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 "os_share_linux.hpp"
  37 #include "prims/jniFastGetField.hpp"
  38 #include "prims/jvm.h"
  39 #include "prims/jvm_misc.hpp"
  40 #include "runtime/arguments.hpp"
  41 #include "runtime/extendedPC.hpp"
  42 #include "runtime/frame.inline.hpp"
  43 #include "runtime/interfaceSupport.hpp"
  44 #include "runtime/java.hpp"
  45 #include "runtime/javaCalls.hpp"
  46 #include "runtime/mutexLocker.hpp"
  47 #include "runtime/osThread.hpp"
  48 #include "runtime/sharedRuntime.hpp"
  49 #include "runtime/stubRoutines.hpp"
  50 #include "runtime/thread.inline.hpp"
  51 #include "runtime/timer.hpp"
  52 #include "services/memTracker.hpp"
  53 #include "utilities/events.hpp"
  54 #include "utilities/vmError.hpp"
  55 
  56 // put OS-includes here
  57 # include <sys/types.h>
  58 # include <sys/mman.h>
  59 # include <pthread.h>
  60 # include <signal.h>
  61 # include <errno.h>
  62 # include <dlfcn.h>
  63 # include <stdlib.h>
  64 # include <stdio.h>
  65 # include <unistd.h>
  66 # include <sys/resource.h>
  67 # include <pthread.h>
  68 # include <sys/stat.h>
  69 # include <sys/time.h>
  70 # include <sys/utsname.h>
  71 # include <sys/socket.h>
  72 # include <sys/wait.h>
  73 # include <pwd.h>
  74 # include <poll.h>
  75 # include <ucontext.h>
  76 # include <fpu_control.h>
  77 
  78 #ifdef AMD64
  79 #define REG_SP REG_RSP
  80 #define REG_PC REG_RIP
  81 #define REG_FP REG_RBP
  82 #define SPELL_REG_SP "rsp"
  83 #define SPELL_REG_FP "rbp"
  84 #else
  85 #define REG_SP REG_UESP
  86 #define REG_PC REG_EIP
  87 #define REG_FP REG_EBP
  88 #define SPELL_REG_SP "esp"
  89 #define SPELL_REG_FP "ebp"
  90 #endif // AMD64
  91 
  92 address os::current_stack_pointer() {
  93 #ifdef SPARC_WORKS
  94   register void *esp;
  95   __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp));
  96   return (address) ((char*)esp + sizeof(long)*2);
  97 #elif defined(__clang__)
  98   intptr_t* esp;
  99   __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):);
 100   return (address) esp;
 101 #else
 102   register void *esp __asm__ (SPELL_REG_SP);
 103   return (address) esp;
 104 #endif
 105 }
 106 
 107 char* os::non_memory_address_word() {
 108   // Must never look like an address returned by reserve_memory,
 109   // even in its subfields (as defined by the CPU immediate fields,
 110   // if the CPU splits constants across multiple instructions).
 111 
 112   return (char*) -1;
 113 }
 114 
 115 void os::initialize_thread(Thread* thr) {
 116 // Nothing to do.
 117 }
 118 
 119 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
 120   return (address)uc->uc_mcontext.gregs[REG_PC];
 121 }
 122 
 123 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
 124   uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
 125 }
 126 
 127 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
 128   return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
 129 }
 130 
 131 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
 132   return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
 133 }
 134 
 135 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
 136 // is currently interrupted by SIGPROF.
 137 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
 138 // frames. Currently we don't do that on Linux, so it's the same as
 139 // os::fetch_frame_from_context().
 140 // This method is also used for stack overflow signal handling.
 141 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
 142   const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
 143 
 144   assert(thread != NULL, "just checking");
 145   assert(ret_sp != NULL, "just checking");
 146   assert(ret_fp != NULL, "just checking");
 147 
 148   return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
 149 }
 150 
 151 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
 152                     intptr_t** ret_sp, intptr_t** ret_fp) {
 153 
 154   ExtendedPC  epc;
 155   const ucontext_t* uc = (const ucontext_t*)ucVoid;
 156 
 157   if (uc != NULL) {
 158     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
 159     if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
 160     if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
 161   } else {
 162     // construct empty ExtendedPC for return value checking
 163     epc = ExtendedPC(NULL);
 164     if (ret_sp) *ret_sp = (intptr_t *)NULL;
 165     if (ret_fp) *ret_fp = (intptr_t *)NULL;
 166   }
 167 
 168   return epc;
 169 }
 170 
 171 frame os::fetch_frame_from_context(const void* ucVoid) {
 172   intptr_t* sp;
 173   intptr_t* fp;
 174   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 175   return frame(sp, fp, epc.pc());
 176 }
 177 
 178 frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) {
 179   intptr_t* sp;
 180   intptr_t* fp;
 181   ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp);
 182   return frame(sp, fp, epc.pc());
 183 }
 184 
 185 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
 186   address pc = (address) os::Linux::ucontext_get_pc(uc);
 187   if (Interpreter::contains(pc)) {
 188     // interpreter performs stack banging after the fixed frame header has
 189     // been generated while the compilers perform it before. To maintain
 190     // semantic consistency between interpreted and compiled frames, the
 191     // method returns the Java sender of the current frame.
 192     *fr = os::fetch_frame_from_ucontext(thread, uc);
 193     if (!fr->is_first_java_frame()) {
 194       // get_frame_at_stack_banging_point() is only called when we
 195       // have well defined stacks so java_sender() calls do not need
 196       // to assert safe_for_sender() first.
 197       *fr = fr->java_sender();
 198     }
 199   } else {
 200     // more complex code with compiled code
 201     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
 202     CodeBlob* cb = CodeCache::find_blob(pc);
 203     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
 204       // Not sure where the pc points to, fallback to default
 205       // stack overflow handling
 206       return false;
 207     } else {
 208       // in compiled code, the stack banging is performed just after the return pc
 209       // has been pushed on the stack
 210       intptr_t* fp = os::Linux::ucontext_get_fp(uc);
 211       intptr_t* sp = os::Linux::ucontext_get_sp(uc);
 212       *fr = frame(sp + 1, fp, (address)*sp);
 213       if (!fr->is_java_frame()) {
 214         assert(!fr->is_first_frame(), "Safety check");
 215         // See java_sender() comment above.
 216         *fr = fr->java_sender();
 217       }
 218     }
 219   }
 220   assert(fr->is_java_frame(), "Safety check");
 221   return true;
 222 }
 223 
 224 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
 225 // turned off by -fomit-frame-pointer,
 226 frame os::get_sender_for_C_frame(frame* fr) {
 227   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
 228 }
 229 
 230 intptr_t* _get_previous_fp() {
 231 #ifdef SPARC_WORKS
 232   register intptr_t **ebp;
 233   __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
 234 #elif defined(__clang__)
 235   intptr_t **ebp;
 236   __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
 237 #else
 238   register intptr_t **ebp __asm__ (SPELL_REG_FP);
 239 #endif
 240   // ebp is for this frame (_get_previous_fp). We want the ebp for the
 241   // caller of os::current_frame*(), so go up two frames. However, for
 242   // optimized builds, _get_previous_fp() will be inlined, so only go
 243   // up 1 frame in that case.
 244 #ifdef _NMT_NOINLINE_
 245   return **(intptr_t***)ebp;
 246 #else
 247   return *ebp;
 248 #endif
 249 }
 250 
 251 
 252 frame os::current_frame() {
 253   intptr_t* fp = _get_previous_fp();
 254   frame myframe((intptr_t*)os::current_stack_pointer(),
 255                 (intptr_t*)fp,
 256                 CAST_FROM_FN_PTR(address, os::current_frame));
 257   if (os::is_first_C_frame(&myframe)) {
 258     // stack is not walkable
 259     return frame();
 260   } else {
 261     return os::get_sender_for_C_frame(&myframe);
 262   }
 263 }
 264 
 265 // Utility functions
 266 
 267 // From IA32 System Programming Guide
 268 enum {
 269   trap_page_fault = 0xE
 270 };
 271 
 272 extern "C" JNIEXPORT int
 273 JVM_handle_linux_signal(int sig,
 274                         siginfo_t* info,
 275                         void* ucVoid,
 276                         int abort_if_unrecognized) {
 277   ucontext_t* uc = (ucontext_t*) ucVoid;
 278 
 279   Thread* t = Thread::current_or_null_safe();
 280 
 281   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
 282   // (no destructors can be run)
 283   os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
 284 
 285   SignalHandlerMark shm(t);
 286 
 287   // Note: it's not uncommon that JNI code uses signal/sigset to install
 288   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 289   // or have a SIGILL handler when detecting CPU type). When that happens,
 290   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
 291   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 292   // that do not require siginfo/ucontext first.
 293 
 294   if (sig == SIGPIPE || sig == SIGXFSZ) {
 295     // allow chained handler to go first
 296     if (os::Linux::chained_handler(sig, info, ucVoid)) {
 297       return true;
 298     } else {
 299       // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219
 300       return true;
 301     }
 302   }
 303 
 304   JavaThread* thread = NULL;
 305   VMThread* vmthread = NULL;
 306   if (os::Linux::signal_handlers_are_installed) {
 307     if (t != NULL ){
 308       if(t->is_Java_thread()) {
 309         thread = (JavaThread*)t;
 310       }
 311       else if(t->is_VM_thread()){
 312         vmthread = (VMThread *)t;
 313       }
 314     }
 315   }
 316 /*
 317   NOTE: does not seem to work on linux.
 318   if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
 319     // can't decode this kind of signal
 320     info = NULL;
 321   } else {
 322     assert(sig == info->si_signo, "bad siginfo");
 323   }
 324 */
 325   // decide if this trap can be handled by a stub
 326   address stub = NULL;
 327 
 328   address pc          = NULL;
 329 
 330   //%note os_trap_1
 331   if (info != NULL && uc != NULL && thread != NULL) {
 332     pc = (address) os::Linux::ucontext_get_pc(uc);
 333 
 334     if (StubRoutines::is_safefetch_fault(pc)) {
 335       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
 336       return 1;
 337     }
 338 
 339 #ifndef AMD64
 340     // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
 341     // This can happen in any running code (currently more frequently in
 342     // interpreter code but has been seen in compiled code)
 343     if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
 344       fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
 345             "to unstable signal handling in this distribution.");
 346     }
 347 #endif // AMD64
 348 
 349     // Handle ALL stack overflow variations here
 350     if (sig == SIGSEGV) {
 351       address addr = (address) info->si_addr;
 352 
 353       // check if fault address is within thread stack
 354       if (thread->on_local_stack(addr)) {
 355         // stack overflow
 356         if (thread->in_stack_yellow_reserved_zone(addr)) {
 357           if (thread->thread_state() == _thread_in_Java) {
 358             if (thread->in_stack_reserved_zone(addr)) {
 359               frame fr;
 360               if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
 361                 assert(fr.is_java_frame(), "Must be a Java frame");
 362                 frame activation =
 363                   SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
 364                 if (activation.sp() != NULL) {
 365                   thread->disable_stack_reserved_zone();
 366                   if (activation.is_interpreted_frame()) {
 367                     thread->set_reserved_stack_activation((address)(
 368                       activation.fp() + frame::interpreter_frame_initial_sp_offset));
 369                   } else {
 370                     thread->set_reserved_stack_activation((address)activation.unextended_sp());
 371                   }
 372                   return 1;
 373                 }
 374               }
 375             }
 376             // Throw a stack overflow exception.  Guard pages will be reenabled
 377             // while unwinding the stack.
 378             thread->disable_stack_yellow_reserved_zone();
 379             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
 380           } else {
 381             // Thread was in the vm or native code.  Return and try to finish.
 382             thread->disable_stack_yellow_reserved_zone();
 383             return 1;
 384           }
 385         } else if (thread->in_stack_red_zone(addr)) {
 386           // Fatal red zone violation.  Disable the guard pages and fall through
 387           // to handle_unexpected_exception way down below.
 388           thread->disable_stack_red_zone();
 389           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 390 
 391           // This is a likely cause, but hard to verify. Let's just print
 392           // it as a hint.
 393           tty->print_raw_cr("Please check if any of your loaded .so files has "
 394                             "enabled executable stack (see man page execstack(8))");
 395         } else {
 396           // Accessing stack address below sp may cause SEGV if current
 397           // thread has MAP_GROWSDOWN stack. This should only happen when
 398           // current thread was created by user code with MAP_GROWSDOWN flag
 399           // and then attached to VM. See notes in os_linux.cpp.
 400           if (thread->osthread()->expanding_stack() == 0) {
 401              thread->osthread()->set_expanding_stack();
 402              if (os::Linux::manually_expand_stack(thread, addr)) {
 403                thread->osthread()->clear_expanding_stack();
 404                return 1;
 405              }
 406              thread->osthread()->clear_expanding_stack();
 407           } else {
 408              fatal("recursive segv. expanding stack.");
 409           }
 410         }
 411       }
 412     }
 413 
 414     if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
 415       // Verify that OS save/restore AVX registers.
 416       stub = VM_Version::cpuinfo_cont_addr();
 417     }
 418 
 419     if (thread->thread_state() == _thread_in_Java) {
 420       // Java thread running in Java code => find exception handler if any
 421       // a fault inside compiled code, the interpreter, or a stub
 422 
 423       if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
 424         stub = SharedRuntime::get_poll_stub(pc);
 425       } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
 426         // BugId 4454115: A read from a MappedByteBuffer can fault
 427         // here if the underlying file has been truncated.
 428         // Do not crash the VM in such a case.
 429         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 430         CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
 431         if (nm != NULL && nm->has_unsafe_access()) {
 432           address next_pc = Assembler::locate_next_instruction(pc);
 433           stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
 434         }
 435       }
 436       else
 437 
 438 #ifdef AMD64
 439       if (sig == SIGFPE  &&
 440           (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
 441         stub =
 442           SharedRuntime::
 443           continuation_for_implicit_exception(thread,
 444                                               pc,
 445                                               SharedRuntime::
 446                                               IMPLICIT_DIVIDE_BY_ZERO);
 447 #else
 448       if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
 449         // HACK: si_code does not work on linux 2.2.12-20!!!
 450         int op = pc[0];
 451         if (op == 0xDB) {
 452           // FIST
 453           // TODO: The encoding of D2I in i486.ad can cause an exception
 454           // prior to the fist instruction if there was an invalid operation
 455           // pending. We want to dismiss that exception. From the win_32
 456           // side it also seems that if it really was the fist causing
 457           // the exception that we do the d2i by hand with different
 458           // rounding. Seems kind of weird.
 459           // NOTE: that we take the exception at the NEXT floating point instruction.
 460           assert(pc[0] == 0xDB, "not a FIST opcode");
 461           assert(pc[1] == 0x14, "not a FIST opcode");
 462           assert(pc[2] == 0x24, "not a FIST opcode");
 463           return true;
 464         } else if (op == 0xF7) {
 465           // IDIV
 466           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 467         } else {
 468           // TODO: handle more cases if we are using other x86 instructions
 469           //   that can generate SIGFPE signal on linux.
 470           tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
 471           fatal("please update this code.");
 472         }
 473 #endif // AMD64
 474       } else if (sig == SIGSEGV &&
 475                !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
 476           // Determination of interpreter/vtable stub/compiled code null exception
 477           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 478       }
 479     } else if (thread->thread_state() == _thread_in_vm &&
 480                sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
 481                thread->doing_unsafe_access()) {
 482         address next_pc = Assembler::locate_next_instruction(pc);
 483         stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
 484     }
 485 
 486     // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
 487     // and the heap gets shrunk before the field access.
 488     if ((sig == SIGSEGV) || (sig == SIGBUS)) {
 489       address addr = JNI_FastGetField::find_slowcase_pc(pc);
 490       if (addr != (address)-1) {
 491         stub = addr;
 492       }
 493     }
 494 
 495     // Check to see if we caught the safepoint code in the
 496     // process of write protecting the memory serialization page.
 497     // It write enables the page immediately after protecting it
 498     // so we can just return to retry the write.
 499     if ((sig == SIGSEGV) &&
 500         os::is_memory_serialize_page(thread, (address) info->si_addr)) {
 501       // Block current thread until the memory serialize page permission restored.
 502       os::block_on_serialize_page_trap();
 503       return true;
 504     }
 505   }
 506 
 507 #ifndef AMD64
 508   // Execution protection violation
 509   //
 510   // This should be kept as the last step in the triage.  We don't
 511   // have a dedicated trap number for a no-execute fault, so be
 512   // conservative and allow other handlers the first shot.
 513   //
 514   // Note: We don't test that info->si_code == SEGV_ACCERR here.
 515   // this si_code is so generic that it is almost meaningless; and
 516   // the si_code for this condition may change in the future.
 517   // Furthermore, a false-positive should be harmless.
 518   if (UnguardOnExecutionViolation > 0 &&
 519       (sig == SIGSEGV || sig == SIGBUS) &&
 520       uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
 521     int page_size = os::vm_page_size();
 522     address addr = (address) info->si_addr;
 523     address pc = os::Linux::ucontext_get_pc(uc);
 524     // Make sure the pc and the faulting address are sane.
 525     //
 526     // If an instruction spans a page boundary, and the page containing
 527     // the beginning of the instruction is executable but the following
 528     // page is not, the pc and the faulting address might be slightly
 529     // different - we still want to unguard the 2nd page in this case.
 530     //
 531     // 15 bytes seems to be a (very) safe value for max instruction size.
 532     bool pc_is_near_addr =
 533       (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
 534     bool instr_spans_page_boundary =
 535       (align_size_down((intptr_t) pc ^ (intptr_t) addr,
 536                        (intptr_t) page_size) > 0);
 537 
 538     if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
 539       static volatile address last_addr =
 540         (address) os::non_memory_address_word();
 541 
 542       // In conservative mode, don't unguard unless the address is in the VM
 543       if (addr != last_addr &&
 544           (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
 545 
 546         // Set memory to RWX and retry
 547         address page_start =
 548           (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
 549         bool res = os::protect_memory((char*) page_start, page_size,
 550                                       os::MEM_PROT_RWX);
 551 
 552         log_debug(os)("Execution protection violation "
 553                       "at " INTPTR_FORMAT
 554                       ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr),
 555                       p2i(page_start), (res ? "success" : "failed"), errno);
 556         stub = pc;
 557 
 558         // Set last_addr so if we fault again at the same address, we don't end
 559         // up in an endless loop.
 560         //
 561         // There are two potential complications here.  Two threads trapping at
 562         // the same address at the same time could cause one of the threads to
 563         // think it already unguarded, and abort the VM.  Likely very rare.
 564         //
 565         // The other race involves two threads alternately trapping at
 566         // different addresses and failing to unguard the page, resulting in
 567         // an endless loop.  This condition is probably even more unlikely than
 568         // the first.
 569         //
 570         // Although both cases could be avoided by using locks or thread local
 571         // last_addr, these solutions are unnecessary complication: this
 572         // handler is a best-effort safety net, not a complete solution.  It is
 573         // disabled by default and should only be used as a workaround in case
 574         // we missed any no-execute-unsafe VM code.
 575 
 576         last_addr = addr;
 577       }
 578     }
 579   }
 580 #endif // !AMD64
 581 
 582   if (stub != NULL) {
 583     // save all thread context in case we need to restore it
 584     if (thread != NULL) thread->set_saved_exception_pc(pc);
 585 
 586     os::Linux::ucontext_set_pc(uc, stub);
 587     return true;
 588   }
 589 
 590   // signal-chaining
 591   if (os::Linux::chained_handler(sig, info, ucVoid)) {
 592      return true;
 593   }
 594 
 595   if (!abort_if_unrecognized) {
 596     // caller wants another chance, so give it to him
 597     return false;
 598   }
 599 
 600   if (pc == NULL && uc != NULL) {
 601     pc = os::Linux::ucontext_get_pc(uc);
 602   }
 603 
 604   // unmask current signal
 605   sigset_t newset;
 606   sigemptyset(&newset);
 607   sigaddset(&newset, sig);
 608   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 609 
 610   VMError::report_and_die(t, sig, pc, info, ucVoid);
 611 
 612   ShouldNotReachHere();
 613   return true; // Mute compiler
 614 }
 615 
 616 void os::Linux::init_thread_fpu_state(void) {
 617 #ifndef AMD64
 618   // set fpu to 53 bit precision
 619   set_fpu_control_word(0x27f);
 620 #endif // !AMD64
 621 }
 622 
 623 int os::Linux::get_fpu_control_word(void) {
 624 #ifdef AMD64
 625   return 0;
 626 #else
 627   int fpu_control;
 628   _FPU_GETCW(fpu_control);
 629   return fpu_control & 0xffff;
 630 #endif // AMD64
 631 }
 632 
 633 void os::Linux::set_fpu_control_word(int fpu_control) {
 634 #ifndef AMD64
 635   _FPU_SETCW(fpu_control);
 636 #endif // !AMD64
 637 }
 638 
 639 // Check that the linux kernel version is 2.4 or higher since earlier
 640 // versions do not support SSE without patches.
 641 bool os::supports_sse() {
 642 #ifdef AMD64
 643   return true;
 644 #else
 645   struct utsname uts;
 646   if( uname(&uts) != 0 ) return false; // uname fails?
 647   char *minor_string;
 648   int major = strtol(uts.release,&minor_string,10);
 649   int minor = strtol(minor_string+1,NULL,10);
 650   bool result = (major > 2 || (major==2 && minor >= 4));
 651   log_info(os)("OS version is %d.%d, which %s support SSE/SSE2",
 652                major,minor, result ? "DOES" : "does NOT");
 653   return result;
 654 #endif // AMD64
 655 }
 656 
 657 bool os::is_allocatable(size_t bytes) {
 658 #ifdef AMD64
 659   // unused on amd64?
 660   return true;
 661 #else
 662 
 663   if (bytes < 2 * G) {
 664     return true;
 665   }
 666 
 667   char* addr = reserve_memory(bytes, NULL);
 668 
 669   if (addr != NULL) {
 670     release_memory(addr, bytes);
 671   }
 672 
 673   return addr != NULL;
 674 #endif // AMD64
 675 }
 676 
 677 ////////////////////////////////////////////////////////////////////////////////
 678 // thread stack
 679 
 680 #ifdef AMD64
 681 size_t os::Posix::_compiler_thread_min_stack_allowed = 64 * K;
 682 size_t os::Posix::_java_thread_min_stack_allowed = 64 * K;
 683 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
 684 #else
 685 size_t os::Posix::_compiler_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
 686 size_t os::Posix::_java_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
 687 size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
 688 #endif // AMD64
 689 
 690 // return default stack size for thr_type
 691 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 692   // default stack size (compiler thread needs larger stack)
 693 #ifdef AMD64
 694   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
 695 #else
 696   size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
 697 #endif // AMD64
 698   return s;
 699 }
 700 





















































































 701 /////////////////////////////////////////////////////////////////////////////
 702 // helper functions for fatal error handler
 703 
 704 void os::print_context(outputStream *st, const void *context) {
 705   if (context == NULL) return;
 706 
 707   const ucontext_t *uc = (const ucontext_t*)context;
 708   st->print_cr("Registers:");
 709 #ifdef AMD64
 710   st->print(  "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
 711   st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
 712   st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
 713   st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
 714   st->cr();
 715   st->print(  "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
 716   st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
 717   st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
 718   st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
 719   st->cr();
 720   st->print(  "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
 721   st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
 722   st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
 723   st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
 724   st->cr();
 725   st->print(  "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
 726   st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
 727   st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
 728   st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
 729   st->cr();
 730   st->print(  "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
 731   st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
 732   st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
 733   st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
 734   st->cr();
 735   st->print("  TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
 736 #else
 737   st->print(  "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
 738   st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
 739   st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
 740   st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
 741   st->cr();
 742   st->print(  "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
 743   st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
 744   st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
 745   st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
 746   st->cr();
 747   st->print(  "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
 748   st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
 749   st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
 750 #endif // AMD64
 751   st->cr();
 752   st->cr();
 753 
 754   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 755   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
 756   print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t));
 757   st->cr();
 758 
 759   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 760   // point to garbage if entry point in an nmethod is corrupted. Leave
 761   // this at the end, and hope for the best.
 762   address pc = os::Linux::ucontext_get_pc(uc);
 763   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
 764   print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
 765 }
 766 
 767 void os::print_register_info(outputStream *st, const void *context) {
 768   if (context == NULL) return;
 769 
 770   const ucontext_t *uc = (const ucontext_t*)context;
 771 
 772   st->print_cr("Register to memory mapping:");
 773   st->cr();
 774 
 775   // this is horrendously verbose but the layout of the registers in the
 776   // context does not match how we defined our abstract Register set, so
 777   // we can't just iterate through the gregs area
 778 
 779   // this is only for the "general purpose" registers
 780 
 781 #ifdef AMD64
 782   st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
 783   st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
 784   st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
 785   st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
 786   st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
 787   st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
 788   st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
 789   st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
 790   st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
 791   st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
 792   st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
 793   st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
 794   st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
 795   st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
 796   st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
 797   st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
 798 #else
 799   st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
 800   st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
 801   st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
 802   st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
 803   st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
 804   st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
 805   st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
 806   st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
 807 #endif // AMD64
 808 
 809   st->cr();
 810 }
 811 
 812 void os::setup_fpu() {
 813 #ifndef AMD64
 814   address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
 815   __asm__ volatile (  "fldcw (%0)" :
 816                       : "r" (fpu_cntrl) : "memory");
 817 #endif // !AMD64
 818 }
 819 
 820 #ifndef PRODUCT
 821 void os::verify_stack_alignment() {
 822 #ifdef AMD64
 823   assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
 824 #endif
 825 }
 826 #endif
 827 
 828 
 829 /*
 830  * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
 831  * updates (JDK-8023956).
 832  */
 833 void os::workaround_expand_exec_shield_cs_limit() {
 834 #if defined(IA32)
 835   size_t page_size = os::vm_page_size();
 836   /*
 837    * Take the highest VA the OS will give us and exec
 838    *
 839    * Although using -(pagesz) as mmap hint works on newer kernel as you would
 840    * think, older variants affected by this work-around don't (search forward only).
 841    *
 842    * On the affected distributions, we understand the memory layout to be:
 843    *
 844    *   TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
 845    *
 846    * A few pages south main stack will do it.
 847    *
 848    * If we are embedded in an app other than launcher (initial != main stack),
 849    * we don't have much control or understanding of the address space, just let it slide.
 850    */
 851   char* hint = (char*)(Linux::initial_thread_stack_bottom() -
 852                        (JavaThread::stack_guard_zone_size() + page_size));
 853   char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
 854   if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) {
 855     return; // No matter, we tried, best effort.
 856   }
 857 
 858   MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
 859 
 860   log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
 861 
 862   // Some code to exec: the 'ret' instruction
 863   codebuf[0] = 0xC3;
 864 
 865   // Call the code in the codebuf
 866   __asm__ volatile("call *%0" : : "r"(codebuf));
 867 
 868   // keep the page mapped so CS limit isn't reduced.
 869 #endif
 870 }
 871 
 872 int os::extra_bang_size_in_bytes() {
 873   // JDK-8050147 requires the full cache line bang for x86.
 874   return VM_Version::L1_line_size();
 875 }
--- EOF ---