1/*
2 * Copyright (c) 1999, 2017, 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
31static const char* file_separator() { return "/"; }
32static const char* line_separator() { return "\n"; }
33static const char* path_separator() { return ":"; }
34
35class Posix {
36  friend class os;
37
38protected:
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
55public:
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
68  // Helper function, returns a string (e.g. "SIGILL") for a signal.
69  // Returned string is a constant. For unknown signals "UNKNOWN" is returned.
70  static const char* get_signal_name(int sig, char* out, size_t outlen);
71
72  // Helper function, returns a signal number for a given signal name, e.g. 11
73  // for "SIGSEGV". Name can be given with or without "SIG" prefix, so both
74  // "SEGV" or "SIGSEGV" work. Name must be uppercase.
75  // Returns -1 for an unknown signal name.
76  static int get_signal_number(const char* signal_name);
77
78  // Returns one-line short description of a signal set in a user provided buffer.
79  static const char* describe_signal_set_short(const sigset_t* set, char* buffer, size_t size);
80
81  // Prints a short one-line description of a signal set.
82  static void print_signal_set_short(outputStream* st, const sigset_t* set);
83
84  // unblocks the signal masks for current thread
85  static int unblock_thread_signal_mask(const sigset_t *set);
86
87  // Writes a one-line description of a combination of sigaction.sa_flags
88  // into a user provided buffer. Returns that buffer.
89  static const char* describe_sa_flags(int flags, char* buffer, size_t size);
90
91  // Prints a one-line description of a combination of sigaction.sa_flags.
92  static void print_sa_flags(outputStream* st, int flags);
93
94  static address ucontext_get_pc(const ucontext_t* ctx);
95  // Set PC into context. Needed for continuation after signal.
96  static void ucontext_set_pc(ucontext_t* ctx, address pc);
97
98  // Helper function; describes pthread attributes as short string. String is written
99  // to buf with len buflen; buf is returned.
100  static char* describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr);
101
102  // A safe implementation of realpath which will not cause a buffer overflow if the resolved path
103  //   is longer than PATH_MAX.
104  // On success, returns 'outbuf', which now contains the path.
105  // On error, it will return NULL and set errno. The content of 'outbuf' is undefined.
106  // On truncation error ('outbuf' too small), it will return NULL and set errno to ENAMETOOLONG.
107  static char* realpath(const char* filename, char* outbuf, size_t outbuflen);
108};
109
110// On POSIX platforms the signal handler is global so we just do the write.
111static void write_memory_serialize_page_with_handler(JavaThread* thread) {
112  write_memory_serialize_page(thread);
113}
114
115/*
116 * Crash protection for the watcher thread. Wrap the callback
117 * with a sigsetjmp and in case of a SIGSEGV/SIGBUS we siglongjmp
118 * back.
119 * To be able to use this - don't take locks, don't rely on destructors,
120 * don't make OS library calls, don't allocate memory, don't print,
121 * don't call code that could leave the heap / memory in an inconsistent state,
122 * or anything else where we are not in control if we suddenly jump out.
123 */
124class ThreadCrashProtection : public StackObj {
125public:
126  static bool is_crash_protected(Thread* thr) {
127    return _crash_protection != NULL && _protected_thread == thr;
128  }
129
130  ThreadCrashProtection();
131  bool call(os::CrashProtectionCallback& cb);
132
133  static void check_crash_protection(int signal, Thread* thread);
134private:
135  static Thread* _protected_thread;
136  static ThreadCrashProtection* _crash_protection;
137  static volatile intptr_t _crash_mux;
138  void restore();
139  sigjmp_buf _jmpbuf;
140};
141
142#ifndef SOLARIS
143
144/*
145 * This is the platform-specific implementation underpinning
146 * the ParkEvent class, which itself underpins Java-level monitor
147 * operations. See park.hpp for details.
148 * These event objects are type-stable and immortal - we never delete them.
149 * Events are associated with a thread for the lifetime of the thread.
150 */
151class PlatformEvent : public CHeapObj<mtInternal> {
152 private:
153  double cachePad[4];        // Increase odds that _mutex is sole occupant of cache line
154  volatile int _event;       // Event count/permit: -1, 0 or 1
155  volatile int _nParked;     // Indicates if associated thread is blocked: 0 or 1
156  pthread_mutex_t _mutex[1]; // Native mutex for locking
157  pthread_cond_t  _cond[1];  // Native condition variable for blocking
158  double postPad[2];
159
160 protected:       // TODO-FIXME: make dtor private
161  ~PlatformEvent() { guarantee(false, "invariant"); } // immortal so can't delete
162
163 public:
164  PlatformEvent();
165  void park();
166  int  park(jlong millis);
167  void unpark();
168
169  // Use caution with reset() and fired() -- they may require MEMBARs
170  void reset() { _event = 0; }
171  int  fired() { return _event; }
172};
173
174// JSR166 support
175// PlatformParker provides the platform dependent base class for the
176// Parker class. It basically provides the internal data structures:
177// - mutex and convars
178// which are then used directly by the Parker methods defined in the OS
179// specific implementation files.
180// There is significant overlap between the funcionality supported in the
181// combination of Parker+PlatformParker and PlatformEvent (above). If Parker
182// were more like ObjectMonitor we could use PlatformEvent in both (with some
183// API updates of course). But Parker methods use fastpaths that break that
184// level of encapsulation - so combining the two remains a future project.
185
186class PlatformParker : public CHeapObj<mtInternal> {
187 protected:
188  enum {
189    REL_INDEX = 0,
190    ABS_INDEX = 1
191  };
192  int _cur_index;  // which cond is in use: -1, 0, 1
193  pthread_mutex_t _mutex[1];
194  pthread_cond_t  _cond[2]; // one for relative times and one for absolute
195
196 public:       // TODO-FIXME: make dtor private
197  ~PlatformParker() { guarantee(false, "invariant"); }
198
199 public:
200  PlatformParker();
201};
202
203#endif // !SOLARIS
204
205#endif // OS_POSIX_VM_OS_POSIX_HPP
206