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