/*

 * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.

 * Copyright (c) 2016, 2018 SAP SE. 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.

 *

 */

// This file is organized as os_linux_x86.cpp.

// no precompiled headers

#include "jvm.h"

#include "asm/assembler.inline.hpp"

#include "classfile/classLoader.hpp"

#include "classfile/systemDictionary.hpp"

#include "classfile/vmSymbols.hpp"

#include "code/icBuffer.hpp"

#include "code/nativeInst.hpp"

#include "code/vtableStubs.hpp"

#include "compiler/disassembler.hpp"

#include "interpreter/interpreter.hpp"

#include "memory/allocation.inline.hpp"

#include "nativeInst_s390.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 "utilities/events.hpp"

#include "utilities/debug.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>

address os::current_stack_pointer() {

  intptr_t* csp;

  // Inline assembly for `z_lgr regno(csp), Z_SP' (Z_SP = Z_R15):

  __asm__ __volatile__ ("lgr %0, 15":"=r"(csp):);

  assert(((uint64_t)csp & (frame::alignment_in_bytes-1)) == 0, "SP must be aligned");

  return (address) csp;

}

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;

}

// Frame information (pc, sp, fp) retrieved via ucontext

// always looks like a C-frame according to the frame

// conventions in frame_s390.hpp.

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

  return (address)uc->uc_mcontext.psw.addr;

}

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

  uc->uc_mcontext.psw.addr = (unsigned long)pc;

}

static address ucontext_get_lr(const ucontext_t * uc) {

  return (address)uc->uc_mcontext.gregs[14/*LINK*/];

}

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

  return (intptr_t*)uc->uc_mcontext.gregs[15/*REG_SP*/];

}

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

  return NULL;

}

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, 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_context(uc);

    if (!fr->is_first_java_frame()) {

      assert(fr->safe_for_sender(thread), "Safety check");

      *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. In compiled code, we bang before

      // the frame is complete.

      return false;

    } else {

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

      address lr = ucontext_get_lr(uc);

      *fr = frame(sp, lr);

      if (!fr->is_java_frame()) {

        assert(fr->safe_for_sender(thread), "Safety check");

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

        *fr = fr->java_sender();

      }

    }

  }

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

  return true;

}

frame os::get_sender_for_C_frame(frame* fr) {

  if (*fr->sp() == 0) {

    // fr is the last C frame.

    return frame();

  }

  // If its not one of our frames, the return pc is saved at gpr14

  // stack slot. The call_stub stores the return_pc to the stack slot

  // of gpr10.

  if ((Interpreter::code() != NULL && Interpreter::contains(fr->pc())) ||

      (CodeCache::contains(fr->pc()) && !StubRoutines::contains(fr->pc()))) {

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

  } else {

    if (StubRoutines::contains(fr->pc())) {

      StubCodeDesc* desc = StubCodeDesc::desc_for(fr->pc());

      if (desc && !strcmp(desc->name(),"call_stub")) {

        return frame(fr->sender_sp(), fr->callstub_sender_pc());

      } else {

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

      }

    } else {

      return frame(fr->sender_sp(), fr->native_sender_pc());

    }

  }

}

frame os::current_frame() {

  // Expected to return the stack pointer of this method.

  // But if inlined, returns the stack pointer of our caller!

  intptr_t* csp = (intptr_t*) *((intptr_t*) os::current_stack_pointer());

  assert (csp != NULL, "sp should not be NULL");

  // Pass a dummy pc. This way we don't have to load it from the

  // stack, since we don't know in which slot we can find it.

  frame topframe(csp, (address)0x8);

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

    // Stack is not walkable.

    return frame();

  } else {

    frame senderFrame = os::get_sender_for_C_frame(&topframe);

    assert(senderFrame.pc() != NULL, "Sender pc should not be NULL");

    // Return sender of sender of current topframe which hopefully

    // both have pc != NULL.

#ifdef _NMT_NOINLINE_   // Is set in slowdebug builds.

    // Current_stack_pointer is not inlined, we must pop one more frame.

    frame tmp = os::get_sender_for_C_frame(&topframe);

    return os::get_sender_for_C_frame(&tmp);

#else

    return os::get_sender_for_C_frame(&topframe);

#endif

  }

}

// Utility functions

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) {

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

      return true;

    } else {

      if (PrintMiscellaneous && (WizardMode || Verbose)) {

        warning("Ignoring SIGPIPE - see bug 4229104");

      }

      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;

      }

    }

  }

  // Moved SafeFetch32 handling outside thread!=NULL conditional block to make

  // it work if no associated JavaThread object exists.

  if (uc) {

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

    if (pc && StubRoutines::is_safefetch_fault(pc)) {

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

      return true;

    }

  }

  // Decide if this trap can be handled by a stub.

  address stub    = NULL;

  address pc      = NULL;  // Pc as retrieved from PSW. Usually points past failing instruction.

  address trap_pc = NULL;  // Pc of the instruction causing the trap.

  //%note os_trap_1

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

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

    if (TraceTraps) {

      tty->print_cr("     pc at " INTPTR_FORMAT, p2i(pc));

    }

    if ((unsigned long)(pc - (address)info->si_addr) <= (unsigned long)Assembler::instr_maxlen() ) {

      trap_pc = (address)info->si_addr;

      if (TraceTraps) {

        tty->print_cr("trap_pc at " INTPTR_FORMAT, p2i(trap_pc));

      }

    }

    // Handle ALL stack overflow variations here

    if (sig == SIGSEGV) {

      address addr = (address)info->si_addr; // Address causing SIGSEGV, usually mem ref target.

      // 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 Javac 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());

                  } 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 (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

      // Handle signal from NativeJump::patch_verified_entry().

      if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_zombie_not_entrant()) {

        if (TraceTraps) {

          tty->print_cr("trap: zombie_not_entrant (SIGILL)");

        }

        stub = SharedRuntime::get_handle_wrong_method_stub();

      }

      else if (sig == SIGSEGV &&

               os::is_poll_address((address)info->si_addr)) {

        if (TraceTraps) {

          tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));

        }

        stub = SharedRuntime::get_poll_stub(pc);

        // Info->si_addr only points to the page base address, so we

        // must extract the real si_addr from the instruction and the

        // ucontext.

        assert(((NativeInstruction*)pc)->is_safepoint_poll(), "must be safepoint poll");

        const address real_si_addr = ((NativeInstruction*)pc)->get_poll_address(uc);

      }

      // SIGTRAP-based implicit null check in compiled code.

      else if ((sig == SIGFPE) &&

               TrapBasedNullChecks &&

               (trap_pc != NULL) &&

               Assembler::is_sigtrap_zero_check(trap_pc)) {

        if (TraceTraps) {

          tty->print_cr("trap: NULL_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));

        }

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

      }

      else if (sig == SIGSEGV && ImplicitNullChecks &&

               CodeCache::contains((void*) pc) &&

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

        if (TraceTraps) {

          tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));

        }

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

      }

      // SIGTRAP-based implicit range check in compiled code.

      else if (sig == SIGFPE && TrapBasedRangeChecks &&

               (trap_pc != NULL) &&

               Assembler::is_sigtrap_range_check(trap_pc)) {

        if (TraceTraps) {

          tty->print_cr("trap: RANGE_CHECK at " INTPTR_FORMAT " (SIGFPE)", p2i(trap_pc));

        }

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

      }

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

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

      }

      else if (sig == SIGBUS) {

        // 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;

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

          // We don't really need a stub here! Just set the pending exeption and

          // continue at the next instruction after the faulting read. Returning

          // garbage from this read is ok.

          thread->set_pending_unsafe_access_error();

          uc->uc_mcontext.psw.addr = ((unsigned long)pc) + Assembler::instr_len(pc);

          return true;

        }

      }

    }

    else { // thread->thread_state() != _thread_in_Java

      if ((sig == SIGILL) && VM_Version::is_determine_features_test_running()) {

        // SIGILL must be caused by VM_Version::determine_features()

        // when attempting to execute a non-existing instruction.

        //*(int *) (pc-6)=0; // Patch instruction to 0 to indicate that it causes a SIGILL.

                             // Flushing of icache is not necessary.

        stub = pc; // Continue with next instruction.

      } else if ((sig == SIGFPE) && VM_Version::is_determine_features_test_running()) {

        // SIGFPE is known to be caused by trying to execute a vector instruction

        // when the vector facility is installed, but operating system support is missing.

        VM_Version::reset_has_VectorFacility();

        stub = pc; // Continue with next instruction.

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

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

                 sig == SIGBUS && thread->doing_unsafe_access()) {

        // We don't really need a stub here! Just set the pending exeption and

        // continue at the next instruction after the faulting read. Returning

        // garbage from this read is ok.

        thread->set_pending_unsafe_access_error();

        os::Linux::ucontext_set_pc(uc, pc + Assembler::instr_len(pc));

        return true;

      }

    }

    // 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;

      }

    }

  }

  if (stub != NULL) {

    // Save all thread context in case we need to restore it.

    if (thread != NULL) thread->set_saved_exception_pc(pc);

    os::Linux::ucontext_set_pc(uc, stub);

    return true;

  }

  // signal-chaining

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

    return true;

  }

  if (!abort_if_unrecognized) {

    // caller wants another chance, so give it to him

    return false;

  }

  if (pc == NULL && uc != NULL) {

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

  }

  // unmask current signal

  sigset_t newset;

  sigemptyset(&newset);

  sigaddset(&newset, sig);

  sigprocmask(SIG_UNBLOCK, &newset, NULL);