1//===- Chunks.cpp ---------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "Chunks.h"
10#include "COFFLinkerContext.h"
11#include "InputFiles.h"
12#include "SymbolTable.h"
13#include "Symbols.h"
14#include "Writer.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/ADT/StringExtras.h"
17#include "llvm/ADT/Twine.h"
18#include "llvm/BinaryFormat/COFF.h"
19#include "llvm/Object/COFF.h"
20#include "llvm/Support/Debug.h"
21#include "llvm/Support/Endian.h"
22#include "llvm/Support/raw_ostream.h"
23#include <algorithm>
24#include <iterator>
25
26using namespace llvm;
27using namespace llvm::object;
28using namespace llvm::support;
29using namespace llvm::support::endian;
30using namespace llvm::COFF;
31using llvm::support::ulittle32_t;
32
33namespace lld::coff {
34
35SectionChunk::SectionChunk(ObjFile *f, const coff_section *h, Kind k)
36 : Chunk(k), file(f), header(h), repl(this) {
37 // Initialize relocs.
38 if (file)
39 setRelocs(file->getCOFFObj()->getRelocations(Sec: header));
40
41 // Initialize sectionName.
42 StringRef sectionName;
43 if (file) {
44 if (Expected<StringRef> e = file->getCOFFObj()->getSectionName(Sec: header))
45 sectionName = *e;
46 }
47 sectionNameData = sectionName.data();
48 sectionNameSize = sectionName.size();
49
50 setAlignment(header->getAlignment());
51
52 hasData = !(header->Characteristics & IMAGE_SCN_CNT_UNINITIALIZED_DATA);
53
54 // If linker GC is disabled, every chunk starts out alive. If linker GC is
55 // enabled, treat non-comdat sections as roots. Generally optimized object
56 // files will be built with -ffunction-sections or /Gy, so most things worth
57 // stripping will be in a comdat.
58 if (file)
59 live = !file->symtab.ctx.config.doGC || !isCOMDAT();
60 else
61 live = true;
62}
63
64MachineTypes SectionChunk::getMachine() const {
65 MachineTypes machine = file->getMachineType();
66 // On ARM64EC, the IMAGE_SCN_GPREL flag is repurposed to indicate that section
67 // code is x86_64. This enables embedding x86_64 code within ARM64EC object
68 // files. MSVC uses this for export thunks in .exp files.
69 if (isArm64EC(Machine: machine) && (header->Characteristics & IMAGE_SCN_GPREL))
70 machine = AMD64;
71 return machine;
72}
73
74// SectionChunk is one of the most frequently allocated classes, so it is
75// important to keep it as compact as possible. As of this writing, the number
76// below is the size of this class on x64 platforms.
77static_assert(sizeof(SectionChunk) <= 88, "SectionChunk grew unexpectedly");
78
79static void add16(uint8_t *p, int16_t v) { write16le(P: p, V: read16le(P: p) + v); }
80static void add32(uint8_t *p, int32_t v) { write32le(P: p, V: read32le(P: p) + v); }
81static void add64(uint8_t *p, int64_t v) { write64le(P: p, V: read64le(P: p) + v); }
82static void or16(uint8_t *p, uint16_t v) { write16le(P: p, V: read16le(P: p) | v); }
83static void or32(uint8_t *p, uint32_t v) { write32le(P: p, V: read32le(P: p) | v); }
84
85// Verify that given sections are appropriate targets for SECREL
86// relocations. This check is relaxed because unfortunately debug
87// sections have section-relative relocations against absolute symbols.
88static bool checkSecRel(const SectionChunk *sec, OutputSection *os) {
89 if (os)
90 return true;
91 if (sec->isCodeView())
92 return false;
93 error(msg: "SECREL relocation cannot be applied to absolute symbols");
94 return false;
95}
96
97static void applySecRel(const SectionChunk *sec, uint8_t *off,
98 OutputSection *os, uint64_t s) {
99 if (!checkSecRel(sec, os))
100 return;
101 uint64_t secRel = s - os->getRVA();
102 if (secRel > UINT32_MAX) {
103 error(msg: "overflow in SECREL relocation in section: " + sec->getSectionName());
104 return;
105 }
106 add32(p: off, v: secRel);
107}
108
109static void applySecIdx(uint8_t *off, OutputSection *os,
110 unsigned numOutputSections) {
111 // numOutputSections is the largest valid section index. Make sure that
112 // it fits in 16 bits.
113 assert(numOutputSections <= 0xffff && "size of outputSections is too big");
114
115 // Absolute symbol doesn't have section index, but section index relocation
116 // against absolute symbol should be resolved to one plus the last output
117 // section index. This is required for compatibility with MSVC.
118 if (os)
119 add16(p: off, v: os->sectionIndex);
120 else
121 add16(p: off, v: numOutputSections + 1);
122}
123
124void SectionChunk::applyRelX64(uint8_t *off, uint16_t type, OutputSection *os,
125 uint64_t s, uint64_t p,
126 uint64_t imageBase) const {
127 switch (type) {
128 case IMAGE_REL_AMD64_ADDR32:
129 add32(p: off, v: s + imageBase);
130 break;
131 case IMAGE_REL_AMD64_ADDR64:
132 add64(p: off, v: s + imageBase);
133 break;
134 case IMAGE_REL_AMD64_ADDR32NB: add32(p: off, v: s); break;
135 case IMAGE_REL_AMD64_REL32: add32(p: off, v: s - p - 4); break;
136 case IMAGE_REL_AMD64_REL32_1: add32(p: off, v: s - p - 5); break;
137 case IMAGE_REL_AMD64_REL32_2: add32(p: off, v: s - p - 6); break;
138 case IMAGE_REL_AMD64_REL32_3: add32(p: off, v: s - p - 7); break;
139 case IMAGE_REL_AMD64_REL32_4: add32(p: off, v: s - p - 8); break;
140 case IMAGE_REL_AMD64_REL32_5: add32(p: off, v: s - p - 9); break;
141 case IMAGE_REL_AMD64_SECTION:
142 applySecIdx(off, os, numOutputSections: file->symtab.ctx.outputSections.size());
143 break;
144 case IMAGE_REL_AMD64_SECREL: applySecRel(sec: this, off, os, s); break;
145 default:
146 error(msg: "unsupported relocation type 0x" + Twine::utohexstr(Val: type) + " in " +
147 toString(file));
148 }
149}
150
151void SectionChunk::applyRelX86(uint8_t *off, uint16_t type, OutputSection *os,
152 uint64_t s, uint64_t p,
153 uint64_t imageBase) const {
154 switch (type) {
155 case IMAGE_REL_I386_ABSOLUTE: break;
156 case IMAGE_REL_I386_DIR32:
157 add32(p: off, v: s + imageBase);
158 break;
159 case IMAGE_REL_I386_DIR32NB: add32(p: off, v: s); break;
160 case IMAGE_REL_I386_REL32: add32(p: off, v: s - p - 4); break;
161 case IMAGE_REL_I386_SECTION:
162 applySecIdx(off, os, numOutputSections: file->symtab.ctx.outputSections.size());
163 break;
164 case IMAGE_REL_I386_SECREL: applySecRel(sec: this, off, os, s); break;
165 default:
166 error(msg: "unsupported relocation type 0x" + Twine::utohexstr(Val: type) + " in " +
167 toString(file));
168 }
169}
170
171static void applyMOV(uint8_t *off, uint16_t v) {
172 write16le(P: off, V: (read16le(P: off) & 0xfbf0) | ((v & 0x800) >> 1) | ((v >> 12) & 0xf));
173 write16le(P: off + 2, V: (read16le(P: off + 2) & 0x8f00) | ((v & 0x700) << 4) | (v & 0xff));
174}
175
176static uint16_t readMOV(uint8_t *off, bool movt) {
177 uint16_t op1 = read16le(P: off);
178 if ((op1 & 0xfbf0) != (movt ? 0xf2c0 : 0xf240))
179 error(msg: "unexpected instruction in " + Twine(movt ? "MOVT" : "MOVW") +
180 " instruction in MOV32T relocation");
181 uint16_t op2 = read16le(P: off + 2);
182 if ((op2 & 0x8000) != 0)
183 error(msg: "unexpected instruction in " + Twine(movt ? "MOVT" : "MOVW") +
184 " instruction in MOV32T relocation");
185 return (op2 & 0x00ff) | ((op2 >> 4) & 0x0700) | ((op1 << 1) & 0x0800) |
186 ((op1 & 0x000f) << 12);
187}
188
189void applyMOV32T(uint8_t *off, uint32_t v) {
190 uint16_t immW = readMOV(off, movt: false); // read MOVW operand
191 uint16_t immT = readMOV(off: off + 4, movt: true); // read MOVT operand
192 uint32_t imm = immW | (immT << 16);
193 v += imm; // add the immediate offset
194 applyMOV(off, v); // set MOVW operand
195 applyMOV(off: off + 4, v: v >> 16); // set MOVT operand
196}
197
198static void applyBranch20T(uint8_t *off, int32_t v) {
199 if (!isInt<21>(x: v))
200 error(msg: "relocation out of range");
201 uint32_t s = v < 0 ? 1 : 0;
202 uint32_t j1 = (v >> 19) & 1;
203 uint32_t j2 = (v >> 18) & 1;
204 or16(p: off, v: (s << 10) | ((v >> 12) & 0x3f));
205 or16(p: off + 2, v: (j1 << 13) | (j2 << 11) | ((v >> 1) & 0x7ff));
206}
207
208void applyBranch24T(uint8_t *off, int32_t v) {
209 if (!isInt<25>(x: v))
210 error(msg: "relocation out of range");
211 uint32_t s = v < 0 ? 1 : 0;
212 uint32_t j1 = ((~v >> 23) & 1) ^ s;
213 uint32_t j2 = ((~v >> 22) & 1) ^ s;
214 or16(p: off, v: (s << 10) | ((v >> 12) & 0x3ff));
215 // Clear out the J1 and J2 bits which may be set.
216 write16le(P: off + 2, V: (read16le(P: off + 2) & 0xd000) | (j1 << 13) | (j2 << 11) | ((v >> 1) & 0x7ff));
217}
218
219void SectionChunk::applyRelARM(uint8_t *off, uint16_t type, OutputSection *os,
220 uint64_t s, uint64_t p,
221 uint64_t imageBase) const {
222 // Pointer to thumb code must have the LSB set.
223 uint64_t sx = s;
224 if (os && (os->header.Characteristics & IMAGE_SCN_MEM_EXECUTE))
225 sx |= 1;
226 switch (type) {
227 case IMAGE_REL_ARM_ADDR32:
228 add32(p: off, v: sx + imageBase);
229 break;
230 case IMAGE_REL_ARM_ADDR32NB: add32(p: off, v: sx); break;
231 case IMAGE_REL_ARM_MOV32T:
232 applyMOV32T(off, v: sx + imageBase);
233 break;
234 case IMAGE_REL_ARM_BRANCH20T: applyBranch20T(off, v: sx - p - 4); break;
235 case IMAGE_REL_ARM_BRANCH24T: applyBranch24T(off, v: sx - p - 4); break;
236 case IMAGE_REL_ARM_BLX23T: applyBranch24T(off, v: sx - p - 4); break;
237 case IMAGE_REL_ARM_SECTION:
238 applySecIdx(off, os, numOutputSections: file->symtab.ctx.outputSections.size());
239 break;
240 case IMAGE_REL_ARM_SECREL: applySecRel(sec: this, off, os, s); break;
241 case IMAGE_REL_ARM_REL32: add32(p: off, v: sx - p - 4); break;
242 default:
243 error(msg: "unsupported relocation type 0x" + Twine::utohexstr(Val: type) + " in " +
244 toString(file));
245 }
246}
247
248// Interpret the existing immediate value as a byte offset to the
249// target symbol, then update the instruction with the immediate as
250// the page offset from the current instruction to the target.
251void applyArm64Addr(uint8_t *off, uint64_t s, uint64_t p, int shift) {
252 uint32_t orig = read32le(P: off);
253 int64_t imm =
254 SignExtend64<21>(x: ((orig >> 29) & 0x3) | ((orig >> 3) & 0x1FFFFC));
255 s += imm;
256 imm = (s >> shift) - (p >> shift);
257 uint32_t immLo = (imm & 0x3) << 29;
258 uint32_t immHi = (imm & 0x1FFFFC) << 3;
259 uint64_t mask = (0x3 << 29) | (0x1FFFFC << 3);
260 write32le(P: off, V: (orig & ~mask) | immLo | immHi);
261}
262
263// Update the immediate field in a AARCH64 ldr, str, and add instruction.
264// Optionally limit the range of the written immediate by one or more bits
265// (rangeLimit).
266void applyArm64Imm(uint8_t *off, uint64_t imm, uint32_t rangeLimit) {
267 uint32_t orig = read32le(P: off);
268 imm += (orig >> 10) & 0xFFF;
269 orig &= ~(0xFFF << 10);
270 write32le(P: off, V: orig | ((imm & (0xFFF >> rangeLimit)) << 10));
271}
272
273// Add the 12 bit page offset to the existing immediate.
274// Ldr/str instructions store the opcode immediate scaled
275// by the load/store size (giving a larger range for larger
276// loads/stores). The immediate is always (both before and after
277// fixing up the relocation) stored scaled similarly.
278// Even if larger loads/stores have a larger range, limit the
279// effective offset to 12 bit, since it is intended to be a
280// page offset.
281static void applyArm64Ldr(uint8_t *off, uint64_t imm) {
282 uint32_t orig = read32le(P: off);
283 uint32_t size = orig >> 30;
284 // 0x04000000 indicates SIMD/FP registers
285 // 0x00800000 indicates 128 bit
286 if ((orig & 0x4800000) == 0x4800000)
287 size += 4;
288 if ((imm & ((1 << size) - 1)) != 0)
289 error(msg: "misaligned ldr/str offset");
290 applyArm64Imm(off, imm: imm >> size, rangeLimit: size);
291}
292
293static void applySecRelLow12A(const SectionChunk *sec, uint8_t *off,
294 OutputSection *os, uint64_t s) {
295 if (checkSecRel(sec, os))
296 applyArm64Imm(off, imm: (s - os->getRVA()) & 0xfff, rangeLimit: 0);
297}
298
299static void applySecRelHigh12A(const SectionChunk *sec, uint8_t *off,
300 OutputSection *os, uint64_t s) {
301 if (!checkSecRel(sec, os))
302 return;
303 uint64_t secRel = (s - os->getRVA()) >> 12;
304 if (0xfff < secRel) {
305 error(msg: "overflow in SECREL_HIGH12A relocation in section: " +
306 sec->getSectionName());
307 return;
308 }
309 applyArm64Imm(off, imm: secRel & 0xfff, rangeLimit: 0);
310}
311
312static void applySecRelLdr(const SectionChunk *sec, uint8_t *off,
313 OutputSection *os, uint64_t s) {
314 if (checkSecRel(sec, os))
315 applyArm64Ldr(off, imm: (s - os->getRVA()) & 0xfff);
316}
317
318void applyArm64Branch26(uint8_t *off, int64_t v) {
319 if (!isInt<28>(x: v))
320 error(msg: "relocation out of range");
321 or32(p: off, v: (v & 0x0FFFFFFC) >> 2);
322}
323
324static void applyArm64Branch19(uint8_t *off, int64_t v) {
325 if (!isInt<21>(x: v))
326 error(msg: "relocation out of range");
327 or32(p: off, v: (v & 0x001FFFFC) << 3);
328}
329
330static void applyArm64Branch14(uint8_t *off, int64_t v) {
331 if (!isInt<16>(x: v))
332 error(msg: "relocation out of range");
333 or32(p: off, v: (v & 0x0000FFFC) << 3);
334}
335
336void SectionChunk::applyRelARM64(uint8_t *off, uint16_t type, OutputSection *os,
337 uint64_t s, uint64_t p,
338 uint64_t imageBase) const {
339 switch (type) {
340 case IMAGE_REL_ARM64_PAGEBASE_REL21: applyArm64Addr(off, s, p, shift: 12); break;
341 case IMAGE_REL_ARM64_REL21: applyArm64Addr(off, s, p, shift: 0); break;
342 case IMAGE_REL_ARM64_PAGEOFFSET_12A: applyArm64Imm(off, imm: s & 0xfff, rangeLimit: 0); break;
343 case IMAGE_REL_ARM64_PAGEOFFSET_12L: applyArm64Ldr(off, imm: s & 0xfff); break;
344 case IMAGE_REL_ARM64_BRANCH26: applyArm64Branch26(off, v: s - p); break;
345 case IMAGE_REL_ARM64_BRANCH19: applyArm64Branch19(off, v: s - p); break;
346 case IMAGE_REL_ARM64_BRANCH14: applyArm64Branch14(off, v: s - p); break;
347 case IMAGE_REL_ARM64_ADDR32:
348 add32(p: off, v: s + imageBase);
349 break;
350 case IMAGE_REL_ARM64_ADDR32NB: add32(p: off, v: s); break;
351 case IMAGE_REL_ARM64_ADDR64:
352 add64(p: off, v: s + imageBase);
353 break;
354 case IMAGE_REL_ARM64_SECREL: applySecRel(sec: this, off, os, s); break;
355 case IMAGE_REL_ARM64_SECREL_LOW12A: applySecRelLow12A(sec: this, off, os, s); break;
356 case IMAGE_REL_ARM64_SECREL_HIGH12A: applySecRelHigh12A(sec: this, off, os, s); break;
357 case IMAGE_REL_ARM64_SECREL_LOW12L: applySecRelLdr(sec: this, off, os, s); break;
358 case IMAGE_REL_ARM64_SECTION:
359 applySecIdx(off, os, numOutputSections: file->symtab.ctx.outputSections.size());
360 break;
361 case IMAGE_REL_ARM64_REL32: add32(p: off, v: s - p - 4); break;
362 default:
363 error(msg: "unsupported relocation type 0x" + Twine::utohexstr(Val: type) + " in " +
364 toString(file));
365 }
366}
367
368static void maybeReportRelocationToDiscarded(const SectionChunk *fromChunk,
369 Defined *sym,
370 const coff_relocation &rel,
371 bool isMinGW) {
372 // Don't report these errors when the relocation comes from a debug info
373 // section or in mingw mode. MinGW mode object files (built by GCC) can
374 // have leftover sections with relocations against discarded comdat
375 // sections. Such sections are left as is, with relocations untouched.
376 if (fromChunk->isCodeView() || fromChunk->isDWARF() || isMinGW)
377 return;
378
379 // Get the name of the symbol. If it's null, it was discarded early, so we
380 // have to go back to the object file.
381 ObjFile *file = fromChunk->file;
382 std::string name;
383 if (sym) {
384 name = toString(ctx: file->symtab.ctx, b&: *sym);
385 } else {
386 COFFSymbolRef coffSym =
387 check(e: file->getCOFFObj()->getSymbol(index: rel.SymbolTableIndex));
388 name = maybeDemangleSymbol(
389 ctx: file->symtab.ctx, symName: check(e: file->getCOFFObj()->getSymbolName(Symbol: coffSym)));
390 }
391
392 std::vector<std::string> symbolLocations =
393 getSymbolLocations(file, symIndex: rel.SymbolTableIndex);
394
395 std::string out;
396 llvm::raw_string_ostream os(out);
397 os << "relocation against symbol in discarded section: " + name;
398 for (const std::string &s : symbolLocations)
399 os << s;
400 error(msg: out);
401}
402
403void SectionChunk::writeTo(uint8_t *buf) const {
404 if (!hasData)
405 return;
406 // Copy section contents from source object file to output file.
407 ArrayRef<uint8_t> a = getContents();
408 if (!a.empty())
409 memcpy(dest: buf, src: a.data(), n: a.size());
410
411 // Apply relocations.
412 size_t inputSize = getSize();
413 for (const coff_relocation &rel : getRelocs()) {
414 // Check for an invalid relocation offset. This check isn't perfect, because
415 // we don't have the relocation size, which is only known after checking the
416 // machine and relocation type. As a result, a relocation may overwrite the
417 // beginning of the following input section.
418 if (rel.VirtualAddress >= inputSize) {
419 error(msg: "relocation points beyond the end of its parent section");
420 continue;
421 }
422
423 applyRelocation(off: buf + rel.VirtualAddress, rel);
424 }
425
426 // Write the offset to EC entry thunk preceding section contents. The low bit
427 // is always set, so it's effectively an offset from the last byte of the
428 // offset.
429 if (Defined *entryThunk = getEntryThunk())
430 write32le(P: buf - sizeof(uint32_t), V: entryThunk->getRVA() - rva + 1);
431}
432
433void SectionChunk::applyRelocation(uint8_t *off,
434 const coff_relocation &rel) const {
435 auto *sym = dyn_cast_or_null<Defined>(Val: file->getSymbol(symbolIndex: rel.SymbolTableIndex));
436
437 // Get the output section of the symbol for this relocation. The output
438 // section is needed to compute SECREL and SECTION relocations used in debug
439 // info.
440 Chunk *c = sym ? sym->getChunk() : nullptr;
441 COFFLinkerContext &ctx = file->symtab.ctx;
442 OutputSection *os = c ? ctx.getOutputSection(c) : nullptr;
443
444 // Skip the relocation if it refers to a discarded section, and diagnose it
445 // as an error if appropriate. If a symbol was discarded early, it may be
446 // null. If it was discarded late, the output section will be null, unless
447 // it was an absolute or synthetic symbol.
448 if (!sym ||
449 (!os && !isa<DefinedAbsolute>(Val: sym) && !isa<DefinedSynthetic>(Val: sym))) {
450 maybeReportRelocationToDiscarded(fromChunk: this, sym, rel, isMinGW: ctx.config.mingw);
451 return;
452 }
453
454 uint64_t s = sym->getRVA();
455
456 // Compute the RVA of the relocation for relative relocations.
457 uint64_t p = rva + rel.VirtualAddress;
458 uint64_t imageBase = ctx.config.imageBase;
459 switch (getArch()) {
460 case Triple::x86_64:
461 applyRelX64(off, type: rel.Type, os, s, p, imageBase);
462 break;
463 case Triple::x86:
464 applyRelX86(off, type: rel.Type, os, s, p, imageBase);
465 break;
466 case Triple::thumb:
467 applyRelARM(off, type: rel.Type, os, s, p, imageBase);
468 break;
469 case Triple::aarch64:
470 applyRelARM64(off, type: rel.Type, os, s, p, imageBase);
471 break;
472 default:
473 llvm_unreachable("unknown machine type");
474 }
475}
476
477// Defend against unsorted relocations. This may be overly conservative.
478void SectionChunk::sortRelocations() {
479 auto cmpByVa = [](const coff_relocation &l, const coff_relocation &r) {
480 return l.VirtualAddress < r.VirtualAddress;
481 };
482 if (llvm::is_sorted(Range: getRelocs(), C: cmpByVa))
483 return;
484 warn(msg: "some relocations in " + file->getName() + " are not sorted");
485 MutableArrayRef<coff_relocation> newRelocs(
486 bAlloc().Allocate<coff_relocation>(Num: relocsSize), relocsSize);
487 memcpy(dest: newRelocs.data(), src: relocsData, n: relocsSize * sizeof(coff_relocation));
488 llvm::sort(C&: newRelocs, Comp: cmpByVa);
489 setRelocs(newRelocs);
490}
491
492// Similar to writeTo, but suitable for relocating a subsection of the overall
493// section.
494void SectionChunk::writeAndRelocateSubsection(ArrayRef<uint8_t> sec,
495 ArrayRef<uint8_t> subsec,
496 uint32_t &nextRelocIndex,
497 uint8_t *buf) const {
498 assert(!subsec.empty() && !sec.empty());
499 assert(sec.begin() <= subsec.begin() && subsec.end() <= sec.end() &&
500 "subsection is not part of this section");
501 size_t vaBegin = std::distance(first: sec.begin(), last: subsec.begin());
502 size_t vaEnd = std::distance(first: sec.begin(), last: subsec.end());
503 memcpy(dest: buf, src: subsec.data(), n: subsec.size());
504 for (; nextRelocIndex < relocsSize; ++nextRelocIndex) {
505 const coff_relocation &rel = relocsData[nextRelocIndex];
506 // Only apply relocations that apply to this subsection. These checks
507 // assume that all subsections completely contain their relocations.
508 // Relocations must not straddle the beginning or end of a subsection.
509 if (rel.VirtualAddress < vaBegin)
510 continue;
511 if (rel.VirtualAddress + 1 >= vaEnd)
512 break;
513 applyRelocation(off: &buf[rel.VirtualAddress - vaBegin], rel);
514 }
515}
516
517void SectionChunk::addAssociative(SectionChunk *child) {
518 // Insert the child section into the list of associated children. Keep the
519 // list ordered by section name so that ICF does not depend on section order.
520 assert(child->assocChildren == nullptr &&
521 "associated sections cannot have their own associated children");
522 SectionChunk *prev = this;
523 SectionChunk *next = assocChildren;
524 for (; next != nullptr; prev = next, next = next->assocChildren) {
525 if (next->getSectionName() <= child->getSectionName())
526 break;
527 }
528
529 // Insert child between prev and next.
530 assert(prev->assocChildren == next);
531 prev->assocChildren = child;
532 child->assocChildren = next;
533}
534
535static uint8_t getBaserelType(const coff_relocation &rel,
536 Triple::ArchType arch) {
537 switch (arch) {
538 case Triple::x86_64:
539 if (rel.Type == IMAGE_REL_AMD64_ADDR64)
540 return IMAGE_REL_BASED_DIR64;
541 if (rel.Type == IMAGE_REL_AMD64_ADDR32)
542 return IMAGE_REL_BASED_HIGHLOW;
543 return IMAGE_REL_BASED_ABSOLUTE;
544 case Triple::x86:
545 if (rel.Type == IMAGE_REL_I386_DIR32)
546 return IMAGE_REL_BASED_HIGHLOW;
547 return IMAGE_REL_BASED_ABSOLUTE;
548 case Triple::thumb:
549 if (rel.Type == IMAGE_REL_ARM_ADDR32)
550 return IMAGE_REL_BASED_HIGHLOW;
551 if (rel.Type == IMAGE_REL_ARM_MOV32T)
552 return IMAGE_REL_BASED_ARM_MOV32T;
553 return IMAGE_REL_BASED_ABSOLUTE;
554 case Triple::aarch64:
555 if (rel.Type == IMAGE_REL_ARM64_ADDR64)
556 return IMAGE_REL_BASED_DIR64;
557 return IMAGE_REL_BASED_ABSOLUTE;
558 default:
559 llvm_unreachable("unknown machine type");
560 }
561}
562
563// Windows-specific.
564// Collect all locations that contain absolute addresses, which need to be
565// fixed by the loader if load-time relocation is needed.
566// Only called when base relocation is enabled.
567void SectionChunk::getBaserels(std::vector<Baserel> *res) {
568 for (const coff_relocation &rel : getRelocs()) {
569 uint8_t ty = getBaserelType(rel, arch: getArch());
570 if (ty == IMAGE_REL_BASED_ABSOLUTE)
571 continue;
572 Symbol *target = file->getSymbol(symbolIndex: rel.SymbolTableIndex);
573 if (!target || isa<DefinedAbsolute>(Val: target))
574 continue;
575 res->emplace_back(args: rva + rel.VirtualAddress, args&: ty);
576 }
577
578 // Insert a 64-bit relocation for CHPEMetadataPointer in the native load
579 // config of a hybrid ARM64X image. Its value will be set in prepareLoadConfig
580 // to match the value in the EC load config, which is expected to be
581 // a relocatable pointer to the __chpe_metadata symbol.
582 COFFLinkerContext &ctx = file->symtab.ctx;
583 if (ctx.config.machine == ARM64X && ctx.hybridSymtab->loadConfigSym &&
584 ctx.hybridSymtab->loadConfigSym->getChunk() == this &&
585 ctx.symtab.loadConfigSym &&
586 ctx.hybridSymtab->loadConfigSize >=
587 offsetof(coff_load_configuration64, CHPEMetadataPointer) +
588 sizeof(coff_load_configuration64::CHPEMetadataPointer))
589 res->emplace_back(
590 args: ctx.hybridSymtab->loadConfigSym->getRVA() +
591 offsetof(coff_load_configuration64, CHPEMetadataPointer),
592 args: IMAGE_REL_BASED_DIR64);
593}
594
595// MinGW specific.
596// Check whether a static relocation of type Type can be deferred and
597// handled at runtime as a pseudo relocation (for references to a module
598// local variable, which turned out to actually need to be imported from
599// another DLL) This returns the size the relocation is supposed to update,
600// in bits, or 0 if the relocation cannot be handled as a runtime pseudo
601// relocation.
602static int getRuntimePseudoRelocSize(uint16_t type, Triple::ArchType arch) {
603 // Relocations that either contain an absolute address, or a plain
604 // relative offset, since the runtime pseudo reloc implementation
605 // adds 8/16/32/64 bit values to a memory address.
606 //
607 // Given a pseudo relocation entry,
608 //
609 // typedef struct {
610 // DWORD sym;
611 // DWORD target;
612 // DWORD flags;
613 // } runtime_pseudo_reloc_item_v2;
614 //
615 // the runtime relocation performs this adjustment:
616 // *(base + .target) += *(base + .sym) - (base + .sym)
617 //
618 // This works for both absolute addresses (IMAGE_REL_*_ADDR32/64,
619 // IMAGE_REL_I386_DIR32, where the memory location initially contains
620 // the address of the IAT slot, and for relative addresses (IMAGE_REL*_REL32),
621 // where the memory location originally contains the relative offset to the
622 // IAT slot.
623 //
624 // This requires the target address to be writable, either directly out of
625 // the image, or temporarily changed at runtime with VirtualProtect.
626 // Since this only operates on direct address values, it doesn't work for
627 // ARM/ARM64 relocations, other than the plain ADDR32/ADDR64 relocations.
628 switch (arch) {
629 case Triple::x86_64:
630 switch (type) {
631 case IMAGE_REL_AMD64_ADDR64:
632 return 64;
633 case IMAGE_REL_AMD64_ADDR32:
634 case IMAGE_REL_AMD64_REL32:
635 case IMAGE_REL_AMD64_REL32_1:
636 case IMAGE_REL_AMD64_REL32_2:
637 case IMAGE_REL_AMD64_REL32_3:
638 case IMAGE_REL_AMD64_REL32_4:
639 case IMAGE_REL_AMD64_REL32_5:
640 return 32;
641 default:
642 return 0;
643 }
644 case Triple::x86:
645 switch (type) {
646 case IMAGE_REL_I386_DIR32:
647 case IMAGE_REL_I386_REL32:
648 return 32;
649 default:
650 return 0;
651 }
652 case Triple::thumb:
653 switch (type) {
654 case IMAGE_REL_ARM_ADDR32:
655 return 32;
656 default:
657 return 0;
658 }
659 case Triple::aarch64:
660 switch (type) {
661 case IMAGE_REL_ARM64_ADDR64:
662 return 64;
663 case IMAGE_REL_ARM64_ADDR32:
664 return 32;
665 default:
666 return 0;
667 }
668 default:
669 llvm_unreachable("unknown machine type");
670 }
671}
672
673// MinGW specific.
674// Append information to the provided vector about all relocations that
675// need to be handled at runtime as runtime pseudo relocations (references
676// to a module local variable, which turned out to actually need to be
677// imported from another DLL).
678void SectionChunk::getRuntimePseudoRelocs(
679 std::vector<RuntimePseudoReloc> &res) {
680 for (const coff_relocation &rel : getRelocs()) {
681 auto *target =
682 dyn_cast_or_null<Defined>(Val: file->getSymbol(symbolIndex: rel.SymbolTableIndex));
683 if (!target || !target->isRuntimePseudoReloc)
684 continue;
685 // If the target doesn't have a chunk allocated, it may be a
686 // DefinedImportData symbol which ended up unnecessary after GC.
687 // Normally we wouldn't eliminate section chunks that are referenced, but
688 // references within DWARF sections don't count for keeping section chunks
689 // alive. Thus such dangling references in DWARF sections are expected.
690 if (!target->getChunk())
691 continue;
692 int sizeInBits = getRuntimePseudoRelocSize(type: rel.Type, arch: getArch());
693 if (sizeInBits == 0) {
694 error(msg: "unable to automatically import from " + target->getName() +
695 " with relocation type " +
696 file->getCOFFObj()->getRelocationTypeName(Type: rel.Type) + " in " +
697 toString(file));
698 continue;
699 }
700 int addressSizeInBits = file->symtab.ctx.config.is64() ? 64 : 32;
701 if (sizeInBits < addressSizeInBits) {
702 warn(msg: "runtime pseudo relocation in " + toString(file) + " against " +
703 "symbol " + target->getName() + " is too narrow (only " +
704 Twine(sizeInBits) + " bits wide); this can fail at runtime " +
705 "depending on memory layout");
706 }
707 // sizeInBits is used to initialize the Flags field; currently no
708 // other flags are defined.
709 res.emplace_back(args&: target, args: this, args: rel.VirtualAddress, args&: sizeInBits);
710 }
711}
712
713bool SectionChunk::isCOMDAT() const {
714 return header->Characteristics & IMAGE_SCN_LNK_COMDAT;
715}
716
717void SectionChunk::printDiscardedMessage() const {
718 // Removed by dead-stripping. If it's removed by ICF, ICF already
719 // printed out the name, so don't repeat that here.
720 if (sym && this == repl)
721 log(msg: "Discarded " + sym->getName());
722}
723
724StringRef SectionChunk::getDebugName() const {
725 if (sym)
726 return sym->getName();
727 return "";
728}
729
730ArrayRef<uint8_t> SectionChunk::getContents() const {
731 ArrayRef<uint8_t> a;
732 cantFail(Err: file->getCOFFObj()->getSectionContents(Sec: header, Res&: a));
733 return a;
734}
735
736ArrayRef<uint8_t> SectionChunk::consumeDebugMagic() {
737 assert(isCodeView());
738 return consumeDebugMagic(data: getContents(), sectionName: getSectionName());
739}
740
741ArrayRef<uint8_t> SectionChunk::consumeDebugMagic(ArrayRef<uint8_t> data,
742 StringRef sectionName) {
743 if (data.empty())
744 return {};
745
746 // First 4 bytes are section magic.
747 if (data.size() < 4)
748 fatal(msg: "the section is too short: " + sectionName);
749
750 if (!sectionName.starts_with(Prefix: ".debug$"))
751 fatal(msg: "invalid section: " + sectionName);
752
753 uint32_t magic = support::endian::read32le(P: data.data());
754 uint32_t expectedMagic = sectionName == ".debug$H"
755 ? DEBUG_HASHES_SECTION_MAGIC
756 : DEBUG_SECTION_MAGIC;
757 if (magic != expectedMagic) {
758 warn(msg: "ignoring section " + sectionName + " with unrecognized magic 0x" +
759 utohexstr(X: magic));
760 return {};
761 }
762 return data.slice(N: 4);
763}
764
765SectionChunk *SectionChunk::findByName(ArrayRef<SectionChunk *> sections,
766 StringRef name) {
767 for (SectionChunk *c : sections)
768 if (c->getSectionName() == name)
769 return c;
770 return nullptr;
771}
772
773void SectionChunk::replace(SectionChunk *other) {
774 p2Align = std::max(a: p2Align, b: other->p2Align);
775 other->repl = repl;
776 other->live = false;
777}
778
779uint32_t SectionChunk::getSectionNumber() const {
780 DataRefImpl r;
781 r.p = reinterpret_cast<uintptr_t>(header);
782 SectionRef s(r, file->getCOFFObj());
783 return s.getIndex() + 1;
784}
785
786CommonChunk::CommonChunk(const COFFSymbolRef s) : sym(s) {
787 // The value of a common symbol is its size. Align all common symbols smaller
788 // than 32 bytes naturally, i.e. round the size up to the next power of two.
789 // This is what MSVC link.exe does.
790 setAlignment(std::min(a: 32U, b: uint32_t(PowerOf2Ceil(A: sym.getValue()))));
791 hasData = false;
792}
793
794uint32_t CommonChunk::getOutputCharacteristics() const {
795 return IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_MEM_READ |
796 IMAGE_SCN_MEM_WRITE;
797}
798
799void StringChunk::writeTo(uint8_t *buf) const {
800 memcpy(dest: buf, src: str.data(), n: str.size());
801 buf[str.size()] = '\0';
802}
803
804ImportThunkChunk::ImportThunkChunk(COFFLinkerContext &ctx, Defined *s)
805 : NonSectionCodeChunk(ImportThunkKind), live(!ctx.config.doGC),
806 impSymbol(s), ctx(ctx) {}
807
808ImportThunkChunkX64::ImportThunkChunkX64(COFFLinkerContext &ctx, Defined *s)
809 : ImportThunkChunk(ctx, s) {
810 // Intel Optimization Manual says that all branch targets
811 // should be 16-byte aligned. MSVC linker does this too.
812 setAlignment(16);
813}
814
815void ImportThunkChunkX64::writeTo(uint8_t *buf) const {
816 memcpy(dest: buf, src: importThunkX86, n: sizeof(importThunkX86));
817 // The first two bytes is a JMP instruction. Fill its operand.
818 write32le(P: buf + 2, V: impSymbol->getRVA() - rva - getSize());
819}
820
821void ImportThunkChunkX86::getBaserels(std::vector<Baserel> *res) {
822 res->emplace_back(args: getRVA() + 2, args&: ctx.config.machine);
823}
824
825void ImportThunkChunkX86::writeTo(uint8_t *buf) const {
826 memcpy(dest: buf, src: importThunkX86, n: sizeof(importThunkX86));
827 // The first two bytes is a JMP instruction. Fill its operand.
828 write32le(P: buf + 2, V: impSymbol->getRVA() + ctx.config.imageBase);
829}
830
831void ImportThunkChunkARM::getBaserels(std::vector<Baserel> *res) {
832 res->emplace_back(args: getRVA(), args: IMAGE_REL_BASED_ARM_MOV32T);
833}
834
835void ImportThunkChunkARM::writeTo(uint8_t *buf) const {
836 memcpy(dest: buf, src: importThunkARM, n: sizeof(importThunkARM));
837 // Fix mov.w and mov.t operands.
838 applyMOV32T(off: buf, v: impSymbol->getRVA() + ctx.config.imageBase);
839}
840
841void ImportThunkChunkARM64::writeTo(uint8_t *buf) const {
842 int64_t off = impSymbol->getRVA() & 0xfff;
843 memcpy(dest: buf, src: importThunkARM64, n: sizeof(importThunkARM64));
844 applyArm64Addr(off: buf, s: impSymbol->getRVA(), p: rva, shift: 12);
845 applyArm64Ldr(off: buf + 4, imm: off);
846}
847
848// A Thumb2, PIC, non-interworking range extension thunk.
849const uint8_t armThunk[] = {
850 0x40, 0xf2, 0x00, 0x0c, // P: movw ip,:lower16:S - (P + (L1-P) + 4)
851 0xc0, 0xf2, 0x00, 0x0c, // movt ip,:upper16:S - (P + (L1-P) + 4)
852 0xe7, 0x44, // L1: add pc, ip
853};
854
855size_t RangeExtensionThunkARM::getSize() const {
856 assert(ctx.config.machine == ARMNT);
857 (void)&ctx;
858 return sizeof(armThunk);
859}
860
861void RangeExtensionThunkARM::writeTo(uint8_t *buf) const {
862 assert(ctx.config.machine == ARMNT);
863 uint64_t offset = target->getRVA() - rva - 12;
864 memcpy(dest: buf, src: armThunk, n: sizeof(armThunk));
865 applyMOV32T(off: buf, v: uint32_t(offset));
866}
867
868// A position independent ARM64 adrp+add thunk, with a maximum range of
869// +/- 4 GB, which is enough for any PE-COFF.
870const uint8_t arm64Thunk[] = {
871 0x10, 0x00, 0x00, 0x90, // adrp x16, Dest
872 0x10, 0x02, 0x00, 0x91, // add x16, x16, :lo12:Dest
873 0x00, 0x02, 0x1f, 0xd6, // br x16
874};
875
876size_t RangeExtensionThunkARM64::getSize() const { return sizeof(arm64Thunk); }
877
878void RangeExtensionThunkARM64::writeTo(uint8_t *buf) const {
879 memcpy(dest: buf, src: arm64Thunk, n: sizeof(arm64Thunk));
880 applyArm64Addr(off: buf + 0, s: target->getRVA(), p: rva, shift: 12);
881 applyArm64Imm(off: buf + 4, imm: target->getRVA() & 0xfff, rangeLimit: 0);
882}
883
884LocalImportChunk::LocalImportChunk(COFFLinkerContext &c, Defined *s)
885 : sym(s), ctx(c) {
886 setAlignment(ctx.config.wordsize);
887}
888
889void LocalImportChunk::getBaserels(std::vector<Baserel> *res) {
890 res->emplace_back(args: getRVA(), args&: ctx.config.machine);
891}
892
893size_t LocalImportChunk::getSize() const { return ctx.config.wordsize; }
894
895void LocalImportChunk::writeTo(uint8_t *buf) const {
896 if (ctx.config.is64()) {
897 write64le(P: buf, V: sym->getRVA() + ctx.config.imageBase);
898 } else {
899 write32le(P: buf, V: sym->getRVA() + ctx.config.imageBase);
900 }
901}
902
903void RVATableChunk::writeTo(uint8_t *buf) const {
904 ulittle32_t *begin = reinterpret_cast<ulittle32_t *>(buf);
905 size_t cnt = 0;
906 for (const ChunkAndOffset &co : syms)
907 begin[cnt++] = co.inputChunk->getRVA() + co.offset;
908 llvm::sort(Start: begin, End: begin + cnt);
909 assert(std::unique(begin, begin + cnt) == begin + cnt &&
910 "RVA tables should be de-duplicated");
911}
912
913void RVAFlagTableChunk::writeTo(uint8_t *buf) const {
914 struct RVAFlag {
915 ulittle32_t rva;
916 uint8_t flag;
917 };
918 auto flags =
919 MutableArrayRef(reinterpret_cast<RVAFlag *>(buf), syms.size());
920 for (auto t : zip(t: syms, u&: flags)) {
921 const auto &sym = std::get<0>(t&: t);
922 auto &flag = std::get<1>(t&: t);
923 flag.rva = sym.inputChunk->getRVA() + sym.offset;
924 flag.flag = 0;
925 }
926 llvm::sort(C&: flags,
927 Comp: [](const RVAFlag &a, const RVAFlag &b) { return a.rva < b.rva; });
928 assert(llvm::unique(flags, [](const RVAFlag &a,
929 const RVAFlag &b) { return a.rva == b.rva; }) ==
930 flags.end() &&
931 "RVA tables should be de-duplicated");
932}
933
934size_t ECCodeMapChunk::getSize() const {
935 return map.size() * sizeof(chpe_range_entry);
936}
937
938void ECCodeMapChunk::writeTo(uint8_t *buf) const {
939 auto table = reinterpret_cast<chpe_range_entry *>(buf);
940 for (uint32_t i = 0; i < map.size(); i++) {
941 const ECCodeMapEntry &entry = map[i];
942 uint32_t start = entry.first->getRVA();
943 table[i].StartOffset = start | entry.type;
944 table[i].Length = entry.last->getRVA() + entry.last->getSize() - start;
945 }
946}
947
948// MinGW specific, for the "automatic import of variables from DLLs" feature.
949size_t PseudoRelocTableChunk::getSize() const {
950 if (relocs.empty())
951 return 0;
952 return 12 + 12 * relocs.size();
953}
954
955// MinGW specific.
956void PseudoRelocTableChunk::writeTo(uint8_t *buf) const {
957 if (relocs.empty())
958 return;
959
960 ulittle32_t *table = reinterpret_cast<ulittle32_t *>(buf);
961 // This is the list header, to signal the runtime pseudo relocation v2
962 // format.
963 table[0] = 0;
964 table[1] = 0;
965 table[2] = 1;
966
967 size_t idx = 3;
968 for (const RuntimePseudoReloc &rpr : relocs) {
969 table[idx + 0] = rpr.sym->getRVA();
970 table[idx + 1] = rpr.target->getRVA() + rpr.targetOffset;
971 table[idx + 2] = rpr.flags;
972 idx += 3;
973 }
974}
975
976// Windows-specific. This class represents a block in .reloc section.
977// The format is described here.
978//
979// On Windows, each DLL is linked against a fixed base address and
980// usually loaded to that address. However, if there's already another
981// DLL that overlaps, the loader has to relocate it. To do that, DLLs
982// contain .reloc sections which contain offsets that need to be fixed
983// up at runtime. If the loader finds that a DLL cannot be loaded to its
984// desired base address, it loads it to somewhere else, and add <actual
985// base address> - <desired base address> to each offset that is
986// specified by the .reloc section. In ELF terms, .reloc sections
987// contain relative relocations in REL format (as opposed to RELA.)
988//
989// This already significantly reduces the size of relocations compared
990// to ELF .rel.dyn, but Windows does more to reduce it (probably because
991// it was invented for PCs in the late '80s or early '90s.) Offsets in
992// .reloc are grouped by page where the page size is 12 bits, and
993// offsets sharing the same page address are stored consecutively to
994// represent them with less space. This is very similar to the page
995// table which is grouped by (multiple stages of) pages.
996//
997// For example, let's say we have 0x00030, 0x00500, 0x00700, 0x00A00,
998// 0x20004, and 0x20008 in a .reloc section for x64. The uppermost 4
999// bits have a type IMAGE_REL_BASED_DIR64 or 0xA. In the section, they
1000// are represented like this:
1001//
1002// 0x00000 -- page address (4 bytes)
1003// 16 -- size of this block (4 bytes)
1004// 0xA030 -- entries (2 bytes each)
1005// 0xA500
1006// 0xA700
1007// 0xAA00
1008// 0x20000 -- page address (4 bytes)
1009// 12 -- size of this block (4 bytes)
1010// 0xA004 -- entries (2 bytes each)
1011// 0xA008
1012//
1013// Usually we have a lot of relocations for each page, so the number of
1014// bytes for one .reloc entry is close to 2 bytes on average.
1015BaserelChunk::BaserelChunk(uint32_t page, Baserel *begin, Baserel *end) {
1016 // Block header consists of 4 byte page RVA and 4 byte block size.
1017 // Each entry is 2 byte. Last entry may be padding.
1018 data.resize(new_size: alignTo(Value: (end - begin) * 2 + 8, Align: 4));
1019 uint8_t *p = data.data();
1020 write32le(P: p, V: page);
1021 write32le(P: p + 4, V: data.size());
1022 p += 8;
1023 for (Baserel *i = begin; i != end; ++i) {
1024 write16le(P: p, V: (i->type << 12) | (i->rva - page));
1025 p += 2;
1026 }
1027}
1028
1029void BaserelChunk::writeTo(uint8_t *buf) const {
1030 memcpy(dest: buf, src: data.data(), n: data.size());
1031}
1032
1033uint8_t Baserel::getDefaultType(llvm::COFF::MachineTypes machine) {
1034 return is64Bit(Machine: machine) ? IMAGE_REL_BASED_DIR64 : IMAGE_REL_BASED_HIGHLOW;
1035}
1036
1037MergeChunk::MergeChunk(uint32_t alignment)
1038 : builder(StringTableBuilder::RAW, llvm::Align(alignment)) {
1039 setAlignment(alignment);
1040}
1041
1042void MergeChunk::addSection(COFFLinkerContext &ctx, SectionChunk *c) {
1043 assert(isPowerOf2_32(c->getAlignment()));
1044 uint8_t p2Align = llvm::Log2_32(Value: c->getAlignment());
1045 assert(p2Align < std::size(ctx.mergeChunkInstances));
1046 auto *&mc = ctx.mergeChunkInstances[p2Align];
1047 if (!mc)
1048 mc = make<MergeChunk>(args: c->getAlignment());
1049 mc->sections.push_back(x: c);
1050}
1051
1052void MergeChunk::finalizeContents() {
1053 assert(!finalized && "should only finalize once");
1054 for (SectionChunk *c : sections)
1055 if (c->live)
1056 builder.add(S: toStringRef(Input: c->getContents()));
1057 builder.finalize();
1058 finalized = true;
1059}
1060
1061void MergeChunk::assignSubsectionRVAs() {
1062 for (SectionChunk *c : sections) {
1063 if (!c->live)
1064 continue;
1065 size_t off = builder.getOffset(S: toStringRef(Input: c->getContents()));
1066 c->setRVA(rva + off);
1067 }
1068}
1069
1070uint32_t MergeChunk::getOutputCharacteristics() const {
1071 return IMAGE_SCN_MEM_READ | IMAGE_SCN_CNT_INITIALIZED_DATA;
1072}
1073
1074size_t MergeChunk::getSize() const {
1075 return builder.getSize();
1076}
1077
1078void MergeChunk::writeTo(uint8_t *buf) const {
1079 builder.write(Buf: buf);
1080}
1081
1082// MinGW specific.
1083size_t AbsolutePointerChunk::getSize() const {
1084 return symtab.ctx.config.wordsize;
1085}
1086
1087void AbsolutePointerChunk::writeTo(uint8_t *buf) const {
1088 if (symtab.ctx.config.is64()) {
1089 write64le(P: buf, V: value);
1090 } else {
1091 write32le(P: buf, V: value);
1092 }
1093}
1094
1095MachineTypes AbsolutePointerChunk::getMachine() const { return symtab.machine; }
1096
1097void ECExportThunkChunk::writeTo(uint8_t *buf) const {
1098 memcpy(dest: buf, src: ECExportThunkCode, n: sizeof(ECExportThunkCode));
1099 write32le(P: buf + 10, V: target->getRVA() - rva - 14);
1100}
1101
1102size_t CHPECodeRangesChunk::getSize() const {
1103 return exportThunks.size() * sizeof(chpe_code_range_entry);
1104}
1105
1106void CHPECodeRangesChunk::writeTo(uint8_t *buf) const {
1107 auto ranges = reinterpret_cast<chpe_code_range_entry *>(buf);
1108
1109 for (uint32_t i = 0; i < exportThunks.size(); i++) {
1110 Chunk *thunk = exportThunks[i].first;
1111 uint32_t start = thunk->getRVA();
1112 ranges[i].StartRva = start;
1113 ranges[i].EndRva = start + thunk->getSize();
1114 ranges[i].EntryPoint = start;
1115 }
1116}
1117
1118size_t CHPERedirectionChunk::getSize() const {
1119 // Add an extra +1 for a terminator entry.
1120 return (exportThunks.size() + 1) * sizeof(chpe_redirection_entry);
1121}
1122
1123void CHPERedirectionChunk::writeTo(uint8_t *buf) const {
1124 auto entries = reinterpret_cast<chpe_redirection_entry *>(buf);
1125
1126 for (uint32_t i = 0; i < exportThunks.size(); i++) {
1127 entries[i].Source = exportThunks[i].first->getRVA();
1128 entries[i].Destination = exportThunks[i].second->getRVA();
1129 }
1130}
1131
1132ImportThunkChunkARM64EC::ImportThunkChunkARM64EC(ImportFile *file)
1133 : ImportThunkChunk(file->symtab.ctx, file->impSym), file(file) {}
1134
1135size_t ImportThunkChunkARM64EC::getSize() const {
1136 if (!extended)
1137 return sizeof(importThunkARM64EC);
1138 // The last instruction is replaced with an inline range extension thunk.
1139 return sizeof(importThunkARM64EC) + sizeof(arm64Thunk) - sizeof(uint32_t);
1140}
1141
1142void ImportThunkChunkARM64EC::writeTo(uint8_t *buf) const {
1143 memcpy(dest: buf, src: importThunkARM64EC, n: sizeof(importThunkARM64EC));
1144 applyArm64Addr(off: buf, s: file->impSym->getRVA(), p: rva, shift: 12);
1145 applyArm64Ldr(off: buf + 4, imm: file->impSym->getRVA() & 0xfff);
1146
1147 // The exit thunk may be missing. This can happen if the application only
1148 // references a function by its address (in which case the thunk is never
1149 // actually used, but is still required to fill the auxiliary IAT), or in
1150 // cases of hand-written assembly calling an imported ARM64EC function (where
1151 // the exit thunk is ignored by __icall_helper_arm64ec). In such cases, MSVC
1152 // link.exe uses 0 as the RVA.
1153 uint32_t exitThunkRVA = exitThunk ? exitThunk->getRVA() : 0;
1154 applyArm64Addr(off: buf + 8, s: exitThunkRVA, p: rva + 8, shift: 12);
1155 applyArm64Imm(off: buf + 12, imm: exitThunkRVA & 0xfff, rangeLimit: 0);
1156
1157 Defined *helper = cast<Defined>(Val: file->symtab.ctx.config.arm64ECIcallHelper);
1158 if (extended) {
1159 // Replace last instruction with an inline range extension thunk.
1160 memcpy(dest: buf + 16, src: arm64Thunk, n: sizeof(arm64Thunk));
1161 applyArm64Addr(off: buf + 16, s: helper->getRVA(), p: rva + 16, shift: 12);
1162 applyArm64Imm(off: buf + 20, imm: helper->getRVA() & 0xfff, rangeLimit: 0);
1163 } else {
1164 applyArm64Branch26(off: buf + 16, v: helper->getRVA() - rva - 16);
1165 }
1166}
1167
1168bool ImportThunkChunkARM64EC::verifyRanges() {
1169 if (extended)
1170 return true;
1171 auto helper = cast<Defined>(Val: file->symtab.ctx.config.arm64ECIcallHelper);
1172 return isInt<28>(x: helper->getRVA() - rva - 16);
1173}
1174
1175uint32_t ImportThunkChunkARM64EC::extendRanges() {
1176 if (extended || verifyRanges())
1177 return 0;
1178 extended = true;
1179 // The last instruction is replaced with an inline range extension thunk.
1180 return sizeof(arm64Thunk) - sizeof(uint32_t);
1181}
1182
1183uint64_t Arm64XRelocVal::get() const {
1184 return (sym ? sym->getRVA() : 0) + (chunk ? chunk->getRVA() : 0) + value;
1185}
1186
1187size_t Arm64XDynamicRelocEntry::getSize() const {
1188 switch (type) {
1189 case IMAGE_DVRT_ARM64X_FIXUP_TYPE_ZEROFILL:
1190 return sizeof(uint16_t); // Just a header.
1191 case IMAGE_DVRT_ARM64X_FIXUP_TYPE_VALUE:
1192 return sizeof(uint16_t) + size; // A header and a payload.
1193 case IMAGE_DVRT_ARM64X_FIXUP_TYPE_DELTA:
1194 return 2 * sizeof(uint16_t); // A header and a delta.
1195 }
1196 llvm_unreachable("invalid type");
1197}
1198
1199void Arm64XDynamicRelocEntry::writeTo(uint8_t *buf) const {
1200 auto out = reinterpret_cast<ulittle16_t *>(buf);
1201 *out = (offset.get() & 0xfff) | (type << 12);
1202
1203 switch (type) {
1204 case IMAGE_DVRT_ARM64X_FIXUP_TYPE_ZEROFILL:
1205 *out |= ((bit_width(Value: size) - 1) << 14); // Encode the size.
1206 break;
1207 case IMAGE_DVRT_ARM64X_FIXUP_TYPE_VALUE:
1208 *out |= ((bit_width(Value: size) - 1) << 14); // Encode the size.
1209 switch (size) {
1210 case 2:
1211 out[1] = value.get();
1212 break;
1213 case 4:
1214 *reinterpret_cast<ulittle32_t *>(out + 1) = value.get();
1215 break;
1216 case 8:
1217 *reinterpret_cast<ulittle64_t *>(out + 1) = value.get();
1218 break;
1219 default:
1220 llvm_unreachable("invalid size");
1221 }
1222 break;
1223 case IMAGE_DVRT_ARM64X_FIXUP_TYPE_DELTA:
1224 int delta = value.get();
1225 // Negative offsets use a sign bit in the header.
1226 if (delta < 0) {
1227 *out |= 1 << 14;
1228 delta = -delta;
1229 }
1230 // Depending on the value, the delta is encoded with a shift of 2 or 3 bits.
1231 if (delta & 7) {
1232 assert(!(delta & 3));
1233 delta >>= 2;
1234 } else {
1235 *out |= (1 << 15);
1236 delta >>= 3;
1237 }
1238 out[1] = delta;
1239 assert(!(delta & ~0xffff));
1240 break;
1241 }
1242}
1243
1244void DynamicRelocsChunk::finalize() {
1245 llvm::stable_sort(Range&: arm64xRelocs, C: [=](const Arm64XDynamicRelocEntry &a,
1246 const Arm64XDynamicRelocEntry &b) {
1247 return a.offset.get() < b.offset.get();
1248 });
1249
1250 size = sizeof(coff_dynamic_reloc_table) + sizeof(coff_dynamic_relocation64);
1251 uint32_t prevPage = 0xfff;
1252
1253 for (const Arm64XDynamicRelocEntry &entry : arm64xRelocs) {
1254 uint32_t page = entry.offset.get() & ~0xfff;
1255 if (page != prevPage) {
1256 size = alignTo(Value: size, Align: sizeof(uint32_t)) +
1257 sizeof(coff_base_reloc_block_header);
1258 prevPage = page;
1259 }
1260 size += entry.getSize();
1261 }
1262
1263 size = alignTo(Value: size, Align: sizeof(uint32_t));
1264}
1265
1266// Set the reloc value. The reloc entry must be allocated beforehand.
1267void DynamicRelocsChunk::set(uint32_t rva, Arm64XRelocVal value) {
1268 auto entry =
1269 llvm::find_if(Range&: arm64xRelocs, P: [rva](const Arm64XDynamicRelocEntry &e) {
1270 return e.offset.get() == rva;
1271 });
1272 assert(entry != arm64xRelocs.end());
1273 assert(!entry->value.get());
1274 entry->value = value;
1275}
1276
1277void DynamicRelocsChunk::writeTo(uint8_t *buf) const {
1278 auto table = reinterpret_cast<coff_dynamic_reloc_table *>(buf);
1279 table->Version = 1;
1280 table->Size = sizeof(coff_dynamic_relocation64);
1281 buf += sizeof(*table);
1282
1283 auto header = reinterpret_cast<coff_dynamic_relocation64 *>(buf);
1284 header->Symbol = IMAGE_DYNAMIC_RELOCATION_ARM64X;
1285 buf += sizeof(*header);
1286
1287 coff_base_reloc_block_header *pageHeader = nullptr;
1288 size_t relocSize = 0;
1289 for (const Arm64XDynamicRelocEntry &entry : arm64xRelocs) {
1290 uint32_t page = entry.offset.get() & ~0xfff;
1291 if (!pageHeader || page != pageHeader->PageRVA) {
1292 relocSize = alignTo(Value: relocSize, Align: sizeof(uint32_t));
1293 if (pageHeader)
1294 pageHeader->BlockSize =
1295 buf + relocSize - reinterpret_cast<uint8_t *>(pageHeader);
1296 pageHeader =
1297 reinterpret_cast<coff_base_reloc_block_header *>(buf + relocSize);
1298 pageHeader->PageRVA = page;
1299 relocSize += sizeof(*pageHeader);
1300 }
1301
1302 entry.writeTo(buf: buf + relocSize);
1303 relocSize += entry.getSize();
1304 }
1305 relocSize = alignTo(Value: relocSize, Align: sizeof(uint32_t));
1306 pageHeader->BlockSize =
1307 buf + relocSize - reinterpret_cast<uint8_t *>(pageHeader);
1308
1309 header->BaseRelocSize = relocSize;
1310 table->Size += relocSize;
1311 assert(size == sizeof(*table) + sizeof(*header) + relocSize);
1312}
1313
1314} // namespace lld::coff
1315