1 //===----- ELF_aarch32.cpp - JIT linker implementation for arm/thumb ------===//
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 // ELF/aarch32 jit-link implementation.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/ExecutionEngine/JITLink/ELF_aarch32.h"
14
15 #include "llvm/BinaryFormat/ELF.h"
16 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
17 #include "llvm/ExecutionEngine/JITLink/aarch32.h"
18 #include "llvm/Object/ELF.h"
19 #include "llvm/Object/ELFObjectFile.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/TargetParser/ARMTargetParser.h"
22
23 #include "ELFLinkGraphBuilder.h"
24 #include "JITLinkGeneric.h"
25
26 #define DEBUG_TYPE "jitlink"
27
28 using namespace llvm::object;
29
30 namespace llvm {
31 namespace jitlink {
32
33 /// Translate from ELF relocation type to JITLink-internal edge kind.
34 Expected<aarch32::EdgeKind_aarch32>
getJITLinkEdgeKind(uint32_t ELFType,const aarch32::ArmConfig & ArmCfg)35 getJITLinkEdgeKind(uint32_t ELFType, const aarch32::ArmConfig &ArmCfg) {
36 switch (ELFType) {
37 case ELF::R_ARM_ABS32:
38 return aarch32::Data_Pointer32;
39 case ELF::R_ARM_GOT_PREL:
40 return aarch32::Data_RequestGOTAndTransformToDelta32;
41 case ELF::R_ARM_REL32:
42 return aarch32::Data_Delta32;
43 case ELF::R_ARM_CALL:
44 return aarch32::Arm_Call;
45 case ELF::R_ARM_JUMP24:
46 return aarch32::Arm_Jump24;
47 case ELF::R_ARM_MOVW_ABS_NC:
48 return aarch32::Arm_MovwAbsNC;
49 case ELF::R_ARM_MOVT_ABS:
50 return aarch32::Arm_MovtAbs;
51 case ELF::R_ARM_NONE:
52 return aarch32::None;
53 case ELF::R_ARM_PREL31:
54 return aarch32::Data_PRel31;
55 case ELF::R_ARM_TARGET1:
56 return (ArmCfg.Target1Rel) ? aarch32::Data_Delta32
57 : aarch32::Data_Pointer32;
58 case ELF::R_ARM_THM_CALL:
59 return aarch32::Thumb_Call;
60 case ELF::R_ARM_THM_JUMP24:
61 return aarch32::Thumb_Jump24;
62 case ELF::R_ARM_THM_MOVW_ABS_NC:
63 return aarch32::Thumb_MovwAbsNC;
64 case ELF::R_ARM_THM_MOVT_ABS:
65 return aarch32::Thumb_MovtAbs;
66 case ELF::R_ARM_THM_MOVW_PREL_NC:
67 return aarch32::Thumb_MovwPrelNC;
68 case ELF::R_ARM_THM_MOVT_PREL:
69 return aarch32::Thumb_MovtPrel;
70 }
71
72 return make_error<JITLinkError>(
73 "Unsupported aarch32 relocation " + formatv("{0:d}: ", ELFType) +
74 object::getELFRelocationTypeName(ELF::EM_ARM, ELFType));
75 }
76
77 /// Translate from JITLink-internal edge kind back to ELF relocation type.
getELFRelocationType(Edge::Kind Kind)78 Expected<uint32_t> getELFRelocationType(Edge::Kind Kind) {
79 switch (static_cast<aarch32::EdgeKind_aarch32>(Kind)) {
80 case aarch32::Data_Delta32:
81 return ELF::R_ARM_REL32;
82 case aarch32::Data_Pointer32:
83 return ELF::R_ARM_ABS32;
84 case aarch32::Data_PRel31:
85 return ELF::R_ARM_PREL31;
86 case aarch32::Data_RequestGOTAndTransformToDelta32:
87 return ELF::R_ARM_GOT_PREL;
88 case aarch32::Arm_Call:
89 return ELF::R_ARM_CALL;
90 case aarch32::Arm_Jump24:
91 return ELF::R_ARM_JUMP24;
92 case aarch32::Arm_MovwAbsNC:
93 return ELF::R_ARM_MOVW_ABS_NC;
94 case aarch32::Arm_MovtAbs:
95 return ELF::R_ARM_MOVT_ABS;
96 case aarch32::Thumb_Call:
97 return ELF::R_ARM_THM_CALL;
98 case aarch32::Thumb_Jump24:
99 return ELF::R_ARM_THM_JUMP24;
100 case aarch32::Thumb_MovwAbsNC:
101 return ELF::R_ARM_THM_MOVW_ABS_NC;
102 case aarch32::Thumb_MovtAbs:
103 return ELF::R_ARM_THM_MOVT_ABS;
104 case aarch32::Thumb_MovwPrelNC:
105 return ELF::R_ARM_THM_MOVW_PREL_NC;
106 case aarch32::Thumb_MovtPrel:
107 return ELF::R_ARM_THM_MOVT_PREL;
108 case aarch32::None:
109 return ELF::R_ARM_NONE;
110 }
111
112 return make_error<JITLinkError>(formatv("Invalid aarch32 edge {0:d}: ",
113 Kind));
114 }
115
116 /// Get a human-readable name for the given ELF AArch32 edge kind.
getELFAArch32EdgeKindName(Edge::Kind R)117 const char *getELFAArch32EdgeKindName(Edge::Kind R) {
118 // No ELF-specific edge kinds yet
119 return aarch32::getEdgeKindName(R);
120 }
121
122 class ELFJITLinker_aarch32 : public JITLinker<ELFJITLinker_aarch32> {
123 friend class JITLinker<ELFJITLinker_aarch32>;
124
125 public:
ELFJITLinker_aarch32(std::unique_ptr<JITLinkContext> Ctx,std::unique_ptr<LinkGraph> G,PassConfiguration PassCfg,aarch32::ArmConfig ArmCfg)126 ELFJITLinker_aarch32(std::unique_ptr<JITLinkContext> Ctx,
127 std::unique_ptr<LinkGraph> G, PassConfiguration PassCfg,
128 aarch32::ArmConfig ArmCfg)
129 : JITLinker(std::move(Ctx), std::move(G), std::move(PassCfg)),
130 ArmCfg(std::move(ArmCfg)) {}
131
132 private:
133 aarch32::ArmConfig ArmCfg;
134
applyFixup(LinkGraph & G,Block & B,const Edge & E) const135 Error applyFixup(LinkGraph &G, Block &B, const Edge &E) const {
136 return aarch32::applyFixup(G, B, E, ArmCfg);
137 }
138 };
139
140 template <llvm::endianness DataEndianness>
141 class ELFLinkGraphBuilder_aarch32
142 : public ELFLinkGraphBuilder<ELFType<DataEndianness, false>> {
143 private:
144 using ELFT = ELFType<DataEndianness, false>;
145 using Base = ELFLinkGraphBuilder<ELFT>;
146
addRelocations()147 Error addRelocations() override {
148 LLVM_DEBUG(dbgs() << "Processing relocations:\n");
149 using Self = ELFLinkGraphBuilder_aarch32<DataEndianness>;
150 for (const auto &RelSect : Base::Sections) {
151 if (Error Err = Base::forEachRelRelocation(RelSect, this,
152 &Self::addSingleRelRelocation))
153 return Err;
154 }
155 return Error::success();
156 }
157
addSingleRelRelocation(const typename ELFT::Rel & Rel,const typename ELFT::Shdr & FixupSect,Block & BlockToFix)158 Error addSingleRelRelocation(const typename ELFT::Rel &Rel,
159 const typename ELFT::Shdr &FixupSect,
160 Block &BlockToFix) {
161 uint32_t SymbolIndex = Rel.getSymbol(false);
162 auto ObjSymbol = Base::Obj.getRelocationSymbol(Rel, Base::SymTabSec);
163 if (!ObjSymbol)
164 return ObjSymbol.takeError();
165
166 Symbol *GraphSymbol = Base::getGraphSymbol(SymbolIndex);
167 if (!GraphSymbol)
168 return make_error<StringError>(
169 formatv("Could not find symbol at given index, did you add it to "
170 "JITSymbolTable? index: {0}, shndx: {1} Size of table: {2}",
171 SymbolIndex, (*ObjSymbol)->st_shndx,
172 Base::GraphSymbols.size()),
173 inconvertibleErrorCode());
174
175 uint32_t Type = Rel.getType(false);
176 Expected<aarch32::EdgeKind_aarch32> Kind = getJITLinkEdgeKind(Type, ArmCfg);
177 if (!Kind)
178 return Kind.takeError();
179
180 auto FixupAddress = orc::ExecutorAddr(FixupSect.sh_addr) + Rel.r_offset;
181 Edge::OffsetT Offset = FixupAddress - BlockToFix.getAddress();
182
183 Expected<int64_t> Addend =
184 aarch32::readAddend(*Base::G, BlockToFix, Offset, *Kind, ArmCfg);
185 if (!Addend)
186 return Addend.takeError();
187
188 Edge E(*Kind, Offset, *GraphSymbol, *Addend);
189 LLVM_DEBUG({
190 dbgs() << " ";
191 printEdge(dbgs(), BlockToFix, E, getELFAArch32EdgeKindName(*Kind));
192 dbgs() << "\n";
193 });
194
195 BlockToFix.addEdge(std::move(E));
196 return Error::success();
197 }
198
199 aarch32::ArmConfig ArmCfg;
200
201 protected:
makeTargetFlags(const typename ELFT::Sym & Sym)202 TargetFlagsType makeTargetFlags(const typename ELFT::Sym &Sym) override {
203 // Only emit target flag for callable symbols
204 if (Sym.getType() != ELF::STT_FUNC)
205 return TargetFlagsType{};
206 if (Sym.getValue() & 0x01)
207 return aarch32::ThumbSymbol;
208 return TargetFlagsType{};
209 }
210
getRawOffset(const typename ELFT::Sym & Sym,TargetFlagsType Flags)211 orc::ExecutorAddrDiff getRawOffset(const typename ELFT::Sym &Sym,
212 TargetFlagsType Flags) override {
213 assert((makeTargetFlags(Sym) & Flags) == Flags);
214 static constexpr uint64_t ThumbBit = 0x01;
215 if (Sym.getType() == ELF::STT_FUNC)
216 return Sym.getValue() & ~ThumbBit;
217 return Sym.getValue();
218 }
219
220 public:
ELFLinkGraphBuilder_aarch32(StringRef FileName,const llvm::object::ELFFile<ELFT> & Obj,Triple TT,SubtargetFeatures Features,aarch32::ArmConfig ArmCfg)221 ELFLinkGraphBuilder_aarch32(StringRef FileName,
222 const llvm::object::ELFFile<ELFT> &Obj, Triple TT,
223 SubtargetFeatures Features,
224 aarch32::ArmConfig ArmCfg)
225 : ELFLinkGraphBuilder<ELFT>(Obj, std::move(TT), std::move(Features),
226 FileName, getELFAArch32EdgeKindName),
227 ArmCfg(std::move(ArmCfg)) {}
228 };
229
230 template <typename StubsManagerType>
buildTables_ELF_aarch32(LinkGraph & G)231 Error buildTables_ELF_aarch32(LinkGraph &G) {
232 LLVM_DEBUG(dbgs() << "Visiting edges in graph:\n");
233
234 StubsManagerType StubsManager;
235 visitExistingEdges(G, StubsManager);
236 aarch32::GOTBuilder GOT;
237 visitExistingEdges(G, GOT);
238
239 return Error::success();
240 }
241
242 Expected<std::unique_ptr<LinkGraph>>
createLinkGraphFromELFObject_aarch32(MemoryBufferRef ObjectBuffer)243 createLinkGraphFromELFObject_aarch32(MemoryBufferRef ObjectBuffer) {
244 LLVM_DEBUG({
245 dbgs() << "Building jitlink graph for new input "
246 << ObjectBuffer.getBufferIdentifier() << "...\n";
247 });
248
249 auto ELFObj = ObjectFile::createELFObjectFile(ObjectBuffer);
250 if (!ELFObj)
251 return ELFObj.takeError();
252
253 auto Features = (*ELFObj)->getFeatures();
254 if (!Features)
255 return Features.takeError();
256
257 // Find out what exact AArch32 instruction set and features we target.
258 auto TT = (*ELFObj)->makeTriple();
259 ARM::ArchKind AK = ARM::parseArch(TT.getArchName());
260 if (AK == ARM::ArchKind::INVALID)
261 return make_error<JITLinkError>(
262 "Failed to build ELF link graph: Invalid ARM ArchKind");
263
264 // Resolve our internal configuration for the target. If at some point the
265 // CPUArch alone becomes too unprecise, we can find more details in the
266 // Tag_CPU_arch_profile.
267 auto Arch = static_cast<ARMBuildAttrs::CPUArch>(ARM::getArchAttr(AK));
268 aarch32::ArmConfig ArmCfg = aarch32::getArmConfigForCPUArch(Arch);
269
270 // Populate the link-graph.
271 switch (TT.getArch()) {
272 case Triple::arm:
273 case Triple::thumb: {
274 auto &ELFFile = cast<ELFObjectFile<ELF32LE>>(**ELFObj).getELFFile();
275 return ELFLinkGraphBuilder_aarch32<llvm::endianness::little>(
276 (*ELFObj)->getFileName(), ELFFile, TT, std::move(*Features),
277 ArmCfg)
278 .buildGraph();
279 }
280 case Triple::armeb:
281 case Triple::thumbeb: {
282 auto &ELFFile = cast<ELFObjectFile<ELF32BE>>(**ELFObj).getELFFile();
283 return ELFLinkGraphBuilder_aarch32<llvm::endianness::big>(
284 (*ELFObj)->getFileName(), ELFFile, TT, std::move(*Features),
285 ArmCfg)
286 .buildGraph();
287 }
288 default:
289 return make_error<JITLinkError>(
290 "Failed to build ELF/aarch32 link graph: Invalid target triple " +
291 TT.getTriple());
292 }
293 }
294
link_ELF_aarch32(std::unique_ptr<LinkGraph> G,std::unique_ptr<JITLinkContext> Ctx)295 void link_ELF_aarch32(std::unique_ptr<LinkGraph> G,
296 std::unique_ptr<JITLinkContext> Ctx) {
297 const Triple &TT = G->getTargetTriple();
298
299 using namespace ARMBuildAttrs;
300 ARM::ArchKind AK = ARM::parseArch(TT.getArchName());
301 auto CPU = static_cast<CPUArch>(ARM::getArchAttr(AK));
302 aarch32::ArmConfig ArmCfg = aarch32::getArmConfigForCPUArch(CPU);
303
304 PassConfiguration PassCfg;
305 if (Ctx->shouldAddDefaultTargetPasses(TT)) {
306 // Add a mark-live pass.
307 if (auto MarkLive = Ctx->getMarkLivePass(TT))
308 PassCfg.PrePrunePasses.push_back(std::move(MarkLive));
309 else
310 PassCfg.PrePrunePasses.push_back(markAllSymbolsLive);
311
312 switch (ArmCfg.Stubs) {
313 case aarch32::StubsFlavor::pre_v7:
314 PassCfg.PostPrunePasses.push_back(
315 buildTables_ELF_aarch32<aarch32::StubsManager_prev7>);
316 break;
317 case aarch32::StubsFlavor::v7:
318 PassCfg.PostPrunePasses.push_back(
319 buildTables_ELF_aarch32<aarch32::StubsManager_v7>);
320 break;
321 case aarch32::StubsFlavor::Undefined:
322 llvm_unreachable("Check before building graph");
323 }
324 }
325
326 if (auto Err = Ctx->modifyPassConfig(*G, PassCfg))
327 return Ctx->notifyFailed(std::move(Err));
328
329 ELFJITLinker_aarch32::link(std::move(Ctx), std::move(G), std::move(PassCfg),
330 std::move(ArmCfg));
331 }
332
333 } // namespace jitlink
334 } // namespace llvm
335