1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2012, 2016 SAP SE. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 // no precompiled headers
27 #include "jvm.h"
28 #include "asm/assembler.inline.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "code/vtableStubs.hpp"
35 #include "interpreter/interpreter.hpp"
36 #include "memory/allocation.inline.hpp"
37 #include "nativeInst_ppc.hpp"
38 #include "os_share_linux.hpp"
39 #include "prims/jniFastGetField.hpp"
40 #include "prims/jvm_misc.hpp"
41 #include "runtime/arguments.hpp"
42 #include "runtime/extendedPC.hpp"
43 #include "runtime/frame.inline.hpp"
44 #include "runtime/interfaceSupport.hpp"
45 #include "runtime/java.hpp"
46 #include "runtime/javaCalls.hpp"
47 #include "runtime/mutexLocker.hpp"
48 #include "runtime/osThread.hpp"
49 #include "runtime/sharedRuntime.hpp"
50 #include "runtime/stubRoutines.hpp"
51 #include "runtime/thread.inline.hpp"
52 #include "runtime/timer.hpp"
53 #include "utilities/events.hpp"
54 #include "utilities/vmError.hpp"
55
56 // put OS-includes here
57 # include <sys/types.h>
58 # include <sys/mman.h>
59 # include <pthread.h>
60 # include <signal.h>
61 # include <errno.h>
62 # include <dlfcn.h>
63 # include <stdlib.h>
64 # include <stdio.h>
65 # include <unistd.h>
66 # include <sys/resource.h>
67 # include <pthread.h>
68 # include <sys/stat.h>
69 # include <sys/time.h>
70 # include <sys/utsname.h>
71 # include <sys/socket.h>
72 # include <sys/wait.h>
73 # include <pwd.h>
74 # include <poll.h>
75 # include <ucontext.h>
76
77
78 address os::current_stack_pointer() {
79 intptr_t* csp;
80
81 // inline assembly `mr regno(csp), R1_SP':
82 __asm__ __volatile__ ("mr %0, 1":"=r"(csp):);
83
84 return (address) csp;
85 }
86
87 char* os::non_memory_address_word() {
88 // Must never look like an address returned by reserve_memory,
89 // even in its subfields (as defined by the CPU immediate fields,
90 // if the CPU splits constants across multiple instructions).
91
92 return (char*) -1;
93 }
94
95 void os::initialize_thread(Thread *thread) { }
96
97 // Frame information (pc, sp, fp) retrieved via ucontext
98 // always looks like a C-frame according to the frame
99 // conventions in frame_ppc64.hpp.
100 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
101 // On powerpc64, ucontext_t is not selfcontained but contains
102 // a pointer to an optional substructure (mcontext_t.regs) containing the volatile
103 // registers - NIP, among others.
104 // This substructure may or may not be there depending where uc came from:
105 // - if uc was handed over as the argument to a sigaction handler, a pointer to the
106 // substructure was provided by the kernel when calling the signal handler, and
107 // regs->nip can be accessed.
108 // - if uc was filled by getcontext(), it is undefined - getcontext() does not fill
109 // it because the volatile registers are not needed to make setcontext() work.
110 // Hopefully it was zero'd out beforehand.
111 guarantee(uc->uc_mcontext.regs != NULL, "only use ucontext_get_pc in sigaction context");
112 return (address)uc->uc_mcontext.regs->nip;
113 }
114
115 // modify PC in ucontext.
116 // Note: Only use this for an ucontext handed down to a signal handler. See comment
117 // in ucontext_get_pc.
118 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
119 guarantee(uc->uc_mcontext.regs != NULL, "only use ucontext_set_pc in sigaction context");
120 uc->uc_mcontext.regs->nip = (unsigned long)pc;
121 }
122
123 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
124 return (intptr_t*)uc->uc_mcontext.regs->gpr[1/*REG_SP*/];
125 }
126
127 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
128 return NULL;
129 }
130
131 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
132 intptr_t** ret_sp, intptr_t** ret_fp) {
133
134 ExtendedPC epc;
135 const ucontext_t* uc = (const ucontext_t*)ucVoid;
136
137 if (uc != NULL) {
138 epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
139 if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
140 if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
141 } else {
142 // construct empty ExtendedPC for return value checking
143 epc = ExtendedPC(NULL);
144 if (ret_sp) *ret_sp = (intptr_t *)NULL;
145 if (ret_fp) *ret_fp = (intptr_t *)NULL;
146 }
147
148 return epc;
149 }
150
151 frame os::fetch_frame_from_context(const void* ucVoid) {
152 intptr_t* sp;
153 intptr_t* fp;
154 ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
155 return frame(sp, epc.pc());
156 }
157
158 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
159 address pc = (address) os::Linux::ucontext_get_pc(uc);
160 if (Interpreter::contains(pc)) {
161 // Interpreter performs stack banging after the fixed frame header has
162 // been generated while the compilers perform it before. To maintain
163 // semantic consistency between interpreted and compiled frames, the
164 // method returns the Java sender of the current frame.
165 *fr = os::fetch_frame_from_context(uc);
166 if (!fr->is_first_java_frame()) {
167 assert(fr->safe_for_sender(thread), "Safety check");
168 *fr = fr->java_sender();
169 }
170 } else {
171 // More complex code with compiled code.
172 assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
173 CodeBlob* cb = CodeCache::find_blob(pc);
174 if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
175 // Not sure where the pc points to, fallback to default
176 // stack overflow handling. In compiled code, we bang before
177 // the frame is complete.
178 return false;
179 } else {
180 intptr_t* fp = os::Linux::ucontext_get_fp(uc);
181 intptr_t* sp = os::Linux::ucontext_get_sp(uc);
182 *fr = frame(sp, (address)*sp);
183 if (!fr->is_java_frame()) {
184 assert(fr->safe_for_sender(thread), "Safety check");
185 assert(!fr->is_first_frame(), "Safety check");
186 *fr = fr->java_sender();
187 }
188 }
189 }
190 assert(fr->is_java_frame(), "Safety check");
191 return true;
192 }
193
194 frame os::get_sender_for_C_frame(frame* fr) {
195 if (*fr->sp() == 0) {
196 // fr is the last C frame
197 return frame(NULL, NULL);
198 }
199 return frame(fr->sender_sp(), fr->sender_pc());
200 }
201
202
203 frame os::current_frame() {
204 intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());
205 // hack.
206 frame topframe(csp, (address)0x8);
207 // Return sender of sender of current topframe which hopefully
208 // both have pc != NULL.
209 frame tmp = os::get_sender_for_C_frame(&topframe);
210 return os::get_sender_for_C_frame(&tmp);
211 }
212
213 // Utility functions
214
215 extern "C" JNIEXPORT int
216 JVM_handle_linux_signal(int sig,
217 siginfo_t* info,
218 void* ucVoid,
219 int abort_if_unrecognized) {
220 ucontext_t* uc = (ucontext_t*) ucVoid;
221
222 Thread* t = Thread::current_or_null_safe();
223
224 SignalHandlerMark shm(t);
225
226 // Note: it's not uncommon that JNI code uses signal/sigset to install
227 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
228 // or have a SIGILL handler when detecting CPU type). When that happens,
229 // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
230 // avoid unnecessary crash when libjsig is not preloaded, try handle signals
231 // that do not require siginfo/ucontext first.
232
233 if (sig == SIGPIPE) {
234 if (os::Linux::chained_handler(sig, info, ucVoid)) {
235 return true;
236 } else {
237 // Ignoring SIGPIPE - see bugs 4229104
238 return true;
239 }
240 }
241
242 // Make the signal handler transaction-aware by checking the existence of a
243 // second (transactional) context with MSR TS bits active. If the signal is
244 // caught during a transaction, then just return to the HTM abort handler.
245 // Please refer to Linux kernel document powerpc/transactional_memory.txt,
246 // section "Signals".
247 if (uc && uc->uc_link) {
248 ucontext_t* second_uc = uc->uc_link;
249
250 // MSR TS bits are 29 and 30 (Power ISA, v2.07B, Book III-S, pp. 857-858,
251 // 3.2.1 "Machine State Register"), however note that ISA notation for bit
252 // numbering is MSB 0, so for normal bit numbering (LSB 0) they come to be
253 // bits 33 and 34. It's not related to endianness, just a notation matter.
254 if (second_uc->uc_mcontext.regs->msr & 0x600000000) {
255 if (TraceTraps) {
256 tty->print_cr("caught signal in transaction, "
257 "ignoring to jump to abort handler");
258 }
259 // Return control to the HTM abort handler.
260 return true;
261 }
262 }
263
264 JavaThread* thread = NULL;
265 VMThread* vmthread = NULL;
266 if (os::Linux::signal_handlers_are_installed) {
267 if (t != NULL) {
268 if(t->is_Java_thread()) {
269 thread = (JavaThread*)t;
270 } else if(t->is_VM_thread()) {
271 vmthread = (VMThread *)t;
272 }
273 }
274 }
275
276 // Moved SafeFetch32 handling outside thread!=NULL conditional block to make
277 // it work if no associated JavaThread object exists.
278 if (uc) {
279 address const pc = os::Linux::ucontext_get_pc(uc);
280 if (pc && StubRoutines::is_safefetch_fault(pc)) {
281 os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
282 return true;
283 }
284 }
285
286 // decide if this trap can be handled by a stub
287 address stub = NULL;
288 address pc = NULL;
289
290 //%note os_trap_1
291 if (info != NULL && uc != NULL && thread != NULL) {
292 pc = (address) os::Linux::ucontext_get_pc(uc);
293
294 // Handle ALL stack overflow variations here
295 if (sig == SIGSEGV) {
296 // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see
297 // comment below). Use get_stack_bang_address instead of si_addr.
298 address addr = ((NativeInstruction*)pc)->get_stack_bang_address(uc);
299
300 // Check if fault address is within thread stack.
301 if (thread->on_local_stack(addr)) {
302 // stack overflow
303 if (thread->in_stack_yellow_reserved_zone(addr)) {
304 if (thread->thread_state() == _thread_in_Java) {
305 if (thread->in_stack_reserved_zone(addr)) {
306 frame fr;
307 if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
308 assert(fr.is_java_frame(), "Must be a Javac frame");
309 frame activation =
310 SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
311 if (activation.sp() != NULL) {
312 thread->disable_stack_reserved_zone();
313 if (activation.is_interpreted_frame()) {
314 thread->set_reserved_stack_activation((address)activation.fp());
315 } else {
316 thread->set_reserved_stack_activation((address)activation.unextended_sp());
317 }
318 return 1;
319 }
320 }
321 }
322 // Throw a stack overflow exception.
323 // Guard pages will be reenabled while unwinding the stack.
324 thread->disable_stack_yellow_reserved_zone();
325 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
326 } else {
327 // Thread was in the vm or native code. Return and try to finish.
328 thread->disable_stack_yellow_reserved_zone();
329 return 1;
330 }
331 } else if (thread->in_stack_red_zone(addr)) {
332 // Fatal red zone violation. Disable the guard pages and fall through
333 // to handle_unexpected_exception way down below.
334 thread->disable_stack_red_zone();
335 tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
336
337 // This is a likely cause, but hard to verify. Let's just print
338 // it as a hint.
339 tty->print_raw_cr("Please check if any of your loaded .so files has "
340 "enabled executable stack (see man page execstack(8))");
341 } else {
342 // Accessing stack address below sp may cause SEGV if current
343 // thread has MAP_GROWSDOWN stack. This should only happen when
344 // current thread was created by user code with MAP_GROWSDOWN flag
345 // and then attached to VM. See notes in os_linux.cpp.
346 if (thread->osthread()->expanding_stack() == 0) {
347 thread->osthread()->set_expanding_stack();
348 if (os::Linux::manually_expand_stack(thread, addr)) {
349 thread->osthread()->clear_expanding_stack();
350 return 1;
351 }
352 thread->osthread()->clear_expanding_stack();
353 } else {
354 fatal("recursive segv. expanding stack.");
355 }
356 }
357 }
358 }
359
360 if (thread->thread_state() == _thread_in_Java) {
361 // Java thread running in Java code => find exception handler if any
362 // a fault inside compiled code, the interpreter, or a stub
363
364 // A VM-related SIGILL may only occur if we are not in the zero page.
365 // On AIX, we get a SIGILL if we jump to 0x0 or to somewhere else
366 // in the zero page, because it is filled with 0x0. We ignore
367 // explicit SIGILLs in the zero page.
368 if (sig == SIGILL && (pc < (address) 0x200)) {
369 if (TraceTraps) {
370 tty->print_raw_cr("SIGILL happened inside zero page.");
371 }
372 goto report_and_die;
373 }
374
375 CodeBlob *cb = NULL;
376 // Handle signal from NativeJump::patch_verified_entry().
377 if (( TrapBasedNotEntrantChecks && sig == SIGTRAP && nativeInstruction_at(pc)->is_sigtrap_zombie_not_entrant()) ||
378 (!TrapBasedNotEntrantChecks && sig == SIGILL && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant())) {
379 if (TraceTraps) {
380 tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
381 }
382 stub = SharedRuntime::get_handle_wrong_method_stub();
383 }
384
385 else if (sig == SIGSEGV &&
386 // A linux-ppc64 kernel before 2.6.6 doesn't set si_addr on some segfaults
387 // in 64bit mode (cf. http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.6),
388 // especially when we try to read from the safepoint polling page. So the check
389 // (address)info->si_addr == os::get_standard_polling_page()
390 // doesn't work for us. We use:
391 ((NativeInstruction*)pc)->is_safepoint_poll() &&
392 CodeCache::contains((void*) pc) &&
393 ((cb = CodeCache::find_blob(pc)) != NULL) &&
394 cb->is_compiled()) {
395 if (TraceTraps) {
396 tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
397 }
398 stub = SharedRuntime::get_poll_stub(pc);
399 }
400
401 // SIGTRAP-based ic miss check in compiled code.
402 else if (sig == SIGTRAP && TrapBasedICMissChecks &&
403 nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) {
404 if (TraceTraps) {
405 tty->print_cr("trap: ic_miss_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
406 }
407 stub = SharedRuntime::get_ic_miss_stub();
408 }
409
410 // SIGTRAP-based implicit null check in compiled code.
411 else if (sig == SIGTRAP && TrapBasedNullChecks &&
412 nativeInstruction_at(pc)->is_sigtrap_null_check()) {
413 if (TraceTraps) {
414 tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
415 }
416 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
417 }
418
419 // SIGSEGV-based implicit null check in compiled code.
420 else if (sig == SIGSEGV && ImplicitNullChecks &&
421 CodeCache::contains((void*) pc) &&
422 !MacroAssembler::needs_explicit_null_check((intptr_t) info->si_addr)) {
423 if (TraceTraps) {
424 tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
425 }
426 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
427 }
428
429 #ifdef COMPILER2
430 // SIGTRAP-based implicit range check in compiled code.
431 else if (sig == SIGTRAP && TrapBasedRangeChecks &&
432 nativeInstruction_at(pc)->is_sigtrap_range_check()) {
433 if (TraceTraps) {
434 tty->print_cr("trap: range_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
435 }
436 stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
437 }
438 #endif
439 else if (sig == SIGBUS) {
440 // BugId 4454115: A read from a MappedByteBuffer can fault here if the
441 // underlying file has been truncated. Do not crash the VM in such a case.
442 CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
443 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
444 if (nm != NULL && nm->has_unsafe_access()) {
445 address next_pc = pc + 4;
446 next_pc = SharedRuntime::handle_unsafe_access(thread, next_pc);
447 os::Linux::ucontext_set_pc(uc, next_pc);
448 return true;
449 }
450 }
451 }
452
453 else { // thread->thread_state() != _thread_in_Java
454 if (sig == SIGILL && VM_Version::is_determine_features_test_running()) {
455 // SIGILL must be caused by VM_Version::determine_features().
456 *(int *)pc = 0; // patch instruction to 0 to indicate that it causes a SIGILL,
457 // flushing of icache is not necessary.
458 stub = pc + 4; // continue with next instruction.
459 }
460 else if (thread->thread_state() == _thread_in_vm &&
461 sig == SIGBUS && thread->doing_unsafe_access()) {
462 address next_pc = pc + 4;
463 next_pc = SharedRuntime::handle_unsafe_access(thread, next_pc);
464 os::Linux::ucontext_set_pc(uc, pc + 4);
465 return true;
466 }
467 }
468
469 // Check to see if we caught the safepoint code in the
470 // process of write protecting the memory serialization page.
471 // It write enables the page immediately after protecting it
472 // so we can just return to retry the write.
473 if ((sig == SIGSEGV) &&
474 // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see comment above).
475 // Use is_memory_serialization instead of si_addr.
476 ((NativeInstruction*)pc)->is_memory_serialization(thread, ucVoid)) {
477 // Synchronization problem in the pseudo memory barrier code (bug id 6546278)
478 // Block current thread until the memory serialize page permission restored.
479 os::block_on_serialize_page_trap();
480 return true;
481 }
482 }
483
484 if (stub != NULL) {
485 // Save all thread context in case we need to restore it.
486 if (thread != NULL) thread->set_saved_exception_pc(pc);
487 os::Linux::ucontext_set_pc(uc, stub);
488 return true;
489 }
490
491 // signal-chaining
492 if (os::Linux::chained_handler(sig, info, ucVoid)) {
493 return true;
494 }
495
496 if (!abort_if_unrecognized) {
497 // caller wants another chance, so give it to him
498 return false;
499 }
500
501 if (pc == NULL && uc != NULL) {
502 pc = os::Linux::ucontext_get_pc(uc);
503 }
504
505 report_and_die:
506 // unmask current signal
507 sigset_t newset;
508 sigemptyset(&newset);
509 sigaddset(&newset, sig);
510 sigprocmask(SIG_UNBLOCK, &newset, NULL);
511
512 VMError::report_and_die(t, sig, pc, info, ucVoid);
513
514 ShouldNotReachHere();
515 return false;
516 }
517
518 void os::Linux::init_thread_fpu_state(void) {
519 // Disable FP exceptions.
520 __asm__ __volatile__ ("mtfsfi 6,0");
521 }
522
523 int os::Linux::get_fpu_control_word(void) {
524 // x86 has problems with FPU precision after pthread_cond_timedwait().
525 // nothing to do on ppc64.
526 return 0;
527 }
528
529 void os::Linux::set_fpu_control_word(int fpu_control) {
530 // x86 has problems with FPU precision after pthread_cond_timedwait().
531 // nothing to do on ppc64.
532 }
533
534 ////////////////////////////////////////////////////////////////////////////////
535 // thread stack
536
537 // Minimum usable stack sizes required to get to user code. Space for
538 // HotSpot guard pages is added later.
539 size_t os::Posix::_compiler_thread_min_stack_allowed = 64 * K;
540 size_t os::Posix::_java_thread_min_stack_allowed = 64 * K;
541 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 64 * K;
542
543 // Return default stack size for thr_type.
544 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
545 // Default stack size (compiler thread needs larger stack).
546 size_t s = (thr_type == os::compiler_thread ? 4 * M : 1024 * K);
547 return s;
548 }
549
550 /////////////////////////////////////////////////////////////////////////////
551 // helper functions for fatal error handler
552
553 void os::print_context(outputStream *st, const void *context) {
554 if (context == NULL) return;
555
556 const ucontext_t* uc = (const ucontext_t*)context;
557
558 st->print_cr("Registers:");
559 st->print("pc =" INTPTR_FORMAT " ", uc->uc_mcontext.regs->nip);
560 st->print("lr =" INTPTR_FORMAT " ", uc->uc_mcontext.regs->link);
561 st->print("ctr=" INTPTR_FORMAT " ", uc->uc_mcontext.regs->ctr);
562 st->cr();
563 for (int i = 0; i < 32; i++) {
564 st->print("r%-2d=" INTPTR_FORMAT " ", i, uc->uc_mcontext.regs->gpr[i]);
565 if (i % 3 == 2) st->cr();
566 }
567 st->cr();
568 st->cr();
569
570 intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
571 st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
572 print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t));
573 st->cr();
574
575 // Note: it may be unsafe to inspect memory near pc. For example, pc may
576 // point to garbage if entry point in an nmethod is corrupted. Leave
577 // this at the end, and hope for the best.
578 address pc = os::Linux::ucontext_get_pc(uc);
579 st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
580 print_hex_dump(st, pc - 64, pc + 64, /*instrsize=*/4);
581 st->cr();
582 }
583
584 void os::print_register_info(outputStream *st, const void *context) {
585 if (context == NULL) return;
586
587 const ucontext_t *uc = (const ucontext_t*)context;
588
589 st->print_cr("Register to memory mapping:");
590 st->cr();
591
592 // this is only for the "general purpose" registers
593 for (int i = 0; i < 32; i++) {
594 st->print("r%-2d=", i);
595 print_location(st, uc->uc_mcontext.regs->gpr[i]);
596 }
597 st->cr();
598 }
599
600 extern "C" {
601 int SpinPause() {
602 return 0;
603 }
604 }
605
606 #ifndef PRODUCT
607 void os::verify_stack_alignment() {
608 assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
609 }
610 #endif
611
612 int os::extra_bang_size_in_bytes() {
613 // PPC does not require the additional stack bang.
614 return 0;
615 }