/* * Copyright (c) 1999, 2025, 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 "classfile/classLoader.hpp" #include "interpreter/interpreter.hpp" #include "jvm.h" #include "jvmtifiles/jvmti.h" #include "logging/log.hpp" #include "memory/allocation.inline.hpp" #include "nmt/memTracker.hpp" #include "os_posix.inline.hpp" #include "runtime/arguments.hpp" #include "runtime/atomic.hpp" #include "runtime/frame.inline.hpp" #include "runtime/globals_extension.hpp" #include "runtime/interfaceSupport.inline.hpp" #include "runtime/java.hpp" #include "runtime/orderAccess.hpp" #include "runtime/osThread.hpp" #include "runtime/park.hpp" #include "runtime/perfMemory.hpp" #include "runtime/sharedRuntime.hpp" #include "services/attachListener.hpp" #include "utilities/align.hpp" #include "utilities/checkedCast.hpp" #include "utilities/debug.hpp" #include "utilities/defaultStream.hpp" #include "utilities/events.hpp" #include "utilities/formatBuffer.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/macros.hpp" #include "utilities/permitForbiddenFunctions.hpp" #include "utilities/vmError.hpp" #if INCLUDE_JFR #include "jfr/support/jfrNativeLibraryLoadEvent.hpp" #endif #ifdef AIX #include "loadlib_aix.hpp" #include "os_aix.hpp" #include "porting_aix.hpp" #endif #ifdef LINUX #include "os_linux.hpp" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef __APPLE__ #include #endif #define ROOT_UID 0 #ifndef MAP_ANONYMOUS #define MAP_ANONYMOUS MAP_ANON #endif /* Input/Output types for mincore(2) */ typedef LINUX_ONLY(unsigned) char mincore_vec_t; static jlong initial_time_count = 0; static int clock_tics_per_sec = 100; // Platform minimum stack allowed size_t os::_os_min_stack_allowed = PTHREAD_STACK_MIN; // Check core dump limit and report possible place where core can be found void os::check_core_dump_prerequisites(char* buffer, size_t bufferSize, bool check_only) { if (!FLAG_IS_DEFAULT(CreateCoredumpOnCrash) && !CreateCoredumpOnCrash) { jio_snprintf(buffer, bufferSize, "CreateCoredumpOnCrash is disabled from command line"); VMError::record_coredump_status(buffer, false); } else { struct rlimit rlim; bool success = true; bool warn = true; char core_path[PATH_MAX]; if (get_core_path(core_path, PATH_MAX) <= 0) { jio_snprintf(buffer, bufferSize, "core.%d (may not exist)", current_process_id()); #ifdef LINUX } else if (core_path[0] == '"') { // redirect to user process jio_snprintf(buffer, bufferSize, "Core dumps may be processed with %s", core_path); #endif } else if (getrlimit(RLIMIT_CORE, &rlim) != 0) { jio_snprintf(buffer, bufferSize, "%s (may not exist)", core_path); } else { switch(rlim.rlim_cur) { case RLIM_INFINITY: jio_snprintf(buffer, bufferSize, "%s", core_path); warn = false; break; case 0: jio_snprintf(buffer, bufferSize, "Core dumps have been disabled. To enable core dumping, try \"ulimit -c unlimited\" before starting Java again"); success = false; break; default: jio_snprintf(buffer, bufferSize, "%s (max size " UINT64_FORMAT " k). To ensure a full core dump, try \"ulimit -c unlimited\" before starting Java again", core_path, uint64_t(rlim.rlim_cur) / K); break; } } if (!check_only) { VMError::record_coredump_status(buffer, success); } else if (warn) { warning("CreateCoredumpOnCrash specified, but %s", buffer); } } } bool os::committed_in_range(address start, size_t size, address& committed_start, size_t& committed_size) { #ifdef _AIX committed_start = start; committed_size = size; return true; #else int mincore_return_value; constexpr size_t stripe = 1024; // query this many pages each time mincore_vec_t vec [stripe + 1]; // set a guard DEBUG_ONLY(vec[stripe] = 'X'); size_t page_sz = os::vm_page_size(); uintx pages = size / page_sz; assert(is_aligned(start, page_sz), "Start address must be page aligned"); assert(is_aligned(size, page_sz), "Size must be page aligned"); committed_start = nullptr; int loops = checked_cast((pages + stripe - 1) / stripe); int committed_pages = 0; address loop_base = start; bool found_range = false; for (int index = 0; index < loops && !found_range; index ++) { assert(pages > 0, "Nothing to do"); uintx pages_to_query = (pages >= stripe) ? stripe : pages; pages -= pages_to_query; // Get stable read int fail_count = 0; while ((mincore_return_value = mincore(loop_base, pages_to_query * page_sz, vec)) == -1 && errno == EAGAIN){ if (++fail_count == 1000){ return false; } } // During shutdown, some memory goes away without properly notifying NMT, // E.g. ConcurrentGCThread/WatcherThread can exit without deleting thread object. // Bailout and return as not committed for now. if (mincore_return_value == -1 && errno == ENOMEM) { return false; } // If mincore is not supported. if (mincore_return_value == -1 && errno == ENOSYS) { return false; } assert(vec[stripe] == 'X', "overflow guard"); assert(mincore_return_value == 0, "Range must be valid"); // Process this stripe for (uintx vecIdx = 0; vecIdx < pages_to_query; vecIdx ++) { if ((vec[vecIdx] & 0x01) == 0) { // not committed // End of current contiguous region if (committed_start != nullptr) { found_range = true; break; } } else { // committed // Start of region if (committed_start == nullptr) { committed_start = loop_base + page_sz * vecIdx; } committed_pages ++; } } loop_base += pages_to_query * page_sz; } if (committed_start != nullptr) { assert(committed_pages > 0, "Must have committed region"); assert(committed_pages <= int(size / page_sz), "Can not commit more than it has"); assert(committed_start >= start && committed_start < start + size, "Out of range"); committed_size = page_sz * committed_pages; return true; } else { assert(committed_pages == 0, "Should not have committed region"); return false; } #endif } int os::get_native_stack(address* stack, int frames, int toSkip) { int frame_idx = 0; int num_of_frames; // number of frames captured frame fr = os::current_frame(); while (fr.pc() && frame_idx < frames) { if (toSkip > 0) { toSkip --; } else { stack[frame_idx ++] = fr.pc(); } if (fr.fp() == nullptr || fr.cb() != nullptr || fr.sender_pc() == nullptr || os::is_first_C_frame(&fr)) { break; } fr = os::get_sender_for_C_frame(&fr); } num_of_frames = frame_idx; for (; frame_idx < frames; frame_idx ++) { stack[frame_idx] = nullptr; } return num_of_frames; } int os::get_last_error() { return errno; } size_t os::lasterror(char *buf, size_t len) { if (errno == 0) return 0; const char *s = os::strerror(errno); size_t n = ::strlen(s); if (n >= len) { n = len - 1; } ::strncpy(buf, s, n); buf[n] = '\0'; return n; } //////////////////////////////////////////////////////////////////////////////// // breakpoint support void os::breakpoint() { BREAKPOINT; } extern "C" void breakpoint() { // use debugger to set breakpoint here } // Return true if user is running as root. bool os::have_special_privileges() { static bool privileges = (getuid() != geteuid()) || (getgid() != getegid()); return privileges; } void os::wait_for_keypress_at_exit(void) { // don't do anything on posix platforms return; } int os::create_file_for_heap(const char* dir) { int fd; #if defined(LINUX) && defined(O_TMPFILE) char* native_dir = os::strdup(dir); if (native_dir == nullptr) { vm_exit_during_initialization(err_msg("strdup failed during creation of backing file for heap (%s)", os::strerror(errno))); return -1; } os::native_path(native_dir); fd = os::open(dir, O_TMPFILE | O_RDWR, S_IRUSR | S_IWUSR); os::free(native_dir); if (fd == -1) #endif { const char name_template[] = "/jvmheap.XXXXXX"; size_t fullname_len = strlen(dir) + strlen(name_template); char *fullname = (char*)os::malloc(fullname_len + 1, mtInternal); if (fullname == nullptr) { vm_exit_during_initialization(err_msg("Malloc failed during creation of backing file for heap (%s)", os::strerror(errno))); return -1; } int n = snprintf(fullname, fullname_len + 1, "%s%s", dir, name_template); assert((size_t)n == fullname_len, "Unexpected number of characters in string"); os::native_path(fullname); // create a new file. fd = mkstemp(fullname); if (fd < 0) { warning("Could not create file for heap with template %s", fullname); os::free(fullname); return -1; } else { // delete the name from the filesystem. When 'fd' is closed, the file (and space) will be deleted. int ret = unlink(fullname); assert_with_errno(ret == 0, "unlink returned error"); } os::free(fullname); } return fd; } // return current position of file pointer jlong os::current_file_offset(int fd) { return (jlong)::lseek(fd, (off_t)0, SEEK_CUR); } // move file pointer to the specified offset jlong os::seek_to_file_offset(int fd, jlong offset) { return (jlong)::lseek(fd, (off_t)offset, SEEK_SET); } // Is a (classpath) directory empty? bool os::dir_is_empty(const char* path) { DIR *dir = nullptr; struct dirent *ptr; dir = ::opendir(path); if (dir == nullptr) return true; // Scan the directory bool result = true; while (result && (ptr = ::readdir(dir)) != nullptr) { if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) { result = false; } } ::closedir(dir); return result; } static char* reserve_mmapped_memory(size_t bytes, char* requested_addr, MemTag mem_tag) { char * addr; int flags = MAP_PRIVATE NOT_AIX( | MAP_NORESERVE ) | MAP_ANONYMOUS; if (requested_addr != nullptr) { assert((uintptr_t)requested_addr % os::vm_page_size() == 0, "Requested address should be aligned to OS page size"); flags |= MAP_FIXED; } // Map reserved/uncommitted pages PROT_NONE so we fail early if we // touch an uncommitted page. Otherwise, the read/write might // succeed if we have enough swap space to back the physical page. addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, flags, -1, 0); if (addr != MAP_FAILED) { MemTracker::record_virtual_memory_reserve((address)addr, bytes, CALLER_PC, mem_tag); return addr; } return nullptr; } static int util_posix_fallocate(int fd, off_t offset, off_t len) { static_assert(sizeof(off_t) == 8, "Expected Large File Support in this file"); #ifdef __APPLE__ fstore_t store = { F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, len }; // First we try to get a continuous chunk of disk space int ret = fcntl(fd, F_PREALLOCATE, &store); if (ret == -1) { // Maybe we are too fragmented, try to allocate non-continuous range store.fst_flags = F_ALLOCATEALL; ret = fcntl(fd, F_PREALLOCATE, &store); } if(ret != -1) { return ftruncate(fd, len); } return -1; #else return posix_fallocate(fd, offset, len); #endif } // Map the given address range to the provided file descriptor. char* os::map_memory_to_file(char* base, size_t size, int fd) { assert(fd != -1, "File descriptor is not valid"); // allocate space for the file int ret = util_posix_fallocate(fd, 0, (off_t)size); if (ret != 0) { vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory. error(%d)", ret)); return nullptr; } int prot = PROT_READ | PROT_WRITE; int flags = MAP_SHARED; if (base != nullptr) { flags |= MAP_FIXED; } char* addr = (char*)mmap(base, size, prot, flags, fd, 0); if (addr == MAP_FAILED) { warning("Failed mmap to file. (%s)", os::strerror(errno)); return nullptr; } if (base != nullptr && addr != base) { if (!os::release_memory(addr, size)) { warning("Could not release memory on unsuccessful file mapping"); } return nullptr; } return addr; } char* os::replace_existing_mapping_with_file_mapping(char* base, size_t size, int fd) { assert(fd != -1, "File descriptor is not valid"); assert(base != nullptr, "Base cannot be null"); return map_memory_to_file(base, size, fd); } static size_t calculate_aligned_extra_size(size_t size, size_t alignment) { assert(is_aligned(alignment, os::vm_allocation_granularity()), "Alignment must be a multiple of allocation granularity (page size)"); assert(is_aligned(size, os::vm_allocation_granularity()), "Size must be a multiple of allocation granularity (page size)"); size_t extra_size = size + alignment; assert(extra_size >= size, "overflow, size is too large to allow alignment"); return extra_size; } // After a bigger chunk was mapped, unmaps start and end parts to get the requested alignment. static char* chop_extra_memory(size_t size, size_t alignment, char* extra_base, size_t extra_size) { // Do manual alignment char* aligned_base = align_up(extra_base, alignment); // [ | | ] // ^ extra_base // ^ extra_base + begin_offset == aligned_base // extra_base + begin_offset + size ^ // extra_base + extra_size ^ // |<>| == begin_offset // end_offset == |<>| size_t begin_offset = aligned_base - extra_base; size_t end_offset = (extra_base + extra_size) - (aligned_base + size); if (begin_offset > 0) { os::release_memory(extra_base, begin_offset); } if (end_offset > 0) { os::release_memory(extra_base + begin_offset + size, end_offset); } return aligned_base; } // Multiple threads can race in this code, and can remap over each other with MAP_FIXED, // so on posix, unmap the section at the start and at the end of the chunk that we mapped // rather than unmapping and remapping the whole chunk to get requested alignment. char* os::reserve_memory_aligned(size_t size, size_t alignment, MemTag mem_tag, bool exec) { size_t extra_size = calculate_aligned_extra_size(size, alignment); char* extra_base = os::reserve_memory(extra_size, mem_tag, exec); if (extra_base == nullptr) { return nullptr; } return chop_extra_memory(size, alignment, extra_base, extra_size); } char* os::map_memory_to_file_aligned(size_t size, size_t alignment, int file_desc, MemTag mem_tag) { size_t extra_size = calculate_aligned_extra_size(size, alignment); // For file mapping, we do not call os:map_memory_to_file(size,fd) since: // - we later chop away parts of the mapping using os::release_memory and that could fail if the // original mmap call had been tied to an fd. // - The memory API os::reserve_memory uses is an implementation detail. It may (and usually is) // mmap but it also may System V shared memory which cannot be uncommitted as a whole, so // chopping off and unmapping excess bits back and front (see below) would not work. char* extra_base = reserve_mmapped_memory(extra_size, nullptr, mem_tag); if (extra_base == nullptr) { return nullptr; } char* aligned_base = chop_extra_memory(size, alignment, extra_base, extra_size); // After we have an aligned address, we can replace anonymous mapping with file mapping if (replace_existing_mapping_with_file_mapping(aligned_base, size, file_desc) == nullptr) { vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory")); } MemTracker::record_virtual_memory_commit((address)aligned_base, size, CALLER_PC); return aligned_base; } int os::get_fileno(FILE* fp) { return NOT_AIX(::)fileno(fp); } struct tm* os::gmtime_pd(const time_t* clock, struct tm* res) { return gmtime_r(clock, res); } void os::Posix::print_load_average(outputStream* st) { st->print("load average: "); double loadavg[3]; int res = os::loadavg(loadavg, 3); if (res != -1) { st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]); } else { st->print(" Unavailable"); } st->cr(); } // boot/uptime information; // unfortunately it does not work on macOS and Linux because the utx chain has no entry // for reboot at least on my test machines void os::Posix::print_uptime_info(outputStream* st) { int bootsec = -1; time_t currsec = time(nullptr); struct utmpx* ent; setutxent(); while ((ent = getutxent())) { if (!strcmp("system boot", ent->ut_line)) { bootsec = (int)ent->ut_tv.tv_sec; break; } } if (bootsec != -1) { os::print_dhm(st, "OS uptime:", currsec-bootsec); } } static void print_rlimit(outputStream* st, const char* msg, int resource, bool output_k = false) { struct rlimit rlim; st->print(" %s ", msg); int res = getrlimit(resource, &rlim); if (res == -1) { st->print("could not obtain value"); } else { // soft limit if (rlim.rlim_cur == RLIM_INFINITY) { st->print("infinity"); } else { if (output_k) { st->print(UINT64_FORMAT "k", uint64_t(rlim.rlim_cur) / K); } else { st->print(UINT64_FORMAT, uint64_t(rlim.rlim_cur)); } } // hard limit st->print("/"); if (rlim.rlim_max == RLIM_INFINITY) { st->print("infinity"); } else { if (output_k) { st->print(UINT64_FORMAT "k", uint64_t(rlim.rlim_max) / K); } else { st->print(UINT64_FORMAT, uint64_t(rlim.rlim_max)); } } } } void os::Posix::print_rlimit_info(outputStream* st) { st->print("rlimit (soft/hard):"); print_rlimit(st, "STACK", RLIMIT_STACK, true); print_rlimit(st, ", CORE", RLIMIT_CORE, true); #if defined(AIX) st->print(", NPROC "); st->print("%ld", sysconf(_SC_CHILD_MAX)); print_rlimit(st, ", THREADS", RLIMIT_THREADS); #else print_rlimit(st, ", NPROC", RLIMIT_NPROC); #endif print_rlimit(st, ", NOFILE", RLIMIT_NOFILE); print_rlimit(st, ", AS", RLIMIT_AS, true); print_rlimit(st, ", CPU", RLIMIT_CPU); print_rlimit(st, ", DATA", RLIMIT_DATA, true); // maximum size of files that the process may create print_rlimit(st, ", FSIZE", RLIMIT_FSIZE, true); #if defined(LINUX) || defined(__APPLE__) // maximum number of bytes of memory that may be locked into RAM // (rounded down to the nearest multiple of system pagesize) print_rlimit(st, ", MEMLOCK", RLIMIT_MEMLOCK, true); #endif // MacOS; The maximum size (in bytes) to which a process's resident set size may grow. #if defined(__APPLE__) print_rlimit(st, ", RSS", RLIMIT_RSS, true); #endif st->cr(); } void os::Posix::print_uname_info(outputStream* st) { // kernel st->print("uname: "); struct utsname name; uname(&name); st->print("%s ", name.sysname); #ifdef ASSERT st->print("%s ", name.nodename); #endif st->print("%s ", name.release); st->print("%s ", name.version); st->print("%s", name.machine); st->cr(); } void os::Posix::print_umask(outputStream* st, mode_t umsk) { st->print((umsk & S_IRUSR) ? "r" : "-"); st->print((umsk & S_IWUSR) ? "w" : "-"); st->print((umsk & S_IXUSR) ? "x" : "-"); st->print((umsk & S_IRGRP) ? "r" : "-"); st->print((umsk & S_IWGRP) ? "w" : "-"); st->print((umsk & S_IXGRP) ? "x" : "-"); st->print((umsk & S_IROTH) ? "r" : "-"); st->print((umsk & S_IWOTH) ? "w" : "-"); st->print((umsk & S_IXOTH) ? "x" : "-"); } void os::print_user_info(outputStream* st) { unsigned id = (unsigned) ::getuid(); st->print("uid : %u ", id); id = (unsigned) ::geteuid(); st->print("euid : %u ", id); id = (unsigned) ::getgid(); st->print("gid : %u ", id); id = (unsigned) ::getegid(); st->print_cr("egid : %u", id); st->cr(); mode_t umsk = ::umask(0); ::umask(umsk); st->print("umask: %04o (", (unsigned) umsk); os::Posix::print_umask(st, umsk); st->print_cr(")"); st->cr(); } // Print all active locale categories, one line each void os::print_active_locale(outputStream* st) { st->print_cr("Active Locale:"); // Posix is quiet about how exactly LC_ALL is implemented. // Just print it out too, in case LC_ALL is held separately // from the individual categories. #define LOCALE_CAT_DO(f) \ f(LC_ALL) \ f(LC_COLLATE) \ f(LC_CTYPE) \ f(LC_MESSAGES) \ f(LC_MONETARY) \ f(LC_NUMERIC) \ f(LC_TIME) #define XX(cat) { cat, #cat }, const struct { int c; const char* name; } categories[] = { LOCALE_CAT_DO(XX) { -1, nullptr } }; #undef XX #undef LOCALE_CAT_DO for (int i = 0; categories[i].c != -1; i ++) { const char* locale = setlocale(categories[i].c, nullptr); st->print_cr("%s=%s", categories[i].name, ((locale != nullptr) ? locale : "")); } } bool os::get_host_name(char* buf, size_t buflen) { struct utsname name; int retcode = uname(&name); if (retcode != -1) { jio_snprintf(buf, buflen, "%s", name.nodename); return true; } const char* errmsg = os::strerror(errno); log_warning(os)("Failed to get host name, error message: %s", errmsg); return false; } #ifndef _LP64 // Helper, on 32bit, for os::has_allocatable_memory_limit static bool is_allocatable(size_t s) { if (s < 2 * G) { return true; } // Use raw anonymous mmap here; no need to go through any // of our reservation layers. We will unmap right away. void* p = ::mmap(nullptr, s, PROT_NONE, MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) { return false; } else { ::munmap(p, s); return true; } } #endif // !_LP64 bool os::has_allocatable_memory_limit(size_t* limit) { struct rlimit rlim; int getrlimit_res = getrlimit(RLIMIT_AS, &rlim); // if there was an error when calling getrlimit, assume that there is no limitation // on virtual memory. bool result; if ((getrlimit_res != 0) || (rlim.rlim_cur == RLIM_INFINITY)) { result = false; } else { *limit = (size_t)rlim.rlim_cur; result = true; } #ifdef _LP64 return result; #else // arbitrary virtual space limit for 32 bit Unices found by testing. If // getrlimit above returned a limit, bound it with this limit. Otherwise // directly use it. const size_t max_virtual_limit = 3800*M; if (result) { *limit = MIN2(*limit, max_virtual_limit); } else { *limit = max_virtual_limit; } // bound by actually allocatable memory. The algorithm uses two bounds, an // upper and a lower limit. The upper limit is the current highest amount of // memory that could not be allocated, the lower limit is the current highest // amount of memory that could be allocated. // The algorithm iteratively refines the result by halving the difference // between these limits, updating either the upper limit (if that value could // not be allocated) or the lower limit (if the that value could be allocated) // until the difference between these limits is "small". // the minimum amount of memory we care about allocating. const size_t min_allocation_size = M; size_t upper_limit = *limit; // first check a few trivial cases if (is_allocatable(upper_limit) || (upper_limit <= min_allocation_size)) { *limit = upper_limit; } else if (!is_allocatable(min_allocation_size)) { // we found that not even min_allocation_size is allocatable. Return it // anyway. There is no point to search for a better value any more. *limit = min_allocation_size; } else { // perform the binary search. size_t lower_limit = min_allocation_size; while ((upper_limit - lower_limit) > min_allocation_size) { size_t temp_limit = ((upper_limit - lower_limit) / 2) + lower_limit; temp_limit = align_down(temp_limit, min_allocation_size); if (is_allocatable(temp_limit)) { lower_limit = temp_limit; } else { upper_limit = temp_limit; } } *limit = lower_limit; } return true; #endif } void* os::get_default_process_handle() { #ifdef __APPLE__ // MacOS X needs to use RTLD_FIRST instead of RTLD_LAZY // to avoid finding unexpected symbols on second (or later) // loads of a library. return (void*)::dlopen(nullptr, RTLD_FIRST); #else return (void*)::dlopen(nullptr, RTLD_LAZY); #endif } void* os::dll_lookup(void* handle, const char* name) { ::dlerror(); // Clear any previous error void* ret = ::dlsym(handle, name); if (ret == nullptr) { const char* tmp = ::dlerror(); // It is possible that we found a null symbol, hence no error. if (tmp != nullptr) { log_debug(os)("Symbol %s not found in dll: %s", name, tmp); } } return ret; } void os::dll_unload(void *lib) { // os::Linux::dll_path returns a pointer to a string that is owned by the dynamic loader. Upon // calling dlclose the dynamic loader may free the memory containing the string, thus we need to // copy the string to be able to reference it after dlclose. const char* l_path = nullptr; #ifdef LINUX char* l_pathdup = nullptr; l_path = os::Linux::dll_path(lib); if (l_path != nullptr) { l_path = l_pathdup = os::strdup(l_path); } #endif // LINUX JFR_ONLY(NativeLibraryUnloadEvent unload_event(l_path);) if (l_path == nullptr) { l_path = ""; } char ebuf[1024]; bool res = os::pd_dll_unload(lib, ebuf, sizeof(ebuf)); if (res) { Events::log_dll_message(nullptr, "Unloaded shared library \"%s\" [" INTPTR_FORMAT "]", l_path, p2i(lib)); log_info(os)("Unloaded shared library \"%s\" [" INTPTR_FORMAT "]", l_path, p2i(lib)); JFR_ONLY(unload_event.set_result(true);) } else { Events::log_dll_message(nullptr, "Attempt to unload shared library \"%s\" [" INTPTR_FORMAT "] failed, %s", l_path, p2i(lib), ebuf); log_info(os)("Attempt to unload shared library \"%s\" [" INTPTR_FORMAT "] failed, %s", l_path, p2i(lib), ebuf); JFR_ONLY(unload_event.set_error_msg(ebuf);) } LINUX_ONLY(os::free(l_pathdup)); } void* os::lookup_function(const char* name) { // This returns the global symbol in the main executable and its dependencies, // as well as shared objects dynamically loaded with RTLD_GLOBAL flag. return dlsym(RTLD_DEFAULT, name); } jlong os::lseek(int fd, jlong offset, int whence) { return (jlong) ::lseek(fd, offset, whence); } int os::ftruncate(int fd, jlong length) { return ::ftruncate(fd, length); } const char* os::get_current_directory(char *buf, size_t buflen) { return getcwd(buf, buflen); } FILE* os::fdopen(int fd, const char* mode) { return ::fdopen(fd, mode); } ssize_t os::pd_write(int fd, const void *buf, size_t nBytes) { ssize_t res; RESTARTABLE(::write(fd, buf, nBytes), res); return res; } ssize_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) { return ::pread(fd, buf, nBytes, offset); } void os::flockfile(FILE* fp) { ::flockfile(fp); } void os::funlockfile(FILE* fp) { ::funlockfile(fp); } DIR* os::opendir(const char* dirname) { assert(dirname != nullptr, "just checking"); return ::opendir(dirname); } struct dirent* os::readdir(DIR* dirp) { assert(dirp != nullptr, "just checking"); return ::readdir(dirp); } int os::closedir(DIR *dirp) { assert(dirp != nullptr, "just checking"); return ::closedir(dirp); } int os::socket_close(int fd) { return ::close(fd); } ssize_t os::recv(int fd, char* buf, size_t nBytes, uint flags) { RESTARTABLE_RETURN_SSIZE_T(::recv(fd, buf, nBytes, flags)); } ssize_t os::send(int fd, char* buf, size_t nBytes, uint flags) { RESTARTABLE_RETURN_SSIZE_T(::send(fd, buf, nBytes, flags)); } ssize_t os::raw_send(int fd, char* buf, size_t nBytes, uint flags) { return os::send(fd, buf, nBytes, flags); } ssize_t os::connect(int fd, struct sockaddr* him, socklen_t len) { RESTARTABLE_RETURN_SSIZE_T(::connect(fd, him, len)); } void os::exit(int num) { permit_forbidden_function::exit(num); } void os::_exit(int num) { permit_forbidden_function::_exit(num); } void os::naked_yield() { sched_yield(); } // Sleep forever; naked call to OS-specific sleep; use with CAUTION void os::infinite_sleep() { while (true) { // sleep forever ... ::sleep(100); // ... 100 seconds at a time } } void os::naked_short_nanosleep(jlong ns) { struct timespec req; assert(ns > -1 && ns < NANOUNITS, "Un-interruptable sleep, short time use only"); req.tv_sec = 0; req.tv_nsec = ns; ::nanosleep(&req, nullptr); return; } void os::naked_short_sleep(jlong ms) { assert(ms < MILLIUNITS, "Un-interruptable sleep, short time use only"); os::naked_short_nanosleep(millis_to_nanos(ms)); return; } char* os::Posix::describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr) { size_t stack_size = 0; size_t guard_size = 0; int detachstate = 0; pthread_attr_getstacksize(attr, &stack_size); pthread_attr_getguardsize(attr, &guard_size); // Work around glibc stack guard issue, see os::create_thread() in os_linux.cpp. LINUX_ONLY(if (os::Linux::adjustStackSizeForGuardPages()) stack_size -= guard_size;) pthread_attr_getdetachstate(attr, &detachstate); jio_snprintf(buf, buflen, "stacksize: %zuk, guardsize: %zuk, %s", stack_size / K, guard_size / K, (detachstate == PTHREAD_CREATE_DETACHED ? "detached" : "joinable")); return buf; } char* os::realpath(const char* filename, char* outbuf, size_t outbuflen) { if (filename == nullptr || outbuf == nullptr || outbuflen < 1) { assert(false, "os::realpath: invalid arguments."); errno = EINVAL; return nullptr; } char* result = nullptr; // This assumes platform realpath() is implemented according to POSIX.1-2008. // POSIX.1-2008 allows to specify null for the output buffer, in which case // output buffer is dynamically allocated and must be ::free()'d by the caller. char* p = permit_forbidden_function::realpath(filename, nullptr); if (p != nullptr) { if (strlen(p) < outbuflen) { strcpy(outbuf, p); result = outbuf; } else { errno = ENAMETOOLONG; } permit_forbidden_function::free(p); // *not* os::free } else { // Fallback for platforms struggling with modern Posix standards (AIX 5.3, 6.1). If realpath // returns EINVAL, this may indicate that realpath is not POSIX.1-2008 compatible and // that it complains about the null we handed down as user buffer. // In this case, use the user provided buffer but at least check whether realpath caused // a memory overwrite. if (errno == EINVAL) { outbuf[outbuflen - 1] = '\0'; p = permit_forbidden_function::realpath(filename, outbuf); if (p != nullptr) { guarantee(outbuf[outbuflen - 1] == '\0', "realpath buffer overwrite detected."); result = p; } } } return result; } int os::stat(const char *path, struct stat *sbuf) { return ::stat(path, sbuf); } char * os::native_path(char *path) { return path; } bool os::same_files(const char* file1, const char* file2) { if (file1 == nullptr && file2 == nullptr) { return true; } if (file1 == nullptr || file2 == nullptr) { return false; } if (strcmp(file1, file2) == 0) { return true; } bool is_same = false; struct stat st1; struct stat st2; if (os::stat(file1, &st1) < 0) { return false; } if (os::stat(file2, &st2) < 0) { return false; } if (st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino) { // same files is_same = true; } return is_same; } static char saved_jvm_path[MAXPATHLEN] = {0}; // Find the full path to the current module, libjvm.so void os::jvm_path(char *buf, jint buflen) { // Error checking. if (buflen < MAXPATHLEN) { assert(false, "must use a large-enough buffer"); buf[0] = '\0'; return; } // Lazy resolve the path to current module. if (saved_jvm_path[0] != 0) { strcpy(buf, saved_jvm_path); return; } const char* fname; #ifdef AIX Dl_info dlinfo; int ret = dladdr(CAST_FROM_FN_PTR(void *, os::jvm_path), &dlinfo); assert(ret != 0, "cannot locate libjvm"); if (ret == 0) { return; } fname = dlinfo.dli_fname; #else char dli_fname[MAXPATHLEN]; dli_fname[0] = '\0'; bool ret = dll_address_to_library_name( CAST_FROM_FN_PTR(address, os::jvm_path), dli_fname, sizeof(dli_fname), nullptr); assert(ret, "cannot locate libjvm"); if (!ret) { return; } fname = dli_fname; #endif // AIX char* rp = nullptr; if (fname[0] != '\0') { rp = os::realpath(fname, buf, buflen); } if (rp == nullptr) { return; } // If executing unit tests we require JAVA_HOME to point to the real JDK. if (Arguments::executing_unit_tests()) { // Look for JAVA_HOME in the environment. char* java_home_var = ::getenv("JAVA_HOME"); if (java_home_var != nullptr && java_home_var[0] != 0) { // Check the current module name "libjvm.so". const char* p = strrchr(buf, '/'); if (p == nullptr) { return; } assert(strstr(p, "/libjvm") == p, "invalid library name"); stringStream ss(buf, buflen); rp = os::realpath(java_home_var, buf, buflen); if (rp == nullptr) { return; } assert((int)strlen(buf) < buflen, "Ran out of buffer room"); ss.print("%s/lib", buf); // If the path exists within JAVA_HOME, add the VM variant directory and JVM // library name to complete the path to JVM being overridden. Otherwise fallback // to the path to the current library. if (0 == access(buf, F_OK)) { // Use current module name "libjvm.so" ss.print("/%s/libjvm%s", Abstract_VM_Version::vm_variant(), JNI_LIB_SUFFIX); assert(strcmp(buf + strlen(buf) - strlen(JNI_LIB_SUFFIX), JNI_LIB_SUFFIX) == 0, "buf has been truncated"); } else { // Go back to path of .so rp = os::realpath(fname, buf, buflen); if (rp == nullptr) { return; } } } } strncpy(saved_jvm_path, buf, MAXPATHLEN); saved_jvm_path[MAXPATHLEN - 1] = '\0'; } // Called when creating the thread. The minimum stack sizes have already been calculated size_t os::Posix::get_initial_stack_size(ThreadType thr_type, size_t req_stack_size) { size_t stack_size; if (req_stack_size == 0) { stack_size = default_stack_size(thr_type); } else { stack_size = req_stack_size; } switch (thr_type) { case os::java_thread: // Java threads use ThreadStackSize which default value can be // changed with the flag -Xss if (req_stack_size == 0 && JavaThread::stack_size_at_create() > 0) { // no requested size and we have a more specific default value stack_size = JavaThread::stack_size_at_create(); } stack_size = MAX2(stack_size, _java_thread_min_stack_allowed); break; case os::compiler_thread: if (req_stack_size == 0 && CompilerThreadStackSize > 0) { // no requested size and we have a more specific default value stack_size = (size_t)(CompilerThreadStackSize * K); } stack_size = MAX2(stack_size, _compiler_thread_min_stack_allowed); break; case os::vm_thread: case os::gc_thread: case os::watcher_thread: default: // presume the unknown thr_type is a VM internal if (req_stack_size == 0 && VMThreadStackSize > 0) { // no requested size and we have a more specific default value stack_size = (size_t)(VMThreadStackSize * K); } stack_size = MAX2(stack_size, _vm_internal_thread_min_stack_allowed); break; } // pthread_attr_setstacksize() may require that the size be rounded up to the OS page size. // Be careful not to round up to 0. Align down in that case. if (stack_size <= SIZE_MAX - vm_page_size()) { stack_size = align_up(stack_size, vm_page_size()); } else { stack_size = align_down(stack_size, vm_page_size()); } return stack_size; } #ifndef ZERO #ifndef ARM static bool get_frame_at_stack_banging_point(JavaThread* thread, address pc, const void* ucVoid, frame* fr) { if (Interpreter::contains(pc)) { // interpreter performs stack banging after the fixed frame header has // been generated while the compilers perform it before. To maintain // semantic consistency between interpreted and compiled frames, the // method returns the Java sender of the current frame. *fr = os::fetch_frame_from_context(ucVoid); if (!fr->is_first_java_frame()) { // get_frame_at_stack_banging_point() is only called when we // have well defined stacks so java_sender() calls do not need // to assert safe_for_sender() first. *fr = fr->java_sender(); } } else { // more complex code with compiled code assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above"); CodeBlob* cb = CodeCache::find_blob(pc); if (cb == nullptr || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) { // Not sure where the pc points to, fallback to default // stack overflow handling return false; } else { // in compiled code, the stack banging is performed just after the return pc // has been pushed on the stack *fr = os::fetch_compiled_frame_from_context(ucVoid); if (!fr->is_java_frame()) { assert(!fr->is_first_frame(), "Safety check"); // See java_sender() comment above. *fr = fr->java_sender(); } } } assert(fr->is_java_frame(), "Safety check"); return true; } #endif // ARM // This return true if the signal handler should just continue, ie. return after calling this bool os::Posix::handle_stack_overflow(JavaThread* thread, address addr, address pc, const void* ucVoid, address* stub) { // stack overflow StackOverflow* overflow_state = thread->stack_overflow_state(); if (overflow_state->in_stack_yellow_reserved_zone(addr)) { if (thread->thread_state() == _thread_in_Java) { #ifndef ARM // arm32 doesn't have this // vthreads don't support this if (!thread->is_vthread_mounted() && overflow_state->in_stack_reserved_zone(addr)) { frame fr; if (get_frame_at_stack_banging_point(thread, pc, ucVoid, &fr)) { assert(fr.is_java_frame(), "Must be a Java frame"); frame activation = SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr); if (activation.sp() != nullptr) { overflow_state->disable_stack_reserved_zone(); if (activation.is_interpreted_frame()) { overflow_state->set_reserved_stack_activation((address)(activation.fp() // Some platforms use frame pointers for interpreter frames, others use initial sp. #if !defined(PPC64) && !defined(S390) + frame::interpreter_frame_initial_sp_offset #endif )); } else { overflow_state->set_reserved_stack_activation((address)activation.unextended_sp()); } return true; // just continue } } } #endif // ARM // Throw a stack overflow exception. Guard pages will be re-enabled // while unwinding the stack. overflow_state->disable_stack_yellow_reserved_zone(); *stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW); } else { // Thread was in the vm or native code. Return and try to finish. overflow_state->disable_stack_yellow_reserved_zone(); return true; // just continue } } else if (overflow_state->in_stack_red_zone(addr)) { // Fatal red zone violation. Disable the guard pages and keep // on handling the signal. overflow_state->disable_stack_red_zone(); tty->print_raw_cr("An irrecoverable stack overflow has occurred."); // This is a likely cause, but hard to verify. Let's just print // it as a hint. tty->print_raw_cr("Please check if any of your loaded .so files has " "enabled executable stack (see man page execstack(8))"); } else { #ifdef LINUX // This only works with os::Linux::manually_expand_stack() // Accessing stack address below sp may cause SEGV if current // thread has MAP_GROWSDOWN stack. This should only happen when // current thread was created by user code with MAP_GROWSDOWN flag // and then attached to VM. See notes in os_linux.cpp. if (thread->osthread()->expanding_stack() == 0) { thread->osthread()->set_expanding_stack(); if (os::Linux::manually_expand_stack(thread, addr)) { thread->osthread()->clear_expanding_stack(); return true; // just continue } thread->osthread()->clear_expanding_stack(); } else { fatal("recursive segv. expanding stack."); } #else tty->print_raw_cr("SIGSEGV happened inside stack but outside yellow and red zone."); #endif // LINUX } return false; } #endif // ZERO bool os::Posix::is_root(uid_t uid){ return ROOT_UID == uid; } bool os::Posix::matches_effective_uid_or_root(uid_t uid) { return is_root(uid) || geteuid() == uid; } bool os::Posix::matches_effective_uid_and_gid_or_root(uid_t uid, gid_t gid) { return is_root(uid) || (geteuid() == uid && getegid() == gid); } // Shared clock/time and other supporting routines for pthread_mutex/cond // initialization. This is enabled on Solaris but only some of the clock/time // functionality is actually used there. // Shared condattr object for use with relative timed-waits. Will be associated // with CLOCK_MONOTONIC if available to avoid issues with time-of-day changes, // but otherwise whatever default is used by the platform - generally the // time-of-day clock. static pthread_condattr_t _condAttr[1]; // Shared mutexattr to explicitly set the type to PTHREAD_MUTEX_NORMAL as not // all systems (e.g. FreeBSD) map the default to "normal". static pthread_mutexattr_t _mutexAttr[1]; // common basic initialization that is always supported static void pthread_init_common(void) { int status; if ((status = pthread_condattr_init(_condAttr)) != 0) { fatal("pthread_condattr_init: %s", os::strerror(status)); } if ((status = pthread_mutexattr_init(_mutexAttr)) != 0) { fatal("pthread_mutexattr_init: %s", os::strerror(status)); } if ((status = pthread_mutexattr_settype(_mutexAttr, PTHREAD_MUTEX_NORMAL)) != 0) { fatal("pthread_mutexattr_settype: %s", os::strerror(status)); } PlatformMutex::init(); } static int (*_pthread_condattr_setclock)(pthread_condattr_t *, clockid_t) = nullptr; static bool _use_clock_monotonic_condattr = false; // Determine what POSIX API's are present and do appropriate // configuration. void os::Posix::init(void) { #if defined(_ALLBSD_SOURCE) clock_tics_per_sec = CLK_TCK; #else clock_tics_per_sec = checked_cast(sysconf(_SC_CLK_TCK)); #endif // NOTE: no logging available when this is called. Put logging // statements in init_2(). // Check for pthread_condattr_setclock support. // libpthread is already loaded. int (*condattr_setclock_func)(pthread_condattr_t*, clockid_t) = (int (*)(pthread_condattr_t*, clockid_t))dlsym(RTLD_DEFAULT, "pthread_condattr_setclock"); if (condattr_setclock_func != nullptr) { _pthread_condattr_setclock = condattr_setclock_func; } // Now do general initialization. pthread_init_common(); int status; if (_pthread_condattr_setclock != nullptr) { if ((status = _pthread_condattr_setclock(_condAttr, CLOCK_MONOTONIC)) != 0) { if (status == EINVAL) { _use_clock_monotonic_condattr = false; warning("Unable to use monotonic clock with relative timed-waits" \ " - changes to the time-of-day clock may have adverse affects"); } else { fatal("pthread_condattr_setclock: %s", os::strerror(status)); } } else { _use_clock_monotonic_condattr = true; } } initial_time_count = javaTimeNanos(); } void os::Posix::init_2(void) { log_info(os)("Use of CLOCK_MONOTONIC is supported"); log_info(os)("Use of pthread_condattr_setclock is%s supported", (_pthread_condattr_setclock != nullptr ? "" : " not")); log_info(os)("Relative timed-wait using pthread_cond_timedwait is associated with %s", _use_clock_monotonic_condattr ? "CLOCK_MONOTONIC" : "the default clock"); } int os::Posix::clock_tics_per_second() { return clock_tics_per_sec; } #ifdef ASSERT bool os::Posix::ucontext_is_interpreter(const ucontext_t* uc) { assert(uc != nullptr, "invariant"); address pc = os::Posix::ucontext_get_pc(uc); assert(pc != nullptr, "invariant"); return Interpreter::contains(pc); } #endif // Utility to convert the given timeout to an absolute timespec // (based on the appropriate clock) to use with pthread_cond_timewait, // and sem_timedwait(). // The clock queried here must be the clock used to manage the // timeout of the condition variable or semaphore. // // The passed in timeout value is either a relative time in nanoseconds // or an absolute time in milliseconds. A relative timeout will be // associated with CLOCK_MONOTONIC if available, unless the real-time clock // is explicitly requested; otherwise, or if absolute, // the default time-of-day clock will be used. // Given time is a 64-bit value and the time_t used in the timespec is // sometimes a signed-32-bit value we have to watch for overflow if times // way in the future are given. Further on Solaris versions // prior to 10 there is a restriction (see cond_timedwait) that the specified // number of seconds, in abstime, is less than current_time + 100000000. // As it will be over 20 years before "now + 100000000" will overflow we can // ignore overflow and just impose a hard-limit on seconds using the value // of "now + 100000000". This places a limit on the timeout of about 3.17 // years from "now". // #define MAX_SECS 100000000 // Calculate a new absolute time that is "timeout" nanoseconds from "now". // "unit" indicates the unit of "now_part_sec" (may be nanos or micros depending // on which clock API is being used). static void calc_rel_time(timespec* abstime, jlong timeout, jlong now_sec, jlong now_part_sec, jlong unit) { time_t max_secs = now_sec + MAX_SECS; jlong seconds = timeout / NANOUNITS; timeout %= NANOUNITS; // remaining nanos if (seconds >= MAX_SECS) { // More seconds than we can add, so pin to max_secs. abstime->tv_sec = max_secs; abstime->tv_nsec = 0; } else { abstime->tv_sec = now_sec + seconds; long nanos = (now_part_sec * (NANOUNITS / unit)) + timeout; if (nanos >= NANOUNITS) { // overflow abstime->tv_sec += 1; nanos -= NANOUNITS; } abstime->tv_nsec = nanos; } } // Unpack the given deadline in milliseconds since the epoch, into the given timespec. // The current time in seconds is also passed in to enforce an upper bound as discussed above. static void unpack_abs_time(timespec* abstime, jlong deadline, jlong now_sec) { time_t max_secs = now_sec + MAX_SECS; jlong seconds = deadline / MILLIUNITS; jlong millis = deadline % MILLIUNITS; if (seconds >= max_secs) { // Absolute seconds exceeds allowed max, so pin to max_secs. abstime->tv_sec = max_secs; abstime->tv_nsec = 0; } else { abstime->tv_sec = seconds; abstime->tv_nsec = millis_to_nanos(millis); } } static jlong millis_to_nanos_bounded(jlong millis) { // We have to watch for overflow when converting millis to nanos, // but if millis is that large then we will end up limiting to // MAX_SECS anyway, so just do that here. if (millis / MILLIUNITS > MAX_SECS) { millis = jlong(MAX_SECS) * MILLIUNITS; } return millis_to_nanos(millis); } static void to_abstime(timespec* abstime, jlong timeout, bool isAbsolute, bool isRealtime) { DEBUG_ONLY(time_t max_secs = MAX_SECS;) if (timeout < 0) { timeout = 0; } clockid_t clock = CLOCK_MONOTONIC; if (isAbsolute || (!_use_clock_monotonic_condattr || isRealtime)) { clock = CLOCK_REALTIME; } struct timespec now; int status = clock_gettime(clock, &now); assert(status == 0, "clock_gettime error: %s", os::strerror(errno)); if (!isAbsolute) { calc_rel_time(abstime, timeout, now.tv_sec, now.tv_nsec, NANOUNITS); } else { unpack_abs_time(abstime, timeout, now.tv_sec); } DEBUG_ONLY(max_secs += now.tv_sec;) assert(abstime->tv_sec >= 0, "tv_sec < 0"); assert(abstime->tv_sec <= max_secs, "tv_sec > max_secs"); assert(abstime->tv_nsec >= 0, "tv_nsec < 0"); assert(abstime->tv_nsec < NANOUNITS, "tv_nsec >= NANOUNITS"); } // Create an absolute time 'millis' milliseconds in the future, using the // real-time (time-of-day) clock. Used by PosixSemaphore. void os::Posix::to_RTC_abstime(timespec* abstime, int64_t millis) { to_abstime(abstime, millis_to_nanos_bounded(millis), false /* not absolute */, true /* use real-time clock */); } // Common (partly) shared time functions jlong os::javaTimeMillis() { struct timespec ts; int status = clock_gettime(CLOCK_REALTIME, &ts); assert(status == 0, "clock_gettime error: %s", os::strerror(errno)); return jlong(ts.tv_sec) * MILLIUNITS + jlong(ts.tv_nsec) / NANOUNITS_PER_MILLIUNIT; } void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) { struct timespec ts; int status = clock_gettime(CLOCK_REALTIME, &ts); assert(status == 0, "clock_gettime error: %s", os::strerror(errno)); seconds = jlong(ts.tv_sec); nanos = jlong(ts.tv_nsec); } // macOS and AIX have platform specific implementations for javaTimeNanos() // using native clock/timer access APIs. These have historically worked well // for those platforms, but it may be possible for them to switch to the // generic clock_gettime mechanism in the future. #if !defined(__APPLE__) && !defined(AIX) jlong os::javaTimeNanos() { struct timespec tp; int status = clock_gettime(CLOCK_MONOTONIC, &tp); assert(status == 0, "clock_gettime error: %s", os::strerror(errno)); jlong result = jlong(tp.tv_sec) * NANOSECS_PER_SEC + jlong(tp.tv_nsec); return result; } void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) { // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past info_ptr->max_value = all_bits_jlong; info_ptr->may_skip_backward = false; // not subject to resetting or drifting info_ptr->may_skip_forward = false; // not subject to resetting or drifting info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time } #endif // ! APPLE && !AIX // Time since start-up in seconds to a fine granularity. double os::elapsedTime() { return ((double)os::elapsed_counter()) / (double)os::elapsed_frequency(); // nanosecond resolution } jlong os::elapsed_counter() { return os::javaTimeNanos() - initial_time_count; } jlong os::elapsed_frequency() { return NANOSECS_PER_SEC; // nanosecond resolution } bool os::supports_vtime() { return true; } // Return the real, user, and system times in seconds from an // arbitrary fixed point in the past. bool os::getTimesSecs(double* process_real_time, double* process_user_time, double* process_system_time) { struct tms ticks; clock_t real_ticks = times(&ticks); if (real_ticks == (clock_t) (-1)) { return false; } else { double ticks_per_second = (double) clock_tics_per_sec; *process_user_time = ((double) ticks.tms_utime) / ticks_per_second; *process_system_time = ((double) ticks.tms_stime) / ticks_per_second; *process_real_time = ((double) real_ticks) / ticks_per_second; return true; } } char * os::local_time_string(char *buf, size_t buflen) { struct tm t; time_t long_time; time(&long_time); localtime_r(&long_time, &t); jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d", t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec); return buf; } struct tm* os::localtime_pd(const time_t* clock, struct tm* res) { return localtime_r(clock, res); } // PlatformEvent // // Assumption: // Only one parker can exist on an event, which is why we allocate // them per-thread. Multiple unparkers can coexist. // // _event serves as a restricted-range semaphore. // -1 : thread is blocked, i.e. there is a waiter // 0 : neutral: thread is running or ready, // could have been signaled after a wait started // 1 : signaled - thread is running or ready // // Having three states allows for some detection of bad usage - see // comments on unpark(). PlatformEvent::PlatformEvent() { int status = pthread_cond_init(_cond, _condAttr); assert_status(status == 0, status, "cond_init"); status = pthread_mutex_init(_mutex, _mutexAttr); assert_status(status == 0, status, "mutex_init"); _event = 0; _nParked = 0; } void PlatformEvent::park() { // AKA "down()" // Transitions for _event: // -1 => -1 : illegal // 1 => 0 : pass - return immediately // 0 => -1 : block; then set _event to 0 before returning // Invariant: Only the thread associated with the PlatformEvent // may call park(). assert(_nParked == 0, "invariant"); int v; // atomically decrement _event for (;;) { v = _event; if (Atomic::cmpxchg(&_event, v, v - 1) == v) break; } guarantee(v >= 0, "invariant"); if (v == 0) { // Do this the hard way by blocking ... int status = pthread_mutex_lock(_mutex); assert_status(status == 0, status, "mutex_lock"); guarantee(_nParked == 0, "invariant"); ++_nParked; while (_event < 0) { // OS-level "spurious wakeups" are ignored status = pthread_cond_wait(_cond, _mutex); assert_status(status == 0 MACOS_ONLY(|| status == ETIMEDOUT), status, "cond_wait"); } --_nParked; _event = 0; status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "mutex_unlock"); // Paranoia to ensure our locked and lock-free paths interact // correctly with each other. OrderAccess::fence(); } guarantee(_event >= 0, "invariant"); } int PlatformEvent::park(jlong millis) { return park_nanos(millis_to_nanos_bounded(millis)); } int PlatformEvent::park_nanos(jlong nanos) { assert(nanos > 0, "nanos are positive"); // Transitions for _event: // -1 => -1 : illegal // 1 => 0 : pass - return immediately // 0 => -1 : block; then set _event to 0 before returning // Invariant: Only the thread associated with the Event/PlatformEvent // may call park(). assert(_nParked == 0, "invariant"); int v; // atomically decrement _event for (;;) { v = _event; if (Atomic::cmpxchg(&_event, v, v - 1) == v) break; } guarantee(v >= 0, "invariant"); if (v == 0) { // Do this the hard way by blocking ... struct timespec abst; to_abstime(&abst, nanos, false, false); int ret = OS_TIMEOUT; int status = pthread_mutex_lock(_mutex); assert_status(status == 0, status, "mutex_lock"); guarantee(_nParked == 0, "invariant"); ++_nParked; while (_event < 0) { status = pthread_cond_timedwait(_cond, _mutex, &abst); assert_status(status == 0 || status == ETIMEDOUT, status, "cond_timedwait"); // OS-level "spurious wakeups" are ignored if (status == ETIMEDOUT) break; } --_nParked; if (_event >= 0) { ret = OS_OK; } _event = 0; status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "mutex_unlock"); // Paranoia to ensure our locked and lock-free paths interact // correctly with each other. OrderAccess::fence(); return ret; } return OS_OK; } void PlatformEvent::unpark() { // Transitions for _event: // 0 => 1 : just return // 1 => 1 : just return // -1 => either 0 or 1; must signal target thread // That is, we can safely transition _event from -1 to either // 0 or 1. // See also: "Semaphores in Plan 9" by Mullender & Cox // // Note: Forcing a transition from "-1" to "1" on an unpark() means // that it will take two back-to-back park() calls for the owning // thread to block. This has the benefit of forcing a spurious return // from the first park() call after an unpark() call which will help // shake out uses of park() and unpark() without checking state conditions // properly. This spurious return doesn't manifest itself in any user code // but only in the correctly written condition checking loops of ObjectMonitor, // Mutex/Monitor, and JavaThread::sleep if (Atomic::xchg(&_event, 1) >= 0) return; int status = pthread_mutex_lock(_mutex); assert_status(status == 0, status, "mutex_lock"); int anyWaiters = _nParked; assert(anyWaiters == 0 || anyWaiters == 1, "invariant"); status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "mutex_unlock"); // Note that we signal() *after* dropping the lock for "immortal" Events. // This is safe and avoids a common class of futile wakeups. In rare // circumstances this can cause a thread to return prematurely from // cond_{timed}wait() but the spurious wakeup is benign and the victim // will simply re-test the condition and re-park itself. // This provides particular benefit if the underlying platform does not // provide wait morphing. if (anyWaiters != 0) { status = pthread_cond_signal(_cond); assert_status(status == 0, status, "cond_signal"); } } // JSR166 support PlatformParker::PlatformParker() : _counter(0), _cur_index(-1) { int status = pthread_cond_init(&_cond[REL_INDEX], _condAttr); assert_status(status == 0, status, "cond_init rel"); status = pthread_cond_init(&_cond[ABS_INDEX], nullptr); assert_status(status == 0, status, "cond_init abs"); status = pthread_mutex_init(_mutex, _mutexAttr); assert_status(status == 0, status, "mutex_init"); } PlatformParker::~PlatformParker() { int status = pthread_cond_destroy(&_cond[REL_INDEX]); assert_status(status == 0, status, "cond_destroy rel"); status = pthread_cond_destroy(&_cond[ABS_INDEX]); assert_status(status == 0, status, "cond_destroy abs"); status = pthread_mutex_destroy(_mutex); assert_status(status == 0, status, "mutex_destroy"); } // Parker::park decrements count if > 0, else does a condvar wait. Unpark // sets count to 1 and signals condvar. Only one thread ever waits // on the condvar. Contention seen when trying to park implies that someone // is unparking you, so don't wait. And spurious returns are fine, so there // is no need to track notifications. void Parker::park(bool isAbsolute, jlong time) { // Optional fast-path check: // Return immediately if a permit is available. // We depend on Atomic::xchg() having full barrier semantics // since we are doing a lock-free update to _counter. if (Atomic::xchg(&_counter, 0) > 0) return; JavaThread *jt = JavaThread::current(); // Optional optimization -- avoid state transitions if there's // an interrupt pending. if (jt->is_interrupted(false)) { return; } // Next, demultiplex/decode time arguments struct timespec absTime; if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all return; } if (time > 0) { to_abstime(&absTime, time, isAbsolute, false); } // Enter safepoint region // Beware of deadlocks such as 6317397. // The per-thread Parker:: mutex is a classic leaf-lock. // In particular a thread must never block on the Threads_lock while // holding the Parker:: mutex. If safepoints are pending both the // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock. ThreadBlockInVM tbivm(jt); // Can't access interrupt state now that we are _thread_blocked. If we've // been interrupted since we checked above then _counter will be > 0. // Don't wait if cannot get lock since interference arises from // unparking. if (pthread_mutex_trylock(_mutex) != 0) { return; } int status; if (_counter > 0) { // no wait needed _counter = 0; status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "invariant"); // Paranoia to ensure our locked and lock-free paths interact // correctly with each other and Java-level accesses. OrderAccess::fence(); return; } OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */); assert(_cur_index == -1, "invariant"); if (time == 0) { _cur_index = REL_INDEX; // arbitrary choice when not timed status = pthread_cond_wait(&_cond[_cur_index], _mutex); assert_status(status == 0 MACOS_ONLY(|| status == ETIMEDOUT), status, "cond_wait"); } else { _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX; status = pthread_cond_timedwait(&_cond[_cur_index], _mutex, &absTime); assert_status(status == 0 || status == ETIMEDOUT, status, "cond_timedwait"); } _cur_index = -1; _counter = 0; status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "invariant"); // Paranoia to ensure our locked and lock-free paths interact // correctly with each other and Java-level accesses. OrderAccess::fence(); } void Parker::unpark() { int status = pthread_mutex_lock(_mutex); assert_status(status == 0, status, "invariant"); const int s = _counter; _counter = 1; // must capture correct index before unlocking int index = _cur_index; status = pthread_mutex_unlock(_mutex); assert_status(status == 0, status, "invariant"); // Note that we signal() *after* dropping the lock for "immortal" Events. // This is safe and avoids a common class of futile wakeups. In rare // circumstances this can cause a thread to return prematurely from // cond_{timed}wait() but the spurious wakeup is benign and the victim // will simply re-test the condition and re-park itself. // This provides particular benefit if the underlying platform does not // provide wait morphing. if (s < 1 && index != -1) { // thread is definitely parked status = pthread_cond_signal(&_cond[index]); assert_status(status == 0, status, "invariant"); } } // Platform Mutex/Monitor implementation #if PLATFORM_MONITOR_IMPL_INDIRECT PlatformMutex::Mutex::Mutex() : _next(nullptr) { int status = pthread_mutex_init(&_mutex, _mutexAttr); assert_status(status == 0, status, "mutex_init"); } PlatformMutex::Mutex::~Mutex() { int status = pthread_mutex_destroy(&_mutex); assert_status(status == 0, status, "mutex_destroy"); } pthread_mutex_t PlatformMutex::_freelist_lock; PlatformMutex::Mutex* PlatformMutex::_mutex_freelist = nullptr; void PlatformMutex::init() { int status = pthread_mutex_init(&_freelist_lock, _mutexAttr); assert_status(status == 0, status, "freelist lock init"); } struct PlatformMutex::WithFreeListLocked : public StackObj { WithFreeListLocked() { int status = pthread_mutex_lock(&_freelist_lock); assert_status(status == 0, status, "freelist lock"); } ~WithFreeListLocked() { int status = pthread_mutex_unlock(&_freelist_lock); assert_status(status == 0, status, "freelist unlock"); } }; PlatformMutex::PlatformMutex() { { WithFreeListLocked wfl; _impl = _mutex_freelist; if (_impl != nullptr) { _mutex_freelist = _impl->_next; _impl->_next = nullptr; return; } } _impl = new Mutex(); } PlatformMutex::~PlatformMutex() { WithFreeListLocked wfl; assert(_impl->_next == nullptr, "invariant"); _impl->_next = _mutex_freelist; _mutex_freelist = _impl; } PlatformMonitor::Cond::Cond() : _next(nullptr) { int status = pthread_cond_init(&_cond, _condAttr); assert_status(status == 0, status, "cond_init"); } PlatformMonitor::Cond::~Cond() { int status = pthread_cond_destroy(&_cond); assert_status(status == 0, status, "cond_destroy"); } PlatformMonitor::Cond* PlatformMonitor::_cond_freelist = nullptr; PlatformMonitor::PlatformMonitor() { { WithFreeListLocked wfl; _impl = _cond_freelist; if (_impl != nullptr) { _cond_freelist = _impl->_next; _impl->_next = nullptr; return; } } _impl = new Cond(); } PlatformMonitor::~PlatformMonitor() { WithFreeListLocked wfl; assert(_impl->_next == nullptr, "invariant"); _impl->_next = _cond_freelist; _cond_freelist = _impl; } #else PlatformMutex::PlatformMutex() { int status = pthread_mutex_init(&_mutex, _mutexAttr); assert_status(status == 0, status, "mutex_init"); } PlatformMutex::~PlatformMutex() { int status = pthread_mutex_destroy(&_mutex); assert_status(status == 0, status, "mutex_destroy"); } PlatformMonitor::PlatformMonitor() { int status = pthread_cond_init(&_cond, _condAttr); assert_status(status == 0, status, "cond_init"); } PlatformMonitor::~PlatformMonitor() { int status = pthread_cond_destroy(&_cond); assert_status(status == 0, status, "cond_destroy"); } #endif // PLATFORM_MONITOR_IMPL_INDIRECT // Must already be locked int PlatformMonitor::wait(uint64_t millis) { if (millis > 0) { struct timespec abst; // We have to watch for overflow when converting millis to nanos, // but if millis is that large then we will end up limiting to // MAX_SECS anyway, so just do that here. This also handles values // larger than int64_t max. if (millis / MILLIUNITS > MAX_SECS) { millis = uint64_t(MAX_SECS) * MILLIUNITS; } to_abstime(&abst, millis_to_nanos(int64_t(millis)), false, false); int ret = OS_TIMEOUT; int status = pthread_cond_timedwait(cond(), mutex(), &abst); assert_status(status == 0 || status == ETIMEDOUT, status, "cond_timedwait"); if (status == 0) { ret = OS_OK; } return ret; } else { int status = pthread_cond_wait(cond(), mutex()); assert_status(status == 0 MACOS_ONLY(|| status == ETIMEDOUT), status, "cond_wait"); return OS_OK; } } // Darwin has no "environ" in a dynamic library. #ifdef __APPLE__ #define environ (*_NSGetEnviron()) #else extern char** environ; #endif char** os::get_environ() { return environ; } // Run the specified command in a separate process. Return its exit value, // or -1 on failure (e.g. can't fork a new process). // Notes: -Unlike system(), this function can be called from signal handler. It // doesn't block SIGINT et al. // -this function is unsafe to use in non-error situations, mainly // because the child process will inherit all parent descriptors. int os::fork_and_exec(const char* cmd) { const char* argv[4] = {"sh", "-c", cmd, nullptr}; pid_t pid = -1; char** env = os::get_environ(); // Note: cast is needed because posix_spawn() requires - for compatibility with ancient // C-code - a non-const argv/envp pointer array. But it is fine to hand in literal // strings and just cast the constness away. See also ProcessImpl_md.c. int rc = ::posix_spawn(&pid, "/bin/sh", nullptr, nullptr, (char**) argv, env); if (rc == 0) { int status; // Wait for the child process to exit. This returns immediately if // the child has already exited. */ while (::waitpid(pid, &status, 0) < 0) { switch (errno) { case ECHILD: return 0; case EINTR: break; default: return -1; } } if (WIFEXITED(status)) { // The child exited normally; get its exit code. return WEXITSTATUS(status); } else if (WIFSIGNALED(status)) { // The child exited because of a signal // The best value to return is 0x80 + signal number, // because that is what all Unix shells do, and because // it allows callers to distinguish between process exit and // process death by signal. return 0x80 + WTERMSIG(status); } else { // Unknown exit code; pass it through return status; } } else { // Don't log, we are inside error handling return -1; } } bool os::message_box(const char* title, const char* message) { int i; fdStream err(defaultStream::error_fd()); for (i = 0; i < 78; i++) err.print_raw("="); err.cr(); err.print_raw_cr(title); for (i = 0; i < 78; i++) err.print_raw("-"); err.cr(); err.print_raw_cr(message); for (i = 0; i < 78; i++) err.print_raw("="); err.cr(); char buf[16]; // Prevent process from exiting upon "read error" without consuming all CPU while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); } return buf[0] == 'y' || buf[0] == 'Y'; } //////////////////////////////////////////////////////////////////////////////// // runtime exit support // Note: os::shutdown() might be called very early during initialization, or // called from signal handler. Before adding something to os::shutdown(), make // sure it is async-safe and can handle partially initialized VM. void os::shutdown() { // allow PerfMemory to attempt cleanup of any persistent resources perfMemory_exit(); // needs to remove object in file system AttachListener::abort(); // flush buffered output, finish log files ostream_abort(); // Check for abort hook abort_hook_t abort_hook = Arguments::abort_hook(); if (abort_hook != nullptr) { abort_hook(); } } // Note: os::abort() might be called very early during initialization, or // called from signal handler. Before adding something to os::abort(), make // sure it is async-safe and can handle partially initialized VM. // Also note we can abort while other threads continue to run, so we can // easily trigger secondary faults in those threads. To reduce the likelihood // of that we use _exit rather than exit, so that no atexit hooks get run. // But note that os::shutdown() could also trigger secondary faults. void os::abort(bool dump_core, const void* siginfo, const void* context) { os::shutdown(); if (dump_core) { LINUX_ONLY(if (DumpPrivateMappingsInCore) ClassLoader::close_jrt_image();) ::abort(); // dump core } os::_exit(1); } // Die immediately, no exit hook, no abort hook, no cleanup. // Dump a core file, if possible, for debugging. void os::die() { if (TestUnresponsiveErrorHandler && !CreateCoredumpOnCrash) { // For TimeoutInErrorHandlingTest.java, we just kill the VM // and don't take the time to generate a core file. ::raise(SIGKILL); // ::raise is not noreturn, even though with SIGKILL it definitely won't // return. Hence "fall through" to ::abort, which is declared noreturn. } ::abort(); } const char* os::file_separator() { return "/"; } const char* os::line_separator() { return "\n"; } const char* os::path_separator() { return ":"; } // Map file into memory; uses mmap(). // Notes: // - if caller specifies addr, MAP_FIXED is used. That means existing // mappings will be replaced. // - The file descriptor must be valid (to create anonymous mappings, use // os::reserve_memory()). // Returns address to mapped memory, nullptr on error char* os::pd_map_memory(int fd, const char* unused, size_t file_offset, char *addr, size_t bytes, bool read_only, bool allow_exec) { assert(fd != -1, "Specify a valid file descriptor"); int prot; int flags = MAP_PRIVATE; if (read_only) { prot = PROT_READ; } else { prot = PROT_READ | PROT_WRITE; } if (allow_exec) { prot |= PROT_EXEC; } if (addr != nullptr) { flags |= MAP_FIXED; } char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags, fd, file_offset); if (mapped_address == MAP_FAILED) { return nullptr; } // If we did specify an address, and the mapping succeeded, it should // have returned that address since we specify MAP_FIXED assert(addr == nullptr || addr == mapped_address, "mmap+MAP_FIXED returned " PTR_FORMAT ", expected " PTR_FORMAT, p2i(mapped_address), p2i(addr)); return mapped_address; } // Unmap a block of memory. Uses munmap. bool os::pd_unmap_memory(char* addr, size_t bytes) { return munmap(addr, bytes) == 0; } #ifdef CAN_SHOW_REGISTERS_ON_ASSERT static ucontext_t _saved_assert_context; static bool _has_saved_context = false; #endif // CAN_SHOW_REGISTERS_ON_ASSERT void os::save_assert_context(const void* ucVoid) { #ifdef CAN_SHOW_REGISTERS_ON_ASSERT assert(ucVoid != nullptr, "invariant"); assert(!_has_saved_context, "invariant"); memcpy(&_saved_assert_context, ucVoid, sizeof(ucontext_t)); // on Linux ppc64, ucontext_t contains pointers into itself which have to be patched up // after copying the context (see comment in sys/ucontext.h): #if defined(PPC64) *((void**)&_saved_assert_context.uc_mcontext.regs) = &(_saved_assert_context.uc_mcontext.gp_regs); #elif defined(AMD64) // In the copied version, fpregs should point to the copied contents. // Sanity check: fpregs should point into the context. if ((address)((const ucontext_t*)ucVoid)->uc_mcontext.fpregs > (address)ucVoid) { size_t fpregs_offset = pointer_delta(((const ucontext_t*)ucVoid)->uc_mcontext.fpregs, ucVoid, 1); if (fpregs_offset < sizeof(ucontext_t)) { // Preserve the offset. *((void**)&_saved_assert_context.uc_mcontext.fpregs) = (void*)((address)(void*)&_saved_assert_context + fpregs_offset); } } #endif _has_saved_context = true; #endif // CAN_SHOW_REGISTERS_ON_ASSERT } const void* os::get_saved_assert_context(const void** sigInfo) { #ifdef CAN_SHOW_REGISTERS_ON_ASSERT assert(sigInfo != nullptr, "invariant"); *sigInfo = nullptr; return _has_saved_context ? &_saved_assert_context : nullptr; #endif *sigInfo = nullptr; return nullptr; }