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) 0
74 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
75 #include <sanitizer/asan_interface.h>
76 void* safe_memcpy(void* dest, void* src, size_t n)
78 char* psrc = static_cast<char*>(src);
79 char* pdest = static_cast<char*>(dest);
80 for (size_t i = 0; i < n;) {
81 while (i < n && __asan_address_is_poisoned(psrc + i))
84 char* p = static_cast<char*>(__asan_region_is_poisoned(psrc + i, n - i));
85 size_t j = p ? (p - psrc) : n;
86 memcpy(pdest + i, psrc + i, j - i);
93 #define safe_memcpy(dest, src, n) memcpy(dest, src, n)
96 /** Map a given SMPI privatization segment (make a SMPI process active) */
97 void smpi_switch_data_segment(int dest) {
98 if (smpi_loaded_page == dest)//no need to switch, we've already loaded the one we want
102 smpi_really_switch_data_segment(dest);
105 /** Map a given SMPI privatization segment (make a SMPI process active) even if SMPI thinks it is already active
107 * When doing a state restoration, the state of the restored variables might not be consistent with the state of the
108 * virtual memory. In this case, we to change the data segment.
110 void smpi_really_switch_data_segment(int dest)
112 if(smpi_size_data_exe == 0)//no need to switch
115 #if HAVE_PRIVATIZATION
116 if(smpi_loaded_page==-1){//initial switch, do the copy from the real page here
117 for (int i=0; i< smpi_process_count(); i++){
118 safe_memcpy(smpi_privatization_regions[i].address, TOPAGE(smpi_start_data_exe), smpi_size_data_exe);
122 // FIXME, cross-process support (mmap across process when necessary)
123 int current = smpi_privatization_regions[dest].file_descriptor;
124 XBT_DEBUG("Switching data frame to the one of process %d", dest);
126 mmap(TOPAGE(smpi_start_data_exe), smpi_size_data_exe, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, current, 0);
127 if (tmp != TOPAGE(smpi_start_data_exe))
128 xbt_die("Couldn't map the new region (errno %d): %s", errno, strerror(errno));
129 smpi_loaded_page = dest;
133 int smpi_is_privatization_file(char* file)
135 const std::string buffer_path("/dev/shm/my-buffer-");
136 return buffer_path.compare(0, std::string::npos, file, buffer_path.length()) == 0;
139 void smpi_initialize_global_memory_segments()
142 #if HAVE_PRIVATIZATION
143 smpi_get_executable_global_size();
145 XBT_DEBUG ("bss+data segment found : size %d starting at %p", smpi_size_data_exe, smpi_start_data_exe );
147 if (smpi_size_data_exe == 0){//no need to switch
148 smpi_privatize_global_variables=false;
152 smpi_privatization_regions = static_cast<smpi_privatization_region_t>(
153 xbt_malloc(smpi_process_count() * sizeof(struct s_smpi_privatization_region)));
155 for (int i=0; i< smpi_process_count(); i++){
156 // create SIMIX_process_count() mappings of this size with the same data inside
158 void* address = nullptr;
163 snprintf(path, sizeof(path), "/smpi-buffer-%06x", rand() % 0xffffffU);
164 file_descriptor = shm_open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
165 } while (file_descriptor == -1 && errno == EEXIST);
166 if (file_descriptor < 0) {
167 if (errno == EMFILE) {
168 xbt_die("Impossible to create temporary file for memory mapping: %s\n\
169 The open() system call failed with the EMFILE error code (too many files). \n\n\
170 This means that you reached the system limits concerning the amount of files per process. \
171 This is not a surprise if you are trying to virtualize many processes on top of SMPI. \
172 Don't panic -- you should simply increase your system limits and try again. \n\n\
173 First, check what your limits are:\n\
174 cat /proc/sys/fs/file-max # Gives you the system-wide limit\n\
175 ulimit -Hn # Gives you the per process hard limit\n\
176 ulimit -Sn # Gives you the per process soft limit\n\
177 cat /proc/self/limits # Displays any per-process limitation (including the one given above)\n\n\
178 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. \
179 Ask the Internet about tutorials on how to increase the files limit such as: https://rtcamp.com/tutorials/linux/increase-open-files-limit/",
182 xbt_die("Impossible to create temporary file for memory mapping: %s", strerror(errno));
185 status = ftruncate(file_descriptor, smpi_size_data_exe);
187 xbt_die("Impossible to set the size of the temporary file for memory mapping");
189 /* Ask for a free region */
190 address = mmap(nullptr, smpi_size_data_exe, PROT_READ | PROT_WRITE, MAP_SHARED, file_descriptor, 0);
191 if (address == MAP_FAILED)
192 xbt_die("Couldn't find a free region for memory mapping");
194 status = shm_unlink(path);
196 xbt_die("Impossible to unlink temporary file for memory mapping");
198 // initialize the values
199 safe_memcpy(address, TOPAGE(smpi_start_data_exe), smpi_size_data_exe);
201 // store the address of the mapping for further switches
202 smpi_privatization_regions[i].file_descriptor = file_descriptor;
203 smpi_privatization_regions[i].address = address;
205 #else /* ! HAVE_PRIVATIZATION */
206 smpi_privatize_global_variables = false;
207 xbt_die("You are trying to use privatization on a system that does not support it. Don't.");
212 void smpi_destroy_global_memory_segments(){
213 if (smpi_size_data_exe == 0)//no need to switch
215 #if HAVE_PRIVATIZATION
216 for (int i=0; i< smpi_process_count(); i++) {
217 if (munmap(smpi_privatization_regions[i].address, smpi_size_data_exe) < 0)
218 XBT_WARN("Unmapping of fd %d failed: %s", smpi_privatization_regions[i].file_descriptor, strerror(errno));
219 close(smpi_privatization_regions[i].file_descriptor);
221 xbt_free(smpi_privatization_regions);