1 /*
2 * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2020, 2021, Huawei Technologies Co., Ltd. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "code/codeCache.hpp"
28 #include "code/nativeInst.hpp"
29 #include "gc/shared/barrierSetNMethod.hpp"
30 #include "logging/log.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "runtime/sharedRuntime.hpp"
33 #include "runtime/registerMap.hpp"
34 #include "runtime/thread.hpp"
35 #include "utilities/align.hpp"
36 #include "utilities/debug.hpp"
37
38 class NativeNMethodBarrier: public NativeInstruction {
39 address instruction_address() const { return addr_at(0); }
40
41 int *guard_addr() {
42 /* auipc + lwu + fence + lwu + beq + lui + addi + slli + addi + slli + jalr + j */
43 return reinterpret_cast<int*>(instruction_address() + 12 * 4);
44 }
45
46 public:
47 int get_value() {
48 return Atomic::load_acquire(guard_addr());
49 }
50
51 void set_value(int value) {
52 Atomic::release_store(guard_addr(), value);
53 }
54
55 void verify() const;
56 };
57
58 // Store the instruction bitmask, bits and name for checking the barrier.
59 struct CheckInsn {
60 uint32_t mask;
61 uint32_t bits;
62 const char *name;
63 };
64
65 static const struct CheckInsn barrierInsn[] = {
66 { 0x00000fff, 0x00000297, "auipc t0, 0 "},
67 { 0x000fffff, 0x0002e283, "lwu t0, 48(t0) "},
68 { 0xffffffff, 0x0aa0000f, "fence ir, ir "},
69 { 0x000fffff, 0x000be303, "lwu t1, 112(xthread)"},
70 { 0x01fff07f, 0x00628063, "beq t0, t1, skip "},
71 { 0x00000fff, 0x000002b7, "lui t0, imm0 "},
72 { 0x000fffff, 0x00028293, "addi t0, t0, imm1 "},
73 { 0xffffffff, 0x00b29293, "slli t0, t0, 11 "},
74 { 0x000fffff, 0x00028293, "addi t0, t0, imm2 "},
75 { 0xffffffff, 0x00629293, "slli t0, t0, 6 "},
76 { 0x000fffff, 0x000280e7, "jalr ra, imm3(t0) "},
77 { 0x00000fff, 0x0000006f, "j skip "}
78 /* guard: */
79 /* 32bit nmethod guard value */
80 /* skip: */
81 };
82
83 // The encodings must match the instructions emitted by
84 // BarrierSetAssembler::nmethod_entry_barrier. The matching ignores the specific
85 // register numbers and immediate values in the encoding.
86 void NativeNMethodBarrier::verify() const {
87 intptr_t addr = (intptr_t) instruction_address();
88 for(unsigned int i = 0; i < sizeof(barrierInsn)/sizeof(struct CheckInsn); i++ ) {
89 uint32_t inst = *((uint32_t*) addr);
90 if ((inst & barrierInsn[i].mask) != barrierInsn[i].bits) {
91 tty->print_cr("Addr: " INTPTR_FORMAT " Code: 0x%x", addr, inst);
92 fatal("not an %s instruction.", barrierInsn[i].name);
93 }
94 addr += 4;
95 }
96 }
97
98
99 /* We're called from an nmethod when we need to deoptimize it. We do
100 this by throwing away the nmethod's frame and jumping to the
101 ic_miss stub. This looks like there has been an IC miss at the
102 entry of the nmethod, so we resolve the call, which will fall back
103 to the interpreter if the nmethod has been unloaded. */
104 void BarrierSetNMethod::deoptimize(nmethod* nm, address* return_address_ptr) {
105
106 typedef struct {
107 intptr_t *sp; intptr_t *fp; address ra; address pc;
108 } frame_pointers_t;
109
110 frame_pointers_t *new_frame = (frame_pointers_t *)(return_address_ptr - 5);
111
112 JavaThread *thread = JavaThread::current();
113 RegisterMap reg_map(thread, false);
114 frame frame = thread->last_frame();
115
116 assert(frame.is_compiled_frame() || frame.is_native_frame(), "must be");
117 assert(frame.cb() == nm, "must be");
118 frame = frame.sender(®_map);
119
120 LogTarget(Trace, nmethod, barrier) out;
121 if (out.is_enabled()) {
122 ResourceMark mark;
123 log_trace(nmethod, barrier)("deoptimize(nmethod: %s(%p), return_addr: %p, osr: %d, thread: %p(%s), making rsp: %p) -> %p",
124 nm->method()->name_and_sig_as_C_string(),
125 nm, *(address *) return_address_ptr, nm->is_osr_method(), thread,
126 thread->name(), frame.sp(), nm->verified_entry_point());
127 }
128
129 new_frame->sp = frame.sp();
130 new_frame->fp = frame.fp();
131 new_frame->ra = frame.pc();
132 new_frame->pc = SharedRuntime::get_handle_wrong_method_stub();
133 }
134
135 // This is the offset of the entry barrier from where the frame is completed.
136 // If any code changes between the end of the verified entry where the entry
137 // barrier resides, and the completion of the frame, then
138 // NativeNMethodCmpBarrier::verify() will immediately complain when it does
139 // not find the expected native instruction at this offset, which needs updating.
140 // Note that this offset is invariant of PreserveFramePointer.
141
142 // see BarrierSetAssembler::nmethod_entry_barrier
143 // auipc + lwu + fence + lwu + beq + movptr_with_offset(5 instructions) + jalr + j + int32
144 static const int entry_barrier_offset = -4 * 13;
145
146 static NativeNMethodBarrier* native_nmethod_barrier(nmethod* nm) {
147 address barrier_address = nm->code_begin() + nm->frame_complete_offset() + entry_barrier_offset;
148 NativeNMethodBarrier* barrier = reinterpret_cast<NativeNMethodBarrier*>(barrier_address);
149 debug_only(barrier->verify());
150 return barrier;
151 }
152
153 void BarrierSetNMethod::disarm(nmethod* nm) {
154 if (!supports_entry_barrier(nm)) {
155 return;
156 }
157
158 // Disarms the nmethod guard emitted by BarrierSetAssembler::nmethod_entry_barrier.
159 NativeNMethodBarrier* barrier = native_nmethod_barrier(nm);
160
161 barrier->set_value(disarmed_value());
162 }
163
164 bool BarrierSetNMethod::is_armed(nmethod* nm) {
165 if (!supports_entry_barrier(nm)) {
166 return false;
167 }
168
169 NativeNMethodBarrier* barrier = native_nmethod_barrier(nm);
170 return barrier->get_value() != disarmed_value();
171 }