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