1 /* 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_CODE_RELOCINFO_HPP 26 #define SHARE_VM_CODE_RELOCINFO_HPP 27 28 #include "memory/allocation.hpp" 29 #include "utilities/top.hpp" 30 31 // Types in this file: 32 // relocInfo 33 // One element of an array of halfwords encoding compressed relocations. 34 // Also, the source of relocation types (relocInfo::oop_type, ...). 35 // Relocation 36 // A flyweight object representing a single relocation. 37 // It is fully unpacked from the compressed relocation array. 38 // oop_Relocation, ... (subclasses of Relocation) 39 // The location of some type-specific operations (oop_addr, ...). 40 // Also, the source of relocation specs (oop_Relocation::spec, ...). 41 // RelocationHolder 42 // A ValueObj type which acts as a union holding a Relocation object. 43 // Represents a relocation spec passed into a CodeBuffer during assembly. 44 // RelocIterator 45 // A StackObj which iterates over the relocations associated with 46 // a range of code addresses. Can be used to operate a copy of code. 47 // PatchingRelocIterator 48 // Specialized subtype of RelocIterator which removes breakpoints 49 // temporarily during iteration, then restores them. 50 // BoundRelocation 51 // An _internal_ type shared by packers and unpackers of relocations. 52 // It pastes together a RelocationHolder with some pointers into 53 // code and relocInfo streams. 54 55 56 // Notes on relocType: 57 // 58 // These hold enough information to read or write a value embedded in 59 // the instructions of an CodeBlob. They're used to update: 60 // 61 // 1) embedded oops (isOop() == true) 62 // 2) inline caches (isIC() == true) 63 // 3) runtime calls (isRuntimeCall() == true) 64 // 4) internal word ref (isInternalWord() == true) 65 // 5) external word ref (isExternalWord() == true) 66 // 67 // when objects move (GC) or if code moves (compacting the code heap). 68 // They are also used to patch the code (if a call site must change) 69 // 70 // A relocInfo is represented in 16 bits: 71 // 4 bits indicating the relocation type 72 // 12 bits indicating the offset from the previous relocInfo address 73 // 74 // The offsets accumulate along the relocInfo stream to encode the 75 // address within the CodeBlob, which is named RelocIterator::addr(). 76 // The address of a particular relocInfo always points to the first 77 // byte of the relevant instruction (and not to any of its subfields 78 // or embedded immediate constants). 79 // 80 // The offset value is scaled appropriately for the target machine. 81 // (See relocInfo_<arch>.hpp for the offset scaling.) 82 // 83 // On some machines, there may also be a "format" field which may provide 84 // additional information about the format of the instruction stream 85 // at the corresponding code address. The format value is usually zero. 86 // Any machine (such as Intel) whose instructions can sometimes contain 87 // more than one relocatable constant needs format codes to distinguish 88 // which operand goes with a given relocation. 89 // 90 // If the target machine needs N format bits, the offset has 12-N bits, 91 // the format is encoded between the offset and the type, and the 92 // relocInfo_<arch>.hpp file has manifest constants for the format codes. 93 // 94 // If the type is "data_prefix_tag" then the offset bits are further encoded, 95 // and in fact represent not a code-stream offset but some inline data. 96 // The data takes the form of a counted sequence of halfwords, which 97 // precedes the actual relocation record. (Clients never see it directly.) 98 // The interpetation of this extra data depends on the relocation type. 99 // 100 // On machines that have 32-bit immediate fields, there is usually 101 // little need for relocation "prefix" data, because the instruction stream 102 // is a perfectly reasonable place to store the value. On machines in 103 // which 32-bit values must be "split" across instructions, the relocation 104 // data is the "true" specification of the value, which is then applied 105 // to some field of the instruction (22 or 13 bits, on SPARC). 106 // 107 // Whenever the location of the CodeBlob changes, any PC-relative 108 // relocations, and any internal_word_type relocations, must be reapplied. 109 // After the GC runs, oop_type relocations must be reapplied. 110 // 111 // 112 // Here are meanings of the types: 113 // 114 // relocInfo::none -- a filler record 115 // Value: none 116 // Instruction: The corresponding code address is ignored 117 // Data: Any data prefix and format code are ignored 118 // (This means that any relocInfo can be disabled by setting 119 // its type to none. See relocInfo::remove.) 120 // 121 // relocInfo::oop_type -- a reference to an oop 122 // Value: an oop, or else the address (handle) of an oop 123 // Instruction types: memory (load), set (load address) 124 // Data: [] an oop stored in 4 bytes of instruction 125 // [n] n is the index of an oop in the CodeBlob's oop pool 126 // [[N]n l] and l is a byte offset to be applied to the oop 127 // [Nn Ll] both index and offset may be 32 bits if necessary 128 // Here is a special hack, used only by the old compiler: 129 // [[N]n 00] the value is the __address__ of the nth oop in the pool 130 // (Note that the offset allows optimal references to class variables.) 131 // 132 // relocInfo::internal_word_type -- an address within the same CodeBlob 133 // relocInfo::section_word_type -- same, but can refer to another section 134 // Value: an address in the CodeBlob's code or constants section 135 // Instruction types: memory (load), set (load address) 136 // Data: [] stored in 4 bytes of instruction 137 // [[L]l] a relative offset (see [About Offsets] below) 138 // In the case of section_word_type, the offset is relative to a section 139 // base address, and the section number (e.g., SECT_INSTS) is encoded 140 // into the low two bits of the offset L. 141 // 142 // relocInfo::external_word_type -- a fixed address in the runtime system 143 // Value: an address 144 // Instruction types: memory (load), set (load address) 145 // Data: [] stored in 4 bytes of instruction 146 // [n] the index of a "well-known" stub (usual case on RISC) 147 // [Ll] a 32-bit address 148 // 149 // relocInfo::runtime_call_type -- a fixed subroutine in the runtime system 150 // Value: an address 151 // Instruction types: PC-relative call (or a PC-relative branch) 152 // Data: [] stored in 4 bytes of instruction 153 // 154 // relocInfo::static_call_type -- a static call 155 // Value: an CodeBlob, a stub, or a fixup routine 156 // Instruction types: a call 157 // Data: [] 158 // The identity of the callee is extracted from debugging information. 159 // //%note reloc_3 160 // 161 // relocInfo::virtual_call_type -- a virtual call site (which includes an inline 162 // cache) 163 // Value: an CodeBlob, a stub, the interpreter, or a fixup routine 164 // Instruction types: a call, plus some associated set-oop instructions 165 // Data: [] the associated set-oops are adjacent to the call 166 // [n] n is a relative offset to the first set-oop 167 // [[N]n l] and l is a limit within which the set-oops occur 168 // [Nn Ll] both n and l may be 32 bits if necessary 169 // The identity of the callee is extracted from debugging information. 170 // 171 // relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound 172 // 173 // Same info as a static_call_type. We use a special type, so the handling of 174 // virtuals and statics are separated. 175 // 176 // 177 // The offset n points to the first set-oop. (See [About Offsets] below.) 178 // In turn, the set-oop instruction specifies or contains an oop cell devoted 179 // exclusively to the IC call, which can be patched along with the call. 180 // 181 // The locations of any other set-oops are found by searching the relocation 182 // information starting at the first set-oop, and continuing until all 183 // relocations up through l have been inspected. The value l is another 184 // relative offset. (Both n and l are relative to the call's first byte.) 185 // 186 // The limit l of the search is exclusive. However, if it points within 187 // the call (e.g., offset zero), it is adjusted to point after the call and 188 // any associated machine-specific delay slot. 189 // 190 // Since the offsets could be as wide as 32-bits, these conventions 191 // put no restrictions whatever upon code reorganization. 192 // 193 // The compiler is responsible for ensuring that transition from a clean 194 // state to a monomorphic compiled state is MP-safe. This implies that 195 // the system must respond well to intermediate states where a random 196 // subset of the set-oops has been correctly from the clean state 197 // upon entry to the VEP of the compiled method. In the case of a 198 // machine (Intel) with a single set-oop instruction, the 32-bit 199 // immediate field must not straddle a unit of memory coherence. 200 // //%note reloc_3 201 // 202 // relocInfo::breakpoint_type -- a conditional breakpoint in the code 203 // Value: none 204 // Instruction types: any whatsoever 205 // Data: [b [T]t i...] 206 // The b is a bit-packed word representing the breakpoint's attributes. 207 // The t is a target address which the breakpoint calls (when it is enabled). 208 // The i... is a place to store one or two instruction words overwritten 209 // by a trap, so that the breakpoint may be subsequently removed. 210 // 211 // relocInfo::static_stub_type -- an extra stub for each static_call_type 212 // Value: none 213 // Instruction types: a virtual call: { set_oop; jump; } 214 // Data: [[N]n] the offset of the associated static_call reloc 215 // This stub becomes the target of a static call which must be upgraded 216 // to a virtual call (because the callee is interpreted). 217 // See [About Offsets] below. 218 // //%note reloc_2 219 // 220 // For example: 221 // 222 // INSTRUCTIONS RELOC: TYPE PREFIX DATA 223 // ------------ ---- ----------- 224 // sethi %hi(myObject), R oop_type [n(myObject)] 225 // ld [R+%lo(myObject)+fldOffset], R2 oop_type [n(myObject) fldOffset] 226 // add R2, 1, R2 227 // st R2, [R+%lo(myObject)+fldOffset] oop_type [n(myObject) fldOffset] 228 //%note reloc_1 229 // 230 // This uses 4 instruction words, 8 relocation halfwords, 231 // and an entry (which is sharable) in the CodeBlob's oop pool, 232 // for a total of 36 bytes. 233 // 234 // Note that the compiler is responsible for ensuring the "fldOffset" when 235 // added to "%lo(myObject)" does not overflow the immediate fields of the 236 // memory instructions. 237 // 238 // 239 // [About Offsets] Relative offsets are supplied to this module as 240 // positive byte offsets, but they may be internally stored scaled 241 // and/or negated, depending on what is most compact for the target 242 // system. Since the object pointed to by the offset typically 243 // precedes the relocation address, it is profitable to store 244 // these negative offsets as positive numbers, but this decision 245 // is internal to the relocation information abstractions. 246 // 247 248 class Relocation; 249 class CodeBuffer; 250 class CodeSection; 251 class RelocIterator; 252 253 class relocInfo VALUE_OBJ_CLASS_SPEC { 254 friend class RelocIterator; 255 public: 256 enum relocType { 257 none = 0, // Used when no relocation should be generated 258 oop_type = 1, // embedded oop 259 virtual_call_type = 2, // a standard inline cache call for a virtual send 260 opt_virtual_call_type = 3, // a virtual call that has been statically bound (i.e., no IC cache) 261 static_call_type = 4, // a static send 262 static_stub_type = 5, // stub-entry for static send (takes care of interpreter case) 263 runtime_call_type = 6, // call to fixed external routine 264 external_word_type = 7, // reference to fixed external address 265 internal_word_type = 8, // reference within the current code blob 266 section_word_type = 9, // internal, but a cross-section reference 267 poll_type = 10, // polling instruction for safepoints 268 poll_return_type = 11, // polling instruction for safepoints at return 269 breakpoint_type = 12, // an initialization barrier or safepoint 270 yet_unused_type = 13, // Still unused 271 yet_unused_type_2 = 14, // Still unused 272 data_prefix_tag = 15, // tag for a prefix (carries data arguments) 273 type_mask = 15 // A mask which selects only the above values 274 }; 275 276 protected: 277 unsigned short _value; 278 279 enum RawBitsToken { RAW_BITS }; 280 relocInfo(relocType type, RawBitsToken ignore, int bits) 281 : _value((type << nontype_width) + bits) { } 282 283 relocInfo(relocType type, RawBitsToken ignore, int off, int f) 284 : _value((type << nontype_width) + (off / (unsigned)offset_unit) + (f << offset_width)) { } 285 286 public: 287 // constructor 288 relocInfo(relocType type, int offset, int format = 0) 289 #ifndef ASSERT 290 { 291 (*this) = relocInfo(type, RAW_BITS, offset, format); 292 } 293 #else 294 // Put a bunch of assertions out-of-line. 295 ; 296 #endif 297 298 #define APPLY_TO_RELOCATIONS(visitor) \ 299 visitor(oop) \ 300 visitor(virtual_call) \ 301 visitor(opt_virtual_call) \ 302 visitor(static_call) \ 303 visitor(static_stub) \ 304 visitor(runtime_call) \ 305 visitor(external_word) \ 306 visitor(internal_word) \ 307 visitor(poll) \ 308 visitor(poll_return) \ 309 visitor(breakpoint) \ 310 visitor(section_word) \ 311 312 313 public: 314 enum { 315 value_width = sizeof(unsigned short) * BitsPerByte, 316 type_width = 4, // == log2(type_mask+1) 317 nontype_width = value_width - type_width, 318 datalen_width = nontype_width-1, 319 datalen_tag = 1 << datalen_width, // or-ed into _value 320 datalen_limit = 1 << datalen_width, 321 datalen_mask = (1 << datalen_width)-1 322 }; 323 324 // accessors 325 public: 326 relocType type() const { return (relocType)((unsigned)_value >> nontype_width); } 327 int format() const { return format_mask==0? 0: format_mask & 328 ((unsigned)_value >> offset_width); } 329 int addr_offset() const { assert(!is_prefix(), "must have offset"); 330 return (_value & offset_mask)*offset_unit; } 331 332 protected: 333 const short* data() const { assert(is_datalen(), "must have data"); 334 return (const short*)(this + 1); } 335 int datalen() const { assert(is_datalen(), "must have data"); 336 return (_value & datalen_mask); } 337 int immediate() const { assert(is_immediate(), "must have immed"); 338 return (_value & datalen_mask); } 339 public: 340 static int addr_unit() { return offset_unit; } 341 static int offset_limit() { return (1 << offset_width) * offset_unit; } 342 343 void set_type(relocType type); 344 void set_format(int format); 345 346 void remove() { set_type(none); } 347 348 protected: 349 bool is_none() const { return type() == none; } 350 bool is_prefix() const { return type() == data_prefix_tag; } 351 bool is_datalen() const { assert(is_prefix(), "must be prefix"); 352 return (_value & datalen_tag) != 0; } 353 bool is_immediate() const { assert(is_prefix(), "must be prefix"); 354 return (_value & datalen_tag) == 0; } 355 356 public: 357 // Occasionally records of type relocInfo::none will appear in the stream. 358 // We do not bother to filter these out, but clients should ignore them. 359 // These records serve as "filler" in three ways: 360 // - to skip large spans of unrelocated code (this is rare) 361 // - to pad out the relocInfo array to the required oop alignment 362 // - to disable old relocation information which is no longer applicable 363 364 inline friend relocInfo filler_relocInfo(); 365 366 // Every non-prefix relocation may be preceded by at most one prefix, 367 // which supplies 1 or more halfwords of associated data. Conventionally, 368 // an int is represented by 0, 1, or 2 halfwords, depending on how 369 // many bits are required to represent the value. (In addition, 370 // if the sole halfword is a 10-bit unsigned number, it is made 371 // "immediate" in the prefix header word itself. This optimization 372 // is invisible outside this module.) 373 374 inline friend relocInfo prefix_relocInfo(int datalen = 0); 375 376 protected: 377 // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value 378 static relocInfo immediate_relocInfo(int data0) { 379 assert(fits_into_immediate(data0), "data0 in limits"); 380 return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0); 381 } 382 static bool fits_into_immediate(int data0) { 383 return (data0 >= 0 && data0 < datalen_limit); 384 } 385 386 public: 387 // Support routines for compilers. 388 389 // This routine takes an infant relocInfo (unprefixed) and 390 // edits in its prefix, if any. It also updates dest.locs_end. 391 void initialize(CodeSection* dest, Relocation* reloc); 392 393 // This routine updates a prefix and returns the limit pointer. 394 // It tries to compress the prefix from 32 to 16 bits, and if 395 // successful returns a reduced "prefix_limit" pointer. 396 relocInfo* finish_prefix(short* prefix_limit); 397 398 // bit-packers for the data array: 399 400 // As it happens, the bytes within the shorts are ordered natively, 401 // but the shorts within the word are ordered big-endian. 402 // This is an arbitrary choice, made this way mainly to ease debugging. 403 static int data0_from_int(jint x) { return x >> value_width; } 404 static int data1_from_int(jint x) { return (short)x; } 405 static jint jint_from_data(short* data) { 406 return (data[0] << value_width) + (unsigned short)data[1]; 407 } 408 409 static jint short_data_at(int n, short* data, int datalen) { 410 return datalen > n ? data[n] : 0; 411 } 412 413 static jint jint_data_at(int n, short* data, int datalen) { 414 return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen); 415 } 416 417 // Update methods for relocation information 418 // (since code is dynamically patched, we also need to dynamically update the relocation info) 419 // Both methods takes old_type, so it is able to performe sanity checks on the information removed. 420 static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type); 421 static void remove_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type); 422 423 // Machine dependent stuff 424 #ifdef TARGET_ARCH_x86 425 # include "relocInfo_x86.hpp" 426 #endif 427 #ifdef TARGET_ARCH_sparc 428 # include "relocInfo_sparc.hpp" 429 #endif 430 #ifdef TARGET_ARCH_zero 431 # include "relocInfo_zero.hpp" 432 #endif 433 434 435 protected: 436 // Derived constant, based on format_width which is PD: 437 enum { 438 offset_width = nontype_width - format_width, 439 offset_mask = (1<<offset_width) - 1, 440 format_mask = (1<<format_width) - 1 441 }; 442 public: 443 enum { 444 // Conservatively large estimate of maximum length (in shorts) 445 // of any relocation record (probably breakpoints are largest). 446 // Extended format is length prefix, data words, and tag/offset suffix. 447 length_limit = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1, 448 have_format = format_width > 0 449 }; 450 }; 451 452 #define FORWARD_DECLARE_EACH_CLASS(name) \ 453 class name##_Relocation; 454 APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS) 455 #undef FORWARD_DECLARE_EACH_CLASS 456 457 458 459 inline relocInfo filler_relocInfo() { 460 return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit); 461 } 462 463 inline relocInfo prefix_relocInfo(int datalen) { 464 assert(relocInfo::fits_into_immediate(datalen), "datalen in limits"); 465 return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen); 466 } 467 468 469 // Holder for flyweight relocation objects. 470 // Although the flyweight subclasses are of varying sizes, 471 // the holder is "one size fits all". 472 class RelocationHolder VALUE_OBJ_CLASS_SPEC { 473 friend class Relocation; 474 friend class CodeSection; 475 476 private: 477 // this preallocated memory must accommodate all subclasses of Relocation 478 // (this number is assertion-checked in Relocation::operator new) 479 enum { _relocbuf_size = 5 }; 480 void* _relocbuf[ _relocbuf_size ]; 481 482 public: 483 Relocation* reloc() const { return (Relocation*) &_relocbuf[0]; } 484 inline relocInfo::relocType type() const; 485 486 // Add a constant offset to a relocation. Helper for class Address. 487 RelocationHolder plus(int offset) const; 488 489 inline RelocationHolder(); // initializes type to none 490 491 inline RelocationHolder(Relocation* r); // make a copy 492 493 static const RelocationHolder none; 494 }; 495 496 // A RelocIterator iterates through the relocation information of a CodeBlob. 497 // It is a variable BoundRelocation which is able to take on successive 498 // values as it is advanced through a code stream. 499 // Usage: 500 // RelocIterator iter(nm); 501 // while (iter.next()) { 502 // iter.reloc()->some_operation(); 503 // } 504 // or: 505 // RelocIterator iter(nm); 506 // while (iter.next()) { 507 // switch (iter.type()) { 508 // case relocInfo::oop_type : 509 // case relocInfo::ic_type : 510 // case relocInfo::prim_type : 511 // case relocInfo::uncommon_type : 512 // case relocInfo::runtime_call_type : 513 // case relocInfo::internal_word_type: 514 // case relocInfo::external_word_type: 515 // ... 516 // } 517 // } 518 519 class RelocIterator : public StackObj { 520 enum { SECT_LIMIT = 3 }; // must be equal to CodeBuffer::SECT_LIMIT, checked in ctor 521 friend class Relocation; 522 friend class relocInfo; // for change_reloc_info_for_address only 523 typedef relocInfo::relocType relocType; 524 525 private: 526 address _limit; // stop producing relocations after this _addr 527 relocInfo* _current; // the current relocation information 528 relocInfo* _end; // end marker; we're done iterating when _current == _end 529 nmethod* _code; // compiled method containing _addr 530 address _addr; // instruction to which the relocation applies 531 short _databuf; // spare buffer for compressed data 532 short* _data; // pointer to the relocation's data 533 short _datalen; // number of halfwords in _data 534 char _format; // position within the instruction 535 536 // Base addresses needed to compute targets of section_word_type relocs. 537 address _section_start[SECT_LIMIT]; 538 address _section_end [SECT_LIMIT]; 539 540 void set_has_current(bool b) { 541 _datalen = !b ? -1 : 0; 542 debug_only(_data = NULL); 543 } 544 void set_current(relocInfo& ri) { 545 _current = &ri; 546 set_has_current(true); 547 } 548 549 RelocationHolder _rh; // where the current relocation is allocated 550 551 relocInfo* current() const { assert(has_current(), "must have current"); 552 return _current; } 553 554 void set_limits(address begin, address limit); 555 556 void advance_over_prefix(); // helper method 557 558 void initialize_misc(); 559 560 void initialize(nmethod* nm, address begin, address limit); 561 562 friend class PatchingRelocIterator; 563 // make an uninitialized one, for PatchingRelocIterator: 564 RelocIterator() { initialize_misc(); } 565 566 public: 567 // constructor 568 RelocIterator(nmethod* nm, address begin = NULL, address limit = NULL); 569 RelocIterator(CodeSection* cb, address begin = NULL, address limit = NULL); 570 571 // get next reloc info, return !eos 572 bool next() { 573 _current++; 574 assert(_current <= _end, "must not overrun relocInfo"); 575 if (_current == _end) { 576 set_has_current(false); 577 return false; 578 } 579 set_has_current(true); 580 581 if (_current->is_prefix()) { 582 advance_over_prefix(); 583 assert(!current()->is_prefix(), "only one prefix at a time"); 584 } 585 586 _addr += _current->addr_offset(); 587 588 if (_limit != NULL && _addr >= _limit) { 589 set_has_current(false); 590 return false; 591 } 592 593 if (relocInfo::have_format) _format = current()->format(); 594 return true; 595 } 596 597 // accessors 598 address limit() const { return _limit; } 599 void set_limit(address x); 600 relocType type() const { return current()->type(); } 601 int format() const { return (relocInfo::have_format) ? current()->format() : 0; } 602 address addr() const { return _addr; } 603 nmethod* code() const { return _code; } 604 short* data() const { return _data; } 605 int datalen() const { return _datalen; } 606 bool has_current() const { return _datalen >= 0; } 607 608 void set_addr(address addr) { _addr = addr; } 609 bool addr_in_const() const; 610 611 address section_start(int n) const { 612 assert(_section_start[n], "must be initialized"); 613 return _section_start[n]; 614 } 615 address section_end(int n) const { 616 assert(_section_end[n], "must be initialized"); 617 return _section_end[n]; 618 } 619 620 // The address points to the affected displacement part of the instruction. 621 // For RISC, this is just the whole instruction. 622 // For Intel, this is an unaligned 32-bit word. 623 624 // type-specific relocation accessors: oop_Relocation* oop_reloc(), etc. 625 #define EACH_TYPE(name) \ 626 inline name##_Relocation* name##_reloc(); 627 APPLY_TO_RELOCATIONS(EACH_TYPE) 628 #undef EACH_TYPE 629 // generic relocation accessor; switches on type to call the above 630 Relocation* reloc(); 631 632 // CodeBlob's have relocation indexes for faster random access: 633 static int locs_and_index_size(int code_size, int locs_size); 634 // Store an index into [dest_start+dest_count..dest_end). 635 // At dest_start[0..dest_count] is the actual relocation information. 636 // Everything else up to dest_end is free space for the index. 637 static void create_index(relocInfo* dest_begin, int dest_count, relocInfo* dest_end); 638 639 #ifndef PRODUCT 640 public: 641 void print(); 642 void print_current(); 643 #endif 644 }; 645 646 647 // A Relocation is a flyweight object allocated within a RelocationHolder. 648 // It represents the relocation data of relocation record. 649 // So, the RelocIterator unpacks relocInfos into Relocations. 650 651 class Relocation VALUE_OBJ_CLASS_SPEC { 652 friend class RelocationHolder; 653 friend class RelocIterator; 654 655 private: 656 static void guarantee_size(); 657 658 // When a relocation has been created by a RelocIterator, 659 // this field is non-null. It allows the relocation to know 660 // its context, such as the address to which it applies. 661 RelocIterator* _binding; 662 663 protected: 664 RelocIterator* binding() const { 665 assert(_binding != NULL, "must be bound"); 666 return _binding; 667 } 668 void set_binding(RelocIterator* b) { 669 assert(_binding == NULL, "must be unbound"); 670 _binding = b; 671 assert(_binding != NULL, "must now be bound"); 672 } 673 674 Relocation() { 675 _binding = NULL; 676 } 677 678 static RelocationHolder newHolder() { 679 return RelocationHolder(); 680 } 681 682 public: 683 void* operator new(size_t size, const RelocationHolder& holder) { 684 if (size > sizeof(holder._relocbuf)) guarantee_size(); 685 assert((void* const *)holder.reloc() == &holder._relocbuf[0], "ptrs must agree"); 686 return holder.reloc(); 687 } 688 689 // make a generic relocation for a given type (if possible) 690 static RelocationHolder spec_simple(relocInfo::relocType rtype); 691 692 // here is the type-specific hook which writes relocation data: 693 virtual void pack_data_to(CodeSection* dest) { } 694 695 // here is the type-specific hook which reads (unpacks) relocation data: 696 virtual void unpack_data() { 697 assert(datalen()==0 || type()==relocInfo::none, "no data here"); 698 } 699 700 protected: 701 // Helper functions for pack_data_to() and unpack_data(). 702 703 // Most of the compression logic is confined here. 704 // (The "immediate data" mechanism of relocInfo works independently 705 // of this stuff, and acts to further compress most 1-word data prefixes.) 706 707 // A variable-width int is encoded as a short if it will fit in 16 bits. 708 // The decoder looks at datalen to decide whether to unpack short or jint. 709 // Most relocation records are quite simple, containing at most two ints. 710 711 static bool is_short(jint x) { return x == (short)x; } 712 static short* add_short(short* p, int x) { *p++ = x; return p; } 713 static short* add_jint (short* p, jint x) { 714 *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x); 715 return p; 716 } 717 static short* add_var_int(short* p, jint x) { // add a variable-width int 718 if (is_short(x)) p = add_short(p, x); 719 else p = add_jint (p, x); 720 return p; 721 } 722 723 static short* pack_1_int_to(short* p, jint x0) { 724 // Format is one of: [] [x] [Xx] 725 if (x0 != 0) p = add_var_int(p, x0); 726 return p; 727 } 728 int unpack_1_int() { 729 assert(datalen() <= 2, "too much data"); 730 return relocInfo::jint_data_at(0, data(), datalen()); 731 } 732 733 // With two ints, the short form is used only if both ints are short. 734 short* pack_2_ints_to(short* p, jint x0, jint x1) { 735 // Format is one of: [] [x y?] [Xx Y?y] 736 if (x0 == 0 && x1 == 0) { 737 // no halfwords needed to store zeroes 738 } else if (is_short(x0) && is_short(x1)) { 739 // 1-2 halfwords needed to store shorts 740 p = add_short(p, x0); if (x1!=0) p = add_short(p, x1); 741 } else { 742 // 3-4 halfwords needed to store jints 743 p = add_jint(p, x0); p = add_var_int(p, x1); 744 } 745 return p; 746 } 747 void unpack_2_ints(jint& x0, jint& x1) { 748 int dlen = datalen(); 749 short* dp = data(); 750 if (dlen <= 2) { 751 x0 = relocInfo::short_data_at(0, dp, dlen); 752 x1 = relocInfo::short_data_at(1, dp, dlen); 753 } else { 754 assert(dlen <= 4, "too much data"); 755 x0 = relocInfo::jint_data_at(0, dp, dlen); 756 x1 = relocInfo::jint_data_at(2, dp, dlen); 757 } 758 } 759 760 protected: 761 // platform-dependent utilities for decoding and patching instructions 762 void pd_set_data_value (address x, intptr_t off); // a set or mem-ref 763 address pd_call_destination (address orig_addr = NULL); 764 void pd_set_call_destination (address x); 765 void pd_swap_in_breakpoint (address x, short* instrs, int instrlen); 766 void pd_swap_out_breakpoint (address x, short* instrs, int instrlen); 767 static int pd_breakpoint_size (); 768 769 // this extracts the address of an address in the code stream instead of the reloc data 770 address* pd_address_in_code (); 771 772 // this extracts an address from the code stream instead of the reloc data 773 address pd_get_address_from_code (); 774 775 // these convert from byte offsets, to scaled offsets, to addresses 776 static jint scaled_offset(address x, address base) { 777 int byte_offset = x - base; 778 int offset = -byte_offset / relocInfo::addr_unit(); 779 assert(address_from_scaled_offset(offset, base) == x, "just checkin'"); 780 return offset; 781 } 782 static jint scaled_offset_null_special(address x, address base) { 783 // Some relocations treat offset=0 as meaning NULL. 784 // Handle this extra convention carefully. 785 if (x == NULL) return 0; 786 assert(x != base, "offset must not be zero"); 787 return scaled_offset(x, base); 788 } 789 static address address_from_scaled_offset(jint offset, address base) { 790 int byte_offset = -( offset * relocInfo::addr_unit() ); 791 return base + byte_offset; 792 } 793 794 // these convert between indexes and addresses in the runtime system 795 static int32_t runtime_address_to_index(address runtime_address); 796 static address index_to_runtime_address(int32_t index); 797 798 // helpers for mapping between old and new addresses after a move or resize 799 address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest); 800 address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest); 801 void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false); 802 803 public: 804 // accessors which only make sense for a bound Relocation 805 address addr() const { return binding()->addr(); } 806 nmethod* code() const { return binding()->code(); } 807 bool addr_in_const() const { return binding()->addr_in_const(); } 808 protected: 809 short* data() const { return binding()->data(); } 810 int datalen() const { return binding()->datalen(); } 811 int format() const { return binding()->format(); } 812 813 public: 814 virtual relocInfo::relocType type() { return relocInfo::none; } 815 816 // is it a call instruction? 817 virtual bool is_call() { return false; } 818 819 // is it a data movement instruction? 820 virtual bool is_data() { return false; } 821 822 // some relocations can compute their own values 823 virtual address value(); 824 825 // all relocations are able to reassert their values 826 virtual void set_value(address x); 827 828 virtual void clear_inline_cache() { } 829 830 // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and 831 // ic_call_type is not always posisition dependent (depending on the state of the cache)). However, this is 832 // probably a reasonable assumption, since empty caches simplifies code reloacation. 833 virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { } 834 835 void print(); 836 }; 837 838 839 // certain inlines must be deferred until class Relocation is defined: 840 841 inline RelocationHolder::RelocationHolder() { 842 // initialize the vtbl, just to keep things type-safe 843 new(*this) Relocation(); 844 } 845 846 847 inline RelocationHolder::RelocationHolder(Relocation* r) { 848 // wordwise copy from r (ok if it copies garbage after r) 849 for (int i = 0; i < _relocbuf_size; i++) { 850 _relocbuf[i] = ((void**)r)[i]; 851 } 852 } 853 854 855 relocInfo::relocType RelocationHolder::type() const { 856 return reloc()->type(); 857 } 858 859 // A DataRelocation always points at a memory or load-constant instruction.. 860 // It is absolute on most machines, and the constant is split on RISCs. 861 // The specific subtypes are oop, external_word, and internal_word. 862 // By convention, the "value" does not include a separately reckoned "offset". 863 class DataRelocation : public Relocation { 864 public: 865 bool is_data() { return true; } 866 867 // both target and offset must be computed somehow from relocation data 868 virtual int offset() { return 0; } 869 address value() = 0; 870 void set_value(address x) { set_value(x, offset()); } 871 void set_value(address x, intptr_t o) { 872 if (addr_in_const()) 873 *(address*)addr() = x; 874 else 875 pd_set_data_value(x, o); 876 } 877 878 // The "o" (displacement) argument is relevant only to split relocations 879 // on RISC machines. In some CPUs (SPARC), the set-hi and set-lo ins'ns 880 // can encode more than 32 bits between them. This allows compilers to 881 // share set-hi instructions between addresses that differ by a small 882 // offset (e.g., different static variables in the same class). 883 // On such machines, the "x" argument to set_value on all set-lo 884 // instructions must be the same as the "x" argument for the 885 // corresponding set-hi instructions. The "o" arguments for the 886 // set-hi instructions are ignored, and must not affect the high-half 887 // immediate constant. The "o" arguments for the set-lo instructions are 888 // added into the low-half immediate constant, and must not overflow it. 889 }; 890 891 // A CallRelocation always points at a call instruction. 892 // It is PC-relative on most machines. 893 class CallRelocation : public Relocation { 894 public: 895 bool is_call() { return true; } 896 897 address destination() { return pd_call_destination(); } 898 void set_destination(address x); // pd_set_call_destination 899 900 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest); 901 address value() { return destination(); } 902 void set_value(address x) { set_destination(x); } 903 }; 904 905 class oop_Relocation : public DataRelocation { 906 relocInfo::relocType type() { return relocInfo::oop_type; } 907 908 public: 909 // encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll] 910 // an oop in the CodeBlob's oop pool 911 static RelocationHolder spec(int oop_index, int offset = 0) { 912 assert(oop_index > 0, "must be a pool-resident oop"); 913 RelocationHolder rh = newHolder(); 914 new(rh) oop_Relocation(oop_index, offset); 915 return rh; 916 } 917 // an oop in the instruction stream 918 static RelocationHolder spec_for_immediate() { 919 const int oop_index = 0; 920 const int offset = 0; // if you want an offset, use the oop pool 921 RelocationHolder rh = newHolder(); 922 new(rh) oop_Relocation(oop_index, offset); 923 return rh; 924 } 925 926 private: 927 jint _oop_index; // if > 0, index into CodeBlob::oop_at 928 jint _offset; // byte offset to apply to the oop itself 929 930 oop_Relocation(int oop_index, int offset) { 931 _oop_index = oop_index; _offset = offset; 932 } 933 934 friend class RelocIterator; 935 oop_Relocation() { } 936 937 public: 938 int oop_index() { return _oop_index; } 939 int offset() { return _offset; } 940 941 // data is packed in "2_ints" format: [i o] or [Ii Oo] 942 void pack_data_to(CodeSection* dest); 943 void unpack_data(); 944 945 void fix_oop_relocation(); // reasserts oop value 946 947 address value() { return (address) *oop_addr(); } 948 949 bool oop_is_immediate() { return oop_index() == 0; } 950 951 oop* oop_addr(); // addr or &pool[jint_data] 952 oop oop_value(); // *oop_addr 953 // Note: oop_value transparently converts Universe::non_oop_word to NULL. 954 }; 955 956 class virtual_call_Relocation : public CallRelocation { 957 relocInfo::relocType type() { return relocInfo::virtual_call_type; } 958 959 public: 960 // "first_oop" points to the first associated set-oop. 961 // The oop_limit helps find the last associated set-oop. 962 // (See comments at the top of this file.) 963 static RelocationHolder spec(address first_oop, address oop_limit = NULL) { 964 RelocationHolder rh = newHolder(); 965 new(rh) virtual_call_Relocation(first_oop, oop_limit); 966 return rh; 967 } 968 969 virtual_call_Relocation(address first_oop, address oop_limit) { 970 _first_oop = first_oop; _oop_limit = oop_limit; 971 assert(first_oop != NULL, "first oop address must be specified"); 972 } 973 974 private: 975 address _first_oop; // location of first set-oop instruction 976 address _oop_limit; // search limit for set-oop instructions 977 978 friend class RelocIterator; 979 virtual_call_Relocation() { } 980 981 982 public: 983 address first_oop(); 984 address oop_limit(); 985 986 // data is packed as scaled offsets in "2_ints" format: [f l] or [Ff Ll] 987 // oop_limit is set to 0 if the limit falls somewhere within the call. 988 // When unpacking, a zero oop_limit is taken to refer to the end of the call. 989 // (This has the effect of bringing in the call's delay slot on SPARC.) 990 void pack_data_to(CodeSection* dest); 991 void unpack_data(); 992 993 void clear_inline_cache(); 994 995 // Figure out where an ic_call is hiding, given a set-oop or call. 996 // Either ic_call or first_oop must be non-null; the other is deduced. 997 // Code if non-NULL must be the nmethod, else it is deduced. 998 // The address of the patchable oop is also deduced. 999 // The returned iterator will enumerate over the oops and the ic_call, 1000 // as well as any other relocations that happen to be in that span of code. 1001 // Recognize relevant set_oops with: oop_reloc()->oop_addr() == oop_addr. 1002 static RelocIterator parse_ic(nmethod* &nm, address &ic_call, address &first_oop, oop* &oop_addr, bool *is_optimized); 1003 }; 1004 1005 1006 class opt_virtual_call_Relocation : public CallRelocation { 1007 relocInfo::relocType type() { return relocInfo::opt_virtual_call_type; } 1008 1009 public: 1010 static RelocationHolder spec() { 1011 RelocationHolder rh = newHolder(); 1012 new(rh) opt_virtual_call_Relocation(); 1013 return rh; 1014 } 1015 1016 private: 1017 friend class RelocIterator; 1018 opt_virtual_call_Relocation() { } 1019 1020 public: 1021 void clear_inline_cache(); 1022 1023 // find the matching static_stub 1024 address static_stub(); 1025 }; 1026 1027 1028 class static_call_Relocation : public CallRelocation { 1029 relocInfo::relocType type() { return relocInfo::static_call_type; } 1030 1031 public: 1032 static RelocationHolder spec() { 1033 RelocationHolder rh = newHolder(); 1034 new(rh) static_call_Relocation(); 1035 return rh; 1036 } 1037 1038 private: 1039 friend class RelocIterator; 1040 static_call_Relocation() { } 1041 1042 public: 1043 void clear_inline_cache(); 1044 1045 // find the matching static_stub 1046 address static_stub(); 1047 }; 1048 1049 class static_stub_Relocation : public Relocation { 1050 relocInfo::relocType type() { return relocInfo::static_stub_type; } 1051 1052 public: 1053 static RelocationHolder spec(address static_call) { 1054 RelocationHolder rh = newHolder(); 1055 new(rh) static_stub_Relocation(static_call); 1056 return rh; 1057 } 1058 1059 private: 1060 address _static_call; // location of corresponding static_call 1061 1062 static_stub_Relocation(address static_call) { 1063 _static_call = static_call; 1064 } 1065 1066 friend class RelocIterator; 1067 static_stub_Relocation() { } 1068 1069 public: 1070 void clear_inline_cache(); 1071 1072 address static_call() { return _static_call; } 1073 1074 // data is packed as a scaled offset in "1_int" format: [c] or [Cc] 1075 void pack_data_to(CodeSection* dest); 1076 void unpack_data(); 1077 }; 1078 1079 class runtime_call_Relocation : public CallRelocation { 1080 relocInfo::relocType type() { return relocInfo::runtime_call_type; } 1081 1082 public: 1083 static RelocationHolder spec() { 1084 RelocationHolder rh = newHolder(); 1085 new(rh) runtime_call_Relocation(); 1086 return rh; 1087 } 1088 1089 private: 1090 friend class RelocIterator; 1091 runtime_call_Relocation() { } 1092 1093 public: 1094 }; 1095 1096 class external_word_Relocation : public DataRelocation { 1097 relocInfo::relocType type() { return relocInfo::external_word_type; } 1098 1099 public: 1100 static RelocationHolder spec(address target) { 1101 assert(target != NULL, "must not be null"); 1102 RelocationHolder rh = newHolder(); 1103 new(rh) external_word_Relocation(target); 1104 return rh; 1105 } 1106 1107 // Use this one where all 32/64 bits of the target live in the code stream. 1108 // The target must be an intptr_t, and must be absolute (not relative). 1109 static RelocationHolder spec_for_immediate() { 1110 RelocationHolder rh = newHolder(); 1111 new(rh) external_word_Relocation(NULL); 1112 return rh; 1113 } 1114 1115 private: 1116 address _target; // address in runtime 1117 1118 external_word_Relocation(address target) { 1119 _target = target; 1120 } 1121 1122 friend class RelocIterator; 1123 external_word_Relocation() { } 1124 1125 public: 1126 // data is packed as a well-known address in "1_int" format: [a] or [Aa] 1127 // The function runtime_address_to_index is used to turn full addresses 1128 // to short indexes, if they are pre-registered by the stub mechanism. 1129 // If the "a" value is 0 (i.e., _target is NULL), the address is stored 1130 // in the code stream. See external_word_Relocation::target(). 1131 void pack_data_to(CodeSection* dest); 1132 void unpack_data(); 1133 1134 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest); 1135 address target(); // if _target==NULL, fetch addr from code stream 1136 address value() { return target(); } 1137 }; 1138 1139 class internal_word_Relocation : public DataRelocation { 1140 relocInfo::relocType type() { return relocInfo::internal_word_type; } 1141 1142 public: 1143 static RelocationHolder spec(address target) { 1144 assert(target != NULL, "must not be null"); 1145 RelocationHolder rh = newHolder(); 1146 new(rh) internal_word_Relocation(target); 1147 return rh; 1148 } 1149 1150 // use this one where all the bits of the target can fit in the code stream: 1151 static RelocationHolder spec_for_immediate() { 1152 RelocationHolder rh = newHolder(); 1153 new(rh) internal_word_Relocation(NULL); 1154 return rh; 1155 } 1156 1157 internal_word_Relocation(address target) { 1158 _target = target; 1159 _section = -1; // self-relative 1160 } 1161 1162 protected: 1163 address _target; // address in CodeBlob 1164 int _section; // section providing base address, if any 1165 1166 friend class RelocIterator; 1167 internal_word_Relocation() { } 1168 1169 // bit-width of LSB field in packed offset, if section >= 0 1170 enum { section_width = 2 }; // must equal CodeBuffer::sect_bits 1171 1172 public: 1173 // data is packed as a scaled offset in "1_int" format: [o] or [Oo] 1174 // If the "o" value is 0 (i.e., _target is NULL), the offset is stored 1175 // in the code stream. See internal_word_Relocation::target(). 1176 // If _section is not -1, it is appended to the low bits of the offset. 1177 void pack_data_to(CodeSection* dest); 1178 void unpack_data(); 1179 1180 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest); 1181 address target(); // if _target==NULL, fetch addr from code stream 1182 int section() { return _section; } 1183 address value() { return target(); } 1184 }; 1185 1186 class section_word_Relocation : public internal_word_Relocation { 1187 relocInfo::relocType type() { return relocInfo::section_word_type; } 1188 1189 public: 1190 static RelocationHolder spec(address target, int section) { 1191 RelocationHolder rh = newHolder(); 1192 new(rh) section_word_Relocation(target, section); 1193 return rh; 1194 } 1195 1196 section_word_Relocation(address target, int section) { 1197 assert(target != NULL, "must not be null"); 1198 assert(section >= 0, "must be a valid section"); 1199 _target = target; 1200 _section = section; 1201 } 1202 1203 //void pack_data_to -- inherited 1204 void unpack_data(); 1205 1206 private: 1207 friend class RelocIterator; 1208 section_word_Relocation() { } 1209 }; 1210 1211 1212 class poll_Relocation : public Relocation { 1213 bool is_data() { return true; } 1214 relocInfo::relocType type() { return relocInfo::poll_type; } 1215 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest); 1216 }; 1217 1218 class poll_return_Relocation : public Relocation { 1219 bool is_data() { return true; } 1220 relocInfo::relocType type() { return relocInfo::poll_return_type; } 1221 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest); 1222 }; 1223 1224 1225 class breakpoint_Relocation : public Relocation { 1226 relocInfo::relocType type() { return relocInfo::breakpoint_type; } 1227 1228 enum { 1229 // attributes which affect the interpretation of the data: 1230 removable_attr = 0x0010, // buffer [i...] allows for undoing the trap 1231 internal_attr = 0x0020, // the target is an internal addr (local stub) 1232 settable_attr = 0x0040, // the target is settable 1233 1234 // states which can change over time: 1235 enabled_state = 0x0100, // breakpoint must be active in running code 1236 active_state = 0x0200, // breakpoint instruction actually in code 1237 1238 kind_mask = 0x000F, // mask for extracting kind 1239 high_bit = 0x4000 // extra bit which is always set 1240 }; 1241 1242 public: 1243 enum { 1244 // kinds: 1245 initialization = 1, 1246 safepoint = 2 1247 }; 1248 1249 // If target is NULL, 32 bits are reserved for a later set_target(). 1250 static RelocationHolder spec(int kind, address target = NULL, bool internal_target = false) { 1251 RelocationHolder rh = newHolder(); 1252 new(rh) breakpoint_Relocation(kind, target, internal_target); 1253 return rh; 1254 } 1255 1256 private: 1257 // We require every bits value to NOT to fit into relocInfo::datalen_width, 1258 // because we are going to actually store state in the reloc, and so 1259 // cannot allow it to be compressed (and hence copied by the iterator). 1260 1261 short _bits; // bit-encoded kind, attrs, & state 1262 address _target; 1263 1264 breakpoint_Relocation(int kind, address target, bool internal_target); 1265 1266 friend class RelocIterator; 1267 breakpoint_Relocation() { } 1268 1269 short bits() const { return _bits; } 1270 short& live_bits() const { return data()[0]; } 1271 short* instrs() const { return data() + datalen() - instrlen(); } 1272 int instrlen() const { return removable() ? pd_breakpoint_size() : 0; } 1273 1274 void set_bits(short x) { 1275 assert(live_bits() == _bits, "must be the only mutator of reloc info"); 1276 live_bits() = _bits = x; 1277 } 1278 1279 public: 1280 address target() const; 1281 void set_target(address x); 1282 1283 int kind() const { return bits() & kind_mask; } 1284 bool enabled() const { return (bits() & enabled_state) != 0; } 1285 bool active() const { return (bits() & active_state) != 0; } 1286 bool internal() const { return (bits() & internal_attr) != 0; } 1287 bool removable() const { return (bits() & removable_attr) != 0; } 1288 bool settable() const { return (bits() & settable_attr) != 0; } 1289 1290 void set_enabled(bool b); // to activate, you must also say set_active 1291 void set_active(bool b); // actually inserts bpt (must be enabled 1st) 1292 1293 // data is packed as 16 bits, followed by the target (1 or 2 words), followed 1294 // if necessary by empty storage for saving away original instruction bytes. 1295 void pack_data_to(CodeSection* dest); 1296 void unpack_data(); 1297 1298 // during certain operations, breakpoints must be out of the way: 1299 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { 1300 assert(!active(), "cannot perform relocation on enabled breakpoints"); 1301 } 1302 }; 1303 1304 1305 // We know all the xxx_Relocation classes, so now we can define these: 1306 #define EACH_CASE(name) \ 1307 inline name##_Relocation* RelocIterator::name##_reloc() { \ 1308 assert(type() == relocInfo::name##_type, "type must agree"); \ 1309 /* The purpose of the placed "new" is to re-use the same */ \ 1310 /* stack storage for each new iteration. */ \ 1311 name##_Relocation* r = new(_rh) name##_Relocation(); \ 1312 r->set_binding(this); \ 1313 r->name##_Relocation::unpack_data(); \ 1314 return r; \ 1315 } 1316 APPLY_TO_RELOCATIONS(EACH_CASE); 1317 #undef EACH_CASE 1318 1319 inline RelocIterator::RelocIterator(nmethod* nm, address begin, address limit) { 1320 initialize(nm, begin, limit); 1321 } 1322 1323 // if you are going to patch code, you should use this subclass of 1324 // RelocIterator 1325 class PatchingRelocIterator : public RelocIterator { 1326 private: 1327 RelocIterator _init_state; 1328 1329 void prepass(); // deactivates all breakpoints 1330 void postpass(); // reactivates all enabled breakpoints 1331 1332 // do not copy these puppies; it would have unpredictable side effects 1333 // these are private and have no bodies defined because they should not be called 1334 PatchingRelocIterator(const RelocIterator&); 1335 void operator=(const RelocIterator&); 1336 1337 public: 1338 PatchingRelocIterator(nmethod* nm, address begin = NULL, address limit = NULL) 1339 : RelocIterator(nm, begin, limit) { prepass(); } 1340 1341 ~PatchingRelocIterator() { postpass(); } 1342 }; 1343 1344 #endif // SHARE_VM_CODE_RELOCINFO_HPP