jdk

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/*
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 * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
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 * Copyright (c) 2014, Red Hat Inc. All rights reserved.
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 * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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// no precompiled headers
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#include "asm/macroAssembler.hpp"
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#include "classfile/classLoader.hpp"
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#include "classfile/vmSymbols.hpp"
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#include "code/codeCache.hpp"
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#include "code/vtableStubs.hpp"
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#include "interpreter/interpreter.hpp"
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#include "jvm.h"
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#include "logging/log.hpp"
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#include "memory/allocation.inline.hpp"
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#include "os_bsd.hpp"
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#include "os_posix.hpp"
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#include "prims/jniFastGetField.hpp"
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#include "prims/jvm_misc.hpp"
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#include "runtime/arguments.hpp"
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#include "runtime/frame.inline.hpp"
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#include "runtime/interfaceSupport.inline.hpp"
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#include "runtime/java.hpp"
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#include "runtime/javaCalls.hpp"
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#include "runtime/javaThread.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/osThread.hpp"
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#include "runtime/safepointMechanism.hpp"
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#include "runtime/sharedRuntime.hpp"
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#include "runtime/stubRoutines.hpp"
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#include "runtime/timer.hpp"
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#include "signals_posix.hpp"
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#include "utilities/align.hpp"
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#include "utilities/events.hpp"
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#include "utilities/vmError.hpp"
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// put OS-includes here
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# include <sys/types.h>
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# include <sys/mman.h>
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# include <pthread.h>
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# include <signal.h>
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# include <errno.h>
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# include <dlfcn.h>
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# include <stdlib.h>
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# include <stdio.h>
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# include <unistd.h>
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# include <sys/resource.h>
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# include <sys/stat.h>
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# include <sys/time.h>
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# include <sys/utsname.h>
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# include <sys/socket.h>
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# include <sys/wait.h>
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# include <pwd.h>
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# include <poll.h>
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#ifndef __OpenBSD__
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# include <ucontext.h>
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#endif
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#if !defined(__APPLE__) && !defined(__NetBSD__)
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# include <pthread_np.h>
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#endif
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#define SPELL_REG_SP "sp"
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#define SPELL_REG_FP "fp"
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#ifdef __APPLE__
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// see darwin-xnu/osfmk/mach/arm/_structs.h
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// 10.5 UNIX03 member name prefixes
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#define DU3_PREFIX(s, m) __ ## s.__ ## m
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#endif
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#define context_x    uc_mcontext->DU3_PREFIX(ss,x)
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#define context_fp   uc_mcontext->DU3_PREFIX(ss,fp)
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#define context_lr   uc_mcontext->DU3_PREFIX(ss,lr)
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#define context_sp   uc_mcontext->DU3_PREFIX(ss,sp)
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#define context_pc   uc_mcontext->DU3_PREFIX(ss,pc)
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#define context_cpsr uc_mcontext->DU3_PREFIX(ss,cpsr)
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#define context_esr  uc_mcontext->DU3_PREFIX(es,esr)
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address os::current_stack_pointer() {
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#if defined(__clang__) || defined(__llvm__)
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  void *sp;
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  __asm__("mov %0, " SPELL_REG_SP : "=r"(sp));
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  return (address) sp;
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#else
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  register void *sp __asm__ (SPELL_REG_SP);
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  return (address) sp;
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#endif
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}
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char* os::non_memory_address_word() {
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  // Must never look like an address returned by reserve_memory,
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  // even in its subfields (as defined by the CPU immediate fields,
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  // if the CPU splits constants across multiple instructions).
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  // the return value used in computation of Universe::non_oop_word(), which
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  // is loaded by cpu/aarch64 by MacroAssembler::movptr(Register, uintptr_t)
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  return (char*) 0xffffffffffff;
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}
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address os::Posix::ucontext_get_pc(const ucontext_t * uc) {
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  return (address)uc->context_pc;
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}
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void os::Posix::ucontext_set_pc(ucontext_t * uc, address pc) {
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  uc->context_pc = (intptr_t)pc ;
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}
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intptr_t* os::Bsd::ucontext_get_sp(const ucontext_t * uc) {
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  return (intptr_t*)uc->context_sp;
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}
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intptr_t* os::Bsd::ucontext_get_fp(const ucontext_t * uc) {
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  return (intptr_t*)uc->context_fp;
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}
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address os::fetch_frame_from_context(const void* ucVoid,
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                    intptr_t** ret_sp, intptr_t** ret_fp) {
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  address epc;
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  const ucontext_t* uc = (const ucontext_t*)ucVoid;
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  if (uc != nullptr) {
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    epc = os::Posix::ucontext_get_pc(uc);
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    if (ret_sp) *ret_sp = os::Bsd::ucontext_get_sp(uc);
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    if (ret_fp) *ret_fp = os::Bsd::ucontext_get_fp(uc);
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  } else {
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    epc = nullptr;
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    if (ret_sp) *ret_sp = (intptr_t *)nullptr;
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    if (ret_fp) *ret_fp = (intptr_t *)nullptr;
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  }
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  return epc;
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}
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frame os::fetch_frame_from_context(const void* ucVoid) {
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  intptr_t* sp;
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  intptr_t* fp;
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  address epc = fetch_frame_from_context(ucVoid, &sp, &fp);
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  return frame(sp, fp, epc);
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}
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frame os::fetch_compiled_frame_from_context(const void* ucVoid) {
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  const ucontext_t* uc = (const ucontext_t*)ucVoid;
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  // In compiled code, the stack banging is performed before LR
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  // has been saved in the frame.  LR is live, and SP and FP
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  // belong to the caller.
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  intptr_t* fp = os::Bsd::ucontext_get_fp(uc);
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  intptr_t* sp = os::Bsd::ucontext_get_sp(uc);
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  address pc = (address)(uc->context_lr
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                         - NativeInstruction::instruction_size);
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  return frame(sp, fp, pc);
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}
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// JVM compiled with -fno-omit-frame-pointer, so RFP is saved on the stack.
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frame os::get_sender_for_C_frame(frame* fr) {
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  return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
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}
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NOINLINE frame os::current_frame() {
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  intptr_t *fp = *(intptr_t **)__builtin_frame_address(0);
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  frame myframe((intptr_t*)os::current_stack_pointer(),
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                (intptr_t*)fp,
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                CAST_FROM_FN_PTR(address, os::current_frame));
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  if (os::is_first_C_frame(&myframe)) {
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    // stack is not walkable
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    return frame();
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  } else {
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    return os::get_sender_for_C_frame(&myframe);
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  }
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}
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bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
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                                             ucontext_t* uc, JavaThread* thread) {
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  // Enable WXWrite: this function is called by the signal handler at arbitrary
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  // point of execution.
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  ThreadWXEnable wx(WXWrite, thread);
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  // decide if this trap can be handled by a stub
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  address stub = nullptr;
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  address pc          = nullptr;
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  //%note os_trap_1
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  if (info != nullptr && uc != nullptr && thread != nullptr) {
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    pc = (address) os::Posix::ucontext_get_pc(uc);
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    // Handle ALL stack overflow variations here
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    if (sig == SIGSEGV || sig == SIGBUS) {
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      address addr = (address) info->si_addr;
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      // Make sure the high order byte is sign extended, as it may be masked away by the hardware.
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      if ((uintptr_t(addr) & (uintptr_t(1) << 55)) != 0) {
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        addr = address(uintptr_t(addr) | (uintptr_t(0xFF) << 56));
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      }
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      // check if fault address is within thread stack
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      if (thread->is_in_full_stack(addr)) {
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        // stack overflow
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        if (os::Posix::handle_stack_overflow(thread, addr, pc, uc, &stub)) {
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          return true; // continue
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        }
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      }
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    }
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    // We test if stub is already set (by the stack overflow code
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    // above) so it is not overwritten by the code that follows. This
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    // check is not required on other platforms, because on other
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    // platforms we check for SIGSEGV only or SIGBUS only, where here
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    // we have to check for both SIGSEGV and SIGBUS.
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    if (thread->thread_state() == _thread_in_Java && stub == nullptr) {
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      // Java thread running in Java code => find exception handler if any
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      // a fault inside compiled code, the interpreter, or a stub
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      // Handle signal from NativeJump::patch_verified_entry().
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      if ((sig == SIGILL)
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          && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
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        if (TraceTraps) {
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          tty->print_cr("trap: not_entrant");
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        }
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        stub = SharedRuntime::get_handle_wrong_method_stub();
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      } else if ((sig == SIGSEGV || sig == SIGBUS) && SafepointMechanism::is_poll_address((address)info->si_addr)) {
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        stub = SharedRuntime::get_poll_stub(pc);
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#if defined(__APPLE__)
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      // 32-bit Darwin reports a SIGBUS for nearly all memory access exceptions.
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      // 64-bit Darwin may also use a SIGBUS (seen with compressed oops).
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      // Catching SIGBUS here prevents the implicit SIGBUS null check below from
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      // being called, so only do so if the implicit null check is not necessary.
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      } else if (sig == SIGBUS && !MacroAssembler::uses_implicit_null_check(info->si_addr)) {
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#else
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      } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
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#endif
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        // BugId 4454115: A read from a MappedByteBuffer can fault
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        // here if the underlying file has been truncated.
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        // Do not crash the VM in such a case.
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        CodeBlob* cb = CodeCache::find_blob(pc);
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        nmethod* nm = (cb != nullptr) ? cb->as_nmethod_or_null() : nullptr;
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        bool is_unsafe_memory_access = (thread->doing_unsafe_access() && UnsafeMemoryAccess::contains_pc(pc));
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        if ((nm != nullptr && nm->has_unsafe_access()) || is_unsafe_memory_access) {
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          address next_pc = pc + NativeCall::instruction_size;
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          if (is_unsafe_memory_access) {
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            next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
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          }
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          stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
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        }
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      } else if (sig == SIGILL && nativeInstruction_at(pc)->is_stop()) {
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        // Pull a pointer to the error message out of the instruction
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        // stream.
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        const uint64_t *detail_msg_ptr
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          = (uint64_t*)(pc + NativeInstruction::instruction_size);
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        const char *detail_msg = (const char *)*detail_msg_ptr;
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        const char *msg = "stop";
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        if (TraceTraps) {
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          tty->print_cr("trap: %s: (SIGILL)", msg);
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        }
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        // End life with a fatal error, message and detail message and the context.
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        // Note: no need to do any post-processing here (e.g. signal chaining)
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        VMError::report_and_die(thread, uc, nullptr, 0, msg, "%s", detail_msg);
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        ShouldNotReachHere();
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      } else if (sig == SIGFPE &&
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          (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
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        stub =
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          SharedRuntime::
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          continuation_for_implicit_exception(thread,
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                                              pc,
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                                              SharedRuntime::
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                                              IMPLICIT_DIVIDE_BY_ZERO);
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      } else if ((sig == SIGSEGV || sig == SIGBUS) &&
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                 MacroAssembler::uses_implicit_null_check(info->si_addr)) {
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          // Determination of interpreter/vtable stub/compiled code null exception
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          stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
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      }
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    } else if ((thread->thread_state() == _thread_in_vm ||
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                 thread->thread_state() == _thread_in_native) &&
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               sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
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               thread->doing_unsafe_access()) {
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      address next_pc = pc + NativeCall::instruction_size;
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      if (UnsafeMemoryAccess::contains_pc(pc)) {
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        next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
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      }
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      stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
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    }
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    // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
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    // and the heap gets shrunk before the field access.
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    if ((sig == SIGSEGV) || (sig == SIGBUS)) {
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      address addr = JNI_FastGetField::find_slowcase_pc(pc);
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      if (addr != (address)-1) {
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        stub = addr;
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      }
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    }
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  }
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  if (stub != nullptr) {
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    // save all thread context in case we need to restore it
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    if (thread != nullptr) thread->set_saved_exception_pc(pc);
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    os::Posix::ucontext_set_pc(uc, stub);
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    return true;
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  }
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  return false; // Mute compiler
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}
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void os::Bsd::init_thread_fpu_state(void) {
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}
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////////////////////////////////////////////////////////////////////////////////
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// thread stack
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// Minimum usable stack sizes required to get to user code. Space for
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// HotSpot guard pages is added later.
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size_t os::_compiler_thread_min_stack_allowed = 72 * K;
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size_t os::_java_thread_min_stack_allowed = 72 * K;
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size_t os::_vm_internal_thread_min_stack_allowed = 72 * K;
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// return default stack size for thr_type
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size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
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  // default stack size (compiler thread needs larger stack)
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  size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
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  return s;
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}
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void os::current_stack_base_and_size(address* base, size_t* size) {
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  address bottom;
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#ifdef __APPLE__
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  pthread_t self = pthread_self();
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  *base = (address) pthread_get_stackaddr_np(self);
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  *size = pthread_get_stacksize_np(self);
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  bottom = *base - *size;
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#elif defined(__OpenBSD__)
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  stack_t ss;
356
  int rslt = pthread_stackseg_np(pthread_self(), &ss);
357

358
  if (rslt != 0)
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    fatal("pthread_stackseg_np failed with error = %d", rslt);
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361
  *base = (address) ss.ss_sp;
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  *size = ss.ss_size;
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  bottom = *base - *size;
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#else
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  pthread_attr_t attr;
366

367
  int rslt = pthread_attr_init(&attr);
368

369
  // JVM needs to know exact stack location, abort if it fails
370
  if (rslt != 0)
371
    fatal("pthread_attr_init failed with error = %d", rslt);
372

373
  rslt = pthread_attr_get_np(pthread_self(), &attr);
374

375
  if (rslt != 0)
376
    fatal("pthread_attr_get_np failed with error = %d", rslt);
377

378
  if (pthread_attr_getstackaddr(&attr, (void **)&bottom) != 0 ||
379
      pthread_attr_getstacksize(&attr, size) != 0) {
380
    fatal("Can not locate current stack attributes!");
381
  }
382

383
  *base = bottom + *size;
384

385
  pthread_attr_destroy(&attr);
386
#endif
387
  assert(os::current_stack_pointer() >= bottom &&
388
         os::current_stack_pointer() < *base, "just checking");
389
}
390

391
/////////////////////////////////////////////////////////////////////////////
392
// helper functions for fatal error handler
393

394
void os::print_context(outputStream *st, const void *context) {
395
  if (context == nullptr) return;
396

397
  const ucontext_t *uc = (const ucontext_t*)context;
398

399
  st->print_cr("Registers:");
400
  st->print( " x0=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 0]);
401
  st->print("  x1=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 1]);
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  st->print("  x2=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 2]);
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  st->print("  x3=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 3]);
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  st->cr();
405
  st->print( " x4=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 4]);
406
  st->print("  x5=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 5]);
407
  st->print("  x6=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 6]);
408
  st->print("  x7=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 7]);
409
  st->cr();
410
  st->print( " x8=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 8]);
411
  st->print("  x9=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 9]);
412
  st->print(" x10=" INTPTR_FORMAT, (intptr_t)uc->context_x[10]);
413
  st->print(" x11=" INTPTR_FORMAT, (intptr_t)uc->context_x[11]);
414
  st->cr();
415
  st->print( "x12=" INTPTR_FORMAT, (intptr_t)uc->context_x[12]);
416
  st->print(" x13=" INTPTR_FORMAT, (intptr_t)uc->context_x[13]);
417
  st->print(" x14=" INTPTR_FORMAT, (intptr_t)uc->context_x[14]);
418
  st->print(" x15=" INTPTR_FORMAT, (intptr_t)uc->context_x[15]);
419
  st->cr();
420
  st->print( "x16=" INTPTR_FORMAT, (intptr_t)uc->context_x[16]);
421
  st->print(" x17=" INTPTR_FORMAT, (intptr_t)uc->context_x[17]);
422
  st->print(" x18=" INTPTR_FORMAT, (intptr_t)uc->context_x[18]);
423
  st->print(" x19=" INTPTR_FORMAT, (intptr_t)uc->context_x[19]);
424
  st->cr();
425
  st->print( "x20=" INTPTR_FORMAT, (intptr_t)uc->context_x[20]);
426
  st->print(" x21=" INTPTR_FORMAT, (intptr_t)uc->context_x[21]);
427
  st->print(" x22=" INTPTR_FORMAT, (intptr_t)uc->context_x[22]);
428
  st->print(" x23=" INTPTR_FORMAT, (intptr_t)uc->context_x[23]);
429
  st->cr();
430
  st->print( "x24=" INTPTR_FORMAT, (intptr_t)uc->context_x[24]);
431
  st->print(" x25=" INTPTR_FORMAT, (intptr_t)uc->context_x[25]);
432
  st->print(" x26=" INTPTR_FORMAT, (intptr_t)uc->context_x[26]);
433
  st->print(" x27=" INTPTR_FORMAT, (intptr_t)uc->context_x[27]);
434
  st->cr();
435
  st->print( "x28=" INTPTR_FORMAT, (intptr_t)uc->context_x[28]);
436
  st->print("  fp=" INTPTR_FORMAT, (intptr_t)uc->context_fp);
437
  st->print("  lr=" INTPTR_FORMAT, (intptr_t)uc->context_lr);
438
  st->print("  sp=" INTPTR_FORMAT, (intptr_t)uc->context_sp);
439
  st->cr();
440
  st->print(  "pc=" INTPTR_FORMAT,  (intptr_t)uc->context_pc);
441
  st->print(" cpsr=" INTPTR_FORMAT, (intptr_t)uc->context_cpsr);
442
  st->cr();
443
}
444

445
void os::print_tos_pc(outputStream *st, const void *context) {
446
  if (context == nullptr) return;
447

448
  const ucontext_t* uc = (const ucontext_t*)context;
449

450
  address sp = (address)os::Bsd::ucontext_get_sp(uc);
451
  print_tos(st, sp);
452
  st->cr();
453

454
  // Note: it may be unsafe to inspect memory near pc. For example, pc may
455
  // point to garbage if entry point in an nmethod is corrupted. Leave
456
  // this at the end, and hope for the best.
457
  address pc = os::Posix::ucontext_get_pc(uc);
458
  print_instructions(st, pc);
459
  st->cr();
460
}
461

462
void os::print_register_info(outputStream *st, const void *context, int& continuation) {
463
  const int register_count = 29 /* x0-x28 */ + 3 /* fp, lr, sp */;
464
  int n = continuation;
465
  assert(n >= 0 && n <= register_count, "Invalid continuation value");
466
  if (context == nullptr || n == register_count) {
467
    return;
468
  }
469

470
  const ucontext_t *uc = (const ucontext_t*)context;
471
  while (n < register_count) {
472
    // Update continuation with next index before printing location
473
    continuation = n + 1;
474
    switch (n) {
475
    case 29:
476
      st->print(" fp="); print_location(st, uc->context_fp);
477
      break;
478
    case 30:
479
      st->print(" lr="); print_location(st, uc->context_lr);
480
      break;
481
    case 31:
482
      st->print(" sp="); print_location(st, uc->context_sp);
483
      break;
484
    default:
485
      st->print("x%-2d=",n); print_location(st, uc->context_x[n]);
486
      break;
487
    }
488
    ++n;
489
  }
490
}
491

492
void os::setup_fpu() {
493
}
494

495
#ifndef PRODUCT
496
void os::verify_stack_alignment() {
497
  assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
498
}
499
#endif
500

501
int os::extra_bang_size_in_bytes() {
502
  // AArch64 does not require the additional stack bang.
503
  return 0;
504
}
505

506
void os::current_thread_enable_wx(WXMode mode) {
507
  pthread_jit_write_protect_np(mode == WXExec);
508
}
509

510
static inline void atomic_copy64(const volatile void *src, volatile void *dst) {
511
  *(jlong *) dst = *(const jlong *) src;
512
}
513

514
extern "C" {
515
  int SpinPause() {
516
    // We don't use StubRoutines::aarch64::spin_wait stub in order to
517
    // avoid a costly call to os::current_thread_enable_wx() on MacOS.
518
    // We should return 1 if SpinPause is implemented, and since there
519
    // will be a sequence of 11 instructions for NONE and YIELD and 12
520
    // instructions for NOP and ISB, SpinPause will always return 1.
521
    uint64_t br_dst;
522
    const int instructions_per_case = 2;
523
    int64_t off = VM_Version::spin_wait_desc().inst() * instructions_per_case * Assembler::instruction_size;
524

525
    assert(VM_Version::spin_wait_desc().inst() >= SpinWait::NONE &&
526
           VM_Version::spin_wait_desc().inst() <= SpinWait::YIELD, "must be");
527
    assert(-1 == SpinWait::NONE,  "must be");
528
    assert( 0 == SpinWait::NOP,   "must be");
529
    assert( 1 == SpinWait::ISB,   "must be");
530
    assert( 2 == SpinWait::YIELD, "must be");
531

532
    asm volatile(
533
        "  adr  %[d], 20          \n" // 20 == PC here + 5 instructions => address
534
                                      // to entry for case SpinWait::NOP
535
        "  add  %[d], %[d], %[o]  \n"
536
        "  br   %[d]              \n"
537
        "  b    SpinPause_return  \n" // case SpinWait::NONE  (-1)
538
        "  nop                    \n" // padding
539
        "  nop                    \n" // case SpinWait::NOP   ( 0)
540
        "  b    SpinPause_return  \n"
541
        "  isb                    \n" // case SpinWait::ISB   ( 1)
542
        "  b    SpinPause_return  \n"
543
        "  yield                  \n" // case SpinWait::YIELD ( 2)
544
        "SpinPause_return:        \n"
545
        : [d]"=&r"(br_dst)
546
        : [o]"r"(off)
547
        : "memory");
548
    return 1;
549
  }
550

551
  void _Copy_conjoint_jshorts_atomic(const jshort* from, jshort* to, size_t count) {
552
    if (from > to) {
553
      const jshort *end = from + count;
554
      while (from < end)
555
        *(to++) = *(from++);
556
    }
557
    else if (from < to) {
558
      const jshort *end = from;
559
      from += count - 1;
560
      to   += count - 1;
561
      while (from >= end)
562
        *(to--) = *(from--);
563
    }
564
  }
565
  void _Copy_conjoint_jints_atomic(const jint* from, jint* to, size_t count) {
566
    if (from > to) {
567
      const jint *end = from + count;
568
      while (from < end)
569
        *(to++) = *(from++);
570
    }
571
    else if (from < to) {
572
      const jint *end = from;
573
      from += count - 1;
574
      to   += count - 1;
575
      while (from >= end)
576
        *(to--) = *(from--);
577
    }
578
  }
579

580
  void _Copy_conjoint_jlongs_atomic(const jlong* from, jlong* to, size_t count) {
581
    if (from > to) {
582
      const jlong *end = from + count;
583
      while (from < end)
584
        atomic_copy64(from++, to++);
585
    }
586
    else if (from < to) {
587
      const jlong *end = from;
588
      from += count - 1;
589
      to   += count - 1;
590
      while (from >= end)
591
        atomic_copy64(from--, to--);
592
    }
593
  }
594

595
  void _Copy_arrayof_conjoint_bytes(const HeapWord* from,
596
                                    HeapWord* to,
597
                                    size_t    count) {
598
    memmove(to, from, count);
599
  }
600
  void _Copy_arrayof_conjoint_jshorts(const HeapWord* from,
601
                                      HeapWord* to,
602
                                      size_t    count) {
603
    memmove(to, from, count * 2);
604
  }
605
  void _Copy_arrayof_conjoint_jints(const HeapWord* from,
606
                                    HeapWord* to,
607
                                    size_t    count) {
608
    memmove(to, from, count * 4);
609
  }
610
  void _Copy_arrayof_conjoint_jlongs(const HeapWord* from,
611
                                     HeapWord* to,
612
                                     size_t    count) {
613
    memmove(to, from, count * 8);
614
  }
615
};
616