1 /* Copyright (c) 2014-2020. 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 "src/mc/mc_private.hpp"
14 #include "xbt/file.hpp"
19 /* For an executable object, addresses are virtual address (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 beginning of the shared object (the base address of the
23 * mapped shared object must be used as offset
24 * i.e. \f$\text{virtual address} = \text{shared object base address}
25 * + \text{dwarf address}\f$.
27 void* ObjectInformation::base_address() const
29 // For an executable (more precisely for an ET_EXEC) the base it 0:
30 if (this->executable())
33 // For an a shared-object (ET_DYN, including position-independent executables) the base address is its lowest address:
34 void* result = this->start_exec;
35 if (this->start_rw != nullptr && result > (void*)this->start_rw)
36 result = this->start_rw;
37 if (this->start_ro != nullptr && result > (void*)this->start_ro)
38 result = this->start_ro;
42 Frame* ObjectInformation::find_function(const void* ip) const
44 /* This is implemented by binary search on a sorted array.
46 * We do quite a lot of those so we want this to be cache efficient.
47 * We pack the only information we need in the index entries in order
48 * to successfully do the binary search. We do not need the high_pc
49 * during the binary search (only at the end) so it is not included
50 * in the index entry. We could use parallel arrays as well.
52 * We cannot really use the std:: algorithm for this.
53 * We could use std::binary_search by including the high_pc inside
54 * the FunctionIndexEntry.
56 const FunctionIndexEntry* base = this->functions_index.data();
58 int j = this->functions_index.size() - 1;
60 int k = i + ((j - i) / 2);
62 /* In most of the search, we do not dereference the base[k].function.
63 * This way the memory accesses are located in the base[k] array. */
64 if (ip < base[k].low_pc)
66 else if (k < j && ip >= base[k + 1].low_pc)
69 /* At this point, the search is over.
70 * Either we have found the correct function or we do not know
71 * any function corresponding to this instruction address.
72 * Only at the point do we dereference the function pointer. */
73 else if ((std::uint64_t)ip < base[k].function->range.end())
74 return base[k].function;
81 const Variable* ObjectInformation::find_variable(const char* name) const
83 for (Variable const& variable : this->global_variables) {
84 if (variable.name == name)
90 void ObjectInformation::remove_global_variable(const char* name)
92 typedef std::vector<Variable>::size_type size_type;
94 if (this->global_variables.empty())
99 size_type last = this->global_variables.size() - 1;
101 while (first <= last) {
102 size_type cursor = first + (last - first) / 2;
103 const Variable& current_var = this->global_variables[cursor];
104 int cmp = current_var.name.compare(name);
107 // Find the whole range:
109 while (first != 0 && this->global_variables[first - 1].name == name)
111 size_type size = this->global_variables.size();
113 while (last != size - 1 && this->global_variables[last + 1].name == name)
116 // Remove the whole range:
117 this->global_variables.erase(this->global_variables.begin() + first, this->global_variables.begin() + last + 1);
122 else if (cursor != 0)
129 /** Ignore a local variable in a scope
131 * Ignore all instances of variables with a given name in any (possibly inlined) subprogram with a given namespaced
134 * @param var_name Name of the local variable to ignore
135 * @param subprogram_name Name of the subprogram to ignore (nullptr for any)
136 * @param subprogram (possibly inlined) Subprogram of the scope current scope
137 * @param scope Current scope
139 static void remove_local_variable(Frame& scope, const char* var_name, const char* subprogram_name,
140 Frame const& subprogram)
142 typedef std::vector<Variable>::size_type size_type;
144 // If the current subprogram matches the given name:
145 if ((subprogram_name == nullptr || (not subprogram.name.empty() && subprogram.name == subprogram_name)) &&
146 not scope.variables.empty()) {
147 // Try to find the variable and remove it:
149 size_type end = scope.variables.size() - 1;
152 while (start <= end) {
153 size_type cursor = start + (end - start) / 2;
154 const Variable& current_var = scope.variables[cursor];
155 int compare = current_var.name.compare(var_name);
157 // Variable found, remove it:
158 scope.variables.erase(scope.variables.begin() + cursor);
160 } else if (compare < 0)
162 else if (cursor != 0)
169 // And recursive processing in nested scopes:
170 for (Frame& nested_scope : scope.scopes) {
171 // The new scope may be an inlined subroutine, in this case we want to use its
172 // namespaced name in recursive calls:
173 Frame const& nested_subprogram = nested_scope.tag == DW_TAG_inlined_subroutine ? nested_scope : subprogram;
174 remove_local_variable(nested_scope, var_name, subprogram_name, nested_subprogram);
178 void ObjectInformation::remove_local_variable(const char* var_name, const char* subprogram_name)
180 for (auto& entry : this->subprograms)
181 mc::remove_local_variable(entry.second, var_name, subprogram_name, entry.second);
184 /** @brief Fills the position of the segments (executable, read-only, read/write) */
185 // TODO, use the ELF segment information for more robustness
186 void find_object_address(std::vector<xbt::VmMap> const& maps, ObjectInformation* result)
188 const int PROT_RW = PROT_READ | PROT_WRITE;
189 const int PROT_RX = PROT_READ | PROT_EXEC;
191 std::string name = xbt::Path(result->file_name).get_base_name();
193 for (size_t i = 0; i < maps.size(); ++i) {
194 simgrid::xbt::VmMap const& reg = maps[i];
195 if (maps[i].pathname.empty())
197 std::string map_basename = simgrid::xbt::Path(maps[i].pathname).get_base_name();
198 if (map_basename != name)
201 // This is the non-GNU_RELRO-part of the data segment:
202 if (reg.prot == PROT_RW) {
203 xbt_assert(not result->start_rw, "Multiple read-write segments for %s, not supported", maps[i].pathname.c_str());
204 result->start_rw = (char*)reg.start_addr;
205 result->end_rw = (char*)reg.end_addr;
207 // The next VMA might be end of the data segment:
208 if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
209 maps[i + 1].start_addr == reg.end_addr)
210 result->end_rw = (char*)maps[i + 1].end_addr;
213 // This is the text segment:
214 else if (reg.prot == PROT_RX) {
215 xbt_assert(not result->start_exec, "Multiple executable segments for %s, not supported",
216 maps[i].pathname.c_str());
217 result->start_exec = (char*)reg.start_addr;
218 result->end_exec = (char*)reg.end_addr;
220 // The next VMA might be end of the data segment:
221 if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
222 maps[i + 1].start_addr == reg.end_addr) {
223 result->start_rw = (char*)maps[i + 1].start_addr;
224 result->end_rw = (char*)maps[i + 1].end_addr;
228 // This is the GNU_RELRO-part of the data segment:
229 else if (reg.prot == PROT_READ) {
230 xbt_assert(not result->start_ro,
231 "Multiple read-only segments for %s, not supported. Compiling with the following may help: "
232 "-Wl,-znorelro -Wl,-znoseparate-code",
233 maps[i].pathname.c_str());
234 result->start_ro = (char*)reg.start_addr;
235 result->end_ro = (char*)reg.end_addr;
239 result->start = result->start_rw;
240 if ((const void*)result->start_ro < result->start)
241 result->start = result->start_ro;
242 if ((const void*)result->start_exec < result->start)
243 result->start = result->start_exec;
245 result->end = result->end_rw;
246 if (result->end_ro && (const void*)result->end_ro > result->end)
247 result->end = result->end_ro;
248 if (result->end_exec && (const void*)result->end_exec > result->end)
249 result->end = result->end_exec;
251 xbt_assert(result->start_exec || result->start_rw || result->start_ro);
255 } // namespace simgrid