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) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2012, 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 // no precompiled headers
  27 #include "asm/assembler.inline.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/icBuffer.hpp"
  33 #include "code/vtableStubs.hpp"
  34 #include "interpreter/interpreter.hpp"
  35 #include "jvm_aix.h"
  36 #include "memory/allocation.inline.hpp"
  37 #include "nativeInst_ppc.hpp"
  38 #include "os_share_aix.hpp"
  39 #include "prims/jniFastGetField.hpp"
  40 #include "prims/jvm.h"
  41 #include "prims/jvm_misc.hpp"
  42 #include "porting_aix.hpp"
  43 #include "runtime/arguments.hpp"
  44 #include "runtime/extendedPC.hpp"
  45 #include "runtime/frame.inline.hpp"
  46 #include "runtime/interfaceSupport.hpp"
  47 #include "runtime/java.hpp"
  48 #include "runtime/javaCalls.hpp"
  49 #include "runtime/mutexLocker.hpp"
  50 #include "runtime/osThread.hpp"
  51 #include "runtime/sharedRuntime.hpp"
  52 #include "runtime/stubRoutines.hpp"
  53 #include "runtime/thread.inline.hpp"
  54 #include "runtime/timer.hpp"
  55 #include "utilities/events.hpp"
  56 #include "utilities/vmError.hpp"
  57 #ifdef COMPILER1
  58 #include "c1/c1_Runtime1.hpp"
  59 #endif
  60 #ifdef COMPILER2
  61 #include "opto/runtime.hpp"
  62 #endif
  63 
  64 // put OS-includes here
  65 # include <ucontext.h>
  66 
  67 address os::current_stack_pointer() {
  68   address csp;
  69 
  70 #if !defined(USE_XLC_BUILTINS)
  71   // inline assembly for `mr regno(csp), R1_SP':
  72   __asm__ __volatile__ ("mr %0, 1":"=r"(csp):);
  73 #else
  74   csp = (address) __builtin_frame_address(0);
  75 #endif
  76 
  77   return csp;
  78 }
  79 
  80 char* os::non_memory_address_word() {
  81   // Must never look like an address returned by reserve_memory,
  82   // even in its subfields (as defined by the CPU immediate fields,
  83   // if the CPU splits constants across multiple instructions).
  84 
  85   return (char*) -1;
  86 }
  87 
  88 // OS specific thread initialization
  89 //
  90 // Calculate and store the limits of the memory stack.
  91 void os::initialize_thread(Thread *thread) { }
  92 
  93 // Frame information (pc, sp, fp) retrieved via ucontext
  94 // always looks like a C-frame according to the frame
  95 // conventions in frame_ppc.hpp.
  96 
  97 address os::Aix::ucontext_get_pc(const ucontext_t * uc) {
  98   return (address)uc->uc_mcontext.jmp_context.iar;
  99 }
 100 
 101 intptr_t* os::Aix::ucontext_get_sp(const ucontext_t * uc) {
 102   // gpr1 holds the stack pointer on aix
 103   return (intptr_t*)uc->uc_mcontext.jmp_context.gpr[1/*REG_SP*/];
 104 }
 105 
 106 intptr_t* os::Aix::ucontext_get_fp(const ucontext_t * uc) {
 107   return NULL;
 108 }
 109 
 110 void os::Aix::ucontext_set_pc(ucontext_t* uc, address new_pc) {
 111   uc->uc_mcontext.jmp_context.iar = (uint64_t) new_pc;
 112 }
 113 
 114 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
 115                                         intptr_t** ret_sp, intptr_t** ret_fp) {
 116 
 117   ExtendedPC  epc;
 118   const ucontext_t* uc = (const ucontext_t*)ucVoid;
 119 
 120   if (uc != NULL) {
 121     epc = ExtendedPC(os::Aix::ucontext_get_pc(uc));
 122     if (ret_sp) *ret_sp = os::Aix::ucontext_get_sp(uc);
 123     if (ret_fp) *ret_fp = os::Aix::ucontext_get_fp(uc);
 124   } else {
 125     // construct empty ExtendedPC for return value checking
 126     epc = ExtendedPC(NULL);
 127     if (ret_sp) *ret_sp = (intptr_t *)NULL;
 128     if (ret_fp) *ret_fp = (intptr_t *)NULL;
 129   }
 130 
 131   return epc;
 132 }
 133 
 134 frame os::fetch_frame_from_context(const void* ucVoid) {
 135   intptr_t* sp;
 136   intptr_t* fp;
 137   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
 138   // Avoid crash during crash if pc broken.
 139   if (epc.pc()) {
 140     frame fr(sp, epc.pc());
 141     return fr;
 142   }
 143   frame fr(sp);
 144   return fr;
 145 }
 146 
 147 bool os::Aix::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
 148   address pc = (address) os::Aix::ucontext_get_pc(uc);
 149   if (Interpreter::contains(pc)) {
 150     // Interpreter performs stack banging after the fixed frame header has
 151     // been generated while the compilers perform it before. To maintain
 152     // semantic consistency between interpreted and compiled frames, the
 153     // method returns the Java sender of the current frame.
 154     *fr = os::fetch_frame_from_context(uc);
 155     if (!fr->is_first_java_frame()) {
 156       assert(fr->safe_for_sender(thread), "Safety check");
 157       *fr = fr->java_sender();
 158     }
 159   } else {
 160     // More complex code with compiled code.
 161     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
 162     CodeBlob* cb = CodeCache::find_blob(pc);
 163     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
 164       // Not sure where the pc points to, fallback to default
 165       // stack overflow handling. In compiled code, we bang before
 166       // the frame is complete.
 167       return false;
 168     } else {
 169       intptr_t* sp = os::Aix::ucontext_get_sp(uc);
 170       *fr = frame(sp, (address)*sp);
 171       if (!fr->is_java_frame()) {
 172         assert(fr->safe_for_sender(thread), "Safety check");
 173         assert(!fr->is_first_frame(), "Safety check");
 174         *fr = fr->java_sender();
 175       }
 176     }
 177   }
 178   assert(fr->is_java_frame(), "Safety check");
 179   return true;
 180 }
 181 
 182 frame os::get_sender_for_C_frame(frame* fr) {
 183   if (*fr->sp() == NULL) {
 184     // fr is the last C frame
 185     return frame(NULL, NULL);
 186   }
 187   return frame(fr->sender_sp(), fr->sender_pc());
 188 }
 189 
 190 
 191 frame os::current_frame() {
 192   intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());
 193   // hack.
 194   frame topframe(csp, (address)0x8);
 195   // Return sender of sender of current topframe which hopefully
 196   // both have pc != NULL.
 197   frame tmp = os::get_sender_for_C_frame(&topframe);
 198   return os::get_sender_for_C_frame(&tmp);
 199 }
 200 
 201 // Utility functions
 202 
 203 extern "C" JNIEXPORT int
 204 JVM_handle_aix_signal(int sig, siginfo_t* info, void* ucVoid, int abort_if_unrecognized) {
 205 
 206   ucontext_t* uc = (ucontext_t*) ucVoid;
 207 
 208   Thread* t = Thread::current_or_null_safe();
 209 
 210   SignalHandlerMark shm(t);
 211 
 212   // Note: it's not uncommon that JNI code uses signal/sigset to install
 213   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
 214   // or have a SIGILL handler when detecting CPU type). When that happens,
 215   // JVM_handle_aix_signal() might be invoked with junk info/ucVoid. To
 216   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
 217   // that do not require siginfo/ucontext first.
 218 
 219   if (sig == SIGPIPE) {
 220     if (os::Aix::chained_handler(sig, info, ucVoid)) {
 221       return 1;
 222     } else {
 223       // Ignoring SIGPIPE - see bugs 4229104
 224       return 1;
 225     }
 226   }
 227 
 228   JavaThread* thread = NULL;
 229   VMThread* vmthread = NULL;
 230   if (os::Aix::signal_handlers_are_installed) {
 231     if (t != NULL) {
 232       if(t->is_Java_thread()) {
 233         thread = (JavaThread*)t;
 234       }
 235       else if(t->is_VM_thread()) {
 236         vmthread = (VMThread *)t;
 237       }
 238     }
 239   }
 240 
 241   // Decide if this trap can be handled by a stub.
 242   address stub = NULL;
 243 
 244   // retrieve program counter
 245   address const pc = uc ? os::Aix::ucontext_get_pc(uc) : NULL;
 246 
 247   // retrieve crash address
 248   address const addr = info ? (const address) info->si_addr : NULL;
 249 
 250   // SafeFetch 32 handling:
 251   // - make it work if _thread is null
 252   // - make it use the standard os::...::ucontext_get/set_pc APIs
 253   if (uc) {
 254     address const pc = os::Aix::ucontext_get_pc(uc);
 255     if (pc && StubRoutines::is_safefetch_fault(pc)) {
 256       os::Aix::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
 257       return true;
 258     }
 259   }
 260 
 261   // Handle SIGDANGER right away. AIX would raise SIGDANGER whenever available swap
 262   // space falls below 30%. This is only a chance for the process to gracefully abort.
 263   // We can't hope to proceed after SIGDANGER since SIGKILL tailgates.
 264   if (sig == SIGDANGER) {
 265     goto report_and_die;
 266   }
 267 
 268   if (info == NULL || uc == NULL || thread == NULL && vmthread == NULL) {
 269     goto run_chained_handler;
 270   }
 271 
 272   // If we are a java thread...
 273   if (thread != NULL) {
 274 
 275     // Handle ALL stack overflow variations here
 276     if (sig == SIGSEGV && thread->on_local_stack(addr)) {
 277       // stack overflow
 278       //
 279       // If we are in a yellow zone and we are inside java, we disable the yellow zone and
 280       // throw a stack overflow exception.
 281       // If we are in native code or VM C code, we report-and-die. The original coding tried
 282       // to continue with yellow zone disabled, but that doesn't buy us much and prevents
 283       // hs_err_pid files.
 284       if (thread->in_stack_yellow_reserved_zone(addr)) {
 285         if (thread->thread_state() == _thread_in_Java) {
 286             if (thread->in_stack_reserved_zone(addr)) {
 287               frame fr;
 288               if (os::Aix::get_frame_at_stack_banging_point(thread, uc, &fr)) {
 289                 assert(fr.is_java_frame(), "Must be a Javac frame");
 290                 frame activation =
 291                   SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
 292                 if (activation.sp() != NULL) {
 293                   thread->disable_stack_reserved_zone();
 294                   if (activation.is_interpreted_frame()) {
 295                     thread->set_reserved_stack_activation((address)activation.fp());
 296                   } else {
 297                     thread->set_reserved_stack_activation((address)activation.unextended_sp());
 298                   }
 299                   return 1;
 300                 }
 301               }
 302             }
 303           // Throw a stack overflow exception.
 304           // Guard pages will be reenabled while unwinding the stack.
 305           thread->disable_stack_yellow_reserved_zone();
 306           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
 307           goto run_stub;
 308         } else {
 309           // Thread was in the vm or native code. Return and try to finish.
 310           thread->disable_stack_yellow_reserved_zone();
 311           return 1;
 312         }
 313       } else if (thread->in_stack_red_zone(addr)) {
 314         // Fatal red zone violation. Disable the guard pages and fall through
 315         // to handle_unexpected_exception way down below.
 316         thread->disable_stack_red_zone();
 317         tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
 318         goto report_and_die;
 319       } else {
 320         // This means a segv happened inside our stack, but not in
 321         // the guarded zone. I'd like to know when this happens,
 322         tty->print_raw_cr("SIGSEGV happened inside stack but outside yellow and red zone.");
 323         goto report_and_die;
 324       }
 325 
 326     } // end handle SIGSEGV inside stack boundaries
 327 
 328     if (thread->thread_state() == _thread_in_Java) {
 329       // Java thread running in Java code
 330 
 331       // The following signals are used for communicating VM events:
 332       //
 333       // SIGILL: the compiler generates illegal opcodes
 334       //   at places where it wishes to interrupt the VM:
 335       //   Safepoints, Unreachable Code, Entry points of Zombie methods,
 336       //    This results in a SIGILL with (*pc) == inserted illegal instruction.
 337       //
 338       //   (so, SIGILLs with a pc inside the zero page are real errors)
 339       //
 340       // SIGTRAP:
 341       //   The ppc trap instruction raises a SIGTRAP and is very efficient if it
 342       //   does not trap. It is used for conditional branches that are expected
 343       //   to be never taken. These are:
 344       //     - zombie methods
 345       //     - IC (inline cache) misses.
 346       //     - null checks leading to UncommonTraps.
 347       //     - range checks leading to Uncommon Traps.
 348       //   On Aix, these are especially null checks, as the ImplicitNullCheck
 349       //   optimization works only in rare cases, as the page at address 0 is only
 350       //   write protected.      //
 351       //   Note: !UseSIGTRAP is used to prevent SIGTRAPS altogether, to facilitate debugging.
 352       //
 353       // SIGSEGV:
 354       //   used for safe point polling:
 355       //     To notify all threads that they have to reach a safe point, safe point polling is used:
 356       //     All threads poll a certain mapped memory page. Normally, this page has read access.
 357       //     If the VM wants to inform the threads about impending safe points, it puts this
 358       //     page to read only ("poisens" the page), and the threads then reach a safe point.
 359       //   used for null checks:
 360       //     If the compiler finds a store it uses it for a null check. Unfortunately this
 361       //     happens rarely.  In heap based and disjoint base compressd oop modes also loads
 362       //     are used for null checks.
 363 
 364       // A VM-related SIGILL may only occur if we are not in the zero page.
 365       // On AIX, we get a SIGILL if we jump to 0x0 or to somewhere else
 366       // in the zero page, because it is filled with 0x0. We ignore
 367       // explicit SIGILLs in the zero page.
 368       if (sig == SIGILL && (pc < (address) 0x200)) {
 369         if (TraceTraps) {
 370           tty->print_raw_cr("SIGILL happened inside zero page.");
 371         }
 372         goto report_and_die;
 373       }
 374 
 375       // Handle signal from NativeJump::patch_verified_entry().
 376       if (( TrapBasedNotEntrantChecks && sig == SIGTRAP && nativeInstruction_at(pc)->is_sigtrap_zombie_not_entrant()) ||
 377           (!TrapBasedNotEntrantChecks && sig == SIGILL  && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant())) {
 378         if (TraceTraps) {
 379           tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
 380         }
 381         stub = SharedRuntime::get_handle_wrong_method_stub();
 382         goto run_stub;
 383       }
 384 
 385       else if (sig == SIGSEGV && os::is_poll_address(addr)) {
 386         if (TraceTraps) {
 387           tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", pc);
 388         }
 389         stub = SharedRuntime::get_poll_stub(pc);
 390         goto run_stub;
 391       }
 392 
 393       // SIGTRAP-based ic miss check in compiled code.
 394       else if (sig == SIGTRAP && TrapBasedICMissChecks &&
 395                nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) {
 396         if (TraceTraps) {
 397           tty->print_cr("trap: ic_miss_check at " INTPTR_FORMAT " (SIGTRAP)", pc);
 398         }
 399         stub = SharedRuntime::get_ic_miss_stub();
 400         goto run_stub;
 401       }
 402 
 403       // SIGTRAP-based implicit null check in compiled code.
 404       else if (sig == SIGTRAP && TrapBasedNullChecks &&
 405                nativeInstruction_at(pc)->is_sigtrap_null_check()) {
 406         if (TraceTraps) {
 407           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGTRAP)", pc);
 408         }
 409         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 410         goto run_stub;
 411       }
 412 
 413       // SIGSEGV-based implicit null check in compiled code.
 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)", pc);
 419         }
 420         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 421       }
 422 
 423 #ifdef COMPILER2
 424       // SIGTRAP-based implicit range check in compiled code.
 425       else if (sig == SIGTRAP && TrapBasedRangeChecks &&
 426                nativeInstruction_at(pc)->is_sigtrap_range_check()) {
 427         if (TraceTraps) {
 428           tty->print_cr("trap: range_check at " INTPTR_FORMAT " (SIGTRAP)", pc);
 429         }
 430         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
 431         goto run_stub;
 432       }
 433 #endif
 434 
 435       else if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
 436         if (TraceTraps) {
 437           tty->print_raw_cr("Fix SIGFPE handler, trying divide by zero handler.");
 438         }
 439         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
 440         goto run_stub;
 441       }
 442 
 443       else if (sig == SIGBUS) {
 444         // BugId 4454115: A read from a MappedByteBuffer can fault here if the
 445         // underlying file has been truncated. Do not crash the VM in such a case.
 446         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
 447         CompiledMethod* nm = cb->as_compiled_method_or_null();
 448         if (nm != NULL && nm->has_unsafe_access()) {
 449           address next_pc = pc + 4;
 450           next_pc = SharedRuntime::handle_unsafe_access(thread, next_pc);
 451           os::Aix::ucontext_set_pc(uc, next_pc);
 452           return 1;
 453         }
 454       }
 455     }
 456 
 457     else { // thread->thread_state() != _thread_in_Java
 458       // Detect CPU features. This is only done at the very start of the VM. Later, the
 459       // VM_Version::is_determine_features_test_running() flag should be false.
 460 
 461       if (sig == SIGILL && VM_Version::is_determine_features_test_running()) {
 462         // SIGILL must be caused by VM_Version::determine_features().
 463         *(int *)pc = 0; // patch instruction to 0 to indicate that it causes a SIGILL,
 464                         // flushing of icache is not necessary.
 465         stub = pc + 4;  // continue with next instruction.
 466         goto run_stub;
 467       }
 468       else if (thread->thread_state() == _thread_in_vm &&
 469                sig == SIGBUS && thread->doing_unsafe_access()) {
 470         address next_pc = pc + 4;
 471         next_pc = SharedRuntime::handle_unsafe_access(thread, next_pc);
 472         os::Aix::ucontext_set_pc(uc, next_pc);
 473         return 1;
 474       }
 475     }
 476 
 477     // Check to see if we caught the safepoint code in the
 478     // process of write protecting the memory serialization page.
 479     // It write enables the page immediately after protecting it
 480     // so we can just return to retry the write.
 481     if ((sig == SIGSEGV) &&
 482         os::is_memory_serialize_page(thread, addr)) {
 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 run_stub:
 491 
 492   // One of the above code blocks ininitalized the stub, so we want to
 493   // delegate control to that stub.
 494   if (stub != NULL) {
 495     // Save all thread context in case we need to restore it.
 496     if (thread != NULL) thread->set_saved_exception_pc(pc);
 497     os::Aix::ucontext_set_pc(uc, stub);
 498     return 1;
 499   }
 500 
 501 run_chained_handler:
 502 
 503   // signal-chaining
 504   if (os::Aix::chained_handler(sig, info, ucVoid)) {
 505     return 1;
 506   }
 507   if (!abort_if_unrecognized) {
 508     // caller wants another chance, so give it to him
 509     return 0;
 510   }
 511 
 512 report_and_die:
 513 
 514   // Use sigthreadmask instead of sigprocmask on AIX and unmask current signal.
 515   sigset_t newset;
 516   sigemptyset(&newset);
 517   sigaddset(&newset, sig);
 518   sigthreadmask(SIG_UNBLOCK, &newset, NULL);
 519 
 520   VMError::report_and_die(t, sig, pc, info, ucVoid);
 521 
 522   ShouldNotReachHere();
 523   return 0;
 524 }
 525 
 526 void os::Aix::init_thread_fpu_state(void) {
 527 #if !defined(USE_XLC_BUILTINS)
 528   // Disable FP exceptions.
 529   __asm__ __volatile__ ("mtfsfi 6,0");
 530 #else
 531   __mtfsfi(6, 0);
 532 #endif
 533 }
 534 
 535 ////////////////////////////////////////////////////////////////////////////////
 536 // thread stack
 537 
 538 size_t os::Posix::_compiler_thread_min_stack_allowed = 128 * K;
 539 size_t os::Posix::_java_thread_min_stack_allowed = 128 * K;


 540 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 128 * K;
 541 
 542 // return default stack size for thr_type
 543 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 544   // default stack size (compiler thread needs larger stack)
 545   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
 546   return s;
 547 }
 548 
 549 /////////////////////////////////////////////////////////////////////////////
 550 // helper functions for fatal error handler
 551 
 552 void os::print_context(outputStream *st, const void *context) {
 553   if (context == NULL) return;
 554 
 555   const ucontext_t* uc = (const ucontext_t*)context;
 556 
 557   st->print_cr("Registers:");
 558   st->print("pc =" INTPTR_FORMAT "  ", uc->uc_mcontext.jmp_context.iar);
 559   st->print("lr =" INTPTR_FORMAT "  ", uc->uc_mcontext.jmp_context.lr);
 560   st->print("ctr=" INTPTR_FORMAT "  ", uc->uc_mcontext.jmp_context.ctr);
 561   st->cr();
 562   for (int i = 0; i < 32; i++) {
 563     st->print("r%-2d=" INTPTR_FORMAT "  ", i, uc->uc_mcontext.jmp_context.gpr[i]);
 564     if (i % 3 == 2) st->cr();
 565   }
 566   st->cr();
 567   st->cr();
 568 
 569   intptr_t *sp = (intptr_t *)os::Aix::ucontext_get_sp(uc);
 570   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
 571   print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t));
 572   st->cr();
 573 
 574   // Note: it may be unsafe to inspect memory near pc. For example, pc may
 575   // point to garbage if entry point in an nmethod is corrupted. Leave
 576   // this at the end, and hope for the best.
 577   address pc = os::Aix::ucontext_get_pc(uc);
 578   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
 579   print_hex_dump(st, pc - 64, pc + 64, /*instrsize=*/4);
 580   st->cr();
 581 
 582   // Try to decode the instructions.
 583   st->print_cr("Decoded instructions: (pc=" PTR_FORMAT ")", pc);
 584   st->print("<TODO: PPC port - print_context>");
 585   // TODO: PPC port Disassembler::decode(pc, 16, 16, st);
 586   st->cr();
 587 }
 588 
 589 void os::print_register_info(outputStream *st, const void *context) {
 590   if (context == NULL) return;
 591 
 592   ucontext_t *uc = (ucontext_t*)context;
 593 
 594   st->print_cr("Register to memory mapping:");
 595   st->cr();
 596 
 597   st->print("pc ="); print_location(st, (intptr_t)uc->uc_mcontext.jmp_context.iar);
 598   st->print("lr ="); print_location(st, (intptr_t)uc->uc_mcontext.jmp_context.lr);
 599   st->print("sp ="); print_location(st, (intptr_t)os::Aix::ucontext_get_sp(uc));
 600   for (int i = 0; i < 32; i++) {
 601     st->print("r%-2d=", i);
 602     print_location(st, (intptr_t)uc->uc_mcontext.jmp_context.gpr[i]);
 603   }
 604 
 605   st->cr();
 606 }
 607 
 608 extern "C" {
 609   int SpinPause() {
 610     return 0;
 611   }
 612 }
 613 
 614 #ifndef PRODUCT
 615 void os::verify_stack_alignment() {
 616   assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
 617 }
 618 #endif
 619 
 620 int os::extra_bang_size_in_bytes() {
 621   // PPC does not require the additional stack bang.
 622   return 0;
 623 }
 624 
 625 bool os::platform_print_native_stack(outputStream* st, void* context, char *buf, int buf_size) {
 626   AixNativeCallstack::print_callstack_for_context(st, (const ucontext_t*)context, true, buf, (size_t) buf_size);
 627   return true;
 628 }
 629 
 630 
--- EOF ---