1 /*
2 * Copyright (c) 1999, 2024, 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 // no precompiled headers
28 #include "asm/macroAssembler.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/vtableStubs.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "jvm.h"
35 #include "logging/log.hpp"
36 #include "memory/allocation.inline.hpp"
37 #include "os_bsd.hpp"
38 #include "os_posix.hpp"
39 #include "prims/jniFastGetField.hpp"
40 #include "prims/jvm_misc.hpp"
41 #include "runtime/arguments.hpp"
42 #include "runtime/frame.inline.hpp"
43 #include "runtime/interfaceSupport.inline.hpp"
44 #include "runtime/java.hpp"
45 #include "runtime/javaCalls.hpp"
46 #include "runtime/javaThread.hpp"
47 #include "runtime/mutexLocker.hpp"
48 #include "runtime/osThread.hpp"
49 #include "runtime/safepointMechanism.hpp"
50 #include "runtime/sharedRuntime.hpp"
51 #include "runtime/stubRoutines.hpp"
52 #include "runtime/timer.hpp"
53 #include "signals_posix.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/events.hpp"
56 #include "utilities/vmError.hpp"
57
58 // put OS-includes here
59 # include <sys/types.h>
60 # include <sys/mman.h>
61 # include <pthread.h>
62 # include <signal.h>
63 # include <errno.h>
64 # include <dlfcn.h>
65 # include <stdlib.h>
66 # include <stdio.h>
67 # include <unistd.h>
68 # include <sys/resource.h>
69 # include <sys/stat.h>
70 # include <sys/time.h>
71 # include <sys/utsname.h>
72 # include <sys/socket.h>
73 # include <sys/wait.h>
74 # include <pwd.h>
75 # include <poll.h>
76 #ifndef __OpenBSD__
77 # include <ucontext.h>
78 #endif
79
80 #if !defined(__APPLE__) && !defined(__NetBSD__)
81 # include <pthread_np.h>
82 #endif
83
84 #define SPELL_REG_SP "sp"
85 #define SPELL_REG_FP "fp"
86
87 #ifdef __APPLE__
88 // see darwin-xnu/osfmk/mach/arm/_structs.h
89
90 // 10.5 UNIX03 member name prefixes
91 #define DU3_PREFIX(s, m) __ ## s.__ ## m
92 #endif
93
94 #define context_x uc_mcontext->DU3_PREFIX(ss,x)
95 #define context_fp uc_mcontext->DU3_PREFIX(ss,fp)
96 #define context_lr uc_mcontext->DU3_PREFIX(ss,lr)
97 #define context_sp uc_mcontext->DU3_PREFIX(ss,sp)
98 #define context_pc uc_mcontext->DU3_PREFIX(ss,pc)
99 #define context_cpsr uc_mcontext->DU3_PREFIX(ss,cpsr)
100 #define context_esr uc_mcontext->DU3_PREFIX(es,esr)
101
102 address os::current_stack_pointer() {
103 #if defined(__clang__) || defined(__llvm__)
104 void *sp;
105 __asm__("mov %0, " SPELL_REG_SP : "=r"(sp));
106 return (address) sp;
107 #else
108 register void *sp __asm__ (SPELL_REG_SP);
109 return (address) sp;
110 #endif
111 }
112
113 char* os::non_memory_address_word() {
114 // Must never look like an address returned by reserve_memory,
115 // even in its subfields (as defined by the CPU immediate fields,
116 // if the CPU splits constants across multiple instructions).
117
118 // the return value used in computation of Universe::non_oop_word(), which
119 // is loaded by cpu/aarch64 by MacroAssembler::movptr(Register, uintptr_t)
120 return (char*) 0xffffffffffff;
121 }
122
123 address os::Posix::ucontext_get_pc(const ucontext_t * uc) {
124 return (address)uc->context_pc;
125 }
126
127 void os::Posix::ucontext_set_pc(ucontext_t * uc, address pc) {
128 uc->context_pc = (intptr_t)pc ;
129 }
130
131 intptr_t* os::Bsd::ucontext_get_sp(const ucontext_t * uc) {
132 return (intptr_t*)uc->context_sp;
133 }
134
135 intptr_t* os::Bsd::ucontext_get_fp(const ucontext_t * uc) {
136 return (intptr_t*)uc->context_fp;
137 }
138
139 address os::fetch_frame_from_context(const void* ucVoid,
140 intptr_t** ret_sp, intptr_t** ret_fp) {
141
142 address epc;
143 const ucontext_t* uc = (const ucontext_t*)ucVoid;
144
145 if (uc != nullptr) {
146 epc = os::Posix::ucontext_get_pc(uc);
147 if (ret_sp) *ret_sp = os::Bsd::ucontext_get_sp(uc);
148 if (ret_fp) *ret_fp = os::Bsd::ucontext_get_fp(uc);
149 } else {
150 epc = nullptr;
151 if (ret_sp) *ret_sp = (intptr_t *)nullptr;
152 if (ret_fp) *ret_fp = (intptr_t *)nullptr;
153 }
154
155 return epc;
156 }
157
158 frame os::fetch_frame_from_context(const void* ucVoid) {
159 intptr_t* sp;
160 intptr_t* fp;
161 address epc = fetch_frame_from_context(ucVoid, &sp, &fp);
162 if (!is_readable_pointer(epc)) {
163 // Try to recover from calling into bad memory
164 // Assume new frame has not been set up, the same as
165 // compiled frame stack bang
166 return fetch_compiled_frame_from_context(ucVoid);
167 }
168 return frame(sp, fp, epc);
169 }
170
171 frame os::fetch_compiled_frame_from_context(const void* ucVoid) {
172 const ucontext_t* uc = (const ucontext_t*)ucVoid;
173 // In compiled code, the stack banging is performed before LR
174 // has been saved in the frame. LR is live, and SP and FP
175 // belong to the caller.
176 intptr_t* fp = os::Bsd::ucontext_get_fp(uc);
177 intptr_t* sp = os::Bsd::ucontext_get_sp(uc);
178 address pc = (address)(uc->context_lr
179 - NativeInstruction::instruction_size);
180 return frame(sp, fp, pc);
181 }
182
183 // JVM compiled with -fno-omit-frame-pointer, so RFP is saved on the stack.
184 frame os::get_sender_for_C_frame(frame* fr) {
185 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
186 }
187
188 NOINLINE frame os::current_frame() {
189 intptr_t *fp = *(intptr_t **)__builtin_frame_address(0);
190 frame myframe((intptr_t*)os::current_stack_pointer(),
191 (intptr_t*)fp,
192 CAST_FROM_FN_PTR(address, os::current_frame));
193 if (os::is_first_C_frame(&myframe)) {
194 // stack is not walkable
195 return frame();
196 } else {
197 return os::get_sender_for_C_frame(&myframe);
198 }
199 }
200
201 bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
202 ucontext_t* uc, JavaThread* thread) {
203 // Enable WXWrite: this function is called by the signal handler at arbitrary
204 // point of execution.
205 ThreadWXEnable wx(WXWrite, thread);
206
207 // decide if this trap can be handled by a stub
208 address stub = nullptr;
209
210 address pc = nullptr;
211
212 //%note os_trap_1
213 if (info != nullptr && uc != nullptr && thread != nullptr) {
214 pc = (address) os::Posix::ucontext_get_pc(uc);
215
216 // Handle ALL stack overflow variations here
217 if (sig == SIGSEGV || sig == SIGBUS) {
218 address addr = (address) info->si_addr;
219
220 // Make sure the high order byte is sign extended, as it may be masked away by the hardware.
221 if ((uintptr_t(addr) & (uintptr_t(1) << 55)) != 0) {
222 addr = address(uintptr_t(addr) | (uintptr_t(0xFF) << 56));
223 }
224
225 // check if fault address is within thread stack
226 if (thread->is_in_full_stack(addr)) {
227 // stack overflow
228 if (os::Posix::handle_stack_overflow(thread, addr, pc, uc, &stub)) {
229 return true; // continue
230 }
231 }
232 }
233
234 // We test if stub is already set (by the stack overflow code
235 // above) so it is not overwritten by the code that follows. This
236 // check is not required on other platforms, because on other
237 // platforms we check for SIGSEGV only or SIGBUS only, where here
238 // we have to check for both SIGSEGV and SIGBUS.
239 if (thread->thread_state() == _thread_in_Java && stub == nullptr) {
240 // Java thread running in Java code => find exception handler if any
241 // a fault inside compiled code, the interpreter, or a stub
242
243 // Handle signal from NativeJump::patch_verified_entry().
244 if ((sig == SIGILL)
245 && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
246 if (TraceTraps) {
247 tty->print_cr("trap: not_entrant");
248 }
249 stub = SharedRuntime::get_handle_wrong_method_stub();
250 } else if ((sig == SIGSEGV || sig == SIGBUS) && SafepointMechanism::is_poll_address((address)info->si_addr)) {
251 stub = SharedRuntime::get_poll_stub(pc);
252 #if defined(__APPLE__)
253 // 32-bit Darwin reports a SIGBUS for nearly all memory access exceptions.
254 // 64-bit Darwin may also use a SIGBUS (seen with compressed oops).
255 // Catching SIGBUS here prevents the implicit SIGBUS null check below from
256 // being called, so only do so if the implicit null check is not necessary.
257 } else if (sig == SIGBUS && !MacroAssembler::uses_implicit_null_check(info->si_addr)) {
258 #else
259 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
260 #endif
261 // BugId 4454115: A read from a MappedByteBuffer can fault
262 // here if the underlying file has been truncated.
263 // Do not crash the VM in such a case.
264 CodeBlob* cb = CodeCache::find_blob(pc);
265 nmethod* nm = (cb != nullptr) ? cb->as_nmethod_or_null() : nullptr;
266 bool is_unsafe_memory_access = (thread->doing_unsafe_access() && UnsafeMemoryAccess::contains_pc(pc));
267 if ((nm != nullptr && nm->has_unsafe_access()) || is_unsafe_memory_access) {
268 address next_pc = pc + NativeCall::instruction_size;
269 if (is_unsafe_memory_access) {
270 next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
271 }
272 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
273 }
274 } else if (sig == SIGILL && nativeInstruction_at(pc)->is_stop()) {
275 // A pointer to the message will have been placed in x0
276 const char *detail_msg = (const char *)(uc->uc_mcontext->DU3_PREFIX(ss,x[0]));
277 const char *msg = "stop";
278 if (TraceTraps) {
279 tty->print_cr("trap: %s: (SIGILL)", msg);
280 }
281
282 // End life with a fatal error, message and detail message and the context.
283 // Note: no need to do any post-processing here (e.g. signal chaining)
284 VMError::report_and_die(thread, uc, nullptr, 0, msg, "%s", detail_msg);
285 ShouldNotReachHere();
286
287 } else if (sig == SIGFPE &&
288 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
289 stub =
290 SharedRuntime::
291 continuation_for_implicit_exception(thread,
292 pc,
293 SharedRuntime::
294 IMPLICIT_DIVIDE_BY_ZERO);
295 } else if ((sig == SIGSEGV || sig == SIGBUS) &&
296 MacroAssembler::uses_implicit_null_check(info->si_addr)) {
297 // Determination of interpreter/vtable stub/compiled code null exception
298 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
299 }
300 } else if ((thread->thread_state() == _thread_in_vm ||
301 thread->thread_state() == _thread_in_native) &&
302 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
303 thread->doing_unsafe_access()) {
304 address next_pc = pc + NativeCall::instruction_size;
305 if (UnsafeMemoryAccess::contains_pc(pc)) {
306 next_pc = UnsafeMemoryAccess::page_error_continue_pc(pc);
307 }
308 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
309 }
310
311 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
312 // and the heap gets shrunk before the field access.
313 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
314 address addr = JNI_FastGetField::find_slowcase_pc(pc);
315 if (addr != (address)-1) {
316 stub = addr;
317 }
318 }
319 }
320
321 if (stub != nullptr) {
322 // save all thread context in case we need to restore it
323 if (thread != nullptr) thread->set_saved_exception_pc(pc);
324
325 os::Posix::ucontext_set_pc(uc, stub);
326 return true;
327 }
328
329 return false; // Mute compiler
330 }
331
332 void os::Bsd::init_thread_fpu_state(void) {
333 }
334
335 ////////////////////////////////////////////////////////////////////////////////
336 // thread stack
337
338 // Minimum usable stack sizes required to get to user code. Space for
339 // HotSpot guard pages is added later.
340 size_t os::_compiler_thread_min_stack_allowed = 72 * K;
341 size_t os::_java_thread_min_stack_allowed = 72 * K;
342 size_t os::_vm_internal_thread_min_stack_allowed = 72 * K;
343
344 // return default stack size for thr_type
345 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
346 // default stack size (compiler thread needs larger stack)
347 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
348 return s;
349 }
350 void os::current_stack_base_and_size(address* base, size_t* size) {
351 address bottom;
352 #ifdef __APPLE__
353 pthread_t self = pthread_self();
354 *base = (address) pthread_get_stackaddr_np(self);
355 *size = pthread_get_stacksize_np(self);
356 bottom = *base - *size;
357 #elif defined(__OpenBSD__)
358 stack_t ss;
359 int rslt = pthread_stackseg_np(pthread_self(), &ss);
360
361 if (rslt != 0)
362 fatal("pthread_stackseg_np failed with error = %d", rslt);
363
364 *base = (address) ss.ss_sp;
365 *size = ss.ss_size;
366 bottom = *base - *size;
367 #else
368 pthread_attr_t attr;
369
370 int rslt = pthread_attr_init(&attr);
371
372 // JVM needs to know exact stack location, abort if it fails
373 if (rslt != 0)
374 fatal("pthread_attr_init failed with error = %d", rslt);
375
376 rslt = pthread_attr_get_np(pthread_self(), &attr);
377
378 if (rslt != 0)
379 fatal("pthread_attr_get_np failed with error = %d", rslt);
380
381 if (pthread_attr_getstackaddr(&attr, (void **)&bottom) != 0 ||
382 pthread_attr_getstacksize(&attr, size) != 0) {
383 fatal("Can not locate current stack attributes!");
384 }
385
386 *base = bottom + *size;
387
388 pthread_attr_destroy(&attr);
389 #endif
390 assert(os::current_stack_pointer() >= bottom &&
391 os::current_stack_pointer() < *base, "just checking");
392 }
393
394 /////////////////////////////////////////////////////////////////////////////
395 // helper functions for fatal error handler
396
397 void os::print_context(outputStream *st, const void *context) {
398 if (context == nullptr) return;
399
400 const ucontext_t *uc = (const ucontext_t*)context;
401
402 st->print_cr("Registers:");
403 st->print( " x0=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 0]);
404 st->print(" x1=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 1]);
405 st->print(" x2=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 2]);
406 st->print(" x3=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 3]);
407 st->cr();
408 st->print( " x4=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 4]);
409 st->print(" x5=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 5]);
410 st->print(" x6=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 6]);
411 st->print(" x7=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 7]);
412 st->cr();
413 st->print( " x8=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 8]);
414 st->print(" x9=" INTPTR_FORMAT, (intptr_t)uc->context_x[ 9]);
415 st->print(" x10=" INTPTR_FORMAT, (intptr_t)uc->context_x[10]);
416 st->print(" x11=" INTPTR_FORMAT, (intptr_t)uc->context_x[11]);
417 st->cr();
418 st->print( "x12=" INTPTR_FORMAT, (intptr_t)uc->context_x[12]);
419 st->print(" x13=" INTPTR_FORMAT, (intptr_t)uc->context_x[13]);
420 st->print(" x14=" INTPTR_FORMAT, (intptr_t)uc->context_x[14]);
421 st->print(" x15=" INTPTR_FORMAT, (intptr_t)uc->context_x[15]);
422 st->cr();
423 st->print( "x16=" INTPTR_FORMAT, (intptr_t)uc->context_x[16]);
424 st->print(" x17=" INTPTR_FORMAT, (intptr_t)uc->context_x[17]);
425 st->print(" x18=" INTPTR_FORMAT, (intptr_t)uc->context_x[18]);
426 st->print(" x19=" INTPTR_FORMAT, (intptr_t)uc->context_x[19]);
427 st->cr();
428 st->print( "x20=" INTPTR_FORMAT, (intptr_t)uc->context_x[20]);
429 st->print(" x21=" INTPTR_FORMAT, (intptr_t)uc->context_x[21]);
430 st->print(" x22=" INTPTR_FORMAT, (intptr_t)uc->context_x[22]);
431 st->print(" x23=" INTPTR_FORMAT, (intptr_t)uc->context_x[23]);
432 st->cr();
433 st->print( "x24=" INTPTR_FORMAT, (intptr_t)uc->context_x[24]);
434 st->print(" x25=" INTPTR_FORMAT, (intptr_t)uc->context_x[25]);
435 st->print(" x26=" INTPTR_FORMAT, (intptr_t)uc->context_x[26]);
436 st->print(" x27=" INTPTR_FORMAT, (intptr_t)uc->context_x[27]);
437 st->cr();
438 st->print( "x28=" INTPTR_FORMAT, (intptr_t)uc->context_x[28]);
439 st->print(" fp=" INTPTR_FORMAT, (intptr_t)uc->context_fp);
440 st->print(" lr=" INTPTR_FORMAT, (intptr_t)uc->context_lr);
441 st->print(" sp=" INTPTR_FORMAT, (intptr_t)uc->context_sp);
442 st->cr();
443 st->print( "pc=" INTPTR_FORMAT, (intptr_t)uc->context_pc);
444 st->print(" cpsr=" INTPTR_FORMAT, (intptr_t)uc->context_cpsr);
445 st->cr();
446 }
447
448 void os::print_register_info(outputStream *st, const void *context, int& continuation) {
449 const int register_count = 29 /* x0-x28 */ + 3 /* fp, lr, sp */;
450 int n = continuation;
451 assert(n >= 0 && n <= register_count, "Invalid continuation value");
452 if (context == nullptr || n == register_count) {
453 return;
454 }
455
456 const ucontext_t *uc = (const ucontext_t*)context;
457 while (n < register_count) {
458 // Update continuation with next index before printing location
459 continuation = n + 1;
460 switch (n) {
461 case 29:
462 st->print(" fp="); print_location(st, uc->context_fp);
463 break;
464 case 30:
465 st->print(" lr="); print_location(st, uc->context_lr);
466 break;
467 case 31:
468 st->print(" sp="); print_location(st, uc->context_sp);
469 break;
470 default:
471 st->print("x%-2d=",n); print_location(st, uc->context_x[n]);
472 break;
473 }
474 ++n;
475 }
476 }
477
478 void os::setup_fpu() {
479 }
480
481 #ifndef PRODUCT
482 void os::verify_stack_alignment() {
483 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
484 }
485 #endif
486
487 int os::extra_bang_size_in_bytes() {
488 // AArch64 does not require the additional stack bang.
489 return 0;
490 }
491
492 void os::current_thread_enable_wx(WXMode mode) {
493 pthread_jit_write_protect_np(mode == WXExec);
494 }
495
496 static inline void atomic_copy64(const volatile void *src, volatile void *dst) {
497 *(jlong *) dst = *(const jlong *) src;
498 }
499
500 extern "C" {
501 int SpinPause() {
502 // We don't use StubRoutines::aarch64::spin_wait stub in order to
503 // avoid a costly call to os::current_thread_enable_wx() on MacOS.
504 // We should return 1 if SpinPause is implemented, and since there
505 // will be a sequence of 11 instructions for NONE and YIELD and 12
506 // instructions for NOP and ISB, SpinPause will always return 1.
507 uint64_t br_dst;
508 const int instructions_per_case = 2;
509 int64_t off = VM_Version::spin_wait_desc().inst() * instructions_per_case * Assembler::instruction_size;
510
511 assert(VM_Version::spin_wait_desc().inst() >= SpinWait::NONE &&
512 VM_Version::spin_wait_desc().inst() <= SpinWait::YIELD, "must be");
513 assert(-1 == SpinWait::NONE, "must be");
514 assert( 0 == SpinWait::NOP, "must be");
515 assert( 1 == SpinWait::ISB, "must be");
516 assert( 2 == SpinWait::YIELD, "must be");
517
518 asm volatile(
519 " adr %[d], 20 \n" // 20 == PC here + 5 instructions => address
520 // to entry for case SpinWait::NOP
521 " add %[d], %[d], %[o] \n"
522 " br %[d] \n"
523 " b SpinPause_return \n" // case SpinWait::NONE (-1)
524 " nop \n" // padding
525 " nop \n" // case SpinWait::NOP ( 0)
526 " b SpinPause_return \n"
527 " isb \n" // case SpinWait::ISB ( 1)
528 " b SpinPause_return \n"
529 " yield \n" // case SpinWait::YIELD ( 2)
530 "SpinPause_return: \n"
531 : [d]"=&r"(br_dst)
532 : [o]"r"(off)
533 : "memory");
534 return 1;
535 }
536
537 void _Copy_conjoint_jshorts_atomic(const jshort* from, jshort* to, size_t count) {
538 if (from > to) {
539 const jshort *end = from + count;
540 while (from < end)
541 *(to++) = *(from++);
542 }
543 else if (from < to) {
544 const jshort *end = from;
545 from += count - 1;
546 to += count - 1;
547 while (from >= end)
548 *(to--) = *(from--);
549 }
550 }
551 void _Copy_conjoint_jints_atomic(const jint* from, jint* to, size_t count) {
552 if (from > to) {
553 const jint *end = from + count;
554 while (from < end)
555 *(to++) = *(from++);
556 }
557 else if (from < to) {
558 const jint *end = from;
559 from += count - 1;
560 to += count - 1;
561 while (from >= end)
562 *(to--) = *(from--);
563 }
564 }
565
566 void _Copy_conjoint_jlongs_atomic(const jlong* from, jlong* to, size_t count) {
567 if (from > to) {
568 const jlong *end = from + count;
569 while (from < end)
570 atomic_copy64(from++, to++);
571 }
572 else if (from < to) {
573 const jlong *end = from;
574 from += count - 1;
575 to += count - 1;
576 while (from >= end)
577 atomic_copy64(from--, to--);
578 }
579 }
580
581 void _Copy_arrayof_conjoint_bytes(const HeapWord* from,
582 HeapWord* to,
583 size_t count) {
584 memmove(to, from, count);
585 }
586 void _Copy_arrayof_conjoint_jshorts(const HeapWord* from,
587 HeapWord* to,
588 size_t count) {
589 memmove(to, from, count * 2);
590 }
591 void _Copy_arrayof_conjoint_jints(const HeapWord* from,
592 HeapWord* to,
593 size_t count) {
594 memmove(to, from, count * 4);
595 }
596 void _Copy_arrayof_conjoint_jlongs(const HeapWord* from,
597 HeapWord* to,
598 size_t count) {
599 memmove(to, from, count * 8);
600 }
601 };