1 /* Copyright (c) 2008-2015. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
13 #include <boost/range/algorithm.hpp>
17 #define DW_LANG_Objc DW_LANG_ObjC /* fix spelling error in older dwarf.h */
19 #include <elfutils/libdw.h>
21 #include <boost/algorithm/string/predicate.hpp>
23 #include <simgrid_config.h>
24 #include "src/simgrid/util.hpp"
26 #include <xbt/sysdep.h>
28 #include "src/mc/mc_private.h"
29 #include "src/mc/mc_dwarf.hpp"
31 #include "src/mc/Process.hpp"
32 #include "src/mc/ObjectInformation.hpp"
33 #include "src/mc/Variable.hpp"
35 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dwarf, mc, "DWARF processing");
37 /** \brief The default DW_TAG_lower_bound for a given DW_AT_language.
39 * The default for a given language is defined in the DWARF spec.
41 * \param language constant as defined by the DWARf spec
43 static uint64_t MC_dwarf_default_lower_bound(int lang);
45 /** \brief Computes the the element_count of a DW_TAG_enumeration_type DIE
47 * This is the number of elements in a given array dimension.
49 * A reference of the compilation unit (DW_TAG_compile_unit) is
50 * needed because the default lower bound (when there is no DW_AT_lower_bound)
51 * depends of the language of the compilation unit (DW_AT_language).
53 * \param die DIE for the DW_TAG_enumeration_type or DW_TAG_subrange_type
54 * \param unit DIE of the DW_TAG_compile_unit
56 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit);
58 /** \brief Computes the number of elements of a given DW_TAG_array_type.
60 * \param die DIE for the DW_TAG_array_type
62 static uint64_t MC_dwarf_array_element_count(Dwarf_Die * die, Dwarf_Die * unit);
64 /** \brief Process a DIE
66 * \param info the resulting object fot the library/binary file (output)
67 * \param die the current DIE
68 * \param unit the DIE of the compile unit of the current DIE
69 * \param frame containing frame if any
71 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
72 Dwarf_Die * unit, simgrid::mc::Frame* frame,
75 /** \brief Process a type DIE
77 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
78 Dwarf_Die * unit, simgrid::mc::Frame* frame,
81 /** \brief Calls MC_dwarf_handle_die on all children of the given die
83 * \param info the resulting object fot the library/binary file (output)
84 * \param die the current DIE
85 * \param unit the DIE of the compile unit of the current DIE
86 * \param frame containing frame if any
88 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
89 Dwarf_Die * unit, simgrid::mc::Frame* frame,
92 /** \brief Handle a variable (DW_TAG_variable or other)
94 * \param info the resulting object fot the library/binary file (output)
95 * \param die the current DIE
96 * \param unit the DIE of the compile unit of the current DIE
97 * \param frame containing frame if any
99 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
100 Dwarf_Die * unit, simgrid::mc::Frame* frame,
103 /** \brief Get the DW_TAG_type of the DIE
106 * \return DW_TAG_type attribute as a new string (nullptr if none)
108 static std::uint64_t MC_dwarf_at_type(Dwarf_Die * die);
113 enum class TagClass {
122 /*** Class of forms defined in the DWARF standard */
123 enum class FormClass {
125 Address, // Location in the program's address space
126 Block, // Arbitrary block of bytes
129 Flag, // Boolean value
130 Reference, // Reference to another DIE
131 ExprLoc, // DWARF expression/location description
139 TagClass classify_tag(int tag)
143 case DW_TAG_array_type:
144 case DW_TAG_class_type:
145 case DW_TAG_enumeration_type:
147 case DW_TAG_pointer_type:
148 case DW_TAG_reference_type:
149 case DW_TAG_rvalue_reference_type:
150 case DW_TAG_string_type:
151 case DW_TAG_structure_type:
152 case DW_TAG_subroutine_type:
153 case DW_TAG_union_type:
154 case DW_TAG_ptr_to_member_type:
155 case DW_TAG_set_type:
156 case DW_TAG_subrange_type:
157 case DW_TAG_base_type:
158 case DW_TAG_const_type:
159 case DW_TAG_file_type:
160 case DW_TAG_packed_type:
161 case DW_TAG_volatile_type:
162 case DW_TAG_restrict_type:
163 case DW_TAG_interface_type:
164 case DW_TAG_unspecified_type:
165 case DW_TAG_shared_type:
166 return TagClass::Type;
168 case DW_TAG_subprogram:
169 return TagClass::Subprogram;
171 case DW_TAG_variable:
172 case DW_TAG_formal_parameter:
173 return TagClass::Variable;
175 case DW_TAG_lexical_block:
176 case DW_TAG_try_block:
177 case DW_TAG_catch_block:
178 case DW_TAG_inlined_subroutine:
179 case DW_TAG_with_stmt:
180 return TagClass::Scope;
182 case DW_TAG_namespace:
183 return TagClass::Namespace;
186 return TagClass::Unknown;
190 /** \brief Find the DWARF data class for a given DWARF data form
192 * This mapping is defined in the DWARF spec.
194 * \param form The form (values taken from the DWARF spec)
195 * \return An internal representation for the corresponding class
198 FormClass classify_form(int form)
202 return FormClass::Address;
207 return FormClass::Block;
214 return FormClass::Constant;
217 return FormClass::String;
218 case DW_FORM_ref_addr:
223 case DW_FORM_ref_udata:
224 return FormClass::Reference;
226 case DW_FORM_flag_present:
227 return FormClass::Flag;
228 case DW_FORM_exprloc:
229 return FormClass::ExprLoc;
233 return FormClass::Unknown;
237 /** \brief Get the name of the tag of a given DIE
240 * \return name of the tag of this DIE
243 const char *tagname(Dwarf_Die * die)
245 return simgrid::dwarf::tagname(dwarf_tag(die));
253 /** \brief Get an attribute of a given DIE as a string
256 * \param attribute attribute
257 * \return value of the given attribute of the given DIE
259 static const char *MC_dwarf_attr_integrate_string(Dwarf_Die * die,
262 Dwarf_Attribute attr;
263 if (!dwarf_attr_integrate(die, attribute, &attr))
266 return dwarf_formstring(&attr);
269 /** \brief Get the linkage name of a DIE.
271 * Use either DW_AT_linkage_name or DW_AT_MIPS_linkage_name.
272 * DW_AT_linkage_name is standardized since DWARF 4.
273 * Before this version of DWARF, the MIPS extensions
274 * DW_AT_MIPS_linkage_name is used (at least by GCC).
277 * \return linkage name of the given DIE (or nullptr)
279 static const char *MC_dwarf_at_linkage_name(Dwarf_Die * die)
281 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_linkage_name);
283 name = MC_dwarf_attr_integrate_string(die, DW_AT_MIPS_linkage_name);
287 static Dwarf_Off MC_dwarf_attr_dieoffset(Dwarf_Die * die, int attribute)
289 Dwarf_Attribute attr;
290 if (dwarf_hasattr_integrate(die, attribute) == 0)
292 dwarf_attr_integrate(die, attribute, &attr);
293 Dwarf_Die subtype_die;
294 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
295 xbt_die("Could not find DIE");
296 return dwarf_dieoffset(&subtype_die);
299 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die * die,
302 Dwarf_Attribute attr;
303 if (dwarf_hasattr_integrate(die, attribute) == 0)
305 dwarf_attr_integrate(die, DW_AT_type, &attr);
306 Dwarf_Die subtype_die;
307 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
308 xbt_die("Could not find DIE");
309 return dwarf_dieoffset(&subtype_die);
312 /** \brief Find the type/subtype (DW_AT_type) for a DIE
315 * \return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
318 std::uint64_t MC_dwarf_at_type(Dwarf_Die * die)
320 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
323 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die * die, int attribute)
325 Dwarf_Attribute attr;
326 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
329 if (dwarf_formaddr(&attr, &value) == 0)
330 return (uint64_t) value;
335 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die * die, int attribute,
336 uint64_t default_value)
338 Dwarf_Attribute attr;
339 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
340 return default_value;
342 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr),
343 &value) == 0 ? (uint64_t) value : default_value;
346 static bool MC_dwarf_attr_flag(Dwarf_Die * die, int attribute, bool integrate)
348 Dwarf_Attribute attr;
349 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr)
350 : dwarf_attr(die, attribute, &attr)) == 0)
354 if (dwarf_formflag(&attr, &result))
355 xbt_die("Unexpected form for attribute %s",
356 simgrid::dwarf::attrname(attribute));
360 /** @brief Find the default lower bound for a given language
362 * The default lower bound of an array (when DW_TAG_lower_bound
363 * is missing) depends on the language of the compilation unit.
365 * @param lang Language of the compilation unit (values defined in the DWARF spec)
366 * @return Default lower bound of an array in this compilation unit
368 static uint64_t MC_dwarf_default_lower_bound(int lang)
374 case DW_LANG_C_plus_plus:
378 case DW_LANG_ObjC_plus_plus:
384 case DW_LANG_Fortran77:
385 case DW_LANG_Fortran90:
386 case DW_LANG_Fortran95:
387 case DW_LANG_Modula2:
388 case DW_LANG_Pascal83:
390 case DW_LANG_Cobol74:
391 case DW_LANG_Cobol85:
394 xbt_die("No default DW_TAG_lower_bound for language %i and none given",
400 /** \brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
403 * \param unit DIE of the compilation unit
404 * \return number of elements in the range
406 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die * die,
409 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type
410 || dwarf_tag(die) == DW_TAG_subrange_type,
411 "MC_dwarf_subrange_element_count called with DIE of type %s",
412 simgrid::dwarf::tagname(die));
414 // Use DW_TAG_count if present:
415 if (dwarf_hasattr_integrate(die, DW_AT_count))
416 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
417 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
419 if (!dwarf_hasattr_integrate(die, DW_AT_upper_bound))
420 // This is not really 0, but the code expects this (we do not know):
423 uint64_t upper_bound =
424 MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, -1);
426 uint64_t lower_bound = 0;
427 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
428 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, -1);
430 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
431 return upper_bound - lower_bound + 1;
434 /** \brief Finds the number of elements in a array type (DW_TAG_array_type)
436 * The compilation unit might be needed because the default lower
437 * bound depends on the language of the compilation unit.
439 * \param die the DIE of the DW_TAG_array_type
440 * \param unit the DIE of the compilation unit
441 * \return number of elements in this array type
443 static uint64_t MC_dwarf_array_element_count(Dwarf_Die * die, Dwarf_Die * unit)
445 xbt_assert(dwarf_tag(die) == DW_TAG_array_type,
446 "MC_dwarf_array_element_count called with DIE of type %s",
447 simgrid::dwarf::tagname(die));
452 for (res = dwarf_child(die, &child); res == 0;
453 res = dwarf_siblingof(&child, &child)) {
454 int child_tag = dwarf_tag(&child);
455 if (child_tag == DW_TAG_subrange_type
456 || child_tag == DW_TAG_enumeration_type)
457 result *= MC_dwarf_subrange_element_count(&child, unit);
464 /** Sort the variable by name and address.
466 * We could use boost::container::flat_set instead.
468 static bool MC_compare_variable(
469 simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
471 int cmp = strcmp(a.name.c_str(), b.name.c_str());
477 return a.address < b.address;
480 // ***** simgrid::mc::Type*
482 /** \brief Initialize the location of a member of a type
483 * (DW_AT_data_member_location of a DW_TAG_member).
485 * \param type a type (struct, class)
486 * \param member the member of the type
487 * \param child DIE of the member (DW_TAG_member)
489 static void MC_dwarf_fill_member_location(
490 simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die * child)
492 if (dwarf_hasattr(child, DW_AT_data_bit_offset))
493 xbt_die("Can't groke DW_AT_data_bit_offset.");
495 if (!dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
496 if (type->type == DW_TAG_union_type)
499 ("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%"
500 PRIx64 ">%s", member->name.c_str(),
501 (uint64_t) type->id, type->name.c_str());
504 Dwarf_Attribute attr;
505 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
506 int form = dwarf_whatform(&attr);
507 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
508 switch (form_class) {
509 case simgrid::dwarf::FormClass::ExprLoc:
510 case simgrid::dwarf::FormClass::Block:
511 // Location expression:
515 if (dwarf_getlocation(&attr, &expr, &len))
517 ("Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%"
518 PRIx64 ">%s", MC_dwarf_attr_integrate_string(child, DW_AT_name),
519 (uint64_t) type->id, type->name.c_str());
520 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr+len);
523 case simgrid::dwarf::FormClass::Constant:
524 // Offset from the base address of the object:
527 if (!dwarf_formudata(&attr, &offset))
528 member->offset(offset);
530 xbt_die("Cannot get %s location <%" PRIx64 ">%s",
531 MC_dwarf_attr_integrate_string(child, DW_AT_name),
532 (uint64_t) type->id, type->name.c_str());
535 case simgrid::dwarf::FormClass::LocListPtr:
536 // Reference to a location list:
538 case simgrid::dwarf::FormClass::Reference:
539 // It's supposed to be possible in DWARF2 but I couldn't find its semantic
542 xbt_die("Can't handle form class (%i) / form 0x%x as DW_AT_member_location",
543 (int) form_class, form);
548 /** \brief Populate the list of members of a type
550 * \param info ELF object containing the type DIE
551 * \param die DIE of the type
552 * \param unit DIE of the compilation unit containing the type DIE
553 * \param type the type
555 static void MC_dwarf_add_members(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
556 Dwarf_Die * unit, simgrid::mc::Type* type)
560 xbt_assert(type->members.empty());
561 for (res = dwarf_child(die, &child); res == 0;
562 res = dwarf_siblingof(&child, &child)) {
563 int tag = dwarf_tag(&child);
564 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
566 // Skip declarations:
567 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
570 // Skip compile time constants:
571 if (dwarf_hasattr(&child, DW_AT_const_value))
574 // TODO, we should use another type (because is is not a type but a member)
575 simgrid::mc::Member member;
576 if (tag == DW_TAG_inheritance)
577 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
579 const char *name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
582 // Those base names are used by GCC and clang for virtual table pointers
583 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
584 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
585 boost::algorithm::starts_with(member.name, "__vptr."))
586 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
587 // A cleaner solution would be to check against the type:
589 // tag: DW_TAG_member
592 // # Type for a pointer to a vtable
593 // tag: DW_TAG_pointer_type
595 // # Type for a vtable:
596 // tag: DW_TAG_pointer_type
597 // name: "__vtbl_ptr_type"
599 // tag: DW_TAG_subroutine_type
601 // tag: DW_TAG_base_type
606 MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
607 member.type_id = MC_dwarf_at_type(&child);
609 if (dwarf_hasattr(&child, DW_AT_data_bit_offset))
610 xbt_die("Can't groke DW_AT_data_bit_offset.");
612 MC_dwarf_fill_member_location(type, &member, &child);
615 xbt_die("Missing type for member %s of <%" PRIx64 ">%s",
617 (uint64_t) type->id, type->name.c_str());
619 type->members.push_back(std::move(member));
624 /** \brief Create a MC type object from a DIE
626 * \param info current object info object
627 * \param DIE (for a given type);
628 * \param unit compilation unit of the current DIE
629 * \return MC representation of the type
631 static simgrid::mc::Type MC_dwarf_die_to_type(
632 simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
633 Dwarf_Die * unit, simgrid::mc::Frame* frame,
636 simgrid::mc::Type type;
637 type.type = dwarf_tag(die);
638 type.name = std::string();
639 type.element_count = -1;
642 type.id = dwarf_dieoffset(die);
644 const char *prefix = "";
646 case DW_TAG_structure_type:
649 case DW_TAG_union_type:
652 case DW_TAG_class_type:
659 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
660 if (name != nullptr) {
661 char* full_name = ns ? bprintf("%s%s::%s", prefix, ns, name) :
662 bprintf("%s%s", prefix, name);
663 type.name = std::string(full_name);
667 type.type_id = MC_dwarf_at_type(die);
669 // Some compilers do not emit DW_AT_byte_size for pointer_type,
670 // so we fill this. We currently assume that the model-checked process is in
671 // the same architecture..
672 if (type.type == DW_TAG_pointer_type)
673 type.byte_size = sizeof(void*);
675 // Computation of the byte_size;
676 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
677 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
678 else if (type.type == DW_TAG_array_type
679 || type.type == DW_TAG_structure_type
680 || type.type == DW_TAG_class_type) {
682 if (dwarf_aggregate_size(die, &size) == 0)
683 type.byte_size = size;
687 case DW_TAG_array_type:
688 type.element_count = MC_dwarf_array_element_count(die, unit);
689 // TODO, handle DW_byte_stride and (not) DW_bit_stride
692 case DW_TAG_pointer_type:
693 case DW_TAG_reference_type:
694 case DW_TAG_rvalue_reference_type:
697 case DW_TAG_structure_type:
698 case DW_TAG_union_type:
699 case DW_TAG_class_type:
700 MC_dwarf_add_members(info, die, unit, &type);
701 char *new_ns = ns == nullptr ? xbt_strdup(type.name.c_str())
702 : bprintf("%s::%s", ns, name);
703 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
711 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
712 Dwarf_Die * unit, simgrid::mc::Frame* frame,
715 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
716 auto& t = (info->types[type.id] = std::move(type));
717 if (!t.name.empty() && type.byte_size != 0)
718 info->full_types_by_name[t.name] = &t;
721 static int mc_anonymous_variable_index = 0;
723 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(
724 simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
725 Dwarf_Die * unit, simgrid::mc::Frame* frame,
728 // Skip declarations:
729 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
732 // Skip compile time constants:
733 if (dwarf_hasattr(die, DW_AT_const_value))
736 Dwarf_Attribute attr_location;
737 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
738 // No location: do not add it ?
741 std::unique_ptr<simgrid::mc::Variable> variable =
742 std::unique_ptr<simgrid::mc::Variable>(new simgrid::mc::Variable());
743 variable->id = dwarf_dieoffset(die);
744 variable->global = frame == nullptr; // Can be override base on DW_AT_location
745 variable->object_info = info;
747 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
749 variable->name = name;
750 variable->type_id = MC_dwarf_at_type(die);
752 int form = dwarf_whatform(&attr_location);
753 simgrid::dwarf::FormClass form_class;
754 if (form == DW_FORM_sec_offset)
755 form_class = simgrid::dwarf::FormClass::Constant;
757 form_class = simgrid::dwarf::classify_form(form);
758 switch (form_class) {
759 case simgrid::dwarf::FormClass::ExprLoc:
760 case simgrid::dwarf::FormClass::Block:
761 // Location expression:
765 if (dwarf_getlocation(&attr_location, &expr, &len)) {
767 "Could not read location expression in DW_AT_location "
768 "of variable <%" PRIx64 ">%s",
769 (uint64_t) variable->id,
770 variable->name.c_str());
773 if (len == 1 && expr[0].atom == DW_OP_addr) {
774 variable->global = true;
775 uintptr_t offset = (uintptr_t) expr[0].number;
776 uintptr_t base = (uintptr_t) info->base_address();
777 variable->address = (void *) (base + offset);
779 variable->location_list = {
780 simgrid::dwarf::DwarfExpression(expr, expr + len) };
785 case simgrid::dwarf::FormClass::LocListPtr:
786 case simgrid::dwarf::FormClass::Constant:
787 // Reference to location list:
788 variable->location_list = simgrid::dwarf::location_list(
789 *info, attr_location);
793 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location "
794 "in <%" PRIx64 ">%s",
795 form, form, (int) form_class, (int) form_class,
796 (uint64_t) variable->id,
797 variable->name.c_str());
800 // Handle start_scope:
801 if (dwarf_hasattr(die, DW_AT_start_scope)) {
802 Dwarf_Attribute attr;
803 dwarf_attr(die, DW_AT_start_scope, &attr);
804 int form = dwarf_whatform(&attr);
805 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
806 switch (form_class) {
807 case simgrid::dwarf::FormClass::Constant:
810 variable->start_scope =
811 dwarf_formudata(&attr, &value) == 0 ? (size_t) value : 0;
815 case simgrid::dwarf::FormClass::RangeListPtr: // TODO
818 ("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s",
819 form, (int) form_class, name == nullptr ? "?" : name);
823 if (ns && variable->global)
825 std::string(ns) + "::" + variable->name;
827 // The current code needs a variable name,
828 // generate a fake one:
829 if (variable->name.empty())
831 "@anonymous#" + std::to_string(mc_anonymous_variable_index++);
836 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
837 Dwarf_Die * unit, simgrid::mc::Frame* frame,
840 std::unique_ptr<simgrid::mc::Variable> variable =
841 MC_die_to_variable(info, die, unit, frame, ns);
844 // Those arrays are sorted later:
845 else if (variable->global)
846 info->global_variables.push_back(std::move(*variable));
847 else if (frame != nullptr)
848 frame->variables.push_back(std::move(*variable));
850 xbt_die("No frame for this local variable");
853 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
854 Dwarf_Die * unit, simgrid::mc::Frame* parent_frame,
857 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
858 int tag = dwarf_tag(die);
859 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
861 // (Template) Subprogram declaration:
862 if (klass == simgrid::dwarf::TagClass::Subprogram
863 && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
866 if (klass == simgrid::dwarf::TagClass::Scope)
867 xbt_assert(parent_frame, "No parent scope for this scope");
869 simgrid::mc::Frame frame;
871 frame.id = dwarf_dieoffset(die);
872 frame.object_info = info;
874 if (klass == simgrid::dwarf::TagClass::Subprogram) {
875 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
877 frame.name = std::string(ns) + "::" + name;
882 frame.abstract_origin_id =
883 MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
885 // This is the base address for DWARF addresses.
886 // Relocated addresses are offset from this base address.
887 // See DWARF4 spec 7.5
888 std::uint64_t base = (std::uint64_t) info->base_address();
890 // TODO, support DW_AT_ranges
891 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
892 frame.range.begin() = low_pc ? (std::uint64_t) base + low_pc : 0;
895 Dwarf_Attribute attr;
896 if (!dwarf_attr_integrate(die, DW_AT_high_pc, &attr))
897 xbt_die("Missing DW_AT_high_pc matching with DW_AT_low_pc");
902 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
904 // DW_AT_high_pc if an offset from the low_pc:
905 case simgrid::dwarf::FormClass::Constant:
907 if (dwarf_formsdata(&attr, &offset) != 0)
908 xbt_die("Could not read constant");
909 frame.range.end() = frame.range.begin() + offset;
912 // DW_AT_high_pc is a relocatable address:
913 case simgrid::dwarf::FormClass::Address:
914 if (dwarf_formaddr(&attr, &high_pc) != 0)
915 xbt_die("Could not read address");
916 frame.range.end() = base + high_pc;
920 xbt_die("Unexpected class for DW_AT_high_pc");
925 if (klass == simgrid::dwarf::TagClass::Subprogram) {
926 Dwarf_Attribute attr_frame_base;
927 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
928 frame.frame_base_location = simgrid::dwarf::location_list(*info,
933 MC_dwarf_handle_children(info, die, unit, &frame, ns);
935 // We sort them in order to have an (somewhat) efficient by name
937 boost::range::sort(frame.variables, MC_compare_variable);
940 if (klass == simgrid::dwarf::TagClass::Subprogram)
941 info->subprograms[frame.id] = std::move(frame);
942 else if (klass == simgrid::dwarf::TagClass::Scope)
943 parent_frame->scopes.push_back(std::move(frame));
946 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info,
947 Dwarf_Die * die, Dwarf_Die * unit,
948 simgrid::mc::Frame* frame,
951 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
953 xbt_die("Unexpected namespace in a subprogram");
954 char *new_ns = ns == nullptr ? xbt_strdup(name)
955 : bprintf("%s::%s", ns, name);
956 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
960 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
961 Dwarf_Die * unit, simgrid::mc::Frame* frame,
964 // For each child DIE:
967 for (res = dwarf_child(die, &child); res == 0;
968 res = dwarf_siblingof(&child, &child))
969 MC_dwarf_handle_die(info, &child, unit, frame, ns);
972 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
973 Dwarf_Die * unit, simgrid::mc::Frame* frame,
976 int tag = dwarf_tag(die);
977 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
981 case simgrid::dwarf::TagClass::Type:
982 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
985 // Subprogram or scope:
986 case simgrid::dwarf::TagClass::Subprogram:
987 case simgrid::dwarf::TagClass::Scope:
988 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
992 case simgrid::dwarf::TagClass::Variable:
993 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
996 case simgrid::dwarf::TagClass::Namespace:
997 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
1007 Elf64_Half get_type(Elf* elf)
1009 Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
1011 return ehdr64->e_type;
1012 Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
1014 return ehdr32->e_type;
1015 xbt_die("Could not get ELF heeader");
1019 void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
1021 // For each compilation unit:
1022 Dwarf_Off offset = 0;
1023 Dwarf_Off next_offset = 0;
1026 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) ==
1029 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
1030 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
1031 offset = next_offset;
1035 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
1037 * This build-id may is used to locate an external debug (DWARF) file
1038 * for this ELF file.
1040 * @param elf libelf handle for an ELF file
1041 * @return build-id for this ELF file (or an empty vector if none is found)
1044 std::vector<char> get_build_id(Elf* elf)
1047 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
1048 // found in a PT_NOTE entry in the program header table.
1051 if (elf_getphdrnum (elf, &phnum) != 0)
1052 xbt_die("Could not read program headers");
1054 // Iterate over the program headers and find the PT_NOTE ones:
1055 for (size_t i = 0; i < phnum; ++i) {
1056 GElf_Phdr phdr_temp;
1057 GElf_Phdr *phdr = gelf_getphdr(elf, i, &phdr_temp);
1058 if (phdr->p_type != PT_NOTE)
1061 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
1063 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
1065 while (pos < data->d_size) {
1067 // Location of the name within Elf_Data:
1070 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
1071 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
1072 // (a namespace and a type within this namespace):
1073 if (nhdr.n_type == NT_GNU_BUILD_ID
1074 && nhdr.n_namesz == sizeof("GNU")
1075 && memcmp((char*) data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
1076 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
1077 char* start = (char*) data->d_buf + desc_pos;
1078 char* end = (char*) start + nhdr.n_descsz;
1079 return std::vector<char>(start, end);
1085 return std::vector<char>();
1088 static char hexdigits[16] = {
1089 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
1090 'a', 'b', 'c', 'd', 'e', 'f'
1093 /** Binary data to hexadecimal */
1095 std::array<char, 2> to_hex(std::uint8_t byte)
1097 // Horrid double braces!
1098 // Apparently, this is needed in C++11 (not in C++14).
1099 return { { hexdigits[byte >> 4], hexdigits[byte & 0xF] } };
1102 /** Binary data to hexadecimal */
1104 std::string to_hex(const char* data, std::size_t count)
1107 res.resize(2*count);
1108 for (std::size_t i = 0; i < count; i++) {
1109 std::array<char, 2> hex_byte = to_hex(data[i]);
1110 for (int j = 0; j < 2; ++j)
1111 res[2 * i + j] = hex_byte[j];
1116 /** Binary data to hexadecimal */
1118 std::string to_hex(std::vector<char> const& data)
1120 return to_hex(data.data(), data.size());
1123 /** Base directories for external debug files */
1125 const char* debug_paths[] = {
1127 "/usr/local/lib/debug/",
1130 /** Locate an external debug file from the NT_GNU_BUILD_ID
1132 * This is one of the mechanisms used for
1133 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
1136 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
1138 std::string find_by_build_id(std::vector<char> id)
1140 std::string filename;
1141 std::string hex = to_hex(id);
1142 for (const char* debug_path : debug_paths) {
1144 filename = std::string(debug_path) + ".build-id/"
1145 + to_hex(id.data(), 1) + '/'
1146 + to_hex(id.data() + 1, id.size() - 1) + ".debug";
1147 XBT_DEBUG("Checking debug file: %s", filename.c_str());
1148 if (access(filename.c_str(), F_OK) == 0) {
1149 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
1153 XBT_DEBUG("Not debuf info found for build ID %s\n", hex.data());
1154 return std::string();
1157 /** \brief Populate the debugging informations of the given ELF object
1159 * Read the DWARf information of the EFFL object and populate the
1160 * lists of types, variables, functions.
1163 void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
1165 if (elf_version(EV_CURRENT) == EV_NONE)
1166 xbt_die("libelf initialization error");
1168 // Open the ELF file:
1169 int fd = open(info->file_name.c_str(), O_RDONLY);
1171 xbt_die("Could not open file %s", info->file_name.c_str());
1172 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
1174 xbt_die("Not an ELF file");
1175 Elf_Kind kind = elf_kind(elf);
1176 if (kind != ELF_K_ELF)
1177 xbt_die("Not an ELF file");
1179 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
1180 Elf64_Half type = get_type(elf);
1181 if (type == ET_EXEC)
1182 info->flags |= simgrid::mc::ObjectInformation::Executable;
1184 // Read DWARF debug information in the file:
1185 Dwarf* dwarf = dwarf_begin_elf (elf, DWARF_C_READ, nullptr);
1186 if (dwarf != nullptr) {
1187 read_dwarf_info(info, dwarf);
1195 // If there was no DWARF in the file, try to find it in a separate file.
1196 // Different methods might be used to store the DWARF informations:
1197 // * GNU NT_GNU_BUILD_ID;
1198 // * .gnu_debuglink.
1199 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1200 // for reference of what we are doing.
1202 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1203 // use this ID to find the file in some known locations in the filesystem.
1204 std::vector<char> build_id = get_build_id(elf);
1205 if (!build_id.empty()) {
1209 // Find the debug file using the build id:
1210 std::string debug_file = find_by_build_id(build_id);
1211 if (debug_file.empty()) {
1212 std::string hex = to_hex(build_id);
1213 xbt_die("Missing debug info for %s with build-id %s\n"
1214 "You might want to install the suitable debugging package.\n",
1215 info->file_name.c_str(), hex.c_str());
1218 // Load the DWARF info from this file:
1219 XBT_DEBUG("Load DWARF for %s from %s",
1220 info->file_name.c_str(), debug_file.c_str());
1221 fd = open(debug_file.c_str(), O_RDONLY);
1223 xbt_die("Could not open file %s", debug_file.c_str());
1224 Dwarf* dwarf = dwarf_begin(fd, DWARF_C_READ);
1225 if (dwarf == nullptr)
1226 xbt_die("No DWARF info in %s for %s",
1227 debug_file.c_str(), info->file_name.c_str());
1228 read_dwarf_info(info, dwarf);
1234 // TODO, try to find DWARF info using .gnu_debuglink.
1238 xbt_die("Debugging information not found for %s\n"
1239 "Try recompiling with -g\n",
1240 info->file_name.c_str());
1243 // ***** Functions index
1245 static int MC_compare_frame_index_items(simgrid::mc::FunctionIndexEntry* a,
1246 simgrid::mc::FunctionIndexEntry* b)
1248 if (a->low_pc < b->low_pc)
1250 else if (a->low_pc == b->low_pc)
1256 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1258 info->functions_index.clear();
1260 for (auto& e : info->subprograms) {
1261 if (e.second.range.begin() == 0)
1263 simgrid::mc::FunctionIndexEntry entry;
1264 entry.low_pc = (void*) e.second.range.begin();
1265 entry.function = &e.second;
1266 info->functions_index.push_back(entry);
1269 info->functions_index.shrink_to_fit();
1271 // Sort the array by low_pc:
1272 boost::range::sort(info->functions_index,
1273 [](simgrid::mc::FunctionIndexEntry const& a,
1274 simgrid::mc::FunctionIndexEntry const& b)
1276 return a.low_pc < b.low_pc;
1280 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1282 // Someone needs this to be sorted but who?
1283 boost::range::sort(info->global_variables, MC_compare_variable);
1285 for(simgrid::mc::Variable& variable : info->global_variables)
1286 if (variable.type_id)
1287 variable.type = simgrid::util::find_map_ptr(
1288 info->types, variable.type_id);
1291 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1294 if (scope->tag == DW_TAG_inlined_subroutine) {
1295 // Attach correct namespaced name in inlined subroutine:
1296 auto i = info->subprograms.find(scope->abstract_origin_id);
1297 xbt_assert(i != info->subprograms.end(),
1298 "Could not lookup abstract origin %" PRIx64,
1299 (std::uint64_t) scope->abstract_origin_id);
1300 scope->name = i->second.name;
1304 for (simgrid::mc::Variable& variable : scope->variables)
1305 if (variable.type_id)
1306 variable.type = simgrid::util::find_map_ptr(
1307 info->types, variable.type_id);
1309 // Recursive post-processing of nested-scopes:
1310 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1311 mc_post_process_scope(info, &nested_scope);
1316 simgrid::mc::Type* MC_resolve_type(
1317 simgrid::mc::ObjectInformation* info, unsigned type_id)
1321 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1322 if (type == nullptr)
1325 // We already have the information on the type:
1326 if (type->byte_size != 0)
1329 // Don't have a name, we can't find a more complete version:
1330 if (type->name.empty())
1333 // Try to find a more complete description of the type:
1334 // We need to fix in order to support C++.
1335 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(
1336 info->full_types_by_name, type->name);
1342 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1344 // Lookup "subtype" field:
1345 for(auto& i : info->types) {
1346 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1347 for (simgrid::mc::Member& member : i.second.members)
1348 member.type = MC_resolve_type(info, member.type_id);
1355 /** \brief Finds informations about a given shared object/executable */
1356 std::shared_ptr<simgrid::mc::ObjectInformation> createObjectInformation(
1357 std::vector<simgrid::xbt::VmMap> const& maps, const char *name)
1359 std::shared_ptr<simgrid::mc::ObjectInformation> result =
1360 std::make_shared<simgrid::mc::ObjectInformation>();
1361 result->file_name = name;
1362 simgrid::mc::find_object_address(maps, result.get());
1363 MC_load_dwarf(result.get());
1364 MC_post_process_variables(result.get());
1365 MC_post_process_types(result.get());
1366 for (auto& entry : result.get()->subprograms)
1367 mc_post_process_scope(result.get(), &entry.second);
1368 MC_make_functions_index(result.get());
1372 /*************************************************************************/
1374 void postProcessObjectInformation(simgrid::mc::Process* process, simgrid::mc::ObjectInformation* info)
1376 for (auto& i : info->types) {
1378 simgrid::mc::Type* type = &(i.second);
1379 simgrid::mc::Type* subtype = type;
1380 while (subtype->type == DW_TAG_typedef
1381 || subtype->type == DW_TAG_volatile_type
1382 || subtype->type == DW_TAG_const_type)
1383 if (subtype->subtype)
1384 subtype = subtype->subtype;
1388 // Resolve full_type:
1389 if (!subtype->name.empty() && subtype->byte_size == 0)
1390 for (auto const& object_info : process->object_infos) {
1391 auto i = object_info->full_types_by_name.find(subtype->name);
1392 if (i != object_info->full_types_by_name.end()
1393 && !i->second->name.empty() && i->second->byte_size) {
1394 type->full_type = i->second;
1398 else type->full_type = subtype;
1409 /** Convert a DWARF register into a libunwind register
1411 * DWARF and libunwind does not use the same convention for numbering the
1412 * registers on some architectures. The function makes the necessary
1415 int dwarf_register_to_libunwind(int dwarf_register)
1417 #if defined(__x86_64__)
1418 // It seems for this arch, DWARF and libunwind agree in the numbering:
1419 return dwarf_register;
1420 #elif defined(__i386__)
1421 // Couldn't find the authoritative source of information for this.
1422 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1423 switch (dwarf_register) {
1443 return UNW_X86_EFLAGS;
1473 xbt_die("Bad/unknown register number.");
1476 #error This architecture is not supported yet for DWARF expression evaluation.