void PatchingStub::emit_code(LIR_Assembler* ce) {
// copy original code here
assert(NativeCall::instruction_size <= _bytes_to_copy && _bytes_to_copy <= 0xFF,
"not enough room for call");
assert((_bytes_to_copy & 0x3) == 0, "must copy a multiple of four bytes");
Label call_patch;
int being_initialized_entry = __ offset();
if (_id == load_klass_id) {
// produce a copy of the load klass instruction for use by the being initialized case
#ifdef ASSERT
address start = __ pc();
#endif
AddressLiteral addrlit(NULL, oop_Relocation::spec(_oop_index));
__ patchable_set(addrlit, _obj);
#ifdef ASSERT
for (int i = 0; i < _bytes_to_copy; i++) {
address ptr = (address)(_pc_start + i);
int a_byte = (*ptr) & 0xFF;
assert(a_byte == *start++, "should be the same code");
}
#endif
} else {
// make a copy the code which is going to be patched.
for (int i = 0; i < _bytes_to_copy; i++) {
address ptr = (address)(_pc_start + i);
int a_byte = (*ptr) & 0xFF;
__ a_byte (a_byte);
}
}
address end_of_patch = __ pc();
int bytes_to_skip = 0;
if (_id == load_klass_id) {
int offset = __ offset();
if (CommentedAssembly) {
__ block_comment(" being_initialized check");
}
// static field accesses have special semantics while the class
// initializer is being run so we emit a test which can be used to
// check that this code is being executed by the initializing
// thread.
assert(_obj != noreg, "must be a valid register");
assert(_oop_index >= 0, "must have oop index");
__ ld_ptr(_obj, instanceKlass::init_thread_offset_in_bytes() + sizeof(klassOopDesc), G3);
__ cmp(G2_thread, G3);
__ br(Assembler::notEqual, false, Assembler::pn, call_patch);
__ delayed()->nop();
// load_klass patches may execute the patched code before it's
// copied back into place so we need to jump back into the main
// code of the nmethod to continue execution.
__ br(Assembler::always, false, Assembler::pt, _patch_site_continuation);
__ delayed()->nop();
// make sure this extra code gets skipped
bytes_to_skip += __ offset() - offset;
}
// Now emit the patch record telling the runtime how to find the
// pieces of the patch. We only need 3 bytes but it has to be
// aligned as an instruction so emit 4 bytes.
int sizeof_patch_record = 4;
bytes_to_skip += sizeof_patch_record;
// emit the offsets needed to find the code to patch
int being_initialized_entry_offset = __ offset() - being_initialized_entry + sizeof_patch_record;
// Emit the patch record. We need to emit a full word, so emit an extra empty byte
__ a_byte(0);
__ a_byte(being_initialized_entry_offset);
__ a_byte(bytes_to_skip);
__ a_byte(_bytes_to_copy);
address patch_info_pc = __ pc();
assert(patch_info_pc - end_of_patch == bytes_to_skip, "incorrect patch info");
address entry = __ pc();
NativeGeneralJump::insert_unconditional((address)_pc_start, entry);
address target = NULL;
switch (_id) {
case access_field_id: target = Runtime1::entry_for(Runtime1::access_field_patching_id); break;
case load_klass_id: target = Runtime1::entry_for(Runtime1::load_klass_patching_id); break;
default: ShouldNotReachHere();
}
__ bind(call_patch);
if (CommentedAssembly) {
__ block_comment("patch entry point");
}
__ call(target, relocInfo::runtime_call_type);
__ delayed()->nop();
assert(_patch_info_offset == (patch_info_pc - __ pc()), "must not change");
ce->add_call_info_here(_info);
__ br(Assembler::always, false, Assembler::pt, _patch_site_entry);
__ delayed()->nop();
if (_id == load_klass_id) {
CodeSection* cs = __ code_section();
address pc = (address)_pc_start;
RelocIterator iter(cs, pc, pc + 1);
relocInfo::change_reloc_info_for_address(&iter, (address) pc, relocInfo::oop_type, relocInfo::none);
pc = (address)(_pc_start + NativeMovConstReg::add_offset);
RelocIterator iter2(cs, pc, pc+1);
relocInfo::change_reloc_info_for_address(&iter2, (address) pc, relocInfo::oop_type, relocInfo::none);
}
}
void PatchingStub::emit_code(LIR_Assembler* ce) {
assert(NativeCall::instruction_size <= _bytes_to_copy && _bytes_to_copy <= 0xFF, "not enough room for call");
Label call_patch;
// static field accesses have special semantics while the class
// initializer is being run so we emit a test which can be used to
// check that this code is being executed by the initializing
// thread.
address being_initialized_entry = __ pc();
if (CommentedAssembly) {
__ block_comment(" patch template");
}
if (_id == load_klass_id) {
// produce a copy of the load klass instruction for use by the being initialized case
address start = __ pc();
jobject o = NULL;
__ movoop(_obj, o);
#ifdef ASSERT
for (int i = 0; i < _bytes_to_copy; i++) {
address ptr = (address)(_pc_start + i);
int a_byte = (*ptr) & 0xFF;
assert(a_byte == *start++, "should be the same code");
}
#endif
} else {
// make a copy the code which is going to be patched.
for ( int i = 0; i < _bytes_to_copy; i++) {
address ptr = (address)(_pc_start + i);
int a_byte = (*ptr) & 0xFF;
__ a_byte (a_byte);
*ptr = 0x90; // make the site look like a nop
}
}
address end_of_patch = __ pc();
int bytes_to_skip = 0;
if (_id == load_klass_id) {
int offset = __ offset();
if (CommentedAssembly) {
__ block_comment(" being_initialized check");
}
assert(_obj != noreg, "must be a valid register");
Register tmp = rax;
Register tmp2 = rbx;
__ push(tmp);
__ push(tmp2);
__ load_heap_oop(tmp2, Address(_obj, java_lang_Class::klass_offset_in_bytes()));
__ get_thread(tmp);
__ cmpptr(tmp, Address(tmp2, instanceKlass::init_thread_offset_in_bytes() + sizeof(klassOopDesc)));
__ pop(tmp2);
__ pop(tmp);
__ jcc(Assembler::notEqual, call_patch);
// access_field patches may execute the patched code before it's
// copied back into place so we need to jump back into the main
// code of the nmethod to continue execution.
__ jmp(_patch_site_continuation);
// make sure this extra code gets skipped
bytes_to_skip += __ offset() - offset;
}
if (CommentedAssembly) {
__ block_comment("patch data encoded as movl");
}
// Now emit the patch record telling the runtime how to find the
// pieces of the patch. We only need 3 bytes but for readability of
// the disassembly we make the data look like a movl reg, imm32,
// which requires 5 bytes
int sizeof_patch_record = 5;
bytes_to_skip += sizeof_patch_record;
// emit the offsets needed to find the code to patch
int being_initialized_entry_offset = __ pc() - being_initialized_entry + sizeof_patch_record;
__ a_byte(0xB8);
__ a_byte(0);
__ a_byte(being_initialized_entry_offset);
__ a_byte(bytes_to_skip);
__ a_byte(_bytes_to_copy);
address patch_info_pc = __ pc();
assert(patch_info_pc - end_of_patch == bytes_to_skip, "incorrect patch info");
address entry = __ pc();
NativeGeneralJump::insert_unconditional((address)_pc_start, entry);
address target = NULL;
switch (_id) {
case access_field_id: target = Runtime1::entry_for(Runtime1::access_field_patching_id); break;
case load_klass_id: target = Runtime1::entry_for(Runtime1::load_klass_patching_id); break;
default: ShouldNotReachHere();
}
__ bind(call_patch);
if (CommentedAssembly) {
__ block_comment("patch entry point");
}
__ call(RuntimeAddress(target));
assert(_patch_info_offset == (patch_info_pc - __ pc()), "must not change");
ce->add_call_info_here(_info);
int jmp_off = __ offset();
__ jmp(_patch_site_entry);
// Add enough nops so deoptimization can overwrite the jmp above with a call
// and not destroy the world.
for (int j = __ offset() ; j < jmp_off + 5 ; j++ ) {
__ nop();
}
if (_id == load_klass_id) {
CodeSection* cs = __ code_section();
RelocIterator iter(cs, (address)_pc_start, (address)(_pc_start + 1));
relocInfo::change_reloc_info_for_address(&iter, (address) _pc_start, relocInfo::oop_type, relocInfo::none);
}
}
void PatchingStub::emit_code(LIR_Assembler* ce) {
// copy original code here
assert(NativeCall::instruction_size <= _bytes_to_copy && _bytes_to_copy <= 0xFF,
"not enough room for call");
assert((_bytes_to_copy & 0x3) == 0, "must copy a multiple of four bytes");
Label call_patch;
// static field accesses have special semantics while the class
// initializer is being run so we emit a test which can be used to
// check that this code is being executed by the initializing
// thread.
address being_initialized_entry = __ pc();
if (_id == access_field_id) {
assert(_obj != noreg, "must be a valid register");
__ ld_ptr(_obj, instanceKlass::init_thread_offset_in_bytes() + sizeof(klassOopDesc), G3);
__ cmp(G2_thread, G3);
__ br(Assembler::notEqual, false, Assembler::pn, call_patch);
__ delayed()->nop();
}
// make a copy the code which is going to be patched.
for (int i = 0; i < _bytes_to_copy; i++) {
address ptr = (address)(_pc_start + i);
int a_byte = (*ptr) & 0xFF;
__ a_byte (a_byte);
}
int bytes_to_skip = 4;
if (_id == access_field_id) {
// access_field patches may execute the patched code before it's
// copied back into place so we need to jump back into the main
// code of the nmethod to continue execution.
bytes_to_skip += 8;
__ br(Assembler::always, false, Assembler::pt, _patch_site_continuation);
__ delayed()->nop();
}
// emit the offsets needed to find the code to patch
int being_initialized_entry_offset = __ pc() - being_initialized_entry + 4;
// We need to emit a full word, so emit an extra empty byte
__ a_byte(0);
__ a_byte(being_initialized_entry_offset);
__ a_byte(bytes_to_skip);
__ a_byte(_bytes_to_copy);
address entry = __ pc();
NativeGeneralJump::insert_unconditional((address)_pc_start, entry);
address target = NULL;
switch (_id) {
case access_field_id: target = Runtime1::entry_for(Runtime1::init_check_patching_id); break;
case load_klass_id: target = Runtime1::entry_for(Runtime1::load_klass_patching_id); break;
default: ShouldNotReachHere();
}
__ bind(call_patch);
__ call(target, relocInfo::runtime_call_type);
__ delayed()->nop();
ce->add_call_info_here(_info);
__ br(Assembler::always, false, Assembler::pt, _patch_site_entry);
__ delayed()->nop();
if (_id == load_klass_id) {
CodeBuffer* cb = __ code();
address pc = (address)_pc_start;
RelocIterator iter(cb, pc, pc + 1);
relocInfo::change_reloc_info_for_address(&iter, (address) pc, relocInfo::oop_type, relocInfo::none);
pc = (address)(_pc_start + NativeMovConstReg::add_offset);
RelocIterator iter2(cb, pc, pc+1);
relocInfo::change_reloc_info_for_address(&iter2, (address) pc, relocInfo::oop_type, relocInfo::none);
}
}
