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 tty->print("OK, we got the SIGSEGV,on address %p now what?\n", (address) info->si_addr);
442 ucontext_t* uc = (ucontext_t*) ucVoid;
443 address pc = (address) os::Linux::ucontext_get_pc(uc);
444 os::print_context(tty, ucVoid);
445 Universe::heap()->print();
446 if (ShenandoahVerifyReadsToFromSpace) {
447 assert(false, "Illegal read to From Space");
448 } else {
449 assert(false, "Illegal write to From Space");
450 }
451 }
452 }
453
454 #ifndef AMD64
455 // Execution protection violation
456 //
457 // This should be kept as the last step in the triage. We don't
458 // have a dedicated trap number for a no-execute fault, so be
459 // conservative and allow other handlers the first shot.
460 //
461 // Note: We don't test that info->si_code == SEGV_ACCERR here.
462 // this si_code is so generic that it is almost meaningless; and
463 // the si_code for this condition may change in the future.
464 // Furthermore, a false-positive should be harmless.
465 if (UnguardOnExecutionViolation > 0 &&
466 (sig == SIGSEGV || sig == SIGBUS) &&
467 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
468 int page_size = os::vm_page_size();
469 address addr = (address) info->si_addr;
470 address pc = os::Linux::ucontext_get_pc(uc);
471 // Make sure the pc and the faulting address are sane.
472 //
473 // If an instruction spans a page boundary, and the page containing
474 // the beginning of the instruction is executable but the following
475 // page is not, the pc and the faulting address might be slightly
476 // different - we still want to unguard the 2nd page in this case.
477 //
478 // 15 bytes seems to be a (very) safe value for max instruction size.
479 bool pc_is_near_addr =
480 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
481 bool instr_spans_page_boundary =
482 (align_size_down((intptr_t) pc ^ (intptr_t) addr,
483 (intptr_t) page_size) > 0);
484
485 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
486 static volatile address last_addr =
487 (address) os::non_memory_address_word();
488
489 // In conservative mode, don't unguard unless the address is in the VM
490 if (addr != last_addr &&
491 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
492
493 // Set memory to RWX and retry
494 address page_start =
495 (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
496 bool res = os::protect_memory((char*) page_start, page_size,
497 os::MEM_PROT_RWX);
498
499 if (PrintMiscellaneous && Verbose) {
500 char buf[256];
501 jio_snprintf(buf, sizeof(buf), "Execution protection violation "
502 "at " INTPTR_FORMAT
503 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
504 page_start, (res ? "success" : "failed"), errno);
505 tty->print_raw_cr(buf);
506 }
507 stub = pc;
508
509 // Set last_addr so if we fault again at the same address, we don't end
510 // up in an endless loop.
511 //
512 // There are two potential complications here. Two threads trapping at
513 // the same address at the same time could cause one of the threads to
514 // think it already unguarded, and abort the VM. Likely very rare.
515 //
516 // The other race involves two threads alternately trapping at
517 // different addresses and failing to unguard the page, resulting in
518 // an endless loop. This condition is probably even more unlikely than
519 // the first.
520 //
521 // Although both cases could be avoided by using locks or thread local
522 // last_addr, these solutions are unnecessary complication: this
523 // handler is a best-effort safety net, not a complete solution. It is
524 // disabled by default and should only be used as a workaround in case
525 // we missed any no-execute-unsafe VM code.
526
527 last_addr = addr;
528 }
529 }
530 }
531 #endif // !AMD64
532
533 if (stub != NULL) {
534 // save all thread context in case we need to restore it
535 if (thread != NULL) thread->set_saved_exception_pc(pc);
536
537 os::Linux::ucontext_set_pc(uc, stub);
538 return true;
539 }
540
541 // signal-chaining
542 if (os::Linux::chained_handler(sig, info, ucVoid)) {
543 return true;
544 }
545
546 if (!abort_if_unrecognized) {
547 // caller wants another chance, so give it to him
548 return false;
549 }
550
551 if (pc == NULL && uc != NULL) {
552 pc = os::Linux::ucontext_get_pc(uc);
553 }
554
555 // unmask current signal
556 sigset_t newset;
557 sigemptyset(&newset);
558 sigaddset(&newset, sig);
559 sigprocmask(SIG_UNBLOCK, &newset, NULL);
560
561 VMError err(t, sig, pc, info, ucVoid);
562 err.report_and_die();
563
564 ShouldNotReachHere();
565 return true; // Mute compiler
566 }
567
568 void os::Linux::init_thread_fpu_state(void) {
569 #ifndef AMD64
570 // set fpu to 53 bit precision
571 set_fpu_control_word(0x27f);
572 #endif // !AMD64
573 }
574
575 int os::Linux::get_fpu_control_word(void) {
576 #ifdef AMD64
577 return 0;
578 #else
579 int fpu_control;
580 _FPU_GETCW(fpu_control);
581 return fpu_control & 0xffff;
582 #endif // AMD64
583 }
584
585 void os::Linux::set_fpu_control_word(int fpu_control) {
586 #ifndef AMD64
587 _FPU_SETCW(fpu_control);
588 #endif // !AMD64
589 }
590
591 // Check that the linux kernel version is 2.4 or higher since earlier
592 // versions do not support SSE without patches.
593 bool os::supports_sse() {
594 #ifdef AMD64
595 return true;
596 #else
597 struct utsname uts;
598 if( uname(&uts) != 0 ) return false; // uname fails?
599 char *minor_string;
600 int major = strtol(uts.release,&minor_string,10);
601 int minor = strtol(minor_string+1,NULL,10);
602 bool result = (major > 2 || (major==2 && minor >= 4));
603 #ifndef PRODUCT
604 if (PrintMiscellaneous && Verbose) {
605 tty->print("OS version is %d.%d, which %s support SSE/SSE2\n",
606 major,minor, result ? "DOES" : "does NOT");
607 }
608 #endif
609 return result;
610 #endif // AMD64
611 }
612
613 bool os::is_allocatable(size_t bytes) {
614 #ifdef AMD64
615 // unused on amd64?
616 return true;
617 #else
618
619 if (bytes < 2 * G) {
620 return true;
621 }
622
623 char* addr = reserve_memory(bytes, NULL);
624
625 if (addr != NULL) {
626 release_memory(addr, bytes);
627 }
628
629 return addr != NULL;
630 #endif // AMD64
631 }
632
633 ////////////////////////////////////////////////////////////////////////////////
634 // thread stack
635
636 #ifdef AMD64
637 size_t os::Linux::min_stack_allowed = 64 * K;
638 #else
639 size_t os::Linux::min_stack_allowed = (48 DEBUG_ONLY(+4))*K;
640 #endif // AMD64
641
642 // return default stack size for thr_type
643 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
644 // default stack size (compiler thread needs larger stack)
645 #ifdef AMD64
646 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
647 #else
648 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
649 #endif // AMD64
650 return s;
651 }
652
653 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
654 // Creating guard page is very expensive. Java thread has HotSpot
655 // guard page, only enable glibc guard page for non-Java threads.
656 return (thr_type == java_thread ? 0 : page_size());
657 }
658
659 // Java thread:
660 //
661 // Low memory addresses
662 // +------------------------+
663 // | |\ JavaThread created by VM does not have glibc
664 // | glibc guard page | - guard, attached Java thread usually has
665 // | |/ 1 page glibc guard.
666 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
667 // | |\
668 // | HotSpot Guard Pages | - red and yellow pages
669 // | |/
670 // +------------------------+ JavaThread::stack_yellow_zone_base()
671 // | |\
672 // | Normal Stack | -
673 // | |/
674 // P2 +------------------------+ Thread::stack_base()
675 //
676 // Non-Java thread:
677 //
678 // Low memory addresses
679 // +------------------------+
680 // | |\
681 // | glibc guard page | - usually 1 page
682 // | |/
683 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
684 // | |\
685 // | Normal Stack | -
686 // | |/
687 // P2 +------------------------+ Thread::stack_base()
688 //
689 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
690 // pthread_attr_getstack()
691
692 static void current_stack_region(address * bottom, size_t * size) {
693 if (os::Linux::is_initial_thread()) {
694 // initial thread needs special handling because pthread_getattr_np()
695 // may return bogus value.
696 *bottom = os::Linux::initial_thread_stack_bottom();
697 *size = os::Linux::initial_thread_stack_size();
698 } else {
699 pthread_attr_t attr;
700
701 int rslt = pthread_getattr_np(pthread_self(), &attr);
702
703 // JVM needs to know exact stack location, abort if it fails
704 if (rslt != 0) {
705 if (rslt == ENOMEM) {
706 vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
707 } else {
708 fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt));
709 }
710 }
711
712 if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
713 fatal("Can not locate current stack attributes!");
714 }
715
716 pthread_attr_destroy(&attr);
717
718 }
719 assert(os::current_stack_pointer() >= *bottom &&
720 os::current_stack_pointer() < *bottom + *size, "just checking");
721 }
722
723 address os::current_stack_base() {
724 address bottom;
725 size_t size;
726 current_stack_region(&bottom, &size);
727 return (bottom + size);
728 }
729
730 size_t os::current_stack_size() {
731 // stack size includes normal stack and HotSpot guard pages
732 address bottom;
733 size_t size;
734 current_stack_region(&bottom, &size);
735 return size;
736 }
737
738 /////////////////////////////////////////////////////////////////////////////
739 // helper functions for fatal error handler
740
741 void os::print_context(outputStream *st, void *context) {
742 if (context == NULL) return;
743
744 ucontext_t *uc = (ucontext_t*)context;
745 st->print_cr("Registers:");
746 #ifdef AMD64
747 st->print( "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]);
748 st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]);
749 st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]);
750 st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]);
751 st->cr();
752 st->print( "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]);
753 st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]);
754 st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]);
755 st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]);
756 st->cr();
757 st->print( "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]);
758 st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]);
759 st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]);
760 st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]);
761 st->cr();
762 st->print( "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]);
763 st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]);
764 st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]);
765 st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]);
766 st->cr();
767 st->print( "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]);
768 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
769 st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]);
770 st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]);
771 st->cr();
772 st->print(" TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]);
773 #else
774 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
775 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
776 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
777 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
778 st->cr();
779 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
780 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
781 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
782 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
783 st->cr();
784 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
785 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
786 st->print(", CR2=" INTPTR_FORMAT, uc->uc_mcontext.cr2);
787 #endif // AMD64
788 st->cr();
789 st->cr();
790
791 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
792 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
793 print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
794 st->cr();
795
796 // Note: it may be unsafe to inspect memory near pc. For example, pc may
797 // point to garbage if entry point in an nmethod is corrupted. Leave
798 // this at the end, and hope for the best.
799 address pc = os::Linux::ucontext_get_pc(uc);
800 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
801 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
802 }
803
804 void os::print_register_info(outputStream *st, void *context) {
805 if (context == NULL) return;
806
807 ucontext_t *uc = (ucontext_t*)context;
808
809 st->print_cr("Register to memory mapping:");
810 st->cr();
811
812 // this is horrendously verbose but the layout of the registers in the
813 // context does not match how we defined our abstract Register set, so
814 // we can't just iterate through the gregs area
815
816 // this is only for the "general purpose" registers
817
818 #ifdef AMD64
819 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
820 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
821 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
822 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
823 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
824 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
825 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
826 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
827 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
828 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
829 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
830 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
831 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
832 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
833 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
834 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
835 #else
836 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
837 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
838 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
839 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
840 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
841 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
842 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
843 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
844 #endif // AMD64
845
846 st->cr();
847 }
848
849 void os::setup_fpu() {
850 #ifndef AMD64
851 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
852 __asm__ volatile ( "fldcw (%0)" :
853 : "r" (fpu_cntrl) : "memory");
854 #endif // !AMD64
855 }
856
857 #ifndef PRODUCT
858 void os::verify_stack_alignment() {
859 #ifdef AMD64
860 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
861 #endif
862 }
863 #endif
864
865
866 /*
867 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
868 * updates (JDK-8023956).
869 */
870 void os::workaround_expand_exec_shield_cs_limit() {
871 #if defined(IA32)
872 size_t page_size = os::vm_page_size();
873 /*
874 * Take the highest VA the OS will give us and exec
875 *
876 * Although using -(pagesz) as mmap hint works on newer kernel as you would
877 * think, older variants affected by this work-around don't (search forward only).
878 *
879 * On the affected distributions, we understand the memory layout to be:
880 *
881 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
882 *
883 * A few pages south main stack will do it.
884 *
885 * If we are embedded in an app other than launcher (initial != main stack),
886 * we don't have much control or understanding of the address space, just let it slide.
887 */
888 char* hint = (char*) (Linux::initial_thread_stack_bottom() -
889 ((StackYellowPages + StackRedPages + 1) * page_size));
890 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
891 if ( (codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true)) ) {
892 return; // No matter, we tried, best effort.
893 }
894
895 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
896
897 if (PrintMiscellaneous && (Verbose || WizardMode)) {
898 tty->print_cr("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
899 }
900
901 // Some code to exec: the 'ret' instruction
902 codebuf[0] = 0xC3;
903
904 // Call the code in the codebuf
905 __asm__ volatile("call *%0" : : "r"(codebuf));
906
907 // keep the page mapped so CS limit isn't reduced.
908 #endif
909 }
910
911 int os::extra_bang_size_in_bytes() {
912 // JDK-8050147 requires the full cache line bang for x86.
913 return VM_Version::L1_line_size();
914 }