1 /*
2 * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2014, Red Hat Inc. 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 "asm/macroAssembler.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/vtableStubs.hpp"
30 #include "code/nativeInst.hpp"
31 #include "interpreter/interpreter.hpp"
32 #include "jvm.h"
33 #include "memory/allocation.inline.hpp"
34 #include "os_linux.hpp"
35 #include "os_posix.hpp"
36 #include "prims/jniFastGetField.hpp"
37 #include "prims/jvm_misc.hpp"
38 #include "runtime/arguments.hpp"
39 #include "runtime/frame.inline.hpp"
40 #include "runtime/interfaceSupport.inline.hpp"
41 #include "runtime/java.hpp"
42 #include "runtime/javaCalls.hpp"
43 #include "runtime/mutexLocker.hpp"
44 #include "runtime/osThread.hpp"
45 #include "runtime/safepointMechanism.hpp"
46 #include "runtime/sharedRuntime.hpp"
47 #include "runtime/stubRoutines.hpp"
48 #include "runtime/javaThread.hpp"
49 #include "runtime/timer.hpp"
50 #include "signals_posix.hpp"
51 #include "utilities/debug.hpp"
52 #include "utilities/events.hpp"
53 #include "utilities/vmError.hpp"
54
55 // put OS-includes here
56 # include <sys/types.h>
57 # include <sys/mman.h>
58 # include <pthread.h>
59 # include <signal.h>
60 # include <errno.h>
61 # include <dlfcn.h>
62 # include <stdlib.h>
63 # include <stdio.h>
64 # include <unistd.h>
65 # include <sys/resource.h>
66 # include <pthread.h>
67 # include <sys/stat.h>
68 # include <sys/time.h>
69 # include <sys/utsname.h>
70 # include <sys/socket.h>
71 # include <sys/wait.h>
72 # include <pwd.h>
73 # include <poll.h>
74 # include <ucontext.h>
75
76 #define REG_FP 29
77 #define REG_LR 30
78
79 NOINLINE address os::current_stack_pointer() {
80 return (address)__builtin_frame_address(0);
81 }
82
83 char* os::non_memory_address_word() {
84 // Must never look like an address returned by reserve_memory,
85 // even in its subfields (as defined by the CPU immediate fields,
86 // if the CPU splits constants across multiple instructions).
87
88 return (char*) 0xffffffffffff;
89 }
90
91 address os::Posix::ucontext_get_pc(const ucontext_t * uc) {
92 return (address)uc->uc_mcontext.pc;
93 }
94
95 void os::Posix::ucontext_set_pc(ucontext_t * uc, address pc) {
96 uc->uc_mcontext.pc = (intptr_t)pc;
97 }
98
99 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
100 return (intptr_t*)uc->uc_mcontext.sp;
101 }
102
103 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
104 return (intptr_t*)uc->uc_mcontext.regs[REG_FP];
105 }
106
107 address os::fetch_frame_from_context(const void* ucVoid,
108 intptr_t** ret_sp, intptr_t** ret_fp) {
109
110 address epc;
111 const ucontext_t* uc = (const ucontext_t*)ucVoid;
112
113 if (uc != nullptr) {
114 epc = os::Posix::ucontext_get_pc(uc);
115 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
116 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
117 } else {
118 epc = nullptr;
119 if (ret_sp) *ret_sp = (intptr_t *)nullptr;
120 if (ret_fp) *ret_fp = (intptr_t *)nullptr;
121 }
122
123 return epc;
124 }
125
126 frame os::fetch_frame_from_context(const void* ucVoid) {
127 intptr_t* sp;
128 intptr_t* fp;
129 address epc = fetch_frame_from_context(ucVoid, &sp, &fp);
130 if (!is_readable_pointer(epc)) {
131 // Try to recover from calling into bad memory
132 // Assume new frame has not been set up, the same as
133 // compiled frame stack bang
134 return fetch_compiled_frame_from_context(ucVoid);
135 }
136 return frame(sp, fp, epc);
137 }
138
139 frame os::fetch_compiled_frame_from_context(const void* ucVoid) {
140 const ucontext_t* uc = (const ucontext_t*)ucVoid;
141 // In compiled code, the stack banging is performed before LR
142 // has been saved in the frame. LR is live, and SP and FP
143 // belong to the caller.
144 intptr_t* fp = os::Linux::ucontext_get_fp(uc);
145 intptr_t* sp = os::Linux::ucontext_get_sp(uc);
146 address pc = (address)(uc->uc_mcontext.regs[REG_LR]
147 - NativeInstruction::instruction_size);
148 return frame(sp, fp, pc);
149 }
150
151 // By default, gcc always saves frame pointer rfp on this stack. This
152 // may get turned off by -fomit-frame-pointer.
153 // The "Procedure Call Standard for the Arm 64-bit Architecture" doesn't
154 // specify a location for the frame record within a stack frame (6.4.6).
155 // GCC currently chooses to save it at the top of the frame (lowest address).
156 // This means that using fr->sender_sp() to set the caller's frame _unextended_sp,
157 // as we do in x86, is wrong. Using fr->link() instead only makes sense for
158 // native frames. Setting a correct value for _unextended_sp is important
159 // if this value is later used to get that frame's caller. This will happen
160 // if we end up calling frame::sender_for_compiled_frame(), which will be the
161 // case if the _pc is associated with a CodeBlob that has a _frame_size > 0
162 // (nmethod, runtime stub, safepoint stub, etc).
163 frame os::get_sender_for_C_frame(frame* fr) {
164 address pc = fr->sender_pc();
165 CodeBlob* cb = CodeCache::find_blob(pc);
166 bool use_codeblob = cb != nullptr && cb->frame_size() > 0;
167 assert(!use_codeblob || !Interpreter::contains(pc), "should not be an interpreter frame");
168 intptr_t* sender_sp = use_codeblob ? (fr->link() + frame::metadata_words - cb->frame_size()) : fr->link();
169 return frame(sender_sp, sender_sp, fr->link(), pc, cb, true /* allow_cb_null */);
170 }
171
172 NOINLINE frame os::current_frame() {
173 intptr_t *fp = *(intptr_t **)__builtin_frame_address(0);
174 frame myframe((intptr_t*)os::current_stack_pointer(),
175 (intptr_t*)fp,
176 CAST_FROM_FN_PTR(address, os::current_frame));
177 if (os::is_first_C_frame(&myframe)) {
178 // stack is not walkable
179 return frame();
180 } else {
181 return os::get_sender_for_C_frame(&myframe);
182 }
183 }
184
185 bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
186 ucontext_t* uc, JavaThread* thread) {
187
188 /*
189 NOTE: does not seem to work on linux.
190 if (info == nullptr || info->si_code <= 0 || info->si_code == SI_NOINFO) {
191 // can't decode this kind of signal
192 info = nullptr;
193 } else {
194 assert(sig == info->si_signo, "bad siginfo");
195 }
196 */
197 // decide if this trap can be handled by a stub
198 address stub = nullptr;
199
200 address pc = nullptr;
201
202 //%note os_trap_1
203 if (info != nullptr && uc != nullptr && thread != nullptr) {
204 pc = (address) os::Posix::ucontext_get_pc(uc);
205
206 address addr = (address) info->si_addr;
207
208 // Make sure the high order byte is sign extended, as it may be masked away by the hardware.
209 if ((uintptr_t(addr) & (uintptr_t(1) << 55)) != 0) {
210 addr = address(uintptr_t(addr) | (uintptr_t(0xFF) << 56));
211 }
212
213 // Handle ALL stack overflow variations here
214 if (sig == SIGSEGV) {
215 // check if fault address is within thread stack
216 if (thread->is_in_full_stack(addr)) {
217 if (os::Posix::handle_stack_overflow(thread, addr, pc, uc, &stub)) {
218 return true; // continue
219 }
220 }
221 }
222
223 if (thread->thread_state() == _thread_in_Java) {
224 // Java thread running in Java code => find exception handler if any
225 // a fault inside compiled code, the interpreter, or a stub
226
227 // Handle signal from NativeJump::patch_verified_entry().
228 if ((sig == SIGILL || sig == SIGTRAP)
229 && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
230 if (TraceTraps) {
231 tty->print_cr("trap: not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
232 }
233 stub = SharedRuntime::get_handle_wrong_method_stub();
234 } else if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
235 stub = SharedRuntime::get_poll_stub(pc);
236 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
237 // BugId 4454115: A read from a MappedByteBuffer can fault
238 // here if the underlying file has been truncated.
239 // Do not crash the VM in such a case.
240 CodeBlob* cb = CodeCache::find_blob(pc);
241 nmethod* nm = (cb != nullptr) ? cb->as_nmethod_or_null() : nullptr;
242 bool is_unsafe_memory_access = (thread->doing_unsafe_access() && UnsafeMemoryAccess::contains_pc(pc));
243 if ((nm != nullptr && nm->has_unsafe_access()) || is_unsafe_memory_access) {
244 address next_pc = pc + NativeCall::instruction_size;
245 if (is_unsafe_memory_access) {
246 next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
247 }
248 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
249 }
250 } else if (sig == SIGILL && nativeInstruction_at(pc)->is_stop()) {
251 // Pull a pointer to the error message out of the instruction
252 // stream.
253 const uint64_t *detail_msg_ptr
254 = (uint64_t*)(pc + NativeInstruction::instruction_size);
255 const char *detail_msg = (const char *)*detail_msg_ptr;
256 const char *msg = "stop";
257 if (TraceTraps) {
258 tty->print_cr("trap: %s: (SIGILL)", msg);
259 }
260
261 // End life with a fatal error, message and detail message and the context.
262 // Note: no need to do any post-processing here (e.g. signal chaining)
263 VMError::report_and_die(thread, uc, nullptr, 0, msg, "%s", detail_msg);
264
265 ShouldNotReachHere();
266
267 }
268 else
269
270 if (sig == SIGFPE &&
271 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
272 stub =
273 SharedRuntime::
274 continuation_for_implicit_exception(thread,
275 pc,
276 SharedRuntime::
277 IMPLICIT_DIVIDE_BY_ZERO);
278 } else if (sig == SIGSEGV &&
279 MacroAssembler::uses_implicit_null_check((void*)addr)) {
280 // Determination of interpreter/vtable stub/compiled code null exception
281 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
282 }
283 } else if ((thread->thread_state() == _thread_in_vm ||
284 thread->thread_state() == _thread_in_native) &&
285 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
286 thread->doing_unsafe_access()) {
287 address next_pc = pc + NativeCall::instruction_size;
288 if (UnsafeMemoryAccess::contains_pc(pc)) {
289 next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
290 }
291 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
292 }
293
294 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
295 // and the heap gets shrunk before the field access.
296 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
297 address addr = JNI_FastGetField::find_slowcase_pc(pc);
298 if (addr != (address)-1) {
299 stub = addr;
300 }
301 }
302 }
303
304 if (stub != nullptr) {
305 // save all thread context in case we need to restore it
306 if (thread != nullptr) thread->set_saved_exception_pc(pc);
307
308 os::Posix::ucontext_set_pc(uc, stub);
309 return true;
310 }
311
312 return false; // Mute compiler
313 }
314
315 void os::Linux::init_thread_fpu_state(void) {
316 }
317
318 int os::Linux::get_fpu_control_word(void) {
319 return 0;
320 }
321
322 void os::Linux::set_fpu_control_word(int fpu_control) {
323 }
324
325 ////////////////////////////////////////////////////////////////////////////////
326 // thread stack
327
328 // Minimum usable stack sizes required to get to user code. Space for
329 // HotSpot guard pages is added later.
330 size_t os::_compiler_thread_min_stack_allowed = 72 * K;
331 size_t os::_java_thread_min_stack_allowed = 72 * K;
332 size_t os::_vm_internal_thread_min_stack_allowed = 72 * K;
333
334 // return default stack size for thr_type
335 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
336 // default stack size (compiler thread needs larger stack)
337 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
338 return s;
339 }
340
341 /////////////////////////////////////////////////////////////////////////////
342 // helper functions for fatal error handler
343
344 void os::print_context(outputStream *st, const void *context) {
345 if (context == nullptr) return;
346
347 const ucontext_t *uc = (const ucontext_t*)context;
348
349 st->print_cr("Registers:");
350 for (int r = 0; r < 31; r++) {
351 st->print_cr( "R%d=" INTPTR_FORMAT, r, (uintptr_t)uc->uc_mcontext.regs[r]);
352 }
353 st->cr();
354 }
355
356 void os::print_register_info(outputStream *st, const void *context, int& continuation) {
357 const int register_count = 31 /* r0-r30 */;
358 int n = continuation;
359 assert(n >= 0 && n <= register_count, "Invalid continuation value");
360 if (context == nullptr || n == register_count) {
361 return;
362 }
363
364 const ucontext_t *uc = (const ucontext_t*)context;
365 while (n < register_count) {
366 // Update continuation with next index before printing location
367 continuation = n + 1;
368 st->print("R%-2d=", n);
369 print_location(st, uc->uc_mcontext.regs[n]);
370 ++n;
371 }
372 }
373
374 void os::setup_fpu() {
375 }
376
377 #ifndef PRODUCT
378 void os::verify_stack_alignment() {
379 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
380 }
381 #endif
382
383 int os::extra_bang_size_in_bytes() {
384 // AArch64 does not require the additional stack bang.
385 return 0;
386 }
387
388 static inline void atomic_copy64(const volatile void *src, volatile void *dst) {
389 *(jlong *) dst = *(const jlong *) src;
390 }
391
392 extern "C" {
393 int SpinPause() {
394 using spin_wait_func_ptr_t = void (*)();
395 spin_wait_func_ptr_t func = CAST_TO_FN_PTR(spin_wait_func_ptr_t, StubRoutines::aarch64::spin_wait());
396 assert(func != nullptr, "StubRoutines::aarch64::spin_wait must not be null.");
397 (*func)();
398 // If StubRoutines::aarch64::spin_wait consists of only a RET,
399 // SpinPause can be considered as implemented. There will be a sequence
400 // of instructions for:
401 // - call of SpinPause
402 // - load of StubRoutines::aarch64::spin_wait stub pointer
403 // - indirect call of the stub
404 // - return from the stub
405 // - return from SpinPause
406 // So '1' always is returned.
407 return 1;
408 }
409
410 void _Copy_conjoint_jshorts_atomic(const jshort* from, jshort* to, size_t count) {
411 if (from > to) {
412 const jshort *end = from + count;
413 while (from < end)
414 *(to++) = *(from++);
415 }
416 else if (from < to) {
417 const jshort *end = from;
418 from += count - 1;
419 to += count - 1;
420 while (from >= end)
421 *(to--) = *(from--);
422 }
423 }
424 void _Copy_conjoint_jints_atomic(const jint* from, jint* to, size_t count) {
425 if (from > to) {
426 const jint *end = from + count;
427 while (from < end)
428 *(to++) = *(from++);
429 }
430 else if (from < to) {
431 const jint *end = from;
432 from += count - 1;
433 to += count - 1;
434 while (from >= end)
435 *(to--) = *(from--);
436 }
437 }
438
439 void _Copy_conjoint_jlongs_atomic(const jlong* from, jlong* to, size_t count) {
440 if (from > to) {
441 const jlong *end = from + count;
442 while (from < end)
443 atomic_copy64(from++, to++);
444 }
445 else if (from < to) {
446 const jlong *end = from;
447 from += count - 1;
448 to += count - 1;
449 while (from >= end)
450 atomic_copy64(from--, to--);
451 }
452 }
453
454 void _Copy_arrayof_conjoint_bytes(const HeapWord* from,
455 HeapWord* to,
456 size_t count) {
457 memmove(to, from, count);
458 }
459 void _Copy_arrayof_conjoint_jshorts(const HeapWord* from,
460 HeapWord* to,
461 size_t count) {
462 memmove(to, from, count * 2);
463 }
464 void _Copy_arrayof_conjoint_jints(const HeapWord* from,
465 HeapWord* to,
466 size_t count) {
467 memmove(to, from, count * 4);
468 }
469 void _Copy_arrayof_conjoint_jlongs(const HeapWord* from,
470 HeapWord* to,
471 size_t count) {
472 memmove(to, from, count * 8);
473 }
474 };