1 /*
2 * Copyright (c) 1999, 2019, 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 if (handle_assert_poison_fault(ucVoid, info->si_addr)) {
307 return 1;
308 }
309 }
310 #endif
311
312 JavaThread* thread = NULL;
313 VMThread* vmthread = NULL;
314 if (os::Linux::signal_handlers_are_installed) {
315 if (t != NULL ){
316 if(t->is_Java_thread()) {
317 thread = (JavaThread*)t;
318 }
319 else if(t->is_VM_thread()){
320 vmthread = (VMThread *)t;
321 }
322 }
323 }
324 /*
325 NOTE: does not seem to work on linux.
326 if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
327 // can't decode this kind of signal
328 info = NULL;
329 } else {
330 assert(sig == info->si_signo, "bad siginfo");
331 }
332 */
333 // decide if this trap can be handled by a stub
334 address stub = NULL;
335
336 address pc = NULL;
337
338 //%note os_trap_1
339 if (info != NULL && uc != NULL && thread != NULL) {
340 pc = (address) os::Linux::ucontext_get_pc(uc);
341
342 if (StubRoutines::is_safefetch_fault(pc)) {
343 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
344 return 1;
345 }
346
347 #ifndef AMD64
348 // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
349 // This can happen in any running code (currently more frequently in
350 // interpreter code but has been seen in compiled code)
351 if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
352 fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
353 "to unstable signal handling in this distribution.");
354 }
355 #endif // AMD64
356
357 // Handle ALL stack overflow variations here
358 if (sig == SIGSEGV) {
359 address addr = (address) info->si_addr;
360
361 // check if fault address is within thread stack
362 if (thread->on_local_stack(addr)) {
363 // stack overflow
364 if (thread->in_stack_yellow_reserved_zone(addr)) {
365 if (thread->thread_state() == _thread_in_Java) {
366 if (thread->in_stack_reserved_zone(addr)) {
367 frame fr;
368 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
369 assert(fr.is_java_frame(), "Must be a Java frame");
370 frame activation =
371 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
372 if (activation.sp() != NULL) {
373 thread->disable_stack_reserved_zone();
374 if (activation.is_interpreted_frame()) {
375 thread->set_reserved_stack_activation((address)(
376 activation.fp() + frame::interpreter_frame_initial_sp_offset));
377 } else {
378 thread->set_reserved_stack_activation((address)activation.unextended_sp());
379 }
380 return 1;
381 }
382 }
383 }
384 // Throw a stack overflow exception. Guard pages will be reenabled
385 // while unwinding the stack.
386 thread->disable_stack_yellow_reserved_zone();
387 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
388 } else {
389 // Thread was in the vm or native code. Return and try to finish.
390 thread->disable_stack_yellow_reserved_zone();
391 return 1;
392 }
393 } else if (thread->in_stack_red_zone(addr)) {
394 // Fatal red zone violation. Disable the guard pages and fall through
395 // to handle_unexpected_exception way down below.
396 thread->disable_stack_red_zone();
397 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
398
399 // This is a likely cause, but hard to verify. Let's just print
400 // it as a hint.
401 tty->print_raw_cr("Please check if any of your loaded .so files has "
402 "enabled executable stack (see man page execstack(8))");
403 } else {
404 // Accessing stack address below sp may cause SEGV if current
405 // thread has MAP_GROWSDOWN stack. This should only happen when
406 // current thread was created by user code with MAP_GROWSDOWN flag
407 // and then attached to VM. See notes in os_linux.cpp.
408 if (thread->osthread()->expanding_stack() == 0) {
409 thread->osthread()->set_expanding_stack();
410 if (os::Linux::manually_expand_stack(thread, addr)) {
411 thread->osthread()->clear_expanding_stack();
412 return 1;
413 }
414 thread->osthread()->clear_expanding_stack();
415 } else {
416 fatal("recursive segv. expanding stack.");
417 }
418 }
419 }
420 }
421
422 if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {
423 // Verify that OS save/restore AVX registers.
424 stub = VM_Version::cpuinfo_cont_addr();
425 }
426
427 if (thread->thread_state() == _thread_in_Java) {
428 // Java thread running in Java code => find exception handler if any
429 // a fault inside compiled code, the interpreter, or a stub
430
431 if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
432 stub = SharedRuntime::get_poll_stub(pc);
433 } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
434 // BugId 4454115: A read from a MappedByteBuffer can fault
435 // here if the underlying file has been truncated.
436 // Do not crash the VM in such a case.
437 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
438 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
439 bool is_unsafe_arraycopy = thread->doing_unsafe_access() && UnsafeCopyMemory::contains_pc(pc);
440 if ((nm != NULL && nm->has_unsafe_access()) || is_unsafe_arraycopy) {
441 address next_pc = Assembler::locate_next_instruction(pc);
442 if (is_unsafe_arraycopy) {
443 next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
444 }
445 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
446 }
447 }
448 else
449
450 #ifdef AMD64
451 if (sig == SIGFPE &&
452 (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
453 stub =
454 SharedRuntime::
455 continuation_for_implicit_exception(thread,
456 pc,
457 SharedRuntime::
458 IMPLICIT_DIVIDE_BY_ZERO);
459 #else
460 if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
461 // HACK: si_code does not work on linux 2.2.12-20!!!
462 int op = pc[0];
463 if (op == 0xDB) {
464 // FIST
465 // TODO: The encoding of D2I in i486.ad can cause an exception
466 // prior to the fist instruction if there was an invalid operation
467 // pending. We want to dismiss that exception. From the win_32
468 // side it also seems that if it really was the fist causing
469 // the exception that we do the d2i by hand with different
470 // rounding. Seems kind of weird.
471 // NOTE: that we take the exception at the NEXT floating point instruction.
472 assert(pc[0] == 0xDB, "not a FIST opcode");
473 assert(pc[1] == 0x14, "not a FIST opcode");
474 assert(pc[2] == 0x24, "not a FIST opcode");
475 return true;
476 } else if (op == 0xF7) {
477 // IDIV
478 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
479 } else {
480 // TODO: handle more cases if we are using other x86 instructions
481 // that can generate SIGFPE signal on linux.
482 tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
483 fatal("please update this code.");
484 }
485 #endif // AMD64
486 } else if (sig == SIGSEGV &&
487 MacroAssembler::uses_implicit_null_check(info->si_addr)) {
488 // Determination of interpreter/vtable stub/compiled code null exception
489 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
490 }
491 } else if ((thread->thread_state() == _thread_in_vm ||
492 thread->thread_state() == _thread_in_native) &&
493 (sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
494 thread->doing_unsafe_access())) {
495 address next_pc = Assembler::locate_next_instruction(pc);
496 if (UnsafeCopyMemory::contains_pc(pc)) {
497 next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
498 }
499 stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
500 }
501
502 // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
503 // and the heap gets shrunk before the field access.
504 if ((sig == SIGSEGV) || (sig == SIGBUS)) {
505 address addr = JNI_FastGetField::find_slowcase_pc(pc);
506 if (addr != (address)-1) {
507 stub = addr;
508 }
509 }
510 }
511
512 #ifndef AMD64
513 // Execution protection violation
514 //
515 // This should be kept as the last step in the triage. We don't
516 // have a dedicated trap number for a no-execute fault, so be
517 // conservative and allow other handlers the first shot.
518 //
519 // Note: We don't test that info->si_code == SEGV_ACCERR here.
520 // this si_code is so generic that it is almost meaningless; and
521 // the si_code for this condition may change in the future.
522 // Furthermore, a false-positive should be harmless.
523 if (UnguardOnExecutionViolation > 0 &&
524 (sig == SIGSEGV || sig == SIGBUS) &&
525 uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
526 int page_size = os::vm_page_size();
527 address addr = (address) info->si_addr;
528 address pc = os::Linux::ucontext_get_pc(uc);
529 // Make sure the pc and the faulting address are sane.
530 //
531 // If an instruction spans a page boundary, and the page containing
532 // the beginning of the instruction is executable but the following
533 // page is not, the pc and the faulting address might be slightly
534 // different - we still want to unguard the 2nd page in this case.
535 //
536 // 15 bytes seems to be a (very) safe value for max instruction size.
537 bool pc_is_near_addr =
538 (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
539 bool instr_spans_page_boundary =
540 (align_down((intptr_t) pc ^ (intptr_t) addr,
541 (intptr_t) page_size) > 0);
542
543 if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
544 static volatile address last_addr =
545 (address) os::non_memory_address_word();
546
547 // In conservative mode, don't unguard unless the address is in the VM
548 if (addr != last_addr &&
549 (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
550
551 // Set memory to RWX and retry
552 address page_start = align_down(addr, page_size);
553 bool res = os::protect_memory((char*) page_start, page_size,
554 os::MEM_PROT_RWX);
555
556 log_debug(os)("Execution protection violation "
557 "at " INTPTR_FORMAT
558 ", unguarding " INTPTR_FORMAT ": %s, errno=%d", p2i(addr),
559 p2i(page_start), (res ? "success" : "failed"), errno);
560 stub = pc;
561
562 // Set last_addr so if we fault again at the same address, we don't end
563 // up in an endless loop.
564 //
565 // There are two potential complications here. Two threads trapping at
566 // the same address at the same time could cause one of the threads to
567 // think it already unguarded, and abort the VM. Likely very rare.
568 //
569 // The other race involves two threads alternately trapping at
570 // different addresses and failing to unguard the page, resulting in
571 // an endless loop. This condition is probably even more unlikely than
572 // the first.
573 //
574 // Although both cases could be avoided by using locks or thread local
575 // last_addr, these solutions are unnecessary complication: this
576 // handler is a best-effort safety net, not a complete solution. It is
577 // disabled by default and should only be used as a workaround in case
578 // we missed any no-execute-unsafe VM code.
579
580 last_addr = addr;
581 }
582 }
583 }
584 #endif // !AMD64
585
586 if (stub != NULL) {
587 // save all thread context in case we need to restore it
588 if (thread != NULL) thread->set_saved_exception_pc(pc);
589
590 os::Linux::ucontext_set_pc(uc, stub);
591 return true;
592 }
593
594 // signal-chaining
595 if (os::Linux::chained_handler(sig, info, ucVoid)) {
596 return true;
597 }
598
599 if (!abort_if_unrecognized) {
600 // caller wants another chance, so give it to him
601 return false;
602 }
603
604 if (pc == NULL && uc != NULL) {
605 pc = os::Linux::ucontext_get_pc(uc);
606 }
607
608 // unmask current signal
609 sigset_t newset;
610 sigemptyset(&newset);
611 sigaddset(&newset, sig);
612 sigprocmask(SIG_UNBLOCK, &newset, NULL);
613
614 VMError::report_and_die(t, sig, pc, info, ucVoid);
615
616 ShouldNotReachHere();
617 return true; // Mute compiler
618 }
619
620 void os::Linux::init_thread_fpu_state(void) {
621 #ifndef AMD64
622 // set fpu to 53 bit precision
623 set_fpu_control_word(0x27f);
624 #endif // !AMD64
625 }
626
627 int os::Linux::get_fpu_control_word(void) {
628 #ifdef AMD64
629 return 0;
630 #else
631 int fpu_control;
632 _FPU_GETCW(fpu_control);
633 return fpu_control & 0xffff;
634 #endif // AMD64
635 }
636
637 void os::Linux::set_fpu_control_word(int fpu_control) {
638 #ifndef AMD64
639 _FPU_SETCW(fpu_control);
640 #endif // !AMD64
641 }
642
643 // Check that the linux kernel version is 2.4 or higher since earlier
644 // versions do not support SSE without patches.
645 bool os::supports_sse() {
646 #ifdef AMD64
647 return true;
648 #else
649 struct utsname uts;
650 if( uname(&uts) != 0 ) return false; // uname fails?
651 char *minor_string;
652 int major = strtol(uts.release,&minor_string,10);
653 int minor = strtol(minor_string+1,NULL,10);
654 bool result = (major > 2 || (major==2 && minor >= 4));
655 log_info(os)("OS version is %d.%d, which %s support SSE/SSE2",
656 major,minor, result ? "DOES" : "does NOT");
657 return result;
658 #endif // AMD64
659 }
660
661 bool os::is_allocatable(size_t bytes) {
662 #ifdef AMD64
663 // unused on amd64?
664 return true;
665 #else
666
667 if (bytes < 2 * G) {
668 return true;
669 }
670
671 char* addr = reserve_memory(bytes, NULL);
672
673 if (addr != NULL) {
674 release_memory(addr, bytes);
675 }
676
677 return addr != NULL;
678 #endif // AMD64
679 }
680
681 ////////////////////////////////////////////////////////////////////////////////
682 // thread stack
683
684 // Minimum usable stack sizes required to get to user code. Space for
685 // HotSpot guard pages is added later.
686 size_t os::Posix::_compiler_thread_min_stack_allowed = 48 * K;
687 size_t os::Posix::_java_thread_min_stack_allowed = 40 * K;
688 #ifdef _LP64
689 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
690 #else
691 size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;
692 #endif // _LP64
693
694 // return default stack size for thr_type
695 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
696 // default stack size (compiler thread needs larger stack)
697 #ifdef AMD64
698 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
699 #else
700 size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
701 #endif // AMD64
702 return s;
703 }
704
705 /////////////////////////////////////////////////////////////////////////////
706 // helper functions for fatal error handler
707
708 void os::print_context(outputStream *st, const void *context) {
709 if (context == NULL) return;
710
711 const ucontext_t *uc = (const ucontext_t*)context;
712 st->print_cr("Registers:");
713 #ifdef AMD64
714 st->print( "RAX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RAX]);
715 st->print(", RBX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBX]);
716 st->print(", RCX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RCX]);
717 st->print(", RDX=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDX]);
718 st->cr();
719 st->print( "RSP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSP]);
720 st->print(", RBP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RBP]);
721 st->print(", RSI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RSI]);
722 st->print(", RDI=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RDI]);
723 st->cr();
724 st->print( "R8 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R8]);
725 st->print(", R9 =" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R9]);
726 st->print(", R10=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R10]);
727 st->print(", R11=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R11]);
728 st->cr();
729 st->print( "R12=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R12]);
730 st->print(", R13=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R13]);
731 st->print(", R14=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R14]);
732 st->print(", R15=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_R15]);
733 st->cr();
734 st->print( "RIP=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_RIP]);
735 st->print(", EFLAGS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_EFL]);
736 st->print(", CSGSFS=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_CSGSFS]);
737 st->print(", ERR=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_ERR]);
738 st->cr();
739 st->print(" TRAPNO=" INTPTR_FORMAT, (intptr_t)uc->uc_mcontext.gregs[REG_TRAPNO]);
740 #else
741 st->print( "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
742 st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
743 st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
744 st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
745 st->cr();
746 st->print( "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
747 st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
748 st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
749 st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
750 st->cr();
751 st->print( "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
752 st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
753 st->print(", CR2=" PTR64_FORMAT, (uint64_t)uc->uc_mcontext.cr2);
754 #endif // AMD64
755 st->cr();
756 st->cr();
757
758 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
759 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
760 print_hex_dump(st, (address)sp, (address)(sp + 8), sizeof(intptr_t));
761 st->cr();
762
763 // Note: it may be unsafe to inspect memory near pc. For example, pc may
764 // point to garbage if entry point in an nmethod is corrupted. Leave
765 // this at the end, and hope for the best.
766 address pc = os::Linux::ucontext_get_pc(uc);
767 print_instructions(st, pc, sizeof(char));
768 st->cr();
769 }
770
771 void os::print_register_info(outputStream *st, const void *context) {
772 if (context == NULL) return;
773
774 const ucontext_t *uc = (const ucontext_t*)context;
775
776 st->print_cr("Register to memory mapping:");
777 st->cr();
778
779 // this is horrendously verbose but the layout of the registers in the
780 // context does not match how we defined our abstract Register set, so
781 // we can't just iterate through the gregs area
782
783 // this is only for the "general purpose" registers
784
785 #ifdef AMD64
786 st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
787 st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
788 st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
789 st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
790 st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
791 st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
792 st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
793 st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
794 st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
795 st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
796 st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
797 st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
798 st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
799 st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
800 st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
801 st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
802 #else
803 st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
804 st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
805 st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
806 st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
807 st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
808 st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
809 st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
810 st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
811 #endif // AMD64
812
813 st->cr();
814 }
815
816 void os::setup_fpu() {
817 #ifndef AMD64
818 address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
819 __asm__ volatile ( "fldcw (%0)" :
820 : "r" (fpu_cntrl) : "memory");
821 #endif // !AMD64
822 }
823
824 #ifndef PRODUCT
825 void os::verify_stack_alignment() {
826 #ifdef AMD64
827 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
828 #endif
829 }
830 #endif
831
832
833 /*
834 * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
835 * updates (JDK-8023956).
836 */
837 void os::workaround_expand_exec_shield_cs_limit() {
838 #if defined(IA32)
839 assert(Linux::initial_thread_stack_bottom() != NULL, "sanity");
840 size_t page_size = os::vm_page_size();
841
842 /*
843 * JDK-8197429
844 *
845 * Expand the stack mapping to the end of the initial stack before
846 * attempting to install the codebuf. This is needed because newer
847 * Linux kernels impose a distance of a megabyte between stack
848 * memory and other memory regions. If we try to install the
849 * codebuf before expanding the stack the installation will appear
850 * to succeed but we'll get a segfault later if we expand the stack
851 * in Java code.
852 *
853 */
854 if (os::is_primordial_thread()) {
855 address limit = Linux::initial_thread_stack_bottom();
856 if (! DisablePrimordialThreadGuardPages) {
857 limit += JavaThread::stack_red_zone_size() +
858 JavaThread::stack_yellow_zone_size();
859 }
860 os::Linux::expand_stack_to(limit);
861 }
862
863 /*
864 * Take the highest VA the OS will give us and exec
865 *
866 * Although using -(pagesz) as mmap hint works on newer kernel as you would
867 * think, older variants affected by this work-around don't (search forward only).
868 *
869 * On the affected distributions, we understand the memory layout to be:
870 *
871 * TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
872 *
873 * A few pages south main stack will do it.
874 *
875 * If we are embedded in an app other than launcher (initial != main stack),
876 * we don't have much control or understanding of the address space, just let it slide.
877 */
878 char* hint = (char*)(Linux::initial_thread_stack_bottom() -
879 (JavaThread::stack_guard_zone_size() + page_size));
880 char* codebuf = os::attempt_reserve_memory_at(page_size, hint);
881
882 if (codebuf == NULL) {
883 // JDK-8197429: There may be a stack gap of one megabyte between
884 // the limit of the stack and the nearest memory region: this is a
885 // Linux kernel workaround for CVE-2017-1000364. If we failed to
886 // map our codebuf, try again at an address one megabyte lower.
887 hint -= 1 * M;
888 codebuf = os::attempt_reserve_memory_at(page_size, hint);
889 }
890
891 if ((codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true))) {
892 return; // No matter, we tried, best effort.
893 }
894
895 MemTracker::record_virtual_memory_type((address)codebuf, mtInternal);
896
897 log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
898
899 // Some code to exec: the 'ret' instruction
900 codebuf[0] = 0xC3;
901
902 // Call the code in the codebuf
903 __asm__ volatile("call *%0" : : "r"(codebuf));
904
905 // keep the page mapped so CS limit isn't reduced.
906 #endif
907 }
908
909 int os::extra_bang_size_in_bytes() {
910 // JDK-8050147 requires the full cache line bang for x86.
911 return VM_Version::L1_line_size();
912 }