/*

 * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

// no precompiled headers

#include "jvm.h"

#include "asm/macroAssembler.hpp"

#include "classfile/classLoader.hpp"

#include "classfile/systemDictionary.hpp"

#include "classfile/vmSymbols.hpp"

#include "code/codeCache.hpp"

#include "code/icBuffer.hpp"

#include "code/vtableStubs.hpp"

#include "interpreter/interpreter.hpp"

#include "logging/log.hpp"

#include "memory/allocation.inline.hpp"

#include "os_share_linux.hpp"

#include "prims/jniFastGetField.hpp"

#include "prims/jvm_misc.hpp"

#include "runtime/arguments.hpp"

#include "runtime/extendedPC.hpp"

#include "runtime/frame.inline.hpp"

#include "runtime/interfaceSupport.inline.hpp"

#include "runtime/java.hpp"

#include "runtime/javaCalls.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/osThread.hpp"

#include "runtime/sharedRuntime.hpp"

#include "runtime/stubRoutines.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/timer.hpp"

#include "services/memTracker.hpp"

#include "utilities/align.hpp"

#include "utilities/debug.hpp"

#include "utilities/events.hpp"

#include "utilities/vmError.hpp"

// put OS-includes here

# include <sys/types.h>

# include <sys/mman.h>

# include <pthread.h>

# include <signal.h>

# include <errno.h>

# include <dlfcn.h>

# include <stdlib.h>

# include <stdio.h>

# include <unistd.h>

# include <sys/resource.h>

# include <pthread.h>

# include <sys/stat.h>

# include <sys/time.h>

# include <sys/utsname.h>

# include <sys/socket.h>

# include <sys/wait.h>

# include <pwd.h>

# include <poll.h>

# include <ucontext.h>

#ifndef AMD64

# include <fpu_control.h>

#endif

#ifdef AMD64

#define REG_SP REG_RSP

#define REG_PC REG_RIP

#define REG_FP REG_RBP

#define SPELL_REG_SP "rsp"

#define SPELL_REG_FP "rbp"

#else

#define REG_SP REG_UESP

#define REG_PC REG_EIP

#define REG_FP REG_EBP

#define SPELL_REG_SP "esp"

#define SPELL_REG_FP "ebp"

#endif // AMD64

address os::current_stack_pointer() {

#ifdef SPARC_WORKS

  void *esp;

  __asm__("mov %%" SPELL_REG_SP ", %0":"=r"(esp));

  return (address) ((char*)esp + sizeof(long)*2);

#elif defined(__clang__)

  void* esp;

  __asm__ __volatile__ ("mov %%" SPELL_REG_SP ", %0":"=r"(esp):);

  return (address) esp;

#else

  register void *esp __asm__ (SPELL_REG_SP);

  return (address) esp;

#endif

}

char* os::non_memory_address_word() {

  // Must never look like an address returned by reserve_memory,

  // even in its subfields (as defined by the CPU immediate fields,

  // if the CPU splits constants across multiple instructions).

  return (char*) -1;

}

address os::Linux::ucontext_get_pc(const ucontext_t * uc) {

  return (address)uc->uc_mcontext.gregs[REG_PC];

}

void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {

  uc->uc_mcontext.gregs[REG_PC] = (intptr_t)pc;

}

intptr_t* os::Linux::ucontext_get_sp(const ucontext_t * uc) {

  return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];

}

intptr_t* os::Linux::ucontext_get_fp(const ucontext_t * uc) {

  return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];

}

// For Forte Analyzer AsyncGetCallTrace profiling support - thread

// is currently interrupted by SIGPROF.

// os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal

// frames. Currently we don't do that on Linux, so it's the same as

// os::fetch_frame_from_context().

// This method is also used for stack overflow signal handling.

ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,

  const ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {

  assert(thread != NULL, "just checking");

  assert(ret_sp != NULL, "just checking");

  assert(ret_fp != NULL, "just checking");

  return os::fetch_frame_from_context(uc, ret_sp, ret_fp);

}

ExtendedPC os::fetch_frame_from_context(const void* ucVoid,

                    intptr_t** ret_sp, intptr_t** ret_fp) {

  ExtendedPC  epc;

  const ucontext_t* uc = (const ucontext_t*)ucVoid;

  if (uc != NULL) {

    epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));

    if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);

    if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);

  } else {

    // construct empty ExtendedPC for return value checking

    epc = ExtendedPC(NULL);

    if (ret_sp) *ret_sp = (intptr_t *)NULL;

    if (ret_fp) *ret_fp = (intptr_t *)NULL;

  }

  return epc;

}

frame os::fetch_frame_from_context(const void* ucVoid) {

  intptr_t* sp;

  intptr_t* fp;

  ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);

  return frame(sp, fp, epc.pc());

}

frame os::fetch_frame_from_ucontext(Thread* thread, void* ucVoid) {

  intptr_t* sp;

  intptr_t* fp;

  ExtendedPC epc = os::Linux::fetch_frame_from_ucontext(thread, (ucontext_t*)ucVoid, &sp, &fp);

  return frame(sp, fp, epc.pc());

}

bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {

  address pc = (address) os::Linux::ucontext_get_pc(uc);

  if (Interpreter::contains(pc)) {

    // interpreter performs stack banging after the fixed frame header has

    // been generated while the compilers perform it before. To maintain

    // semantic consistency between interpreted and compiled frames, the

    // method returns the Java sender of the current frame.

    *fr = os::fetch_frame_from_ucontext(thread, uc);

    if (!fr->is_first_java_frame()) {

      // get_frame_at_stack_banging_point() is only called when we

      // have well defined stacks so java_sender() calls do not need

      // to assert safe_for_sender() first.

      *fr = fr->java_sender();

    }

  } else {

    // more complex code with compiled code

    assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");

    CodeBlob* cb = CodeCache::find_blob(pc);

    if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {

      // Not sure where the pc points to, fallback to default

      // stack overflow handling

      return false;

    } else {

      // in compiled code, the stack banging is performed just after the return pc

      // has been pushed on the stack

      intptr_t* fp = os::Linux::ucontext_get_fp(uc);

      intptr_t* sp = os::Linux::ucontext_get_sp(uc);

      *fr = frame(sp + 1, fp, (address)*sp);

      if (!fr->is_java_frame()) {

        assert(!fr->is_first_frame(), "Safety check");

        // See java_sender() comment above.

        *fr = fr->java_sender();

      }

    }

  }

  assert(fr->is_java_frame(), "Safety check");

  return true;

}

// By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get

// turned off by -fomit-frame-pointer,

frame os::get_sender_for_C_frame(frame* fr) {

  return frame(fr->sender_sp(), fr->link(), fr->sender_pc());

}

intptr_t* _get_previous_fp() {

#ifdef SPARC_WORKS

  intptr_t **ebp;

  __asm__("mov %%" SPELL_REG_FP ", %0":"=r"(ebp));

#elif defined(__clang__)

  intptr_t **ebp;

  __asm__ __volatile__ ("mov %%" SPELL_REG_FP ", %0":"=r"(ebp):);

#else

  register intptr_t **ebp __asm__ (SPELL_REG_FP);

#endif

  // ebp is for this frame (_get_previous_fp). We want the ebp for the

  // caller of os::current_frame*(), so go up two frames. However, for

  // optimized builds, _get_previous_fp() will be inlined, so only go

  // up 1 frame in that case.

#ifdef _NMT_NOINLINE_

  return **(intptr_t***)ebp;

#else

  return *ebp;

#endif

}

frame os::current_frame() {

  intptr_t* fp = _get_previous_fp();

  frame myframe((intptr_t*)os::current_stack_pointer(),

                (intptr_t*)fp,

                CAST_FROM_FN_PTR(address, os::current_frame));

  if (os::is_first_C_frame(&myframe)) {

    // stack is not walkable

    return frame();

  } else {

    return os::get_sender_for_C_frame(&myframe);

  }

}

// Utility functions

// From IA32 System Programming Guide

enum {

  trap_page_fault = 0xE

};

extern "C" JNIEXPORT int

JVM_handle_linux_signal(int sig,

                        siginfo_t* info,

                        void* ucVoid,

                        int abort_if_unrecognized) {

  ucontext_t* uc = (ucontext_t*) ucVoid;

  Thread* t = Thread::current_or_null_safe();

  // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away

  // (no destructors can be run)

  os::ThreadCrashProtection::check_crash_protection(sig, t);

  SignalHandlerMark shm(t);

  // Note: it's not uncommon that JNI code uses signal/sigset to install

  // then restore certain signal handler (e.g. to temporarily block SIGPIPE,

  // or have a SIGILL handler when detecting CPU type). When that happens,

  // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To

  // avoid unnecessary crash when libjsig is not preloaded, try handle signals

  // that do not require siginfo/ucontext first.

  if (sig == SIGPIPE || sig == SIGXFSZ) {

    // allow chained handler to go first

    if (os::Linux::chained_handler(sig, info, ucVoid)) {

      return true;

    } else {

      // Ignoring SIGPIPE/SIGXFSZ - see bugs 4229104 or 6499219

      return true;

    }

  }

#ifdef CAN_SHOW_REGISTERS_ON_ASSERT

  if ((sig == SIGSEGV || sig == SIGBUS) && info != NULL && info->si_addr == g_assert_poison) {

    if (handle_assert_poison_fault(ucVoid, info->si_addr)) {

      return 1;

    }

  }

#endif

  JavaThread* thread = NULL;

  VMThread* vmthread = NULL;

  if (os::Linux::signal_handlers_are_installed) {

    if (t != NULL ){

      if(t->is_Java_thread()) {

        thread = (JavaThread*)t;

      }

      else if(t->is_VM_thread()){

        vmthread = (VMThread *)t;

      }

    }

  }

/*

  NOTE: does not seem to work on linux.

  if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {

    // can't decode this kind of signal

    info = NULL;

  } else {

    assert(sig == info->si_signo, "bad siginfo");

  }

*/

  // decide if this trap can be handled by a stub

  address stub = NULL;

  address pc          = NULL;

  //%note os_trap_1

  if (info != NULL && uc != NULL && thread != NULL) {

    pc = (address) os::Linux::ucontext_get_pc(uc);

    if (StubRoutines::is_safefetch_fault(pc)) {

      os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));

      return 1;

    }

#ifndef AMD64

    // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs

    // This can happen in any running code (currently more frequently in

    // interpreter code but has been seen in compiled code)

    if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {

      fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "

            "to unstable signal handling in this distribution.");

    }

#endif // AMD64

    // Handle ALL stack overflow variations here

    if (sig == SIGSEGV) {

      address addr = (address) info->si_addr;

      // check if fault address is within thread stack

      if (thread->on_local_stack(addr)) {

        // stack overflow

        if (thread->in_stack_yellow_reserved_zone(addr)) {

          if (thread->thread_state() == _thread_in_Java) {

            if (thread->in_stack_reserved_zone(addr)) {

              frame fr;

              if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {

                assert(fr.is_java_frame(), "Must be a Java frame");

                frame activation =

                  SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);

                if (activation.sp() != NULL) {

                  thread->disable_stack_reserved_zone();

                  if (activation.is_interpreted_frame()) {

                    thread->set_reserved_stack_activation((address)(

                      activation.fp() + frame::interpreter_frame_initial_sp_offset));

                  } else {

                    thread->set_reserved_stack_activation((address)activation.unextended_sp());

                  }

                  return 1;

                }

              }

            }

            // Throw a stack overflow exception.  Guard pages will be reenabled

            // while unwinding the stack.

            thread->disable_stack_yellow_reserved_zone();

            stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);

          } else {

            // Thread was in the vm or native code.  Return and try to finish.

            thread->disable_stack_yellow_reserved_zone();

            return 1;

          }

        } else if (thread->in_stack_red_zone(addr)) {

          // Fatal red zone violation.  Disable the guard pages and fall through

          // to handle_unexpected_exception way down below.

          thread->disable_stack_red_zone();

          tty->print_raw_cr("An irrecoverable stack overflow has occurred.");

          // This is a likely cause, but hard to verify. Let's just print

          // it as a hint.

          tty->print_raw_cr("Please check if any of your loaded .so files has "

                            "enabled executable stack (see man page execstack(8))");

        } else {

          // Accessing stack address below sp may cause SEGV if current

          // thread has MAP_GROWSDOWN stack. This should only happen when

          // current thread was created by user code with MAP_GROWSDOWN flag

          // and then attached to VM. See notes in os_linux.cpp.

          if (thread->osthread()->expanding_stack() == 0) {

             thread->osthread()->set_expanding_stack();

             if (os::Linux::manually_expand_stack(thread, addr)) {

               thread->osthread()->clear_expanding_stack();

               return 1;

             }

             thread->osthread()->clear_expanding_stack();

          } else {

             fatal("recursive segv. expanding stack.");

          }

        }

      }

    }

    if ((sig == SIGSEGV) && VM_Version::is_cpuinfo_segv_addr(pc)) {

      // Verify that OS save/restore AVX registers.

      stub = VM_Version::cpuinfo_cont_addr();

    }

    if (thread->thread_state() == _thread_in_Java) {

      // Java thread running in Java code => find exception handler if any

      // a fault inside compiled code, the interpreter, or a stub

      if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {

        stub = SharedRuntime::get_poll_stub(pc);

      } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {

        // BugId 4454115: A read from a MappedByteBuffer can fault

        // here if the underlying file has been truncated.

        // Do not crash the VM in such a case.

        CodeBlob* cb = CodeCache::find_blob_unsafe(pc);

        CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;

        bool is_unsafe_arraycopy = thread->doing_unsafe_access() && UnsafeCopyMemory::contains_pc(pc);

        if ((nm != NULL && nm->has_unsafe_access()) || is_unsafe_arraycopy) {

          address next_pc = Assembler::locate_next_instruction(pc);

          if (is_unsafe_arraycopy) {

            next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);

          }

          stub = SharedRuntime::handle_unsafe_access(thread, next_pc);

        }

      }

      else

#ifdef AMD64

      if (sig == SIGFPE  &&

          (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {

        stub =

          SharedRuntime::

          continuation_for_implicit_exception(thread,

                                              pc,

                                              SharedRuntime::

                                              IMPLICIT_DIVIDE_BY_ZERO);

#else

      if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {

        // HACK: si_code does not work on linux 2.2.12-20!!!

        int op = pc[0];

        if (op == 0xDB) {

          // FIST

          // TODO: The encoding of D2I in i486.ad can cause an exception

          // prior to the fist instruction if there was an invalid operation

          // pending. We want to dismiss that exception. From the win_32

          // side it also seems that if it really was the fist causing

          // the exception that we do the d2i by hand with different

          // rounding. Seems kind of weird.

          // NOTE: that we take the exception at the NEXT floating point instruction.

          assert(pc[0] == 0xDB, "not a FIST opcode");

          assert(pc[1] == 0x14, "not a FIST opcode");

          assert(pc[2] == 0x24, "not a FIST opcode");

          return true;

        } else if (op == 0xF7) {

          // IDIV

          stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);

        } else {

          // TODO: handle more cases if we are using other x86 instructions

          //   that can generate SIGFPE signal on linux.

          tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);

          fatal("please update this code.");

        }

#endif // AMD64

      } else if (sig == SIGSEGV &&

                 MacroAssembler::uses_implicit_null_check(info->si_addr)) {

          // Determination of interpreter/vtable stub/compiled code null exception

          stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);

      }

    } else if ((thread->thread_state() == _thread_in_vm ||

                thread->thread_state() == _thread_in_native) &&

               (sig == SIGBUS && /* info->si_code == BUS_OBJERR && */

               thread->doing_unsafe_access())) {

        address next_pc = Assembler::locate_next_instruction(pc);

        if (UnsafeCopyMemory::contains_pc(pc)) {

          next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);

        }

        stub = SharedRuntime::handle_unsafe_access(thread, next_pc);

    }

    // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in

    // and the heap gets shrunk before the field access.

    if ((sig == SIGSEGV) || (sig == SIGBUS)) {

      address addr = JNI_FastGetField::find_slowcase_pc(pc);

      if (addr != (address)-1) {

        stub = addr;