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 "src/mc/mc_private.hpp"
14 #include "xbt/file.hpp"
19 /* For an executable object, addresses are virtual address
20 * (there is no offset) i.e.
21 * \f$\text{virtual address} = \{dwarf address}\f$
23 * For a shared object, the addresses are offset from the begining
24 * of the shared object (the base address of the mapped shared
25 * object must be used as offset
26 * i.e. \f$\text{virtual address} = \text{shared object base address}
27 * + \text{dwarf address}\f$.
29 void* ObjectInformation::base_address() const
31 // For an executable (more precisely for a ET_EXEC) the base it 0:
32 if (this->executable())
35 // For an a shared-object (ET_DYN, including position-independent executables)
36 // the base address is its lowest address:
37 void* result = this->start_exec;
38 if (this->start_rw != nullptr && result > (void*)this->start_rw)
39 result = this->start_rw;
40 if (this->start_ro != nullptr && result > (void*)this->start_ro)
41 result = this->start_ro;
45 simgrid::mc::Frame* ObjectInformation::find_function(const void* ip) const
47 /* This is implemented by binary search on a sorted array.
49 * We do quite a lot of those so we want this to be cache efficient.
50 * We pack the only information we need in the index entries in order
51 * to successfully do the binary search. We do not need the high_pc
52 * during the binary search (only at the end) so it is not included
53 * in the index entry. We could use parallel arrays as well.
55 * We cannot really use the std:: algorithm for this.
56 * We could use std::binary_search by including the high_pc inside
57 * the FunctionIndexEntry.
59 const simgrid::mc::FunctionIndexEntry* base = this->functions_index.data();
61 int j = this->functions_index.size() - 1;
63 int k = i + ((j - i) / 2);
65 /* In most of the search, we do not dereference the base[k].function.
66 * This way the memory accesses are located in the base[k] array. */
67 if (ip < base[k].low_pc)
69 else if (k < j && ip >= base[k + 1].low_pc)
72 /* At this point, the search is over.
73 * Either we have found the correct function or we do not know
74 * any function corresponding to this instruction address.
75 * Only at the point do we dereference the function pointer. */
76 else if ((std::uint64_t)ip < base[k].function->range.end())
77 return base[k].function;
84 const simgrid::mc::Variable* ObjectInformation::find_variable(const char* name) const
86 for (simgrid::mc::Variable const& variable : this->global_variables) {
87 if (variable.name == name)
93 void ObjectInformation::remove_global_variable(const char* name)
95 typedef std::vector<Variable>::size_type size_type;
97 if (this->global_variables.empty())
102 size_type last = this->global_variables.size() - 1;
104 while (first <= last) {
105 size_type cursor = first + (last - first) / 2;
106 simgrid::mc::Variable& current_var = this->global_variables[cursor];
107 int cmp = current_var.name.compare(name);
111 // Find the whole range:
113 while (first != 0 && this->global_variables[first - 1].name == name)
115 size_type size = this->global_variables.size();
117 while (last != size - 1 && this->global_variables[last + 1].name == name)
120 // Remove the whole range:
121 this->global_variables.erase(this->global_variables.begin() + first, this->global_variables.begin() + last + 1);
126 else if (cursor != 0)
133 /** Ignore a local variable in a scope
135 * Ignore all instances of variables with a given name in
136 * any (possibly inlined) subprogram with a given namespaced
139 * @param var_name Name of the local variable to ignore
140 * @param subprogram_name Name of the subprogram to ignore (nullptr for any)
141 * @param subprogram (possibly inlined) Subprogram of the scope current scope
142 * @param scope Current scope
144 static void remove_local_variable(simgrid::mc::Frame& scope, const char* var_name, const char* subprogram_name,
145 simgrid::mc::Frame const& subprogram)
147 typedef std::vector<Variable>::size_type size_type;
149 // If the current subprogram matches the given name:
150 if ((subprogram_name == nullptr || (not subprogram.name.empty() && subprogram.name == subprogram_name)) &&
151 not scope.variables.empty()) {
153 // Try to find the variable and remove it:
155 size_type end = scope.variables.size() - 1;
158 while (start <= end) {
159 size_type cursor = start + (end - start) / 2;
160 simgrid::mc::Variable& current_var = scope.variables[cursor];
161 int compare = current_var.name.compare(var_name);
163 // Variable found, remove it:
164 scope.variables.erase(scope.variables.begin() + cursor);
166 } else if (compare < 0)
168 else if (cursor != 0)
175 // And recursive processing in nested scopes:
176 for (simgrid::mc::Frame& nested_scope : scope.scopes) {
177 // The new scope may be an inlined subroutine, in this case we want to use its
178 // namespaced name in recursive calls:
179 simgrid::mc::Frame const& nested_subprogram =
180 nested_scope.tag == DW_TAG_inlined_subroutine ? nested_scope : subprogram;
181 remove_local_variable(nested_scope, var_name, subprogram_name, nested_subprogram);
185 void ObjectInformation::remove_local_variable(const char* var_name, const char* subprogram_name)
187 for (auto& entry : this->subprograms)
188 simgrid::mc::remove_local_variable(entry.second, var_name, subprogram_name, entry.second);
191 /** @brief Fills the position of the segments (executable, read-only, read/write) */
192 // TODO, use the ELF segment information for more robustness
193 void find_object_address(std::vector<simgrid::xbt::VmMap> const& maps, simgrid::mc::ObjectInformation* result)
195 const int PROT_RW = PROT_READ | PROT_WRITE;
196 const int PROT_RX = PROT_READ | PROT_EXEC;
198 std::string name = simgrid::xbt::Path(result->file_name).get_base_name();
200 for (size_t i = 0; i < maps.size(); ++i) {
201 simgrid::xbt::VmMap const& reg = maps[i];
202 if (maps[i].pathname.empty())
204 std::string map_basename = simgrid::xbt::Path(maps[i].pathname).get_base_name();
205 if (map_basename != name)
208 // This is the non-GNU_RELRO-part of the data segment:
209 if (reg.prot == PROT_RW) {
210 xbt_assert(not result->start_rw, "Multiple read-write segments for %s, not supported", maps[i].pathname.c_str());
211 result->start_rw = (char*)reg.start_addr;
212 result->end_rw = (char*)reg.end_addr;
214 // The next VMA might be end of the data segment:
215 if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
216 maps[i + 1].start_addr == reg.end_addr)
217 result->end_rw = (char*)maps[i + 1].end_addr;
220 // This is the text segment:
221 else if (reg.prot == PROT_RX) {
222 xbt_assert(not result->start_exec, "Multiple executable segments for %s, not supported",
223 maps[i].pathname.c_str());
224 result->start_exec = (char*)reg.start_addr;
225 result->end_exec = (char*)reg.end_addr;
227 // The next VMA might be end of the data segment:
228 if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
229 maps[i + 1].start_addr == reg.end_addr) {
230 result->start_rw = (char*)maps[i + 1].start_addr;
231 result->end_rw = (char*)maps[i + 1].end_addr;
235 // This is the GNU_RELRO-part of the data segment:
236 else if (reg.prot == PROT_READ) {
237 xbt_assert(not result->start_ro,
238 "Multiple read-only segments for %s, not supported. Compiling with the following may help: "
239 "-Wl,-znorelro -Wl,-znoseparate-code",
240 maps[i].pathname.c_str());
241 result->start_ro = (char*)reg.start_addr;
242 result->end_ro = (char*)reg.end_addr;
246 result->start = result->start_rw;
247 if ((const void*)result->start_ro < result->start)
248 result->start = result->start_ro;
249 if ((const void*)result->start_exec < result->start)
250 result->start = result->start_exec;
252 result->end = result->end_rw;
253 if (result->end_ro && (const void*)result->end_ro > result->end)
254 result->end = result->end_ro;
255 if (result->end_exec && (const void*)result->end_exec > result->end)
256 result->end = result->end_exec;
258 xbt_assert(result->start_exec || result->start_rw || result->start_ro);
262 } // namespace simgrid