/*
* Copyright 2001-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_perfMemory_linux.cpp.incl"
// 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 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) + 2;
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 occured.
//
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) + 1);
strcpy(usrdir_name, tmpdirname);
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 <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;
}