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. */
18 #include <sys/types.h>
24 #include "src/xbt/memory_map.hpp"
27 #include "private.hpp"
29 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smpi_memory, smpi, "Memory layout support for SMPI");
31 int smpi_loaded_page = -1;
32 char* smpi_start_data_exe = nullptr;
33 int smpi_size_data_exe = 0;
34 int smpi_privatize_global_variables;
36 static const int PROT_RWX = (PROT_READ | PROT_WRITE | PROT_EXEC);
37 static const int PROT_RW = (PROT_READ | PROT_WRITE );
38 XBT_ATTRIB_UNUSED static const int PROT_RX = (PROT_READ | PROT_EXEC );
40 void smpi_get_executable_global_size()
42 char buffer[PATH_MAX];
43 char* full_name = realpath(xbt_binary_name, buffer);
44 if (full_name == nullptr)
45 xbt_die("Could not resolve binary file name");
47 std::vector<simgrid::xbt::VmMap> map = simgrid::xbt::get_memory_map(getpid());
48 for (auto i = map.begin(); i != map.end() ; ++i) {
49 // TODO, In practice, this implementation would not detect a completely
50 // anonymous data segment. This does not happen in practice, however.
52 // File backed RW entry:
53 if (i->pathname == full_name && (i->prot & PROT_RWX) == PROT_RW) {
54 smpi_start_data_exe = (char*) i->start_addr;
55 smpi_size_data_exe = i->end_addr - i->start_addr;
57 /* Here we are making the assumption that a suitable empty region
58 following the rw- area is the end of the data segment. It would
59 be better to check with the size of the data segment. */
60 if (i != map.end() && i->pathname.empty() && (i->prot & PROT_RWX) == PROT_RW
61 && (char*)i->start_addr == smpi_start_data_exe + smpi_size_data_exe) {
62 smpi_size_data_exe = (char*)i->end_addr - smpi_start_data_exe;
67 xbt_die("Did not find my data segment.");
71 #if defined(__has_feature)
72 #define HAS_FEATURE(x) __has_feature(x)
74 #define HAS_FEATURE(x) 0
76 #if HAS_FEATURE(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
77 #include <sanitizer/asan_interface.h>
78 static void* safe_memcpy(void* dest, void* src, size_t n)
80 char* psrc = static_cast<char*>(src);
81 char* pdest = static_cast<char*>(dest);
82 for (size_t i = 0; i < n;) {
83 while (i < n && __asan_address_is_poisoned(psrc + i))
86 char* p = static_cast<char*>(__asan_region_is_poisoned(psrc + i, n - i));
87 size_t j = p ? (p - psrc) : n;
88 memcpy(pdest + i, psrc + i, j - i);
95 #define safe_memcpy(dest, src, n) memcpy(dest, src, n)
98 /** Map a given SMPI privatization segment (make a SMPI process active) */
99 void smpi_switch_data_segment(int dest) {
100 if (smpi_loaded_page == dest)//no need to switch, we've already loaded the one we want
104 smpi_really_switch_data_segment(dest);
107 /** Map a given SMPI privatization segment (make a SMPI process active) even if SMPI thinks it is already active
109 * When doing a state restoration, the state of the restored variables might not be consistent with the state of the
110 * virtual memory. In this case, we to change the data segment.
112 void smpi_really_switch_data_segment(int dest)
114 if(smpi_size_data_exe == 0)//no need to switch
117 #if HAVE_PRIVATIZATION
118 if(smpi_loaded_page==-1){//initial switch, do the copy from the real page here
119 for (int i=0; i< smpi_process_count(); i++){
120 safe_memcpy(smpi_privatization_regions[i].address, TOPAGE(smpi_start_data_exe), smpi_size_data_exe);
124 // FIXME, cross-process support (mmap across process when necessary)
125 int current = smpi_privatization_regions[dest].file_descriptor;
126 XBT_DEBUG("Switching data frame to the one of process %d", dest);
128 mmap(TOPAGE(smpi_start_data_exe), smpi_size_data_exe, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, current, 0);
129 if (tmp != TOPAGE(smpi_start_data_exe))
130 xbt_die("Couldn't map the new region (errno %d): %s", errno, strerror(errno));
131 smpi_loaded_page = dest;
135 int smpi_is_privatization_file(char* file)
137 const std::string buffer_path("/dev/shm/my-buffer-");
138 return buffer_path.compare(0, std::string::npos, file, buffer_path.length()) == 0;
141 void smpi_initialize_global_memory_segments()
144 #if HAVE_PRIVATIZATION
145 smpi_get_executable_global_size();
147 XBT_DEBUG ("bss+data segment found : size %d starting at %p", smpi_size_data_exe, smpi_start_data_exe );
149 if (smpi_size_data_exe == 0){//no need to switch
150 smpi_privatize_global_variables=false;
154 smpi_privatization_regions = static_cast<smpi_privatization_region_t>(
155 xbt_malloc(smpi_process_count() * sizeof(struct s_smpi_privatization_region)));
157 for (int i=0; i< smpi_process_count(); i++){
158 // create SIMIX_process_count() mappings of this size with the same data inside
160 void* address = nullptr;
165 snprintf(path, sizeof(path), "/smpi-buffer-%06x", rand() % 0xffffffU);
166 file_descriptor = shm_open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
167 } while (file_descriptor == -1 && errno == EEXIST);
168 if (file_descriptor < 0) {
169 if (errno == EMFILE) {
170 xbt_die("Impossible to create temporary file for memory mapping: %s\n\
171 The open() system call failed with the EMFILE error code (too many files). \n\n\
172 This means that you reached the system limits concerning the amount of files per process. \
173 This is not a surprise if you are trying to virtualize many processes on top of SMPI. \
174 Don't panic -- you should simply increase your system limits and try again. \n\n\
175 First, check what your limits are:\n\
176 cat /proc/sys/fs/file-max # Gives you the system-wide limit\n\
177 ulimit -Hn # Gives you the per process hard limit\n\
178 ulimit -Sn # Gives you the per process soft limit\n\
179 cat /proc/self/limits # Displays any per-process limitation (including the one given above)\n\n\
180 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. \
181 Ask the Internet about tutorials on how to increase the files limit such as: https://rtcamp.com/tutorials/linux/increase-open-files-limit/",
184 xbt_die("Impossible to create temporary file for memory mapping: %s", strerror(errno));
187 status = ftruncate(file_descriptor, smpi_size_data_exe);
189 xbt_die("Impossible to set the size of the temporary file for memory mapping");
191 /* Ask for a free region */
192 address = mmap(nullptr, smpi_size_data_exe, PROT_READ | PROT_WRITE, MAP_SHARED, file_descriptor, 0);
193 if (address == MAP_FAILED)
194 xbt_die("Couldn't find a free region for memory mapping");
196 status = shm_unlink(path);
198 xbt_die("Impossible to unlink temporary file for memory mapping");
200 // initialize the values
201 safe_memcpy(address, TOPAGE(smpi_start_data_exe), smpi_size_data_exe);
203 // store the address of the mapping for further switches
204 smpi_privatization_regions[i].file_descriptor = file_descriptor;
205 smpi_privatization_regions[i].address = address;
207 #else /* ! HAVE_PRIVATIZATION */
208 smpi_privatize_global_variables = false;
209 xbt_die("You are trying to use privatization on a system that does not support it. Don't.");
214 void smpi_destroy_global_memory_segments(){
215 if (smpi_size_data_exe == 0)//no need to switch
217 #if HAVE_PRIVATIZATION
218 for (int i=0; i< smpi_process_count(); i++) {
219 if (munmap(smpi_privatization_regions[i].address, smpi_size_data_exe) < 0)
220 XBT_WARN("Unmapping of fd %d failed: %s", smpi_privatization_regions[i].file_descriptor, strerror(errno));
221 close(smpi_privatization_regions[i].file_descriptor);
223 xbt_free(smpi_privatization_regions);