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"
28 #include "smpi_process.hpp"
30 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smpi_memory, smpi, "Memory layout support for SMPI");
32 int smpi_loaded_page = -1;
33 char* smpi_data_exe_start = nullptr;
34 int smpi_data_exe_size = 0;
35 int smpi_privatize_global_variables;
36 static char* smpi_data_exe_copy;
38 // We keep a copy of all the privatization regions: We can then delete everything easily by iterating over this
39 // collection and nothing can be leaked. We could also iterate over all actors but we would have to be diligent when two
40 // actors use the same privatization region (so, smart pointers would have to be used etc.)
41 static std::set<smpi_privatization_region_t> smpi_privatization_regions;
43 static const int PROT_RWX = (PROT_READ | PROT_WRITE | PROT_EXEC);
44 static const int PROT_RW = (PROT_READ | PROT_WRITE );
45 XBT_ATTRIB_UNUSED static const int PROT_RX = (PROT_READ | PROT_EXEC );
47 void smpi_get_executable_global_size()
49 char buffer[PATH_MAX];
50 char* full_name = realpath(xbt_binary_name, buffer);
51 if (full_name == nullptr)
52 xbt_die("Could not resolve binary file name");
54 std::vector<simgrid::xbt::VmMap> map = simgrid::xbt::get_memory_map(getpid());
55 for (auto i = map.begin(); i != map.end() ; ++i) {
56 // TODO, In practice, this implementation would not detect a completely
57 // anonymous data segment. This does not happen in practice, however.
59 // File backed RW entry:
60 if (i->pathname == full_name && (i->prot & PROT_RWX) == PROT_RW) {
61 smpi_data_exe_start = (char*)i->start_addr;
62 smpi_data_exe_size = i->end_addr - i->start_addr;
64 /* Here we are making the assumption that a suitable empty region
65 following the rw- area is the end of the data segment. It would
66 be better to check with the size of the data segment. */
67 if (i != map.end() && i->pathname.empty() && (i->prot & PROT_RWX) == PROT_RW &&
68 (char*)i->start_addr == smpi_data_exe_start + smpi_data_exe_size) {
69 smpi_data_exe_size = (char*)i->end_addr - smpi_data_exe_start;
74 xbt_die("Did not find my data segment.");
78 #if HAVE_SANITIZE_ADDRESS
79 #include <sanitizer/asan_interface.h>
80 static void* asan_safe_memcpy(void* dest, void* src, size_t n)
82 char* psrc = static_cast<char*>(src);
83 char* pdest = static_cast<char*>(dest);
84 for (size_t i = 0; i < n;) {
85 while (i < n && __asan_address_is_poisoned(psrc + i))
88 char* p = static_cast<char*>(__asan_region_is_poisoned(psrc + i, n - i));
89 size_t j = p ? (p - psrc) : n;
90 memcpy(pdest + i, psrc + i, j - i);
97 #define asan_safe_memcpy(dest, src, n) memcpy(dest, src, n)
100 /** Map a given SMPI privatization segment (make a SMPI process active) */
101 void smpi_switch_data_segment(int dest) {
102 if (smpi_loaded_page == dest)//no need to switch, we've already loaded the one we want
106 smpi_really_switch_data_segment(dest);
109 /** Map a given SMPI privatization segment (make a SMPI process active) even if SMPI thinks it is already active
111 * When doing a state restoration, the state of the restored variables might not be consistent with the state of the
112 * virtual memory. In this case, we to change the data segment.
114 void smpi_really_switch_data_segment(int dest)
116 if (smpi_data_exe_size == 0) // no need to switch
119 #if HAVE_PRIVATIZATION
120 // FIXME, cross-process support (mmap across process when necessary)
121 simgrid::smpi::Process* process = smpi_process_remote(dest);
122 int current = process->privatized_region()->file_descriptor;
123 XBT_DEBUG("Switching data frame to the one of process %d", dest);
125 mmap(TOPAGE(smpi_data_exe_start), smpi_data_exe_size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, current, 0);
126 if (tmp != TOPAGE(smpi_data_exe_start))
127 xbt_die("Couldn't map the new region (errno %d): %s", errno, strerror(errno));
128 smpi_loaded_page = dest;
132 int smpi_is_privatization_file(char* file)
134 const std::string buffer_path("/dev/shm/my-buffer-");
135 return buffer_path.compare(0, std::string::npos, file, buffer_path.length()) == 0;
138 // TODO: cheinrich: The behavior changed; this now only makes a backup of the
139 // data segment. I think the function should be renamed.
140 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_data_exe_size, smpi_data_exe_start);
147 if (smpi_data_exe_size == 0) { // no need to switch as global variables don't exist
148 smpi_privatize_global_variables=false;
152 smpi_data_exe_copy = (char*)malloc(smpi_data_exe_size);
153 // Make a copy of the data segment. This clean copy is retained over the whole runtime
154 // of the simulation and can be used to initialize a dynamically added, new process.
155 asan_safe_memcpy(smpi_data_exe_copy, TOPAGE(smpi_data_exe_start), smpi_data_exe_size);
156 #else /* ! HAVE_PRIVATIZATION */
157 smpi_privatize_global_variables = false;
158 xbt_die("You are trying to use privatization on a system that does not support it. Don't.");
163 // Initializes the memory mapping for a single process and returns the privatization region
164 smpi_privatization_region_t smpi_init_global_memory_segment_process()
167 void* address = nullptr;
172 snprintf(path, sizeof(path), "/smpi-buffer-%06x", rand() % 0xffffffU);
173 file_descriptor = shm_open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
174 } while (file_descriptor == -1 && errno == EEXIST);
175 if (file_descriptor < 0) {
176 if (errno == EMFILE) {
177 xbt_die("Impossible to create temporary file for memory mapping: %s\n\
178 The open() system call failed with the EMFILE error code (too many files). \n\n\
179 This means that you reached the system limits concerning the amount of files per process. \
180 This is not a surprise if you are trying to virtualize many processes on top of SMPI. \
181 Don't panic -- you should simply increase your system limits and try again. \n\n\
182 First, check what your limits are:\n\
183 cat /proc/sys/fs/file-max # Gives you the system-wide limit\n\
184 ulimit -Hn # Gives you the per process hard limit\n\
185 ulimit -Sn # Gives you the per process soft limit\n\
186 cat /proc/self/limits # Displays any per-process limitation (including the one given above)\n\n\
187 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. \
188 Ask the Internet about tutorials on how to increase the files limit such as: https://rtcamp.com/tutorials/linux/increase-open-files-limit/",
191 xbt_die("Impossible to create temporary file for memory mapping: %s", strerror(errno));
194 status = ftruncate(file_descriptor, smpi_data_exe_size);
196 xbt_die("Impossible to set the size of the temporary file for memory mapping");
198 /* Ask for a free region */
199 address = mmap(nullptr, smpi_data_exe_size, PROT_READ | PROT_WRITE, MAP_SHARED, file_descriptor, 0);
200 if (address == MAP_FAILED)
201 xbt_die("Couldn't find a free region for memory mapping");
203 status = shm_unlink(path);
205 xbt_die("Impossible to unlink temporary file for memory mapping");
207 // initialize the values
208 asan_safe_memcpy(address, smpi_data_exe_copy, smpi_data_exe_size);
210 // store the address of the mapping for further switches
211 smpi_privatization_region_t tmp =
212 static_cast<smpi_privatization_region_t>(xbt_malloc(sizeof(struct s_smpi_privatization_region)));
214 tmp->file_descriptor = file_descriptor;
215 tmp->address = address;
216 smpi_privatization_regions.insert(tmp);
221 void smpi_destroy_global_memory_segments(){
222 if (smpi_data_exe_size == 0) // no need to switch
224 #if HAVE_PRIVATIZATION
225 for (auto& it : smpi_privatization_regions) {
226 if (munmap(it->address, smpi_data_exe_size) < 0)
227 XBT_WARN("Unmapping of fd %d failed: %s", it->file_descriptor, strerror(errno));
228 close(it->file_descriptor);