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 * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "asm/macroAssembler.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/vtableStubs.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "jvm.h"
34 #include "logging/log.hpp"
35 #include "memory/allocation.inline.hpp"
36 #include "os_bsd.hpp"
37 #include "os_posix.hpp"
38 #include "prims/jniFastGetField.hpp"
39 #include "prims/jvm_misc.hpp"
40 #include "runtime/arguments.hpp"
41 #include "runtime/frame.inline.hpp"
42 #include "runtime/interfaceSupport.inline.hpp"
43 #include "runtime/java.hpp"
44 #include "runtime/javaCalls.hpp"
45 #include "runtime/javaThread.hpp"
46 #include "runtime/mutexLocker.hpp"
47 #include "runtime/osThread.hpp"
48 #include "runtime/safepointMechanism.hpp"
49 #include "runtime/sharedRuntime.hpp"
50 #include "runtime/stubRoutines.hpp"
51 #include "runtime/timer.hpp"
52 #include "runtime/vm_version.hpp"
53 #include "signals_posix.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/debug.hpp"
56 #include "utilities/events.hpp"
57 #include "utilities/vmError.hpp"
58
59 // put OS-includes here
60 # include <sys/types.h>
61 # include <sys/mman.h>
62 # include <pthread.h>
63 # include <signal.h>
64 # include <errno.h>
65 # include <dlfcn.h>
66 # include <stdlib.h>
67 # include <stdio.h>
68 # include <unistd.h>
69 # include <sys/resource.h>
70 # include <sys/stat.h>
71 # include <sys/time.h>
72 # include <sys/utsname.h>
73 # include <sys/socket.h>
74 # include <sys/wait.h>
75 # include <pwd.h>
76 # include <poll.h>
77 #ifndef __OpenBSD__
78 # include <ucontext.h>
79 #endif
80
81 #if !defined(__APPLE__) && !defined(__NetBSD__)
82 # include <pthread_np.h>
83 #endif
84
85 #define SPELL_REG_SP "sp"
86 #define SPELL_REG_FP "fp"
87
88 #ifdef __APPLE__
89 // see darwin-xnu/osfmk/mach/arm/_structs.h
90
91 // 10.5 UNIX03 member name prefixes
92 #define DU3_PREFIX(s, m) __ ## s.__ ## m
93 #endif
94
95 #define context_x uc_mcontext->DU3_PREFIX(ss,x)
96 #define context_fp uc_mcontext->DU3_PREFIX(ss,fp)
97 #define context_lr uc_mcontext->DU3_PREFIX(ss,lr)
98 #define context_sp uc_mcontext->DU3_PREFIX(ss,sp)
99 #define context_pc uc_mcontext->DU3_PREFIX(ss,pc)
100 #define context_cpsr uc_mcontext->DU3_PREFIX(ss,cpsr)
101 #define context_esr uc_mcontext->DU3_PREFIX(es,esr)
102
103 #define REG_BCP context_x[22]
104
105 address os::current_stack_pointer() {
106 #if defined(__clang__) || defined(__llvm__)
107 void *sp;
108 __asm__("mov %0, " SPELL_REG_SP : "=r"(sp));
109 return (address) sp;
110 #else
111 register void *sp __asm__ (SPELL_REG_SP);
112 return (address) sp;
113 #endif
114 }
115
116 char* os::non_memory_address_word() {
117 // Must never look like an address returned by reserve_memory,
118 // even in its subfields (as defined by the CPU immediate fields,
119 // if the CPU splits constants across multiple instructions).
120
121 // the return value used in computation of Universe::non_oop_word(), which
122 // is loaded by cpu/aarch64 by MacroAssembler::movptr(Register, uintptr_t)
123 return (char*) 0xffffffffffff;
124 }
125
126 address os::Posix::ucontext_get_pc(const ucontext_t * uc) {
127 return (address)uc->context_pc;
128 }
129
130 void os::Posix::ucontext_set_pc(ucontext_t * uc, address pc) {
131 uc->context_pc = (intptr_t)pc ;
132 }
133
134 intptr_t* os::Bsd::ucontext_get_sp(const ucontext_t * uc) {
135 return (intptr_t*)uc->context_sp;
136 }
137
138 intptr_t* os::Bsd::ucontext_get_fp(const ucontext_t * uc) {
139 return (intptr_t*)uc->context_fp;
140 }
141
142 address os::fetch_frame_from_context(const void* ucVoid,
143 intptr_t** ret_sp, intptr_t** ret_fp) {
144
145 address epc;
146 const ucontext_t* uc = (const ucontext_t*)ucVoid;
147
148 if (uc != nullptr) {
149 epc = os::Posix::ucontext_get_pc(uc);
150 if (ret_sp) *ret_sp = os::Bsd::ucontext_get_sp(uc);
151 if (ret_fp) *ret_fp = os::Bsd::ucontext_get_fp(uc);
152 } else {
153 epc = nullptr;
154 if (ret_sp) *ret_sp = (intptr_t *)nullptr;
155 if (ret_fp) *ret_fp = (intptr_t *)nullptr;
156 }
157
158 return epc;
159 }
160
161 frame os::fetch_frame_from_context(const void* ucVoid) {
162 intptr_t* sp;
163 intptr_t* fp;
164 address epc = fetch_frame_from_context(ucVoid, &sp, &fp);
165 if (!is_readable_pointer(epc)) {
166 // Try to recover from calling into bad memory
167 // Assume new frame has not been set up, the same as
168 // compiled frame stack bang
169 return fetch_compiled_frame_from_context(ucVoid);
170 }
171 return frame(sp, fp, epc);
172 }
173
174 frame os::fetch_compiled_frame_from_context(const void* ucVoid) {
175 const ucontext_t* uc = (const ucontext_t*)ucVoid;
176 // In compiled code, the stack banging is performed before LR
177 // has been saved in the frame. LR is live, and SP and FP
178 // belong to the caller.
179 intptr_t* fp = os::Bsd::ucontext_get_fp(uc);
180 intptr_t* sp = os::Bsd::ucontext_get_sp(uc);
181 address pc = (address)(uc->context_lr
182 - NativeInstruction::instruction_size);
183 return frame(sp, fp, pc);
184 }
185
186 intptr_t* os::fetch_bcp_from_context(const void* ucVoid) {
187 assert(ucVoid != nullptr, "invariant");
188 const ucontext_t* uc = (const ucontext_t*)ucVoid;
189 assert(os::Posix::ucontext_is_interpreter(uc), "invariant");
190 return reinterpret_cast<intptr_t*>(uc->REG_BCP);
191 }
192
193 // JVM compiled with -fno-omit-frame-pointer, so RFP is saved on the stack.
194 frame os::get_sender_for_C_frame(frame* fr) {
195 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
196 }
197
198 NOINLINE frame os::current_frame() {
199 intptr_t *fp = *(intptr_t **)__builtin_frame_address(0);
200 frame myframe((intptr_t*)os::current_stack_pointer(),
201 (intptr_t*)fp,
202 CAST_FROM_FN_PTR(address, os::current_frame));
203 if (os::is_first_C_frame(&myframe)) {
204 // stack is not walkable
205 return frame();
206 } else {
207 return os::get_sender_for_C_frame(&myframe);
208 }
209 }
210
211 bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
212 ucontext_t* uc, JavaThread* thread) {
213 // Enable WXWrite: this function is called by the signal handler at arbitrary
214 // point of execution.
215 ThreadWXEnable wx(WXWrite, thread);
216
217 // decide if this trap can be handled by a stub
218 address stub = nullptr;
219
220 address pc = nullptr;
221
222 //%note os_trap_1
223 if (info != nullptr && uc != nullptr && thread != nullptr) {
224 pc = (address) os::Posix::ucontext_get_pc(uc);
225
226 // Handle ALL stack overflow variations here
227 if (sig == SIGSEGV || sig == SIGBUS) {
228 address addr = (address) info->si_addr;
229
230 // Make sure the high order byte is sign extended, as it may be masked away by the hardware.
231 if ((uintptr_t(addr) & (uintptr_t(1) << 55)) != 0) {
232 addr = address(uintptr_t(addr) | (uintptr_t(0xFF) << 56));
233 }
234
235 // check if fault address is within thread stack
236 if (thread->is_in_full_stack(addr)) {
237 // stack overflow
238 if (os::Posix::handle_stack_overflow(thread, addr, pc, uc, &stub)) {
239 return true; // continue
240 }
241 }
242 }
243
244 // We test if stub is already set (by the stack overflow code
245 // above) so it is not overwritten by the code that follows. This
246 // check is not required on other platforms, because on other
247 // platforms we check for SIGSEGV only or SIGBUS only, where here
248 // we have to check for both SIGSEGV and SIGBUS.
249 if (thread->thread_state() == _thread_in_Java && stub == nullptr) {
250 // Java thread running in Java code => find exception handler if any
251 // a fault inside compiled code, the interpreter, or a stub
252
253 // Handle signal from NativeJump::patch_verified_entry().
254 if ((sig == SIGILL)
255 && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
256 if (TraceTraps) {
257 tty->print_cr("trap: not_entrant");
258 }
259 stub = SharedRuntime::get_handle_wrong_method_stub();
260 } else if ((sig == SIGSEGV || sig == SIGBUS) && SafepointMechanism::is_poll_address((address)info->si_addr)) {
261 stub = SharedRuntime::get_poll_stub(pc);
262 #if defined(__APPLE__)
263 // 32-bit Darwin reports a SIGBUS for nearly all memory access exceptions.
264 // 64-bit Darwin may also use a SIGBUS (seen with compressed oops).
265 // Catching SIGBUS here prevents the implicit SIGBUS null check below from
266 // being called, so only do so if the implicit null check is not necessary.
267 } else if (sig == SIGBUS && !MacroAssembler::uses_implicit_null_check(info->si_addr)) {
268 #else
269 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
270 #endif
271 // BugId 4454115: A read from a MappedByteBuffer can fault
272 // here if the underlying file has been truncated.
273 // Do not crash the VM in such a case.
274 CodeBlob* cb = CodeCache::find_blob(pc);
275 nmethod* nm = (cb != nullptr) ? cb->as_nmethod_or_null() : nullptr;
276 bool is_unsafe_memory_access = (thread->doing_unsafe_access() && UnsafeMemoryAccess::contains_pc(pc));
277 if ((nm != nullptr && nm->has_unsafe_access()) || is_unsafe_memory_access) {
278 address next_pc = pc + NativeCall::instruction_size;
279 if (is_unsafe_memory_access) {
280 next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
281 }
282 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
283 }
284 } else if (sig == SIGILL && nativeInstruction_at(pc)->is_stop()) {
285 // A pointer to the message will have been placed in r0
286 const char *detail_msg = (const char *)(uc->uc_mcontext->DU3_PREFIX(ss,x[0]));
287 const char *msg = "stop";
288 if (TraceTraps) {
289 tty->print_cr("trap: %s: (SIGILL)", msg);
290 }
291
292 // End life with a fatal error, message and detail message and the context.
293 // Note: no need to do any post-processing here (e.g. signal chaining)
294 VMError::report_and_die(thread, uc, nullptr, 0, msg, "%s", detail_msg);
295 ShouldNotReachHere();
296
297 } else if (sig == SIGFPE &&
298 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
299 stub =
300 SharedRuntime::
301 continuation_for_implicit_exception(thread,
302 pc,
303 SharedRuntime::
304 IMPLICIT_DIVIDE_BY_ZERO);
305 } else if ((sig == SIGSEGV || sig == SIGBUS) &&
306 MacroAssembler::uses_implicit_null_check(info->si_addr)) {
307 // Determination of interpreter/vtable stub/compiled code null exception
308 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
309 }
310 } else if ((thread->thread_state() == _thread_in_vm ||
311 thread->thread_state() == _thread_in_native) &&
312 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
313 thread->doing_unsafe_access()) {
314 address next_pc = pc + NativeCall::instruction_size;
315 if (UnsafeMemoryAccess::contains_pc(pc)) {
316 next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
317 }
318 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
319 }
320
321 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
322 // and the heap gets shrunk before the field access.
323 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
324 address addr = JNI_FastGetField::find_slowcase_pc(pc);
325 if (addr != (address)-1) {
326 stub = addr;
327 }
328 }
329 }
330
331 if (stub != nullptr) {
332 // save all thread context in case we need to restore it
333 if (thread != nullptr) thread->set_saved_exception_pc(pc);
334
335 os::Posix::ucontext_set_pc(uc, stub);
336 return true;
337 }
338
339 return false; // Mute compiler
340 }
341
342 void os::Bsd::init_thread_fpu_state(void) {
343 }
344
345 ////////////////////////////////////////////////////////////////////////////////
346 // thread stack
347
348 // Minimum usable stack sizes required to get to user code. Space for
349 // HotSpot guard pages is added later.
350 size_t os::_compiler_thread_min_stack_allowed = 72 * K;
351 size_t os::_java_thread_min_stack_allowed = 72 * K;
352 size_t os::_vm_internal_thread_min_stack_allowed = 72 * K;
353
354 // return default stack size for thr_type
355 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
356 // default stack size (compiler thread needs larger stack)
357 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
358 return s;
359 }
360 void os::current_stack_base_and_size(address* base, size_t* size) {
361 address bottom;
362 #ifdef __APPLE__
363 pthread_t self = pthread_self();
364 *base = (address) pthread_get_stackaddr_np(self);
365 *size = pthread_get_stacksize_np(self);
366 bottom = *base - *size;
367 #elif defined(__OpenBSD__)
368 stack_t ss;
369 int rslt = pthread_stackseg_np(pthread_self(), &ss);
370
371 if (rslt != 0)
372 fatal("pthread_stackseg_np failed with error = %d", rslt);
373
374 *base = (address) ss.ss_sp;
375 *size = ss.ss_size;
376 bottom = *base - *size;
377 #else
378 pthread_attr_t attr;
379
380 int rslt = pthread_attr_init(&attr);
381
382 // JVM needs to know exact stack location, abort if it fails
383 if (rslt != 0)
384 fatal("pthread_attr_init failed with error = %d", rslt);
385
386 rslt = pthread_attr_get_np(pthread_self(), &attr);
387
388 if (rslt != 0)
389 fatal("pthread_attr_get_np failed with error = %d", rslt);
390
391 if (pthread_attr_getstackaddr(&attr, (void **)&bottom) != 0 ||
392 pthread_attr_getstacksize(&attr, size) != 0) {
393 fatal("Can not locate current stack attributes!");
394 }
395
396 *base = bottom + *size;
397
398 pthread_attr_destroy(&attr);
399 #endif
400 assert(os::current_stack_pointer() >= bottom &&
401 os::current_stack_pointer() < *base, "just checking");
402 }
403
404 /////////////////////////////////////////////////////////////////////////////
405 // helper functions for fatal error handler
406
407 void os::print_context(outputStream *st, const void *context) {
408 if (context == nullptr) return;
409
410 const ucontext_t *uc = (const ucontext_t*)context;
411
412 st->print_cr("Registers:");
413 st->print( " x0=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 0]);
414 st->print(" x1=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 1]);
415 st->print(" x2=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 2]);
416 st->print(" x3=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 3]);
417 st->cr();
418 st->print( " x4=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 4]);
419 st->print(" x5=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 5]);
420 st->print(" x6=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 6]);
421 st->print(" x7=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 7]);
422 st->cr();
423 st->print( " x8=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 8]);
424 st->print(" x9=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 9]);
425 st->print(" x10=" INTPTR_FORMAT, (intptr_t)uc->context_x[10]);
426 st->print(" x11=" INTPTR_FORMAT, (intptr_t)uc->context_x[11]);
427 st->cr();
428 st->print( "x12=" INTPTR_FORMAT, (intptr_t)uc->context_x[12]);
429 st->print(" x13=" INTPTR_FORMAT, (intptr_t)uc->context_x[13]);
430 st->print(" x14=" INTPTR_FORMAT, (intptr_t)uc->context_x[14]);
431 st->print(" x15=" INTPTR_FORMAT, (intptr_t)uc->context_x[15]);
432 st->cr();
433 st->print( "x16=" INTPTR_FORMAT, (intptr_t)uc->context_x[16]);
434 st->print(" x17=" INTPTR_FORMAT, (intptr_t)uc->context_x[17]);
435 st->print(" x18=" INTPTR_FORMAT, (intptr_t)uc->context_x[18]);
436 st->print(" x19=" INTPTR_FORMAT, (intptr_t)uc->context_x[19]);
437 st->cr();
438 st->print( "x20=" INTPTR_FORMAT, (intptr_t)uc->context_x[20]);
439 st->print(" x21=" INTPTR_FORMAT, (intptr_t)uc->context_x[21]);
440 st->print(" x22=" INTPTR_FORMAT, (intptr_t)uc->context_x[22]);
441 st->print(" x23=" INTPTR_FORMAT, (intptr_t)uc->context_x[23]);
442 st->cr();
443 st->print( "x24=" INTPTR_FORMAT, (intptr_t)uc->context_x[24]);
444 st->print(" x25=" INTPTR_FORMAT, (intptr_t)uc->context_x[25]);
445 st->print(" x26=" INTPTR_FORMAT, (intptr_t)uc->context_x[26]);
446 st->print(" x27=" INTPTR_FORMAT, (intptr_t)uc->context_x[27]);
447 st->cr();
448 st->print( "x28=" INTPTR_FORMAT, (intptr_t)uc->context_x[28]);
449 st->print(" fp=" INTPTR_FORMAT, (intptr_t)uc->context_fp);
450 st->print(" lr=" INTPTR_FORMAT, (intptr_t)uc->context_lr);
451 st->print(" sp=" INTPTR_FORMAT, (intptr_t)uc->context_sp);
452 st->cr();
453 st->print( "pc=" INTPTR_FORMAT, (intptr_t)uc->context_pc);
454 st->print(" cpsr=" INTPTR_FORMAT, (intptr_t)uc->context_cpsr);
455 st->cr();
456 }
457
458 void os::print_register_info(outputStream *st, const void *context, int& continuation) {
459 const int register_count = 29 /* x0-x28 */ + 3 /* fp, lr, sp */;
460 int n = continuation;
461 assert(n >= 0 && n <= register_count, "Invalid continuation value");
462 if (context == nullptr || n == register_count) {
463 return;
464 }
465
466 const ucontext_t *uc = (const ucontext_t*)context;
467 while (n < register_count) {
468 // Update continuation with next index before printing location
469 continuation = n + 1;
470 switch (n) {
471 case 29:
472 st->print(" fp="); print_location(st, uc->context_fp);
473 break;
474 case 30:
475 st->print(" lr="); print_location(st, uc->context_lr);
476 break;
477 case 31:
478 st->print(" sp="); print_location(st, uc->context_sp);
479 break;
480 default:
481 st->print("x%-2d=",n); print_location(st, uc->context_x[n]);
482 break;
483 }
484 ++n;
485 }
486 }
487
488 void os::setup_fpu() {
489 }
490
491 #ifndef PRODUCT
492 void os::verify_stack_alignment() {
493 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
494 }
495 #endif
496
497 int os::extra_bang_size_in_bytes() {
498 // AArch64 does not require the additional stack bang.
499 return 0;
500 }
501
502 void os::current_thread_enable_wx(WXMode mode) {
503 pthread_jit_write_protect_np(mode == WXExec);
504 }
505
506 static inline void atomic_copy64(const volatile void *src, volatile void *dst) {
507 *(jlong *) dst = *(const jlong *) src;
508 }
509
510 extern "C" {
511 int SpinPause() {
512 // We don't use StubRoutines::aarch64::spin_wait stub in order to
513 // avoid a costly call to os::current_thread_enable_wx() on MacOS.
514 // We should return 1 if SpinPause is implemented, and since there
515 // will be always a sequence of instructions, SpinPause will always return 1.
516 switch (VM_Version::spin_wait_desc().inst()) {
517 case SpinWait::NONE:
518 break;
519 case SpinWait::NOP:
520 asm volatile("nop" : : : "memory");
521 break;
522 case SpinWait::ISB:
523 asm volatile("isb" : : : "memory");
524 break;
525 case SpinWait::YIELD:
526 asm volatile("yield" : : : "memory");
527 break;
528 case SpinWait::SB:
529 assert(VM_Version::supports_sb(), "current CPU does not support SB instruction");
530 asm volatile(".inst 0xd50330ff" : : : "memory");
531 break;
532 #ifdef ASSERT
533 default:
534 ShouldNotReachHere();
535 #endif
536 }
537 return 1;
538 }
539
540 void _Copy_conjoint_jshorts_atomic(const jshort* from, jshort* to, size_t count) {
541 if (from > to) {
542 const jshort *end = from + count;
543 while (from < end)
544 *(to++) = *(from++);
545 }
546 else if (from < to) {
547 const jshort *end = from;
548 from += count - 1;
549 to += count - 1;
550 while (from >= end)
551 *(to--) = *(from--);
552 }
553 }
554 void _Copy_conjoint_jints_atomic(const jint* from, jint* to, size_t count) {
555 if (from > to) {
556 const jint *end = from + count;
557 while (from < end)
558 *(to++) = *(from++);
559 }
560 else if (from < to) {
561 const jint *end = from;
562 from += count - 1;
563 to += count - 1;
564 while (from >= end)
565 *(to--) = *(from--);
566 }
567 }
568
569 void _Copy_conjoint_jlongs_atomic(const jlong* from, jlong* to, size_t count) {
570 if (from > to) {
571 const jlong *end = from + count;
572 while (from < end)
573 atomic_copy64(from++, to++);
574 }
575 else if (from < to) {
576 const jlong *end = from;
577 from += count - 1;
578 to += count - 1;
579 while (from >= end)
580 atomic_copy64(from--, to--);
581 }
582 }
583
584 void _Copy_arrayof_conjoint_bytes(const HeapWord* from,
585 HeapWord* to,
586 size_t count) {
587 memmove(to, from, count);
588 }
589 void _Copy_arrayof_conjoint_jshorts(const HeapWord* from,
590 HeapWord* to,
591 size_t count) {
592 memmove(to, from, count * 2);
593 }
594 void _Copy_arrayof_conjoint_jints(const HeapWord* from,
595 HeapWord* to,
596 size_t count) {
597 memmove(to, from, count * 4);
598 }
599 void _Copy_arrayof_conjoint_jlongs(const HeapWord* from,
600 HeapWord* to,
601 size_t count) {
602 memmove(to, from, count * 8);
603 }
604 };