1 /* Copyright (c) 2008-2019. 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/RemoteClient.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 fot 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 fot 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 fot 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, 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)
127 case DW_TAG_array_type:
128 case DW_TAG_class_type:
129 case DW_TAG_enumeration_type:
131 case DW_TAG_pointer_type:
132 case DW_TAG_reference_type:
133 case DW_TAG_rvalue_reference_type:
134 case DW_TAG_string_type:
135 case DW_TAG_structure_type:
136 case DW_TAG_subroutine_type:
137 case DW_TAG_union_type:
138 case DW_TAG_ptr_to_member_type:
139 case DW_TAG_set_type:
140 case DW_TAG_subrange_type:
141 case DW_TAG_base_type:
142 case DW_TAG_const_type:
143 case DW_TAG_file_type:
144 case DW_TAG_packed_type:
145 case DW_TAG_volatile_type:
146 case DW_TAG_restrict_type:
147 case DW_TAG_interface_type:
148 case DW_TAG_unspecified_type:
149 case DW_TAG_shared_type:
150 return TagClass::Type;
152 case DW_TAG_subprogram:
153 return TagClass::Subprogram;
155 case DW_TAG_variable:
156 case DW_TAG_formal_parameter:
157 return TagClass::Variable;
159 case DW_TAG_lexical_block:
160 case DW_TAG_try_block:
161 case DW_TAG_catch_block:
162 case DW_TAG_inlined_subroutine:
163 case DW_TAG_with_stmt:
164 return TagClass::Scope;
166 case DW_TAG_namespace:
167 return TagClass::Namespace;
170 return TagClass::Unknown;
174 /** @brief Find the DWARF data class for a given DWARF data form
176 * This mapping is defined in the DWARF spec.
178 * @param form The form (values taken from the DWARF spec)
179 * @return An internal representation for the corresponding class
181 static FormClass classify_form(int form)
185 return FormClass::Address;
190 return FormClass::Block;
197 return FormClass::Constant;
200 return FormClass::String;
201 case DW_FORM_ref_addr:
206 case DW_FORM_ref_udata:
207 return FormClass::Reference;
209 case DW_FORM_flag_present:
210 return FormClass::Flag;
211 case DW_FORM_exprloc:
212 return FormClass::ExprLoc;
216 return FormClass::Unknown;
220 /** @brief Get the name of the tag of a given DIE
223 * @return name of the tag of this DIE
225 inline XBT_PRIVATE const char* tagname(Dwarf_Die* die)
227 return simgrid::dwarf::tagname(dwarf_tag(die));
231 } // namespace simgrid
235 /** @brief Get an attribute of a given DIE as a string
238 * @param attribute attribute
239 * @return value of the given attribute of the given DIE
241 static const char* MC_dwarf_attr_integrate_string(Dwarf_Die* die, int attribute)
243 Dwarf_Attribute attr;
244 if (not dwarf_attr_integrate(die, attribute, &attr))
247 return dwarf_formstring(&attr);
250 static Dwarf_Off MC_dwarf_attr_dieoffset(Dwarf_Die* die, int attribute)
252 Dwarf_Attribute attr;
253 if (dwarf_hasattr_integrate(die, attribute) == 0)
255 dwarf_attr_integrate(die, attribute, &attr);
256 Dwarf_Die subtype_die;
257 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
258 xbt_die("Could not find DIE");
259 return dwarf_dieoffset(&subtype_die);
262 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die* die, int attribute)
264 Dwarf_Attribute attr;
265 if (dwarf_hasattr_integrate(die, attribute) == 0)
267 dwarf_attr_integrate(die, DW_AT_type, &attr);
268 Dwarf_Die subtype_die;
269 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
270 xbt_die("Could not find DIE");
271 return dwarf_dieoffset(&subtype_die);
274 /** @brief Find the type/subtype (DW_AT_type) for a DIE
277 * @return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
279 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die)
281 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
284 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die* die, int attribute)
286 Dwarf_Attribute attr;
287 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
290 if (dwarf_formaddr(&attr, &value) == 0)
291 return (uint64_t)value;
296 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die* die, int attribute, uint64_t default_value)
298 Dwarf_Attribute attr;
299 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
300 return default_value;
302 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t)value : default_value;
305 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, bool integrate)
307 Dwarf_Attribute attr;
308 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr) : dwarf_attr(die, attribute, &attr)) == 0)
312 if (dwarf_formflag(&attr, &result))
313 xbt_die("Unexpected form for attribute %s", simgrid::dwarf::attrname(attribute));
317 /** @brief Find the default lower bound for a given language
319 * The default lower bound of an array (when DW_TAG_lower_bound
320 * is missing) depends on the language of the compilation unit.
322 * @param lang Language of the compilation unit (values defined in the DWARF spec)
323 * @return Default lower bound of an array in this compilation unit
325 static uint64_t MC_dwarf_default_lower_bound(int lang)
331 case DW_LANG_C_plus_plus:
335 case DW_LANG_ObjC_plus_plus:
341 case DW_LANG_Fortran77:
342 case DW_LANG_Fortran90:
343 case DW_LANG_Fortran95:
344 case DW_LANG_Modula2:
345 case DW_LANG_Pascal83:
347 case DW_LANG_Cobol74:
348 case DW_LANG_Cobol85:
351 xbt_die("No default DW_TAG_lower_bound for language %i and none given", lang);
356 /** @brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
359 * @param unit DIE of the compilation unit
360 * @return number of elements in the range
362 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit)
364 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type || dwarf_tag(die) == DW_TAG_subrange_type,
365 "MC_dwarf_subrange_element_count called with DIE of type %s", simgrid::dwarf::tagname(die));
367 // Use DW_TAG_count if present:
368 if (dwarf_hasattr_integrate(die, DW_AT_count))
369 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
370 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
372 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
373 // This is not really 0, but the code expects this (we do not know):
376 uint64_t upper_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, static_cast<uint64_t>(-1));
378 uint64_t lower_bound = 0;
379 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
380 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, static_cast<uint64_t>(-1));
382 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
383 return upper_bound - lower_bound + 1;
386 /** @brief Finds the number of elements in a array type (DW_TAG_array_type)
388 * The compilation unit might be needed because the default lower
389 * bound depends on the language of the compilation unit.
391 * @param die the DIE of the DW_TAG_array_type
392 * @param unit the DIE of the compilation unit
393 * @return number of elements in this array type
395 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit)
397 xbt_assert(dwarf_tag(die) == DW_TAG_array_type, "MC_dwarf_array_element_count called with DIE of type %s",
398 simgrid::dwarf::tagname(die));
403 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
404 int child_tag = dwarf_tag(&child);
405 if (child_tag == DW_TAG_subrange_type || child_tag == DW_TAG_enumeration_type)
406 result *= MC_dwarf_subrange_element_count(&child, unit);
413 /** Sort the variable by name and address.
415 * We could use boost::container::flat_set instead.
417 static bool MC_compare_variable(simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
419 int cmp = a.name.compare(b.name);
425 return a.address < b.address;
428 // ***** simgrid::mc::Type*
430 /** @brief Initialize the location of a member of a type
431 * (DW_AT_data_member_location of a DW_TAG_member).
433 * @param type a type (struct, class)
434 * @param member the member of the type
435 * @param child DIE of the member (DW_TAG_member)
437 static void MC_dwarf_fill_member_location(simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die* child)
439 if (dwarf_hasattr(child, DW_AT_data_bit_offset))
440 xbt_die("Can't groke DW_AT_data_bit_offset.");
442 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
443 if (type->type == DW_TAG_union_type)
445 xbt_die("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%" PRIx64 ">%s",
446 member->name.c_str(), (uint64_t)type->id, type->name.c_str());
449 Dwarf_Attribute attr;
450 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
451 int form = dwarf_whatform(&attr);
452 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
453 switch (form_class) {
454 case simgrid::dwarf::FormClass::ExprLoc:
455 case simgrid::dwarf::FormClass::Block:
456 // Location expression:
460 if (dwarf_getlocation(&attr, &expr, &len))
461 xbt_die("Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%" PRIx64
463 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
464 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr + len);
467 case simgrid::dwarf::FormClass::Constant:
468 // Offset from the base address of the object:
471 if (not dwarf_formudata(&attr, &offset))
472 member->offset(offset);
474 xbt_die("Cannot get %s location <%" PRIx64 ">%s", MC_dwarf_attr_integrate_string(child, DW_AT_name),
475 (uint64_t)type->id, type->name.c_str());
480 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to
481 // be possible in DWARF2 but I couldn't find its semantic in the spec)
482 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
486 /** @brief Populate the list of members of a type
488 * @param info ELF object containing the type DIE
489 * @param die DIE of the type
490 * @param unit DIE of the compilation unit containing the type DIE
491 * @param type the type
493 static void MC_dwarf_add_members(simgrid::mc::ObjectInformation* /*info*/, Dwarf_Die* die, Dwarf_Die* /*unit*/,
494 simgrid::mc::Type* type)
498 xbt_assert(type->members.empty());
499 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
500 int tag = dwarf_tag(&child);
501 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
503 // Skip declarations:
504 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
507 // Skip compile time constants:
508 if (dwarf_hasattr(&child, DW_AT_const_value))
511 // TODO, we should use another type (because is is not a type but a member)
512 simgrid::mc::Member member;
513 if (tag == DW_TAG_inheritance)
514 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
516 const char* name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
519 // Those base names are used by GCC and clang for virtual table pointers
520 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
521 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
522 boost::algorithm::starts_with(member.name, "__vptr."))
523 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
524 // A cleaner solution would be to check against the type:
526 // tag: DW_TAG_member
529 // # Type for a pointer to a vtable
530 // tag: DW_TAG_pointer_type
532 // # Type for a vtable:
533 // tag: DW_TAG_pointer_type
534 // name: "__vtbl_ptr_type"
536 // tag: DW_TAG_subroutine_type
538 // tag: DW_TAG_base_type
542 member.byte_size = MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
543 member.type_id = MC_dwarf_at_type(&child);
545 if (dwarf_hasattr(&child, DW_AT_data_bit_offset))
546 xbt_die("Can't groke DW_AT_data_bit_offset.");
548 MC_dwarf_fill_member_location(type, &member, &child);
550 if (not member.type_id)
551 xbt_die("Missing type for member %s of <%" PRIx64 ">%s", member.name.c_str(), (uint64_t)type->id,
554 type->members.push_back(std::move(member));
559 /** @brief Create a MC type object from a DIE
561 * @param info current object info object
562 * @param die DIE (for a given type)
563 * @param unit compilation unit of the current DIE
564 * @return MC representation of the type
566 static simgrid::mc::Type MC_dwarf_die_to_type(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
567 simgrid::mc::Frame* frame, const char* ns)
569 simgrid::mc::Type type;
570 type.type = dwarf_tag(die);
571 type.name = std::string();
572 type.element_count = -1;
575 type.id = dwarf_dieoffset(die);
577 const char* prefix = "";
579 case DW_TAG_structure_type:
582 case DW_TAG_union_type:
585 case DW_TAG_class_type:
592 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
593 if (name != nullptr) {
595 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
597 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
600 type.type_id = MC_dwarf_at_type(die);
602 // Some compilers do not emit DW_AT_byte_size for pointer_type,
603 // so we fill this. We currently assume that the model-checked process is in
604 // the same architecture..
605 if (type.type == DW_TAG_pointer_type)
606 type.byte_size = sizeof(void*);
608 // Computation of the byte_size
609 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
610 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
611 else if (type.type == DW_TAG_array_type || type.type == DW_TAG_structure_type || type.type == DW_TAG_class_type) {
613 if (dwarf_aggregate_size(die, &size) == 0)
614 type.byte_size = size;
618 case DW_TAG_array_type:
619 type.element_count = MC_dwarf_array_element_count(die, unit);
620 // TODO, handle DW_byte_stride and (not) DW_bit_stride
623 case DW_TAG_pointer_type:
624 case DW_TAG_reference_type:
625 case DW_TAG_rvalue_reference_type:
628 case DW_TAG_structure_type:
629 case DW_TAG_union_type:
630 case DW_TAG_class_type:
631 MC_dwarf_add_members(info, die, unit, &type);
632 MC_dwarf_handle_children(info, die, unit, frame,
633 ns ? simgrid::xbt::string_printf("%s::%s", ns, name).c_str() : type.name.c_str());
637 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
644 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
645 simgrid::mc::Frame* frame, const char* ns)
647 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
648 auto& t = (info->types[type.id] = std::move(type));
649 if (not t.name.empty() && type.byte_size != 0)
650 info->full_types_by_name[t.name] = &t;
653 static int mc_anonymous_variable_index = 0;
655 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(simgrid::mc::ObjectInformation* info, Dwarf_Die* die,
656 Dwarf_Die* /*unit*/, simgrid::mc::Frame* frame,
659 // Skip declarations:
660 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
663 // Skip compile time constants:
664 if (dwarf_hasattr(die, DW_AT_const_value))
667 Dwarf_Attribute attr_location;
668 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
669 // No location: do not add it ?
672 std::unique_ptr<simgrid::mc::Variable> variable = std::unique_ptr<simgrid::mc::Variable>(new simgrid::mc::Variable());
673 variable->id = dwarf_dieoffset(die);
674 variable->global = frame == nullptr; // Can be override base on DW_AT_location
675 variable->object_info = info;
677 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
679 variable->name = name;
680 variable->type_id = MC_dwarf_at_type(die);
682 int form = dwarf_whatform(&attr_location);
683 simgrid::dwarf::FormClass form_class;
684 if (form == DW_FORM_sec_offset)
685 form_class = simgrid::dwarf::FormClass::Constant;
687 form_class = simgrid::dwarf::classify_form(form);
688 switch (form_class) {
689 case simgrid::dwarf::FormClass::ExprLoc:
690 case simgrid::dwarf::FormClass::Block:
691 // Location expression:
695 if (dwarf_getlocation(&attr_location, &expr, &len)) {
696 xbt_die("Could not read location expression in DW_AT_location "
697 "of variable <%" PRIx64 ">%s",
698 (uint64_t)variable->id, variable->name.c_str());
701 if (len == 1 && expr[0].atom == DW_OP_addr) {
702 variable->global = true;
703 uintptr_t offset = (uintptr_t)expr[0].number;
704 uintptr_t base = (uintptr_t)info->base_address();
705 variable->address = (void*)(base + offset);
707 variable->location_list = {
708 simgrid::dwarf::LocationListEntry(simgrid::dwarf::DwarfExpression(expr, expr + len))};
713 case simgrid::dwarf::FormClass::LocListPtr:
714 case simgrid::dwarf::FormClass::Constant:
715 // Reference to location list:
716 variable->location_list = simgrid::dwarf::location_list(*info, attr_location);
720 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
721 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
724 // Handle start_scope:
725 if (dwarf_hasattr(die, DW_AT_start_scope)) {
726 Dwarf_Attribute attr;
727 dwarf_attr(die, DW_AT_start_scope, &attr);
728 form = dwarf_whatform(&attr);
729 form_class = simgrid::dwarf::classify_form(form);
730 if (form_class == simgrid::dwarf::FormClass::Constant) {
732 variable->start_scope = dwarf_formudata(&attr, &value) == 0 ? (size_t)value : 0;
734 // TODO: FormClass::RangeListPtr
735 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
736 (unsigned)form_class, name == nullptr ? "?" : name);
740 if (ns && variable->global)
741 variable->name = std::string(ns) + "::" + variable->name;
743 // The current code needs a variable name,
744 // generate a fake one:
745 if (variable->name.empty()) {
746 variable->name = "@anonymous#" + std::to_string(mc_anonymous_variable_index);
747 mc_anonymous_variable_index++;
752 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
753 simgrid::mc::Frame* frame, const char* ns)
755 std::unique_ptr<simgrid::mc::Variable> variable = MC_die_to_variable(info, die, unit, frame, ns);
758 // Those arrays are sorted later:
759 if (variable->global)
760 info->global_variables.push_back(std::move(*variable));
761 else if (frame != nullptr)
762 frame->variables.push_back(std::move(*variable));
764 xbt_die("No frame for this local variable");
767 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
768 simgrid::mc::Frame* parent_frame, const char* ns)
770 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
771 int tag = dwarf_tag(die);
772 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
774 // (Template) Subprogram declaration:
775 if (klass == simgrid::dwarf::TagClass::Subprogram && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
778 if (klass == simgrid::dwarf::TagClass::Scope)
779 xbt_assert(parent_frame, "No parent scope for this scope");
781 simgrid::mc::Frame frame;
783 frame.id = dwarf_dieoffset(die);
784 frame.object_info = info;
786 if (klass == simgrid::dwarf::TagClass::Subprogram) {
787 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
789 frame.name = std::string(ns) + "::" + name;
794 frame.abstract_origin_id = MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
796 // This is the base address for DWARF addresses.
797 // Relocated addresses are offset from this base address.
798 // See DWARF4 spec 7.5
799 std::uint64_t base = (std::uint64_t)info->base_address();
801 // TODO, support DW_AT_ranges
802 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
803 frame.range.begin() = low_pc ? (std::uint64_t)base + low_pc : 0;
806 Dwarf_Attribute attr;
807 if (not dwarf_attr_integrate(die, DW_AT_high_pc, &attr))
808 xbt_die("Missing DW_AT_high_pc matching with DW_AT_low_pc");
813 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
815 // DW_AT_high_pc if an offset from the low_pc:
816 case simgrid::dwarf::FormClass::Constant:
818 if (dwarf_formsdata(&attr, &offset) != 0)
819 xbt_die("Could not read constant");
820 frame.range.end() = frame.range.begin() + offset;
823 // DW_AT_high_pc is a relocatable address:
824 case simgrid::dwarf::FormClass::Address:
825 if (dwarf_formaddr(&attr, &high_pc) != 0)
826 xbt_die("Could not read address");
827 frame.range.end() = base + high_pc;
831 xbt_die("Unexpected class for DW_AT_high_pc");
835 if (klass == simgrid::dwarf::TagClass::Subprogram) {
836 Dwarf_Attribute attr_frame_base;
837 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
838 frame.frame_base_location = simgrid::dwarf::location_list(*info, attr_frame_base);
842 MC_dwarf_handle_children(info, die, unit, &frame, ns);
844 // We sort them in order to have an (somewhat) efficient by name
846 boost::range::sort(frame.variables, MC_compare_variable);
849 if (klass == simgrid::dwarf::TagClass::Subprogram)
850 info->subprograms[frame.id] = std::move(frame);
851 else if (klass == simgrid::dwarf::TagClass::Scope)
852 parent_frame->scopes.push_back(std::move(frame));
855 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
856 simgrid::mc::Frame* frame, const char* ns)
858 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
860 xbt_die("Unexpected namespace in a subprogram");
861 char* new_ns = ns == nullptr ? xbt_strdup(name) : bprintf("%s::%s", ns, name);
862 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
866 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
867 simgrid::mc::Frame* frame, const char* ns)
869 // For each child DIE:
872 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child))
873 MC_dwarf_handle_die(info, &child, unit, frame, ns);
876 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
877 simgrid::mc::Frame* frame, const char* ns)
879 int tag = dwarf_tag(die);
880 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
884 case simgrid::dwarf::TagClass::Type:
885 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
888 // Subprogram or scope:
889 case simgrid::dwarf::TagClass::Subprogram:
890 case simgrid::dwarf::TagClass::Scope:
891 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
895 case simgrid::dwarf::TagClass::Variable:
896 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
899 case simgrid::dwarf::TagClass::Namespace:
900 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
908 static Elf64_Half get_type(Elf* elf)
910 Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
912 return ehdr64->e_type;
913 Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
915 return ehdr32->e_type;
916 xbt_die("Could not get ELF heeader");
919 static void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
921 // For each compilation unit:
922 Dwarf_Off offset = 0;
923 Dwarf_Off next_offset = 0;
926 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) == 0) {
928 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
929 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
930 offset = next_offset;
934 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
936 * This build-id may is used to locate an external debug (DWARF) file
939 * @param elf libelf handle for an ELF file
940 * @return build-id for this ELF file (or an empty vector if none is found)
942 static std::vector<char> get_build_id(Elf* elf)
945 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
946 // found in a PT_NOTE entry in the program header table.
949 if (elf_getphdrnum(elf, &phnum) != 0)
950 xbt_die("Could not read program headers");
952 // Iterate over the program headers and find the PT_NOTE ones:
953 for (size_t i = 0; i < phnum; ++i) {
955 GElf_Phdr* phdr = gelf_getphdr(elf, i, &phdr_temp);
956 if (phdr->p_type != PT_NOTE)
959 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
961 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
963 while (pos < data->d_size) {
965 // Location of the name within Elf_Data:
968 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
969 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
970 // (a namespace and a type within this namespace):
971 if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU") &&
972 memcmp((char*)data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
973 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
974 char* start = (char*)data->d_buf + desc_pos;
975 char* end = (char*)start + nhdr.n_descsz;
976 return std::vector<char>(start, end);
981 return std::vector<char>();
984 static char hexdigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
986 /** Binary data to hexadecimal */
987 static inline std::array<char, 2> to_hex(std::uint8_t byte)
989 // Horrid double braces!
990 // Apparently, this is needed in C++11 (not in C++14).
991 return {{hexdigits[byte >> 4], hexdigits[byte & 0xF]}};
994 /** Binary data to hexadecimal */
995 static std::string to_hex(const char* data, std::size_t count)
998 res.resize(2 * count);
999 for (std::size_t i = 0; i < count; i++) {
1000 std::array<char, 2> hex_byte = to_hex(data[i]);
1001 for (int j = 0; j < 2; ++j)
1002 res[2 * i + j] = hex_byte[j];
1007 /** Binary data to hexadecimal */
1008 static std::string to_hex(std::vector<char> const& data)
1010 return to_hex(data.data(), data.size());
1013 /** Base directories for external debug files */
1014 static const char* debug_paths[] = {
1016 "/usr/local/lib/debug/",
1019 /** Locate an external debug file from the NT_GNU_BUILD_ID
1021 * This is one of the mechanisms used for
1022 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
1025 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
1026 static std::string find_by_build_id(std::vector<char> id)
1028 std::string filename;
1029 std::string hex = to_hex(id);
1030 for (const char* const& debug_path : debug_paths) {
1032 filename = std::string(debug_path) + ".build-id/" + to_hex(id.data(), 1) + '/' +
1033 to_hex(id.data() + 1, id.size() - 1) + ".debug";
1034 XBT_DEBUG("Checking debug file: %s", filename.c_str());
1035 if (access(filename.c_str(), F_OK) == 0) {
1036 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
1040 XBT_DEBUG("Not debuf info found for build ID %s\n", hex.data());
1041 return std::string();
1044 /** @brief Populate the debugging informations of the given ELF object
1046 * Read the DWARf information of the EFFL object and populate the
1047 * lists of types, variables, functions.
1049 static void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
1051 if (elf_version(EV_CURRENT) == EV_NONE)
1052 xbt_die("libelf initialization error");
1054 // Open the ELF file:
1055 int fd = open(info->file_name.c_str(), O_RDONLY);
1057 xbt_die("Could not open file %s", info->file_name.c_str());
1058 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
1060 xbt_die("Not an ELF file");
1061 Elf_Kind kind = elf_kind(elf);
1062 if (kind != ELF_K_ELF)
1063 xbt_die("Not an ELF file");
1065 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
1066 Elf64_Half type = get_type(elf);
1067 if (type == ET_EXEC)
1068 info->flags |= simgrid::mc::ObjectInformation::Executable;
1070 // Read DWARF debug information in the file:
1071 Dwarf* dwarf = dwarf_begin_elf(elf, DWARF_C_READ, nullptr);
1072 if (dwarf != nullptr) {
1073 read_dwarf_info(info, dwarf);
1081 // If there was no DWARF in the file, try to find it in a separate file.
1082 // Different methods might be used to store the DWARF informations:
1083 // * GNU NT_GNU_BUILD_ID
1085 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1086 // for reference of what we are doing.
1088 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1089 // use this ID to find the file in some known locations in the filesystem.
1090 std::vector<char> build_id = get_build_id(elf);
1091 if (not build_id.empty()) {
1095 // Find the debug file using the build id:
1096 std::string debug_file = find_by_build_id(build_id);
1097 if (debug_file.empty()) {
1098 std::string hex = to_hex(build_id);
1099 xbt_die("Missing debug info for %s with build-id %s\n"
1100 "You might want to install the suitable debugging package.\n",
1101 info->file_name.c_str(), hex.c_str());
1104 // Load the DWARF info from this file:
1105 XBT_DEBUG("Load DWARF for %s from %s", info->file_name.c_str(), debug_file.c_str());
1106 fd = open(debug_file.c_str(), O_RDONLY);
1108 xbt_die("Could not open file %s", debug_file.c_str());
1109 dwarf = dwarf_begin(fd, DWARF_C_READ);
1110 if (dwarf == nullptr)
1111 xbt_die("No DWARF info in %s for %s", debug_file.c_str(), info->file_name.c_str());
1112 read_dwarf_info(info, dwarf);
1118 // TODO, try to find DWARF info using .gnu_debuglink.
1122 xbt_die("Debugging information not found for %s\n"
1123 "Try recompiling with -g\n",
1124 info->file_name.c_str());
1127 // ***** Functions index
1129 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1131 info->functions_index.clear();
1133 for (auto& e : info->subprograms) {
1134 if (e.second.range.begin() == 0)
1136 simgrid::mc::FunctionIndexEntry entry;
1137 entry.low_pc = (void*)e.second.range.begin();
1138 entry.function = &e.second;
1139 info->functions_index.push_back(entry);
1142 info->functions_index.shrink_to_fit();
1144 // Sort the array by low_pc:
1145 boost::range::sort(info->functions_index,
1146 [](simgrid::mc::FunctionIndexEntry const& a, simgrid::mc::FunctionIndexEntry const& b) {
1147 return a.low_pc < b.low_pc;
1151 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1153 // Someone needs this to be sorted but who?
1154 boost::range::sort(info->global_variables, MC_compare_variable);
1156 for (simgrid::mc::Variable& variable : info->global_variables)
1157 if (variable.type_id)
1158 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1161 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1164 if (scope->tag == DW_TAG_inlined_subroutine) {
1165 // Attach correct namespaced name in inlined subroutine:
1166 auto i = info->subprograms.find(scope->abstract_origin_id);
1167 xbt_assert(i != info->subprograms.end(), "Could not lookup abstract origin %" PRIx64,
1168 (std::uint64_t)scope->abstract_origin_id);
1169 scope->name = i->second.name;
1173 for (simgrid::mc::Variable& variable : scope->variables)
1174 if (variable.type_id)
1175 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1177 // Recursive post-processing of nested-scopes:
1178 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1179 mc_post_process_scope(info, &nested_scope);
1182 static simgrid::mc::Type* MC_resolve_type(simgrid::mc::ObjectInformation* info, unsigned type_id)
1186 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1187 if (type == nullptr)
1190 // We already have the information on the type:
1191 if (type->byte_size != 0)
1194 // Don't have a name, we can't find a more complete version:
1195 if (type->name.empty())
1198 // Try to find a more complete description of the type:
1199 // We need to fix in order to support C++.
1200 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(info->full_types_by_name, type->name);
1206 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1208 // Lookup "subtype" field:
1209 for (auto& i : info->types) {
1210 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1211 for (simgrid::mc::Member& member : i.second.members)
1212 member.type = MC_resolve_type(info, member.type_id);
1219 /** @brief Finds informations about a given shared object/executable */
1220 std::shared_ptr<simgrid::mc::ObjectInformation> createObjectInformation(std::vector<simgrid::xbt::VmMap> const& maps,
1223 std::shared_ptr<simgrid::mc::ObjectInformation> result = std::make_shared<simgrid::mc::ObjectInformation>();
1224 result->file_name = name;
1225 simgrid::mc::find_object_address(maps, result.get());
1226 MC_load_dwarf(result.get());
1227 MC_post_process_variables(result.get());
1228 MC_post_process_types(result.get());
1229 for (auto& entry : result.get()->subprograms)
1230 mc_post_process_scope(result.get(), &entry.second);
1231 MC_make_functions_index(result.get());
1235 /*************************************************************************/
1237 void postProcessObjectInformation(simgrid::mc::RemoteClient* process, simgrid::mc::ObjectInformation* info)
1239 for (auto& t : info->types) {
1241 simgrid::mc::Type* type = &(t.second);
1242 simgrid::mc::Type* subtype = type;
1243 while (subtype->type == DW_TAG_typedef || subtype->type == DW_TAG_volatile_type ||
1244 subtype->type == DW_TAG_const_type)
1245 if (subtype->subtype)
1246 subtype = subtype->subtype;
1250 // Resolve full_type:
1251 if (not subtype->name.empty() && subtype->byte_size == 0)
1252 for (auto const& object_info : process->object_infos) {
1253 auto i = object_info->full_types_by_name.find(subtype->name);
1254 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1255 type->full_type = i->second;
1260 type->full_type = subtype;
1265 } // namespace simgrid
1270 /** Convert a DWARF register into a libunwind register
1272 * DWARF and libunwind does not use the same convention for numbering the
1273 * registers on some architectures. The function makes the necessary
1276 int dwarf_register_to_libunwind(int dwarf_register)
1278 #if defined(__x86_64__)
1279 // It seems for this arch, DWARF and libunwind agree in the numbering:
1280 return dwarf_register;
1281 #elif defined(__i386__)
1282 // Couldn't find the authoritative source of information for this.
1283 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1284 switch (dwarf_register) {
1304 return UNW_X86_EFLAGS;
1334 xbt_die("Bad/unknown register number.");
1337 #error This architecture is not supported yet for DWARF expression evaluation.
1341 } // namespace dwarf
1342 } // namespace simgrid