xref: /freebsd/contrib/llvm-project/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFAArch64.h (revision a521f2116473fbd8c09db395518f060a27d02334) 
1 //===-- RuntimeDyldCOFFAArch64.h --- COFF/AArch64 specific code ---*- C++
2 //-*-===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // COFF AArch64 support for MC-JIT runtime dynamic linker.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFAARCH64_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFAARCH64_H
16 
17 #include "../RuntimeDyldCOFF.h"
18 #include "llvm/BinaryFormat/COFF.h"
19 #include "llvm/Object/COFF.h"
20 #include "llvm/Support/Endian.h"
21 
22 #define DEBUG_TYPE "dyld"
23 
24 using namespace llvm::support::endian;
25 
26 namespace llvm {
27 
28 // This relocation type is used for handling long branch instruction
29 // throught the Stub.
30 enum InternalRelocationType : unsigned {
31   INTERNAL_REL_ARM64_LONG_BRANCH26 = 0x111,
32 };
33 
34 static void add16(uint8_t *p, int16_t v) { write16le(p, read16le(p) + v); }
35 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }
36 
37 static void write32AArch64Imm(uint8_t *T, uint64_t imm, uint32_t rangeLimit) {
38   uint32_t orig = read32le(T);
39   orig &= ~(0xFFF << 10);
40   write32le(T, orig | ((imm & (0xFFF >> rangeLimit)) << 10));
41 }
42 
43 static void write32AArch64Ldr(uint8_t *T, uint64_t imm) {
44   uint32_t orig = read32le(T);
45   uint32_t size = orig >> 30;
46   // 0x04000000 indicates SIMD/FP registers
47   // 0x00800000 indicates 128 bit
48   if ((orig & 0x04800000) == 0x04800000)
49     size += 4;
50   if ((imm & ((1 << size) - 1)) != 0)
51     assert(0 && "misaligned ldr/str offset");
52   write32AArch64Imm(T, imm >> size, size);
53 }
54 
55 static void write32AArch64Addr(void *T, uint64_t s, uint64_t p, int shift) {
56   uint64_t Imm = (s >> shift) - (p >> shift);
57   uint32_t ImmLo = (Imm & 0x3) << 29;
58   uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
59   uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
60   write32le(T, (read32le(T) & ~Mask) | ImmLo | ImmHi);
61 }
62 
63 class RuntimeDyldCOFFAArch64 : public RuntimeDyldCOFF {
64 
65 private:
66   // When a module is loaded we save the SectionID of the unwind
67   // sections in a table until we receive a request to register all
68   // unregisteredEH frame sections with the memory manager.
69   SmallVector<SID, 2> UnregisteredEHFrameSections;
70   SmallVector<SID, 2> RegisteredEHFrameSections;
71   uint64_t ImageBase;
72 
73   // Fake an __ImageBase pointer by returning the section with the lowest adress
74   uint64_t getImageBase() {
75     if (!ImageBase) {
76       ImageBase = std::numeric_limits<uint64_t>::max();
77       for (const SectionEntry &Section : Sections)
78         // The Sections list may contain sections that weren't loaded for
79         // whatever reason: they may be debug sections, and ProcessAllSections
80         // is false, or they may be sections that contain 0 bytes. If the
81         // section isn't loaded, the load address will be 0, and it should not
82         // be included in the ImageBase calculation.
83         if (Section.getLoadAddress() != 0)
84           ImageBase = std::min(ImageBase, Section.getLoadAddress());
85     }
86     return ImageBase;
87   }
88 
89 public:
90   RuntimeDyldCOFFAArch64(RuntimeDyld::MemoryManager &MM,
91                          JITSymbolResolver &Resolver)
92       : RuntimeDyldCOFF(MM, Resolver, 8, COFF::IMAGE_REL_ARM64_ADDR64),
93         ImageBase(0) {}
94 
95   unsigned getStubAlignment() override { return 8; }
96 
97   unsigned getMaxStubSize() const override { return 20; }
98 
99   std::tuple<uint64_t, uint64_t, uint64_t>
100   generateRelocationStub(unsigned SectionID, StringRef TargetName,
101                          uint64_t Offset, uint64_t RelType, uint64_t Addend,
102                          StubMap &Stubs) {
103     uintptr_t StubOffset;
104     SectionEntry &Section = Sections[SectionID];
105 
106     RelocationValueRef OriginalRelValueRef;
107     OriginalRelValueRef.SectionID = SectionID;
108     OriginalRelValueRef.Offset = Offset;
109     OriginalRelValueRef.Addend = Addend;
110     OriginalRelValueRef.SymbolName = TargetName.data();
111 
112     auto Stub = Stubs.find(OriginalRelValueRef);
113     if (Stub == Stubs.end()) {
114       LLVM_DEBUG(dbgs() << " Create a new stub function for "
115                         << TargetName.data() << "\n");
116 
117       StubOffset = Section.getStubOffset();
118       Stubs[OriginalRelValueRef] = StubOffset;
119       createStubFunction(Section.getAddressWithOffset(StubOffset));
120       Section.advanceStubOffset(getMaxStubSize());
121     } else {
122       LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()
123                         << "\n");
124       StubOffset = Stub->second;
125     }
126 
127     // Resolve original relocation to stub function.
128     const RelocationEntry RE(SectionID, Offset, RelType, Addend);
129     resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));
130 
131     // adjust relocation info so resolution writes to the stub function
132     // Here an internal relocation type is used for resolving long branch via
133     // stub instruction.
134     Addend = 0;
135     Offset = StubOffset;
136     RelType = INTERNAL_REL_ARM64_LONG_BRANCH26;
137 
138     return std::make_tuple(Offset, RelType, Addend);
139   }
140 
141   Expected<object::relocation_iterator>
142   processRelocationRef(unsigned SectionID, object::relocation_iterator RelI,
143                        const object::ObjectFile &Obj,
144                        ObjSectionToIDMap &ObjSectionToID,
145                        StubMap &Stubs) override {
146 
147     auto Symbol = RelI->getSymbol();
148     if (Symbol == Obj.symbol_end())
149       report_fatal_error("Unknown symbol in relocation");
150 
151     Expected<StringRef> TargetNameOrErr = Symbol->getName();
152     if (!TargetNameOrErr)
153       return TargetNameOrErr.takeError();
154     StringRef TargetName = *TargetNameOrErr;
155 
156     auto SectionOrErr = Symbol->getSection();
157     if (!SectionOrErr)
158       return SectionOrErr.takeError();
159     auto Section = *SectionOrErr;
160 
161     uint64_t RelType = RelI->getType();
162     uint64_t Offset = RelI->getOffset();
163 
164     // If there is no section, this must be an external reference.
165     bool IsExtern = Section == Obj.section_end();
166 
167     // Determine the Addend used to adjust the relocation value.
168     uint64_t Addend = 0;
169     SectionEntry &AddendSection = Sections[SectionID];
170     uintptr_t ObjTarget = AddendSection.getObjAddress() + Offset;
171     uint8_t *Displacement = (uint8_t *)ObjTarget;
172 
173     unsigned TargetSectionID = -1;
174     uint64_t TargetOffset = -1;
175 
176     if (TargetName.startswith(getImportSymbolPrefix())) {
177       TargetSectionID = SectionID;
178       TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName);
179       TargetName = StringRef();
180       IsExtern = false;
181     } else if (!IsExtern) {
182       if (auto TargetSectionIDOrErr = findOrEmitSection(
183               Obj, *Section, Section->isText(), ObjSectionToID))
184         TargetSectionID = *TargetSectionIDOrErr;
185       else
186         return TargetSectionIDOrErr.takeError();
187 
188       TargetOffset = getSymbolOffset(*Symbol);
189     }
190 
191     switch (RelType) {
192     case COFF::IMAGE_REL_ARM64_ADDR32:
193     case COFF::IMAGE_REL_ARM64_ADDR32NB:
194     case COFF::IMAGE_REL_ARM64_REL32:
195     case COFF::IMAGE_REL_ARM64_SECREL:
196       Addend = read32le(Displacement);
197       break;
198     case COFF::IMAGE_REL_ARM64_BRANCH26: {
199       uint32_t orig = read32le(Displacement);
200       Addend = (orig & 0x03FFFFFF) << 2;
201 
202       if (IsExtern)
203         std::tie(Offset, RelType, Addend) = generateRelocationStub(
204             SectionID, TargetName, Offset, RelType, Addend, Stubs);
205       break;
206     }
207     case COFF::IMAGE_REL_ARM64_BRANCH19: {
208       uint32_t orig = read32le(Displacement);
209       Addend = (orig & 0x00FFFFE0) >> 3;
210       break;
211     }
212     case COFF::IMAGE_REL_ARM64_BRANCH14: {
213       uint32_t orig = read32le(Displacement);
214       Addend = (orig & 0x000FFFE0) >> 3;
215       break;
216     }
217     case COFF::IMAGE_REL_ARM64_REL21:
218     case COFF::IMAGE_REL_ARM64_PAGEBASE_REL21: {
219       uint32_t orig = read32le(Displacement);
220       Addend = ((orig >> 29) & 0x3) | ((orig >> 3) & 0x1FFFFC);
221       break;
222     }
223     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12L:
224     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12A: {
225       uint32_t orig = read32le(Displacement);
226       Addend = ((orig >> 10) & 0xFFF);
227       break;
228     }
229     case COFF::IMAGE_REL_ARM64_ADDR64: {
230       Addend = read64le(Displacement);
231       break;
232     }
233     default:
234       break;
235     }
236 
237 #if !defined(NDEBUG)
238     SmallString<32> RelTypeName;
239     RelI->getTypeName(RelTypeName);
240 
241     LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
242                       << " RelType: " << RelTypeName << " TargetName: "
243                       << TargetName << " Addend " << Addend << "\n");
244 #endif
245 
246     if (IsExtern) {
247       RelocationEntry RE(SectionID, Offset, RelType, Addend);
248       addRelocationForSymbol(RE, TargetName);
249     } else {
250       RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
251       addRelocationForSection(RE, TargetSectionID);
252     }
253     return ++RelI;
254   }
255 
256   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
257     const auto Section = Sections[RE.SectionID];
258     uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
259     uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
260 
261     switch (RE.RelType) {
262     default:
263       llvm_unreachable("unsupported relocation type");
264     case COFF::IMAGE_REL_ARM64_ABSOLUTE: {
265       // This relocation is ignored.
266       break;
267     }
268     case COFF::IMAGE_REL_ARM64_PAGEBASE_REL21: {
269       // The page base of the target, for ADRP instruction.
270       Value += RE.Addend;
271       write32AArch64Addr(Target, Value, FinalAddress, 12);
272       break;
273     }
274     case COFF::IMAGE_REL_ARM64_REL21: {
275       // The 12-bit relative displacement to the target, for instruction ADR
276       Value += RE.Addend;
277       write32AArch64Addr(Target, Value, FinalAddress, 0);
278       break;
279     }
280     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12A: {
281       // The 12-bit page offset of the target,
282       // for instructions ADD/ADDS (immediate) with zero shift.
283       Value += RE.Addend;
284       write32AArch64Imm(Target, Value & 0xFFF, 0);
285       break;
286     }
287     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12L: {
288       // The 12-bit page offset of the target,
289       // for instruction LDR (indexed, unsigned immediate).
290       Value += RE.Addend;
291       write32AArch64Ldr(Target, Value & 0xFFF);
292       break;
293     }
294     case COFF::IMAGE_REL_ARM64_ADDR32: {
295       // The 32-bit VA of the target.
296       uint32_t VA = Value + RE.Addend;
297       write32le(Target, VA);
298       break;
299     }
300     case COFF::IMAGE_REL_ARM64_ADDR32NB: {
301       // The target's 32-bit RVA.
302       uint64_t RVA = Value + RE.Addend - getImageBase();
303       write32le(Target, RVA);
304       break;
305     }
306     case INTERNAL_REL_ARM64_LONG_BRANCH26: {
307       // Encode the immadiate value for generated Stub instruction (MOVZ)
308       or32le(Target + 12, ((Value + RE.Addend) & 0xFFFF) << 5);
309       or32le(Target + 8, ((Value + RE.Addend) & 0xFFFF0000) >> 11);
310       or32le(Target + 4, ((Value + RE.Addend) & 0xFFFF00000000) >> 27);
311       or32le(Target + 0, ((Value + RE.Addend) & 0xFFFF000000000000) >> 43);
312       break;
313     }
314     case COFF::IMAGE_REL_ARM64_BRANCH26: {
315       // The 26-bit relative displacement to the target, for B and BL
316       // instructions.
317       uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
318       assert(isInt<28>(PCRelVal) && "Branch target is out of range.");
319       write32le(Target, (read32le(Target) & ~(0x03FFFFFF)) |
320                             (PCRelVal & 0x0FFFFFFC) >> 2);
321       break;
322     }
323     case COFF::IMAGE_REL_ARM64_BRANCH19: {
324       // The 19-bit offset to the relocation target,
325       // for conditional B instruction.
326       uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
327       assert(isInt<21>(PCRelVal) && "Branch target is out of range.");
328       write32le(Target, (read32le(Target) & ~(0x00FFFFE0)) |
329                             (PCRelVal & 0x001FFFFC) << 3);
330       break;
331     }
332     case COFF::IMAGE_REL_ARM64_BRANCH14: {
333       // The 14-bit offset to the relocation target,
334       // for instructions TBZ and TBNZ.
335       uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
336       assert(isInt<16>(PCRelVal) && "Branch target is out of range.");
337       write32le(Target, (read32le(Target) & ~(0x000FFFE0)) |
338                             (PCRelVal & 0x0000FFFC) << 3);
339       break;
340     }
341     case COFF::IMAGE_REL_ARM64_ADDR64: {
342       // The 64-bit VA of the relocation target.
343       write64le(Target, Value + RE.Addend);
344       break;
345     }
346     case COFF::IMAGE_REL_ARM64_SECTION: {
347       // 16-bit section index of the section that contains the target.
348       assert(static_cast<uint32_t>(RE.SectionID) <= UINT16_MAX &&
349              "relocation overflow");
350       add16(Target, RE.SectionID);
351       break;
352     }
353     case COFF::IMAGE_REL_ARM64_SECREL: {
354       // 32-bit offset of the target from the beginning of its section.
355       assert(static_cast<int64_t>(RE.Addend) <= INT32_MAX &&
356              "Relocation overflow");
357       assert(static_cast<int64_t>(RE.Addend) >= INT32_MIN &&
358              "Relocation underflow");
359       write32le(Target, RE.Addend);
360       break;
361     }
362     case COFF::IMAGE_REL_ARM64_REL32: {
363       // The 32-bit relative address from the byte following the relocation.
364       uint64_t Result = Value - FinalAddress - 4;
365       write32le(Target, Result + RE.Addend);
366       break;
367     }
368     }
369   }
370 
371   void registerEHFrames() override {}
372 };
373 
374 } // End namespace llvm
375 
376 #endif
377