/* * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "classfile/vmSymbols.hpp" #include "memory/allocation.inline.hpp" #include "memory/resourceArea.hpp" #include "oops/oop.inline.hpp" #include "os_linux.inline.hpp" #include "runtime/handles.inline.hpp" #include "runtime/perfMemory.hpp" #include "utilities/exceptions.hpp" // put OS-includes here # include # include # include # include # include # include # include # include static char* backing_store_file_name = NULL; // name of the backing store // file, if successfully created. // Standard Memory Implementation Details // create the PerfData memory region in standard memory. // static char* create_standard_memory(size_t size) { // allocate an aligned chuck of memory char* mapAddress = os::reserve_memory(size); if (mapAddress == NULL) { return NULL; } // commit memory if (!os::commit_memory(mapAddress, size)) { if (PrintMiscellaneous && Verbose) { warning("Could not commit PerfData memory\n"); } os::release_memory(mapAddress, size); return NULL; } return mapAddress; } // delete the PerfData memory region // static void delete_standard_memory(char* addr, size_t size) { // there are no persistent external resources to cleanup for standard // memory. since DestroyJavaVM does not support unloading of the JVM, // cleanup of the memory resource is not performed. The memory will be // reclaimed by the OS upon termination of the process. // return; } // save the specified memory region to the given file // // Note: this function might be called from signal handler (by os::abort()), // don't allocate heap memory. // static void save_memory_to_file(char* addr, size_t size) { const char* destfile = PerfMemory::get_perfdata_file_path(); assert(destfile[0] != '\0', "invalid PerfData file path"); int result; RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), result);; if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("Could not create Perfdata save file: %s: %s\n", destfile, strerror(errno)); } } else { int fd = result; for (size_t remaining = size; remaining > 0;) { RESTARTABLE(::write(fd, addr, remaining), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("Could not write Perfdata save file: %s: %s\n", destfile, strerror(errno)); } break; } remaining -= (size_t)result; addr += result; } RESTARTABLE(::close(fd), result); if (PrintMiscellaneous && Verbose) { if (result == OS_ERR) { warning("Could not close %s: %s\n", destfile, strerror(errno)); } } } FREE_C_HEAP_ARRAY(char, destfile); } // Shared Memory Implementation Details // Note: the solaris and linux shared memory implementation uses the mmap // interface with a backing store file to implement named shared memory. // Using the file system as the name space for shared memory allows a // common name space to be supported across a variety of platforms. It // also provides a name space that Java applications can deal with through // simple file apis. // // The solaris and linux implementations store the backing store file in // a user specific temporary directory located in the /tmp file system, // which is always a local file system and is sometimes a RAM based file // system. // return the user specific temporary directory name. // // the caller is expected to free the allocated memory. // static char* get_user_tmp_dir(const char* user) { const char* tmpdir = os::get_temp_directory(); const char* perfdir = PERFDATA_NAME; size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; char* dirname = NEW_C_HEAP_ARRAY(char, nbytes); // construct the path name to user specific tmp directory snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); return dirname; } // convert the given file name into a process id. if the file // does not meet the file naming constraints, return 0. // static pid_t filename_to_pid(const char* filename) { // a filename that doesn't begin with a digit is not a // candidate for conversion. // if (!isdigit(*filename)) { return 0; } // check if file name can be converted to an integer without // any leftover characters. // char* remainder = NULL; errno = 0; pid_t pid = (pid_t)strtol(filename, &remainder, 10); if (errno != 0) { return 0; } // check for left over characters. If any, then the filename is // not a candidate for conversion. // if (remainder != NULL && *remainder != '\0') { return 0; } // successful conversion, return the pid return pid; } // check if the given path is considered a secure directory for // the backing store files. Returns true if the directory exists // and is considered a secure location. Returns false if the path // is a symbolic link or if an error occurred. // static bool is_directory_secure(const char* path) { struct stat statbuf; int result = 0; RESTARTABLE(::lstat(path, &statbuf), result); if (result == OS_ERR) { return false; } // the path exists, now check it's mode if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { // the path represents a link or some non-directory file type, // which is not what we expected. declare it insecure. // return false; } else { // we have an existing directory, check if the permissions are safe. // if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) { // the directory is open for writing and could be subjected // to a symlnk attack. declare it insecure. // return false; } } return true; } // return the user name for the given user id // // the caller is expected to free the allocated memory. // static char* get_user_name(uid_t uid) { struct passwd pwent; // determine the max pwbuf size from sysconf, and hardcode // a default if this not available through sysconf. // long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); if (bufsize == -1) bufsize = 1024; char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize); // POSIX interface to getpwuid_r is used on LINUX struct passwd* p; int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { if (PrintMiscellaneous && Verbose) { if (result != 0) { warning("Could not retrieve passwd entry: %s\n", strerror(result)); } else if (p == NULL) { // this check is added to protect against an observed problem // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, // indicating success, but has p == NULL. This was observed when // inserting a file descriptor exhaustion fault prior to the call // getpwuid_r() call. In this case, error is set to the appropriate // error condition, but this is undocumented behavior. This check // is safe under any condition, but the use of errno in the output // message may result in an erroneous message. // Bug Id 89052 was opened with RedHat. // warning("Could not retrieve passwd entry: %s\n", strerror(errno)); } else { warning("Could not determine user name: %s\n", p->pw_name == NULL ? "pw_name = NULL" : "pw_name zero length"); } } FREE_C_HEAP_ARRAY(char, pwbuf); return NULL; } char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1); strcpy(user_name, p->pw_name); FREE_C_HEAP_ARRAY(char, pwbuf); return user_name; } // return the name of the user that owns the process identified by vmid. // // This method uses a slow directory search algorithm to find the backing // store file for the specified vmid and returns the user name, as determined // by the user name suffix of the hsperfdata_ directory name. // // the caller is expected to free the allocated memory. // static char* get_user_name_slow(int vmid, TRAPS) { // short circuit the directory search if the process doesn't even exist. if (kill(vmid, 0) == OS_ERR) { if (errno == ESRCH) { THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Process not found"); } else /* EPERM */ { THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); } } // directory search char* oldest_user = NULL; time_t oldest_ctime = 0; const char* tmpdirname = os::get_temp_directory(); DIR* tmpdirp = os::opendir(tmpdirname); if (tmpdirp == NULL) { return NULL; } // for each entry in the directory that matches the pattern hsperfdata_*, // open the directory and check if the file for the given vmid exists. // The file with the expected name and the latest creation date is used // to determine the user name for the process id. // struct dirent* dentry; char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname)); errno = 0; while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { // check if the directory entry is a hsperfdata file if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { continue; } char* usrdir_name = NEW_C_HEAP_ARRAY(char, strlen(tmpdirname) + strlen(dentry->d_name) + 2); strcpy(usrdir_name, tmpdirname); strcat(usrdir_name, "/"); strcat(usrdir_name, dentry->d_name); DIR* subdirp = os::opendir(usrdir_name); if (subdirp == NULL) { FREE_C_HEAP_ARRAY(char, usrdir_name); continue; } // Since we don't create the backing store files in directories // pointed to by symbolic links, we also don't follow them when // looking for the files. We check for a symbolic link after the // call to opendir in order to eliminate a small window where the // symlink can be exploited. // if (!is_directory_secure(usrdir_name)) { FREE_C_HEAP_ARRAY(char, usrdir_name); os::closedir(subdirp); continue; } struct dirent* udentry; char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name)); errno = 0; while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { if (filename_to_pid(udentry->d_name) == vmid) { struct stat statbuf; int result; char* filename = NEW_C_HEAP_ARRAY(char, strlen(usrdir_name) + strlen(udentry->d_name) + 2); strcpy(filename, usrdir_name); strcat(filename, "/"); strcat(filename, udentry->d_name); // don't follow symbolic links for the file RESTARTABLE(::lstat(filename, &statbuf), result); if (result == OS_ERR) { FREE_C_HEAP_ARRAY(char, filename); continue; } // skip over files that are not regular files. if (!S_ISREG(statbuf.st_mode)) { FREE_C_HEAP_ARRAY(char, filename); continue; } // compare and save filename with latest creation time if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { if (statbuf.st_ctime > oldest_ctime) { char* user = strchr(dentry->d_name, '_') + 1; if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1); strcpy(oldest_user, user); oldest_ctime = statbuf.st_ctime; } } FREE_C_HEAP_ARRAY(char, filename); } } os::closedir(subdirp); FREE_C_HEAP_ARRAY(char, udbuf); FREE_C_HEAP_ARRAY(char, usrdir_name); } os::closedir(tmpdirp); FREE_C_HEAP_ARRAY(char, tdbuf); return(oldest_user); } // return the name of the user that owns the JVM indicated by the given vmid. // static char* get_user_name(int vmid, TRAPS) { return get_user_name_slow(vmid, CHECK_NULL); } // return the file name of the backing store file for the named // shared memory region for the given user name and vmid. // // the caller is expected to free the allocated memory. // static char* get_sharedmem_filename(const char* dirname, int vmid) { // add 2 for the file separator and a null terminator. size_t nbytes = strlen(dirname) + UINT_CHARS + 2; char* name = NEW_C_HEAP_ARRAY(char, nbytes); snprintf(name, nbytes, "%s/%d", dirname, vmid); return name; } // remove file // // this method removes the file specified by the given path // static void remove_file(const char* path) { int result; // if the file is a directory, the following unlink will fail. since // we don't expect to find directories in the user temp directory, we // won't try to handle this situation. even if accidentially or // maliciously planted, the directory's presence won't hurt anything. // RESTARTABLE(::unlink(path), result); if (PrintMiscellaneous && Verbose && result == OS_ERR) { if (errno != ENOENT) { warning("Could not unlink shared memory backing" " store file %s : %s\n", path, strerror(errno)); } } } // remove file // // this method removes the file with the given file name in the // named directory. // static void remove_file(const char* dirname, const char* filename) { size_t nbytes = strlen(dirname) + strlen(filename) + 2; char* path = NEW_C_HEAP_ARRAY(char, nbytes); strcpy(path, dirname); strcat(path, "/"); strcat(path, filename); remove_file(path); FREE_C_HEAP_ARRAY(char, path); } // cleanup stale shared memory resources // // This method attempts to remove all stale shared memory files in // the named user temporary directory. It scans the named directory // for files matching the pattern ^$[0-9]*$. For each file found, the // process id is extracted from the file name and a test is run to // determine if the process is alive. If the process is not alive, // any stale file resources are removed. // static void cleanup_sharedmem_resources(const char* dirname) { // open the user temp directory DIR* dirp = os::opendir(dirname); if (dirp == NULL) { // directory doesn't exist, so there is nothing to cleanup return; } if (!is_directory_secure(dirname)) { // the directory is not a secure directory return; } // for each entry in the directory that matches the expected file // name pattern, determine if the file resources are stale and if // so, remove the file resources. Note, instrumented HotSpot processes // for this user may start and/or terminate during this search and // remove or create new files in this directory. The behavior of this // loop under these conditions is dependent upon the implementation of // opendir/readdir. // struct dirent* entry; char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname)); errno = 0; while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { pid_t pid = filename_to_pid(entry->d_name); if (pid == 0) { if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { // attempt to remove all unexpected files, except "." and ".." remove_file(dirname, entry->d_name); } errno = 0; continue; } // we now have a file name that converts to a valid integer // that could represent a process id . if this process id // matches the current process id or the process is not running, // then remove the stale file resources. // // process liveness is detected by sending signal number 0 to // the process id (see kill(2)). if kill determines that the // process does not exist, then the file resources are removed. // if kill determines that that we don't have permission to // signal the process, then the file resources are assumed to // be stale and are removed because the resources for such a // process should be in a different user specific directory. // if ((pid == os::current_process_id()) || (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { remove_file(dirname, entry->d_name); } errno = 0; } os::closedir(dirp); FREE_C_HEAP_ARRAY(char, dbuf); } // make the user specific temporary directory. Returns true if // the directory exists and is secure upon return. Returns false // if the directory exists but is either a symlink, is otherwise // insecure, or if an error occurred. // static bool make_user_tmp_dir(const char* dirname) { // create the directory with 0755 permissions. note that the directory // will be owned by euid::egid, which may not be the same as uid::gid. // if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { if (errno == EEXIST) { // The directory already exists and was probably created by another // JVM instance. However, this could also be the result of a // deliberate symlink. Verify that the existing directory is safe. // if (!is_directory_secure(dirname)) { // directory is not secure if (PrintMiscellaneous && Verbose) { warning("%s directory is insecure\n", dirname); } return false; } } else { // we encountered some other failure while attempting // to create the directory // if (PrintMiscellaneous && Verbose) { warning("could not create directory %s: %s\n", dirname, strerror(errno)); } return false; } } return true; } // create the shared memory file resources // // This method creates the shared memory file with the given size // This method also creates the user specific temporary directory, if // it does not yet exist. // static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { // make the user temporary directory if (!make_user_tmp_dir(dirname)) { // could not make/find the directory or the found directory // was not secure return -1; } int result; RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("could not create file %s: %s\n", filename, strerror(errno)); } return -1; } // save the file descriptor int fd = result; // set the file size RESTARTABLE(::ftruncate(fd, (off_t)size), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("could not set shared memory file size: %s\n", strerror(errno)); } RESTARTABLE(::close(fd), result); return -1; } return fd; } // open the shared memory file for the given user and vmid. returns // the file descriptor for the open file or -1 if the file could not // be opened. // static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { // open the file int result; RESTARTABLE(::open(filename, oflags), result); if (result == OS_ERR) { if (errno == ENOENT) { THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Process not found"); } else if (errno == EACCES) { THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Permission denied"); } else { THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); } } return result; } // create a named shared memory region. returns the address of the // memory region on success or NULL on failure. A return value of // NULL will ultimately disable the shared memory feature. // // On Solaris and Linux, the name space for shared memory objects // is the file system name space. // // A monitoring application attaching to a JVM does not need to know // the file system name of the shared memory object. However, it may // be convenient for applications to discover the existence of newly // created and terminating JVMs by watching the file system name space // for files being created or removed. // static char* mmap_create_shared(size_t size) { int result; int fd; char* mapAddress; int vmid = os::current_process_id(); char* user_name = get_user_name(geteuid()); if (user_name == NULL) return NULL; char* dirname = get_user_tmp_dir(user_name); char* filename = get_sharedmem_filename(dirname, vmid); // cleanup any stale shared memory files cleanup_sharedmem_resources(dirname); assert(((size > 0) && (size % os::vm_page_size() == 0)), "unexpected PerfMemory region size"); fd = create_sharedmem_resources(dirname, filename, size); FREE_C_HEAP_ARRAY(char, user_name); FREE_C_HEAP_ARRAY(char, dirname); if (fd == -1) { FREE_C_HEAP_ARRAY(char, filename); return NULL; } mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); // attempt to close the file - restart it if it was interrupted, // but ignore other failures RESTARTABLE(::close(fd), result); assert(result != OS_ERR, "could not close file"); if (mapAddress == MAP_FAILED) { if (PrintMiscellaneous && Verbose) { warning("mmap failed - %s\n", strerror(errno)); } remove_file(filename); FREE_C_HEAP_ARRAY(char, filename); return NULL; } // save the file name for use in delete_shared_memory() backing_store_file_name = filename; // clear the shared memory region (void)::memset((void*) mapAddress, 0, size); return mapAddress; } // release a named shared memory region // static void unmap_shared(char* addr, size_t bytes) { os::release_memory(addr, bytes); } // create the PerfData memory region in shared memory. // static char* create_shared_memory(size_t size) { // create the shared memory region. return mmap_create_shared(size); } // delete the shared PerfData memory region // static void delete_shared_memory(char* addr, size_t size) { // cleanup the persistent shared memory resources. since DestroyJavaVM does // not support unloading of the JVM, unmapping of the memory resource is // not performed. The memory will be reclaimed by the OS upon termination of // the process. The backing store file is deleted from the file system. assert(!PerfDisableSharedMem, "shouldn't be here"); if (backing_store_file_name != NULL) { remove_file(backing_store_file_name); // Don't.. Free heap memory could deadlock os::abort() if it is called // from signal handler. OS will reclaim the heap memory. // FREE_C_HEAP_ARRAY(char, backing_store_file_name); backing_store_file_name = NULL; } } // return the size of the file for the given file descriptor // or 0 if it is not a valid size for a shared memory file // static size_t sharedmem_filesize(int fd, TRAPS) { struct stat statbuf; int result; RESTARTABLE(::fstat(fd, &statbuf), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("fstat failed: %s\n", strerror(errno)); } THROW_MSG_0(vmSymbols::java_io_IOException(), "Could not determine PerfMemory size"); } if ((statbuf.st_size == 0) || ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { THROW_MSG_0(vmSymbols::java_lang_Exception(), "Invalid PerfMemory size"); } return (size_t)statbuf.st_size; } // attach to a named shared memory region. // static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { char* mapAddress; int result; int fd; size_t size; const char* luser = NULL; int mmap_prot; int file_flags; ResourceMark rm; // map the high level access mode to the appropriate permission // constructs for the file and the shared memory mapping. if (mode == PerfMemory::PERF_MODE_RO) { mmap_prot = PROT_READ; file_flags = O_RDONLY; } else if (mode == PerfMemory::PERF_MODE_RW) { #ifdef LATER mmap_prot = PROT_READ | PROT_WRITE; file_flags = O_RDWR; #else THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Unsupported access mode"); #endif } else { THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Illegal access mode"); } if (user == NULL || strlen(user) == 0) { luser = get_user_name(vmid, CHECK); } else { luser = user; } if (luser == NULL) { THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Could not map vmid to user Name"); } char* dirname = get_user_tmp_dir(luser); // since we don't follow symbolic links when creating the backing // store file, we don't follow them when attaching either. // if (!is_directory_secure(dirname)) { FREE_C_HEAP_ARRAY(char, dirname); THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Process not found"); } char* filename = get_sharedmem_filename(dirname, vmid); // copy heap memory to resource memory. the open_sharedmem_file // method below need to use the filename, but could throw an // exception. using a resource array prevents the leak that // would otherwise occur. char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); strcpy(rfilename, filename); // free the c heap resources that are no longer needed if (luser != user) FREE_C_HEAP_ARRAY(char, luser); FREE_C_HEAP_ARRAY(char, dirname); FREE_C_HEAP_ARRAY(char, filename); // open the shared memory file for the give vmid fd = open_sharedmem_file(rfilename, file_flags, CHECK); assert(fd != OS_ERR, "unexpected value"); if (*sizep == 0) { size = sharedmem_filesize(fd, CHECK); assert(size != 0, "unexpected size"); } mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); // attempt to close the file - restart if it gets interrupted, // but ignore other failures RESTARTABLE(::close(fd), result); assert(result != OS_ERR, "could not close file"); if (mapAddress == MAP_FAILED) { if (PrintMiscellaneous && Verbose) { warning("mmap failed: %s\n", strerror(errno)); } THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), "Could not map PerfMemory"); } *addr = mapAddress; *sizep = size; if (PerfTraceMemOps) { tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); } } // create the PerfData memory region // // This method creates the memory region used to store performance // data for the JVM. The memory may be created in standard or // shared memory. // void PerfMemory::create_memory_region(size_t size) { if (PerfDisableSharedMem) { // do not share the memory for the performance data. _start = create_standard_memory(size); } else { _start = create_shared_memory(size); if (_start == NULL) { // creation of the shared memory region failed, attempt // to create a contiguous, non-shared memory region instead. // if (PrintMiscellaneous && Verbose) { warning("Reverting to non-shared PerfMemory region.\n"); } PerfDisableSharedMem = true; _start = create_standard_memory(size); } } if (_start != NULL) _capacity = size; } // delete the PerfData memory region // // This method deletes the memory region used to store performance // data for the JVM. The memory region indicated by the // tuple will be inaccessible after a call to this method. // void PerfMemory::delete_memory_region() { assert((start() != NULL && capacity() > 0), "verify proper state"); // If user specifies PerfDataSaveFile, it will save the performance data // to the specified file name no matter whether PerfDataSaveToFile is specified // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag // -XX:+PerfDataSaveToFile. if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { save_memory_to_file(start(), capacity()); } if (PerfDisableSharedMem) { delete_standard_memory(start(), capacity()); } else { delete_shared_memory(start(), capacity()); } } // attach to the PerfData memory region for another JVM // // This method returns an tuple that points to // a memory buffer that is kept reasonably synchronized with // the PerfData memory region for the indicated JVM. This // buffer may be kept in synchronization via shared memory // or some other mechanism that keeps the buffer updated. // // If the JVM chooses not to support the attachability feature, // this method should throw an UnsupportedOperation exception. // // This implementation utilizes named shared memory to map // the indicated process's PerfData memory region into this JVMs // address space. // void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { if (vmid == 0 || vmid == os::current_process_id()) { *addrp = start(); *sizep = capacity(); return; } mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); } // detach from the PerfData memory region of another JVM // // This method detaches the PerfData memory region of another // JVM, specified as an tuple of a buffer // in this process's address space. This method may perform // arbitrary actions to accomplish the detachment. The memory // region specified by will be inaccessible after // a call to this method. // // If the JVM chooses not to support the attachability feature, // this method should throw an UnsupportedOperation exception. // // This implementation utilizes named shared memory to detach // the indicated process's PerfData memory region from this // process's address space. // void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { assert(addr != 0, "address sanity check"); assert(bytes > 0, "capacity sanity check"); if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { // prevent accidental detachment of this process's PerfMemory region return; } unmap_shared(addr, bytes); } char* PerfMemory::backing_store_filename() { return backing_store_file_name; }