1 /* 2 * Copyright (c) 1999, 2018, 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_VM_OS_POSIX_HPP 28 #define OS_POSIX_VM_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 45 // Minimum stack size a thread can be created with (allowing 46 // the VM to completely create the thread and enter user code). 47 // The initial values exclude any guard pages (by HotSpot or libc). 48 // set_minimum_stack_sizes() will add the size required for 49 // HotSpot guard pages depending on page size and flag settings. 50 // Libc guard pages are never considered by these values. 51 static size_t _compiler_thread_min_stack_allowed; 52 static size_t _java_thread_min_stack_allowed; 53 static size_t _vm_internal_thread_min_stack_allowed; 54 55 public: 56 static void init(void); // early initialization - no logging available 57 static void init_2(void);// later initialization - logging available 58 59 // Return default stack size for the specified thread type 60 static size_t default_stack_size(os::ThreadType thr_type); 61 // Check and sets minimum stack sizes 62 static jint set_minimum_stack_sizes(); 63 static size_t get_initial_stack_size(ThreadType thr_type, size_t req_stack_size); 64 65 // Returns true if signal is valid. 66 static bool is_valid_signal(int sig); 67 static bool is_sig_ignored(int sig); 68 69 // Helper function, returns a string (e.g. "SIGILL") for a signal. 70 // Returned string is a constant. For unknown signals "UNKNOWN" is returned. 71 static const char* get_signal_name(int sig, char* out, size_t outlen); 72 73 // Helper function, returns a signal number for a given signal name, e.g. 11 74 // for "SIGSEGV". Name can be given with or without "SIG" prefix, so both 75 // "SEGV" or "SIGSEGV" work. Name must be uppercase. 76 // Returns -1 for an unknown signal name. 77 static int get_signal_number(const char* signal_name); 78 79 // Returns one-line short description of a signal set in a user provided buffer. 80 static const char* describe_signal_set_short(const sigset_t* set, char* buffer, size_t size); 81 82 // Prints a short one-line description of a signal set. 83 static void print_signal_set_short(outputStream* st, const sigset_t* set); 84 85 // unblocks the signal masks for current thread 86 static int unblock_thread_signal_mask(const sigset_t *set); 87 88 // Writes a one-line description of a combination of sigaction.sa_flags 89 // into a user provided buffer. Returns that buffer. 90 static const char* describe_sa_flags(int flags, char* buffer, size_t size); 91 92 // Prints a one-line description of a combination of sigaction.sa_flags. 93 static void print_sa_flags(outputStream* st, int flags); 94 95 static address ucontext_get_pc(const ucontext_t* ctx); 96 // Set PC into context. Needed for continuation after signal. 97 static void ucontext_set_pc(ucontext_t* ctx, address pc); 98 99 // Helper function; describes pthread attributes as short string. String is written 100 // to buf with len buflen; buf is returned. 101 static char* describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr); 102 103 // A safe implementation of realpath which will not cause a buffer overflow if the resolved path 104 // is longer than PATH_MAX. 105 // On success, returns 'outbuf', which now contains the path. 106 // On error, it will return NULL and set errno. The content of 'outbuf' is undefined. 107 // On truncation error ('outbuf' too small), it will return NULL and set errno to ENAMETOOLONG. 108 static char* realpath(const char* filename, char* outbuf, size_t outbuflen); 109 110 // Returns true if given uid is root. 111 static bool is_root(uid_t uid); 112 113 // Returns true if given uid is effective or root uid. 114 static bool matches_effective_uid_or_root(uid_t uid); 115 116 // Returns true if either given uid is effective uid and given gid is 117 // effective gid, or if given uid is root. 118 static bool matches_effective_uid_and_gid_or_root(uid_t uid, gid_t gid); 119 120 #ifdef SUPPORTS_CLOCK_MONOTONIC 121 122 static bool supports_monotonic_clock(); 123 static int clock_gettime(clockid_t clock_id, struct timespec *tp); 124 static int clock_getres(clockid_t clock_id, struct timespec *tp); 125 126 #else 127 128 static bool supports_monotonic_clock() { return false; } 129 130 #endif 131 }; 132 133 /* 134 * Crash protection for the watcher thread. Wrap the callback 135 * with a sigsetjmp and in case of a SIGSEGV/SIGBUS we siglongjmp 136 * back. 137 * To be able to use this - don't take locks, don't rely on destructors, 138 * don't make OS library calls, don't allocate memory, don't print, 139 * don't call code that could leave the heap / memory in an inconsistent state, 140 * or anything else where we are not in control if we suddenly jump out. 141 */ 142 class ThreadCrashProtection : public StackObj { 143 public: 144 static bool is_crash_protected(Thread* thr) { 145 return _crash_protection != NULL && _protected_thread == thr; 146 } 147 148 ThreadCrashProtection(); 149 bool call(os::CrashProtectionCallback& cb); 150 151 static void check_crash_protection(int signal, Thread* thread); 152 private: 153 static Thread* _protected_thread; 154 static ThreadCrashProtection* _crash_protection; 155 static volatile intptr_t _crash_mux; 156 void restore(); 157 sigjmp_buf _jmpbuf; 158 }; 159 160 #ifndef SOLARIS 161 162 /* 163 * This is the platform-specific implementation underpinning 164 * the ParkEvent class, which itself underpins Java-level monitor 165 * operations. See park.hpp for details. 166 * These event objects are type-stable and immortal - we never delete them. 167 * Events are associated with a thread for the lifetime of the thread. 168 */ 169 class PlatformEvent : public CHeapObj<mtInternal> { 170 private: 171 double cachePad[4]; // Increase odds that _mutex is sole occupant of cache line 172 volatile int _event; // Event count/permit: -1, 0 or 1 173 volatile int _nParked; // Indicates if associated thread is blocked: 0 or 1 174 pthread_mutex_t _mutex[1]; // Native mutex for locking 175 pthread_cond_t _cond[1]; // Native condition variable for blocking 176 double postPad[2]; 177 178 protected: // TODO-FIXME: make dtor private 179 ~PlatformEvent() { guarantee(false, "invariant"); } // immortal so can't delete 180 181 public: 182 PlatformEvent(); 183 void park(); 184 int park(jlong millis); 185 void unpark(); 186 187 // Use caution with reset() and fired() -- they may require MEMBARs 188 void reset() { _event = 0; } 189 int fired() { return _event; } 190 }; 191 192 // JSR166 support 193 // PlatformParker provides the platform dependent base class for the 194 // Parker class. It basically provides the internal data structures: 195 // - mutex and convars 196 // which are then used directly by the Parker methods defined in the OS 197 // specific implementation files. 198 // There is significant overlap between the funcionality supported in the 199 // combination of Parker+PlatformParker and PlatformEvent (above). If Parker 200 // were more like ObjectMonitor we could use PlatformEvent in both (with some 201 // API updates of course). But Parker methods use fastpaths that break that 202 // level of encapsulation - so combining the two remains a future project. 203 204 class PlatformParker : public CHeapObj<mtInternal> { 205 protected: 206 enum { 207 REL_INDEX = 0, 208 ABS_INDEX = 1 209 }; 210 int _cur_index; // which cond is in use: -1, 0, 1 211 pthread_mutex_t _mutex[1]; 212 pthread_cond_t _cond[2]; // one for relative times and one for absolute 213 214 public: // TODO-FIXME: make dtor private 215 ~PlatformParker() { guarantee(false, "invariant"); } 216 217 public: 218 PlatformParker(); 219 }; 220 221 #endif // !SOLARIS 222 223 #endif // OS_POSIX_VM_OS_POSIX_HPP