1 /*
  2  * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
  3  * Copyright (c) 2014, Red Hat Inc. 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 "asm/macroAssembler.hpp"
 28 #include "classfile/vmSymbols.hpp"
 29 #include "code/codeCache.hpp"
 30 #include "code/vtableStubs.hpp"
 31 #include "code/nativeInst.hpp"
 32 #include "interpreter/interpreter.hpp"
 33 #include "jvm.h"
 34 #include "memory/allocation.inline.hpp"
 35 #include "os_linux.hpp"
 36 #include "os_posix.hpp"
 37 #include "prims/jniFastGetField.hpp"
 38 #include "prims/jvm_misc.hpp"
 39 #include "runtime/arguments.hpp"
 40 #include "runtime/frame.inline.hpp"
 41 #include "runtime/interfaceSupport.inline.hpp"
 42 #include "runtime/java.hpp"
 43 #include "runtime/javaCalls.hpp"
 44 #include "runtime/mutexLocker.hpp"
 45 #include "runtime/osThread.hpp"
 46 #include "runtime/safepointMechanism.hpp"
 47 #include "runtime/sharedRuntime.hpp"
 48 #include "runtime/stubRoutines.hpp"
 49 #include "runtime/javaThread.hpp"
 50 #include "runtime/timer.hpp"
 51 #include "signals_posix.hpp"
 52 #include "utilities/debug.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 #define REG_FP 29
 78 #define REG_LR 30
 79 
 80 NOINLINE address os::current_stack_pointer() {
 81   return (address)__builtin_frame_address(0);
 82 }
 83 
 84 char* os::non_memory_address_word() {
 85   // Must never look like an address returned by reserve_memory,
 86   // even in its subfields (as defined by the CPU immediate fields,
 87   // if the CPU splits constants across multiple instructions).
 88 
 89   return (char*) 0xffffffffffff;
 90 }
 91 
 92 address os::Posix::ucontext_get_pc(const ucontext_t * uc) {
 93   return (address)uc->uc_mcontext.pc;
 94 }
 95 
 96 void os::Posix::ucontext_set_pc(ucontext_t * uc, address pc) {
 97   uc->uc_mcontext.pc = (intptr_t)pc;
 98 }
 99 
100 intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {
101   return (intptr_t*)uc->uc_mcontext.sp;
102 }
103 
104 intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {
105   return (intptr_t*)uc->uc_mcontext.regs[REG_FP];
106 }
107 
108 address os::fetch_frame_from_context(const void* ucVoid,
109                     intptr_t** ret_sp, intptr_t** ret_fp) {
110 
111   address epc;
112   const ucontext_t* uc = (const ucontext_t*)ucVoid;
113 
114   if (uc != nullptr) {
115     epc = os::Posix::ucontext_get_pc(uc);
116     if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
117     if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
118   } else {
119     epc = nullptr;
120     if (ret_sp) *ret_sp = (intptr_t *)nullptr;
121     if (ret_fp) *ret_fp = (intptr_t *)nullptr;
122   }
123 
124   return epc;
125 }
126 
127 frame os::fetch_frame_from_context(const void* ucVoid) {
128   intptr_t* sp;
129   intptr_t* fp;
130   address epc = fetch_frame_from_context(ucVoid, &sp, &fp);
131   if (!is_readable_pointer(epc)) {
132     // Try to recover from calling into bad memory
133     // Assume new frame has not been set up, the same as
134     // compiled frame stack bang
135     return fetch_compiled_frame_from_context(ucVoid);
136   }
137   return frame(sp, fp, epc);
138 }
139 
140 frame os::fetch_compiled_frame_from_context(const void* ucVoid) {
141   const ucontext_t* uc = (const ucontext_t*)ucVoid;
142   // In compiled code, the stack banging is performed before LR
143   // has been saved in the frame.  LR is live, and SP and FP
144   // belong to the caller.
145   intptr_t* fp = os::Linux::ucontext_get_fp(uc);
146   intptr_t* sp = os::Linux::ucontext_get_sp(uc);
147   address pc = (address)(uc->uc_mcontext.regs[REG_LR]
148                          - NativeInstruction::instruction_size);
149   return frame(sp, fp, pc);
150 }
151 
152 // By default, gcc always saves frame pointer rfp on this stack. This
153 // may get turned off by -fomit-frame-pointer.
154 // The "Procedure Call Standard for the Arm 64-bit Architecture" doesn't
155 // specify a location for the frame record within a stack frame (6.4.6).
156 // GCC currently chooses to save it at the top of the frame (lowest address).
157 // This means that using fr->sender_sp() to set the caller's frame _unextended_sp,
158 // as we do in x86, is wrong. Using fr->link() instead only makes sense for
159 // native frames. Setting a correct value for _unextended_sp is important
160 // if this value is later used to get that frame's caller. This will happen
161 // if we end up calling frame::sender_for_compiled_frame(), which will be the
162 // case if the _pc is associated with a CodeBlob that has a _frame_size > 0
163 // (nmethod, runtime stub, safepoint stub, etc).
164 frame os::get_sender_for_C_frame(frame* fr) {
165   address pc = fr->sender_pc();
166   CodeBlob* cb = CodeCache::find_blob(pc);
167   bool use_codeblob = cb != nullptr && cb->frame_size() > 0;
168   assert(!use_codeblob || !Interpreter::contains(pc), "should not be an interpreter frame");
169   intptr_t* sender_sp = use_codeblob ? (fr->link() + frame::metadata_words - cb->frame_size()) : fr->link();
170   return frame(sender_sp, sender_sp, fr->link(), pc, cb, true /* allow_cb_null */);
171 }
172 
173 NOINLINE frame os::current_frame() {
174   intptr_t *fp = *(intptr_t **)__builtin_frame_address(0);
175   frame myframe((intptr_t*)os::current_stack_pointer(),
176                 (intptr_t*)fp,
177                 CAST_FROM_FN_PTR(address, os::current_frame));
178   if (os::is_first_C_frame(&myframe)) {
179     // stack is not walkable
180     return frame();
181   } else {
182     return os::get_sender_for_C_frame(&myframe);
183   }
184 }
185 
186 bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
187                                              ucontext_t* uc, JavaThread* thread) {
188 
189 /*
190   NOTE: does not seem to work on linux.
191   if (info == nullptr || info->si_code <= 0 || info->si_code == SI_NOINFO) {
192     // can't decode this kind of signal
193     info = nullptr;
194   } else {
195     assert(sig == info->si_signo, "bad siginfo");
196   }
197 */
198   // decide if this trap can be handled by a stub
199   address stub = nullptr;
200 
201   address pc          = nullptr;
202 
203   //%note os_trap_1
204   if (info != nullptr && uc != nullptr && thread != nullptr) {
205     pc = (address) os::Posix::ucontext_get_pc(uc);
206 
207     address addr = (address) info->si_addr;
208 
209     // Make sure the high order byte is sign extended, as it may be masked away by the hardware.
210     if ((uintptr_t(addr) & (uintptr_t(1) << 55)) != 0) {
211       addr = address(uintptr_t(addr) | (uintptr_t(0xFF) << 56));
212     }
213 
214     // Handle ALL stack overflow variations here
215     if (sig == SIGSEGV) {
216       // check if fault address is within thread stack
217       if (thread->is_in_full_stack(addr)) {
218         if (os::Posix::handle_stack_overflow(thread, addr, pc, uc, &stub)) {
219           return true; // continue
220         }
221       }
222     }
223 
224     if (thread->thread_state() == _thread_in_Java) {
225       // Java thread running in Java code => find exception handler if any
226       // a fault inside compiled code, the interpreter, or a stub
227 
228       // Handle signal from NativeJump::patch_verified_entry().
229       if ((sig == SIGILL || sig == SIGTRAP)
230           && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
231         if (TraceTraps) {
232           tty->print_cr("trap: not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
233         }
234         stub = SharedRuntime::get_handle_wrong_method_stub();
235       } else if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
236         stub = SharedRuntime::get_poll_stub(pc);
237       } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
238         // BugId 4454115: A read from a MappedByteBuffer can fault
239         // here if the underlying file has been truncated.
240         // Do not crash the VM in such a case.
241         CodeBlob* cb = CodeCache::find_blob(pc);
242         nmethod* nm = (cb != nullptr) ? cb->as_nmethod_or_null() : nullptr;
243         bool is_unsafe_arraycopy = (thread->doing_unsafe_access() && UnsafeCopyMemory::contains_pc(pc));
244         if ((nm != nullptr && nm->has_unsafe_access()) || is_unsafe_arraycopy) {
245           address next_pc = pc + NativeCall::instruction_size;
246           if (is_unsafe_arraycopy) {
247             next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
248           }
249           stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
250         }
251       } else if (sig == SIGILL && nativeInstruction_at(pc)->is_stop()) {
252         // A pointer to the message will have been placed in r0
253         const char *detail_msg = (const char *)(uc->uc_mcontext.regs[0]);
254         const char *msg = "stop";
255         if (TraceTraps) {
256           tty->print_cr("trap: %s: (SIGILL)", msg);
257         }
258 
259         // End life with a fatal error, message and detail message and the context.
260         // Note: no need to do any post-processing here (e.g. signal chaining)
261         VMError::report_and_die(thread, uc, nullptr, 0, msg, "%s", detail_msg);
262 
263         ShouldNotReachHere();
264 
265       }
266       else
267 
268       if (sig == SIGFPE  &&
269           (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
270         stub =
271           SharedRuntime::
272           continuation_for_implicit_exception(thread,
273                                               pc,
274                                               SharedRuntime::
275                                               IMPLICIT_DIVIDE_BY_ZERO);
276       } else if (sig == SIGSEGV &&
277                  MacroAssembler::uses_implicit_null_check((void*)addr)) {
278           // Determination of interpreter/vtable stub/compiled code null exception
279           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
280       }
281     } else if ((thread->thread_state() == _thread_in_vm ||
282                  thread->thread_state() == _thread_in_native) &&
283                sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
284                thread->doing_unsafe_access()) {
285       address next_pc = pc + NativeCall::instruction_size;
286       if (UnsafeCopyMemory::contains_pc(pc)) {
287         next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
288       }
289       stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
290     }
291 
292     // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
293     // and the heap gets shrunk before the field access.
294     if ((sig == SIGSEGV) || (sig == SIGBUS)) {
295       address addr = JNI_FastGetField::find_slowcase_pc(pc);
296       if (addr != (address)-1) {
297         stub = addr;
298       }
299     }
300   }
301 
302   if (stub != nullptr) {
303     // save all thread context in case we need to restore it
304     if (thread != nullptr) thread->set_saved_exception_pc(pc);
305 
306     os::Posix::ucontext_set_pc(uc, stub);
307     return true;
308   }
309 
310   return false; // Mute compiler
311 }
312 
313 void os::Linux::init_thread_fpu_state(void) {
314 }
315 
316 int os::Linux::get_fpu_control_word(void) {
317   return 0;
318 }
319 
320 void os::Linux::set_fpu_control_word(int fpu_control) {
321 }
322 
323 ////////////////////////////////////////////////////////////////////////////////
324 // thread stack
325 
326 // Minimum usable stack sizes required to get to user code. Space for
327 // HotSpot guard pages is added later.
328 size_t os::_compiler_thread_min_stack_allowed = 72 * K;
329 size_t os::_java_thread_min_stack_allowed = 72 * K;
330 size_t os::_vm_internal_thread_min_stack_allowed = 72 * K;
331 
332 // return default stack size for thr_type
333 size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
334   // default stack size (compiler thread needs larger stack)
335   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
336   return s;
337 }
338 
339 /////////////////////////////////////////////////////////////////////////////
340 // helper functions for fatal error handler
341 
342 void os::print_context(outputStream *st, const void *context) {
343   if (context == nullptr) return;
344 
345   const ucontext_t *uc = (const ucontext_t*)context;
346 
347   st->print_cr("Registers:");
348   for (int r = 0; r < 31; r++) {
349     st->print_cr(  "R%d=" INTPTR_FORMAT, r, (uintptr_t)uc->uc_mcontext.regs[r]);
350   }
351   st->cr();
352 }
353 
354 void os::print_tos_pc(outputStream *st, const void *context) {
355   if (context == nullptr) return;
356 
357   const ucontext_t* uc = (const ucontext_t*)context;
358 
359   address sp = (address)os::Linux::ucontext_get_sp(uc);
360   print_tos(st, sp);
361   st->cr();
362 
363   // Note: it may be unsafe to inspect memory near pc. For example, pc may
364   // point to garbage if entry point in an nmethod is corrupted. Leave
365   // this at the end, and hope for the best.
366   address pc = os::fetch_frame_from_context(uc).pc();
367   print_instructions(st, pc);
368   st->cr();
369 }
370 
371 void os::print_register_info(outputStream *st, const void *context, int& continuation) {
372   const int register_count = 32 /* r0-r31 */;
373   int n = continuation;
374   assert(n >= 0 && n <= register_count, "Invalid continuation value");
375   if (context == nullptr || n == register_count) {
376     return;
377   }
378 
379   const ucontext_t *uc = (const ucontext_t*)context;
380   while (n < register_count) {
381     // Update continuation with next index before printing location
382     continuation = n + 1;
383     st->print("R%-2d=", n);
384     print_location(st, uc->uc_mcontext.regs[n]);
385     ++n;
386   }
387 }
388 
389 void os::setup_fpu() {
390 }
391 
392 #ifndef PRODUCT
393 void os::verify_stack_alignment() {
394   assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
395 }
396 #endif
397 
398 int os::extra_bang_size_in_bytes() {
399   // AArch64 does not require the additional stack bang.
400   return 0;
401 }
402 
403 static inline void atomic_copy64(const volatile void *src, volatile void *dst) {
404   *(jlong *) dst = *(const jlong *) src;
405 }
406 
407 extern "C" {
408   int SpinPause() {
409     using spin_wait_func_ptr_t = void (*)();
410     spin_wait_func_ptr_t func = CAST_TO_FN_PTR(spin_wait_func_ptr_t, StubRoutines::aarch64::spin_wait());
411     assert(func != nullptr, "StubRoutines::aarch64::spin_wait must not be null.");
412     (*func)();
413     // If StubRoutines::aarch64::spin_wait consists of only a RET,
414     // SpinPause can be considered as implemented. There will be a sequence
415     // of instructions for:
416     // - call of SpinPause
417     // - load of StubRoutines::aarch64::spin_wait stub pointer
418     // - indirect call of the stub
419     // - return from the stub
420     // - return from SpinPause
421     // So '1' always is returned.
422     return 1;
423   }
424 
425   void _Copy_conjoint_jshorts_atomic(const jshort* from, jshort* to, size_t count) {
426     if (from > to) {
427       const jshort *end = from + count;
428       while (from < end)
429         *(to++) = *(from++);
430     }
431     else if (from < to) {
432       const jshort *end = from;
433       from += count - 1;
434       to   += count - 1;
435       while (from >= end)
436         *(to--) = *(from--);
437     }
438   }
439   void _Copy_conjoint_jints_atomic(const jint* from, jint* to, size_t count) {
440     if (from > to) {
441       const jint *end = from + count;
442       while (from < end)
443         *(to++) = *(from++);
444     }
445     else if (from < to) {
446       const jint *end = from;
447       from += count - 1;
448       to   += count - 1;
449       while (from >= end)
450         *(to--) = *(from--);
451     }
452   }
453 
454   void _Copy_conjoint_jlongs_atomic(const jlong* from, jlong* to, size_t count) {
455     if (from > to) {
456       const jlong *end = from + count;
457       while (from < end)
458         atomic_copy64(from++, to++);
459     }
460     else if (from < to) {
461       const jlong *end = from;
462       from += count - 1;
463       to   += count - 1;
464       while (from >= end)
465         atomic_copy64(from--, to--);
466     }
467   }
468 
469   void _Copy_arrayof_conjoint_bytes(const HeapWord* from,
470                                     HeapWord* to,
471                                     size_t    count) {
472     memmove(to, from, count);
473   }
474   void _Copy_arrayof_conjoint_jshorts(const HeapWord* from,
475                                       HeapWord* to,
476                                       size_t    count) {
477     memmove(to, from, count * 2);
478   }
479   void _Copy_arrayof_conjoint_jints(const HeapWord* from,
480                                     HeapWord* to,
481                                     size_t    count) {
482     memmove(to, from, count * 4);
483   }
484   void _Copy_arrayof_conjoint_jlongs(const HeapWord* from,
485                                      HeapWord* to,
486                                      size_t    count) {
487     memmove(to, from, count * 8);
488   }
489 };