1//===- Relocations.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 "Relocations.h"
10#include "ConcatOutputSection.h"
11#include "Symbols.h"
12#include "SyntheticSections.h"
13#include "Target.h"
14
15#include "lld/Common/ErrorHandler.h"
16
17using namespace llvm;
18using namespace lld;
19using namespace lld::macho;
20
21static_assert(sizeof(void *) != 8 || sizeof(Reloc) == 24,
22 "Try to minimize Reloc's size; we create many instances");
23
24InputSection *Reloc::getReferentInputSection() const {
25 if (const auto *sym = referent.dyn_cast<Symbol *>()) {
26 if (const auto *d = dyn_cast<Defined>(Val: sym))
27 return d->isec();
28 return nullptr;
29 } else {
30 return referent.get<InputSection *>();
31 }
32}
33
34bool macho::validateSymbolRelocation(const Symbol *sym,
35 const InputSection *isec, const Reloc &r) {
36 const RelocAttrs &relocAttrs = target->getRelocAttrs(type: r.type);
37 bool valid = true;
38 auto message = [&](const Twine &diagnostic) {
39 valid = false;
40 return (isec->getLocation(off: r.offset) + ": " + relocAttrs.name +
41 " relocation " + diagnostic)
42 .str();
43 };
44
45 if (relocAttrs.hasAttr(b: RelocAttrBits::TLV) != sym->isTlv())
46 error(msg: message(Twine("requires that symbol ") + sym->getName() + " " +
47 (sym->isTlv() ? "not " : "") + "be thread-local"));
48
49 return valid;
50}
51
52// Given an offset in the output buffer, figure out which ConcatInputSection (if
53// any) maps to it. At the same time, update the offset such that it is relative
54// to the InputSection rather than to the output buffer.
55//
56// Obtaining the InputSection allows us to have better error diagnostics.
57// However, many of our relocation-handling methods do not take the InputSection
58// as a parameter. Since we are already passing the buffer offsets to our Target
59// methods, this function allows us to emit better errors without threading an
60// additional InputSection argument through the call stack.
61//
62// This is implemented as a slow linear search through OutputSegments,
63// OutputSections, and finally the InputSections themselves. However, this
64// function should be called only on error paths, so some overhead is fine.
65InputSection *macho::offsetToInputSection(uint64_t *off) {
66 for (OutputSegment *seg : outputSegments) {
67 if (*off < seg->fileOff || *off >= seg->fileOff + seg->fileSize)
68 continue;
69
70 const std::vector<OutputSection *> &sections = seg->getSections();
71 size_t osecIdx = 0;
72 for (; osecIdx < sections.size(); ++osecIdx)
73 if (*off < sections[osecIdx]->fileOff)
74 break;
75 assert(osecIdx > 0);
76 // We should be only calling this function on offsets that belong to
77 // ConcatOutputSections.
78 auto *osec = cast<ConcatOutputSection>(Val: sections[osecIdx - 1]);
79 *off -= osec->fileOff;
80
81 size_t isecIdx = 0;
82 for (; isecIdx < osec->inputs.size(); ++isecIdx) {
83 const ConcatInputSection *isec = osec->inputs[isecIdx];
84 if (*off < isec->outSecOff)
85 break;
86 }
87 assert(isecIdx > 0);
88 ConcatInputSection *isec = osec->inputs[isecIdx - 1];
89 *off -= isec->outSecOff;
90 return isec;
91 }
92 return nullptr;
93}
94
95void macho::reportRangeError(void *loc, const Reloc &r, const Twine &v,
96 uint8_t bits, int64_t min, uint64_t max) {
97 std::string hint;
98 uint64_t off = reinterpret_cast<const uint8_t *>(loc) - in.bufferStart;
99 const InputSection *isec = offsetToInputSection(off: &off);
100 std::string locStr = isec ? isec->getLocation(off) : "(invalid location)";
101 if (auto *sym = r.referent.dyn_cast<Symbol *>())
102 hint = "; references " + toString(*sym);
103 error(msg: locStr + ": relocation " + target->getRelocAttrs(type: r.type).name +
104 " is out of range: " + v + " is not in [" + Twine(min) + ", " +
105 Twine(max) + "]" + hint);
106}
107
108void macho::reportRangeError(void *loc, SymbolDiagnostic d, const Twine &v,
109 uint8_t bits, int64_t min, uint64_t max) {
110 // FIXME: should we use `loc` somehow to provide a better error message?
111 std::string hint;
112 if (d.symbol)
113 hint = "; references " + toString(*d.symbol);
114 error(msg: d.reason + " is out of range: " + v + " is not in [" + Twine(min) +
115 ", " + Twine(max) + "]" + hint);
116}
117
118const RelocAttrs macho::invalidRelocAttrs{.name: "INVALID", .bits: RelocAttrBits::_0};
119

source code of lld/MachO/Relocations.cpp