1 /*
2 * Copyright (c) 1999, 2015, 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 "services/memTracker.hpp"
53 #include "utilities/events.hpp"
54 #include "utilities/vmError.hpp"
55
56 // put OS-includes here
57 # include <sys/types.h>
58 # include <sys/mman.h>
59 # include <pthread.h>
60 # include <signal.h>
61 # include <errno.h>
62 # include <dlfcn.h>
63 # include <stdlib.h>
64 # include <stdio.h>
65 # include <unistd.h>
66 # include <sys/resource.h>
67 # include <pthread.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 # include <ucontext.h>
76 # include <fpu_control.h>
77
78 #ifdef AMD64
79 #define REG_SP REG_RSP
80 #define REG_PC REG_RIP
81 #define REG_FP REG_RBP
82 #define SPELL_REG_SP "rsp"
83 #define SPELL_REG_FP "rbp"
84 #else
85 #define REG_SP REG_UESP
86 #define REG_PC REG_EIP
87 #define REG_FP REG_EBP
88 #define SPELL_REG_SP "esp"
89 #define SPELL_REG_FP "ebp"
90 #endif // AMD64
91
92 address os::current_stack_pointer() {
93 #ifdef SPARC_WORKS
94 register void *esp;
95 __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp));
96 return (address) ((char*)esp + sizeof(long)*2);
97 #elif defined(__clang__)
98 intptr_t* esp;
99 __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):);
100 return (address) esp;
101 #else
102 register void *esp __asm__ (SPELL_REG_SP);
103 return (address) esp;
104 #endif
105 }
106
107 char* os::non_memory_address_word() {
108 // Must never look like an address returned by reserve_memory,
109 // even in its subfields (as defined by the CPU immediate fields,
110 // if the CPU splits constants across multiple instructions).
111
112 return (char*) -1;
113 }
114
115 void os::initialize_thread(Thread* thr) {
116 // Nothing to do.
117 }
118
119 address os::Linux::ucontext_get_pc(ucontext_t * uc) {
120 return (address)uc->uc_mcontext.gregs[REG_PC];
121 }
122
123 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
124 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
125 }
126
127 intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) {
128 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
129 }
130
131 intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) {
132 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
133 }
134
135 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
136 // is currently interrupted by SIGPROF.
137 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
138 // frames. Currently we don't do that on Linux, so it's the same as
139 // os::fetch_frame_from_context().
140 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
141 ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
142
143 assert(thread != NULL, "just checking");
144 assert(ret_sp != NULL, "just checking");
145 assert(ret_fp != NULL, "just checking");
146
147 return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
148 }
149
150 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
151 intptr_t** ret_sp, intptr_t** ret_fp) {
152
153 ExtendedPC epc;
154 ucontext_t* uc = (ucontext_t*)ucVoid;
155
156 if (uc != NULL) {
157 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
158 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
159 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
160 } else {
161 // construct empty ExtendedPC for return value checking
162 epc = ExtendedPC(NULL);
163 if (ret_sp) *ret_sp = (intptr_t *)NULL;
164 if (ret_fp) *ret_fp = (intptr_t *)NULL;
165 }
166
167 return epc;
168 }
169
170 frame os::fetch_frame_from_context(void* ucVoid) {
171 intptr_t* sp;
172 intptr_t* fp;
173 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
174 return frame(sp, fp, epc.pc());
175 }
176
177 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
178 // turned off by -fomit-frame-pointer,
179 frame os::get_sender_for_C_frame(frame* fr) {
180 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
181 }
182
183 intptr_t* _get_previous_fp() {
184 #ifdef SPARC_WORKS
185 register intptr_t **ebp;
186 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
187 #elif defined(__clang__)
188 intptr_t **ebp;
189 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
190 #else
191 register intptr_t **ebp __asm__ (SPELL_REG_FP);
192 #endif
193 return (intptr_t*) *ebp; // we want what it points to.
194 }
195
196
197 frame os::current_frame() {
198 intptr_t* fp = _get_previous_fp();
199 frame myframe((intptr_t*)os::current_stack_pointer(),
200 (intptr_t*)fp,
201 CAST_FROM_FN_PTR(address, os::current_frame));
202 if (os::is_first_C_frame(&myframe)) {
203 // stack is not walkable
204 return frame();
205 } else {
206 return os::get_sender_for_C_frame(&myframe);
207 }
208 }
209
210 // Utility functions
211
212 // From IA32 System Programming Guide
213 enum {
214 trap_page_fault = 0xE
215 };
216
217 extern "C" JNIEXPORT int
218 JVM_handle_linux_signal(int sig,
219 siginfo_t* info,
220 void* ucVoid,
221 int abort_if_unrecognized) {
222 ucontext_t* uc = (ucontext_t*) ucVoid;
223
224 Thread* t = ThreadLocalStorage::get_thread_slow();
225
226 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
227 // (no destructors can be run)
228 os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
229
230 SignalHandlerMark shm(t);
231
232 // Note: it's not uncommon that JNI code uses signal/sigset to install
233 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
234 // or have a SIGILL handler when detecting CPU type). When that happens,
235 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
236 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
237 // that do not require siginfo/ucontext first.
238
239 if (sig == SIGPIPE || sig == SIGXFSZ) {
240 // allow chained handler to go first
241 if (os::Linux::chained_handler(sig, info, ucVoid)) {
242 return true;
243 } else {
244 if (PrintMiscellaneous && (WizardMode || Verbose)) {
245 char buf[64];
246 warning("Ignoring %s - see bugs 4229104 or 646499219",
247 os::exception_name(sig, buf, sizeof(buf)));
248 }
249 return true;
250 }
251 }
252
253 JavaThread* thread = NULL;
254 VMThread* vmthread = NULL;
255 if (os::Linux::signal_handlers_are_installed) {
256 if (t != NULL ){
257 if(t->is_Java_thread()) {
258 thread = (JavaThread*)t;
259 }
260 else if(t->is_VM_thread()){
261 vmthread = (VMThread *)t;
262 }
263 }
264 }
265 /*
266 NOTE: does not seem to work on linux.
267 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
268 // can't decode this kind of signal
269 info = NULL;
270 } else {
271 assert(sig == info->si_signo, "bad siginfo");
272 }
273 */
274 // decide if this trap can be handled by a stub
275 address stub = NULL;
276
277 address pc = NULL;
278
279 //%note os_trap_1
280 if (info != NULL && uc != NULL && thread != NULL) {
281 pc = (address) os::Linux::ucontext_get_pc(uc);
282
283 if (StubRoutines::is_safefetch_fault(pc)) {
284 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
285 return 1;
286 }
287
288 #ifndef AMD64
289 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
290 // This can happen in any running code (currently more frequently in
291 // interpreter code but has been seen in compiled code)
292 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
293 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
294 "to unstable signal handling in this distribution.");
295 }
296 #endif // AMD64
297
298 // Handle ALL stack overflow variations here
299 if (sig == SIGSEGV) {
300 address addr = (address) info->si_addr;
301
302 // check if fault address is within thread stack
303 if (addr < thread->stack_base() &&
304 addr >= thread->stack_base() - thread->stack_size()) {
305 // stack overflow
306 if (thread->in_stack_yellow_zone(addr)) {
307 thread->disable_stack_yellow_zone();
308 if (thread->thread_state() == _thread_in_Java) {
309 // Throw a stack overflow exception. Guard pages will be reenabled
310 // while unwinding the stack.
311 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
312 } else {
313 // Thread was in the vm or native code. Return and try to finish.
314 return 1;
315 }
316 } else if (thread->in_stack_red_zone(addr)) {
317 // Fatal red zone violation. Disable the guard pages and fall through
318 // to handle_unexpected_exception way down below.
319 thread->disable_stack_red_zone();
320 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
321
322 // This is a likely cause, but hard to verify. Let's just print
323 // it as a hint.
324 tty->print_raw_cr("Please check if any of your loaded .so files has "
325 "enabled executable stack (see man page execstack(8))");
326 } else {
327 // Accessing stack address below sp may cause SEGV if current
328 // thread has MAP_GROWSDOWN stack. This should only happen when
329 // current thread was created by user code with MAP_GROWSDOWN flag
330 // and then attached to VM. See notes in os_linux.cpp.
331 if (thread->osthread()->expanding_stack() == 0) {
332 thread->osthread()->set_expanding_stack();
333 if (os::Linux::manually_expand_stack(thread, addr)) {
334 thread->osthread()->clear_expanding_stack();
335 return 1;
336 }
337 thread->osthread()->clear_expanding_stack();
338 } else {
339 fatal("recursive segv. expanding stack.");
340 }
341 }
342 }
343 }
344
345 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
346 // Verify that OS save/restore AVX registers.
347 stub = VM_Version::cpuinfo_cont_addr();
348 }
349
350 if (thread->thread_state() == _thread_in_Java) {
351 // Java thread running in Java code => find exception handler if any
352 // a fault inside compiled code, the interpreter, or a stub
353
354 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
355 stub = SharedRuntime::get_poll_stub(pc);
356 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
357 // BugId 4454115: A read from a MappedByteBuffer can fault
358 // here if the underlying file has been truncated.
359 // Do not crash the VM in such a case.
360 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
361 nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
362 if (nm != NULL && nm->has_unsafe_access()) {
363 stub = StubRoutines::handler_for_unsafe_access();
364 }
365 }
366 else
367
368 #ifdef AMD64
369 if (sig == SIGFPE &&
370 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
371 stub =
372 SharedRuntime::
373 continuation_for_implicit_exception(thread,
374 pc,
375 SharedRuntime::
376 IMPLICIT_DIVIDE_BY_ZERO);
377 #else
378 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
379 // HACK: si_code does not work on linux 2.2.12-20!!!
380 int op = pc[0];
381 if (op == 0xDB) {
382 // FIST
383 // TODO: The encoding of D2I in i486.ad can cause an exception
384 // prior to the fist instruction if there was an invalid operation
385 // pending. We want to dismiss that exception. From the win_32
386 // side it also seems that if it really was the fist causing
387 // the exception that we do the d2i by hand with different
388 // rounding. Seems kind of weird.
389 // NOTE: that we take the exception at the NEXT floating point instruction.
390 assert(pc[0] == 0xDB, "not a FIST opcode");
391 assert(pc[1] == 0x14, "not a FIST opcode");
392 assert(pc[2] == 0x24, "not a FIST opcode");
393 return true;
394 } else if (op == 0xF7) {
395 // IDIV
396 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
397 } else {
398 // TODO: handle more cases if we are using other x86 instructions
399 // that can generate SIGFPE signal on linux.
400 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
401 fatal("please update this code.");
402 }
403 #endif // AMD64
404 } else if (sig == SIGSEGV &&
405 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
406 // Determination of interpreter/vtable stub/compiled code null exception
407 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
408 }
409 } else if (thread->thread_state() == _thread_in_vm &&
410 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
411 thread->doing_unsafe_access()) {
412 stub = StubRoutines::handler_for_unsafe_access();
413 }
414
415 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
416 // and the heap gets shrunk before the field access.
417 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
418 address addr = JNI_FastGetField::find_slowcase_pc(pc);
419 if (addr != (address)-1) {
420 stub = addr;
421 }
422 }
423
424 // Check to see if we caught the safepoint code in the
425 // process of write protecting the memory serialization page.
426 // It write enables the page immediately after protecting it
427 // so we can just return to retry the write.
428 if ((sig == SIGSEGV) &&
429 os::is_memory_serialize_page(thread, (address) info->si_addr)) {
430 // Block current thread until the memory serialize page permission restored.
431 os::block_on_serialize_page_trap();
432 return true;
433 }
434 }
435
436 #ifndef AMD64
437 // Execution protection violation
438 //
439 // This should be kept as the last step in the triage. We don't
440 // have a dedicated trap number for a no-execute fault, so be
441 // conservative and allow other handlers the first shot.
442 //
443 // Note: We don't test that info->si_code == SEGV_ACCERR here.
444 // this si_code is so generic that it is almost meaningless; and
445 // the si_code for this condition may change in the future.
446 // Furthermore, a false-positive should be harmless.
447 if (UnguardOnExecutionViolation > 0 &&
448 (sig == SIGSEGV || sig == SIGBUS) &&
449 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
450 int page_size = os::vm_page_size();
451 address addr = (address) info->si_addr;
452 address pc = os::Linux::ucontext_get_pc(uc);
453 // Make sure the pc and the faulting address are sane.
454 //
455 // If an instruction spans a page boundary, and the page containing
456 // the beginning of the instruction is executable but the following
457 // page is not, the pc and the faulting address might be slightly
458 // different - we still want to unguard the 2nd page in this case.
459 //
460 // 15 bytes seems to be a (very) safe value for max instruction size.
461 bool pc_is_near_addr =
462 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
463 bool instr_spans_page_boundary =
464 (align_size_down((intptr_t) pc ^ (intptr_t) addr,
465 (intptr_t) page_size) > 0);
466
467 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
468 static volatile address last_addr =
469 (address) os::non_memory_address_word();
470
471 // In conservative mode, don't unguard unless the address is in the VM
472 if (addr != last_addr &&
473 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
474
475 // Set memory to RWX and retry
476 address page_start =
477 (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
478 bool res = os::protect_memory((char*) page_start, page_size,
479 os::MEM_PROT_RWX);
480
481 if (PrintMiscellaneous && Verbose) {
482 char buf[256];
483 jio_snprintf(buf, sizeof(buf), "Execution protection violation "
484 "at " INTPTR_FORMAT
485 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
486 page_start, (res ? "success" : "failed"), errno);
487 tty->print_raw_cr(buf);
488 }
489 stub = pc;
490
491 // Set last_addr so if we fault again at the same address, we don't end
492 // up in an endless loop.
493 //
494 // There are two potential complications here. Two threads trapping at
495 // the same address at the same time could cause one of the threads to
496 // think it already unguarded, and abort the VM. Likely very rare.
497 //
498 // The other race involves two threads alternately trapping at
499 // different addresses and failing to unguard the page, resulting in
500 // an endless loop. This condition is probably even more unlikely than
501 // the first.
502 //
503 // Although both cases could be avoided by using locks or thread local
504 // last_addr, these solutions are unnecessary complication: this
505 // handler is a best-effort safety net, not a complete solution. It is
506 // disabled by default and should only be used as a workaround in case
507 // we missed any no-execute-unsafe VM code.
508
509 last_addr = addr;
510 }
511 }
512 }
513 #endif // !AMD64
514
515 if (stub != NULL) {
516 // save all thread context in case we need to restore it
517 if (thread != NULL) thread->set_saved_exception_pc(pc);
518
519 os::Linux::ucontext_set_pc(uc, stub);
520 return true;
521 }
522
523 // signal-chaining
524 if (os::Linux::chained_handler(sig, info, ucVoid)) {
525 return true;
526 }
527
528 if (!abort_if_unrecognized) {
529 // caller wants another chance, so give it to him
530 return false;
531 }
532
533 if (pc == NULL && uc != NULL) {
534 pc = os::Linux::ucontext_get_pc(uc);
535 }
536
537 // unmask current signal
538 sigset_t newset;
539 sigemptyset(&newset);
540 sigaddset(&newset, sig);
541 sigprocmask(SIG_UNBLOCK, &newset, NULL);
542
543 VMError::report_and_die(t, sig, pc, info, ucVoid);
544
545 ShouldNotReachHere();
546 return true; // Mute compiler
547 }
548
549 void os::Linux::init_thread_fpu_state(void) {
550 #ifndef AMD64
551 // set fpu to 53 bit precision
552 set_fpu_control_word(0x27f);
553 #endif // !AMD64
554 }
555
556 int os::Linux::get_fpu_control_word(void) {
557 #ifdef AMD64
558 return 0;
559 #else
560 int fpu_control;
561 _FPU_GETCW(fpu_control);
562 return fpu_control & 0xffff;
563 #endif // AMD64
564 }
565
566 void os::Linux::set_fpu_control_word(int fpu_control) {
567 #ifndef AMD64
568 _FPU_SETCW(fpu_control);
569 #endif // !AMD64
570 }
571
572 // Check that the linux kernel version is 2.4 or higher since earlier
573 // versions do not support SSE without patches.
574 bool os::supports_sse() {
575 #ifdef AMD64
576 return true;
577 #else
578 struct utsname uts;
579 if( uname(&uts) != 0 ) return false; // uname fails?
580 char *minor_string;
581 int major = strtol(uts.release,&minor_string,10);
582 int minor = strtol(minor_string+1,NULL,10);
583 bool result = (major > 2 || (major==2 && minor >= 4));
584 #ifndef PRODUCT
585 if (PrintMiscellaneous && Verbose) {
586 tty->print("OS version is %d.%d, which %s support SSE/SSE2\n",
587 major,minor, result ? "DOES" : "does NOT");
588 }
589 #endif
590 return result;
591 #endif // AMD64
592 }
593
594 bool os::is_allocatable(size_t bytes) {
595 #ifdef AMD64
596 // unused on amd64?
597 return true;
598 #else
599
600 if (bytes < 2 * G) {
601 return true;
602 }
603
604 char* addr = reserve_memory(bytes, NULL);
605
606 if (addr != NULL) {
607 release_memory(addr, bytes);
608 }
609
610 return addr != NULL;
611 #endif // AMD64
612 }
613
614 ////////////////////////////////////////////////////////////////////////////////
615 // thread stack
616
617 #ifdef AMD64
618 size_t os::Linux::min_stack_allowed = 64 * K;
619 #else
620 size_t os::Linux::min_stack_allowed = (48 DEBUG_ONLY(+4))*K;
621 #endif // AMD64
622
623 // return default stack size for thr_type
624 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
625 // default stack size (compiler thread needs larger stack)
626 #ifdef AMD64
627 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
628 #else
629 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
630 #endif // AMD64
631 return s;
632 }
633
634 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
635 // Creating guard page is very expensive. Java thread has HotSpot
636 // guard page, only enable glibc guard page for non-Java threads.
637 return (thr_type == java_thread ? 0 : page_size());
638 }
639
640 // Java thread:
641 //
642 // Low memory addresses
643 // +------------------------+
644 // | |\ JavaThread created by VM does not have glibc
645 // | glibc guard page | - guard, attached Java thread usually has
646 // | |/ 1 page glibc guard.
647 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
648 // | |\
649 // | HotSpot Guard Pages | - red and yellow pages
650 // | |/
651 // +------------------------+ JavaThread::stack_yellow_zone_base()
652 // | |\
653 // | Normal Stack | -
654 // | |/
655 // P2 +------------------------+ Thread::stack_base()
656 //
657 // Non-Java thread:
658 //
659 // Low memory addresses
660 // +------------------------+
661 // | |\
662 // | glibc guard page | - usually 1 page
663 // | |/
664 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
665 // | |\
666 // | Normal Stack | -
667 // | |/
668 // P2 +------------------------+ Thread::stack_base()
669 //
670 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
671 // pthread_attr_getstack()
672
673 static void current_stack_region(address * bottom, size_t * size) {
674 if (os::Linux::is_initial_thread()) {
675 // initial thread needs special handling because pthread_getattr_np()
676 // may return bogus value.
677 *bottom = os::Linux::initial_thread_stack_bottom();
678 *size = os::Linux::initial_thread_stack_size();
679 } else {
680 pthread_attr_t attr;
681
682 int rslt = pthread_getattr_np(pthread_self(), &attr);
683
684 // JVM needs to know exact stack location, abort if it fails
685 if (rslt != 0) {
686 if (rslt == ENOMEM) {
687 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
688 } else {
689 fatal("pthread_getattr_np failed with errno = %d", rslt);
690 }
691 }
692
693 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
694 fatal("Can not locate current stack attributes!");
695 }
696
697 pthread_attr_destroy(&attr);
698
699 }
700 assert(os::current_stack_pointer() >= *bottom &&
701 os::current_stack_pointer() < *bottom + *size, "just checking");
702 }
703
704 address os::current_stack_base() {
705 address bottom;
706 size_t size;
707 current_stack_region(&bottom, &size);
708 return (bottom + size);
709 }
710
711 size_t os::current_stack_size() {
712 // stack size includes normal stack and HotSpot guard pages
713 address bottom;
714 size_t size;
715 current_stack_region(&bottom, &size);
716 return size;
717 }
718
719 /////////////////////////////////////////////////////////////////////////////
720 // helper functions for fatal error handler
721
722 void os::print_context(outputStream *st, void *context) {
723 if (context == NULL) return;
724
725 ucontext_t *uc = (ucontext_t*)context;
726 st->print_cr("Registers:");
727 #ifdef AMD64
728 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
729 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
730 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
731 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
732 st->cr();
733 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
734 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
735 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
736 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
737 st->cr();
738 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
739 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
740 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
741 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
742 st->cr();
743 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
744 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
745 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
746 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
747 st->cr();
748 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
749 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
750 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
751 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
752 st->cr();
753 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
754 #else
755 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
756 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
757 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
758 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
759 st->cr();
760 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
761 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
762 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
763 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
764 st->cr();
765 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
766 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
767 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
768 #endif // AMD64
769 st->cr();
770 st->cr();
771
772 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
773 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
774 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
775 st->cr();
776
777 // Note: it may be unsafe to inspect memory near pc. For example, pc may
778 // point to garbage if entry point in an nmethod is corrupted. Leave
779 // this at the end, and hope for the best.
780 address pc = os::Linux::ucontext_get_pc(uc);
781 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
782 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
783 }
784
785 void os::print_register_info(outputStream *st, void *context) {
786 if (context == NULL) return;
787
788 ucontext_t *uc = (ucontext_t*)context;
789
790 st->print_cr("Register to memory mapping:");
791 st->cr();
792
793 // this is horrendously verbose but the layout of the registers in the
794 // context does not match how we defined our abstract Register set, so
795 // we can't just iterate through the gregs area
796
797 // this is only for the "general purpose" registers
798
799 #ifdef AMD64
800 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
801 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
802 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
803 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
804 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
805 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
806 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
807 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
808 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
809 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
810 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
811 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
812 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
813 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
814 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
815 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
816 #else
817 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
818 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
819 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
820 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
821 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
822 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
823 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
824 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
825 #endif // AMD64
826
827 st->cr();
828 }
829
830 void os::setup_fpu() {
831 #ifndef AMD64
832 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
833 __asm__ volatile ( "fldcw (%0)" :
834 : "r" (fpu_cntrl) : "memory");
835 #endif // !AMD64
836 }
837
838 #ifndef PRODUCT
839 void os::verify_stack_alignment() {
840 #ifdef AMD64
841 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
842 #endif
843 }
844 #endif
845
846
847 /*
848 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
849 * updates (JDK-8023956).
850 */
851 void os::workaround_expand_exec_shield_cs_limit() {
852 #if defined(IA32)
853 size_t page_size = os::vm_page_size();
854 /*
855 * Take the highest VA the OS will give us and exec
856 *
857 * Although using -(pagesz) as mmap hint works on newer kernel as you would
858 * think, older variants affected by this work-around don't (search forward only).
859 *
860 * On the affected distributions, we understand the memory layout to be:
861 *
862 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
863 *
864 * A few pages south main stack will do it.
865 *
866 * If we are embedded in an app other than launcher (initial != main stack),
867 * we don't have much control or understanding of the address space, just let it slide.
868 */
869 char* hint = (char*) (Linux::initial_thread_stack_bottom() -
870 ((StackYellowPages + StackRedPages + 1) * page_size));
871 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
872 if ( (codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true)) ) {
873 return; // No matter, we tried, best effort.
874 }
875
876 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
877
878 if (PrintMiscellaneous && (Verbose || WizardMode)) {
879 tty->print_cr("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
880 }
881
882 // Some code to exec: the 'ret' instruction
883 codebuf[0] = 0xC3;
884
885 // Call the code in the codebuf
886 __asm__ volatile("call *%0" : : "r"(codebuf));
887
888 // keep the page mapped so CS limit isn't reduced.
889 #endif
890 }
891
892 int os::extra_bang_size_in_bytes() {
893 // JDK-8050147 requires the full cache line bang for x86.
894 return VM_Version::L1_line_size();
895 }