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 frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) {
178 intptr_t* sp;
179 intptr_t* fp;
180 ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp);
181 return frame(sp, fp, epc.pc());
182 }
183
184 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
185 address pc = (address) os::Linux::ucontext_get_pc(uc);
186 if (Interpreter::contains(pc)) {
187 // interpreter performs stack banging after the fixed frame header has
188 // been generated while the compilers perform it before. To maintain
189 // semantic consistency between interpreted and compiled frames, the
190 // method returns the Java sender of the current frame.
191 *fr = os::fetch_frame_from_ucontext(thread, uc);
192 assert(fr->safe_for_sender(thread), "Safety check");
193 if (!fr->is_first_java_frame()) {
194 *fr = fr->java_sender();
195 }
196 } else {
197 // more complex code with compiled code
198 assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
199 CodeBlob* cb = CodeCache::find_blob(pc);
200 if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
201 // Not sure where the pc points to, fallback to default
202 // stack overflow handling
203 return false;
204 } else {
205 // in compiled code, the stack banging is performed just after the return pc
206 // has been pushed on the stack
207 intptr_t* fp = os::Linux::ucontext_get_fp(uc);
208 intptr_t* sp = os::Linux::ucontext_get_sp(uc);
209 *fr = frame(sp + 1, fp, (address)*sp);
210 if (!fr->is_java_frame()) {
211 assert(fr->safe_for_sender(thread), "Safety check");
212 assert(!fr->is_first_frame(), "Safety check");
213 *fr = fr->java_sender();
214 }
215 }
216 }
217 assert(fr->is_java_frame(), "Safety check");
218 return true;
219 }
220
221 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
222 // turned off by -fomit-frame-pointer,
223 frame os::get_sender_for_C_frame(frame* fr) {
224 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
225 }
226
227 intptr_t* _get_previous_fp() {
228 #ifdef SPARC_WORKS
229 register intptr_t **ebp;
230 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
231 #elif defined(__clang__)
232 intptr_t **ebp;
233 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
234 #else
235 register intptr_t **ebp __asm__ (SPELL_REG_FP);
236 #endif
237 return (intptr_t*) *ebp; // we want what it points to.
238 }
239
240
241 frame os::current_frame() {
242 intptr_t* fp = _get_previous_fp();
243 frame myframe((intptr_t*)os::current_stack_pointer(),
244 (intptr_t*)fp,
245 CAST_FROM_FN_PTR(address, os::current_frame));
246 if (os::is_first_C_frame(&myframe)) {
247 // stack is not walkable
248 return frame();
249 } else {
250 return os::get_sender_for_C_frame(&myframe);
251 }
252 }
253
254 // Utility functions
255
256 // From IA32 System Programming Guide
257 enum {
258 trap_page_fault = 0xE
259 };
260
261 extern "C" JNIEXPORT int
262 JVM_handle_linux_signal(int sig,
263 siginfo_t* info,
264 void* ucVoid,
265 int abort_if_unrecognized) {
266 ucontext_t* uc = (ucontext_t*) ucVoid;
267
268 Thread* t = ThreadLocalStorage::get_thread_slow();
269
270 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
271 // (no destructors can be run)
272 os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
273
274 SignalHandlerMark shm(t);
275
276 // Note: it's not uncommon that JNI code uses signal/sigset to install
277 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
278 // or have a SIGILL handler when detecting CPU type). When that happens,
279 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
280 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
281 // that do not require siginfo/ucontext first.
282
283 if (sig == SIGPIPE || sig == SIGXFSZ) {
284 // allow chained handler to go first
285 if (os::Linux::chained_handler(sig, info, ucVoid)) {
286 return true;
287 } else {
288 if (PrintMiscellaneous && (WizardMode || Verbose)) {
289 char buf[64];
290 warning("Ignoring %s - see bugs 4229104 or 646499219",
291 os::exception_name(sig, buf, sizeof(buf)));
292 }
293 return true;
294 }
295 }
296
297 JavaThread* thread = NULL;
298 VMThread* vmthread = NULL;
299 if (os::Linux::signal_handlers_are_installed) {
300 if (t != NULL ){
301 if(t->is_Java_thread()) {
302 thread = (JavaThread*)t;
303 }
304 else if(t->is_VM_thread()){
305 vmthread = (VMThread *)t;
306 }
307 }
308 }
309 /*
310 NOTE: does not seem to work on linux.
311 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
312 // can't decode this kind of signal
313 info = NULL;
314 } else {
315 assert(sig == info->si_signo, "bad siginfo");
316 }
317 */
318 // decide if this trap can be handled by a stub
319 address stub = NULL;
320
321 address pc = NULL;
322
323 //%note os_trap_1
324 if (info != NULL && uc != NULL && thread != NULL) {
325 pc = (address) os::Linux::ucontext_get_pc(uc);
326
327 if (StubRoutines::is_safefetch_fault(pc)) {
328 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
329 return 1;
330 }
331
332 #ifndef AMD64
333 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
334 // This can happen in any running code (currently more frequently in
335 // interpreter code but has been seen in compiled code)
336 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
337 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
338 "to unstable signal handling in this distribution.");
339 }
340 #endif // AMD64
341
342 // Handle ALL stack overflow variations here
343 if (sig == SIGSEGV) {
344 address addr = (address) info->si_addr;
345
346 // check if fault address is within thread stack
347 if (addr < thread->stack_base() &&
348 addr >= thread->stack_base() - thread->stack_size()) {
349 // stack overflow
350 if (thread->in_stack_yellow_zone(addr)) {
351 if (thread->thread_state() == _thread_in_Java) {
352 if (thread->in_stack_reserved_zone(addr)) {
353 frame fr;
354 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
355 assert(fr.is_java_frame(), "Must be a Java frame");
356 frame activation =
357 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
358 if (activation.sp() != NULL) {
359 thread->disable_stack_reserved_zone();
360 if (activation.is_interpreted_frame()) {
361 thread->set_reserved_stack_activation(
362 activation.fp() + frame::interpreter_frame_initial_sp_offset);
363 } else {
364 thread->set_reserved_stack_activation(activation.unextended_sp());
365 }
366 return 1;
367 }
368 }
369 }
370 // Throw a stack overflow exception. Guard pages will be reenabled
371 // while unwinding the stack.
372 thread->disable_stack_yellow_zone();
373 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
374 } else {
375 // Thread was in the vm or native code. Return and try to finish.
376 thread->disable_stack_yellow_zone();
377 return 1;
378 }
379 } else if (thread->in_stack_red_zone(addr)) {
380 // Fatal red zone violation. Disable the guard pages and fall through
381 // to handle_unexpected_exception way down below.
382 thread->disable_stack_red_zone();
383 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
384
385 // This is a likely cause, but hard to verify. Let's just print
386 // it as a hint.
387 tty->print_raw_cr("Please check if any of your loaded .so files has "
388 "enabled executable stack (see man page execstack(8))");
389 } else {
390 // Accessing stack address below sp may cause SEGV if current
391 // thread has MAP_GROWSDOWN stack. This should only happen when
392 // current thread was created by user code with MAP_GROWSDOWN flag
393 // and then attached to VM. See notes in os_linux.cpp.
394 if (thread->osthread()->expanding_stack() == 0) {
395 thread->osthread()->set_expanding_stack();
396 if (os::Linux::manually_expand_stack(thread, addr)) {
397 thread->osthread()->clear_expanding_stack();
398 return 1;
399 }
400 thread->osthread()->clear_expanding_stack();
401 } else {
402 fatal("recursive segv. expanding stack.");
403 }
404 }
405 }
406 }
407
408 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
409 // Verify that OS save/restore AVX registers.
410 stub = VM_Version::cpuinfo_cont_addr();
411 }
412
413 if (thread->thread_state() == _thread_in_Java) {
414 // Java thread running in Java code => find exception handler if any
415 // a fault inside compiled code, the interpreter, or a stub
416
417 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
418 stub = SharedRuntime::get_poll_stub(pc);
419 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
420 // BugId 4454115: A read from a MappedByteBuffer can fault
421 // here if the underlying file has been truncated.
422 // Do not crash the VM in such a case.
423 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
424 nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
425 if (nm != NULL && nm->has_unsafe_access()) {
426 stub = StubRoutines::handler_for_unsafe_access();
427 }
428 }
429 else
430
431 #ifdef AMD64
432 if (sig == SIGFPE &&
433 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
434 stub =
435 SharedRuntime::
436 continuation_for_implicit_exception(thread,
437 pc,
438 SharedRuntime::
439 IMPLICIT_DIVIDE_BY_ZERO);
440 #else
441 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
442 // HACK: si_code does not work on linux 2.2.12-20!!!
443 int op = pc[0];
444 if (op == 0xDB) {
445 // FIST
446 // TODO: The encoding of D2I in i486.ad can cause an exception
447 // prior to the fist instruction if there was an invalid operation
448 // pending. We want to dismiss that exception. From the win_32
449 // side it also seems that if it really was the fist causing
450 // the exception that we do the d2i by hand with different
451 // rounding. Seems kind of weird.
452 // NOTE: that we take the exception at the NEXT floating point instruction.
453 assert(pc[0] == 0xDB, "not a FIST opcode");
454 assert(pc[1] == 0x14, "not a FIST opcode");
455 assert(pc[2] == 0x24, "not a FIST opcode");
456 return true;
457 } else if (op == 0xF7) {
458 // IDIV
459 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
460 } else {
461 // TODO: handle more cases if we are using other x86 instructions
462 // that can generate SIGFPE signal on linux.
463 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
464 fatal("please update this code.");
465 }
466 #endif // AMD64
467 } else if (sig == SIGSEGV &&
468 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
469 // Determination of interpreter/vtable stub/compiled code null exception
470 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
471 }
472 } else if (thread->thread_state() == _thread_in_vm &&
473 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
474 thread->doing_unsafe_access()) {
475 stub = StubRoutines::handler_for_unsafe_access();
476 }
477
478 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
479 // and the heap gets shrunk before the field access.
480 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
481 address addr = JNI_FastGetField::find_slowcase_pc(pc);
482 if (addr != (address)-1) {
483 stub = addr;
484 }
485 }
486
487 // Check to see if we caught the safepoint code in the
488 // process of write protecting the memory serialization page.
489 // It write enables the page immediately after protecting it
490 // so we can just return to retry the write.
491 if ((sig == SIGSEGV) &&
492 os::is_memory_serialize_page(thread, (address) info->si_addr)) {
493 // Block current thread until the memory serialize page permission restored.
494 os::block_on_serialize_page_trap();
495 return true;
496 }
497 }
498
499 #ifndef AMD64
500 // Execution protection violation
501 //
502 // This should be kept as the last step in the triage. We don't
503 // have a dedicated trap number for a no-execute fault, so be
504 // conservative and allow other handlers the first shot.
505 //
506 // Note: We don't test that info->si_code == SEGV_ACCERR here.
507 // this si_code is so generic that it is almost meaningless; and
508 // the si_code for this condition may change in the future.
509 // Furthermore, a false-positive should be harmless.
510 if (UnguardOnExecutionViolation > 0 &&
511 (sig == SIGSEGV || sig == SIGBUS) &&
512 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
513 int page_size = os::vm_page_size();
514 address addr = (address) info->si_addr;
515 address pc = os::Linux::ucontext_get_pc(uc);
516 // Make sure the pc and the faulting address are sane.
517 //
518 // If an instruction spans a page boundary, and the page containing
519 // the beginning of the instruction is executable but the following
520 // page is not, the pc and the faulting address might be slightly
521 // different - we still want to unguard the 2nd page in this case.
522 //
523 // 15 bytes seems to be a (very) safe value for max instruction size.
524 bool pc_is_near_addr =
525 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
526 bool instr_spans_page_boundary =
527 (align_size_down((intptr_t) pc ^ (intptr_t) addr,
528 (intptr_t) page_size) > 0);
529
530 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
531 static volatile address last_addr =
532 (address) os::non_memory_address_word();
533
534 // In conservative mode, don't unguard unless the address is in the VM
535 if (addr != last_addr &&
536 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
537
538 // Set memory to RWX and retry
539 address page_start =
540 (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
541 bool res = os::protect_memory((char*) page_start, page_size,
542 os::MEM_PROT_RWX);
543
544 if (PrintMiscellaneous && Verbose) {
545 char buf[256];
546 jio_snprintf(buf, sizeof(buf), "Execution protection violation "
547 "at " INTPTR_FORMAT
548 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
549 page_start, (res ? "success" : "failed"), errno);
550 tty->print_raw_cr(buf);
551 }
552 stub = pc;
553
554 // Set last_addr so if we fault again at the same address, we don't end
555 // up in an endless loop.
556 //
557 // There are two potential complications here. Two threads trapping at
558 // the same address at the same time could cause one of the threads to
559 // think it already unguarded, and abort the VM. Likely very rare.
560 //
561 // The other race involves two threads alternately trapping at
562 // different addresses and failing to unguard the page, resulting in
563 // an endless loop. This condition is probably even more unlikely than
564 // the first.
565 //
566 // Although both cases could be avoided by using locks or thread local
567 // last_addr, these solutions are unnecessary complication: this
568 // handler is a best-effort safety net, not a complete solution. It is
569 // disabled by default and should only be used as a workaround in case
570 // we missed any no-execute-unsafe VM code.
571
572 last_addr = addr;
573 }
574 }
575 }
576 #endif // !AMD64
577
578 if (stub != NULL) {
579 // save all thread context in case we need to restore it
580 if (thread != NULL) thread->set_saved_exception_pc(pc);
581
582 os::Linux::ucontext_set_pc(uc, stub);
583 return true;
584 }
585
586 // signal-chaining
587 if (os::Linux::chained_handler(sig, info, ucVoid)) {
588 return true;
589 }
590
591 if (!abort_if_unrecognized) {
592 // caller wants another chance, so give it to him
593 return false;
594 }
595
596 if (pc == NULL && uc != NULL) {
597 pc = os::Linux::ucontext_get_pc(uc);
598 }
599
600 // unmask current signal
601 sigset_t newset;
602 sigemptyset(&newset);
603 sigaddset(&newset, sig);
604 sigprocmask(SIG_UNBLOCK, &newset, NULL);
605
606 VMError::report_and_die(t, sig, pc, info, ucVoid);
607
608 ShouldNotReachHere();
609 return true; // Mute compiler
610 }
611
612 void os::Linux::init_thread_fpu_state(void) {
613 #ifndef AMD64
614 // set fpu to 53 bit precision
615 set_fpu_control_word(0x27f);
616 #endif // !AMD64
617 }
618
619 int os::Linux::get_fpu_control_word(void) {
620 #ifdef AMD64
621 return 0;
622 #else
623 int fpu_control;
624 _FPU_GETCW(fpu_control);
625 return fpu_control & 0xffff;
626 #endif // AMD64
627 }
628
629 void os::Linux::set_fpu_control_word(int fpu_control) {
630 #ifndef AMD64
631 _FPU_SETCW(fpu_control);
632 #endif // !AMD64
633 }
634
635 // Check that the linux kernel version is 2.4 or higher since earlier
636 // versions do not support SSE without patches.
637 bool os::supports_sse() {
638 #ifdef AMD64
639 return true;
640 #else
641 struct utsname uts;
642 if( uname(&uts) != 0 ) return false; // uname fails?
643 char *minor_string;
644 int major = strtol(uts.release,&minor_string,10);
645 int minor = strtol(minor_string+1,NULL,10);
646 bool result = (major > 2 || (major==2 && minor >= 4));
647 #ifndef PRODUCT
648 if (PrintMiscellaneous && Verbose) {
649 tty->print("OS version is %d.%d, which %s support SSE/SSE2\n",
650 major,minor, result ? "DOES" : "does NOT");
651 }
652 #endif
653 return result;
654 #endif // AMD64
655 }
656
657 bool os::is_allocatable(size_t bytes) {
658 #ifdef AMD64
659 // unused on amd64?
660 return true;
661 #else
662
663 if (bytes < 2 * G) {
664 return true;
665 }
666
667 char* addr = reserve_memory(bytes, NULL);
668
669 if (addr != NULL) {
670 release_memory(addr, bytes);
671 }
672
673 return addr != NULL;
674 #endif // AMD64
675 }
676
677 ////////////////////////////////////////////////////////////////////////////////
678 // thread stack
679
680 #ifdef AMD64
681 size_t os::Linux::min_stack_allowed = 64 * K;
682 #else
683 size_t os::Linux::min_stack_allowed = (48 DEBUG_ONLY(+4))*K;
684 #endif // AMD64
685
686 // return default stack size for thr_type
687 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
688 // default stack size (compiler thread needs larger stack)
689 #ifdef AMD64
690 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
691 #else
692 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
693 #endif // AMD64
694 return s;
695 }
696
697 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
698 // Creating guard page is very expensive. Java thread has HotSpot
699 // guard page, only enable glibc guard page for non-Java threads.
700 return (thr_type == java_thread ? 0 : page_size());
701 }
702
703 // Java thread:
704 //
705 // Low memory addresses
706 // +------------------------+
707 // | |\ JavaThread created by VM does not have glibc
708 // | glibc guard page | - guard, attached Java thread usually has
709 // | |/ 1 page glibc guard.
710 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
711 // | |\
712 // | HotSpot Guard Pages | - red and yellow pages
713 // | |/
714 // +------------------------+ JavaThread::stack_yellow_zone_base()
715 // | |\
716 // | Normal Stack | -
717 // | |/
718 // P2 +------------------------+ Thread::stack_base()
719 //
720 // Non-Java thread:
721 //
722 // Low memory addresses
723 // +------------------------+
724 // | |\
725 // | glibc guard page | - usually 1 page
726 // | |/
727 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
728 // | |\
729 // | Normal Stack | -
730 // | |/
731 // P2 +------------------------+ Thread::stack_base()
732 //
733 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
734 // pthread_attr_getstack()
735
736 static void current_stack_region(address * bottom, size_t * size) {
737 if (os::Linux::is_initial_thread()) {
738 // initial thread needs special handling because pthread_getattr_np()
739 // may return bogus value.
740 *bottom = os::Linux::initial_thread_stack_bottom();
741 *size = os::Linux::initial_thread_stack_size();
742 } else {
743 pthread_attr_t attr;
744
745 int rslt = pthread_getattr_np(pthread_self(), &attr);
746
747 // JVM needs to know exact stack location, abort if it fails
748 if (rslt != 0) {
749 if (rslt == ENOMEM) {
750 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
751 } else {
752 fatal("pthread_getattr_np failed with errno = %d", rslt);
753 }
754 }
755
756 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
757 fatal("Can not locate current stack attributes!");
758 }
759
760 pthread_attr_destroy(&attr);
761
762 }
763 assert(os::current_stack_pointer() >= *bottom &&
764 os::current_stack_pointer() < *bottom + *size, "just checking");
765 }
766
767 address os::current_stack_base() {
768 address bottom;
769 size_t size;
770 current_stack_region(&bottom, &size);
771 return (bottom + size);
772 }
773
774 size_t os::current_stack_size() {
775 // stack size includes normal stack and HotSpot guard pages
776 address bottom;
777 size_t size;
778 current_stack_region(&bottom, &size);
779 return size;
780 }
781
782 /////////////////////////////////////////////////////////////////////////////
783 // helper functions for fatal error handler
784
785 void os::print_context(outputStream *st, void *context) {
786 if (context == NULL) return;
787
788 ucontext_t *uc = (ucontext_t*)context;
789 st->print_cr("Registers:");
790 #ifdef AMD64
791 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
792 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
793 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
794 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
795 st->cr();
796 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
797 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
798 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
799 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
800 st->cr();
801 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
802 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
803 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
804 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
805 st->cr();
806 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
807 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
808 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
809 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
810 st->cr();
811 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
812 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
813 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
814 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
815 st->cr();
816 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
817 #else
818 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
819 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
820 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
821 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
822 st->cr();
823 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
824 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
825 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
826 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
827 st->cr();
828 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
829 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
830 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
831 #endif // AMD64
832 st->cr();
833 st->cr();
834
835 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
836 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
837 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
838 st->cr();
839
840 // Note: it may be unsafe to inspect memory near pc. For example, pc may
841 // point to garbage if entry point in an nmethod is corrupted. Leave
842 // this at the end, and hope for the best.
843 address pc = os::Linux::ucontext_get_pc(uc);
844 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
845 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
846 }
847
848 void os::print_register_info(outputStream *st, void *context) {
849 if (context == NULL) return;
850
851 ucontext_t *uc = (ucontext_t*)context;
852
853 st->print_cr("Register to memory mapping:");
854 st->cr();
855
856 // this is horrendously verbose but the layout of the registers in the
857 // context does not match how we defined our abstract Register set, so
858 // we can't just iterate through the gregs area
859
860 // this is only for the "general purpose" registers
861
862 #ifdef AMD64
863 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
864 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
865 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
866 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
867 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
868 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
869 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
870 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
871 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
872 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
873 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
874 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
875 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
876 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
877 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
878 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
879 #else
880 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
881 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
882 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
883 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
884 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
885 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
886 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
887 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
888 #endif // AMD64
889
890 st->cr();
891 }
892
893 void os::setup_fpu() {
894 #ifndef AMD64
895 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
896 __asm__ volatile ( "fldcw (%0)" :
897 : "r" (fpu_cntrl) : "memory");
898 #endif // !AMD64
899 }
900
901 #ifndef PRODUCT
902 void os::verify_stack_alignment() {
903 #ifdef AMD64
904 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
905 #endif
906 }
907 #endif
908
909
910 /*
911 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
912 * updates (JDK-8023956).
913 */
914 void os::workaround_expand_exec_shield_cs_limit() {
915 #if defined(IA32)
916 size_t page_size = os::vm_page_size();
917 /*
918 * Take the highest VA the OS will give us and exec
919 *
920 * Although using -(pagesz) as mmap hint works on newer kernel as you would
921 * think, older variants affected by this work-around don't (search forward only).
922 *
923 * On the affected distributions, we understand the memory layout to be:
924 *
925 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
926 *
927 * A few pages south main stack will do it.
928 *
929 * If we are embedded in an app other than launcher (initial != main stack),
930 * we don't have much control or understanding of the address space, just let it slide.
931 */
932 char* hint = (char*) (Linux::initial_thread_stack_bottom() -
933 ((StackReservedPages + StackYellowPages + StackRedPages + 1) * page_size));
934 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
935 if ( (codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true)) ) {
936 return; // No matter, we tried, best effort.
937 }
938
939 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
940
941 if (PrintMiscellaneous && (Verbose || WizardMode)) {
942 tty->print_cr("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
943 }
944
945 // Some code to exec: the 'ret' instruction
946 codebuf[0] = 0xC3;
947
948 // Call the code in the codebuf
949 __asm__ volatile("call *%0" : : "r"(codebuf));
950
951 // keep the page mapped so CS limit isn't reduced.
952 #endif
953 }
954
955 int os::extra_bang_size_in_bytes() {
956 // JDK-8050147 requires the full cache line bang for x86.
957 return VM_Version::L1_line_size();
958 }