1 /*
2 * Copyright (c) 2018, 2025, 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 "code/codeCache.hpp"
26 #include "code/nativeInst.hpp"
27 #include "gc/shared/barrierSetNMethod.hpp"
28 #include "logging/log.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "runtime/javaThread.hpp"
31 #include "runtime/sharedRuntime.hpp"
32 #include "utilities/align.hpp"
33 #include "utilities/debug.hpp"
34 #include "utilities/formatBuffer.hpp"
35 #include "utilities/macros.hpp"
36 #if INCLUDE_JVMCI
37 #include "jvmci/jvmciRuntime.hpp"
38 #endif
39
40 class NativeNMethodCmpBarrier: public NativeInstruction {
41 public:
42 #ifdef _LP64
43 enum Intel_specific_constants {
44 instruction_code = 0x81,
45 instruction_size = 8,
46 imm_offset = 4,
47 instruction_rex_prefix = Assembler::REX | Assembler::REX_B,
48 instruction_modrm = 0x7f // [r15 + offset]
49 };
50 #else
51 enum Intel_specific_constants {
52 instruction_code = 0x81,
53 instruction_size = 7,
54 imm_offset = 2,
55 instruction_modrm = 0x3f // [rdi]
56 };
57 #endif
58
59 address instruction_address() const { return addr_at(0); }
60 address immediate_address() const { return addr_at(imm_offset); }
61
62 jint get_immediate() const { return int_at(imm_offset); }
63 void set_immediate(jint imm) { set_int_at(imm_offset, imm); }
64 bool check_barrier(err_msg& msg) const;
65 void verify() const {
66 #ifdef ASSERT
67 err_msg msg("%s", "");
68 assert(check_barrier(msg), "%s", msg.buffer());
69 #endif
70 }
71 };
72
73 #ifdef _LP64
74 bool NativeNMethodCmpBarrier::check_barrier(err_msg& msg) const {
75 // Only require 4 byte alignment
76 if (((uintptr_t) instruction_address()) & 0x3) {
77 msg.print("Addr: " INTPTR_FORMAT " not properly aligned", p2i(instruction_address()));
78 return false;
79 }
80
81 int prefix = ubyte_at(0);
82 if (prefix != instruction_rex_prefix) {
83 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x expected 0x%x", p2i(instruction_address()), prefix, instruction_rex_prefix);
84 return false;
85 }
86
87 int inst = ubyte_at(1);
88 if (inst != instruction_code) {
89 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x expected 0x%x", p2i(instruction_address()), inst, instruction_code);
90 return false;
91 }
92
93 int modrm = ubyte_at(2);
94 if (modrm != instruction_modrm) {
95 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x expected mod/rm 0x%x", p2i(instruction_address()), modrm, instruction_modrm);
96 return false;
97 }
98 return true;
99 }
100 #else
101 bool NativeNMethodCmpBarrier::check_barrier(err_msg& msg) const {
102 if (((uintptr_t) instruction_address()) & 0x3) {
103 msg.print("Addr: " INTPTR_FORMAT " not properly aligned", p2i(instruction_address()));
104 return false;
105 }
106
107 int inst = ubyte_at(0);
108 if (inst != instruction_code) {
109 msg.print("Addr: " INTPTR_FORMAT " Code: 0x%x", p2i(instruction_address()),
110 inst);
111 return false;
112 }
113
114 int modrm = ubyte_at(1);
115 if (modrm != instruction_modrm) {
116 msg.print("Addr: " INTPTR_FORMAT " mod/rm: 0x%x", p2i(instruction_address()),
117 modrm);
118 return false;
119 }
120 return true;
121 }
122 #endif // _LP64
123
124 void BarrierSetNMethod::deoptimize(nmethod* nm, address* return_address_ptr) {
125 /*
126 * [ callers frame ]
127 * [ callers return address ] <- callers rsp
128 * [ callers rbp ] <- callers rbp
129 * [ callers frame slots ]
130 * [ return_address ] <- return_address_ptr
131 * [ cookie ] <- used to write the new rsp (callers rsp)
132 * [ stub rbp ]
133 * [ stub stuff ]
134 */
135
136 address* stub_rbp = return_address_ptr - 2;
137 address* callers_rsp = return_address_ptr + nm->frame_size(); /* points to callers return_address now */
138 address* callers_rbp = callers_rsp - 1; // 1 to move to the callers return address, 1 more to move to the rbp
139 address* cookie = return_address_ptr - 1;
140
141 LogTarget(Trace, nmethod, barrier) out;
142 if (out.is_enabled()) {
143 JavaThread* jth = JavaThread::current();
144 ResourceMark mark;
145 log_trace(nmethod, barrier)("deoptimize(nmethod: %p, return_addr: %p, osr: %d, thread: %p(%s), making rsp: %p) -> %p",
146 nm, (address *) return_address_ptr, nm->is_osr_method(), jth,
147 jth->name(), callers_rsp, nm->verified_entry_point());
148 }
149
150 assert(nm->frame_size() >= 3, "invariant");
151 assert(*cookie == (address) -1, "invariant");
152
153 // Preserve caller rbp.
154 *stub_rbp = *callers_rbp;
155
156 // At the cookie address put the callers rsp.
157 *cookie = (address) callers_rsp; // should point to the return address
158
159 // In the slot that used to be the callers rbp we put the address that our stub needs to jump to at the end.
160 // Overwriting the caller rbp should be okay since our stub rbp has the same value.
161 address* jmp_addr_ptr = callers_rbp;
162 *jmp_addr_ptr = SharedRuntime::get_handle_wrong_method_stub();
163 }
164
165 // This is the offset of the entry barrier from where the frame is completed.
166 // If any code changes between the end of the verified entry where the entry
167 // barrier resides, and the completion of the frame, then
168 // NativeNMethodCmpBarrier::verify() will immediately complain when it does
169 // not find the expected native instruction at this offset, which needs updating.
170 // Note that this offset is invariant of PreserveFramePointer.
171 static int entry_barrier_offset(nmethod* nm) {
172 #ifdef _LP64
173 if (nm->is_compiled_by_c2()) {
174 return -14;
175 } else {
176 return -15;
177 }
178 #else
179 return -18;
180 #endif
181 }
182
183 static NativeNMethodCmpBarrier* native_nmethod_barrier(nmethod* nm) {
184 address barrier_address;
185 #if INCLUDE_JVMCI
186 if (nm->is_compiled_by_jvmci()) {
187 barrier_address = nm->code_begin() + nm->jvmci_nmethod_data()->nmethod_entry_patch_offset();
188 } else
189 #endif
190 {
191 barrier_address = nm->code_begin() + nm->frame_complete_offset() + entry_barrier_offset(nm);
192 }
193
194 NativeNMethodCmpBarrier* barrier = reinterpret_cast<NativeNMethodCmpBarrier*>(barrier_address);
195 barrier->verify();
196 return barrier;
197 }
198
199 static void set_immediate(nmethod* nm, jint val) {
200 NativeNMethodCmpBarrier* cmp1 = native_nmethod_barrier(nm);
201 cmp1->set_immediate(val);
202
203 if (!nm->is_osr_method() && nm->method()->has_scalarized_args()) {
204 // nmethods with scalarized arguments have multiple entry points that each have an own nmethod entry barrier
205 assert(nm->verified_entry_point() != nm->verified_inline_entry_point(), "scalarized entry point not found");
206 address method_body = nm->is_compiled_by_c1() ? nm->verified_inline_entry_point() : nm->verified_entry_point();
207 address entry_point2 = nm->is_compiled_by_c1() ? nm->verified_entry_point() : nm->verified_inline_entry_point();
208
209 int barrier_offset = reinterpret_cast<address>(cmp1) - method_body;
210 NativeNMethodCmpBarrier* cmp2 = reinterpret_cast<NativeNMethodCmpBarrier*>(entry_point2 + barrier_offset);
211 assert(cmp1 != cmp2, "sanity");
212 debug_only(cmp2->verify());
213 cmp2->set_immediate(val);
214
215 if (method_body != nm->verified_inline_ro_entry_point() && entry_point2 != nm->verified_inline_ro_entry_point()) {
216 NativeNMethodCmpBarrier* cmp3 = reinterpret_cast<NativeNMethodCmpBarrier*>(nm->verified_inline_ro_entry_point() + barrier_offset);
217 assert(cmp1 != cmp3 && cmp2 != cmp3, "sanity");
218 debug_only(cmp3->verify());
219 cmp3->set_immediate(val);
220 }
221 }
222 }
223
224 void BarrierSetNMethod::set_guard_value(nmethod* nm, int value) {
225 if (!supports_entry_barrier(nm)) {
226 return;
227 }
228
229 set_immediate(nm, value);
230 }
231
232 int BarrierSetNMethod::guard_value(nmethod* nm) {
233 if (!supports_entry_barrier(nm)) {
234 return disarmed_guard_value();
235 }
236
237 NativeNMethodCmpBarrier* cmp = native_nmethod_barrier(nm);
238 return cmp->get_immediate();
239 }
240
241
242 #if INCLUDE_JVMCI
243 bool BarrierSetNMethod::verify_barrier(nmethod* nm, err_msg& msg) {
244 NativeNMethodCmpBarrier* barrier = native_nmethod_barrier(nm);
245 return barrier->check_barrier(msg);
246 }
247 #endif