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. */
12 #include <boost/range/algorithm.hpp>
15 #include <elfutils/libdw.h>
18 #include <boost/algorithm/string/predicate.hpp>
20 #include "src/simgrid/util.hpp"
22 #include "xbt/string.hpp"
23 #include "xbt/sysdep.h"
24 #include <simgrid/config.h>
26 #include "src/mc/mc_dwarf.hpp"
27 #include "src/mc/mc_private.hpp"
29 #include "src/mc/ObjectInformation.hpp"
30 #include "src/mc/Variable.hpp"
31 #include "src/mc/remote/RemoteClient.hpp"
33 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dwarf, mc, "DWARF processing");
35 /** @brief The default DW_TAG_lower_bound for a given DW_AT_language.
37 * The default for a given language is defined in the DWARF spec.
39 * @param language constant as defined by the DWARf spec
41 static uint64_t MC_dwarf_default_lower_bound(int lang);
43 /** @brief Computes the the element_count of a DW_TAG_enumeration_type DIE
45 * This is the number of elements in a given array dimension.
47 * A reference of the compilation unit (DW_TAG_compile_unit) is
48 * needed because the default lower bound (when there is no DW_AT_lower_bound)
49 * depends of the language of the compilation unit (DW_AT_language).
51 * @param die DIE for the DW_TAG_enumeration_type or DW_TAG_subrange_type
52 * @param unit DIE of the DW_TAG_compile_unit
54 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit);
56 /** @brief Computes the number of elements of a given DW_TAG_array_type.
58 * @param die DIE for the DW_TAG_array_type
60 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit);
62 /** @brief Process a DIE
64 * @param info the resulting object fot the library/binary file (output)
65 * @param die the current DIE
66 * @param unit the DIE of the compile unit of the current DIE
67 * @param frame containing frame if any
69 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
70 simgrid::mc::Frame* frame, const char* ns);
72 /** @brief Process a type DIE
74 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
75 simgrid::mc::Frame* frame, const char* ns);
77 /** @brief Calls MC_dwarf_handle_die on all children of the given die
79 * @param info the resulting object fot the library/binary file (output)
80 * @param die the current DIE
81 * @param unit the DIE of the compile unit of the current DIE
82 * @param frame containing frame if any
84 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
85 simgrid::mc::Frame* frame, const char* ns);
87 /** @brief Handle a variable (DW_TAG_variable or other)
89 * @param info the resulting object fot the library/binary file (output)
90 * @param die the current DIE
91 * @param unit the DIE of the compile unit of the current DIE
92 * @param frame containing frame if any
94 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
95 simgrid::mc::Frame* frame, const char* ns);
97 /** @brief Get the DW_TAG_type of the DIE
100 * @return DW_TAG_type attribute as a new string (nullptr if none)
102 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die);
107 enum class TagClass { Unknown, Type, Subprogram, Variable, Scope, Namespace };
109 /*** Class of forms defined in the DWARF standard */
110 enum class FormClass {
112 Address, // Location in the program's address space
113 Block, // Arbitrary block of bytes
116 Flag, // Boolean value
117 Reference, // Reference to another DIE
118 ExprLoc, // DWARF expression/location description
125 static TagClass classify_tag(int tag)
129 case DW_TAG_array_type:
130 case DW_TAG_class_type:
131 case DW_TAG_enumeration_type:
133 case DW_TAG_pointer_type:
134 case DW_TAG_reference_type:
135 case DW_TAG_rvalue_reference_type:
136 case DW_TAG_string_type:
137 case DW_TAG_structure_type:
138 case DW_TAG_subroutine_type:
139 case DW_TAG_union_type:
140 case DW_TAG_ptr_to_member_type:
141 case DW_TAG_set_type:
142 case DW_TAG_subrange_type:
143 case DW_TAG_base_type:
144 case DW_TAG_const_type:
145 case DW_TAG_file_type:
146 case DW_TAG_packed_type:
147 case DW_TAG_volatile_type:
148 case DW_TAG_restrict_type:
149 case DW_TAG_interface_type:
150 case DW_TAG_unspecified_type:
151 case DW_TAG_shared_type:
152 return TagClass::Type;
154 case DW_TAG_subprogram:
155 return TagClass::Subprogram;
157 case DW_TAG_variable:
158 case DW_TAG_formal_parameter:
159 return TagClass::Variable;
161 case DW_TAG_lexical_block:
162 case DW_TAG_try_block:
163 case DW_TAG_catch_block:
164 case DW_TAG_inlined_subroutine:
165 case DW_TAG_with_stmt:
166 return TagClass::Scope;
168 case DW_TAG_namespace:
169 return TagClass::Namespace;
172 return TagClass::Unknown;
176 /** @brief Find the DWARF data class for a given DWARF data form
178 * This mapping is defined in the DWARF spec.
180 * @param form The form (values taken from the DWARF spec)
181 * @return An internal representation for the corresponding class
183 static FormClass classify_form(int form)
187 return FormClass::Address;
192 return FormClass::Block;
199 return FormClass::Constant;
202 return FormClass::String;
203 case DW_FORM_ref_addr:
208 case DW_FORM_ref_udata:
209 return FormClass::Reference;
211 case DW_FORM_flag_present:
212 return FormClass::Flag;
213 case DW_FORM_exprloc:
214 return FormClass::ExprLoc;
218 return FormClass::Unknown;
222 /** @brief Get the name of the tag of a given DIE
225 * @return name of the tag of this DIE
227 inline XBT_PRIVATE const char* tagname(Dwarf_Die* die)
229 return simgrid::dwarf::tagname(dwarf_tag(die));
233 } // namespace simgrid
237 /** @brief Get an attribute of a given DIE as a string
240 * @param attribute attribute
241 * @return value of the given attribute of the given DIE
243 static const char* MC_dwarf_attr_integrate_string(Dwarf_Die* die, int attribute)
245 Dwarf_Attribute attr;
246 if (not dwarf_attr_integrate(die, attribute, &attr))
249 return dwarf_formstring(&attr);
252 static Dwarf_Off MC_dwarf_attr_dieoffset(Dwarf_Die* die, int attribute)
254 Dwarf_Attribute attr;
255 if (dwarf_hasattr_integrate(die, attribute) == 0)
257 dwarf_attr_integrate(die, attribute, &attr);
258 Dwarf_Die subtype_die;
259 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
260 xbt_die("Could not find DIE");
261 return dwarf_dieoffset(&subtype_die);
264 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die* die, int attribute)
266 Dwarf_Attribute attr;
267 if (dwarf_hasattr_integrate(die, attribute) == 0)
269 dwarf_attr_integrate(die, DW_AT_type, &attr);
270 Dwarf_Die subtype_die;
271 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
272 xbt_die("Could not find DIE");
273 return dwarf_dieoffset(&subtype_die);
276 /** @brief Find the type/subtype (DW_AT_type) for a DIE
279 * @return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
281 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die)
283 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
286 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die* die, int attribute)
288 Dwarf_Attribute attr;
289 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
292 if (dwarf_formaddr(&attr, &value) == 0)
293 return (uint64_t)value;
298 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die* die, int attribute, uint64_t default_value)
300 Dwarf_Attribute attr;
301 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
302 return default_value;
304 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t)value : default_value;
307 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, bool integrate)
309 Dwarf_Attribute attr;
310 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr) : dwarf_attr(die, attribute, &attr)) == 0)
314 if (dwarf_formflag(&attr, &result))
315 xbt_die("Unexpected form for attribute %s", simgrid::dwarf::attrname(attribute));
319 /** @brief Find the default lower bound for a given language
321 * The default lower bound of an array (when DW_TAG_lower_bound
322 * is missing) depends on the language of the compilation unit.
324 * @param lang Language of the compilation unit (values defined in the DWARF spec)
325 * @return Default lower bound of an array in this compilation unit
327 static uint64_t MC_dwarf_default_lower_bound(int lang)
333 case DW_LANG_C_plus_plus:
337 case DW_LANG_ObjC_plus_plus:
343 case DW_LANG_Fortran77:
344 case DW_LANG_Fortran90:
345 case DW_LANG_Fortran95:
346 case DW_LANG_Modula2:
347 case DW_LANG_Pascal83:
349 case DW_LANG_Cobol74:
350 case DW_LANG_Cobol85:
353 xbt_die("No default DW_TAG_lower_bound for language %i and none given", lang);
358 /** @brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
361 * @param unit DIE of the compilation unit
362 * @return number of elements in the range
364 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit)
366 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type || dwarf_tag(die) == DW_TAG_subrange_type,
367 "MC_dwarf_subrange_element_count called with DIE of type %s", simgrid::dwarf::tagname(die));
369 // Use DW_TAG_count if present:
370 if (dwarf_hasattr_integrate(die, DW_AT_count))
371 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
372 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
374 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
375 // This is not really 0, but the code expects this (we do not know):
378 uint64_t upper_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, static_cast<uint64_t>(-1));
380 uint64_t lower_bound = 0;
381 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
382 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, static_cast<uint64_t>(-1));
384 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
385 return upper_bound - lower_bound + 1;
388 /** @brief Finds the number of elements in a array type (DW_TAG_array_type)
390 * The compilation unit might be needed because the default lower
391 * bound depends on the language of the compilation unit.
393 * @param die the DIE of the DW_TAG_array_type
394 * @param unit the DIE of the compilation unit
395 * @return number of elements in this array type
397 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit)
399 xbt_assert(dwarf_tag(die) == DW_TAG_array_type, "MC_dwarf_array_element_count called with DIE of type %s",
400 simgrid::dwarf::tagname(die));
405 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
406 int child_tag = dwarf_tag(&child);
407 if (child_tag == DW_TAG_subrange_type || child_tag == DW_TAG_enumeration_type)
408 result *= MC_dwarf_subrange_element_count(&child, unit);
415 /** Sort the variable by name and address.
417 * We could use boost::container::flat_set instead.
419 static bool MC_compare_variable(simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
421 int cmp = a.name.compare(b.name);
427 return a.address < b.address;
430 // ***** simgrid::mc::Type*
432 /** @brief Initialize the location of a member of a type
433 * (DW_AT_data_member_location of a DW_TAG_member).
435 * @param type a type (struct, class)
436 * @param member the member of the type
437 * @param child DIE of the member (DW_TAG_member)
439 static void MC_dwarf_fill_member_location(simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die* child)
441 if (dwarf_hasattr(child, DW_AT_data_bit_offset))
442 xbt_die("Can't groke DW_AT_data_bit_offset.");
444 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
445 if (type->type == DW_TAG_union_type)
447 xbt_die("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%" PRIx64 ">%s",
448 member->name.c_str(), (uint64_t)type->id, type->name.c_str());
451 Dwarf_Attribute attr;
452 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
453 int form = dwarf_whatform(&attr);
454 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
455 switch (form_class) {
456 case simgrid::dwarf::FormClass::ExprLoc:
457 case simgrid::dwarf::FormClass::Block:
458 // Location expression:
462 if (dwarf_getlocation(&attr, &expr, &len))
463 xbt_die("Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%" PRIx64
465 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
466 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr + len);
469 case simgrid::dwarf::FormClass::Constant:
470 // Offset from the base address of the object:
473 if (not dwarf_formudata(&attr, &offset))
474 member->offset(offset);
476 xbt_die("Cannot get %s location <%" PRIx64 ">%s", MC_dwarf_attr_integrate_string(child, DW_AT_name),
477 (uint64_t)type->id, type->name.c_str());
482 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to
483 // be possible in DWARF2 but I couldn't find its semantic in the spec)
484 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
488 /** @brief Populate the list of members of a type
490 * @param info ELF object containing the type DIE
491 * @param die DIE of the type
492 * @param unit DIE of the compilation unit containing the type DIE
493 * @param type the type
495 static void MC_dwarf_add_members(simgrid::mc::ObjectInformation* /*info*/, Dwarf_Die* die, Dwarf_Die* /*unit*/,
496 simgrid::mc::Type* type)
500 xbt_assert(type->members.empty());
501 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
502 int tag = dwarf_tag(&child);
503 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
505 // Skip declarations:
506 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
509 // Skip compile time constants:
510 if (dwarf_hasattr(&child, DW_AT_const_value))
513 // TODO, we should use another type (because is is not a type but a member)
514 simgrid::mc::Member member;
515 if (tag == DW_TAG_inheritance)
516 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
518 const char* name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
521 // Those base names are used by GCC and clang for virtual table pointers
522 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
523 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
524 boost::algorithm::starts_with(member.name, "__vptr."))
525 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
526 // A cleaner solution would be to check against the type:
528 // tag: DW_TAG_member
531 // # Type for a pointer to a vtable
532 // tag: DW_TAG_pointer_type
534 // # Type for a vtable:
535 // tag: DW_TAG_pointer_type
536 // name: "__vtbl_ptr_type"
538 // tag: DW_TAG_subroutine_type
540 // tag: DW_TAG_base_type
544 member.byte_size = MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
545 member.type_id = MC_dwarf_at_type(&child);
547 if (dwarf_hasattr(&child, DW_AT_data_bit_offset))
548 xbt_die("Can't groke DW_AT_data_bit_offset.");
550 MC_dwarf_fill_member_location(type, &member, &child);
552 if (not member.type_id)
553 xbt_die("Missing type for member %s of <%" PRIx64 ">%s", member.name.c_str(), (uint64_t)type->id,
556 type->members.push_back(std::move(member));
561 /** @brief Create a MC type object from a DIE
563 * @param info current object info object
564 * @param die DIE (for a given type)
565 * @param unit compilation unit of the current DIE
566 * @return MC representation of the type
568 static simgrid::mc::Type MC_dwarf_die_to_type(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
569 simgrid::mc::Frame* frame, const char* ns)
571 simgrid::mc::Type type;
572 type.type = dwarf_tag(die);
573 type.name = std::string();
574 type.element_count = -1;
577 type.id = dwarf_dieoffset(die);
579 const char* prefix = "";
581 case DW_TAG_structure_type:
584 case DW_TAG_union_type:
587 case DW_TAG_class_type:
594 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
595 if (name != nullptr) {
597 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
599 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
602 type.type_id = MC_dwarf_at_type(die);
604 // Some compilers do not emit DW_AT_byte_size for pointer_type,
605 // so we fill this. We currently assume that the model-checked process is in
606 // the same architecture..
607 if (type.type == DW_TAG_pointer_type)
608 type.byte_size = sizeof(void*);
610 // Computation of the byte_size
611 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
612 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
613 else if (type.type == DW_TAG_array_type || type.type == DW_TAG_structure_type || type.type == DW_TAG_class_type) {
615 if (dwarf_aggregate_size(die, &size) == 0)
616 type.byte_size = size;
620 case DW_TAG_array_type:
621 type.element_count = MC_dwarf_array_element_count(die, unit);
622 // TODO, handle DW_byte_stride and (not) DW_bit_stride
625 case DW_TAG_pointer_type:
626 case DW_TAG_reference_type:
627 case DW_TAG_rvalue_reference_type:
630 case DW_TAG_structure_type:
631 case DW_TAG_union_type:
632 case DW_TAG_class_type:
633 MC_dwarf_add_members(info, die, unit, &type);
634 MC_dwarf_handle_children(info, die, unit, frame,
635 ns ? simgrid::xbt::string_printf("%s::%s", ns, name).c_str() : type.name.c_str());
639 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
646 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
647 simgrid::mc::Frame* frame, const char* ns)
649 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
650 auto& t = (info->types[type.id] = std::move(type));
651 if (not t.name.empty() && type.byte_size != 0)
652 info->full_types_by_name[t.name] = &t;
655 static int mc_anonymous_variable_index = 0;
657 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(simgrid::mc::ObjectInformation* info, Dwarf_Die* die,
658 Dwarf_Die* /*unit*/, simgrid::mc::Frame* frame,
661 // Skip declarations:
662 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
665 // Skip compile time constants:
666 if (dwarf_hasattr(die, DW_AT_const_value))
669 Dwarf_Attribute attr_location;
670 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
671 // No location: do not add it ?
674 std::unique_ptr<simgrid::mc::Variable> variable = std::unique_ptr<simgrid::mc::Variable>(new simgrid::mc::Variable());
675 variable->id = dwarf_dieoffset(die);
676 variable->global = frame == nullptr; // Can be override base on DW_AT_location
677 variable->object_info = info;
679 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
681 variable->name = name;
682 variable->type_id = MC_dwarf_at_type(die);
684 int form = dwarf_whatform(&attr_location);
685 simgrid::dwarf::FormClass form_class;
686 if (form == DW_FORM_sec_offset)
687 form_class = simgrid::dwarf::FormClass::Constant;
689 form_class = simgrid::dwarf::classify_form(form);
690 switch (form_class) {
691 case simgrid::dwarf::FormClass::ExprLoc:
692 case simgrid::dwarf::FormClass::Block:
693 // Location expression:
697 if (dwarf_getlocation(&attr_location, &expr, &len)) {
698 xbt_die("Could not read location expression in DW_AT_location "
699 "of variable <%" PRIx64 ">%s",
700 (uint64_t)variable->id, variable->name.c_str());
703 if (len == 1 && expr[0].atom == DW_OP_addr) {
704 variable->global = true;
705 uintptr_t offset = (uintptr_t)expr[0].number;
706 uintptr_t base = (uintptr_t)info->base_address();
707 variable->address = (void*)(base + offset);
709 variable->location_list = {
710 simgrid::dwarf::LocationListEntry(simgrid::dwarf::DwarfExpression(expr, expr + len))};
715 case simgrid::dwarf::FormClass::LocListPtr:
716 case simgrid::dwarf::FormClass::Constant:
717 // Reference to location list:
718 variable->location_list = simgrid::dwarf::location_list(*info, attr_location);
722 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
723 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
726 // Handle start_scope:
727 if (dwarf_hasattr(die, DW_AT_start_scope)) {
728 Dwarf_Attribute attr;
729 dwarf_attr(die, DW_AT_start_scope, &attr);
730 form = dwarf_whatform(&attr);
731 form_class = simgrid::dwarf::classify_form(form);
732 if (form_class == simgrid::dwarf::FormClass::Constant) {
734 variable->start_scope = dwarf_formudata(&attr, &value) == 0 ? (size_t)value : 0;
736 // TODO: FormClass::RangeListPtr
737 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
738 (unsigned)form_class, name == nullptr ? "?" : name);
742 if (ns && variable->global)
743 variable->name = std::string(ns) + "::" + variable->name;
745 // The current code needs a variable name,
746 // generate a fake one:
747 if (variable->name.empty()) {
748 variable->name = "@anonymous#" + std::to_string(mc_anonymous_variable_index);
749 mc_anonymous_variable_index++;
754 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
755 simgrid::mc::Frame* frame, const char* ns)
757 std::unique_ptr<simgrid::mc::Variable> variable = MC_die_to_variable(info, die, unit, frame, ns);
760 // Those arrays are sorted later:
761 if (variable->global)
762 info->global_variables.push_back(std::move(*variable));
763 else if (frame != nullptr)
764 frame->variables.push_back(std::move(*variable));
766 xbt_die("No frame for this local variable");
769 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
770 simgrid::mc::Frame* parent_frame, const char* ns)
772 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
773 int tag = dwarf_tag(die);
774 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
776 // (Template) Subprogram declaration:
777 if (klass == simgrid::dwarf::TagClass::Subprogram && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
780 if (klass == simgrid::dwarf::TagClass::Scope)
781 xbt_assert(parent_frame, "No parent scope for this scope");
783 simgrid::mc::Frame frame;
785 frame.id = dwarf_dieoffset(die);
786 frame.object_info = info;
788 if (klass == simgrid::dwarf::TagClass::Subprogram) {
789 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
791 frame.name = std::string(ns) + "::" + name;
796 frame.abstract_origin_id = MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
798 // This is the base address for DWARF addresses.
799 // Relocated addresses are offset from this base address.
800 // See DWARF4 spec 7.5
801 std::uint64_t base = (std::uint64_t)info->base_address();
803 // TODO, support DW_AT_ranges
804 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
805 frame.range.begin() = low_pc ? (std::uint64_t)base + low_pc : 0;
808 Dwarf_Attribute attr;
809 if (not dwarf_attr_integrate(die, DW_AT_high_pc, &attr))
810 xbt_die("Missing DW_AT_high_pc matching with DW_AT_low_pc");
815 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
817 // DW_AT_high_pc if an offset from the low_pc:
818 case simgrid::dwarf::FormClass::Constant:
820 if (dwarf_formsdata(&attr, &offset) != 0)
821 xbt_die("Could not read constant");
822 frame.range.end() = frame.range.begin() + offset;
825 // DW_AT_high_pc is a relocatable address:
826 case simgrid::dwarf::FormClass::Address:
827 if (dwarf_formaddr(&attr, &high_pc) != 0)
828 xbt_die("Could not read address");
829 frame.range.end() = base + high_pc;
833 xbt_die("Unexpected class for DW_AT_high_pc");
837 if (klass == simgrid::dwarf::TagClass::Subprogram) {
838 Dwarf_Attribute attr_frame_base;
839 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
840 frame.frame_base_location = simgrid::dwarf::location_list(*info, attr_frame_base);
844 MC_dwarf_handle_children(info, die, unit, &frame, ns);
846 // We sort them in order to have an (somewhat) efficient by name
848 boost::range::sort(frame.variables, MC_compare_variable);
851 if (klass == simgrid::dwarf::TagClass::Subprogram)
852 info->subprograms[frame.id] = std::move(frame);
853 else if (klass == simgrid::dwarf::TagClass::Scope)
854 parent_frame->scopes.push_back(std::move(frame));
857 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
858 simgrid::mc::Frame* frame, const char* ns)
860 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
862 xbt_die("Unexpected namespace in a subprogram");
863 char* new_ns = ns == nullptr ? xbt_strdup(name) : bprintf("%s::%s", ns, name);
864 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
868 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
869 simgrid::mc::Frame* frame, const char* ns)
871 // For each child DIE:
874 for (res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child))
875 MC_dwarf_handle_die(info, &child, unit, frame, ns);
878 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
879 simgrid::mc::Frame* frame, const char* ns)
881 int tag = dwarf_tag(die);
882 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
886 case simgrid::dwarf::TagClass::Type:
887 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
890 // Subprogram or scope:
891 case simgrid::dwarf::TagClass::Subprogram:
892 case simgrid::dwarf::TagClass::Scope:
893 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
897 case simgrid::dwarf::TagClass::Variable:
898 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
901 case simgrid::dwarf::TagClass::Namespace:
902 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
910 static Elf64_Half get_type(Elf* elf)
912 Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
914 return ehdr64->e_type;
915 Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
917 return ehdr32->e_type;
918 xbt_die("Could not get ELF heeader");
921 static void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
923 // For each compilation unit:
924 Dwarf_Off offset = 0;
925 Dwarf_Off next_offset = 0;
928 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) == 0) {
930 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
931 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
932 offset = next_offset;
936 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
938 * This build-id may is used to locate an external debug (DWARF) file
941 * @param elf libelf handle for an ELF file
942 * @return build-id for this ELF file (or an empty vector if none is found)
944 static std::vector<char> get_build_id(Elf* elf)
947 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
948 // found in a PT_NOTE entry in the program header table.
951 if (elf_getphdrnum(elf, &phnum) != 0)
952 xbt_die("Could not read program headers");
954 // Iterate over the program headers and find the PT_NOTE ones:
955 for (size_t i = 0; i < phnum; ++i) {
957 GElf_Phdr* phdr = gelf_getphdr(elf, i, &phdr_temp);
958 if (phdr->p_type != PT_NOTE)
961 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
963 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
965 while (pos < data->d_size) {
967 // Location of the name within Elf_Data:
970 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
971 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
972 // (a namespace and a type within this namespace):
973 if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU") &&
974 memcmp((char*)data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
975 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
976 char* start = (char*)data->d_buf + desc_pos;
977 char* end = (char*)start + nhdr.n_descsz;
978 return std::vector<char>(start, end);
983 return std::vector<char>();
986 static char hexdigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
988 /** Binary data to hexadecimal */
989 static inline std::array<char, 2> to_hex(std::uint8_t byte)
991 // Horrid double braces!
992 // Apparently, this is needed in C++11 (not in C++14).
993 return {{hexdigits[byte >> 4], hexdigits[byte & 0xF]}};
996 /** Binary data to hexadecimal */
997 static std::string to_hex(const char* data, std::size_t count)
1000 res.resize(2 * count);
1001 for (std::size_t i = 0; i < count; i++) {
1002 std::array<char, 2> hex_byte = to_hex(data[i]);
1003 for (int j = 0; j < 2; ++j)
1004 res[2 * i + j] = hex_byte[j];
1009 /** Binary data to hexadecimal */
1010 static std::string to_hex(std::vector<char> const& data)
1012 return to_hex(data.data(), data.size());
1015 /** Base directories for external debug files */
1016 static const char* debug_paths[] = {
1018 "/usr/local/lib/debug/",
1021 /** Locate an external debug file from the NT_GNU_BUILD_ID
1023 * This is one of the mechanisms used for
1024 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
1027 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
1028 static std::string find_by_build_id(std::vector<char> id)
1030 std::string filename;
1031 std::string hex = to_hex(id);
1032 for (const char* const& debug_path : debug_paths) {
1034 filename = std::string(debug_path) + ".build-id/" + to_hex(id.data(), 1) + '/' +
1035 to_hex(id.data() + 1, id.size() - 1) + ".debug";
1036 XBT_DEBUG("Checking debug file: %s", filename.c_str());
1037 if (access(filename.c_str(), F_OK) == 0) {
1038 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
1042 XBT_DEBUG("Not debuf info found for build ID %s\n", hex.data());
1043 return std::string();
1046 /** @brief Populate the debugging informations of the given ELF object
1048 * Read the DWARf information of the EFFL object and populate the
1049 * lists of types, variables, functions.
1051 static void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
1053 if (elf_version(EV_CURRENT) == EV_NONE)
1054 xbt_die("libelf initialization error");
1056 // Open the ELF file:
1057 int fd = open(info->file_name.c_str(), O_RDONLY);
1059 xbt_die("Could not open file %s", info->file_name.c_str());
1060 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
1062 xbt_die("Not an ELF file");
1063 Elf_Kind kind = elf_kind(elf);
1064 if (kind != ELF_K_ELF)
1065 xbt_die("Not an ELF file");
1067 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
1068 Elf64_Half type = get_type(elf);
1069 if (type == ET_EXEC)
1070 info->flags |= simgrid::mc::ObjectInformation::Executable;
1072 // Read DWARF debug information in the file:
1073 Dwarf* dwarf = dwarf_begin_elf(elf, DWARF_C_READ, nullptr);
1074 if (dwarf != nullptr) {
1075 read_dwarf_info(info, dwarf);
1083 // If there was no DWARF in the file, try to find it in a separate file.
1084 // Different methods might be used to store the DWARF informations:
1085 // * GNU NT_GNU_BUILD_ID
1087 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1088 // for reference of what we are doing.
1090 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1091 // use this ID to find the file in some known locations in the filesystem.
1092 std::vector<char> build_id = get_build_id(elf);
1093 if (not build_id.empty()) {
1097 // Find the debug file using the build id:
1098 std::string debug_file = find_by_build_id(build_id);
1099 if (debug_file.empty()) {
1100 std::string hex = to_hex(build_id);
1101 xbt_die("Missing debug info for %s with build-id %s\n"
1102 "You might want to install the suitable debugging package.\n",
1103 info->file_name.c_str(), hex.c_str());
1106 // Load the DWARF info from this file:
1107 XBT_DEBUG("Load DWARF for %s from %s", info->file_name.c_str(), debug_file.c_str());
1108 fd = open(debug_file.c_str(), O_RDONLY);
1110 xbt_die("Could not open file %s", debug_file.c_str());
1111 dwarf = dwarf_begin(fd, DWARF_C_READ);
1112 if (dwarf == nullptr)
1113 xbt_die("No DWARF info in %s for %s", debug_file.c_str(), info->file_name.c_str());
1114 read_dwarf_info(info, dwarf);
1120 // TODO, try to find DWARF info using .gnu_debuglink.
1124 xbt_die("Debugging information not found for %s\n"
1125 "Try recompiling with -g\n",
1126 info->file_name.c_str());
1129 // ***** Functions index
1131 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1133 info->functions_index.clear();
1135 for (auto& e : info->subprograms) {
1136 if (e.second.range.begin() == 0)
1138 simgrid::mc::FunctionIndexEntry entry;
1139 entry.low_pc = (void*)e.second.range.begin();
1140 entry.function = &e.second;
1141 info->functions_index.push_back(entry);
1144 info->functions_index.shrink_to_fit();
1146 // Sort the array by low_pc:
1147 boost::range::sort(info->functions_index,
1148 [](simgrid::mc::FunctionIndexEntry const& a, simgrid::mc::FunctionIndexEntry const& b) {
1149 return a.low_pc < b.low_pc;
1153 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1155 // Someone needs this to be sorted but who?
1156 boost::range::sort(info->global_variables, MC_compare_variable);
1158 for (simgrid::mc::Variable& variable : info->global_variables)
1159 if (variable.type_id)
1160 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1163 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1166 if (scope->tag == DW_TAG_inlined_subroutine) {
1167 // Attach correct namespaced name in inlined subroutine:
1168 auto i = info->subprograms.find(scope->abstract_origin_id);
1169 xbt_assert(i != info->subprograms.end(), "Could not lookup abstract origin %" PRIx64,
1170 (std::uint64_t)scope->abstract_origin_id);
1171 scope->name = i->second.name;
1175 for (simgrid::mc::Variable& variable : scope->variables)
1176 if (variable.type_id)
1177 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1179 // Recursive post-processing of nested-scopes:
1180 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1181 mc_post_process_scope(info, &nested_scope);
1184 static simgrid::mc::Type* MC_resolve_type(simgrid::mc::ObjectInformation* info, unsigned type_id)
1188 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1189 if (type == nullptr)
1192 // We already have the information on the type:
1193 if (type->byte_size != 0)
1196 // Don't have a name, we can't find a more complete version:
1197 if (type->name.empty())
1200 // Try to find a more complete description of the type:
1201 // We need to fix in order to support C++.
1202 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(info->full_types_by_name, type->name);
1208 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1210 // Lookup "subtype" field:
1211 for (auto& i : info->types) {
1212 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1213 for (simgrid::mc::Member& member : i.second.members)
1214 member.type = MC_resolve_type(info, member.type_id);
1221 /** @brief Finds informations about a given shared object/executable */
1222 std::shared_ptr<simgrid::mc::ObjectInformation> createObjectInformation(std::vector<simgrid::xbt::VmMap> const& maps,
1225 std::shared_ptr<simgrid::mc::ObjectInformation> result = std::make_shared<simgrid::mc::ObjectInformation>();
1226 result->file_name = name;
1227 simgrid::mc::find_object_address(maps, result.get());
1228 MC_load_dwarf(result.get());
1229 MC_post_process_variables(result.get());
1230 MC_post_process_types(result.get());
1231 for (auto& entry : result.get()->subprograms)
1232 mc_post_process_scope(result.get(), &entry.second);
1233 MC_make_functions_index(result.get());
1237 /*************************************************************************/
1239 void postProcessObjectInformation(simgrid::mc::RemoteClient* process, simgrid::mc::ObjectInformation* info)
1241 for (auto& t : info->types) {
1243 simgrid::mc::Type* type = &(t.second);
1244 simgrid::mc::Type* subtype = type;
1245 while (subtype->type == DW_TAG_typedef || subtype->type == DW_TAG_volatile_type ||
1246 subtype->type == DW_TAG_const_type)
1247 if (subtype->subtype)
1248 subtype = subtype->subtype;
1252 // Resolve full_type:
1253 if (not subtype->name.empty() && subtype->byte_size == 0)
1254 for (auto const& object_info : process->object_infos) {
1255 auto i = object_info->full_types_by_name.find(subtype->name);
1256 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1257 type->full_type = i->second;
1262 type->full_type = subtype;
1267 } // namespace simgrid
1272 /** Convert a DWARF register into a libunwind register
1274 * DWARF and libunwind does not use the same convention for numbering the
1275 * registers on some architectures. The function makes the necessary
1278 int dwarf_register_to_libunwind(int dwarf_register)
1280 #if defined(__x86_64__)
1281 // It seems for this arch, DWARF and libunwind agree in the numbering:
1282 return dwarf_register;
1283 #elif defined(__i386__)
1284 // Couldn't find the authoritative source of information for this.
1285 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1286 switch (dwarf_register) {
1306 return UNW_X86_EFLAGS;
1336 xbt_die("Bad/unknown register number.");
1339 #error This architecture is not supported yet for DWARF expression evaluation.
1343 } // namespace dwarf
1344 } // namespace simgrid