1 /* Copyright (c) 2008-2017. 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 "src/simgrid/util.hpp"
25 #include "xbt/string.hpp"
26 #include "xbt/sysdep.h"
27 #include <simgrid_config.h>
29 #include "src/mc/mc_dwarf.hpp"
30 #include "src/mc/mc_private.hpp"
32 #include "src/mc/ObjectInformation.hpp"
33 #include "src/mc/Variable.hpp"
34 #include "src/mc/remote/RemoteClient.hpp"
36 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dwarf, mc, "DWARF processing");
38 /** \brief The default DW_TAG_lower_bound for a given DW_AT_language.
40 * The default for a given language is defined in the DWARF spec.
42 * \param language constant as defined by the DWARf spec
44 static uint64_t MC_dwarf_default_lower_bound(int lang);
46 /** \brief Computes the the element_count of a DW_TAG_enumeration_type DIE
48 * This is the number of elements in a given array dimension.
50 * A reference of the compilation unit (DW_TAG_compile_unit) is
51 * needed because the default lower bound (when there is no DW_AT_lower_bound)
52 * depends of the language of the compilation unit (DW_AT_language).
54 * \param die DIE for the DW_TAG_enumeration_type or DW_TAG_subrange_type
55 * \param unit DIE of the DW_TAG_compile_unit
57 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit);
59 /** \brief Computes the number of elements of a given DW_TAG_array_type.
61 * \param die DIE for the DW_TAG_array_type
63 static uint64_t MC_dwarf_array_element_count(Dwarf_Die * die, Dwarf_Die * unit);
65 /** \brief Process a DIE
67 * \param info the resulting object fot the library/binary file (output)
68 * \param die the current DIE
69 * \param unit the DIE of the compile unit of the current DIE
70 * \param frame containing frame if any
72 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
73 Dwarf_Die * unit, simgrid::mc::Frame* frame,
76 /** \brief Process a type DIE
78 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
79 Dwarf_Die * unit, simgrid::mc::Frame* frame,
82 /** \brief Calls MC_dwarf_handle_die on all children of the given die
84 * \param info the resulting object fot the library/binary file (output)
85 * \param die the current DIE
86 * \param unit the DIE of the compile unit of the current DIE
87 * \param frame containing frame if any
89 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
90 Dwarf_Die * unit, simgrid::mc::Frame* frame,
93 /** \brief Handle a variable (DW_TAG_variable or other)
95 * \param info the resulting object fot the library/binary file (output)
96 * \param die the current DIE
97 * \param unit the DIE of the compile unit of the current DIE
98 * \param frame containing frame if any
100 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
101 Dwarf_Die * unit, simgrid::mc::Frame* frame,
104 /** \brief Get the DW_TAG_type of the DIE
107 * \return DW_TAG_type attribute as a new string (nullptr if none)
109 static std::uint64_t MC_dwarf_at_type(Dwarf_Die * die);
114 enum class TagClass {
123 /*** Class of forms defined in the DWARF standard */
124 enum class FormClass {
126 Address, // Location in the program's address space
127 Block, // Arbitrary block of bytes
130 Flag, // Boolean value
131 Reference, // Reference to another DIE
132 ExprLoc, // DWARF expression/location description
140 TagClass classify_tag(int tag)
144 case DW_TAG_array_type:
145 case DW_TAG_class_type:
146 case DW_TAG_enumeration_type:
148 case DW_TAG_pointer_type:
149 case DW_TAG_reference_type:
150 case DW_TAG_rvalue_reference_type:
151 case DW_TAG_string_type:
152 case DW_TAG_structure_type:
153 case DW_TAG_subroutine_type:
154 case DW_TAG_union_type:
155 case DW_TAG_ptr_to_member_type:
156 case DW_TAG_set_type:
157 case DW_TAG_subrange_type:
158 case DW_TAG_base_type:
159 case DW_TAG_const_type:
160 case DW_TAG_file_type:
161 case DW_TAG_packed_type:
162 case DW_TAG_volatile_type:
163 case DW_TAG_restrict_type:
164 case DW_TAG_interface_type:
165 case DW_TAG_unspecified_type:
166 case DW_TAG_shared_type:
167 return TagClass::Type;
169 case DW_TAG_subprogram:
170 return TagClass::Subprogram;
172 case DW_TAG_variable:
173 case DW_TAG_formal_parameter:
174 return TagClass::Variable;
176 case DW_TAG_lexical_block:
177 case DW_TAG_try_block:
178 case DW_TAG_catch_block:
179 case DW_TAG_inlined_subroutine:
180 case DW_TAG_with_stmt:
181 return TagClass::Scope;
183 case DW_TAG_namespace:
184 return TagClass::Namespace;
187 return TagClass::Unknown;
191 /** \brief Find the DWARF data class for a given DWARF data form
193 * This mapping is defined in the DWARF spec.
195 * \param form The form (values taken from the DWARF spec)
196 * \return An internal representation for the corresponding class
199 FormClass classify_form(int form)
203 return FormClass::Address;
208 return FormClass::Block;
215 return FormClass::Constant;
218 return FormClass::String;
219 case DW_FORM_ref_addr:
224 case DW_FORM_ref_udata:
225 return FormClass::Reference;
227 case DW_FORM_flag_present:
228 return FormClass::Flag;
229 case DW_FORM_exprloc:
230 return FormClass::ExprLoc;
234 return FormClass::Unknown;
238 /** \brief Get the name of the tag of a given DIE
241 * \return name of the tag of this DIE
244 const char *tagname(Dwarf_Die * die)
246 return simgrid::dwarf::tagname(dwarf_tag(die));
254 /** \brief Get an attribute of a given DIE as a string
257 * \param attribute attribute
258 * \return value of the given attribute of the given DIE
260 static const char *MC_dwarf_attr_integrate_string(Dwarf_Die * die,
263 Dwarf_Attribute attr;
264 if (not dwarf_attr_integrate(die, attribute, &attr))
267 return dwarf_formstring(&attr);
270 /** \brief Get the linkage name of a DIE.
272 * Use either DW_AT_linkage_name or DW_AT_MIPS_linkage_name.
273 * DW_AT_linkage_name is standardized since DWARF 4.
274 * Before this version of DWARF, the MIPS extensions
275 * DW_AT_MIPS_linkage_name is used (at least by GCC).
278 * \return linkage name of the given DIE (or nullptr)
280 static const char *MC_dwarf_at_linkage_name(Dwarf_Die * die)
282 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_linkage_name);
284 name = MC_dwarf_attr_integrate_string(die, DW_AT_MIPS_linkage_name);
288 static Dwarf_Off MC_dwarf_attr_dieoffset(Dwarf_Die * die, int attribute)
290 Dwarf_Attribute attr;
291 if (dwarf_hasattr_integrate(die, attribute) == 0)
293 dwarf_attr_integrate(die, attribute, &attr);
294 Dwarf_Die subtype_die;
295 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
296 xbt_die("Could not find DIE");
297 return dwarf_dieoffset(&subtype_die);
300 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die * die,
303 Dwarf_Attribute attr;
304 if (dwarf_hasattr_integrate(die, attribute) == 0)
306 dwarf_attr_integrate(die, DW_AT_type, &attr);
307 Dwarf_Die subtype_die;
308 if (dwarf_formref_die(&attr, &subtype_die) == nullptr)
309 xbt_die("Could not find DIE");
310 return dwarf_dieoffset(&subtype_die);
313 /** \brief Find the type/subtype (DW_AT_type) for a DIE
316 * \return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
319 std::uint64_t MC_dwarf_at_type(Dwarf_Die * die)
321 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
324 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die * die, int attribute)
326 Dwarf_Attribute attr;
327 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
330 if (dwarf_formaddr(&attr, &value) == 0)
331 return (uint64_t) value;
336 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die * die, int attribute,
337 uint64_t default_value)
339 Dwarf_Attribute attr;
340 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
341 return default_value;
343 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr),
344 &value) == 0 ? (uint64_t) value : default_value;
347 static bool MC_dwarf_attr_flag(Dwarf_Die * die, int attribute, bool integrate)
349 Dwarf_Attribute attr;
350 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr)
351 : dwarf_attr(die, attribute, &attr)) == 0)
355 if (dwarf_formflag(&attr, &result))
356 xbt_die("Unexpected form for attribute %s",
357 simgrid::dwarf::attrname(attribute));
361 /** @brief Find the default lower bound for a given language
363 * The default lower bound of an array (when DW_TAG_lower_bound
364 * is missing) depends on the language of the compilation unit.
366 * @param lang Language of the compilation unit (values defined in the DWARF spec)
367 * @return Default lower bound of an array in this compilation unit
369 static uint64_t MC_dwarf_default_lower_bound(int lang)
375 case DW_LANG_C_plus_plus:
379 case DW_LANG_ObjC_plus_plus:
385 case DW_LANG_Fortran77:
386 case DW_LANG_Fortran90:
387 case DW_LANG_Fortran95:
388 case DW_LANG_Modula2:
389 case DW_LANG_Pascal83:
391 case DW_LANG_Cobol74:
392 case DW_LANG_Cobol85:
395 xbt_die("No default DW_TAG_lower_bound for language %i and none given",
401 /** \brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
404 * \param unit DIE of the compilation unit
405 * \return number of elements in the range
407 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die * die,
410 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type
411 || dwarf_tag(die) == DW_TAG_subrange_type,
412 "MC_dwarf_subrange_element_count called with DIE of type %s",
413 simgrid::dwarf::tagname(die));
415 // Use DW_TAG_count if present:
416 if (dwarf_hasattr_integrate(die, DW_AT_count))
417 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
418 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
420 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
421 // This is not really 0, but the code expects this (we do not know):
424 uint64_t upper_bound =
425 MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, -1);
427 uint64_t lower_bound = 0;
428 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
429 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, -1);
431 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
432 return upper_bound - lower_bound + 1;
435 /** \brief Finds the number of elements in a array type (DW_TAG_array_type)
437 * The compilation unit might be needed because the default lower
438 * bound depends on the language of the compilation unit.
440 * \param die the DIE of the DW_TAG_array_type
441 * \param unit the DIE of the compilation unit
442 * \return number of elements in this array type
444 static uint64_t MC_dwarf_array_element_count(Dwarf_Die * die, Dwarf_Die * unit)
446 xbt_assert(dwarf_tag(die) == DW_TAG_array_type,
447 "MC_dwarf_array_element_count called with DIE of type %s",
448 simgrid::dwarf::tagname(die));
453 for (res = dwarf_child(die, &child); res == 0;
454 res = dwarf_siblingof(&child, &child)) {
455 int child_tag = dwarf_tag(&child);
456 if (child_tag == DW_TAG_subrange_type
457 || child_tag == DW_TAG_enumeration_type)
458 result *= MC_dwarf_subrange_element_count(&child, unit);
465 /** Sort the variable by name and address.
467 * We could use boost::container::flat_set instead.
469 static bool MC_compare_variable(
470 simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
472 int cmp = strcmp(a.name.c_str(), b.name.c_str());
478 return a.address < b.address;
481 // ***** simgrid::mc::Type*
483 /** \brief Initialize the location of a member of a type
484 * (DW_AT_data_member_location of a DW_TAG_member).
486 * \param type a type (struct, class)
487 * \param member the member of the type
488 * \param child DIE of the member (DW_TAG_member)
490 static void MC_dwarf_fill_member_location(
491 simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die * child)
493 if (dwarf_hasattr(child, DW_AT_data_bit_offset))
494 xbt_die("Can't groke DW_AT_data_bit_offset.");
496 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
497 if (type->type == DW_TAG_union_type)
500 ("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%"
501 PRIx64 ">%s", member->name.c_str(),
502 (uint64_t) type->id, type->name.c_str());
505 Dwarf_Attribute attr;
506 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
507 int form = dwarf_whatform(&attr);
508 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
509 switch (form_class) {
510 case simgrid::dwarf::FormClass::ExprLoc:
511 case simgrid::dwarf::FormClass::Block:
512 // Location expression:
516 if (dwarf_getlocation(&attr, &expr, &len))
518 ("Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%"
519 PRIx64 ">%s", MC_dwarf_attr_integrate_string(child, DW_AT_name),
520 (uint64_t) type->id, type->name.c_str());
521 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr+len);
524 case simgrid::dwarf::FormClass::Constant:
525 // Offset from the base address of the object:
528 if (not dwarf_formudata(&attr, &offset))
529 member->offset(offset);
531 xbt_die("Cannot get %s location <%" PRIx64 ">%s",
532 MC_dwarf_attr_integrate_string(child, DW_AT_name),
533 (uint64_t) type->id, type->name.c_str());
538 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to be
539 // possible in DWARF2 but I couldn't find its semantic in the spec)
540 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
545 /** \brief Populate the list of members of a type
547 * \param info ELF object containing the type DIE
548 * \param die DIE of the type
549 * \param unit DIE of the compilation unit containing the type DIE
550 * \param type the type
552 static void MC_dwarf_add_members(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
553 Dwarf_Die * unit, simgrid::mc::Type* type)
557 xbt_assert(type->members.empty());
558 for (res = dwarf_child(die, &child); res == 0;
559 res = dwarf_siblingof(&child, &child)) {
560 int tag = dwarf_tag(&child);
561 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
563 // Skip declarations:
564 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
567 // Skip compile time constants:
568 if (dwarf_hasattr(&child, DW_AT_const_value))
571 // TODO, we should use another type (because is is not a type but a member)
572 simgrid::mc::Member member;
573 if (tag == DW_TAG_inheritance)
574 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
576 const char *name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
579 // Those base names are used by GCC and clang for virtual table pointers
580 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
581 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
582 boost::algorithm::starts_with(member.name, "__vptr."))
583 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
584 // A cleaner solution would be to check against the type:
586 // tag: DW_TAG_member
589 // # Type for a pointer to a vtable
590 // tag: DW_TAG_pointer_type
592 // # Type for a vtable:
593 // tag: DW_TAG_pointer_type
594 // name: "__vtbl_ptr_type"
596 // tag: DW_TAG_subroutine_type
598 // tag: DW_TAG_base_type
603 MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
604 member.type_id = MC_dwarf_at_type(&child);
606 if (dwarf_hasattr(&child, DW_AT_data_bit_offset))
607 xbt_die("Can't groke DW_AT_data_bit_offset.");
609 MC_dwarf_fill_member_location(type, &member, &child);
611 if (not member.type_id)
612 xbt_die("Missing type for member %s of <%" PRIx64 ">%s",
614 (uint64_t) type->id, type->name.c_str());
616 type->members.push_back(std::move(member));
621 /** \brief Create a MC type object from a DIE
623 * \param info current object info object
624 * \param DIE (for a given type)
625 * \param unit compilation unit of the current DIE
626 * \return MC representation of the type
628 static simgrid::mc::Type MC_dwarf_die_to_type(
629 simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
630 Dwarf_Die * unit, simgrid::mc::Frame* frame,
633 simgrid::mc::Type type;
634 type.type = dwarf_tag(die);
635 type.name = std::string();
636 type.element_count = -1;
639 type.id = dwarf_dieoffset(die);
641 const char *prefix = "";
643 case DW_TAG_structure_type:
646 case DW_TAG_union_type:
649 case DW_TAG_class_type:
656 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
657 if (name != nullptr) {
659 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
661 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
664 type.type_id = MC_dwarf_at_type(die);
666 // Some compilers do not emit DW_AT_byte_size for pointer_type,
667 // so we fill this. We currently assume that the model-checked process is in
668 // the same architecture..
669 if (type.type == DW_TAG_pointer_type)
670 type.byte_size = sizeof(void*);
672 // Computation of the byte_size
673 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
674 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
675 else if (type.type == DW_TAG_array_type
676 || type.type == DW_TAG_structure_type
677 || type.type == DW_TAG_class_type) {
679 if (dwarf_aggregate_size(die, &size) == 0)
680 type.byte_size = size;
685 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
688 case DW_TAG_array_type:
689 type.element_count = MC_dwarf_array_element_count(die, unit);
690 // TODO, handle DW_byte_stride and (not) DW_bit_stride
693 case DW_TAG_pointer_type:
694 case DW_TAG_reference_type:
695 case DW_TAG_rvalue_reference_type:
698 case DW_TAG_structure_type:
699 case DW_TAG_union_type:
700 case DW_TAG_class_type:
701 MC_dwarf_add_members(info, die, unit, &type);
702 std::string new_ns = ns ? simgrid::xbt::string_printf("%s::%s", ns, name) : type.name;
703 MC_dwarf_handle_children(info, die, unit, frame, new_ns.c_str());
710 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
711 Dwarf_Die * unit, simgrid::mc::Frame* frame,
714 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
715 auto& t = (info->types[type.id] = std::move(type));
716 if (not t.name.empty() && type.byte_size != 0)
717 info->full_types_by_name[t.name] = &t;
720 static int mc_anonymous_variable_index = 0;
722 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(
723 simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
724 Dwarf_Die * unit, simgrid::mc::Frame* frame,
727 // Skip declarations:
728 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
731 // Skip compile time constants:
732 if (dwarf_hasattr(die, DW_AT_const_value))
735 Dwarf_Attribute attr_location;
736 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
737 // No location: do not add it ?
740 std::unique_ptr<simgrid::mc::Variable> variable =
741 std::unique_ptr<simgrid::mc::Variable>(new simgrid::mc::Variable());
742 variable->id = dwarf_dieoffset(die);
743 variable->global = frame == nullptr; // Can be override base on DW_AT_location
744 variable->object_info = info;
746 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
748 variable->name = name;
749 variable->type_id = MC_dwarf_at_type(die);
751 int form = dwarf_whatform(&attr_location);
752 simgrid::dwarf::FormClass form_class;
753 if (form == DW_FORM_sec_offset)
754 form_class = simgrid::dwarf::FormClass::Constant;
756 form_class = simgrid::dwarf::classify_form(form);
757 switch (form_class) {
758 case simgrid::dwarf::FormClass::ExprLoc:
759 case simgrid::dwarf::FormClass::Block:
760 // Location expression:
764 if (dwarf_getlocation(&attr_location, &expr, &len)) {
766 "Could not read location expression in DW_AT_location "
767 "of variable <%" PRIx64 ">%s",
768 (uint64_t) variable->id,
769 variable->name.c_str());
772 if (len == 1 && expr[0].atom == DW_OP_addr) {
773 variable->global = true;
774 uintptr_t offset = (uintptr_t) expr[0].number;
775 uintptr_t base = (uintptr_t) info->base_address();
776 variable->address = (void *) (base + offset);
778 variable->location_list = {
779 simgrid::dwarf::DwarfExpression(expr, expr + len) };
784 case simgrid::dwarf::FormClass::LocListPtr:
785 case simgrid::dwarf::FormClass::Constant:
786 // Reference to location list:
787 variable->location_list = simgrid::dwarf::location_list(
788 *info, attr_location);
792 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
793 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
796 // Handle start_scope:
797 if (dwarf_hasattr(die, DW_AT_start_scope)) {
798 Dwarf_Attribute attr;
799 dwarf_attr(die, DW_AT_start_scope, &attr);
800 int form = dwarf_whatform(&attr);
801 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
802 switch (form_class) {
803 case simgrid::dwarf::FormClass::Constant: {
805 variable->start_scope =
806 dwarf_formudata(&attr, &value) == 0 ? (size_t) value : 0;
810 default: // includes FormClass::RangeListPtr (TODO)
811 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
812 (unsigned)form_class, name == nullptr ? "?" : name);
816 if (ns && variable->global)
818 std::string(ns) + "::" + variable->name;
820 // The current code needs a variable name,
821 // generate a fake one:
822 if (variable->name.empty())
824 "@anonymous#" + std::to_string(mc_anonymous_variable_index++);
829 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
830 Dwarf_Die * unit, simgrid::mc::Frame* frame,
833 std::unique_ptr<simgrid::mc::Variable> variable =
834 MC_die_to_variable(info, die, unit, frame, ns);
837 // Those arrays are sorted later:
838 else if (variable->global)
839 info->global_variables.push_back(std::move(*variable));
840 else if (frame != nullptr)
841 frame->variables.push_back(std::move(*variable));
843 xbt_die("No frame for this local variable");
846 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
847 Dwarf_Die * unit, simgrid::mc::Frame* parent_frame,
850 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
851 int tag = dwarf_tag(die);
852 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
854 // (Template) Subprogram declaration:
855 if (klass == simgrid::dwarf::TagClass::Subprogram
856 && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
859 if (klass == simgrid::dwarf::TagClass::Scope)
860 xbt_assert(parent_frame, "No parent scope for this scope");
862 simgrid::mc::Frame frame;
864 frame.id = dwarf_dieoffset(die);
865 frame.object_info = info;
867 if (klass == simgrid::dwarf::TagClass::Subprogram) {
868 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
870 frame.name = std::string(ns) + "::" + name;
875 frame.abstract_origin_id =
876 MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
878 // This is the base address for DWARF addresses.
879 // Relocated addresses are offset from this base address.
880 // See DWARF4 spec 7.5
881 std::uint64_t base = (std::uint64_t) info->base_address();
883 // TODO, support DW_AT_ranges
884 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
885 frame.range.begin() = low_pc ? (std::uint64_t) base + low_pc : 0;
888 Dwarf_Attribute attr;
889 if (not dwarf_attr_integrate(die, DW_AT_high_pc, &attr))
890 xbt_die("Missing DW_AT_high_pc matching with DW_AT_low_pc");
895 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
897 // DW_AT_high_pc if an offset from the low_pc:
898 case simgrid::dwarf::FormClass::Constant:
900 if (dwarf_formsdata(&attr, &offset) != 0)
901 xbt_die("Could not read constant");
902 frame.range.end() = frame.range.begin() + offset;
905 // DW_AT_high_pc is a relocatable address:
906 case simgrid::dwarf::FormClass::Address:
907 if (dwarf_formaddr(&attr, &high_pc) != 0)
908 xbt_die("Could not read address");
909 frame.range.end() = base + high_pc;
913 xbt_die("Unexpected class for DW_AT_high_pc");
918 if (klass == simgrid::dwarf::TagClass::Subprogram) {
919 Dwarf_Attribute attr_frame_base;
920 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
921 frame.frame_base_location = simgrid::dwarf::location_list(*info,
926 MC_dwarf_handle_children(info, die, unit, &frame, ns);
928 // We sort them in order to have an (somewhat) efficient by name
930 boost::range::sort(frame.variables, MC_compare_variable);
933 if (klass == simgrid::dwarf::TagClass::Subprogram)
934 info->subprograms[frame.id] = std::move(frame);
935 else if (klass == simgrid::dwarf::TagClass::Scope)
936 parent_frame->scopes.push_back(std::move(frame));
939 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info,
940 Dwarf_Die * die, Dwarf_Die * unit,
941 simgrid::mc::Frame* frame,
944 const char *name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
946 xbt_die("Unexpected namespace in a subprogram");
947 char *new_ns = ns == nullptr ? xbt_strdup(name)
948 : bprintf("%s::%s", ns, name);
949 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
953 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
954 Dwarf_Die * unit, simgrid::mc::Frame* frame,
957 // For each child DIE:
960 for (res = dwarf_child(die, &child); res == 0;
961 res = dwarf_siblingof(&child, &child))
962 MC_dwarf_handle_die(info, &child, unit, frame, ns);
965 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
966 Dwarf_Die * unit, simgrid::mc::Frame* frame,
969 int tag = dwarf_tag(die);
970 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
974 case simgrid::dwarf::TagClass::Type:
975 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
978 // Subprogram or scope:
979 case simgrid::dwarf::TagClass::Subprogram:
980 case simgrid::dwarf::TagClass::Scope:
981 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
985 case simgrid::dwarf::TagClass::Variable:
986 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
989 case simgrid::dwarf::TagClass::Namespace:
990 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
1000 Elf64_Half get_type(Elf* elf)
1002 Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
1004 return ehdr64->e_type;
1005 Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
1007 return ehdr32->e_type;
1008 xbt_die("Could not get ELF heeader");
1012 void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
1014 // For each compilation unit:
1015 Dwarf_Off offset = 0;
1016 Dwarf_Off next_offset = 0;
1019 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) ==
1022 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
1023 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
1024 offset = next_offset;
1028 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
1030 * This build-id may is used to locate an external debug (DWARF) file
1031 * for this ELF file.
1033 * @param elf libelf handle for an ELF file
1034 * @return build-id for this ELF file (or an empty vector if none is found)
1037 std::vector<char> get_build_id(Elf* elf)
1040 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
1041 // found in a PT_NOTE entry in the program header table.
1044 if (elf_getphdrnum (elf, &phnum) != 0)
1045 xbt_die("Could not read program headers");
1047 // Iterate over the program headers and find the PT_NOTE ones:
1048 for (size_t i = 0; i < phnum; ++i) {
1049 GElf_Phdr phdr_temp;
1050 GElf_Phdr *phdr = gelf_getphdr(elf, i, &phdr_temp);
1051 if (phdr->p_type != PT_NOTE)
1054 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
1056 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
1058 while (pos < data->d_size) {
1060 // Location of the name within Elf_Data:
1063 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
1064 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
1065 // (a namespace and a type within this namespace):
1066 if (nhdr.n_type == NT_GNU_BUILD_ID
1067 && nhdr.n_namesz == sizeof("GNU")
1068 && memcmp((char*) data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
1069 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
1070 char* start = (char*) data->d_buf + desc_pos;
1071 char* end = (char*) start + nhdr.n_descsz;
1072 return std::vector<char>(start, end);
1078 return std::vector<char>();
1081 static char hexdigits[16] = {
1082 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
1083 'a', 'b', 'c', 'd', 'e', 'f'
1086 /** Binary data to hexadecimal */
1088 std::array<char, 2> to_hex(std::uint8_t byte)
1090 // Horrid double braces!
1091 // Apparently, this is needed in C++11 (not in C++14).
1092 return { { hexdigits[byte >> 4], hexdigits[byte & 0xF] } };
1095 /** Binary data to hexadecimal */
1097 std::string to_hex(const char* data, std::size_t count)
1100 res.resize(2*count);
1101 for (std::size_t i = 0; i < count; i++) {
1102 std::array<char, 2> hex_byte = to_hex(data[i]);
1103 for (int j = 0; j < 2; ++j)
1104 res[2 * i + j] = hex_byte[j];
1109 /** Binary data to hexadecimal */
1111 std::string to_hex(std::vector<char> const& data)
1113 return to_hex(data.data(), data.size());
1116 /** Base directories for external debug files */
1118 const char* debug_paths[] = {
1120 "/usr/local/lib/debug/",
1123 /** Locate an external debug file from the NT_GNU_BUILD_ID
1125 * This is one of the mechanisms used for
1126 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
1129 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
1131 std::string find_by_build_id(std::vector<char> id)
1133 std::string filename;
1134 std::string hex = to_hex(id);
1135 for (const char* const& debug_path : debug_paths) {
1137 filename = std::string(debug_path) + ".build-id/"
1138 + to_hex(id.data(), 1) + '/'
1139 + to_hex(id.data() + 1, id.size() - 1) + ".debug";
1140 XBT_DEBUG("Checking debug file: %s", filename.c_str());
1141 if (access(filename.c_str(), F_OK) == 0) {
1142 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
1146 XBT_DEBUG("Not debuf info found for build ID %s\n", hex.data());
1147 return std::string();
1150 /** \brief Populate the debugging informations of the given ELF object
1152 * Read the DWARf information of the EFFL object and populate the
1153 * lists of types, variables, functions.
1156 void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
1158 if (elf_version(EV_CURRENT) == EV_NONE)
1159 xbt_die("libelf initialization error");
1161 // Open the ELF file:
1162 int fd = open(info->file_name.c_str(), O_RDONLY);
1164 xbt_die("Could not open file %s", info->file_name.c_str());
1165 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
1167 xbt_die("Not an ELF file");
1168 Elf_Kind kind = elf_kind(elf);
1169 if (kind != ELF_K_ELF)
1170 xbt_die("Not an ELF file");
1172 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
1173 Elf64_Half type = get_type(elf);
1174 if (type == ET_EXEC)
1175 info->flags |= simgrid::mc::ObjectInformation::Executable;
1177 // Read DWARF debug information in the file:
1178 Dwarf* dwarf = dwarf_begin_elf (elf, DWARF_C_READ, nullptr);
1179 if (dwarf != nullptr) {
1180 read_dwarf_info(info, dwarf);
1188 // If there was no DWARF in the file, try to find it in a separate file.
1189 // Different methods might be used to store the DWARF informations:
1190 // * GNU NT_GNU_BUILD_ID
1192 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1193 // for reference of what we are doing.
1195 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1196 // use this ID to find the file in some known locations in the filesystem.
1197 std::vector<char> build_id = get_build_id(elf);
1198 if (not build_id.empty()) {
1202 // Find the debug file using the build id:
1203 std::string debug_file = find_by_build_id(build_id);
1204 if (debug_file.empty()) {
1205 std::string hex = to_hex(build_id);
1206 xbt_die("Missing debug info for %s with build-id %s\n"
1207 "You might want to install the suitable debugging package.\n",
1208 info->file_name.c_str(), hex.c_str());
1211 // Load the DWARF info from this file:
1212 XBT_DEBUG("Load DWARF for %s from %s",
1213 info->file_name.c_str(), debug_file.c_str());
1214 fd = open(debug_file.c_str(), O_RDONLY);
1216 xbt_die("Could not open file %s", debug_file.c_str());
1217 Dwarf* dwarf = dwarf_begin(fd, DWARF_C_READ);
1218 if (dwarf == nullptr)
1219 xbt_die("No DWARF info in %s for %s",
1220 debug_file.c_str(), info->file_name.c_str());
1221 read_dwarf_info(info, dwarf);
1227 // TODO, try to find DWARF info using .gnu_debuglink.
1231 xbt_die("Debugging information not found for %s\n"
1232 "Try recompiling with -g\n",
1233 info->file_name.c_str());
1236 // ***** Functions index
1238 static int MC_compare_frame_index_items(simgrid::mc::FunctionIndexEntry* a,
1239 simgrid::mc::FunctionIndexEntry* b)
1241 if (a->low_pc < b->low_pc)
1243 else if (a->low_pc == b->low_pc)
1249 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1251 info->functions_index.clear();
1253 for (auto& e : info->subprograms) {
1254 if (e.second.range.begin() == 0)
1256 simgrid::mc::FunctionIndexEntry entry;
1257 entry.low_pc = (void*) e.second.range.begin();
1258 entry.function = &e.second;
1259 info->functions_index.push_back(entry);
1262 info->functions_index.shrink_to_fit();
1264 // Sort the array by low_pc:
1265 boost::range::sort(info->functions_index,
1266 [](simgrid::mc::FunctionIndexEntry const& a,
1267 simgrid::mc::FunctionIndexEntry const& b)
1269 return a.low_pc < b.low_pc;
1273 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1275 // Someone needs this to be sorted but who?
1276 boost::range::sort(info->global_variables, MC_compare_variable);
1278 for (simgrid::mc::Variable& variable : info->global_variables)
1279 if (variable.type_id)
1280 variable.type = simgrid::util::find_map_ptr(
1281 info->types, variable.type_id);
1284 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1287 if (scope->tag == DW_TAG_inlined_subroutine) {
1288 // Attach correct namespaced name in inlined subroutine:
1289 auto i = info->subprograms.find(scope->abstract_origin_id);
1290 xbt_assert(i != info->subprograms.end(),
1291 "Could not lookup abstract origin %" PRIx64,
1292 (std::uint64_t) scope->abstract_origin_id);
1293 scope->name = i->second.name;
1297 for (simgrid::mc::Variable& variable : scope->variables)
1298 if (variable.type_id)
1299 variable.type = simgrid::util::find_map_ptr(
1300 info->types, variable.type_id);
1302 // Recursive post-processing of nested-scopes:
1303 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1304 mc_post_process_scope(info, &nested_scope);
1308 simgrid::mc::Type* MC_resolve_type(
1309 simgrid::mc::ObjectInformation* info, unsigned type_id)
1313 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1314 if (type == nullptr)
1317 // We already have the information on the type:
1318 if (type->byte_size != 0)
1321 // Don't have a name, we can't find a more complete version:
1322 if (type->name.empty())
1325 // Try to find a more complete description of the type:
1326 // We need to fix in order to support C++.
1327 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(
1328 info->full_types_by_name, type->name);
1334 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1336 // Lookup "subtype" field:
1337 for (auto& i : info->types) {
1338 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1339 for (simgrid::mc::Member& member : i.second.members)
1340 member.type = MC_resolve_type(info, member.type_id);
1347 /** \brief Finds informations about a given shared object/executable */
1348 std::shared_ptr<simgrid::mc::ObjectInformation> createObjectInformation(
1349 std::vector<simgrid::xbt::VmMap> const& maps, const char *name)
1351 std::shared_ptr<simgrid::mc::ObjectInformation> result =
1352 std::make_shared<simgrid::mc::ObjectInformation>();
1353 result->file_name = name;
1354 simgrid::mc::find_object_address(maps, result.get());
1355 MC_load_dwarf(result.get());
1356 MC_post_process_variables(result.get());
1357 MC_post_process_types(result.get());
1358 for (auto& entry : result.get()->subprograms)
1359 mc_post_process_scope(result.get(), &entry.second);
1360 MC_make_functions_index(result.get());
1364 /*************************************************************************/
1366 void postProcessObjectInformation(simgrid::mc::RemoteClient* process, simgrid::mc::ObjectInformation* info)
1368 for (auto& i : info->types) {
1370 simgrid::mc::Type* type = &(i.second);
1371 simgrid::mc::Type* subtype = type;
1372 while (subtype->type == DW_TAG_typedef
1373 || subtype->type == DW_TAG_volatile_type
1374 || subtype->type == DW_TAG_const_type)
1375 if (subtype->subtype)
1376 subtype = subtype->subtype;
1380 // Resolve full_type:
1381 if (not subtype->name.empty() && subtype->byte_size == 0)
1382 for (auto const& object_info : process->object_infos) {
1383 auto i = object_info->full_types_by_name.find(subtype->name);
1384 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1385 type->full_type = i->second;
1389 else type->full_type = subtype;
1400 /** Convert a DWARF register into a libunwind register
1402 * DWARF and libunwind does not use the same convention for numbering the
1403 * registers on some architectures. The function makes the necessary
1406 int dwarf_register_to_libunwind(int dwarf_register)
1408 #if defined(__x86_64__)
1409 // It seems for this arch, DWARF and libunwind agree in the numbering:
1410 return dwarf_register;
1411 #elif defined(__i386__)
1412 // Couldn't find the authoritative source of information for this.
1413 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1414 switch (dwarf_register) {
1434 return UNW_X86_EFLAGS;
1464 xbt_die("Bad/unknown register number.");
1467 #error This architecture is not supported yet for DWARF expression evaluation.