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