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//===- Relocations.cpp ----------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Relocations.h"
#include "ConcatOutputSection.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "Target.h"
#include "lld/Common/ErrorHandler.h"
using namespace llvm;
using namespace lld;
using namespace lld::macho;
static_assert(sizeof(void *) != 8 || sizeof(Reloc) == 24,
"Try to minimize Reloc's size; we create many instances");
InputSection *Reloc::getReferentInputSection() const {
if (const auto *sym = referent.dyn_cast<Symbol *>()) {
if (const auto *d = dyn_cast<Defined>(sym))
return d->isec();
return nullptr;
} else {
return cast<InputSection *>(referent);
}
}
StringRef Reloc::getReferentString() const {
if (auto *isec = dyn_cast<InputSection *>(referent)) {
const auto *cisec = dyn_cast<CStringInputSection>(isec);
assert(cisec && "referent must be a CStringInputSection");
return cisec->getStringRefAtOffset(addend);
}
auto *sym = dyn_cast<Defined>(cast<Symbol *>(referent));
assert(sym && "referent must be a Defined symbol");
auto *symIsec = sym->isec();
auto symOffset = sym->value + addend;
if (auto *s = dyn_cast_or_null<CStringInputSection>(symIsec))
return s->getStringRefAtOffset(symOffset);
if (isa<ConcatInputSection>(symIsec)) {
auto strData = symIsec->data.slice(symOffset);
const char *pszData = reinterpret_cast<const char *>(strData.data());
return StringRef(pszData, strnlen(pszData, strData.size()));
}
llvm_unreachable("unknown reference section in getReferentString");
}
bool macho::validateSymbolRelocation(const Symbol *sym,
const InputSection *isec, const Reloc &r) {
const RelocAttrs &relocAttrs = target->getRelocAttrs(r.type);
bool valid = true;
auto message = [&](const Twine &diagnostic) {
valid = false;
return (isec->getLocation(r.offset) + ": " + relocAttrs.name +
" relocation " + diagnostic)
.str();
};
if (relocAttrs.hasAttr(RelocAttrBits::TLV) != sym->isTlv())
error(message(Twine("requires that symbol ") + sym->getName() + " " +
(sym->isTlv() ? "not " : "") + "be thread-local"));
return valid;
}
// Given an offset in the output buffer, figure out which ConcatInputSection (if
// any) maps to it. At the same time, update the offset such that it is relative
// to the InputSection rather than to the output buffer.
//
// Obtaining the InputSection allows us to have better error diagnostics.
// However, many of our relocation-handling methods do not take the InputSection
// as a parameter. Since we are already passing the buffer offsets to our Target
// methods, this function allows us to emit better errors without threading an
// additional InputSection argument through the call stack.
//
// This is implemented as a slow linear search through OutputSegments,
// OutputSections, and finally the InputSections themselves. However, this
// function should be called only on error paths, so some overhead is fine.
InputSection *macho::offsetToInputSection(uint64_t *off) {
for (OutputSegment *seg : outputSegments) {
if (*off < seg->fileOff || *off >= seg->fileOff + seg->fileSize)
continue;
const std::vector<OutputSection *> §ions = seg->getSections();
size_t osecIdx = 0;
for (; osecIdx < sections.size(); ++osecIdx)
if (*off < sections[osecIdx]->fileOff)
break;
assert(osecIdx > 0);
// We should be only calling this function on offsets that belong to
// ConcatOutputSections.
auto *osec = cast<ConcatOutputSection>(sections[osecIdx - 1]);
*off -= osec->fileOff;
size_t isecIdx = 0;
for (; isecIdx < osec->inputs.size(); ++isecIdx) {
const ConcatInputSection *isec = osec->inputs[isecIdx];
if (*off < isec->outSecOff)
break;
}
assert(isecIdx > 0);
ConcatInputSection *isec = osec->inputs[isecIdx - 1];
*off -= isec->outSecOff;
return isec;
}
return nullptr;
}
void macho::reportRangeError(void *loc, const Reloc &r, const Twine &v,
uint8_t bits, int64_t min, uint64_t max) {
std::string hint;
uint64_t off = reinterpret_cast<const uint8_t *>(loc) - in.bufferStart;
const InputSection *isec = offsetToInputSection(&off);
std::string locStr = isec ? isec->getLocation(off) : "(invalid location)";
if (auto *sym = r.referent.dyn_cast<Symbol *>())
hint = "; references " + toString(*sym);
error(locStr + ": relocation " + target->getRelocAttrs(r.type).name +
" is out of range: " + v + " is not in [" + Twine(min) + ", " +
Twine(max) + "]" + hint);
}
void macho::reportRangeError(void *loc, SymbolDiagnostic d, const Twine &v,
uint8_t bits, int64_t min, uint64_t max) {
// FIXME: should we use `loc` somehow to provide a better error message?
std::string hint;
if (d.symbol)
hint = "; references " + toString(*d.symbol);
error(d.reason + " is out of range: " + v + " is not in [" + Twine(min) +
", " + Twine(max) + "]" + hint);
}
const RelocAttrs macho::invalidRelocAttrs{"INVALID", RelocAttrBits::_0};
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