1 /* 2 * Copyright (c) 1999, 2018, 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 "jvm.h" 27 #include "asm/macroAssembler.hpp" 28 #include "classfile/classLoader.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/icBuffer.hpp" 33 #include "code/vtableStubs.hpp" 34 #include "interpreter/interpreter.hpp" 35 #include "logging/log.hpp" 36 #include "memory/allocation.inline.hpp" 37 #include "os_share_linux.hpp" 38 #include "prims/jniFastGetField.hpp" 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.inline.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 "services/memTracker.hpp" 53 #include "utilities/align.hpp" 54 #include "utilities/debug.hpp" 55 #include "utilities/events.hpp" 56 #include "utilities/vmError.hpp" 57 58 // put OS-includes here 59 # include <sys/types.h> 60 # include <sys/mman.h> 61 # include <pthread.h> 62 # include <signal.h> 63 # include <errno.h> 64 # include <dlfcn.h> 65 # include <stdlib.h> 66 # include <stdio.h> 67 # include <unistd.h> 68 # include <sys/resource.h> 69 # include <pthread.h> 70 # include <sys/stat.h> 71 # include <sys/time.h> 72 # include <sys/utsname.h> 73 # include <sys/socket.h> 74 # include <sys/wait.h> 75 # include <pwd.h> 76 # include <poll.h> 77 # include <ucontext.h> 78 #ifndef AMD64 79 # include <fpu_control.h> 80 #endif 81 82 #ifdef AMD64 83 #define REG_SP REG_RSP 84 #define REG_PC REG_RIP 85 #define REG_FP REG_RBP 86 #define SPELL_REG_SP "rsp" 87 #define SPELL_REG_FP "rbp" 88 #else 89 #define REG_SP REG_UESP 90 #define REG_PC REG_EIP 91 #define REG_FP REG_EBP 92 #define SPELL_REG_SP "esp" 93 #define SPELL_REG_FP "ebp" 94 #endif // AMD64 95 96 address os::current_stack_pointer() { 97 #ifdef SPARC_WORKS 98 void *esp; 99 __asm__("mov %%" SPELL_REG_SP ", %0":"=r"(esp)); 100 return (address) ((char*)esp + sizeof(long)*2); 101 #elif defined(__clang__) 102 void* esp; 103 __asm__ __volatile__ ("mov %%" SPELL_REG_SP ", %0":"=r"(esp):); 104 return (address) esp; 105 #else 106 register void *esp __asm__ (SPELL_REG_SP); 107 return (address) esp; 108 #endif 109 } 110 111 char* os::non_memory_address_word() { 112 // Must never look like an address returned by reserve_memory, 113 // even in its subfields (as defined by the CPU immediate fields, 114 // if the CPU splits constants across multiple instructions). 115 116 return (char*) -1; 117 } 118 119 address os::Linux::ucontext_get_pc(const ucontext_t * uc) { 120 return (address)uc->uc_mcontext.gregs[REG_PC]; 121 } 122 123 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) { 124 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc; 125 } 126 127 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) { 128 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP]; 129 } 130 131 intptr_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. 141 ExtendedPC 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 } 150 151 ExtendedPC 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 } 170 171 frame 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 } 177 178 frame 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 } 184 185 bool 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, 226 frame os::get_sender_for_C_frame(frame* fr) { 227 return frame(fr->sender_sp(), fr->link(), fr->sender_pc()); 228 } 229 230 intptr_t* _get_previous_fp() { 231 #ifdef SPARC_WORKS 232 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 } 250 251 252 frame 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 268 enum { 269 trap_page_fault = 0xE 270 }; 271 272 extern "C" JNIEXPORT int 273 JVM_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::ThreadCrashProtection::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 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 305 if ((sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) { 306 handle_assert_poison_fault(ucVoid, info->si_addr); 307 return 1; 308 } 309 #endif 310 311 JavaThread* thread = NULL; 312 VMThread* vmthread = NULL; 313 if (os::Linux::signal_handlers_are_installed) { 314 if (t != NULL ){ 315 if(t->is_Java_thread()) { 316 thread = (JavaThread*)t; 317 } 318 else if(t->is_VM_thread()){ 319 vmthread = (VMThread *)t; 320 } 321 } 322 } 323 /* 324 NOTE: does not seem to work on linux. 325 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) { 326 // can't decode this kind of signal 327 info = NULL; 328 } else { 329 assert(sig == info->si_signo, "bad siginfo"); 330 } 331 */ 332 // decide if this trap can be handled by a stub 333 address stub = NULL; 334 335 address pc = NULL; 336 337 //%note os_trap_1 338 if (info != NULL && uc != NULL && thread != NULL) { 339 pc = (address) os::Linux::ucontext_get_pc(uc); 340 341 if (StubRoutines::is_safefetch_fault(pc)) { 342 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc)); 343 return 1; 344 } 345 346 #ifndef AMD64 347 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs 348 // This can happen in any running code (currently more frequently in 349 // interpreter code but has been seen in compiled code) 350 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) { 351 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due " 352 "to unstable signal handling in this distribution."); 353 } 354 #endif // AMD64 355 356 // Handle ALL stack overflow variations here 357 if (sig == SIGSEGV) { 358 address addr = (address) info->si_addr; 359 360 // check if fault address is within thread stack 361 if (thread->on_local_stack(addr)) { 362 // stack overflow 363 if (thread->in_stack_yellow_reserved_zone(addr)) { 364 if (thread->thread_state() == _thread_in_Java) { 365 if (thread->in_stack_reserved_zone(addr)) { 366 frame fr; 367 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) { 368 assert(fr.is_java_frame(), "Must be a Java frame"); 369 frame activation = 370 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr); 371 if (activation.sp() != NULL) { 372 thread->disable_stack_reserved_zone(); 373 if (activation.is_interpreted_frame()) { 374 thread->set_reserved_stack_activation((address)( 375 activation.fp() + frame::interpreter_frame_initial_sp_offset)); 376 } else { 377 thread->set_reserved_stack_activation((address)activation.unextended_sp()); 378 } 379 return 1; 380 } 381 } 382 } 383 // Throw a stack overflow exception. Guard pages will be reenabled 384 // while unwinding the stack. 385 thread->disable_stack_yellow_reserved_zone(); 386 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW); 387 } else { 388 // Thread was in the vm or native code. Return and try to finish. 389 thread->disable_stack_yellow_reserved_zone(); 390 return 1; 391 } 392 } else if (thread->in_stack_red_zone(addr)) { 393 // Fatal red zone violation. Disable the guard pages and fall through 394 // to handle_unexpected_exception way down below. 395 thread->disable_stack_red_zone(); 396 tty->print_raw_cr("An irrecoverable stack overflow has occurred."); 397 398 // This is a likely cause, but hard to verify. Let's just print 399 // it as a hint. 400 tty->print_raw_cr("Please check if any of your loaded .so files has " 401 "enabled executable stack (see man page execstack(8))"); 402 } else { 403 // Accessing stack address below sp may cause SEGV if current 404 // thread has MAP_GROWSDOWN stack. This should only happen when 405 // current thread was created by user code with MAP_GROWSDOWN flag 406 // and then attached to VM. See notes in os_linux.cpp. 407 if (thread->osthread()->expanding_stack() == 0) { 408 thread->osthread()->set_expanding_stack(); 409 if (os::Linux::manually_expand_stack(thread, addr)) { 410 thread->osthread()->clear_expanding_stack(); 411 return 1; 412 } 413 thread->osthread()->clear_expanding_stack(); 414 } else { 415 fatal("recursive segv. expanding stack."); 416 } 417 } 418 } 419 } 420 421 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) { 422 // Verify that OS save/restore AVX registers. 423 stub = VM_Version::cpuinfo_cont_addr(); 424 } 425 426 if (thread->thread_state() == _thread_in_Java) { 427 // Java thread running in Java code => find exception handler if any 428 // a fault inside compiled code, the interpreter, or a stub 429 430 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) { 431 stub = SharedRuntime::get_poll_stub(pc); 432 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) { 433 // BugId 4454115: A read from a MappedByteBuffer can fault 434 // here if the underlying file has been truncated. 435 // Do not crash the VM in such a case. 436 CodeBlob* cb = CodeCache::find_blob_unsafe(pc); 437 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL; 438 if (nm != NULL && nm->has_unsafe_access()) { 439 address next_pc = Assembler::locate_next_instruction(pc); 440 stub = SharedRuntime::handle_unsafe_access(thread, next_pc); 441 } 442 } 443 else 444 445 #ifdef AMD64 446 if (sig == SIGFPE && 447 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) { 448 stub = 449 SharedRuntime:: 450 continuation_for_implicit_exception(thread, 451 pc, 452 SharedRuntime:: 453 IMPLICIT_DIVIDE_BY_ZERO); 454 #else 455 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) { 456 // HACK: si_code does not work on linux 2.2.12-20!!! 457 int op = pc[0]; 458 if (op == 0xDB) { 459 // FIST 460 // TODO: The encoding of D2I in i486.ad can cause an exception 461 // prior to the fist instruction if there was an invalid operation 462 // pending. We want to dismiss that exception. From the win_32 463 // side it also seems that if it really was the fist causing 464 // the exception that we do the d2i by hand with different 465 // rounding. Seems kind of weird. 466 // NOTE: that we take the exception at the NEXT floating point instruction. 467 assert(pc[0] == 0xDB, "not a FIST opcode"); 468 assert(pc[1] == 0x14, "not a FIST opcode"); 469 assert(pc[2] == 0x24, "not a FIST opcode"); 470 return true; 471 } else if (op == 0xF7) { 472 // IDIV 473 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO); 474 } else { 475 // TODO: handle more cases if we are using other x86 instructions 476 // that can generate SIGFPE signal on linux. 477 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op); 478 fatal("please update this code."); 479 } 480 #endif // AMD64 481 } else if (sig == SIGSEGV && 482 MacroAssembler::uses_implicit_null_check(info->si_addr)) { 483 // Determination of interpreter/vtable stub/compiled code null exception 484 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL); 485 } 486 } else if (thread->thread_state() == _thread_in_vm && 487 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */ 488 thread->doing_unsafe_access()) { 489 address next_pc = Assembler::locate_next_instruction(pc); 490 stub = SharedRuntime::handle_unsafe_access(thread, next_pc); 491 } 492 493 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in 494 // and the heap gets shrunk before the field access. 495 if ((sig == SIGSEGV) || (sig == SIGBUS)) { 496 address addr = JNI_FastGetField::find_slowcase_pc(pc); 497 if (addr != (address)-1) { 498 stub = addr; 499 } 500 } 501 502 // Check to see if we caught the safepoint code in the 503 // process of write protecting the memory serialization page. 504 // It write enables the page immediately after protecting it 505 // so we can just return to retry the write. 506 if ((sig == SIGSEGV) && 507 os::is_memory_serialize_page(thread, (address) info->si_addr)) { 508 // Block current thread until the memory serialize page permission restored. 509 os::block_on_serialize_page_trap(); 510 return true; 511 } 512 } 513 514 #ifndef AMD64 515 // Execution protection violation 516 // 517 // This should be kept as the last step in the triage. We don't 518 // have a dedicated trap number for a no-execute fault, so be 519 // conservative and allow other handlers the first shot. 520 // 521 // Note: We don't test that info->si_code == SEGV_ACCERR here. 522 // this si_code is so generic that it is almost meaningless; and 523 // the si_code for this condition may change in the future. 524 // Furthermore, a false-positive should be harmless. 525 if (UnguardOnExecutionViolation > 0 && 526 (sig == SIGSEGV || sig == SIGBUS) && 527 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) { 528 int page_size = os::vm_page_size(); 529 address addr = (address) info->si_addr; 530 address pc = os::Linux::ucontext_get_pc(uc); 531 // Make sure the pc and the faulting address are sane. 532 // 533 // If an instruction spans a page boundary, and the page containing 534 // the beginning of the instruction is executable but the following 535 // page is not, the pc and the faulting address might be slightly 536 // different - we still want to unguard the 2nd page in this case. 537 // 538 // 15 bytes seems to be a (very) safe value for max instruction size. 539 bool pc_is_near_addr = 540 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15); 541 bool instr_spans_page_boundary = 542 (align_down((intptr_t) pc ^ (intptr_t) addr, 543 (intptr_t) page_size) > 0); 544 545 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) { 546 static volatile address last_addr = 547 (address) os::non_memory_address_word(); 548 549 // In conservative mode, don't unguard unless the address is in the VM 550 if (addr != last_addr && 551 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) { 552 553 // Set memory to RWX and retry 554 address page_start = align_down(addr, page_size); 555 bool res = os::protect_memory((char*) page_start, page_size, 556 os::MEM_PROT_RWX); 557 558 log_debug(os)("Execution protection violation " 559 "at " INTPTR_FORMAT 560 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr), 561 p2i(page_start), (res ? "success" : "failed"), errno); 562 stub = pc; 563 564 // Set last_addr so if we fault again at the same address, we don't end 565 // up in an endless loop. 566 // 567 // There are two potential complications here. Two threads trapping at 568 // the same address at the same time could cause one of the threads to 569 // think it already unguarded, and abort the VM. Likely very rare. 570 // 571 // The other race involves two threads alternately trapping at 572 // different addresses and failing to unguard the page, resulting in 573 // an endless loop. This condition is probably even more unlikely than 574 // the first. 575 // 576 // Although both cases could be avoided by using locks or thread local 577 // last_addr, these solutions are unnecessary complication: this 578 // handler is a best-effort safety net, not a complete solution. It is 579 // disabled by default and should only be used as a workaround in case 580 // we missed any no-execute-unsafe VM code. 581 582 last_addr = addr; 583 } 584 } 585 } 586 #endif // !AMD64 587 588 if (stub != NULL) { 589 // save all thread context in case we need to restore it 590 if (thread != NULL) thread->set_saved_exception_pc(pc); 591 592 os::Linux::ucontext_set_pc(uc, stub); 593 return true; 594 } 595 596 // signal-chaining 597 if (os::Linux::chained_handler(sig, info, ucVoid)) { 598 return true; 599 } 600 601 if (!abort_if_unrecognized) { 602 // caller wants another chance, so give it to him 603 return false; 604 } 605 606 if (pc == NULL && uc != NULL) { 607 pc = os::Linux::ucontext_get_pc(uc); 608 } 609 610 // unmask current signal 611 sigset_t newset; 612 sigemptyset(&newset); 613 sigaddset(&newset, sig); 614 sigprocmask(SIG_UNBLOCK, &newset, NULL); 615 616 VMError::report_and_die(t, sig, pc, info, ucVoid); 617 618 ShouldNotReachHere(); 619 return true; // Mute compiler 620 } 621 622 void os::Linux::init_thread_fpu_state(void) { 623 #ifndef AMD64 624 // set fpu to 53 bit precision 625 set_fpu_control_word(0x27f); 626 #endif // !AMD64 627 } 628 629 int os::Linux::get_fpu_control_word(void) { 630 #ifdef AMD64 631 return 0; 632 #else 633 int fpu_control; 634 _FPU_GETCW(fpu_control); 635 return fpu_control & 0xffff; 636 #endif // AMD64 637 } 638 639 void os::Linux::set_fpu_control_word(int fpu_control) { 640 #ifndef AMD64 641 _FPU_SETCW(fpu_control); 642 #endif // !AMD64 643 } 644 645 // Check that the linux kernel version is 2.4 or higher since earlier 646 // versions do not support SSE without patches. 647 bool os::supports_sse() { 648 #ifdef AMD64 649 return true; 650 #else 651 struct utsname uts; 652 if( uname(&uts) != 0 ) return false; // uname fails? 653 char *minor_string; 654 int major = strtol(uts.release,&minor_string,10); 655 int minor = strtol(minor_string+1,NULL,10); 656 bool result = (major > 2 || (major==2 && minor >= 4)); 657 log_info(os)("OS version is %d.%d, which %s support SSE/SSE2", 658 major,minor, result ? "DOES" : "does NOT"); 659 return result; 660 #endif // AMD64 661 } 662 663 bool os::is_allocatable(size_t bytes) { 664 #ifdef AMD64 665 // unused on amd64? 666 return true; 667 #else 668 669 if (bytes < 2 * G) { 670 return true; 671 } 672 673 char* addr = reserve_memory(bytes, NULL); 674 675 if (addr != NULL) { 676 release_memory(addr, bytes); 677 } 678 679 return addr != NULL; 680 #endif // AMD64 681 } 682 683 //////////////////////////////////////////////////////////////////////////////// 684 // thread stack 685 686 // Minimum usable stack sizes required to get to user code. Space for 687 // HotSpot guard pages is added later. 688 size_t os::Posix::_compiler_thread_min_stack_allowed = 48 * K; 689 size_t os::Posix::_java_thread_min_stack_allowed = 40 * K; 690 #ifdef _LP64 691 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K; 692 #else 693 size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K; 694 #endif // _LP64 695 696 // return default stack size for thr_type 697 size_t os::Posix::default_stack_size(os::ThreadType thr_type) { 698 // default stack size (compiler thread needs larger stack) 699 #ifdef AMD64 700 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M); 701 #else 702 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K); 703 #endif // AMD64 704 return s; 705 } 706 707 ///////////////////////////////////////////////////////////////////////////// 708 // helper functions for fatal error handler 709 710 void os::print_context(outputStream *st, const void *context) { 711 if (context == NULL) return; 712 713 const ucontext_t *uc = (const ucontext_t*)context; 714 st->print_cr("Registers:"); 715 #ifdef AMD64 716 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]); 717 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]); 718 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]); 719 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]); 720 st->cr(); 721 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]); 722 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]); 723 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]); 724 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]); 725 st->cr(); 726 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]); 727 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]); 728 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]); 729 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]); 730 st->cr(); 731 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]); 732 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]); 733 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]); 734 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]); 735 st->cr(); 736 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]); 737 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]); 738 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]); 739 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]); 740 st->cr(); 741 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]); 742 #else 743 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]); 744 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]); 745 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]); 746 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]); 747 st->cr(); 748 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]); 749 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]); 750 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]); 751 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]); 752 st->cr(); 753 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]); 754 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]); 755 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2); 756 #endif // AMD64 757 st->cr(); 758 st->cr(); 759 760 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc); 761 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp)); 762 print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t)); 763 st->cr(); 764 765 // Note: it may be unsafe to inspect memory near pc. For example, pc may 766 // point to garbage if entry point in an nmethod is corrupted. Leave 767 // this at the end, and hope for the best. 768 address pc = os::Linux::ucontext_get_pc(uc); 769 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc)); 770 print_hex_dump(st, pc - 32, pc + 32, sizeof(char)); 771 } 772 773 void os::print_register_info(outputStream *st, const void *context) { 774 if (context == NULL) return; 775 776 const ucontext_t *uc = (const ucontext_t*)context; 777 778 st->print_cr("Register to memory mapping:"); 779 st->cr(); 780 781 // this is horrendously verbose but the layout of the registers in the 782 // context does not match how we defined our abstract Register set, so 783 // we can't just iterate through the gregs area 784 785 // this is only for the "general purpose" registers 786 787 #ifdef AMD64 788 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]); 789 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]); 790 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]); 791 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]); 792 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]); 793 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]); 794 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]); 795 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]); 796 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]); 797 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]); 798 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]); 799 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]); 800 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]); 801 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]); 802 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]); 803 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]); 804 #else 805 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]); 806 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]); 807 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]); 808 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]); 809 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]); 810 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]); 811 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]); 812 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]); 813 #endif // AMD64 814 815 st->cr(); 816 } 817 818 void os::setup_fpu() { 819 #ifndef AMD64 820 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std(); 821 __asm__ volatile ( "fldcw (%0)" : 822 : "r" (fpu_cntrl) : "memory"); 823 #endif // !AMD64 824 } 825 826 #ifndef PRODUCT 827 void os::verify_stack_alignment() { 828 #ifdef AMD64 829 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment"); 830 #endif 831 } 832 #endif 833 834 835 /* 836 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit 837 * updates (JDK-8023956). 838 */ 839 void os::workaround_expand_exec_shield_cs_limit() { 840 #if defined(IA32) 841 size_t page_size = os::vm_page_size(); 842 843 /* 844 * JDK-8197429 845 * 846 * Expand the stack mapping to the end of the initial stack before 847 * attempting to install the codebuf. This is needed because newer 848 * Linux kernels impose a distance of a megabyte between stack 849 * memory and other memory regions. If we try to install the 850 * codebuf before expanding the stack the installation will appear 851 * to succeed but we'll get a segfault later if we expand the stack 852 * in Java code. 853 * 854 */ 855 if (os::is_primordial_thread()) { 856 address limit = Linux::initial_thread_stack_bottom(); 857 if (! DisablePrimordialThreadGuardPages) { 858 limit += JavaThread::stack_red_zone_size() + 859 JavaThread::stack_yellow_zone_size(); 860 } 861 os::Linux::expand_stack_to(limit); 862 } 863 864 /* 865 * Take the highest VA the OS will give us and exec 866 * 867 * Although using -(pagesz) as mmap hint works on newer kernel as you would 868 * think, older variants affected by this work-around don't (search forward only). 869 * 870 * On the affected distributions, we understand the memory layout to be: 871 * 872 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT. 873 * 874 * A few pages south main stack will do it. 875 * 876 * If we are embedded in an app other than launcher (initial != main stack), 877 * we don't have much control or understanding of the address space, just let it slide. 878 */ 879 char* hint = (char*)(Linux::initial_thread_stack_bottom() - 880 (JavaThread::stack_guard_zone_size() + page_size)); 881 char* codebuf = os::attempt_reserve_memory_at(page_size, hint); 882 883 if (codebuf == NULL) { 884 // JDK-8197429: There may be a stack gap of one megabyte between 885 // the limit of the stack and the nearest memory region: this is a 886 // Linux kernel workaround for CVE-2017-1000364. If we failed to 887 // map our codebuf, try again at an address one megabyte lower. 888 hint -= 1 * M; 889 codebuf = os::attempt_reserve_memory_at(page_size, hint); 890 } 891 892 if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) { 893 return; // No matter, we tried, best effort. 894 } 895 896 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal); 897 898 log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf); 899 900 // Some code to exec: the 'ret' instruction 901 codebuf[0] = 0xC3; 902 903 // Call the code in the codebuf 904 __asm__ volatile("call *%0" : : "r"(codebuf)); 905 906 // keep the page mapped so CS limit isn't reduced. 907 #endif 908 } 909 910 int os::extra_bang_size_in_bytes() { 911 // JDK-8050147 requires the full cache line bang for x86. 912 return VM_Version::L1_line_size(); 913 }