1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2012, 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 // no precompiled headers
  27 #include "jvm.h"
  28 #include "asm/assembler.inline.hpp"
  29 #include "classfile/classLoader.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/vmSymbols.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/icBuffer.hpp"
  34 #include "code/vtableStubs.hpp"
  35 #include "interpreter/interpreter.hpp"
  36 #include "memory/allocation.inline.hpp"
  37 #include "nativeInst_ppc.hpp"
  38 #include "os_share_linux.hpp"
  39 #include "prims/jniFastGetField.hpp"
  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.inline.hpp"
  45 #include "runtime/java.hpp"
  46 #include "runtime/javaCalls.hpp"
  47 #include "runtime/mutexLocker.hpp"
  48 #include "runtime/osThread.hpp"
  49 #include "runtime/safepointMechanism.hpp"
  50 #include "runtime/sharedRuntime.hpp"
  51 #include "runtime/stubRoutines.hpp"
  52 #include "runtime/thread.inline.hpp"
  53 #include "runtime/timer.hpp"
  54 #include "utilities/events.hpp"
  55 #include "utilities/vmError.hpp"
  56 
  57 // put OS-includes here
  58 # include <sys/types.h>
  59 # include <sys/mman.h>
  60 # include <pthread.h>
  61 # include <signal.h>
  62 # include <errno.h>
  63 # include <dlfcn.h>
  64 # include <stdlib.h>
  65 # include <stdio.h>
  66 # include <unistd.h>
  67 # include <sys/resource.h>
  68 # include <pthread.h>
  69 # include <sys/stat.h>
  70 # include <sys/time.h>
  71 # include <sys/utsname.h>
  72 # include <sys/socket.h>
  73 # include <sys/wait.h>
  74 # include <pwd.h>
  75 # include <poll.h>
  76 # include <ucontext.h>
  77 
  78 
  79 address os::current_stack_pointer() {
  80   intptr_t* csp;
  81 
  82   // inline assembly `mr regno(csp), R1_SP':
  83   __asm__ __volatile__ ("mr %0, 1":"=r"(csp):);
  84 
  85   return (address) csp;
  86 }
  87 
  88 char* os::non_memory_address_word() {
  89   // Must never look like an address returned by reserve_memory,
  90   // even in its subfields (as defined by the CPU immediate fields,
  91   // if the CPU splits constants across multiple instructions).
  92 
  93   return (char*) -1;
  94 }
  95 
  96 void os::initialize_thread(Thread *thread) { }
  97 
  98 // Frame information (pc, sp, fp) retrieved via ucontext
  99 // always looks like a C-frame according to the frame
 100 // conventions in frame_ppc64.hpp.
 101 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
 102   // On powerpc64, ucontext_t is not selfcontained but contains
 103   // a pointer to an optional substructure (mcontext_t.regs) containing the volatile
 104   // registers - NIP, among others.
 105   // This substructure may or may not be there depending where uc came from:
 106   // - if uc was handed over as the argument to a sigaction handler, a pointer to the
 107   //   substructure was provided by the kernel when calling the signal handler, and
 108   //   regs->nip can be accessed.
 109   // - if uc was filled by getcontext(), it is undefined - getcontext() does not fill
 110   //   it because the volatile registers are not needed to make setcontext() work.
 111   //   Hopefully it was zero'd out beforehand.
 112   guarantee(uc->uc_mcontext.regs != NULL, "only use ucontext_get_pc in sigaction context");
 113   return (address)uc->uc_mcontext.regs->nip;
 114 }
 115 
 116 // modify PC in ucontext.
 117 // Note: Only use this for an ucontext handed down to a signal handler. See comment
 118 // in ucontext_get_pc.
 119 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
 120   guarantee(uc->uc_mcontext.regs != NULL, "only use ucontext_set_pc in sigaction context");
 121   uc->uc_mcontext.regs->nip = (unsigned long)pc;
 122 }
 123 
 124 static address ucontext_get_lr(const ucontext_t * uc) {
 125   return (address)uc->uc_mcontext.regs->link;
 126 }
 127 
 128 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
 129   return (intptr_t*)uc->uc_mcontext.regs->gpr[1/*REG_SP*/];
 130 }
 131 
 132 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
 133   return NULL;
 134 }
 135 
 136 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
 137                     intptr_t** ret_sp, intptr_t** ret_fp) {
 138 
 139   ExtendedPC  epc;
 140   const ucontext_t* uc = (const ucontext_t*)ucVoid;
 141 
 142   if (uc != NULL) {
 143     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
 144     if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
 145     if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
 146   } else {
 147     // construct empty ExtendedPC for return value checking
 148     epc = ExtendedPC(NULL);
 149     if (ret_sp) *ret_sp = (intptr_t *)NULL;
 150     if (ret_fp) *ret_fp = (intptr_t *)NULL;
 151   }
 152 
 153   return epc;
 154 }
 155 
 156 frame os::fetch_frame_from_context(const void* ucVoid) {
 157   intptr_t* sp;
 158   intptr_t* fp;
 159   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 160   return frame(sp, epc.pc());
 161 }
 162 
 163 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
 164   address pc = (address) os::Linux::ucontext_get_pc(uc);
 165   if (Interpreter::contains(pc)) {
 166     // Interpreter performs stack banging after the fixed frame header has
 167     // been generated while the compilers perform it before. To maintain
 168     // semantic consistency between interpreted and compiled frames, the
 169     // method returns the Java sender of the current frame.
 170     *fr = os::fetch_frame_from_context(uc);
 171     if (!fr->is_first_java_frame()) {
 172       assert(fr->safe_for_sender(thread), "Safety check");
 173       *fr = fr->java_sender();
 174     }
 175   } else {
 176     // More complex code with compiled code.
 177     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
 178     CodeBlob* cb = CodeCache::find_blob(pc);
 179     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
 180       // Not sure where the pc points to, fallback to default
 181       // stack overflow handling. In compiled code, we bang before
 182       // the frame is complete.
 183       return false;
 184     } else {
 185       intptr_t* sp = os::Linux::ucontext_get_sp(uc);
 186       address lr = ucontext_get_lr(uc);
 187       *fr = frame(sp, lr);
 188       if (!fr->is_java_frame()) {
 189         assert(fr->safe_for_sender(thread), "Safety check");
 190         assert(!fr->is_first_frame(), "Safety check");
 191         *fr = fr->java_sender();
 192       }
 193     }
 194   }
 195   assert(fr->is_java_frame(), "Safety check");
 196   return true;
 197 }
 198 
 199 frame os::get_sender_for_C_frame(frame* fr) {
 200   if (*fr->sp() == 0) {
 201     // fr is the last C frame
 202     return frame(NULL, NULL);
 203   }
 204   return frame(fr->sender_sp(), fr->sender_pc());
 205 }
 206 
 207 
 208 frame os::current_frame() {
 209   intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());
 210   // hack.
 211   frame topframe(csp, (address)0x8);
 212   // Return sender of sender of current topframe which hopefully
 213   // both have pc != NULL.
 214   frame tmp = os::get_sender_for_C_frame(&topframe);
 215   return os::get_sender_for_C_frame(&tmp);
 216 }
 217 
 218 // Utility functions
 219 
 220 extern "C" JNIEXPORT int
 221 JVM_handle_linux_signal(int sig,
 222                         siginfo_t* info,
 223                         void* ucVoid,
 224                         int abort_if_unrecognized) {
 225   ucontext_t* uc = (ucontext_t*) ucVoid;
 226 
 227   Thread* t = Thread::current_or_null_safe();
 228 
 229   SignalHandlerMark shm(t);
 230 
 231   // Note: it's not uncommon that JNI code uses signal/sigset to install
 232   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 233   // or have a SIGILL handler when detecting CPU type). When that happens,
 234   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
 235   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 236   // that do not require siginfo/ucontext first.
 237 
 238   if (sig == SIGPIPE) {
 239     if (os::Linux::chained_handler(sig, info, ucVoid)) {
 240       return true;
 241     } else {
 242       // Ignoring SIGPIPE - see bugs 4229104
 243       return true;
 244     }
 245   }
 246 
 247   // Make the signal handler transaction-aware by checking the existence of a
 248   // second (transactional) context with MSR TS bits active. If the signal is
 249   // caught during a transaction, then just return to the HTM abort handler.
 250   // Please refer to Linux kernel document powerpc/transactional_memory.txt,
 251   // section "Signals".
 252   if (uc && uc->uc_link) {
 253     ucontext_t* second_uc = uc->uc_link;
 254 
 255     // MSR TS bits are 29 and 30 (Power ISA, v2.07B, Book III-S, pp. 857-858,
 256     // 3.2.1 "Machine State Register"), however note that ISA notation for bit
 257     // numbering is MSB 0, so for normal bit numbering (LSB 0) they come to be
 258     // bits 33 and 34. It's not related to endianness, just a notation matter.
 259     if (second_uc->uc_mcontext.regs->msr & 0x600000000) {
 260       if (TraceTraps) {
 261         tty->print_cr("caught signal in transaction, "
 262                         "ignoring to jump to abort handler");
 263       }
 264       // Return control to the HTM abort handler.
 265       return true;
 266     }
 267   }
 268 
 269   JavaThread* thread = NULL;
 270   VMThread* vmthread = NULL;
 271   if (os::Linux::signal_handlers_are_installed) {
 272     if (t != NULL) {
 273       if(t->is_Java_thread()) {
 274         thread = (JavaThread*)t;
 275       } else if(t->is_VM_thread()) {
 276         vmthread = (VMThread *)t;
 277       }
 278     }
 279   }
 280 
 281   // Moved SafeFetch32 handling outside thread!=NULL conditional block to make
 282   // it work if no associated JavaThread object exists.
 283   if (uc) {
 284     address const pc = os::Linux::ucontext_get_pc(uc);
 285     if (pc && StubRoutines::is_safefetch_fault(pc)) {
 286       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
 287       return true;
 288     }
 289   }
 290 
 291   // decide if this trap can be handled by a stub
 292   address stub = NULL;
 293   address pc   = NULL;
 294 
 295   //%note os_trap_1
 296   if (info != NULL && uc != NULL && thread != NULL) {
 297     pc = (address) os::Linux::ucontext_get_pc(uc);
 298 
 299     // Handle ALL stack overflow variations here
 300     if (sig == SIGSEGV) {
 301       // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see
 302       // comment below). Use get_stack_bang_address instead of si_addr.
 303       address addr = ((NativeInstruction*)pc)->get_stack_bang_address(uc);
 304 
 305       // Check if fault address is within thread stack.
 306       if (thread->on_local_stack(addr)) {
 307         // stack overflow
 308         if (thread->in_stack_yellow_reserved_zone(addr)) {
 309           if (thread->thread_state() == _thread_in_Java) {
 310             if (thread->in_stack_reserved_zone(addr)) {
 311               frame fr;
 312               if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
 313                 assert(fr.is_java_frame(), "Must be a Javac frame");
 314                 frame activation =
 315                   SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
 316                 if (activation.sp() != NULL) {
 317                   thread->disable_stack_reserved_zone();
 318                   if (activation.is_interpreted_frame()) {
 319                     thread->set_reserved_stack_activation((address)activation.fp());
 320                   } else {
 321                     thread->set_reserved_stack_activation((address)activation.unextended_sp());
 322                   }
 323                   return 1;
 324                 }
 325               }
 326             }
 327             // Throw a stack overflow exception.
 328             // Guard pages will be reenabled while unwinding the stack.
 329             thread->disable_stack_yellow_reserved_zone();
 330             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
 331           } else {
 332             // Thread was in the vm or native code. Return and try to finish.
 333             thread->disable_stack_yellow_reserved_zone();
 334             return 1;
 335           }
 336         } else if (thread->in_stack_red_zone(addr)) {
 337           // Fatal red zone violation.  Disable the guard pages and fall through
 338           // to handle_unexpected_exception way down below.
 339           thread->disable_stack_red_zone();
 340           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 341 
 342           // This is a likely cause, but hard to verify. Let's just print
 343           // it as a hint.
 344           tty->print_raw_cr("Please check if any of your loaded .so files has "
 345                             "enabled executable stack (see man page execstack(8))");
 346         } else {
 347           // Accessing stack address below sp may cause SEGV if current
 348           // thread has MAP_GROWSDOWN stack. This should only happen when
 349           // current thread was created by user code with MAP_GROWSDOWN flag
 350           // and then attached to VM. See notes in os_linux.cpp.
 351           if (thread->osthread()->expanding_stack() == 0) {
 352              thread->osthread()->set_expanding_stack();
 353              if (os::Linux::manually_expand_stack(thread, addr)) {
 354                thread->osthread()->clear_expanding_stack();
 355                return 1;
 356              }
 357              thread->osthread()->clear_expanding_stack();
 358           } else {
 359              fatal("recursive segv. expanding stack.");
 360           }
 361         }
 362       }
 363     }
 364 
 365     if (thread->thread_state() == _thread_in_Java) {
 366       // Java thread running in Java code => find exception handler if any
 367       // a fault inside compiled code, the interpreter, or a stub
 368 
 369       // A VM-related SIGILL may only occur if we are not in the zero page.
 370       // On AIX, we get a SIGILL if we jump to 0x0 or to somewhere else
 371       // in the zero page, because it is filled with 0x0. We ignore
 372       // explicit SIGILLs in the zero page.
 373       if (sig == SIGILL && (pc < (address) 0x200)) {
 374         if (TraceTraps) {
 375           tty->print_raw_cr("SIGILL happened inside zero page.");
 376         }
 377         goto report_and_die;
 378       }
 379 
 380       CodeBlob *cb = NULL;
 381       // Handle signal from NativeJump::patch_verified_entry().
 382       if (( TrapBasedNotEntrantChecks && sig == SIGTRAP && nativeInstruction_at(pc)->is_sigtrap_zombie_not_entrant()) ||
 383           (!TrapBasedNotEntrantChecks && sig == SIGILL  && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant())) {
 384         if (TraceTraps) {
 385           tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
 386         }
 387         stub = SharedRuntime::get_handle_wrong_method_stub();
 388       }
 389 
 390       else if (sig == ((SafepointMechanism::uses_thread_local_poll() && USE_POLL_BIT_ONLY) ? SIGTRAP : SIGSEGV) &&
 391                // A linux-ppc64 kernel before 2.6.6 doesn't set si_addr on some segfaults
 392                // in 64bit mode (cf. http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.6),
 393                // especially when we try to read from the safepoint polling page. So the check
 394                //   (address)info->si_addr == os::get_standard_polling_page()
 395                // doesn't work for us. We use:
 396                ((NativeInstruction*)pc)->is_safepoint_poll() &&
 397                CodeCache::contains((void*) pc) &&
 398                ((cb = CodeCache::find_blob(pc)) != NULL) &&
 399                cb->is_compiled()) {
 400         if (TraceTraps) {
 401           tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (%s)", p2i(pc),
 402                         (SafepointMechanism::uses_thread_local_poll() && USE_POLL_BIT_ONLY) ? "SIGTRAP" : "SIGSEGV");
 403         }
 404         stub = SharedRuntime::get_poll_stub(pc);
 405       }
 406 
 407       // SIGTRAP-based ic miss check in compiled code.
 408       else if (sig == SIGTRAP && TrapBasedICMissChecks &&
 409                nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) {
 410         if (TraceTraps) {
 411           tty->print_cr("trap: ic_miss_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
 412         }
 413         stub = SharedRuntime::get_ic_miss_stub();
 414       }
 415 
 416       // SIGTRAP-based implicit null check in compiled code.
 417       else if (sig == SIGTRAP && TrapBasedNullChecks &&
 418                nativeInstruction_at(pc)->is_sigtrap_null_check()) {
 419         if (TraceTraps) {
 420           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
 421         }
 422         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 423       }
 424 
 425       // SIGSEGV-based implicit null check in compiled code.
 426       else if (sig == SIGSEGV && ImplicitNullChecks &&
 427                CodeCache::contains((void*) pc) &&
 428                !MacroAssembler::needs_explicit_null_check((intptr_t) info->si_addr)) {
 429         if (TraceTraps) {
 430           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
 431         }
 432         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 433       }
 434 
 435 #ifdef COMPILER2
 436       // SIGTRAP-based implicit range check in compiled code.
 437       else if (sig == SIGTRAP && TrapBasedRangeChecks &&
 438                nativeInstruction_at(pc)->is_sigtrap_range_check()) {
 439         if (TraceTraps) {
 440           tty->print_cr("trap: range_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
 441         }
 442         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 443       }
 444 #endif
 445       else if (sig == SIGBUS) {
 446         // BugId 4454115: A read from a MappedByteBuffer can fault here if the
 447         // underlying file has been truncated. Do not crash the VM in such a case.
 448         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 449         CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
 450         if (nm != NULL && nm->has_unsafe_access()) {
 451           address next_pc = pc + 4;
 452           next_pc = SharedRuntime::handle_unsafe_access(thread, next_pc);
 453           os::Linux::ucontext_set_pc(uc, next_pc);
 454           return true;
 455         }
 456       }
 457     }
 458 
 459     else { // thread->thread_state() != _thread_in_Java
 460       if (sig == SIGILL && VM_Version::is_determine_features_test_running()) {
 461         // SIGILL must be caused by VM_Version::determine_features().
 462         *(int *)pc = 0; // patch instruction to 0 to indicate that it causes a SIGILL,
 463                         // flushing of icache is not necessary.
 464         stub = pc + 4;  // continue with next instruction.
 465       }
 466       else if (thread->thread_state() == _thread_in_vm &&
 467                sig == SIGBUS && thread->doing_unsafe_access()) {
 468         address next_pc = pc + 4;
 469         next_pc = SharedRuntime::handle_unsafe_access(thread, next_pc);
 470         os::Linux::ucontext_set_pc(uc, pc + 4);
 471         return true;
 472       }
 473     }
 474 
 475     // Check to see if we caught the safepoint code in the
 476     // process of write protecting the memory serialization page.
 477     // It write enables the page immediately after protecting it
 478     // so we can just return to retry the write.
 479     if ((sig == SIGSEGV) &&
 480         // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see comment above).
 481         // Use is_memory_serialization instead of si_addr.
 482         ((NativeInstruction*)pc)->is_memory_serialization(thread, ucVoid)) {
 483       // Synchronization problem in the pseudo memory barrier code (bug id 6546278)
 484       // Block current thread until the memory serialize page permission restored.
 485       os::block_on_serialize_page_trap();
 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 report_and_die:
 512   // unmask current signal
 513   sigset_t newset;
 514   sigemptyset(&newset);
 515   sigaddset(&newset, sig);
 516   sigprocmask(SIG_UNBLOCK, &newset, NULL);
 517 
 518   VMError::report_and_die(t, sig, pc, info, ucVoid);
 519 
 520   ShouldNotReachHere();
 521   return false;
 522 }
 523 
 524 void os::Linux::init_thread_fpu_state(void) {
 525   // Disable FP exceptions.
 526   __asm__ __volatile__ ("mtfsfi 6,0");
 527 }
 528 
 529 int os::Linux::get_fpu_control_word(void) {
 530   // x86 has problems with FPU precision after pthread_cond_timedwait().
 531   // nothing to do on ppc64.
 532   return 0;
 533 }
 534 
 535 void os::Linux::set_fpu_control_word(int fpu_control) {
 536   // x86 has problems with FPU precision after pthread_cond_timedwait().
 537   // nothing to do on ppc64.
 538 }
 539 
 540 ////////////////////////////////////////////////////////////////////////////////
 541 // thread stack
 542 
 543 // Minimum usable stack sizes required to get to user code. Space for
 544 // HotSpot guard pages is added later.
 545 size_t os::Posix::_compiler_thread_min_stack_allowed = 64 * K;
 546 size_t os::Posix::_java_thread_min_stack_allowed = 64 * K;
 547 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
 548 
 549 // Return default stack size for thr_type.
 550 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 551   // Default stack size (compiler thread needs larger stack).
 552   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1024 * K);
 553   return s;
 554 }
 555 
 556 /////////////////////////////////////////////////////////////////////////////
 557 // helper functions for fatal error handler
 558 
 559 void os::print_context(outputStream *st, const void *context) {
 560   if (context == NULL) return;
 561 
 562   const ucontext_t* uc = (const ucontext_t*)context;
 563 
 564   st->print_cr("Registers:");
 565   st->print("pc =" INTPTR_FORMAT "  ", uc->uc_mcontext.regs->nip);
 566   st->print("lr =" INTPTR_FORMAT "  ", uc->uc_mcontext.regs->link);
 567   st->print("ctr=" INTPTR_FORMAT "  ", uc->uc_mcontext.regs->ctr);
 568   st->cr();
 569   for (int i = 0; i < 32; i++) {
 570     st->print("r%-2d=" INTPTR_FORMAT "  ", i, uc->uc_mcontext.regs->gpr[i]);
 571     if (i % 3 == 2) st->cr();
 572   }
 573   st->cr();
 574   st->cr();
 575 
 576   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
 577   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
 578   print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t));
 579   st->cr();
 580 
 581   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 582   // point to garbage if entry point in an nmethod is corrupted. Leave
 583   // this at the end, and hope for the best.
 584   address pc = os::Linux::ucontext_get_pc(uc);
 585   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
 586   print_hex_dump(st, pc - 64, pc + 64, /*instrsize=*/4);
 587   st->cr();
 588 }
 589 
 590 void os::print_register_info(outputStream *st, const void *context) {
 591   if (context == NULL) return;
 592 
 593   const ucontext_t *uc = (const ucontext_t*)context;
 594 
 595   st->print_cr("Register to memory mapping:");
 596   st->cr();
 597 
 598   // this is only for the "general purpose" registers
 599   for (int i = 0; i < 32; i++) {
 600     st->print("r%-2d=", i);
 601     print_location(st, uc->uc_mcontext.regs->gpr[i]);
 602   }
 603   st->cr();
 604 }
 605 
 606 extern "C" {
 607   int SpinPause() {
 608     return 0;
 609   }
 610 }
 611 
 612 #ifndef PRODUCT
 613 void os::verify_stack_alignment() {
 614   assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
 615 }
 616 #endif
 617 
 618 int os::extra_bang_size_in_bytes() {
 619   // PPC does not require the additional stack bang.
 620   return 0;
 621 }
--- EOF ---