os_linux_x86.cpp revision 12469:c7a256349729
12786Ssos/* 22786Ssos * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved. 32786Ssos * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 42786Ssos * 52786Ssos * This code is free software; you can redistribute it and/or modify it 62786Ssos * under the terms of the GNU General Public License version 2 only, as 72786Ssos * published by the Free Software Foundation. 86851Ssos * 92786Ssos * This code is distributed in the hope that it will be useful, but WITHOUT 102786Ssos * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 112786Ssos * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 122786Ssos * version 2 for more details (a copy is included in the LICENSE file that 132786Ssos * accompanied this code). 142786Ssos * 152786Ssos * You should have received a copy of the GNU General Public License version 162786Ssos * 2 along with this work; if not, write to the Free Software Foundation, 172786Ssos * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 182786Ssos * 192786Ssos * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 204686Sache * or visit www.oracle.com if you need additional information or have any 212786Ssos * questions. 222786Ssos * 232786Ssos */ 242786Ssos 252786Ssos// no precompiled headers 262786Ssos#include "asm/macroAssembler.hpp" 272786Ssos#include "classfile/classLoader.hpp" 282786Ssos#include "classfile/systemDictionary.hpp" 292786Ssos#include "classfile/vmSymbols.hpp" 302786Ssos#include "code/codeCache.hpp" 312786Ssos#include "code/icBuffer.hpp" 322786Ssos#include "code/vtableStubs.hpp" 332786Ssos#include "interpreter/interpreter.hpp" 342786Ssos#include "jvm_linux.h" 352786Ssos#include "memory/allocation.inline.hpp" 362786Ssos#include "os_share_linux.hpp" 372786Ssos#include "prims/jniFastGetField.hpp" 382786Ssos#include "prims/jvm.h" 392786Ssos#include "prims/jvm_misc.hpp" 402786Ssos#include "runtime/arguments.hpp" 412786Ssos#include "runtime/extendedPC.hpp" 422786Ssos#include "runtime/frame.inline.hpp" 432786Ssos#include "runtime/interfaceSupport.hpp" 442786Ssos#include "runtime/java.hpp" 452786Ssos#include "runtime/javaCalls.hpp" 462786Ssos#include "runtime/mutexLocker.hpp" 472786Ssos#include "runtime/osThread.hpp" 482786Ssos#include "runtime/sharedRuntime.hpp" 492786Ssos#include "runtime/stubRoutines.hpp" 502786Ssos#include "runtime/thread.inline.hpp" 512786Ssos#include "runtime/timer.hpp" 522786Ssos#include "services/memTracker.hpp" 532786Ssos#include "utilities/events.hpp" 542786Ssos#include "utilities/vmError.hpp" 552786Ssos 562786Ssos// put OS-includes here 572786Ssos# include <sys/types.h> 582786Ssos# include <sys/mman.h> 592786Ssos# include <pthread.h> 602786Ssos# include <signal.h> 612786Ssos# include <errno.h> 626851Ssos# include <dlfcn.h> 632786Ssos# include <stdlib.h> 642786Ssos# include <stdio.h> 652786Ssos# include <unistd.h> 662786Ssos# include <sys/resource.h> 672786Ssos# include <pthread.h> 682786Ssos# include <sys/stat.h> 692786Ssos# include <sys/time.h> 702786Ssos# include <sys/utsname.h> 712786Ssos# include <sys/socket.h> 722786Ssos# include <sys/wait.h> 732786Ssos# include <pwd.h> 742786Ssos# include <poll.h> 752786Ssos# include <ucontext.h> 762786Ssos# include <fpu_control.h> 772786Ssos 782786Ssos#ifdef AMD64 792786Ssos#define REG_SP REG_RSP 802786Ssos#define REG_PC REG_RIP 815994Ssos#define REG_FP REG_RBP 822786Ssos#define SPELL_REG_SP "rsp" 832786Ssos#define SPELL_REG_FP "rbp" 842786Ssos#else 852786Ssos#define REG_SP REG_UESP 862786Ssos#define REG_PC REG_EIP 872786Ssos#define REG_FP REG_EBP 886045Ssos#define SPELL_REG_SP "esp" 892786Ssos#define SPELL_REG_FP "ebp" 902786Ssos#endif // AMD64 912786Ssos 922786Ssosaddress os::current_stack_pointer() { 932786Ssos#ifdef SPARC_WORKS 942786Ssos register void *esp; 952786Ssos __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp)); 962786Ssos return (address) ((char*)esp + sizeof(long)*2); 972786Ssos#elif defined(__clang__) 982786Ssos intptr_t* esp; 992786Ssos __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):); 1002786Ssos return (address) esp; 1012786Ssos#else 1022786Ssos register void *esp __asm__ (SPELL_REG_SP); 1032786Ssos return (address) esp; 1042786Ssos#endif 1052786Ssos} 1062786Ssos 1072786Ssoschar* os::non_memory_address_word() { 1086851Ssos // Must never look like an address returned by reserve_memory, 1092786Ssos // even in its subfields (as defined by the CPU immediate fields, 1106851Ssos // if the CPU splits constants across multiple instructions). 1116851Ssos 1126851Ssos return (char*) -1; 113} 114 115void os::initialize_thread(Thread* thr) { 116// Nothing to do. 117} 118 119address os::Linux::ucontext_get_pc(const ucontext_t * uc) { 120 return (address)uc->uc_mcontext.gregs[REG_PC]; 121} 122 123void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) { 124 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc; 125} 126 127intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) { 128 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP]; 129} 130 131intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) { 132 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP]; 133} 134 135// For Forte Analyzer AsyncGetCallTrace profiling support - thread 136// is currently interrupted by SIGPROF. 137// os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal 138// frames. Currently we don't do that on Linux, so it's the same as 139// os::fetch_frame_from_context(). 140// This method is also used for stack overflow signal handling. 141ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread, 142 const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) { 143 144 assert(thread != NULL, "just checking"); 145 assert(ret_sp != NULL, "just checking"); 146 assert(ret_fp != NULL, "just checking"); 147 148 return os::fetch_frame_from_context(uc, ret_sp, ret_fp); 149} 150 151ExtendedPC os::fetch_frame_from_context(const void* ucVoid, 152 intptr_t** ret_sp, intptr_t** ret_fp) { 153 154 ExtendedPC epc; 155 const ucontext_t* uc = (const ucontext_t*)ucVoid; 156 157 if (uc != NULL) { 158 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc)); 159 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc); 160 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc); 161 } else { 162 // construct empty ExtendedPC for return value checking 163 epc = ExtendedPC(NULL); 164 if (ret_sp) *ret_sp = (intptr_t *)NULL; 165 if (ret_fp) *ret_fp = (intptr_t *)NULL; 166 } 167 168 return epc; 169} 170 171frame os::fetch_frame_from_context(const void* ucVoid) { 172 intptr_t* sp; 173 intptr_t* fp; 174 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp); 175 return frame(sp, fp, epc.pc()); 176} 177 178frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) { 179 intptr_t* sp; 180 intptr_t* fp; 181 ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp); 182 return frame(sp, fp, epc.pc()); 183} 184 185bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) { 186 address pc = (address) os::Linux::ucontext_get_pc(uc); 187 if (Interpreter::contains(pc)) { 188 // interpreter performs stack banging after the fixed frame header has 189 // been generated while the compilers perform it before. To maintain 190 // semantic consistency between interpreted and compiled frames, the 191 // method returns the Java sender of the current frame. 192 *fr = os::fetch_frame_from_ucontext(thread, uc); 193 if (!fr->is_first_java_frame()) { 194 // get_frame_at_stack_banging_point() is only called when we 195 // have well defined stacks so java_sender() calls do not need 196 // to assert safe_for_sender() first. 197 *fr = fr->java_sender(); 198 } 199 } else { 200 // more complex code with compiled code 201 assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above"); 202 CodeBlob* cb = CodeCache::find_blob(pc); 203 if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) { 204 // Not sure where the pc points to, fallback to default 205 // stack overflow handling 206 return false; 207 } else { 208 // in compiled code, the stack banging is performed just after the return pc 209 // has been pushed on the stack 210 intptr_t* fp = os::Linux::ucontext_get_fp(uc); 211 intptr_t* sp = os::Linux::ucontext_get_sp(uc); 212 *fr = frame(sp + 1, fp, (address)*sp); 213 if (!fr->is_java_frame()) { 214 assert(!fr->is_first_frame(), "Safety check"); 215 // See java_sender() comment above. 216 *fr = fr->java_sender(); 217 } 218 } 219 } 220 assert(fr->is_java_frame(), "Safety check"); 221 return true; 222} 223 224// By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get 225// turned off by -fomit-frame-pointer, 226frame os::get_sender_for_C_frame(frame* fr) { 227 return frame(fr->sender_sp(), fr->link(), fr->sender_pc()); 228} 229 230intptr_t* _get_previous_fp() { 231#ifdef SPARC_WORKS 232 register intptr_t **ebp; 233 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp)); 234#elif defined(__clang__) 235 intptr_t **ebp; 236 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):); 237#else 238 register intptr_t **ebp __asm__ (SPELL_REG_FP); 239#endif 240 // ebp is for this frame (_get_previous_fp). We want the ebp for the 241 // caller of os::current_frame*(), so go up two frames. However, for 242 // optimized builds, _get_previous_fp() will be inlined, so only go 243 // up 1 frame in that case. 244#ifdef _NMT_NOINLINE_ 245 return **(intptr_t***)ebp; 246#else 247 return *ebp; 248#endif 249} 250 251 252frame os::current_frame() { 253 intptr_t* fp = _get_previous_fp(); 254 frame myframe((intptr_t*)os::current_stack_pointer(), 255 (intptr_t*)fp, 256 CAST_FROM_FN_PTR(address, os::current_frame)); 257 if (os::is_first_C_frame(&myframe)) { 258 // stack is not walkable 259 return frame(); 260 } else { 261 return os::get_sender_for_C_frame(&myframe); 262 } 263} 264 265// Utility functions 266 267// From IA32 System Programming Guide 268enum { 269 trap_page_fault = 0xE 270}; 271 272extern "C" JNIEXPORT int 273JVM_handle_linux_signal(int sig, 274 siginfo_t* info, 275 void* ucVoid, 276 int abort_if_unrecognized) { 277 ucontext_t* uc = (ucontext_t*) ucVoid; 278 279 Thread* t = Thread::current_or_null_safe(); 280 281 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away 282 // (no destructors can be run) 283 os::WatcherThreadCrashProtection::check_crash_protection(sig, t); 284 285 SignalHandlerMark shm(t); 286 287 // Note: it's not uncommon that JNI code uses signal/sigset to install 288 // then restore certain signal handler (e.g. to temporarily block SIGPIPE, 289 // or have a SIGILL handler when detecting CPU type). When that happens, 290 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To 291 // avoid unnecessary crash when libjsig is not preloaded, try handle signals 292 // that do not require siginfo/ucontext first. 293 294 if (sig == SIGPIPE || sig == SIGXFSZ) { 295 // allow chained handler to go first 296 if (os::Linux::chained_handler(sig, info, ucVoid)) { 297 return true; 298 } else { 299 // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219 300 return true; 301 } 302 } 303 304 JavaThread* thread = NULL; 305 VMThread* vmthread = NULL; 306 if (os::Linux::signal_handlers_are_installed) { 307 if (t != NULL ){ 308 if(t->is_Java_thread()) { 309 thread = (JavaThread*)t; 310 } 311 else if(t->is_VM_thread()){ 312 vmthread = (VMThread *)t; 313 } 314 } 315 } 316/* 317 NOTE: does not seem to work on linux. 318 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) { 319 // can't decode this kind of signal 320 info = NULL; 321 } else { 322 assert(sig == info->si_signo, "bad siginfo"); 323 } 324*/ 325 // decide if this trap can be handled by a stub 326 address stub = NULL; 327 328 address pc = NULL; 329 330 //%note os_trap_1 331 if (info != NULL && uc != NULL && thread != NULL) { 332 pc = (address) os::Linux::ucontext_get_pc(uc); 333 334 if (StubRoutines::is_safefetch_fault(pc)) { 335 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc)); 336 return 1; 337 } 338 339#ifndef AMD64 340 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs 341 // This can happen in any running code (currently more frequently in 342 // interpreter code but has been seen in compiled code) 343 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) { 344 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due " 345 "to unstable signal handling in this distribution."); 346 } 347#endif // AMD64 348 349 // Handle ALL stack overflow variations here 350 if (sig == SIGSEGV) { 351 address addr = (address) info->si_addr; 352 353 // check if fault address is within thread stack 354 if (thread->on_local_stack(addr)) { 355 // stack overflow 356 if (thread->in_stack_yellow_reserved_zone(addr)) { 357 if (thread->thread_state() == _thread_in_Java) { 358 if (thread->in_stack_reserved_zone(addr)) { 359 frame fr; 360 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) { 361 assert(fr.is_java_frame(), "Must be a Java frame"); 362 frame activation = 363 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr); 364 if (activation.sp() != NULL) { 365 thread->disable_stack_reserved_zone(); 366 if (activation.is_interpreted_frame()) { 367 thread->set_reserved_stack_activation((address)( 368 activation.fp() + frame::interpreter_frame_initial_sp_offset)); 369 } else { 370 thread->set_reserved_stack_activation((address)activation.unextended_sp()); 371 } 372 return 1; 373 } 374 } 375 } 376 // Throw a stack overflow exception. Guard pages will be reenabled 377 // while unwinding the stack. 378 thread->disable_stack_yellow_reserved_zone(); 379 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW); 380 } else { 381 // Thread was in the vm or native code. Return and try to finish. 382 thread->disable_stack_yellow_reserved_zone(); 383 return 1; 384 } 385 } else if (thread->in_stack_red_zone(addr)) { 386 // Fatal red zone violation. Disable the guard pages and fall through 387 // to handle_unexpected_exception way down below. 388 thread->disable_stack_red_zone(); 389 tty->print_raw_cr("An irrecoverable stack overflow has occurred."); 390 391 // This is a likely cause, but hard to verify. Let's just print 392 // it as a hint. 393 tty->print_raw_cr("Please check if any of your loaded .so files has " 394 "enabled executable stack (see man page execstack(8))"); 395 } else { 396 // Accessing stack address below sp may cause SEGV if current 397 // thread has MAP_GROWSDOWN stack. This should only happen when 398 // current thread was created by user code with MAP_GROWSDOWN flag 399 // and then attached to VM. See notes in os_linux.cpp. 400 if (thread->osthread()->expanding_stack() == 0) { 401 thread->osthread()->set_expanding_stack(); 402 if (os::Linux::manually_expand_stack(thread, addr)) { 403 thread->osthread()->clear_expanding_stack(); 404 return 1; 405 } 406 thread->osthread()->clear_expanding_stack(); 407 } else { 408 fatal("recursive segv. expanding stack."); 409 } 410 } 411 } 412 } 413 414 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) { 415 // Verify that OS save/restore AVX registers. 416 stub = VM_Version::cpuinfo_cont_addr(); 417 } 418 419 if (thread->thread_state() == _thread_in_Java) { 420 // Java thread running in Java code => find exception handler if any 421 // a fault inside compiled code, the interpreter, or a stub 422 423 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) { 424 stub = SharedRuntime::get_poll_stub(pc); 425 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) { 426 // BugId 4454115: A read from a MappedByteBuffer can fault 427 // here if the underlying file has been truncated. 428 // Do not crash the VM in such a case. 429 CodeBlob* cb = CodeCache::find_blob_unsafe(pc); 430 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL; 431 if (nm != NULL && nm->has_unsafe_access()) { 432 address next_pc = Assembler::locate_next_instruction(pc); 433 stub = SharedRuntime::handle_unsafe_access(thread, next_pc); 434 } 435 } 436 else 437 438#ifdef AMD64 439 if (sig == SIGFPE && 440 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) { 441 stub = 442 SharedRuntime:: 443 continuation_for_implicit_exception(thread, 444 pc, 445 SharedRuntime:: 446 IMPLICIT_DIVIDE_BY_ZERO); 447#else 448 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) { 449 // HACK: si_code does not work on linux 2.2.12-20!!! 450 int op = pc[0]; 451 if (op == 0xDB) { 452 // FIST 453 // TODO: The encoding of D2I in i486.ad can cause an exception 454 // prior to the fist instruction if there was an invalid operation 455 // pending. We want to dismiss that exception. From the win_32 456 // side it also seems that if it really was the fist causing 457 // the exception that we do the d2i by hand with different 458 // rounding. Seems kind of weird. 459 // NOTE: that we take the exception at the NEXT floating point instruction. 460 assert(pc[0] == 0xDB, "not a FIST opcode"); 461 assert(pc[1] == 0x14, "not a FIST opcode"); 462 assert(pc[2] == 0x24, "not a FIST opcode"); 463 return true; 464 } else if (op == 0xF7) { 465 // IDIV 466 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO); 467 } else { 468 // TODO: handle more cases if we are using other x86 instructions 469 // that can generate SIGFPE signal on linux. 470 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op); 471 fatal("please update this code."); 472 } 473#endif // AMD64 474 } else if (sig == SIGSEGV && 475 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) { 476 // Determination of interpreter/vtable stub/compiled code null exception 477 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 478 } 479 } else if (thread->thread_state() == _thread_in_vm && 480 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */ 481 thread->doing_unsafe_access()) { 482 address next_pc = Assembler::locate_next_instruction(pc); 483 stub = SharedRuntime::handle_unsafe_access(thread, next_pc); 484 } 485 486 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in 487 // and the heap gets shrunk before the field access. 488 if ((sig == SIGSEGV) || (sig == SIGBUS)) { 489 address addr = JNI_FastGetField::find_slowcase_pc(pc); 490 if (addr != (address)-1) { 491 stub = addr; 492 } 493 } 494 495 // Check to see if we caught the safepoint code in the 496 // process of write protecting the memory serialization page. 497 // It write enables the page immediately after protecting it 498 // so we can just return to retry the write. 499 if ((sig == SIGSEGV) && 500 os::is_memory_serialize_page(thread, (address) info->si_addr)) { 501 // Block current thread until the memory serialize page permission restored. 502 os::block_on_serialize_page_trap(); 503 return true; 504 } 505 } 506 507#ifndef AMD64 508 // Execution protection violation 509 // 510 // This should be kept as the last step in the triage. We don't 511 // have a dedicated trap number for a no-execute fault, so be 512 // conservative and allow other handlers the first shot. 513 // 514 // Note: We don't test that info->si_code == SEGV_ACCERR here. 515 // this si_code is so generic that it is almost meaningless; and 516 // the si_code for this condition may change in the future. 517 // Furthermore, a false-positive should be harmless. 518 if (UnguardOnExecutionViolation > 0 && 519 (sig == SIGSEGV || sig == SIGBUS) && 520 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) { 521 int page_size = os::vm_page_size(); 522 address addr = (address) info->si_addr; 523 address pc = os::Linux::ucontext_get_pc(uc); 524 // Make sure the pc and the faulting address are sane. 525 // 526 // If an instruction spans a page boundary, and the page containing 527 // the beginning of the instruction is executable but the following 528 // page is not, the pc and the faulting address might be slightly 529 // different - we still want to unguard the 2nd page in this case. 530 // 531 // 15 bytes seems to be a (very) safe value for max instruction size. 532 bool pc_is_near_addr = 533 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15); 534 bool instr_spans_page_boundary = 535 (align_size_down((intptr_t) pc ^ (intptr_t) addr, 536 (intptr_t) page_size) > 0); 537 538 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) { 539 static volatile address last_addr = 540 (address) os::non_memory_address_word(); 541 542 // In conservative mode, don't unguard unless the address is in the VM 543 if (addr != last_addr && 544 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) { 545 546 // Set memory to RWX and retry 547 address page_start = 548 (address) align_size_down((intptr_t) addr, (intptr_t) page_size); 549 bool res = os::protect_memory((char*) page_start, page_size, 550 os::MEM_PROT_RWX); 551 552 log_debug(os)("Execution protection violation " 553 "at " INTPTR_FORMAT 554 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr), 555 p2i(page_start), (res ? "success" : "failed"), errno); 556 stub = pc; 557 558 // Set last_addr so if we fault again at the same address, we don't end 559 // up in an endless loop. 560 // 561 // There are two potential complications here. Two threads trapping at 562 // the same address at the same time could cause one of the threads to 563 // think it already unguarded, and abort the VM. Likely very rare. 564 // 565 // The other race involves two threads alternately trapping at 566 // different addresses and failing to unguard the page, resulting in 567 // an endless loop. This condition is probably even more unlikely than 568 // the first. 569 // 570 // Although both cases could be avoided by using locks or thread local 571 // last_addr, these solutions are unnecessary complication: this 572 // handler is a best-effort safety net, not a complete solution. It is 573 // disabled by default and should only be used as a workaround in case 574 // we missed any no-execute-unsafe VM code. 575 576 last_addr = addr; 577 } 578 } 579 } 580#endif // !AMD64 581 582 if (stub != NULL) { 583 // save all thread context in case we need to restore it 584 if (thread != NULL) thread->set_saved_exception_pc(pc); 585 586 os::Linux::ucontext_set_pc(uc, stub); 587 return true; 588 } 589 590 // signal-chaining 591 if (os::Linux::chained_handler(sig, info, ucVoid)) { 592 return true; 593 } 594 595 if (!abort_if_unrecognized) { 596 // caller wants another chance, so give it to him 597 return false; 598 } 599 600 if (pc == NULL && uc != NULL) { 601 pc = os::Linux::ucontext_get_pc(uc); 602 } 603 604 // unmask current signal 605 sigset_t newset; 606 sigemptyset(&newset); 607 sigaddset(&newset, sig); 608 sigprocmask(SIG_UNBLOCK, &newset, NULL); 609 610 VMError::report_and_die(t, sig, pc, info, ucVoid); 611 612 ShouldNotReachHere(); 613 return true; // Mute compiler 614} 615 616void os::Linux::init_thread_fpu_state(void) { 617#ifndef AMD64 618 // set fpu to 53 bit precision 619 set_fpu_control_word(0x27f); 620#endif // !AMD64 621} 622 623int os::Linux::get_fpu_control_word(void) { 624#ifdef AMD64 625 return 0; 626#else 627 int fpu_control; 628 _FPU_GETCW(fpu_control); 629 return fpu_control & 0xffff; 630#endif // AMD64 631} 632 633void os::Linux::set_fpu_control_word(int fpu_control) { 634#ifndef AMD64 635 _FPU_SETCW(fpu_control); 636#endif // !AMD64 637} 638 639// Check that the linux kernel version is 2.4 or higher since earlier 640// versions do not support SSE without patches. 641bool os::supports_sse() { 642#ifdef AMD64 643 return true; 644#else 645 struct utsname uts; 646 if( uname(&uts) != 0 ) return false; // uname fails? 647 char *minor_string; 648 int major = strtol(uts.release,&minor_string,10); 649 int minor = strtol(minor_string+1,NULL,10); 650 bool result = (major > 2 || (major==2 && minor >= 4)); 651 log_info(os)("OS version is %d.%d, which %s support SSE/SSE2", 652 major,minor, result ? "DOES" : "does NOT"); 653 return result; 654#endif // AMD64 655} 656 657bool os::is_allocatable(size_t bytes) { 658#ifdef AMD64 659 // unused on amd64? 660 return true; 661#else 662 663 if (bytes < 2 * G) { 664 return true; 665 } 666 667 char* addr = reserve_memory(bytes, NULL); 668 669 if (addr != NULL) { 670 release_memory(addr, bytes); 671 } 672 673 return addr != NULL; 674#endif // AMD64 675} 676 677//////////////////////////////////////////////////////////////////////////////// 678// thread stack 679 680// Minimum usable stack sizes required to get to user code. Space for 681// HotSpot guard pages is added later. 682size_t os::Posix::_compiler_thread_min_stack_allowed = 48 * K; 683size_t os::Posix::_java_thread_min_stack_allowed = 40 * K; 684#ifdef _LP64 685size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K; 686#else 687size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K; 688#endif // _LP64 689 690// return default stack size for thr_type 691size_t os::Posix::default_stack_size(os::ThreadType thr_type) { 692 // default stack size (compiler thread needs larger stack) 693#ifdef AMD64 694 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M); 695#else 696 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K); 697#endif // AMD64 698 return s; 699} 700 701///////////////////////////////////////////////////////////////////////////// 702// helper functions for fatal error handler 703 704void os::print_context(outputStream *st, const void *context) { 705 if (context == NULL) return; 706 707 const ucontext_t *uc = (const ucontext_t*)context; 708 st->print_cr("Registers:"); 709#ifdef AMD64 710 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]); 711 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]); 712 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]); 713 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]); 714 st->cr(); 715 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]); 716 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]); 717 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]); 718 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]); 719 st->cr(); 720 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]); 721 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]); 722 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]); 723 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]); 724 st->cr(); 725 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]); 726 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]); 727 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]); 728 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]); 729 st->cr(); 730 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]); 731 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]); 732 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]); 733 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]); 734 st->cr(); 735 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]); 736#else 737 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]); 738 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]); 739 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]); 740 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]); 741 st->cr(); 742 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]); 743 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]); 744 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]); 745 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]); 746 st->cr(); 747 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]); 748 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]); 749 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2); 750#endif // AMD64 751 st->cr(); 752 st->cr(); 753 754 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc); 755 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp)); 756 print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t)); 757 st->cr(); 758 759 // Note: it may be unsafe to inspect memory near pc. For example, pc may 760 // point to garbage if entry point in an nmethod is corrupted. Leave 761 // this at the end, and hope for the best. 762 address pc = os::Linux::ucontext_get_pc(uc); 763 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc)); 764 print_hex_dump(st, pc - 32, pc + 32, sizeof(char)); 765} 766 767void os::print_register_info(outputStream *st, const void *context) { 768 if (context == NULL) return; 769 770 const ucontext_t *uc = (const ucontext_t*)context; 771 772 st->print_cr("Register to memory mapping:"); 773 st->cr(); 774 775 // this is horrendously verbose but the layout of the registers in the 776 // context does not match how we defined our abstract Register set, so 777 // we can't just iterate through the gregs area 778 779 // this is only for the "general purpose" registers 780 781#ifdef AMD64 782 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]); 783 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]); 784 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]); 785 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]); 786 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]); 787 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]); 788 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]); 789 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]); 790 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]); 791 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]); 792 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]); 793 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]); 794 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]); 795 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]); 796 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]); 797 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]); 798#else 799 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]); 800 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]); 801 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]); 802 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]); 803 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]); 804 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]); 805 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]); 806 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]); 807#endif // AMD64 808 809 st->cr(); 810} 811 812void os::setup_fpu() { 813#ifndef AMD64 814 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std(); 815 __asm__ volatile ( "fldcw (%0)" : 816 : "r" (fpu_cntrl) : "memory"); 817#endif // !AMD64 818} 819 820#ifndef PRODUCT 821void os::verify_stack_alignment() { 822#ifdef AMD64 823 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment"); 824#endif 825} 826#endif 827 828 829/* 830 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit 831 * updates (JDK-8023956). 832 */ 833void os::workaround_expand_exec_shield_cs_limit() { 834#if defined(IA32) 835 size_t page_size = os::vm_page_size(); 836 /* 837 * Take the highest VA the OS will give us and exec 838 * 839 * Although using -(pagesz) as mmap hint works on newer kernel as you would 840 * think, older variants affected by this work-around don't (search forward only). 841 * 842 * On the affected distributions, we understand the memory layout to be: 843 * 844 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT. 845 * 846 * A few pages south main stack will do it. 847 * 848 * If we are embedded in an app other than launcher (initial != main stack), 849 * we don't have much control or understanding of the address space, just let it slide. 850 */ 851 char* hint = (char*)(Linux::initial_thread_stack_bottom() - 852 (JavaThread::stack_guard_zone_size() + page_size)); 853 char* codebuf = os::attempt_reserve_memory_at(page_size, hint); 854 if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) { 855 return; // No matter, we tried, best effort. 856 } 857 858 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal); 859 860 log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf); 861 862 // Some code to exec: the 'ret' instruction 863 codebuf[0] = 0xC3; 864 865 // Call the code in the codebuf 866 __asm__ volatile("call *%0" : : "r"(codebuf)); 867 868 // keep the page mapped so CS limit isn't reduced. 869#endif 870} 871 872int os::extra_bang_size_in_bytes() { 873 // JDK-8050147 requires the full cache line bang for x86. 874 return VM_Version::L1_line_size(); 875} 876