1 /* Copyright (c) 2015-2017. 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. */
15 #include <sys/types.h>
22 #include "src/internal_config.h"
23 #include "src/xbt/memory_map.hpp"
25 #include "private.hpp"
26 #include "smpi_process.hpp"
28 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smpi_memory, smpi, "Memory layout support for SMPI");
30 int smpi_loaded_page = -1;
31 char* smpi_data_exe_start = nullptr;
32 int smpi_data_exe_size = 0;
33 int smpi_privatize_global_variables;
34 static void* smpi_data_exe_copy;
36 // We keep a copy of all the privatization regions: We can then delete everything easily by iterating over this
37 // collection and nothing can be leaked. We could also iterate over all actors but we would have to be diligent when two
38 // actors use the same privatization region (so, smart pointers would have to be used etc.)
39 // Use a std::deque so that pointers remain valid after push_back().
40 static std::deque<s_smpi_privatization_region_t> smpi_privatization_regions;
42 static const int PROT_RWX = (PROT_READ | PROT_WRITE | PROT_EXEC);
43 static const int PROT_RW = (PROT_READ | PROT_WRITE );
44 XBT_ATTRIB_UNUSED static const int PROT_RX = (PROT_READ | PROT_EXEC );
46 void smpi_get_executable_global_size()
48 char buffer[PATH_MAX];
49 char* full_name = realpath(xbt_binary_name, buffer);
50 if (full_name == nullptr)
51 xbt_die("Could not resolve binary file name");
53 std::vector<simgrid::xbt::VmMap> map = simgrid::xbt::get_memory_map(getpid());
54 for (auto i = map.begin(); i != map.end() ; ++i) {
55 // TODO, In practice, this implementation would not detect a completely
56 // anonymous data segment. This does not happen in practice, however.
58 // File backed RW entry:
59 if (i->pathname == full_name && (i->prot & PROT_RWX) == PROT_RW) {
60 smpi_data_exe_start = (char*)i->start_addr;
61 smpi_data_exe_size = i->end_addr - i->start_addr;
63 /* Here we are making the assumption that a suitable empty region
64 following the rw- area is the end of the data segment. It would
65 be better to check with the size of the data segment. */
66 if (i != map.end() && i->pathname.empty() && (i->prot & PROT_RWX) == PROT_RW &&
67 (char*)i->start_addr == smpi_data_exe_start + smpi_data_exe_size) {
68 smpi_data_exe_size = (char*)i->end_addr - smpi_data_exe_start;
73 xbt_die("Did not find my data segment.");
77 #if HAVE_SANITIZE_ADDRESS
78 #include <sanitizer/asan_interface.h>
79 static void* asan_safe_memcpy(void* dest, void* src, size_t n)
81 char* psrc = static_cast<char*>(src);
82 char* pdest = static_cast<char*>(dest);
83 for (size_t i = 0; i < n;) {
84 while (i < n && __asan_address_is_poisoned(psrc + i))
87 char* p = static_cast<char*>(__asan_region_is_poisoned(psrc + i, n - i));
88 size_t j = p ? (p - psrc) : n;
89 memcpy(pdest + i, psrc + i, j - i);
96 #define asan_safe_memcpy(dest, src, n) memcpy(dest, src, n)
99 /** Map a given SMPI privatization segment (make a SMPI process active) */
100 void smpi_switch_data_segment(int dest) {
101 if (smpi_loaded_page == dest)//no need to switch, we've already loaded the one we want
105 smpi_really_switch_data_segment(dest);
108 /** Map a given SMPI privatization segment (make a SMPI process active) even if SMPI thinks it is already active
110 * When doing a state restoration, the state of the restored variables might not be consistent with the state of the
111 * virtual memory. In this case, we to change the data segment.
113 void smpi_really_switch_data_segment(int dest)
115 if (smpi_data_exe_size == 0) // no need to switch
118 #if HAVE_PRIVATIZATION
119 // FIXME, cross-process support (mmap across process when necessary)
120 simgrid::smpi::Process* process = smpi_process_remote(dest);
121 int current = process->privatized_region()->file_descriptor;
122 XBT_DEBUG("Switching data frame to the one of process %d", dest);
124 mmap(TOPAGE(smpi_data_exe_start), smpi_data_exe_size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, current, 0);
125 if (tmp != TOPAGE(smpi_data_exe_start))
126 xbt_die("Couldn't map the new region (errno %d): %s", errno, strerror(errno));
127 smpi_loaded_page = dest;
131 int smpi_is_privatization_file(char* file)
133 const std::string buffer_path("/dev/shm/my-buffer-");
134 return buffer_path.compare(0, std::string::npos, file, buffer_path.length()) == 0;
137 // TODO: cheinrich: The behavior changed; this now only makes a backup of the
138 // data segment. I think the function should be renamed.
139 void smpi_backup_global_memory_segment()
141 #if HAVE_PRIVATIZATION
142 smpi_get_executable_global_size();
144 XBT_DEBUG("bss+data segment found : size %d starting at %p", smpi_data_exe_size, smpi_data_exe_start);
146 if (smpi_data_exe_size == 0) { // no need to do anything as global variables don't exist
147 smpi_privatize_global_variables=false;
151 smpi_data_exe_copy = ::operator new(smpi_data_exe_size);
152 // Make a copy of the data segment. This clean copy is retained over the whole runtime
153 // of the simulation and can be used to initialize a dynamically added, new process.
154 asan_safe_memcpy(smpi_data_exe_copy, TOPAGE(smpi_data_exe_start), smpi_data_exe_size);
155 #else /* ! HAVE_PRIVATIZATION */
156 smpi_privatize_global_variables = false;
157 xbt_die("You are trying to use privatization on a system that does not support it. Don't.");
162 // Initializes the memory mapping for a single process and returns the privatization region
163 smpi_privatization_region_t smpi_init_global_memory_segment_process()
166 void* address = nullptr;
171 snprintf(path, sizeof(path), "/smpi-buffer-%06x", rand() % 0xffffffU);
172 file_descriptor = shm_open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
173 } while (file_descriptor == -1 && errno == EEXIST);
174 if (file_descriptor < 0) {
175 if (errno == EMFILE) {
176 xbt_die("Impossible to create temporary file for memory mapping: %s\n\
177 The open() system call failed with the EMFILE error code (too many files). \n\n\
178 This means that you reached the system limits concerning the amount of files per process. \
179 This is not a surprise if you are trying to virtualize many processes on top of SMPI. \
180 Don't panic -- you should simply increase your system limits and try again. \n\n\
181 First, check what your limits are:\n\
182 cat /proc/sys/fs/file-max # Gives you the system-wide limit\n\
183 ulimit -Hn # Gives you the per process hard limit\n\
184 ulimit -Sn # Gives you the per process soft limit\n\
185 cat /proc/self/limits # Displays any per-process limitation (including the one given above)\n\n\
186 If one of these values is less than the amount of MPI processes that you try to run, then you got the explanation of this error. \
187 Ask the Internet about tutorials on how to increase the files limit such as: https://rtcamp.com/tutorials/linux/increase-open-files-limit/",
190 xbt_die("Impossible to create temporary file for memory mapping: %s", strerror(errno));
193 status = ftruncate(file_descriptor, smpi_data_exe_size);
195 xbt_die("Impossible to set the size of the temporary file for memory mapping");
197 /* Ask for a free region */
198 address = mmap(nullptr, smpi_data_exe_size, PROT_READ | PROT_WRITE, MAP_SHARED, file_descriptor, 0);
199 if (address == MAP_FAILED)
200 xbt_die("Couldn't find a free region for memory mapping");
202 status = shm_unlink(path);
204 xbt_die("Impossible to unlink temporary file for memory mapping");
206 // initialize the values
207 asan_safe_memcpy(address, smpi_data_exe_copy, smpi_data_exe_size);
209 // store the address of the mapping for further switches
210 smpi_privatization_regions.emplace_back(s_smpi_privatization_region_t{address, file_descriptor});
212 return &smpi_privatization_regions.back();
215 void smpi_destroy_global_memory_segments(){
216 if (smpi_data_exe_size == 0) // no need to switch
218 #if HAVE_PRIVATIZATION
219 for (auto const& region : smpi_privatization_regions) {
220 if (munmap(region.address, smpi_data_exe_size) < 0)
221 XBT_WARN("Unmapping of fd %d failed: %s", region.file_descriptor, strerror(errno));
222 close(region.file_descriptor);
224 smpi_privatization_regions.clear();
225 ::operator delete(smpi_data_exe_copy);