1 /*
2 * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // no precompiled headers
26 #include "jvm.h"
27 #include "asm/macroAssembler.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "code/vtableStubs.hpp"
34 #include "interpreter/interpreter.hpp"
35 #include "memory/allocation.inline.hpp"
36 #include "os_share_linux.hpp"
37 #include "prims/jniFastGetField.hpp"
38 #include "prims/jvm_misc.hpp"
39 #include "runtime/arguments.hpp"
40 #include "runtime/extendedPC.hpp"
41 #include "runtime/frame.inline.hpp"
42 #include "runtime/interfaceSupport.inline.hpp"
43 #include "runtime/java.hpp"
44 #include "runtime/javaCalls.hpp"
45 #include "runtime/mutexLocker.hpp"
46 #include "runtime/osThread.hpp"
47 #include "runtime/sharedRuntime.hpp"
48 #include "runtime/stubRoutines.hpp"
49 #include "runtime/thread.inline.hpp"
50 #include "runtime/timer.hpp"
51 #include "services/memTracker.hpp"
52 #include "utilities/align.hpp"
53 #include "utilities/debug.hpp"
54 #include "utilities/events.hpp"
55 #include "utilities/vmError.hpp"
56
57 // put OS-includes here
58 # include <sys/types.h>
59 # include <sys/mman.h>
60 # include <pthread.h>
61 # include <signal.h>
62 # include <errno.h>
63 # include <dlfcn.h>
64 # include <stdlib.h>
65 # include <stdio.h>
66 # include <unistd.h>
67 # include <sys/resource.h>
68 # include <pthread.h>
69 # include <sys/stat.h>
70 # include <sys/time.h>
71 # include <sys/utsname.h>
72 # include <sys/socket.h>
73 # include <sys/wait.h>
74 # include <pwd.h>
75 # include <poll.h>
76 # include <ucontext.h>
77 #ifndef AMD64
78 # include <fpu_control.h>
79 #endif
80
81 #ifdef AMD64
82 #define REG_SP REG_RSP
83 #define REG_PC REG_RIP
84 #define REG_FP REG_RBP
85 #define SPELL_REG_SP "rsp"
86 #define SPELL_REG_FP "rbp"
87 #else
88 #define REG_SP REG_UESP
89 #define REG_PC REG_EIP
90 #define REG_FP REG_EBP
91 #define SPELL_REG_SP "esp"
92 #define SPELL_REG_FP "ebp"
93 #endif // AMD64
94
95 address os::current_stack_pointer() {
96 #ifdef SPARC_WORKS
97 register void *esp;
98 __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp));
99 return (address) ((char*)esp + sizeof(long)*2);
100 #elif defined(__clang__)
101 intptr_t* esp;
102 __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):);
103 return (address) esp;
104 #else
105 register void *esp __asm__ (SPELL_REG_SP);
106 return (address) esp;
107 #endif
108 }
109
110 char* os::non_memory_address_word() {
111 // Must never look like an address returned by reserve_memory,
112 // even in its subfields (as defined by the CPU immediate fields,
113 // if the CPU splits constants across multiple instructions).
114
115 return (char*) -1;
116 }
117
118 void os::initialize_thread(Thread* thr) {
119 // Nothing to do.
120 }
121
122 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
123 return (address)uc->uc_mcontext.gregs[REG_PC];
124 }
125
126 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
127 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
128 }
129
130 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
131 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
132 }
133
134 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
135 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
136 }
137
138 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
139 // is currently interrupted by SIGPROF.
140 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
141 // frames. Currently we don't do that on Linux, so it's the same as
142 // os::fetch_frame_from_context().
143 // This method is also used for stack overflow signal handling.
144 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
145 const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
146
147 assert(thread != NULL, "just checking");
148 assert(ret_sp != NULL, "just checking");
149 assert(ret_fp != NULL, "just checking");
150
151 return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
152 }
153
154 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
155 intptr_t** ret_sp, intptr_t** ret_fp) {
156
157 ExtendedPC epc;
158 const ucontext_t* uc = (const ucontext_t*)ucVoid;
159
160 if (uc != NULL) {
161 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
162 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
163 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
164 } else {
165 // construct empty ExtendedPC for return value checking
166 epc = ExtendedPC(NULL);
167 if (ret_sp) *ret_sp = (intptr_t *)NULL;
168 if (ret_fp) *ret_fp = (intptr_t *)NULL;
169 }
170
171 return epc;
172 }
173
174 frame os::fetch_frame_from_context(const void* ucVoid) {
175 intptr_t* sp;
176 intptr_t* fp;
177 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
178 return frame(sp, fp, epc.pc());
179 }
180
181 frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) {
182 intptr_t* sp;
183 intptr_t* fp;
184 ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp);
185 return frame(sp, fp, epc.pc());
186 }
187
188 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
189 address pc = (address) os::Linux::ucontext_get_pc(uc);
190 if (Interpreter::contains(pc)) {
191 // interpreter performs stack banging after the fixed frame header has
192 // been generated while the compilers perform it before. To maintain
193 // semantic consistency between interpreted and compiled frames, the
194 // method returns the Java sender of the current frame.
195 *fr = os::fetch_frame_from_ucontext(thread, uc);
196 if (!fr->is_first_java_frame()) {
197 // get_frame_at_stack_banging_point() is only called when we
198 // have well defined stacks so java_sender() calls do not need
199 // to assert safe_for_sender() first.
200 *fr = fr->java_sender();
201 }
202 } else {
203 // more complex code with compiled code
204 assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
205 CodeBlob* cb = CodeCache::find_blob(pc);
206 if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
207 // Not sure where the pc points to, fallback to default
208 // stack overflow handling
209 return false;
210 } else {
211 // in compiled code, the stack banging is performed just after the return pc
212 // has been pushed on the stack
213 intptr_t* fp = os::Linux::ucontext_get_fp(uc);
214 intptr_t* sp = os::Linux::ucontext_get_sp(uc);
215 *fr = frame(sp + 1, fp, (address)*sp);
216 if (!fr->is_java_frame()) {
217 assert(!fr->is_first_frame(), "Safety check");
218 // See java_sender() comment above.
219 *fr = fr->java_sender();
220 }
221 }
222 }
223 assert(fr->is_java_frame(), "Safety check");
224 return true;
225 }
226
227 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
228 // turned off by -fomit-frame-pointer,
229 frame os::get_sender_for_C_frame(frame* fr) {
230 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
231 }
232
233 intptr_t* _get_previous_fp() {
234 #ifdef SPARC_WORKS
235 register intptr_t **ebp;
236 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
237 #elif defined(__clang__)
238 intptr_t **ebp;
239 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
240 #else
241 register intptr_t **ebp __asm__ (SPELL_REG_FP);
242 #endif
243 // ebp is for this frame (_get_previous_fp). We want the ebp for the
244 // caller of os::current_frame*(), so go up two frames. However, for
245 // optimized builds, _get_previous_fp() will be inlined, so only go
246 // up 1 frame in that case.
247 #ifdef _NMT_NOINLINE_
248 return **(intptr_t***)ebp;
249 #else
250 return *ebp;
251 #endif
252 }
253
254
255 frame os::current_frame() {
256 intptr_t* fp = _get_previous_fp();
257 frame myframe((intptr_t*)os::current_stack_pointer(),
258 (intptr_t*)fp,
259 CAST_FROM_FN_PTR(address, os::current_frame));
260 if (os::is_first_C_frame(&myframe)) {
261 // stack is not walkable
262 return frame();
263 } else {
264 return os::get_sender_for_C_frame(&myframe);
265 }
266 }
267
268 // Utility functions
269
270 // From IA32 System Programming Guide
271 enum {
272 trap_page_fault = 0xE
273 };
274
275 extern "C" JNIEXPORT int
276 JVM_handle_linux_signal(int sig,
277 siginfo_t* info,
278 void* ucVoid,
279 int abort_if_unrecognized) {
280 ucontext_t* uc = (ucontext_t*) ucVoid;
281
282 Thread* t = Thread::current_or_null_safe();
283
284 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
285 // (no destructors can be run)
286 os::ThreadCrashProtection::check_crash_protection(sig, t);
287
288 SignalHandlerMark shm(t);
289
290 // Note: it's not uncommon that JNI code uses signal/sigset to install
291 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
292 // or have a SIGILL handler when detecting CPU type). When that happens,
293 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
294 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
295 // that do not require siginfo/ucontext first.
296
297 if (sig == SIGPIPE || sig == SIGXFSZ) {
298 // allow chained handler to go first
299 if (os::Linux::chained_handler(sig, info, ucVoid)) {
300 return true;
301 } else {
302 // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219
303 return true;
304 }
305 }
306
307 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
308 if ( (sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) {
309 handle_assert_poison_fault(ucVoid, info->si_addr);
310 return 1;
311 }
312 #endif
313
314 JavaThread* thread = NULL;
315 VMThread* vmthread = NULL;
316 if (os::Linux::signal_handlers_are_installed) {
317 if (t != NULL ){
318 if(t->is_Java_thread()) {
319 thread = (JavaThread*)t;
320 }
321 else if(t->is_VM_thread()){
322 vmthread = (VMThread *)t;
323 }
324 }
325 }
326 /*
327 NOTE: does not seem to work on linux.
328 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
329 // can't decode this kind of signal
330 info = NULL;
331 } else {
332 assert(sig == info->si_signo, "bad siginfo");
333 }
334 */
335 // decide if this trap can be handled by a stub
336 address stub = NULL;
337
338 address pc = NULL;
339
340 //%note os_trap_1
341 if (info != NULL && uc != NULL && thread != NULL) {
342 pc = (address) os::Linux::ucontext_get_pc(uc);
343
344 if (StubRoutines::is_safefetch_fault(pc)) {
345 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
346 return 1;
347 }
348
349 #ifndef AMD64
350 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
351 // This can happen in any running code (currently more frequently in
352 // interpreter code but has been seen in compiled code)
353 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
354 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
355 "to unstable signal handling in this distribution.");
356 }
357 #endif // AMD64
358
359 // Handle ALL stack overflow variations here
360 if (sig == SIGSEGV) {
361 address addr = (address) info->si_addr;
362
363 // check if fault address is within thread stack
364 if (thread->on_local_stack(addr)) {
365 // stack overflow
366 if (thread->in_stack_yellow_reserved_zone(addr)) {
367 if (thread->thread_state() == _thread_in_Java) {
368 if (thread->in_stack_reserved_zone(addr)) {
369 frame fr;
370 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
371 assert(fr.is_java_frame(), "Must be a Java frame");
372 frame activation =
373 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
374 if (activation.sp() != NULL) {
375 thread->disable_stack_reserved_zone();
376 if (activation.is_interpreted_frame()) {
377 thread->set_reserved_stack_activation((address)(
378 activation.fp() + frame::interpreter_frame_initial_sp_offset));
379 } else {
380 thread->set_reserved_stack_activation((address)activation.unextended_sp());
381 }
382 return 1;
383 }
384 }
385 }
386 // Throw a stack overflow exception. Guard pages will be reenabled
387 // while unwinding the stack.
388 thread->disable_stack_yellow_reserved_zone();
389 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
390 } else {
391 // Thread was in the vm or native code. Return and try to finish.
392 thread->disable_stack_yellow_reserved_zone();
393 return 1;
394 }
395 } else if (thread->in_stack_red_zone(addr)) {
396 // Fatal red zone violation. Disable the guard pages and fall through
397 // to handle_unexpected_exception way down below.
398 thread->disable_stack_red_zone();
399 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
400
401 // This is a likely cause, but hard to verify. Let's just print
402 // it as a hint.
403 tty->print_raw_cr("Please check if any of your loaded .so files has "
404 "enabled executable stack (see man page execstack(8))");
405 } else {
406 // Accessing stack address below sp may cause SEGV if current
407 // thread has MAP_GROWSDOWN stack. This should only happen when
408 // current thread was created by user code with MAP_GROWSDOWN flag
409 // and then attached to VM. See notes in os_linux.cpp.
410 if (thread->osthread()->expanding_stack() == 0) {
411 thread->osthread()->set_expanding_stack();
412 if (os::Linux::manually_expand_stack(thread, addr)) {
413 thread->osthread()->clear_expanding_stack();
414 return 1;
415 }
416 thread->osthread()->clear_expanding_stack();
417 } else {
418 fatal("recursive segv. expanding stack.");
419 }
420 }
421 }
422 }
423
424 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
425 // Verify that OS save/restore AVX registers.
426 stub = VM_Version::cpuinfo_cont_addr();
427 }
428
429 if (thread->thread_state() == _thread_in_Java) {
430 // Java thread running in Java code => find exception handler if any
431 // a fault inside compiled code, the interpreter, or a stub
432
433 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
434 stub = SharedRuntime::get_poll_stub(pc);
435 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
436 // BugId 4454115: A read from a MappedByteBuffer can fault
437 // here if the underlying file has been truncated.
438 // Do not crash the VM in such a case.
439 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
440 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
441 if (nm != NULL && nm->has_unsafe_access()) {
442 address next_pc = Assembler::locate_next_instruction(pc);
443 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
444 }
445 }
446 else
447
448 #ifdef AMD64
449 if (sig == SIGFPE &&
450 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
451 stub =
452 SharedRuntime::
453 continuation_for_implicit_exception(thread,
454 pc,
455 SharedRuntime::
456 IMPLICIT_DIVIDE_BY_ZERO);
457 #else
458 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
459 // HACK: si_code does not work on linux 2.2.12-20!!!
460 int op = pc[0];
461 if (op == 0xDB) {
462 // FIST
463 // TODO: The encoding of D2I in i486.ad can cause an exception
464 // prior to the fist instruction if there was an invalid operation
465 // pending. We want to dismiss that exception. From the win_32
466 // side it also seems that if it really was the fist causing
467 // the exception that we do the d2i by hand with different
468 // rounding. Seems kind of weird.
469 // NOTE: that we take the exception at the NEXT floating point instruction.
470 assert(pc[0] == 0xDB, "not a FIST opcode");
471 assert(pc[1] == 0x14, "not a FIST opcode");
472 assert(pc[2] == 0x24, "not a FIST opcode");
473 return true;
474 } else if (op == 0xF7) {
475 // IDIV
476 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
477 } else {
478 // TODO: handle more cases if we are using other x86 instructions
479 // that can generate SIGFPE signal on linux.
480 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
481 fatal("please update this code.");
482 }
483 #endif // AMD64
484 } else if (sig == SIGSEGV &&
485 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
486 // Determination of interpreter/vtable stub/compiled code null exception
487 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
488 }
489 } else if (thread->thread_state() == _thread_in_vm &&
490 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
491 thread->doing_unsafe_access()) {
492 address next_pc = Assembler::locate_next_instruction(pc);
493 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
494 }
495
496 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
497 // and the heap gets shrunk before the field access.
498 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
499 address addr = JNI_FastGetField::find_slowcase_pc(pc);
500 if (addr != (address)-1) {
501 stub = addr;
502 }
503 }
504
505 // Check to see if we caught the safepoint code in the
506 // process of write protecting the memory serialization page.
507 // It write enables the page immediately after protecting it
508 // so we can just return to retry the write.
509 if ((sig == SIGSEGV) &&
510 os::is_memory_serialize_page(thread, (address) info->si_addr)) {
511 // Block current thread until the memory serialize page permission restored.
512 os::block_on_serialize_page_trap();
513 return true;
514 }
515 }
516
517 #ifndef AMD64
518 // Execution protection violation
519 //
520 // This should be kept as the last step in the triage. We don't
521 // have a dedicated trap number for a no-execute fault, so be
522 // conservative and allow other handlers the first shot.
523 //
524 // Note: We don't test that info->si_code == SEGV_ACCERR here.
525 // this si_code is so generic that it is almost meaningless; and
526 // the si_code for this condition may change in the future.
527 // Furthermore, a false-positive should be harmless.
528 if (UnguardOnExecutionViolation > 0 &&
529 (sig == SIGSEGV || sig == SIGBUS) &&
530 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
531 int page_size = os::vm_page_size();
532 address addr = (address) info->si_addr;
533 address pc = os::Linux::ucontext_get_pc(uc);
534 // Make sure the pc and the faulting address are sane.
535 //
536 // If an instruction spans a page boundary, and the page containing
537 // the beginning of the instruction is executable but the following
538 // page is not, the pc and the faulting address might be slightly
539 // different - we still want to unguard the 2nd page in this case.
540 //
541 // 15 bytes seems to be a (very) safe value for max instruction size.
542 bool pc_is_near_addr =
543 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
544 bool instr_spans_page_boundary =
545 (align_down((intptr_t) pc ^ (intptr_t) addr,
546 (intptr_t) page_size) > 0);
547
548 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
549 static volatile address last_addr =
550 (address) os::non_memory_address_word();
551
552 // In conservative mode, don't unguard unless the address is in the VM
553 if (addr != last_addr &&
554 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
555
556 // Set memory to RWX and retry
557 address page_start = align_down(addr, page_size);
558 bool res = os::protect_memory((char*) page_start, page_size,
559 os::MEM_PROT_RWX);
560
561 log_debug(os)("Execution protection violation "
562 "at " INTPTR_FORMAT
563 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr),
564 p2i(page_start), (res ? "success" : "failed"), errno);
565 stub = pc;
566
567 // Set last_addr so if we fault again at the same address, we don't end
568 // up in an endless loop.
569 //
570 // There are two potential complications here. Two threads trapping at
571 // the same address at the same time could cause one of the threads to
572 // think it already unguarded, and abort the VM. Likely very rare.
573 //
574 // The other race involves two threads alternately trapping at
575 // different addresses and failing to unguard the page, resulting in
576 // an endless loop. This condition is probably even more unlikely than
577 // the first.
578 //
579 // Although both cases could be avoided by using locks or thread local
580 // last_addr, these solutions are unnecessary complication: this
581 // handler is a best-effort safety net, not a complete solution. It is
582 // disabled by default and should only be used as a workaround in case
583 // we missed any no-execute-unsafe VM code.
584
585 last_addr = addr;
586 }
587 }
588 }
589 #endif // !AMD64
590
591 if (stub != NULL) {
592 // save all thread context in case we need to restore it
593 if (thread != NULL) thread->set_saved_exception_pc(pc);
594
595 os::Linux::ucontext_set_pc(uc, stub);
596 return true;
597 }
598
599 // signal-chaining
600 if (os::Linux::chained_handler(sig, info, ucVoid)) {
601 return true;
602 }
603
604 if (!abort_if_unrecognized) {
605 // caller wants another chance, so give it to him
606 return false;
607 }
608
609 if (pc == NULL && uc != NULL) {
610 pc = os::Linux::ucontext_get_pc(uc);
611 }
612
613 // unmask current signal
614 sigset_t newset;
615 sigemptyset(&newset);
616 sigaddset(&newset, sig);
617 sigprocmask(SIG_UNBLOCK, &newset, NULL);
618
619 VMError::report_and_die(t, sig, pc, info, ucVoid);
620
621 ShouldNotReachHere();
622 return true; // Mute compiler
623 }
624
625 void os::Linux::init_thread_fpu_state(void) {
626 #ifndef AMD64
627 // set fpu to 53 bit precision
628 set_fpu_control_word(0x27f);
629 #endif // !AMD64
630 }
631
632 int os::Linux::get_fpu_control_word(void) {
633 #ifdef AMD64
634 return 0;
635 #else
636 int fpu_control;
637 _FPU_GETCW(fpu_control);
638 return fpu_control & 0xffff;
639 #endif // AMD64
640 }
641
642 void os::Linux::set_fpu_control_word(int fpu_control) {
643 #ifndef AMD64
644 _FPU_SETCW(fpu_control);
645 #endif // !AMD64
646 }
647
648 // Check that the linux kernel version is 2.4 or higher since earlier
649 // versions do not support SSE without patches.
650 bool os::supports_sse() {
651 #ifdef AMD64
652 return true;
653 #else
654 struct utsname uts;
655 if( uname(&uts) != 0 ) return false; // uname fails?
656 char *minor_string;
657 int major = strtol(uts.release,&minor_string,10);
658 int minor = strtol(minor_string+1,NULL,10);
659 bool result = (major > 2 || (major==2 && minor >= 4));
660 log_info(os)("OS version is %d.%d, which %s support SSE/SSE2",
661 major,minor, result ? "DOES" : "does NOT");
662 return result;
663 #endif // AMD64
664 }
665
666 bool os::is_allocatable(size_t bytes) {
667 #ifdef AMD64
668 // unused on amd64?
669 return true;
670 #else
671
672 if (bytes < 2 * G) {
673 return true;
674 }
675
676 char* addr = reserve_memory(bytes, NULL);
677
678 if (addr != NULL) {
679 release_memory(addr, bytes);
680 }
681
682 return addr != NULL;
683 #endif // AMD64
684 }
685
686 ////////////////////////////////////////////////////////////////////////////////
687 // thread stack
688
689 // Minimum usable stack sizes required to get to user code. Space for
690 // HotSpot guard pages is added later.
691 size_t os::Posix::_compiler_thread_min_stack_allowed = 48 * K;
692 size_t os::Posix::_java_thread_min_stack_allowed = 40 * K;
693 #ifdef _LP64
694 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
695 #else
696 size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
697 #endif // _LP64
698
699 // return default stack size for thr_type
700 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
701 // default stack size (compiler thread needs larger stack)
702 #ifdef AMD64
703 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
704 #else
705 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
706 #endif // AMD64
707 return s;
708 }
709
710 /////////////////////////////////////////////////////////////////////////////
711 // helper functions for fatal error handler
712
713 void os::print_context(outputStream *st, const void *context) {
714 if (context == NULL) return;
715
716 const ucontext_t *uc = (const ucontext_t*)context;
717 st->print_cr("Registers:");
718 #ifdef AMD64
719 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
720 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
721 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
722 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
723 st->cr();
724 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
725 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
726 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
727 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
728 st->cr();
729 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
730 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
731 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
732 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
733 st->cr();
734 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
735 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
736 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
737 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
738 st->cr();
739 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
740 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
741 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
742 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
743 st->cr();
744 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
745 #else
746 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
747 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
748 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
749 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
750 st->cr();
751 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
752 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
753 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
754 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
755 st->cr();
756 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
757 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
758 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
759 #endif // AMD64
760 st->cr();
761 st->cr();
762
763 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
764 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
765 print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t));
766 st->cr();
767
768 // Note: it may be unsafe to inspect memory near pc. For example, pc may
769 // point to garbage if entry point in an nmethod is corrupted. Leave
770 // this at the end, and hope for the best.
771 address pc = os::Linux::ucontext_get_pc(uc);
772 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
773 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
774 }
775
776 void os::print_register_info(outputStream *st, const void *context) {
777 if (context == NULL) return;
778
779 const ucontext_t *uc = (const ucontext_t*)context;
780
781 st->print_cr("Register to memory mapping:");
782 st->cr();
783
784 // this is horrendously verbose but the layout of the registers in the
785 // context does not match how we defined our abstract Register set, so
786 // we can't just iterate through the gregs area
787
788 // this is only for the "general purpose" registers
789
790 #ifdef AMD64
791 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
792 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
793 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
794 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
795 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
796 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
797 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
798 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
799 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
800 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
801 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
802 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
803 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
804 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
805 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
806 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
807 #else
808 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
809 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
810 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
811 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
812 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
813 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
814 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
815 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
816 #endif // AMD64
817
818 st->cr();
819 }
820
821 void os::setup_fpu() {
822 #ifndef AMD64
823 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
824 __asm__ volatile ( "fldcw (%0)" :
825 : "r" (fpu_cntrl) : "memory");
826 #endif // !AMD64
827 }
828
829 #ifndef PRODUCT
830 void os::verify_stack_alignment() {
831 #ifdef AMD64
832 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
833 #endif
834 }
835 #endif
836
837
838 /*
839 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
840 * updates (JDK-8023956).
841 */
842 void os::workaround_expand_exec_shield_cs_limit() {
843 #if defined(IA32)
844 size_t page_size = os::vm_page_size();
845
846 /*
847 * JDK-8197429
848 *
849 * Expand the stack mapping to the end of the initial stack before
850 * attempting to install the codebuf. This is needed because newer
851 * Linux kernels impose a distance of a megabyte between stack
852 * memory and other memory regions. If we try to install the
853 * codebuf before expanding the stack the installation will appear
854 * to succeed but we'll get a segfault later if we expand the stack
855 * in Java code.
856 *
857 */
858 if (os::is_primordial_thread()) {
859 address limit = Linux::initial_thread_stack_bottom();
860 if (! DisablePrimordialThreadGuardPages) {
861 limit += JavaThread::stack_red_zone_size() +
862 JavaThread::stack_yellow_zone_size();
863 }
864 os::Linux::expand_stack_to(limit);
865 }
866
867 /*
868 * Take the highest VA the OS will give us and exec
869 *
870 * Although using -(pagesz) as mmap hint works on newer kernel as you would
871 * think, older variants affected by this work-around don't (search forward only).
872 *
873 * On the affected distributions, we understand the memory layout to be:
874 *
875 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
876 *
877 * A few pages south main stack will do it.
878 *
879 * If we are embedded in an app other than launcher (initial != main stack),
880 * we don't have much control or understanding of the address space, just let it slide.
881 */
882 char* hint = (char*)(Linux::initial_thread_stack_bottom() -
883 (JavaThread::stack_guard_zone_size() + page_size));
884 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
885
886 if (codebuf == NULL) {
887 // JDK-8197429: There may be a stack gap of one megabyte between
888 // the limit of the stack and the nearest memory region: this is a
889 // Linux kernel workaround for CVE-2017-1000364. If we failed to
890 // map our codebuf, try again at an address one megabyte lower.
891 hint -= 1 * M;
892 codebuf = os::attempt_reserve_memory_at(page_size, hint);
893 }
894
895 if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) {
896 return; // No matter, we tried, best effort.
897 }
898
899 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
900
901 log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
902
903 // Some code to exec: the 'ret' instruction
904 codebuf[0] = 0xC3;
905
906 // Call the code in the codebuf
907 __asm__ volatile("call *%0" : : "r"(codebuf));
908
909 // keep the page mapped so CS limit isn't reduced.
910 #endif
911 }
912
913 int os::extra_bang_size_in_bytes() {
914 // JDK-8050147 requires the full cache line bang for x86.
915 return VM_Version::L1_line_size();
916 }