1 /*
   2  * Copyright 1999-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // do not include  precompiled  header file
  26 # include "incls/_os_solaris_x86.cpp.incl"
  27 
  28 // put OS-includes here
  29 # include <sys/types.h>
  30 # include <sys/mman.h>
  31 # include <pthread.h>
  32 # include <signal.h>
  33 # include <setjmp.h>
  34 # include <errno.h>
  35 # include <dlfcn.h>
  36 # include <stdio.h>
  37 # include <unistd.h>
  38 # include <sys/resource.h>
  39 # include <thread.h>
  40 # include <sys/stat.h>
  41 # include <sys/time.h>
  42 # include <sys/filio.h>
  43 # include <sys/utsname.h>
  44 # include <sys/systeminfo.h>
  45 # include <sys/socket.h>
  46 # include <sys/trap.h>
  47 # include <sys/lwp.h>
  48 # include <pwd.h>
  49 # include <poll.h>
  50 # include <sys/lwp.h>
  51 # include <procfs.h>     //  see comment in <sys/procfs.h>
  52 
  53 #ifndef AMD64
  54 // QQQ seems useless at this point
  55 # define _STRUCTURED_PROC 1  //  this gets us the new structured proc interfaces of 5.6 & later
  56 #endif // AMD64
  57 # include <sys/procfs.h>     //  see comment in <sys/procfs.h>
  58 
  59 
  60 #define MAX_PATH (2 * K)
  61 
  62 // Minimum stack size for the VM.  It's easier to document a constant value
  63 // but it's different for x86 and sparc because the page sizes are different.
  64 #ifdef AMD64
  65 size_t os::Solaris::min_stack_allowed = 224*K;
  66 #define REG_SP REG_RSP
  67 #define REG_PC REG_RIP
  68 #define REG_FP REG_RBP
  69 #else
  70 size_t os::Solaris::min_stack_allowed = 64*K;
  71 #define REG_SP UESP
  72 #define REG_PC EIP
  73 #define REG_FP EBP
  74 // 4900493 counter to prevent runaway LDTR refresh attempt
  75 
  76 static volatile int ldtr_refresh = 0;
  77 // the libthread instruction that faults because of the stale LDTR
  78 
  79 static const unsigned char movlfs[] = { 0x8e, 0xe0    // movl %eax,%fs
  80                        };
  81 #endif // AMD64
  82 
  83 char* os::non_memory_address_word() {
  84   // Must never look like an address returned by reserve_memory,
  85   // even in its subfields (as defined by the CPU immediate fields,
  86   // if the CPU splits constants across multiple instructions).
  87   return (char*) -1;
  88 }
  89 
  90 //
  91 // Validate a ucontext retrieved from walking a uc_link of a ucontext.
  92 // There are issues with libthread giving out uc_links for different threads
  93 // on the same uc_link chain and bad or circular links.
  94 //
  95 bool os::Solaris::valid_ucontext(Thread* thread, ucontext_t* valid, ucontext_t* suspect) {
  96   if (valid >= suspect ||
  97       valid->uc_stack.ss_flags != suspect->uc_stack.ss_flags ||
  98       valid->uc_stack.ss_sp    != suspect->uc_stack.ss_sp    ||
  99       valid->uc_stack.ss_size  != suspect->uc_stack.ss_size) {
 100     DEBUG_ONLY(tty->print_cr("valid_ucontext: failed test 1");)
 101     return false;
 102   }
 103 
 104   if (thread->is_Java_thread()) {
 105     if (!valid_stack_address(thread, (address)suspect)) {
 106       DEBUG_ONLY(tty->print_cr("valid_ucontext: uc_link not in thread stack");)
 107       return false;
 108     }
 109     if (!valid_stack_address(thread,  (address) suspect->uc_mcontext.gregs[REG_SP])) {
 110       DEBUG_ONLY(tty->print_cr("valid_ucontext: stackpointer not in thread stack");)
 111       return false;
 112     }
 113   }
 114   return true;
 115 }
 116 
 117 // We will only follow one level of uc_link since there are libthread
 118 // issues with ucontext linking and it is better to be safe and just
 119 // let caller retry later.
 120 ucontext_t* os::Solaris::get_valid_uc_in_signal_handler(Thread *thread,
 121   ucontext_t *uc) {
 122 
 123   ucontext_t *retuc = NULL;
 124 
 125   if (uc != NULL) {
 126     if (uc->uc_link == NULL) {
 127       // cannot validate without uc_link so accept current ucontext
 128       retuc = uc;
 129     } else if (os::Solaris::valid_ucontext(thread, uc, uc->uc_link)) {
 130       // first ucontext is valid so try the next one
 131       uc = uc->uc_link;
 132       if (uc->uc_link == NULL) {
 133         // cannot validate without uc_link so accept current ucontext
 134         retuc = uc;
 135       } else if (os::Solaris::valid_ucontext(thread, uc, uc->uc_link)) {
 136         // the ucontext one level down is also valid so return it
 137         retuc = uc;
 138       }
 139     }
 140   }
 141   return retuc;
 142 }
 143 
 144 // Assumes ucontext is valid
 145 ExtendedPC os::Solaris::ucontext_get_ExtendedPC(ucontext_t *uc) {
 146   return ExtendedPC((address)uc->uc_mcontext.gregs[REG_PC]);
 147 }
 148 
 149 // Assumes ucontext is valid
 150 intptr_t* os::Solaris::ucontext_get_sp(ucontext_t *uc) {
 151   return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
 152 }
 153 
 154 // Assumes ucontext is valid
 155 intptr_t* os::Solaris::ucontext_get_fp(ucontext_t *uc) {
 156   return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
 157 }
 158 
 159 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
 160 // is currently interrupted by SIGPROF.
 161 //
 162 // The difference between this and os::fetch_frame_from_context() is that
 163 // here we try to skip nested signal frames.
 164 ExtendedPC os::Solaris::fetch_frame_from_ucontext(Thread* thread,
 165   ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
 166 
 167   assert(thread != NULL, "just checking");
 168   assert(ret_sp != NULL, "just checking");
 169   assert(ret_fp != NULL, "just checking");
 170 
 171   ucontext_t *luc = os::Solaris::get_valid_uc_in_signal_handler(thread, uc);
 172   return os::fetch_frame_from_context(luc, ret_sp, ret_fp);
 173 }
 174 
 175 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
 176                     intptr_t** ret_sp, intptr_t** ret_fp) {
 177 
 178   ExtendedPC  epc;
 179   ucontext_t *uc = (ucontext_t*)ucVoid;
 180 
 181   if (uc != NULL) {
 182     epc = os::Solaris::ucontext_get_ExtendedPC(uc);
 183     if (ret_sp) *ret_sp = os::Solaris::ucontext_get_sp(uc);
 184     if (ret_fp) *ret_fp = os::Solaris::ucontext_get_fp(uc);
 185   } else {
 186     // construct empty ExtendedPC for return value checking
 187     epc = ExtendedPC(NULL);
 188     if (ret_sp) *ret_sp = (intptr_t *)NULL;
 189     if (ret_fp) *ret_fp = (intptr_t *)NULL;
 190   }
 191 
 192   return epc;
 193 }
 194 
 195 frame os::fetch_frame_from_context(void* ucVoid) {
 196   intptr_t* sp;
 197   intptr_t* fp;
 198   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 199   return frame(sp, fp, epc.pc());
 200 }
 201 
 202 frame os::get_sender_for_C_frame(frame* fr) {
 203   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
 204 }
 205 
 206 extern "C" intptr_t *_get_current_fp();  // in .il file
 207 
 208 frame os::current_frame() {
 209   intptr_t* fp = _get_current_fp();  // it's inlined so want current fp
 210   frame myframe((intptr_t*)os::current_stack_pointer(),
 211                 (intptr_t*)fp,
 212                 CAST_FROM_FN_PTR(address, os::current_frame));
 213   if (os::is_first_C_frame(&myframe)) {
 214     // stack is not walkable
 215     frame ret; // This will be a null useless frame
 216     return ret;
 217   } else {
 218     return os::get_sender_for_C_frame(&myframe);
 219   }
 220 }
 221 
 222 // This is a simple callback that just fetches a PC for an interrupted thread.
 223 // The thread need not be suspended and the fetched PC is just a hint.
 224 // This one is currently used for profiling the VMThread ONLY!
 225 
 226 // Must be synchronous
 227 void GetThreadPC_Callback::execute(OSThread::InterruptArguments *args) {
 228   Thread*     thread = args->thread();
 229   ucontext_t* uc     = args->ucontext();
 230   intptr_t* sp;
 231 
 232   assert(ProfileVM && thread->is_VM_thread(), "just checking");
 233 
 234   ExtendedPC new_addr((address)uc->uc_mcontext.gregs[REG_PC]);
 235   _addr = new_addr;
 236 }
 237 
 238 static int threadgetstate(thread_t tid, int *flags, lwpid_t *lwp, stack_t *ss, gregset_t rs, lwpstatus_t *lwpstatus) {
 239   char lwpstatusfile[PROCFILE_LENGTH];
 240   int lwpfd, err;
 241 
 242   if (err = os::Solaris::thr_getstate(tid, flags, lwp, ss, rs))
 243     return (err);
 244   if (*flags == TRS_LWPID) {
 245     sprintf(lwpstatusfile, "/proc/%d/lwp/%d/lwpstatus", getpid(),
 246             *lwp);
 247     if ((lwpfd = open(lwpstatusfile, O_RDONLY)) < 0) {
 248       perror("thr_mutator_status: open lwpstatus");
 249       return (EINVAL);
 250     }
 251     if (pread(lwpfd, lwpstatus, sizeof (lwpstatus_t), (off_t)0) !=
 252         sizeof (lwpstatus_t)) {
 253       perror("thr_mutator_status: read lwpstatus");
 254       (void) close(lwpfd);
 255       return (EINVAL);
 256     }
 257     (void) close(lwpfd);
 258   }
 259   return (0);
 260 }
 261 
 262 #ifndef AMD64
 263 
 264 // Detecting SSE support by OS
 265 // From solaris_i486.s
 266 extern "C" bool sse_check();
 267 extern "C" bool sse_unavailable();
 268 
 269 enum { SSE_UNKNOWN, SSE_NOT_SUPPORTED, SSE_SUPPORTED};
 270 static int sse_status = SSE_UNKNOWN;
 271 
 272 
 273 static void  check_for_sse_support() {
 274   if (!VM_Version::supports_sse()) {
 275     sse_status = SSE_NOT_SUPPORTED;
 276     return;
 277   }
 278   // looking for _sse_hw in libc.so, if it does not exist or
 279   // the value (int) is 0, OS has no support for SSE
 280   int *sse_hwp;
 281   void *h;
 282 
 283   if ((h=dlopen("/usr/lib/libc.so", RTLD_LAZY)) == NULL) {
 284     //open failed, presume no support for SSE
 285     sse_status = SSE_NOT_SUPPORTED;
 286     return;
 287   }
 288   if ((sse_hwp = (int *)dlsym(h, "_sse_hw")) == NULL) {
 289     sse_status = SSE_NOT_SUPPORTED;
 290   } else if (*sse_hwp == 0) {
 291     sse_status = SSE_NOT_SUPPORTED;
 292   }
 293   dlclose(h);
 294 
 295   if (sse_status == SSE_UNKNOWN) {
 296     bool (*try_sse)() = (bool (*)())sse_check;
 297     sse_status = (*try_sse)() ? SSE_SUPPORTED : SSE_NOT_SUPPORTED;
 298   }
 299 
 300 }
 301 
 302 #endif // AMD64
 303 
 304 bool os::supports_sse() {
 305 #ifdef AMD64
 306   return true;
 307 #else
 308   if (sse_status == SSE_UNKNOWN)
 309     check_for_sse_support();
 310   return sse_status == SSE_SUPPORTED;
 311 #endif // AMD64
 312 }
 313 
 314 bool os::is_allocatable(size_t bytes) {
 315 #ifdef AMD64
 316   return true;
 317 #else
 318 
 319   if (bytes < 2 * G) {
 320     return true;
 321   }
 322 
 323   char* addr = reserve_memory(bytes, NULL);
 324 
 325   if (addr != NULL) {
 326     release_memory(addr, bytes);
 327   }
 328 
 329   return addr != NULL;
 330 #endif // AMD64
 331 
 332 }
 333 
 334 extern "C" int JVM_handle_solaris_signal(int signo, siginfo_t* siginfo, void* ucontext, int abort_if_unrecognized);
 335 
 336 extern "C" void Fetch32PFI () ;
 337 extern "C" void Fetch32Resume () ;
 338 #ifdef AMD64
 339 extern "C" void FetchNPFI () ;
 340 extern "C" void FetchNResume () ;
 341 #endif // AMD64
 342 
 343 int JVM_handle_solaris_signal(int sig, siginfo_t* info, void* ucVoid, int abort_if_unrecognized) {
 344   ucontext_t* uc = (ucontext_t*) ucVoid;
 345 
 346 #ifndef AMD64
 347   if (sig == SIGILL && info->si_addr == (caddr_t)sse_check) {
 348     // the SSE instruction faulted. supports_sse() need return false.
 349     uc->uc_mcontext.gregs[EIP] = (greg_t)sse_unavailable;
 350     return true;
 351   }
 352 #endif // !AMD64
 353 
 354   Thread* t = ThreadLocalStorage::get_thread_slow();  // slow & steady
 355 
 356   SignalHandlerMark shm(t);
 357 
 358   if(sig == SIGPIPE || sig == SIGXFSZ) {
 359     if (os::Solaris::chained_handler(sig, info, ucVoid)) {
 360       return true;
 361     } else {
 362       if (PrintMiscellaneous && (WizardMode || Verbose)) {
 363         char buf[64];
 364         warning("Ignoring %s - see 4229104 or 6499219",
 365                 os::exception_name(sig, buf, sizeof(buf)));
 366 
 367       }
 368       return true;
 369     }
 370   }
 371 
 372   JavaThread* thread = NULL;
 373   VMThread* vmthread = NULL;
 374 
 375   if (os::Solaris::signal_handlers_are_installed) {
 376     if (t != NULL ){
 377       if(t->is_Java_thread()) {
 378         thread = (JavaThread*)t;
 379       }
 380       else if(t->is_VM_thread()){
 381         vmthread = (VMThread *)t;
 382       }
 383     }
 384   }
 385 
 386   guarantee(sig != os::Solaris::SIGinterrupt(), "Can not chain VM interrupt signal, try -XX:+UseAltSigs");
 387 
 388   if (sig == os::Solaris::SIGasync()) {
 389     if(thread){
 390       OSThread::InterruptArguments args(thread, uc);
 391       thread->osthread()->do_interrupt_callbacks_at_interrupt(&args);
 392       return true;
 393     }
 394     else if(vmthread){
 395       OSThread::InterruptArguments args(vmthread, uc);
 396       vmthread->osthread()->do_interrupt_callbacks_at_interrupt(&args);
 397       return true;
 398     } else if (os::Solaris::chained_handler(sig, info, ucVoid)) {
 399       return true;
 400     } else {
 401       // If os::Solaris::SIGasync not chained, and this is a non-vm and
 402       // non-java thread
 403       return true;
 404     }
 405   }
 406 
 407   if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
 408     // can't decode this kind of signal
 409     info = NULL;
 410   } else {
 411     assert(sig == info->si_signo, "bad siginfo");
 412   }
 413 
 414   // decide if this trap can be handled by a stub
 415   address stub = NULL;
 416 
 417   address pc          = NULL;
 418 
 419   //%note os_trap_1
 420   if (info != NULL && uc != NULL && thread != NULL) {
 421     // factor me: getPCfromContext
 422     pc = (address) uc->uc_mcontext.gregs[REG_PC];
 423 
 424     // SafeFetch32() support
 425     if (pc == (address) Fetch32PFI) {
 426       uc->uc_mcontext.gregs[REG_PC] = intptr_t(Fetch32Resume) ;
 427       return true ;
 428     }
 429 #ifdef AMD64
 430     if (pc == (address) FetchNPFI) {
 431        uc->uc_mcontext.gregs [REG_PC] = intptr_t(FetchNResume) ;
 432        return true ;
 433     }
 434 #endif // AMD64
 435 
 436     // Handle ALL stack overflow variations here
 437     if (sig == SIGSEGV && info->si_code == SEGV_ACCERR) {
 438       address addr = (address) info->si_addr;
 439       if (thread->in_stack_yellow_zone(addr)) {
 440         thread->disable_stack_yellow_zone();
 441         if (thread->thread_state() == _thread_in_Java) {
 442           // Throw a stack overflow exception.  Guard pages will be reenabled
 443           // while unwinding the stack.
 444           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
 445         } else {
 446           // Thread was in the vm or native code.  Return and try to finish.
 447           return true;
 448         }
 449       } else if (thread->in_stack_red_zone(addr)) {
 450         // Fatal red zone violation.  Disable the guard pages and fall through
 451         // to handle_unexpected_exception way down below.
 452         thread->disable_stack_red_zone();
 453         tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 454       }
 455     }
 456 
 457     if (thread->thread_state() == _thread_in_vm) {
 458       if (sig == SIGBUS && info->si_code == BUS_OBJERR && thread->doing_unsafe_access()) {
 459         stub = StubRoutines::handler_for_unsafe_access();
 460       }
 461     }
 462 
 463     if (thread->thread_state() == _thread_in_Java) {
 464       // Support Safepoint Polling
 465       if ( sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
 466         stub = SharedRuntime::get_poll_stub(pc);
 467       }
 468       else if (sig == SIGBUS && info->si_code == BUS_OBJERR) {
 469         // BugId 4454115: A read from a MappedByteBuffer can fault
 470         // here if the underlying file has been truncated.
 471         // Do not crash the VM in such a case.
 472         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 473         nmethod* nm = cb->is_nmethod() ? (nmethod*)cb : NULL;
 474         if (nm != NULL && nm->has_unsafe_access()) {
 475           stub = StubRoutines::handler_for_unsafe_access();
 476         }
 477       }
 478       else
 479       if (sig == SIGFPE && info->si_code == FPE_INTDIV) {
 480         // integer divide by zero
 481         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 482       }
 483 #ifndef AMD64
 484       else if (sig == SIGFPE && info->si_code == FPE_FLTDIV) {
 485         // floating-point divide by zero
 486         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 487       }
 488       else if (sig == SIGFPE && info->si_code == FPE_FLTINV) {
 489         // The encoding of D2I in i486.ad can cause an exception prior
 490         // to the fist instruction if there was an invalid operation
 491         // pending. We want to dismiss that exception. From the win_32
 492         // side it also seems that if it really was the fist causing
 493         // the exception that we do the d2i by hand with different
 494         // rounding. Seems kind of weird. QQQ TODO
 495         // Note that we take the exception at the NEXT floating point instruction.
 496         if (pc[0] == 0xDB) {
 497             assert(pc[0] == 0xDB, "not a FIST opcode");
 498             assert(pc[1] == 0x14, "not a FIST opcode");
 499             assert(pc[2] == 0x24, "not a FIST opcode");
 500             return true;
 501         } else {
 502             assert(pc[-3] == 0xDB, "not an flt invalid opcode");
 503             assert(pc[-2] == 0x14, "not an flt invalid opcode");
 504             assert(pc[-1] == 0x24, "not an flt invalid opcode");
 505         }
 506       }
 507       else if (sig == SIGFPE ) {
 508         tty->print_cr("caught SIGFPE, info 0x%x.", info->si_code);
 509       }
 510 #endif // !AMD64
 511 
 512         // QQQ It doesn't seem that we need to do this on x86 because we should be able
 513         // to return properly from the handler without this extra stuff on the back side.
 514 
 515       else if (sig == SIGSEGV && info->si_code > 0 && !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
 516         // Determination of interpreter/vtable stub/compiled code null exception
 517         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 518       }
 519     }
 520 
 521     // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
 522     // and the heap gets shrunk before the field access.
 523     if ((sig == SIGSEGV) || (sig == SIGBUS)) {
 524       address addr = JNI_FastGetField::find_slowcase_pc(pc);
 525       if (addr != (address)-1) {
 526         stub = addr;
 527       }
 528     }
 529 
 530     // Check to see if we caught the safepoint code in the
 531     // process of write protecting the memory serialization page.
 532     // It write enables the page immediately after protecting it
 533     // so we can just return to retry the write.
 534     if ((sig == SIGSEGV) &&
 535         os::is_memory_serialize_page(thread, (address)info->si_addr)) {
 536       // Block current thread until the memory serialize page permission restored.
 537       os::block_on_serialize_page_trap();
 538       return true;
 539     }
 540   }
 541 
 542   // Execution protection violation
 543   //
 544   // Preventative code for future versions of Solaris which may
 545   // enable execution protection when running the 32-bit VM on AMD64.
 546   //
 547   // This should be kept as the last step in the triage.  We don't
 548   // have a dedicated trap number for a no-execute fault, so be
 549   // conservative and allow other handlers the first shot.
 550   //
 551   // Note: We don't test that info->si_code == SEGV_ACCERR here.
 552   // this si_code is so generic that it is almost meaningless; and
 553   // the si_code for this condition may change in the future.
 554   // Furthermore, a false-positive should be harmless.
 555   if (UnguardOnExecutionViolation > 0 &&
 556       (sig == SIGSEGV || sig == SIGBUS) &&
 557       uc->uc_mcontext.gregs[TRAPNO] == T_PGFLT) {  // page fault
 558     int page_size = os::vm_page_size();
 559     address addr = (address) info->si_addr;
 560     address pc = (address) uc->uc_mcontext.gregs[REG_PC];
 561     // Make sure the pc and the faulting address are sane.
 562     //
 563     // If an instruction spans a page boundary, and the page containing
 564     // the beginning of the instruction is executable but the following
 565     // page is not, the pc and the faulting address might be slightly
 566     // different - we still want to unguard the 2nd page in this case.
 567     //
 568     // 15 bytes seems to be a (very) safe value for max instruction size.
 569     bool pc_is_near_addr =
 570       (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
 571     bool instr_spans_page_boundary =
 572       (align_size_down((intptr_t) pc ^ (intptr_t) addr,
 573                        (intptr_t) page_size) > 0);
 574 
 575     if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
 576       static volatile address last_addr =
 577         (address) os::non_memory_address_word();
 578 
 579       // In conservative mode, don't unguard unless the address is in the VM
 580       if (addr != last_addr &&
 581           (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
 582 
 583         // Make memory rwx and retry
 584         address page_start =
 585           (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
 586         bool res = os::protect_memory((char*) page_start, page_size,
 587                                       os::MEM_PROT_RWX);
 588 
 589         if (PrintMiscellaneous && Verbose) {
 590           char buf[256];
 591           jio_snprintf(buf, sizeof(buf), "Execution protection violation "
 592                        "at " INTPTR_FORMAT
 593                        ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
 594                        page_start, (res ? "success" : "failed"), errno);
 595           tty->print_raw_cr(buf);
 596         }
 597         stub = pc;
 598 
 599         // Set last_addr so if we fault again at the same address, we don't end
 600         // up in an endless loop.
 601         //
 602         // There are two potential complications here.  Two threads trapping at
 603         // the same address at the same time could cause one of the threads to
 604         // think it already unguarded, and abort the VM.  Likely very rare.
 605         //
 606         // The other race involves two threads alternately trapping at
 607         // different addresses and failing to unguard the page, resulting in
 608         // an endless loop.  This condition is probably even more unlikely than
 609         // the first.
 610         //
 611         // Although both cases could be avoided by using locks or thread local
 612         // last_addr, these solutions are unnecessary complication: this
 613         // handler is a best-effort safety net, not a complete solution.  It is
 614         // disabled by default and should only be used as a workaround in case
 615         // we missed any no-execute-unsafe VM code.
 616 
 617         last_addr = addr;
 618       }
 619     }
 620   }
 621 
 622   if (stub != NULL) {
 623     // save all thread context in case we need to restore it
 624 
 625     if (thread != NULL) thread->set_saved_exception_pc(pc);
 626     // 12/02/99: On Sparc it appears that the full context is also saved
 627     // but as yet, no one looks at or restores that saved context
 628     // factor me: setPC
 629     uc->uc_mcontext.gregs[REG_PC] = (greg_t)stub;
 630     return true;
 631   }
 632 
 633   // signal-chaining
 634   if (os::Solaris::chained_handler(sig, info, ucVoid)) {
 635     return true;
 636   }
 637 
 638 #ifndef AMD64
 639   // Workaround (bug 4900493) for Solaris kernel bug 4966651.
 640   // Handle an undefined selector caused by an attempt to assign
 641   // fs in libthread getipriptr(). With the current libthread design every 512
 642   // thread creations the LDT for a private thread data structure is extended
 643   // and thre is a hazard that and another thread attempting a thread creation
 644   // will use a stale LDTR that doesn't reflect the structure's growth,
 645   // causing a GP fault.
 646   // Enforce the probable limit of passes through here to guard against an
 647   // infinite loop if some other move to fs caused the GP fault. Note that
 648   // this loop counter is ultimately a heuristic as it is possible for
 649   // more than one thread to generate this fault at a time in an MP system.
 650   // In the case of the loop count being exceeded or if the poll fails
 651   // just fall through to a fatal error.
 652   // If there is some other source of T_GPFLT traps and the text at EIP is
 653   // unreadable this code will loop infinitely until the stack is exausted.
 654   // The key to diagnosis in this case is to look for the bottom signal handler
 655   // frame.
 656 
 657   if(! IgnoreLibthreadGPFault) {
 658     if (sig == SIGSEGV && uc->uc_mcontext.gregs[TRAPNO] == T_GPFLT) {
 659       const unsigned char *p =
 660                         (unsigned const char *) uc->uc_mcontext.gregs[EIP];
 661 
 662       // Expected instruction?
 663 
 664       if(p[0] == movlfs[0] && p[1] == movlfs[1]) {
 665 
 666         Atomic::inc(&ldtr_refresh);
 667 
 668         // Infinite loop?
 669 
 670         if(ldtr_refresh < ((2 << 16) / PAGESIZE)) {
 671 
 672           // No, force scheduling to get a fresh view of the LDTR
 673 
 674           if(poll(NULL, 0, 10) == 0) {
 675 
 676             // Retry the move
 677 
 678             return false;
 679           }
 680         }
 681       }
 682     }
 683   }
 684 #endif // !AMD64
 685 
 686   if (!abort_if_unrecognized) {
 687     // caller wants another chance, so give it to him
 688     return false;
 689   }
 690 
 691   if (!os::Solaris::libjsig_is_loaded) {
 692     struct sigaction oldAct;
 693     sigaction(sig, (struct sigaction *)0, &oldAct);
 694     if (oldAct.sa_sigaction != signalHandler) {
 695       void* sighand = oldAct.sa_sigaction ? CAST_FROM_FN_PTR(void*,  oldAct.sa_sigaction)
 696                                           : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
 697       warning("Unexpected Signal %d occurred under user-defined signal handler %#lx", sig, (long)sighand);
 698     }
 699   }
 700 
 701   if (pc == NULL && uc != NULL) {
 702     pc = (address) uc->uc_mcontext.gregs[REG_PC];
 703   }
 704 
 705   // unmask current signal
 706   sigset_t newset;
 707   sigemptyset(&newset);
 708   sigaddset(&newset, sig);
 709   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 710 
 711   VMError err(t, sig, pc, info, ucVoid);
 712   err.report_and_die();
 713 
 714   ShouldNotReachHere();
 715 }
 716 
 717 void os::print_context(outputStream *st, void *context) {
 718   if (context == NULL) return;
 719 
 720   ucontext_t *uc = (ucontext_t*)context;
 721   st->print_cr("Registers:");
 722 #ifdef AMD64
 723   st->print(  "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]);
 724   st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]);
 725   st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]);
 726   st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]);
 727   st->cr();
 728   st->print(  "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]);
 729   st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]);
 730   st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]);
 731   st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]);
 732   st->cr();
 733   st->print(", R8=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]);
 734   st->print(", R9=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]);
 735   st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]);
 736   st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]);
 737   st->print(", R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]);
 738   st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]);
 739   st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]);
 740   st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]);
 741   st->cr();
 742   st->print(  "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]);
 743   st->print(", RFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RFL]);
 744 #else
 745   st->print(  "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EAX]);
 746   st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EBX]);
 747   st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[ECX]);
 748   st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EDX]);
 749   st->cr();
 750   st->print(  "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[UESP]);
 751   st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EBP]);
 752   st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[ESI]);
 753   st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EDI]);
 754   st->cr();
 755   st->print(  "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EIP]);
 756   st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[EFL]);
 757 #endif // AMD64
 758   st->cr();
 759   st->cr();
 760 
 761   intptr_t *sp = (intptr_t *)os::Solaris::ucontext_get_sp(uc);
 762   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
 763   print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
 764   st->cr();
 765 
 766   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 767   // point to garbage if entry point in an nmethod is corrupted. Leave
 768   // this at the end, and hope for the best.
 769   ExtendedPC epc = os::Solaris::ucontext_get_ExtendedPC(uc);
 770   address pc = epc.pc();
 771   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
 772   print_hex_dump(st, pc - 16, pc + 16, sizeof(char));
 773 }
 774 
 775 #ifdef AMD64
 776 void os::Solaris::init_thread_fpu_state(void) {
 777   // Nothing to do
 778 }
 779 #else
 780 // From solaris_i486.s
 781 extern "C" void fixcw();
 782 
 783 void os::Solaris::init_thread_fpu_state(void) {
 784   // Set fpu to 53 bit precision. This happens too early to use a stub.
 785   fixcw();
 786 }
 787 
 788 // These routines are the initial value of atomic_xchg_entry(),
 789 // atomic_cmpxchg_entry(), atomic_inc_entry() and fence_entry()
 790 // until initialization is complete.
 791 // TODO - replace with .il implementation when compiler supports it.
 792 
 793 typedef jint  xchg_func_t        (jint,  volatile jint*);
 794 typedef jint  cmpxchg_func_t     (jint,  volatile jint*,  jint);
 795 typedef jlong cmpxchg_long_func_t(jlong, volatile jlong*, jlong);
 796 typedef jint  add_func_t         (jint,  volatile jint*);
 797 
 798 jint os::atomic_xchg_bootstrap(jint exchange_value, volatile jint* dest) {
 799   // try to use the stub:
 800   xchg_func_t* func = CAST_TO_FN_PTR(xchg_func_t*, StubRoutines::atomic_xchg_entry());
 801 
 802   if (func != NULL) {
 803     os::atomic_xchg_func = func;
 804     return (*func)(exchange_value, dest);
 805   }
 806   assert(Threads::number_of_threads() == 0, "for bootstrap only");
 807 
 808   jint old_value = *dest;
 809   *dest = exchange_value;
 810   return old_value;
 811 }
 812 
 813 jint os::atomic_cmpxchg_bootstrap(jint exchange_value, volatile jint* dest, jint compare_value) {
 814   // try to use the stub:
 815   cmpxchg_func_t* func = CAST_TO_FN_PTR(cmpxchg_func_t*, StubRoutines::atomic_cmpxchg_entry());
 816 
 817   if (func != NULL) {
 818     os::atomic_cmpxchg_func = func;
 819     return (*func)(exchange_value, dest, compare_value);
 820   }
 821   assert(Threads::number_of_threads() == 0, "for bootstrap only");
 822 
 823   jint old_value = *dest;
 824   if (old_value == compare_value)
 825     *dest = exchange_value;
 826   return old_value;
 827 }
 828 
 829 jlong os::atomic_cmpxchg_long_bootstrap(jlong exchange_value, volatile jlong* dest, jlong compare_value) {
 830   // try to use the stub:
 831   cmpxchg_long_func_t* func = CAST_TO_FN_PTR(cmpxchg_long_func_t*, StubRoutines::atomic_cmpxchg_long_entry());
 832 
 833   if (func != NULL) {
 834     os::atomic_cmpxchg_long_func = func;
 835     return (*func)(exchange_value, dest, compare_value);
 836   }
 837   assert(Threads::number_of_threads() == 0, "for bootstrap only");
 838 
 839   jlong old_value = *dest;
 840   if (old_value == compare_value)
 841     *dest = exchange_value;
 842   return old_value;
 843 }
 844 
 845 jint os::atomic_add_bootstrap(jint add_value, volatile jint* dest) {
 846   // try to use the stub:
 847   add_func_t* func = CAST_TO_FN_PTR(add_func_t*, StubRoutines::atomic_add_entry());
 848 
 849   if (func != NULL) {
 850     os::atomic_add_func = func;
 851     return (*func)(add_value, dest);
 852   }
 853   assert(Threads::number_of_threads() == 0, "for bootstrap only");
 854 
 855   return (*dest) += add_value;
 856 }
 857 
 858 xchg_func_t*         os::atomic_xchg_func         = os::atomic_xchg_bootstrap;
 859 cmpxchg_func_t*      os::atomic_cmpxchg_func      = os::atomic_cmpxchg_bootstrap;
 860 cmpxchg_long_func_t* os::atomic_cmpxchg_long_func = os::atomic_cmpxchg_long_bootstrap;
 861 add_func_t*          os::atomic_add_func          = os::atomic_add_bootstrap;
 862 
 863 extern "C" _solaris_raw_setup_fpu(address ptr);
 864 void os::setup_fpu() {
 865   address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
 866   _solaris_raw_setup_fpu(fpu_cntrl);
 867 }
 868 #endif // AMD64