1 /* Copyright (c) 2008-2022. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/simgrid/util.hpp"
8 #include "xbt/string.hpp"
9 #include "xbt/sysdep.h"
10 #include <simgrid/config.h>
12 #include "src/mc/inspect/ObjectInformation.hpp"
13 #include "src/mc/inspect/Variable.hpp"
14 #include "src/mc/inspect/mc_dwarf.hpp"
15 #include "src/mc/mc_private.hpp"
16 #include "src/mc/remote/RemoteProcess.hpp"
27 #include <unordered_map>
30 #include <boost/range/algorithm.hpp>
32 #include <elfutils/libdw.h>
33 #include <elfutils/version.h>
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 for 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, Dwarf_Die* unit,
72 simgrid::mc::Frame* frame, const char* ns);
74 /** @brief Process a type DIE
76 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
77 simgrid::mc::Frame* frame, const char* ns);
79 /** @brief Calls MC_dwarf_handle_die on all children of the given die
81 * @param info the resulting object for the library/binary file (output)
82 * @param die the current DIE
83 * @param unit the DIE of the compile unit of the current DIE
84 * @param frame containing frame if any
86 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
87 simgrid::mc::Frame* frame, const char* ns);
89 /** @brief Handle a variable (DW_TAG_variable or other)
91 * @param info the resulting object for the library/binary file (output)
92 * @param die the current DIE
93 * @param unit the DIE of the compile unit of the current DIE
94 * @param frame containing frame if any
96 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, const Dwarf_Die* unit,
97 simgrid::mc::Frame* frame, const char* ns);
99 /** @brief Get the DW_TAG_type of the DIE
102 * @return DW_TAG_type attribute as a new string (nullptr if none)
104 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die);
106 namespace simgrid::dwarf {
108 enum class TagClass { Unknown, Type, Subprogram, Variable, Scope, Namespace };
110 /*** Class of forms defined in the DWARF standard */
111 enum class FormClass {
113 Address, // Location in the program's address space
114 Block, // Arbitrary block of bytes
117 Flag, // Boolean value
118 Reference, // Reference to another DIE
119 ExprLoc, // DWARF expression/location description
126 static TagClass classify_tag(int tag)
128 static const std::unordered_map<int, TagClass> map = {
129 {DW_TAG_array_type, TagClass::Type}, {DW_TAG_class_type, TagClass::Type},
130 {DW_TAG_enumeration_type, TagClass::Type}, {DW_TAG_typedef, TagClass::Type},
131 {DW_TAG_pointer_type, TagClass::Type}, {DW_TAG_reference_type, TagClass::Type},
132 {DW_TAG_rvalue_reference_type, TagClass::Type}, {DW_TAG_string_type, TagClass::Type},
133 {DW_TAG_structure_type, TagClass::Type}, {DW_TAG_subroutine_type, TagClass::Type},
134 {DW_TAG_union_type, TagClass::Type}, {DW_TAG_ptr_to_member_type, TagClass::Type},
135 {DW_TAG_set_type, TagClass::Type}, {DW_TAG_subrange_type, TagClass::Type},
136 {DW_TAG_base_type, TagClass::Type}, {DW_TAG_const_type, TagClass::Type},
137 {DW_TAG_file_type, TagClass::Type}, {DW_TAG_packed_type, TagClass::Type},
138 {DW_TAG_volatile_type, TagClass::Type}, {DW_TAG_restrict_type, TagClass::Type},
139 {DW_TAG_interface_type, TagClass::Type}, {DW_TAG_unspecified_type, TagClass::Type},
140 {DW_TAG_shared_type, TagClass::Type},
142 {DW_TAG_subprogram, TagClass::Subprogram},
144 {DW_TAG_variable, TagClass::Variable}, {DW_TAG_formal_parameter, TagClass::Variable},
146 {DW_TAG_lexical_block, TagClass::Scope}, {DW_TAG_try_block, TagClass::Scope},
147 {DW_TAG_catch_block, TagClass::Scope}, {DW_TAG_inlined_subroutine, TagClass::Scope},
148 {DW_TAG_with_stmt, TagClass::Scope},
150 {DW_TAG_namespace, TagClass::Namespace}};
152 auto res = map.find(tag);
153 return res != map.end() ? res->second : TagClass::Unknown;
156 /** @brief Find the DWARF data class for a given DWARF data form
158 * This mapping is defined in the DWARF spec.
160 * @param form The form (values taken from the DWARF spec)
161 * @return An internal representation for the corresponding class
163 static FormClass classify_form(int form)
165 static const std::unordered_map<int, FormClass> map = {
166 {DW_FORM_addr, FormClass::Address},
168 {DW_FORM_block2, FormClass::Block}, {DW_FORM_block4, FormClass::Block},
169 {DW_FORM_block, FormClass::Block}, {DW_FORM_block1, FormClass::Block},
171 {DW_FORM_data1, FormClass::Constant}, {DW_FORM_data2, FormClass::Constant},
172 {DW_FORM_data4, FormClass::Constant}, {DW_FORM_data8, FormClass::Constant},
173 {DW_FORM_udata, FormClass::Constant}, {DW_FORM_sdata, FormClass::Constant},
174 #if _ELFUTILS_PREREQ(0, 171)
175 {DW_FORM_implicit_const, FormClass::Constant},
178 {DW_FORM_string, FormClass::String}, {DW_FORM_strp, FormClass::String},
180 {DW_FORM_ref_addr, FormClass::Reference}, {DW_FORM_ref1, FormClass::Reference},
181 {DW_FORM_ref2, FormClass::Reference}, {DW_FORM_ref4, FormClass::Reference},
182 {DW_FORM_ref8, FormClass::Reference}, {DW_FORM_ref_udata, FormClass::Reference},
184 {DW_FORM_flag, FormClass::Flag}, {DW_FORM_flag_present, FormClass::Flag},
186 {DW_FORM_exprloc, FormClass::ExprLoc}
192 auto res = map.find(form);
193 return res != map.end() ? res->second : FormClass::Unknown;
196 /** @brief Get the name of the tag of a given DIE
199 * @return name of the tag of this DIE
201 inline XBT_PRIVATE const char* tagname(Dwarf_Die* die)
203 return tagname(dwarf_tag(die));
206 } // namespace simgrid::dwarf
210 /** @brief Get an attribute of a given DIE as a string
213 * @param attribute attribute
214 * @return value of the given attribute of the given DIE
216 static const char* MC_dwarf_attr_integrate_string(Dwarf_Die* die, int attribute)
218 Dwarf_Attribute attr;
219 if (not dwarf_attr_integrate(die, attribute, &attr))
222 return dwarf_formstring(&attr);
225 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die* die, int attribute)
227 Dwarf_Attribute attr;
228 if (dwarf_hasattr_integrate(die, attribute) == 0)
230 dwarf_attr_integrate(die, attribute, &attr);
231 Dwarf_Die subtype_die;
232 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
233 return dwarf_dieoffset(&subtype_die);
236 /** @brief Find the type/subtype (DW_AT_type) for a DIE
239 * @return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
241 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die)
243 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
246 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die* die, int attribute)
248 Dwarf_Attribute attr;
249 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
252 if (dwarf_formaddr(&attr, &value) == 0)
253 return (uint64_t)value;
258 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die* die, int attribute, uint64_t default_value)
260 Dwarf_Attribute attr;
261 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
262 return default_value;
264 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t)value : default_value;
267 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, bool integrate)
269 Dwarf_Attribute attr;
270 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr) : dwarf_attr(die, attribute, &attr)) == nullptr)
274 xbt_assert(not dwarf_formflag(&attr, &result), "Unexpected form for attribute %s",
275 simgrid::dwarf::attrname(attribute));
279 /** @brief Find the default lower bound for a given language
281 * The default lower bound of an array (when DW_TAG_lower_bound
282 * is missing) depends on the language of the compilation unit.
284 * @param lang Language of the compilation unit (values defined in the DWARF spec)
285 * @return Default lower bound of an array in this compilation unit
287 static uint64_t MC_dwarf_default_lower_bound(int lang)
289 const std::unordered_map<int, unsigned> map = {
290 {DW_LANG_C, 0}, {DW_LANG_C89, 0}, {DW_LANG_C99, 0}, {DW_LANG_C11, 0},
291 {DW_LANG_C_plus_plus, 0}, {DW_LANG_C_plus_plus_11, 0}, {DW_LANG_C_plus_plus_14, 0}, {DW_LANG_D, 0},
292 {DW_LANG_Java, 0}, {DW_LANG_ObjC, 0}, {DW_LANG_ObjC_plus_plus, 0}, {DW_LANG_Python, 0},
295 {DW_LANG_Ada83, 1}, {DW_LANG_Ada95, 1}, {DW_LANG_Fortran77, 1}, {DW_LANG_Fortran90, 1},
296 {DW_LANG_Fortran95, 1}, {DW_LANG_Fortran03, 1}, {DW_LANG_Fortran08, 1}, {DW_LANG_Modula2, 1},
297 {DW_LANG_Pascal83, 1}, {DW_LANG_PL1, 1}, {DW_LANG_Cobol74, 1}, {DW_LANG_Cobol85, 1}};
299 auto res = map.find(lang);
300 xbt_assert(res != map.end(), "No default DW_TAG_lower_bound for language %i and none given", lang);
304 /** @brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
307 * @param unit DIE of the compilation unit
308 * @return number of elements in the range
310 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit)
312 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type || dwarf_tag(die) == DW_TAG_subrange_type,
313 "MC_dwarf_subrange_element_count called with DIE of type %s", simgrid::dwarf::tagname(die));
315 // Use DW_TAG_count if present:
316 if (dwarf_hasattr_integrate(die, DW_AT_count))
317 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
318 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
320 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
321 // This is not really 0, but the code expects this (we do not know):
324 uint64_t upper_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, static_cast<uint64_t>(-1));
326 uint64_t lower_bound = 0;
327 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
328 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, static_cast<uint64_t>(-1));
330 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
331 return upper_bound - lower_bound + 1;
334 /** @brief Finds the number of elements in an array type (DW_TAG_array_type)
336 * The compilation unit might be needed because the default lower
337 * bound depends on the language of the compilation unit.
339 * @param die the DIE of the DW_TAG_array_type
340 * @param unit the DIE of the compilation unit
341 * @return number of elements in this array type
343 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit)
345 xbt_assert(dwarf_tag(die) == DW_TAG_array_type, "MC_dwarf_array_element_count called with DIE of type %s",
346 simgrid::dwarf::tagname(die));
350 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
351 int child_tag = dwarf_tag(&child);
352 if (child_tag == DW_TAG_subrange_type || child_tag == DW_TAG_enumeration_type)
353 result *= MC_dwarf_subrange_element_count(&child, unit);
360 /** Sort the variable by name and address.
362 * We could use boost::container::flat_set instead.
364 static bool MC_compare_variable(simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
366 int cmp = a.name.compare(b.name);
372 return a.address < b.address;
375 // ***** simgrid::mc::Type*
377 /** @brief Initialize the location of a member of a type
378 * (DW_AT_data_member_location of a DW_TAG_member).
380 * @param type a type (struct, class)
381 * @param member the member of the type
382 * @param child DIE of the member (DW_TAG_member)
384 static void MC_dwarf_fill_member_location(const simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die* child)
386 xbt_assert(not dwarf_hasattr(child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
388 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
389 xbt_assert(type->type == DW_TAG_union_type,
390 "Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%" PRIx64 ">%s",
391 member->name.c_str(), (uint64_t)type->id, type->name.c_str());
395 Dwarf_Attribute attr;
396 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
397 int form = dwarf_whatform(&attr);
398 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
399 switch (form_class) {
400 case simgrid::dwarf::FormClass::ExprLoc:
401 case simgrid::dwarf::FormClass::Block:
402 // Location expression:
406 xbt_assert(not dwarf_getlocation(&attr, &expr, &len),
407 "Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%" PRIx64
409 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
410 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr + len);
413 case simgrid::dwarf::FormClass::Constant:
414 // Offset from the base address of the object:
417 xbt_assert(not dwarf_formudata(&attr, &offset), "Cannot get %s location <%" PRIx64 ">%s",
418 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
419 member->offset(offset);
424 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to
425 // be possible in DWARF2 but I couldn't find its semantic in the spec)
426 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
430 /** @brief Populate the list of members of a type
432 * @param info ELF object containing the type DIE
433 * @param die DIE of the type
434 * @param unit DIE of the compilation unit containing the type DIE
435 * @param type the type
437 static void MC_dwarf_add_members(const simgrid::mc::ObjectInformation* /*info*/, Dwarf_Die* die,
438 const Dwarf_Die* /*unit*/, simgrid::mc::Type* type)
441 xbt_assert(type->members.empty());
442 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
443 int tag = dwarf_tag(&child);
444 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
445 // Skip declarations:
446 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
449 // Skip compile time constants:
450 if (dwarf_hasattr(&child, DW_AT_const_value))
453 // TODO, we should use another type (because is is not a type but a member)
454 simgrid::mc::Member member;
455 if (tag == DW_TAG_inheritance)
456 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
458 const char* name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
461 // Those base names are used by GCC and clang for virtual table pointers
462 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
463 if (member.name.rfind("__vptr$", 0) == 0 || member.name.rfind("__vptr.", 0) == 0)
464 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
465 // A cleaner solution would be to check against the type:
467 // tag: DW_TAG_member
470 // # Type for a pointer to a vtable
471 // tag: DW_TAG_pointer_type
473 // # Type for a vtable:
474 // tag: DW_TAG_pointer_type
475 // name: "__vtbl_ptr_type"
477 // tag: DW_TAG_subroutine_type
479 // tag: DW_TAG_base_type
483 member.byte_size = MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
484 member.type_id = MC_dwarf_at_type(&child);
486 if (dwarf_hasattr(&child, DW_AT_data_bit_offset)) {
487 XBT_WARN("Can't groke DW_AT_data_bit_offset for %s", name);
491 MC_dwarf_fill_member_location(type, &member, &child);
493 xbt_assert(member.type_id, "Missing type for member %s of <%" PRIx64 ">%s", member.name.c_str(),
494 (uint64_t)type->id, type->name.c_str());
496 type->members.push_back(std::move(member));
501 /** @brief Create a MC type object from a DIE
503 * @param info current object info object
504 * @param die DIE (for a given type)
505 * @param unit compilation unit of the current DIE
506 * @return MC representation of the type
508 static simgrid::mc::Type MC_dwarf_die_to_type(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
509 simgrid::mc::Frame* frame, const char* ns)
511 simgrid::mc::Type type;
512 type.type = dwarf_tag(die);
513 type.name = std::string();
514 type.element_count = -1;
517 type.id = dwarf_dieoffset(die);
521 case DW_TAG_structure_type:
524 case DW_TAG_union_type:
527 case DW_TAG_class_type:
534 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
535 if (name != nullptr) {
537 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
539 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
542 type.type_id = MC_dwarf_at_type(die);
544 // Some compilers do not emit DW_AT_byte_size for pointer_type,
545 // so we fill this. We currently assume that the model-checked process is in
546 // the same architecture..
547 if (type.type == DW_TAG_pointer_type)
548 type.byte_size = sizeof(void*);
550 // Computation of the byte_size
551 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
552 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
553 else if (type.type == DW_TAG_array_type || type.type == DW_TAG_structure_type || type.type == DW_TAG_class_type) {
555 if (dwarf_aggregate_size(die, &size) == 0)
556 type.byte_size = size;
560 case DW_TAG_array_type:
561 type.element_count = MC_dwarf_array_element_count(die, unit);
562 // TODO, handle DW_byte_stride and (not) DW_bit_stride
565 case DW_TAG_pointer_type:
566 case DW_TAG_reference_type:
567 case DW_TAG_rvalue_reference_type:
570 case DW_TAG_structure_type:
571 case DW_TAG_union_type:
572 case DW_TAG_class_type:
573 MC_dwarf_add_members(info, die, unit, &type);
574 MC_dwarf_handle_children(info, die, unit, frame,
575 ns ? simgrid::xbt::string_printf("%s::%s", ns, name).c_str() : type.name.c_str());
579 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
586 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
587 simgrid::mc::Frame* frame, const char* ns)
589 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
590 auto& t = (info->types[type.id] = std::move(type));
591 if (not t.name.empty() && type.byte_size != 0)
592 info->full_types_by_name[t.name] = &t;
595 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(simgrid::mc::ObjectInformation* info, Dwarf_Die* die,
596 const Dwarf_Die* /*unit*/,
597 const simgrid::mc::Frame* frame, const char* ns)
599 // Skip declarations:
600 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
603 // Skip compile time constants:
604 if (dwarf_hasattr(die, DW_AT_const_value))
607 Dwarf_Attribute attr_location;
608 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
609 // No location: do not add it ?
612 auto variable = std::make_unique<simgrid::mc::Variable>();
613 variable->id = dwarf_dieoffset(die);
614 variable->global = frame == nullptr; // Can be override base on DW_AT_location
615 variable->object_info = info;
617 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
619 variable->name = name;
620 variable->type_id = MC_dwarf_at_type(die);
622 int form = dwarf_whatform(&attr_location);
623 simgrid::dwarf::FormClass form_class;
624 if (form == DW_FORM_sec_offset)
625 form_class = simgrid::dwarf::FormClass::Constant;
627 form_class = simgrid::dwarf::classify_form(form);
628 switch (form_class) {
629 case simgrid::dwarf::FormClass::ExprLoc:
630 case simgrid::dwarf::FormClass::Block:
631 // Location expression:
635 xbt_assert(not dwarf_getlocation(&attr_location, &expr, &len),
636 "Could not read location expression in DW_AT_location "
637 "of variable <%" PRIx64 ">%s",
638 (uint64_t)variable->id, variable->name.c_str());
640 if (len == 1 && expr[0].atom == DW_OP_addr) {
641 variable->global = true;
642 auto offset = static_cast<uintptr_t>(expr[0].number);
643 auto base = reinterpret_cast<uintptr_t>(info->base_address());
644 variable->address = reinterpret_cast<void*>(base + offset);
646 variable->location_list = {
647 simgrid::dwarf::LocationListEntry(simgrid::dwarf::DwarfExpression(expr, expr + len))};
652 case simgrid::dwarf::FormClass::LocListPtr:
653 case simgrid::dwarf::FormClass::Constant:
654 // Reference to location list:
655 variable->location_list = simgrid::dwarf::location_list(*info, attr_location);
659 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
660 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
663 // Handle start_scope:
664 if (dwarf_hasattr(die, DW_AT_start_scope)) {
665 Dwarf_Attribute attr;
666 dwarf_attr(die, DW_AT_start_scope, &attr);
667 form = dwarf_whatform(&attr);
668 form_class = simgrid::dwarf::classify_form(form);
669 if (form_class == simgrid::dwarf::FormClass::Constant) {
671 variable->start_scope = dwarf_formudata(&attr, &value) == 0 ? (size_t)value : 0;
673 // TODO: FormClass::RangeListPtr
674 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
675 (unsigned)form_class, name == nullptr ? "?" : name);
679 if (ns && variable->global)
680 variable->name = std::string(ns) + "::" + variable->name;
682 // The current code needs a variable name,
683 // generate a fake one:
684 static int mc_anonymous_variable_index = 0;
685 if (variable->name.empty()) {
686 variable->name = "@anonymous#" + std::to_string(mc_anonymous_variable_index);
687 mc_anonymous_variable_index++;
692 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, const Dwarf_Die* unit,
693 simgrid::mc::Frame* frame, const char* ns)
695 std::unique_ptr<simgrid::mc::Variable> variable = MC_die_to_variable(info, die, unit, frame, ns);
698 // Those arrays are sorted later:
699 if (variable->global)
700 info->global_variables.push_back(std::move(*variable));
701 else if (frame != nullptr)
702 frame->variables.push_back(std::move(*variable));
704 xbt_die("No frame for this local variable");
707 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
708 simgrid::mc::Frame* parent_frame, const char* ns)
710 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
711 int tag = dwarf_tag(die);
712 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
714 // (Template) Subprogram declaration:
715 if (klass == simgrid::dwarf::TagClass::Subprogram && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
718 if (klass == simgrid::dwarf::TagClass::Scope)
719 xbt_assert(parent_frame, "No parent scope for this scope");
721 simgrid::mc::Frame frame;
723 frame.id = dwarf_dieoffset(die);
724 frame.object_info = info;
726 if (klass == simgrid::dwarf::TagClass::Subprogram) {
727 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
729 frame.name = std::string(ns) + "::" + name;
734 frame.abstract_origin_id = MC_dwarf_attr_integrate_dieoffset(die, DW_AT_abstract_origin);
736 // This is the base address for DWARF addresses.
737 // Relocated addresses are offset from this base address.
738 // See DWARF4 spec 7.5
739 auto base = reinterpret_cast<std::uint64_t>(info->base_address());
741 // TODO, support DW_AT_ranges
742 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
743 frame.range.begin() = low_pc ? base + low_pc : 0;
746 Dwarf_Attribute attr;
747 xbt_assert(dwarf_attr_integrate(die, DW_AT_high_pc, &attr), "Missing DW_AT_high_pc matching with DW_AT_low_pc");
752 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
753 // DW_AT_high_pc if an offset from the low_pc:
754 case simgrid::dwarf::FormClass::Constant:
756 xbt_assert(dwarf_formsdata(&attr, &offset) == 0, "Could not read constant");
757 frame.range.end() = frame.range.begin() + offset;
760 // DW_AT_high_pc is a relocatable address:
761 case simgrid::dwarf::FormClass::Address:
762 xbt_assert(dwarf_formaddr(&attr, &high_pc) == 0, "Could not read address");
763 frame.range.end() = base + high_pc;
767 xbt_die("Unexpected class for DW_AT_high_pc");
771 if (klass == simgrid::dwarf::TagClass::Subprogram) {
772 Dwarf_Attribute attr_frame_base;
773 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
774 frame.frame_base_location = simgrid::dwarf::location_list(*info, attr_frame_base);
778 MC_dwarf_handle_children(info, die, unit, &frame, ns);
780 // We sort them in order to have an (somewhat) efficient by name
782 boost::range::sort(frame.variables, MC_compare_variable);
785 if (klass == simgrid::dwarf::TagClass::Subprogram)
786 info->subprograms[frame.id] = std::move(frame);
787 else if (klass == simgrid::dwarf::TagClass::Scope)
788 parent_frame->scopes.push_back(std::move(frame));
791 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
792 simgrid::mc::Frame* frame, const char* ns)
794 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
795 xbt_assert(not frame, "Unexpected namespace in a subprogram");
796 char* new_ns = ns == nullptr ? xbt_strdup(name) : bprintf("%s::%s", ns, name);
797 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
801 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
802 simgrid::mc::Frame* frame, const char* ns)
804 // For each child DIE:
806 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child))
807 MC_dwarf_handle_die(info, &child, unit, frame, ns);
810 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
811 simgrid::mc::Frame* frame, const char* ns)
813 int tag = dwarf_tag(die);
814 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
817 case simgrid::dwarf::TagClass::Type:
818 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
821 // Subprogram or scope:
822 case simgrid::dwarf::TagClass::Subprogram:
823 case simgrid::dwarf::TagClass::Scope:
824 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
828 case simgrid::dwarf::TagClass::Variable:
829 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
832 case simgrid::dwarf::TagClass::Namespace:
833 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
841 static Elf64_Half get_type(Elf* elf)
843 if (const Elf64_Ehdr* ehdr64 = elf64_getehdr(elf))
844 return ehdr64->e_type;
845 if (const Elf32_Ehdr* ehdr32 = elf32_getehdr(elf))
846 return ehdr32->e_type;
847 xbt_die("Could not get ELF heeader");
850 static void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
852 // For each compilation unit:
853 Dwarf_Off offset = 0;
854 Dwarf_Off next_offset = 0;
857 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) == 0) {
858 if (Dwarf_Die unit_die; dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
859 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
860 offset = next_offset;
864 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
866 * This build-id may is used to locate an external debug (DWARF) file
869 * @param elf libelf handle for an ELF file
870 * @return build-id for this ELF file (or an empty vector if none is found)
872 static std::vector<char> get_build_id(Elf* elf)
875 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
876 // found in a PT_NOTE entry in the program header table.
879 xbt_assert(elf_getphdrnum(elf, &phnum) == 0, "Could not read program headers");
881 // Iterate over the program headers and find the PT_NOTE ones:
882 for (size_t i = 0; i < phnum; ++i) {
884 const GElf_Phdr* phdr = gelf_getphdr(elf, i, &phdr_temp);
885 if (phdr->p_type != PT_NOTE)
888 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
890 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
892 while (pos < data->d_size) {
894 // Location of the name within Elf_Data:
897 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
898 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
899 // (a namespace and a type within this namespace):
900 if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU") &&
901 memcmp((char*)data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
902 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
903 char* start = (char*)data->d_buf + desc_pos;
904 char* end = start + nhdr.n_descsz;
905 return std::vector<char>(start, end);
910 return std::vector<char>();
913 /** Binary data to hexadecimal */
914 static inline std::array<char, 2> to_hex(std::uint8_t byte)
916 constexpr std::array<char, 16> hexdigits{
917 {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}};
918 // Horrid double braces!
919 // Apparently, this is needed in C++11 (not in C++14).
920 return {{hexdigits[byte >> 4], hexdigits[byte & 0xF]}};
923 /** Binary data to hexadecimal */
924 static std::string to_hex(const char* data, std::size_t count)
927 res.resize(2 * count);
928 for (std::size_t i = 0; i < count; i++)
929 std::copy_n(cbegin(to_hex(data[i])), 2, &res[2 * i]);
933 /** Binary data to hexadecimal */
934 static std::string to_hex(std::vector<char> const& data)
936 return to_hex(data.data(), data.size());
939 /** Base directories for external debug files */
940 static constexpr auto debug_paths = {
942 "/usr/local/lib/debug/",
945 /** Locate an external debug file from the NT_GNU_BUILD_ID
947 * This is one of the mechanisms used for
948 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
951 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
952 static int find_by_build_id(std::vector<char> id)
954 std::string filename;
955 std::string hex = to_hex(id);
956 for (const char* const& debug_path : debug_paths) {
958 filename = std::string(debug_path) + ".build-id/" + to_hex(id.data(), 1) + '/' +
959 to_hex(id.data() + 1, id.size() - 1) + ".debug";
960 XBT_DEBUG("Checking debug file: %s", filename.c_str());
961 if (int fd = open(filename.c_str(), O_RDONLY); fd != -1) {
962 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
965 xbt_assert(errno != ENOENT, "Could not open file: %s", strerror(errno));
967 XBT_DEBUG("No debug info found for build ID %s\n", hex.data());
971 /** @brief Populate the debugging information of the given ELF object
973 * Read the DWARF information of the ELF object and populate the
974 * lists of types, variables, functions.
976 static void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
978 xbt_assert(elf_version(EV_CURRENT) != EV_NONE, "libelf initialization error");
980 // Open the ELF file:
981 int fd = open(info->file_name.c_str(), O_RDONLY);
982 xbt_assert(fd >= 0, "Could not open file %s", info->file_name.c_str());
983 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
984 xbt_assert(elf != nullptr && elf_kind(elf) == ELF_K_ELF, "%s is not an ELF file", info->file_name.c_str());
986 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
987 if (get_type(elf) == ET_EXEC)
988 info->flags |= simgrid::mc::ObjectInformation::Executable;
990 // Read DWARF debug information in the file:
991 if (Dwarf* dwarf = dwarf_begin_elf(elf, DWARF_C_READ, nullptr)) {
992 read_dwarf_info(info, dwarf);
999 // If there was no DWARF in the file, try to find it in a separate file.
1000 // Different methods might be used to store the DWARF information:
1001 // * GNU NT_GNU_BUILD_ID
1003 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1004 // for reference of what we are doing.
1006 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1007 // use this ID to find the file in some known locations in the filesystem.
1008 if (std::vector<char> build_id = get_build_id(elf); not build_id.empty()) {
1012 // Find the debug file using the build id:
1013 fd = find_by_build_id(build_id);
1014 xbt_assert(fd != -1,
1015 "Missing debug info for %s with build-id %s\n"
1016 "You might want to install the suitable debugging package.\n",
1017 info->file_name.c_str(), to_hex(build_id).c_str());
1019 // Load the DWARF info from this file:
1020 XBT_DEBUG("Load DWARF for %s", info->file_name.c_str());
1021 Dwarf* dwarf = dwarf_begin(fd, DWARF_C_READ);
1022 xbt_assert(dwarf != nullptr, "No DWARF info for %s", info->file_name.c_str());
1023 read_dwarf_info(info, dwarf);
1029 // TODO, try to find DWARF info using .gnu_debuglink.
1033 xbt_die("Debugging information not found for %s\n"
1034 "Try recompiling with -g\n",
1035 info->file_name.c_str());
1038 // ***** Functions index
1040 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1042 info->functions_index.clear();
1044 for (auto& [_, e] : info->subprograms) {
1045 if (e.range.begin() == 0)
1047 simgrid::mc::FunctionIndexEntry entry;
1048 entry.low_pc = (void*)e.range.begin();
1049 entry.function = &e;
1050 info->functions_index.push_back(entry);
1053 info->functions_index.shrink_to_fit();
1055 // Sort the array by low_pc:
1056 boost::range::sort(info->functions_index,
1057 [](simgrid::mc::FunctionIndexEntry const& a, simgrid::mc::FunctionIndexEntry const& b) {
1058 return a.low_pc < b.low_pc;
1062 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1064 // Someone needs this to be sorted but who?
1065 boost::range::sort(info->global_variables, MC_compare_variable);
1067 for (simgrid::mc::Variable& variable : info->global_variables)
1068 if (variable.type_id)
1069 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1072 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1074 if (scope->tag == DW_TAG_inlined_subroutine) {
1075 // Attach correct namespaced name in inlined subroutine:
1076 auto i = info->subprograms.find(scope->abstract_origin_id);
1077 xbt_assert(i != info->subprograms.end(), "Could not lookup abstract origin %" PRIx64,
1078 (std::uint64_t)scope->abstract_origin_id);
1079 scope->name = i->second.name;
1083 for (simgrid::mc::Variable& variable : scope->variables)
1084 if (variable.type_id)
1085 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1087 // Recursive post-processing of nested-scopes:
1088 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1089 mc_post_process_scope(info, &nested_scope);
1092 static simgrid::mc::Type* MC_resolve_type(simgrid::mc::ObjectInformation* info, unsigned type_id)
1096 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1097 if (type == nullptr)
1100 // We already have the information on the type:
1101 if (type->byte_size != 0)
1104 // Don't have a name, we can't find a more complete version:
1105 if (type->name.empty())
1108 // Try to find a more complete description of the type:
1109 // We need to fix in order to support C++.
1110 if (simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(info->full_types_by_name, type->name))
1115 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1117 // Lookup "subtype" field:
1118 for (auto& [_, i] : info->types) {
1119 i.subtype = MC_resolve_type(info, i.type_id);
1120 for (simgrid::mc::Member& member : i.members)
1121 member.type = MC_resolve_type(info, member.type_id);
1125 namespace simgrid::mc {
1127 void ObjectInformation::ensure_dwarf_loaded()
1131 dwarf_loaded = true;
1133 MC_load_dwarf(this);
1134 MC_post_process_variables(this);
1135 MC_post_process_types(this);
1136 for (auto& [_, entry] : this->subprograms)
1137 mc_post_process_scope(this, &entry);
1138 MC_make_functions_index(this);
1141 /** @brief Finds information about a given shared object/executable */
1142 std::shared_ptr<ObjectInformation> createObjectInformation(std::vector<xbt::VmMap> const& maps, const char* name)
1144 auto result = std::make_shared<ObjectInformation>();
1145 result->file_name = name;
1146 simgrid::mc::find_object_address(maps, result.get());
1150 /*************************************************************************/
1152 void postProcessObjectInformation(const RemoteProcess* process, ObjectInformation* info)
1154 for (auto& [_, t] : info->types) {
1156 Type* subtype = type;
1157 while (subtype->type == DW_TAG_typedef || subtype->type == DW_TAG_volatile_type ||
1158 subtype->type == DW_TAG_const_type)
1159 if (subtype->subtype)
1160 subtype = subtype->subtype;
1164 // Resolve full_type:
1165 if (not subtype->name.empty() && subtype->byte_size == 0)
1166 for (auto const& object_info : process->object_infos) {
1167 auto i = object_info->full_types_by_name.find(subtype->name);
1168 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1169 type->full_type = i->second;
1174 type->full_type = subtype;
1178 } // namespace simgrid::mc
1180 namespace simgrid::dwarf {
1182 /** Convert a DWARF register into a libunwind register
1184 * DWARF and libunwind does not use the same convention for numbering the
1185 * registers on some architectures. The function makes the necessary
1188 int dwarf_register_to_libunwind(int dwarf_register)
1190 #if defined(__x86_64__) || defined(__aarch64__)
1191 // It seems for this arch, DWARF and libunwind agree in the numbering:
1192 return dwarf_register;
1193 #elif defined(__i386__)
1194 // Couldn't find the authoritative source of information for this.
1195 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1196 constexpr std::array<int, 24> regs{
1197 {/* 0 */ UNW_X86_EAX, /* 1 */ UNW_X86_ECX, /* 2 */ UNW_X86_EDX, /* 3 */ UNW_X86_EBX,
1198 /* 4 */ UNW_X86_ESP, /* 5 */ UNW_X86_EBP, /* 6 */ UNW_X86_ESI, /* 7 */ UNW_X86_EDI,
1199 /* 8 */ UNW_X86_EIP, /* 9 */ UNW_X86_EFLAGS, /* 10 */ UNW_X86_CS, /* 11 */ UNW_X86_SS,
1200 /* 12 */ UNW_X86_DS, /* 13 */ UNW_X86_ES, /* 14 */ UNW_X86_FS, /* 15 */ UNW_X86_GS,
1201 /* 16 */ UNW_X86_ST0, /* 17 */ UNW_X86_ST1, /* 18 */ UNW_X86_ST2, /* 19 */ UNW_X86_ST3,
1202 /* 20 */ UNW_X86_ST4, /* 21 */ UNW_X86_ST5, /* 22 */ UNW_X86_ST6, /* 23 */ UNW_X86_ST7}};
1203 return regs.at(dwarf_register);
1205 #error This architecture is not supported yet for DWARF expression evaluation.
1209 } // namespace simgrid::dwarf