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 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
93
94 address os::current_stack_pointer() {
95 #ifdef SPARC_WORKS
96 register void *esp;
97 __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp));
98 return (address) ((char*)esp + sizeof(long)*2);
99 #elif defined(__clang__)
100 intptr_t* esp;
101 __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):);
102 return (address) esp;
103 #else
104 register void *esp __asm__ (SPELL_REG_SP);
105 return (address) esp;
106 #endif
107 }
108
109 char* os::non_memory_address_word() {
110 // Must never look like an address returned by reserve_memory,
111 // even in its subfields (as defined by the CPU immediate fields,
112 // if the CPU splits constants across multiple instructions).
113
114 return (char*) -1;
115 }
116
117 void os::initialize_thread(Thread* thr) {
118 // Nothing to do.
119 }
120
121 address os::Linux::ucontext_get_pc(ucontext_t * uc) {
122 return (address)uc->uc_mcontext.gregs[REG_PC];
123 }
124
125 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
126 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
127 }
128
129 intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) {
130 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
131 }
132
133 intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) {
134 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
135 }
136
137 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
138 // is currently interrupted by SIGPROF.
139 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
140 // frames. Currently we don't do that on Linux, so it's the same as
141 // os::fetch_frame_from_context().
142 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
143 ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
144
145 assert(thread != NULL, "just checking");
146 assert(ret_sp != NULL, "just checking");
147 assert(ret_fp != NULL, "just checking");
148
149 return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
150 }
151
152 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
153 intptr_t** ret_sp, intptr_t** ret_fp) {
154
155 ExtendedPC epc;
156 ucontext_t* uc = (ucontext_t*)ucVoid;
157
158 if (uc != NULL) {
159 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
160 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
161 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
162 } else {
163 // construct empty ExtendedPC for return value checking
164 epc = ExtendedPC(NULL);
165 if (ret_sp) *ret_sp = (intptr_t *)NULL;
166 if (ret_fp) *ret_fp = (intptr_t *)NULL;
167 }
168
169 return epc;
170 }
171
172 frame os::fetch_frame_from_context(void* ucVoid) {
173 intptr_t* sp;
174 intptr_t* fp;
175 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
176 return frame(sp, fp, epc.pc());
177 }
178
179 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
180 // turned off by -fomit-frame-pointer,
181 frame os::get_sender_for_C_frame(frame* fr) {
182 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
183 }
184
185 intptr_t* _get_previous_fp() {
186 #ifdef SPARC_WORKS
187 register intptr_t **ebp;
188 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
189 #elif defined(__clang__)
190 intptr_t **ebp;
191 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
192 #else
193 register intptr_t **ebp __asm__ (SPELL_REG_FP);
194 #endif
195 return (intptr_t*) *ebp; // we want what it points to.
196 }
197
198
199 frame os::current_frame() {
200 intptr_t* fp = _get_previous_fp();
201 frame myframe((intptr_t*)os::current_stack_pointer(),
202 (intptr_t*)fp,
203 CAST_FROM_FN_PTR(address, os::current_frame));
204 if (os::is_first_C_frame(&myframe)) {
205 // stack is not walkable
206 return frame();
207 } else {
208 return os::get_sender_for_C_frame(&myframe);
209 }
210 }
211
212 // Utility functions
213
214 // From IA32 System Programming Guide
215 enum {
216 trap_page_fault = 0xE
217 };
218
219 extern "C" JNIEXPORT int
220 JVM_handle_linux_signal(int sig,
221 siginfo_t* info,
222 void* ucVoid,
223 int abort_if_unrecognized) {
224 ucontext_t* uc = (ucontext_t*) ucVoid;
225
226 Thread* t = ThreadLocalStorage::get_thread_slow();
227
228 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
229 // (no destructors can be run)
230 os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
231
232 SignalHandlerMark shm(t);
233
234 // Note: it's not uncommon that JNI code uses signal/sigset to install
235 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
236 // or have a SIGILL handler when detecting CPU type). When that happens,
237 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
238 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
239 // that do not require siginfo/ucontext first.
240
241 if (sig == SIGPIPE || sig == SIGXFSZ) {
242 // allow chained handler to go first
243 if (os::Linux::chained_handler(sig, info, ucVoid)) {
244 return true;
245 } else {
246 if (PrintMiscellaneous && (WizardMode || Verbose)) {
247 char buf[64];
248 warning("Ignoring %s - see bugs 4229104 or 646499219",
249 os::exception_name(sig, buf, sizeof(buf)));
250 }
251 return true;
252 }
253 }
254
255 JavaThread* thread = NULL;
256 VMThread* vmthread = NULL;
257 if (os::Linux::signal_handlers_are_installed) {
258 if (t != NULL ){
259 if(t->is_Java_thread()) {
260 thread = (JavaThread*)t;
261 }
262 else if(t->is_VM_thread()){
263 vmthread = (VMThread *)t;
264 }
265 }
266 }
267 /*
268 NOTE: does not seem to work on linux.
269 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
270 // can't decode this kind of signal
271 info = NULL;
272 } else {
273 assert(sig == info->si_signo, "bad siginfo");
274 }
275 */
276 // decide if this trap can be handled by a stub
277 address stub = NULL;
278
279 address pc = NULL;
280
281 //%note os_trap_1
282 if (info != NULL && uc != NULL && thread != NULL) {
283 pc = (address) os::Linux::ucontext_get_pc(uc);
284
285 if (StubRoutines::is_safefetch_fault(pc)) {
286 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
287 return 1;
288 }
289
290 #ifndef AMD64
291 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
292 // This can happen in any running code (currently more frequently in
293 // interpreter code but has been seen in compiled code)
294 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
295 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
296 "to unstable signal handling in this distribution.");
297 }
298 #endif // AMD64
299
300 // Handle ALL stack overflow variations here
301 if (sig == SIGSEGV) {
302 address addr = (address) info->si_addr;
303
304 // check if fault address is within thread stack
305 if (addr < thread->stack_base() &&
306 addr >= thread->stack_base() - thread->stack_size()) {
307 // stack overflow
308 if (thread->in_stack_yellow_zone(addr)) {
309 thread->disable_stack_yellow_zone();
310 if (thread->thread_state() == _thread_in_Java) {
311 // Throw a stack overflow exception. Guard pages will be reenabled
312 // while unwinding the stack.
313 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
314 } else {
315 // Thread was in the vm or native code. Return and try to finish.
316 return 1;
317 }
318 } else if (thread->in_stack_red_zone(addr)) {
319 // Fatal red zone violation. Disable the guard pages and fall through
320 // to handle_unexpected_exception way down below.
321 thread->disable_stack_red_zone();
322 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
323
324 // This is a likely cause, but hard to verify. Let's just print
325 // it as a hint.
326 tty->print_raw_cr("Please check if any of your loaded .so files has "
327 "enabled executable stack (see man page execstack(8))");
328 } else {
329 // Accessing stack address below sp may cause SEGV if current
330 // thread has MAP_GROWSDOWN stack. This should only happen when
331 // current thread was created by user code with MAP_GROWSDOWN flag
332 // and then attached to VM. See notes in os_linux.cpp.
333 if (thread->osthread()->expanding_stack() == 0) {
334 thread->osthread()->set_expanding_stack();
335 if (os::Linux::manually_expand_stack(thread, addr)) {
336 thread->osthread()->clear_expanding_stack();
337 return 1;
338 }
339 thread->osthread()->clear_expanding_stack();
340 } else {
341 fatal("recursive segv. expanding stack.");
342 }
343 }
344 }
345 }
346
347 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
348 // Verify that OS save/restore AVX registers.
349 stub = VM_Version::cpuinfo_cont_addr();
350 }
351
352 if (thread->thread_state() == _thread_in_Java) {
353 // Java thread running in Java code => find exception handler if any
354 // a fault inside compiled code, the interpreter, or a stub
355
356 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
357 stub = SharedRuntime::get_poll_stub(pc);
358 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
359 // BugId 4454115: A read from a MappedByteBuffer can fault
360 // here if the underlying file has been truncated.
361 // Do not crash the VM in such a case.
362 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
363 nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
364 if (nm != NULL && nm->has_unsafe_access()) {
365 stub = StubRoutines::handler_for_unsafe_access();
366 }
367 }
368 else
369
370 #ifdef AMD64
371 if (sig == SIGFPE &&
372 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
373 stub =
374 SharedRuntime::
375 continuation_for_implicit_exception(thread,
376 pc,
377 SharedRuntime::
378 IMPLICIT_DIVIDE_BY_ZERO);
379 #else
380 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
381 // HACK: si_code does not work on linux 2.2.12-20!!!
382 int op = pc[0];
383 if (op == 0xDB) {
384 // FIST
385 // TODO: The encoding of D2I in i486.ad can cause an exception
386 // prior to the fist instruction if there was an invalid operation
387 // pending. We want to dismiss that exception. From the win_32
388 // side it also seems that if it really was the fist causing
389 // the exception that we do the d2i by hand with different
390 // rounding. Seems kind of weird.
391 // NOTE: that we take the exception at the NEXT floating point instruction.
392 assert(pc[0] == 0xDB, "not a FIST opcode");
393 assert(pc[1] == 0x14, "not a FIST opcode");
394 assert(pc[2] == 0x24, "not a FIST opcode");
395 return true;
396 } else if (op == 0xF7) {
397 // IDIV
398 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
399 } else {
400 // TODO: handle more cases if we are using other x86 instructions
401 // that can generate SIGFPE signal on linux.
402 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
403 fatal("please update this code.");
404 }
405 #endif // AMD64
406 } else if (sig == SIGSEGV &&
407 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
408 // Determination of interpreter/vtable stub/compiled code null exception
409 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
410 }
411 } else if (thread->thread_state() == _thread_in_vm &&
412 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
413 thread->doing_unsafe_access()) {
414 stub = StubRoutines::handler_for_unsafe_access();
415 }
416
417 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
418 // and the heap gets shrunk before the field access.
419 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
420 address addr = JNI_FastGetField::find_slowcase_pc(pc);
421 if (addr != (address)-1) {
422 stub = addr;
423 }
424 }
425
426 // Check to see if we caught the safepoint code in the
427 // process of write protecting the memory serialization page.
428 // It write enables the page immediately after protecting it
429 // so we can just return to retry the write.
430 if ((sig == SIGSEGV) &&
431 os::is_memory_serialize_page(thread, (address) info->si_addr)) {
432 // Block current thread until the memory serialize page permission restored.
433 os::block_on_serialize_page_trap();
434 return true;
435 }
436 }
437
438 if ((sig == SIGSEGV) && UseShenandoahGC
439 && (ShenandoahVerifyWritesToFromSpace || ShenandoahVerifyReadsToFromSpace)) {
440 if (Universe::heap()->is_in(info->si_addr)) {
441 ucontext_t* uc = (ucontext_t*) ucVoid;
442 address pc = (address) os::Linux::ucontext_get_pc(uc);
443 os::print_context(tty, ucVoid);
444 Universe::heap()->print();
445 if (ShenandoahVerifyReadsToFromSpace) {
446 assert(false, "Illegal read to From Space");
447 } else {
448 assert(false, "Illegal write to From Space");
449 }
450 }
451 }
452
453 #ifndef AMD64
454 // Execution protection violation
455 //
456 // This should be kept as the last step in the triage. We don't
457 // have a dedicated trap number for a no-execute fault, so be
458 // conservative and allow other handlers the first shot.
459 //
460 // Note: We don't test that info->si_code == SEGV_ACCERR here.
461 // this si_code is so generic that it is almost meaningless; and
462 // the si_code for this condition may change in the future.
463 // Furthermore, a false-positive should be harmless.
464 if (UnguardOnExecutionViolation > 0 &&
465 (sig == SIGSEGV || sig == SIGBUS) &&
466 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
467 int page_size = os::vm_page_size();
468 address addr = (address) info->si_addr;
469 address pc = os::Linux::ucontext_get_pc(uc);
470 // Make sure the pc and the faulting address are sane.
471 //
472 // If an instruction spans a page boundary, and the page containing
473 // the beginning of the instruction is executable but the following
474 // page is not, the pc and the faulting address might be slightly
475 // different - we still want to unguard the 2nd page in this case.
476 //
477 // 15 bytes seems to be a (very) safe value for max instruction size.
478 bool pc_is_near_addr =
479 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
480 bool instr_spans_page_boundary =
481 (align_size_down((intptr_t) pc ^ (intptr_t) addr,
482 (intptr_t) page_size) > 0);
483
484 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
485 static volatile address last_addr =
486 (address) os::non_memory_address_word();
487
488 // In conservative mode, don't unguard unless the address is in the VM
489 if (addr != last_addr &&
490 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
491
492 // Set memory to RWX and retry
493 address page_start =
494 (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
495 bool res = os::protect_memory((char*) page_start, page_size,
496 os::MEM_PROT_RWX);
497
498 if (PrintMiscellaneous && Verbose) {
499 char buf[256];
500 jio_snprintf(buf, sizeof(buf), "Execution protection violation "
501 "at " INTPTR_FORMAT
502 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
503 page_start, (res ? "success" : "failed"), errno);
504 tty->print_raw_cr(buf);
505 }
506 stub = pc;
507
508 // Set last_addr so if we fault again at the same address, we don't end
509 // up in an endless loop.
510 //
511 // There are two potential complications here. Two threads trapping at
512 // the same address at the same time could cause one of the threads to
513 // think it already unguarded, and abort the VM. Likely very rare.
514 //
515 // The other race involves two threads alternately trapping at
516 // different addresses and failing to unguard the page, resulting in
517 // an endless loop. This condition is probably even more unlikely than
518 // the first.
519 //
520 // Although both cases could be avoided by using locks or thread local
521 // last_addr, these solutions are unnecessary complication: this
522 // handler is a best-effort safety net, not a complete solution. It is
523 // disabled by default and should only be used as a workaround in case
524 // we missed any no-execute-unsafe VM code.
525
526 last_addr = addr;
527 }
528 }
529 }
530 #endif // !AMD64
531
532 if (stub != NULL) {
533 // save all thread context in case we need to restore it
534 if (thread != NULL) thread->set_saved_exception_pc(pc);
535
536 os::Linux::ucontext_set_pc(uc, stub);
537 return true;
538 }
539
540 // signal-chaining
541 if (os::Linux::chained_handler(sig, info, ucVoid)) {
542 return true;
543 }
544
545 if (!abort_if_unrecognized) {
546 // caller wants another chance, so give it to him
547 return false;
548 }
549
550 if (pc == NULL && uc != NULL) {
551 pc = os::Linux::ucontext_get_pc(uc);
552 }
553
554 // unmask current signal
555 sigset_t newset;
556 sigemptyset(&newset);
557 sigaddset(&newset, sig);
558 sigprocmask(SIG_UNBLOCK, &newset, NULL);
559
560 VMError err(t, sig, pc, info, ucVoid);
561 err.report_and_die();
562
563 ShouldNotReachHere();
564 return true; // Mute compiler
565 }
566
567 void os::Linux::init_thread_fpu_state(void) {
568 #ifndef AMD64
569 // set fpu to 53 bit precision
570 set_fpu_control_word(0x27f);
571 #endif // !AMD64
572 }
573
574 int os::Linux::get_fpu_control_word(void) {
575 #ifdef AMD64
576 return 0;
577 #else
578 int fpu_control;
579 _FPU_GETCW(fpu_control);
580 return fpu_control & 0xffff;
581 #endif // AMD64
582 }
583
584 void os::Linux::set_fpu_control_word(int fpu_control) {
585 #ifndef AMD64
586 _FPU_SETCW(fpu_control);
587 #endif // !AMD64
588 }
589
590 // Check that the linux kernel version is 2.4 or higher since earlier
591 // versions do not support SSE without patches.
592 bool os::supports_sse() {
593 #ifdef AMD64
594 return true;
595 #else
596 struct utsname uts;
597 if( uname(&uts) != 0 ) return false; // uname fails?
598 char *minor_string;
599 int major = strtol(uts.release,&minor_string,10);
600 int minor = strtol(minor_string+1,NULL,10);
601 bool result = (major > 2 || (major==2 && minor >= 4));
602 #ifndef PRODUCT
603 if (PrintMiscellaneous && Verbose) {
604 tty->print("OS version is %d.%d, which %s support SSE/SSE2\n",
605 major,minor, result ? "DOES" : "does NOT");
606 }
607 #endif
608 return result;
609 #endif // AMD64
610 }
611
612 bool os::is_allocatable(size_t bytes) {
613 #ifdef AMD64
614 // unused on amd64?
615 return true;
616 #else
617
618 if (bytes < 2 * G) {
619 return true;
620 }
621
622 char* addr = reserve_memory(bytes, NULL);
623
624 if (addr != NULL) {
625 release_memory(addr, bytes);
626 }
627
628 return addr != NULL;
629 #endif // AMD64
630 }
631
632 ////////////////////////////////////////////////////////////////////////////////
633 // thread stack
634
635 #ifdef AMD64
636 size_t os::Linux::min_stack_allowed = 64 * K;
637 #else
638 size_t os::Linux::min_stack_allowed = (48 DEBUG_ONLY(+4))*K;
639 #endif // AMD64
640
641 // return default stack size for thr_type
642 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
643 // default stack size (compiler thread needs larger stack)
644 #ifdef AMD64
645 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
646 #else
647 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
648 #endif // AMD64
649 return s;
650 }
651
652 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
653 // Creating guard page is very expensive. Java thread has HotSpot
654 // guard page, only enable glibc guard page for non-Java threads.
655 return (thr_type == java_thread ? 0 : page_size());
656 }
657
658 // Java thread:
659 //
660 // Low memory addresses
661 // +------------------------+
662 // | |\ JavaThread created by VM does not have glibc
663 // | glibc guard page | - guard, attached Java thread usually has
664 // | |/ 1 page glibc guard.
665 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
666 // | |\
667 // | HotSpot Guard Pages | - red and yellow pages
668 // | |/
669 // +------------------------+ JavaThread::stack_yellow_zone_base()
670 // | |\
671 // | Normal Stack | -
672 // | |/
673 // P2 +------------------------+ Thread::stack_base()
674 //
675 // Non-Java thread:
676 //
677 // Low memory addresses
678 // +------------------------+
679 // | |\
680 // | glibc guard page | - usually 1 page
681 // | |/
682 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
683 // | |\
684 // | Normal Stack | -
685 // | |/
686 // P2 +------------------------+ Thread::stack_base()
687 //
688 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
689 // pthread_attr_getstack()
690
691 static void current_stack_region(address * bottom, size_t * size) {
692 if (os::Linux::is_initial_thread()) {
693 // initial thread needs special handling because pthread_getattr_np()
694 // may return bogus value.
695 *bottom = os::Linux::initial_thread_stack_bottom();
696 *size = os::Linux::initial_thread_stack_size();
697 } else {
698 pthread_attr_t attr;
699
700 int rslt = pthread_getattr_np(pthread_self(), &attr);
701
702 // JVM needs to know exact stack location, abort if it fails
703 if (rslt != 0) {
704 if (rslt == ENOMEM) {
705 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
706 } else {
707 fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt));
708 }
709 }
710
711 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
712 fatal("Can not locate current stack attributes!");
713 }
714
715 pthread_attr_destroy(&attr);
716
717 }
718 assert(os::current_stack_pointer() >= *bottom &&
719 os::current_stack_pointer() < *bottom + *size, "just checking");
720 }
721
722 address os::current_stack_base() {
723 address bottom;
724 size_t size;
725 current_stack_region(&bottom, &size);
726 return (bottom + size);
727 }
728
729 size_t os::current_stack_size() {
730 // stack size includes normal stack and HotSpot guard pages
731 address bottom;
732 size_t size;
733 current_stack_region(&bottom, &size);
734 return size;
735 }
736
737 /////////////////////////////////////////////////////////////////////////////
738 // helper functions for fatal error handler
739
740 void os::print_context(outputStream *st, void *context) {
741 if (context == NULL) return;
742
743 ucontext_t *uc = (ucontext_t*)context;
744 st->print_cr("Registers:");
745 #ifdef AMD64
746 st->print( "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]);
747 st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]);
748 st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]);
749 st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]);
750 st->cr();
751 st->print( "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]);
752 st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]);
753 st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]);
754 st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]);
755 st->cr();
756 st->print( "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]);
757 st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]);
758 st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]);
759 st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]);
760 st->cr();
761 st->print( "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]);
762 st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]);
763 st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]);
764 st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]);
765 st->cr();
766 st->print( "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]);
767 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
768 st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]);
769 st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]);
770 st->cr();
771 st->print(" TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]);
772 #else
773 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
774 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
775 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
776 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
777 st->cr();
778 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
779 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
780 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
781 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
782 st->cr();
783 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
784 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
785 st->print(", CR2=" INTPTR_FORMAT, uc->uc_mcontext.cr2);
786 #endif // AMD64
787 st->cr();
788 st->cr();
789
790 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
791 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
792 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
793 st->cr();
794
795 // Note: it may be unsafe to inspect memory near pc. For example, pc may
796 // point to garbage if entry point in an nmethod is corrupted. Leave
797 // this at the end, and hope for the best.
798 address pc = os::Linux::ucontext_get_pc(uc);
799 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
800 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
801 }
802
803 void os::print_register_info(outputStream *st, void *context) {
804 if (context == NULL) return;
805
806 ucontext_t *uc = (ucontext_t*)context;
807
808 st->print_cr("Register to memory mapping:");
809 st->cr();
810
811 // this is horrendously verbose but the layout of the registers in the
812 // context does not match how we defined our abstract Register set, so
813 // we can't just iterate through the gregs area
814
815 // this is only for the "general purpose" registers
816
817 #ifdef AMD64
818 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
819 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
820 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
821 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
822 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
823 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
824 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
825 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
826 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
827 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
828 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
829 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
830 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
831 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
832 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
833 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
834 #else
835 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
836 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
837 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
838 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
839 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
840 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
841 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
842 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
843 #endif // AMD64
844
845 st->cr();
846 }
847
848 void os::setup_fpu() {
849 #ifndef AMD64
850 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
851 __asm__ volatile ( "fldcw (%0)" :
852 : "r" (fpu_cntrl) : "memory");
853 #endif // !AMD64
854 }
855
856 #ifndef PRODUCT
857 void os::verify_stack_alignment() {
858 #ifdef AMD64
859 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
860 #endif
861 }
862 #endif
863
864
865 /*
866 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
867 * updates (JDK-8023956).
868 */
869 void os::workaround_expand_exec_shield_cs_limit() {
870 #if defined(IA32)
871 size_t page_size = os::vm_page_size();
872 /*
873 * Take the highest VA the OS will give us and exec
874 *
875 * Although using -(pagesz) as mmap hint works on newer kernel as you would
876 * think, older variants affected by this work-around don't (search forward only).
877 *
878 * On the affected distributions, we understand the memory layout to be:
879 *
880 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
881 *
882 * A few pages south main stack will do it.
883 *
884 * If we are embedded in an app other than launcher (initial != main stack),
885 * we don't have much control or understanding of the address space, just let it slide.
886 */
887 char* hint = (char*) (Linux::initial_thread_stack_bottom() -
888 ((StackYellowPages + StackRedPages + 1) * page_size));
889 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
890 if ( (codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true)) ) {
891 return; // No matter, we tried, best effort.
892 }
893
894 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
895
896 if (PrintMiscellaneous && (Verbose || WizardMode)) {
897 tty->print_cr("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
898 }
899
900 // Some code to exec: the 'ret' instruction
901 codebuf[0] = 0xC3;
902
903 // Call the code in the codebuf
904 __asm__ volatile("call *%0" : : "r"(codebuf));
905
906 // keep the page mapped so CS limit isn't reduced.
907 #endif
908 }
909
910 int os::extra_bang_size_in_bytes() {
911 // JDK-8050147 requires the full cache line bang for x86.
912 return VM_Version::L1_line_size();
913 }