1 /* Copyright (c) 2014-2019. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
7 #include <sys/mman.h> // PROT_READ and friends
10 #include "src/mc/inspect/Frame.hpp"
11 #include "src/mc/inspect/ObjectInformation.hpp"
12 #include "src/mc/inspect/Variable.hpp"
13 #include "xbt/file.hpp"
18 /* For an executable object, addresses are virtual address
19 * (there is no offset) i.e.
20 * \f$\text{virtual address} = \{dwarf address}\f$
22 * For a shared object, the addresses are offset from the begining
23 * of the shared object (the base address of the mapped shared
24 * object must be used as offset
25 * i.e. \f$\text{virtual address} = \text{shared object base address}
26 * + \text{dwarf address}\f$.
28 void* ObjectInformation::base_address() const
30 // For an executable (more precisely for a ET_EXEC) the base it 0:
31 if (this->executable())
34 // For an a shared-object (ET_DYN, including position-independent executables)
35 // the base address is its lowest address:
36 void* result = this->start_exec;
37 if (this->start_rw != nullptr && result > (void*)this->start_rw)
38 result = this->start_rw;
39 if (this->start_ro != nullptr && result > (void*)this->start_ro)
40 result = this->start_ro;
44 simgrid::mc::Frame* ObjectInformation::find_function(const void* ip) const
46 /* This is implemented by binary search on a sorted array.
48 * We do quite a lot of those so we want this to be cache efficient.
49 * We pack the only information we need in the index entries in order
50 * to successfully do the binary search. We do not need the high_pc
51 * during the binary search (only at the end) so it is not included
52 * in the index entry. We could use parallel arrays as well.
54 * We cannot really use the std:: algorithm for this.
55 * We could use std::binary_search by including the high_pc inside
56 * the FunctionIndexEntry.
58 const simgrid::mc::FunctionIndexEntry* base = this->functions_index.data();
60 int j = this->functions_index.size() - 1;
62 int k = i + ((j - i) / 2);
64 /* In most of the search, we do not dereference the base[k].function.
65 * This way the memory accesses are located in the base[k] array. */
66 if (ip < base[k].low_pc)
68 else if (k < j && ip >= base[k + 1].low_pc)
71 /* At this point, the search is over.
72 * Either we have found the correct function or we do not know
73 * any function corresponding to this instruction address.
74 * Only at the point do we dereference the function pointer. */
75 else if ((std::uint64_t)ip < base[k].function->range.end())
76 return base[k].function;
83 const simgrid::mc::Variable* ObjectInformation::find_variable(const char* name) const
85 for (simgrid::mc::Variable const& variable : this->global_variables)
86 if (variable.name == name)
91 void ObjectInformation::remove_global_variable(const char* name)
93 typedef std::vector<Variable>::size_type size_type;
95 if (this->global_variables.empty())
100 size_type last = this->global_variables.size() - 1;
102 while (first <= last) {
103 size_type cursor = first + (last - first) / 2;
104 simgrid::mc::Variable& current_var = this->global_variables[cursor];
105 int cmp = current_var.name.compare(name);
109 // Find the whole range:
111 while (first != 0 && this->global_variables[first - 1].name == name)
113 size_type size = this->global_variables.size();
115 while (last != size - 1 && this->global_variables[last + 1].name == name)
118 // Remove the whole range:
119 this->global_variables.erase(this->global_variables.begin() + first, this->global_variables.begin() + last + 1);
124 else if (cursor != 0)
131 /** Ignore a local variable in a scope
133 * Ignore all instances of variables with a given name in
134 * any (possibly inlined) subprogram with a given namespaced
137 * @param var_name Name of the local variable to ignore
138 * @param subprogram_name Name of the subprogram to ignore (nullptr for any)
139 * @param subprogram (possibly inlined) Subprogram of the scope current scope
140 * @param scope Current scope
142 static void remove_local_variable(simgrid::mc::Frame& scope, const char* var_name, const char* subprogram_name,
143 simgrid::mc::Frame const& subprogram)
145 typedef std::vector<Variable>::size_type size_type;
147 // If the current subprogram matches the given name:
148 if ((subprogram_name == nullptr || (not subprogram.name.empty() && subprogram.name == subprogram_name)) &&
149 not scope.variables.empty()) {
151 // Try to find the variable and remove it:
153 size_type end = scope.variables.size() - 1;
156 while (start <= end) {
157 size_type cursor = start + (end - start) / 2;
158 simgrid::mc::Variable& current_var = scope.variables[cursor];
159 int compare = current_var.name.compare(var_name);
161 // Variable found, remove it:
162 scope.variables.erase(scope.variables.begin() + cursor);
164 } else if (compare < 0)
166 else if (cursor != 0)
173 // And recursive processing in nested scopes:
174 for (simgrid::mc::Frame& nested_scope : scope.scopes) {
175 // The new scope may be an inlined subroutine, in this case we want to use its
176 // namespaced name in recursive calls:
177 simgrid::mc::Frame const& nested_subprogram =
178 nested_scope.tag == DW_TAG_inlined_subroutine ? nested_scope : subprogram;
179 remove_local_variable(nested_scope, var_name, subprogram_name, nested_subprogram);
183 void ObjectInformation::remove_local_variable(const char* var_name, const char* subprogram_name)
185 for (auto& entry : this->subprograms)
186 simgrid::mc::remove_local_variable(entry.second, var_name, subprogram_name, entry.second);
189 /** @brief Fills the position of the segments (executable, read-only, read/write) */
190 // TODO, use the ELF segment information for more robustness
191 void find_object_address(std::vector<simgrid::xbt::VmMap> const& maps, simgrid::mc::ObjectInformation* result)
193 const int PROT_RW = PROT_READ | PROT_WRITE;
194 const int PROT_RX = PROT_READ | PROT_EXEC;
196 std::string name = simgrid::xbt::Path(result->file_name).get_base_name();
198 for (size_t i = 0; i < maps.size(); ++i) {
199 simgrid::xbt::VmMap const& reg = maps[i];
200 if (maps[i].pathname.empty())
202 std::string map_basename = simgrid::xbt::Path(maps[i].pathname).get_base_name();
203 if (map_basename != name)
206 // This is the non-GNU_RELRO-part of the data segment:
207 if (reg.prot == PROT_RW) {
208 xbt_assert(not result->start_rw, "Multiple read-write segments for %s, not supported", maps[i].pathname.c_str());
209 result->start_rw = (char*)reg.start_addr;
210 result->end_rw = (char*)reg.end_addr;
212 // The next VMA might be end of the data segment:
213 if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
214 maps[i + 1].start_addr == reg.end_addr)
215 result->end_rw = (char*)maps[i + 1].end_addr;
218 // This is the text segment:
219 else if (reg.prot == PROT_RX) {
220 xbt_assert(not result->start_exec, "Multiple executable segments for %s, not supported",
221 maps[i].pathname.c_str());
222 result->start_exec = (char*)reg.start_addr;
223 result->end_exec = (char*)reg.end_addr;
225 // The next VMA might be end of the data segment:
226 if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
227 maps[i + 1].start_addr == reg.end_addr) {
228 result->start_rw = (char*)maps[i + 1].start_addr;
229 result->end_rw = (char*)maps[i + 1].end_addr;
233 // This is the GNU_RELRO-part of the data segment:
234 else if (reg.prot == PROT_READ) {
235 xbt_assert(not result->start_ro, "Multiple read only segments for %s, not supported", maps[i].pathname.c_str());
236 result->start_ro = (char*)reg.start_addr;
237 result->end_ro = (char*)reg.end_addr;
241 result->start = result->start_rw;
242 if ((const void*)result->start_ro < result->start)
243 result->start = result->start_ro;
244 if ((const void*)result->start_exec < result->start)
245 result->start = result->start_exec;
247 result->end = result->end_rw;
248 if (result->end_ro && (const void*)result->end_ro > result->end)
249 result->end = result->end_ro;
250 if (result->end_exec && (const void*)result->end_exec > result->end)
251 result->end = result->end_exec;
253 xbt_assert(result->start_exec || result->start_rw || result->start_ro);
257 } // namespace simgrid