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. */
6 #include <cstddef> /* std::size_t */
8 #include "src/mc/mc_config.hpp"
9 #include "src/mc/mc_hash.hpp"
10 #include "src/mc/mc_smx.hpp"
11 #include "src/mc/sosp/mc_snapshot.hpp"
13 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_snapshot, mc, "Taking and restoring snapshots");
15 /** @brief Read memory from a snapshot region broken across fragmented pages
17 * @param addr Process (non-snapshot) address of the data
18 * @param region Snapshot memory region where the data is located
19 * @param target Buffer to store the value
20 * @param size Size of the data to read in bytes
21 * @return Pointer where the data is located (target buffer of original location)
23 const void* MC_region_read_fragmented(simgrid::mc::RegionSnapshot* region, void* target, const void* addr, size_t size)
25 // Last byte of the memory area:
26 void* end = (char*)addr + size - 1;
28 // TODO, we assume the chunks are aligned to natural chunk boundaries.
29 // We should remove this assumption.
31 // Page of the last byte of the memory area:
32 size_t page_end = simgrid::mc::mmu::split((std::uintptr_t)end).first;
37 xbt_die("Missing destination buffer for fragmented memory access");
40 while (simgrid::mc::mmu::split((std::uintptr_t)addr).first != page_end) {
41 void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, region);
42 void* next_page = (void*)simgrid::mc::mmu::join(simgrid::mc::mmu::split((std::uintptr_t)addr).first + 1, 0);
43 size_t readable = (char*)next_page - (char*)addr;
44 memcpy(dest, snapshot_addr, readable);
45 addr = (char*)addr + readable;
46 dest = (char*)dest + readable;
51 void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, region);
52 memcpy(dest, snapshot_addr, size);
57 /** Compare memory between snapshots (with known regions)
59 * @param addr1 Address in the first snapshot
60 * @param region1 Region of the address in the first snapshot
61 * @param addr2 Address in the second snapshot
62 * @param region2 Region of the address in the second snapshot
63 * @return same semantic as memcmp
65 int MC_snapshot_region_memcmp(const void* addr1, simgrid::mc::RegionSnapshot* region1, const void* addr2,
66 simgrid::mc::RegionSnapshot* region2, size_t size)
68 // Using alloca() for large allocations may trigger stack overflow:
69 // use malloc if the buffer is too big.
70 bool stack_alloc = size < 64;
71 void* buffer1a = stack_alloc ? alloca(size) : ::operator new(size);
72 void* buffer2a = stack_alloc ? alloca(size) : ::operator new(size);
73 const void* buffer1 = MC_region_read(region1, buffer1a, addr1, size);
74 const void* buffer2 = MC_region_read(region2, buffer2a, addr2, size);
76 if (buffer1 == buffer2)
79 res = memcmp(buffer1, buffer2, size);
80 if (not stack_alloc) {
81 ::operator delete(buffer1a);
82 ::operator delete(buffer2a);
89 /************************************* Take Snapshot ************************************/
90 /****************************************************************************************/
92 void simgrid::mc::Snapshot::snapshot_regions(simgrid::mc::RemoteClient* process)
94 snapshot_regions_.clear();
96 for (auto const& object_info : process->object_infos)
97 add_region(simgrid::mc::RegionType::Data, object_info.get(), object_info->start_rw, object_info->start_rw,
98 object_info->end_rw - object_info->start_rw);
100 xbt_mheap_t heap = process->get_heap();
101 void* start_heap = heap->base;
102 void* end_heap = heap->breakval;
104 add_region(simgrid::mc::RegionType::Heap, nullptr, start_heap, start_heap, (char*)end_heap - (char*)start_heap);
105 heap_bytes_used_ = mmalloc_get_bytes_used_remote(heap->heaplimit, process->get_malloc_info());
108 /** @brief Checks whether the variable is in scope for a given IP.
110 * A variable may be defined only from a given value of IP.
112 * @param var Variable description
113 * @param scope Scope description
114 * @param ip Instruction pointer
115 * @return true if the variable is valid
117 static bool valid_variable(simgrid::mc::Variable* var, simgrid::mc::Frame* scope, const void* ip)
119 // The variable is not yet valid:
120 if (scope->range.begin() + var->start_scope > (std::uint64_t)ip)
126 static void fill_local_variables_values(mc_stack_frame_t stack_frame, simgrid::mc::Frame* scope,
127 std::vector<s_local_variable_t>& result)
129 if (not scope || not scope->range.contain(stack_frame->ip))
132 for (simgrid::mc::Variable& current_variable : scope->variables) {
134 if (not valid_variable(¤t_variable, scope, (void*)stack_frame->ip))
137 s_local_variable_t new_var;
138 new_var.subprogram = stack_frame->frame;
139 new_var.ip = stack_frame->ip;
140 new_var.name = current_variable.name;
141 new_var.type = current_variable.type;
142 new_var.address = nullptr;
144 if (current_variable.address != nullptr)
145 new_var.address = current_variable.address;
146 else if (not current_variable.location_list.empty()) {
147 simgrid::dwarf::Location location = simgrid::dwarf::resolve(
148 current_variable.location_list, current_variable.object_info, &(stack_frame->unw_cursor),
149 (void*)stack_frame->frame_base, &mc_model_checker->process());
151 if (not location.in_memory())
152 xbt_die("Cannot handle non-address variable");
153 new_var.address = location.address();
156 xbt_die("No address");
158 result.push_back(std::move(new_var));
161 // Recursive processing of nested scopes:
162 for (simgrid::mc::Frame& nested_scope : scope->scopes)
163 fill_local_variables_values(stack_frame, &nested_scope, result);
166 static std::vector<s_local_variable_t> get_local_variables_values(std::vector<s_mc_stack_frame_t>& stack_frames)
168 std::vector<s_local_variable_t> variables;
169 for (s_mc_stack_frame_t& stack_frame : stack_frames)
170 fill_local_variables_values(&stack_frame, stack_frame.frame, variables);
174 static std::vector<s_mc_stack_frame_t> unwind_stack_frames(simgrid::mc::UnwindContext* stack_context)
176 simgrid::mc::RemoteClient* process = &mc_model_checker->process();
177 std::vector<s_mc_stack_frame_t> result;
179 unw_cursor_t c = stack_context->cursor();
181 // TODO, check condition check (unw_init_local==0 means end of frame)
185 s_mc_stack_frame_t stack_frame;
187 stack_frame.unw_cursor = c;
192 unw_get_reg(&c, UNW_REG_IP, &ip);
193 unw_get_reg(&c, UNW_REG_SP, &sp);
198 // TODO, use real addresses in frame_t instead of fixing it here
200 simgrid::mc::Frame* frame = process->find_function(remote(ip));
201 stack_frame.frame = frame;
204 stack_frame.frame_name = frame->name;
205 stack_frame.frame_base = (unw_word_t)frame->frame_base(c);
207 stack_frame.frame_base = 0;
208 stack_frame.frame_name = std::string();
211 result.push_back(std::move(stack_frame));
213 /* Stop before context switch with maestro */
214 if (frame != nullptr && frame->name == "smx_ctx_wrapper")
217 int ret = unw_step(&c);
219 xbt_die("Unexpected end of stack.");
221 xbt_die("Error while unwinding stack");
224 xbt_assert(not result.empty(), "unw_init_local failed");
229 void simgrid::mc::Snapshot::snapshot_stacks(simgrid::mc::RemoteClient* process)
231 for (auto const& stack : process->stack_areas()) {
232 s_mc_snapshot_stack_t st;
234 // Read the context from remote process:
235 unw_context_t context;
236 mc_model_checker->process().read_bytes(&context, sizeof(context), remote(stack.context));
238 st.context.initialize(&mc_model_checker->process(), &context);
240 st.stack_frames = unwind_stack_frames(&st.context);
241 st.local_variables = get_local_variables_values(st.stack_frames);
243 unw_word_t sp = st.stack_frames[0].sp;
245 stacks_.push_back(std::move(st));
247 size_t stack_size = (char*)stack.address + stack.size - (char*)sp;
248 stack_sizes_.push_back(stack_size);
252 static void snapshot_handle_ignore(simgrid::mc::Snapshot* snapshot)
254 xbt_assert(snapshot->process());
257 for (auto const& region : mc_model_checker->process().ignored_regions()) {
258 s_mc_snapshot_ignored_data_t ignored_data;
259 ignored_data.start = (void*)region.addr;
260 ignored_data.data.resize(region.size);
261 // TODO, we should do this once per privatization segment:
262 snapshot->process()->read_bytes(ignored_data.data.data(), region.size, remote(region.addr));
263 snapshot->ignored_data_.push_back(std::move(ignored_data));
267 for (auto const& region : mc_model_checker->process().ignored_regions())
268 snapshot->process()->clear_bytes(remote(region.addr), region.size);
270 static void snapshot_ignore_restore(simgrid::mc::Snapshot* snapshot)
272 for (auto const& ignored_data : snapshot->ignored_data_)
273 snapshot->process()->write_bytes(ignored_data.data.data(), ignored_data.data.size(), remote(ignored_data.start));
276 Snapshot::Snapshot(int _num_state, RemoteClient* process)
277 : AddressSpace(process)
278 , num_state_(_num_state)
279 , heap_bytes_used_(0)
280 , enabled_processes_()
283 for (auto const& p : process->actors())
284 enabled_processes_.insert(p.copy.get_buffer()->get_pid());
286 snapshot_handle_ignore(this);
288 /* Save the std heap and the writable mapped pages of libsimgrid and binary */
289 snapshot_regions(process);
291 to_ignore_ = process->ignored_heap();
293 if (_sg_mc_max_visited_states > 0 || not _sg_mc_property_file.get().empty()) {
294 snapshot_stacks(process);
296 hash_ = simgrid::mc::hash(*this);
299 snapshot_ignore_restore(this);
302 void Snapshot::add_region(RegionType type, ObjectInformation* object_info, void* start_addr, void* permanent_addr,
305 if (type == simgrid::mc::RegionType::Data)
306 xbt_assert(object_info, "Missing object info for object.");
307 else if (type == simgrid::mc::RegionType::Heap)
308 xbt_assert(not object_info, "Unexpected object info for heap region.");
310 simgrid::mc::RegionSnapshot* region = simgrid::mc::region(type, start_addr, permanent_addr, size);
311 region->object_info(object_info);
312 snapshot_regions_.push_back(std::unique_ptr<simgrid::mc::RegionSnapshot>(std::move(region)));
315 const void* Snapshot::read_bytes(void* buffer, std::size_t size, RemotePtr<void> address, ReadOptions options) const
317 RegionSnapshot* region = this->get_region((void*)address.address());
319 const void* res = MC_region_read(region, buffer, (void*)address.address(), size);
320 if (buffer == res || options & ReadOptions::lazy())
323 memcpy(buffer, res, size);
327 return this->process()->read_bytes(buffer, size, address, options);
329 /** @brief Find the snapshoted region from a pointer
331 * @param addr Pointer
333 RegionSnapshot* Snapshot::get_region(const void* addr) const
335 size_t n = snapshot_regions_.size();
336 for (size_t i = 0; i != n; ++i) {
337 RegionSnapshot* region = snapshot_regions_[i].get();
338 if (not(region && region->contain(simgrid::mc::remote(addr))))
347 /** @brief Find the snapshoted region from a pointer, with a hinted_region */
348 RegionSnapshot* Snapshot::get_region(const void* addr, RegionSnapshot* hinted_region) const
350 if (hinted_region->contain(simgrid::mc::remote(addr)))
351 return hinted_region;
353 return get_region(addr);
356 void Snapshot::restore(RemoteClient* process)
358 XBT_DEBUG("Restore snapshot %i", num_state_);
361 for (std::unique_ptr<simgrid::mc::RegionSnapshot> const& region : snapshot_regions_) {
362 if (region) // privatized variables are not snapshoted
363 region.get()->restore();
366 snapshot_ignore_restore(this);
367 process->clear_cache();
371 } // namespace simgrid