1 /*
2 * Copyright (c) 2019, 2022, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25
26 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
27 #include "gc/shenandoah/shenandoahBarrierSetNMethod.hpp"
28 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
29 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahLock.hpp"
32 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
33 #include "gc/shenandoah/shenandoahStackChunkGCData.hpp"
34 #include "gc/shenandoah/shenandoahStackWatermark.hpp"
35 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
36 #include "memory/iterator.hpp"
37 #include "memory/resourceArea.hpp"
38 #include "runtime/icache.hpp"
39 #include "runtime/threadWXSetters.inline.hpp"
40
41 bool ShenandoahBarrierSetNMethod::nmethod_entry_barrier(nmethod* nm) {
42 if (!is_armed(nm)) {
43 // Some other thread got here first and healed the oops.
44 // No need to continue. We only need to sync up the changes done by others.
45 cross_modify_fence();
46 return true;
47 }
48
49 ShenandoahNMethodLock* lock = ShenandoahNMethod::lock_for_nmethod(nm);
50 assert(lock != nullptr, "Must be");
51 ShenandoahNMethodLocker locker(lock);
52
53 if (!is_armed(nm)) {
54 // Some other thread managed to complete while we were waiting for lock.
55 // No need to continue. We only need to sync up the changes done by others.
56 cross_modify_fence();
57 return true;
58 }
59
60 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
61
62 if (nm->is_unloading()) {
63 // We don't need to take the lock when unlinking nmethods from
64 // the Method, because it is only concurrently unlinked by
65 // the entry barrier, which acquires the per nmethod lock.
66 nm->unlink_from_method();
67
68 // We can end up calling nmethods that are unloading
69 // since we clear compiled ICs lazily. Returning false
70 // will re-resolve the call and update the compiled IC.
71 return false;
72 }
73
74 // Handle oops and jumps.
75 {
76 ICacheInvalidationContext icic;
77 ShenandoahNMethod::handle_oops(nm, &icic);
78 ShenandoahNMethod::handle_jumps(nm, &icic);
79 }
80
81 // CodeCache unloading support
82 nm->mark_as_maybe_on_stack();
83
84 // Disarm
85 ShenandoahNMethod::disarm_nmethod(nm);
86
87 // Paranoia: sync up the changes done by others, even though we did a lot ourselves.
88 cross_modify_fence();
89
90 return true;
91 }
92
93 void ShenandoahBarrierSetNMethod::cross_modify_fence() {
94 // For Java threads that can execute the nmethod code, we need to sync up
95 // the code changes with current execution. Non-Java threads do not execute
96 // the code, and thus do not need this fence. (VM has VerifyCrossModifyFence code
97 // that barfs when we attempt to do this.)
98 if (Thread::current()->is_Java_thread()) {
99 OrderAccess::cross_modify_fence();
100 }
101 }
102
103 void ShenandoahBarrierSetNMethod::finalize_relocations(nmethod* nm) {
104 RelocIterator iter(nm);
105 while (iter.next()) {
106 if (iter.type() == relocInfo::patchable_barrier_type) {
107 patchable_barrier_Relocation* r = iter.patchable_barrier_reloc();
108 if (!r->is_target_offset_resolved()) {
109 address pc = r->addr();
110 address target = ShenandoahBarrierSetAssembler::parse_jump_address(pc);
111 r->set_target_offset(target - nm->code_begin());
112 } else {
113 // Already set. This is likely nmethod relocation, so just trust
114 // the existing relocation data.
115 }
116 }
117 }
118 }
119
120 void ShenandoahBarrierSetNMethod::arm_all_nmethods() {
121 BarrierSetNMethod::arm_all_nmethods();
122
123 // Arming should also activate stack watermark machinery.
124 // See ShenandoahNMethod::patch_jump.
125 ShenandoahStackWatermark::change_epoch_id();
126
127 // All currently allocated stack chunks now need to be fixed up.
128 ShenandoahStackChunkGCData::change_epoch_id();
129 }