec
39 static uint64_t MC_dwarf_default_lower_bound(int lang);
41 /** @brief Computes the the element_count of a DW_TAG_enumeration_type DIE
43 * This is the number of elements in a given array dimension.
45 * A reference of the compilation unit (DW_TAG_compile_unit) is
46 * needed because the default lower bound (when there is no DW_AT_lower_bound)
47 * depends of the language of the compilation unit (DW_AT_language).
49 * @param die DIE for the DW_TAG_enumeration_type or DW_TAG_subrange_type
50 * @param unit DIE of the DW_TAG_compile_unit
52 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit);
54 /** @brief Computes the number of elements of a given DW_TAG_array_type.
56 * @param die DIE for the DW_TAG_array_type
58 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit);
60 /** @brief Process a DIE
62 * @param info the resulting object for the library/binary file (output)
63 * @param die the current DIE
64 * @param unit the DIE of the compile unit of the current DIE
65 * @param frame containing frame if any
67 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
68 simgrid::mc::Frame* frame, const char* ns);
70 /** @brief Process a type DIE
72 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
73 simgrid::mc::Frame* frame, const char* ns);
75 /** @brief Calls MC_dwarf_handle_die on all children of the given die
77 * @param info the resulting object for the library/binary file (output)
78 * @param die the current DIE
79 * @param unit the DIE of the compile unit of the current DIE
80 * @param frame containing frame if any
82 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
83 simgrid::mc::Frame* frame, const char* ns);
85 /** @brief Handle a variable (DW_TAG_variable or other)
87 * @param info the resulting object for the library/binary file (output)
88 * @param die the current DIE
89 * @param unit the DIE of the compile unit of the current DIE
90 * @param frame containing frame if any
92 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, const Dwarf_Die* unit,
93 simgrid::mc::Frame* frame, const char* ns);
95 /** @brief Get the DW_TAG_type of the DIE
98 * @return DW_TAG_type attribute as a new string (nullptr if none)
100 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die);
105 enum class TagClass { Unknown, Type, Subprogram, Variable, Scope, Namespace };
107 /*** Class of forms defined in the DWARF standard */
108 enum class FormClass {
110 Address, // Location in the program's address space
111 Block, // Arbitrary block of bytes
114 Flag, // Boolean value
115 Reference, // Reference to another DIE
116 ExprLoc, // DWARF expression/location description
123 static TagClass classify_tag(int tag)
126 case DW_TAG_array_type:
127 case DW_TAG_class_type:
128 case DW_TAG_enumeration_type:
130 case DW_TAG_pointer_type:
131 case DW_TAG_reference_type:
132 case DW_TAG_rvalue_reference_type:
133 case DW_TAG_string_type:
134 case DW_TAG_structure_type:
135 case DW_TAG_subroutine_type:
136 case DW_TAG_union_type:
137 case DW_TAG_ptr_to_member_type:
138 case DW_TAG_set_type:
139 case DW_TAG_subrange_type:
140 case DW_TAG_base_type:
141 case DW_TAG_const_type:
142 case DW_TAG_file_type:
143 case DW_TAG_packed_type:
144 case DW_TAG_volatile_type:
145 case DW_TAG_restrict_type:
146 case DW_TAG_interface_type:
147 case DW_TAG_unspecified_type:
148 case DW_TAG_shared_type:
149 return TagClass::Type;
151 case DW_TAG_subprogram:
152 return TagClass::Subprogram;
154 case DW_TAG_variable:
155 case DW_TAG_formal_parameter:
156 return TagClass::Variable;
158 case DW_TAG_lexical_block:
159 case DW_TAG_try_block:
160 case DW_TAG_catch_block:
161 case DW_TAG_inlined_subroutine:
162 case DW_TAG_with_stmt:
163 return TagClass::Scope;
165 case DW_TAG_namespace:
166 return TagClass::Namespace;
169 return TagClass::Unknown;
173 /** @brief Find the DWARF data class for a given DWARF data form
175 * This mapping is defined in the DWARF spec.
177 * @param form The form (values taken from the DWARF spec)
178 * @return An internal representation for the corresponding class
180 static FormClass classify_form(int form)
184 return FormClass::Address;
189 return FormClass::Block;
196 return FormClass::Constant;
199 return FormClass::String;
200 case DW_FORM_ref_addr:
205 case DW_FORM_ref_udata:
206 return FormClass::Reference;
208 case DW_FORM_flag_present:
209 return FormClass::Flag;
210 case DW_FORM_exprloc:
211 return FormClass::ExprLoc;
215 return FormClass::Unknown;
219 /** @brief Get the name of the tag of a given DIE
222 * @return name of the tag of this DIE
224 inline XBT_PRIVATE const char* tagname(Dwarf_Die* die)
226 return tagname(dwarf_tag(die));
230 } // namespace simgrid
234 /** @brief Get an attribute of a given DIE as a string
237 * @param attribute attribute
238 * @return value of the given attribute of the given DIE
240 static const char* MC_dwarf_attr_integrate_string(Dwarf_Die* die, int attribute)
242 Dwarf_Attribute attr;
243 if (not dwarf_attr_integrate(die, attribute, &attr))
246 return dwarf_formstring(&attr);
249 static Dwarf_Off MC_dwarf_attr_dieoffset(Dwarf_Die* die, int attribute)
251 Dwarf_Attribute attr;
252 if (dwarf_hasattr_integrate(die, attribute) == 0)
254 dwarf_attr_integrate(die, attribute, &attr);
255 Dwarf_Die subtype_die;
256 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
257 return dwarf_dieoffset(&subtype_die);
260 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die* die, int attribute)
262 Dwarf_Attribute attr;
263 if (dwarf_hasattr_integrate(die, attribute) == 0)
265 dwarf_attr_integrate(die, DW_AT_type, &attr);
266 Dwarf_Die subtype_die;
267 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
268 return dwarf_dieoffset(&subtype_die);
271 /** @brief Find the type/subtype (DW_AT_type) for a DIE
274 * @return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
276 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die)
278 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
281 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die* die, int attribute)
283 Dwarf_Attribute attr;
284 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
287 if (dwarf_formaddr(&attr, &value) == 0)
288 return (uint64_t)value;
293 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die* die, int attribute, uint64_t default_value)
295 Dwarf_Attribute attr;
296 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
297 return default_value;
299 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t)value : default_value;
302 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, bool integrate)
304 Dwarf_Attribute attr;
305 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr) : dwarf_attr(die, attribute, &attr)) == nullptr)
309 xbt_assert(not dwarf_formflag(&attr, &result), "Unexpected form for attribute %s",
310 simgrid::dwarf::attrname(attribute));
314 /** @brief Find the default lower bound for a given language
316 * The default lower bound of an array (when DW_TAG_lower_bound
317 * is missing) depends on the language of the compilation unit.
319 * @param lang Language of the compilation unit (values defined in the DWARF spec)
320 * @return Default lower bound of an array in this compilation unit
322 static uint64_t MC_dwarf_default_lower_bound(int lang)
328 case DW_LANG_C_plus_plus:
332 case DW_LANG_ObjC_plus_plus:
338 case DW_LANG_Fortran77:
339 case DW_LANG_Fortran90:
340 case DW_LANG_Fortran95:
341 case DW_LANG_Modula2:
342 case DW_LANG_Pascal83:
344 case DW_LANG_Cobol74:
345 case DW_LANG_Cobol85:
348 xbt_die("No default DW_TAG_lower_bound for language %i and none given", lang);
353 /** @brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
356 * @param unit DIE of the compilation unit
357 * @return number of elements in the range
359 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit)
361 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type || dwarf_tag(die) == DW_TAG_subrange_type,
362 "MC_dwarf_subrange_element_count called with DIE of type %s", simgrid::dwarf::tagname(die));
364 // Use DW_TAG_count if present:
365 if (dwarf_hasattr_integrate(die, DW_AT_count))
366 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
367 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
369 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
370 // This is not really 0, but the code expects this (we do not know):
373 uint64_t upper_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, static_cast<uint64_t>(-1));
375 uint64_t lower_bound = 0;
376 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
377 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, static_cast<uint64_t>(-1));
379 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
380 return upper_bound - lower_bound + 1;
383 /** @brief Finds the number of elements in an array type (DW_TAG_array_type)
385 * The compilation unit might be needed because the default lower
386 * bound depends on the language of the compilation unit.
388 * @param die the DIE of the DW_TAG_array_type
389 * @param unit the DIE of the compilation unit
390 * @return number of elements in this array type
392 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit)
394 xbt_assert(dwarf_tag(die) == DW_TAG_array_type, "MC_dwarf_array_element_count called with DIE of type %s",
395 simgrid::dwarf::tagname(die));
399 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
400 int child_tag = dwarf_tag(&child);
401 if (child_tag == DW_TAG_subrange_type || child_tag == DW_TAG_enumeration_type)
402 result *= MC_dwarf_subrange_element_count(&child, unit);
409 /** Sort the variable by name and address.
411 * We could use boost::container::flat_set instead.
413 static bool MC_compare_variable(simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
415 int cmp = a.name.compare(b.name);
421 return a.address < b.address;
424 // ***** simgrid::mc::Type*
426 /** @brief Initialize the location of a member of a type
427 * (DW_AT_data_member_location of a DW_TAG_member).
429 * @param type a type (struct, class)
430 * @param member the member of the type
431 * @param child DIE of the member (DW_TAG_member)
433 static void MC_dwarf_fill_member_location(const simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die* child)
435 xbt_assert(not dwarf_hasattr(child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
437 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
438 if (type->type == DW_TAG_union_type)
440 xbt_die("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%" PRIx64 ">%s",
441 member->name.c_str(), (uint64_t)type->id, type->name.c_str());
444 Dwarf_Attribute attr;
445 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
446 int form = dwarf_whatform(&attr);
447 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
448 switch (form_class) {
449 case simgrid::dwarf::FormClass::ExprLoc:
450 case simgrid::dwarf::FormClass::Block:
451 // Location expression:
455 xbt_assert(not dwarf_getlocation(&attr, &expr, &len),
456 "Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%" PRIx64
458 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
459 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr + len);
462 case simgrid::dwarf::FormClass::Constant:
463 // Offset from the base address of the object:
466 xbt_assert(not dwarf_formudata(&attr, &offset), "Cannot get %s location <%" PRIx64 ">%s",
467 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
468 member->offset(offset);
473 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to
474 // be possible in DWARF2 but I couldn't find its semantic in the spec)
475 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
479 /** @brief Populate the list of members of a type
481 * @param info ELF object containing the type DIE
482 * @param die DIE of the type
483 * @param unit DIE of the compilation unit containing the type DIE
484 * @param type the type
486 static void MC_dwarf_add_members(const simgrid::mc::ObjectInformation* /*info*/, Dwarf_Die* die,
487 const Dwarf_Die* /*unit*/, simgrid::mc::Type* type)
490 xbt_assert(type->members.empty());
491 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
492 int tag = dwarf_tag(&child);
493 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
494 // Skip declarations:
495 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
498 // Skip compile time constants:
499 if (dwarf_hasattr(&child, DW_AT_const_value))
502 // TODO, we should use another type (because is is not a type but a member)
503 simgrid::mc::Member member;
504 if (tag == DW_TAG_inheritance)
505 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
507 const char* name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
510 // Those base names are used by GCC and clang for virtual table pointers
511 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
512 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
513 boost::algorithm::starts_with(member.name, "__vptr."))
514 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
515 // A cleaner solution would be to check against the type:
517 // tag: DW_TAG_member
520 // # Type for a pointer to a vtable
521 // tag: DW_TAG_pointer_type
523 // # Type for a vtable:
524 // tag: DW_TAG_pointer_type
525 // name: "__vtbl_ptr_type"
527 // tag: DW_TAG_subroutine_type
529 // tag: DW_TAG_base_type
533 member.byte_size = MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
534 member.type_id = MC_dwarf_at_type(&child);
536 xbt_assert(not dwarf_hasattr(&child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
538 MC_dwarf_fill_member_location(type, &member, &child);
540 xbt_assert(member.type_id, "Missing type for member %s of <%" PRIx64 ">%s", member.name.c_str(),
541 (uint64_t)type->id, type->name.c_str());
543 type->members.push_back(std::move(member));
548 /** @brief Create a MC type object from a DIE
550 * @param info current object info object
551 * @param die DIE (for a given type)
552 * @param unit compilation unit of the current DIE
553 * @return MC representation of the type
555 static simgrid::mc::Type MC_dwarf_die_to_type(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
556 simgrid::mc::Frame* frame, const char* ns)
558 simgrid::mc::Type type;
559 type.type = dwarf_tag(die);
560 type.name = std::string();
561 type.element_count = -1;
564 type.id = dwarf_dieoffset(die);
566 const char* prefix = "";
568 case DW_TAG_structure_type:
571 case DW_TAG_union_type:
574 case DW_TAG_class_type:
581 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
582 if (name != nullptr) {
584 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
586 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
589 type.type_id = MC_dwarf_at_type(die);
591 // Some compilers do not emit DW_AT_byte_size for pointer_type,
592 // so we fill this. We currently assume that the model-checked process is in
593 // the same architecture..
594 if (type.type == DW_TAG_pointer_type)
595 type.byte_size = sizeof(void*);
597 // Computation of the byte_size
598 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
599 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
600 else if (type.type == DW_TAG_array_type || type.type == DW_TAG_structure_type || type.type == DW_TAG_class_type) {
602 if (dwarf_aggregate_size(die, &size) == 0)
603 type.byte_size = size;
607 case DW_TAG_array_type:
608 type.element_count = MC_dwarf_array_element_count(die, unit);
609 // TODO, handle DW_byte_stride and (not) DW_bit_stride
612 case DW_TAG_pointer_type:
613 case DW_TAG_reference_type:
614 case DW_TAG_rvalue_reference_type:
617 case DW_TAG_structure_type:
618 case DW_TAG_union_type:
619 case DW_TAG_class_type:
620 MC_dwarf_add_members(info, die, unit, &type);
621 MC_dwarf_handle_children(info, die, unit, frame,
622 ns ? simgrid::xbt::string_printf("%s::%s", ns, name).c_str() : type.name.c_str());
626 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
633 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
634 simgrid::mc::Frame* frame, const char* ns)
636 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
637 auto& t = (info->types[type.id] = std::move(type));
638 if (not t.name.empty() && type.byte_size != 0)
639 info->full_types_by_name[t.name] = &t;
642 static int mc_anonymous_variable_index = 0;
644 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(simgrid::mc::ObjectInformation* info, Dwarf_Die* die,
645 const Dwarf_Die* /*unit*/,
646 const simgrid::mc::Frame* frame, const char* ns)
648 // Skip declarations:
649 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
652 // Skip compile time constants:
653 if (dwarf_hasattr(die, DW_AT_const_value))
656 Dwarf_Attribute attr_location;
657 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
658 // No location: do not add it ?
661 auto variable = std::make_unique<simgrid::mc::Variable>();
662 variable->id = dwarf_dieoffset(die);
663 variable->global = frame == nullptr; // Can be override base on DW_AT_location
664 variable->object_info = info;
666 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
668 variable->name = name;
669 variable->type_id = MC_dwarf_at_type(die);
671 int form = dwarf_whatform(&attr_location);
672 simgrid::dwarf::FormClass form_class;
673 if (form == DW_FORM_sec_offset)
674 form_class = simgrid::dwarf::FormClass::Constant;
676 form_class = simgrid::dwarf::classify_form(form);
677 switch (form_class) {
678 case simgrid::dwarf::FormClass::ExprLoc:
679 case simgrid::dwarf::FormClass::Block:
680 // Location expression:
684 xbt_assert(not dwarf_getlocation(&attr_location, &expr, &len),
685 "Could not read location expression in DW_AT_location "
686 "of variable <%" PRIx64 ">%s",
687 (uint64_t)variable->id, variable->name.c_str());
689 if (len == 1 && expr[0].atom == DW_OP_addr) {
690 variable->global = true;
691 auto offset = static_cast<uintptr_t>(expr[0].number);
692 auto base = reinterpret_cast<uintptr_t>(info->base_address());
693 variable->address = reinterpret_cast<void*>(base + offset);
695 variable->location_list = {
696 simgrid::dwarf::LocationListEntry(simgrid::dwarf::DwarfExpression(expr, expr + len))};
701 case simgrid::dwarf::FormClass::LocListPtr:
702 case simgrid::dwarf::FormClass::Constant:
703 // Reference to location list:
704 variable->location_list = simgrid::dwarf::location_list(*info, attr_location);
708 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
709 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
712 // Handle start_scope:
713 if (dwarf_hasattr(die, DW_AT_start_scope)) {
714 Dwarf_Attribute attr;
715 dwarf_attr(die, DW_AT_start_scope, &attr);
716 form = dwarf_whatform(&attr);
717 form_class = simgrid::dwarf::classify_form(form);
718 if (form_class == simgrid::dwarf::FormClass::Constant) {
720 variable->start_scope = dwarf_formudata(&attr, &value) == 0 ? (size_t)value : 0;
722 // TODO: FormClass::RangeListPtr
723 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
724 (unsigned)form_class, name == nullptr ? "?" : name);
728 if (ns && variable->global)
729 variable->name = std::string(ns) + "::" + variable->name;
731 // The current code needs a variable name,
732 // generate a fake one:
733 if (variable->name.empty()) {
734 variable->name = "@anonymous#" + std::to_string(mc_anonymous_variable_index);
735 mc_anonymous_variable_index++;
740 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, const Dwarf_Die* unit,
741 simgrid::mc::Frame* frame, const char* ns)
743 std::unique_ptr<simgrid::mc::Variable> variable = MC_die_to_variable(info, die, unit, frame, ns);
746 // Those arrays are sorted later:
747 if (variable->global)
748 info->global_variables.push_back(std::move(*variable));
749 else if (frame != nullptr)
750 frame->variables.push_back(std::move(*variable));
752 xbt_die("No frame for this local variable");
755 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
756 simgrid::mc::Frame* parent_frame, const char* ns)
758 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
759 int tag = dwarf_tag(die);
760 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
762 // (Template) Subprogram declaration:
763 if (klass == simgrid::dwarf::TagClass::Subprogram && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
766 if (klass == simgrid::dwarf::TagClass::Scope)
767 xbt_assert(parent_frame, "No parent scope for this scope");
769 simgrid::mc::Frame frame;
771 frame.id = dwarf_dieoffset(die);
772 frame.object_info = info;
774 if (klass == simgrid::dwarf::TagClass::Subprogram) {
775 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
777 frame.name = std::string(ns) + "::" + name;
782 frame.abstract_origin_id = MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
784 // This is the base address for DWARF addresses.
785 // Relocated addresses are offset from this base address.
786 // See DWARF4 spec 7.5
787 auto base = reinterpret_cast<std::uint64_t>(info->base_address());
789 // TODO, support DW_AT_ranges
790 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
791 frame.range.begin() = low_pc ? base + low_pc : 0;
794 Dwarf_Attribute attr;
795 xbt_assert(dwarf_attr_integrate(die, DW_AT_high_pc, &attr), "Missing DW_AT_high_pc matching with DW_AT_low_pc");
800 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
801 // DW_AT_high_pc if an offset from the low_pc:
802 case simgrid::dwarf::FormClass::Constant:
804 xbt_assert(dwarf_formsdata(&attr, &offset) == 0, "Could not read constant");
805 frame.range.end() = frame.range.begin() + offset;
808 // DW_AT_high_pc is a relocatable address:
809 case simgrid::dwarf::FormClass::Address:
810 xbt_assert(dwarf_formaddr(&attr, &high_pc) == 0, "Could not read address");
811 frame.range.end() = base + high_pc;
815 xbt_die("Unexpected class for DW_AT_high_pc");
819 if (klass == simgrid::dwarf::TagClass::Subprogram) {
820 Dwarf_Attribute attr_frame_base;
821 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
822 frame.frame_base_location = simgrid::dwarf::location_list(*info, attr_frame_base);
826 MC_dwarf_handle_children(info, die, unit, &frame, ns);
828 // We sort them in order to have an (somewhat) efficient by name
830 boost::range::sort(frame.variables, MC_compare_variable);
833 if (klass == simgrid::dwarf::TagClass::Subprogram)
834 info->subprograms[frame.id] = std::move(frame);
835 else if (klass == simgrid::dwarf::TagClass::Scope)
836 parent_frame->scopes.push_back(std::move(frame));
839 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
840 simgrid::mc::Frame* frame, const char* ns)
842 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
843 xbt_assert(not frame, "Unexpected namespace in a subprogram");
844 char* new_ns = ns == nullptr ? xbt_strdup(name) : bprintf("%s::%s", ns, name);
845 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
849 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
850 simgrid::mc::Frame* frame, const char* ns)
852 // For each child DIE:
854 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child))
855 MC_dwarf_handle_die(info, &child, unit, frame, ns);
858 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
859 simgrid::mc::Frame* frame, const char* ns)
861 int tag = dwarf_tag(die);
862 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
865 case simgrid::dwarf::TagClass::Type:
866 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
869 // Subprogram or scope:
870 case simgrid::dwarf::TagClass::Subprogram:
871 case simgrid::dwarf::TagClass::Scope:
872 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
876 case simgrid::dwarf::TagClass::Variable:
877 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
880 case simgrid::dwarf::TagClass::Namespace:
881 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
889 static Elf64_Half get_type(Elf* elf)
891 const Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
893 return ehdr64->e_type;
894 const Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
896 return ehdr32->e_type;
897 xbt_die("Could not get ELF heeader");
900 static void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
902 // For each compilation unit:
903 Dwarf_Off offset = 0;
904 Dwarf_Off next_offset = 0;
907 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) == 0) {
909 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
910 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
911 offset = next_offset;
915 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
917 * This build-id may is used to locate an external debug (DWARF) file
920 * @param elf libelf handle for an ELF file
921 * @return build-id for this ELF file (or an empty vector if none is found)
923 static std::vector<char> get_build_id(Elf* elf)
926 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
927 // found in a PT_NOTE entry in the program header table.
930 xbt_assert(elf_getphdrnum(elf, &phnum) == 0, "Could not read program headers");
932 // Iterate over the program headers and find the PT_NOTE ones:
933 for (size_t i = 0; i < phnum; ++i) {
935 const GElf_Phdr* phdr = gelf_getphdr(elf, i, &phdr_temp);
936 if (phdr->p_type != PT_NOTE)
939 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
941 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
943 while (pos < data->d_size) {
945 // Location of the name within Elf_Data:
948 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
949 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
950 // (a namespace and a type within this namespace):
951 if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU") &&
952 memcmp((char*)data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
953 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
954 char* start = (char*)data->d_buf + desc_pos;
955 char* end = start + nhdr.n_descsz;
956 return std::vector<char>(start, end);
961 return std::vector<char>();
964 static char hexdigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
966 /** Binary data to hexadecimal */
967 static inline std::array<char, 2> to_hex(std::uint8_t byte)
969 // Horrid double braces!
970 // Apparently, this is needed in C++11 (not in C++14).
971 return {{hexdigits[byte >> 4], hexdigits[byte & 0xF]}};
974 /** Binary data to hexadecimal */
975 static std::string to_hex(const char* data, std::size_t count)
978 res.resize(2 * count);
979 for (std::size_t i = 0; i < count; i++) {
980 std::array<char, 2> hex_byte = to_hex(data[i]);
981 for (int j = 0; j < 2; ++j)
982 res[2 * i + j] = hex_byte[j];
987 /** Binary data to hexadecimal */
988 static std::string to_hex(std::vector<char> const& data)
990 return to_hex(data.data(), data.size());
993 /** Base directories for external debug files */
994 static constexpr auto debug_paths = {
996 "/usr/local/lib/debug/",
999 /** Locate an external debug file from the NT_GNU_BUILD_ID
1001 * This is one of the mechanisms used for
1002 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
1005 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
1006 static std::string find_by_build_id(std::vector<char> id)
1008 std::string filename;
1009 std::string hex = to_hex(id);
1010 for (const char* const& debug_path : debug_paths) {
1012 filename = std::string(debug_path) + ".build-id/" + to_hex(id.data(), 1) + '/' +
1013 to_hex(id.data() + 1, id.size() - 1) + ".debug";
1014 XBT_DEBUG("Checking debug file: %s", filename.c_str());
1015 if (access(filename.c_str(), F_OK) == 0) {
1016 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
1020 XBT_DEBUG("No debug info found for build ID %s\n", hex.data());
1021 return std::string();
1024 /** @brief Populate the debugging information of the given ELF object
1026 * Read the DWARf information of the EFFL object and populate the
1027 * lists of types, variables, functions.
1029 static void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
1031 xbt_assert(elf_version(EV_CURRENT) != EV_NONE, "libelf initialization error");
1033 // Open the ELF file:
1034 int fd = open(info->file_name.c_str(), O_RDONLY);
1035 xbt_assert(fd >= 0, "Could not open file %s", info->file_name.c_str());
1036 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
1037 xbt_assert(elf != nullptr, "Not an ELF file");
1038 Elf_Kind kind = elf_kind(elf);
1039 xbt_assert(kind == ELF_K_ELF, "Not an ELF file");
1041 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
1042 Elf64_Half type = get_type(elf);
1043 if (type == ET_EXEC)
1044 info->flags |= simgrid::mc::ObjectInformation::Executable;
1046 // Read DWARF debug information in the file:
1047 Dwarf* dwarf = dwarf_begin_elf(elf, DWARF_C_READ, nullptr);
1048 if (dwarf != nullptr) {
1049 read_dwarf_info(info, dwarf);
1057 // If there was no DWARF in the file, try to find it in a separate file.
1058 // Different methods might be used to store the DWARF information:
1059 // * GNU NT_GNU_BUILD_ID
1061 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1062 // for reference of what we are doing.
1064 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1065 // use this ID to find the file in some known locations in the filesystem.
1066 std::vector<char> build_id = get_build_id(elf);
1067 if (not build_id.empty()) {
1071 // Find the debug file using the build id:
1072 std::string debug_file = find_by_build_id(build_id);
1073 xbt_assert(not debug_file.empty(),
1074 "Missing debug info for %s with build-id %s\n"
1075 "You might want to install the suitable debugging package.\n",
1076 info->file_name.c_str(), to_hex(build_id).c_str());
1078 // Load the DWARF info from this file:
1079 XBT_DEBUG("Load DWARF for %s from %s", info->file_name.c_str(), debug_file.c_str());
1080 fd = open(debug_file.c_str(), O_RDONLY);
1081 xbt_assert(fd >= 0, "Could not open file %s", debug_file.c_str());
1082 dwarf = dwarf_begin(fd, DWARF_C_READ);
1083 xbt_assert(dwarf != nullptr, "No DWARF info in %s for %s", debug_file.c_str(), info->file_name.c_str());
1084 read_dwarf_info(info, dwarf);
1090 // TODO, try to find DWARF info using .gnu_debuglink.
1094 xbt_die("Debugging information not found for %s\n"
1095 "Try recompiling with -g\n",
1096 info->file_name.c_str());
1099 // ***** Functions index
1101 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1103 info->functions_index.clear();
1105 for (auto& e : info->subprograms) {
1106 if (e.second.range.begin() == 0)
1108 simgrid::mc::FunctionIndexEntry entry;
1109 entry.low_pc = (void*)e.second.range.begin();
1110 entry.function = &e.second;
1111 info->functions_index.push_back(entry);
1114 info->functions_index.shrink_to_fit();
1116 // Sort the array by low_pc:
1117 boost::range::sort(info->functions_index,
1118 [](simgrid::mc::FunctionIndexEntry const& a, simgrid::mc::FunctionIndexEntry const& b) {
1119 return a.low_pc < b.low_pc;
1123 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1125 // Someone needs this to be sorted but who?
1126 boost::range::sort(info->global_variables, MC_compare_variable);
1128 for (simgrid::mc::Variable& variable : info->global_variables)
1129 if (variable.type_id)
1130 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1133 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1135 if (scope->tag == DW_TAG_inlined_subroutine) {
1136 // Attach correct namespaced name in inlined subroutine:
1137 auto i = info->subprograms.find(scope->abstract_origin_id);
1138 xbt_assert(i != info->subprograms.end(), "Could not lookup abstract origin %" PRIx64,
1139 (std::uint64_t)scope->abstract_origin_id);
1140 scope->name = i->second.name;
1144 for (simgrid::mc::Variable& variable : scope->variables)
1145 if (variable.type_id)
1146 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1148 // Recursive post-processing of nested-scopes:
1149 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1150 mc_post_process_scope(info, &nested_scope);
1153 static simgrid::mc::Type* MC_resolve_type(simgrid::mc::ObjectInformation* info, unsigned type_id)
1157 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1158 if (type == nullptr)
1161 // We already have the information on the type:
1162 if (type->byte_size != 0)
1165 // Don't have a name, we can't find a more complete version:
1166 if (type->name.empty())
1169 // Try to find a more complete description of the type:
1170 // We need to fix in order to support C++.
1171 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(info->full_types_by_name, type->name);
1177 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1179 // Lookup "subtype" field:
1180 for (auto& i : info->types) {
1181 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1182 for (simgrid::mc::Member& member : i.second.members)
1183 member.type = MC_resolve_type(info, member.type_id);
1190 /** @brief Finds information about a given shared object/executable */
1191 std::shared_ptr<ObjectInformation> createObjectInformation(std::vector<xbt::VmMap> const& maps, const char* name)
1193 auto result = std::make_shared<ObjectInformation>();
1194 result->file_name = name;
1195 simgrid::mc::find_object_address(maps, result.get());
1196 MC_load_dwarf(result.get());
1197 MC_post_process_variables(result.get());
1198 MC_post_process_types(result.get());
1199 for (auto& entry : result.get()->subprograms)
1200 mc_post_process_scope(result.get(), &entry.second);
1201 MC_make_functions_index(result.get());
1205 /*************************************************************************/
1207 void postProcessObjectInformation(const RemoteSimulation* process, ObjectInformation* info)
1209 for (auto& t : info->types) {
1210 Type* type = &(t.second);
1211 Type* subtype = type;
1212 while (subtype->type == DW_TAG_typedef || subtype->type == DW_TAG_volatile_type ||
1213 subtype->type == DW_TAG_const_type)
1214 if (subtype->subtype)
1215 subtype = subtype->subtype;
1219 // Resolve full_type:
1220 if (not subtype->name.empty() && subtype->byte_size == 0)
1221 for (auto const& object_info : process->object_infos) {
1222 auto i = object_info->full_types_by_name.find(subtype->name);
1223 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1224 type->full_type = i->second;
1229 type->full_type = subtype;
1234 } // namespace simgrid
1239 /** Convert a DWARF register into a libunwind register
1241 * DWARF and libunwind does not use the same convention for numbering the
1242 * registers on some architectures. The function makes the necessary
1245 int dwarf_register_to_libunwind(int dwarf_register)
1247 #if defined(__x86_64__)
1248 // It seems for this arch, DWARF and libunwind agree in the numbering:
1249 return dwarf_register;
1250 #elif defined(__i386__)
1251 // Couldn't find the authoritative source of information for this.
1252 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1253 switch (dwarf_register) {
1273 return UNW_X86_EFLAGS;
1303 xbt_die("Bad/unknown register number.");
1306 #error This architecture is not supported yet for DWARF expression evaluation.
1310 } // namespace dwarf
1311 } // namespace simgrid