1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2016 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 "asm/assembler.inline.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "code/icBuffer.hpp"
  34 #include "code/nativeInst.hpp"
  35 #include "code/vtableStubs.hpp"
  36 #include "compiler/disassembler.hpp"
  37 #include "interpreter/interpreter.hpp"
  38 #include "jvm_linux.h"
  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.h"
  44 #include "prims/jvm_misc.hpp"
  45 #include "runtime/arguments.hpp"
  46 #include "runtime/extendedPC.hpp"
  47 #include "runtime/frame.inline.hpp"
  48 #include "runtime/interfaceSupport.hpp"
  49 #include "runtime/java.hpp"
  50 #include "runtime/javaCalls.hpp"
  51 #include "runtime/mutexLocker.hpp"
  52 #include "runtime/osThread.hpp"
  53 #include "runtime/sharedRuntime.hpp"
  54 #include "runtime/stubRoutines.hpp"
  55 #include "runtime/thread.inline.hpp"
  56 #include "runtime/timer.hpp"
  57 #include "utilities/events.hpp"
  58 #include "utilities/vmError.hpp"
  59 
  60 // put OS-includes here
  61 # include <sys/types.h>
  62 # include <sys/mman.h>
  63 # include <pthread.h>
  64 # include <signal.h>
  65 # include <errno.h>
  66 # include <dlfcn.h>
  67 # include <stdlib.h>
  68 # include <stdio.h>
  69 # include <unistd.h>
  70 # include <sys/resource.h>
  71 # include <pthread.h>
  72 # include <sys/stat.h>
  73 # include <sys/time.h>
  74 # include <sys/utsname.h>
  75 # include <sys/socket.h>
  76 # include <sys/wait.h>
  77 # include <pwd.h>
  78 # include <poll.h>
  79 # include <ucontext.h>
  80 
  81 address os::current_stack_pointer() {
  82   intptr_t* csp;
  83 
  84   // Inline assembly for `z_lgr regno(csp), Z_SP' (Z_SP = Z_R15):
  85   __asm__ __volatile__ ("lgr %0, 15":"=r"(csp):);
  86 
  87   assert(((uint64_t)csp & (frame::alignment_in_bytes-1)) == 0, "SP must be aligned");
  88   return (address) csp;
  89 }
  90 
  91 char* os::non_memory_address_word() {
  92   // Must never look like an address returned by reserve_memory,
  93   // even in its subfields (as defined by the CPU immediate fields,
  94   // if the CPU splits constants across multiple instructions).
  95   return (char*) -1;
  96 }
  97 
  98 // OS specific thread initialization.
  99 void os::initialize_thread(Thread* thread) { }
 100 
 101 // Frame information (pc, sp, fp) retrieved via ucontext
 102 // always looks like a C-frame according to the frame
 103 // conventions in frame_s390.hpp.
 104 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
 105   return (address)uc->uc_mcontext.psw.addr;
 106 }
 107 
 108 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
 109   uc->uc_mcontext.psw.addr = (unsigned long)pc;
 110 }
 111 
 112 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
 113   return (intptr_t*)uc->uc_mcontext.gregs[15/*REG_SP*/];
 114 }
 115 
 116 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
 117   return NULL;
 118 }
 119 
 120 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
 121                     intptr_t** ret_sp, intptr_t** ret_fp) {
 122 
 123   ExtendedPC  epc;
 124   const ucontext_t* uc = (const ucontext_t*)ucVoid;
 125 
 126   if (uc != NULL) {
 127     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
 128     if (ret_sp) { *ret_sp = os::Linux::ucontext_get_sp(uc); }
 129     if (ret_fp) { *ret_fp = os::Linux::ucontext_get_fp(uc); }
 130   } else {
 131     // Construct empty ExtendedPC for return value checking.
 132     epc = ExtendedPC(NULL);
 133     if (ret_sp) { *ret_sp = (intptr_t *)NULL; }
 134     if (ret_fp) { *ret_fp = (intptr_t *)NULL; }
 135   }
 136 
 137   return epc;
 138 }
 139 
 140 frame os::fetch_frame_from_context(const void* ucVoid) {
 141   intptr_t* sp;
 142   intptr_t* fp;
 143   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 144   return frame(sp, epc.pc());
 145 }
 146 
 147 frame os::get_sender_for_C_frame(frame* fr) {
 148   if (*fr->sp() == 0) {
 149     // fr is the last C frame.
 150     return frame();
 151   }
 152 
 153   // If its not one of our frames, the return pc is saved at gpr14
 154   // stack slot. The call_stub stores the return_pc to the stack slot
 155   // of gpr10.
 156   if ((Interpreter::code() != NULL && Interpreter::contains(fr->pc())) ||
 157       (CodeCache::contains(fr->pc()) && !StubRoutines::contains(fr->pc()))) {
 158     return frame(fr->sender_sp(), fr->sender_pc());
 159   } else {
 160     if (StubRoutines::contains(fr->pc())) {
 161       StubCodeDesc* desc = StubCodeDesc::desc_for(fr->pc());
 162       if (desc && !strcmp(desc->name(),"call_stub")) {
 163         return frame(fr->sender_sp(), fr->callstub_sender_pc());
 164       } else {
 165         return frame(fr->sender_sp(), fr->sender_pc());
 166       }
 167     } else {
 168       return frame(fr->sender_sp(), fr->native_sender_pc());
 169     }
 170   }
 171 }
 172 
 173 frame os::current_frame() {
 174   intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());
 175   assert (csp != NULL, "sp should not be NULL");
 176   // Pass a dummy pc. This way we don't have to load it from the
 177   // stack, since we don't know in which slot we can find it.
 178   frame topframe(csp, (address)0x8);
 179   if (os::is_first_C_frame(&topframe)) {
 180     // Stack is not walkable.
 181     return frame();
 182   } else {
 183     frame senderFrame = os::get_sender_for_C_frame(&topframe);
 184     assert(senderFrame.pc() != NULL, "Sender pc should not be NULL");
 185     // Return sender of sender of current topframe which hopefully
 186     // both have pc != NULL.
 187     frame tmp = os::get_sender_for_C_frame(&topframe);
 188     return os::get_sender_for_C_frame(&tmp);
 189   }
 190 }
 191 
 192 // Utility functions
 193 
 194 extern "C" JNIEXPORT int
 195 JVM_handle_linux_signal(int sig,
 196                         siginfo_t* info,
 197                         void* ucVoid,
 198                         int abort_if_unrecognized) {
 199   ucontext_t* uc = (ucontext_t*) ucVoid;
 200 
 201   Thread* t = Thread::current_or_null_safe();
 202 
 203   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
 204   // (no destructors can be run).
 205   os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
 206 
 207   SignalHandlerMark shm(t);
 208 
 209   // Note: it's not uncommon that JNI code uses signal/sigset to install
 210   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 211   // or have a SIGILL handler when detecting CPU type). When that happens,
 212   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
 213   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 214   // that do not require siginfo/ucontext first.
 215 
 216   if (sig == SIGPIPE) {
 217     if (os::Linux::chained_handler(sig, info, ucVoid)) {
 218       return true;
 219     } else {
 220       if (PrintMiscellaneous && (WizardMode || Verbose)) {
 221         warning("Ignoring SIGPIPE - see bug 4229104");
 222       }
 223       return true;
 224     }
 225   }
 226 
 227   JavaThread* thread = NULL;
 228   VMThread* vmthread = NULL;
 229   if (os::Linux::signal_handlers_are_installed) {
 230     if (t != NULL) {
 231       if(t->is_Java_thread()) {
 232         thread = (JavaThread*)t;
 233       } else if(t->is_VM_thread()) {
 234         vmthread = (VMThread *)t;
 235       }
 236     }
 237   }
 238 
 239   // Moved SafeFetch32 handling outside thread!=NULL conditional block to make
 240   // it work if no associated JavaThread object exists.
 241   if (uc) {
 242     address const pc = os::Linux::ucontext_get_pc(uc);
 243     if (pc && StubRoutines::is_safefetch_fault(pc)) {
 244       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
 245       return true;
 246     }
 247   }
 248 
 249   // Decide if this trap can be handled by a stub.
 250   address stub    = NULL;
 251   address pc      = NULL;  // Pc as retrieved from PSW. Usually points past failing instruction.
 252   address trap_pc = NULL;  // Pc of the instruction causing the trap.
 253 
 254   //%note os_trap_1
 255   if (info != NULL && uc != NULL && thread != NULL) {
 256     pc = os::Linux::ucontext_get_pc(uc);
 257     if (TraceTraps) {
 258       tty->print_cr("     pc at " INTPTR_FORMAT, p2i(pc));
 259     }
 260     if ((unsigned long)(pc - (address)info->si_addr) <= (unsigned long)Assembler::instr_maxlen() ) {
 261       trap_pc = (address)info->si_addr;
 262       if (TraceTraps) {
 263         tty->print_cr("trap_pc at " INTPTR_FORMAT, p2i(trap_pc));
 264       }
 265     }
 266 
 267     // Handle ALL stack overflow variations here
 268     if (sig == SIGSEGV) {
 269       address addr = (address)info->si_addr; // Address causing SIGSEGV, usually mem ref target.
 270 
 271       // Check if fault address is within thread stack.
 272       if (thread->on_local_stack(addr)) {
 273         // stack overflow
 274         if (thread->in_stack_yellow_reserved_zone(addr)) {
 275           thread->disable_stack_yellow_reserved_zone();
 276           if (thread->thread_state() == _thread_in_Java) {
 277             // Throw a stack overflow exception.
 278             // Guard pages will be reenabled while unwinding the stack.
 279             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
 280           } else {
 281             // Thread was in the vm or native code. Return and try to finish.
 282             return 1;
 283           }
 284         } else if (thread->in_stack_red_zone(addr)) {
 285           // Fatal red zone violation.  Disable the guard pages and fall through
 286           // to handle_unexpected_exception way down below.
 287           thread->disable_stack_red_zone();
 288           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 289 
 290           // This is a likely cause, but hard to verify. Let's just print
 291           // it as a hint.
 292           tty->print_raw_cr("Please check if any of your loaded .so files has "
 293                             "enabled executable stack (see man page execstack(8))");
 294         } else {
 295           // Accessing stack address below sp may cause SEGV if current
 296           // thread has MAP_GROWSDOWN stack. This should only happen when
 297           // current thread was created by user code with MAP_GROWSDOWN flag
 298           // and then attached to VM. See notes in os_linux.cpp.
 299           if (thread->osthread()->expanding_stack() == 0) {
 300              thread->osthread()->set_expanding_stack();
 301              if (os::Linux::manually_expand_stack(thread, addr)) {
 302                thread->osthread()->clear_expanding_stack();
 303                return 1;
 304              }
 305              thread->osthread()->clear_expanding_stack();
 306           } else {
 307              fatal("recursive segv. expanding stack.");
 308           }
 309         }
 310       }
 311     }
 312 
 313     if (thread->thread_state() == _thread_in_Java) {
 314       // Java thread running in Java code => find exception handler if any
 315       // a fault inside compiled code, the interpreter, or a stub
 316 
 317       // Handle signal from NativeJump::patch_verified_entry().
 318       if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {
 319         if (TraceTraps) {
 320           tty->print_cr("trap: zombie_not_entrant (SIGILL)");
 321         }
 322         stub = SharedRuntime::get_handle_wrong_method_stub();
 323       }
 324 
 325       else if (sig == SIGSEGV &&
 326                os::is_poll_address((address)info->si_addr)) {
 327         if (TraceTraps) {
 328           tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
 329         }
 330         stub = SharedRuntime::get_poll_stub(pc);
 331 
 332         // Info->si_addr only points to the page base address, so we
 333         // must extract the real si_addr from the instruction and the
 334         // ucontext.
 335         assert(((NativeInstruction*)pc)->is_safepoint_poll(), "must be safepoint poll");
 336         const address real_si_addr = ((NativeInstruction*)pc)->get_poll_address(uc);
 337       }
 338 
 339       // SIGTRAP-based implicit null check in compiled code.
 340       else if ((sig == SIGFPE) &&
 341                TrapBasedNullChecks &&
 342                (trap_pc != NULL) &&
 343                Assembler::is_sigtrap_zero_check(trap_pc)) {
 344         if (TraceTraps) {
 345           tty->print_cr("trap: NULL_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));
 346         }
 347         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_NULL);
 348       }
 349 
 350       else if (sig == SIGSEGV && ImplicitNullChecks &&
 351                CodeCache::contains((void*) pc) &&
 352                !MacroAssembler::needs_explicit_null_check((intptr_t) info->si_addr)) {
 353         if (TraceTraps) {
 354           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
 355         }
 356         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 357       }
 358 
 359       // SIGTRAP-based implicit range check in compiled code.
 360       else if (sig == SIGFPE && TrapBasedRangeChecks &&
 361                (trap_pc != NULL) &&
 362                Assembler::is_sigtrap_range_check(trap_pc)) {
 363         if (TraceTraps) {
 364           tty->print_cr("trap: RANGE_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));
 365         }
 366         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_NULL);
 367       }
 368 
 369       else if (sig == SIGFPE && info->si_code == FPE_INTDIV) {
 370         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 371       }
 372 
 373       else if (sig == SIGBUS) {
 374         // BugId 4454115: A read from a MappedByteBuffer can fault here if the
 375         // underlying file has been truncated. Do not crash the VM in such a case.
 376         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 377         nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
 378         if (nm != NULL && nm->has_unsafe_access()) {
 379           // We don't really need a stub here! Just set the pending exeption and
 380           // continue at the next instruction after the faulting read. Returning
 381           // garbage from this read is ok.
 382           thread->set_pending_unsafe_access_error();
 383           uc->uc_mcontext.psw.addr = ((unsigned long)pc) + Assembler::instr_len(pc);
 384           return true;
 385         }
 386       }
 387     }
 388 
 389     else { // thread->thread_state() != _thread_in_Java
 390       if (sig == SIGILL && VM_Version::is_determine_features_test_running()) {
 391         // SIGILL must be caused by VM_Version::determine_features().
 392         //*(int *) (pc-6)=0; // Patch instruction to 0 to indicate that it causes a SIGILL.
 393                              // Flushing of icache is not necessary.
 394         stub = pc; // Continue with next instruction.
 395       } else if (thread->thread_state() == _thread_in_vm &&
 396                  sig == SIGBUS && thread->doing_unsafe_access()) {
 397         // We don't really need a stub here! Just set the pending exeption and
 398         // continue at the next instruction after the faulting read. Returning
 399         // garbage from this read is ok.
 400         thread->set_pending_unsafe_access_error();
 401         os::Linux::ucontext_set_pc(uc, pc + Assembler::instr_len(pc));
 402         return true;
 403       }
 404     }
 405 
 406     // Check to see if we caught the safepoint code in the
 407     // process of write protecting the memory serialization page.
 408     // It write enables the page immediately after protecting it
 409     // so we can just return to retry the write.
 410     // Info->si_addr need not be the exact address, it is only
 411     // guaranteed to be on the same page as the address that caused
 412     // the SIGSEGV.
 413     if ((sig == SIGSEGV) &&
 414         (os::get_memory_serialize_page() ==
 415          (address)((uintptr_t)info->si_addr & ~(os::vm_page_size()-1)))) {
 416       return true;
 417     }
 418   }
 419 
 420   if (stub != NULL) {
 421     // Save all thread context in case we need to restore it.
 422     if (thread != NULL) thread->set_saved_exception_pc(pc);
 423     os::Linux::ucontext_set_pc(uc, stub);
 424     return true;
 425   }
 426 
 427   // signal-chaining
 428   if (os::Linux::chained_handler(sig, info, ucVoid)) {
 429     return true;
 430   }
 431 
 432   if (!abort_if_unrecognized) {
 433     // caller wants another chance, so give it to him
 434     return false;
 435   }
 436 
 437   if (pc == NULL && uc != NULL) {
 438     pc = os::Linux::ucontext_get_pc(uc);
 439   }
 440 
 441   // unmask current signal
 442   sigset_t newset;
 443   sigemptyset(&newset);
 444   sigaddset(&newset, sig);
 445   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 446 
 447   VMError::report_and_die(t, sig, pc, info, ucVoid);
 448 
 449   ShouldNotReachHere();
 450   return false;
 451 }
 452 
 453 void os::Linux::init_thread_fpu_state(void) {
 454   // Nothing to do on z/Architecture.
 455 }
 456 
 457 int os::Linux::get_fpu_control_word(void) {
 458   // Nothing to do on z/Architecture.
 459   return 0;
 460 }
 461 
 462 void os::Linux::set_fpu_control_word(int fpu_control) {
 463   // Nothing to do on z/Architecture.
 464 }
 465 
 466 ////////////////////////////////////////////////////////////////////////////////
 467 // thread stack
 468 
 469 // These sizes exclude OS stack guard pages, but include
 470 // the VM guard pages.
 471 size_t os::Posix::_compiler_thread_min_stack_allowed = 128 * K;
 472 size_t os::Posix::_java_thread_min_stack_allowed = 128 * K;
 473 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 128 * K;
 474 
 475 // Return default stack size for thr_type.
 476 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 477   // Default stack size (compiler thread needs larger stack).
 478   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1024 * K);
 479   return s;
 480 }
 481 
 482 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
 483   // Creating guard page is very expensive. Java thread has HotSpot
 484   // guard page, only enable glibc guard page for non-Java threads.
 485   return (thr_type == java_thread ? 0 : page_size());
 486 }
 487 
 488 // Java thread:
 489 //
 490 //   Low memory addresses
 491 //    +------------------------+
 492 //    |                        |\
 493 //    |    glibc guard page    | - Right in the middle of stack, 2 pages
 494 //    |                        |/
 495 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
 496 //    |                        |\
 497 //    |  HotSpot Guard Pages   | - red and yellow pages
 498 //    |                        |/
 499 //    +------------------------+ JavaThread::stack_yellow_zone_base()
 500 //    |                        |\
 501 //    |      Normal Stack      | -
 502 //    |                        |/
 503 // P2 +------------------------+ Thread::stack_base()
 504 //
 505 // Non-Java thread:
 506 //
 507 //   Low memory addresses
 508 //    +------------------------+
 509 //    |                        |\
 510 //    |    glibc guard page    | - Right in the middle of stack, 2 pages
 511 //    |                        |/
 512 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
 513 //    |                        |\
 514 //    |      Normal Stack      | -
 515 //    |                        |/
 516 // P2 +------------------------+ Thread::stack_base()
 517 //
 518 // ** P2 is the address returned from pthread_attr_getstackaddr(), P2 - P1
 519 //    is the stack size returned by pthread_attr_getstacksize().
 520 
 521 
 522 static void current_stack_region(address * bottom, size_t * size) {
 523   if (os::Linux::is_initial_thread()) {
 524     // Initial thread needs special handling because pthread_getattr_np()
 525     // may return bogus value.
 526     *bottom = os::Linux::initial_thread_stack_bottom();
 527     *size   = os::Linux::initial_thread_stack_size();
 528   } else {
 529     pthread_attr_t attr;
 530 
 531     int rslt = pthread_getattr_np(pthread_self(), &attr);
 532 
 533     // JVM needs to know exact stack location, abort if it fails
 534     if (rslt != 0) {
 535       if (rslt == ENOMEM) {
 536         vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
 537       } else {
 538         fatal("pthread_getattr_np failed with errno = %d", rslt);
 539       }
 540     }
 541 
 542     if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
 543       fatal("Can not locate current stack attributes!");
 544     }
 545 
 546     pthread_attr_destroy(&attr);
 547 
 548   }
 549   assert(os::current_stack_pointer() >= *bottom &&
 550          os::current_stack_pointer() < *bottom + *size, "just checking");
 551 }
 552 
 553 address os::current_stack_base() {
 554   address bottom;
 555   size_t size;
 556   current_stack_region(&bottom, &size);
 557   return (bottom + size);
 558 }
 559 
 560 size_t os::current_stack_size() {
 561   // stack size includes normal stack and HotSpot guard pages
 562   address bottom;
 563   size_t size;
 564   current_stack_region(&bottom, &size);
 565   return size;
 566 }
 567 
 568 /////////////////////////////////////////////////////////////////////////////
 569 // helper functions for fatal error handler
 570 
 571 void os::print_context(outputStream *st, const void *context) {
 572   if (context == NULL) return;
 573 
 574   const ucontext_t* uc = (const ucontext_t*)context;
 575 
 576   st->print_cr("Processor state:");
 577   st->print_cr("----------------");
 578   st->print_cr("        ip = " INTPTR_FORMAT " ", uc->uc_mcontext.psw.addr);
 579   st->print_cr(" proc mask = " INTPTR_FORMAT " ", uc->uc_mcontext.psw.mask);
 580   st->print_cr("   fpc reg = 0x%8.8x "          , uc->uc_mcontext.fpregs.fpc);
 581   st->cr();
 582 
 583   st->print_cr("General Purpose Registers:");
 584   st->print_cr("--------------------------");
 585   for( int i = 0; i < 16; i+=2 ) {
 586     st->print("  r%-2d = " INTPTR_FORMAT "  " ,  i,   uc->uc_mcontext.gregs[i]);
 587     st->print("  r%-2d = " INTPTR_FORMAT "  |",  i+1, uc->uc_mcontext.gregs[i+1]);
 588     st->print("  r%-2d = %23.1ld  "           ,  i,   uc->uc_mcontext.gregs[i]);
 589     st->print("  r%-2d = %23.1ld  "           ,  i+1, uc->uc_mcontext.gregs[i+1]);
 590     st->cr();
 591   }
 592   st->cr();
 593 
 594   st->print_cr("Access Registers:");
 595   st->print_cr("-----------------");
 596   for( int i = 0; i < 16; i+=2 ) {
 597     st->print("  ar%-2d = 0x%8.8x  ", i,   uc->uc_mcontext.aregs[i]);
 598     st->print("  ar%-2d = 0x%8.8x  ", i+1, uc->uc_mcontext.aregs[i+1]);
 599     st->cr();
 600   }
 601   st->cr();
 602 
 603   st->print_cr("Float Registers:");
 604   st->print_cr("----------------");
 605   for (int i = 0; i < 16; i += 2) {
 606     st->print("  fr%-2d = " INTPTR_FORMAT "  " , i,   (int64_t)(uc->uc_mcontext.fpregs.fprs[i].d));
 607     st->print("  fr%-2d = " INTPTR_FORMAT "  |", i+1, (int64_t)(uc->uc_mcontext.fpregs.fprs[i+1].d));
 608     st->print("  fr%-2d = %23.15e  "           , i,   (uc->uc_mcontext.fpregs.fprs[i].d));
 609     st->print("  fr%-2d = %23.15e  "           , i+1, (uc->uc_mcontext.fpregs.fprs[i+1].d));
 610     st->cr();
 611   }
 612   st->cr();
 613   st->cr();
 614 
 615   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 616   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
 617   print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t));
 618   st->cr();
 619 
 620   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 621   // point to garbage if entry point in an nmethod is corrupted. Leave
 622   // this at the end, and hope for the best.
 623   address pc = os::Linux::ucontext_get_pc(uc);
 624   if (Verbose) { st->print_cr("pc at " PTR_FORMAT, p2i(pc)); }
 625   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
 626   print_hex_dump(st, pc-64, pc+64, /*intrsize=*/4);
 627   st->cr();
 628 }
 629 
 630 void os::print_register_info(outputStream *st, const void *context) {
 631   st->print("Not ported\n");
 632 }
 633 
 634 #ifndef PRODUCT
 635 void os::verify_stack_alignment() {
 636 }
 637 #endif
 638 
 639 int os::extra_bang_size_in_bytes() {
 640   // z/Architecture does not require the additional stack bang.
 641   return 0;
 642 }