/*

 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.

 * Copyright (c) 2012, 2016 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.

 *

 */

// no precompiled headers

#include "asm/assembler.inline.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 "jvm_linux.h"

#include "memory/allocation.inline.hpp"

#include "nativeInst_ppc.hpp"

#include "os_share_linux.hpp"

#include "prims/jniFastGetField.hpp"

#include "prims/jvm.h"

#include "prims/jvm_misc.hpp"

#include "runtime/arguments.hpp"

#include "runtime/extendedPC.hpp"

#include "runtime/frame.inline.hpp"

#include "runtime/interfaceSupport.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/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 `mr regno(csp), R1_SP':

  __asm__ __volatile__ ("mr %0, 1":"=r"(csp):);

  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;

}

void os::initialize_thread(Thread *thread) { }

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

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

// conventions in frame_ppc64.hpp.

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

  // On powerpc64, ucontext_t is not selfcontained but contains

  // a pointer to an optional substructure (mcontext_t.regs) containing the volatile

  // registers - NIP, among others.

  // This substructure may or may not be there depending where uc came from:

  // - if uc was handed over as the argument to a sigaction handler, a pointer to the

  //   substructure was provided by the kernel when calling the signal handler, and

  //   regs->nip can be accessed.

  // - if uc was filled by getcontext(), it is undefined - getcontext() does not fill

  //   it because the volatile registers are not needed to make setcontext() work.

  //   Hopefully it was zero'd out beforehand.

  guarantee(uc->uc_mcontext.regs != NULL, "only use ucontext_get_pc in sigaction context");

  return (address)uc->uc_mcontext.regs->nip;

}

// modify PC in ucontext.

// Note: Only use this for an ucontext handed down to a signal handler. See comment

// in ucontext_get_pc.

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

  guarantee(uc->uc_mcontext.regs != NULL, "only use ucontext_set_pc in sigaction context");

  uc->uc_mcontext.regs->nip = (unsigned long)pc;

}

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

  return (intptr_t*)uc->uc_mcontext.regs->gpr[1/*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* fp = os::Linux::ucontext_get_fp(uc);

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

      *fr = frame(sp, (address)*sp);

      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(NULL, NULL);

  }

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

}

frame os::current_frame() {

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

  // hack.

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

  // Return sender of sender of current topframe which hopefully

  // both have pc != NULL.

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

  return os::get_sender_for_C_frame(&tmp);

}

// 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();

  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 {

      // Ignoring SIGPIPE - see bugs 4229104

      return true;

    }

  }

  // Make the signal handler transaction-aware by checking the existence of a

  // second (transactional) context with MSR TS bits active. If the signal is

  // caught during a transaction, then just return to the HTM abort handler.

  // Please refer to Linux kernel document powerpc/transactional_memory.txt,

  // section "Signals".

  if (uc && uc->uc_link) {

    ucontext_t* second_uc = uc->uc_link;

    // MSR TS bits are 29 and 30 (Power ISA, v2.07B, Book III-S, pp. 857-858,

    // 3.2.1 "Machine State Register"), however note that ISA notation for bit

    // numbering is MSB 0, so for normal bit numbering (LSB 0) they come to be

    // bits 33 and 34. It's not related to endianness, just a notation matter.

    if (second_uc->uc_mcontext.regs->msr & 0x600000000) {

      if (TraceTraps) {

        tty->print_cr("caught signal in transaction, "

                        "ignoring to jump to abort handler");

      }

      // Return control to the HTM abort handler.

      return true;

    }

  }

  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;

  //%note os_trap_1

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

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

    // Handle ALL stack overflow variations here

    if (sig == SIGSEGV) {

      // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see

      // comment below). Use get_stack_bang_address instead of si_addr.

      address addr = ((NativeInstruction*)pc)->get_stack_bang_address(uc);

      // 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

      // A VM-related SIGILL may only occur if we are not in the zero page.

      // On AIX, we get a SIGILL if we jump to 0x0 or to somewhere else

      // in the zero page, because it is filled with 0x0. We ignore

      // explicit SIGILLs in the zero page.

      if (sig == SIGILL && (pc < (address) 0x200)) {

        if (TraceTraps) {

          tty->print_raw_cr("SIGILL happened inside zero page.");

        }

        goto report_and_die;

      }

      CodeBlob *cb = NULL;

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

      if (( TrapBasedNotEntrantChecks && sig == SIGTRAP && nativeInstruction_at(pc)->is_sigtrap_zombie_not_entrant()) ||

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

        if (TraceTraps) {

          tty->print_cr("trap: zombie_not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");

        }

        stub = SharedRuntime::get_handle_wrong_method_stub();

      }

      else if (sig == SIGSEGV &&

               // A linux-ppc64 kernel before 2.6.6 doesn't set si_addr on some segfaults

               // in 64bit mode (cf. http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.6),

               // especially when we try to read from the safepoint polling page. So the check

               //   (address)info->si_addr == os::get_standard_polling_page()

               // doesn't work for us. We use:

               ((NativeInstruction*)pc)->is_safepoint_poll() &&

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

               ((cb = CodeCache::find_blob(pc)) != NULL) &&

               cb->is_compiled()) {

        if (TraceTraps) {

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

        }

        stub = SharedRuntime::get_poll_stub(pc);

      }

      // SIGTRAP-based ic miss check in compiled code.

      else if (sig == SIGTRAP && TrapBasedICMissChecks &&

               nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) {

        if (TraceTraps) {

          tty->print_cr("trap: ic_miss_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));

        }

        stub = SharedRuntime::get_ic_miss_stub();

      }

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

      else if (sig == SIGTRAP && TrapBasedNullChecks &&

               nativeInstruction_at(pc)->is_sigtrap_null_check()) {

        if (TraceTraps) {

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

        }

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

      }

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

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

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

               !MacroAssembler::needs_explicit_null_check((intptr_t) 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);

      }

#ifdef COMPILER2

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

      else if (sig == SIGTRAP && TrapBasedRangeChecks &&

               nativeInstruction_at(pc)->is_sigtrap_range_check()) {

        if (TraceTraps) {

          tty->print_cr("trap: range_check at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));

        }

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

      }

#endif

      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()) {

          address next_pc = pc + 4;

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

          os::Linux::ucontext_set_pc(uc, next_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().

        *(int *)pc = 0; // patch instruction to 0 to indicate that it causes a SIGILL,

                        // flushing of icache is not necessary.

        stub = pc + 4;  // continue with next instruction.

      }

      else if (thread->thread_state() == _thread_in_vm &&

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

        address next_pc = pc + 4;

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

        os::Linux::ucontext_set_pc(uc, pc + 4);

        return true;

      }

    }

    // Check to see if we caught the safepoint code in the

    // process of write protecting the memory serialization page.

    // It write enables the page immediately after protecting it

    // so we can just return to retry the write.

    if ((sig == SIGSEGV) &&

        // Si_addr may not be valid due to a bug in the linux-ppc64 kernel (see comment above).

        // Use is_memory_serialization instead of si_addr.

        ((NativeInstruction*)pc)->is_memory_serialization(thread, ucVoid)) {

      // Synchronization problem in the pseudo memory barrier code (bug id 6546278)

      // Block current thread until the memory serialize page permission restored.

      os::block_on_serialize_page_trap();

      return true;

    }

  }

  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);

  }

report_and_die:

  // unmask current signal

  sigset_t newset;

  sigemptyset(&newset);

  sigaddset(&newset, sig);

  sigprocmask(SIG_UNBLOCK, &newset, NULL);

  VMError::report_and_die(t, sig, pc, info, ucVoid);