Mercurial > hg > graal-compiler
diff src/os/bsd/vm/perfMemory_bsd.cpp @ 3960:f08d439fab8c
7089790: integrate bsd-port changes
Reviewed-by: kvn, twisti, jrose
Contributed-by: Kurt Miller <kurt@intricatesoftware.com>, Greg Lewis <glewis@eyesbeyond.com>, Jung-uk Kim <jkim@freebsd.org>, Christos Zoulas <christos@zoulas.com>, Landon Fuller <landonf@plausible.coop>, The FreeBSD Foundation <board@freebsdfoundation.org>, Michael Franz <mvfranz@gmail.com>, Roger Hoover <rhoover@apple.com>, Alexander Strange <astrange@apple.com>
author | never |
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date | Sun, 25 Sep 2011 16:03:29 -0700 |
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children | d2a62e0f25eb |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/os/bsd/vm/perfMemory_bsd.cpp Sun Sep 25 16:03:29 2011 -0700 @@ -0,0 +1,1041 @@ +/* + * 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_bsd.inline.hpp" +#include "runtime/handles.inline.hpp" +#include "runtime/perfMemory.hpp" +#include "utilities/exceptions.hpp" + +// put OS-includes here +# include <sys/types.h> +# include <sys/mman.h> +# include <errno.h> +# include <stdio.h> +# include <unistd.h> +# include <sys/stat.h> +# include <signal.h> +# include <pwd.h> + +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 bsd 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 bsd 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_<username> 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; + } + + // Verify that we have enough disk space for this file. + // We'll get random SIGBUS crashes on memory accesses if + // we don't. + + for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) { + int zero_int = 0; + result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos)); + if (result == -1 ) break; + RESTARTABLE(::write(fd, &zero_int, 1), result); + if (result != 1) { + if (errno == ENOSPC) { + warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename); + } + break; + } + } + + if (result != -1) { + return fd; + } else { + RESTARTABLE(::close(fd), result); + return -1; + } +} + +// 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 Bsd, 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 <address, size> +// 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 <address, size> 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 <address, size> 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 <address, size> 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; +}