1 /*
2 * Copyright (c) 1999, 2020, 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/safepointMechanism.hpp"
49 #include "runtime/sharedRuntime.hpp"
50 #include "runtime/stubRoutines.hpp"
51 #include "runtime/thread.inline.hpp"
52 #include "runtime/timer.hpp"
53 #include "services/memTracker.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/debug.hpp"
56 #include "utilities/events.hpp"
57 #include "utilities/vmError.hpp"
58
59 // put OS-includes here
60 # include <sys/types.h>
61 # include <sys/mman.h>
62 # include <pthread.h>
63 # include <signal.h>
64 # include <errno.h>
65 # include <dlfcn.h>
66 # include <stdlib.h>
67 # include <stdio.h>
68 # include <unistd.h>
69 # include <sys/resource.h>
70 # include <pthread.h>
71 # include <sys/stat.h>
72 # include <sys/time.h>
73 # include <sys/utsname.h>
74 # include <sys/socket.h>
75 # include <sys/wait.h>
76 # include <pwd.h>
77 # include <poll.h>
78 # include <ucontext.h>
79 #ifndef AMD64
80 # include <fpu_control.h>
81 #endif
82
83 #ifdef AMD64
84 #define REG_SP REG_RSP
85 #define REG_PC REG_RIP
86 #define REG_FP REG_RBP
87 #define SPELL_REG_SP "rsp"
88 #define SPELL_REG_FP "rbp"
89 #else
90 #define REG_SP REG_UESP
91 #define REG_PC REG_EIP
92 #define REG_FP REG_EBP
93 #define SPELL_REG_SP "esp"
94 #define SPELL_REG_FP "ebp"
95 #endif // AMD64
96
97 address os::current_stack_pointer() {
98 return (address)__builtin_frame_address(0);
99 }
100
101 char* os::non_memory_address_word() {
102 // Must never look like an address returned by reserve_memory,
103 // even in its subfields (as defined by the CPU immediate fields,
104 // if the CPU splits constants across multiple instructions).
105
106 return (char*) -1;
107 }
108
109 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
110 return (address)uc->uc_mcontext.gregs[REG_PC];
111 }
112
113 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
114 uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;
115 }
116
117 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
118 return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
119 }
120
121 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
122 return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
123 }
124
125 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
126 // is currently interrupted by SIGPROF.
127 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
128 // frames. Currently we don't do that on Linux, so it's the same as
129 // os::fetch_frame_from_context().
130 // This method is also used for stack overflow signal handling.
131 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
132 const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
133
134 assert(thread != NULL, "just checking");
135 assert(ret_sp != NULL, "just checking");
136 assert(ret_fp != NULL, "just checking");
137
138 return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
139 }
140
141 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
142 intptr_t** ret_sp, intptr_t** ret_fp) {
143
144 ExtendedPC epc;
145 const ucontext_t* uc = (const ucontext_t*)ucVoid;
146
147 if (uc != NULL) {
148 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
149 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
150 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
151 } else {
152 // construct empty ExtendedPC for return value checking
153 epc = ExtendedPC(NULL);
154 if (ret_sp) *ret_sp = (intptr_t *)NULL;
155 if (ret_fp) *ret_fp = (intptr_t *)NULL;
156 }
157
158 return epc;
159 }
160
161 frame os::fetch_frame_from_context(const void* ucVoid) {
162 intptr_t* sp;
163 intptr_t* fp;
164 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
165 return frame(sp, fp, epc.pc());
166 }
167
168 frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) {
169 intptr_t* sp;
170 intptr_t* fp;
171 ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp);
172 return frame(sp, fp, epc.pc());
173 }
174
175 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
176 address pc = (address) os::Linux::ucontext_get_pc(uc);
177 if (Interpreter::contains(pc)) {
178 // interpreter performs stack banging after the fixed frame header has
179 // been generated while the compilers perform it before. To maintain
180 // semantic consistency between interpreted and compiled frames, the
181 // method returns the Java sender of the current frame.
182 *fr = os::fetch_frame_from_ucontext(thread, uc);
183 if (!fr->is_first_java_frame()) {
184 // get_frame_at_stack_banging_point() is only called when we
185 // have well defined stacks so java_sender() calls do not need
186 // to assert safe_for_sender() first.
187 *fr = fr->java_sender();
188 }
189 } else {
190 // more complex code with compiled code
191 assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
192 CodeBlob* cb = CodeCache::find_blob(pc);
193 if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
194 // Not sure where the pc points to, fallback to default
195 // stack overflow handling
196 return false;
197 } else {
198 // in compiled code, the stack banging is performed just after the return pc
199 // has been pushed on the stack
200 intptr_t* fp = os::Linux::ucontext_get_fp(uc);
201 intptr_t* sp = os::Linux::ucontext_get_sp(uc);
202 *fr = frame(sp + 1, fp, (address)*sp);
203 if (!fr->is_java_frame()) {
204 assert(!fr->is_first_frame(), "Safety check");
205 // See java_sender() comment above.
206 *fr = fr->java_sender();
207 }
208 }
209 }
210 assert(fr->is_java_frame(), "Safety check");
211 return true;
212 }
213
214 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
215 // turned off by -fomit-frame-pointer,
216 frame os::get_sender_for_C_frame(frame* fr) {
217 return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
218 }
219
220 intptr_t* _get_previous_fp() {
221 #if defined(__clang__)
222 intptr_t **ebp;
223 __asm__ __volatile__ ("mov %%" SPELL_REG_FP ", %0":"=r"(ebp):);
224 #else
225 register intptr_t **ebp __asm__ (SPELL_REG_FP);
226 #endif
227 // ebp is for this frame (_get_previous_fp). We want the ebp for the
228 // caller of os::current_frame*(), so go up two frames. However, for
229 // optimized builds, _get_previous_fp() will be inlined, so only go
230 // up 1 frame in that case.
231 #ifdef _NMT_NOINLINE_
232 return **(intptr_t***)ebp;
233 #else
234 return *ebp;
235 #endif
236 }
237
238
239 frame os::current_frame() {
240 intptr_t* fp = _get_previous_fp();
241 frame myframe((intptr_t*)os::current_stack_pointer(),
242 (intptr_t*)fp,
243 CAST_FROM_FN_PTR(address, os::current_frame));
244 if (os::is_first_C_frame(&myframe)) {
245 // stack is not walkable
246 return frame();
247 } else {
248 return os::get_sender_for_C_frame(&myframe);
249 }
250 }
251
252 // Utility functions
253
254 // From IA32 System Programming Guide
255 enum {
256 trap_page_fault = 0xE
257 };
258
259 extern "C" JNIEXPORT int
260 JVM_handle_linux_signal(int sig,
261 siginfo_t* info,
262 void* ucVoid,
263 int abort_if_unrecognized) {
264 ucontext_t* uc = (ucontext_t*) ucVoid;
265
266 Thread* t = Thread::current_or_null_safe();
267
268 // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
269 // (no destructors can be run)
270 os::ThreadCrashProtection::check_crash_protection(sig, t);
271
272 SignalHandlerMark shm(t);
273
274 // Note: it's not uncommon that JNI code uses signal/sigset to install
275 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
276 // or have a SIGILL handler when detecting CPU type). When that happens,
277 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
278 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
279 // that do not require siginfo/ucontext first.
280
281 if (sig == SIGPIPE || sig == SIGXFSZ) {
282 // allow chained handler to go first
283 if (os::Linux::chained_handler(sig, info, ucVoid)) {
284 return true;
285 } else {
286 // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219
287 return true;
288 }
289 }
290
291 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
292 if ((sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) {
293 if (handle_assert_poison_fault(ucVoid, info->si_addr)) {
294 return 1;
295 }
296 }
297 #endif
298
299 JavaThread* thread = NULL;
300 VMThread* vmthread = NULL;
301 if (os::Linux::signal_handlers_are_installed) {
302 if (t != NULL ){
303 if(t->is_Java_thread()) {
304 thread = (JavaThread*)t;
305 }
306 else if(t->is_VM_thread()){
307 vmthread = (VMThread *)t;
308 }
309 }
310 }
311 /*
312 NOTE: does not seem to work on linux.
313 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
314 // can't decode this kind of signal
315 info = NULL;
316 } else {
317 assert(sig == info->si_signo, "bad siginfo");
318 }
319 */
320 // decide if this trap can be handled by a stub
321 address stub = NULL;
322
323 address pc = NULL;
324
325 //%note os_trap_1
326 if (info != NULL && uc != NULL && thread != NULL) {
327 pc = (address) os::Linux::ucontext_get_pc(uc);
328
329 if (StubRoutines::is_safefetch_fault(pc)) {
330 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
331 return 1;
332 }
333
334 #ifndef AMD64
335 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
336 // This can happen in any running code (currently more frequently in
337 // interpreter code but has been seen in compiled code)
338 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
339 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
340 "to unstable signal handling in this distribution.");
341 }
342 #endif // AMD64
343
344 // Handle ALL stack overflow variations here
345 if (sig == SIGSEGV) {
346 address addr = (address) info->si_addr;
347
348 // check if fault address is within thread stack
349 if (thread->is_in_full_stack(addr)) {
350 // stack overflow
351 if (thread->in_stack_yellow_reserved_zone(addr)) {
352 if (thread->thread_state() == _thread_in_Java) {
353 if (thread->in_stack_reserved_zone(addr)) {
354 frame fr;
355 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
356 assert(fr.is_java_frame(), "Must be a Java frame");
357 frame activation =
358 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
359 if (activation.sp() != NULL) {
360 thread->disable_stack_reserved_zone();
361 if (activation.is_interpreted_frame()) {
362 thread->set_reserved_stack_activation((address)(
363 activation.fp() + frame::interpreter_frame_initial_sp_offset));
364 } else {
365 thread->set_reserved_stack_activation((address)activation.unextended_sp());
366 }
367 return 1;
368 }
369 }
370 }
371 // Throw a stack overflow exception. Guard pages will be reenabled
372 // while unwinding the stack.
373 thread->disable_stack_yellow_reserved_zone();
374 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
375 } else {
376 // Thread was in the vm or native code. Return and try to finish.
377 thread->disable_stack_yellow_reserved_zone();
378 return 1;
379 }
380 } else if (thread->in_stack_red_zone(addr)) {
381 // Fatal red zone violation. Disable the guard pages and fall through
382 // to handle_unexpected_exception way down below.
383 thread->disable_stack_red_zone();
384 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
385
386 // This is a likely cause, but hard to verify. Let's just print
387 // it as a hint.
388 tty->print_raw_cr("Please check if any of your loaded .so files has "
389 "enabled executable stack (see man page execstack(8))");
390 } else {
391 // Accessing stack address below sp may cause SEGV if current
392 // thread has MAP_GROWSDOWN stack. This should only happen when
393 // current thread was created by user code with MAP_GROWSDOWN flag
394 // and then attached to VM. See notes in os_linux.cpp.
395 if (thread->osthread()->expanding_stack() == 0) {
396 thread->osthread()->set_expanding_stack();
397 if (os::Linux::manually_expand_stack(thread, addr)) {
398 thread->osthread()->clear_expanding_stack();
399 return 1;
400 }
401 thread->osthread()->clear_expanding_stack();
402 } else {
403 fatal("recursive segv. expanding stack.");
404 }
405 }
406 }
407 }
408
409 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
410 // Verify that OS save/restore AVX registers.
411 stub = VM_Version::cpuinfo_cont_addr();
412 }
413
414 if (thread->thread_state() == _thread_in_Java) {
415 // Java thread running in Java code => find exception handler if any
416 // a fault inside compiled code, the interpreter, or a stub
417
418 if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
419 stub = SharedRuntime::get_poll_stub(pc);
420 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
421 // BugId 4454115: A read from a MappedByteBuffer can fault
422 // here if the underlying file has been truncated.
423 // Do not crash the VM in such a case.
424 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
425 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
426 bool is_unsafe_arraycopy = thread->doing_unsafe_access() && UnsafeCopyMemory::contains_pc(pc);
427 if ((nm != NULL && nm->has_unsafe_access()) || is_unsafe_arraycopy) {
428 address next_pc = Assembler::locate_next_instruction(pc);
429 if (is_unsafe_arraycopy) {
430 next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
431 }
432 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
433 }
434 }
435 else
436
437 #ifdef AMD64
438 if (sig == SIGFPE &&
439 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
440 stub =
441 SharedRuntime::
442 continuation_for_implicit_exception(thread,
443 pc,
444 SharedRuntime::
445 IMPLICIT_DIVIDE_BY_ZERO);
446 #else
447 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
448 // HACK: si_code does not work on linux 2.2.12-20!!!
449 int op = pc[0];
450 if (op == 0xDB) {
451 // FIST
452 // TODO: The encoding of D2I in i486.ad can cause an exception
453 // prior to the fist instruction if there was an invalid operation
454 // pending. We want to dismiss that exception. From the win_32
455 // side it also seems that if it really was the fist causing
456 // the exception that we do the d2i by hand with different
457 // rounding. Seems kind of weird.
458 // NOTE: that we take the exception at the NEXT floating point instruction.
459 assert(pc[0] == 0xDB, "not a FIST opcode");
460 assert(pc[1] == 0x14, "not a FIST opcode");
461 assert(pc[2] == 0x24, "not a FIST opcode");
462 return true;
463 } else if (op == 0xF7) {
464 // IDIV
465 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
466 } else {
467 // TODO: handle more cases if we are using other x86 instructions
468 // that can generate SIGFPE signal on linux.
469 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
470 fatal("please update this code.");
471 }
472 #endif // AMD64
473 } else if (sig == SIGSEGV &&
474 MacroAssembler::uses_implicit_null_check(info->si_addr)) {
475 // Determination of interpreter/vtable stub/compiled code null exception
476 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
477 }
478 } else if ((thread->thread_state() == _thread_in_vm ||
479 thread->thread_state() == _thread_in_native) &&
480 (sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
481 thread->doing_unsafe_access())) {
482 address next_pc = Assembler::locate_next_instruction(pc);
483 if (UnsafeCopyMemory::contains_pc(pc)) {
484 next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
485 }
486 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
487 }
488
489 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
490 // and the heap gets shrunk before the field access.
491 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
492 address addr = JNI_FastGetField::find_slowcase_pc(pc);
493 if (addr != (address)-1) {
494 stub = addr;
495 }
496 }
497 }
498
499 #ifndef AMD64
500 // Execution protection violation
501 //
502 // This should be kept as the last step in the triage. We don't
503 // have a dedicated trap number for a no-execute fault, so be
504 // conservative and allow other handlers the first shot.
505 //
506 // Note: We don't test that info->si_code == SEGV_ACCERR here.
507 // this si_code is so generic that it is almost meaningless; and
508 // the si_code for this condition may change in the future.
509 // Furthermore, a false-positive should be harmless.
510 if (UnguardOnExecutionViolation > 0 &&
511 (sig == SIGSEGV || sig == SIGBUS) &&
512 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
513 int page_size = os::vm_page_size();
514 address addr = (address) info->si_addr;
515 address pc = os::Linux::ucontext_get_pc(uc);
516 // Make sure the pc and the faulting address are sane.
517 //
518 // If an instruction spans a page boundary, and the page containing
519 // the beginning of the instruction is executable but the following
520 // page is not, the pc and the faulting address might be slightly
521 // different - we still want to unguard the 2nd page in this case.
522 //
523 // 15 bytes seems to be a (very) safe value for max instruction size.
524 bool pc_is_near_addr =
525 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
526 bool instr_spans_page_boundary =
527 (align_down((intptr_t) pc ^ (intptr_t) addr,
528 (intptr_t) page_size) > 0);
529
530 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
531 static volatile address last_addr =
532 (address) os::non_memory_address_word();
533
534 // In conservative mode, don't unguard unless the address is in the VM
535 if (addr != last_addr &&
536 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
537
538 // Set memory to RWX and retry
539 address page_start = align_down(addr, page_size);
540 bool res = os::protect_memory((char*) page_start, page_size,
541 os::MEM_PROT_RWX);
542
543 log_debug(os)("Execution protection violation "
544 "at " INTPTR_FORMAT
545 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr),
546 p2i(page_start), (res ? "success" : "failed"), errno);
547 stub = pc;
548
549 // Set last_addr so if we fault again at the same address, we don't end
550 // up in an endless loop.
551 //
552 // There are two potential complications here. Two threads trapping at
553 // the same address at the same time could cause one of the threads to
554 // think it already unguarded, and abort the VM. Likely very rare.
555 //
556 // The other race involves two threads alternately trapping at
557 // different addresses and failing to unguard the page, resulting in
558 // an endless loop. This condition is probably even more unlikely than
559 // the first.
560 //
561 // Although both cases could be avoided by using locks or thread local
562 // last_addr, these solutions are unnecessary complication: this
563 // handler is a best-effort safety net, not a complete solution. It is
564 // disabled by default and should only be used as a workaround in case
565 // we missed any no-execute-unsafe VM code.
566
567 last_addr = addr;
568 }
569 }
570 }
571 #endif // !AMD64
572
573 if (stub != NULL) {
574 // save all thread context in case we need to restore it
575 if (thread != NULL) thread->set_saved_exception_pc(pc);
576
577 os::Linux::ucontext_set_pc(uc, stub);
578 return true;
579 }
580
581 // signal-chaining
582 if (os::Linux::chained_handler(sig, info, ucVoid)) {
583 return true;
584 }
585
586 if (!abort_if_unrecognized) {
587 // caller wants another chance, so give it to him
588 return false;
589 }
590
591 if (pc == NULL && uc != NULL) {
592 pc = os::Linux::ucontext_get_pc(uc);
593 }
594
595 // unmask current signal
596 sigset_t newset;
597 sigemptyset(&newset);
598 sigaddset(&newset, sig);
599 sigprocmask(SIG_UNBLOCK, &newset, NULL);
600
601 VMError::report_and_die(t, sig, pc, info, ucVoid);
602
603 ShouldNotReachHere();
604 return true; // Mute compiler
605 }
606
607 void os::Linux::init_thread_fpu_state(void) {
608 #ifndef AMD64
609 // set fpu to 53 bit precision
610 set_fpu_control_word(0x27f);
611 #endif // !AMD64
612 }
613
614 int os::Linux::get_fpu_control_word(void) {
615 #ifdef AMD64
616 return 0;
617 #else
618 int fpu_control;
619 _FPU_GETCW(fpu_control);
620 return fpu_control & 0xffff;
621 #endif // AMD64
622 }
623
624 void os::Linux::set_fpu_control_word(int fpu_control) {
625 #ifndef AMD64
626 _FPU_SETCW(fpu_control);
627 #endif // !AMD64
628 }
629
630 // Check that the linux kernel version is 2.4 or higher since earlier
631 // versions do not support SSE without patches.
632 bool os::supports_sse() {
633 #ifdef AMD64
634 return true;
635 #else
636 struct utsname uts;
637 if( uname(&uts) != 0 ) return false; // uname fails?
638 char *minor_string;
639 int major = strtol(uts.release,&minor_string,10);
640 int minor = strtol(minor_string+1,NULL,10);
641 bool result = (major > 2 || (major==2 && minor >= 4));
642 log_info(os)("OS version is %d.%d, which %s support SSE/SSE2",
643 major,minor, result ? "DOES" : "does NOT");
644 return result;
645 #endif // AMD64
646 }
647
648 bool os::is_allocatable(size_t bytes) {
649 #ifdef AMD64
650 // unused on amd64?
651 return true;
652 #else
653
654 if (bytes < 2 * G) {
655 return true;
656 }
657
658 char* addr = reserve_memory(bytes, NULL);
659
660 if (addr != NULL) {
661 release_memory(addr, bytes);
662 }
663
664 return addr != NULL;
665 #endif // AMD64
666 }
667
668 ////////////////////////////////////////////////////////////////////////////////
669 // thread stack
670
671 // Minimum usable stack sizes required to get to user code. Space for
672 // HotSpot guard pages is added later.
673 size_t os::Posix::_compiler_thread_min_stack_allowed = 48 * K;
674 size_t os::Posix::_java_thread_min_stack_allowed = 40 * K;
675 #ifdef _LP64
676 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
677 #else
678 size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
679 #endif // _LP64
680
681 // return default stack size for thr_type
682 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
683 // default stack size (compiler thread needs larger stack)
684 #ifdef AMD64
685 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
686 #else
687 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
688 #endif // AMD64
689 return s;
690 }
691
692 /////////////////////////////////////////////////////////////////////////////
693 // helper functions for fatal error handler
694
695 void os::print_context(outputStream *st, const void *context) {
696 if (context == NULL) return;
697
698 const ucontext_t *uc = (const ucontext_t*)context;
699 st->print_cr("Registers:");
700 #ifdef AMD64
701 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
702 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
703 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
704 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
705 st->cr();
706 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
707 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
708 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
709 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
710 st->cr();
711 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
712 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
713 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
714 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
715 st->cr();
716 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
717 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
718 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
719 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
720 st->cr();
721 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
722 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
723 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
724 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
725 st->cr();
726 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
727 #else
728 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
729 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
730 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
731 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
732 st->cr();
733 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
734 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
735 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
736 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
737 st->cr();
738 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
739 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
740 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
741 #endif // AMD64
742 st->cr();
743 st->cr();
744
745 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
746 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
747 print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t));
748 st->cr();
749
750 // Note: it may be unsafe to inspect memory near pc. For example, pc may
751 // point to garbage if entry point in an nmethod is corrupted. Leave
752 // this at the end, and hope for the best.
753 address pc = os::Linux::ucontext_get_pc(uc);
754 print_instructions(st, pc, sizeof(char));
755 st->cr();
756 }
757
758 void os::print_register_info(outputStream *st, const void *context) {
759 if (context == NULL) return;
760
761 const ucontext_t *uc = (const ucontext_t*)context;
762
763 st->print_cr("Register to memory mapping:");
764 st->cr();
765
766 // this is horrendously verbose but the layout of the registers in the
767 // context does not match how we defined our abstract Register set, so
768 // we can't just iterate through the gregs area
769
770 // this is only for the "general purpose" registers
771
772 #ifdef AMD64
773 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
774 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
775 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
776 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
777 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
778 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
779 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
780 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
781 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
782 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
783 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
784 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
785 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
786 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
787 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
788 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
789 #else
790 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
791 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
792 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
793 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
794 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
795 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
796 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
797 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
798 #endif // AMD64
799
800 st->cr();
801 }
802
803 void os::setup_fpu() {
804 #ifndef AMD64
805 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
806 __asm__ volatile ( "fldcw (%0)" :
807 : "r" (fpu_cntrl) : "memory");
808 #endif // !AMD64
809 }
810
811 #ifndef PRODUCT
812 void os::verify_stack_alignment() {
813 #ifdef AMD64
814 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
815 #endif
816 }
817 #endif
818
819
820 /*
821 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
822 * updates (JDK-8023956).
823 */
824 void os::workaround_expand_exec_shield_cs_limit() {
825 #if defined(IA32)
826 assert(Linux::initial_thread_stack_bottom() != NULL, "sanity");
827 size_t page_size = os::vm_page_size();
828
829 /*
830 * JDK-8197429
831 *
832 * Expand the stack mapping to the end of the initial stack before
833 * attempting to install the codebuf. This is needed because newer
834 * Linux kernels impose a distance of a megabyte between stack
835 * memory and other memory regions. If we try to install the
836 * codebuf before expanding the stack the installation will appear
837 * to succeed but we'll get a segfault later if we expand the stack
838 * in Java code.
839 *
840 */
841 if (os::is_primordial_thread()) {
842 address limit = Linux::initial_thread_stack_bottom();
843 if (! DisablePrimordialThreadGuardPages) {
844 limit += JavaThread::stack_red_zone_size() +
845 JavaThread::stack_yellow_zone_size();
846 }
847 os::Linux::expand_stack_to(limit);
848 }
849
850 /*
851 * Take the highest VA the OS will give us and exec
852 *
853 * Although using -(pagesz) as mmap hint works on newer kernel as you would
854 * think, older variants affected by this work-around don't (search forward only).
855 *
856 * On the affected distributions, we understand the memory layout to be:
857 *
858 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
859 *
860 * A few pages south main stack will do it.
861 *
862 * If we are embedded in an app other than launcher (initial != main stack),
863 * we don't have much control or understanding of the address space, just let it slide.
864 */
865 char* hint = (char*)(Linux::initial_thread_stack_bottom() -
866 (JavaThread::stack_guard_zone_size() + page_size));
867 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
868
869 if (codebuf == NULL) {
870 // JDK-8197429: There may be a stack gap of one megabyte between
871 // the limit of the stack and the nearest memory region: this is a
872 // Linux kernel workaround for CVE-2017-1000364. If we failed to
873 // map our codebuf, try again at an address one megabyte lower.
874 hint -= 1 * M;
875 codebuf = os::attempt_reserve_memory_at(page_size, hint);
876 }
877
878 if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) {
879 return; // No matter, we tried, best effort.
880 }
881
882 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
883
884 log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
885
886 // Some code to exec: the 'ret' instruction
887 codebuf[0] = 0xC3;
888
889 // Call the code in the codebuf
890 __asm__ volatile("call *%0" : : "r"(codebuf));
891
892 // keep the page mapped so CS limit isn't reduced.
893 #endif
894 }
895
896 int os::extra_bang_size_in_bytes() {
897 // JDK-8050147 requires the full cache line bang for x86.
898 return VM_Version::L1_line_size();
899 }