1 /*
   2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2016, 2018 SAP SE. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 // This file is organized as os_linux_x86.cpp.
  27 
  28 // no precompiled headers
  29 #include "jvm.h"
  30 #include "asm/assembler.inline.hpp"
  31 #include "classfile/classLoader.hpp"
  32 #include "classfile/systemDictionary.hpp"
  33 #include "classfile/vmSymbols.hpp"
  34 #include "code/icBuffer.hpp"
  35 #include "code/nativeInst.hpp"
  36 #include "code/vtableStubs.hpp"
  37 #include "compiler/disassembler.hpp"
  38 #include "interpreter/interpreter.hpp"
  39 #include "memory/allocation.inline.hpp"
  40 #include "nativeInst_s390.hpp"
  41 #include "os_share_linux.hpp"
  42 #include "prims/jniFastGetField.hpp"
  43 #include "prims/jvm_misc.hpp"
  44 #include "runtime/arguments.hpp"
  45 #include "runtime/extendedPC.hpp"
  46 #include "runtime/frame.inline.hpp"
  47 #include "runtime/interfaceSupport.inline.hpp"
  48 #include "runtime/java.hpp"
  49 #include "runtime/javaCalls.hpp"
  50 #include "runtime/mutexLocker.hpp"
  51 #include "runtime/osThread.hpp"
  52 #include "runtime/sharedRuntime.hpp"
  53 #include "runtime/stubRoutines.hpp"
  54 #include "runtime/thread.inline.hpp"
  55 #include "runtime/timer.hpp"
  56 #include "utilities/events.hpp"
  57 #include "utilities/vmError.hpp"
  58 
  59 // put OS-includes here
  60 # include <sys/types.h>
  61 # include <sys/mman.h>
  62 # include <pthread.h>
  63 # include <signal.h>
  64 # include <errno.h>
  65 # include <dlfcn.h>
  66 # include <stdlib.h>
  67 # include <stdio.h>
  68 # include <unistd.h>
  69 # include <sys/resource.h>
  70 # include <pthread.h>
  71 # include <sys/stat.h>
  72 # include <sys/time.h>
  73 # include <sys/utsname.h>
  74 # include <sys/socket.h>
  75 # include <sys/wait.h>
  76 # include <pwd.h>
  77 # include <poll.h>
  78 # include <ucontext.h>
  79 
  80 address os::current_stack_pointer() {
  81   intptr_t* csp;
  82 
  83   // Inline assembly for `z_lgr regno(csp), Z_SP' (Z_SP = Z_R15):
  84   __asm__ __volatile__ ("lgr %0, 15":"=r"(csp):);
  85 
  86   assert(((uint64_t)csp & (frame::alignment_in_bytes-1)) == 0, "SP must be aligned");
  87   return (address) csp;
  88 }
  89 
  90 char* os::non_memory_address_word() {
  91   // Must never look like an address returned by reserve_memory,
  92   // even in its subfields (as defined by the CPU immediate fields,
  93   // if the CPU splits constants across multiple instructions).
  94   return (char*) -1;
  95 }
  96 
  97 // OS specific thread initialization.
  98 void os::initialize_thread(Thread* thread) { }
  99 
 100 // Frame information (pc, sp, fp) retrieved via ucontext
 101 // always looks like a C-frame according to the frame
 102 // conventions in frame_s390.hpp.
 103 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
 104   return (address)uc->uc_mcontext.psw.addr;
 105 }
 106 
 107 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
 108   uc->uc_mcontext.psw.addr = (unsigned long)pc;
 109 }
 110 
 111 static address ucontext_get_lr(const ucontext_t * uc) {
 112   return (address)uc->uc_mcontext.gregs[14/*LINK*/];
 113 }
 114 
 115 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
 116   return (intptr_t*)uc->uc_mcontext.gregs[15/*REG_SP*/];
 117 }
 118 
 119 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
 120   return NULL;
 121 }
 122 
 123 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
 124                     intptr_t** ret_sp, intptr_t** ret_fp) {
 125 
 126   ExtendedPC  epc;
 127   const ucontext_t* uc = (const ucontext_t*)ucVoid;
 128 
 129   if (uc != NULL) {
 130     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
 131     if (ret_sp) { *ret_sp = os::Linux::ucontext_get_sp(uc); }
 132     if (ret_fp) { *ret_fp = os::Linux::ucontext_get_fp(uc); }
 133   } else {
 134     // Construct empty ExtendedPC for return value checking.
 135     epc = ExtendedPC(NULL);
 136     if (ret_sp) { *ret_sp = (intptr_t *)NULL; }
 137     if (ret_fp) { *ret_fp = (intptr_t *)NULL; }
 138   }
 139 
 140   return epc;
 141 }
 142 
 143 frame os::fetch_frame_from_context(const void* ucVoid) {
 144   intptr_t* sp;
 145   intptr_t* fp;
 146   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 147   return frame(sp, epc.pc());
 148 }
 149 
 150 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
 151   address pc = (address) os::Linux::ucontext_get_pc(uc);
 152   if (Interpreter::contains(pc)) {
 153     // Interpreter performs stack banging after the fixed frame header has
 154     // been generated while the compilers perform it before. To maintain
 155     // semantic consistency between interpreted and compiled frames, the
 156     // method returns the Java sender of the current frame.
 157     *fr = os::fetch_frame_from_context(uc);
 158     if (!fr->is_first_java_frame()) {
 159       assert(fr->safe_for_sender(thread), "Safety check");
 160       *fr = fr->java_sender();
 161     }
 162   } else {
 163     // More complex code with compiled code.
 164     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
 165     CodeBlob* cb = CodeCache::find_blob(pc);
 166     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
 167       // Not sure where the pc points to, fallback to default
 168       // stack overflow handling. In compiled code, we bang before
 169       // the frame is complete.
 170       return false;
 171     } else {
 172       intptr_t* sp = os::Linux::ucontext_get_sp(uc);
 173       address lr = ucontext_get_lr(uc);
 174       *fr = frame(sp, lr);
 175       if (!fr->is_java_frame()) {
 176         assert(fr->safe_for_sender(thread), "Safety check");
 177         assert(!fr->is_first_frame(), "Safety check");
 178         *fr = fr->java_sender();
 179       }
 180     }
 181   }
 182   assert(fr->is_java_frame(), "Safety check");
 183   return true;
 184 }
 185 
 186 frame os::get_sender_for_C_frame(frame* fr) {
 187   if (*fr->sp() == 0) {
 188     // fr is the last C frame.
 189     return frame();
 190   }
 191 
 192   // If its not one of our frames, the return pc is saved at gpr14
 193   // stack slot. The call_stub stores the return_pc to the stack slot
 194   // of gpr10.
 195   if ((Interpreter::code() != NULL && Interpreter::contains(fr->pc())) ||
 196       (CodeCache::contains(fr->pc()) && !StubRoutines::contains(fr->pc()))) {
 197     return frame(fr->sender_sp(), fr->sender_pc());
 198   } else {
 199     if (StubRoutines::contains(fr->pc())) {
 200       StubCodeDesc* desc = StubCodeDesc::desc_for(fr->pc());
 201       if (desc && !strcmp(desc->name(),"call_stub")) {
 202         return frame(fr->sender_sp(), fr->callstub_sender_pc());
 203       } else {
 204         return frame(fr->sender_sp(), fr->sender_pc());
 205       }
 206     } else {
 207       return frame(fr->sender_sp(), fr->native_sender_pc());
 208     }
 209   }
 210 }
 211 
 212 frame os::current_frame() {
 213   // Expected to return the stack pointer of this method.
 214   // But if inlined, returns the stack pointer of our caller!
 215   intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());
 216   assert (csp != NULL, "sp should not be NULL");
 217   // Pass a dummy pc. This way we don't have to load it from the
 218   // stack, since we don't know in which slot we can find it.
 219   frame topframe(csp, (address)0x8);
 220   if (os::is_first_C_frame(&topframe)) {
 221     // Stack is not walkable.
 222     return frame();
 223   } else {
 224     frame senderFrame = os::get_sender_for_C_frame(&topframe);
 225     assert(senderFrame.pc() != NULL, "Sender pc should not be NULL");
 226     // Return sender of sender of current topframe which hopefully
 227     // both have pc != NULL.
 228 #ifdef _NMT_NOINLINE_   // Is set in slowdebug builds.
 229     // Current_stack_pointer is not inlined, we must pop one more frame.
 230     frame tmp = os::get_sender_for_C_frame(&topframe);
 231     return os::get_sender_for_C_frame(&tmp);
 232 #else
 233     return os::get_sender_for_C_frame(&topframe);
 234 #endif
 235   }
 236 }
 237 
 238 // Utility functions
 239 
 240 extern "C" JNIEXPORT int
 241 JVM_handle_linux_signal(int sig,
 242                         siginfo_t* info,
 243                         void* ucVoid,
 244                         int abort_if_unrecognized) {
 245   ucontext_t* uc = (ucontext_t*) ucVoid;
 246 
 247   Thread* t = Thread::current_or_null_safe();
 248 
 249   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
 250   // (no destructors can be run).
 251   os::ThreadCrashProtection::check_crash_protection(sig, t);
 252 
 253   SignalHandlerMark shm(t);
 254 
 255   // Note: it's not uncommon that JNI code uses signal/sigset to install
 256   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 257   // or have a SIGILL handler when detecting CPU type). When that happens,
 258   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
 259   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 260   // that do not require siginfo/ucontext first.
 261 
 262   if (sig == SIGPIPE) {
 263     if (os::Linux::chained_handler(sig, info, ucVoid)) {
 264       return true;
 265     } else {
 266       if (PrintMiscellaneous && (WizardMode || Verbose)) {
 267         warning("Ignoring SIGPIPE - see bug 4229104");
 268       }
 269       return true;
 270     }
 271   }
 272 
 273   JavaThread* thread = NULL;
 274   VMThread* vmthread = NULL;
 275   if (os::Linux::signal_handlers_are_installed) {
 276     if (t != NULL) {
 277       if(t->is_Java_thread()) {
 278         thread = (JavaThread*)t;
 279       } else if(t->is_VM_thread()) {
 280         vmthread = (VMThread *)t;
 281       }
 282     }
 283   }
 284 
 285   // Moved SafeFetch32 handling outside thread!=NULL conditional block to make
 286   // it work if no associated JavaThread object exists.
 287   if (uc) {
 288     address const pc = os::Linux::ucontext_get_pc(uc);
 289     if (pc && StubRoutines::is_safefetch_fault(pc)) {
 290       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
 291       return true;
 292     }
 293   }
 294 
 295   // Decide if this trap can be handled by a stub.
 296   address stub    = NULL;
 297   address pc      = NULL;  // Pc as retrieved from PSW. Usually points past failing instruction.
 298   address trap_pc = NULL;  // Pc of the instruction causing the trap.
 299 
 300   //%note os_trap_1
 301   if (info != NULL && uc != NULL && thread != NULL) {
 302     pc = os::Linux::ucontext_get_pc(uc);
 303     if (TraceTraps) {
 304       tty->print_cr("     pc at " INTPTR_FORMAT, p2i(pc));
 305     }
 306     if ((unsigned long)(pc - (address)info->si_addr) <= (unsigned long)Assembler::instr_maxlen() ) {
 307       trap_pc = (address)info->si_addr;
 308       if (TraceTraps) {
 309         tty->print_cr("trap_pc at " INTPTR_FORMAT, p2i(trap_pc));
 310       }
 311     }
 312 
 313     // Handle ALL stack overflow variations here
 314     if (sig == SIGSEGV) {
 315       address addr = (address)info->si_addr; // Address causing SIGSEGV, usually mem ref target.
 316 
 317       // Check if fault address is within thread stack.
 318       if (thread->on_local_stack(addr)) {
 319         // stack overflow
 320         if (thread->in_stack_yellow_reserved_zone(addr)) {
 321           if (thread->thread_state() == _thread_in_Java) {
 322             if (thread->in_stack_reserved_zone(addr)) {
 323               frame fr;
 324               if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
 325                 assert(fr.is_java_frame(), "Must be a Javac frame");
 326                 frame activation =
 327                   SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
 328                 if (activation.sp() != NULL) {
 329                   thread->disable_stack_reserved_zone();
 330                   if (activation.is_interpreted_frame()) {
 331                     thread->set_reserved_stack_activation((address)activation.fp());
 332                   } else {
 333                     thread->set_reserved_stack_activation((address)activation.unextended_sp());
 334                   }
 335                   return 1;
 336                 }
 337               }
 338             }
 339             // Throw a stack overflow exception.
 340             // Guard pages will be reenabled while unwinding the stack.
 341             thread->disable_stack_yellow_reserved_zone();
 342             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
 343           } else {
 344             // Thread was in the vm or native code. Return and try to finish.
 345             thread->disable_stack_yellow_reserved_zone();
 346             return 1;
 347           }
 348         } else if (thread->in_stack_red_zone(addr)) {
 349           // Fatal red zone violation.  Disable the guard pages and fall through
 350           // to handle_unexpected_exception way down below.
 351           thread->disable_stack_red_zone();
 352           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 353 
 354           // This is a likely cause, but hard to verify. Let's just print
 355           // it as a hint.
 356           tty->print_raw_cr("Please check if any of your loaded .so files has "
 357                             "enabled executable stack (see man page execstack(8))");
 358         } else {
 359           // Accessing stack address below sp may cause SEGV if current
 360           // thread has MAP_GROWSDOWN stack. This should only happen when
 361           // current thread was created by user code with MAP_GROWSDOWN flag
 362           // and then attached to VM. See notes in os_linux.cpp.
 363           if (thread->osthread()->expanding_stack() == 0) {
 364              thread->osthread()->set_expanding_stack();
 365              if (os::Linux::manually_expand_stack(thread, addr)) {
 366                thread->osthread()->clear_expanding_stack();
 367                return 1;
 368              }
 369              thread->osthread()->clear_expanding_stack();
 370           } else {
 371              fatal("recursive segv. expanding stack.");
 372           }
 373         }
 374       }
 375     }
 376 
 377     if (thread->thread_state() == _thread_in_Java) {
 378       // Java thread running in Java code => find exception handler if any
 379       // a fault inside compiled code, the interpreter, or a stub
 380 
 381       // Handle signal from NativeJump::patch_verified_entry().
 382       if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {
 383         if (TraceTraps) {
 384           tty->print_cr("trap: zombie_not_entrant (SIGILL)");
 385         }
 386         stub = SharedRuntime::get_handle_wrong_method_stub();
 387       }
 388 
 389       else if (sig == SIGSEGV &&
 390                os::is_poll_address((address)info->si_addr)) {
 391         if (TraceTraps) {
 392           tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
 393         }
 394         stub = SharedRuntime::get_poll_stub(pc);
 395 
 396         // Info->si_addr only points to the page base address, so we
 397         // must extract the real si_addr from the instruction and the
 398         // ucontext.
 399         assert(((NativeInstruction*)pc)->is_safepoint_poll(), "must be safepoint poll");
 400         const address real_si_addr = ((NativeInstruction*)pc)->get_poll_address(uc);
 401       }
 402 
 403       // SIGTRAP-based implicit null check in compiled code.
 404       else if ((sig == SIGFPE) &&
 405                TrapBasedNullChecks &&
 406                (trap_pc != NULL) &&
 407                Assembler::is_sigtrap_zero_check(trap_pc)) {
 408         if (TraceTraps) {
 409           tty->print_cr("trap: NULL_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));
 410         }
 411         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_NULL);
 412       }
 413 
 414       else if (sig == SIGSEGV && ImplicitNullChecks &&
 415                CodeCache::contains((void*) pc) &&
 416                !MacroAssembler::needs_explicit_null_check((intptr_t) info->si_addr)) {
 417         if (TraceTraps) {
 418           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
 419         }
 420         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 421       }
 422 
 423       // SIGTRAP-based implicit range check in compiled code.
 424       else if (sig == SIGFPE && TrapBasedRangeChecks &&
 425                (trap_pc != NULL) &&
 426                Assembler::is_sigtrap_range_check(trap_pc)) {
 427         if (TraceTraps) {
 428           tty->print_cr("trap: RANGE_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));
 429         }
 430         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_NULL);
 431       }
 432 
 433       else if (sig == SIGFPE && info->si_code == FPE_INTDIV) {
 434         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 435       }
 436 
 437       else if (sig == SIGBUS) {
 438         // BugId 4454115: A read from a MappedByteBuffer can fault here if the
 439         // underlying file has been truncated. Do not crash the VM in such a case.
 440         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 441         CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
 442         if (nm != NULL && nm->has_unsafe_access()) {
 443           // We don't really need a stub here! Just set the pending exeption and
 444           // continue at the next instruction after the faulting read. Returning
 445           // garbage from this read is ok.
 446           thread->set_pending_unsafe_access_error();
 447           uc->uc_mcontext.psw.addr = ((unsigned long)pc) + Assembler::instr_len(pc);
 448           return true;
 449         }
 450       }
 451     }
 452 
 453     else { // thread->thread_state() != _thread_in_Java
 454       if ((sig == SIGILL) && VM_Version::is_determine_features_test_running()) {
 455         // SIGILL must be caused by VM_Version::determine_features()
 456         // when attempting to execute a non-existing instruction.
 457         //*(int *) (pc-6)=0; // Patch instruction to 0 to indicate that it causes a SIGILL.
 458                              // Flushing of icache is not necessary.
 459         stub = pc; // Continue with next instruction.
 460       } else if ((sig == SIGFPE) && VM_Version::is_determine_features_test_running()) {
 461         // SIGFPE is known to be caused by trying to execute a vector instruction
 462         // when the vector facility is installed, but operating system support is missing.
 463         VM_Version::reset_has_VectorFacility();
 464         stub = pc; // Continue with next instruction.
 465       } else if (thread->thread_state() == _thread_in_vm &&
 466                  sig == SIGBUS && thread->doing_unsafe_access()) {
 467         // We don't really need a stub here! Just set the pending exeption and
 468         // continue at the next instruction after the faulting read. Returning
 469         // garbage from this read is ok.
 470         thread->set_pending_unsafe_access_error();
 471         os::Linux::ucontext_set_pc(uc, pc + Assembler::instr_len(pc));
 472         return true;
 473       }
 474     }
 475 
 476     // Check to see if we caught the safepoint code in the
 477     // process of write protecting the memory serialization page.
 478     // It write enables the page immediately after protecting it
 479     // so we can just return to retry the write.
 480     // Info->si_addr need not be the exact address, it is only
 481     // guaranteed to be on the same page as the address that caused
 482     // the SIGSEGV.
 483     if ((sig == SIGSEGV) && !UseMembar &&
 484         (os::get_memory_serialize_page() ==
 485          (address)((uintptr_t)info->si_addr & ~(os::vm_page_size()-1)))) {
 486       return true;
 487     }
 488   }
 489 
 490   if (stub != NULL) {
 491     // Save all thread context in case we need to restore it.
 492     if (thread != NULL) thread->set_saved_exception_pc(pc);
 493     os::Linux::ucontext_set_pc(uc, stub);
 494     return true;
 495   }
 496 
 497   // signal-chaining
 498   if (os::Linux::chained_handler(sig, info, ucVoid)) {
 499     return true;
 500   }
 501 
 502   if (!abort_if_unrecognized) {
 503     // caller wants another chance, so give it to him
 504     return false;
 505   }
 506 
 507   if (pc == NULL && uc != NULL) {
 508     pc = os::Linux::ucontext_get_pc(uc);
 509   }
 510 
 511   // unmask current signal
 512   sigset_t newset;
 513   sigemptyset(&newset);
 514   sigaddset(&newset, sig);
 515   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 516 
 517   // Hand down correct pc for SIGILL, SIGFPE. pc from context
 518   // usually points to the instruction after the failing instruction.
 519   // Note: this should be combined with the trap_pc handling above,
 520   // because it handles the same issue.
 521   if (sig == SIGILL || sig == SIGFPE) {
 522     pc = (address)info->si_addr;
 523   }
 524 
 525   VMError::report_and_die(t, sig, pc, info, ucVoid);
 526 
 527   ShouldNotReachHere();
 528   return false;
 529 }
 530 
 531 void os::Linux::init_thread_fpu_state(void) {
 532   // Nothing to do on z/Architecture.
 533 }
 534 
 535 int os::Linux::get_fpu_control_word(void) {
 536   // Nothing to do on z/Architecture.
 537   return 0;
 538 }
 539 
 540 void os::Linux::set_fpu_control_word(int fpu_control) {
 541   // Nothing to do on z/Architecture.
 542 }
 543 
 544 ////////////////////////////////////////////////////////////////////////////////
 545 // thread stack
 546 
 547 // Minimum usable stack sizes required to get to user code. Space for
 548 // HotSpot guard pages is added later.
 549 size_t os::Posix::_compiler_thread_min_stack_allowed = (52 DEBUG_ONLY(+ 32)) * K;
 550 size_t os::Posix::_java_thread_min_stack_allowed = (32 DEBUG_ONLY(+ 8)) * K;
 551 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 32 * K;
 552 
 553 // Return default stack size for thr_type.
 554 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 555   // Default stack size (compiler thread needs larger stack).
 556   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1024 * K);
 557   return s;
 558 }
 559 
 560 /////////////////////////////////////////////////////////////////////////////
 561 // helper functions for fatal error handler
 562 
 563 void os::print_context(outputStream *st, const void *context) {
 564   if (context == NULL) return;
 565 
 566   const ucontext_t* uc = (const ucontext_t*)context;
 567 
 568   st->print_cr("Processor state:");
 569   st->print_cr("----------------");
 570   st->print_cr("        ip = " INTPTR_FORMAT " ", uc->uc_mcontext.psw.addr);
 571   st->print_cr(" proc mask = " INTPTR_FORMAT " ", uc->uc_mcontext.psw.mask);
 572   st->print_cr("   fpc reg = 0x%8.8x "          , uc->uc_mcontext.fpregs.fpc);
 573   st->cr();
 574 
 575   st->print_cr("General Purpose Registers:");
 576   st->print_cr("--------------------------");
 577   for( int i = 0; i < 16; i+=2 ) {
 578     st->print("  r%-2d = " INTPTR_FORMAT "  " ,  i,   uc->uc_mcontext.gregs[i]);
 579     st->print("  r%-2d = " INTPTR_FORMAT "  |",  i+1, uc->uc_mcontext.gregs[i+1]);
 580     st->print("  r%-2d = %23.1ld  "           ,  i,   uc->uc_mcontext.gregs[i]);
 581     st->print("  r%-2d = %23.1ld  "           ,  i+1, uc->uc_mcontext.gregs[i+1]);
 582     st->cr();
 583   }
 584   st->cr();
 585 
 586   st->print_cr("Access Registers:");
 587   st->print_cr("-----------------");
 588   for( int i = 0; i < 16; i+=2 ) {
 589     st->print("  ar%-2d = 0x%8.8x  ", i,   uc->uc_mcontext.aregs[i]);
 590     st->print("  ar%-2d = 0x%8.8x  ", i+1, uc->uc_mcontext.aregs[i+1]);
 591     st->cr();
 592   }
 593   st->cr();
 594 
 595   st->print_cr("Float Registers:");
 596   st->print_cr("----------------");
 597   for (int i = 0; i < 16; i += 2) {
 598     st->print("  fr%-2d = " INTPTR_FORMAT "  " , i,   (int64_t)(uc->uc_mcontext.fpregs.fprs[i].d));
 599     st->print("  fr%-2d = " INTPTR_FORMAT "  |", i+1, (int64_t)(uc->uc_mcontext.fpregs.fprs[i+1].d));
 600     st->print("  fr%-2d = %23.15e  "           , i,   (uc->uc_mcontext.fpregs.fprs[i].d));
 601     st->print("  fr%-2d = %23.15e  "           , i+1, (uc->uc_mcontext.fpregs.fprs[i+1].d));
 602     st->cr();
 603   }
 604   st->cr();
 605   st->cr();
 606 
 607   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 608   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
 609   print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t));
 610   st->cr();
 611 
 612   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 613   // point to garbage if entry point in an nmethod is corrupted. Leave
 614   // this at the end, and hope for the best.
 615   address pc = os::Linux::ucontext_get_pc(uc);
 616   if (Verbose) { st->print_cr("pc at " PTR_FORMAT, p2i(pc)); }
 617   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
 618   print_hex_dump(st, pc-64, pc+64, /*intrsize=*/4);
 619   st->cr();
 620 }
 621 
 622 void os::print_register_info(outputStream *st, const void *context) {
 623   st->print("Not ported\n");
 624 }
 625 
 626 #ifndef PRODUCT
 627 void os::verify_stack_alignment() {
 628 }
 629 #endif
 630 
 631 int os::extra_bang_size_in_bytes() {
 632   // z/Architecture does not require the additional stack bang.
 633   return 0;
 634 }
--- EOF ---