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 /*

  * 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

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  */

 #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);

   // 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);

 }

 void NativePopReg::insert(address code_pos, Register reg) {

   assert(reg->encoding() < 8, "no space for REX");

   assert(NativePopReg::instruction_size == sizeof(char), "right address unit for update");

   *code_pos = (u_char)(instruction_code | reg->encoding());

   ICache::invalidate_range(code_pos, instruction_size);

 }

 void NativeIllegalInstruction::insert(address code_pos) {

   assert(NativeIllegalInstruction::instruction_size == sizeof(short), "right address unit for update");

   *(short *)code_pos = instruction_code;

   ICache::invalidate_range(code_pos, instruction_size);

 }

 void NativeGeneralJump::verify() {

   assert(((NativeInstruction *)this)->is_jump() ||

          ((NativeInstruction *)this)->is_cond_jump(), "not a general jump instruction");

 }

 void NativeGeneralJump::insert_unconditional(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 = unconditional_long_jump;

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

   ICache::invalidate_range(code_pos, instruction_size);

 }

 // MT-safe patching of a long jump 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 NativeGeneralJump::replace_mt_safe(address instr_addr, address code_buffer) {

    assert (instr_addr != NULL, "illegal address for code patching (4)");

    NativeGeneralJump* n_jump =  nativeGeneralJump_at (instr_addr); // checking that it is a jump

    // Temporary code

    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*)instr_addr = *(int32_t *)patch;

     n_jump->wrote(0);

    // Patch 4th byte

    instr_addr[4] = code_buffer[4];

     n_jump->wrote(4);

    // Patch bytes 0-3

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

     n_jump->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

 }

 address NativeGeneralJump::jump_destination() const {

   int op_code = ubyte_at(0);

   bool is_rel32off = (op_code == 0xE9 || op_code == 0x0F);

   int  offset  = (op_code == 0x0F)  ? 2 : 1;

   int  length  = offset + ((is_rel32off) ? 4 : 1);

   if (is_rel32off)

     return addr_at(0) + length + int_at(offset);

   else

     return addr_at(0) + length + sbyte_at(offset);

 }

 bool NativeInstruction::is_dtrace_trap() {

   return (*(int32_t*)this & 0xff) == 0xcc;

 }