1 /*
2 * Copyright (c) 1999, 2018, 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 // no precompiled headers
26 #include "asm/macroAssembler.hpp"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/icBuffer.hpp"
31 #include "code/vtableStubs.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "jvm_linux.h"
34 #include "memory/allocation.inline.hpp"
35 #include "mutex_linux.inline.hpp"
36 #include "os_share_linux.hpp"
37 #include "prims/jniFastGetField.hpp"
38 #include "prims/jvm.h"
39 #include "prims/jvm_misc.hpp"
40 #include "runtime/arguments.hpp"
41 #include "runtime/extendedPC.hpp"
42 #include "runtime/frame.inline.hpp"
43 #include "runtime/interfaceSupport.hpp"
44 #include "runtime/java.hpp"
45 #include "runtime/javaCalls.hpp"
46 #include "runtime/mutexLocker.hpp"
47 #include "runtime/osThread.hpp"
48 #include "runtime/sharedRuntime.hpp"
49 #include "runtime/stubRoutines.hpp"
50 #include "runtime/thread.inline.hpp"
51 #include "runtime/timer.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 # include <fpu_control.h>
76
77 #define REG_FP 29
78
79 #define NOINLINE __attribute__ ((noinline))
80
81 NOINLINE address os::current_stack_pointer() {
82 return (address)__builtin_frame_address(0);
83 }
84
85 char* os::non_memory_address_word() {
86 // Must never look like an address returned by reserve_memory,
87 // even in its subfields (as defined by the CPU immediate fields,
88 // if the CPU splits constants across multiple instructions).
89
90 return (char*) 0xffffffffffff;
91 }
92
93 void os::initialize_thread(Thread *thr) {
94 }
95
96 address os::Linux::ucontext_get_pc(ucontext_t * uc) {
97 return (address)uc->uc_mcontext.pc;
98 }
99
100 intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) {
101 return (intptr_t*)uc->uc_mcontext.sp;
102 }
103
104 intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) {
105 return (intptr_t*)uc->uc_mcontext.regs[REG_FP];
106 }
107
108 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
109 // is currently interrupted by SIGPROF.
110 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
111 // frames. Currently we don't do that on Linux, so it's the same as
112 // os::fetch_frame_from_context().
113 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
114 ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
115
116 assert(thread != NULL, "just checking");
117 assert(ret_sp != NULL, "just checking");
118 assert(ret_fp != NULL, "just checking");
119
120 return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
121 }
122
123 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
124 intptr_t** ret_sp, intptr_t** ret_fp) {
125
126 ExtendedPC epc;
127 ucontext_t* uc = (ucontext_t*)ucVoid;
128
129 if (uc != NULL) {
130 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
131 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
132 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
133 } else {
134 // construct empty ExtendedPC for return value checking
135 epc = ExtendedPC(NULL);
136 if (ret_sp) *ret_sp = (intptr_t *)NULL;
137 if (ret_fp) *ret_fp = (intptr_t *)NULL;
138 }
139
140 return epc;
141 }
142
143 frame os::fetch_frame_from_context(void* ucVoid) {
144 intptr_t* sp;
145 intptr_t* fp;
146 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
147 return frame(sp, fp, epc.pc());
148 }
149
150 // By default, gcc always saves frame pointer rfp on this stack. This
151 // may get turned off by -fomit-frame-pointer.
152 frame os::get_sender_for_C_frame(frame* fr) {
153 return frame(fr->link(), fr->link(), fr->sender_pc());
154 }
155
156 NOINLINE frame os::current_frame() {
157 intptr_t *fp = *(intptr_t **)__builtin_frame_address(0);
158 frame myframe((intptr_t*)os::current_stack_pointer(),
159 (intptr_t*)fp,
160 CAST_FROM_FN_PTR(address, os::current_frame));
161 if (os::is_first_C_frame(&myframe)) {
162 // stack is not walkable
163 return frame();
164 } else {
165 return os::get_sender_for_C_frame(&myframe);
166 }
167 }
168
169 // Utility functions
170
171 // An operation in Unsafe has faulted. We're going to return to the
172 // instruction after the faulting load or store. We also set
173 // pending_unsafe_access_error so that at some point in the future our
174 // user will get a helpful message.
175 static address handle_unsafe_access(JavaThread* thread, address pc) {
176 // pc is the instruction which we must emulate
177 // doing a no-op is fine: return garbage from the load
178 // therefore, compute npc
179 address npc = pc + NativeCall::instruction_size;
180
181 // request an async exception
182 thread->set_pending_unsafe_access_error();
183
184 // return address of next instruction to execute
185 return npc;
186 }
187
188 extern "C" JNIEXPORT int
189 JVM_handle_linux_signal(int sig,
190 siginfo_t* info,
191 void* ucVoid,
192 int abort_if_unrecognized) {
193 ucontext_t* uc = (ucontext_t*) ucVoid;
194
195 Thread* t = ThreadLocalStorage::get_thread_slow();
196
197 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
198 // (no destructors can be run)
199 os::ThreadCrashProtection::check_crash_protection(sig, t);
200
201 SignalHandlerMark shm(t);
202
203 // Note: it's not uncommon that JNI code uses signal/sigset to install
204 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
205 // or have a SIGILL handler when detecting CPU type). When that happens,
206 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
207 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
208 // that do not require siginfo/ucontext first.
209
210 if (sig == SIGPIPE || sig == SIGXFSZ) {
211 // allow chained handler to go first
212 if (os::Linux::chained_handler(sig, info, ucVoid)) {
213 return true;
214 } else {
215 if (PrintMiscellaneous && (WizardMode || Verbose)) {
216 char buf[64];
217 warning("Ignoring %s - see bugs 4229104 or 646499219",
218 os::exception_name(sig, buf, sizeof(buf)));
219 }
220 return true;
221 }
222 }
223
224 JavaThread* thread = NULL;
225 VMThread* vmthread = NULL;
226 if (os::Linux::signal_handlers_are_installed) {
227 if (t != NULL ){
228 if(t->is_Java_thread()) {
229 thread = (JavaThread*)t;
230 }
231 else if(t->is_VM_thread()){
232 vmthread = (VMThread *)t;
233 }
234 }
235 }
236 /*
237 NOTE: does not seem to work on linux.
238 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
239 // can't decode this kind of signal
240 info = NULL;
241 } else {
242 assert(sig == info->si_signo, "bad siginfo");
243 }
244 */
245 // decide if this trap can be handled by a stub
246 address stub = NULL;
247
248 address pc = NULL;
249
250 //%note os_trap_1
251 if (info != NULL && uc != NULL && thread != NULL) {
252 pc = (address) os::Linux::ucontext_get_pc(uc);
253
254 if (StubRoutines::is_safefetch_fault(pc)) {
255 uc->uc_mcontext.pc = intptr_t(StubRoutines::continuation_for_safefetch_fault(pc));
256 return 1;
257 }
258
259 #ifndef AMD64
260 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
261 // This can happen in any running code (currently more frequently in
262 // interpreter code but has been seen in compiled code)
263 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
264 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
265 "to unstable signal handling in this distribution.");
266 }
267 #endif // AMD64
268
269 // Handle ALL stack overflow variations here
270 if (sig == SIGSEGV) {
271 address addr = (address) info->si_addr;
272
273 // check if fault address is within thread stack
274 if (addr < thread->stack_base() &&
275 addr >= thread->stack_base() - thread->stack_size()) {
276 // stack overflow
277 if (thread->in_stack_yellow_zone(addr)) {
278 thread->disable_stack_yellow_zone();
279 if (thread->thread_state() == _thread_in_Java) {
280 // Throw a stack overflow exception. Guard pages will be reenabled
281 // while unwinding the stack.
282 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
283 } else {
284 // Thread was in the vm or native code. Return and try to finish.
285 return 1;
286 }
287 } else if (thread->in_stack_red_zone(addr)) {
288 // Fatal red zone violation. Disable the guard pages and fall through
289 // to handle_unexpected_exception way down below.
290 thread->disable_stack_red_zone();
291 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
292
293 // This is a likely cause, but hard to verify. Let's just print
294 // it as a hint.
295 tty->print_raw_cr("Please check if any of your loaded .so files has "
296 "enabled executable stack (see man page execstack(8))");
297 } else {
298 // Accessing stack address below sp may cause SEGV if current
299 // thread has MAP_GROWSDOWN stack. This should only happen when
300 // current thread was created by user code with MAP_GROWSDOWN flag
301 // and then attached to VM. See notes in os_linux.cpp.
302 if (thread->osthread()->expanding_stack() == 0) {
303 thread->osthread()->set_expanding_stack();
304 if (os::Linux::manually_expand_stack(thread, addr)) {
305 thread->osthread()->clear_expanding_stack();
306 return 1;
307 }
308 thread->osthread()->clear_expanding_stack();
309 } else {
310 fatal("recursive segv. expanding stack.");
311 }
312 }
313 }
314 }
315
316 if (thread->thread_state() == _thread_in_Java) {
317 // Java thread running in Java code => find exception handler if any
318 // a fault inside compiled code, the interpreter, or a stub
319
320 // Handle signal from NativeJump::patch_verified_entry().
321 if ((sig == SIGILL || sig == SIGTRAP)
322 && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {
323 if (TraceTraps) {
324 tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
325 }
326 stub = SharedRuntime::get_handle_wrong_method_stub();
327 } else if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
328 stub = SharedRuntime::get_poll_stub(pc);
329 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
330 // BugId 4454115: A read from a MappedByteBuffer can fault
331 // here if the underlying file has been truncated.
332 // Do not crash the VM in such a case.
333 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
334 nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
335 if (nm != NULL && nm->has_unsafe_access()) {
336 stub = handle_unsafe_access(thread, pc);
337 }
338 }
339 else
340
341 if (sig == SIGFPE &&
342 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
343 stub =
344 SharedRuntime::
345 continuation_for_implicit_exception(thread,
346 pc,
347 SharedRuntime::
348 IMPLICIT_DIVIDE_BY_ZERO);
349 } else if (sig == SIGSEGV &&
350 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
351 // Determination of interpreter/vtable stub/compiled code null exception
352 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
353 }
354 } else if (thread->thread_state() == _thread_in_vm &&
355 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
356 thread->doing_unsafe_access()) {
357 stub = handle_unsafe_access(thread, pc);
358 }
359
360 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
361 // and the heap gets shrunk before the field access.
362 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
363 address addr = JNI_FastGetField::find_slowcase_pc(pc);
364 if (addr != (address)-1) {
365 stub = addr;
366 }
367 }
368
369 // Check to see if we caught the safepoint code in the
370 // process of write protecting the memory serialization page.
371 // It write enables the page immediately after protecting it
372 // so we can just return to retry the write.
373 if ((sig == SIGSEGV) &&
374 os::is_memory_serialize_page(thread, (address) info->si_addr)) {
375 // Block current thread until the memory serialize page permission restored.
376 os::block_on_serialize_page_trap();
377 return true;
378 }
379 }
380
381 if (stub != NULL) {
382 // save all thread context in case we need to restore it
383 if (thread != NULL) thread->set_saved_exception_pc(pc);
384
385 uc->uc_mcontext.pc = (__u64)stub;
386 return true;
387 }
388
389 // signal-chaining
390 if (os::Linux::chained_handler(sig, info, ucVoid)) {
391 return true;
392 }
393
394 if (!abort_if_unrecognized) {
395 // caller wants another chance, so give it to him
396 return false;
397 }
398
399 if (pc == NULL && uc != NULL) {
400 pc = os::Linux::ucontext_get_pc(uc);
401 }
402
403 // unmask current signal
404 sigset_t newset;
405 sigemptyset(&newset);
406 sigaddset(&newset, sig);
407 sigprocmask(SIG_UNBLOCK, &newset, NULL);
408
409 VMError err(t, sig, pc, info, ucVoid);
410 err.report_and_die();
411
412 ShouldNotReachHere();
413 return true; // Mute compiler
414 }
415
416 void os::Linux::init_thread_fpu_state(void) {
417 }
418
419 int os::Linux::get_fpu_control_word(void) {
420 return 0;
421 }
422
423 void os::Linux::set_fpu_control_word(int fpu_control) {
424 }
425
426 // Check that the linux kernel version is 2.4 or higher since earlier
427 // versions do not support SSE without patches.
428 bool os::supports_sse() {
429 return true;
430 }
431
432 bool os::is_allocatable(size_t bytes) {
433 return true;
434 }
435
436 ////////////////////////////////////////////////////////////////////////////////
437 // thread stack
438
439 size_t os::Linux::min_stack_allowed = 64 * K;
440
441 // amd64: pthread on amd64 is always in floating stack mode
442 bool os::Linux::supports_variable_stack_size() { return true; }
443
444 // return default stack size for thr_type
445 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
446 // default stack size (compiler thread needs larger stack)
447 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
448 return s;
449 }
450
451 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
452 // Creating guard page is very expensive. Java thread has HotSpot
453 // guard page, only enable glibc guard page for non-Java threads.
454 return (thr_type == java_thread ? 0 : page_size());
455 }
456
457 // Java thread:
458 //
459 // Low memory addresses
460 // +------------------------+
461 // | |\ JavaThread created by VM does not have glibc
462 // | glibc guard page | - guard, attached Java thread usually has
463 // | |/ 1 page glibc guard.
464 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
465 // | |\
466 // | HotSpot Guard Pages | - red and yellow pages
467 // | |/
468 // +------------------------+ JavaThread::stack_yellow_zone_base()
469 // | |\
470 // | Normal Stack | -
471 // | |/
472 // P2 +------------------------+ Thread::stack_base()
473 //
474 // Non-Java thread:
475 //
476 // Low memory addresses
477 // +------------------------+
478 // | |\
479 // | glibc guard page | - usually 1 page
480 // | |/
481 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
482 // | |\
483 // | Normal Stack | -
484 // | |/
485 // P2 +------------------------+ Thread::stack_base()
486 //
487 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
488 // pthread_attr_getstack()
489
490 static void current_stack_region(address * bottom, size_t * size) {
491 if (os::is_primordial_thread()) {
492 // primordial thread needs special handling because pthread_getattr_np()
493 // may return bogus value.
494 *bottom = os::Linux::initial_thread_stack_bottom();
495 *size = os::Linux::initial_thread_stack_size();
496 } else {
497 pthread_attr_t attr;
498
499 int rslt = pthread_getattr_np(pthread_self(), &attr);
500
501 // JVM needs to know exact stack location, abort if it fails
502 if (rslt != 0) {
503 if (rslt == ENOMEM) {
504 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
505 } else {
506 fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt));
507 }
508 }
509
510 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
511 fatal("Can not locate current stack attributes!");
512 }
513
514 pthread_attr_destroy(&attr);
515
516 }
517 assert(os::current_stack_pointer() >= *bottom &&
518 os::current_stack_pointer() < *bottom + *size, "just checking");
519 }
520
521 address os::current_stack_base() {
522 address bottom;
523 size_t size;
524 current_stack_region(&bottom, &size);
525 return (bottom + size);
526 }
527
528 size_t os::current_stack_size() {
529 // stack size includes normal stack and HotSpot guard pages
530 address bottom;
531 size_t size;
532 current_stack_region(&bottom, &size);
533 return size;
534 }
535
536 /////////////////////////////////////////////////////////////////////////////
537 // helper functions for fatal error handler
538
539 void os::print_context(outputStream *st, void *context) {
540 if (context == NULL) return;
541
542 ucontext_t *uc = (ucontext_t*)context;
543 st->print_cr("Registers:");
544 for (int r = 0; r < 31; r++)
545 st->print_cr( "R%d=" INTPTR_FORMAT, r, (int64_t)uc->uc_mcontext.regs[r]);
546 st->cr();
547
548 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
549 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
550 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
551 st->cr();
552
553 // Note: it may be unsafe to inspect memory near pc. For example, pc may
554 // point to garbage if entry point in an nmethod is corrupted. Leave
555 // this at the end, and hope for the best.
556 address pc = os::Linux::ucontext_get_pc(uc);
557 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
558 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
559 }
560
561 void os::print_register_info(outputStream *st, void *context) {
562 if (context == NULL) return;
563
564 ucontext_t *uc = (ucontext_t*)context;
565
566 st->print_cr("Register to memory mapping:");
567 st->cr();
568
569 // this is horrendously verbose but the layout of the registers in the
570 // context does not match how we defined our abstract Register set, so
571 // we can't just iterate through the gregs area
572
573 // this is only for the "general purpose" registers
574
575 for (int r = 0; r < 31; r++)
576 st->print_cr( "R%d=" INTPTR_FORMAT, r, (int64_t)uc->uc_mcontext.regs[r]);
577 st->cr();
578 }
579
580 void os::setup_fpu() {
581 }
582
583 #ifndef PRODUCT
584 void os::verify_stack_alignment() {
585 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
586 }
587 #endif
588
589 extern "C" {
590 int SpinPause() {
591 return 0;
592 }
593
594 void _Copy_conjoint_jshorts_atomic(jshort* from, jshort* to, size_t count) {
595 if (from > to) {
596 const jshort *end = from + count;
597 while (from < end)
598 *(to++) = *(from++);
599 }
600 else if (from < to) {
601 const jshort *end = from;
602 from += count - 1;
603 to += count - 1;
604 while (from >= end)
605 *(to--) = *(from--);
606 }
607 }
608 void _Copy_conjoint_jints_atomic(jint* from, jint* to, size_t count) {
609 if (from > to) {
610 const jint *end = from + count;
611 while (from < end)
612 *(to++) = *(from++);
613 }
614 else if (from < to) {
615 const jint *end = from;
616 from += count - 1;
617 to += count - 1;
618 while (from >= end)
619 *(to--) = *(from--);
620 }
621 }
622 void _Copy_conjoint_jlongs_atomic(jlong* from, jlong* to, size_t count) {
623 if (from > to) {
624 const jlong *end = from + count;
625 while (from < end)
626 os::atomic_copy64(from++, to++);
627 }
628 else if (from < to) {
629 const jlong *end = from;
630 from += count - 1;
631 to += count - 1;
632 while (from >= end)
633 os::atomic_copy64(from--, to--);
634 }
635 }
636
637 void _Copy_arrayof_conjoint_bytes(HeapWord* from,
638 HeapWord* to,
639 size_t count) {
640 memmove(to, from, count);
641 }
642 void _Copy_arrayof_conjoint_jshorts(HeapWord* from,
643 HeapWord* to,
644 size_t count) {
645 memmove(to, from, count * 2);
646 }
647 void _Copy_arrayof_conjoint_jints(HeapWord* from,
648 HeapWord* to,
649 size_t count) {
650 memmove(to, from, count * 4);
651 }
652 void _Copy_arrayof_conjoint_jlongs(HeapWord* from,
653 HeapWord* to,
654 size_t count) {
655 memmove(to, from, count * 8);
656 }
657 };