/*

 * Copyright (c) 2008, 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 "assembler_arm.inline.hpp"

#include "classfile/classLoader.hpp"

#include "classfile/systemDictionary.hpp"

#include "classfile/vmSymbols.hpp"

#include "code/icBuffer.hpp"

#include "code/vtableStubs.hpp"

#include "interpreter/interpreter.hpp"

#include "memory/allocation.inline.hpp"

#include "nativeInst_arm.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/timer.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>

# include <fpu_control.h>

# include <asm/ptrace.h>

#define SPELL_REG_SP  "sp"

// Don't #define SPELL_REG_FP for thumb because it is not safe to use, so this makes sure we never fetch it.

#ifndef __thumb__

#define SPELL_REG_FP "fp"

#endif

address os::current_stack_pointer() {

  register address sp __asm__ (SPELL_REG_SP);

  return sp;

}

char* os::non_memory_address_word() {

  // Must never look like an address returned by reserve_memory

  return (char*) -1;

}

#if NGREG == 16

// These definitions are based on the observation that until

// the certain version of GCC mcontext_t was defined as

// a structure containing gregs[NGREG] array with 16 elements.

// In later GCC versions mcontext_t was redefined as struct sigcontext,

// along with NGREG constant changed to 18.

#define arm_pc gregs[15]

#define arm_sp gregs[13]

#define arm_fp gregs[11]

#define arm_r0 gregs[0]

#endif

#define ARM_REGS_IN_CONTEXT  16

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

  return (address)uc->uc_mcontext.arm_pc;

}

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

  uc->uc_mcontext.arm_pc = (uintx)pc;

}

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

  return (intptr_t*)uc->uc_mcontext.arm_sp;

}

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

  return (intptr_t*)uc->uc_mcontext.arm_fp;

}

bool is_safe_for_fp(address pc) {

#ifdef __thumb__

  if (CodeCache::find_blob(pc) != NULL) {

    return true;

  }

  // For thumb C frames, given an fp we have no idea how to access the frame contents.

  return false;

#else

  // Calling os::address_is_in_vm() here leads to a dladdr call. Calling any libc

  // function during os::get_native_stack() can result in a deadlock if JFR is

  // enabled. For now, be more lenient and allow all pc's. There are other

  // frame sanity checks in shared code, and to date they have been sufficient

  // for other platforms.

  //return os::address_is_in_vm(pc);

  return true;

#endif

}

// 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().

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) {

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

#ifndef __thumb__

      if (CodeCache::find_blob(epc.pc()) == NULL) {

        // It's a C frame. We need to adjust the fp.

        fp += os::C_frame_offset;

      }

#endif

      // Clear FP when stack walking is dangerous so that

      // the frame created will not be walked.

      // However, ensure FP is set correctly when reliable and

      // potentially necessary.

      if (!is_safe_for_fp(epc.pc())) {

        // FP unreliable

        fp = (intptr_t *)NULL;

      }

      *ret_fp = fp;

    }

  } 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::get_sender_for_C_frame(frame* fr) {

#ifdef __thumb__

  // We can't reliably get anything from a thumb C frame.

  return frame();

#else

  address pc = fr->sender_pc();

  if (! is_safe_for_fp(pc)) {

    return frame(fr->sender_sp(), (intptr_t *)NULL, pc);

  } else {

    return frame(fr->sender_sp(), fr->link() + os::C_frame_offset, pc);

  }

#endif

}

//

// This actually returns two frames up. It does not return os::current_frame(),

// which is the actual current frame. Nor does it return os::get_native_stack(),

// which is the caller. It returns whoever called os::get_native_stack(). Not

// very intuitive, but consistent with how this API is implemented on other

// platforms.

//

frame os::current_frame() {

#ifdef __thumb__

  // We can't reliably get anything from a thumb C frame.

  return frame();

#else

  register intptr_t* fp __asm__ (SPELL_REG_FP);

  // fp is for os::current_frame. We want the fp for our caller.

  frame myframe((intptr_t*)os::current_stack_pointer(), fp + os::C_frame_offset,

                 CAST_FROM_FN_PTR(address, os::current_frame));

  frame caller_frame = os::get_sender_for_C_frame(&myframe);

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

    // stack is not walkable

    // Assert below was added because it does not seem like this can ever happen.

    // How can this frame ever be the first C frame since it is called from C code?

    // If it does ever happen, undo the assert and comment here on when/why it happens.

    assert(false, "this should never happen");

    return frame();

  }

  // return frame for our caller's caller

  return os::get_sender_for_C_frame(&caller_frame);

#endif

}

extern "C" address check_vfp_fault_instr;

extern "C" address check_vfp3_32_fault_instr;

extern "C" address check_simd_fault_instr;

extern "C" address check_mp_ext_fault_instr;

address check_vfp_fault_instr = NULL;

address check_vfp3_32_fault_instr = NULL;

address check_simd_fault_instr = NULL;

address check_mp_ext_fault_instr = NULL;

// Utility functions

extern "C" 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);

  if (sig == SIGILL &&

      ((info->si_addr == (caddr_t)check_simd_fault_instr)

       || info->si_addr == (caddr_t)check_vfp_fault_instr

       || info->si_addr == (caddr_t)check_vfp3_32_fault_instr

       || info->si_addr == (caddr_t)check_mp_ext_fault_instr)) {

    // skip faulty instruction + instruction that sets return value to

    // success and set return value to failure.

    os::Linux::ucontext_set_pc(uc, (address)info->si_addr + 8);

    uc->uc_mcontext.arm_r0 = 0;

    return true;

  }

  // 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;

      }

    }

  }

  address stub = NULL;

  address pc = NULL;

  bool unsafe_access = false;

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

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

    // Handle ALL stack overflow variations here

    if (sig == SIGSEGV) {

      address addr = (address) info->si_addr;

      if (StubRoutines::is_safefetch_fault(pc)) {

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

        return 1;

      }

      // check if fault address is within thread stack

      if (addr < thread->stack_base() &&

          addr >= thread->stack_base() - thread->stack_size()) {

        // stack overflow

        if (thread->in_stack_yellow_reserved_zone(addr)) {

          thread->disable_stack_yellow_reserved_zone();

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

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

            // while unwinding the stack.

            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.

            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.");

        } 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

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

        stub = SharedRuntime::get_poll_stub(pc);

      } 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()) || (thread->doing_unsafe_access() && UnsafeCopyMemory::contains_pc(pc))) {

          unsafe_access = true;

        }

      } else if (sig == SIGSEGV &&

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

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

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

          if (cb != NULL) {

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

          }

      } else if (sig == SIGILL && *(int *)pc == NativeInstruction::zombie_illegal_instruction) {

        // Zombie

        stub = SharedRuntime::get_handle_wrong_method_stub();

      }

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

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

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

        unsafe_access = 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 (unsafe_access && stub == NULL) {

    // it can be an unsafe access and we haven't found

    // any other suitable exception reason,

    // so assume it is an unsafe access.

    address next_pc = pc + Assembler::InstructionSize;

    if (UnsafeCopyMemory::contains_pc(pc)) {

      next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);

    }

#ifdef __thumb__

    if (uc->uc_mcontext.arm_cpsr & PSR_T_BIT) {

      next_pc = (address)((intptr_t)next_pc | 0x1);

    }

#endif

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

  }

  if (stub != NULL) {

#ifdef __thumb__

    if (uc->uc_mcontext.arm_cpsr & PSR_T_BIT) {

      intptr_t p = (intptr_t)pc | 0x1;

      pc = (address)p;

      // Clear Thumb mode bit if we're redirected into the ARM ISA based code

      if (((intptr_t)stub & 0x1) == 0) {

        uc->uc_mcontext.arm_cpsr &= ~PSR_T_BIT;

      }

    } else {

      // No Thumb2 compiled stubs are triggered from ARM ISA compiled JIT'd code today.

      // The support needs to be added if that changes

      assert((((intptr_t)stub & 0x1) == 0), "can't return to Thumb code");

    }

#endif

    // 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);

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

  ShouldNotReachHere();

  return false;

}

void os::Linux::init_thread_fpu_state(void) {

  os::setup_fpu();

}

int os::Linux::get_fpu_control_word(void) {

  return 0;

}

void os::Linux::set_fpu_control_word(int fpu_control) {

  // Nothing to do

}

void os::setup_fpu() {

#if !defined(__SOFTFP__) && defined(__VFP_FP__)

  // Turn on IEEE-754 compliant VFP mode

  __asm__ volatile (

    "mov %%r0, #0;"

    "fmxr fpscr, %%r0"

    : /* no output */ : /* no input */ : "r0"

  );

#endif

}

bool os::is_allocatable(size_t bytes) {

  return true;

}

////////////////////////////////////////////////////////////////////////////////

// thread stack

// Minimum usable stack sizes required to get to user code. Space for

// HotSpot guard pages is added later.

size_t os::Posix::_compiler_thread_min_stack_allowed = (32 DEBUG_ONLY(+ 4)) * K;

size_t os::Posix::_java_thread_min_stack_allowed = (32 DEBUG_ONLY(+ 4)) * K;

size_t os::Posix::_vm_internal_thread_min_stack_allowed = (48 DEBUG_ONLY(+ 4)) * K;

// return default stack size for thr_type

size_t os::Posix::default_stack_size(os::ThreadType thr_type) {

  // default stack size (compiler thread needs larger stack)

  size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);