/*

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

 * Copyright (c) 2019 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

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 */

#include "asm/assembler.inline.hpp"

#include "asm/macroAssembler.hpp"

#include "code/codeCache.hpp"

#include "compiler/disassembler.hpp"

#include "depChecker_s390.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/cardTableBarrierSet.hpp"

#include "gc/shared/genOopClosures.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/stubCodeGenerator.hpp"

#include "runtime/stubRoutines.hpp"

#include "utilities/align.hpp"

// List of all major opcodes, as of

// Principles of Operation, Eleventh Edition, March 2015

bool Disassembler::valid_opcodes[] =

{ true,  true,  false, false, true,  true,  true,  true,  // 0x00..07

  false, false, true,  true,  true,  true,  true,  true,  // 0x08..0f

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x10..17

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x18..1f

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x20..27

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x28..2f

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x30..37

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x38..3f

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x40..47

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x48..4f

  true,  true,  false, false, true,  true,  true,  true,  // 0x50..57

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x58..5f

  true,  false, false, false, false, false, false, true,  // 0x60..67

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x68..6f

  true,  true,  false, false, false, false, false, false, // 0x70..77

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x78..7f

  true,  false, true,  true,  true,  true,  true,  true,  // 0x80..87

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x88..8f

  true,  true,  true,  true,  true,  true,  true,  true,  // 0x90..97

  true,  true,  true,  true,  false, false, false, false, // 0x98..9f

  false, false, false, false, false, true,  false, true,  // 0xa0..a7

  true,  true,  false, false, true,  true,  true,  true,  // 0xa8..af

  false, true,  true,  true,  false, false, true,  true,  // 0xb0..b7

  false, true,  true,  true,  false, true,  true,  true,  // 0xb8..bf

  true,  false, true,  false, true,  false, true,  false, // 0xc0..c7

  true,  false, false, false, true,  false, false, false, // 0xc8..cf

  true,  true,  true,  true,  true,  true,  true,  true,  // 0xd0..d7

  false, true,  true,  true,  true,  true,  true,  true,  // 0xd8..df

  false, true,  true,  true,  false, true,  false, true,  // 0xe0..e7

  true,  true,  true,  true,  true,  true,  true,  true,  // 0xe8..ef

  true,  true,  true,  true,  false, false, false, false, // 0xf0..f7

  true,  true,  true,  true,  true,  true,  false, false, // 0xf8..ff

};

// Check for valid opcodes.

//

// The major opcode (one byte) at the passed location is inspected.

// If the opcode found is assigned, the function returns true, false otherwise.

// The true indication is not reliable. It may well be that the major opcode is

// assigned, but there exists a minor opcode field in the instruction which

// which has unassigned values.

bool Disassembler::is_valid_opcode_at(address here) {

  return valid_opcodes[*here];

}

// This method does plain instruction decoding, no frills.

// It may be called before the binutils disassembler kicks in

// to handle special cases the binutils disassembler does not.

// Instruction address, comments, and the like have to be output by caller.

address Disassembler::decode_instruction0(address here, outputStream * st, address virtual_begin) {

  if (is_abstract()) {

    // The disassembler library was not loaded (yet),

    // use AbstractDisassembler's decode-method.

    return decode_instruction_abstract(here, st, Assembler::instr_len(here), Assembler::instr_maxlen());

  }

  // Currently, "special decoding" doesn't work when decoding error files.

  // When decoding an instruction from a hs_err file, the given

  // instruction address 'start' points to the instruction's virtual address

  // which is not equal to the address where the instruction is located.

  // Therefore, we will either crash or decode garbage.

  if (is_decode_error_file()) {

    return here;

  }

  //---<  Decode some well-known "instructions"  >---

  address  next;

  uint16_t instruction_2bytes = *(uint16_t*)here;

  if (Assembler::is_z_nop((long)instruction_2bytes)) {

#if 1

    st->print("nop     ");  // fill up to operand column, leads to better code comment alignment

    next = here + 2;

#else

    // Compact disassembler output. Does not work the easy way.

    // Currently unusable, search does not terminate, risk of crash.

    // TODO: rework required.

    // Terminate search loop when reaching CodeEntryAlignment-aligned offset

    // or, at the latest, when reaching the next page boundary.

    int n_nops = 0;

    while(is_same_page(here, here+2*n_nops) && Assembler::is_z_nop((long)instruction_2bytes)) {

      n_nops++;

      instruction_2bytes   = *(uint16_t*)(here+2*n_nops);

    }

    if (n_nops <= 4) { // do not group few subsequent nops

      st->print("nop     ");  // fill up to operand column, leads to better code comment alignment

      next = here + 2;

    } else {

      st->print("nop     count=%d", n_nops);

      next = here + 2*n_nops;

    }

#endif

  } else if (Assembler::is_z_sync((long)instruction_2bytes)) {

    // Specific names. Make use of lightweight sync.

    st->print("sync   ");

    if (Assembler::is_z_sync_full((long)instruction_2bytes) ) st->print("heavyweight");

    if (Assembler::is_z_sync_light((long)instruction_2bytes)) st->print("lightweight");

    next = here + 2;

  } else if (instruction_2bytes == 0x0000) {

#if 1

    st->print("illtrap .nodata");

    next = here + 2;

#else

    // Compact disassembler output. Does not work the easy way.

    // Currently unusable, search does not terminate, risk of crash.

    // TODO: rework required.

    // Terminate search loop when reaching CodeEntryAlignment-aligned offset

    // or, at the latest, when reaching the next page boundary.

    int n_traps = 0;

    while(is_same_page(here, here+2*n_nops) && (instruction_2bytes == 0x0000)) {

      n_traps++;

      instruction_2bytes   = *(uint16_t*)(here+2*n_traps);

    }

    if (n_traps <= 4) { // do not group few subsequent illtraps

      st->print("illtrap .nodata");

      next = here + 2;

    } else {

      st->print("illtrap .nodata count=%d", n_traps);

      next = here + 2*n_traps;

    }

#endif

  } else if ((instruction_2bytes & 0xff00) == 0x0000) {

    st->print("illtrap .data 0x%2.2x", instruction_2bytes & 0x00ff);

    next = here + 2;

  } else {

     next = here;

  }

  return next;

}

// Count the instructions contained in the range [begin..end).

// The range must exactly contain the instructions, i.e.

//  - the first instruction starts @begin

//  - the last instruction ends @(end-1)

// The caller has to make sure that the given range is readable.

// This function performs no safety checks!

// Return value:

//  - The number of instructions, if there was exact containment.

//  - If there is no exact containment, a negative value is returned.

//    Its absolute value is the number of instructions from begin to end,

//    where the last instruction counted runs over the range end.

//  - 0 (zero) is returned if there was a parameter error

//    (inverted range, bad starting point).

int Disassembler::count_instr(address begin, address end) {

  if (end < begin+2) return 0; // no instructions in range

  if (!Disassembler::is_valid_opcode_at(begin)) return 0; // bad starting point

  address p = begin;

  int     n = 0;

  while(p < end) {

    p += Assembler::instr_len(p);

    n++;

  }

  return (p == end) ? n : -n;

}

// Find preceding instruction.

//

// Starting at the passed location, the n-th preceding (towards lower addresses)

// instruction is searched. With variable length instructions, there may be

// more than one solution, or no solution at all (if the passed location

// does not point to the start of an instruction or if the storage area

// does not contain instructions at all).

// instructions - has the passed location as n-th successor.

//  - If multiple such locations exist between (here-n*instr_maxlen()) and here,

//    the most distant location is selected.

//  - If no such location exists, NULL is returned. The caller should then

//    terminate its search and react properly.

// Must be placed here in disassembler_s390.cpp. It does not compile

// in the header. There the class 'Assembler' is not available.

address Disassembler::find_prev_instr(address here, int n_instr) {

  if (!os::is_readable_pointer(here)) return NULL;    // obviously a bad location to decode

  // Find most distant possible starting point.

  // Narrow down because we don't want to SEGV while printing.

  address start = here - n_instr*Assembler::instr_maxlen(); // starting point can't be further away.

  while ((start < here) && !os::is_readable_range(start, here)) {

    start = align_down(start, os::min_page_size()) + os::min_page_size();

  }

  if (start >= here) {

    // Strange. Can only happen with here on page boundary.

    return NULL;

  }

  //---<  Find a starting point  >---

  int i_count = 0;

  while ((start < here) && ((i_count = count_instr(start, here)) <= 0)) start += 2;

  if (i_count == 0) return NULL; // There is something seriously wrong

  //---<  Narrow down distance (estimate was too large)  >---

  while(i_count-- > n_instr) {

    start   += Assembler::instr_len(start);

  }

  assert(n_instr >= count_instr(start, here), "just checking");

  return start;

}

// Print annotations (value of loaded constant)

void Disassembler::annotate(address here, outputStream* st) {

  // Currently, annotation doesn't work when decoding error files.

  // When decoding an instruction from a hs_err file, the given

  // instruction address 'start' points to the instruction's virtual address

  // which is not equal to the address where the instruction is located.

  // Therefore, we will either crash or decode garbage.

  if (is_decode_error_file()) {

    return;

  }

  if (MacroAssembler::is_load_const(here)) {

    long      value = MacroAssembler::get_const(here);

    const int tsize = 8;

    st->fill_to(60);

    st->print(";const %p | %ld | %23.15e", (void *)value, value, (double)value);

  }

}