hotspot/src/os_cpu/linux_zero/vm/os_linux_zero.cpp - edge/openjdk - Git at Google

 /*
  * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2007, 2008, 2009, 2010 Red Hat, Inc.
  * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */

 // no precompiled headers
 #include "assembler_zero.inline.hpp"
 #include "classfile/classLoader.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "code/icBuffer.hpp"
 #include "code/vtableStubs.hpp"
 #include "interpreter/interpreter.hpp"
 #include "jvm_linux.h"
 #include "memory/allocation.inline.hpp"
 #include "mutex_linux.inline.hpp"
 #include "nativeInst_zero.hpp"
 #include "os_share_linux.hpp"
 #include "prims/jniFastGetField.hpp"
 #include "prims/jvm.h"
 #include "prims/jvm_misc.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/extendedPC.hpp"
 #include "runtime/frame.inline.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/java.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/osThread.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "runtime/stubRoutines.hpp"
 #include "runtime/thread.inline.hpp"
 #include "runtime/timer.hpp"
 #include "utilities/events.hpp"
 #include "utilities/vmError.hpp"

 address os::current_stack_pointer() {
   // return the address of the current function
   return (address)__builtin_frame_address(0);
 }

 frame os::get_sender_for_C_frame(frame* fr) {
   ShouldNotCallThis();
 }

 frame os::current_frame() {
   // The only thing that calls this is the stack printing code in
   // VMError::report:
   //   - Step 110 (printing stack bounds) uses the sp in the frame
   //     to determine the amount of free space on the stack.  We
   //     set the sp to a close approximation of the real value in
   //     order to allow this step to complete.
   //   - Step 120 (printing native stack) tries to walk the stack.
   //     The frame we create has a NULL pc, which is ignored as an
   //     invalid frame.
   frame dummy = frame();
   dummy.set_sp((intptr_t *) current_stack_pointer());
   return dummy;
 }

 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).
 #ifdef SPARC
   // On SPARC, 0 != %hi(any real address), because there is no
   // allocation in the first 1Kb of the virtual address space.
   return (char *) 0;
 #else
   // This is the value for x86; works pretty well for PPC too.
   return (char *) -1;
 #endif // SPARC
 }

 void os::initialize_thread(Thread * thr){
   // Nothing to do.
 }

 address os::Linux::ucontext_get_pc(ucontext_t* uc) {
   ShouldNotCallThis();
 }

 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
                                         intptr_t** ret_sp,
                                         intptr_t** ret_fp) {
   ShouldNotCallThis();
 }

 frame os::fetch_frame_from_context(void* ucVoid) {
   ShouldNotCallThis();
 }

 extern "C" JNIEXPORT 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;
       }
     }
   }

   if (info != NULL && thread != NULL) {
     // 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();
           ShouldNotCallThis();
         }
         else if (thread->in_stack_red_zone(addr)) {
           thread->disable_stack_red_zone();
           ShouldNotCallThis();
         }
         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 true;
             }
             thread->osthread()->clear_expanding_stack();
           }
           else {
             fatal("recursive segv. expanding stack.");
           }
         }
       }
     }

     /*if (thread->thread_state() == _thread_in_Java) {
       ShouldNotCallThis();
     }
     else*/ if (thread->thread_state() == _thread_in_vm &&
                sig == SIGBUS && thread->doing_unsafe_access()) {
       ShouldNotCallThis();
     }

     // 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 permission is restored.
       os::block_on_serialize_page_trap();
       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;
   }

 #ifndef PRODUCT
   if (sig == SIGSEGV) {
     fatal("\n#"
           "\n#    /--------------------\\"
           "\n#    | segmentation fault |"
           "\n#    \\---\\ /--------------/"
           "\n#        /"
           "\n#    [-]        |\\_/|    "
           "\n#    (+)=C      |o o|__  "
           "\n#    | |        =-*-=__\\ "
           "\n#    OOO        c_c_(___)");
   }
 #endif // !PRODUCT

   const char *fmt = "caught unhandled signal %d";
   char buf[64];

   sprintf(buf, fmt, sig);
   fatal(buf);
 }

 void os::Linux::init_thread_fpu_state(void) {
   // Nothing to do
 }

 int os::Linux::get_fpu_control_word() {
   ShouldNotCallThis();
 }

 void os::Linux::set_fpu_control_word(int fpu) {
   ShouldNotCallThis();
 }

 bool os::is_allocatable(size_t bytes) {
 #ifdef _LP64
   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 // _LP64
 }

 ///////////////////////////////////////////////////////////////////////////////
 // thread stack

 size_t os::Linux::min_stack_allowed = 64 * K;

 bool os::Linux::supports_variable_stack_size() {
   return true;
 }

 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
 #ifdef _LP64
   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 // _LP64
   return s;
 }

 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
   // Only enable glibc guard pages for non-Java threads
   // (Java threads have HotSpot guard pages)
   return (thr_type == java_thread ? 0 : page_size());
 }

 static void current_stack_region(address *bottom, size_t *size) {
   pthread_attr_t attr;
   int res = pthread_getattr_np(pthread_self(), &attr);
   if (res != 0) {
     if (res == ENOMEM) {
       vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
     }
     else {
       fatal(err_msg("pthread_getattr_np failed with errno = %d", res));
     }
   }

   address stack_bottom;
   size_t stack_bytes;
   res = pthread_attr_getstack(&attr, (void **) &stack_bottom, &stack_bytes);
   if (res != 0) {
     fatal(err_msg("pthread_attr_getstack failed with errno = %d", res));
   }
   address stack_top = stack_bottom + stack_bytes;

   // The block of memory returned by pthread_attr_getstack() includes
   // guard pages where present.  We need to trim these off.
   size_t page_bytes = os::Linux::page_size();
   assert(((intptr_t) stack_bottom & (page_bytes - 1)) == 0, "unaligned stack");

   size_t guard_bytes;
   res = pthread_attr_getguardsize(&attr, &guard_bytes);
   if (res != 0) {
     fatal(err_msg("pthread_attr_getguardsize failed with errno = %d", res));
   }
   int guard_pages = align_size_up(guard_bytes, page_bytes) / page_bytes;
   assert(guard_bytes == guard_pages * page_bytes, "unaligned guard");

 #ifdef IA64
   // IA64 has two stacks sharing the same area of memory, a normal
   // stack growing downwards and a register stack growing upwards.
   // Guard pages, if present, are in the centre.  This code splits
   // the stack in two even without guard pages, though in theory
   // there's nothing to stop us allocating more to the normal stack
   // or more to the register stack if one or the other were found
   // to grow faster.
   int total_pages = align_size_down(stack_bytes, page_bytes) / page_bytes;
   stack_bottom += (total_pages - guard_pages) / 2 * page_bytes;
 #endif // IA64

   stack_bottom += guard_bytes;

   pthread_attr_destroy(&attr);

   // The initial thread has a growable stack, and the size reported
   // by pthread_attr_getstack is the maximum size it could possibly
   // be given what currently mapped.  This can be huge, so we cap it.
   if (os::Linux::is_initial_thread()) {
     stack_bytes = stack_top - stack_bottom;

     if (stack_bytes > JavaThread::stack_size_at_create())
       stack_bytes = JavaThread::stack_size_at_create();

     stack_bottom = stack_top - stack_bytes;
   }

   assert(os::current_stack_pointer() >= stack_bottom, "should do");
   assert(os::current_stack_pointer() < stack_top, "should do");

   *bottom = stack_bottom;
   *size = stack_top - stack_bottom;
 }

 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) {
   ShouldNotCallThis();
 }

 void os::print_register_info(outputStream *st, void *context) {
   ShouldNotCallThis();
 }

 /////////////////////////////////////////////////////////////////////////////
 // Stubs for things that would be in linux_zero.s if it existed.
 // You probably want to disassemble these monkeys to check they're ok.

 extern "C" {
   int SpinPause() {
   }


   void _Copy_conjoint_jshorts_atomic(jshort* from, jshort* to, size_t count) {
     if (from > to) {
       jshort *end = from + count;
       while (from < end)
         *(to++) = *(from++);
     }
     else if (from < to) {
       jshort *end = from;
       from += count - 1;
       to   += count - 1;
       while (from >= end)
         *(to--) = *(from--);
     }
   }
   void _Copy_conjoint_jints_atomic(jint* from, jint* to, size_t count) {
     if (from > to) {
       jint *end = from + count;
       while (from < end)
         *(to++) = *(from++);
     }
     else if (from < to) {
       jint *end = from;
       from += count - 1;
       to   += count - 1;
       while (from >= end)
         *(to--) = *(from--);
     }
   }
   void _Copy_conjoint_jlongs_atomic(jlong* from, jlong* to, size_t count) {
     if (from > to) {
       jlong *end = from + count;
       while (from < end)
         os::atomic_copy64(from++, to++);
     }
     else if (from < to) {
       jlong *end = from;
       from += count - 1;
       to   += count - 1;
       while (from >= end)
         os::atomic_copy64(from--, to--);
     }
   }

   void _Copy_arrayof_conjoint_bytes(HeapWord* from,
                                     HeapWord* to,
                                     size_t    count) {
     memmove(to, from, count);
   }
   void _Copy_arrayof_conjoint_jshorts(HeapWord* from,
                                       HeapWord* to,
                                       size_t    count) {
     memmove(to, from, count * 2);
   }
   void _Copy_arrayof_conjoint_jints(HeapWord* from,
                                     HeapWord* to,
                                     size_t    count) {
     memmove(to, from, count * 4);
   }
   void _Copy_arrayof_conjoint_jlongs(HeapWord* from,
                                      HeapWord* to,
                                      size_t    count) {
     memmove(to, from, count * 8);
   }
 };

 /////////////////////////////////////////////////////////////////////////////
 // Implementations of atomic operations not supported by processors.
 //  -- http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Atomic-Builtins.html

 #ifndef _LP64
 extern "C" {
   long long unsigned int __sync_val_compare_and_swap_8(
     volatile void *ptr,
     long long unsigned int oldval,
     long long unsigned int newval) {
     ShouldNotCallThis();
   }
 };
 #endif // !_LP64

 #ifndef PRODUCT
 void os::verify_stack_alignment() {
 }
 #endif
	/*
	* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
	* Copyright 2007, 2008, 2009, 2010 Red Hat, Inc.
	* 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*
	*/

	// no precompiled headers
	#include "assembler_zero.inline.hpp"
	#include "classfile/classLoader.hpp"
	#include "classfile/systemDictionary.hpp"
	#include "classfile/vmSymbols.hpp"
	#include "code/icBuffer.hpp"
	#include "code/vtableStubs.hpp"
	#include "interpreter/interpreter.hpp"
	#include "jvm_linux.h"
	#include "memory/allocation.inline.hpp"
	#include "mutex_linux.inline.hpp"
	#include "nativeInst_zero.hpp"
	#include "os_share_linux.hpp"
	#include "prims/jniFastGetField.hpp"
	#include "prims/jvm.h"
	#include "prims/jvm_misc.hpp"
	#include "runtime/arguments.hpp"
	#include "runtime/extendedPC.hpp"
	#include "runtime/frame.inline.hpp"
	#include "runtime/interfaceSupport.hpp"
	#include "runtime/java.hpp"
	#include "runtime/javaCalls.hpp"
	#include "runtime/mutexLocker.hpp"
	#include "runtime/osThread.hpp"
	#include "runtime/sharedRuntime.hpp"
	#include "runtime/stubRoutines.hpp"
	#include "runtime/thread.inline.hpp"
	#include "runtime/timer.hpp"
	#include "utilities/events.hpp"
	#include "utilities/vmError.hpp"

	address os::current_stack_pointer() {
	// return the address of the current function
	return (address)__builtin_frame_address(0);
	}

	frame os::get_sender_for_C_frame(frame* fr) {
	ShouldNotCallThis();
	}

	frame os::current_frame() {
	// The only thing that calls this is the stack printing code in
	// VMError::report:
	// - Step 110 (printing stack bounds) uses the sp in the frame
	// to determine the amount of free space on the stack. We
	// set the sp to a close approximation of the real value in
	// order to allow this step to complete.
	// - Step 120 (printing native stack) tries to walk the stack.
	// The frame we create has a NULL pc, which is ignored as an
	// invalid frame.
	frame dummy = frame();
	dummy.set_sp((intptr_t *) current_stack_pointer());
	return dummy;
	}

	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).
	#ifdef SPARC
	// On SPARC, 0 != %hi(any real address), because there is no
	// allocation in the first 1Kb of the virtual address space.
	return (char *) 0;
	#else
	// This is the value for x86; works pretty well for PPC too.
	return (char *) -1;
	#endif // SPARC
	}

	void os::initialize_thread(Thread * thr){
	// Nothing to do.
	}

	address os::Linux::ucontext_get_pc(ucontext_t* uc) {
	ShouldNotCallThis();
	}

	ExtendedPC os::fetch_frame_from_context(void* ucVoid,
	intptr_t** ret_sp,
	intptr_t** ret_fp) {
	ShouldNotCallThis();
	}

	frame os::fetch_frame_from_context(void* ucVoid) {
	ShouldNotCallThis();
	}

	extern "C" JNIEXPORT 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;
	}
	}
	}

	if (info != NULL && thread != NULL) {
	// 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();
	ShouldNotCallThis();
	}
	else if (thread->in_stack_red_zone(addr)) {
	thread->disable_stack_red_zone();
	ShouldNotCallThis();
	}
	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 true;
	}
	thread->osthread()->clear_expanding_stack();
	}
	else {
	fatal("recursive segv. expanding stack.");
	}
	}
	}
	}

	/*if (thread->thread_state() == _thread_in_Java) {
	ShouldNotCallThis();
	}
	else*/ if (thread->thread_state() == _thread_in_vm &&
	sig == SIGBUS && thread->doing_unsafe_access()) {
	ShouldNotCallThis();
	}

	// 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 permission is restored.
	os::block_on_serialize_page_trap();
	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;
	}

	#ifndef PRODUCT
	if (sig == SIGSEGV) {
	fatal("\n#"
	"\n# /--------------------\\"
	"\n# \| segmentation fault \|"
	"\n# \\---\\ /--------------/"
	"\n# /"
	"\n# [-] \|\\_/\| "
	"\n# (+)=C \|o o\|__ "
	"\n# \| \| =-*-=__\\ "
	"\n# OOO c_c_(___)");
	}
	#endif // !PRODUCT

	const char *fmt = "caught unhandled signal %d";
	char buf[64];

	sprintf(buf, fmt, sig);
	fatal(buf);
	}

	void os::Linux::init_thread_fpu_state(void) {
	// Nothing to do
	}

	int os::Linux::get_fpu_control_word() {
	ShouldNotCallThis();
	}

	void os::Linux::set_fpu_control_word(int fpu) {
	ShouldNotCallThis();
	}

	bool os::is_allocatable(size_t bytes) {
	#ifdef _LP64
	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 // _LP64
	}

	///////////////////////////////////////////////////////////////////////////////
	// thread stack

	size_t os::Linux::min_stack_allowed = 64 * K;

	bool os::Linux::supports_variable_stack_size() {
	return true;
	}

	size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
	#ifdef _LP64
	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 // _LP64
	return s;
	}

	size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
	// Only enable glibc guard pages for non-Java threads
	// (Java threads have HotSpot guard pages)
	return (thr_type == java_thread ? 0 : page_size());
	}

	static void current_stack_region(address bottom, size_t size) {
	pthread_attr_t attr;
	int res = pthread_getattr_np(pthread_self(), &attr);
	if (res != 0) {
	if (res == ENOMEM) {
	vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
	}
	else {
	fatal(err_msg("pthread_getattr_np failed with errno = %d", res));
	}
	}

	address stack_bottom;
	size_t stack_bytes;
	res = pthread_attr_getstack(&attr, (void **) &stack_bottom, &stack_bytes);
	if (res != 0) {
	fatal(err_msg("pthread_attr_getstack failed with errno = %d", res));
	}
	address stack_top = stack_bottom + stack_bytes;

	// The block of memory returned by pthread_attr_getstack() includes
	// guard pages where present. We need to trim these off.
	size_t page_bytes = os::Linux::page_size();
	assert(((intptr_t) stack_bottom & (page_bytes - 1)) == 0, "unaligned stack");

	size_t guard_bytes;
	res = pthread_attr_getguardsize(&attr, &guard_bytes);
	if (res != 0) {
	fatal(err_msg("pthread_attr_getguardsize failed with errno = %d", res));
	}
	int guard_pages = align_size_up(guard_bytes, page_bytes) / page_bytes;
	assert(guard_bytes == guard_pages * page_bytes, "unaligned guard");

	#ifdef IA64
	// IA64 has two stacks sharing the same area of memory, a normal
	// stack growing downwards and a register stack growing upwards.
	// Guard pages, if present, are in the centre. This code splits
	// the stack in two even without guard pages, though in theory
	// there's nothing to stop us allocating more to the normal stack
	// or more to the register stack if one or the other were found
	// to grow faster.
	int total_pages = align_size_down(stack_bytes, page_bytes) / page_bytes;
	stack_bottom += (total_pages - guard_pages) / 2 * page_bytes;
	#endif // IA64

	stack_bottom += guard_bytes;

	pthread_attr_destroy(&attr);

	// The initial thread has a growable stack, and the size reported
	// by pthread_attr_getstack is the maximum size it could possibly
	// be given what currently mapped. This can be huge, so we cap it.
	if (os::Linux::is_initial_thread()) {
	stack_bytes = stack_top - stack_bottom;

	if (stack_bytes > JavaThread::stack_size_at_create())
	stack_bytes = JavaThread::stack_size_at_create();

	stack_bottom = stack_top - stack_bytes;
	}

	assert(os::current_stack_pointer() >= stack_bottom, "should do");
	assert(os::current_stack_pointer() < stack_top, "should do");

	*bottom = stack_bottom;
	*size = stack_top - stack_bottom;
	}

	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) {
	ShouldNotCallThis();
	}

	void os::print_register_info(outputStream st, void context) {
	ShouldNotCallThis();
	}

	/////////////////////////////////////////////////////////////////////////////
	// Stubs for things that would be in linux_zero.s if it existed.
	// You probably want to disassemble these monkeys to check they're ok.

	extern "C" {
	int SpinPause() {
	}


	void _Copy_conjoint_jshorts_atomic(jshort* from, jshort* to, size_t count) {
	if (from > to) {
	jshort *end = from + count;
	while (from < end)
	(to++) = (from++);
	}
	else if (from < to) {
	jshort *end = from;
	from += count - 1;
	to += count - 1;
	while (from >= end)
	(to--) = (from--);
	}
	}
	void _Copy_conjoint_jints_atomic(jint* from, jint* to, size_t count) {
	if (from > to) {
	jint *end = from + count;
	while (from < end)
	(to++) = (from++);
	}
	else if (from < to) {
	jint *end = from;
	from += count - 1;
	to += count - 1;
	while (from >= end)
	(to--) = (from--);
	}
	}
	void _Copy_conjoint_jlongs_atomic(jlong* from, jlong* to, size_t count) {
	if (from > to) {
	jlong *end = from + count;
	while (from < end)
	os::atomic_copy64(from++, to++);
	}
	else if (from < to) {
	jlong *end = from;
	from += count - 1;
	to += count - 1;
	while (from >= end)
	os::atomic_copy64(from--, to--);
	}
	}

	void _Copy_arrayof_conjoint_bytes(HeapWord* from,
	HeapWord* to,
	size_t count) {
	memmove(to, from, count);
	}
	void _Copy_arrayof_conjoint_jshorts(HeapWord* from,
	HeapWord* to,
	size_t count) {
	memmove(to, from, count * 2);
	}
	void _Copy_arrayof_conjoint_jints(HeapWord* from,
	HeapWord* to,
	size_t count) {
	memmove(to, from, count * 4);
	}
	void _Copy_arrayof_conjoint_jlongs(HeapWord* from,
	HeapWord* to,
	size_t count) {
	memmove(to, from, count * 8);
	}
	};

	/////////////////////////////////////////////////////////////////////////////
	// Implementations of atomic operations not supported by processors.
	// -- http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Atomic-Builtins.html

	#ifndef _LP64
	extern "C" {
	long long unsigned int __sync_val_compare_and_swap_8(
	volatile void *ptr,
	long long unsigned int oldval,
	long long unsigned int newval) {
	ShouldNotCallThis();
	}
	};
	#endif // !_LP64

	#ifndef PRODUCT
	void os::verify_stack_alignment() {
	}
	#endif