--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/os_cpu/linux_x86/vm/os_linux_x86.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,782 @@
+/*
+ * Copyright 1999-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// do not include  precompiled  header file
+# include "incls/_os_linux_x86.cpp.incl"
+
+// put OS-includes here
+# include <sys/types.h>
+# include <sys/mman.h>
+# include <pthread.h>
+# include <signal.h>
+# include <errno.h>
+# include <dlfcn.h>
+# include <stdlib.h>
+# include <stdio.h>
+# include <unistd.h>
+# include <sys/resource.h>
+# include <pthread.h>
+# include <sys/stat.h>
+# include <sys/time.h>
+# include <sys/utsname.h>
+# include <sys/socket.h>
+# include <sys/wait.h>
+# include <pwd.h>
+# include <poll.h>
+# include <ucontext.h>
+# include <fpu_control.h>
+
+#ifdef AMD64
+#define REG_SP REG_RSP
+#define REG_PC REG_RIP
+#define REG_FP REG_RBP
+#define SPELL_REG_SP "rsp"
+#define SPELL_REG_FP "rbp"
+#else
+#define REG_SP REG_UESP
+#define REG_PC REG_EIP
+#define REG_FP REG_EBP
+#define SPELL_REG_SP "esp"
+#define SPELL_REG_FP "ebp"
+#endif // AMD64
+
+address os::current_stack_pointer() {
+  register void *esp __asm__ (SPELL_REG_SP);
+  return (address) esp;
+}
+
+char* os::non_memory_address_word() {
+  // Must never look like an address returned by reserve_memory,
+  // even in its subfields (as defined by the CPU immediate fields,
+  // if the CPU splits constants across multiple instructions).
+
+  return (char*) -1;
+}
+
+void os::initialize_thread() {
+// Nothing to do.
+}
+
+address os::Linux::ucontext_get_pc(ucontext_t * uc) {
+  return (address)uc->uc_mcontext.gregs[REG_PC];
+}
+
+intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) {
+  return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
+}
+
+intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) {
+  return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
+}
+
+// For Forte Analyzer AsyncGetCallTrace profiling support - thread
+// is currently interrupted by SIGPROF.
+// os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
+// frames. Currently we don't do that on Linux, so it's the same as
+// os::fetch_frame_from_context().
+ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
+  ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
+
+  assert(thread != NULL, "just checking");
+  assert(ret_sp != NULL, "just checking");
+  assert(ret_fp != NULL, "just checking");
+
+  return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
+}
+
+ExtendedPC os::fetch_frame_from_context(void* ucVoid,
+                    intptr_t** ret_sp, intptr_t** ret_fp) {
+
+  ExtendedPC  epc;
+  ucontext_t* uc = (ucontext_t*)ucVoid;
+
+  if (uc != NULL) {
+    epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
+    if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
+    if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
+  } else {
+    // construct empty ExtendedPC for return value checking
+    epc = ExtendedPC(NULL);
+    if (ret_sp) *ret_sp = (intptr_t *)NULL;
+    if (ret_fp) *ret_fp = (intptr_t *)NULL;
+  }
+
+  return epc;
+}
+
+frame os::fetch_frame_from_context(void* ucVoid) {
+  intptr_t* sp;
+  intptr_t* fp;
+  ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
+  return frame(sp, fp, epc.pc());
+}
+
+// By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
+// turned off by -fomit-frame-pointer,
+frame os::get_sender_for_C_frame(frame* fr) {
+  return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
+}
+
+intptr_t* _get_previous_fp() {
+  register intptr_t **ebp __asm__ (SPELL_REG_FP);
+  return (intptr_t*) *ebp;   // we want what it points to.
+}
+
+
+frame os::current_frame() {
+  intptr_t* fp = _get_previous_fp();
+  frame myframe((intptr_t*)os::current_stack_pointer(),
+                (intptr_t*)fp,
+                CAST_FROM_FN_PTR(address, os::current_frame));
+  if (os::is_first_C_frame(&myframe)) {
+    // stack is not walkable
+    return frame(NULL, NULL, NULL);
+  } else {
+    return os::get_sender_for_C_frame(&myframe);
+  }
+}
+
+
+// Utility functions
+
+julong os::allocatable_physical_memory(julong size) {
+#ifdef AMD64
+  return size;
+#else
+  julong result = MIN2(size, (julong)3800*M);
+   if (!is_allocatable(result)) {
+     // See comments under solaris for alignment considerations
+     julong reasonable_size = (julong)2*G - 2 * os::vm_page_size();
+     result =  MIN2(size, reasonable_size);
+   }
+   return result;
+#endif // AMD64
+}
+
+// From IA32 System Programming Guide
+enum {
+  trap_page_fault = 0xE
+};
+
+extern "C" void Fetch32PFI () ;
+extern "C" void Fetch32Resume () ;
+#ifdef AMD64
+extern "C" void FetchNPFI () ;
+extern "C" void FetchNResume () ;
+#endif // AMD64
+
+extern "C" int
+JVM_handle_linux_signal(int sig,
+                        siginfo_t* info,
+                        void* ucVoid,
+                        int abort_if_unrecognized) {
+  ucontext_t* uc = (ucontext_t*) ucVoid;
+
+  Thread* t = ThreadLocalStorage::get_thread_slow();
+
+  SignalHandlerMark shm(t);
+
+  // Note: it's not uncommon that JNI code uses signal/sigset to install
+  // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
+  // or have a SIGILL handler when detecting CPU type). When that happens,
+  // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
+  // avoid unnecessary crash when libjsig is not preloaded, try handle signals
+  // that do not require siginfo/ucontext first.
+
+  if (sig == SIGPIPE || sig == SIGXFSZ) {
+    // allow chained handler to go first
+    if (os::Linux::chained_handler(sig, info, ucVoid)) {
+      return true;
+    } else {
+      if (PrintMiscellaneous && (WizardMode || Verbose)) {
+        char buf[64];
+        warning("Ignoring %s - see bugs 4229104 or 646499219",
+                os::exception_name(sig, buf, sizeof(buf)));
+      }
+      return true;
+    }
+  }
+
+  JavaThread* thread = NULL;
+  VMThread* vmthread = NULL;
+  if (os::Linux::signal_handlers_are_installed) {
+    if (t != NULL ){
+      if(t->is_Java_thread()) {
+        thread = (JavaThread*)t;
+      }
+      else if(t->is_VM_thread()){
+        vmthread = (VMThread *)t;
+      }
+    }
+  }
+/*
+  NOTE: does not seem to work on linux.
+  if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
+    // can't decode this kind of signal
+    info = NULL;
+  } else {
+    assert(sig == info->si_signo, "bad siginfo");
+  }
+*/
+  // decide if this trap can be handled by a stub
+  address stub = NULL;
+
+  address pc          = NULL;
+
+  //%note os_trap_1
+  if (info != NULL && uc != NULL && thread != NULL) {
+    pc = (address) os::Linux::ucontext_get_pc(uc);
+
+    if (pc == (address) Fetch32PFI) {
+       uc->uc_mcontext.gregs[REG_PC] = intptr_t(Fetch32Resume) ;
+       return 1 ;
+    }
+#ifdef AMD64
+    if (pc == (address) FetchNPFI) {
+       uc->uc_mcontext.gregs[REG_PC] = intptr_t (FetchNResume) ;
+       return 1 ;
+    }
+#endif // AMD64
+
+    // Handle ALL stack overflow variations here
+    if (sig == SIGSEGV) {
+      address addr = (address) info->si_addr;
+
+      // check if fault address is within thread stack
+      if (addr < thread->stack_base() &&
+          addr >= thread->stack_base() - thread->stack_size()) {
+        // stack overflow
+        if (thread->in_stack_yellow_zone(addr)) {
+          thread->disable_stack_yellow_zone();
+          if (thread->thread_state() == _thread_in_Java) {
+            // Throw a stack overflow exception.  Guard pages will be reenabled
+            // while unwinding the stack.
+            stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
+          } else {
+            // Thread was in the vm or native code.  Return and try to finish.
+            return 1;
+          }
+        } else if (thread->in_stack_red_zone(addr)) {
+          // Fatal red zone violation.  Disable the guard pages and fall through
+          // to handle_unexpected_exception way down below.
+          thread->disable_stack_red_zone();
+          tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
+        } else {
+          // Accessing stack address below sp may cause SEGV if current
+          // thread has MAP_GROWSDOWN stack. This should only happen when
+          // current thread was created by user code with MAP_GROWSDOWN flag
+          // and then attached to VM. See notes in os_linux.cpp.
+          if (thread->osthread()->expanding_stack() == 0) {
+             thread->osthread()->set_expanding_stack();
+             if (os::Linux::manually_expand_stack(thread, addr)) {
+               thread->osthread()->clear_expanding_stack();
+               return 1;
+             }
+             thread->osthread()->clear_expanding_stack();
+          } else {
+             fatal("recursive segv. expanding stack.");
+          }
+        }
+      }
+    }
+
+    if (thread->thread_state() == _thread_in_Java) {
+      // Java thread running in Java code => find exception handler if any
+      // a fault inside compiled code, the interpreter, or a stub
+
+      if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
+        stub = SharedRuntime::get_poll_stub(pc);
+      } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
+        // BugId 4454115: A read from a MappedByteBuffer can fault
+        // here if the underlying file has been truncated.
+        // Do not crash the VM in such a case.
+        CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
+        nmethod* nm = cb->is_nmethod() ? (nmethod*)cb : NULL;
+        if (nm != NULL && nm->has_unsafe_access()) {
+          stub = StubRoutines::handler_for_unsafe_access();
+        }
+      }
+      else
+
+#ifdef AMD64
+      if (sig == SIGFPE  &&
+          (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
+        stub =
+          SharedRuntime::
+          continuation_for_implicit_exception(thread,
+                                              pc,
+                                              SharedRuntime::
+                                              IMPLICIT_DIVIDE_BY_ZERO);
+#else
+      if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
+        // HACK: si_code does not work on linux 2.2.12-20!!!
+        int op = pc[0];
+        if (op == 0xDB) {
+          // FIST
+          // TODO: The encoding of D2I in i486.ad can cause an exception
+          // prior to the fist instruction if there was an invalid operation
+          // pending. We want to dismiss that exception. From the win_32
+          // side it also seems that if it really was the fist causing
+          // the exception that we do the d2i by hand with different
+          // rounding. Seems kind of weird.
+          // NOTE: that we take the exception at the NEXT floating point instruction.
+          assert(pc[0] == 0xDB, "not a FIST opcode");
+          assert(pc[1] == 0x14, "not a FIST opcode");
+          assert(pc[2] == 0x24, "not a FIST opcode");
+          return true;
+        } else if (op == 0xF7) {
+          // IDIV
+          stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
+        } else {
+          // TODO: handle more cases if we are using other x86 instructions
+          //   that can generate SIGFPE signal on linux.
+          tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
+          fatal("please update this code.");
+        }
+#endif // AMD64
+      } else if (sig == SIGSEGV &&
+               !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
+          // Determination of interpreter/vtable stub/compiled code null exception
+          stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
+      }
+    } else if (thread->thread_state() == _thread_in_vm &&
+               sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
+               thread->doing_unsafe_access()) {
+        stub = StubRoutines::handler_for_unsafe_access();
+    }
+
+    // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
+    // and the heap gets shrunk before the field access.
+    if ((sig == SIGSEGV) || (sig == SIGBUS)) {
+      address addr = JNI_FastGetField::find_slowcase_pc(pc);
+      if (addr != (address)-1) {
+        stub = addr;
+      }
+    }
+
+    // Check to see if we caught the safepoint code in the
+    // process of write protecting the memory serialization page.
+    // It write enables the page immediately after protecting it
+    // so we can just return to retry the write.
+    if ((sig == SIGSEGV) &&
+        os::is_memory_serialize_page(thread, (address) info->si_addr)) {
+      // Block current thread until the memory serialize page permission restored.
+      os::block_on_serialize_page_trap();
+      return true;
+    }
+  }
+
+#ifndef AMD64
+  // Execution protection violation
+  //
+  // This should be kept as the last step in the triage.  We don't
+  // have a dedicated trap number for a no-execute fault, so be
+  // conservative and allow other handlers the first shot.
+  //
+  // Note: We don't test that info->si_code == SEGV_ACCERR here.
+  // this si_code is so generic that it is almost meaningless; and
+  // the si_code for this condition may change in the future.
+  // Furthermore, a false-positive should be harmless.
+  if (UnguardOnExecutionViolation > 0 &&
+      (sig == SIGSEGV || sig == SIGBUS) &&
+      uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
+    int page_size = os::vm_page_size();
+    address addr = (address) info->si_addr;
+    address pc = os::Linux::ucontext_get_pc(uc);
+    // Make sure the pc and the faulting address are sane.
+    //
+    // If an instruction spans a page boundary, and the page containing
+    // the beginning of the instruction is executable but the following
+    // page is not, the pc and the faulting address might be slightly
+    // different - we still want to unguard the 2nd page in this case.
+    //
+    // 15 bytes seems to be a (very) safe value for max instruction size.
+    bool pc_is_near_addr =
+      (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
+    bool instr_spans_page_boundary =
+      (align_size_down((intptr_t) pc ^ (intptr_t) addr,
+                       (intptr_t) page_size) > 0);
+
+    if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
+      static volatile address last_addr =
+        (address) os::non_memory_address_word();
+
+      // In conservative mode, don't unguard unless the address is in the VM
+      if (addr != last_addr &&
+          (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
+
+        // Unguard and retry
+        address page_start =
+          (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
+        bool res = os::unguard_memory((char*) page_start, page_size);
+
+        if (PrintMiscellaneous && Verbose) {
+          char buf[256];
+          jio_snprintf(buf, sizeof(buf), "Execution protection violation "
+                       "at " INTPTR_FORMAT
+                       ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
+                       page_start, (res ? "success" : "failed"), errno);
+          tty->print_raw_cr(buf);
+        }
+        stub = pc;
+
+        // Set last_addr so if we fault again at the same address, we don't end
+        // up in an endless loop.
+        //
+        // There are two potential complications here.  Two threads trapping at
+        // the same address at the same time could cause one of the threads to
+        // think it already unguarded, and abort the VM.  Likely very rare.
+        //
+        // The other race involves two threads alternately trapping at
+        // different addresses and failing to unguard the page, resulting in
+        // an endless loop.  This condition is probably even more unlikely than
+        // the first.
+        //
+        // Although both cases could be avoided by using locks or thread local
+        // last_addr, these solutions are unnecessary complication: this
+        // handler is a best-effort safety net, not a complete solution.  It is
+        // disabled by default and should only be used as a workaround in case
+        // we missed any no-execute-unsafe VM code.
+
+        last_addr = addr;
+      }
+    }
+  }
+#endif // !AMD64
+
+  if (stub != NULL) {
+    // save all thread context in case we need to restore it
+    if (thread != NULL) thread->set_saved_exception_pc(pc);
+
+    uc->uc_mcontext.gregs[REG_PC] = (greg_t)stub;
+    return true;
+  }
+
+  // signal-chaining
+  if (os::Linux::chained_handler(sig, info, ucVoid)) {
+     return true;
+  }
+
+  if (!abort_if_unrecognized) {
+    // caller wants another chance, so give it to him
+    return false;
+  }
+
+  if (pc == NULL && uc != NULL) {
+    pc = os::Linux::ucontext_get_pc(uc);
+  }
+
+  // unmask current signal
+  sigset_t newset;
+  sigemptyset(&newset);
+  sigaddset(&newset, sig);
+  sigprocmask(SIG_UNBLOCK, &newset, NULL);
+
+  VMError err(t, sig, pc, info, ucVoid);
+  err.report_and_die();
+
+  ShouldNotReachHere();
+}
+
+void os::Linux::init_thread_fpu_state(void) {
+#ifndef AMD64
+  // set fpu to 53 bit precision
+  set_fpu_control_word(0x27f);
+#endif // !AMD64
+}
+
+int os::Linux::get_fpu_control_word(void) {
+#ifdef AMD64
+  return 0;
+#else
+  int fpu_control;
+  _FPU_GETCW(fpu_control);
+  return fpu_control & 0xffff;
+#endif // AMD64
+}
+
+void os::Linux::set_fpu_control_word(int fpu_control) {
+#ifndef AMD64
+  _FPU_SETCW(fpu_control);
+#endif // !AMD64
+}
+
+// Check that the linux kernel version is 2.4 or higher since earlier
+// versions do not support SSE without patches.
+bool os::supports_sse() {
+#ifdef AMD64
+  return true;
+#else
+  struct utsname uts;
+  if( uname(&uts) != 0 ) return false; // uname fails?
+  char *minor_string;
+  int major = strtol(uts.release,&minor_string,10);
+  int minor = strtol(minor_string+1,NULL,10);
+  bool result = (major > 2 || (major==2 && minor >= 4));
+#ifndef PRODUCT
+  if (PrintMiscellaneous && Verbose) {
+    tty->print("OS version is %d.%d, which %s support SSE/SSE2\n",
+               major,minor, result ? "DOES" : "does NOT");
+  }
+#endif
+  return result;
+#endif // AMD64
+}
+
+bool os::is_allocatable(size_t bytes) {
+#ifdef AMD64
+  // unused on amd64?
+  return true;
+#else
+
+  if (bytes < 2 * G) {
+    return true;
+  }
+
+  char* addr = reserve_memory(bytes, NULL);
+
+  if (addr != NULL) {
+    release_memory(addr, bytes);
+  }
+
+  return addr != NULL;
+#endif // AMD64
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// thread stack
+
+#ifdef AMD64
+size_t os::Linux::min_stack_allowed  = 64 * K;
+
+// amd64: pthread on amd64 is always in floating stack mode
+bool os::Linux::supports_variable_stack_size() {  return true; }
+#else
+size_t os::Linux::min_stack_allowed  =  (48 DEBUG_ONLY(+4))*K;
+
+#define GET_GS() ({int gs; __asm__ volatile("movw %%gs, %w0":"=q"(gs)); gs&0xffff;})
+
+// Test if pthread library can support variable thread stack size. LinuxThreads
+// in fixed stack mode allocates 2M fixed slot for each thread. LinuxThreads
+// in floating stack mode and NPTL support variable stack size.
+bool os::Linux::supports_variable_stack_size() {
+  if (os::Linux::is_NPTL()) {
+     // NPTL, yes
+     return true;
+
+  } else {
+    // Note: We can't control default stack size when creating a thread.
+    // If we use non-default stack size (pthread_attr_setstacksize), both
+    // floating stack and non-floating stack LinuxThreads will return the
+    // same value. This makes it impossible to implement this function by
+    // detecting thread stack size directly.
+    //
+    // An alternative approach is to check %gs. Fixed-stack LinuxThreads
+    // do not use %gs, so its value is 0. Floating-stack LinuxThreads use
+    // %gs (either as LDT selector or GDT selector, depending on kernel)
+    // to access thread specific data.
+    //
+    // Note that %gs is a reserved glibc register since early 2001, so
+    // applications are not allowed to change its value (Ulrich Drepper from
+    // Redhat confirmed that all known offenders have been modified to use
+    // either %fs or TSD). In the worst case scenario, when VM is embedded in
+    // a native application that plays with %gs, we might see non-zero %gs
+    // even LinuxThreads is running in fixed stack mode. As the result, we'll
+    // return true and skip _thread_safety_check(), so we may not be able to
+    // detect stack-heap collisions. But otherwise it's harmless.
+    //
+    return (GET_GS() != 0);
+  }
+}
+#endif // AMD64
+
+// return default stack size for thr_type
+size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
+  // default stack size (compiler thread needs larger stack)
+#ifdef AMD64
+  size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
+#else
+  size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
+#endif // AMD64
+  return s;
+}
+
+size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
+  // Creating guard page is very expensive. Java thread has HotSpot
+  // guard page, only enable glibc guard page for non-Java threads.
+  return (thr_type == java_thread ? 0 : page_size());
+}
+
+// Java thread:
+//
+//   Low memory addresses
+//    +------------------------+
+//    |                        |\  JavaThread created by VM does not have glibc
+//    |    glibc guard page    | - guard, attached Java thread usually has
+//    |                        |/  1 page glibc guard.
+// P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
+//    |                        |\
+//    |  HotSpot Guard Pages   | - red and yellow pages
+//    |                        |/
+//    +------------------------+ JavaThread::stack_yellow_zone_base()
+//    |                        |\
+//    |      Normal Stack      | -
+//    |                        |/
+// P2 +------------------------+ Thread::stack_base()
+//
+// Non-Java thread:
+//
+//   Low memory addresses
+//    +------------------------+
+//    |                        |\
+//    |  glibc guard page      | - usually 1 page
+//    |                        |/
+// P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
+//    |                        |\
+//    |      Normal Stack      | -
+//    |                        |/
+// P2 +------------------------+ Thread::stack_base()
+//
+// ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
+//    pthread_attr_getstack()
+
+static void current_stack_region(address * bottom, size_t * size) {
+  if (os::Linux::is_initial_thread()) {
+     // initial thread needs special handling because pthread_getattr_np()
+     // may return bogus value.
+     *bottom = os::Linux::initial_thread_stack_bottom();
+     *size   = os::Linux::initial_thread_stack_size();
+  } else {
+     pthread_attr_t attr;
+
+     int rslt = pthread_getattr_np(pthread_self(), &attr);
+
+     // JVM needs to know exact stack location, abort if it fails
+     if (rslt != 0) {
+       if (rslt == ENOMEM) {
+         vm_exit_out_of_memory(0, "pthread_getattr_np");
+       } else {
+         fatal1("pthread_getattr_np failed with errno = %d", rslt);
+       }
+     }
+
+     if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
+         fatal("Can not locate current stack attributes!");
+     }
+
+     pthread_attr_destroy(&attr);
+
+  }
+  assert(os::current_stack_pointer() >= *bottom &&
+         os::current_stack_pointer() < *bottom + *size, "just checking");
+}
+
+address os::current_stack_base() {
+  address bottom;
+  size_t size;
+  current_stack_region(&bottom, &size);
+  return (bottom + size);
+}
+
+size_t os::current_stack_size() {
+  // stack size includes normal stack and HotSpot guard pages
+  address bottom;
+  size_t size;
+  current_stack_region(&bottom, &size);
+  return size;
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// helper functions for fatal error handler
+
+void os::print_context(outputStream *st, void *context) {
+  if (context == NULL) return;
+
+  ucontext_t *uc = (ucontext_t*)context;
+  st->print_cr("Registers:");
+#ifdef AMD64
+  st->print(  "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]);
+  st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]);
+  st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]);
+  st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]);
+  st->cr();
+  st->print(  "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]);
+  st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]);
+  st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]);
+  st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]);
+  st->cr();
+  st->print(  "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]);
+  st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]);
+  st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]);
+  st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]);
+  st->cr();
+  st->print(  "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]);
+  st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]);
+  st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]);
+  st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]);
+  st->cr();
+  st->print(  "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]);
+  st->print(", EFL=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
+  st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]);
+  st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]);
+  st->cr();
+  st->print("  TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]);
+#else
+  st->print(  "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
+  st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
+  st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
+  st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
+  st->cr();
+  st->print(  "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
+  st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
+  st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
+  st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
+  st->cr();
+  st->print(  "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
+  st->print(", CR2=" INTPTR_FORMAT, uc->uc_mcontext.cr2);
+  st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
+#endif // AMD64
+  st->cr();
+  st->cr();
+
+  intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
+  st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
+  print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
+  st->cr();
+
+  // Note: it may be unsafe to inspect memory near pc. For example, pc may
+  // point to garbage if entry point in an nmethod is corrupted. Leave
+  // this at the end, and hope for the best.
+  address pc = os::Linux::ucontext_get_pc(uc);
+  st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
+  print_hex_dump(st, pc - 16, pc + 16, sizeof(char));
+}
+
+void os::setup_fpu() {
+#ifndef AMD64
+  address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
+  __asm__ volatile (  "fldcw (%0)" :
+                      : "r" (fpu_cntrl) : "memory");
+#endif // !AMD64
+}