1 /* Copyright (c) 2008-2021. 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/RemoteSimulation.hpp"
25 #include <unordered_map>
28 #include <boost/range/algorithm.hpp>
30 #include <elfutils/libdw.h>
32 #include <boost/algorithm/string/predicate.hpp>
34 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dwarf, mc, "DWARF processing");
36 /** @brief The default DW_TAG_lower_bound for a given DW_AT_language.
38 * The default for a given language is defined in the DWARF spec.
40 * @param language constant as defined by the DWARf spec
42 static uint64_t MC_dwarf_default_lower_bound(int lang);
44 /** @brief Computes the the element_count of a DW_TAG_enumeration_type DIE
46 * This is the number of elements in a given array dimension.
48 * A reference of the compilation unit (DW_TAG_compile_unit) is
49 * needed because the default lower bound (when there is no DW_AT_lower_bound)
50 * depends of the language of the compilation unit (DW_AT_language).
52 * @param die DIE for the DW_TAG_enumeration_type or DW_TAG_subrange_type
53 * @param unit DIE of the DW_TAG_compile_unit
55 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit);
57 /** @brief Computes the number of elements of a given DW_TAG_array_type.
59 * @param die DIE for the DW_TAG_array_type
61 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit);
63 /** @brief Process a DIE
65 * @param info the resulting object for the library/binary file (output)
66 * @param die the current DIE
67 * @param unit the DIE of the compile unit of the current DIE
68 * @param frame containing frame if any
70 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
71 simgrid::mc::Frame* frame, const char* ns);
73 /** @brief Process a type DIE
75 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
76 simgrid::mc::Frame* frame, const char* ns);
78 /** @brief Calls MC_dwarf_handle_die on all children of the given die
80 * @param info the resulting object for the library/binary file (output)
81 * @param die the current DIE
82 * @param unit the DIE of the compile unit of the current DIE
83 * @param frame containing frame if any
85 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
86 simgrid::mc::Frame* frame, const char* ns);
88 /** @brief Handle a variable (DW_TAG_variable or other)
90 * @param info the resulting object for the library/binary file (output)
91 * @param die the current DIE
92 * @param unit the DIE of the compile unit of the current DIE
93 * @param frame containing frame if any
95 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, const Dwarf_Die* unit,
96 simgrid::mc::Frame* frame, const char* ns);
98 /** @brief Get the DW_TAG_type of the DIE
101 * @return DW_TAG_type attribute as a new string (nullptr if none)
103 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die);
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},
175 {DW_FORM_string, FormClass::String}, {DW_FORM_strp, FormClass::String},
177 {DW_FORM_ref_addr, FormClass::Reference}, {DW_FORM_ref1, FormClass::Reference},
178 {DW_FORM_ref2, FormClass::Reference}, {DW_FORM_ref4, FormClass::Reference},
179 {DW_FORM_ref8, FormClass::Reference}, {DW_FORM_ref_udata, FormClass::Reference},
181 {DW_FORM_flag, FormClass::Flag}, {DW_FORM_flag_present, FormClass::Flag},
183 {DW_FORM_exprloc, FormClass::ExprLoc}
189 auto res = map.find(form);
190 return res != map.end() ? res->second : FormClass::Unknown;
193 /** @brief Get the name of the tag of a given DIE
196 * @return name of the tag of this DIE
198 inline XBT_PRIVATE const char* tagname(Dwarf_Die* die)
200 return tagname(dwarf_tag(die));
204 } // namespace simgrid
208 /** @brief Get an attribute of a given DIE as a string
211 * @param attribute attribute
212 * @return value of the given attribute of the given DIE
214 static const char* MC_dwarf_attr_integrate_string(Dwarf_Die* die, int attribute)
216 Dwarf_Attribute attr;
217 if (not dwarf_attr_integrate(die, attribute, &attr))
220 return dwarf_formstring(&attr);
223 static Dwarf_Off MC_dwarf_attr_dieoffset(Dwarf_Die* die, int attribute)
225 Dwarf_Attribute attr;
226 if (dwarf_hasattr_integrate(die, attribute) == 0)
228 dwarf_attr_integrate(die, attribute, &attr);
229 Dwarf_Die subtype_die;
230 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
231 return dwarf_dieoffset(&subtype_die);
234 static Dwarf_Off MC_dwarf_attr_integrate_dieoffset(Dwarf_Die* die, int attribute)
236 Dwarf_Attribute attr;
237 if (dwarf_hasattr_integrate(die, attribute) == 0)
239 dwarf_attr_integrate(die, DW_AT_type, &attr);
240 Dwarf_Die subtype_die;
241 xbt_assert(dwarf_formref_die(&attr, &subtype_die) != nullptr, "Could not find DIE");
242 return dwarf_dieoffset(&subtype_die);
245 /** @brief Find the type/subtype (DW_AT_type) for a DIE
248 * @return DW_AT_type reference as a global offset in hexadecimal (or nullptr)
250 static std::uint64_t MC_dwarf_at_type(Dwarf_Die* die)
252 return MC_dwarf_attr_integrate_dieoffset(die, DW_AT_type);
255 static uint64_t MC_dwarf_attr_integrate_addr(Dwarf_Die* die, int attribute)
257 Dwarf_Attribute attr;
258 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
261 if (dwarf_formaddr(&attr, &value) == 0)
262 return (uint64_t)value;
267 static uint64_t MC_dwarf_attr_integrate_uint(Dwarf_Die* die, int attribute, uint64_t default_value)
269 Dwarf_Attribute attr;
270 if (dwarf_attr_integrate(die, attribute, &attr) == nullptr)
271 return default_value;
273 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t)value : default_value;
276 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, bool integrate)
278 Dwarf_Attribute attr;
279 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr) : dwarf_attr(die, attribute, &attr)) == nullptr)
283 xbt_assert(not dwarf_formflag(&attr, &result), "Unexpected form for attribute %s",
284 simgrid::dwarf::attrname(attribute));
288 /** @brief Find the default lower bound for a given language
290 * The default lower bound of an array (when DW_TAG_lower_bound
291 * is missing) depends on the language of the compilation unit.
293 * @param lang Language of the compilation unit (values defined in the DWARF spec)
294 * @return Default lower bound of an array in this compilation unit
296 static uint64_t MC_dwarf_default_lower_bound(int lang)
298 const std::unordered_map<int, unsigned> map = {
299 {DW_LANG_C, 0}, {DW_LANG_C89, 0}, {DW_LANG_C99, 0}, {DW_LANG_C_plus_plus, 0},
300 {DW_LANG_D, 0}, {DW_LANG_Java, 0}, {DW_LANG_ObjC, 0}, {DW_LANG_ObjC_plus_plus, 0},
301 {DW_LANG_Python, 0}, {DW_LANG_UPC, 0},
303 {DW_LANG_Ada83, 1}, {DW_LANG_Ada95, 1}, {DW_LANG_Fortran77, 1}, {DW_LANG_Fortran90, 1},
304 {DW_LANG_Fortran95, 1}, {DW_LANG_Modula2, 1}, {DW_LANG_Pascal83, 1}, {DW_LANG_PL1, 1},
305 {DW_LANG_Cobol74, 1}, {DW_LANG_Cobol85, 1}};
307 auto res = map.find(lang);
308 xbt_assert(res != map.end(), "No default DW_TAG_lower_bound for language %i and none given", lang);
312 /** @brief Finds the number of elements in a DW_TAG_subrange_type or DW_TAG_enumeration_type DIE
315 * @param unit DIE of the compilation unit
316 * @return number of elements in the range
318 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit)
320 xbt_assert(dwarf_tag(die) == DW_TAG_enumeration_type || dwarf_tag(die) == DW_TAG_subrange_type,
321 "MC_dwarf_subrange_element_count called with DIE of type %s", simgrid::dwarf::tagname(die));
323 // Use DW_TAG_count if present:
324 if (dwarf_hasattr_integrate(die, DW_AT_count))
325 return MC_dwarf_attr_integrate_uint(die, DW_AT_count, 0);
326 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound + 1:
328 if (not dwarf_hasattr_integrate(die, DW_AT_upper_bound))
329 // This is not really 0, but the code expects this (we do not know):
332 uint64_t upper_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_upper_bound, static_cast<uint64_t>(-1));
334 uint64_t lower_bound = 0;
335 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound))
336 lower_bound = MC_dwarf_attr_integrate_uint(die, DW_AT_lower_bound, static_cast<uint64_t>(-1));
338 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
339 return upper_bound - lower_bound + 1;
342 /** @brief Finds the number of elements in an array type (DW_TAG_array_type)
344 * The compilation unit might be needed because the default lower
345 * bound depends on the language of the compilation unit.
347 * @param die the DIE of the DW_TAG_array_type
348 * @param unit the DIE of the compilation unit
349 * @return number of elements in this array type
351 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit)
353 xbt_assert(dwarf_tag(die) == DW_TAG_array_type, "MC_dwarf_array_element_count called with DIE of type %s",
354 simgrid::dwarf::tagname(die));
358 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
359 int child_tag = dwarf_tag(&child);
360 if (child_tag == DW_TAG_subrange_type || child_tag == DW_TAG_enumeration_type)
361 result *= MC_dwarf_subrange_element_count(&child, unit);
368 /** Sort the variable by name and address.
370 * We could use boost::container::flat_set instead.
372 static bool MC_compare_variable(simgrid::mc::Variable const& a, simgrid::mc::Variable const& b)
374 int cmp = a.name.compare(b.name);
380 return a.address < b.address;
383 // ***** simgrid::mc::Type*
385 /** @brief Initialize the location of a member of a type
386 * (DW_AT_data_member_location of a DW_TAG_member).
388 * @param type a type (struct, class)
389 * @param member the member of the type
390 * @param child DIE of the member (DW_TAG_member)
392 static void MC_dwarf_fill_member_location(const simgrid::mc::Type* type, simgrid::mc::Member* member, Dwarf_Die* child)
394 xbt_assert(not dwarf_hasattr(child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
396 if (not dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
397 if (type->type == DW_TAG_union_type)
399 xbt_die("Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%" PRIx64 ">%s",
400 member->name.c_str(), (uint64_t)type->id, type->name.c_str());
403 Dwarf_Attribute attr;
404 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
405 int form = dwarf_whatform(&attr);
406 simgrid::dwarf::FormClass form_class = simgrid::dwarf::classify_form(form);
407 switch (form_class) {
408 case simgrid::dwarf::FormClass::ExprLoc:
409 case simgrid::dwarf::FormClass::Block:
410 // Location expression:
414 xbt_assert(not dwarf_getlocation(&attr, &expr, &len),
415 "Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%" PRIx64
417 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
418 member->location_expression = simgrid::dwarf::DwarfExpression(expr, expr + len);
421 case simgrid::dwarf::FormClass::Constant:
422 // Offset from the base address of the object:
425 xbt_assert(not dwarf_formudata(&attr, &offset), "Cannot get %s location <%" PRIx64 ">%s",
426 MC_dwarf_attr_integrate_string(child, DW_AT_name), (uint64_t)type->id, type->name.c_str());
427 member->offset(offset);
432 // includes FormClass::LocListPtr (reference to a location list: TODO) and FormClass::Reference (it's supposed to
433 // be possible in DWARF2 but I couldn't find its semantic in the spec)
434 xbt_die("Can't handle form class (%d) / form 0x%x as DW_AT_member_location", (int)form_class, (unsigned)form);
438 /** @brief Populate the list of members of a type
440 * @param info ELF object containing the type DIE
441 * @param die DIE of the type
442 * @param unit DIE of the compilation unit containing the type DIE
443 * @param type the type
445 static void MC_dwarf_add_members(const simgrid::mc::ObjectInformation* /*info*/, Dwarf_Die* die,
446 const Dwarf_Die* /*unit*/, simgrid::mc::Type* type)
449 xbt_assert(type->members.empty());
450 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child)) {
451 int tag = dwarf_tag(&child);
452 if (tag == DW_TAG_member || tag == DW_TAG_inheritance) {
453 // Skip declarations:
454 if (MC_dwarf_attr_flag(&child, DW_AT_declaration, false))
457 // Skip compile time constants:
458 if (dwarf_hasattr(&child, DW_AT_const_value))
461 // TODO, we should use another type (because is is not a type but a member)
462 simgrid::mc::Member member;
463 if (tag == DW_TAG_inheritance)
464 member.flags |= simgrid::mc::Member::INHERITANCE_FLAG;
466 const char* name = MC_dwarf_attr_integrate_string(&child, DW_AT_name);
469 // Those base names are used by GCC and clang for virtual table pointers
470 // respectively ("__vptr$ClassName", "__vptr.ClassName"):
471 if (boost::algorithm::starts_with(member.name, "__vptr$") ||
472 boost::algorithm::starts_with(member.name, "__vptr."))
473 member.flags |= simgrid::mc::Member::VIRTUAL_POINTER_FLAG;
474 // A cleaner solution would be to check against the type:
476 // tag: DW_TAG_member
479 // # Type for a pointer to a vtable
480 // tag: DW_TAG_pointer_type
482 // # Type for a vtable:
483 // tag: DW_TAG_pointer_type
484 // name: "__vtbl_ptr_type"
486 // tag: DW_TAG_subroutine_type
488 // tag: DW_TAG_base_type
492 member.byte_size = MC_dwarf_attr_integrate_uint(&child, DW_AT_byte_size, 0);
493 member.type_id = MC_dwarf_at_type(&child);
495 xbt_assert(not dwarf_hasattr(&child, DW_AT_data_bit_offset), "Can't groke DW_AT_data_bit_offset.");
497 MC_dwarf_fill_member_location(type, &member, &child);
499 xbt_assert(member.type_id, "Missing type for member %s of <%" PRIx64 ">%s", member.name.c_str(),
500 (uint64_t)type->id, type->name.c_str());
502 type->members.push_back(std::move(member));
507 /** @brief Create a MC type object from a DIE
509 * @param info current object info object
510 * @param die DIE (for a given type)
511 * @param unit compilation unit of the current DIE
512 * @return MC representation of the type
514 static simgrid::mc::Type MC_dwarf_die_to_type(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
515 simgrid::mc::Frame* frame, const char* ns)
517 simgrid::mc::Type type;
518 type.type = dwarf_tag(die);
519 type.name = std::string();
520 type.element_count = -1;
523 type.id = dwarf_dieoffset(die);
525 const char* prefix = "";
527 case DW_TAG_structure_type:
530 case DW_TAG_union_type:
533 case DW_TAG_class_type:
540 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
541 if (name != nullptr) {
543 type.name = simgrid::xbt::string_printf("%s%s::%s", prefix, ns, name);
545 type.name = simgrid::xbt::string_printf("%s%s", prefix, name);
548 type.type_id = MC_dwarf_at_type(die);
550 // Some compilers do not emit DW_AT_byte_size for pointer_type,
551 // so we fill this. We currently assume that the model-checked process is in
552 // the same architecture..
553 if (type.type == DW_TAG_pointer_type)
554 type.byte_size = sizeof(void*);
556 // Computation of the byte_size
557 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
558 type.byte_size = MC_dwarf_attr_integrate_uint(die, DW_AT_byte_size, 0);
559 else if (type.type == DW_TAG_array_type || type.type == DW_TAG_structure_type || type.type == DW_TAG_class_type) {
561 if (dwarf_aggregate_size(die, &size) == 0)
562 type.byte_size = size;
566 case DW_TAG_array_type:
567 type.element_count = MC_dwarf_array_element_count(die, unit);
568 // TODO, handle DW_byte_stride and (not) DW_bit_stride
571 case DW_TAG_pointer_type:
572 case DW_TAG_reference_type:
573 case DW_TAG_rvalue_reference_type:
576 case DW_TAG_structure_type:
577 case DW_TAG_union_type:
578 case DW_TAG_class_type:
579 MC_dwarf_add_members(info, die, unit, &type);
580 MC_dwarf_handle_children(info, die, unit, frame,
581 ns ? simgrid::xbt::string_printf("%s::%s", ns, name).c_str() : type.name.c_str());
585 XBT_DEBUG("Unhandled type: %d (%s)", type.type, simgrid::dwarf::tagname(type.type));
592 static void MC_dwarf_handle_type_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
593 simgrid::mc::Frame* frame, const char* ns)
595 simgrid::mc::Type type = MC_dwarf_die_to_type(info, die, unit, frame, ns);
596 auto& t = (info->types[type.id] = std::move(type));
597 if (not t.name.empty() && type.byte_size != 0)
598 info->full_types_by_name[t.name] = &t;
601 static int mc_anonymous_variable_index = 0;
603 static std::unique_ptr<simgrid::mc::Variable> MC_die_to_variable(simgrid::mc::ObjectInformation* info, Dwarf_Die* die,
604 const Dwarf_Die* /*unit*/,
605 const simgrid::mc::Frame* frame, const char* ns)
607 // Skip declarations:
608 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
611 // Skip compile time constants:
612 if (dwarf_hasattr(die, DW_AT_const_value))
615 Dwarf_Attribute attr_location;
616 if (dwarf_attr(die, DW_AT_location, &attr_location) == nullptr)
617 // No location: do not add it ?
620 auto variable = std::make_unique<simgrid::mc::Variable>();
621 variable->id = dwarf_dieoffset(die);
622 variable->global = frame == nullptr; // Can be override base on DW_AT_location
623 variable->object_info = info;
625 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
627 variable->name = name;
628 variable->type_id = MC_dwarf_at_type(die);
630 int form = dwarf_whatform(&attr_location);
631 simgrid::dwarf::FormClass form_class;
632 if (form == DW_FORM_sec_offset)
633 form_class = simgrid::dwarf::FormClass::Constant;
635 form_class = simgrid::dwarf::classify_form(form);
636 switch (form_class) {
637 case simgrid::dwarf::FormClass::ExprLoc:
638 case simgrid::dwarf::FormClass::Block:
639 // Location expression:
643 xbt_assert(not dwarf_getlocation(&attr_location, &expr, &len),
644 "Could not read location expression in DW_AT_location "
645 "of variable <%" PRIx64 ">%s",
646 (uint64_t)variable->id, variable->name.c_str());
648 if (len == 1 && expr[0].atom == DW_OP_addr) {
649 variable->global = true;
650 auto offset = static_cast<uintptr_t>(expr[0].number);
651 auto base = reinterpret_cast<uintptr_t>(info->base_address());
652 variable->address = reinterpret_cast<void*>(base + offset);
654 variable->location_list = {
655 simgrid::dwarf::LocationListEntry(simgrid::dwarf::DwarfExpression(expr, expr + len))};
660 case simgrid::dwarf::FormClass::LocListPtr:
661 case simgrid::dwarf::FormClass::Constant:
662 // Reference to location list:
663 variable->location_list = simgrid::dwarf::location_list(*info, attr_location);
667 xbt_die("Unexpected form 0x%x (%i), class 0x%x (%i) list for location in <%" PRIx64 ">%s", (unsigned)form, form,
668 (unsigned)form_class, (int)form_class, (uint64_t)variable->id, variable->name.c_str());
671 // Handle start_scope:
672 if (dwarf_hasattr(die, DW_AT_start_scope)) {
673 Dwarf_Attribute attr;
674 dwarf_attr(die, DW_AT_start_scope, &attr);
675 form = dwarf_whatform(&attr);
676 form_class = simgrid::dwarf::classify_form(form);
677 if (form_class == simgrid::dwarf::FormClass::Constant) {
679 variable->start_scope = dwarf_formudata(&attr, &value) == 0 ? (size_t)value : 0;
681 // TODO: FormClass::RangeListPtr
682 xbt_die("Unhandled form 0x%x, class 0x%X for DW_AT_start_scope of variable %s", (unsigned)form,
683 (unsigned)form_class, name == nullptr ? "?" : name);
687 if (ns && variable->global)
688 variable->name = std::string(ns) + "::" + variable->name;
690 // The current code needs a variable name,
691 // generate a fake one:
692 if (variable->name.empty()) {
693 variable->name = "@anonymous#" + std::to_string(mc_anonymous_variable_index);
694 mc_anonymous_variable_index++;
699 static void MC_dwarf_handle_variable_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, const Dwarf_Die* unit,
700 simgrid::mc::Frame* frame, const char* ns)
702 std::unique_ptr<simgrid::mc::Variable> variable = MC_die_to_variable(info, die, unit, frame, ns);
705 // Those arrays are sorted later:
706 if (variable->global)
707 info->global_variables.push_back(std::move(*variable));
708 else if (frame != nullptr)
709 frame->variables.push_back(std::move(*variable));
711 xbt_die("No frame for this local variable");
714 static void MC_dwarf_handle_scope_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
715 simgrid::mc::Frame* parent_frame, const char* ns)
717 // TODO, handle DW_TAG_type/DW_TAG_location for DW_TAG_with_stmt
718 int tag = dwarf_tag(die);
719 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
721 // (Template) Subprogram declaration:
722 if (klass == simgrid::dwarf::TagClass::Subprogram && MC_dwarf_attr_flag(die, DW_AT_declaration, false))
725 if (klass == simgrid::dwarf::TagClass::Scope)
726 xbt_assert(parent_frame, "No parent scope for this scope");
728 simgrid::mc::Frame frame;
730 frame.id = dwarf_dieoffset(die);
731 frame.object_info = info;
733 if (klass == simgrid::dwarf::TagClass::Subprogram) {
734 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
736 frame.name = std::string(ns) + "::" + name;
741 frame.abstract_origin_id = MC_dwarf_attr_dieoffset(die, DW_AT_abstract_origin);
743 // This is the base address for DWARF addresses.
744 // Relocated addresses are offset from this base address.
745 // See DWARF4 spec 7.5
746 auto base = reinterpret_cast<std::uint64_t>(info->base_address());
748 // TODO, support DW_AT_ranges
749 uint64_t low_pc = MC_dwarf_attr_integrate_addr(die, DW_AT_low_pc);
750 frame.range.begin() = low_pc ? base + low_pc : 0;
753 Dwarf_Attribute attr;
754 xbt_assert(dwarf_attr_integrate(die, DW_AT_high_pc, &attr), "Missing DW_AT_high_pc matching with DW_AT_low_pc");
759 switch (simgrid::dwarf::classify_form(dwarf_whatform(&attr))) {
760 // DW_AT_high_pc if an offset from the low_pc:
761 case simgrid::dwarf::FormClass::Constant:
763 xbt_assert(dwarf_formsdata(&attr, &offset) == 0, "Could not read constant");
764 frame.range.end() = frame.range.begin() + offset;
767 // DW_AT_high_pc is a relocatable address:
768 case simgrid::dwarf::FormClass::Address:
769 xbt_assert(dwarf_formaddr(&attr, &high_pc) == 0, "Could not read address");
770 frame.range.end() = base + high_pc;
774 xbt_die("Unexpected class for DW_AT_high_pc");
778 if (klass == simgrid::dwarf::TagClass::Subprogram) {
779 Dwarf_Attribute attr_frame_base;
780 if (dwarf_attr_integrate(die, DW_AT_frame_base, &attr_frame_base))
781 frame.frame_base_location = simgrid::dwarf::location_list(*info, attr_frame_base);
785 MC_dwarf_handle_children(info, die, unit, &frame, ns);
787 // We sort them in order to have an (somewhat) efficient by name
789 boost::range::sort(frame.variables, MC_compare_variable);
792 if (klass == simgrid::dwarf::TagClass::Subprogram)
793 info->subprograms[frame.id] = std::move(frame);
794 else if (klass == simgrid::dwarf::TagClass::Scope)
795 parent_frame->scopes.push_back(std::move(frame));
798 static void mc_dwarf_handle_namespace_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
799 simgrid::mc::Frame* frame, const char* ns)
801 const char* name = MC_dwarf_attr_integrate_string(die, DW_AT_name);
802 xbt_assert(not frame, "Unexpected namespace in a subprogram");
803 char* new_ns = ns == nullptr ? xbt_strdup(name) : bprintf("%s::%s", ns, name);
804 MC_dwarf_handle_children(info, die, unit, frame, new_ns);
808 static void MC_dwarf_handle_children(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
809 simgrid::mc::Frame* frame, const char* ns)
811 // For each child DIE:
813 for (int res = dwarf_child(die, &child); res == 0; res = dwarf_siblingof(&child, &child))
814 MC_dwarf_handle_die(info, &child, unit, frame, ns);
817 static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die* die, Dwarf_Die* unit,
818 simgrid::mc::Frame* frame, const char* ns)
820 int tag = dwarf_tag(die);
821 simgrid::dwarf::TagClass klass = simgrid::dwarf::classify_tag(tag);
824 case simgrid::dwarf::TagClass::Type:
825 MC_dwarf_handle_type_die(info, die, unit, frame, ns);
828 // Subprogram or scope:
829 case simgrid::dwarf::TagClass::Subprogram:
830 case simgrid::dwarf::TagClass::Scope:
831 MC_dwarf_handle_scope_die(info, die, unit, frame, ns);
835 case simgrid::dwarf::TagClass::Variable:
836 MC_dwarf_handle_variable_die(info, die, unit, frame, ns);
839 case simgrid::dwarf::TagClass::Namespace:
840 mc_dwarf_handle_namespace_die(info, die, unit, frame, ns);
848 static Elf64_Half get_type(Elf* elf)
850 const Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
852 return ehdr64->e_type;
853 const Elf32_Ehdr* ehdr32 = elf32_getehdr(elf);
855 return ehdr32->e_type;
856 xbt_die("Could not get ELF heeader");
859 static void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
861 // For each compilation unit:
862 Dwarf_Off offset = 0;
863 Dwarf_Off next_offset = 0;
866 while (dwarf_nextcu(dwarf, offset, &next_offset, &length, nullptr, nullptr, nullptr) == 0) {
868 if (dwarf_offdie(dwarf, offset + length, &unit_die) != nullptr)
869 MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, nullptr);
870 offset = next_offset;
874 /** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
876 * This build-id may is used to locate an external debug (DWARF) file
879 * @param elf libelf handle for an ELF file
880 * @return build-id for this ELF file (or an empty vector if none is found)
882 static std::vector<char> get_build_id(Elf* elf)
885 // Summary: the GNU build ID is stored in a ("GNU, NT_GNU_BUILD_ID) note
886 // found in a PT_NOTE entry in the program header table.
889 xbt_assert(elf_getphdrnum(elf, &phnum) == 0, "Could not read program headers");
891 // Iterate over the program headers and find the PT_NOTE ones:
892 for (size_t i = 0; i < phnum; ++i) {
894 const GElf_Phdr* phdr = gelf_getphdr(elf, i, &phdr_temp);
895 if (phdr->p_type != PT_NOTE)
898 Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
900 // Iterate over the notes and find the NT_GNU_BUILD_ID one:
902 while (pos < data->d_size) {
904 // Location of the name within Elf_Data:
907 pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
908 // A build ID note is identified by the pair ("GNU", NT_GNU_BUILD_ID)
909 // (a namespace and a type within this namespace):
910 if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU") &&
911 memcmp((char*)data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
912 XBT_DEBUG("Found GNU/NT_GNU_BUILD_ID note");
913 char* start = (char*)data->d_buf + desc_pos;
914 char* end = start + nhdr.n_descsz;
915 return std::vector<char>(start, end);
920 return std::vector<char>();
923 /** Binary data to hexadecimal */
924 static inline std::array<char, 2> to_hex(std::uint8_t byte)
926 constexpr std::array<char, 16> hexdigits{
927 {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}};
928 // Horrid double braces!
929 // Apparently, this is needed in C++11 (not in C++14).
930 return {{hexdigits[byte >> 4], hexdigits[byte & 0xF]}};
933 /** Binary data to hexadecimal */
934 static std::string to_hex(const char* data, std::size_t count)
937 res.resize(2 * count);
938 for (std::size_t i = 0; i < count; i++)
939 std::copy_n(cbegin(to_hex(data[i])), 2, &res[2 * i]);
943 /** Binary data to hexadecimal */
944 static std::string to_hex(std::vector<char> const& data)
946 return to_hex(data.data(), data.size());
949 /** Base directories for external debug files */
950 static constexpr auto debug_paths = {
952 "/usr/local/lib/debug/",
955 /** Locate an external debug file from the NT_GNU_BUILD_ID
957 * This is one of the mechanisms used for
958 * [separate debug files](https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html).
961 // /usr/lib/debug/.build-id/0b/dc77f1c29aea2b14ff5acd9a19ab3175ffdeae.debug
962 static std::string find_by_build_id(std::vector<char> id)
964 std::string filename;
965 std::string hex = to_hex(id);
966 for (const char* const& debug_path : debug_paths) {
968 filename = std::string(debug_path) + ".build-id/" + to_hex(id.data(), 1) + '/' +
969 to_hex(id.data() + 1, id.size() - 1) + ".debug";
970 XBT_DEBUG("Checking debug file: %s", filename.c_str());
971 if (access(filename.c_str(), F_OK) == 0) {
972 XBT_DEBUG("Found debug file: %s\n", hex.c_str());
976 XBT_DEBUG("No debug info found for build ID %s\n", hex.data());
977 return std::string();
980 /** @brief Populate the debugging information of the given ELF object
982 * Read the DWARf information of the EFFL object and populate the
983 * lists of types, variables, functions.
985 static void MC_load_dwarf(simgrid::mc::ObjectInformation* info)
987 xbt_assert(elf_version(EV_CURRENT) != EV_NONE, "libelf initialization error");
989 // Open the ELF file:
990 int fd = open(info->file_name.c_str(), O_RDONLY);
991 xbt_assert(fd >= 0, "Could not open file %s", info->file_name.c_str());
992 Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
993 xbt_assert(elf != nullptr, "Not an ELF file");
994 Elf_Kind kind = elf_kind(elf);
995 xbt_assert(kind == ELF_K_ELF, "Not an ELF file");
997 // Remember if this is a `ET_EXEC` (fixed location) or `ET_DYN`:
998 Elf64_Half type = get_type(elf);
1000 info->flags |= simgrid::mc::ObjectInformation::Executable;
1002 // Read DWARF debug information in the file:
1003 Dwarf* dwarf = dwarf_begin_elf(elf, DWARF_C_READ, nullptr);
1004 if (dwarf != nullptr) {
1005 read_dwarf_info(info, dwarf);
1013 // If there was no DWARF in the file, try to find it in a separate file.
1014 // Different methods might be used to store the DWARF information:
1015 // * GNU NT_GNU_BUILD_ID
1017 // See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
1018 // for reference of what we are doing.
1020 // Try with NT_GNU_BUILD_ID: we find the build ID in the ELF file and then
1021 // use this ID to find the file in some known locations in the filesystem.
1022 std::vector<char> build_id = get_build_id(elf);
1023 if (not build_id.empty()) {
1027 // Find the debug file using the build id:
1028 std::string debug_file = find_by_build_id(build_id);
1029 xbt_assert(not debug_file.empty(),
1030 "Missing debug info for %s with build-id %s\n"
1031 "You might want to install the suitable debugging package.\n",
1032 info->file_name.c_str(), to_hex(build_id).c_str());
1034 // Load the DWARF info from this file:
1035 XBT_DEBUG("Load DWARF for %s from %s", info->file_name.c_str(), debug_file.c_str());
1036 fd = open(debug_file.c_str(), O_RDONLY);
1037 xbt_assert(fd >= 0, "Could not open file %s", debug_file.c_str());
1038 dwarf = dwarf_begin(fd, DWARF_C_READ);
1039 xbt_assert(dwarf != nullptr, "No DWARF info in %s for %s", debug_file.c_str(), info->file_name.c_str());
1040 read_dwarf_info(info, dwarf);
1046 // TODO, try to find DWARF info using .gnu_debuglink.
1050 xbt_die("Debugging information not found for %s\n"
1051 "Try recompiling with -g\n",
1052 info->file_name.c_str());
1055 // ***** Functions index
1057 static void MC_make_functions_index(simgrid::mc::ObjectInformation* info)
1059 info->functions_index.clear();
1061 for (auto& e : info->subprograms) {
1062 if (e.second.range.begin() == 0)
1064 simgrid::mc::FunctionIndexEntry entry;
1065 entry.low_pc = (void*)e.second.range.begin();
1066 entry.function = &e.second;
1067 info->functions_index.push_back(entry);
1070 info->functions_index.shrink_to_fit();
1072 // Sort the array by low_pc:
1073 boost::range::sort(info->functions_index,
1074 [](simgrid::mc::FunctionIndexEntry const& a, simgrid::mc::FunctionIndexEntry const& b) {
1075 return a.low_pc < b.low_pc;
1079 static void MC_post_process_variables(simgrid::mc::ObjectInformation* info)
1081 // Someone needs this to be sorted but who?
1082 boost::range::sort(info->global_variables, MC_compare_variable);
1084 for (simgrid::mc::Variable& variable : info->global_variables)
1085 if (variable.type_id)
1086 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1089 static void mc_post_process_scope(simgrid::mc::ObjectInformation* info, simgrid::mc::Frame* scope)
1091 if (scope->tag == DW_TAG_inlined_subroutine) {
1092 // Attach correct namespaced name in inlined subroutine:
1093 auto i = info->subprograms.find(scope->abstract_origin_id);
1094 xbt_assert(i != info->subprograms.end(), "Could not lookup abstract origin %" PRIx64,
1095 (std::uint64_t)scope->abstract_origin_id);
1096 scope->name = i->second.name;
1100 for (simgrid::mc::Variable& variable : scope->variables)
1101 if (variable.type_id)
1102 variable.type = simgrid::util::find_map_ptr(info->types, variable.type_id);
1104 // Recursive post-processing of nested-scopes:
1105 for (simgrid::mc::Frame& nested_scope : scope->scopes)
1106 mc_post_process_scope(info, &nested_scope);
1109 static simgrid::mc::Type* MC_resolve_type(simgrid::mc::ObjectInformation* info, unsigned type_id)
1113 simgrid::mc::Type* type = simgrid::util::find_map_ptr(info->types, type_id);
1114 if (type == nullptr)
1117 // We already have the information on the type:
1118 if (type->byte_size != 0)
1121 // Don't have a name, we can't find a more complete version:
1122 if (type->name.empty())
1125 // Try to find a more complete description of the type:
1126 // We need to fix in order to support C++.
1127 simgrid::mc::Type** subtype = simgrid::util::find_map_ptr(info->full_types_by_name, type->name);
1133 static void MC_post_process_types(simgrid::mc::ObjectInformation* info)
1135 // Lookup "subtype" field:
1136 for (auto& i : info->types) {
1137 i.second.subtype = MC_resolve_type(info, i.second.type_id);
1138 for (simgrid::mc::Member& member : i.second.members)
1139 member.type = MC_resolve_type(info, member.type_id);
1146 /** @brief Finds information about a given shared object/executable */
1147 std::shared_ptr<ObjectInformation> createObjectInformation(std::vector<xbt::VmMap> const& maps, const char* name)
1149 auto result = std::make_shared<ObjectInformation>();
1150 result->file_name = name;
1151 simgrid::mc::find_object_address(maps, result.get());
1152 MC_load_dwarf(result.get());
1153 MC_post_process_variables(result.get());
1154 MC_post_process_types(result.get());
1155 for (auto& entry : result.get()->subprograms)
1156 mc_post_process_scope(result.get(), &entry.second);
1157 MC_make_functions_index(result.get());
1161 /*************************************************************************/
1163 void postProcessObjectInformation(const RemoteSimulation* process, ObjectInformation* info)
1165 for (auto& t : info->types) {
1166 Type* type = &(t.second);
1167 Type* subtype = type;
1168 while (subtype->type == DW_TAG_typedef || subtype->type == DW_TAG_volatile_type ||
1169 subtype->type == DW_TAG_const_type)
1170 if (subtype->subtype)
1171 subtype = subtype->subtype;
1175 // Resolve full_type:
1176 if (not subtype->name.empty() && subtype->byte_size == 0)
1177 for (auto const& object_info : process->object_infos) {
1178 auto i = object_info->full_types_by_name.find(subtype->name);
1179 if (i != object_info->full_types_by_name.end() && not i->second->name.empty() && i->second->byte_size) {
1180 type->full_type = i->second;
1185 type->full_type = subtype;
1190 } // namespace simgrid
1195 /** Convert a DWARF register into a libunwind register
1197 * DWARF and libunwind does not use the same convention for numbering the
1198 * registers on some architectures. The function makes the necessary
1201 int dwarf_register_to_libunwind(int dwarf_register)
1203 #if defined(__x86_64__)
1204 // It seems for this arch, DWARF and libunwind agree in the numbering:
1205 return dwarf_register;
1206 #elif defined(__i386__)
1207 // Couldn't find the authoritative source of information for this.
1208 // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
1209 constexpr std::array<int, 24> regs{
1210 {/* 0 */ UNW_X86_EAX, /* 1 */ UNW_X86_ECX, /* 2 */ UNW_X86_EDX, /* 3 */ UNW_X86_EBX,
1211 /* 4 */ UNW_X86_ESP, /* 5 */ UNW_X86_EBP, /* 6 */ UNW_X86_ESI, /* 7 */ UNW_X86_EDI,
1212 /* 8 */ UNW_X86_EIP, /* 9 */ UNW_X86_EFLAGS, /* 10 */ UNW_X86_CS, /* 11 */ UNW_X86_SS,
1213 /* 12 */ UNW_X86_DS, /* 13 */ UNW_X86_ES, /* 14 */ UNW_X86_FS, /* 15 */ UNW_X86_GS,
1214 /* 16 */ UNW_X86_ST0, /* 17 */ UNW_X86_ST1, /* 18 */ UNW_X86_ST2, /* 19 */ UNW_X86_ST3,
1215 /* 20 */ UNW_X86_ST4, /* 21 */ UNW_X86_ST5, /* 22 */ UNW_X86_ST6, /* 23 */ UNW_X86_ST7}};
1216 return regs.at(dwarf_register);
1218 #error This architecture is not supported yet for DWARF expression evaluation.
1222 } // namespace dwarf
1223 } // namespace simgrid