/*

 * Copyright (c) 1997, 2010, 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.

 *

 */

#include "precompiled.hpp"

#include "assembler_x86.inline.hpp"

#include "memory/resourceArea.hpp"

#include "nativeInst_x86.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/handles.hpp"

#include "runtime/sharedRuntime.hpp"

#include "runtime/stubRoutines.hpp"

#include "utilities/ostream.hpp"

#ifdef COMPILER1

#include "c1/c1_Runtime1.hpp"

#endif

void NativeInstruction::wrote(int offset) {

  ICache::invalidate_word(addr_at(offset));

}

void NativeCall::verify() {

  // Make sure code pattern is actually a call imm32 instruction.

  int inst = ubyte_at(0);

  if (inst != instruction_code) {

    tty->print_cr("Addr: " INTPTR_FORMAT " Code: 0x%x", instruction_address(),

                                                        inst);

    fatal("not a call disp32");

  }

}

address NativeCall::destination() const {

  // Getting the destination of a call isn't safe because that call can

  // be getting patched while you're calling this.  There's only special

  // places where this can be called but not automatically verifiable by

  // checking which locks are held.  The solution is true atomic patching

  // on x86, nyi.

  return return_address() + displacement();

}

void NativeCall::print() {

  tty->print_cr(PTR_FORMAT ": call " PTR_FORMAT,

                instruction_address(), destination());

}

// Inserts a native call instruction at a given pc

void NativeCall::insert(address code_pos, address entry) {

  intptr_t disp = (intptr_t)entry - ((intptr_t)code_pos + 1 + 4);

#ifdef AMD64

  guarantee(disp == (intptr_t)(jint)disp, "must be 32-bit offset");

#endif // AMD64

  *code_pos = instruction_code;

  *((int32_t *)(code_pos+1)) = (int32_t) disp;

  ICache::invalidate_range(code_pos, instruction_size);

}

// MT-safe patching of a call instruction.

// First patches first word of instruction to two jmp's that jmps to them

// selfs (spinlock). Then patches the last byte, and then atomicly replaces

// the jmp's with the first 4 byte of the new instruction.

void NativeCall::replace_mt_safe(address instr_addr, address code_buffer) {

  assert(Patching_lock->is_locked() ||

         SafepointSynchronize::is_at_safepoint(), "concurrent code patching");

  assert (instr_addr != NULL, "illegal address for code patching");

  NativeCall* n_call =  nativeCall_at (instr_addr); // checking that it is a call

  if (os::is_MP()) {

    guarantee((intptr_t)instr_addr % BytesPerWord == 0, "must be aligned");

  }

  // First patch dummy jmp in place

  unsigned char patch[4];

  assert(sizeof(patch)==sizeof(jint), "sanity check");

  patch[0] = 0xEB;       // jmp rel8

  patch[1] = 0xFE;       // jmp to self

  patch[2] = 0xEB;

  patch[3] = 0xFE;

  // First patch dummy jmp in place

  *(jint*)instr_addr = *(jint *)patch;

  // Invalidate.  Opteron requires a flush after every write.

  n_call->wrote(0);

  // Patch 4th byte

  instr_addr[4] = code_buffer[4];

  n_call->wrote(4);

  // Patch bytes 0-3

  *(jint*)instr_addr = *(jint *)code_buffer;

  n_call->wrote(0);

#ifdef ASSERT

   // verify patching

   for ( int i = 0; i < instruction_size; i++) {

     address ptr = (address)((intptr_t)code_buffer + i);

     int a_byte = (*ptr) & 0xFF;

     assert(*((address)((intptr_t)instr_addr + i)) == a_byte, "mt safe patching failed");

   }

#endif

}

// Similar to replace_mt_safe, but just changes the destination.  The

// important thing is that free-running threads are able to execute this

// call instruction at all times.  If the displacement field is aligned

// we can simply rely on atomicity of 32-bit writes to make sure other threads

// will see no intermediate states.  Otherwise, the first two bytes of the

// call are guaranteed to be aligned, and can be atomically patched to a

// self-loop to guard the instruction while we change the other bytes.

// We cannot rely on locks here, since the free-running threads must run at

// full speed.

//

// Used in the runtime linkage of calls; see class CompiledIC.

// (Cf. 4506997 and 4479829, where threads witnessed garbage displacements.)

void NativeCall::set_destination_mt_safe(address dest) {

  debug_only(verify());

  // Make sure patching code is locked.  No two threads can patch at the same

  // time but one may be executing this code.

  assert(Patching_lock->is_locked() ||

         SafepointSynchronize::is_at_safepoint(), "concurrent code patching");

  // Both C1 and C2 should now be generating code which aligns the patched address

  // to be within a single cache line except that C1 does not do the alignment on

  // uniprocessor systems.

  bool is_aligned = ((uintptr_t)displacement_address() + 0) / cache_line_size ==

                    ((uintptr_t)displacement_address() + 3) / cache_line_size;

  guarantee(!os::is_MP() || is_aligned, "destination must be aligned");

  if (is_aligned) {

    // Simple case:  The destination lies within a single cache line.

    set_destination(dest);

  } else if ((uintptr_t)instruction_address() / cache_line_size ==

             ((uintptr_t)instruction_address()+1) / cache_line_size) {

    // Tricky case:  The instruction prefix lies within a single cache line.

    intptr_t disp = dest - return_address();

#ifdef AMD64

    guarantee(disp == (intptr_t)(jint)disp, "must be 32-bit offset");

#endif // AMD64

    int call_opcode = instruction_address()[0];

    // First patch dummy jump in place:

    {

      u_char patch_jump[2];

      patch_jump[0] = 0xEB;       // jmp rel8

      patch_jump[1] = 0xFE;       // jmp to self

      assert(sizeof(patch_jump)==sizeof(short), "sanity check");

      *(short*)instruction_address() = *(short*)patch_jump;

    }

    // Invalidate.  Opteron requires a flush after every write.

    wrote(0);

    // (Note: We assume any reader which has already started to read

    // the unpatched call will completely read the whole unpatched call

    // without seeing the next writes we are about to make.)

    // Next, patch the last three bytes:

    u_char patch_disp[5];

    patch_disp[0] = call_opcode;

    *(int32_t*)&patch_disp[1] = (int32_t)disp;

    assert(sizeof(patch_disp)==instruction_size, "sanity check");

    for (int i = sizeof(short); i < instruction_size; i++)

      instruction_address()[i] = patch_disp[i];

    // Invalidate.  Opteron requires a flush after every write.

    wrote(sizeof(short));

    // (Note: We assume that any reader which reads the opcode we are

    // about to repatch will also read the writes we just made.)

    // Finally, overwrite the jump:

    *(short*)instruction_address() = *(short*)patch_disp;

    // Invalidate.  Opteron requires a flush after every write.

    wrote(0);

    debug_only(verify());

    guarantee(destination() == dest, "patch succeeded");

  } else {

    // Impossible:  One or the other must be atomically writable.

    ShouldNotReachHere();

  }

}

void NativeMovConstReg::verify() {

#ifdef AMD64

  // make sure code pattern is actually a mov reg64, imm64 instruction

  if ((ubyte_at(0) != Assembler::REX_W && ubyte_at(0) != Assembler::REX_WB) ||

      (ubyte_at(1) & (0xff ^ register_mask)) != 0xB8) {

    print();

    fatal("not a REX.W[B] mov reg64, imm64");

  }

#else

  // make sure code pattern is actually a mov reg, imm32 instruction

  u_char test_byte = *(u_char*)instruction_address();

  u_char test_byte_2 = test_byte & ( 0xff ^ register_mask);

  if (test_byte_2 != instruction_code) fatal("not a mov reg, imm32");

#endif // AMD64

}

void NativeMovConstReg::print() {

  tty->print_cr(PTR_FORMAT ": mov reg, " INTPTR_FORMAT,

                instruction_address(), data());

}

//-------------------------------------------------------------------

int NativeMovRegMem::instruction_start() const {

  int off = 0;

  u_char instr_0 = ubyte_at(off);

  // See comment in Assembler::locate_operand() about VEX prefixes.

  if (instr_0 == instruction_VEX_prefix_2bytes) {

    assert((UseAVX > 0), "shouldn't have VEX prefix");

    NOT_LP64(assert((0xC0 & ubyte_at(1)) == 0xC0, "shouldn't have LDS and LES instructions"));

    return 2;

  }

  if (instr_0 == instruction_VEX_prefix_3bytes) {

    assert((UseAVX > 0), "shouldn't have VEX prefix");

    NOT_LP64(assert((0xC0 & ubyte_at(1)) == 0xC0, "shouldn't have LDS and LES instructions"));

    return 3;

  }

  // First check to see if we have a (prefixed or not) xor

  if (instr_0 >= instruction_prefix_wide_lo && // 0x40

      instr_0 <= instruction_prefix_wide_hi) { // 0x4f

    off++;

    instr_0 = ubyte_at(off);

  }

  if (instr_0 == instruction_code_xor) {

    off += 2;

    instr_0 = ubyte_at(off);

  }

  // Now look for the real instruction and the many prefix/size specifiers.

  if (instr_0 == instruction_operandsize_prefix ) {  // 0x66

    off++; // Not SSE instructions

    instr_0 = ubyte_at(off);

  }

  if ( instr_0 == instruction_code_xmm_ss_prefix || // 0xf3

       instr_0 == instruction_code_xmm_sd_prefix) { // 0xf2

    off++;

    instr_0 = ubyte_at(off);

  }

  if ( instr_0 >= instruction_prefix_wide_lo && // 0x40

       instr_0 <= instruction_prefix_wide_hi) { // 0x4f

    off++;

    instr_0 = ubyte_at(off);

  }

  if (instr_0 == instruction_extended_prefix ) {  // 0x0f

    off++;

  }

  return off;

}

address NativeMovRegMem::instruction_address() const {

  return addr_at(instruction_start());

}

address NativeMovRegMem::next_instruction_address() const {

  address ret = instruction_address() + instruction_size;

  u_char instr_0 =  *(u_char*) instruction_address();

  switch (instr_0) {

  case instruction_operandsize_prefix:

    fatal("should have skipped instruction_operandsize_prefix");

    break;

  case instruction_extended_prefix:

    fatal("should have skipped instruction_extended_prefix");

    break;

  case instruction_code_mem2reg_movslq: // 0x63

  case instruction_code_mem2reg_movzxb: // 0xB6

  case instruction_code_mem2reg_movsxb: // 0xBE

  case instruction_code_mem2reg_movzxw: // 0xB7

  case instruction_code_mem2reg_movsxw: // 0xBF

  case instruction_code_reg2mem:        // 0x89 (q/l)

  case instruction_code_mem2reg:        // 0x8B (q/l)

  case instruction_code_reg2memb:       // 0x88

  case instruction_code_mem2regb:       // 0x8a

  case instruction_code_float_s:        // 0xd9 fld_s a

  case instruction_code_float_d:        // 0xdd fld_d a

  case instruction_code_xmm_load:       // 0x10

  case instruction_code_xmm_store:      // 0x11

  case instruction_code_xmm_lpd:        // 0x12

    {

      // If there is an SIB then instruction is longer than expected

      u_char mod_rm = *(u_char*)(instruction_address() + 1);

      if ((mod_rm & 7) == 0x4) {

        ret++;

      }

    }

  case instruction_code_xor:

    fatal("should have skipped xor lead in");

    break;

  default:

    fatal("not a NativeMovRegMem");

  }

  return ret;

}

int NativeMovRegMem::offset() const{

  int off = data_offset + instruction_start();

  u_char mod_rm = *(u_char*)(instruction_address() + 1);

  // nnnn(r12|rsp) isn't coded as simple mod/rm since that is

  // the encoding to use an SIB byte. Which will have the nnnn

  // field off by one byte

  if ((mod_rm & 7) == 0x4) {

    off++;

  }

  return int_at(off);

}

void NativeMovRegMem::set_offset(int x) {

  int off = data_offset + instruction_start();

  u_char mod_rm = *(u_char*)(instruction_address() + 1);

  // nnnn(r12|rsp) isn't coded as simple mod/rm since that is

  // the encoding to use an SIB byte. Which will have the nnnn

  // field off by one byte

  if ((mod_rm & 7) == 0x4) {

    off++;

  }

  set_int_at(off, x);

}

void NativeMovRegMem::verify() {

  // make sure code pattern is actually a mov [reg+offset], reg instruction

  u_char test_byte = *(u_char*)instruction_address();

  switch (test_byte) {

    case instruction_code_reg2memb:  // 0x88 movb a, r

    case instruction_code_reg2mem:   // 0x89 movl a, r (can be movq in 64bit)

    case instruction_code_mem2regb:  // 0x8a movb r, a

    case instruction_code_mem2reg:   // 0x8b movl r, a (can be movq in 64bit)

      break;

    case instruction_code_mem2reg_movslq: // 0x63 movsql r, a

    case instruction_code_mem2reg_movzxb: // 0xb6 movzbl r, a (movzxb)

    case instruction_code_mem2reg_movzxw: // 0xb7 movzwl r, a (movzxw)

    case instruction_code_mem2reg_movsxb: // 0xbe movsbl r, a (movsxb)

    case instruction_code_mem2reg_movsxw: // 0xbf  movswl r, a (movsxw)

      break;

    case instruction_code_float_s:   // 0xd9 fld_s a

    case instruction_code_float_d:   // 0xdd fld_d a

    case instruction_code_xmm_load:  // 0x10 movsd xmm, a

    case instruction_code_xmm_store: // 0x11 movsd a, xmm

    case instruction_code_xmm_lpd:   // 0x12 movlpd xmm, a

      break;

    default:

          fatal ("not a mov [reg+offs], reg instruction");

  }

}

void NativeMovRegMem::print() {

  tty->print_cr("0x%x: mov reg, [reg + %x]", instruction_address(), offset());

}

//-------------------------------------------------------------------

void NativeLoadAddress::verify() {

  // make sure code pattern is actually a mov [reg+offset], reg instruction

  u_char test_byte = *(u_char*)instruction_address();

#ifdef _LP64

  if ( (test_byte == instruction_prefix_wide ||

        test_byte == instruction_prefix_wide_extended) ) {

    test_byte = *(u_char*)(instruction_address() + 1);

  }

#endif // _LP64

  if ( ! ((test_byte == lea_instruction_code)

          LP64_ONLY(|| (test_byte == mov64_instruction_code) ))) {

    fatal ("not a lea reg, [reg+offs] instruction");

  }

}

void NativeLoadAddress::print() {

  tty->print_cr("0x%x: lea [reg + %x], reg", instruction_address(), offset());

}

//--------------------------------------------------------------------------------

void NativeJump::verify() {

  if (*(u_char*)instruction_address() != instruction_code) {

    fatal("not a jump instruction");

  }

}

void NativeJump::insert(address code_pos, address entry) {

  intptr_t disp = (intptr_t)entry - ((intptr_t)code_pos + 1 + 4);

#ifdef AMD64

  guarantee(disp == (intptr_t)(int32_t)disp, "must be 32-bit offset");

#endif // AMD64

  *code_pos = instruction_code;

  *((int32_t*)(code_pos + 1)) = (int32_t)disp;

  ICache::invalidate_range(code_pos, instruction_size);

}

void NativeJump::check_verified_entry_alignment(address entry, address verified_entry) {

  // Patching to not_entrant can happen while activations of the method are

  // in use. The patching in that instance must happen only when certain

  // alignment restrictions are true. These guarantees check those

  // conditions.

#ifdef AMD64

  const int linesize = 64;

#else

  const int linesize = 32;

#endif // AMD64

  // Must be wordSize aligned

  guarantee(((uintptr_t) verified_entry & (wordSize -1)) == 0,

            "illegal address for code patching 2");

  // First 5 bytes must be within the same cache line - 4827828

  guarantee((uintptr_t) verified_entry / linesize ==

            ((uintptr_t) verified_entry + 4) / linesize,

            "illegal address for code patching 3");

}

// MT safe inserting of a jump over an unknown instruction sequence (used by nmethod::makeZombie)

// The problem: jmp <dest> is a 5-byte instruction. Atomical write can be only with 4 bytes.

// First patches the first word atomically to be a jump to itself.

// Then patches the last byte  and then atomically patches the first word (4-bytes),

// thus inserting the desired jump

// This code is mt-safe with the following conditions: entry point is 4 byte aligned,

// entry point is in same cache line as unverified entry point, and the instruction being

// patched is >= 5 byte (size of patch).

//

// In C2 the 5+ byte sized instruction is enforced by code in MachPrologNode::emit.

// In C1 the restriction is enforced by CodeEmitter::method_entry

//

void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {

  // complete jump instruction (to be inserted) is in code_buffer;

  unsigned char code_buffer[5];

  code_buffer[0] = instruction_code;

  intptr_t disp = (intptr_t)dest - ((intptr_t)verified_entry + 1 + 4);

#ifdef AMD64

  guarantee(disp == (intptr_t)(int32_t)disp, "must be 32-bit offset");

#endif // AMD64

  *(int32_t*)(code_buffer + 1) = (int32_t)disp;

  check_verified_entry_alignment(entry, verified_entry);

  // Can't call nativeJump_at() because it's asserts jump exists

  NativeJump* n_jump = (NativeJump*) verified_entry;

  //First patch dummy jmp in place

  unsigned char patch[4];

  assert(sizeof(patch)==sizeof(int32_t), "sanity check");

  patch[0] = 0xEB;       // jmp rel8

  patch[1] = 0xFE;       // jmp to self

  patch[2] = 0xEB;

  patch[3] = 0xFE;

  // First patch dummy jmp in place

  *(int32_t*)verified_entry = *(int32_t *)patch;

  n_jump->wrote(0);

  // Patch 5th byte (from jump instruction)

  verified_entry[4] = code_buffer[4];

  n_jump->wrote(4);

  // Patch bytes 0-3 (from jump instruction)

  *(int32_t*)verified_entry = *(int32_t *)code_buffer;

  // Invalidate.  Opteron requires a flush after every write.

  n_jump->wrote(0);

}