# HG changeset patch
# User zgu
# Date 1571192543 14400
# Node ID 55fe0d93bdd39463196651b79c69f2d333e35046
# Parent  e0bb6b38a6f6d8cd44e21061ebbe83ebf94f1ced
8229919: Support JNI Critical functions in object pinning API on x86_32 platforms
Reviewed-by: rkennke, adinn

diff -r e0bb6b38a6f6 -r 55fe0d93bdd3 src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp
--- a/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp	Tue Oct 15 21:33:54 2019 +0000
+++ b/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp	Tue Oct 15 22:22:23 2019 -0400
@@ -1304,6 +1304,97 @@
   }
 }
 
+// Registers need to be saved for runtime call
+static Register caller_saved_registers[] = {
+  rcx, rdx, rsi, rdi
+};
+
+// Save caller saved registers except r1 and r2
+static void save_registers_except(MacroAssembler* masm, Register r1, Register r2) {
+  int reg_len = (int)(sizeof(caller_saved_registers) / sizeof(Register));
+  for (int index = 0; index < reg_len; index ++) {
+    Register this_reg = caller_saved_registers[index];
+    if (this_reg != r1 && this_reg != r2) {
+      __ push(this_reg);
+    }
+  }
+}
+
+// Restore caller saved registers except r1 and r2
+static void restore_registers_except(MacroAssembler* masm, Register r1, Register r2) {
+  int reg_len = (int)(sizeof(caller_saved_registers) / sizeof(Register));
+  for (int index = reg_len - 1; index >= 0; index --) {
+    Register this_reg = caller_saved_registers[index];
+    if (this_reg != r1 && this_reg != r2) {
+      __ pop(this_reg);
+    }
+  }
+}
+
+// Pin object, return pinned object or null in rax
+static void gen_pin_object(MacroAssembler* masm,
+                           Register thread, VMRegPair reg) {
+  __ block_comment("gen_pin_object {");
+
+  Label is_null;
+  Register tmp_reg = rax;
+  VMRegPair tmp(tmp_reg->as_VMReg());
+  if (reg.first()->is_stack()) {
+    // Load the arg up from the stack
+    simple_move32(masm, reg, tmp);
+    reg = tmp;
+  } else {
+    __ movl(tmp_reg, reg.first()->as_Register());
+  }
+  __ testptr(reg.first()->as_Register(), reg.first()->as_Register());
+  __ jccb(Assembler::equal, is_null);
+
+  // Save registers that may be used by runtime call
+  Register arg = reg.first()->is_Register() ? reg.first()->as_Register() : noreg;
+  save_registers_except(masm, arg, thread);
+
+  __ call_VM_leaf(
+    CAST_FROM_FN_PTR(address, SharedRuntime::pin_object),
+    thread, reg.first()->as_Register());
+
+  // Restore saved registers
+  restore_registers_except(masm, arg, thread);
+
+  __ bind(is_null);
+  __ block_comment("} gen_pin_object");
+}
+
+// Unpin object
+static void gen_unpin_object(MacroAssembler* masm,
+                             Register thread, VMRegPair reg) {
+  __ block_comment("gen_unpin_object {");
+  Label is_null;
+
+  // temp register
+  __ push(rax);
+  Register tmp_reg = rax;
+  VMRegPair tmp(tmp_reg->as_VMReg());
+
+  simple_move32(masm, reg, tmp);
+
+  __ testptr(rax, rax);
+  __ jccb(Assembler::equal, is_null);
+
+  // Save registers that may be used by runtime call
+  Register arg = reg.first()->is_Register() ? reg.first()->as_Register() : noreg;
+  save_registers_except(masm, arg, thread);
+
+  __ call_VM_leaf(
+    CAST_FROM_FN_PTR(address, SharedRuntime::unpin_object),
+    thread, rax);
+
+  // Restore saved registers
+  restore_registers_except(masm, arg, thread);
+  __ bind(is_null);
+  __ pop(rax);
+  __ block_comment("} gen_unpin_object");
+}
+
 // Check GCLocker::needs_gc and enter the runtime if it's true.  This
 // keeps a new JNI critical region from starting until a GC has been
 // forced.  Save down any oops in registers and describe them in an
@@ -1837,7 +1928,7 @@
 
   __ get_thread(thread);
 
-  if (is_critical_native) {
+  if (is_critical_native && !Universe::heap()->supports_object_pinning()) {
     check_needs_gc_for_critical_native(masm, thread, stack_slots, total_c_args, total_in_args,
                                        oop_handle_offset, oop_maps, in_regs, in_sig_bt);
   }
@@ -1875,6 +1966,11 @@
   //
   OopMap* map = new OopMap(stack_slots * 2, 0 /* arg_slots*/);
 
+  // Inbound arguments that need to be pinned for critical natives
+  GrowableArray<int> pinned_args(total_in_args);
+  // Current stack slot for storing register based array argument
+  int pinned_slot = oop_handle_offset;
+
   // Mark location of rbp,
   // map->set_callee_saved(VMRegImpl::stack2reg( stack_slots - 2), stack_slots * 2, 0, rbp->as_VMReg());
 
@@ -1886,7 +1982,28 @@
     switch (in_sig_bt[i]) {
       case T_ARRAY:
         if (is_critical_native) {
-          unpack_array_argument(masm, in_regs[i], in_elem_bt[i], out_regs[c_arg + 1], out_regs[c_arg]);
+          VMRegPair in_arg = in_regs[i];
+          if (Universe::heap()->supports_object_pinning()) {
+            // gen_pin_object handles save and restore
+            // of any clobbered registers
+            gen_pin_object(masm, thread, in_arg);
+            pinned_args.append(i);
+
+            // rax has pinned array
+            VMRegPair result_reg(rax->as_VMReg());
+            if (!in_arg.first()->is_stack()) {
+              assert(pinned_slot <= stack_slots, "overflow");
+              simple_move32(masm, result_reg, VMRegImpl::stack2reg(pinned_slot));
+              pinned_slot += VMRegImpl::slots_per_word;
+            } else {
+              // Write back pinned value, it will be used to unpin this argument
+              __ movptr(Address(rbp, reg2offset_in(in_arg.first())), result_reg.first()->as_Register());
+            }
+            // We have the array in register, use it
+            in_arg = result_reg;
+          }
+
+          unpack_array_argument(masm, in_arg, in_elem_bt[i], out_regs[c_arg + 1], out_regs[c_arg]);
           c_arg++;
           break;
         }
@@ -2079,6 +2196,26 @@
   default       : ShouldNotReachHere();
   }
 
+  // unpin pinned arguments
+  pinned_slot = oop_handle_offset;
+  if (pinned_args.length() > 0) {
+    // save return value that may be overwritten otherwise.
+    save_native_result(masm, ret_type, stack_slots);
+    for (int index = 0; index < pinned_args.length(); index ++) {
+      int i = pinned_args.at(index);
+      assert(pinned_slot <= stack_slots, "overflow");
+      if (!in_regs[i].first()->is_stack()) {
+        int offset = pinned_slot * VMRegImpl::stack_slot_size;
+        __ movl(in_regs[i].first()->as_Register(), Address(rsp, offset));
+        pinned_slot += VMRegImpl::slots_per_word;
+      }
+      // gen_pin_object handles save and restore
+      // of any other clobbered registers
+      gen_unpin_object(masm, thread, in_regs[i]);
+    }
+    restore_native_result(masm, ret_type, stack_slots);
+  }
+
   // Switch thread to "native transition" state before reading the synchronization state.
   // This additional state is necessary because reading and testing the synchronization
   // state is not atomic w.r.t. GC, as this scenario demonstrates:
diff -r e0bb6b38a6f6 -r 55fe0d93bdd3 test/hotspot/jtreg/gc/CriticalNativeArgs.java
--- a/test/hotspot/jtreg/gc/CriticalNativeArgs.java	Tue Oct 15 21:33:54 2019 +0000
+++ b/test/hotspot/jtreg/gc/CriticalNativeArgs.java	Tue Oct 15 22:22:23 2019 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates.
+ * Copyright (c) 2018, 2019, Red Hat, Inc. and/or its affiliates.
  *
  * 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
@@ -28,7 +28,7 @@
  * @key gc
  * @bug 8199868
  * @library /
- * @requires (os.arch =="x86_64" | os.arch == "amd64") & vm.gc.Epsilon & !vm.graal.enabled
+ * @requires (os.arch =="x86_64" | os.arch == "amd64" | os.arch=="x86" | os.arch=="i386") & vm.gc.Epsilon & !vm.graal.enabled
  * @summary test argument unpacking nmethod wrapper of critical native method
  * @run main/othervm/native -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -Xcomp -Xmx256M -XX:+CriticalJNINatives gc.CriticalNativeArgs
  */
@@ -38,7 +38,7 @@
  * @key gc
  * @bug 8199868
  * @library /
- * @requires (os.arch =="x86_64" | os.arch == "amd64") & vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires (os.arch =="x86_64" | os.arch == "amd64" | os.arch=="x86" | os.arch=="i386") & vm.gc.Shenandoah & !vm.graal.enabled
  * @summary test argument unpacking nmethod wrapper of critical native method
  * @run main/othervm/native -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive    -XX:+ShenandoahDegeneratedGC -Xcomp -Xmx512M -XX:+CriticalJNINatives gc.CriticalNativeArgs
  * @run main/othervm/native -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive    -XX:-ShenandoahDegeneratedGC -Xcomp -Xmx512M -XX:+CriticalJNINatives gc.CriticalNativeArgs
diff -r e0bb6b38a6f6 -r 55fe0d93bdd3 test/hotspot/jtreg/gc/stress/CriticalNativeStress.java
--- a/test/hotspot/jtreg/gc/stress/CriticalNativeStress.java	Tue Oct 15 21:33:54 2019 +0000
+++ b/test/hotspot/jtreg/gc/stress/CriticalNativeStress.java	Tue Oct 15 22:22:23 2019 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates.
+ * Copyright (c) 2018, 2019, Red Hat, Inc. and/or its affiliates.
  *
  * 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
@@ -31,7 +31,7 @@
  * @key gc
  * @bug 8199868
  * @library /
- * @requires (os.arch =="x86_64" | os.arch == "amd64") & vm.gc.Epsilon & !vm.graal.enabled
+ * @requires (os.arch =="x86_64" | os.arch == "amd64" | os.arch=="x86" | os.arch=="i386") & vm.gc.Epsilon & !vm.graal.enabled
  * @summary test argument pinning by nmethod wrapper of critical native method
  * @run main/othervm/native -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -Xcomp -Xmx1G -XX:+CriticalJNINatives gc.stress.CriticalNativeStress
  */
@@ -41,7 +41,7 @@
  * @key gc
  * @bug 8199868
  * @library /
- * @requires (os.arch =="x86_64" | os.arch == "amd64") & vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires (os.arch =="x86_64" | os.arch == "amd64" | os.arch=="x86" | os.arch=="i386") & vm.gc.Shenandoah & !vm.graal.enabled
  * @summary test argument pinning by nmethod wrapper of critical native method
  * @run main/othervm/native -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive    -XX:-ShenandoahDegeneratedGC -Xcomp -Xmx512M -XX:+CriticalJNINatives gc.stress.CriticalNativeStress
  * @run main/othervm/native -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive    -XX:+ShenandoahDegeneratedGC -Xcomp -Xmx512M -XX:+CriticalJNINatives gc.stress.CriticalNativeStress