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/internal_config.h"
25 #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_data_exe_start = nullptr;
33 int smpi_data_exe_size = 0;
34 int smpi_privatize_global_variables;
35 static char* smpi_data_exe_copy;
36 smpi_privatization_region_t smpi_privatization_regions;
37 // static std::set smpi_privatization_regions;
39 static const int PROT_RWX = (PROT_READ | PROT_WRITE | PROT_EXEC);
40 static const int PROT_RW = (PROT_READ | PROT_WRITE );
41 XBT_ATTRIB_UNUSED static const int PROT_RX = (PROT_READ | PROT_EXEC );
43 void smpi_get_executable_global_size()
45 char buffer[PATH_MAX];
46 char* full_name = realpath(xbt_binary_name, buffer);
47 if (full_name == nullptr)
48 xbt_die("Could not resolve binary file name");
50 std::vector<simgrid::xbt::VmMap> map = simgrid::xbt::get_memory_map(getpid());
51 for (auto i = map.begin(); i != map.end() ; ++i) {
52 // TODO, In practice, this implementation would not detect a completely
53 // anonymous data segment. This does not happen in practice, however.
55 // File backed RW entry:
56 if (i->pathname == full_name && (i->prot & PROT_RWX) == PROT_RW) {
57 smpi_data_exe_start = (char*)i->start_addr;
58 smpi_data_exe_size = i->end_addr - i->start_addr;
60 /* Here we are making the assumption that a suitable empty region
61 following the rw- area is the end of the data segment. It would
62 be better to check with the size of the data segment. */
63 if (i != map.end() && i->pathname.empty() && (i->prot & PROT_RWX) == PROT_RW &&
64 (char*)i->start_addr == smpi_data_exe_start + smpi_data_exe_size) {
65 smpi_data_exe_size = (char*)i->end_addr - smpi_data_exe_start;
70 xbt_die("Did not find my data segment.");
74 #if HAVE_SANITIZE_ADDRESS
75 #include <sanitizer/asan_interface.h>
76 static void* asan_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 asan_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_data_exe_size == 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 asan_safe_memcpy(smpi_data_exe_copy, TOPAGE(smpi_data_exe_start), smpi_data_exe_size);
120 // FIXME, cross-process support (mmap across process when necessary)
121 int current = smpi_privatization_regions[dest].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 void smpi_initialize_global_memory_segments()
140 #if HAVE_PRIVATIZATION
141 smpi_get_executable_global_size();
143 XBT_DEBUG("bss+data segment found : size %d starting at %p", smpi_data_exe_size, smpi_data_exe_start);
145 if (smpi_data_exe_size == 0) { // no need to switch
146 smpi_privatize_global_variables=false;
150 smpi_data_exe_copy = (char*)malloc(smpi_data_exe_size);
151 asan_safe_memcpy(smpi_data_exe_copy, TOPAGE(smpi_data_exe_start), smpi_data_exe_size);
152 smpi_privatization_regions = new s_smpi_privatization_region_t[smpi_process_count()];
154 for (int i=0; i< smpi_process_count(); i++){
155 // create SIMIX_process_count() mappings of this size with the same data inside
157 void* address = nullptr;
162 snprintf(path, sizeof(path), "/smpi-buffer-%06x", rand() % 0xffffffU);
163 file_descriptor = shm_open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
164 } while (file_descriptor == -1 && errno == EEXIST);
165 if (file_descriptor < 0) {
166 if (errno == EMFILE) {
167 xbt_die("Impossible to create temporary file for memory mapping: %s\n\
168 The open() system call failed with the EMFILE error code (too many files). \n\n\
169 This means that you reached the system limits concerning the amount of files per process. \
170 This is not a surprise if you are trying to virtualize many processes on top of SMPI. \
171 Don't panic -- you should simply increase your system limits and try again. \n\n\
172 First, check what your limits are:\n\
173 cat /proc/sys/fs/file-max # Gives you the system-wide limit\n\
174 ulimit -Hn # Gives you the per process hard limit\n\
175 ulimit -Sn # Gives you the per process soft limit\n\
176 cat /proc/self/limits # Displays any per-process limitation (including the one given above)\n\n\
177 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. \
178 Ask the Internet about tutorials on how to increase the files limit such as: https://rtcamp.com/tutorials/linux/increase-open-files-limit/",
181 xbt_die("Impossible to create temporary file for memory mapping: %s", strerror(errno));
184 status = ftruncate(file_descriptor, smpi_data_exe_size);
186 xbt_die("Impossible to set the size of the temporary file for memory mapping");
188 /* Ask for a free region */
189 address = mmap(nullptr, smpi_data_exe_size, PROT_READ | PROT_WRITE, MAP_SHARED, file_descriptor, 0);
190 if (address == MAP_FAILED)
191 xbt_die("Couldn't find a free region for memory mapping");
193 status = shm_unlink(path);
195 xbt_die("Impossible to unlink temporary file for memory mapping");
197 // initialize the values
198 asan_safe_memcpy(address, smpi_data_exe_copy, smpi_data_exe_size);
200 // store the address of the mapping for further switches
201 smpi_privatization_regions[i].file_descriptor = file_descriptor;
202 smpi_privatization_regions[i].address = address;
204 #else /* ! HAVE_PRIVATIZATION */
205 smpi_privatize_global_variables = false;
206 xbt_die("You are trying to use privatization on a system that does not support it. Don't.");
211 void smpi_destroy_global_memory_segments(){
212 if (smpi_data_exe_size == 0) // no need to switch
214 #if HAVE_PRIVATIZATION
215 for (int i=0; i< smpi_process_count(); i++) {
216 if (munmap(smpi_privatization_regions[i].address, smpi_data_exe_size) < 0)
217 XBT_WARN("Unmapping of fd %d failed: %s", smpi_privatization_regions[i].file_descriptor, strerror(errno));
218 close(smpi_privatization_regions[i].file_descriptor);
220 delete[] smpi_privatization_regions;