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 register void *esp;
99 __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp));
100 return (address) ((char*)esp + sizeof(long)*2);
101 #elif defined(__clang__)
102 intptr_t* 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 void os::initialize_thread(Thread* thr) {
120 // Nothing to do.
121 }
122
123 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
124 return (address)uc->uc_mcontext.gregs[REG_PC];
125 }
126
127 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
128 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
129 }
130
131 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
132 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
133 }
134
135 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
136 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
137 }
138
139 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
140 // is currently interrupted by SIGPROF.
141 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
142 // frames. Currently we don't do that on Linux, so it's the same as
143 // os::fetch_frame_from_context().
144 // This method is also used for stack overflow signal handling.
145 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
146 const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
147
148 assert(thread != NULL, "just checking");
149 assert(ret_sp != NULL, "just checking");
150 assert(ret_fp != NULL, "just checking");
151
152 return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
153 }
154
155 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
156 intptr_t** ret_sp, intptr_t** ret_fp) {
157
158 ExtendedPC epc;
159 const ucontext_t* uc = (const ucontext_t*)ucVoid;
160
161 if (uc != NULL) {
162 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
163 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
164 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
165 } else {
166 // construct empty ExtendedPC for return value checking
167 epc = ExtendedPC(NULL);
168 if (ret_sp) *ret_sp = (intptr_t *)NULL;
169 if (ret_fp) *ret_fp = (intptr_t *)NULL;
170 }
171
172 return epc;
173 }
174
175 frame os::fetch_frame_from_context(const void* ucVoid) {
176 intptr_t* sp;
177 intptr_t* fp;
178 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
179 return frame(sp, fp, epc.pc());
180 }
181
182 frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) {
183 intptr_t* sp;
184 intptr_t* fp;
185 ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp);
186 return frame(sp, fp, epc.pc());
187 }
188
189 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
190 address pc = (address) os::Linux::ucontext_get_pc(uc);
191 if (Interpreter::contains(pc)) {
192 // interpreter performs stack banging after the fixed frame header has
193 // been generated while the compilers perform it before. To maintain
194 // semantic consistency between interpreted and compiled frames, the
195 // method returns the Java sender of the current frame.
196 *fr = os::fetch_frame_from_ucontext(thread, uc);
197 if (!fr->is_first_java_frame()) {
198 // get_frame_at_stack_banging_point() is only called when we
199 // have well defined stacks so java_sender() calls do not need
200 // to assert safe_for_sender() first.
201 *fr = fr->java_sender();
202 }
203 } else {
204 // more complex code with compiled code
205 assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
206 CodeBlob* cb = CodeCache::find_blob(pc);
207 if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
208 // Not sure where the pc points to, fallback to default
209 // stack overflow handling
210 return false;
211 } else {
212 // in compiled code, the stack banging is performed just after the return pc
213 // has been pushed on the stack
214 intptr_t* fp = os::Linux::ucontext_get_fp(uc);
215 intptr_t* sp = os::Linux::ucontext_get_sp(uc);
216 *fr = frame(sp + 1, fp, (address)*sp);
217 if (!fr->is_java_frame()) {
218 assert(!fr->is_first_frame(), "Safety check");
219 // See java_sender() comment above.
220 *fr = fr->java_sender();
221 }
222 }
223 }
224 assert(fr->is_java_frame(), "Safety check");
225 return true;
226 }
227
228 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
229 // turned off by -fomit-frame-pointer,
230 frame os::get_sender_for_C_frame(frame* fr) {
231 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
232 }
233
234 intptr_t* _get_previous_fp() {
235 #ifdef SPARC_WORKS
236 register intptr_t **ebp;
237 __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
238 #elif defined(__clang__)
239 intptr_t **ebp;
240 __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
241 #else
242 register intptr_t **ebp __asm__ (SPELL_REG_FP);
243 #endif
244 // ebp is for this frame (_get_previous_fp). We want the ebp for the
245 // caller of os::current_frame*(), so go up two frames. However, for
246 // optimized builds, _get_previous_fp() will be inlined, so only go
247 // up 1 frame in that case.
248 #ifdef _NMT_NOINLINE_
249 return **(intptr_t***)ebp;
250 #else
251 return *ebp;
252 #endif
253 }
254
255
256 frame os::current_frame() {
257 intptr_t* fp = _get_previous_fp();
258 frame myframe((intptr_t*)os::current_stack_pointer(),
259 (intptr_t*)fp,
260 CAST_FROM_FN_PTR(address, os::current_frame));
261 if (os::is_first_C_frame(&myframe)) {
262 // stack is not walkable
263 return frame();
264 } else {
265 return os::get_sender_for_C_frame(&myframe);
266 }
267 }
268
269 // Utility functions
270
271 // From IA32 System Programming Guide
272 enum {
273 trap_page_fault = 0xE
274 };
275
276 extern "C" JNIEXPORT int
277 JVM_handle_linux_signal(int sig,
278 siginfo_t* info,
279 void* ucVoid,
280 int abort_if_unrecognized) {
281 ucontext_t* uc = (ucontext_t*) ucVoid;
282
283 Thread* t = Thread::current_or_null_safe();
284
285 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
286 // (no destructors can be run)
287 os::ThreadCrashProtection::check_crash_protection(sig, t);
288
289 SignalHandlerMark shm(t);
290
291 // Note: it's not uncommon that JNI code uses signal/sigset to install
292 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
293 // or have a SIGILL handler when detecting CPU type). When that happens,
294 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
295 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
296 // that do not require siginfo/ucontext first.
297
298 if (sig == SIGPIPE || sig == SIGXFSZ) {
299 // allow chained handler to go first
300 if (os::Linux::chained_handler(sig, info, ucVoid)) {
301 return true;
302 } else {
303 // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219
304 return true;
305 }
306 }
307
308 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
309 if ((sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) {
310 handle_assert_poison_fault(ucVoid, info->si_addr);
311 return 1;
312 }
313 #endif
314
315 JavaThread* thread = NULL;
316 VMThread* vmthread = NULL;
317 if (os::Linux::signal_handlers_are_installed) {
318 if (t != NULL ){
319 if(t->is_Java_thread()) {
320 thread = (JavaThread*)t;
321 }
322 else if(t->is_VM_thread()){
323 vmthread = (VMThread *)t;
324 }
325 }
326 }
327 /*
328 NOTE: does not seem to work on linux.
329 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
330 // can't decode this kind of signal
331 info = NULL;
332 } else {
333 assert(sig == info->si_signo, "bad siginfo");
334 }
335 */
336 // decide if this trap can be handled by a stub
337 address stub = NULL;
338
339 address pc = NULL;
340
341 //%note os_trap_1
342 if (info != NULL && uc != NULL && thread != NULL) {
343 pc = (address) os::Linux::ucontext_get_pc(uc);
344
345 if (StubRoutines::is_safefetch_fault(pc)) {
346 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
347 return 1;
348 }
349
350 #ifndef AMD64
351 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
352 // This can happen in any running code (currently more frequently in
353 // interpreter code but has been seen in compiled code)
354 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
355 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
356 "to unstable signal handling in this distribution.");
357 }
358 #endif // AMD64
359
360 // Handle ALL stack overflow variations here
361 if (sig == SIGSEGV) {
362 address addr = (address) info->si_addr;
363
364 // check if fault address is within thread stack
365 if (thread->on_local_stack(addr)) {
366 // stack overflow
367 if (thread->in_stack_yellow_reserved_zone(addr)) {
368 if (thread->thread_state() == _thread_in_Java) {
369 if (thread->in_stack_reserved_zone(addr)) {
370 frame fr;
371 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
372 assert(fr.is_java_frame(), "Must be a Java frame");
373 frame activation =
374 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
375 if (activation.sp() != NULL) {
376 thread->disable_stack_reserved_zone();
377 if (activation.is_interpreted_frame()) {
378 thread->set_reserved_stack_activation((address)(
379 activation.fp() + frame::interpreter_frame_initial_sp_offset));
380 } else {
381 thread->set_reserved_stack_activation((address)activation.unextended_sp());
382 }
383 return 1;
384 }
385 }
386 }
387 // Throw a stack overflow exception. Guard pages will be reenabled
388 // while unwinding the stack.
389 thread->disable_stack_yellow_reserved_zone();
390 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
391 } else {
392 // Thread was in the vm or native code. Return and try to finish.
393 thread->disable_stack_yellow_reserved_zone();
394 return 1;
395 }
396 } else if (thread->in_stack_red_zone(addr)) {
397 // Fatal red zone violation. Disable the guard pages and fall through
398 // to handle_unexpected_exception way down below.
399 thread->disable_stack_red_zone();
400 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
401
402 // This is a likely cause, but hard to verify. Let's just print
403 // it as a hint.
404 tty->print_raw_cr("Please check if any of your loaded .so files has "
405 "enabled executable stack (see man page execstack(8))");
406 } else {
407 // Accessing stack address below sp may cause SEGV if current
408 // thread has MAP_GROWSDOWN stack. This should only happen when
409 // current thread was created by user code with MAP_GROWSDOWN flag
410 // and then attached to VM. See notes in os_linux.cpp.
411 if (thread->osthread()->expanding_stack() == 0) {
412 thread->osthread()->set_expanding_stack();
413 if (os::Linux::manually_expand_stack(thread, addr)) {
414 thread->osthread()->clear_expanding_stack();
415 return 1;
416 }
417 thread->osthread()->clear_expanding_stack();
418 } else {
419 fatal("recursive segv. expanding stack.");
420 }
421 }
422 }
423 }
424
425 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
426 // Verify that OS save/restore AVX registers.
427 stub = VM_Version::cpuinfo_cont_addr();
428 }
429
430 if (thread->thread_state() == _thread_in_Java) {
431 // Java thread running in Java code => find exception handler if any
432 // a fault inside compiled code, the interpreter, or a stub
433
434 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
435 stub = SharedRuntime::get_poll_stub(pc);
436 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
437 // BugId 4454115: A read from a MappedByteBuffer can fault
438 // here if the underlying file has been truncated.
439 // Do not crash the VM in such a case.
440 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
441 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
442 if (nm != NULL && nm->has_unsafe_access()) {
443 address next_pc = Assembler::locate_next_instruction(pc);
444 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
445 }
446 }
447 else
448
449 #ifdef AMD64
450 if (sig == SIGFPE &&
451 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
452 stub =
453 SharedRuntime::
454 continuation_for_implicit_exception(thread,
455 pc,
456 SharedRuntime::
457 IMPLICIT_DIVIDE_BY_ZERO);
458 #else
459 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
460 // HACK: si_code does not work on linux 2.2.12-20!!!
461 int op = pc[0];
462 if (op == 0xDB) {
463 // FIST
464 // TODO: The encoding of D2I in i486.ad can cause an exception
465 // prior to the fist instruction if there was an invalid operation
466 // pending. We want to dismiss that exception. From the win_32
467 // side it also seems that if it really was the fist causing
468 // the exception that we do the d2i by hand with different
469 // rounding. Seems kind of weird.
470 // NOTE: that we take the exception at the NEXT floating point instruction.
471 assert(pc[0] == 0xDB, "not a FIST opcode");
472 assert(pc[1] == 0x14, "not a FIST opcode");
473 assert(pc[2] == 0x24, "not a FIST opcode");
474 return true;
475 } else if (op == 0xF7) {
476 // IDIV
477 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
478 } else {
479 // TODO: handle more cases if we are using other x86 instructions
480 // that can generate SIGFPE signal on linux.
481 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
482 fatal("please update this code.");
483 }
484 #endif // AMD64
485 } else if (sig == SIGSEGV &&
486 !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
487 // Determination of interpreter/vtable stub/compiled code null exception
488 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
489 }
490 } else if (thread->thread_state() == _thread_in_vm &&
491 sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
492 thread->doing_unsafe_access()) {
493 address next_pc = Assembler::locate_next_instruction(pc);
494 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
495 }
496
497 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
498 // and the heap gets shrunk before the field access.
499 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
500 address addr = JNI_FastGetField::find_slowcase_pc(pc);
501 if (addr != (address)-1) {
502 stub = addr;
503 }
504 }
505
506 // Check to see if we caught the safepoint code in the
507 // process of write protecting the memory serialization page.
508 // It write enables the page immediately after protecting it
509 // so we can just return to retry the write.
510 if ((sig == SIGSEGV) &&
511 os::is_memory_serialize_page(thread, (address) info->si_addr)) {
512 // Block current thread until the memory serialize page permission restored.
513 os::block_on_serialize_page_trap();
514 return true;
515 }
516 }
517
518 #ifndef AMD64
519 // Execution protection violation
520 //
521 // This should be kept as the last step in the triage. We don't
522 // have a dedicated trap number for a no-execute fault, so be
523 // conservative and allow other handlers the first shot.
524 //
525 // Note: We don't test that info->si_code == SEGV_ACCERR here.
526 // this si_code is so generic that it is almost meaningless; and
527 // the si_code for this condition may change in the future.
528 // Furthermore, a false-positive should be harmless.
529 if (UnguardOnExecutionViolation > 0 &&
530 (sig == SIGSEGV || sig == SIGBUS) &&
531 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
532 int page_size = os::vm_page_size();
533 address addr = (address) info->si_addr;
534 address pc = os::Linux::ucontext_get_pc(uc);
535 // Make sure the pc and the faulting address are sane.
536 //
537 // If an instruction spans a page boundary, and the page containing
538 // the beginning of the instruction is executable but the following
539 // page is not, the pc and the faulting address might be slightly
540 // different - we still want to unguard the 2nd page in this case.
541 //
542 // 15 bytes seems to be a (very) safe value for max instruction size.
543 bool pc_is_near_addr =
544 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
545 bool instr_spans_page_boundary =
546 (align_down((intptr_t) pc ^ (intptr_t) addr,
547 (intptr_t) page_size) > 0);
548
549 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
550 static volatile address last_addr =
551 (address) os::non_memory_address_word();
552
553 // In conservative mode, don't unguard unless the address is in the VM
554 if (addr != last_addr &&
555 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
556
557 // Set memory to RWX and retry
558 address page_start = align_down(addr, page_size);
559 bool res = os::protect_memory((char*) page_start, page_size,
560 os::MEM_PROT_RWX);
561
562 log_debug(os)("Execution protection violation "
563 "at " INTPTR_FORMAT
564 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr),
565 p2i(page_start), (res ? "success" : "failed"), errno);
566 stub = pc;
567
568 // Set last_addr so if we fault again at the same address, we don't end
569 // up in an endless loop.
570 //
571 // There are two potential complications here. Two threads trapping at
572 // the same address at the same time could cause one of the threads to
573 // think it already unguarded, and abort the VM. Likely very rare.
574 //
575 // The other race involves two threads alternately trapping at
576 // different addresses and failing to unguard the page, resulting in
577 // an endless loop. This condition is probably even more unlikely than
578 // the first.
579 //
580 // Although both cases could be avoided by using locks or thread local
581 // last_addr, these solutions are unnecessary complication: this
582 // handler is a best-effort safety net, not a complete solution. It is
583 // disabled by default and should only be used as a workaround in case
584 // we missed any no-execute-unsafe VM code.
585
586 last_addr = addr;
587 }
588 }
589 }
590 #endif // !AMD64
591
592 if (stub != NULL) {
593 // save all thread context in case we need to restore it
594 if (thread != NULL) thread->set_saved_exception_pc(pc);
595
596 os::Linux::ucontext_set_pc(uc, stub);
597 return true;
598 }
599
600 // signal-chaining
601 if (os::Linux::chained_handler(sig, info, ucVoid)) {
602 return true;
603 }
604
605 if (!abort_if_unrecognized) {
606 // caller wants another chance, so give it to him
607 return false;
608 }
609
610 if (pc == NULL && uc != NULL) {
611 pc = os::Linux::ucontext_get_pc(uc);
612 }
613
614 // unmask current signal
615 sigset_t newset;
616 sigemptyset(&newset);
617 sigaddset(&newset, sig);
618 sigprocmask(SIG_UNBLOCK, &newset, NULL);
619
620 VMError::report_and_die(t, sig, pc, info, ucVoid);
621
622 ShouldNotReachHere();
623 return true; // Mute compiler
624 }
625
626 void os::Linux::init_thread_fpu_state(void) {
627 #ifndef AMD64
628 // set fpu to 53 bit precision
629 set_fpu_control_word(0x27f);
630 #endif // !AMD64
631 }
632
633 int os::Linux::get_fpu_control_word(void) {
634 #ifdef AMD64
635 return 0;
636 #else
637 int fpu_control;
638 _FPU_GETCW(fpu_control);
639 return fpu_control & 0xffff;
640 #endif // AMD64
641 }
642
643 void os::Linux::set_fpu_control_word(int fpu_control) {
644 #ifndef AMD64
645 _FPU_SETCW(fpu_control);
646 #endif // !AMD64
647 }
648
649 // Check that the linux kernel version is 2.4 or higher since earlier
650 // versions do not support SSE without patches.
651 bool os::supports_sse() {
652 #ifdef AMD64
653 return true;
654 #else
655 struct utsname uts;
656 if( uname(&uts) != 0 ) return false; // uname fails?
657 char *minor_string;
658 int major = strtol(uts.release,&minor_string,10);
659 int minor = strtol(minor_string+1,NULL,10);
660 bool result = (major > 2 || (major==2 && minor >= 4));
661 log_info(os)("OS version is %d.%d, which %s support SSE/SSE2",
662 major,minor, result ? "DOES" : "does NOT");
663 return result;
664 #endif // AMD64
665 }
666
667 bool os::is_allocatable(size_t bytes) {
668 #ifdef AMD64
669 // unused on amd64?
670 return true;
671 #else
672
673 if (bytes < 2 * G) {
674 return true;
675 }
676
677 char* addr = reserve_memory(bytes, NULL);
678
679 if (addr != NULL) {
680 release_memory(addr, bytes);
681 }
682
683 return addr != NULL;
684 #endif // AMD64
685 }
686
687 ////////////////////////////////////////////////////////////////////////////////
688 // thread stack
689
690 // Minimum usable stack sizes required to get to user code. Space for
691 // HotSpot guard pages is added later.
692 size_t os::Posix::_compiler_thread_min_stack_allowed = 48 * K;
693 size_t os::Posix::_java_thread_min_stack_allowed = 40 * K;
694 #ifdef _LP64
695 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
696 #else
697 size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
698 #endif // _LP64
699
700 // return default stack size for thr_type
701 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
702 // default stack size (compiler thread needs larger stack)
703 #ifdef AMD64
704 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
705 #else
706 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
707 #endif // AMD64
708 return s;
709 }
710
711 /////////////////////////////////////////////////////////////////////////////
712 // helper functions for fatal error handler
713
714 void os::print_context(outputStream *st, const void *context) {
715 if (context == NULL) return;
716
717 const ucontext_t *uc = (const ucontext_t*)context;
718 st->print_cr("Registers:");
719 #ifdef AMD64
720 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
721 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
722 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
723 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
724 st->cr();
725 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
726 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
727 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
728 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
729 st->cr();
730 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
731 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
732 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
733 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
734 st->cr();
735 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
736 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
737 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
738 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
739 st->cr();
740 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
741 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
742 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
743 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
744 st->cr();
745 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
746 #else
747 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
748 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
749 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
750 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
751 st->cr();
752 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
753 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
754 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
755 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
756 st->cr();
757 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
758 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
759 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
760 #endif // AMD64
761 st->cr();
762 st->cr();
763
764 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
765 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
766 print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t));
767 st->cr();
768
769 // Note: it may be unsafe to inspect memory near pc. For example, pc may
770 // point to garbage if entry point in an nmethod is corrupted. Leave
771 // this at the end, and hope for the best.
772 address pc = os::Linux::ucontext_get_pc(uc);
773 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
774 print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
775 }
776
777 void os::print_register_info(outputStream *st, const void *context) {
778 if (context == NULL) return;
779
780 const ucontext_t *uc = (const ucontext_t*)context;
781
782 st->print_cr("Register to memory mapping:");
783 st->cr();
784
785 // this is horrendously verbose but the layout of the registers in the
786 // context does not match how we defined our abstract Register set, so
787 // we can't just iterate through the gregs area
788
789 // this is only for the "general purpose" registers
790
791 #ifdef AMD64
792 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
793 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
794 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
795 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
796 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
797 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
798 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
799 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
800 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
801 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
802 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
803 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
804 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
805 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
806 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
807 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
808 #else
809 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
810 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
811 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
812 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
813 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
814 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
815 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
816 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
817 #endif // AMD64
818
819 st->cr();
820 }
821
822 void os::setup_fpu() {
823 #ifndef AMD64
824 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
825 __asm__ volatile ( "fldcw (%0)" :
826 : "r" (fpu_cntrl) : "memory");
827 #endif // !AMD64
828 }
829
830 #ifndef PRODUCT
831 void os::verify_stack_alignment() {
832 #ifdef AMD64
833 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
834 #endif
835 }
836 #endif
837
838
839 /*
840 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
841 * updates (JDK-8023956).
842 */
843 void os::workaround_expand_exec_shield_cs_limit() {
844 #if defined(IA32)
845 size_t page_size = os::vm_page_size();
846
847 /*
848 * JDK-8197429
849 *
850 * Expand the stack mapping to the end of the initial stack before
851 * attempting to install the codebuf. This is needed because newer
852 * Linux kernels impose a distance of a megabyte between stack
853 * memory and other memory regions. If we try to install the
854 * codebuf before expanding the stack the installation will appear
855 * to succeed but we'll get a segfault later if we expand the stack
856 * in Java code.
857 *
858 */
859 if (os::is_primordial_thread()) {
860 address limit = Linux::initial_thread_stack_bottom();
861 if (! DisablePrimordialThreadGuardPages) {
862 limit += JavaThread::stack_red_zone_size() +
863 JavaThread::stack_yellow_zone_size();
864 }
865 os::Linux::expand_stack_to(limit);
866 }
867
868 /*
869 * Take the highest VA the OS will give us and exec
870 *
871 * Although using -(pagesz) as mmap hint works on newer kernel as you would
872 * think, older variants affected by this work-around don't (search forward only).
873 *
874 * On the affected distributions, we understand the memory layout to be:
875 *
876 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
877 *
878 * A few pages south main stack will do it.
879 *
880 * If we are embedded in an app other than launcher (initial != main stack),
881 * we don't have much control or understanding of the address space, just let it slide.
882 */
883 char* hint = (char*)(Linux::initial_thread_stack_bottom() -
884 (JavaThread::stack_guard_zone_size() + page_size));
885 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
886
887 if (codebuf == NULL) {
888 // JDK-8197429: There may be a stack gap of one megabyte between
889 // the limit of the stack and the nearest memory region: this is a
890 // Linux kernel workaround for CVE-2017-1000364. If we failed to
891 // map our codebuf, try again at an address one megabyte lower.
892 hint -= 1 * M;
893 codebuf = os::attempt_reserve_memory_at(page_size, hint);
894 }
895
896 if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) {
897 return; // No matter, we tried, best effort.
898 }
899
900 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
901
902 log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
903
904 // Some code to exec: the 'ret' instruction
905 codebuf[0] = 0xC3;
906
907 // Call the code in the codebuf
908 __asm__ volatile("call *%0" : : "r"(codebuf));
909
910 // keep the page mapped so CS limit isn't reduced.
911 #endif
912 }
913
914 int os::extra_bang_size_in_bytes() {
915 // JDK-8050147 requires the full cache line bang for x86.
916 return VM_Version::L1_line_size();
917 }