1 /* 2 * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "runtime/os.hpp" 26 27 #ifndef OS_POSIX_OS_POSIX_HPP 28 #define OS_POSIX_OS_POSIX_HPP 29 30 // File conventions 31 static const char* file_separator() { return "/"; } 32 static const char* line_separator() { return "\n"; } 33 static const char* path_separator() { return ":"; } 34 35 class Posix { 36 friend class os; 37 38 protected: 39 static void print_distro_info(outputStream* st); 40 static void print_rlimit_info(outputStream* st); 41 static void print_uname_info(outputStream* st); 42 static void print_libversion_info(outputStream* st); 43 static void print_load_average(outputStream* st); 44 static void print_uptime_info(outputStream* st); 45 46 // Minimum stack size a thread can be created with (allowing 47 // the VM to completely create the thread and enter user code). 48 // The initial values exclude any guard pages (by HotSpot or libc). 49 // set_minimum_stack_sizes() will add the size required for 50 // HotSpot guard pages depending on page size and flag settings. 51 // Libc guard pages are never considered by these values. 52 static size_t _compiler_thread_min_stack_allowed; 53 static size_t _java_thread_min_stack_allowed; 54 static size_t _vm_internal_thread_min_stack_allowed; 55 56 public: 57 static void init(void); // early initialization - no logging available 58 static void init_2(void);// later initialization - logging available 59 60 // Return default stack size for the specified thread type 61 static size_t default_stack_size(os::ThreadType thr_type); 62 // Check and sets minimum stack sizes 63 static jint set_minimum_stack_sizes(); 64 static size_t get_initial_stack_size(ThreadType thr_type, size_t req_stack_size); 65 66 // Returns true if signal is valid. 67 static bool is_valid_signal(int sig); 68 static bool is_sig_ignored(int sig); 69 70 // Helper function, returns a string (e.g. "SIGILL") for a signal. 71 // Returned string is a constant. For unknown signals "UNKNOWN" is returned. 72 static const char* get_signal_name(int sig, char* out, size_t outlen); 73 74 // Helper function, returns a signal number for a given signal name, e.g. 11 75 // for "SIGSEGV". Name can be given with or without "SIG" prefix, so both 76 // "SEGV" or "SIGSEGV" work. Name must be uppercase. 77 // Returns -1 for an unknown signal name. 78 static int get_signal_number(const char* signal_name); 79 80 // Returns one-line short description of a signal set in a user provided buffer. 81 static const char* describe_signal_set_short(const sigset_t* set, char* buffer, size_t size); 82 83 // Prints a short one-line description of a signal set. 84 static void print_signal_set_short(outputStream* st, const sigset_t* set); 85 86 // unblocks the signal masks for current thread 87 static int unblock_thread_signal_mask(const sigset_t *set); 88 89 // Writes a one-line description of a combination of sigaction.sa_flags 90 // into a user provided buffer. Returns that buffer. 91 static const char* describe_sa_flags(int flags, char* buffer, size_t size); 92 93 // Prints a one-line description of a combination of sigaction.sa_flags. 94 static void print_sa_flags(outputStream* st, int flags); 95 96 static address ucontext_get_pc(const ucontext_t* ctx); 97 // Set PC into context. Needed for continuation after signal. 98 static void ucontext_set_pc(ucontext_t* ctx, address pc); 99 100 // Helper function; describes pthread attributes as short string. String is written 101 // to buf with len buflen; buf is returned. 102 static char* describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr); 103 104 // A safe implementation of realpath which will not cause a buffer overflow if the resolved path 105 // is longer than PATH_MAX. 106 // On success, returns 'outbuf', which now contains the path. 107 // On error, it will return NULL and set errno. The content of 'outbuf' is undefined. 108 // On truncation error ('outbuf' too small), it will return NULL and set errno to ENAMETOOLONG. 109 static char* realpath(const char* filename, char* outbuf, size_t outbuflen); 110 111 // Returns true if given uid is root. 112 static bool is_root(uid_t uid); 113 114 // Returns true if given uid is effective or root uid. 115 static bool matches_effective_uid_or_root(uid_t uid); 116 117 // Returns true if either given uid is effective uid and given gid is 118 // effective gid, or if given uid is root. 119 static bool matches_effective_uid_and_gid_or_root(uid_t uid, gid_t gid); 120 121 static struct sigaction *get_preinstalled_handler(int); 122 static void save_preinstalled_handler(int, struct sigaction&); 123 124 static void print_umask(outputStream* st, mode_t umsk); 125 126 static void print_user_info(outputStream* st); 127 128 #ifdef SUPPORTS_CLOCK_MONOTONIC 129 130 private: 131 // These need to be members so we can access them from inline functions 132 static int (*_clock_gettime)(clockid_t, struct timespec *); 133 static int (*_clock_getres)(clockid_t, struct timespec *); 134 public: 135 static bool supports_monotonic_clock(); 136 static int clock_gettime(clockid_t clock_id, struct timespec *tp); 137 static int clock_getres(clockid_t clock_id, struct timespec *tp); 138 139 #else 140 141 static bool supports_monotonic_clock() { return false; } 142 143 #endif 144 145 static void to_RTC_abstime(timespec* abstime, int64_t millis); 146 }; 147 148 /* 149 * Crash protection for the watcher thread. Wrap the callback 150 * with a sigsetjmp and in case of a SIGSEGV/SIGBUS we siglongjmp 151 * back. 152 * To be able to use this - don't take locks, don't rely on destructors, 153 * don't make OS library calls, don't allocate memory, don't print, 154 * don't call code that could leave the heap / memory in an inconsistent state, 155 * or anything else where we are not in control if we suddenly jump out. 156 */ 157 class ThreadCrashProtection : public StackObj { 158 public: 159 static bool is_crash_protected(Thread* thr) { 160 return _crash_protection != NULL && _protected_thread == thr; 161 } 162 163 ThreadCrashProtection(); 164 bool call(os::CrashProtectionCallback& cb); 165 166 static void check_crash_protection(int signal, Thread* thread); 167 private: 168 static Thread* _protected_thread; 169 static ThreadCrashProtection* _crash_protection; 170 static volatile intptr_t _crash_mux; 171 void restore(); 172 sigjmp_buf _jmpbuf; 173 }; 174 175 #ifndef SOLARIS 176 177 /* 178 * This is the platform-specific implementation underpinning 179 * the ParkEvent class, which itself underpins Java-level monitor 180 * operations. See park.hpp for details. 181 * These event objects are type-stable and immortal - we never delete them. 182 * Events are associated with a thread for the lifetime of the thread. 183 */ 184 class PlatformEvent : public CHeapObj<mtSynchronizer> { 185 private: 186 double cachePad[4]; // Increase odds that _mutex is sole occupant of cache line 187 volatile int _event; // Event count/permit: -1, 0 or 1 188 volatile int _nParked; // Indicates if associated thread is blocked: 0 or 1 189 pthread_mutex_t _mutex[1]; // Native mutex for locking 190 pthread_cond_t _cond[1]; // Native condition variable for blocking 191 double postPad[2]; 192 193 protected: // TODO-FIXME: make dtor private 194 ~PlatformEvent() { guarantee(false, "invariant"); } // immortal so can't delete 195 196 public: 197 PlatformEvent(); 198 void park(); 199 int park(jlong millis); 200 void unpark(); 201 202 // Use caution with reset() and fired() -- they may require MEMBARs 203 void reset() { _event = 0; } 204 int fired() { return _event; } 205 }; 206 207 // JSR166 support 208 // PlatformParker provides the platform dependent base class for the 209 // Parker class. It basically provides the internal data structures: 210 // - mutex and convars 211 // which are then used directly by the Parker methods defined in the OS 212 // specific implementation files. 213 // There is significant overlap between the funcionality supported in the 214 // combination of Parker+PlatformParker and PlatformEvent (above). If Parker 215 // were more like ObjectMonitor we could use PlatformEvent in both (with some 216 // API updates of course). But Parker methods use fastpaths that break that 217 // level of encapsulation - so combining the two remains a future project. 218 219 class PlatformParker : public CHeapObj<mtSynchronizer> { 220 protected: 221 enum { 222 REL_INDEX = 0, 223 ABS_INDEX = 1 224 }; 225 int _cur_index; // which cond is in use: -1, 0, 1 226 pthread_mutex_t _mutex[1]; 227 pthread_cond_t _cond[2]; // one for relative times and one for absolute 228 229 public: // TODO-FIXME: make dtor private 230 ~PlatformParker() { guarantee(false, "invariant"); } 231 232 public: 233 PlatformParker(); 234 }; 235 236 // Workaround for a bug in macOSX kernel's pthread support (fixed in Mojave?). 237 // Avoid ever allocating a pthread_mutex_t at the same address as one of our 238 // former pthread_cond_t, by using freelists of mutexes and condvars. 239 // Conditional to avoid extra indirection and padding loss on other platforms. 240 #ifdef __APPLE__ 241 #define PLATFORM_MONITOR_IMPL_INDIRECT 1 242 #else 243 #define PLATFORM_MONITOR_IMPL_INDIRECT 0 244 #endif 245 246 // Platform specific implementations that underpin VM Mutex/Monitor classes 247 248 class PlatformMutex : public CHeapObj<mtSynchronizer> { 249 #if PLATFORM_MONITOR_IMPL_INDIRECT 250 class Mutex : public CHeapObj<mtSynchronizer> { 251 public: 252 pthread_mutex_t _mutex; 253 Mutex* _next; 254 255 Mutex(); 256 ~Mutex(); 257 }; 258 259 Mutex* _impl; 260 261 static pthread_mutex_t _freelist_lock; // used for mutex and cond freelists 262 static Mutex* _mutex_freelist; 263 264 protected: 265 class WithFreeListLocked; 266 pthread_mutex_t* mutex() { return &(_impl->_mutex); } 267 268 public: 269 PlatformMutex(); // Use freelist allocation of impl. 270 ~PlatformMutex(); 271 272 static void init(); // Initialize the freelist. 273 274 #else 275 276 pthread_mutex_t _mutex; 277 278 protected: 279 pthread_mutex_t* mutex() { return &_mutex; } 280 281 public: 282 static void init() {} // Nothing needed for the non-indirect case. 283 284 PlatformMutex(); 285 ~PlatformMutex(); 286 287 #endif // PLATFORM_MONITOR_IMPL_INDIRECT 288 289 private: 290 NONCOPYABLE(PlatformMutex); 291 292 public: 293 void lock(); 294 void unlock(); 295 bool try_lock(); 296 }; 297 298 class PlatformMonitor : public PlatformMutex { 299 #if PLATFORM_MONITOR_IMPL_INDIRECT 300 class Cond : public CHeapObj<mtSynchronizer> { 301 public: 302 pthread_cond_t _cond; 303 Cond* _next; 304 305 Cond(); 306 ~Cond(); 307 }; 308 309 Cond* _impl; 310 311 static Cond* _cond_freelist; 312 313 pthread_cond_t* cond() { return &(_impl->_cond); } 314 315 public: 316 PlatformMonitor(); // Use freelist allocation of impl. 317 ~PlatformMonitor(); 318 319 #else 320 321 pthread_cond_t _cond; 322 pthread_cond_t* cond() { return &_cond; } 323 324 public: 325 PlatformMonitor(); 326 ~PlatformMonitor(); 327 328 #endif // PLATFORM_MONITOR_IMPL_INDIRECT 329 330 private: 331 NONCOPYABLE(PlatformMonitor); 332 333 public: 334 int wait(jlong millis); 335 void notify(); 336 void notify_all(); 337 }; 338 339 #endif // !SOLARIS 340 341 #endif // OS_POSIX_OS_POSIX_HPP