rev 12334 : 8169373: Work around linux NPTL stack guard error.
Summary: Also skip OS guard page for compiler thread, merge similar code on linux platforms, and streamline OS guard page handling on linuxs390, linuxppc, aixppc.

   1 /*
   2  * Copyright (c) 1999, 2016, 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 "asm/macroAssembler.hpp"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/icBuffer.hpp"
  32 #include "code/vtableStubs.hpp"
  33 #include "interpreter/interpreter.hpp"
  34 #include "jvm_linux.h"
  35 #include "memory/allocation.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/thread.inline.hpp"
  52 #include "runtime/timer.hpp"
  53 #include "utilities/events.hpp"
  54 #include "utilities/vmError.hpp"
  55 
  56 // Linux/Sparc has rather obscure naming of registers in sigcontext
  57 // different between 32 and 64 bits
  58 #ifdef _LP64
  59 #define SIG_PC(x) ((x)->sigc_regs.tpc)
  60 #define SIG_NPC(x) ((x)->sigc_regs.tnpc)
  61 #define SIG_REGS(x) ((x)->sigc_regs)
  62 #else
  63 #define SIG_PC(x) ((x)->si_regs.pc)
  64 #define SIG_NPC(x) ((x)->si_regs.npc)
  65 #define SIG_REGS(x) ((x)->si_regs)
  66 #endif
  67 
  68 // those are to reference registers in sigcontext
  69 enum {
  70   CON_G0 = 0,
  71   CON_G1,
  72   CON_G2,
  73   CON_G3,
  74   CON_G4,
  75   CON_G5,
  76   CON_G6,
  77   CON_G7,
  78   CON_O0,
  79   CON_O1,
  80   CON_O2,
  81   CON_O3,
  82   CON_O4,
  83   CON_O5,
  84   CON_O6,
  85   CON_O7,
  86 };
  87 
  88 // For Forte Analyzer AsyncGetCallTrace profiling support - thread is
  89 // currently interrupted by SIGPROF.
  90 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested
  91 // signal frames. Currently we don't do that on Linux, so it's the
  92 // same as os::fetch_frame_from_context().
  93 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
  94                                                 const ucontext_t* uc,
  95                                                 intptr_t** ret_sp,
  96                                                 intptr_t** ret_fp) {
  97   assert(thread != NULL, "just checking");
  98   assert(ret_sp != NULL, "just checking");
  99   assert(ret_fp != NULL, "just checking");
 100 
 101   return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
 102 }
 103 
 104 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
 105                                         intptr_t** ret_sp,
 106                                         intptr_t** ret_fp) {
 107   const ucontext_t* uc = (const ucontext_t*) ucVoid;
 108   ExtendedPC  epc;
 109 
 110   if (uc != NULL) {
 111     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
 112     if (ret_sp) {
 113       *ret_sp = os::Linux::ucontext_get_sp(uc);
 114     }
 115     if (ret_fp) {
 116       *ret_fp = (intptr_t*)NULL;
 117     }
 118   } else {
 119     // construct empty ExtendedPC for return value checking
 120     epc = ExtendedPC(NULL);
 121     if (ret_sp) {
 122       *ret_sp = (intptr_t*) NULL;
 123     }
 124     if (ret_fp) {
 125       *ret_fp = (intptr_t*) NULL;
 126     }
 127   }
 128 
 129   return epc;
 130 }
 131 
 132 frame os::fetch_frame_from_context(const void* ucVoid) {
 133   intptr_t* sp;
 134   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, NULL);
 135   return frame(sp, frame::unpatchable, epc.pc());
 136 }
 137 
 138 frame os::get_sender_for_C_frame(frame* fr) {
 139   return frame(fr->sender_sp(), frame::unpatchable, fr->sender_pc());
 140 }
 141 
 142 frame os::current_frame() {
 143   intptr_t* sp = StubRoutines::Sparc::flush_callers_register_windows_func()();
 144   frame myframe(sp, frame::unpatchable,
 145                 CAST_FROM_FN_PTR(address, os::current_frame));
 146   if (os::is_first_C_frame(&myframe)) {
 147     // stack is not walkable
 148     return frame(NULL, frame::unpatchable, NULL);
 149   } else {
 150     return os::get_sender_for_C_frame(&myframe);
 151   }
 152 }
 153 
 154 address os::current_stack_pointer() {
 155   register void *sp __asm__ ("sp");
 156   return (address)sp;
 157 }
 158 
 159 static void current_stack_region(address* bottom, size_t* size) {
 160   if (os::Linux::is_initial_thread()) {
 161     // initial thread needs special handling because pthread_getattr_np()
 162     // may return bogus value.
 163     *bottom = os::Linux::initial_thread_stack_bottom();
 164     *size = os::Linux::initial_thread_stack_size();
 165   } else {
 166     pthread_attr_t attr;
 167 
 168     int rslt = pthread_getattr_np(pthread_self(), &attr);
 169 
 170     // JVM needs to know exact stack location, abort if it fails
 171     if (rslt != 0) {
 172       if (rslt == ENOMEM) {
 173         vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
 174       } else {
 175         fatal("pthread_getattr_np failed with errno = %d", rslt);
 176       }
 177     }
 178 
 179     if (pthread_attr_getstack(&attr, (void**)bottom, size) != 0) {
 180       fatal("Can not locate current stack attributes!");
 181     }
 182 
 183     pthread_attr_destroy(&attr);
 184   }
 185   assert(os::current_stack_pointer() >= *bottom &&
 186          os::current_stack_pointer() < *bottom + *size, "just checking");
 187 }
 188 
 189 address os::current_stack_base() {
 190   address bottom;
 191   size_t size;
 192   current_stack_region(&bottom, &size);
 193   return bottom + size;
 194 }
 195 
 196 size_t os::current_stack_size() {
 197   // stack size includes normal stack and HotSpot guard pages
 198   address bottom;
 199   size_t size;
 200   current_stack_region(&bottom, &size);
 201   return size;
 202 }
 203 
 204 char* os::non_memory_address_word() {
 205   // Must never look like an address returned by reserve_memory,
 206   // even in its subfields (as defined by the CPU immediate fields,
 207   // if the CPU splits constants across multiple instructions).
 208   // On SPARC, 0 != %hi(any real address), because there is no
 209   // allocation in the first 1Kb of the virtual address space.
 210   return (char*) 0;
 211 }
 212 
 213 void os::initialize_thread(Thread* thr) {}
 214 
 215 void os::print_context(outputStream *st, const void *context) {
 216   if (context == NULL) return;
 217 
 218   const ucontext_t* uc = (const ucontext_t*)context;
 219   sigcontext* sc = (sigcontext*)context;
 220   st->print_cr("Registers:");
 221 
 222   st->print_cr(" G1=" INTPTR_FORMAT " G2=" INTPTR_FORMAT
 223                " G3=" INTPTR_FORMAT " G4=" INTPTR_FORMAT,
 224                SIG_REGS(sc).u_regs[CON_G1],
 225                SIG_REGS(sc).u_regs[CON_G2],
 226                SIG_REGS(sc).u_regs[CON_G3],
 227                SIG_REGS(sc).u_regs[CON_G4]);
 228   st->print_cr(" G5=" INTPTR_FORMAT " G6=" INTPTR_FORMAT
 229                " G7=" INTPTR_FORMAT " Y=0x%x",
 230                SIG_REGS(sc).u_regs[CON_G5],
 231                SIG_REGS(sc).u_regs[CON_G6],
 232                SIG_REGS(sc).u_regs[CON_G7],
 233                SIG_REGS(sc).y);
 234   st->print_cr(" O0=" INTPTR_FORMAT " O1=" INTPTR_FORMAT
 235                " O2=" INTPTR_FORMAT " O3=" INTPTR_FORMAT,
 236                SIG_REGS(sc).u_regs[CON_O0],
 237                SIG_REGS(sc).u_regs[CON_O1],
 238                SIG_REGS(sc).u_regs[CON_O2],
 239                SIG_REGS(sc).u_regs[CON_O3]);
 240   st->print_cr(" O4=" INTPTR_FORMAT " O5=" INTPTR_FORMAT
 241                " O6=" INTPTR_FORMAT " O7=" INTPTR_FORMAT,
 242                SIG_REGS(sc).u_regs[CON_O4],
 243                SIG_REGS(sc).u_regs[CON_O5],
 244                SIG_REGS(sc).u_regs[CON_O6],
 245                SIG_REGS(sc).u_regs[CON_O7]);
 246 
 247 
 248   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 249   st->print_cr(" L0=" INTPTR_FORMAT " L1=" INTPTR_FORMAT
 250                " L2=" INTPTR_FORMAT " L3=" INTPTR_FORMAT,
 251                sp[L0->sp_offset_in_saved_window()],
 252                sp[L1->sp_offset_in_saved_window()],
 253                sp[L2->sp_offset_in_saved_window()],
 254                sp[L3->sp_offset_in_saved_window()]);
 255   st->print_cr(" L4=" INTPTR_FORMAT " L5=" INTPTR_FORMAT
 256                " L6=" INTPTR_FORMAT " L7=" INTPTR_FORMAT,
 257                sp[L4->sp_offset_in_saved_window()],
 258                sp[L5->sp_offset_in_saved_window()],
 259                sp[L6->sp_offset_in_saved_window()],
 260                sp[L7->sp_offset_in_saved_window()]);
 261   st->print_cr(" I0=" INTPTR_FORMAT " I1=" INTPTR_FORMAT
 262                " I2=" INTPTR_FORMAT " I3=" INTPTR_FORMAT,
 263                sp[I0->sp_offset_in_saved_window()],
 264                sp[I1->sp_offset_in_saved_window()],
 265                sp[I2->sp_offset_in_saved_window()],
 266                sp[I3->sp_offset_in_saved_window()]);
 267   st->print_cr(" I4=" INTPTR_FORMAT " I5=" INTPTR_FORMAT
 268                " I6=" INTPTR_FORMAT " I7=" INTPTR_FORMAT,
 269                sp[I4->sp_offset_in_saved_window()],
 270                sp[I5->sp_offset_in_saved_window()],
 271                sp[I6->sp_offset_in_saved_window()],
 272                sp[I7->sp_offset_in_saved_window()]);
 273 
 274   st->print_cr(" PC=" INTPTR_FORMAT " nPC=" INTPTR_FORMAT,
 275                SIG_PC(sc),
 276                SIG_NPC(sc));
 277   st->cr();
 278   st->cr();
 279 
 280   st->print_cr("Top of Stack: (sp=" INTPTR_FORMAT ")", p2i(sp));
 281   print_hex_dump(st, (address)sp, (address)(sp + 32), sizeof(intptr_t));
 282   st->cr();
 283 
 284   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 285   // point to garbage if entry point in an nmethod is corrupted. Leave
 286   // this at the end, and hope for the best.
 287   address pc = os::Linux::ucontext_get_pc(uc);
 288   st->print_cr("Instructions: (pc=" INTPTR_FORMAT ")", p2i(pc));
 289   print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
 290 }
 291 
 292 
 293 void os::print_register_info(outputStream *st, const void *context) {
 294   if (context == NULL) return;
 295 
 296   const ucontext_t *uc = (const ucontext_t*)context;
 297   const sigcontext* sc = (const sigcontext*)context;
 298   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 299 
 300   st->print_cr("Register to memory mapping:");
 301   st->cr();
 302 
 303   // this is only for the "general purpose" registers
 304   st->print("G1="); print_location(st, SIG_REGS(sc).u_regs[CON_G1]);
 305   st->print("G2="); print_location(st, SIG_REGS(sc).u_regs[CON_G2]);
 306   st->print("G3="); print_location(st, SIG_REGS(sc).u_regs[CON_G3]);
 307   st->print("G4="); print_location(st, SIG_REGS(sc).u_regs[CON_G4]);
 308   st->print("G5="); print_location(st, SIG_REGS(sc).u_regs[CON_G5]);
 309   st->print("G6="); print_location(st, SIG_REGS(sc).u_regs[CON_G6]);
 310   st->print("G7="); print_location(st, SIG_REGS(sc).u_regs[CON_G7]);
 311   st->cr();
 312 
 313   st->print("O0="); print_location(st, SIG_REGS(sc).u_regs[CON_O0]);
 314   st->print("O1="); print_location(st, SIG_REGS(sc).u_regs[CON_O1]);
 315   st->print("O2="); print_location(st, SIG_REGS(sc).u_regs[CON_O2]);
 316   st->print("O3="); print_location(st, SIG_REGS(sc).u_regs[CON_O3]);
 317   st->print("O4="); print_location(st, SIG_REGS(sc).u_regs[CON_O4]);
 318   st->print("O5="); print_location(st, SIG_REGS(sc).u_regs[CON_O5]);
 319   st->print("O6="); print_location(st, SIG_REGS(sc).u_regs[CON_O6]);
 320   st->print("O7="); print_location(st, SIG_REGS(sc).u_regs[CON_O7]);
 321   st->cr();
 322 
 323   st->print("L0="); print_location(st, sp[L0->sp_offset_in_saved_window()]);
 324   st->print("L1="); print_location(st, sp[L1->sp_offset_in_saved_window()]);
 325   st->print("L2="); print_location(st, sp[L2->sp_offset_in_saved_window()]);
 326   st->print("L3="); print_location(st, sp[L3->sp_offset_in_saved_window()]);
 327   st->print("L4="); print_location(st, sp[L4->sp_offset_in_saved_window()]);
 328   st->print("L5="); print_location(st, sp[L5->sp_offset_in_saved_window()]);
 329   st->print("L6="); print_location(st, sp[L6->sp_offset_in_saved_window()]);
 330   st->print("L7="); print_location(st, sp[L7->sp_offset_in_saved_window()]);
 331   st->cr();
 332 
 333   st->print("I0="); print_location(st, sp[I0->sp_offset_in_saved_window()]);
 334   st->print("I1="); print_location(st, sp[I1->sp_offset_in_saved_window()]);
 335   st->print("I2="); print_location(st, sp[I2->sp_offset_in_saved_window()]);
 336   st->print("I3="); print_location(st, sp[I3->sp_offset_in_saved_window()]);
 337   st->print("I4="); print_location(st, sp[I4->sp_offset_in_saved_window()]);
 338   st->print("I5="); print_location(st, sp[I5->sp_offset_in_saved_window()]);
 339   st->print("I6="); print_location(st, sp[I6->sp_offset_in_saved_window()]);
 340   st->print("I7="); print_location(st, sp[I7->sp_offset_in_saved_window()]);
 341   st->cr();
 342 }
 343 
 344 
 345 address os::Linux::ucontext_get_pc(const ucontext_t* uc) {
 346   return (address) SIG_PC((sigcontext*)uc);
 347 }
 348 
 349 void os::Linux::ucontext_set_pc(ucontext_t* uc, address pc) {
 350   sigcontext* ctx = (sigcontext*) uc;
 351   SIG_PC(ctx)  = (intptr_t)pc;
 352   SIG_NPC(ctx) = (intptr_t)(pc+4);
 353 }
 354 
 355 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t *uc) {
 356   return (intptr_t*)
 357     ((intptr_t)SIG_REGS((sigcontext*)uc).u_regs[CON_O6] + STACK_BIAS);
 358 }
 359 
 360 // not used on Sparc
 361 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t *uc) {
 362   ShouldNotReachHere();
 363   return NULL;
 364 }
 365 
 366 // Utility functions
 367 
 368 inline static bool checkPrefetch(sigcontext* uc, address pc) {
 369   if (StubRoutines::is_safefetch_fault(pc)) {
 370     os::Linux::ucontext_set_pc((ucontext_t*)uc, StubRoutines::continuation_for_safefetch_fault(pc));
 371     return true;
 372   }
 373   return false;
 374 }
 375 
 376 inline static bool checkOverflow(sigcontext* uc,
 377                                  address pc,
 378                                  address addr,
 379                                  JavaThread* thread,
 380                                  address* stub) {
 381   // check if fault address is within thread stack
 382   if (thread->on_local_stack(addr)) {
 383     // stack overflow
 384     if (thread->in_stack_yellow_reserved_zone(addr)) {
 385       thread->disable_stack_yellow_reserved_zone();
 386       if (thread->thread_state() == _thread_in_Java) {
 387         // Throw a stack overflow exception.  Guard pages will be reenabled
 388         // while unwinding the stack.
 389         *stub =
 390           SharedRuntime::continuation_for_implicit_exception(thread,
 391                                                              pc,
 392                                                              SharedRuntime::STACK_OVERFLOW);
 393       } else {
 394         // Thread was in the vm or native code.  Return and try to finish.
 395         return true;
 396       }
 397     } else if (thread->in_stack_red_zone(addr)) {
 398       // Fatal red zone violation.  Disable the guard pages and fall through
 399       // to handle_unexpected_exception way down below.
 400       thread->disable_stack_red_zone();
 401       tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 402 
 403       // This is a likely cause, but hard to verify. Let's just print
 404       // it as a hint.
 405       tty->print_raw_cr("Please check if any of your loaded .so files has "
 406                         "enabled executable stack (see man page execstack(8))");
 407     } else {
 408       // Accessing stack address below sp may cause SEGV if current
 409       // thread has MAP_GROWSDOWN stack. This should only happen when
 410       // current thread was created by user code with MAP_GROWSDOWN flag
 411       // and then attached to VM. See notes in os_linux.cpp.
 412       if (thread->osthread()->expanding_stack() == 0) {
 413         thread->osthread()->set_expanding_stack();
 414         if (os::Linux::manually_expand_stack(thread, addr)) {
 415           thread->osthread()->clear_expanding_stack();
 416           return true;
 417         }
 418         thread->osthread()->clear_expanding_stack();
 419       } else {
 420         fatal("recursive segv. expanding stack.");
 421       }
 422     }
 423   }
 424   return false;
 425 }
 426 
 427 inline static bool checkPollingPage(address pc, address fault, address* stub) {
 428   if (fault == os::get_polling_page()) {
 429     *stub = SharedRuntime::get_poll_stub(pc);
 430     return true;
 431   }
 432   return false;
 433 }
 434 
 435 inline static bool checkByteBuffer(address pc, address npc, address* stub) {
 436   // BugId 4454115: A read from a MappedByteBuffer can fault
 437   // here if the underlying file has been truncated.
 438   // Do not crash the VM in such a case.
 439   CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 440   CompiledMethod* nm = cb->as_compiled_method_or_null();
 441   if (nm != NULL && nm->has_unsafe_access()) {
 442     *stub = SharedRuntime::handle_unsafe_access(thread, npc);
 443     return true;
 444   }
 445   return false;
 446 }
 447 
 448 inline static bool checkVerifyOops(address pc, address fault, address* stub) {
 449   if (pc >= MacroAssembler::_verify_oop_implicit_branch[0]
 450       && pc <  MacroAssembler::_verify_oop_implicit_branch[1] ) {
 451     *stub     =  MacroAssembler::_verify_oop_implicit_branch[2];
 452     warning("fixed up memory fault in +VerifyOops at address "
 453             INTPTR_FORMAT, p2i(fault));
 454     return true;
 455   }
 456   return false;
 457 }
 458 
 459 inline static bool checkFPFault(address pc, int code,
 460                                 JavaThread* thread, address* stub) {
 461   if (code == FPE_INTDIV || code == FPE_FLTDIV) {
 462     *stub =
 463       SharedRuntime::
 464       continuation_for_implicit_exception(thread,
 465                                           pc,
 466                                           SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 467     return true;
 468   }
 469   return false;
 470 }
 471 
 472 inline static bool checkNullPointer(address pc, intptr_t fault,
 473                                     JavaThread* thread, address* stub) {
 474   if (!MacroAssembler::needs_explicit_null_check(fault)) {
 475     // Determination of interpreter/vtable stub/compiled code null
 476     // exception
 477     *stub =
 478       SharedRuntime::
 479       continuation_for_implicit_exception(thread, pc,
 480                                           SharedRuntime::IMPLICIT_NULL);
 481     return true;
 482   }
 483   return false;
 484 }
 485 
 486 inline static bool checkFastJNIAccess(address pc, address* stub) {
 487   address addr = JNI_FastGetField::find_slowcase_pc(pc);
 488   if (addr != (address)-1) {
 489     *stub = addr;
 490     return true;
 491   }
 492   return false;
 493 }
 494 
 495 inline static bool checkSerializePage(JavaThread* thread, address addr) {
 496   return os::is_memory_serialize_page(thread, addr);
 497 }
 498 
 499 inline static bool checkZombie(sigcontext* uc, address* pc, address* stub) {
 500   if (nativeInstruction_at(*pc)->is_zombie()) {
 501     // zombie method (ld [%g0],%o7 instruction)
 502     *stub = SharedRuntime::get_handle_wrong_method_stub();
 503 
 504     // At the stub it needs to look like a call from the caller of this
 505     // method (not a call from the segv site).
 506     *pc = (address)SIG_REGS(uc).u_regs[CON_O7];
 507     return true;
 508   }
 509   return false;
 510 }
 511 
 512 inline static bool checkICMiss(sigcontext* uc, address* pc, address* stub) {
 513 #ifdef COMPILER2
 514   if (nativeInstruction_at(*pc)->is_ic_miss_trap()) {
 515 #ifdef ASSERT
 516 #ifdef TIERED
 517     CodeBlob* cb = CodeCache::find_blob_unsafe(*pc);
 518     assert(cb->is_compiled_by_c2(), "Wrong compiler");
 519 #endif // TIERED
 520 #endif // ASSERT
 521     // Inline cache missed and user trap "Tne G0+ST_RESERVED_FOR_USER_0+2" taken.
 522     *stub = SharedRuntime::get_ic_miss_stub();
 523     // At the stub it needs to look like a call from the caller of this
 524     // method (not a call from the segv site).
 525     *pc = (address)SIG_REGS(uc).u_regs[CON_O7];
 526     return true;
 527   }
 528 #endif  // COMPILER2
 529   return false;
 530 }
 531 
 532 extern "C" JNIEXPORT int
 533 JVM_handle_linux_signal(int sig,
 534                         siginfo_t* info,
 535                         void* ucVoid,
 536                         int abort_if_unrecognized) {
 537   // in fact this isn't ucontext_t* at all, but struct sigcontext*
 538   // but Linux porting layer uses ucontext_t, so to minimize code change
 539   // we cast as needed
 540   ucontext_t* ucFake = (ucontext_t*) ucVoid;
 541   sigcontext* uc = (sigcontext*)ucVoid;
 542 
 543   Thread* t = Thread::current_or_null_safe();
 544 
 545   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
 546   // (no destructors can be run)
 547   os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
 548 
 549   SignalHandlerMark shm(t);
 550 
 551   // Note: it's not uncommon that JNI code uses signal/sigset to install
 552   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 553   // or have a SIGILL handler when detecting CPU type). When that happens,
 554   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
 555   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 556   // that do not require siginfo/ucontext first.
 557 
 558   if (sig == SIGPIPE || sig == SIGXFSZ) {
 559     // allow chained handler to go first
 560     if (os::Linux::chained_handler(sig, info, ucVoid)) {
 561       return true;
 562     } else {
 563       // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219
 564       return true;
 565     }
 566   }
 567 
 568   JavaThread* thread = NULL;
 569   VMThread* vmthread = NULL;
 570   if (os::Linux::signal_handlers_are_installed) {
 571     if (t != NULL ){
 572       if(t->is_Java_thread()) {
 573         thread = (JavaThread*)t;
 574       }
 575       else if(t->is_VM_thread()){
 576         vmthread = (VMThread *)t;
 577       }
 578     }
 579   }
 580 
 581   // decide if this trap can be handled by a stub
 582   address stub = NULL;
 583   address pc = NULL;
 584   address npc = NULL;
 585 
 586   //%note os_trap_1
 587   if (info != NULL && uc != NULL && thread != NULL) {
 588     pc = address(SIG_PC(uc));
 589     npc = address(SIG_NPC(uc));
 590 
 591     // Check to see if we caught the safepoint code in the
 592     // process of write protecting the memory serialization page.
 593     // It write enables the page immediately after protecting it
 594     // so we can just return to retry the write.
 595     if ((sig == SIGSEGV) && checkSerializePage(thread, (address)info->si_addr)) {
 596       // Block current thread until the memory serialize page permission restored.
 597       os::block_on_serialize_page_trap();
 598       return 1;
 599     }
 600 
 601     if (checkPrefetch(uc, pc)) {
 602       return 1;
 603     }
 604 
 605     // Handle ALL stack overflow variations here
 606     if (sig == SIGSEGV) {
 607       if (checkOverflow(uc, pc, (address)info->si_addr, thread, &stub)) {
 608         return 1;
 609       }
 610     }
 611 
 612     if (sig == SIGBUS &&
 613         thread->thread_state() == _thread_in_vm &&
 614         thread->doing_unsafe_access()) {
 615       stub = SharedRuntime::handle_unsafe_access(thread, npc);
 616     }
 617 
 618     if (thread->thread_state() == _thread_in_Java) {
 619       do {
 620         // Java thread running in Java code => find exception handler if any
 621         // a fault inside compiled code, the interpreter, or a stub
 622 
 623         if ((sig == SIGSEGV) && checkPollingPage(pc, (address)info->si_addr, &stub)) {
 624           break;
 625         }
 626 
 627         if ((sig == SIGBUS) && checkByteBuffer(pc, npc, &stub)) {
 628           break;
 629         }
 630 
 631         if ((sig == SIGSEGV || sig == SIGBUS) &&
 632             checkVerifyOops(pc, (address)info->si_addr, &stub)) {
 633           break;
 634         }
 635 
 636         if ((sig == SIGSEGV) && checkZombie(uc, &pc, &stub)) {
 637           break;
 638         }
 639 
 640         if ((sig == SIGILL) && checkICMiss(uc, &pc, &stub)) {
 641           break;
 642         }
 643 
 644         if ((sig == SIGFPE) && checkFPFault(pc, info->si_code, thread, &stub)) {
 645           break;
 646         }
 647 
 648         if ((sig == SIGSEGV) &&
 649             checkNullPointer(pc, (intptr_t)info->si_addr, thread, &stub)) {
 650           break;
 651         }
 652       } while (0);
 653 
 654       // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
 655       // and the heap gets shrunk before the field access.
 656       if ((sig == SIGSEGV) || (sig == SIGBUS)) {
 657         checkFastJNIAccess(pc, &stub);
 658       }
 659     }
 660 
 661     if (stub != NULL) {
 662       // save all thread context in case we need to restore it
 663       thread->set_saved_exception_pc(pc);
 664       thread->set_saved_exception_npc(npc);
 665       os::Linux::ucontext_set_pc((ucontext_t*)uc, stub);
 666       return true;
 667     }
 668   }
 669 
 670   // signal-chaining
 671   if (os::Linux::chained_handler(sig, info, ucVoid)) {
 672     return true;
 673   }
 674 
 675   if (!abort_if_unrecognized) {
 676     // caller wants another chance, so give it to him
 677     return false;
 678   }
 679 
 680   if (pc == NULL && uc != NULL) {
 681     pc = os::Linux::ucontext_get_pc((const ucontext_t*)uc);
 682   }
 683 
 684   // unmask current signal
 685   sigset_t newset;
 686   sigemptyset(&newset);
 687   sigaddset(&newset, sig);
 688   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 689 
 690   VMError::report_and_die(t, sig, pc, info, ucVoid);
 691 
 692   ShouldNotReachHere();
 693   return false;
 694 }
 695 
 696 void os::Linux::init_thread_fpu_state(void) {
 697   // Nothing to do
 698 }
 699 
 700 int os::Linux::get_fpu_control_word() {
 701   return 0;
 702 }
 703 
 704 void os::Linux::set_fpu_control_word(int fpu) {
 705   // nothing
 706 }
 707 
 708 bool os::is_allocatable(size_t bytes) {
 709 #ifdef _LP64
 710   return true;
 711 #else
 712   if (bytes < 2 * G) {
 713     return true;
 714   }
 715 
 716   char* addr = reserve_memory(bytes, NULL);
 717 
 718   if (addr != NULL) {
 719     release_memory(addr, bytes);
 720   }
 721 
 722   return addr != NULL;
 723 #endif // _LP64
 724 }
 725 
 726 ///////////////////////////////////////////////////////////////////////////////
 727 // thread stack
 728 
 729 size_t os::Posix::_compiler_thread_min_stack_allowed = 128 * K;
 730 size_t os::Posix::_java_thread_min_stack_allowed = 128 * K;
 731 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 128 * K;
 732 
 733 // return default stack size for thr_type
 734 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 735   // default stack size (compiler thread needs larger stack)
 736   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
 737   return s;
 738 }
 739 
 740 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
 741   // Creating guard page is very expensive. Java thread has HotSpot
 742   // guard page, only enable glibc guard page for non-Java threads.
 743   return (thr_type == java_thread ? 0 : page_size());
 744 }
 745 
 746 #ifndef PRODUCT
 747 void os::verify_stack_alignment() {
 748 }
 749 #endif
 750 
 751 int os::extra_bang_size_in_bytes() {
 752   // SPARC does not require the additional stack bang.
 753   return 0;
 754 }
--- EOF ---