1 /*
  2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
  3  * Copyright (c) 2016, 2018 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 // This file is organized as os_linux_x86.cpp.
 27 
 28 // no precompiled headers
 29 #include "jvm.h"
 30 #include "asm/assembler.inline.hpp"
 31 #include "classfile/classLoader.hpp"
 32 #include "classfile/systemDictionary.hpp"
 33 #include "classfile/vmSymbols.hpp"
 34 #include "code/icBuffer.hpp"
 35 #include "code/nativeInst.hpp"
 36 #include "code/vtableStubs.hpp"
 37 #include "compiler/disassembler.hpp"
 38 #include "interpreter/interpreter.hpp"
 39 #include "memory/allocation.inline.hpp"
 40 #include "nativeInst_s390.hpp"
 41 #include "os_share_linux.hpp"
 42 #include "prims/jniFastGetField.hpp"
 43 #include "prims/jvm_misc.hpp"
 44 #include "runtime/arguments.hpp"
 45 #include "runtime/extendedPC.hpp"
 46 #include "runtime/frame.inline.hpp"
 47 #include "runtime/interfaceSupport.inline.hpp"
 48 #include "runtime/java.hpp"
 49 #include "runtime/javaCalls.hpp"
 50 #include "runtime/mutexLocker.hpp"
 51 #include "runtime/osThread.hpp"
 52 #include "runtime/sharedRuntime.hpp"
 53 #include "runtime/stubRoutines.hpp"
 54 #include "runtime/thread.inline.hpp"
 55 #include "runtime/timer.hpp"
 56 #include "utilities/events.hpp"
 57 #include "utilities/debug.hpp"
 58 #include "utilities/vmError.hpp"
 59 
 60 // put OS-includes here
 61 # include <sys/types.h>
 62 # include <sys/mman.h>
 63 # include <pthread.h>
 64 # include <signal.h>
 65 # include <errno.h>
 66 # include <dlfcn.h>
 67 # include <stdlib.h>
 68 # include <stdio.h>
 69 # include <unistd.h>
 70 # include <sys/resource.h>
 71 # include <pthread.h>
 72 # include <sys/stat.h>
 73 # include <sys/time.h>
 74 # include <sys/utsname.h>
 75 # include <sys/socket.h>
 76 # include <sys/wait.h>
 77 # include <pwd.h>
 78 # include <poll.h>
 79 # include <ucontext.h>
 80 
 81 address os::current_stack_pointer() {
 82   intptr_t* csp;
 83 
 84   // Inline assembly for `z_lgr regno(csp), Z_SP' (Z_SP = Z_R15):
 85   __asm__ __volatile__ ("lgr %0, 15":"=r"(csp):);
 86 
 87   assert(((uint64_t)csp & (frame::alignment_in_bytes-1)) == 0, "SP must be aligned");
 88   return (address) csp;
 89 }
 90 
 91 char* os::non_memory_address_word() {
 92   // Must never look like an address returned by reserve_memory,
 93   // even in its subfields (as defined by the CPU immediate fields,
 94   // if the CPU splits constants across multiple instructions).
 95   return (char*) -1;
 96 }
 97 
 98 // Frame information (pc, sp, fp) retrieved via ucontext
 99 // always looks like a C-frame according to the frame
100 // conventions in frame_s390.hpp.
101 address os::Linux::ucontext_get_pc(const ucontext_t * uc) {
102   return (address)uc->uc_mcontext.psw.addr;
103 }
104 
105 void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
106   uc->uc_mcontext.psw.addr = (unsigned long)pc;
107 }
108 
109 static address ucontext_get_lr(const ucontext_t * uc) {
110   return (address)uc->uc_mcontext.gregs[14/*LINK*/];
111 }
112 
113 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
114   return (intptr_t*)uc->uc_mcontext.gregs[15/*REG_SP*/];
115 }
116 
117 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
118   return NULL;
119 }
120 
121 ExtendedPC os::fetch_frame_from_context(const void* ucVoid,
122                     intptr_t** ret_sp, intptr_t** ret_fp) {
123 
124   ExtendedPC  epc;
125   const ucontext_t* uc = (const ucontext_t*)ucVoid;
126 
127   if (uc != NULL) {
128     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
129     if (ret_sp) { *ret_sp = os::Linux::ucontext_get_sp(uc); }
130     if (ret_fp) { *ret_fp = os::Linux::ucontext_get_fp(uc); }
131   } else {
132     // Construct empty ExtendedPC for return value checking.
133     epc = ExtendedPC(NULL);
134     if (ret_sp) { *ret_sp = (intptr_t *)NULL; }
135     if (ret_fp) { *ret_fp = (intptr_t *)NULL; }
136   }
137 
138   return epc;
139 }
140 
141 frame os::fetch_frame_from_context(const void* ucVoid) {
142   intptr_t* sp;
143   intptr_t* fp;
144   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
145   return frame(sp, epc.pc());
146 }
147 
148 bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
149   address pc = (address) os::Linux::ucontext_get_pc(uc);
150   if (Interpreter::contains(pc)) {
151     // Interpreter performs stack banging after the fixed frame header has
152     // been generated while the compilers perform it before. To maintain
153     // semantic consistency between interpreted and compiled frames, the
154     // method returns the Java sender of the current frame.
155     *fr = os::fetch_frame_from_context(uc);
156     if (!fr->is_first_java_frame()) {
157       assert(fr->safe_for_sender(thread), "Safety check");
158       *fr = fr->java_sender();
159     }
160   } else {
161     // More complex code with compiled code.
162     assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
163     CodeBlob* cb = CodeCache::find_blob(pc);
164     if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
165       // Not sure where the pc points to, fallback to default
166       // stack overflow handling. In compiled code, we bang before
167       // the frame is complete.
168       return false;
169     } else {
170       intptr_t* sp = os::Linux::ucontext_get_sp(uc);
171       address lr = ucontext_get_lr(uc);
172       *fr = frame(sp, lr);
173       if (!fr->is_java_frame()) {
174         assert(fr->safe_for_sender(thread), "Safety check");
175         assert(!fr->is_first_frame(), "Safety check");
176         *fr = fr->java_sender();
177       }
178     }
179   }
180   assert(fr->is_java_frame(), "Safety check");
181   return true;
182 }
183 
184 frame os::get_sender_for_C_frame(frame* fr) {
185   if (*fr->sp() == 0) {
186     // fr is the last C frame.
187     return frame();
188   }
189 
190   // If its not one of our frames, the return pc is saved at gpr14
191   // stack slot. The call_stub stores the return_pc to the stack slot
192   // of gpr10.
193   if ((Interpreter::code() != NULL && Interpreter::contains(fr->pc())) ||
194       (CodeCache::contains(fr->pc()) && !StubRoutines::contains(fr->pc()))) {
195     return frame(fr->sender_sp(), fr->sender_pc());
196   } else {
197     if (StubRoutines::contains(fr->pc())) {
198       StubCodeDesc* desc = StubCodeDesc::desc_for(fr->pc());
199       if (desc && !strcmp(desc->name(),"call_stub")) {
200         return frame(fr->sender_sp(), fr->callstub_sender_pc());
201       } else {
202         return frame(fr->sender_sp(), fr->sender_pc());
203       }
204     } else {
205       return frame(fr->sender_sp(), fr->native_sender_pc());
206     }
207   }
208 }
209 
210 frame os::current_frame() {
211   // Expected to return the stack pointer of this method.
212   // But if inlined, returns the stack pointer of our caller!
213   intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());
214   assert (csp != NULL, "sp should not be NULL");
215   // Pass a dummy pc. This way we don't have to load it from the
216   // stack, since we don't know in which slot we can find it.
217   frame topframe(csp, (address)0x8);
218   if (os::is_first_C_frame(&topframe)) {
219     // Stack is not walkable.
220     return frame();
221   } else {
222     frame senderFrame = os::get_sender_for_C_frame(&topframe);
223     assert(senderFrame.pc() != NULL, "Sender pc should not be NULL");
224     // Return sender of sender of current topframe which hopefully
225     // both have pc != NULL.
226 #ifdef _NMT_NOINLINE_   // Is set in slowdebug builds.
227     // Current_stack_pointer is not inlined, we must pop one more frame.
228     frame tmp = os::get_sender_for_C_frame(&topframe);
229     return os::get_sender_for_C_frame(&tmp);
230 #else
231     return os::get_sender_for_C_frame(&topframe);
232 #endif
233   }
234 }
235 
236 // Utility functions
237 
238 extern "C" JNIEXPORT int
239 JVM_handle_linux_signal(int sig,
240                         siginfo_t* info,
241                         void* ucVoid,
242                         int abort_if_unrecognized) {
243   ucontext_t* uc = (ucontext_t*) ucVoid;
244 
245   Thread* t = Thread::current_or_null_safe();
246 
247   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
248   // (no destructors can be run).
249   os::ThreadCrashProtection::check_crash_protection(sig, t);
250 
251   SignalHandlerMark shm(t);
252 
253   // Note: it's not uncommon that JNI code uses signal/sigset to install
254   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
255   // or have a SIGILL handler when detecting CPU type). When that happens,
256   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
257   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
258   // that do not require siginfo/ucontext first.
259 
260   if (sig == SIGPIPE) {
261     if (os::Linux::chained_handler(sig, info, ucVoid)) {
262       return true;
263     } else {
264       if (PrintMiscellaneous && (WizardMode || Verbose)) {
265         warning("Ignoring SIGPIPE - see bug 4229104");
266       }
267       return true;
268     }
269   }
270 
271 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
272   if ((sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) {
273     handle_assert_poison_fault(ucVoid, info->si_addr);
274     return 1;
275   }
276 #endif
277 
278   JavaThread* thread = NULL;
279   VMThread* vmthread = NULL;
280   if (os::Linux::signal_handlers_are_installed) {
281     if (t != NULL) {
282       if(t->is_Java_thread()) {
283         thread = (JavaThread*)t;
284       } else if(t->is_VM_thread()) {
285         vmthread = (VMThread *)t;
286       }
287     }
288   }
289 
290   // Moved SafeFetch32 handling outside thread!=NULL conditional block to make
291   // it work if no associated JavaThread object exists.
292   if (uc) {
293     address const pc = os::Linux::ucontext_get_pc(uc);
294     if (pc && StubRoutines::is_safefetch_fault(pc)) {
295       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
296       return true;
297     }
298   }
299 
300   // Decide if this trap can be handled by a stub.
301   address stub    = NULL;
302   address pc      = NULL;  // Pc as retrieved from PSW. Usually points past failing instruction.
303   address trap_pc = NULL;  // Pc of the instruction causing the trap.
304 
305   //%note os_trap_1
306   if (info != NULL && uc != NULL && thread != NULL) {
307     pc = os::Linux::ucontext_get_pc(uc);
308     if (TraceTraps) {
309       tty->print_cr("     pc at " INTPTR_FORMAT, p2i(pc));
310     }
311     if ((unsigned long)(pc - (address)info->si_addr) <= (unsigned long)Assembler::instr_maxlen() ) {
312       trap_pc = (address)info->si_addr;
313       if (TraceTraps) {
314         tty->print_cr("trap_pc at " INTPTR_FORMAT, p2i(trap_pc));
315       }
316     }
317 
318     // Handle ALL stack overflow variations here
319     if (sig == SIGSEGV) {
320       address addr = (address)info->si_addr; // Address causing SIGSEGV, usually mem ref target.
321 
322       // Check if fault address is within thread stack.
323       if (thread->on_local_stack(addr)) {
324         // stack overflow
325         if (thread->in_stack_yellow_reserved_zone(addr)) {
326           if (thread->thread_state() == _thread_in_Java) {
327             if (thread->in_stack_reserved_zone(addr)) {
328               frame fr;
329               if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
330                 assert(fr.is_java_frame(), "Must be a Javac frame");
331                 frame activation =
332                   SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
333                 if (activation.sp() != NULL) {
334                   thread->disable_stack_reserved_zone();
335                   if (activation.is_interpreted_frame()) {
336                     thread->set_reserved_stack_activation((address)activation.fp());
337                   } else {
338                     thread->set_reserved_stack_activation((address)activation.unextended_sp());
339                   }
340                   return 1;
341                 }
342               }
343             }
344             // Throw a stack overflow exception.
345             // Guard pages will be reenabled while unwinding the stack.
346             thread->disable_stack_yellow_reserved_zone();
347             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
348           } else {
349             // Thread was in the vm or native code. Return and try to finish.
350             thread->disable_stack_yellow_reserved_zone();
351             return 1;
352           }
353         } else if (thread->in_stack_red_zone(addr)) {
354           // Fatal red zone violation.  Disable the guard pages and fall through
355           // to handle_unexpected_exception way down below.
356           thread->disable_stack_red_zone();
357           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
358 
359           // This is a likely cause, but hard to verify. Let's just print
360           // it as a hint.
361           tty->print_raw_cr("Please check if any of your loaded .so files has "
362                             "enabled executable stack (see man page execstack(8))");
363         } else {
364           // Accessing stack address below sp may cause SEGV if current
365           // thread has MAP_GROWSDOWN stack. This should only happen when
366           // current thread was created by user code with MAP_GROWSDOWN flag
367           // and then attached to VM. See notes in os_linux.cpp.
368           if (thread->osthread()->expanding_stack() == 0) {
369              thread->osthread()->set_expanding_stack();
370              if (os::Linux::manually_expand_stack(thread, addr)) {
371                thread->osthread()->clear_expanding_stack();
372                return 1;
373              }
374              thread->osthread()->clear_expanding_stack();
375           } else {
376              fatal("recursive segv. expanding stack.");
377           }
378         }
379       }
380     }
381 
382     if (thread->thread_state() == _thread_in_Java) {
383       // Java thread running in Java code => find exception handler if any
384       // a fault inside compiled code, the interpreter, or a stub
385 
386       // Handle signal from NativeJump::patch_verified_entry().
387       if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {
388         if (TraceTraps) {
389           tty->print_cr("trap: zombie_not_entrant (SIGILL)");
390         }
391         stub = SharedRuntime::get_handle_wrong_method_stub();
392       }
393 
394       else if (sig == SIGSEGV &&
395                os::is_poll_address((address)info->si_addr)) {
396         if (TraceTraps) {
397           tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
398         }
399         stub = SharedRuntime::get_poll_stub(pc);
400 
401         // Info->si_addr only points to the page base address, so we
402         // must extract the real si_addr from the instruction and the
403         // ucontext.
404         assert(((NativeInstruction*)pc)->is_safepoint_poll(), "must be safepoint poll");
405         const address real_si_addr = ((NativeInstruction*)pc)->get_poll_address(uc);
406       }
407 
408       // SIGTRAP-based implicit null check in compiled code.
409       else if ((sig == SIGFPE) &&
410                TrapBasedNullChecks &&
411                (trap_pc != NULL) &&
412                Assembler::is_sigtrap_zero_check(trap_pc)) {
413         if (TraceTraps) {
414           tty->print_cr("trap: NULL_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));
415         }
416         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_NULL);
417       }
418 
419       else if (sig == SIGSEGV && ImplicitNullChecks &&
420                CodeCache::contains((void*) pc) &&
421                !MacroAssembler::needs_explicit_null_check((intptr_t) info->si_addr)) {
422         if (TraceTraps) {
423           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
424         }
425         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
426       }
427 
428       // SIGTRAP-based implicit range check in compiled code.
429       else if (sig == SIGFPE && TrapBasedRangeChecks &&
430                (trap_pc != NULL) &&
431                Assembler::is_sigtrap_range_check(trap_pc)) {
432         if (TraceTraps) {
433           tty->print_cr("trap: RANGE_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));
434         }
435         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_NULL);
436       }
437 
438       else if (sig == SIGFPE && info->si_code == FPE_INTDIV) {
439         stub = SharedRuntime::continuation_for_implicit_exception(thread, trap_pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
440       }
441 
442       else if (sig == SIGBUS) {
443         // BugId 4454115: A read from a MappedByteBuffer can fault here if the
444         // underlying file has been truncated. Do not crash the VM in such a case.
445         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
446         CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
447         if (nm != NULL && nm->has_unsafe_access()) {
448           // We don't really need a stub here! Just set the pending exeption and
449           // continue at the next instruction after the faulting read. Returning
450           // garbage from this read is ok.
451           thread->set_pending_unsafe_access_error();
452           uc->uc_mcontext.psw.addr = ((unsigned long)pc) + Assembler::instr_len(pc);
453           return true;
454         }
455       }
456     }
457 
458     else { // thread->thread_state() != _thread_in_Java
459       if ((sig == SIGILL) && VM_Version::is_determine_features_test_running()) {
460         // SIGILL must be caused by VM_Version::determine_features()
461         // when attempting to execute a non-existing instruction.
462         //*(int *) (pc-6)=0; // Patch instruction to 0 to indicate that it causes a SIGILL.
463                              // Flushing of icache is not necessary.
464         stub = pc; // Continue with next instruction.
465       } else if ((sig == SIGFPE) && VM_Version::is_determine_features_test_running()) {
466         // SIGFPE is known to be caused by trying to execute a vector instruction
467         // when the vector facility is installed, but operating system support is missing.
468         VM_Version::reset_has_VectorFacility();
469         stub = pc; // Continue with next instruction.
470       } else if (thread->thread_state() == _thread_in_vm &&
471                  sig == SIGBUS && thread->doing_unsafe_access()) {
472         // We don't really need a stub here! Just set the pending exeption and
473         // continue at the next instruction after the faulting read. Returning
474         // garbage from this read is ok.
475         thread->set_pending_unsafe_access_error();
476         os::Linux::ucontext_set_pc(uc, pc + Assembler::instr_len(pc));
477         return true;
478       }
479     }
480 
481     // Check to see if we caught the safepoint code in the
482     // process of write protecting the memory serialization page.
483     // It write enables the page immediately after protecting it
484     // so we can just return to retry the write.
485     // Info->si_addr need not be the exact address, it is only
486     // guaranteed to be on the same page as the address that caused
487     // the SIGSEGV.
488     if ((sig == SIGSEGV) && !UseMembar &&
489         (os::get_memory_serialize_page() ==
490          (address)((uintptr_t)info->si_addr & ~(os::vm_page_size()-1)))) {
491       return true;
492     }
493   }
494 
495   if (stub != NULL) {
496     // Save all thread context in case we need to restore it.
497     if (thread != NULL) thread->set_saved_exception_pc(pc);
498     os::Linux::ucontext_set_pc(uc, stub);
499     return true;
500   }
501 
502   // signal-chaining
503   if (os::Linux::chained_handler(sig, info, ucVoid)) {
504     return true;
505   }
506 
507   if (!abort_if_unrecognized) {
508     // caller wants another chance, so give it to him
509     return false;
510   }
511 
512   if (pc == NULL && uc != NULL) {
513     pc = os::Linux::ucontext_get_pc(uc);
514   }
515 
516   // unmask current signal
517   sigset_t newset;
518   sigemptyset(&newset);
519   sigaddset(&newset, sig);
520   sigprocmask(SIG_UNBLOCK, &newset, NULL);
521 
522   // Hand down correct pc for SIGILL, SIGFPE. pc from context
523   // usually points to the instruction after the failing instruction.
524   // Note: this should be combined with the trap_pc handling above,
525   // because it handles the same issue.
526   if (sig == SIGILL || sig == SIGFPE) {
527     pc = (address)info->si_addr;
528   }
529 
530   VMError::report_and_die(t, sig, pc, info, ucVoid);
531 
532   ShouldNotReachHere();
533   return false;
534 }
535 
536 void os::Linux::init_thread_fpu_state(void) {
537   // Nothing to do on z/Architecture.
538 }
539 
540 int os::Linux::get_fpu_control_word(void) {
541   // Nothing to do on z/Architecture.
542   return 0;
543 }
544 
545 void os::Linux::set_fpu_control_word(int fpu_control) {
546   // Nothing to do on z/Architecture.
547 }
548 
549 ////////////////////////////////////////////////////////////////////////////////
550 // thread stack
551 
552 // Minimum usable stack sizes required to get to user code. Space for
553 // HotSpot guard pages is added later.
554 size_t os::Posix::_compiler_thread_min_stack_allowed = (52 DEBUG_ONLY(+ 32)) * K;
555 size_t os::Posix::_java_thread_min_stack_allowed = (32 DEBUG_ONLY(+ 8)) * K;
556 size_t os::Posix::_vm_internal_thread_min_stack_allowed = 32 * K;
557 
558 // Return default stack size for thr_type.
559 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
560   // Default stack size (compiler thread needs larger stack).
561   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1024 * K);
562   return s;
563 }
564 
565 /////////////////////////////////////////////////////////////////////////////
566 // helper functions for fatal error handler
567 
568 void os::print_context(outputStream *st, const void *context) {
569   if (context == NULL) return;
570 
571   const ucontext_t* uc = (const ucontext_t*)context;
572 
573   st->print_cr("Processor state:");
574   st->print_cr("----------------");
575   st->print_cr("        ip = " INTPTR_FORMAT " ", uc->uc_mcontext.psw.addr);
576   st->print_cr(" proc mask = " INTPTR_FORMAT " ", uc->uc_mcontext.psw.mask);
577   st->print_cr("   fpc reg = 0x%8.8x "          , uc->uc_mcontext.fpregs.fpc);
578   st->cr();
579 
580   st->print_cr("General Purpose Registers:");
581   st->print_cr("--------------------------");
582   for( int i = 0; i < 16; i+=2 ) {
583     st->print("  r%-2d = " INTPTR_FORMAT "  " ,  i,   uc->uc_mcontext.gregs[i]);
584     st->print("  r%-2d = " INTPTR_FORMAT "  |",  i+1, uc->uc_mcontext.gregs[i+1]);
585     st->print("  r%-2d = %23.1ld  "           ,  i,   uc->uc_mcontext.gregs[i]);
586     st->print("  r%-2d = %23.1ld  "           ,  i+1, uc->uc_mcontext.gregs[i+1]);
587     st->cr();
588   }
589   st->cr();
590 
591   st->print_cr("Access Registers:");
592   st->print_cr("-----------------");
593   for( int i = 0; i < 16; i+=2 ) {
594     st->print("  ar%-2d = 0x%8.8x  ", i,   uc->uc_mcontext.aregs[i]);
595     st->print("  ar%-2d = 0x%8.8x  ", i+1, uc->uc_mcontext.aregs[i+1]);
596     st->cr();
597   }
598   st->cr();
599 
600   st->print_cr("Float Registers:");
601   st->print_cr("----------------");
602   for (int i = 0; i < 16; i += 2) {
603     st->print("  fr%-2d = " INTPTR_FORMAT "  " , i,   (int64_t)(uc->uc_mcontext.fpregs.fprs[i].d));
604     st->print("  fr%-2d = " INTPTR_FORMAT "  |", i+1, (int64_t)(uc->uc_mcontext.fpregs.fprs[i+1].d));
605     st->print("  fr%-2d = %23.15e  "           , i,   (uc->uc_mcontext.fpregs.fprs[i].d));
606     st->print("  fr%-2d = %23.15e  "           , i+1, (uc->uc_mcontext.fpregs.fprs[i+1].d));
607     st->cr();
608   }
609   st->cr();
610   st->cr();
611 
612   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
613   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", p2i(sp));
614   print_hex_dump(st, (address)sp, (address)(sp + 128), sizeof(intptr_t));
615   st->cr();
616 
617   // Note: it may be unsafe to inspect memory near pc. For example, pc may
618   // point to garbage if entry point in an nmethod is corrupted. Leave
619   // this at the end, and hope for the best.
620   address pc = os::Linux::ucontext_get_pc(uc);
621   if (Verbose) { st->print_cr("pc at " PTR_FORMAT, p2i(pc)); }
622   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", p2i(pc));
623   print_hex_dump(st, pc-64, pc+64, /*intrsize=*/4);
624   st->cr();
625 }
626 
627 void os::print_register_info(outputStream *st, const void *context) {
628   if (context == NULL) return;
629 
630   const ucontext_t *uc = (const ucontext_t*)context;
631 
632   st->print_cr("Register to memory mapping:");
633   st->cr();
634 
635   st->print("pc ="); print_location(st, (intptr_t)uc->uc_mcontext.psw.addr);
636   for (int i = 0; i < 16; i++) {
637     st->print("r%-2d=", i);
638     print_location(st, uc->uc_mcontext.gregs[i]);
639   }
640   st->cr();
641 }
642 
643 #ifndef PRODUCT
644 void os::verify_stack_alignment() {
645 }
646 #endif
647 
648 int os::extra_bang_size_in_bytes() {
649   // z/Architecture does not require the additional stack bang.
650   return 0;
651 }