1 /* 2 * Copyright (c) 1999, 2011, 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 "assembler_x86.inline.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 "nativeInst_x86.hpp" 37 #include "os_share_linux.hpp" 38 #include "prims/jniFastGetField.hpp" 39 #include "prims/jvm.h" 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.hpp" 45 #include "runtime/java.hpp" 46 #include "runtime/javaCalls.hpp" 47 #include "runtime/mutexLocker.hpp" 48 #include "runtime/osThread.hpp" 49 #include "runtime/sharedRuntime.hpp" 50 #include "runtime/stubRoutines.hpp" 51 #include "runtime/timer.hpp" 52 #include "thread_linux.inline.hpp" 53 #include "utilities/events.hpp" 54 #include "utilities/vmError.hpp" 55 #ifdef COMPILER1 56 #include "c1/c1_Runtime1.hpp" 57 #endif 58 #ifdef COMPILER2 59 #include "opto/runtime.hpp" 60 #endif 61 62 // put OS-includes here 63 # include <sys/types.h> 64 # include <sys/mman.h> 65 # include <pthread.h> 66 # include <signal.h> 67 # include <errno.h> 68 # include <dlfcn.h> 69 # include <stdlib.h> 70 # include <stdio.h> 71 # include <unistd.h> 72 # include <sys/resource.h> 73 # include <pthread.h> 74 # include <sys/stat.h> 75 # include <sys/time.h> 76 # include <sys/utsname.h> 77 # include <sys/socket.h> 78 # include <sys/wait.h> 79 # include <pwd.h> 80 # include <poll.h> 81 # include <ucontext.h> 82 # include <fpu_control.h> 83 84 #ifdef AMD64 85 #define REG_SP REG_RSP 86 #define REG_PC REG_RIP 87 #define REG_FP REG_RBP 88 #define SPELL_REG_SP "rsp" 89 #define SPELL_REG_FP "rbp" 90 #else 91 #define REG_SP REG_UESP 92 #define REG_PC REG_EIP 93 #define REG_FP REG_EBP 94 #define SPELL_REG_SP "esp" 95 #define SPELL_REG_FP "ebp" 96 #endif // AMD64 97 98 address os::current_stack_pointer() { 99 #ifdef SPARC_WORKS 100 register void *esp; 101 __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp)); 102 return (address) ((char*)esp + sizeof(long)*2); 103 #else 104 register void *esp __asm__ (SPELL_REG_SP); 105 return (address) esp; 106 #endif 107 } 108 109 char* os::non_memory_address_word() { 110 // Must never look like an address returned by reserve_memory, 111 // even in its subfields (as defined by the CPU immediate fields, 112 // if the CPU splits constants across multiple instructions). 113 114 return (char*) -1; 115 } 116 117 void os::initialize_thread(Thread* thr) { 118 // Nothing to do. 119 } 120 121 address os::Linux::ucontext_get_pc(ucontext_t * uc) { 122 return (address)uc->uc_mcontext.gregs[REG_PC]; 123 } 124 125 intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) { 126 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP]; 127 } 128 129 intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) { 130 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP]; 131 } 132 133 // For Forte Analyzer AsyncGetCallTrace profiling support - thread 134 // is currently interrupted by SIGPROF. 135 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal 136 // frames. Currently we don't do that on Linux, so it's the same as 137 // os::fetch_frame_from_context(). 138 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread, 139 ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) { 140 141 assert(thread != NULL, "just checking"); 142 assert(ret_sp != NULL, "just checking"); 143 assert(ret_fp != NULL, "just checking"); 144 145 return os::fetch_frame_from_context(uc, ret_sp, ret_fp); 146 } 147 148 ExtendedPC os::fetch_frame_from_context(void* ucVoid, 149 intptr_t** ret_sp, intptr_t** ret_fp) { 150 151 ExtendedPC epc; 152 ucontext_t* uc = (ucontext_t*)ucVoid; 153 154 if (uc != NULL) { 155 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc)); 156 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc); 157 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc); 158 } else { 159 // construct empty ExtendedPC for return value checking 160 epc = ExtendedPC(NULL); 161 if (ret_sp) *ret_sp = (intptr_t *)NULL; 162 if (ret_fp) *ret_fp = (intptr_t *)NULL; 163 } 164 165 return epc; 166 } 167 168 frame os::fetch_frame_from_context(void* ucVoid) { 169 intptr_t* sp; 170 intptr_t* fp; 171 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp); 172 return frame(sp, fp, epc.pc()); 173 } 174 175 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get 176 // turned off by -fomit-frame-pointer, 177 frame os::get_sender_for_C_frame(frame* fr) { 178 return frame(fr->sender_sp(), fr->link(), fr->sender_pc()); 179 } 180 181 intptr_t* _get_previous_fp() { 182 #ifdef SPARC_WORKS 183 register intptr_t **ebp; 184 __asm__("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 } 190 191 192 frame 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(NULL, NULL, NULL); 200 } else { 201 return os::get_sender_for_C_frame(&myframe); 202 } 203 } 204 205 // Utility functions 206 207 // From IA32 System Programming Guide 208 enum { 209 trap_page_fault = 0xE 210 }; 211 212 extern "C" void Fetch32PFI () ; 213 extern "C" void Fetch32Resume () ; 214 #ifdef AMD64 215 extern "C" void FetchNPFI () ; 216 extern "C" void FetchNResume () ; 217 #endif // AMD64 218 219 extern "C" JNIEXPORT int 220 JVM_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 } else { 316 // Accessing stack address below sp may cause SEGV if current 317 // thread has MAP_GROWSDOWN stack. This should only happen when 318 // current thread was created by user code with MAP_GROWSDOWN flag 319 // and then attached to VM. See notes in os_linux.cpp. 320 if (thread->osthread()->expanding_stack() == 0) { 321 thread->osthread()->set_expanding_stack(); 322 if (os::Linux::manually_expand_stack(thread, addr)) { 323 thread->osthread()->clear_expanding_stack(); 324 return 1; 325 } 326 thread->osthread()->clear_expanding_stack(); 327 } else { 328 fatal("recursive segv. expanding stack."); 329 } 330 } 331 } 332 } 333 334 if (thread->thread_state() == _thread_in_Java) { 335 // Java thread running in Java code => find exception handler if any 336 // a fault inside compiled code, the interpreter, or a stub 337 338 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) { 339 stub = SharedRuntime::get_poll_stub(pc); 340 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) { 341 // BugId 4454115: A read from a MappedByteBuffer can fault 342 // here if the underlying file has been truncated. 343 // Do not crash the VM in such a case. 344 CodeBlob* cb = CodeCache::find_blob_unsafe(pc); 345 nmethod* nm = cb->is_nmethod() ? (nmethod*)cb : NULL; 346 if (nm != NULL && nm->has_unsafe_access()) { 347 stub = StubRoutines::handler_for_unsafe_access(); 348 } 349 } 350 else 351 352 #ifdef AMD64 353 if (sig == SIGFPE && 354 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) { 355 stub = 356 SharedRuntime:: 357 continuation_for_implicit_exception(thread, 358 pc, 359 SharedRuntime:: 360 IMPLICIT_DIVIDE_BY_ZERO); 361 #else 362 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) { 363 // HACK: si_code does not work on linux 2.2.12-20!!! 364 int op = pc[0]; 365 if (op == 0xDB) { 366 // FIST 367 // TODO: The encoding of D2I in i486.ad can cause an exception 368 // prior to the fist instruction if there was an invalid operation 369 // pending. We want to dismiss that exception. From the win_32 370 // side it also seems that if it really was the fist causing 371 // the exception that we do the d2i by hand with different 372 // rounding. Seems kind of weird. 373 // NOTE: that we take the exception at the NEXT floating point instruction. 374 assert(pc[0] == 0xDB, "not a FIST opcode"); 375 assert(pc[1] == 0x14, "not a FIST opcode"); 376 assert(pc[2] == 0x24, "not a FIST opcode"); 377 return true; 378 } else if (op == 0xF7) { 379 // IDIV 380 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO); 381 } else { 382 // TODO: handle more cases if we are using other x86 instructions 383 // that can generate SIGFPE signal on linux. 384 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op); 385 fatal("please update this code."); 386 } 387 #endif // AMD64 388 } else if (sig == SIGSEGV && 389 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) { 390 // Determination of interpreter/vtable stub/compiled code null exception 391 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 392 } 393 } else if (thread->thread_state() == _thread_in_vm && 394 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */ 395 thread->doing_unsafe_access()) { 396 stub = StubRoutines::handler_for_unsafe_access(); 397 } 398 399 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in 400 // and the heap gets shrunk before the field access. 401 if ((sig == SIGSEGV) || (sig == SIGBUS)) { 402 address addr = JNI_FastGetField::find_slowcase_pc(pc); 403 if (addr != (address)-1) { 404 stub = addr; 405 } 406 } 407 408 // Check to see if we caught the safepoint code in the 409 // process of write protecting the memory serialization page. 410 // It write enables the page immediately after protecting it 411 // so we can just return to retry the write. 412 if ((sig == SIGSEGV) && 413 os::is_memory_serialize_page(thread, (address) info->si_addr)) { 414 // Block current thread until the memory serialize page permission restored. 415 os::block_on_serialize_page_trap(); 416 return true; 417 } 418 } 419 420 #ifndef AMD64 421 // Execution protection violation 422 // 423 // This should be kept as the last step in the triage. We don't 424 // have a dedicated trap number for a no-execute fault, so be 425 // conservative and allow other handlers the first shot. 426 // 427 // Note: We don't test that info->si_code == SEGV_ACCERR here. 428 // this si_code is so generic that it is almost meaningless; and 429 // the si_code for this condition may change in the future. 430 // Furthermore, a false-positive should be harmless. 431 if (UnguardOnExecutionViolation > 0 && 432 (sig == SIGSEGV || sig == SIGBUS) && 433 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) { 434 int page_size = os::vm_page_size(); 435 address addr = (address) info->si_addr; 436 address pc = os::Linux::ucontext_get_pc(uc); 437 // Make sure the pc and the faulting address are sane. 438 // 439 // If an instruction spans a page boundary, and the page containing 440 // the beginning of the instruction is executable but the following 441 // page is not, the pc and the faulting address might be slightly 442 // different - we still want to unguard the 2nd page in this case. 443 // 444 // 15 bytes seems to be a (very) safe value for max instruction size. 445 bool pc_is_near_addr = 446 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15); 447 bool instr_spans_page_boundary = 448 (align_size_down((intptr_t) pc ^ (intptr_t) addr, 449 (intptr_t) page_size) > 0); 450 451 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) { 452 static volatile address last_addr = 453 (address) os::non_memory_address_word(); 454 455 // In conservative mode, don't unguard unless the address is in the VM 456 if (addr != last_addr && 457 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) { 458 459 // Set memory to RWX and retry 460 address page_start = 461 (address) align_size_down((intptr_t) addr, (intptr_t) page_size); 462 bool res = os::protect_memory((char*) page_start, page_size, 463 os::MEM_PROT_RWX); 464 465 if (PrintMiscellaneous && Verbose) { 466 char buf[256]; 467 jio_snprintf(buf, sizeof(buf), "Execution protection violation " 468 "at " INTPTR_FORMAT 469 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr, 470 page_start, (res ? "success" : "failed"), errno); 471 tty->print_raw_cr(buf); 472 } 473 stub = pc; 474 475 // Set last_addr so if we fault again at the same address, we don't end 476 // up in an endless loop. 477 // 478 // There are two potential complications here. Two threads trapping at 479 // the same address at the same time could cause one of the threads to 480 // think it already unguarded, and abort the VM. Likely very rare. 481 // 482 // The other race involves two threads alternately trapping at 483 // different addresses and failing to unguard the page, resulting in 484 // an endless loop. This condition is probably even more unlikely than 485 // the first. 486 // 487 // Although both cases could be avoided by using locks or thread local 488 // last_addr, these solutions are unnecessary complication: this 489 // handler is a best-effort safety net, not a complete solution. It is 490 // disabled by default and should only be used as a workaround in case 491 // we missed any no-execute-unsafe VM code. 492 493 last_addr = addr; 494 } 495 } 496 } 497 #endif // !AMD64 498 499 if (stub != NULL) { 500 // save all thread context in case we need to restore it 501 if (thread != NULL) thread->set_saved_exception_pc(pc); 502 503 uc->uc_mcontext.gregs[REG_PC] = (greg_t)stub; 504 return true; 505 } 506 507 // signal-chaining 508 if (os::Linux::chained_handler(sig, info, ucVoid)) { 509 return true; 510 } 511 512 if (!abort_if_unrecognized) { 513 // caller wants another chance, so give it to him 514 return false; 515 } 516 517 if (pc == NULL && uc != NULL) { 518 pc = os::Linux::ucontext_get_pc(uc); 519 } 520 521 // unmask current signal 522 sigset_t newset; 523 sigemptyset(&newset); 524 sigaddset(&newset, sig); 525 sigprocmask(SIG_UNBLOCK, &newset, NULL); 526 527 VMError err(t, sig, pc, info, ucVoid); 528 err.report_and_die(); 529 530 ShouldNotReachHere(); 531 } 532 533 void os::Linux::init_thread_fpu_state(void) { 534 #ifndef AMD64 535 // set fpu to 53 bit precision 536 set_fpu_control_word(0x27f); 537 #endif // !AMD64 538 } 539 540 int os::Linux::get_fpu_control_word(void) { 541 #ifdef AMD64 542 return 0; 543 #else 544 int fpu_control; 545 _FPU_GETCW(fpu_control); 546 return fpu_control & 0xffff; 547 #endif // AMD64 548 } 549 550 void os::Linux::set_fpu_control_word(int fpu_control) { 551 #ifndef AMD64 552 _FPU_SETCW(fpu_control); 553 #endif // !AMD64 554 } 555 556 // Check that the linux kernel version is 2.4 or higher since earlier 557 // versions do not support SSE without patches. 558 bool os::supports_sse() { 559 #ifdef AMD64 560 return true; 561 #else 562 struct utsname uts; 563 if( uname(&uts) != 0 ) return false; // uname fails? 564 char *minor_string; 565 int major = strtol(uts.release,&minor_string,10); 566 int minor = strtol(minor_string+1,NULL,10); 567 bool result = (major > 2 || (major==2 && minor >= 4)); 568 #ifndef PRODUCT 569 if (PrintMiscellaneous && Verbose) { 570 tty->print("OS version is %d.%d, which %s support SSE/SSE2\n", 571 major,minor, result ? "DOES" : "does NOT"); 572 } 573 #endif 574 return result; 575 #endif // AMD64 576 } 577 578 bool os::is_allocatable(size_t bytes) { 579 #ifdef AMD64 580 // unused on amd64? 581 return true; 582 #else 583 584 if (bytes < 2 * G) { 585 return true; 586 } 587 588 char* addr = reserve_memory(bytes, NULL); 589 590 if (addr != NULL) { 591 release_memory(addr, bytes); 592 } 593 594 return addr != NULL; 595 #endif // AMD64 596 } 597 598 //////////////////////////////////////////////////////////////////////////////// 599 // thread stack 600 601 #ifdef AMD64 602 size_t os::Linux::min_stack_allowed = 64 * K; 603 604 // amd64: pthread on amd64 is always in floating stack mode 605 bool os::Linux::supports_variable_stack_size() { return true; } 606 #else 607 size_t os::Linux::min_stack_allowed = (48 DEBUG_ONLY(+4))*K; 608 609 #ifdef __GNUC__ 610 #define GET_GS() ({int gs; __asm__ volatile("movw %%gs, %w0":"=q"(gs)); gs&0xffff;}) 611 #endif 612 613 // Test if pthread library can support variable thread stack size. LinuxThreads 614 // in fixed stack mode allocates 2M fixed slot for each thread. LinuxThreads 615 // in floating stack mode and NPTL support variable stack size. 616 bool os::Linux::supports_variable_stack_size() { 617 if (os::Linux::is_NPTL()) { 618 // NPTL, yes 619 return true; 620 621 } else { 622 // Note: We can't control default stack size when creating a thread. 623 // If we use non-default stack size (pthread_attr_setstacksize), both 624 // floating stack and non-floating stack LinuxThreads will return the 625 // same value. This makes it impossible to implement this function by 626 // detecting thread stack size directly. 627 // 628 // An alternative approach is to check %gs. Fixed-stack LinuxThreads 629 // do not use %gs, so its value is 0. Floating-stack LinuxThreads use 630 // %gs (either as LDT selector or GDT selector, depending on kernel) 631 // to access thread specific data. 632 // 633 // Note that %gs is a reserved glibc register since early 2001, so 634 // applications are not allowed to change its value (Ulrich Drepper from 635 // Redhat confirmed that all known offenders have been modified to use 636 // either %fs or TSD). In the worst case scenario, when VM is embedded in 637 // a native application that plays with %gs, we might see non-zero %gs 638 // even LinuxThreads is running in fixed stack mode. As the result, we'll 639 // return true and skip _thread_safety_check(), so we may not be able to 640 // detect stack-heap collisions. But otherwise it's harmless. 641 // 642 #ifdef __GNUC__ 643 return (GET_GS() != 0); 644 #else 645 return false; 646 #endif 647 } 648 } 649 #endif // AMD64 650 651 // return default stack size for thr_type 652 size_t os::Linux::default_stack_size(os::ThreadType thr_type) { 653 // default stack size (compiler thread needs larger stack) 654 #ifdef AMD64 655 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M); 656 #else 657 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K); 658 #endif // AMD64 659 return s; 660 } 661 662 size_t os::Linux::default_guard_size(os::ThreadType thr_type) { 663 // Creating guard page is very expensive. Java thread has HotSpot 664 // guard page, only enable glibc guard page for non-Java threads. 665 return (thr_type == java_thread ? 0 : page_size()); 666 } 667 668 // Java thread: 669 // 670 // Low memory addresses 671 // +------------------------+ 672 // | |\ JavaThread created by VM does not have glibc 673 // | glibc guard page | - guard, attached Java thread usually has 674 // | |/ 1 page glibc guard. 675 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size() 676 // | |\ 677 // | HotSpot Guard Pages | - red and yellow pages 678 // | |/ 679 // +------------------------+ JavaThread::stack_yellow_zone_base() 680 // | |\ 681 // | Normal Stack | - 682 // | |/ 683 // P2 +------------------------+ Thread::stack_base() 684 // 685 // Non-Java thread: 686 // 687 // Low memory addresses 688 // +------------------------+ 689 // | |\ 690 // | glibc guard page | - usually 1 page 691 // | |/ 692 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size() 693 // | |\ 694 // | Normal Stack | - 695 // | |/ 696 // P2 +------------------------+ Thread::stack_base() 697 // 698 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from 699 // pthread_attr_getstack() 700 701 static void current_stack_region(address * bottom, size_t * size) { 702 if (os::Linux::is_initial_thread()) { 703 // initial thread needs special handling because pthread_getattr_np() 704 // may return bogus value. 705 *bottom = os::Linux::initial_thread_stack_bottom(); 706 *size = os::Linux::initial_thread_stack_size(); 707 } else { 708 pthread_attr_t attr; 709 710 int rslt = pthread_getattr_np(pthread_self(), &attr); 711 712 // JVM needs to know exact stack location, abort if it fails 713 if (rslt != 0) { 714 if (rslt == ENOMEM) { 715 vm_exit_out_of_memory(0, "pthread_getattr_np"); 716 } else { 717 fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt)); 718 } 719 } 720 721 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) { 722 fatal("Can not locate current stack attributes!"); 723 } 724 725 pthread_attr_destroy(&attr); 726 727 } 728 assert(os::current_stack_pointer() >= *bottom && 729 os::current_stack_pointer() < *bottom + *size, "just checking"); 730 } 731 732 address os::current_stack_base() { 733 address bottom; 734 size_t size; 735 current_stack_region(&bottom, &size); 736 return (bottom + size); 737 } 738 739 size_t os::current_stack_size() { 740 // stack size includes normal stack and HotSpot guard pages 741 address bottom; 742 size_t size; 743 current_stack_region(&bottom, &size); 744 return size; 745 } 746 747 ///////////////////////////////////////////////////////////////////////////// 748 // helper functions for fatal error handler 749 750 void os::print_context(outputStream *st, void *context) { 751 if (context == NULL) return; 752 753 ucontext_t *uc = (ucontext_t*)context; 754 st->print_cr("Registers:"); 755 #ifdef AMD64 756 st->print( "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]); 757 st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]); 758 st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]); 759 st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]); 760 st->cr(); 761 st->print( "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]); 762 st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]); 763 st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]); 764 st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]); 765 st->cr(); 766 st->print( "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]); 767 st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]); 768 st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]); 769 st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]); 770 st->cr(); 771 st->print( "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]); 772 st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]); 773 st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]); 774 st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]); 775 st->cr(); 776 st->print( "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]); 777 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]); 778 st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]); 779 st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]); 780 st->cr(); 781 st->print(" TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]); 782 #else 783 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]); 784 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]); 785 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]); 786 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]); 787 st->cr(); 788 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]); 789 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]); 790 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]); 791 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]); 792 st->cr(); 793 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]); 794 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]); 795 st->print(", CR2=" INTPTR_FORMAT, uc->uc_mcontext.cr2); 796 #endif // AMD64 797 st->cr(); 798 st->cr(); 799 800 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc); 801 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp); 802 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t)); 803 st->cr(); 804 805 // Note: it may be unsafe to inspect memory near pc. For example, pc may 806 // point to garbage if entry point in an nmethod is corrupted. Leave 807 // this at the end, and hope for the best. 808 address pc = os::Linux::ucontext_get_pc(uc); 809 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc); 810 print_hex_dump(st, pc - 32, pc + 32, sizeof(char)); 811 } 812 813 void os::print_register_info(outputStream *st, void *context) { 814 if (context == NULL) return; 815 816 ucontext_t *uc = (ucontext_t*)context; 817 818 st->print_cr("Register to memory mapping:"); 819 st->cr(); 820 821 // this is horrendously verbose but the layout of the registers in the 822 // context does not match how we defined our abstract Register set, so 823 // we can't just iterate through the gregs area 824 825 // this is only for the "general purpose" registers 826 827 #ifdef AMD64 828 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]); 829 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]); 830 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]); 831 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]); 832 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]); 833 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]); 834 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]); 835 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]); 836 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]); 837 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]); 838 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]); 839 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]); 840 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]); 841 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]); 842 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]); 843 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]); 844 #else 845 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]); 846 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]); 847 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]); 848 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]); 849 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]); 850 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]); 851 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]); 852 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]); 853 #endif // AMD64 854 855 st->cr(); 856 } 857 858 void os::setup_fpu() { 859 #ifndef AMD64 860 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std(); 861 __asm__ volatile ( "fldcw (%0)" : 862 : "r" (fpu_cntrl) : "memory"); 863 #endif // !AMD64 864 } 865 866 #ifndef PRODUCT 867 void os::verify_stack_alignment() { 868 #ifdef AMD64 869 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment"); 870 #endif 871 } 872 #endif