os_linux_x86.cpp revision 4795:2cb5d5f6d5e5
1/* 2 * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25// no precompiled headers 26#include "asm/macroAssembler.hpp" 27#include "classfile/classLoader.hpp" 28#include "classfile/systemDictionary.hpp" 29#include "classfile/vmSymbols.hpp" 30#include "code/icBuffer.hpp" 31#include "code/vtableStubs.hpp" 32#include "interpreter/interpreter.hpp" 33#include "jvm_linux.h" 34#include "memory/allocation.inline.hpp" 35#include "mutex_linux.inline.hpp" 36#include "os_share_linux.hpp" 37#include "prims/jniFastGetField.hpp" 38#include "prims/jvm.h" 39#include "prims/jvm_misc.hpp" 40#include "runtime/arguments.hpp" 41#include "runtime/extendedPC.hpp" 42#include "runtime/frame.inline.hpp" 43#include "runtime/interfaceSupport.hpp" 44#include "runtime/java.hpp" 45#include "runtime/javaCalls.hpp" 46#include "runtime/mutexLocker.hpp" 47#include "runtime/osThread.hpp" 48#include "runtime/sharedRuntime.hpp" 49#include "runtime/stubRoutines.hpp" 50#include "runtime/thread.inline.hpp" 51#include "runtime/timer.hpp" 52#include "utilities/events.hpp" 53#include "utilities/vmError.hpp" 54 55// put OS-includes here 56# include <sys/types.h> 57# include <sys/mman.h> 58# include <pthread.h> 59# include <signal.h> 60# include <errno.h> 61# include <dlfcn.h> 62# include <stdlib.h> 63# include <stdio.h> 64# include <unistd.h> 65# include <sys/resource.h> 66# include <pthread.h> 67# include <sys/stat.h> 68# include <sys/time.h> 69# include <sys/utsname.h> 70# include <sys/socket.h> 71# include <sys/wait.h> 72# include <pwd.h> 73# include <poll.h> 74# include <ucontext.h> 75# include <fpu_control.h> 76 77#ifdef AMD64 78#define REG_SP REG_RSP 79#define REG_PC REG_RIP 80#define REG_FP REG_RBP 81#define SPELL_REG_SP "rsp" 82#define SPELL_REG_FP "rbp" 83#else 84#define REG_SP REG_UESP 85#define REG_PC REG_EIP 86#define REG_FP REG_EBP 87#define SPELL_REG_SP "esp" 88#define SPELL_REG_FP "ebp" 89#endif // AMD64 90 91address os::current_stack_pointer() { 92#ifdef SPARC_WORKS 93 register void *esp; 94 __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp)); 95 return (address) ((char*)esp + sizeof(long)*2); 96#elif defined(__clang__) 97 intptr_t* esp; 98 __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):); 99 return (address) esp; 100#else 101 register void *esp __asm__ (SPELL_REG_SP); 102 return (address) esp; 103#endif 104} 105 106char* os::non_memory_address_word() { 107 // Must never look like an address returned by reserve_memory, 108 // even in its subfields (as defined by the CPU immediate fields, 109 // if the CPU splits constants across multiple instructions). 110 111 return (char*) -1; 112} 113 114void os::initialize_thread(Thread* thr) { 115// Nothing to do. 116} 117 118address os::Linux::ucontext_get_pc(ucontext_t * uc) { 119 return (address)uc->uc_mcontext.gregs[REG_PC]; 120} 121 122intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) { 123 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP]; 124} 125 126intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) { 127 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP]; 128} 129 130// For Forte Analyzer AsyncGetCallTrace profiling support - thread 131// is currently interrupted by SIGPROF. 132// os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal 133// frames. Currently we don't do that on Linux, so it's the same as 134// os::fetch_frame_from_context(). 135ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread, 136 ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) { 137 138 assert(thread != NULL, "just checking"); 139 assert(ret_sp != NULL, "just checking"); 140 assert(ret_fp != NULL, "just checking"); 141 142 return os::fetch_frame_from_context(uc, ret_sp, ret_fp); 143} 144 145ExtendedPC os::fetch_frame_from_context(void* ucVoid, 146 intptr_t** ret_sp, intptr_t** ret_fp) { 147 148 ExtendedPC epc; 149 ucontext_t* uc = (ucontext_t*)ucVoid; 150 151 if (uc != NULL) { 152 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc)); 153 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc); 154 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc); 155 } else { 156 // construct empty ExtendedPC for return value checking 157 epc = ExtendedPC(NULL); 158 if (ret_sp) *ret_sp = (intptr_t *)NULL; 159 if (ret_fp) *ret_fp = (intptr_t *)NULL; 160 } 161 162 return epc; 163} 164 165frame os::fetch_frame_from_context(void* ucVoid) { 166 intptr_t* sp; 167 intptr_t* fp; 168 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp); 169 return frame(sp, fp, epc.pc()); 170} 171 172// By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get 173// turned off by -fomit-frame-pointer, 174frame os::get_sender_for_C_frame(frame* fr) { 175 return frame(fr->sender_sp(), fr->link(), fr->sender_pc()); 176} 177 178intptr_t* _get_previous_fp() { 179#ifdef SPARC_WORKS 180 register intptr_t **ebp; 181 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp)); 182#elif defined(__clang__) 183 intptr_t **ebp; 184 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):); 185#else 186 register intptr_t **ebp __asm__ (SPELL_REG_FP); 187#endif 188 return (intptr_t*) *ebp; // we want what it points to. 189} 190 191 192frame os::current_frame() { 193 intptr_t* fp = _get_previous_fp(); 194 frame myframe((intptr_t*)os::current_stack_pointer(), 195 (intptr_t*)fp, 196 CAST_FROM_FN_PTR(address, os::current_frame)); 197 if (os::is_first_C_frame(&myframe)) { 198 // stack is not walkable 199 return frame(); 200 } else { 201 return os::get_sender_for_C_frame(&myframe); 202 } 203} 204 205// Utility functions 206 207// From IA32 System Programming Guide 208enum { 209 trap_page_fault = 0xE 210}; 211 212extern "C" void Fetch32PFI () ; 213extern "C" void Fetch32Resume () ; 214#ifdef AMD64 215extern "C" void FetchNPFI () ; 216extern "C" void FetchNResume () ; 217#endif // AMD64 218 219extern "C" JNIEXPORT int 220JVM_handle_linux_signal(int sig, 221 siginfo_t* info, 222 void* ucVoid, 223 int abort_if_unrecognized) { 224 ucontext_t* uc = (ucontext_t*) ucVoid; 225 226 Thread* t = ThreadLocalStorage::get_thread_slow(); 227 228 SignalHandlerMark shm(t); 229 230 // Note: it's not uncommon that JNI code uses signal/sigset to install 231 // then restore certain signal handler (e.g. to temporarily block SIGPIPE, 232 // or have a SIGILL handler when detecting CPU type). When that happens, 233 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To 234 // avoid unnecessary crash when libjsig is not preloaded, try handle signals 235 // that do not require siginfo/ucontext first. 236 237 if (sig == SIGPIPE || sig == SIGXFSZ) { 238 // allow chained handler to go first 239 if (os::Linux::chained_handler(sig, info, ucVoid)) { 240 return true; 241 } else { 242 if (PrintMiscellaneous && (WizardMode || Verbose)) { 243 char buf[64]; 244 warning("Ignoring %s - see bugs 4229104 or 646499219", 245 os::exception_name(sig, buf, sizeof(buf))); 246 } 247 return true; 248 } 249 } 250 251 JavaThread* thread = NULL; 252 VMThread* vmthread = NULL; 253 if (os::Linux::signal_handlers_are_installed) { 254 if (t != NULL ){ 255 if(t->is_Java_thread()) { 256 thread = (JavaThread*)t; 257 } 258 else if(t->is_VM_thread()){ 259 vmthread = (VMThread *)t; 260 } 261 } 262 } 263/* 264 NOTE: does not seem to work on linux. 265 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) { 266 // can't decode this kind of signal 267 info = NULL; 268 } else { 269 assert(sig == info->si_signo, "bad siginfo"); 270 } 271*/ 272 // decide if this trap can be handled by a stub 273 address stub = NULL; 274 275 address pc = NULL; 276 277 //%note os_trap_1 278 if (info != NULL && uc != NULL && thread != NULL) { 279 pc = (address) os::Linux::ucontext_get_pc(uc); 280 281 if (pc == (address) Fetch32PFI) { 282 uc->uc_mcontext.gregs[REG_PC] = intptr_t(Fetch32Resume) ; 283 return 1 ; 284 } 285#ifdef AMD64 286 if (pc == (address) FetchNPFI) { 287 uc->uc_mcontext.gregs[REG_PC] = intptr_t (FetchNResume) ; 288 return 1 ; 289 } 290#endif // AMD64 291 292 // Handle ALL stack overflow variations here 293 if (sig == SIGSEGV) { 294 address addr = (address) info->si_addr; 295 296 // check if fault address is within thread stack 297 if (addr < thread->stack_base() && 298 addr >= thread->stack_base() - thread->stack_size()) { 299 // stack overflow 300 if (thread->in_stack_yellow_zone(addr)) { 301 thread->disable_stack_yellow_zone(); 302 if (thread->thread_state() == _thread_in_Java) { 303 // Throw a stack overflow exception. Guard pages will be reenabled 304 // while unwinding the stack. 305 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW); 306 } else { 307 // Thread was in the vm or native code. Return and try to finish. 308 return 1; 309 } 310 } else if (thread->in_stack_red_zone(addr)) { 311 // Fatal red zone violation. Disable the guard pages and fall through 312 // to handle_unexpected_exception way down below. 313 thread->disable_stack_red_zone(); 314 tty->print_raw_cr("An irrecoverable stack overflow has occurred."); 315 316 // This is a likely cause, but hard to verify. Let's just print 317 // it as a hint. 318 tty->print_raw_cr("Please check if any of your loaded .so files has " 319 "enabled executable stack (see man page execstack(8))"); 320 } else { 321 // Accessing stack address below sp may cause SEGV if current 322 // thread has MAP_GROWSDOWN stack. This should only happen when 323 // current thread was created by user code with MAP_GROWSDOWN flag 324 // and then attached to VM. See notes in os_linux.cpp. 325 if (thread->osthread()->expanding_stack() == 0) { 326 thread->osthread()->set_expanding_stack(); 327 if (os::Linux::manually_expand_stack(thread, addr)) { 328 thread->osthread()->clear_expanding_stack(); 329 return 1; 330 } 331 thread->osthread()->clear_expanding_stack(); 332 } else { 333 fatal("recursive segv. expanding stack."); 334 } 335 } 336 } 337 } 338 339 if (thread->thread_state() == _thread_in_Java) { 340 // Java thread running in Java code => find exception handler if any 341 // a fault inside compiled code, the interpreter, or a stub 342 343 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) { 344 stub = SharedRuntime::get_poll_stub(pc); 345 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) { 346 // BugId 4454115: A read from a MappedByteBuffer can fault 347 // here if the underlying file has been truncated. 348 // 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 stub = StubRoutines::handler_for_unsafe_access(); 353 } 354 } 355 else 356 357#ifdef AMD64 358 if (sig == SIGFPE && 359 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) { 360 stub = 361 SharedRuntime:: 362 continuation_for_implicit_exception(thread, 363 pc, 364 SharedRuntime:: 365 IMPLICIT_DIVIDE_BY_ZERO); 366#else 367 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) { 368 // HACK: si_code does not work on linux 2.2.12-20!!! 369 int op = pc[0]; 370 if (op == 0xDB) { 371 // FIST 372 // TODO: The encoding of D2I in i486.ad can cause an exception 373 // prior to the fist instruction if there was an invalid operation 374 // pending. We want to dismiss that exception. From the win_32 375 // side it also seems that if it really was the fist causing 376 // the exception that we do the d2i by hand with different 377 // rounding. Seems kind of weird. 378 // NOTE: that we take the exception at the NEXT floating point instruction. 379 assert(pc[0] == 0xDB, "not a FIST opcode"); 380 assert(pc[1] == 0x14, "not a FIST opcode"); 381 assert(pc[2] == 0x24, "not a FIST opcode"); 382 return true; 383 } else if (op == 0xF7) { 384 // IDIV 385 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO); 386 } else { 387 // TODO: handle more cases if we are using other x86 instructions 388 // that can generate SIGFPE signal on linux. 389 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op); 390 fatal("please update this code."); 391 } 392#endif // AMD64 393 } else if (sig == SIGSEGV && 394 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) { 395 // Determination of interpreter/vtable stub/compiled code null exception 396 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 397 } 398 } else if (thread->thread_state() == _thread_in_vm && 399 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */ 400 thread->doing_unsafe_access()) { 401 stub = StubRoutines::handler_for_unsafe_access(); 402 } 403 404 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in 405 // and the heap gets shrunk before the field access. 406 if ((sig == SIGSEGV) || (sig == SIGBUS)) { 407 address addr = JNI_FastGetField::find_slowcase_pc(pc); 408 if (addr != (address)-1) { 409 stub = addr; 410 } 411 } 412 413 // Check to see if we caught the safepoint code in the 414 // process of write protecting the memory serialization page. 415 // It write enables the page immediately after protecting it 416 // so we can just return to retry the write. 417 if ((sig == SIGSEGV) && 418 os::is_memory_serialize_page(thread, (address) info->si_addr)) { 419 // Block current thread until the memory serialize page permission restored. 420 os::block_on_serialize_page_trap(); 421 return true; 422 } 423 } 424 425#ifndef AMD64 426 // Execution protection violation 427 // 428 // This should be kept as the last step in the triage. We don't 429 // have a dedicated trap number for a no-execute fault, so be 430 // conservative and allow other handlers the first shot. 431 // 432 // Note: We don't test that info->si_code == SEGV_ACCERR here. 433 // this si_code is so generic that it is almost meaningless; and 434 // the si_code for this condition may change in the future. 435 // Furthermore, a false-positive should be harmless. 436 if (UnguardOnExecutionViolation > 0 && 437 (sig == SIGSEGV || sig == SIGBUS) && 438 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) { 439 int page_size = os::vm_page_size(); 440 address addr = (address) info->si_addr; 441 address pc = os::Linux::ucontext_get_pc(uc); 442 // Make sure the pc and the faulting address are sane. 443 // 444 // If an instruction spans a page boundary, and the page containing 445 // the beginning of the instruction is executable but the following 446 // page is not, the pc and the faulting address might be slightly 447 // different - we still want to unguard the 2nd page in this case. 448 // 449 // 15 bytes seems to be a (very) safe value for max instruction size. 450 bool pc_is_near_addr = 451 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15); 452 bool instr_spans_page_boundary = 453 (align_size_down((intptr_t) pc ^ (intptr_t) addr, 454 (intptr_t) page_size) > 0); 455 456 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) { 457 static volatile address last_addr = 458 (address) os::non_memory_address_word(); 459 460 // In conservative mode, don't unguard unless the address is in the VM 461 if (addr != last_addr && 462 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) { 463 464 // Set memory to RWX and retry 465 address page_start = 466 (address) align_size_down((intptr_t) addr, (intptr_t) page_size); 467 bool res = os::protect_memory((char*) page_start, page_size, 468 os::MEM_PROT_RWX); 469 470 if (PrintMiscellaneous && Verbose) { 471 char buf[256]; 472 jio_snprintf(buf, sizeof(buf), "Execution protection violation " 473 "at " INTPTR_FORMAT 474 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr, 475 page_start, (res ? "success" : "failed"), errno); 476 tty->print_raw_cr(buf); 477 } 478 stub = pc; 479 480 // Set last_addr so if we fault again at the same address, we don't end 481 // up in an endless loop. 482 // 483 // There are two potential complications here. Two threads trapping at 484 // the same address at the same time could cause one of the threads to 485 // think it already unguarded, and abort the VM. Likely very rare. 486 // 487 // The other race involves two threads alternately trapping at 488 // different addresses and failing to unguard the page, resulting in 489 // an endless loop. This condition is probably even more unlikely than 490 // the first. 491 // 492 // Although both cases could be avoided by using locks or thread local 493 // last_addr, these solutions are unnecessary complication: this 494 // handler is a best-effort safety net, not a complete solution. It is 495 // disabled by default and should only be used as a workaround in case 496 // we missed any no-execute-unsafe VM code. 497 498 last_addr = addr; 499 } 500 } 501 } 502#endif // !AMD64 503 504 if (stub != NULL) { 505 // save all thread context in case we need to restore it 506 if (thread != NULL) thread->set_saved_exception_pc(pc); 507 508 uc->uc_mcontext.gregs[REG_PC] = (greg_t)stub; 509 return true; 510 } 511 512 // signal-chaining 513 if (os::Linux::chained_handler(sig, info, ucVoid)) { 514 return true; 515 } 516 517 if (!abort_if_unrecognized) { 518 // caller wants another chance, so give it to him 519 return false; 520 } 521 522 if (pc == NULL && uc != NULL) { 523 pc = os::Linux::ucontext_get_pc(uc); 524 } 525 526 // unmask current signal 527 sigset_t newset; 528 sigemptyset(&newset); 529 sigaddset(&newset, sig); 530 sigprocmask(SIG_UNBLOCK, &newset, NULL); 531 532 VMError err(t, sig, pc, info, ucVoid); 533 err.report_and_die(); 534 535 ShouldNotReachHere(); 536} 537 538void os::Linux::init_thread_fpu_state(void) { 539#ifndef AMD64 540 // set fpu to 53 bit precision 541 set_fpu_control_word(0x27f); 542#endif // !AMD64 543} 544 545int os::Linux::get_fpu_control_word(void) { 546#ifdef AMD64 547 return 0; 548#else 549 int fpu_control; 550 _FPU_GETCW(fpu_control); 551 return fpu_control & 0xffff; 552#endif // AMD64 553} 554 555void os::Linux::set_fpu_control_word(int fpu_control) { 556#ifndef AMD64 557 _FPU_SETCW(fpu_control); 558#endif // !AMD64 559} 560 561// Check that the linux kernel version is 2.4 or higher since earlier 562// versions do not support SSE without patches. 563bool os::supports_sse() { 564#ifdef AMD64 565 return true; 566#else 567 struct utsname uts; 568 if( uname(&uts) != 0 ) return false; // uname fails? 569 char *minor_string; 570 int major = strtol(uts.release,&minor_string,10); 571 int minor = strtol(minor_string+1,NULL,10); 572 bool result = (major > 2 || (major==2 && minor >= 4)); 573#ifndef PRODUCT 574 if (PrintMiscellaneous && Verbose) { 575 tty->print("OS version is %d.%d, which %s support SSE/SSE2\n", 576 major,minor, result ? "DOES" : "does NOT"); 577 } 578#endif 579 return result; 580#endif // AMD64 581} 582 583bool os::is_allocatable(size_t bytes) { 584#ifdef AMD64 585 // unused on amd64? 586 return true; 587#else 588 589 if (bytes < 2 * G) { 590 return true; 591 } 592 593 char* addr = reserve_memory(bytes, NULL); 594 595 if (addr != NULL) { 596 release_memory(addr, bytes); 597 } 598 599 return addr != NULL; 600#endif // AMD64 601} 602 603//////////////////////////////////////////////////////////////////////////////// 604// thread stack 605 606#ifdef AMD64 607size_t os::Linux::min_stack_allowed = 64 * K; 608 609// amd64: pthread on amd64 is always in floating stack mode 610bool os::Linux::supports_variable_stack_size() { return true; } 611#else 612size_t os::Linux::min_stack_allowed = (48 DEBUG_ONLY(+4))*K; 613 614#ifdef __GNUC__ 615#define GET_GS() ({int gs; __asm__ volatile("movw %%gs, %w0":"=q"(gs)); gs&0xffff;}) 616#endif 617 618// Test if pthread library can support variable thread stack size. LinuxThreads 619// in fixed stack mode allocates 2M fixed slot for each thread. LinuxThreads 620// in floating stack mode and NPTL support variable stack size. 621bool os::Linux::supports_variable_stack_size() { 622 if (os::Linux::is_NPTL()) { 623 // NPTL, yes 624 return true; 625 626 } else { 627 // Note: We can't control default stack size when creating a thread. 628 // If we use non-default stack size (pthread_attr_setstacksize), both 629 // floating stack and non-floating stack LinuxThreads will return the 630 // same value. This makes it impossible to implement this function by 631 // detecting thread stack size directly. 632 // 633 // An alternative approach is to check %gs. Fixed-stack LinuxThreads 634 // do not use %gs, so its value is 0. Floating-stack LinuxThreads use 635 // %gs (either as LDT selector or GDT selector, depending on kernel) 636 // to access thread specific data. 637 // 638 // Note that %gs is a reserved glibc register since early 2001, so 639 // applications are not allowed to change its value (Ulrich Drepper from 640 // Redhat confirmed that all known offenders have been modified to use 641 // either %fs or TSD). In the worst case scenario, when VM is embedded in 642 // a native application that plays with %gs, we might see non-zero %gs 643 // even LinuxThreads is running in fixed stack mode. As the result, we'll 644 // return true and skip _thread_safety_check(), so we may not be able to 645 // detect stack-heap collisions. But otherwise it's harmless. 646 // 647#ifdef __GNUC__ 648 return (GET_GS() != 0); 649#else 650 return false; 651#endif 652 } 653} 654#endif // AMD64 655 656// return default stack size for thr_type 657size_t os::Linux::default_stack_size(os::ThreadType thr_type) { 658 // default stack size (compiler thread needs larger stack) 659#ifdef AMD64 660 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M); 661#else 662 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K); 663#endif // AMD64 664 return s; 665} 666 667size_t os::Linux::default_guard_size(os::ThreadType thr_type) { 668 // Creating guard page is very expensive. Java thread has HotSpot 669 // guard page, only enable glibc guard page for non-Java threads. 670 return (thr_type == java_thread ? 0 : page_size()); 671} 672 673// Java thread: 674// 675// Low memory addresses 676// +------------------------+ 677// | |\ JavaThread created by VM does not have glibc 678// | glibc guard page | - guard, attached Java thread usually has 679// | |/ 1 page glibc guard. 680// P1 +------------------------+ Thread::stack_base() - Thread::stack_size() 681// | |\ 682// | HotSpot Guard Pages | - red and yellow pages 683// | |/ 684// +------------------------+ JavaThread::stack_yellow_zone_base() 685// | |\ 686// | Normal Stack | - 687// | |/ 688// P2 +------------------------+ Thread::stack_base() 689// 690// Non-Java thread: 691// 692// Low memory addresses 693// +------------------------+ 694// | |\ 695// | glibc guard page | - usually 1 page 696// | |/ 697// P1 +------------------------+ Thread::stack_base() - Thread::stack_size() 698// | |\ 699// | Normal Stack | - 700// | |/ 701// P2 +------------------------+ Thread::stack_base() 702// 703// ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from 704// pthread_attr_getstack() 705 706static void current_stack_region(address * bottom, size_t * size) { 707 if (os::Linux::is_initial_thread()) { 708 // initial thread needs special handling because pthread_getattr_np() 709 // may return bogus value. 710 *bottom = os::Linux::initial_thread_stack_bottom(); 711 *size = os::Linux::initial_thread_stack_size(); 712 } else { 713 pthread_attr_t attr; 714 715 int rslt = pthread_getattr_np(pthread_self(), &attr); 716 717 // JVM needs to know exact stack location, abort if it fails 718 if (rslt != 0) { 719 if (rslt == ENOMEM) { 720 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np"); 721 } else { 722 fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt)); 723 } 724 } 725 726 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) { 727 fatal("Can not locate current stack attributes!"); 728 } 729 730 pthread_attr_destroy(&attr); 731 732 } 733 assert(os::current_stack_pointer() >= *bottom && 734 os::current_stack_pointer() < *bottom + *size, "just checking"); 735} 736 737address os::current_stack_base() { 738 address bottom; 739 size_t size; 740 current_stack_region(&bottom, &size); 741 return (bottom + size); 742} 743 744size_t os::current_stack_size() { 745 // stack size includes normal stack and HotSpot guard pages 746 address bottom; 747 size_t size; 748 current_stack_region(&bottom, &size); 749 return size; 750} 751 752///////////////////////////////////////////////////////////////////////////// 753// helper functions for fatal error handler 754 755void os::print_context(outputStream *st, void *context) { 756 if (context == NULL) return; 757 758 ucontext_t *uc = (ucontext_t*)context; 759 st->print_cr("Registers:"); 760#ifdef AMD64 761 st->print( "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]); 762 st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]); 763 st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]); 764 st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]); 765 st->cr(); 766 st->print( "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]); 767 st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]); 768 st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]); 769 st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]); 770 st->cr(); 771 st->print( "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]); 772 st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]); 773 st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]); 774 st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]); 775 st->cr(); 776 st->print( "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]); 777 st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]); 778 st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]); 779 st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]); 780 st->cr(); 781 st->print( "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]); 782 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]); 783 st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]); 784 st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]); 785 st->cr(); 786 st->print(" TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]); 787#else 788 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]); 789 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]); 790 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]); 791 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]); 792 st->cr(); 793 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]); 794 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]); 795 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]); 796 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]); 797 st->cr(); 798 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]); 799 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]); 800 st->print(", CR2=" INTPTR_FORMAT, uc->uc_mcontext.cr2); 801#endif // AMD64 802 st->cr(); 803 st->cr(); 804 805 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc); 806 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp); 807 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t)); 808 st->cr(); 809 810 // Note: it may be unsafe to inspect memory near pc. For example, pc may 811 // point to garbage if entry point in an nmethod is corrupted. Leave 812 // this at the end, and hope for the best. 813 address pc = os::Linux::ucontext_get_pc(uc); 814 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc); 815 print_hex_dump(st, pc - 32, pc + 32, sizeof(char)); 816} 817 818void os::print_register_info(outputStream *st, void *context) { 819 if (context == NULL) return; 820 821 ucontext_t *uc = (ucontext_t*)context; 822 823 st->print_cr("Register to memory mapping:"); 824 st->cr(); 825 826 // this is horrendously verbose but the layout of the registers in the 827 // context does not match how we defined our abstract Register set, so 828 // we can't just iterate through the gregs area 829 830 // this is only for the "general purpose" registers 831 832#ifdef AMD64 833 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]); 834 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]); 835 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]); 836 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]); 837 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]); 838 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]); 839 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]); 840 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]); 841 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]); 842 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]); 843 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]); 844 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]); 845 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]); 846 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]); 847 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]); 848 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]); 849#else 850 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]); 851 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]); 852 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]); 853 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]); 854 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]); 855 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]); 856 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]); 857 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]); 858#endif // AMD64 859 860 st->cr(); 861} 862 863void os::setup_fpu() { 864#ifndef AMD64 865 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std(); 866 __asm__ volatile ( "fldcw (%0)" : 867 : "r" (fpu_cntrl) : "memory"); 868#endif // !AMD64 869} 870 871#ifndef PRODUCT 872void os::verify_stack_alignment() { 873#ifdef AMD64 874 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment"); 875#endif 876} 877#endif 878