1 /* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * Copyright 2012, 2013 SAP AG. 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 hat 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 "assembler_ppc.inline.hpp" 28 #include "classfile/classLoader.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/icBuffer.hpp" 32 #include "code/vtableStubs.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "jvm_linux.h" 35 #include "memory/allocation.inline.hpp" 36 #include "mutex_linux.inline.hpp" 37 #include "nativeInst_ppc.hpp" 38 #include "os_share_linux.hpp" 39 #include "prims/jniFastGetField.hpp" 40 #include "prims/jvm.h" 41 #include "prims/jvm_misc.hpp" 42 #include "runtime/arguments.hpp" 43 #include "runtime/extendedPC.hpp" 44 #include "runtime/frame.inline.hpp" 45 #include "runtime/interfaceSupport.hpp" 46 #include "runtime/java.hpp" 47 #include "runtime/javaCalls.hpp" 48 #include "runtime/mutexLocker.hpp" 49 #include "runtime/osThread.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(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 intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) { 117 return (intptr_t*)uc->uc_mcontext.regs->gpr[1/*REG_SP*/]; 118 } 119 120 intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) { 121 return NULL; 122 } 123 124 ExtendedPC os::fetch_frame_from_context(void* ucVoid, 125 intptr_t** ret_sp, intptr_t** ret_fp) { 126 127 ExtendedPC epc; 128 ucontext_t* uc = (ucontext_t*)ucVoid; 129 130 if (uc != NULL) { 131 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc)); 132 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc); 133 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc); 134 } else { 135 // construct empty ExtendedPC for return value checking 136 epc = ExtendedPC(NULL); 137 if (ret_sp) *ret_sp = (intptr_t *)NULL; 138 if (ret_fp) *ret_fp = (intptr_t *)NULL; 139 } 140 141 return epc; 142 } 143 144 frame os::fetch_frame_from_context(void* ucVoid) { 145 intptr_t* sp; 146 intptr_t* fp; 147 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp); 148 return frame(sp, epc.pc()); 149 } 150 151 frame os::get_sender_for_C_frame(frame* fr) { 152 if (*fr->sp() == 0) { 153 // fr is the last C frame 154 return frame(NULL, NULL); 155 } 156 return frame(fr->sender_sp(), fr->sender_pc()); 157 } 158 159 160 frame os::current_frame() { 161 intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer()); 162 // hack. 163 frame topframe(csp, (address)0x8); 164 // return sender of current topframe which hopefully has pc != NULL. 165 return os::get_sender_for_C_frame(&topframe); 166 } 167 168 // Utility functions 169 170 extern "C" JNIEXPORT int 171 JVM_handle_linux_signal(int sig, 172 siginfo_t* info, 173 void* ucVoid, 174 int abort_if_unrecognized) { 175 ucontext_t* uc = (ucontext_t*) ucVoid; 176 177 Thread* t = ThreadLocalStorage::get_thread_slow(); 178 179 SignalHandlerMark shm(t); 180 181 // Note: it's not uncommon that JNI code uses signal/sigset to install 182 // then restore certain signal handler (e.g. to temporarily block SIGPIPE, 183 // or have a SIGILL handler when detecting CPU type). When that happens, 184 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To 185 // avoid unnecessary crash when libjsig is not preloaded, try handle signals 186 // that do not require siginfo/ucontext first. 187 188 if (sig == SIGPIPE) { 189 if (os::Linux::chained_handler(sig, info, ucVoid)) { 190 return true; 191 } else { 192 if (PrintMiscellaneous && (WizardMode || Verbose)) { 193 warning("Ignoring SIGPIPE - see bug 4229104"); 194 } 195 return true; 196 } 197 } 198 199 JavaThread* thread = NULL; 200 VMThread* vmthread = NULL; 201 if (os::Linux::signal_handlers_are_installed) { 202 if (t != NULL) { 203 if(t->is_Java_thread()) { 204 thread = (JavaThread*)t; 205 } else if(t->is_VM_thread()) { 206 vmthread = (VMThread *)t; 207 } 208 } 209 } 210 211 // Moved SafeFetch32 handling outside thread!=NULL conditional block to make 212 // it work if no associated JavaThread object exists. 213 if (uc) { 214 address const pc = os::Linux::ucontext_get_pc(uc); 215 if (pc && StubRoutines::is_safefetch_fault(pc)) { 216 uc->uc_mcontext.regs->nip = (unsigned long)StubRoutines::continuation_for_safefetch_fault(pc); 217 return true; 218 } 219 } 220 221 // decide if this trap can be handled by a stub 222 address stub = NULL; 223 address pc = NULL; 224 225 //%note os_trap_1 226 if (info != NULL && uc != NULL && thread != NULL) { 227 pc = (address) os::Linux::ucontext_get_pc(uc); 228 229 // Handle ALL stack overflow variations here 230 if (sig == SIGSEGV) { 231 // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see 232 // comment below). Use get_stack_bang_address instead of si_addr. 233 address addr = ((NativeInstruction*)pc)->get_stack_bang_address(uc); 234 235 // Check if fault address is within thread stack. 236 if (addr < thread->stack_base() && 237 addr >= thread->stack_base() - thread->stack_size()) { 238 // stack overflow 239 if (thread->in_stack_yellow_zone(addr)) { 240 thread->disable_stack_yellow_zone(); 241 if (thread->thread_state() == _thread_in_Java) { 242 // Throw a stack overflow exception. 243 // Guard pages will be reenabled while unwinding the stack. 244 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW); 245 } else { 246 // Thread was in the vm or native code. Return and try to finish. 247 return 1; 248 } 249 } else if (thread->in_stack_red_zone(addr)) { 250 // Fatal red zone violation. Disable the guard pages and fall through 251 // to handle_unexpected_exception way down below. 252 thread->disable_stack_red_zone(); 253 tty->print_raw_cr("An irrecoverable stack overflow has occurred."); 254 255 // This is a likely cause, but hard to verify. Let's just print 256 // it as a hint. 257 tty->print_raw_cr("Please check if any of your loaded .so files has " 258 "enabled executable stack (see man page execstack(8))"); 259 } else { 260 // Accessing stack address below sp may cause SEGV if current 261 // thread has MAP_GROWSDOWN stack. This should only happen when 262 // current thread was created by user code with MAP_GROWSDOWN flag 263 // and then attached to VM. See notes in os_linux.cpp. 264 if (thread->osthread()->expanding_stack() == 0) { 265 thread->osthread()->set_expanding_stack(); 266 if (os::Linux::manually_expand_stack(thread, addr)) { 267 thread->osthread()->clear_expanding_stack(); 268 return 1; 269 } 270 thread->osthread()->clear_expanding_stack(); 271 } else { 272 fatal("recursive segv. expanding stack."); 273 } 274 } 275 } 276 } 277 278 if (thread->thread_state() == _thread_in_Java) { 279 // Java thread running in Java code => find exception handler if any 280 // a fault inside compiled code, the interpreter, or a stub 281 282 // A VM-related SIGILL may only occur if we are not in the zero page. 283 // On AIX, we get a SIGILL if we jump to 0x0 or to somewhere else 284 // in the zero page, because it is filled with 0x0. We ignore 285 // explicit SIGILLs in the zero page. 286 if (sig == SIGILL && (pc < (address) 0x200)) { 287 if (TraceTraps) 288 tty->print_raw_cr("SIGILL happened inside zero page."); 289 goto report_and_die; 290 } 291 292 // Handle signal from NativeJump::patch_verified_entry(). 293 if (( TrapBasedNotEntrantChecks && sig == SIGTRAP && nativeInstruction_at(pc)->is_sigtrap_zombie_not_entrant()) || 294 (!TrapBasedNotEntrantChecks && sig == SIGILL && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant())) { 295 if (TraceTraps) 296 tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL"); 297 stub = SharedRuntime::get_handle_wrong_method_stub(); 298 } 299 300 else if (sig == SIGSEGV && 301 // A linux-ppc64 kernel before 2.6.6 doesn't set si_addr on some segfaults 302 // in 64bit mode (cf. http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.6), 303 // especially when we try to read from the safepoint polling page. So the check 304 // (address)info->si_addr == os::get_standard_polling_page() 305 // doesn't work for us. We use: 306 ((NativeInstruction*)pc)->is_safepoint_poll()) { 307 if (TraceTraps) 308 tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", pc); 309 stub = SharedRuntime::get_poll_stub(pc); 310 } 311 312 // SIGTRAP-based ic miss check in compiled code. 313 else if (sig == SIGTRAP && TrapBasedICMissChecks && 314 nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) { 315 if (TraceTraps) 316 tty->print_cr("trap: ic_miss_check at " INTPTR_FORMAT " (SIGTRAP)", pc); 317 stub = SharedRuntime::get_ic_miss_stub(); 318 } 319 320 // SIGTRAP-based implicit null check in compiled code. 321 else if (sig == SIGTRAP && TrapBasedNullChecks && 322 nativeInstruction_at(pc)->is_sigtrap_null_check()) { 323 if (TraceTraps) 324 tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGTRAP)", pc); 325 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 326 } 327 328 // SIGSEGV-based implicit null check in compiled code. 329 else if (sig == SIGSEGV && ImplicitNullChecks && 330 CodeCache::contains((void*) pc) && 331 !MacroAssembler::needs_explicit_null_check((intptr_t) info->si_addr)) { 332 if (TraceTraps) 333 tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", pc); 334 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 335 } 336 337 #ifdef COMPILER2 338 // SIGTRAP-based implicit range check in compiled code. 339 else if (sig == SIGTRAP && TrapBasedRangeChecks && 340 nativeInstruction_at(pc)->is_sigtrap_range_check()) { 341 if (TraceTraps) 342 tty->print_cr("trap: range_check at " INTPTR_FORMAT " (SIGTRAP)", pc); 343 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 344 } 345 #endif 346 else if (sig == SIGBUS) { 347 // BugId 4454115: A read from a MappedByteBuffer can fault here if the 348 // underlying file has been truncated. Do not crash the VM in such a case. 349 CodeBlob* cb = CodeCache::find_blob_unsafe(pc); 350 nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL; 351 if (nm != NULL && nm->has_unsafe_access()) { 352 // We don't really need a stub here! Just set the pending exeption and 353 // continue at the next instruction after the faulting read. Returning 354 // garbage from this read is ok. 355 thread->set_pending_unsafe_access_error(); 356 uc->uc_mcontext.regs->nip = ((unsigned long)pc) + 4; 357 return true; 358 } 359 } 360 } 361 362 else { // thread->thread_state() != _thread_in_Java 363 if (sig == SIGILL && VM_Version::is_determine_features_test_running()) { 364 // SIGILL must be caused by VM_Version::determine_features(). 365 *(int *)pc = 0; // patch instruction to 0 to indicate that it causes a SIGILL, 366 // flushing of icache is not necessary. 367 stub = pc + 4; // continue with next instruction. 368 } 369 else if (thread->thread_state() == _thread_in_vm && 370 sig == SIGBUS && thread->doing_unsafe_access()) { 371 // We don't really need a stub here! Just set the pending exeption and 372 // continue at the next instruction after the faulting read. Returning 373 // garbage from this read is ok. 374 thread->set_pending_unsafe_access_error(); 375 uc->uc_mcontext.regs->nip = ((unsigned long)pc) + 4; 376 return true; 377 } 378 } 379 380 // Check to see if we caught the safepoint code in the 381 // process of write protecting the memory serialization page. 382 // It write enables the page immediately after protecting it 383 // so we can just return to retry the write. 384 if ((sig == SIGSEGV) && 385 // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see comment above). 386 // Use is_memory_serialization instead of si_addr. 387 ((NativeInstruction*)pc)->is_memory_serialization(thread, ucVoid)) { 388 // Synchronization problem in the pseudo memory barrier code (bug id 6546278) 389 // Block current thread until the memory serialize page permission restored. 390 os::block_on_serialize_page_trap(); 391 return true; 392 } 393 } 394 395 if (stub != NULL) { 396 // Save all thread context in case we need to restore it. 397 if (thread != NULL) thread->set_saved_exception_pc(pc); 398 uc->uc_mcontext.regs->nip = (unsigned long)stub; 399 return true; 400 } 401 402 // signal-chaining 403 if (os::Linux::chained_handler(sig, info, ucVoid)) { 404 return true; 405 } 406 407 if (!abort_if_unrecognized) { 408 // caller wants another chance, so give it to him 409 return false; 410 } 411 412 if (pc == NULL && uc != NULL) { 413 pc = os::Linux::ucontext_get_pc(uc); 414 } 415 416 report_and_die: 417 // unmask current signal 418 sigset_t newset; 419 sigemptyset(&newset); 420 sigaddset(&newset, sig); 421 sigprocmask(SIG_UNBLOCK, &newset, NULL); 422 423 VMError err(t, sig, pc, info, ucVoid); 424 err.report_and_die(); 425 426 ShouldNotReachHere(); 427 return false; 428 } 429 430 void os::Linux::init_thread_fpu_state(void) { 431 // Disable FP exceptions. 432 __asm__ __volatile__ ("mtfsfi 6,0"); 433 } 434 435 int os::Linux::get_fpu_control_word(void) { 436 // x86 has problems with FPU precision after pthread_cond_timedwait(). 437 // nothing to do on ppc64. 438 return 0; 439 } 440 441 void os::Linux::set_fpu_control_word(int fpu_control) { 442 // x86 has problems with FPU precision after pthread_cond_timedwait(). 443 // nothing to do on ppc64. 444 } 445 446 //////////////////////////////////////////////////////////////////////////////// 447 // thread stack 448 449 size_t os::Linux::min_stack_allowed = 768*K; 450 451 bool os::Linux::supports_variable_stack_size() { return true; } 452 453 // return default stack size for thr_type 454 size_t os::Linux::default_stack_size(os::ThreadType thr_type) { 455 // default stack size (compiler thread needs larger stack) 456 // Notice that the setting for compiler threads here have no impact 457 // because of the strange 'fallback logic' in os::create_thread(). 458 // Better set CompilerThreadStackSize in globals_<os_cpu>.hpp if you want to 459 // specify a different stack size for compiler threads! 460 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1024 * K); 461 return s; 462 } 463 464 size_t os::Linux::default_guard_size(os::ThreadType thr_type) { 465 return 2 * page_size(); 466 } 467 468 // Java thread: 469 // 470 // Low memory addresses 471 // +------------------------+ 472 // | |\ JavaThread created by VM does not have glibc 473 // | glibc guard page | - guard, attached Java thread usually has 474 // | |/ 1 page glibc guard. 475 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size() 476 // | |\ 477 // | HotSpot Guard Pages | - red and yellow pages 478 // | |/ 479 // +------------------------+ JavaThread::stack_yellow_zone_base() 480 // | |\ 481 // | Normal Stack | - 482 // | |/ 483 // P2 +------------------------+ Thread::stack_base() 484 // 485 // Non-Java thread: 486 // 487 // Low memory addresses 488 // +------------------------+ 489 // | |\ 490 // | glibc guard page | - usually 1 page 491 // | |/ 492 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size() 493 // | |\ 494 // | Normal Stack | - 495 // | |/ 496 // P2 +------------------------+ Thread::stack_base() 497 // 498 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from 499 // pthread_attr_getstack() 500 501 static void current_stack_region(address * bottom, size_t * size) { 502 if (os::Linux::is_initial_thread()) { 503 // initial thread needs special handling because pthread_getattr_np() 504 // may return bogus value. 505 *bottom = os::Linux::initial_thread_stack_bottom(); 506 *size = os::Linux::initial_thread_stack_size(); 507 } else { 508 pthread_attr_t attr; 509 510 int rslt = pthread_getattr_np(pthread_self(), &attr); 511 512 // JVM needs to know exact stack location, abort if it fails 513 if (rslt != 0) { 514 if (rslt == ENOMEM) { 515 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np"); 516 } else { 517 fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt)); 518 } 519 } 520 521 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) { 522 fatal("Can not locate current stack attributes!"); 523 } 524 525 pthread_attr_destroy(&attr); 526 527 } 528 assert(os::current_stack_pointer() >= *bottom && 529 os::current_stack_pointer() < *bottom + *size, "just checking"); 530 } 531 532 address os::current_stack_base() { 533 address bottom; 534 size_t size; 535 current_stack_region(&bottom, &size); 536 return (bottom + size); 537 } 538 539 size_t os::current_stack_size() { 540 // stack size includes normal stack and HotSpot guard pages 541 address bottom; 542 size_t size; 543 current_stack_region(&bottom, &size); 544 return size; 545 } 546 547 ///////////////////////////////////////////////////////////////////////////// 548 // helper functions for fatal error handler 549 550 void os::print_context(outputStream *st, void *context) { 551 if (context == NULL) return; 552 553 ucontext_t* uc = (ucontext_t*)context; 554 555 st->print_cr("Registers:"); 556 st->print("pc =" INTPTR_FORMAT " ", uc->uc_mcontext.regs->nip); 557 st->print("lr =" INTPTR_FORMAT " ", uc->uc_mcontext.regs->link); 558 st->print("ctr=" INTPTR_FORMAT " ", uc->uc_mcontext.regs->ctr); 559 st->cr(); 560 for (int i = 0; i < 32; i++) { 561 st->print("r%-2d=" INTPTR_FORMAT " ", i, uc->uc_mcontext.regs->gpr[i]); 562 if (i % 3 == 2) st->cr(); 563 } 564 st->cr(); 565 st->cr(); 566 567 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc); 568 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp); 569 print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t)); 570 st->cr(); 571 572 // Note: it may be unsafe to inspect memory near pc. For example, pc may 573 // point to garbage if entry point in an nmethod is corrupted. Leave 574 // this at the end, and hope for the best. 575 address pc = os::Linux::ucontext_get_pc(uc); 576 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc); 577 print_hex_dump(st, pc - 64, pc + 64, /*instrsize=*/4); 578 st->cr(); 579 } 580 581 void os::print_register_info(outputStream *st, void *context) { 582 if (context == NULL) return; 583 584 ucontext_t *uc = (ucontext_t*)context; 585 586 st->print_cr("Register to memory mapping:"); 587 st->cr(); 588 589 // this is only for the "general purpose" registers 590 for (int i = 0; i < 32; i++) { 591 st->print("r%-2d=", i); 592 print_location(st, uc->uc_mcontext.regs->gpr[i]); 593 } 594 st->cr(); 595 } 596 597 extern "C" { 598 int SpinPause() { 599 return 0; 600 } 601 } 602 603 #ifndef PRODUCT 604 void os::verify_stack_alignment() { 605 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment"); 606 } 607 #endif