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