changeset 55879:865775b86780

8214527: ZGC for Aarch64 Summary: Implement ZGC for AArch64 Reviewed-by: aph, pliden, eosterlund, rkennke, shade, njian, adinn
author smonteith
date Thu, 13 Jun 2019 15:24:34 +0100
parents bd613b97c7c8
children 22b3b7983ada
files make/autoconf/hotspot.m4 src/hotspot/cpu/aarch64/aarch64.ad src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp src/hotspot/cpu/aarch64/gc/z/zBarrierSetAssembler_aarch64.cpp src/hotspot/cpu/aarch64/gc/z/zBarrierSetAssembler_aarch64.hpp src/hotspot/cpu/aarch64/gc/z/z_aarch64.ad src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zArguments_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.hpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.hpp src/hotspot/os_cpu/linux_aarch64/gc/z/zGlobals_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zGlobals_linux_aarch64.hpp src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp
diffstat 16 files changed, 2615 insertions(+), 3 deletions(-) [+]
line wrap: on
line diff
--- a/make/autoconf/hotspot.m4	Thu Jun 13 12:27:29 2019 +0200
+++ b/make/autoconf/hotspot.m4	Thu Jun 13 15:24:34 2019 +0100
@@ -350,7 +350,8 @@
 
   # Only enable ZGC on supported platforms
   AC_MSG_CHECKING([if zgc can be built])
-  if test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xx86_64"; then
+  if (test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xx86_64") || \
+     (test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xaarch64"); then
     AC_MSG_RESULT([yes])
   else
     DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES zgc"
--- a/src/hotspot/cpu/aarch64/aarch64.ad	Thu Jun 13 12:27:29 2019 +0200
+++ b/src/hotspot/cpu/aarch64/aarch64.ad	Thu Jun 13 15:24:34 2019 +0100
@@ -957,6 +957,146 @@
     V3, V3_H
 );
 
+// Class for 128 bit register v4
+reg_class v4_reg(
+    V4, V4_H
+);
+
+// Class for 128 bit register v5
+reg_class v5_reg(
+    V5, V5_H
+);
+
+// Class for 128 bit register v6
+reg_class v6_reg(
+    V6, V6_H
+);
+
+// Class for 128 bit register v7
+reg_class v7_reg(
+    V7, V7_H
+);
+
+// Class for 128 bit register v8
+reg_class v8_reg(
+    V8, V8_H
+);
+
+// Class for 128 bit register v9
+reg_class v9_reg(
+    V9, V9_H
+);
+
+// Class for 128 bit register v10
+reg_class v10_reg(
+    V10, V10_H
+);
+
+// Class for 128 bit register v11
+reg_class v11_reg(
+    V11, V11_H
+);
+
+// Class for 128 bit register v12
+reg_class v12_reg(
+    V12, V12_H
+);
+
+// Class for 128 bit register v13
+reg_class v13_reg(
+    V13, V13_H
+);
+
+// Class for 128 bit register v14
+reg_class v14_reg(
+    V14, V14_H
+);
+
+// Class for 128 bit register v15
+reg_class v15_reg(
+    V15, V15_H
+);
+
+// Class for 128 bit register v16
+reg_class v16_reg(
+    V16, V16_H
+);
+
+// Class for 128 bit register v17
+reg_class v17_reg(
+    V17, V17_H
+);
+
+// Class for 128 bit register v18
+reg_class v18_reg(
+    V18, V18_H
+);
+
+// Class for 128 bit register v19
+reg_class v19_reg(
+    V19, V19_H
+);
+
+// Class for 128 bit register v20
+reg_class v20_reg(
+    V20, V20_H
+);
+
+// Class for 128 bit register v21
+reg_class v21_reg(
+    V21, V21_H
+);
+
+// Class for 128 bit register v22
+reg_class v22_reg(
+    V22, V22_H
+);
+
+// Class for 128 bit register v23
+reg_class v23_reg(
+    V23, V23_H
+);
+
+// Class for 128 bit register v24
+reg_class v24_reg(
+    V24, V24_H
+);
+
+// Class for 128 bit register v25
+reg_class v25_reg(
+    V25, V25_H
+);
+
+// Class for 128 bit register v26
+reg_class v26_reg(
+    V26, V26_H
+);
+
+// Class for 128 bit register v27
+reg_class v27_reg(
+    V27, V27_H
+);
+
+// Class for 128 bit register v28
+reg_class v28_reg(
+    V28, V28_H
+);
+
+// Class for 128 bit register v29
+reg_class v29_reg(
+    V29, V29_H
+);
+
+// Class for 128 bit register v30
+reg_class v30_reg(
+    V30, V30_H
+);
+
+// Class for 128 bit register v31
+reg_class v31_reg(
+    V31, V31_H
+);
+
 // Singleton class for condition codes
 reg_class int_flags(RFLAGS);
 
@@ -4774,6 +4914,258 @@
   interface(REG_INTER);
 %}
 
+operand vRegD_V4()
+%{
+  constraint(ALLOC_IN_RC(v4_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V5()
+%{
+  constraint(ALLOC_IN_RC(v5_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V6()
+%{
+  constraint(ALLOC_IN_RC(v6_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V7()
+%{
+  constraint(ALLOC_IN_RC(v7_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V8()
+%{
+  constraint(ALLOC_IN_RC(v8_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V9()
+%{
+  constraint(ALLOC_IN_RC(v9_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V10()
+%{
+  constraint(ALLOC_IN_RC(v10_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V11()
+%{
+  constraint(ALLOC_IN_RC(v11_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V12()
+%{
+  constraint(ALLOC_IN_RC(v12_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V13()
+%{
+  constraint(ALLOC_IN_RC(v13_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V14()
+%{
+  constraint(ALLOC_IN_RC(v14_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V15()
+%{
+  constraint(ALLOC_IN_RC(v15_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V16()
+%{
+  constraint(ALLOC_IN_RC(v16_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V17()
+%{
+  constraint(ALLOC_IN_RC(v17_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V18()
+%{
+  constraint(ALLOC_IN_RC(v18_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V19()
+%{
+  constraint(ALLOC_IN_RC(v19_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V20()
+%{
+  constraint(ALLOC_IN_RC(v20_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V21()
+%{
+  constraint(ALLOC_IN_RC(v21_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V22()
+%{
+  constraint(ALLOC_IN_RC(v22_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V23()
+%{
+  constraint(ALLOC_IN_RC(v23_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V24()
+%{
+  constraint(ALLOC_IN_RC(v24_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V25()
+%{
+  constraint(ALLOC_IN_RC(v25_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V26()
+%{
+  constraint(ALLOC_IN_RC(v26_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V27()
+%{
+  constraint(ALLOC_IN_RC(v27_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V28()
+%{
+  constraint(ALLOC_IN_RC(v28_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V29()
+%{
+  constraint(ALLOC_IN_RC(v29_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V30()
+%{
+  constraint(ALLOC_IN_RC(v30_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
+operand vRegD_V31()
+%{
+  constraint(ALLOC_IN_RC(v31_reg));
+  match(RegD);
+  op_cost(0);
+  format %{ %}
+  interface(REG_INTER);
+%}
+
 // Flags register, used as output of signed compare instructions
 
 // note that on AArch64 we also use this register as the output for
--- a/src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp	Thu Jun 13 12:27:29 2019 +0200
+++ b/src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -1015,7 +1015,11 @@
     if (UseCompressedOops && !wide) {
       __ decode_heap_oop(dest->as_register());
     }
-    __ verify_oop(dest->as_register());
+
+    if (!UseZGC) {
+      // Load barrier has not yet been applied, so ZGC can't verify the oop here
+      __ verify_oop(dest->as_register());
+    }
   } else if (type == T_ADDRESS && addr->disp() == oopDesc::klass_offset_in_bytes()) {
     if (UseCompressedClassPointers) {
       __ decode_klass_not_null(dest->as_register());
@@ -2869,7 +2873,11 @@
 
 
 void LIR_Assembler::leal(LIR_Opr addr, LIR_Opr dest, LIR_PatchCode patch_code, CodeEmitInfo* info) {
-  assert(patch_code == lir_patch_none, "Patch code not supported");
+  if (patch_code != lir_patch_none) {
+    deoptimize_trap(info);
+    return;
+  }
+
   __ lea(dest->as_register_lo(), as_Address(addr->as_address_ptr()));
 }
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/cpu/aarch64/gc/z/zBarrierSetAssembler_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,407 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "asm/macroAssembler.inline.hpp"
+#include "code/codeBlob.hpp"
+#include "gc/z/zBarrier.inline.hpp"
+#include "gc/z/zBarrierSet.hpp"
+#include "gc/z/zBarrierSetAssembler.hpp"
+#include "gc/z/zBarrierSetRuntime.hpp"
+#include "memory/resourceArea.hpp"
+#ifdef COMPILER1
+#include "c1/c1_LIRAssembler.hpp"
+#include "c1/c1_MacroAssembler.hpp"
+#include "gc/z/c1/zBarrierSetC1.hpp"
+#endif // COMPILER1
+
+#include "gc/z/zThreadLocalData.hpp"
+
+ZBarrierSetAssembler::ZBarrierSetAssembler() :
+    _load_barrier_slow_stub(),
+    _load_barrier_weak_slow_stub() {}
+
+#ifdef PRODUCT
+#define BLOCK_COMMENT(str) /* nothing */
+#else
+#define BLOCK_COMMENT(str) __ block_comment(str)
+#endif
+
+#undef __
+#define __ masm->
+
+void ZBarrierSetAssembler::load_at(MacroAssembler* masm,
+                                   DecoratorSet decorators,
+                                   BasicType type,
+                                   Register dst,
+                                   Address src,
+                                   Register tmp1,
+                                   Register tmp_thread) {
+  if (!ZBarrierSet::barrier_needed(decorators, type)) {
+    // Barrier not needed
+    BarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp_thread);
+    return;
+  }
+
+  // rscratch1 can be passed as src or dst, so don't use it.
+  RegSet savedRegs = RegSet::of(rscratch2, rheapbase);
+
+  Label done;
+  assert_different_registers(rheapbase, rscratch2, dst);
+  assert_different_registers(rheapbase, rscratch2, src.base());
+
+  __ push(savedRegs, sp);
+
+  // Load bad mask into scratch register.
+  __ ldr(rheapbase, address_bad_mask_from_thread(rthread));
+  __ lea(rscratch2, src);
+  __ ldr(dst, src);
+
+  // Test reference against bad mask. If mask bad, then we need to fix it up.
+  __ tst(dst, rheapbase);
+  __ br(Assembler::EQ, done);
+
+  __ enter();
+
+  __ push(RegSet::range(r0,r28) - RegSet::of(dst), sp);
+
+  if (c_rarg0 != dst) {
+    __ mov(c_rarg0, dst);
+  }
+  __ mov(c_rarg1, rscratch2);
+
+  int step = 4 * wordSize;
+  __ mov(rscratch1, -step);
+  __ sub(sp, sp, step);
+
+  for (int i = 28; i >= 4; i -= 4) {
+    __ st1(as_FloatRegister(i), as_FloatRegister(i+1), as_FloatRegister(i+2),
+        as_FloatRegister(i+3), __ T1D, Address(__ post(sp, rscratch1)));
+  }
+
+  __ call_VM_leaf(ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr(decorators), 2);
+
+  for (int i = 0; i <= 28; i += 4) {
+    __ ld1(as_FloatRegister(i), as_FloatRegister(i+1), as_FloatRegister(i+2),
+        as_FloatRegister(i+3), __ T1D, Address(__ post(sp, step)));
+  }
+
+  // Make sure dst has the return value.
+  if (dst != r0) {
+    __ mov(dst, r0);
+  }
+
+  __ pop(RegSet::range(r0,r28) - RegSet::of(dst), sp);
+  __ leave();
+
+  __ bind(done);
+
+  // Restore tmps
+  __ pop(savedRegs, sp);
+}
+
+#ifdef ASSERT
+
+void ZBarrierSetAssembler::store_at(MacroAssembler* masm,
+                                        DecoratorSet decorators,
+                                        BasicType type,
+                                        Address dst,
+                                        Register val,
+                                        Register tmp1,
+                                        Register tmp2) {
+  // Verify value
+  if (type == T_OBJECT || type == T_ARRAY) {
+    // Note that src could be noreg, which means we
+    // are storing null and can skip verification.
+    if (val != noreg) {
+      Label done;
+
+      // tmp1 and tmp2 are often set to noreg.
+      RegSet savedRegs = RegSet::of(rscratch1);
+      __ push(savedRegs, sp);
+
+      __ ldr(rscratch1, address_bad_mask_from_thread(rthread));
+      __ tst(val, rscratch1);
+      __ br(Assembler::EQ, done);
+      __ stop("Verify oop store failed");
+      __ should_not_reach_here();
+      __ bind(done);
+      __ pop(savedRegs, sp);
+    }
+  }
+
+  // Store value
+  BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2);
+}
+
+#endif // ASSERT
+
+void ZBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm,
+                                              DecoratorSet decorators,
+                                              bool is_oop,
+                                              Register src,
+                                              Register dst,
+                                              Register count,
+                                              RegSet saved_regs) {
+  if (!is_oop) {
+    // Barrier not needed
+    return;
+  }
+
+  BLOCK_COMMENT("ZBarrierSetAssembler::arraycopy_prologue {");
+
+  assert_different_registers(src, count, rscratch1);
+
+  __ pusha();
+
+  if (count == c_rarg0) {
+    if (src == c_rarg1) {
+      // exactly backwards!!
+      __ mov(rscratch1, c_rarg0);
+      __ mov(c_rarg0, c_rarg1);
+      __ mov(c_rarg1, rscratch1);
+    } else {
+      __ mov(c_rarg1, count);
+      __ mov(c_rarg0, src);
+    }
+  } else {
+    __ mov(c_rarg0, src);
+    __ mov(c_rarg1, count);
+  }
+
+  __ call_VM_leaf(ZBarrierSetRuntime::load_barrier_on_oop_array_addr(), 2);
+
+  __ popa();
+  BLOCK_COMMENT("} ZBarrierSetAssembler::arraycopy_prologue");
+}
+
+void ZBarrierSetAssembler::try_resolve_jobject_in_native(MacroAssembler* masm,
+                                                         Register jni_env,
+                                                         Register robj,
+                                                         Register tmp,
+                                                         Label& slowpath) {
+  BLOCK_COMMENT("ZBarrierSetAssembler::try_resolve_jobject_in_native {");
+
+  assert_different_registers(jni_env, robj, tmp);
+
+  // Resolve jobject
+  BarrierSetAssembler::try_resolve_jobject_in_native(masm, jni_env, robj, tmp, slowpath);
+
+  // The Address offset is too large to direct load - -784. Our range is +127, -128.
+  __ mov(tmp, (long int)(in_bytes(ZThreadLocalData::address_bad_mask_offset()) -
+      in_bytes(JavaThread::jni_environment_offset())));
+  // Load address bad mask
+  __ add(tmp, jni_env, tmp);
+  __ ldr(tmp, Address(tmp));
+
+  // Check address bad mask
+  __ tst(robj, tmp);
+  __ br(Assembler::NE, slowpath);
+
+  BLOCK_COMMENT("} ZBarrierSetAssembler::try_resolve_jobject_in_native");
+}
+
+#ifdef COMPILER1
+
+#undef __
+#define __ ce->masm()->
+
+void ZBarrierSetAssembler::generate_c1_load_barrier_test(LIR_Assembler* ce,
+                                                         LIR_Opr ref) const {
+  assert_different_registers(rheapbase, rthread, ref->as_register());
+
+  __ ldr(rheapbase, address_bad_mask_from_thread(rthread));
+  __ tst(ref->as_register(), rheapbase);
+}
+
+void ZBarrierSetAssembler::generate_c1_load_barrier_stub(LIR_Assembler* ce,
+                                                         ZLoadBarrierStubC1* stub) const {
+  // Stub entry
+  __ bind(*stub->entry());
+
+  Register ref = stub->ref()->as_register();
+  Register ref_addr = noreg;
+  Register tmp = noreg;
+
+  if (stub->tmp()->is_valid()) {
+    // Load address into tmp register
+    ce->leal(stub->ref_addr(), stub->tmp());
+    ref_addr = tmp = stub->tmp()->as_pointer_register();
+  } else {
+    // Address already in register
+    ref_addr = stub->ref_addr()->as_address_ptr()->base()->as_pointer_register();
+  }
+
+  assert_different_registers(ref, ref_addr, noreg);
+
+  // Save r0 unless it is the result or tmp register
+  // Set up SP to accomodate parameters and maybe r0..
+  if (ref != r0 && tmp != r0) {
+    __ sub(sp, sp, 32);
+    __ str(r0, Address(sp, 16));
+  } else {
+    __ sub(sp, sp, 16);
+  }
+
+  // Setup arguments and call runtime stub
+  ce->store_parameter(ref_addr, 1);
+  ce->store_parameter(ref, 0);
+
+  __ far_call(stub->runtime_stub());
+
+  // Verify result
+  __ verify_oop(r0, "Bad oop");
+
+  // Move result into place
+  if (ref != r0) {
+    __ mov(ref, r0);
+  }
+
+  // Restore r0 unless it is the result or tmp register
+  if (ref != r0 && tmp != r0) {
+    __ ldr(r0, Address(sp, 16));
+    __ add(sp, sp, 32);
+  } else {
+    __ add(sp, sp, 16);
+  }
+
+  // Stub exit
+  __ b(*stub->continuation());
+}
+
+#undef __
+#define __ sasm->
+
+void ZBarrierSetAssembler::generate_c1_load_barrier_runtime_stub(StubAssembler* sasm,
+                                                                 DecoratorSet decorators) const {
+  __ prologue("zgc_load_barrier stub", false);
+
+  // We don't use push/pop_clobbered_registers() - we need to pull out the result from r0.
+  for (int i = 0; i < 32; i +=2) {
+    __ stpd(as_FloatRegister(i), as_FloatRegister(i+1), Address(__ pre(sp,-16)));
+  }
+
+  RegSet saveRegs = RegSet::range(r0,r28) - RegSet::of(r0);
+  __ push(saveRegs, sp);
+
+  // Setup arguments
+  __ load_parameter(0, c_rarg0);
+  __ load_parameter(1, c_rarg1);
+
+  __ call_VM_leaf(ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr(decorators), 2);
+
+  __ pop(saveRegs, sp);
+
+  for (int i = 30; i >0; i -=2) {
+      __ ldpd(as_FloatRegister(i), as_FloatRegister(i+1), Address(__ post(sp, 16)));
+    }
+
+  __ epilogue();
+}
+#endif // COMPILER1
+
+#undef __
+#define __ cgen->assembler()->
+
+// Generates a register specific stub for calling
+// ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded() or
+// ZBarrierSetRuntime::load_barrier_on_weak_oop_field_preloaded().
+//
+// The raddr register serves as both input and output for this stub. When the stub is
+// called the raddr register contains the object field address (oop*) where the bad oop
+// was loaded from, which caused the slow path to be taken. On return from the stub the
+// raddr register contains the good/healed oop returned from
+// ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded() or
+// ZBarrierSetRuntime::load_barrier_on_weak_oop_field_preloaded().
+static address generate_load_barrier_stub(StubCodeGenerator* cgen, Register raddr, DecoratorSet decorators) {
+  // Don't generate stub for invalid registers
+  if (raddr == zr || raddr == r29 || raddr == r30) {
+    return NULL;
+  }
+
+  // Create stub name
+  char name[64];
+  const bool weak = (decorators & ON_WEAK_OOP_REF) != 0;
+  os::snprintf(name, sizeof(name), "zgc_load_barrier%s_stub_%s", weak ? "_weak" : "", raddr->name());
+
+  __ align(CodeEntryAlignment);
+  StubCodeMark mark(cgen, "StubRoutines", os::strdup(name, mtCode));
+  address start = __ pc();
+
+  // Save live registers
+  RegSet savedRegs = RegSet::range(r0,r18) - RegSet::of(raddr);
+
+  __ enter();
+  __ push(savedRegs, sp);
+
+  // Setup arguments
+  if (raddr != c_rarg1) {
+    __ mov(c_rarg1, raddr);
+  }
+
+  __ ldr(c_rarg0, Address(raddr));
+
+  // Call barrier function
+  __ call_VM_leaf(ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr(decorators), c_rarg0, c_rarg1);
+
+  // Move result returned in r0 to raddr, if needed
+  if (raddr != r0) {
+    __ mov(raddr, r0);
+  }
+
+  __ pop(savedRegs, sp);
+  __ leave();
+  __ ret(lr);
+
+  return start;
+}
+
+#undef __
+
+static void barrier_stubs_init_inner(const char* label, const DecoratorSet decorators, address* stub) {
+  const int nregs = 28;              // Exclude FP, XZR, SP from calculation.
+  const int code_size = nregs * 254; // Rough estimate of code size
+
+  ResourceMark rm;
+
+  CodeBuffer buf(BufferBlob::create(label, code_size));
+  StubCodeGenerator cgen(&buf);
+
+  for (int i = 0; i < nregs; i++) {
+    const Register reg = as_Register(i);
+    stub[i] = generate_load_barrier_stub(&cgen, reg, decorators);
+  }
+}
+
+void ZBarrierSetAssembler::barrier_stubs_init() {
+  barrier_stubs_init_inner("zgc_load_barrier_stubs", ON_STRONG_OOP_REF, _load_barrier_slow_stub);
+  barrier_stubs_init_inner("zgc_load_barrier_weak_stubs", ON_WEAK_OOP_REF, _load_barrier_weak_slow_stub);
+}
+
+address ZBarrierSetAssembler::load_barrier_slow_stub(Register reg) {
+  return _load_barrier_slow_stub[reg->encoding()];
+}
+
+address ZBarrierSetAssembler::load_barrier_weak_slow_stub(Register reg) {
+  return _load_barrier_weak_slow_stub[reg->encoding()];
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/cpu/aarch64/gc/z/zBarrierSetAssembler_aarch64.hpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef CPU_AARCH64_GC_Z_ZBARRIERSETASSEMBLER_AARCH64_HPP
+#define CPU_AARCH64_GC_Z_ZBARRIERSETASSEMBLER_AARCH64_HPP
+
+#ifdef COMPILER1
+class LIR_Assembler;
+class LIR_OprDesc;
+typedef LIR_OprDesc* LIR_Opr;
+class StubAssembler;
+class ZLoadBarrierStubC1;
+#endif // COMPILER1
+
+class ZBarrierSetAssembler : public ZBarrierSetAssemblerBase {
+private:
+  address _load_barrier_slow_stub[RegisterImpl::number_of_registers];
+  address _load_barrier_weak_slow_stub[RegisterImpl::number_of_registers];
+
+public:
+  ZBarrierSetAssembler();
+
+  virtual void load_at(MacroAssembler* masm,
+                       DecoratorSet decorators,
+                       BasicType type,
+                       Register dst,
+                       Address src,
+                       Register tmp1,
+                       Register tmp_thread);
+
+#ifdef ASSERT
+  virtual void store_at(MacroAssembler* masm,
+                        DecoratorSet decorators,
+                        BasicType type,
+                        Address dst,
+                        Register val,
+                        Register tmp1,
+                        Register tmp2);
+#endif // ASSERT
+
+  virtual void arraycopy_prologue(MacroAssembler* masm,
+                                  DecoratorSet decorators,
+                                  bool is_oop,
+                                  Register src,
+                                  Register dst,
+                                  Register count,
+                                  RegSet saved_regs);
+
+  virtual void try_resolve_jobject_in_native(MacroAssembler* masm,
+                                             Register jni_env,
+                                             Register robj,
+                                             Register tmp,
+                                             Label& slowpath);
+
+#ifdef COMPILER1
+  void generate_c1_load_barrier_test(LIR_Assembler* ce,
+                                     LIR_Opr ref) const;
+
+  void generate_c1_load_barrier_stub(LIR_Assembler* ce,
+                                     ZLoadBarrierStubC1* stub) const;
+
+  void generate_c1_load_barrier_runtime_stub(StubAssembler* sasm,
+                                             DecoratorSet decorators) const;
+#endif // COMPILER1
+
+  virtual void barrier_stubs_init();
+
+  address load_barrier_slow_stub(Register reg);
+  address load_barrier_weak_slow_stub(Register reg);
+};
+
+#endif // CPU_AARCH64_GC_Z_ZBARRIERSETASSEMBLER_AARCH64_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/cpu/aarch64/gc/z/z_aarch64.ad	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,174 @@
+//
+// Copyright (c) 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+// or visit www.oracle.com if you need additional information or have any
+// questions.
+//
+
+source_hpp %{
+
+#include "gc/z/c2/zBarrierSetC2.hpp"
+
+%}
+
+source %{
+
+#include "gc/z/zBarrierSetAssembler.hpp"
+
+static void z_load_barrier_slow_reg(MacroAssembler& _masm, Register dst, 
+                                    Register base, int index, int scale, 
+                                    int disp, bool weak) {
+  const address stub = weak ? ZBarrierSet::assembler()->load_barrier_weak_slow_stub(dst)
+                            : ZBarrierSet::assembler()->load_barrier_slow_stub(dst);
+
+  if (index == -1) {
+    if (disp != 0) {
+      __ lea(dst, Address(base, disp));
+    } else {
+       __ mov(dst, base);
+    }
+  } else {
+    Register index_reg = as_Register(index);
+    if (disp == 0) {
+      __ lea(dst, Address(base, index_reg, Address::lsl(scale)));
+    } else {
+      __ lea(dst, Address(base, disp));
+      __ lea(dst, Address(dst, index_reg, Address::lsl(scale)));
+    }
+  }
+
+  __ far_call(RuntimeAddress(stub));
+}
+
+%}
+
+//
+// Execute ZGC load barrier (strong) slow path
+//
+instruct loadBarrierSlowReg(iRegP dst, memory mem, rFlagsReg cr,
+    vRegD_V0 v0, vRegD_V1 v1, vRegD_V2 v2, vRegD_V3 v3, vRegD_V4 v4,
+    vRegD_V5 v5, vRegD_V6 v6, vRegD_V7 v7, vRegD_V8 v8, vRegD_V9 v9,
+    vRegD_V10 v10, vRegD_V11 v11, vRegD_V12 v12, vRegD_V13 v13, vRegD_V14 v14,
+    vRegD_V15 v15, vRegD_V16 v16, vRegD_V17 v17, vRegD_V18 v18, vRegD_V19 v19,
+    vRegD_V20 v20, vRegD_V21 v21, vRegD_V22 v22, vRegD_V23 v23, vRegD_V24 v24,
+    vRegD_V25 v25, vRegD_V26 v26, vRegD_V27 v27, vRegD_V28 v28, vRegD_V29 v29,
+    vRegD_V30 v30, vRegD_V31 v31) %{
+  match(Set dst (LoadBarrierSlowReg mem));
+  predicate(!n->as_LoadBarrierSlowReg()->is_weak());
+
+  effect(DEF dst, KILL cr,
+     KILL v0, KILL v1, KILL v2, KILL v3, KILL v4, KILL v5, KILL v6, KILL v7,
+     KILL v8, KILL v9, KILL v10, KILL v11, KILL v12, KILL v13, KILL v14,
+     KILL v15, KILL v16, KILL v17, KILL v18, KILL v19, KILL v20, KILL v21,
+     KILL v22, KILL v23, KILL v24, KILL v25, KILL v26, KILL v27, KILL v28,
+     KILL v29, KILL v30, KILL v31);
+
+  format %{"LoadBarrierSlowReg $dst, $mem" %}
+  ins_encode %{
+    z_load_barrier_slow_reg(_masm, $dst$$Register, $mem$$base$$Register,
+                            $mem$$index, $mem$$scale, $mem$$disp, false);
+  %}
+  ins_pipe(pipe_slow);
+%}
+
+//
+// Execute ZGC load barrier (weak) slow path
+//
+instruct loadBarrierWeakSlowReg(iRegP dst, memory mem, rFlagsReg cr,
+    vRegD_V0 v0, vRegD_V1 v1, vRegD_V2 v2, vRegD_V3 v3, vRegD_V4 v4,
+    vRegD_V5 v5, vRegD_V6 v6, vRegD_V7 v7, vRegD_V8 v8, vRegD_V9 v9,
+    vRegD_V10 v10, vRegD_V11 v11, vRegD_V12 v12, vRegD_V13 v13, vRegD_V14 v14,
+    vRegD_V15 v15, vRegD_V16 v16, vRegD_V17 v17, vRegD_V18 v18, vRegD_V19 v19,
+    vRegD_V20 v20, vRegD_V21 v21, vRegD_V22 v22, vRegD_V23 v23, vRegD_V24 v24,
+    vRegD_V25 v25, vRegD_V26 v26, vRegD_V27 v27, vRegD_V28 v28, vRegD_V29 v29,
+    vRegD_V30 v30, vRegD_V31 v31) %{
+  match(Set dst (LoadBarrierSlowReg mem));
+  predicate(n->as_LoadBarrierSlowReg()->is_weak());
+
+  effect(DEF dst, KILL cr,
+     KILL v0, KILL v1, KILL v2, KILL v3, KILL v4, KILL v5, KILL v6, KILL v7,
+     KILL v8, KILL v9, KILL v10, KILL v11, KILL v12, KILL v13, KILL v14,
+     KILL v15, KILL v16, KILL v17, KILL v18, KILL v19, KILL v20, KILL v21,
+     KILL v22, KILL v23, KILL v24, KILL v25, KILL v26, KILL v27, KILL v28,
+     KILL v29, KILL v30, KILL v31);
+
+  format %{"LoadBarrierWeakSlowReg $dst, $mem" %}
+  ins_encode %{
+    z_load_barrier_slow_reg(_masm, $dst$$Register, $mem$$base$$Register,
+                            $mem$$index, $mem$$scale, $mem$$disp, true);
+  %}
+  ins_pipe(pipe_slow);
+%}
+
+
+// Specialized versions of compareAndExchangeP that adds a keepalive that is consumed
+// but doesn't affect output.
+
+instruct z_compareAndExchangeP(iRegPNoSp res, indirect mem,
+                               iRegP oldval, iRegP newval, iRegP keepalive,
+                               rFlagsReg cr) %{
+  match(Set res (ZCompareAndExchangeP (Binary mem keepalive) (Binary oldval newval)));
+  ins_cost(2 * VOLATILE_REF_COST);
+  effect(TEMP_DEF res, KILL cr);
+  format %{
+    "cmpxchg $res = $mem, $oldval, $newval\t# (ptr, weak) if $mem == $oldval then $mem <-- $newval"
+  %}
+  ins_encode %{
+    __ cmpxchg($mem$$Register, $oldval$$Register, $newval$$Register,
+               Assembler::xword, /*acquire*/ false, /*release*/ true,
+               /*weak*/ false, $res$$Register);
+  %}
+  ins_pipe(pipe_slow);
+%}
+
+instruct z_compareAndSwapP(iRegINoSp res,
+                           indirect mem,
+                           iRegP oldval, iRegP newval, iRegP keepalive,
+                            rFlagsReg cr) %{
+
+  match(Set res (ZCompareAndSwapP (Binary mem keepalive) (Binary oldval newval)));
+  match(Set res (ZWeakCompareAndSwapP (Binary mem keepalive) (Binary oldval newval)));
+
+  ins_cost(2 * VOLATILE_REF_COST);
+
+  effect(KILL cr);
+
+ format %{
+    "cmpxchg $mem, $oldval, $newval\t# (ptr) if $mem == $oldval then $mem <-- $newval"
+    "cset $res, EQ\t# $res <-- (EQ ? 1 : 0)"
+ %}
+
+ ins_encode(aarch64_enc_cmpxchg(mem, oldval, newval),
+            aarch64_enc_cset_eq(res));
+
+  ins_pipe(pipe_slow);
+%}
+
+
+instruct z_get_and_setP(indirect mem, iRegP newv, iRegPNoSp prev,
+                        iRegP keepalive) %{
+  match(Set prev (ZGetAndSetP mem (Binary newv keepalive)));
+
+  ins_cost(2 * VOLATILE_REF_COST);
+  format %{ "atomic_xchg  $prev, $newv, [$mem]" %}
+  ins_encode %{
+    __ atomic_xchg($prev$$Register, $newv$$Register, as_Register($mem$$base));
+  %}
+  ins_pipe(pipe_serial);
+%}
--- a/src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp	Thu Jun 13 12:27:29 2019 +0200
+++ b/src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -46,6 +46,9 @@
 #ifdef COMPILER2
 #include "opto/runtime.hpp"
 #endif
+#if INCLUDE_ZGC
+#include "gc/z/zThreadLocalData.hpp"
+#endif
 
 #ifdef BUILTIN_SIM
 #include "../../../../../../simulator/simulator.hpp"
@@ -580,6 +583,16 @@
     // make sure object is 'reasonable'
     __ cbz(r0, exit); // if obj is NULL it is OK
 
+#if INCLUDE_ZGC
+    if (UseZGC) {
+      // Check if mask is good.
+      // verifies that ZAddressBadMask & r0 == 0
+      __ ldr(c_rarg3, Address(rthread, ZThreadLocalData::address_bad_mask_offset()));
+      __ andr(c_rarg2, r0, c_rarg3);
+      __ cbnz(c_rarg2, error);
+    }
+#endif
+
     // Check if the oop is in the right area of memory
     __ mov(c_rarg3, (intptr_t) Universe::verify_oop_mask());
     __ andr(c_rarg2, r0, c_rarg3);
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zArguments_linux_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2018, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zArguments.hpp"
+#include "runtime/globals.hpp"
+#include "runtime/globals_extension.hpp"
+#include "utilities/debug.hpp"
+
+void ZArguments::initialize_platform() {
+  // Disable class unloading - we don't support concurrent class unloading yet.
+  FLAG_SET_DEFAULT(ClassUnloading, false);
+  FLAG_SET_DEFAULT(ClassUnloadingWithConcurrentMark, false);
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,590 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zArray.inline.hpp"
+#include "gc/z/zBackingFile_linux_aarch64.hpp"
+#include "gc/z/zBackingPath_linux_aarch64.hpp"
+#include "gc/z/zErrno.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zLargePages.inline.hpp"
+#include "logging/log.hpp"
+#include "runtime/init.hpp"
+#include "runtime/os.hpp"
+#include "utilities/align.hpp"
+#include "utilities/debug.hpp"
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+//
+// Support for building on older Linux systems
+//
+
+// System calls
+#ifndef SYS_fallocate
+#define SYS_fallocate                    47
+#endif
+#ifndef SYS_memfd_create
+#define SYS_memfd_create                 279
+#endif
+
+// memfd_create(2) flags
+#ifndef MFD_CLOEXEC
+#define MFD_CLOEXEC                      0x0001U
+#endif
+#ifndef MFD_HUGETLB
+#define MFD_HUGETLB                      0x0004U
+#endif
+
+// open(2) flags
+#ifndef O_CLOEXEC
+#define O_CLOEXEC                        02000000
+#endif
+#ifndef O_TMPFILE
+#define O_TMPFILE                        (020000000 | O_DIRECTORY)
+#endif
+
+// fallocate(2) flags
+#ifndef FALLOC_FL_KEEP_SIZE
+#define FALLOC_FL_KEEP_SIZE              0x01
+#endif
+#ifndef FALLOC_FL_PUNCH_HOLE
+#define FALLOC_FL_PUNCH_HOLE             0x02
+#endif
+
+// Filesystem types, see statfs(2)
+#ifndef TMPFS_MAGIC
+#define TMPFS_MAGIC                      0x01021994
+#endif
+#ifndef HUGETLBFS_MAGIC
+#define HUGETLBFS_MAGIC                  0x958458f6
+#endif
+
+// Filesystem names
+#define ZFILESYSTEM_TMPFS                "tmpfs"
+#define ZFILESYSTEM_HUGETLBFS            "hugetlbfs"
+
+// Sysfs file for transparent huge page on tmpfs
+#define ZFILENAME_SHMEM_ENABLED          "/sys/kernel/mm/transparent_hugepage/shmem_enabled"
+
+// Java heap filename
+#define ZFILENAME_HEAP                   "java_heap"
+
+// Preferred tmpfs mount points, ordered by priority
+static const char* z_preferred_tmpfs_mountpoints[] = {
+  "/dev/shm",
+  "/run/shm",
+  NULL
+};
+
+// Preferred hugetlbfs mount points, ordered by priority
+static const char* z_preferred_hugetlbfs_mountpoints[] = {
+  "/dev/hugepages",
+  "/hugepages",
+  NULL
+};
+
+static int z_fallocate_hugetlbfs_attempts = 3;
+static bool z_fallocate_supported = true;
+
+static int z_fallocate(int fd, int mode, size_t offset, size_t length) {
+  return syscall(SYS_fallocate, fd, mode, offset, length);
+}
+
+static int z_memfd_create(const char *name, unsigned int flags) {
+  return syscall(SYS_memfd_create, name, flags);
+}
+
+ZBackingFile::ZBackingFile() :
+    _fd(-1),
+    _size(0),
+    _filesystem(0),
+    _block_size(0),
+    _available(0),
+    _initialized(false) {
+
+  // Create backing file
+  _fd = create_fd(ZFILENAME_HEAP);
+  if (_fd == -1) {
+    return;
+  }
+
+  // Get filesystem statistics
+  struct statfs buf;
+  if (fstatfs(_fd, &buf) == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to determine filesystem type for backing file (%s)", err.to_string());
+    return;
+  }
+
+  _filesystem = buf.f_type;
+  _block_size = buf.f_bsize;
+  _available = buf.f_bavail * _block_size;
+
+  // Make sure we're on a supported filesystem
+  if (!is_tmpfs() && !is_hugetlbfs()) {
+    log_error(gc)("Backing file must be located on a %s or a %s filesystem",
+                  ZFILESYSTEM_TMPFS, ZFILESYSTEM_HUGETLBFS);
+    return;
+  }
+
+  // Make sure the filesystem type matches requested large page type
+  if (ZLargePages::is_transparent() && !is_tmpfs()) {
+    log_error(gc)("-XX:+UseTransparentHugePages can only be enable when using a %s filesystem",
+                  ZFILESYSTEM_TMPFS);
+    return;
+  }
+
+  if (ZLargePages::is_transparent() && !tmpfs_supports_transparent_huge_pages()) {
+    log_error(gc)("-XX:+UseTransparentHugePages on a %s filesystem not supported by kernel",
+                  ZFILESYSTEM_TMPFS);
+    return;
+  }
+
+  if (ZLargePages::is_explicit() && !is_hugetlbfs()) {
+    log_error(gc)("-XX:+UseLargePages (without -XX:+UseTransparentHugePages) can only be enabled "
+                  "when using a %s filesystem", ZFILESYSTEM_HUGETLBFS);
+    return;
+  }
+
+  if (!ZLargePages::is_explicit() && is_hugetlbfs()) {
+    log_error(gc)("-XX:+UseLargePages must be enabled when using a %s filesystem",
+                  ZFILESYSTEM_HUGETLBFS);
+    return;
+  }
+
+  const size_t expected_block_size = is_tmpfs() ? os::vm_page_size() : os::large_page_size();
+  if (expected_block_size != _block_size) {
+    log_error(gc)("%s filesystem has unexpected block size " SIZE_FORMAT " (expected " SIZE_FORMAT ")",
+                  is_tmpfs() ? ZFILESYSTEM_TMPFS : ZFILESYSTEM_HUGETLBFS, _block_size, expected_block_size);
+    return;
+  }
+
+  // Successfully initialized
+  _initialized = true;
+}
+
+int ZBackingFile::create_mem_fd(const char* name) const {
+  // Create file name
+  char filename[PATH_MAX];
+  snprintf(filename, sizeof(filename), "%s%s", name, ZLargePages::is_explicit() ? ".hugetlb" : "");
+
+  // Create file
+  const int extra_flags = ZLargePages::is_explicit() ? MFD_HUGETLB : 0;
+  const int fd = z_memfd_create(filename, MFD_CLOEXEC | extra_flags);
+  if (fd == -1) {
+    ZErrno err;
+    log_debug(gc, init)("Failed to create memfd file (%s)",
+                        ((ZLargePages::is_explicit() && err == EINVAL) ? "Hugepages not supported" : err.to_string()));
+    return -1;
+  }
+
+  log_info(gc, init)("Heap backed by file: /memfd:%s", filename);
+
+  return fd;
+}
+
+int ZBackingFile::create_file_fd(const char* name) const {
+  const char* const filesystem = ZLargePages::is_explicit()
+                                 ? ZFILESYSTEM_HUGETLBFS
+                                 : ZFILESYSTEM_TMPFS;
+  const char** const preferred_mountpoints = ZLargePages::is_explicit()
+                                             ? z_preferred_hugetlbfs_mountpoints
+                                             : z_preferred_tmpfs_mountpoints;
+
+  // Find mountpoint
+  ZBackingPath path(filesystem, preferred_mountpoints);
+  if (path.get() == NULL) {
+    log_error(gc)("Use -XX:ZPath to specify the path to a %s filesystem", filesystem);
+    return -1;
+  }
+
+  // Try to create an anonymous file using the O_TMPFILE flag. Note that this
+  // flag requires kernel >= 3.11. If this fails we fall back to open/unlink.
+  const int fd_anon = os::open(path.get(), O_TMPFILE|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
+  if (fd_anon == -1) {
+    ZErrno err;
+    log_debug(gc, init)("Failed to create anonymous file in %s (%s)", path.get(),
+                        (err == EINVAL ? "Not supported" : err.to_string()));
+  } else {
+    // Get inode number for anonymous file
+    struct stat stat_buf;
+    if (fstat(fd_anon, &stat_buf) == -1) {
+      ZErrno err;
+      log_error(gc)("Failed to determine inode number for anonymous file (%s)", err.to_string());
+      return -1;
+    }
+
+    log_info(gc, init)("Heap backed by file: %s/#" UINT64_FORMAT, path.get(), (uint64_t)stat_buf.st_ino);
+
+    return fd_anon;
+  }
+
+  log_debug(gc, init)("Falling back to open/unlink");
+
+  // Create file name
+  char filename[PATH_MAX];
+  snprintf(filename, sizeof(filename), "%s/%s.%d", path.get(), name, os::current_process_id());
+
+  // Create file
+  const int fd = os::open(filename, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
+  if (fd == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to create file %s (%s)", filename, err.to_string());
+    return -1;
+  }
+
+  // Unlink file
+  if (unlink(filename) == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to unlink file %s (%s)", filename, err.to_string());
+    return -1;
+  }
+
+  log_info(gc, init)("Heap backed by file: %s", filename);
+
+  return fd;
+}
+
+int ZBackingFile::create_fd(const char* name) const {
+  if (ZPath == NULL) {
+    // If the path is not explicitly specified, then we first try to create a memfd file
+    // instead of looking for a tmpfd/hugetlbfs mount point. Note that memfd_create() might
+    // not be supported at all (requires kernel >= 3.17), or it might not support large
+    // pages (requires kernel >= 4.14). If memfd_create() fails, then we try to create a
+    // file on an accessible tmpfs or hugetlbfs mount point.
+    const int fd = create_mem_fd(name);
+    if (fd != -1) {
+      return fd;
+    }
+
+    log_debug(gc, init)("Falling back to searching for an accessible mount point");
+  }
+
+  return create_file_fd(name);
+}
+
+bool ZBackingFile::is_initialized() const {
+  return _initialized;
+}
+
+int ZBackingFile::fd() const {
+  return _fd;
+}
+
+size_t ZBackingFile::size() const {
+  return _size;
+}
+
+size_t ZBackingFile::available() const {
+  return _available;
+}
+
+bool ZBackingFile::is_tmpfs() const {
+  return _filesystem == TMPFS_MAGIC;
+}
+
+bool ZBackingFile::is_hugetlbfs() const {
+  return _filesystem == HUGETLBFS_MAGIC;
+}
+
+bool ZBackingFile::tmpfs_supports_transparent_huge_pages() const {
+  // If the shmem_enabled file exists and is readable then we
+  // know the kernel supports transparent huge pages for tmpfs.
+  return access(ZFILENAME_SHMEM_ENABLED, R_OK) == 0;
+}
+
+ZErrno ZBackingFile::fallocate_compat_ftruncate(size_t size) const {
+  while (ftruncate(_fd, size) == -1) {
+    if (errno != EINTR) {
+      // Failed
+      return errno;
+    }
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_compat_mmap(size_t offset, size_t length, bool touch) const {
+  // On hugetlbfs, mapping a file segment will fail immediately, without
+  // the need to touch the mapped pages first, if there aren't enough huge
+  // pages available to back the mapping.
+  void* const addr = mmap(0, length, PROT_READ|PROT_WRITE, MAP_SHARED, _fd, offset);
+  if (addr == MAP_FAILED) {
+    // Failed
+    return errno;
+  }
+
+  // Once mapped, the huge pages are only reserved. We need to touch them
+  // to associate them with the file segment. Note that we can not punch
+  // hole in file segments which only have reserved pages.
+  if (touch) {
+    char* const start = (char*)addr;
+    char* const end = start + length;
+    os::pretouch_memory(start, end, _block_size);
+  }
+
+  // Unmap again. From now on, the huge pages that were mapped are allocated
+  // to this file. There's no risk in getting SIGBUS when touching them.
+  if (munmap(addr, length) == -1) {
+    // Failed
+    return errno;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_compat_pwrite(size_t offset, size_t length) const {
+  uint8_t data = 0;
+
+  // Allocate backing memory by writing to each block
+  for (size_t pos = offset; pos < offset + length; pos += _block_size) {
+    if (pwrite(_fd, &data, sizeof(data), pos) == -1) {
+      // Failed
+      return errno;
+    }
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_fill_hole_compat(size_t offset, size_t length) {
+  // fallocate(2) is only supported by tmpfs since Linux 3.5, and by hugetlbfs
+  // since Linux 4.3. When fallocate(2) is not supported we emulate it using
+  // ftruncate/pwrite (for tmpfs) or ftruncate/mmap/munmap (for hugetlbfs).
+
+  const size_t end = offset + length;
+  if (end > _size) {
+    // Increase file size
+    const ZErrno err = fallocate_compat_ftruncate(end);
+    if (err) {
+      // Failed
+      return err;
+    }
+  }
+
+  // Allocate backing memory
+  const ZErrno err = is_hugetlbfs() ? fallocate_compat_mmap(offset, length, false /* touch */)
+                                    : fallocate_compat_pwrite(offset, length);
+  if (err) {
+    if (end > _size) {
+      // Restore file size
+      fallocate_compat_ftruncate(_size);
+    }
+
+    // Failed
+    return err;
+  }
+
+  if (end > _size) {
+    // Record new file size
+    _size = end;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_fill_hole_syscall(size_t offset, size_t length) {
+  const int mode = 0; // Allocate
+  const int res = z_fallocate(_fd, mode, offset, length);
+  if (res == -1) {
+    // Failed
+    return errno;
+  }
+
+  const size_t end = offset + length;
+  if (end > _size) {
+    // Record new file size
+    _size = end;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_fill_hole(size_t offset, size_t length) {
+  // Using compat mode is more efficient when allocating space on hugetlbfs.
+  // Note that allocating huge pages this way will only reserve them, and not
+  // associate them with segments of the file. We must guarantee that we at
+  // some point touch these segments, otherwise we can not punch hole in them.
+  if (z_fallocate_supported && !is_hugetlbfs()) {
+     const ZErrno err = fallocate_fill_hole_syscall(offset, length);
+     if (!err) {
+       // Success
+       return 0;
+     }
+
+     if (err != ENOSYS && err != EOPNOTSUPP) {
+       // Failed
+       return err;
+     }
+
+     // Not supported
+     log_debug(gc)("Falling back to fallocate() compatibility mode");
+     z_fallocate_supported = false;
+  }
+
+  return fallocate_fill_hole_compat(offset, length);
+}
+
+ZErrno ZBackingFile::fallocate_punch_hole(size_t offset, size_t length) {
+  if (is_hugetlbfs()) {
+    // We can only punch hole in pages that have been touched. Non-touched
+    // pages are only reserved, and not associated with any specific file
+    // segment. We don't know which pages have been previously touched, so
+    // we always touch them here to guarantee that we can punch hole.
+    const ZErrno err = fallocate_compat_mmap(offset, length, true /* touch */);
+    if (err) {
+      // Failed
+      return err;
+    }
+  }
+
+  const int mode = FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE;
+  if (z_fallocate(_fd, mode, offset, length) == -1) {
+    // Failed
+    return errno;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::split_and_fallocate(bool punch_hole, size_t offset, size_t length) {
+  // Try first half
+  const size_t offset0 = offset;
+  const size_t length0 = align_up(length / 2, _block_size);
+  const ZErrno err0 = fallocate(punch_hole, offset0, length0);
+  if (err0) {
+    return err0;
+  }
+
+  // Try second half
+  const size_t offset1 = offset0 + length0;
+  const size_t length1 = length - length0;
+  const ZErrno err1 = fallocate(punch_hole, offset1, length1);
+  if (err1) {
+    return err1;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate(bool punch_hole, size_t offset, size_t length) {
+  assert(is_aligned(offset, _block_size), "Invalid offset");
+  assert(is_aligned(length, _block_size), "Invalid length");
+
+  const ZErrno err = punch_hole ? fallocate_punch_hole(offset, length) : fallocate_fill_hole(offset, length);
+  if (err == EINTR && length > _block_size) {
+    // Calling fallocate(2) with a large length can take a long time to
+    // complete. When running profilers, such as VTune, this syscall will
+    // be constantly interrupted by signals. Expanding the file in smaller
+    // steps avoids this problem.
+    return split_and_fallocate(punch_hole, offset, length);
+  }
+
+  return err;
+}
+
+bool ZBackingFile::commit_inner(size_t offset, size_t length) {
+  log_trace(gc, heap)("Committing memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
+                      offset / M, (offset + length) / M, length / M);
+
+retry:
+  const ZErrno err = fallocate(false /* punch_hole */, offset, length);
+  if (err) {
+    if (err == ENOSPC && !is_init_completed() && is_hugetlbfs() && z_fallocate_hugetlbfs_attempts-- > 0) {
+      // If we fail to allocate during initialization, due to lack of space on
+      // the hugetlbfs filesystem, then we wait and retry a few times before
+      // giving up. Otherwise there is a risk that running JVMs back-to-back
+      // will fail, since there is a delay between process termination and the
+      // huge pages owned by that process being returned to the huge page pool
+      // and made available for new allocations.
+      log_debug(gc, init)("Failed to commit memory (%s), retrying", err.to_string());
+
+      // Wait and retry in one second, in the hope that huge pages will be
+      // available by then.
+      sleep(1);
+      goto retry;
+    }
+
+    // Failed
+    log_error(gc)("Failed to commit memory (%s)", err.to_string());
+    return false;
+  }
+
+  // Success
+  return true;
+}
+
+size_t ZBackingFile::commit(size_t offset, size_t length) {
+  // Try to commit the whole region
+  if (commit_inner(offset, length)) {
+    // Success
+    return length;
+  }
+
+  // Failed, try to commit as much as possible
+  size_t start = offset;
+  size_t end = offset + length;
+
+  for (;;) {
+    length = align_down((end - start) / 2, ZGranuleSize);
+    if (length < ZGranuleSize) {
+      // Done, don't commit more
+      return start - offset;
+    }
+
+    if (commit_inner(start, length)) {
+      // Success, try commit more
+      start += length;
+    } else {
+      // Failed, try commit less
+      end -= length;
+    }
+  }
+}
+
+size_t ZBackingFile::uncommit(size_t offset, size_t length) {
+  log_trace(gc, heap)("Uncommitting memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
+                      offset / M, (offset + length) / M, length / M);
+
+  const ZErrno err = fallocate(true /* punch_hole */, offset, length);
+  if (err) {
+    log_error(gc)("Failed to uncommit memory (%s)", err.to_string());
+    return 0;
+  }
+
+  return length;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.hpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGFILE_LINUX_AARCH64_HPP
+#define OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGFILE_LINUX_AARCH64_HPP
+
+#include "memory/allocation.hpp"
+
+class ZErrno;
+
+class ZBackingFile {
+private:
+  int      _fd;
+  size_t   _size;
+  uint64_t _filesystem;
+  size_t   _block_size;
+  size_t   _available;
+  bool     _initialized;
+
+  int create_mem_fd(const char* name) const;
+  int create_file_fd(const char* name) const;
+  int create_fd(const char* name) const;
+
+  bool is_tmpfs() const;
+  bool is_hugetlbfs() const;
+  bool tmpfs_supports_transparent_huge_pages() const;
+
+  ZErrno fallocate_compat_ftruncate(size_t size) const;
+  ZErrno fallocate_compat_mmap(size_t offset, size_t length, bool reserve_only) const;
+  ZErrno fallocate_compat_pwrite(size_t offset, size_t length) const;
+  ZErrno fallocate_fill_hole_compat(size_t offset, size_t length);
+  ZErrno fallocate_fill_hole_syscall(size_t offset, size_t length);
+  ZErrno fallocate_fill_hole(size_t offset, size_t length);
+  ZErrno fallocate_punch_hole(size_t offset, size_t length);
+  ZErrno split_and_fallocate(bool punch_hole, size_t offset, size_t length);
+  ZErrno fallocate(bool punch_hole, size_t offset, size_t length);
+
+  bool commit_inner(size_t offset, size_t length);
+
+public:
+  ZBackingFile();
+
+  bool is_initialized() const;
+
+  int fd() const;
+  size_t size() const;
+  size_t available() const;
+
+  size_t commit(size_t offset, size_t length);
+  size_t uncommit(size_t offset, size_t length);
+};
+
+#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGFILE_LINUX_AARCH64_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2016, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zArray.inline.hpp"
+#include "zBackingPath_linux_aarch64.hpp"
+#include "gc/z/zErrno.hpp"
+#include "logging/log.hpp"
+
+#include <stdio.h>
+#include <unistd.h>
+
+// Mount information, see proc(5) for more details.
+#define PROC_SELF_MOUNTINFO        "/proc/self/mountinfo"
+
+ZBackingPath::ZBackingPath(const char* filesystem, const char** preferred_mountpoints) {
+  if (ZPath != NULL) {
+    // Use specified path
+    _path = strdup(ZPath);
+  } else {
+    // Find suitable path
+    _path = find_mountpoint(filesystem, preferred_mountpoints);
+  }
+}
+
+ZBackingPath::~ZBackingPath() {
+  free(_path);
+  _path = NULL;
+}
+
+char* ZBackingPath::get_mountpoint(const char* line, const char* filesystem) const {
+  char* line_mountpoint = NULL;
+  char* line_filesystem = NULL;
+
+  // Parse line and return a newly allocated string containing the mount point if
+  // the line contains a matching filesystem and the mount point is accessible by
+  // the current user.
+  if (sscanf(line, "%*u %*u %*u:%*u %*s %ms %*[^-]- %ms", &line_mountpoint, &line_filesystem) != 2 ||
+      strcmp(line_filesystem, filesystem) != 0 ||
+      access(line_mountpoint, R_OK|W_OK|X_OK) != 0) {
+    // Not a matching or accessible filesystem
+    free(line_mountpoint);
+    line_mountpoint = NULL;
+  }
+
+  free(line_filesystem);
+
+  return line_mountpoint;
+}
+
+void ZBackingPath::get_mountpoints(const char* filesystem, ZArray<char*>* mountpoints) const {
+  FILE* fd = fopen(PROC_SELF_MOUNTINFO, "r");
+  if (fd == NULL) {
+    ZErrno err;
+    log_error(gc)("Failed to open %s: %s", PROC_SELF_MOUNTINFO, err.to_string());
+    return;
+  }
+
+  char* line = NULL;
+  size_t length = 0;
+
+  while (getline(&line, &length, fd) != -1) {
+    char* const mountpoint = get_mountpoint(line, filesystem);
+    if (mountpoint != NULL) {
+      mountpoints->add(mountpoint);
+    }
+  }
+
+  free(line);
+  fclose(fd);
+}
+
+void ZBackingPath::free_mountpoints(ZArray<char*>* mountpoints) const {
+  ZArrayIterator<char*> iter(mountpoints);
+  for (char* mountpoint; iter.next(&mountpoint);) {
+    free(mountpoint);
+  }
+  mountpoints->clear();
+}
+
+char* ZBackingPath::find_preferred_mountpoint(const char* filesystem,
+                                              ZArray<char*>* mountpoints,
+                                              const char** preferred_mountpoints) const {
+  // Find preferred mount point
+  ZArrayIterator<char*> iter1(mountpoints);
+  for (char* mountpoint; iter1.next(&mountpoint);) {
+    for (const char** preferred = preferred_mountpoints; *preferred != NULL; preferred++) {
+      if (!strcmp(mountpoint, *preferred)) {
+        // Preferred mount point found
+        return strdup(mountpoint);
+      }
+    }
+  }
+
+  // Preferred mount point not found
+  log_error(gc)("More than one %s filesystem found:", filesystem);
+  ZArrayIterator<char*> iter2(mountpoints);
+  for (char* mountpoint; iter2.next(&mountpoint);) {
+    log_error(gc)("  %s", mountpoint);
+  }
+
+  return NULL;
+}
+
+char* ZBackingPath::find_mountpoint(const char* filesystem, const char** preferred_mountpoints) const {
+  char* path = NULL;
+  ZArray<char*> mountpoints;
+
+  get_mountpoints(filesystem, &mountpoints);
+
+  if (mountpoints.size() == 0) {
+    // No mount point found
+    log_error(gc)("Failed to find an accessible %s filesystem", filesystem);
+  } else if (mountpoints.size() == 1) {
+    // One mount point found
+    path = strdup(mountpoints.at(0));
+  } else {
+    // More than one mount point found
+    path = find_preferred_mountpoint(filesystem, &mountpoints, preferred_mountpoints);
+  }
+
+  free_mountpoints(&mountpoints);
+
+  return path;
+}
+
+const char* ZBackingPath::get() const {
+  return _path;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.hpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2016, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGPATH_LINUX_AARCH64_HPP
+#define OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGPATH_LINUX_AARCH64_HPP
+
+#include "gc/z/zArray.hpp"
+#include "memory/allocation.hpp"
+
+class ZBackingPath : public StackObj {
+private:
+  char* _path;
+
+  char* get_mountpoint(const char* line,
+                       const char* filesystem) const;
+  void get_mountpoints(const char* filesystem,
+                       ZArray<char*>* mountpoints) const;
+  void free_mountpoints(ZArray<char*>* mountpoints) const;
+  char* find_preferred_mountpoint(const char* filesystem,
+                                  ZArray<char*>* mountpoints,
+                                  const char** preferred_mountpoints) const;
+  char* find_mountpoint(const char* filesystem,
+                        const char** preferred_mountpoints) const;
+
+public:
+  ZBackingPath(const char* filesystem, const char** preferred_mountpoints);
+  ~ZBackingPath();
+
+  const char* get() const;
+};
+
+#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGPATH_LINUX_AARCH64_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zGlobals_linux_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2017, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zUtils.inline.hpp"
+#include "runtime/globals.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+//
+// The heap can have three different layouts, depending on the max heap size.
+//
+// Address Space & Pointer Layout 1
+// --------------------------------
+//
+//  +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
+//  .                                .
+//  .                                .
+//  .                                .
+//  +--------------------------------+ 0x0000014000000000 (20TB)
+//  |         Remapped View          |
+//  +--------------------------------+ 0x0000010000000000 (16TB)
+//  |     (Reserved, but unused)     |
+//  +--------------------------------+ 0x00000c0000000000 (12TB)
+//  |         Marked1 View           |
+//  +--------------------------------+ 0x0000080000000000 (8TB)
+//  |         Marked0 View           |
+//  +--------------------------------+ 0x0000040000000000 (4TB)
+//  .                                .
+//  +--------------------------------+ 0x0000000000000000
+//
+//   6                  4 4  4 4
+//   3                  6 5  2 1                                             0
+//  +--------------------+----+-----------------------------------------------+
+//  |00000000 00000000 00|1111|11 11111111 11111111 11111111 11111111 11111111|
+//  +--------------------+----+-----------------------------------------------+
+//  |                    |    |
+//  |                    |    * 41-0 Object Offset (42-bits, 4TB address space)
+//  |                    |
+//  |                    * 45-42 Metadata Bits (4-bits)  0001 = Marked0      (Address view 4-8TB)
+//  |                                                    0010 = Marked1      (Address view 8-12TB)
+//  |                                                    0100 = Remapped     (Address view 16-20TB)
+//  |                                                    1000 = Finalizable  (Address view N/A)
+//  |
+//  * 63-46 Fixed (18-bits, always zero)
+//
+//
+// Address Space & Pointer Layout 2
+// --------------------------------
+//
+//  +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
+//  .                                .
+//  .                                .
+//  .                                .
+//  +--------------------------------+ 0x0000280000000000 (40TB)
+//  |         Remapped View          |
+//  +--------------------------------+ 0x0000200000000000 (32TB)
+//  |     (Reserved, but unused)     |
+//  +--------------------------------+ 0x0000180000000000 (24TB)
+//  |         Marked1 View           |
+//  +--------------------------------+ 0x0000100000000000 (16TB)
+//  |         Marked0 View           |
+//  +--------------------------------+ 0x0000080000000000 (8TB)
+//  .                                .
+//  +--------------------------------+ 0x0000000000000000
+//
+//   6                 4 4  4 4
+//   3                 7 6  3 2                                              0
+//  +------------------+-----+------------------------------------------------+
+//  |00000000 00000000 0|1111|111 11111111 11111111 11111111 11111111 11111111|
+//  +-------------------+----+------------------------------------------------+
+//  |                   |    |
+//  |                   |    * 42-0 Object Offset (43-bits, 8TB address space)
+//  |                   |
+//  |                   * 46-43 Metadata Bits (4-bits)  0001 = Marked0      (Address view 8-16TB)
+//  |                                                   0010 = Marked1      (Address view 16-24TB)
+//  |                                                   0100 = Remapped     (Address view 32-40TB)
+//  |                                                   1000 = Finalizable  (Address view N/A)
+//  |
+//  * 63-47 Fixed (17-bits, always zero)
+//
+//
+// Address Space & Pointer Layout 3
+// --------------------------------
+//
+//  +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
+//  .                                .
+//  .                                .
+//  .                                .
+//  +--------------------------------+ 0x0000500000000000 (80TB)
+//  |         Remapped View          |
+//  +--------------------------------+ 0x0000400000000000 (64TB)
+//  |     (Reserved, but unused)     |
+//  +--------------------------------+ 0x0000300000000000 (48TB)
+//  |         Marked1 View           |
+//  +--------------------------------+ 0x0000200000000000 (32TB)
+//  |         Marked0 View           |
+//  +--------------------------------+ 0x0000100000000000 (16TB)
+//  .                                .
+//  +--------------------------------+ 0x0000000000000000
+//
+//   6               4  4  4 4
+//   3               8  7  4 3                                               0
+//  +------------------+----+-------------------------------------------------+
+//  |00000000 00000000 |1111|1111 11111111 11111111 11111111 11111111 11111111|
+//  +------------------+----+-------------------------------------------------+
+//  |                  |    |
+//  |                  |    * 43-0 Object Offset (44-bits, 16TB address space)
+//  |                  |
+//  |                  * 47-44 Metadata Bits (4-bits)  0001 = Marked0      (Address view 16-32TB)
+//  |                                                  0010 = Marked1      (Address view 32-48TB)
+//  |                                                  0100 = Remapped     (Address view 64-80TB)
+//  |                                                  1000 = Finalizable  (Address view N/A)
+//  |
+//  * 63-48 Fixed (16-bits, always zero)
+//
+
+uintptr_t ZPlatformAddressSpaceStart() {
+  const uintptr_t first_heap_view_address = (uintptr_t)1 << (ZPlatformAddressMetadataShift() + 0);
+  const size_t min_address_offset = 0;
+  return first_heap_view_address + min_address_offset;
+}
+
+uintptr_t ZPlatformAddressSpaceEnd() {
+  const uintptr_t last_heap_view_address = (uintptr_t)1 << (ZPlatformAddressMetadataShift() + 2);
+  const size_t max_address_offset = (size_t)1 << ZPlatformAddressOffsetBits();
+  return last_heap_view_address + max_address_offset;
+}
+
+uintptr_t ZPlatformAddressReservedStart() {
+  return ZPlatformAddressSpaceStart();
+}
+
+uintptr_t ZPlatformAddressReservedEnd() {
+  return ZPlatformAddressSpaceEnd();
+}
+
+uintptr_t ZPlatformAddressBase() {
+  return 0;
+}
+
+size_t ZPlatformAddressOffsetBits() {
+  const size_t min_address_offset_bits = 42; // 4TB
+  const size_t max_address_offset_bits = 44; // 16TB
+  const size_t virtual_to_physical_ratio = 7; // 7:1
+  const size_t address_offset = ZUtils::round_up_power_of_2(MaxHeapSize * virtual_to_physical_ratio);
+  const size_t address_offset_bits = log2_intptr(address_offset);
+  return MIN2(MAX2(address_offset_bits, min_address_offset_bits), max_address_offset_bits);
+}
+
+size_t ZPlatformAddressMetadataShift() {
+  return ZPlatformAddressOffsetBits();
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zGlobals_linux_aarch64.hpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZGLOBALS_LINUX_AARCH64_HPP
+#define OS_CPU_LINUX_AARCH64_GC_Z_ZGLOBALS_LINUX_AARCH64_HPP
+
+//
+// Page Allocation Tiers
+// ---------------------
+//
+//  Page Type     Page Size     Object Size Limit     Object Alignment
+//  ------------------------------------------------------------------
+//  Small         2M            <= 265K               <MinObjAlignmentInBytes>
+//  Medium        32M           <= 4M                 4K
+//  Large         X*M           > 4M                  2M
+//  ------------------------------------------------------------------
+//
+const size_t ZPlatformGranuleSizeShift      = 21; // 2MB
+const size_t ZPlatformMaxHeapSizeShift      = 46; // 16TB
+const size_t ZPlatformNMethodDisarmedOffset = 4;
+const size_t ZPlatformCacheLineSize         = 64;
+
+uintptr_t    ZPlatformAddressSpaceStart();
+uintptr_t    ZPlatformAddressSpaceEnd();
+uintptr_t    ZPlatformAddressReservedStart();
+uintptr_t    ZPlatformAddressReservedEnd();
+uintptr_t    ZPlatformAddressBase();
+size_t       ZPlatformAddressOffsetBits();
+size_t       ZPlatformAddressMetadataShift();
+
+#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZGLOBALS_LINUX_AARCH64_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.cpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,333 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zAddress.inline.hpp"
+#include "gc/z/zBackingFile_linux_aarch64.hpp"
+#include "gc/z/zErrno.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zLargePages.inline.hpp"
+#include "gc/z/zMemory.hpp"
+#include "gc/z/zNUMA.hpp"
+#include "gc/z/zPhysicalMemory.inline.hpp"
+#include "gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp"
+#include "logging/log.hpp"
+#include "runtime/init.hpp"
+#include "runtime/os.hpp"
+#include "utilities/align.hpp"
+#include "utilities/debug.hpp"
+
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+
+//
+// Support for building on older Linux systems
+//
+
+// madvise(2) flags
+#ifndef MADV_HUGEPAGE
+#define MADV_HUGEPAGE                        14
+#endif
+
+// Proc file entry for max map mount
+#define ZFILENAME_PROC_MAX_MAP_COUNT         "/proc/sys/vm/max_map_count"
+
+bool ZPhysicalMemoryBacking::is_initialized() const {
+  return _file.is_initialized();
+}
+
+void ZPhysicalMemoryBacking::warn_available_space(size_t max) const {
+  // Note that the available space on a tmpfs or a hugetlbfs filesystem
+  // will be zero if no size limit was specified when it was mounted.
+  const size_t available = _file.available();
+  if (available == 0) {
+    // No size limit set, skip check
+    log_info(gc, init)("Available space on backing filesystem: N/A");
+    return;
+  }
+
+  log_info(gc, init)("Available space on backing filesystem: " SIZE_FORMAT "M", available / M);
+
+  // Warn if the filesystem doesn't currently have enough space available to hold
+  // the max heap size. The max heap size will be capped if we later hit this limit
+  // when trying to expand the heap.
+  if (available < max) {
+    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
+    log_warning(gc)("Not enough space available on the backing filesystem to hold the current max Java heap");
+    log_warning(gc)("size (" SIZE_FORMAT "M). Please adjust the size of the backing filesystem accordingly "
+                    "(available", max / M);
+    log_warning(gc)("space is currently " SIZE_FORMAT "M). Continuing execution with the current filesystem "
+                    "size could", available / M);
+    log_warning(gc)("lead to a premature OutOfMemoryError being thrown, due to failure to map memory.");
+  }
+}
+
+void ZPhysicalMemoryBacking::warn_max_map_count(size_t max) const {
+  const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT;
+  FILE* const file = fopen(filename, "r");
+  if (file == NULL) {
+    // Failed to open file, skip check
+    log_debug(gc, init)("Failed to open %s", filename);
+    return;
+  }
+
+  size_t actual_max_map_count = 0;
+  const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count);
+  fclose(file);
+  if (result != 1) {
+    // Failed to read file, skip check
+    log_debug(gc, init)("Failed to read %s", filename);
+    return;
+  }
+
+  // The required max map count is impossible to calculate exactly since subsystems
+  // other than ZGC are also creating memory mappings, and we have no control over that.
+  // However, ZGC tends to create the most mappings and dominate the total count.
+  // In the worst cases, ZGC will map each granule three times, i.e. once per heap view.
+  // We speculate that we need another 20% to allow for non-ZGC subsystems to map memory.
+  const size_t required_max_map_count = (max / ZGranuleSize) * 3 * 1.2;
+  if (actual_max_map_count < required_max_map_count) {
+    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
+    log_warning(gc)("The system limit on number of memory mappings per process might be too low for the given");
+    log_warning(gc)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at",
+                    max / M, filename);
+    log_warning(gc)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing execution "
+                    "with the current", required_max_map_count, actual_max_map_count);
+    log_warning(gc)("limit could lead to a fatal error, due to failure to map memory.");
+  }
+}
+
+void ZPhysicalMemoryBacking::warn_commit_limits(size_t max) const {
+  // Warn if available space is too low
+  warn_available_space(max);
+
+  // Warn if max map count is too low
+  warn_max_map_count(max);
+}
+
+bool ZPhysicalMemoryBacking::supports_uncommit() {
+  assert(!is_init_completed(), "Invalid state");
+  assert(_file.size() >= ZGranuleSize, "Invalid size");
+
+  // Test if uncommit is supported by uncommitting and then re-committing a granule
+  return commit(uncommit(ZGranuleSize)) == ZGranuleSize;
+}
+
+size_t ZPhysicalMemoryBacking::commit(size_t size) {
+  size_t committed = 0;
+
+  // Fill holes in the backing file
+  while (committed < size) {
+    size_t allocated = 0;
+    const size_t remaining = size - committed;
+    const uintptr_t start = _uncommitted.alloc_from_front_at_most(remaining, &allocated);
+    if (start == UINTPTR_MAX) {
+      // No holes to commit
+      break;
+    }
+
+    // Try commit hole
+    const size_t filled = _file.commit(start, allocated);
+    if (filled > 0) {
+      // Successful or partialy successful
+      _committed.free(start, filled);
+      committed += filled;
+    }
+    if (filled < allocated) {
+      // Failed or partialy failed
+      _uncommitted.free(start + filled, allocated - filled);
+      return committed;
+    }
+  }
+
+  // Expand backing file
+  if (committed < size) {
+    const size_t remaining = size - committed;
+    const uintptr_t start = _file.size();
+    const size_t expanded = _file.commit(start, remaining);
+    if (expanded > 0) {
+      // Successful or partialy successful
+      _committed.free(start, expanded);
+      committed += expanded;
+    }
+  }
+
+  return committed;
+}
+
+size_t ZPhysicalMemoryBacking::uncommit(size_t size) {
+  size_t uncommitted = 0;
+
+  // Punch holes in backing file
+  while (uncommitted < size) {
+    size_t allocated = 0;
+    const size_t remaining = size - uncommitted;
+    const uintptr_t start = _committed.alloc_from_back_at_most(remaining, &allocated);
+    assert(start != UINTPTR_MAX, "Allocation should never fail");
+
+    // Try punch hole
+    const size_t punched = _file.uncommit(start, allocated);
+    if (punched > 0) {
+      // Successful or partialy successful
+      _uncommitted.free(start, punched);
+      uncommitted += punched;
+    }
+    if (punched < allocated) {
+      // Failed or partialy failed
+      _committed.free(start + punched, allocated - punched);
+      return uncommitted;
+    }
+  }
+
+  return uncommitted;
+}
+
+ZPhysicalMemory ZPhysicalMemoryBacking::alloc(size_t size) {
+  assert(is_aligned(size, ZGranuleSize), "Invalid size");
+
+  ZPhysicalMemory pmem;
+
+  // Allocate segments
+  for (size_t allocated = 0; allocated < size; allocated += ZGranuleSize) {
+    const uintptr_t start = _committed.alloc_from_front(ZGranuleSize);
+    assert(start != UINTPTR_MAX, "Allocation should never fail");
+    pmem.add_segment(ZPhysicalMemorySegment(start, ZGranuleSize));
+  }
+
+  return pmem;
+}
+
+void ZPhysicalMemoryBacking::free(const ZPhysicalMemory& pmem) {
+  const size_t nsegments = pmem.nsegments();
+
+  // Free segments
+  for (size_t i = 0; i < nsegments; i++) {
+    const ZPhysicalMemorySegment& segment = pmem.segment(i);
+    _committed.free(segment.start(), segment.size());
+  }
+}
+
+void ZPhysicalMemoryBacking::map_failed(ZErrno err) const {
+  if (err == ENOMEM) {
+    fatal("Failed to map memory. Please check the system limit on number of "
+          "memory mappings allowed per process (see %s)", ZFILENAME_PROC_MAX_MAP_COUNT);
+  } else {
+    fatal("Failed to map memory (%s)", err.to_string());
+  }
+}
+
+void ZPhysicalMemoryBacking::advise_view(uintptr_t addr, size_t size, int advice) const {
+  if (madvise((void*)addr, size, advice) == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to advise on memory (advice %d, %s)", advice, err.to_string());
+  }
+}
+
+void ZPhysicalMemoryBacking::pretouch_view(uintptr_t addr, size_t size) const {
+  const size_t page_size = ZLargePages::is_explicit() ? os::large_page_size() : os::vm_page_size();
+  os::pretouch_memory((void*)addr, (void*)(addr + size), page_size);
+}
+
+void ZPhysicalMemoryBacking::map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const {
+  const size_t nsegments = pmem.nsegments();
+  size_t size = 0;
+
+  // Map segments
+  for (size_t i = 0; i < nsegments; i++) {
+    const ZPhysicalMemorySegment& segment = pmem.segment(i);
+    const uintptr_t segment_addr = addr + size;
+    const void* const res = mmap((void*)segment_addr, segment.size(), PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, _file.fd(), segment.start());
+    if (res == MAP_FAILED) {
+      ZErrno err;
+      map_failed(err);
+    }
+
+    size += segment.size();
+  }
+
+  // Advise on use of transparent huge pages before touching it
+  if (ZLargePages::is_transparent()) {
+    advise_view(addr, size, MADV_HUGEPAGE);
+  }
+
+  // NUMA interleave memory before touching it
+  ZNUMA::memory_interleave(addr, size);
+
+  // Pre-touch memory
+  if (pretouch) {
+    pretouch_view(addr, size);
+  }
+}
+
+void ZPhysicalMemoryBacking::unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const {
+  // Note that we must keep the address space reservation intact and just detach
+  // the backing memory. For this reason we map a new anonymous, non-accessible
+  // and non-reserved page over the mapping instead of actually unmapping.
+  const void* const res = mmap((void*)addr, pmem.size(), PROT_NONE, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
+  if (res == MAP_FAILED) {
+    ZErrno err;
+    map_failed(err);
+  }
+}
+
+uintptr_t ZPhysicalMemoryBacking::nmt_address(uintptr_t offset) const {
+  // From an NMT point of view we treat the first heap view (marked0) as committed
+  return ZAddress::marked0(offset);
+}
+
+void ZPhysicalMemoryBacking::map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  if (ZVerifyViews) {
+    // Map good view
+    map_view(pmem, ZAddress::good(offset), AlwaysPreTouch);
+  } else {
+    // Map all views
+    map_view(pmem, ZAddress::marked0(offset), AlwaysPreTouch);
+    map_view(pmem, ZAddress::marked1(offset), AlwaysPreTouch);
+    map_view(pmem, ZAddress::remapped(offset), AlwaysPreTouch);
+  }
+}
+
+void ZPhysicalMemoryBacking::unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  if (ZVerifyViews) {
+    // Unmap good view
+    unmap_view(pmem, ZAddress::good(offset));
+  } else {
+    // Unmap all views
+    unmap_view(pmem, ZAddress::marked0(offset));
+    unmap_view(pmem, ZAddress::marked1(offset));
+    unmap_view(pmem, ZAddress::remapped(offset));
+  }
+}
+
+void ZPhysicalMemoryBacking::debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  // Map good view
+  assert(ZVerifyViews, "Should be enabled");
+  map_view(pmem, ZAddress::good(offset), false /* pretouch */);
+}
+
+void ZPhysicalMemoryBacking::debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  // Unmap good view
+  assert(ZVerifyViews, "Should be enabled");
+  unmap_view(pmem, ZAddress::good(offset));
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp	Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_AARCH64_HPP
+#define OS_CPU_LINUX_AARCH64_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_AARCH64_HPP
+
+#include "gc/z/zBackingFile_linux_aarch64.hpp"
+#include "gc/z/zMemory.hpp"
+
+class ZErrno;
+class ZPhysicalMemory;
+
+class ZPhysicalMemoryBacking {
+private:
+  ZBackingFile   _file;
+  ZMemoryManager _committed;
+  ZMemoryManager _uncommitted;
+
+  void warn_available_space(size_t max) const;
+  void warn_max_map_count(size_t max) const;
+
+  void map_failed(ZErrno err) const;
+
+  void advise_view(uintptr_t addr, size_t size, int advice) const;
+  void pretouch_view(uintptr_t addr, size_t size) const;
+  void map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const;
+  void unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const;
+
+public:
+  bool is_initialized() const;
+
+  void warn_commit_limits(size_t max) const;
+  bool supports_uncommit();
+
+  size_t commit(size_t size);
+  size_t uncommit(size_t size);
+
+  ZPhysicalMemory alloc(size_t size);
+  void free(const ZPhysicalMemory& pmem);
+
+  uintptr_t nmt_address(uintptr_t offset) const;
+
+  void map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+  void unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+
+  void debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+  void debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+};
+
+#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_AARCH64_HPP