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 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
258 return dwarf_dieoffset(&subtype_die);
261 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die* die, int attribute)
263 Dwarf_Attribute attr;
264 if (dwarf_hasattr_integrate(die, attribute) == 0)
266 dwarf_attr_integrate(die, DW_AT_type, &attr);
267 Dwarf_Die subtype_die;
268 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
269 return dwarf_dieoffset(&subtype_die);
272 /** @brief Find the type/subtype (DW_AT_type) for a DIE
275 * @return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
277 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die)
279 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
282 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die* die, int attribute)
284 Dwarf_Attribute attr;
285 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
288 if (dwarf_formaddr(&attr, &value) == 0)
289 return (uint64_t)value;
294 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die* die, int attribute, uint64_t default_value)
296 Dwarf_Attribute attr;
297 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
298 return default_value;
300 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t)value : default_value;
303 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, bool integrate)
305 Dwarf_Attribute attr;
306 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr) : dwarf_attr(die, attribute, &attr)) == 0)
310 xbt_assert(not dwarf_formflag(&attr, &result), "Unexpected form for attribute %s",
311 simgrid::dwarf::attrname(attribute));
315 /** @brief Find the default lower bound for a given language
317 * The default lower bound of an array (when DW_TAG_lower_bound
318 * is missing) depends on the language of the compilation unit.
320 * @param lang Language of the compilation unit (values defined in the DWARF spec)
321 * @return Default lower bound of an array in this compilation unit
323 static uint64_t MC_dwarf_default_lower_bound(int lang)
329 case DW_LANG_C_plus_plus:
333 case DW_LANG_ObjC_plus_plus:
339 case DW_LANG_Fortran77:
340 case DW_LANG_Fortran90:
341 case DW_LANG_Fortran95:
342 case DW_LANG_Modula2:
343 case DW_LANG_Pascal83:
345 case DW_LANG_Cobol74:
346 case DW_LANG_Cobol85:
349 xbt_die("No default DW_TAG_lower_bound for language %i and none given", lang);
354 /** @brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
357 * @param unit DIE of the compilation unit
358 * @return number of elements in the range
360 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit)
362 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type || dwarf_tag(die) == DW_TAG_subrange_type,
363 "MC_dwarf_subrange_element_count called with DIE of type %s", simgrid::dwarf::tagname(die));
365 // Use DW_TAG_count if present:
366 if (dwarf_hasattr_integrate(die, DW_AT_count))
367 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
368 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
370 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
371 // This is not really 0, but the code expects this (we do not know):
374 uint64_t upper_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, static_cast<uint64_t>(-1));
376 uint64_t lower_bound = 0;
377 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
378 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, static_cast<uint64_t>(-1));
380 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
381 return upper_bound - lower_bound + 1;
384 /** @brief Finds the number of elements in a array type (DW_TAG_array_type)
386 * The compilation unit might be needed because the default lower
387 * bound depends on the language of the compilation unit.
389 * @param die the DIE of the DW_TAG_array_type
390 * @param unit the DIE of the compilation unit
391 * @return number of elements in this array type
393 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit)
395 xbt_assert(dwarf_tag(die) == DW_TAG_array_type, "MC_dwarf_array_element_count called with DIE of type %s",
396 simgrid::dwarf::tagname(die));
401 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
402 int child_tag = dwarf_tag(&child);
403 if (child_tag == DW_TAG_subrange_type || child_tag == DW_TAG_enumeration_type)
404 result *= MC_dwarf_subrange_element_count(&child, unit);
411 /** Sort the variable by name and address.
413 * We could use boost::container::flat_set instead.
415 static bool MC_compare_variable(simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
417 int cmp = a.name.compare(b.name);
423 return a.address < b.address;
426 // ***** simgrid::mc::Type*
428 /** @brief Initialize the location of a member of a type
429 * (DW_AT_data_member_location of a DW_TAG_member).
431 * @param type a type (struct, class)
432 * @param member the member of the type
433 * @param child DIE of the member (DW_TAG_member)
435 static void MC_dwarf_fill_member_location(simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die* child)
437 xbt_assert(not dwarf_hasattr(child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
439 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
440 if (type->type == DW_TAG_union_type)
442 xbt_die("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%" PRIx64 ">%s",
443 member->name.c_str(), (uint64_t)type->id, type->name.c_str());
446 Dwarf_Attribute attr;
447 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
448 int form = dwarf_whatform(&attr);
449 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
450 switch (form_class) {
451 case simgrid::dwarf::FormClass::ExprLoc:
452 case simgrid::dwarf::FormClass::Block:
453 // Location expression:
457 xbt_assert(not dwarf_getlocation(&attr, &expr, &len),
458 "Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%" PRIx64
460 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
461 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr + len);
464 case simgrid::dwarf::FormClass::Constant:
465 // Offset from the base address of the object:
468 xbt_assert(not dwarf_formudata(&attr, &offset), "Cannot get %s location <%" PRIx64 ">%s",
469 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
470 member->offset(offset);
475 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to
476 // be possible in DWARF2 but I couldn't find its semantic in the spec)
477 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
481 /** @brief Populate the list of members of a type
483 * @param info ELF object containing the type DIE
484 * @param die DIE of the type
485 * @param unit DIE of the compilation unit containing the type DIE
486 * @param type the type
488 static void MC_dwarf_add_members(simgrid::mc::ObjectInformation* /*info*/, Dwarf_Die* die, Dwarf_Die* /*unit*/,
489 simgrid::mc::Type* type)
493 xbt_assert(type->members.empty());
494 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
495 int tag = dwarf_tag(&child);
496 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
498 // Skip declarations:
499 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
502 // Skip compile time constants:
503 if (dwarf_hasattr(&child, DW_AT_const_value))
506 // TODO, we should use another type (because is is not a type but a member)
507 simgrid::mc::Member member;
508 if (tag == DW_TAG_inheritance)
509 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
511 const char* name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
514 // Those base names are used by GCC and clang for virtual table pointers
515 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
516 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
517 boost::algorithm::starts_with(member.name, "__vptr."))
518 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
519 // A cleaner solution would be to check against the type:
521 // tag: DW_TAG_member
524 // # Type for a pointer to a vtable
525 // tag: DW_TAG_pointer_type
527 // # Type for a vtable:
528 // tag: DW_TAG_pointer_type
529 // name: "__vtbl_ptr_type"
531 // tag: DW_TAG_subroutine_type
533 // tag: DW_TAG_base_type
537 member.byte_size = MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
538 member.type_id = MC_dwarf_at_type(&child);
540 xbt_assert(not dwarf_hasattr(&child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
542 MC_dwarf_fill_member_location(type, &member, &child);
544 xbt_assert(member.type_id, "Missing type for member %s of <%" PRIx64 ">%s", member.name.c_str(),
545 (uint64_t)type->id, type->name.c_str());
547 type->members.push_back(std::move(member));
552 /** @brief Create a MC type object from a DIE
554 * @param info current object info object
555 * @param die DIE (for a given type)
556 * @param unit compilation unit of the current DIE
557 * @return MC representation of the type
559 static simgrid::mc::Type MC_dwarf_die_to_type(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
560 simgrid::mc::Frame* frame, const char* ns)
562 simgrid::mc::Type type;
563 type.type = dwarf_tag(die);
564 type.name = std::string();
565 type.element_count = -1;
568 type.id = dwarf_dieoffset(die);
570 const char* prefix = "";
572 case DW_TAG_structure_type:
575 case DW_TAG_union_type:
578 case DW_TAG_class_type:
585 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
586 if (name != nullptr) {
588 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
590 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
593 type.type_id = MC_dwarf_at_type(die);
595 // Some compilers do not emit DW_AT_byte_size for pointer_type,
596 // so we fill this. We currently assume that the model-checked process is in
597 // the same architecture..
598 if (type.type == DW_TAG_pointer_type)
599 type.byte_size = sizeof(void*);
601 // Computation of the byte_size
602 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
603 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
604 else if (type.type == DW_TAG_array_type || type.type == DW_TAG_structure_type || type.type == DW_TAG_class_type) {
606 if (dwarf_aggregate_size(die, &size) == 0)
607 type.byte_size = size;
611 case DW_TAG_array_type:
612 type.element_count = MC_dwarf_array_element_count(die, unit);
613 // TODO, handle DW_byte_stride and (not) DW_bit_stride
616 case DW_TAG_pointer_type:
617 case DW_TAG_reference_type:
618 case DW_TAG_rvalue_reference_type:
621 case DW_TAG_structure_type:
622 case DW_TAG_union_type:
623 case DW_TAG_class_type:
624 MC_dwarf_add_members(info, die, unit, &type);
625 MC_dwarf_handle_children(info, die, unit, frame,
626 ns ? simgrid::xbt::string_printf("%s::%s", ns, name).c_str() : type.name.c_str());
630 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
637 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
638 simgrid::mc::Frame* frame, const char* ns)
640 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
641 auto& t = (info->types[type.id] = std::move(type));
642 if (not t.name.empty() && type.byte_size != 0)
643 info->full_types_by_name[t.name] = &t;
646 static int mc_anonymous_variable_index = 0;
648 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(simgrid::mc::ObjectInformation* info, Dwarf_Die* die,
649 Dwarf_Die* /*unit*/, simgrid::mc::Frame* frame,
652 // Skip declarations:
653 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
656 // Skip compile time constants:
657 if (dwarf_hasattr(die, DW_AT_const_value))
660 Dwarf_Attribute attr_location;
661 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
662 // No location: do not add it ?
665 std::unique_ptr<simgrid::mc::Variable> variable = std::unique_ptr<simgrid::mc::Variable>(new simgrid::mc::Variable());
666 variable->id = dwarf_dieoffset(die);
667 variable->global = frame == nullptr; // Can be override base on DW_AT_location
668 variable->object_info = info;
670 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
672 variable->name = name;
673 variable->type_id = MC_dwarf_at_type(die);
675 int form = dwarf_whatform(&attr_location);
676 simgrid::dwarf::FormClass form_class;
677 if (form == DW_FORM_sec_offset)
678 form_class = simgrid::dwarf::FormClass::Constant;
680 form_class = simgrid::dwarf::classify_form(form);
681 switch (form_class) {
682 case simgrid::dwarf::FormClass::ExprLoc:
683 case simgrid::dwarf::FormClass::Block:
684 // Location expression:
688 xbt_assert(not dwarf_getlocation(&attr_location, &expr, &len),
689 "Could not read location expression in DW_AT_location "
690 "of variable <%" PRIx64 ">%s",
691 (uint64_t)variable->id, variable->name.c_str());
693 if (len == 1 && expr[0].atom == DW_OP_addr) {
694 variable->global = true;
695 uintptr_t offset = (uintptr_t)expr[0].number;
696 uintptr_t base = (uintptr_t)info->base_address();
697 variable->address = (void*)(base + offset);
699 variable->location_list = {
700 simgrid::dwarf::LocationListEntry(simgrid::dwarf::DwarfExpression(expr, expr + len))};
705 case simgrid::dwarf::FormClass::LocListPtr:
706 case simgrid::dwarf::FormClass::Constant:
707 // Reference to location list:
708 variable->location_list = simgrid::dwarf::location_list(*info, attr_location);
712 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
713 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
716 // Handle start_scope:
717 if (dwarf_hasattr(die, DW_AT_start_scope)) {
718 Dwarf_Attribute attr;
719 dwarf_attr(die, DW_AT_start_scope, &attr);
720 form = dwarf_whatform(&attr);
721 form_class = simgrid::dwarf::classify_form(form);
722 if (form_class == simgrid::dwarf::FormClass::Constant) {
724 variable->start_scope = dwarf_formudata(&attr, &value) == 0 ? (size_t)value : 0;
726 // TODO: FormClass::RangeListPtr
727 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
728 (unsigned)form_class, name == nullptr ? "?" : name);
732 if (ns && variable->global)
733 variable->name = std::string(ns) + "::" + variable->name;
735 // The current code needs a variable name,
736 // generate a fake one:
737 if (variable->name.empty()) {
738 variable->name = "@anonymous#" + std::to_string(mc_anonymous_variable_index);
739 mc_anonymous_variable_index++;
744 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
745 simgrid::mc::Frame* frame, const char* ns)
747 std::unique_ptr<simgrid::mc::Variable> variable = MC_die_to_variable(info, die, unit, frame, ns);
750 // Those arrays are sorted later:
751 if (variable->global)
752 info->global_variables.push_back(std::move(*variable));
753 else if (frame != nullptr)
754 frame->variables.push_back(std::move(*variable));
756 xbt_die("No frame for this local variable");
759 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
760 simgrid::mc::Frame* parent_frame, const char* ns)
762 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
763 int tag = dwarf_tag(die);
764 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
766 // (Template) Subprogram declaration:
767 if (klass == simgrid::dwarf::TagClass::Subprogram && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
770 if (klass == simgrid::dwarf::TagClass::Scope)
771 xbt_assert(parent_frame, "No parent scope for this scope");
773 simgrid::mc::Frame frame;
775 frame.id = dwarf_dieoffset(die);
776 frame.object_info = info;
778 if (klass == simgrid::dwarf::TagClass::Subprogram) {
779 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
781 frame.name = std::string(ns) + "::" + name;
786 frame.abstract_origin_id = MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
788 // This is the base address for DWARF addresses.
789 // Relocated addresses are offset from this base address.
790 // See DWARF4 spec 7.5
791 std::uint64_t base = (std::uint64_t)info->base_address();
793 // TODO, support DW_AT_ranges
794 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
795 frame.range.begin() = low_pc ? (std::uint64_t)base + low_pc : 0;
798 Dwarf_Attribute attr;
799 xbt_assert(dwarf_attr_integrate(die, DW_AT_high_pc, &attr), "Missing DW_AT_high_pc matching with DW_AT_low_pc");
804 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
806 // DW_AT_high_pc if an offset from the low_pc:
807 case simgrid::dwarf::FormClass::Constant:
809 xbt_assert(dwarf_formsdata(&attr, &offset) == 0, "Could not read constant");
810 frame.range.end() = frame.range.begin() + offset;
813 // DW_AT_high_pc is a relocatable address:
814 case simgrid::dwarf::FormClass::Address:
815 xbt_assert(dwarf_formaddr(&attr, &high_pc) == 0, "Could not read address");
816 frame.range.end() = base + high_pc;
820 xbt_die("Unexpected class for DW_AT_high_pc");
824 if (klass == simgrid::dwarf::TagClass::Subprogram) {
825 Dwarf_Attribute attr_frame_base;
826 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
827 frame.frame_base_location = simgrid::dwarf::location_list(*info, attr_frame_base);
831 MC_dwarf_handle_children(info, die, unit, &frame, ns);
833 // We sort them in order to have an (somewhat) efficient by name
835 boost::range::sort(frame.variables, MC_compare_variable);
838 if (klass == simgrid::dwarf::TagClass::Subprogram)
839 info->subprograms[frame.id] = std::move(frame);
840 else if (klass == simgrid::dwarf::TagClass::Scope)
841 parent_frame->scopes.push_back(std::move(frame));
844 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
845 simgrid::mc::Frame* frame, const char* ns)
847 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
848 xbt_assert(not frame, "Unexpected namespace in a subprogram");
849 char* new_ns = ns == nullptr ? xbt_strdup(name) : bprintf("%s::%s", ns, name);
850 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
854 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
855 simgrid::mc::Frame* frame, const char* ns)
857 // For each child DIE:
860 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child))
861 MC_dwarf_handle_die(info, &child, unit, frame, ns);
864 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
865 simgrid::mc::Frame* frame, const char* ns)
867 int tag = dwarf_tag(die);
868 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
872 case simgrid::dwarf::TagClass::Type:
873 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
876 // Subprogram or scope:
877 case simgrid::dwarf::TagClass::Subprogram:
878 case simgrid::dwarf::TagClass::Scope:
879 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
883 case simgrid::dwarf::TagClass::Variable:
884 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
887 case simgrid::dwarf::TagClass::Namespace:
888 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
896 static Elf64_Half get_type(Elf* elf)
898 Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
900 return ehdr64->e_type;
901 Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
903 return ehdr32->e_type;
904 xbt_die("Could not get ELF heeader");
907 static void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
909 // For each compilation unit:
910 Dwarf_Off offset = 0;
911 Dwarf_Off next_offset = 0;
914 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) == 0) {
916 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
917 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
918 offset = next_offset;
922 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
924 * This build-id may is used to locate an external debug (DWARF) file
927 * @param elf libelf handle for an ELF file
928 * @return build-id for this ELF file (or an empty vector if none is found)
930 static std::vector<char> get_build_id(Elf* elf)
933 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
934 // found in a PT_NOTE entry in the program header table.
937 xbt_assert(elf_getphdrnum(elf, &phnum) == 0, "Could not read program headers");
939 // Iterate over the program headers and find the PT_NOTE ones:
940 for (size_t i = 0; i < phnum; ++i) {
942 GElf_Phdr* phdr = gelf_getphdr(elf, i, &phdr_temp);
943 if (phdr->p_type != PT_NOTE)
946 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
948 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
950 while (pos < data->d_size) {
952 // Location of the name within Elf_Data:
955 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
956 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
957 // (a namespace and a type within this namespace):
958 if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU") &&
959 memcmp((char*)data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
960 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
961 char* start = (char*)data->d_buf + desc_pos;
962 char* end = (char*)start + nhdr.n_descsz;
963 return std::vector<char>(start, end);
968 return std::vector<char>();
971 static char hexdigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
973 /** Binary data to hexadecimal */
974 static inline std::array<char, 2> to_hex(std::uint8_t byte)
976 // Horrid double braces!
977 // Apparently, this is needed in C++11 (not in C++14).
978 return {{hexdigits[byte >> 4], hexdigits[byte & 0xF]}};
981 /** Binary data to hexadecimal */
982 static std::string to_hex(const char* data, std::size_t count)
985 res.resize(2 * count);
986 for (std::size_t i = 0; i < count; i++) {
987 std::array<char, 2> hex_byte = to_hex(data[i]);
988 for (int j = 0; j < 2; ++j)
989 res[2 * i + j] = hex_byte[j];
994 /** Binary data to hexadecimal */
995 static std::string to_hex(std::vector<char> const& data)
997 return to_hex(data.data(), data.size());
1000 /** Base directories for external debug files */
1001 static const char* debug_paths[] = {
1003 "/usr/local/lib/debug/",
1006 /** Locate an external debug file from the NT_GNU_BUILD_ID
1008 * This is one of the mechanisms used for
1009 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
1012 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
1013 static std::string find_by_build_id(std::vector<char> id)
1015 std::string filename;
1016 std::string hex = to_hex(id);
1017 for (const char* const& debug_path : debug_paths) {
1019 filename = std::string(debug_path) + ".build-id/" + to_hex(id.data(), 1) + '/' +
1020 to_hex(id.data() + 1, id.size() - 1) + ".debug";
1021 XBT_DEBUG("Checking debug file: %s", filename.c_str());
1022 if (access(filename.c_str(), F_OK) == 0) {
1023 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
1027 XBT_DEBUG("Not debuf info found for build ID %s\n", hex.data());
1028 return std::string();
1031 /** @brief Populate the debugging informations of the given ELF object
1033 * Read the DWARf information of the EFFL object and populate the
1034 * lists of types, variables, functions.
1036 static void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
1038 xbt_assert(elf_version(EV_CURRENT) != EV_NONE, "libelf initialization error");
1040 // Open the ELF file:
1041 int fd = open(info->file_name.c_str(), O_RDONLY);
1042 xbt_assert(fd >= 0, "Could not open file %s", info->file_name.c_str());
1043 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
1044 xbt_assert(elf != nullptr, "Not an ELF file");
1045 Elf_Kind kind = elf_kind(elf);
1046 xbt_assert(kind == ELF_K_ELF, "Not an ELF file");
1048 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
1049 Elf64_Half type = get_type(elf);
1050 if (type == ET_EXEC)
1051 info->flags |= simgrid::mc::ObjectInformation::Executable;
1053 // Read DWARF debug information in the file:
1054 Dwarf* dwarf = dwarf_begin_elf(elf, DWARF_C_READ, nullptr);
1055 if (dwarf != nullptr) {
1056 read_dwarf_info(info, dwarf);
1064 // If there was no DWARF in the file, try to find it in a separate file.
1065 // Different methods might be used to store the DWARF informations:
1066 // * GNU NT_GNU_BUILD_ID
1068 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1069 // for reference of what we are doing.
1071 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1072 // use this ID to find the file in some known locations in the filesystem.
1073 std::vector<char> build_id = get_build_id(elf);
1074 if (not build_id.empty()) {
1078 // Find the debug file using the build id:
1079 std::string debug_file = find_by_build_id(build_id);
1080 xbt_assert(not debug_file.empty(),
1081 "Missing debug info for %s with build-id %s\n"
1082 "You might want to install the suitable debugging package.\n",
1083 info->file_name.c_str(), to_hex(build_id).c_str());
1085 // Load the DWARF info from this file:
1086 XBT_DEBUG("Load DWARF for %s from %s", info->file_name.c_str(), debug_file.c_str());
1087 fd = open(debug_file.c_str(), O_RDONLY);
1088 xbt_assert(fd >= 0, "Could not open file %s", debug_file.c_str());
1089 dwarf = dwarf_begin(fd, DWARF_C_READ);
1090 xbt_assert(dwarf != nullptr, "No DWARF info in %s for %s", debug_file.c_str(), info->file_name.c_str());
1091 read_dwarf_info(info, dwarf);
1097 // TODO, try to find DWARF info using .gnu_debuglink.
1101 xbt_die("Debugging information not found for %s\n"
1102 "Try recompiling with -g\n",
1103 info->file_name.c_str());
1106 // ***** Functions index
1108 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1110 info->functions_index.clear();
1112 for (auto& e : info->subprograms) {
1113 if (e.second.range.begin() == 0)
1115 simgrid::mc::FunctionIndexEntry entry;
1116 entry.low_pc = (void*)e.second.range.begin();
1117 entry.function = &e.second;
1118 info->functions_index.push_back(entry);
1121 info->functions_index.shrink_to_fit();
1123 // Sort the array by low_pc:
1124 boost::range::sort(info->functions_index,
1125 [](simgrid::mc::FunctionIndexEntry const& a, simgrid::mc::FunctionIndexEntry const& b) {
1126 return a.low_pc < b.low_pc;
1130 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1132 // Someone needs this to be sorted but who?
1133 boost::range::sort(info->global_variables, MC_compare_variable);
1135 for (simgrid::mc::Variable& variable : info->global_variables)
1136 if (variable.type_id)
1137 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1140 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1143 if (scope->tag == DW_TAG_inlined_subroutine) {
1144 // Attach correct namespaced name in inlined subroutine:
1145 auto i = info->subprograms.find(scope->abstract_origin_id);
1146 xbt_assert(i != info->subprograms.end(), "Could not lookup abstract origin %" PRIx64,
1147 (std::uint64_t)scope->abstract_origin_id);
1148 scope->name = i->second.name;
1152 for (simgrid::mc::Variable& variable : scope->variables)
1153 if (variable.type_id)
1154 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1156 // Recursive post-processing of nested-scopes:
1157 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1158 mc_post_process_scope(info, &nested_scope);
1161 static simgrid::mc::Type* MC_resolve_type(simgrid::mc::ObjectInformation* info, unsigned type_id)
1165 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1166 if (type == nullptr)
1169 // We already have the information on the type:
1170 if (type->byte_size != 0)
1173 // Don't have a name, we can't find a more complete version:
1174 if (type->name.empty())
1177 // Try to find a more complete description of the type:
1178 // We need to fix in order to support C++.
1179 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(info->full_types_by_name, type->name);
1185 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1187 // Lookup "subtype" field:
1188 for (auto& i : info->types) {
1189 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1190 for (simgrid::mc::Member& member : i.second.members)
1191 member.type = MC_resolve_type(info, member.type_id);
1198 /** @brief Finds informations about a given shared object/executable */
1199 std::shared_ptr<simgrid::mc::ObjectInformation> createObjectInformation(std::vector<simgrid::xbt::VmMap> const& maps,
1202 std::shared_ptr<simgrid::mc::ObjectInformation> result = std::make_shared<simgrid::mc::ObjectInformation>();
1203 result->file_name = name;
1204 simgrid::mc::find_object_address(maps, result.get());
1205 MC_load_dwarf(result.get());
1206 MC_post_process_variables(result.get());
1207 MC_post_process_types(result.get());
1208 for (auto& entry : result.get()->subprograms)
1209 mc_post_process_scope(result.get(), &entry.second);
1210 MC_make_functions_index(result.get());
1214 /*************************************************************************/
1216 void postProcessObjectInformation(simgrid::mc::RemoteClient* process, simgrid::mc::ObjectInformation* info)
1218 for (auto& t : info->types) {
1220 simgrid::mc::Type* type = &(t.second);
1221 simgrid::mc::Type* subtype = type;
1222 while (subtype->type == DW_TAG_typedef || subtype->type == DW_TAG_volatile_type ||
1223 subtype->type == DW_TAG_const_type)
1224 if (subtype->subtype)
1225 subtype = subtype->subtype;
1229 // Resolve full_type:
1230 if (not subtype->name.empty() && subtype->byte_size == 0)
1231 for (auto const& object_info : process->object_infos) {
1232 auto i = object_info->full_types_by_name.find(subtype->name);
1233 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1234 type->full_type = i->second;
1239 type->full_type = subtype;
1244 } // namespace simgrid
1249 /** Convert a DWARF register into a libunwind register
1251 * DWARF and libunwind does not use the same convention for numbering the
1252 * registers on some architectures. The function makes the necessary
1255 int dwarf_register_to_libunwind(int dwarf_register)
1257 #if defined(__x86_64__)
1258 // It seems for this arch, DWARF and libunwind agree in the numbering:
1259 return dwarf_register;
1260 #elif defined(__i386__)
1261 // Couldn't find the authoritative source of information for this.
1262 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1263 switch (dwarf_register) {
1283 return UNW_X86_EFLAGS;
1313 xbt_die("Bad/unknown register number.");
1316 #error This architecture is not supported yet for DWARF expression evaluation.
1320 } // namespace dwarf
1321 } // namespace simgrid