1 /*
  2  * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
  3  * Copyright (c) 2014, Red Hat Inc. All rights reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 // no precompiled headers
 27 #include "jvm.h"
 28 #include "asm/macroAssembler.hpp"
 29 #include "classfile/classLoader.hpp"
 30 #include "classfile/systemDictionary.hpp"
 31 #include "classfile/vmSymbols.hpp"
 32 #include "code/codeCache.hpp"
 33 #include "code/icBuffer.hpp"
 34 #include "code/vtableStubs.hpp"
 35 #include "code/nativeInst.hpp"
 36 #include "interpreter/interpreter.hpp"
 37 #include "memory/allocation.inline.hpp"
 38 #include "os_share_linux.hpp"
 39 #include "prims/jniFastGetField.hpp"
 40 #include "prims/jvm_misc.hpp"
 41 #include "runtime/arguments.hpp"
 42 #include "runtime/extendedPC.hpp"
 43 #include "runtime/frame.inline.hpp"
 44 #include "runtime/interfaceSupport.inline.hpp"
 45 #include "runtime/java.hpp"
 46 #include "runtime/javaCalls.hpp"
 47 #include "runtime/mutexLocker.hpp"
 48 #include "runtime/osThread.hpp"
 49 #include "runtime/sharedRuntime.hpp"
 50 #include "runtime/stubRoutines.hpp"
 51 #include "runtime/thread.inline.hpp"
 52 #include "runtime/timer.hpp"
 53 #include "utilities/debug.hpp"
 54 #include "utilities/events.hpp"
 55 #include "utilities/vmError.hpp"
 56 #ifdef BUILTIN_SIM
 57 #include "../../../../../../simulator/simulator.hpp"
 58 #endif
 59 
 60 // put OS-includes here
 61 # include <sys/types.h>
 62 # include <sys/mman.h>
 63 # include <pthread.h>
 64 # include <signal.h>
 65 # include <errno.h>
 66 # include <dlfcn.h>
 67 # include <stdlib.h>
 68 # include <stdio.h>
 69 # include <unistd.h>
 70 # include <sys/resource.h>
 71 # include <pthread.h>
 72 # include <sys/stat.h>
 73 # include <sys/time.h>
 74 # include <sys/utsname.h>
 75 # include <sys/socket.h>
 76 # include <sys/wait.h>
 77 # include <pwd.h>
 78 # include <poll.h>
 79 # include <ucontext.h>
 80 # include <fpu_control.h>
 81 
 82 #ifdef BUILTIN_SIM
 83 #define REG_SP REG_RSP
 84 #define REG_PC REG_RIP
 85 #define REG_FP REG_RBP
 86 #define SPELL_REG_SP "rsp"
 87 #define SPELL_REG_FP "rbp"
 88 #else
 89 #define REG_FP 29
 90 #define REG_LR 30
 91 
 92 #define SPELL_REG_SP "sp"
 93 #define SPELL_REG_FP "x29"
 94 #endif
 95 
 96 address os::current_stack_pointer() {
 97   register void *esp __asm__ (SPELL_REG_SP);
 98   return (address) esp;
 99 }
100 
101 char* os::non_memory_address_word() {
102   // Must never look like an address returned by reserve_memory,
103   // even in its subfields (as defined by the CPU immediate fields,
104   // if the CPU splits constants across multiple instructions).
105 
106   return (char*) 0xffffffffffff;
107 }
108 
109 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
110 #ifdef BUILTIN_SIM
111   return (address)uc->uc_mcontext.gregs[REG_PC];
112 #else
113   return (address)uc->uc_mcontext.pc;
114 #endif
115 }
116 
117 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
118 #ifdef BUILTIN_SIM
119   uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
120 #else
121   uc->uc_mcontext.pc = (intptr_t)pc;
122 #endif
123 }
124 
125 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
126 #ifdef BUILTIN_SIM
127   return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
128 #else
129   return (intptr_t*)uc->uc_mcontext.sp;
130 #endif
131 }
132 
133 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
134 #ifdef BUILTIN_SIM
135   return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
136 #else
137   return (intptr_t*)uc->uc_mcontext.regs[REG_FP];
138 #endif
139 }
140 
141 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
142 // is currently interrupted by SIGPROF.
143 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
144 // frames. Currently we don't do that on Linux, so it's the same as
145 // os::fetch_frame_from_context().
146 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
147   const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
148 
149   assert(thread != NULL, "just checking");
150   assert(ret_sp != NULL, "just checking");
151   assert(ret_fp != NULL, "just checking");
152 
153   return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
154 }
155 
156 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
157                     intptr_t** ret_sp, intptr_t** ret_fp) {
158 
159   ExtendedPC  epc;
160   const ucontext_t* uc = (const ucontext_t*)ucVoid;
161 
162   if (uc != NULL) {
163     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
164     if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
165     if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
166   } else {
167     // construct empty ExtendedPC for return value checking
168     epc = ExtendedPC(NULL);
169     if (ret_sp) *ret_sp = (intptr_t *)NULL;
170     if (ret_fp) *ret_fp = (intptr_t *)NULL;
171   }
172 
173   return epc;
174 }
175 
176 frame os::fetch_frame_from_context(const void* ucVoid) {
177   intptr_t* sp;
178   intptr_t* fp;
179   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
180   return frame(sp, fp, epc.pc());
181 }
182 
183 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
184   address pc = (address) os::Linux::ucontext_get_pc(uc);
185   if (Interpreter::contains(pc)) {
186     // interpreter performs stack banging after the fixed frame header has
187     // been generated while the compilers perform it before. To maintain
188     // semantic consistency between interpreted and compiled frames, the
189     // method returns the Java sender of the current frame.
190     *fr = os::fetch_frame_from_context(uc);
191     if (!fr->is_first_java_frame()) {
192       assert(fr->safe_for_sender(thread), "Safety check");
193       *fr = fr->java_sender();
194     }
195   } else {
196     // more complex code with compiled code
197     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
198     CodeBlob* cb = CodeCache::find_blob(pc);
199     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
200       // Not sure where the pc points to, fallback to default
201       // stack overflow handling
202       return false;
203     } else {
204       // In compiled code, the stack banging is performed before LR
205       // has been saved in the frame.  LR is live, and SP and FP
206       // belong to the caller.
207       intptr_t* fp = os::Linux::ucontext_get_fp(uc);
208       intptr_t* sp = os::Linux::ucontext_get_sp(uc);
209       address pc = (address)(uc->uc_mcontext.regs[REG_LR]
210                          - NativeInstruction::instruction_size);
211       *fr = frame(sp, fp, pc);
212       if (!fr->is_java_frame()) {
213         assert(fr->safe_for_sender(thread), "Safety check");
214         assert(!fr->is_first_frame(), "Safety check");
215         *fr = fr->java_sender();
216       }
217     }
218   }
219   assert(fr->is_java_frame(), "Safety check");
220   return true;
221 }
222 
223 // By default, gcc always saves frame pointer rfp on this stack. This
224 // may get turned off by -fomit-frame-pointer.
225 frame os::get_sender_for_C_frame(frame* fr) {
226 #ifdef BUILTIN_SIM
227   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
228 #else
229   return frame(fr->link(), fr->link(), fr->sender_pc());
230 #endif
231 }
232 
233 intptr_t* _get_previous_fp() {
234   register intptr_t **fp __asm__ (SPELL_REG_FP);
235 
236   // fp is for this frame (_get_previous_fp). We want the fp for the
237   // caller of os::current_frame*(), so go up two frames. However, for
238   // optimized builds, _get_previous_fp() will be inlined, so only go
239   // up 1 frame in that case.
240   #ifdef _NMT_NOINLINE_
241     return **(intptr_t***)fp;
242   #else
243     return *fp;
244   #endif
245 }
246 
247 
248 frame os::current_frame() {
249   intptr_t* fp = _get_previous_fp();
250   frame myframe((intptr_t*)os::current_stack_pointer(),
251                 (intptr_t*)fp,
252                 CAST_FROM_FN_PTR(address, os::current_frame));
253   if (os::is_first_C_frame(&myframe)) {
254     // stack is not walkable
255     return frame();
256   } else {
257     return os::get_sender_for_C_frame(&myframe);
258   }
259 }
260 
261 // Utility functions
262 
263 // From IA32 System Programming Guide
264 enum {
265   trap_page_fault = 0xE
266 };
267 
268 #ifdef BUILTIN_SIM
269 extern "C" void Fetch32PFI () ;
270 extern "C" void Fetch32Resume () ;
271 extern "C" void FetchNPFI () ;
272 extern "C" void FetchNResume () ;
273 #endif
274 
275 extern "C" JNIEXPORT int
276 JVM_handle_linux_signal(int sig,
277                         siginfo_t* info,
278                         void* ucVoid,
279                         int abort_if_unrecognized) {
280   ucontext_t* uc = (ucontext_t*) ucVoid;
281 
282   Thread* t = Thread::current_or_null_safe();
283 
284   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
285   // (no destructors can be run)
286   os::ThreadCrashProtection::check_crash_protection(sig, t);
287 
288   SignalHandlerMark shm(t);
289 
290   // Note: it's not uncommon that JNI code uses signal/sigset to install
291   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
292   // or have a SIGILL handler when detecting CPU type). When that happens,
293   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
294   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
295   // that do not require siginfo/ucontext first.
296 
297   if (sig == SIGPIPE || sig == SIGXFSZ) {
298     // allow chained handler to go first
299     if (os::Linux::chained_handler(sig, info, ucVoid)) {
300       return true;
301     } else {
302       // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219
303       return true;
304     }
305   }
306 
307 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
308   if ((sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) {
309     handle_assert_poison_fault(ucVoid, info->si_addr);
310     return 1;
311   }
312 #endif
313 
314   JavaThread* thread = NULL;
315   VMThread* vmthread = NULL;
316   if (os::Linux::signal_handlers_are_installed) {
317     if (t != NULL ){
318       if(t->is_Java_thread()) {
319         thread = (JavaThread*)t;
320       }
321       else if(t->is_VM_thread()){
322         vmthread = (VMThread *)t;
323       }
324     }
325   }
326 /*
327   NOTE: does not seem to work on linux.
328   if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
329     // can't decode this kind of signal
330     info = NULL;
331   } else {
332     assert(sig == info->si_signo, "bad siginfo");
333   }
334 */
335   // decide if this trap can be handled by a stub
336   address stub = NULL;
337 
338   address pc          = NULL;
339 
340   //%note os_trap_1
341   if (info != NULL && uc != NULL && thread != NULL) {
342     pc = (address) os::Linux::ucontext_get_pc(uc);
343 
344 #ifdef BUILTIN_SIM
345     if (pc == (address) Fetch32PFI) {
346        uc->uc_mcontext.gregs[REG_PC] = intptr_t(Fetch32Resume) ;
347        return 1 ;
348     }
349     if (pc == (address) FetchNPFI) {
350        uc->uc_mcontext.gregs[REG_PC] = intptr_t (FetchNResume) ;
351        return 1 ;
352     }
353 #else
354     if (StubRoutines::is_safefetch_fault(pc)) {
355       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
356       return 1;
357     }
358 #endif
359 
360     address addr = (address) info->si_addr;
361 
362     // Make sure the high order byte is sign extended, as it may be masked away by the hardware.
363     if ((uintptr_t(addr) & (uintptr_t(1) << 55)) != 0) {
364       addr = address(uintptr_t(addr) | (uintptr_t(0xFF) << 56));
365     }
366 
367     // Handle ALL stack overflow variations here
368     if (sig == SIGSEGV) {
369       // check if fault address is within thread stack
370       if (thread->on_local_stack(addr)) {
371         // stack overflow
372         if (thread->in_stack_yellow_reserved_zone(addr)) {
373           thread->disable_stack_yellow_reserved_zone();
374           if (thread->thread_state() == _thread_in_Java) {
375             if (thread->in_stack_reserved_zone(addr)) {
376               frame fr;
377               if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
378                 assert(fr.is_java_frame(), "Must be a Java frame");
379                 frame activation =
380                   SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
381                 if (activation.sp() != NULL) {
382                   thread->disable_stack_reserved_zone();
383                   if (activation.is_interpreted_frame()) {
384                     thread->set_reserved_stack_activation((address)(
385                       activation.fp() + frame::interpreter_frame_initial_sp_offset));
386                   } else {
387                     thread->set_reserved_stack_activation((address)activation.unextended_sp());
388                   }
389                   return 1;
390                 }
391               }
392             }
393             // Throw a stack overflow exception.  Guard pages will be reenabled
394             // while unwinding the stack.
395             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
396           } else {
397             // Thread was in the vm or native code.  Return and try to finish.
398             return 1;
399           }
400         } else if (thread->in_stack_red_zone(addr)) {
401           // Fatal red zone violation.  Disable the guard pages and fall through
402           // to handle_unexpected_exception way down below.
403           thread->disable_stack_red_zone();
404           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
405 
406           // This is a likely cause, but hard to verify. Let's just print
407           // it as a hint.
408           tty->print_raw_cr("Please check if any of your loaded .so files has "
409                             "enabled executable stack (see man page execstack(8))");
410         } else {
411           // Accessing stack address below sp may cause SEGV if current
412           // thread has MAP_GROWSDOWN stack. This should only happen when
413           // current thread was created by user code with MAP_GROWSDOWN flag
414           // and then attached to VM. See notes in os_linux.cpp.
415           if (thread->osthread()->expanding_stack() == 0) {
416              thread->osthread()->set_expanding_stack();
417              if (os::Linux::manually_expand_stack(thread, addr)) {
418                thread->osthread()->clear_expanding_stack();
419                return 1;
420              }
421              thread->osthread()->clear_expanding_stack();
422           } else {
423              fatal("recursive segv. expanding stack.");
424           }
425         }
426       }
427     }
428 
429     if (thread->thread_state() == _thread_in_Java) {
430       // Java thread running in Java code => find exception handler if any
431       // a fault inside compiled code, the interpreter, or a stub
432 
433       // Handle signal from NativeJump::patch_verified_entry().
434       if ((sig == SIGILL || sig == SIGTRAP)
435           && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {
436         if (TraceTraps) {
437           tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
438         }
439         stub = SharedRuntime::get_handle_wrong_method_stub();
440       } else if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
441         stub = SharedRuntime::get_poll_stub(pc);
442       } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
443         // BugId 4454115: A read from a MappedByteBuffer can fault
444         // here if the underlying file has been truncated.
445         // Do not crash the VM in such a case.
446         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
447         CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
448         if (nm != NULL && nm->has_unsafe_access()) {
449           address next_pc = pc + NativeCall::instruction_size;
450           stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
451         }
452       }
453       else
454 
455       if (sig == SIGFPE  &&
456           (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
457         stub =
458           SharedRuntime::
459           continuation_for_implicit_exception(thread,
460                                               pc,
461                                               SharedRuntime::
462                                               IMPLICIT_DIVIDE_BY_ZERO);
463       } else if (sig == SIGSEGV &&
464                  MacroAssembler::uses_implicit_null_check(info->si_addr)) {
465           // Determination of interpreter/vtable stub/compiled code null exception
466           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
467       }
468     } else if (thread->thread_state() == _thread_in_vm &&
469                sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
470                thread->doing_unsafe_access()) {
471       address next_pc = pc + NativeCall::instruction_size;
472       stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
473     }
474 
475     // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
476     // and the heap gets shrunk before the field access.
477     if ((sig == SIGSEGV) || (sig == SIGBUS)) {
478       address addr = JNI_FastGetField::find_slowcase_pc(pc);
479       if (addr != (address)-1) {
480         stub = addr;
481       }
482     }
483 
484     // Check to see if we caught the safepoint code in the
485     // process of write protecting the memory serialization page.
486     // It write enables the page immediately after protecting it
487     // so we can just return to retry the write.
488     if ((sig == SIGSEGV) &&
489         os::is_memory_serialize_page(thread, (address) info->si_addr)) {
490       // Block current thread until the memory serialize page permission restored.
491       os::block_on_serialize_page_trap();
492       return true;
493     }
494   }
495 
496   if (stub != NULL) {
497     // save all thread context in case we need to restore it
498     if (thread != NULL) thread->set_saved_exception_pc(pc);
499 
500     os::Linux::ucontext_set_pc(uc, stub);
501     return true;
502   }
503 
504   // signal-chaining
505   if (os::Linux::chained_handler(sig, info, ucVoid)) {
506      return true;
507   }
508 
509   if (!abort_if_unrecognized) {
510     // caller wants another chance, so give it to him
511     return false;
512   }
513 
514   if (pc == NULL && uc != NULL) {
515     pc = os::Linux::ucontext_get_pc(uc);
516   }
517 
518   // unmask current signal
519   sigset_t newset;
520   sigemptyset(&newset);
521   sigaddset(&newset, sig);
522   sigprocmask(SIG_UNBLOCK, &newset, NULL);
523 
524   VMError::report_and_die(t, sig, pc, info, ucVoid);
525 
526   ShouldNotReachHere();
527   return true; // Mute compiler
528 }
529 
530 void os::Linux::init_thread_fpu_state(void) {
531 }
532 
533 int os::Linux::get_fpu_control_word(void) {
534   return 0;
535 }
536 
537 void os::Linux::set_fpu_control_word(int fpu_control) {
538 }
539 
540 // Check that the linux kernel version is 2.4 or higher since earlier
541 // versions do not support SSE without patches.
542 bool os::supports_sse() {
543   return true;
544 }
545 
546 bool os::is_allocatable(size_t bytes) {
547   return true;
548 }
549 
550 ////////////////////////////////////////////////////////////////////////////////
551 // thread stack
552 
553 // Minimum usable stack sizes required to get to user code. Space for
554 // HotSpot guard pages is added later.
555 size_t os::Posix::_compiler_thread_min_stack_allowed = 72 * K;
556 size_t os::Posix::_java_thread_min_stack_allowed = 72 * K;
557 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 72 * K;
558 
559 // return default stack size for thr_type
560 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
561   // default stack size (compiler thread needs larger stack)
562   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
563   return s;
564 }
565 
566 /////////////////////////////////////////////////////////////////////////////
567 // helper functions for fatal error handler
568 
569 void os::print_context(outputStream *st, const void *context) {
570   if (context == NULL) return;
571 
572   const ucontext_t *uc = (const ucontext_t*)context;
573   st->print_cr("Registers:");
574 #ifdef BUILTIN_SIM
575   st->print(  "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]);
576   st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]);
577   st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]);
578   st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]);
579   st->cr();
580   st->print(  "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]);
581   st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]);
582   st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]);
583   st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]);
584   st->cr();
585   st->print(  "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]);
586   st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]);
587   st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]);
588   st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]);
589   st->cr();
590   st->print(  "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]);
591   st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]);
592   st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]);
593   st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]);
594   st->cr();
595   st->print(  "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]);
596   st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
597   st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]);
598   st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]);
599   st->cr();
600   st->print("  TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]);
601   st->cr();
602 #else
603   for (int r = 0; r < 31; r++) {
604     st->print("R%-2d=", r);
605     print_location(st, uc->uc_mcontext.regs[r]);
606   }
607 #endif
608   st->cr();
609 
610   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
611   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
612   print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
613   st->cr();
614 
615   // Note: it may be unsafe to inspect memory near pc. For example, pc may
616   // point to garbage if entry point in an nmethod is corrupted. Leave
617   // this at the end, and hope for the best.
618   address pc = os::Linux::ucontext_get_pc(uc);
619   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
620   print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
621 }
622 
623 void os::print_register_info(outputStream *st, const void *context) {
624   if (context == NULL) return;
625 
626   const ucontext_t *uc = (const ucontext_t*)context;
627 
628   st->print_cr("Register to memory mapping:");
629   st->cr();
630 
631   // this is horrendously verbose but the layout of the registers in the
632   // context does not match how we defined our abstract Register set, so
633   // we can't just iterate through the gregs area
634 
635   // this is only for the "general purpose" registers
636 
637 #ifdef BUILTIN_SIM
638   st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
639   st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
640   st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
641   st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
642   st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
643   st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
644   st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
645   st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
646   st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
647   st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
648   st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
649   st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
650   st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
651   st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
652   st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
653   st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
654 #else
655   for (int r = 0; r < 31; r++)
656     st->print_cr(  "R%d=" INTPTR_FORMAT, r, (uintptr_t)uc->uc_mcontext.regs[r]);
657 #endif
658   st->cr();
659 }
660 
661 void os::setup_fpu() {
662 }
663 
664 #ifndef PRODUCT
665 void os::verify_stack_alignment() {
666   assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
667 }
668 #endif
669 
670 int os::extra_bang_size_in_bytes() {
671   // AArch64 does not require the additional stack bang.
672   return 0;
673 }
674 
675 extern "C" {
676   int SpinPause() {
677     return 0;
678   }
679 
680   void _Copy_conjoint_jshorts_atomic(jshort* from, jshort* to, size_t count) {
681     if (from > to) {
682       jshort *end = from + count;
683       while (from < end)
684         *(to++) = *(from++);
685     }
686     else if (from < to) {
687       jshort *end = from;
688       from += count - 1;
689       to   += count - 1;
690       while (from >= end)
691         *(to--) = *(from--);
692     }
693   }
694   void _Copy_conjoint_jints_atomic(jint* from, jint* to, size_t count) {
695     if (from > to) {
696       jint *end = from + count;
697       while (from < end)
698         *(to++) = *(from++);
699     }
700     else if (from < to) {
701       jint *end = from;
702       from += count - 1;
703       to   += count - 1;
704       while (from >= end)
705         *(to--) = *(from--);
706     }
707   }
708   void _Copy_conjoint_jlongs_atomic(jlong* from, jlong* to, size_t count) {
709     if (from > to) {
710       jlong *end = from + count;
711       while (from < end)
712         os::atomic_copy64(from++, to++);
713     }
714     else if (from < to) {
715       jlong *end = from;
716       from += count - 1;
717       to   += count - 1;
718       while (from >= end)
719         os::atomic_copy64(from--, to--);
720     }
721   }
722 
723   void _Copy_arrayof_conjoint_bytes(HeapWord* from,
724                                     HeapWord* to,
725                                     size_t    count) {
726     memmove(to, from, count);
727   }
728   void _Copy_arrayof_conjoint_jshorts(HeapWord* from,
729                                       HeapWord* to,
730                                       size_t    count) {
731     memmove(to, from, count * 2);
732   }
733   void _Copy_arrayof_conjoint_jints(HeapWord* from,
734                                     HeapWord* to,
735                                     size_t    count) {
736     memmove(to, from, count * 4);
737   }
738   void _Copy_arrayof_conjoint_jlongs(HeapWord* from,
739                                      HeapWord* to,
740                                      size_t    count) {
741     memmove(to, from, count * 8);
742   }
743 };