1 /*
   2  * Copyright (c) 1999, 2011, 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 // no precompiled headers
  26 #include "assembler_sparc.inline.hpp"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "code/vtableStubs.hpp"
  32 #include "interpreter/interpreter.hpp"
  33 #include "jvm_linux.h"
  34 #include "memory/allocation.inline.hpp"
  35 #include "mutex_linux.inline.hpp"
  36 #include "nativeInst_sparc.hpp"
  37 #include "os_share_linux.hpp"
  38 #include "prims/jniFastGetField.hpp"
  39 #include "prims/jvm.h"
  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.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/timer.hpp"
  52 #include "thread_linux.inline.hpp"
  53 #include "utilities/events.hpp"
  54 #include "utilities/vmError.hpp"
  55 #ifdef COMPILER1
  56 #include "c1/c1_Runtime1.hpp"
  57 #endif
  58 #ifdef COMPILER2
  59 #include "opto/runtime.hpp"
  60 #endif
  61 
  62 
  63 // Linux/Sparc has rather obscure naming of registers in sigcontext
  64 // different between 32 and 64 bits
  65 #ifdef _LP64
  66 #define SIG_PC(x) ((x)->sigc_regs.tpc)
  67 #define SIG_NPC(x) ((x)->sigc_regs.tnpc)
  68 #define SIG_REGS(x) ((x)->sigc_regs)
  69 #else
  70 #define SIG_PC(x) ((x)->si_regs.pc)
  71 #define SIG_NPC(x) ((x)->si_regs.npc)
  72 #define SIG_REGS(x) ((x)->si_regs)
  73 #endif
  74 
  75 // those are to reference registers in sigcontext
  76 enum {
  77   CON_G0 = 0,
  78   CON_G1,
  79   CON_G2,
  80   CON_G3,
  81   CON_G4,
  82   CON_G5,
  83   CON_G6,
  84   CON_G7,
  85   CON_O0,
  86   CON_O1,
  87   CON_O2,
  88   CON_O3,
  89   CON_O4,
  90   CON_O5,
  91   CON_O6,
  92   CON_O7,
  93 };
  94 
  95 static inline void set_cont_address(sigcontext* ctx, address addr) {
  96   SIG_PC(ctx)  = (intptr_t)addr;
  97   SIG_NPC(ctx) = (intptr_t)(addr+4);
  98 }
  99 
 100 // For Forte Analyzer AsyncGetCallTrace profiling support - thread is
 101 // currently interrupted by SIGPROF.
 102 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested
 103 // signal frames. Currently we don't do that on Linux, so it's the
 104 // same as os::fetch_frame_from_context().
 105 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
 106                                                 ucontext_t* uc,
 107                                                 intptr_t** ret_sp,
 108                                                 intptr_t** ret_fp) {
 109   assert(thread != NULL, "just checking");
 110   assert(ret_sp != NULL, "just checking");
 111   assert(ret_fp != NULL, "just checking");
 112 
 113   return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
 114 }
 115 
 116 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
 117                                         intptr_t** ret_sp,
 118                                         intptr_t** ret_fp) {
 119   ucontext_t* uc = (ucontext_t*) ucVoid;
 120   ExtendedPC  epc;
 121 
 122   if (uc != NULL) {
 123     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
 124     if (ret_sp) {
 125       *ret_sp = os::Linux::ucontext_get_sp(uc);
 126     }
 127     if (ret_fp) {
 128       *ret_fp = os::Linux::ucontext_get_fp(uc);
 129     }
 130   } else {
 131     // construct empty ExtendedPC for return value checking
 132     epc = ExtendedPC(NULL);
 133     if (ret_sp) {
 134       *ret_sp = (intptr_t*) NULL;
 135     }
 136     if (ret_fp) {
 137       *ret_fp = (intptr_t*) NULL;
 138     }
 139   }
 140 
 141   return epc;
 142 }
 143 
 144 frame os::fetch_frame_from_context(void* ucVoid) {
 145   intptr_t* sp;
 146   intptr_t* fp;
 147   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 148   return frame(sp, fp, epc.pc());
 149 }
 150 
 151 frame os::get_sender_for_C_frame(frame* fr) {
 152   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
 153 }
 154 
 155 frame os::current_frame() {
 156   fprintf(stderr, "current_frame()");
 157 
 158   intptr_t* sp = StubRoutines::Sparc::flush_callers_register_windows_func()();
 159   frame myframe(sp, frame::unpatchable,
 160                 CAST_FROM_FN_PTR(address, os::current_frame));
 161   if (os::is_first_C_frame(&myframe)) {
 162     // stack is not walkable
 163     return frame(NULL, frame::unpatchable, NULL);
 164   } else {
 165     return os::get_sender_for_C_frame(&myframe);
 166   }
 167 }
 168 
 169 address os::current_stack_pointer() {
 170   register void *sp __asm__ ("sp");
 171   return (address)sp;
 172 }
 173 
 174 static void current_stack_region(address* bottom, size_t* size) {
 175   if (os::Linux::is_initial_thread()) {
 176     // initial thread needs special handling because pthread_getattr_np()
 177     // may return bogus value.
 178     *bottom = os::Linux::initial_thread_stack_bottom();
 179     *size = os::Linux::initial_thread_stack_size();
 180   } else {
 181     pthread_attr_t attr;
 182 
 183     int rslt = pthread_getattr_np(pthread_self(), &attr);
 184 
 185     // JVM needs to know exact stack location, abort if it fails
 186     if (rslt != 0) {
 187       if (rslt == ENOMEM) {
 188         vm_exit_out_of_memory(0, "pthread_getattr_np");
 189       } else {
 190         fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt));
 191       }
 192     }
 193 
 194     if (pthread_attr_getstack(&attr, (void**)bottom, size) != 0) {
 195       fatal("Can not locate current stack attributes!");
 196     }
 197 
 198     pthread_attr_destroy(&attr);
 199   }
 200   assert(os::current_stack_pointer() >= *bottom &&
 201          os::current_stack_pointer() < *bottom + *size, "just checking");
 202 }
 203 
 204 address os::current_stack_base() {
 205   address bottom;
 206   size_t size;
 207   current_stack_region(&bottom, &size);
 208   return bottom + size;
 209 }
 210 
 211 size_t os::current_stack_size() {
 212   // stack size includes normal stack and HotSpot guard pages
 213   address bottom;
 214   size_t size;
 215   current_stack_region(&bottom, &size);
 216   return size;
 217 }
 218 
 219 char* os::non_memory_address_word() {
 220   // Must never look like an address returned by reserve_memory,
 221   // even in its subfields (as defined by the CPU immediate fields,
 222   // if the CPU splits constants across multiple instructions).
 223   // On SPARC, 0 != %hi(any real address), because there is no
 224   // allocation in the first 1Kb of the virtual address space.
 225   return (char*) 0;
 226 }
 227 
 228 void os::initialize_thread(Thread* thr) {}
 229 
 230 void os::print_context(outputStream *st, void *context) {
 231   if (context == NULL) return;
 232 
 233   ucontext_t* uc = (ucontext_t*)context;
 234   sigcontext* sc = (sigcontext*)context;
 235   st->print_cr("Registers:");
 236 
 237   st->print_cr(" G1=" INTPTR_FORMAT " G2=" INTPTR_FORMAT
 238                " G3=" INTPTR_FORMAT " G4=" INTPTR_FORMAT,
 239                SIG_REGS(sc).u_regs[CON_G1],
 240                SIG_REGS(sc).u_regs[CON_G2],
 241                SIG_REGS(sc).u_regs[CON_G3],
 242                SIG_REGS(sc).u_regs[CON_G4]);
 243   st->print_cr(" G5=" INTPTR_FORMAT " G6=" INTPTR_FORMAT
 244                " G7=" INTPTR_FORMAT " Y=" INTPTR_FORMAT,
 245                SIG_REGS(sc).u_regs[CON_G5],
 246                SIG_REGS(sc).u_regs[CON_G6],
 247                SIG_REGS(sc).u_regs[CON_G7],
 248                SIG_REGS(sc).y);
 249   st->print_cr(" O0=" INTPTR_FORMAT " O1=" INTPTR_FORMAT
 250                " O2=" INTPTR_FORMAT " O3=" INTPTR_FORMAT,
 251                SIG_REGS(sc).u_regs[CON_O0],
 252                SIG_REGS(sc).u_regs[CON_O1],
 253                SIG_REGS(sc).u_regs[CON_O2],
 254                SIG_REGS(sc).u_regs[CON_O3]);
 255   st->print_cr(" O4=" INTPTR_FORMAT " O5=" INTPTR_FORMAT
 256                " O6=" INTPTR_FORMAT " O7=" INTPTR_FORMAT,
 257                SIG_REGS(sc).u_regs[CON_O4],
 258                SIG_REGS(sc).u_regs[CON_O5],
 259                SIG_REGS(sc).u_regs[CON_O6],
 260                SIG_REGS(sc).u_regs[CON_O7]);
 261 
 262 
 263   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 264   st->print_cr(" L0=" INTPTR_FORMAT " L1=" INTPTR_FORMAT
 265                " L2=" INTPTR_FORMAT " L3=" INTPTR_FORMAT,
 266                sp[L0->sp_offset_in_saved_window()],
 267                sp[L1->sp_offset_in_saved_window()],
 268                sp[L2->sp_offset_in_saved_window()],
 269                sp[L3->sp_offset_in_saved_window()]);
 270   st->print_cr(" L4=" INTPTR_FORMAT " L5=" INTPTR_FORMAT
 271                " L6=" INTPTR_FORMAT " L7=" INTPTR_FORMAT,
 272                sp[L4->sp_offset_in_saved_window()],
 273                sp[L5->sp_offset_in_saved_window()],
 274                sp[L6->sp_offset_in_saved_window()],
 275                sp[L7->sp_offset_in_saved_window()]);
 276   st->print_cr(" I0=" INTPTR_FORMAT " I1=" INTPTR_FORMAT
 277                " I2=" INTPTR_FORMAT " I3=" INTPTR_FORMAT,
 278                sp[I0->sp_offset_in_saved_window()],
 279                sp[I1->sp_offset_in_saved_window()],
 280                sp[I2->sp_offset_in_saved_window()],
 281                sp[I3->sp_offset_in_saved_window()]);
 282   st->print_cr(" I4=" INTPTR_FORMAT " I5=" INTPTR_FORMAT
 283                " I6=" INTPTR_FORMAT " I7=" INTPTR_FORMAT,
 284                sp[I4->sp_offset_in_saved_window()],
 285                sp[I5->sp_offset_in_saved_window()],
 286                sp[I6->sp_offset_in_saved_window()],
 287                sp[I7->sp_offset_in_saved_window()]);
 288 
 289   st->print_cr(" PC=" INTPTR_FORMAT " nPC=" INTPTR_FORMAT,
 290                SIG_PC(sc),
 291                SIG_NPC(sc));
 292   st->cr();
 293   st->cr();
 294 
 295   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
 296   print_hex_dump(st, (address)sp, (address)(sp + 32), sizeof(intptr_t));
 297   st->cr();
 298 
 299   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 300   // point to garbage if entry point in an nmethod is corrupted. Leave
 301   // this at the end, and hope for the best.
 302   address pc = os::Linux::ucontext_get_pc(uc);
 303   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
 304   print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
 305 }
 306 
 307 
 308 void os::print_register_info(outputStream *st, void *context) {
 309   if (context == NULL) return;
 310 
 311   ucontext_t *uc = (ucontext_t*)context;
 312   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 313 
 314   st->print_cr("Register to memory mapping:");
 315   st->cr();
 316 
 317   // this is only for the "general purpose" registers
 318   st->print("G1="); print_location(st, SIG_REGS(sc).u_regs[CON__G1]);
 319   st->print("G2="); print_location(st, SIG_REGS(sc).u_regs[CON__G2]);
 320   st->print("G3="); print_location(st, SIG_REGS(sc).u_regs[CON__G3]);
 321   st->print("G4="); print_location(st, SIG_REGS(sc).u_regs[CON__G4]);
 322   st->print("G5="); print_location(st, SIG_REGS(sc).u_regs[CON__G5]);
 323   st->print("G6="); print_location(st, SIG_REGS(sc).u_regs[CON__G6]);
 324   st->print("G7="); print_location(st, SIG_REGS(sc).u_regs[CON__G7]);
 325   st->cr();
 326 
 327   st->print("O0="); print_location(st, SIG_REGS(sc).u_regs[CON__O0]);
 328   st->print("O1="); print_location(st, SIG_REGS(sc).u_regs[CON__O1]);
 329   st->print("O2="); print_location(st, SIG_REGS(sc).u_regs[CON__O2]);
 330   st->print("O3="); print_location(st, SIG_REGS(sc).u_regs[CON__O3]);
 331   st->print("O4="); print_location(st, SIG_REGS(sc).u_regs[CON__O4]);
 332   st->print("O5="); print_location(st, SIG_REGS(sc).u_regs[CON__O5]);
 333   st->print("O6="); print_location(st, SIG_REGS(sc).u_regs[CON__O6]);
 334   st->print("O7="); print_location(st, SIG_REGS(sc).u_regs[CON__O7]);
 335   st->cr();
 336 
 337   st->print("L0="); print_location(st, sp[L0->sp_offset_in_saved_window()]);
 338   st->print("L1="); print_location(st, sp[L1->sp_offset_in_saved_window()]);
 339   st->print("L2="); print_location(st, sp[L2->sp_offset_in_saved_window()]);
 340   st->print("L3="); print_location(st, sp[L3->sp_offset_in_saved_window()]);
 341   st->print("L4="); print_location(st, sp[L4->sp_offset_in_saved_window()]);
 342   st->print("L5="); print_location(st, sp[L5->sp_offset_in_saved_window()]);
 343   st->print("L6="); print_location(st, sp[L6->sp_offset_in_saved_window()]);
 344   st->print("L7="); print_location(st, sp[L7->sp_offset_in_saved_window()]);
 345   st->cr();
 346 
 347   st->print("I0="); print_location(st, sp[I0->sp_offset_in_saved_window()]);
 348   st->print("I1="); print_location(st, sp[I1->sp_offset_in_saved_window()]);
 349   st->print("I2="); print_location(st, sp[I2->sp_offset_in_saved_window()]);
 350   st->print("I3="); print_location(st, sp[I3->sp_offset_in_saved_window()]);
 351   st->print("I4="); print_location(st, sp[I4->sp_offset_in_saved_window()]);
 352   st->print("I5="); print_location(st, sp[I5->sp_offset_in_saved_window()]);
 353   st->print("I6="); print_location(st, sp[I6->sp_offset_in_saved_window()]);
 354   st->print("I7="); print_location(st, sp[I7->sp_offset_in_saved_window()]);
 355   st->cr();
 356 }
 357 
 358 
 359 address os::Linux::ucontext_get_pc(ucontext_t* uc) {
 360   return (address) SIG_PC((sigcontext*)uc);
 361 }
 362 
 363 intptr_t* os::Linux::ucontext_get_sp(ucontext_t *uc) {
 364   return (intptr_t*)
 365     ((intptr_t)SIG_REGS((sigcontext*)uc).u_regs[CON_O6] + STACK_BIAS);
 366 }
 367 
 368 // not used on Sparc
 369 intptr_t* os::Linux::ucontext_get_fp(ucontext_t *uc) {
 370   ShouldNotReachHere();
 371   return NULL;
 372 }
 373 
 374 // Utility functions
 375 
 376 extern "C" void Fetch32PFI();
 377 extern "C" void Fetch32Resume();
 378 extern "C" void FetchNPFI();
 379 extern "C" void FetchNResume();
 380 
 381 inline static bool checkPrefetch(sigcontext* uc, address pc) {
 382   if (pc == (address) Fetch32PFI) {
 383     set_cont_address(uc, address(Fetch32Resume));
 384     return true;
 385   }
 386   if (pc == (address) FetchNPFI) {
 387     set_cont_address(uc, address(FetchNResume));
 388     return true;
 389   }
 390   return false;
 391 }
 392 
 393 inline static bool checkOverflow(sigcontext* uc,
 394                                  address pc,
 395                                  address addr,
 396                                  JavaThread* thread,
 397                                  address* stub) {
 398   // check if fault address is within thread stack
 399   if (addr < thread->stack_base() &&
 400       addr >= thread->stack_base() - thread->stack_size()) {
 401     // stack overflow
 402     if (thread->in_stack_yellow_zone(addr)) {
 403       thread->disable_stack_yellow_zone();
 404       if (thread->thread_state() == _thread_in_Java) {
 405         // Throw a stack overflow exception.  Guard pages will be reenabled
 406         // while unwinding the stack.
 407         *stub =
 408           SharedRuntime::continuation_for_implicit_exception(thread,
 409                                                              pc,
 410                                                              SharedRuntime::STACK_OVERFLOW);
 411       } else {
 412         // Thread was in the vm or native code.  Return and try to finish.
 413         return true;
 414       }
 415     } else if (thread->in_stack_red_zone(addr)) {
 416       // Fatal red zone violation.  Disable the guard pages and fall through
 417       // to handle_unexpected_exception way down below.
 418       thread->disable_stack_red_zone();
 419       tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 420     } else {
 421       // Accessing stack address below sp may cause SEGV if current
 422       // thread has MAP_GROWSDOWN stack. This should only happen when
 423       // current thread was created by user code with MAP_GROWSDOWN flag
 424       // and then attached to VM. See notes in os_linux.cpp.
 425       if (thread->osthread()->expanding_stack() == 0) {
 426         thread->osthread()->set_expanding_stack();
 427         if (os::Linux::manually_expand_stack(thread, addr)) {
 428           thread->osthread()->clear_expanding_stack();
 429           return true;
 430         }
 431         thread->osthread()->clear_expanding_stack();
 432       } else {
 433         fatal("recursive segv. expanding stack.");
 434       }
 435     }
 436   }
 437   return false;
 438 }
 439 
 440 inline static bool checkPollingPage(address pc, address fault, address* stub) {
 441   if (fault == os::get_polling_page()) {
 442     *stub = SharedRuntime::get_poll_stub(pc);
 443     return true;
 444   }
 445   return false;
 446 }
 447 
 448 inline static bool checkByteBuffer(address pc, address* stub) {
 449   // BugId 4454115: A read from a MappedByteBuffer can fault
 450   // here if the underlying file has been truncated.
 451   // Do not crash the VM in such a case.
 452   CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 453   nmethod* nm = cb->is_nmethod() ? (nmethod*)cb : NULL;
 454   if (nm != NULL && nm->has_unsafe_access()) {
 455     *stub = StubRoutines::handler_for_unsafe_access();
 456     return true;
 457   }
 458   return false;
 459 }
 460 
 461 inline static bool checkVerifyOops(address pc, address fault, address* stub) {
 462   if (pc >= MacroAssembler::_verify_oop_implicit_branch[0]
 463       && pc <  MacroAssembler::_verify_oop_implicit_branch[1] ) {
 464     *stub     =  MacroAssembler::_verify_oop_implicit_branch[2];
 465     warning("fixed up memory fault in +VerifyOops at address "
 466             INTPTR_FORMAT, fault);
 467     return true;
 468   }
 469   return false;
 470 }
 471 
 472 inline static bool checkFPFault(address pc, int code,
 473                                 JavaThread* thread, address* stub) {
 474   if (code == FPE_INTDIV || code == FPE_FLTDIV) {
 475     *stub =
 476       SharedRuntime::
 477       continuation_for_implicit_exception(thread,
 478                                           pc,
 479                                           SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 480     return true;
 481   }
 482   return false;
 483 }
 484 
 485 inline static bool checkNullPointer(address pc, intptr_t fault,
 486                                     JavaThread* thread, address* stub) {
 487   if (!MacroAssembler::needs_explicit_null_check(fault)) {
 488     // Determination of interpreter/vtable stub/compiled code null
 489     // exception
 490     *stub =
 491       SharedRuntime::
 492       continuation_for_implicit_exception(thread, pc,
 493                                           SharedRuntime::IMPLICIT_NULL);
 494     return true;
 495   }
 496   return false;
 497 }
 498 
 499 inline static bool checkFastJNIAccess(address pc, address* stub) {
 500   address addr = JNI_FastGetField::find_slowcase_pc(pc);
 501   if (addr != (address)-1) {
 502     *stub = addr;
 503     return true;
 504   }
 505   return false;
 506 }
 507 
 508 inline static bool checkSerializePage(JavaThread* thread, address addr) {
 509   return os::is_memory_serialize_page(thread, addr);
 510 }
 511 
 512 inline static bool checkZombie(sigcontext* uc, address* pc, address* stub) {
 513   if (nativeInstruction_at(*pc)->is_zombie()) {
 514     // zombie method (ld [%g0],%o7 instruction)
 515     *stub = SharedRuntime::get_handle_wrong_method_stub();
 516 
 517     // At the stub it needs to look like a call from the caller of this
 518     // method (not a call from the segv site).
 519     *pc = (address)SIG_REGS(uc).u_regs[CON_O7];
 520     return true;
 521   }
 522   return false;
 523 }
 524 
 525 inline static bool checkICMiss(sigcontext* uc, address* pc, address* stub) {
 526 #ifdef COMPILER2
 527   if (nativeInstruction_at(*pc)->is_ic_miss_trap()) {
 528 #ifdef ASSERT
 529 #ifdef TIERED
 530     CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 531     assert(cb->is_compiled_by_c2(), "Wrong compiler");
 532 #endif // TIERED
 533 #endif // ASSERT
 534     // Inline cache missed and user trap "Tne G0+ST_RESERVED_FOR_USER_0+2" taken.
 535     *stub = SharedRuntime::get_ic_miss_stub();
 536     // At the stub it needs to look like a call from the caller of this
 537     // method (not a call from the segv site).
 538     *pc = (address)SIG_REGS(uc).u_regs[CON_O7];
 539     return true;
 540   }
 541 #endif  // COMPILER2
 542   return false;
 543 }
 544 
 545 extern "C" JNIEXPORT int
 546 JVM_handle_linux_signal(int sig,
 547                         siginfo_t* info,
 548                         void* ucVoid,
 549                         int abort_if_unrecognized) {
 550   // in fact this isn't ucontext_t* at all, but struct sigcontext*
 551   // but Linux porting layer uses ucontext_t, so to minimize code change
 552   // we cast as needed
 553   ucontext_t* ucFake = (ucontext_t*) ucVoid;
 554   sigcontext* uc = (sigcontext*)ucVoid;
 555 
 556   Thread* t = ThreadLocalStorage::get_thread_slow();
 557 
 558   SignalHandlerMark shm(t);
 559 
 560   // Note: it's not uncommon that JNI code uses signal/sigset to install
 561   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 562   // or have a SIGILL handler when detecting CPU type). When that happens,
 563   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
 564   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 565   // that do not require siginfo/ucontext first.
 566 
 567   if (sig == SIGPIPE || sig == SIGXFSZ) {
 568     // allow chained handler to go first
 569     if (os::Linux::chained_handler(sig, info, ucVoid)) {
 570       return true;
 571     } else {
 572       if (PrintMiscellaneous && (WizardMode || Verbose)) {
 573         char buf[64];
 574         warning("Ignoring %s - see bugs 4229104 or 646499219",
 575                 os::exception_name(sig, buf, sizeof(buf)));
 576       }
 577       return true;
 578     }
 579   }
 580 
 581   JavaThread* thread = NULL;
 582   VMThread* vmthread = NULL;
 583   if (os::Linux::signal_handlers_are_installed) {
 584     if (t != NULL ){
 585       if(t->is_Java_thread()) {
 586         thread = (JavaThread*)t;
 587       }
 588       else if(t->is_VM_thread()){
 589         vmthread = (VMThread *)t;
 590       }
 591     }
 592   }
 593 
 594   // decide if this trap can be handled by a stub
 595   address stub = NULL;
 596   address pc = NULL;
 597   address npc = NULL;
 598 
 599   //%note os_trap_1
 600   if (info != NULL && uc != NULL && thread != NULL) {
 601     pc = address(SIG_PC(uc));
 602     npc = address(SIG_NPC(uc));
 603 
 604     // Check to see if we caught the safepoint code in the
 605     // process of write protecting the memory serialization page.
 606     // It write enables the page immediately after protecting it
 607     // so we can just return to retry the write.
 608     if ((sig == SIGSEGV) && checkSerializePage(thread, (address)info->si_addr)) {
 609       // Block current thread until the memory serialize page permission restored.
 610       os::block_on_serialize_page_trap();
 611       return 1;
 612     }
 613 
 614     if (checkPrefetch(uc, pc)) {
 615       return 1;
 616     }
 617 
 618     // Handle ALL stack overflow variations here
 619     if (sig == SIGSEGV) {
 620       if (checkOverflow(uc, pc, (address)info->si_addr, thread, &stub)) {
 621         return 1;
 622       }
 623     }
 624 
 625     if (sig == SIGBUS &&
 626         thread->thread_state() == _thread_in_vm &&
 627         thread->doing_unsafe_access()) {
 628       stub = StubRoutines::handler_for_unsafe_access();
 629     }
 630 
 631     if (thread->thread_state() == _thread_in_Java) {
 632       do {
 633         // Java thread running in Java code => find exception handler if any
 634         // a fault inside compiled code, the interpreter, or a stub
 635 
 636         if ((sig == SIGSEGV) && checkPollingPage(pc, (address)info->si_addr, &stub)) {
 637           break;
 638         }
 639 
 640         if ((sig == SIGBUS) && checkByteBuffer(pc, &stub)) {
 641           break;
 642         }
 643 
 644         if ((sig == SIGSEGV || sig == SIGBUS) &&
 645             checkVerifyOops(pc, (address)info->si_addr, &stub)) {
 646           break;
 647         }
 648 
 649         if ((sig == SIGSEGV) && checkZombie(uc, &pc, &stub)) {
 650           break;
 651         }
 652 
 653         if ((sig == SIGILL) && checkICMiss(uc, &pc, &stub)) {
 654           break;
 655         }
 656 
 657         if ((sig == SIGFPE) && checkFPFault(pc, info->si_code, thread, &stub)) {
 658           break;
 659         }
 660 
 661         if ((sig == SIGSEGV) &&
 662             checkNullPointer(pc, (intptr_t)info->si_addr, thread, &stub)) {
 663           break;
 664         }
 665       } while (0);
 666 
 667       // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
 668       // and the heap gets shrunk before the field access.
 669       if ((sig == SIGSEGV) || (sig == SIGBUS)) {
 670         checkFastJNIAccess(pc, &stub);
 671       }
 672     }
 673 
 674     if (stub != NULL) {
 675       // save all thread context in case we need to restore it
 676       thread->set_saved_exception_pc(pc);
 677       thread->set_saved_exception_npc(npc);
 678       set_cont_address(uc, stub);
 679       return true;
 680     }
 681   }
 682 
 683   // signal-chaining
 684   if (os::Linux::chained_handler(sig, info, ucVoid)) {
 685     return true;
 686   }
 687 
 688   if (!abort_if_unrecognized) {
 689     // caller wants another chance, so give it to him
 690     return false;
 691   }
 692 
 693   if (pc == NULL && uc != NULL) {
 694     pc = os::Linux::ucontext_get_pc((ucontext_t*)uc);
 695   }
 696 
 697   // unmask current signal
 698   sigset_t newset;
 699   sigemptyset(&newset);
 700   sigaddset(&newset, sig);
 701   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 702 
 703   VMError err(t, sig, pc, info, ucVoid);
 704   err.report_and_die();
 705 
 706   ShouldNotReachHere();
 707 }
 708 
 709 void os::Linux::init_thread_fpu_state(void) {
 710   // Nothing to do
 711 }
 712 
 713 int os::Linux::get_fpu_control_word() {
 714   return 0;
 715 }
 716 
 717 void os::Linux::set_fpu_control_word(int fpu) {
 718   // nothing
 719 }
 720 
 721 bool os::is_allocatable(size_t bytes) {
 722 #ifdef _LP64
 723   return true;
 724 #else
 725   if (bytes < 2 * G) {
 726     return true;
 727   }
 728 
 729   char* addr = reserve_memory(bytes, NULL);
 730 
 731   if (addr != NULL) {
 732     release_memory(addr, bytes);
 733   }
 734 
 735   return addr != NULL;
 736 #endif // _LP64
 737 }
 738 
 739 ///////////////////////////////////////////////////////////////////////////////
 740 // thread stack
 741 
 742 size_t os::Linux::min_stack_allowed  = 128 * K;
 743 
 744 // pthread on Ubuntu is always in floating stack mode
 745 bool os::Linux::supports_variable_stack_size() {  return true; }
 746 
 747 // return default stack size for thr_type
 748 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
 749   // default stack size (compiler thread needs larger stack)
 750   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
 751   return s;
 752 }
 753 
 754 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
 755   // Creating guard page is very expensive. Java thread has HotSpot
 756   // guard page, only enable glibc guard page for non-Java threads.
 757   return (thr_type == java_thread ? 0 : page_size());
 758 }
 759 
 760 #ifndef PRODUCT
 761 void os::verify_stack_alignment() {
 762 }
 763 #endif