1 /*
2 * Copyright (c) 2018, 2022, Oracle and/or its affiliates. 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 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/nativeInst.hpp"
28 #include "gc/shared/barrierSetNMethod.hpp"
29 #include "logging/log.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "runtime/javaThread.hpp"
32 #include "runtime/sharedRuntime.hpp"
33 #include "utilities/align.hpp"
34 #include "utilities/debug.hpp"
35 #include "utilities/formatBuffer.hpp"
36 #include "utilities/macros.hpp"
37 #if INCLUDE_JVMCI
38 #include "jvmci/jvmciRuntime.hpp"
39 #endif
40
41 class NativeNMethodCmpBarrier: public NativeInstruction {
42 public:
43 #ifdef _LP64
44 enum Intel_specific_constants {
45 instruction_code = 0x81,
46 instruction_size = 8,
47 imm_offset = 4,
48 instruction_rex_prefix = Assembler::REX | Assembler::REX_B,
49 instruction_modrm = 0x7f // [r15 + offset]
50 };
51 #else
52 enum Intel_specific_constants {
53 instruction_code = 0x81,
54 instruction_size = 7,
55 imm_offset = 2,
56 instruction_modrm = 0x3f // [rdi]
57 };
58 #endif
59
60 address instruction_address() const { return addr_at(0); }
61 address immediate_address() const { return addr_at(imm_offset); }
62
63 jint get_immediate() const { return int_at(imm_offset); }
64 void set_immediate(jint imm) { set_int_at(imm_offset, imm); }
65 bool check_barrier(err_msg& msg) const;
66 void verify() const {
67 #ifdef ASSERT
68 err_msg msg("%s", "");
69 assert(check_barrier(msg), "%s", msg.buffer());
70 #endif
71 }
72 };
73
74 #ifdef _LP64
75 bool NativeNMethodCmpBarrier::check_barrier(err_msg& msg) const {
76 // Only require 4 byte alignment
77 if (((uintptr_t) instruction_address()) & 0x3) {
78 msg.print("Addr: " INTPTR_FORMAT " not properly aligned", p2i(instruction_address()));
79 return false;
80 }
81
82 int prefix = ubyte_at(0);
83 if (prefix != instruction_rex_prefix) {
84 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x expected 0x%x", p2i(instruction_address()), prefix, instruction_rex_prefix);
85 return false;
86 }
87
88 int inst = ubyte_at(1);
89 if (inst != instruction_code) {
90 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x expected 0x%x", p2i(instruction_address()), inst, instruction_code);
91 return false;
92 }
93
94 int modrm = ubyte_at(2);
95 if (modrm != instruction_modrm) {
96 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x expected mod/rm 0x%x", p2i(instruction_address()), modrm, instruction_modrm);
97 return false;
98 }
99 return true;
100 }
101 #else
102 bool NativeNMethodCmpBarrier::check_barrier(err_msg& msg) const {
103 if (((uintptr_t) instruction_address()) & 0x3) {
104 msg.print("Addr: " INTPTR_FORMAT " not properly aligned", p2i(instruction_address()));
105 return false;
106 }
107
108 int inst = ubyte_at(0);
109 if (inst != instruction_code) {
110 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x", p2i(instruction_address()),
111 inst);
112 return false;
113 }
114
115 int modrm = ubyte_at(1);
116 if (modrm != instruction_modrm) {
117 msg.print("Addr: " INTPTR_FORMAT " mod/rm: 0x%x", p2i(instruction_address()),
118 modrm);
119 return false;
120 }
121 return true;
122 }
123 #endif // _LP64
124
125 void BarrierSetNMethod::deoptimize(nmethod* nm, address* return_address_ptr) {
126 /*
127 * [ callers frame ]
128 * [ callers return address ] <- callers rsp
129 * [ callers rbp ] <- callers rbp
130 * [ callers frame slots ]
131 * [ return_address ] <- return_address_ptr
132 * [ cookie ] <- used to write the new rsp (callers rsp)
133 * [ stub rbp ]
134 * [ stub stuff ]
135 */
136
137 address* stub_rbp = return_address_ptr - 2;
138 address* callers_rsp = return_address_ptr + nm->frame_size(); /* points to callers return_address now */
139 address* callers_rbp = callers_rsp - 1; // 1 to move to the callers return address, 1 more to move to the rbp
140 address* cookie = return_address_ptr - 1;
141
142 LogTarget(Trace, nmethod, barrier) out;
143 if (out.is_enabled()) {
144 JavaThread* jth = JavaThread::current();
145 ResourceMark mark;
146 log_trace(nmethod, barrier)("deoptimize(nmethod: %p, return_addr: %p, osr: %d, thread: %p(%s), making rsp: %p) -> %p",
147 nm, (address *) return_address_ptr, nm->is_osr_method(), jth,
148 jth->name(), callers_rsp, nm->verified_entry_point());
149 }
150
151 assert(nm->frame_size() >= 3, "invariant");
152 assert(*cookie == (address) -1, "invariant");
153
154 // Preserve caller rbp.
155 *stub_rbp = *callers_rbp;
156
157 // At the cookie address put the callers rsp.
158 *cookie = (address) callers_rsp; // should point to the return address
159
160 // In the slot that used to be the callers rbp we put the address that our stub needs to jump to at the end.
161 // Overwriting the caller rbp should be okay since our stub rbp has the same value.
162 address* jmp_addr_ptr = callers_rbp;
163 *jmp_addr_ptr = SharedRuntime::get_handle_wrong_method_stub();
164 }
165
166 // This is the offset of the entry barrier from where the frame is completed.
167 // If any code changes between the end of the verified entry where the entry
168 // barrier resides, and the completion of the frame, then
169 // NativeNMethodCmpBarrier::verify() will immediately complain when it does
170 // not find the expected native instruction at this offset, which needs updating.
171 // Note that this offset is invariant of PreserveFramePointer.
172 static int entry_barrier_offset(nmethod* nm) {
173 #ifdef _LP64
174 if (nm->is_compiled_by_c2()) {
175 return -14;
176 } else {
177 return -15;
178 }
179 #else
180 return -18;
181 #endif
182 }
183
184 static NativeNMethodCmpBarrier* native_nmethod_barrier(nmethod* nm) {
185 address barrier_address;
186 #if INCLUDE_JVMCI
187 if (nm->is_compiled_by_jvmci()) {
188 barrier_address = nm->code_begin() + nm->jvmci_nmethod_data()->nmethod_entry_patch_offset();
189 } else
190 #endif
191 {
192 barrier_address = nm->code_begin() + nm->frame_complete_offset() + entry_barrier_offset(nm);
193 }
194
195 NativeNMethodCmpBarrier* barrier = reinterpret_cast<NativeNMethodCmpBarrier*>(barrier_address);
196 barrier->verify();
197 return barrier;
198 }
199
200 void BarrierSetNMethod::set_guard_value(nmethod* nm, int value) {
201 if (!supports_entry_barrier(nm)) {
202 return;
203 }
204
205 NativeNMethodCmpBarrier* cmp = native_nmethod_barrier(nm);
206 cmp->set_immediate(value);
207 }
208
209 int BarrierSetNMethod::guard_value(nmethod* nm) {
210 if (!supports_entry_barrier(nm)) {
211 return disarmed_guard_value();
212 }
213
214 NativeNMethodCmpBarrier* cmp = native_nmethod_barrier(nm);
215 return cmp->get_immediate();
216 }
217
218
219 #if INCLUDE_JVMCI
220 bool BarrierSetNMethod::verify_barrier(nmethod* nm, err_msg& msg) {
221 NativeNMethodCmpBarrier* barrier = native_nmethod_barrier(nm);
222 return barrier->check_barrier(msg);
223 }
224 #endif