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
28using namespace llvm::object;
29
30namespace llvm {
31namespace jitlink {
32
33/// Translate from ELF relocation type to JITLink-internal edge kind.
34Expected<aarch32::EdgeKind_aarch32>
35getJITLinkEdgeKind(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 Args: "Unsupported aarch32 relocation " + formatv(Fmt: "{0:d}: ", Vals&: ELFType) +
74 object::getELFRelocationTypeName(Machine: ELF::EM_ARM, Type: ELFType));
75}
76
77/// Translate from JITLink-internal edge kind back to ELF relocation type.
78Expected<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>(Args: formatv(Fmt: "Invalid aarch32 edge {0:d}: ",
113 Vals&: Kind));
114}
115
116/// Get a human-readable name for the given ELF AArch32 edge kind.
117const char *getELFAArch32EdgeKindName(Edge::Kind R) {
118 // No ELF-specific edge kinds yet
119 return aarch32::getEdgeKindName(K: R);
120}
121
122class ELFJITLinker_aarch32 : public JITLinker<ELFJITLinker_aarch32> {
123 friend class JITLinker<ELFJITLinker_aarch32>;
124
125public:
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
132private:
133 aarch32::ArmConfig ArmCfg;
134
135 Error applyFixup(LinkGraph &G, Block &B, const Edge &E) const {
136 return aarch32::applyFixup(G, B, E, ArmCfg);
137 }
138};
139
140template <llvm::endianness DataEndianness>
141class ELFLinkGraphBuilder_aarch32
142 : public ELFLinkGraphBuilder<ELFType<DataEndianness, false>> {
143private:
144 using ELFT = ELFType<DataEndianness, false>;
145 using Base = ELFLinkGraphBuilder<ELFT>;
146
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
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(ELFType: 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(G&: *Base::G, B&: BlockToFix, Offset, Kind: *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(E: std::move(E));
196 return Error::success();
197 }
198
199 aarch32::ArmConfig ArmCfg;
200
201protected:
202 TargetFlagsType makeTargetFlags(const typename ELFT::Sym &Sym) override {
203 if (Sym.getValue() & 0x01)
204 return aarch32::ThumbSymbol;
205 return TargetFlagsType{};
206 }
207
208 orc::ExecutorAddrDiff getRawOffset(const typename ELFT::Sym &Sym,
209 TargetFlagsType Flags) override {
210 assert((makeTargetFlags(Sym) & Flags) == Flags);
211 static constexpr uint64_t ThumbBit = 0x01;
212 return Sym.getValue() & ~ThumbBit;
213 }
214
215public:
216 ELFLinkGraphBuilder_aarch32(StringRef FileName,
217 const llvm::object::ELFFile<ELFT> &Obj, Triple TT,
218 SubtargetFeatures Features,
219 aarch32::ArmConfig ArmCfg)
220 : ELFLinkGraphBuilder<ELFT>(Obj, std::move(TT), std::move(Features),
221 FileName, getELFAArch32EdgeKindName),
222 ArmCfg(std::move(ArmCfg)) {}
223};
224
225template <typename StubsManagerType>
226Error buildTables_ELF_aarch32(LinkGraph &G) {
227 LLVM_DEBUG(dbgs() << "Visiting edges in graph:\n");
228
229 StubsManagerType StubsManager;
230 visitExistingEdges(G, StubsManager);
231 aarch32::GOTBuilder GOT;
232 visitExistingEdges(G, Vs&: GOT);
233
234 return Error::success();
235}
236
237Expected<std::unique_ptr<LinkGraph>>
238createLinkGraphFromELFObject_aarch32(MemoryBufferRef ObjectBuffer) {
239 LLVM_DEBUG({
240 dbgs() << "Building jitlink graph for new input "
241 << ObjectBuffer.getBufferIdentifier() << "...\n";
242 });
243
244 auto ELFObj = ObjectFile::createELFObjectFile(Object: ObjectBuffer);
245 if (!ELFObj)
246 return ELFObj.takeError();
247
248 auto Features = (*ELFObj)->getFeatures();
249 if (!Features)
250 return Features.takeError();
251
252 // Find out what exact AArch32 instruction set and features we target.
253 auto TT = (*ELFObj)->makeTriple();
254 ARM::ArchKind AK = ARM::parseArch(Arch: TT.getArchName());
255 if (AK == ARM::ArchKind::INVALID)
256 return make_error<JITLinkError>(
257 Args: "Failed to build ELF link graph: Invalid ARM ArchKind");
258
259 // Resolve our internal configuration for the target. If at some point the
260 // CPUArch alone becomes too unprecise, we can find more details in the
261 // Tag_CPU_arch_profile.
262 auto Arch = static_cast<ARMBuildAttrs::CPUArch>(ARM::getArchAttr(AK));
263 aarch32::ArmConfig ArmCfg = aarch32::getArmConfigForCPUArch(CPUArch: Arch);
264
265 // Populate the link-graph.
266 switch (TT.getArch()) {
267 case Triple::arm:
268 case Triple::thumb: {
269 auto &ELFFile = cast<ELFObjectFile<ELF32LE>>(Val&: **ELFObj).getELFFile();
270 return ELFLinkGraphBuilder_aarch32<llvm::endianness::little>(
271 (*ELFObj)->getFileName(), ELFFile, TT, std::move(*Features),
272 ArmCfg)
273 .buildGraph();
274 }
275 case Triple::armeb:
276 case Triple::thumbeb: {
277 auto &ELFFile = cast<ELFObjectFile<ELF32BE>>(Val&: **ELFObj).getELFFile();
278 return ELFLinkGraphBuilder_aarch32<llvm::endianness::big>(
279 (*ELFObj)->getFileName(), ELFFile, TT, std::move(*Features),
280 ArmCfg)
281 .buildGraph();
282 }
283 default:
284 return make_error<JITLinkError>(
285 Args: "Failed to build ELF/aarch32 link graph: Invalid target triple " +
286 TT.getTriple());
287 }
288}
289
290void link_ELF_aarch32(std::unique_ptr<LinkGraph> G,
291 std::unique_ptr<JITLinkContext> Ctx) {
292 const Triple &TT = G->getTargetTriple();
293
294 using namespace ARMBuildAttrs;
295 ARM::ArchKind AK = ARM::parseArch(Arch: TT.getArchName());
296 auto CPU = static_cast<CPUArch>(ARM::getArchAttr(AK));
297 aarch32::ArmConfig ArmCfg = aarch32::getArmConfigForCPUArch(CPUArch: CPU);
298
299 PassConfiguration PassCfg;
300 if (Ctx->shouldAddDefaultTargetPasses(TT)) {
301 // Add a mark-live pass.
302 if (auto MarkLive = Ctx->getMarkLivePass(TT))
303 PassCfg.PrePrunePasses.push_back(x: std::move(MarkLive));
304 else
305 PassCfg.PrePrunePasses.push_back(x: markAllSymbolsLive);
306
307 switch (ArmCfg.Stubs) {
308 case aarch32::StubsFlavor::pre_v7:
309 PassCfg.PostPrunePasses.push_back(
310 x: buildTables_ELF_aarch32<aarch32::StubsManager_prev7>);
311 break;
312 case aarch32::StubsFlavor::v7:
313 PassCfg.PostPrunePasses.push_back(
314 x: buildTables_ELF_aarch32<aarch32::StubsManager_v7>);
315 break;
316 case aarch32::StubsFlavor::Undefined:
317 llvm_unreachable("Check before building graph");
318 }
319 }
320
321 if (auto Err = Ctx->modifyPassConfig(G&: *G, Config&: PassCfg))
322 return Ctx->notifyFailed(Err: std::move(Err));
323
324 ELFJITLinker_aarch32::link(Args: std::move(Ctx), Args: std::move(G), Args: std::move(PassCfg),
325 Args: std::move(ArmCfg));
326}
327
328} // namespace jitlink
329} // namespace llvm
330

source code of llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp