/*

 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.

 * Copyright (c) 2012, 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.

 *

 */

// 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/codeCache.hpp"

#include "code/icBuffer.hpp"

#include "code/vtableStubs.hpp"

#include "interpreter/interpreter.hpp"

#include "memory/allocation.inline.hpp"

#include "nativeInst_ppc.hpp"

#include "os_share_aix.hpp"

#include "prims/jniFastGetField.hpp"

#include "prims/jvm_misc.hpp"

#include "porting_aix.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/safepointMechanism.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"

#ifdef COMPILER1

#include "c1/c1_Runtime1.hpp"

#endif

#ifdef COMPILER2

#include "opto/runtime.hpp"

#endif

// put OS-includes here

# include <ucontext.h>

address os::current_stack_pointer() {

  address csp;

#if !defined(USE_XLC_BUILTINS)

  // inline assembly for `mr regno(csp), R1_SP':

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

#else

  csp = (address) __builtin_frame_address(0);

#endif

  return 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_ppc.hpp.

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

  return (address)uc->uc_mcontext.jmp_context.iar;

}

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

  // gpr1 holds the stack pointer on aix

  return (intptr_t*)uc->uc_mcontext.jmp_context.gpr[1/*REG_SP*/];

}

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

  return NULL;

}

void os::Aix::ucontext_set_pc(ucontext_t* uc, address new_pc) {

  uc->uc_mcontext.jmp_context.iar = (uint64_t) new_pc;

}

static address ucontext_get_lr(const ucontext_t * uc) {

  return (address)uc->uc_mcontext.jmp_context.lr;

}

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::Aix::ucontext_get_pc(uc));

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

    if (ret_fp) *ret_fp = os::Aix::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);

  // Avoid crash during crash if pc broken.

  if (epc.pc()) {

    frame fr(sp, epc.pc());

    return fr;

  }

  frame fr(sp);

  return fr;

}

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

  address pc = (address) os::Aix::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::Aix::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() == NULL) {

    // 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_aix_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_aix_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::Aix::chained_handler(sig, info, ucVoid)) {

      return 1;

    } else {

      // Ignoring SIGPIPE - see bugs 4229104

      return 1;

    }

  }

  JavaThread* thread = NULL;

  VMThread* vmthread = NULL;

  if (os::Aix::signal_handlers_are_installed) {

    if (t != NULL) {

      if(t->is_Java_thread()) {

        thread = (JavaThread*)t;

      }

      else if(t->is_VM_thread()) {

        vmthread = (VMThread *)t;

      }

    }

  }

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

  address stub = NULL;

  // retrieve program counter

  address const pc = uc ? os::Aix::ucontext_get_pc(uc) : NULL;

  // retrieve crash address

  address const addr = info ? (const address) info->si_addr : NULL;

  // SafeFetch 32 handling:

  // - make it work if _thread is null

  // - make it use the standard os::...::ucontext_get/set_pc APIs

  if (uc) {

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

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

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

      return true;

    }

  }

  if (info == NULL || uc == NULL || thread == NULL && vmthread == NULL) {

    goto run_chained_handler;

  }

  // If we are a java thread...

  if (thread != NULL) {

    // Handle ALL stack overflow variations here

    if (sig == SIGSEGV && thread->on_local_stack(addr)) {

      // stack overflow

      //

      // If we are in a yellow zone and we are inside java, we disable the yellow zone and

      // throw a stack overflow exception.

      // If we are in native code or VM C code, we report-and-die. The original coding tried

      // to continue with yellow zone disabled, but that doesn't buy us much and prevents

      // hs_err_pid files.

      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::Aix::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);

          goto run_stub;

        } 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.");

        goto report_and_die;

      } else {

        // This means a segv happened inside our stack, but not in

        // the guarded zone. I'd like to know when this happens,

        tty->print_raw_cr("SIGSEGV happened inside stack but outside yellow and red zone.");

        goto report_and_die;

      }

    } // end handle SIGSEGV inside stack boundaries

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

      // Java thread running in Java code

      // The following signals are used for communicating VM events:

      //

      // SIGILL: the compiler generates illegal opcodes

      //   at places where it wishes to interrupt the VM:

      //   Safepoints, Unreachable Code, Entry points of Zombie methods,

      //    This results in a SIGILL with (*pc) == inserted illegal instruction.

      //

      //   (so, SIGILLs with a pc inside the zero page are real errors)

      //

      // SIGTRAP:

      //   The ppc trap instruction raises a SIGTRAP and is very efficient if it

      //   does not trap. It is used for conditional branches that are expected

      //   to be never taken. These are:

      //     - zombie methods

      //     - IC (inline cache) misses.

      //     - null checks leading to UncommonTraps.

      //     - range checks leading to Uncommon Traps.

      //   On Aix, these are especially null checks, as the ImplicitNullCheck

      //   optimization works only in rare cases, as the page at address 0 is only

      //   write protected.      //

      //   Note: !UseSIGTRAP is used to prevent SIGTRAPS altogether, to facilitate debugging.

      //

      // SIGSEGV:

      //   used for safe point polling:

      //     To notify all threads that they have to reach a safe point, safe point polling is used:

      //     All threads poll a certain mapped memory page. Normally, this page has read access.

      //     If the VM wants to inform the threads about impending safe points, it puts this

      //     page to read only ("poisens" the page), and the threads then reach a safe point.

      //   used for null checks:

      //     If the compiler finds a store it uses it for a null check. Unfortunately this

      //     happens rarely.  In heap based and disjoint base compressd oop modes also loads

      //     are used for null checks.

      // 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;

      }

      // 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();

        goto run_stub;

      }

      else if ((SafepointMechanism::uses_thread_local_poll() && USE_POLL_BIT_ONLY)

               ? (sig == SIGTRAP && ((NativeInstruction*)pc)->is_safepoint_poll())

               : (sig == SIGSEGV && os::is_poll_address(addr))) {

        if (TraceTraps) {

          tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (%s)", p2i(pc),

                        (SafepointMechanism::uses_thread_local_poll() && USE_POLL_BIT_ONLY) ? "SIGTRAP" : "SIGSEGV");

        }

        stub = SharedRuntime::get_poll_stub(pc);

        goto run_stub;

      }

      // 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)", pc);

        }

        stub = SharedRuntime::get_ic_miss_stub();

        goto run_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)", pc);

        }

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

        goto run_stub;

      }

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

      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)", 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)", pc);

        }

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

        goto run_stub;

      }

#endif

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

        if (TraceTraps) {

          tty->print_raw_cr("Fix SIGFPE handler, trying divide by zero handler.");

        }

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

        goto run_stub;

      }

      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->as_compiled_method_or_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 = pc + 4;

          if (is_unsafe_arraycopy) {

            next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);

          }

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

          os::Aix::ucontext_set_pc(uc, next_pc);

          return 1;

        }

      }

    }

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

      // Detect CPU features. This is only done at the very start of the VM. Later, the

      // VM_Version::is_determine_features_test_running() flag should be false.

      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.

        goto run_stub;

      }

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

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

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

        address next_pc = pc + 4;

        if (UnsafeCopyMemory::contains_pc(pc)) {

          next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);

        }

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

        os::Aix::ucontext_set_pc(uc, next_pc);

        return 1;

      }

    }

    // 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;

      }

    }

  }

run_stub:

  // One of the above code blocks ininitalized the stub, so we want to

  // delegate control to that stub.

  if (stub != NULL) {

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

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

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

    return 1;

  }

run_chained_handler:

  // signal-chaining

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

    return 1;

  }

  if (!abort_if_unrecognized) {

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

    return 0;

  }

report_and_die: