1 //===-- PPCELFObjectWriter.cpp - PPC ELF Writer ---------------------------===//
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 "MCTargetDesc/PPCFixupKinds.h"
10 #include "MCTargetDesc/PPCMCExpr.h"
11 #include "MCTargetDesc/PPCMCTargetDesc.h"
12 #include "llvm/ADT/STLExtras.h"
13 #include "llvm/MC/MCELFObjectWriter.h"
14 #include "llvm/MC/MCExpr.h"
15 #include "llvm/MC/MCObjectWriter.h"
16 #include "llvm/MC/MCSymbolELF.h"
17 #include "llvm/MC/MCValue.h"
18 #include "llvm/Support/ErrorHandling.h"
19 
20 using namespace llvm;
21 
22 namespace {
23   class PPCELFObjectWriter : public MCELFObjectTargetWriter {
24   public:
25     PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI);
26 
27   protected:
28     unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
29                           const MCFixup &Fixup, bool IsPCRel) const override;
30 
31     bool needsRelocateWithSymbol(const MCSymbol &Sym,
32                                  unsigned Type) const override;
33   };
34 }
35 
PPCELFObjectWriter(bool Is64Bit,uint8_t OSABI)36 PPCELFObjectWriter::PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI)
37   : MCELFObjectTargetWriter(Is64Bit, OSABI,
38                             Is64Bit ?  ELF::EM_PPC64 : ELF::EM_PPC,
39                             /*HasRelocationAddend*/ true) {}
40 
getAccessVariant(const MCValue & Target,const MCFixup & Fixup)41 static MCSymbolRefExpr::VariantKind getAccessVariant(const MCValue &Target,
42                                                      const MCFixup &Fixup) {
43   const MCExpr *Expr = Fixup.getValue();
44 
45   if (Expr->getKind() != MCExpr::Target)
46     return Target.getAccessVariant();
47 
48   switch (cast<PPCMCExpr>(Expr)->getKind()) {
49   case PPCMCExpr::VK_PPC_None:
50     return MCSymbolRefExpr::VK_None;
51   case PPCMCExpr::VK_PPC_LO:
52     return MCSymbolRefExpr::VK_PPC_LO;
53   case PPCMCExpr::VK_PPC_HI:
54     return MCSymbolRefExpr::VK_PPC_HI;
55   case PPCMCExpr::VK_PPC_HA:
56     return MCSymbolRefExpr::VK_PPC_HA;
57   case PPCMCExpr::VK_PPC_HIGH:
58     return MCSymbolRefExpr::VK_PPC_HIGH;
59   case PPCMCExpr::VK_PPC_HIGHA:
60     return MCSymbolRefExpr::VK_PPC_HIGHA;
61   case PPCMCExpr::VK_PPC_HIGHERA:
62     return MCSymbolRefExpr::VK_PPC_HIGHERA;
63   case PPCMCExpr::VK_PPC_HIGHER:
64     return MCSymbolRefExpr::VK_PPC_HIGHER;
65   case PPCMCExpr::VK_PPC_HIGHEST:
66     return MCSymbolRefExpr::VK_PPC_HIGHEST;
67   case PPCMCExpr::VK_PPC_HIGHESTA:
68     return MCSymbolRefExpr::VK_PPC_HIGHESTA;
69   }
70   llvm_unreachable("unknown PPCMCExpr kind");
71 }
72 
getRelocType(MCContext & Ctx,const MCValue & Target,const MCFixup & Fixup,bool IsPCRel) const73 unsigned PPCELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
74                                           const MCFixup &Fixup,
75                                           bool IsPCRel) const {
76   MCFixupKind Kind = Fixup.getKind();
77   if (Kind >= FirstLiteralRelocationKind)
78     return Kind - FirstLiteralRelocationKind;
79   MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Target, Fixup);
80 
81   // determine the type of the relocation
82   unsigned Type;
83   if (IsPCRel) {
84     switch (Fixup.getTargetKind()) {
85     default:
86       llvm_unreachable("Unimplemented");
87     case PPC::fixup_ppc_br24:
88     case PPC::fixup_ppc_br24abs:
89     case PPC::fixup_ppc_br24_notoc:
90       switch (Modifier) {
91       default: llvm_unreachable("Unsupported Modifier");
92       case MCSymbolRefExpr::VK_None:
93         Type = ELF::R_PPC_REL24;
94         break;
95       case MCSymbolRefExpr::VK_PLT:
96         Type = ELF::R_PPC_PLTREL24;
97         break;
98       case MCSymbolRefExpr::VK_PPC_LOCAL:
99         Type = ELF::R_PPC_LOCAL24PC;
100         break;
101       case MCSymbolRefExpr::VK_PPC_NOTOC:
102         Type = ELF::R_PPC64_REL24_NOTOC;
103         break;
104       }
105       break;
106     case PPC::fixup_ppc_brcond14:
107     case PPC::fixup_ppc_brcond14abs:
108       Type = ELF::R_PPC_REL14;
109       break;
110     case PPC::fixup_ppc_half16:
111       switch (Modifier) {
112       default: llvm_unreachable("Unsupported Modifier");
113       case MCSymbolRefExpr::VK_None:
114         Type = ELF::R_PPC_REL16;
115         break;
116       case MCSymbolRefExpr::VK_PPC_LO:
117         Type = ELF::R_PPC_REL16_LO;
118         break;
119       case MCSymbolRefExpr::VK_PPC_HI:
120         Type = ELF::R_PPC_REL16_HI;
121         break;
122       case MCSymbolRefExpr::VK_PPC_HA:
123         Type = ELF::R_PPC_REL16_HA;
124         break;
125       }
126       break;
127     case PPC::fixup_ppc_half16ds:
128       Target.print(errs());
129       errs() << '\n';
130       report_fatal_error("Invalid PC-relative half16ds relocation");
131     case PPC::fixup_ppc_pcrel34:
132       switch (Modifier) {
133       default:
134         llvm_unreachable("Unsupported Modifier for fixup_ppc_pcrel34");
135       case MCSymbolRefExpr::VK_PCREL:
136         Type = ELF::R_PPC64_PCREL34;
137         break;
138       case MCSymbolRefExpr::VK_PPC_GOT_PCREL:
139         Type = ELF::R_PPC64_GOT_PCREL34;
140         break;
141       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_PCREL:
142         Type = ELF::R_PPC64_GOT_TLSGD_PCREL34;
143         break;
144       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_PCREL:
145         Type = ELF::R_PPC64_GOT_TLSLD_PCREL34;
146         break;
147       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_PCREL:
148         Type = ELF::R_PPC64_GOT_TPREL_PCREL34;
149         break;
150       }
151       break;
152     case FK_Data_4:
153     case FK_PCRel_4:
154       Type = ELF::R_PPC_REL32;
155       break;
156     case FK_Data_8:
157     case FK_PCRel_8:
158       Type = ELF::R_PPC64_REL64;
159       break;
160     }
161   } else {
162     switch (Fixup.getTargetKind()) {
163       default: llvm_unreachable("invalid fixup kind!");
164     case PPC::fixup_ppc_br24abs:
165       Type = ELF::R_PPC_ADDR24;
166       break;
167     case PPC::fixup_ppc_brcond14abs:
168       Type = ELF::R_PPC_ADDR14; // XXX: or BRNTAKEN?_
169       break;
170     case PPC::fixup_ppc_half16:
171       switch (Modifier) {
172       default: llvm_unreachable("Unsupported Modifier");
173       case MCSymbolRefExpr::VK_None:
174         Type = ELF::R_PPC_ADDR16;
175         break;
176       case MCSymbolRefExpr::VK_PPC_LO:
177         Type = ELF::R_PPC_ADDR16_LO;
178         break;
179       case MCSymbolRefExpr::VK_PPC_HI:
180         Type = ELF::R_PPC_ADDR16_HI;
181         break;
182       case MCSymbolRefExpr::VK_PPC_HA:
183         Type = ELF::R_PPC_ADDR16_HA;
184         break;
185       case MCSymbolRefExpr::VK_PPC_HIGH:
186         Type = ELF::R_PPC64_ADDR16_HIGH;
187         break;
188       case MCSymbolRefExpr::VK_PPC_HIGHA:
189         Type = ELF::R_PPC64_ADDR16_HIGHA;
190         break;
191       case MCSymbolRefExpr::VK_PPC_HIGHER:
192         Type = ELF::R_PPC64_ADDR16_HIGHER;
193         break;
194       case MCSymbolRefExpr::VK_PPC_HIGHERA:
195         Type = ELF::R_PPC64_ADDR16_HIGHERA;
196         break;
197       case MCSymbolRefExpr::VK_PPC_HIGHEST:
198         Type = ELF::R_PPC64_ADDR16_HIGHEST;
199         break;
200       case MCSymbolRefExpr::VK_PPC_HIGHESTA:
201         Type = ELF::R_PPC64_ADDR16_HIGHESTA;
202         break;
203       case MCSymbolRefExpr::VK_GOT:
204         Type = ELF::R_PPC_GOT16;
205         break;
206       case MCSymbolRefExpr::VK_PPC_GOT_LO:
207         Type = ELF::R_PPC_GOT16_LO;
208         break;
209       case MCSymbolRefExpr::VK_PPC_GOT_HI:
210         Type = ELF::R_PPC_GOT16_HI;
211         break;
212       case MCSymbolRefExpr::VK_PPC_GOT_HA:
213         Type = ELF::R_PPC_GOT16_HA;
214         break;
215       case MCSymbolRefExpr::VK_PPC_TOC:
216         Type = ELF::R_PPC64_TOC16;
217         break;
218       case MCSymbolRefExpr::VK_PPC_TOC_LO:
219         Type = ELF::R_PPC64_TOC16_LO;
220         break;
221       case MCSymbolRefExpr::VK_PPC_TOC_HI:
222         Type = ELF::R_PPC64_TOC16_HI;
223         break;
224       case MCSymbolRefExpr::VK_PPC_TOC_HA:
225         Type = ELF::R_PPC64_TOC16_HA;
226         break;
227       case MCSymbolRefExpr::VK_TPREL:
228         Type = ELF::R_PPC_TPREL16;
229         break;
230       case MCSymbolRefExpr::VK_PPC_TPREL_LO:
231         Type = ELF::R_PPC_TPREL16_LO;
232         break;
233       case MCSymbolRefExpr::VK_PPC_TPREL_HI:
234         Type = ELF::R_PPC_TPREL16_HI;
235         break;
236       case MCSymbolRefExpr::VK_PPC_TPREL_HA:
237         Type = ELF::R_PPC_TPREL16_HA;
238         break;
239       case MCSymbolRefExpr::VK_PPC_TPREL_HIGH:
240         Type = ELF::R_PPC64_TPREL16_HIGH;
241         break;
242       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHA:
243         Type = ELF::R_PPC64_TPREL16_HIGHA;
244         break;
245       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHER:
246         Type = ELF::R_PPC64_TPREL16_HIGHER;
247         break;
248       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHERA:
249         Type = ELF::R_PPC64_TPREL16_HIGHERA;
250         break;
251       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHEST:
252         Type = ELF::R_PPC64_TPREL16_HIGHEST;
253         break;
254       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHESTA:
255         Type = ELF::R_PPC64_TPREL16_HIGHESTA;
256         break;
257       case MCSymbolRefExpr::VK_DTPREL:
258         Type = ELF::R_PPC64_DTPREL16;
259         break;
260       case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
261         Type = ELF::R_PPC64_DTPREL16_LO;
262         break;
263       case MCSymbolRefExpr::VK_PPC_DTPREL_HI:
264         Type = ELF::R_PPC64_DTPREL16_HI;
265         break;
266       case MCSymbolRefExpr::VK_PPC_DTPREL_HA:
267         Type = ELF::R_PPC64_DTPREL16_HA;
268         break;
269       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGH:
270         Type = ELF::R_PPC64_DTPREL16_HIGH;
271         break;
272       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHA:
273         Type = ELF::R_PPC64_DTPREL16_HIGHA;
274         break;
275       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHER:
276         Type = ELF::R_PPC64_DTPREL16_HIGHER;
277         break;
278       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHERA:
279         Type = ELF::R_PPC64_DTPREL16_HIGHERA;
280         break;
281       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHEST:
282         Type = ELF::R_PPC64_DTPREL16_HIGHEST;
283         break;
284       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHESTA:
285         Type = ELF::R_PPC64_DTPREL16_HIGHESTA;
286         break;
287       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD:
288         if (is64Bit())
289           Type = ELF::R_PPC64_GOT_TLSGD16;
290         else
291           Type = ELF::R_PPC_GOT_TLSGD16;
292         break;
293       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
294         Type = ELF::R_PPC64_GOT_TLSGD16_LO;
295         break;
296       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
297         Type = ELF::R_PPC64_GOT_TLSGD16_HI;
298         break;
299       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
300         Type = ELF::R_PPC64_GOT_TLSGD16_HA;
301         break;
302       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
303         if (is64Bit())
304           Type = ELF::R_PPC64_GOT_TLSLD16;
305         else
306           Type = ELF::R_PPC_GOT_TLSLD16;
307         break;
308       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
309         Type = ELF::R_PPC64_GOT_TLSLD16_LO;
310         break;
311       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
312         Type = ELF::R_PPC64_GOT_TLSLD16_HI;
313         break;
314       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
315         Type = ELF::R_PPC64_GOT_TLSLD16_HA;
316         break;
317       case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
318         /* We don't have R_PPC64_GOT_TPREL16, but since GOT offsets
319            are always 4-aligned, we can use R_PPC64_GOT_TPREL16_DS.  */
320         Type = ELF::R_PPC64_GOT_TPREL16_DS;
321         break;
322       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
323         /* We don't have R_PPC64_GOT_TPREL16_LO, but since GOT offsets
324            are always 4-aligned, we can use R_PPC64_GOT_TPREL16_LO_DS.  */
325         Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
326         break;
327       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HI:
328         Type = ELF::R_PPC64_GOT_TPREL16_HI;
329         break;
330       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
331         /* We don't have R_PPC64_GOT_DTPREL16, but since GOT offsets
332            are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_DS.  */
333         Type = ELF::R_PPC64_GOT_DTPREL16_DS;
334         break;
335       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
336         /* We don't have R_PPC64_GOT_DTPREL16_LO, but since GOT offsets
337            are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_LO_DS.  */
338         Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
339         break;
340       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA:
341         Type = ELF::R_PPC64_GOT_TPREL16_HA;
342         break;
343       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HI:
344         Type = ELF::R_PPC64_GOT_DTPREL16_HI;
345         break;
346       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HA:
347         Type = ELF::R_PPC64_GOT_DTPREL16_HA;
348         break;
349       }
350       break;
351     case PPC::fixup_ppc_half16ds:
352       switch (Modifier) {
353       default: llvm_unreachable("Unsupported Modifier");
354       case MCSymbolRefExpr::VK_None:
355         Type = ELF::R_PPC64_ADDR16_DS;
356         break;
357       case MCSymbolRefExpr::VK_PPC_LO:
358         Type = ELF::R_PPC64_ADDR16_LO_DS;
359         break;
360       case MCSymbolRefExpr::VK_GOT:
361         Type = ELF::R_PPC64_GOT16_DS;
362         break;
363       case MCSymbolRefExpr::VK_PPC_GOT_LO:
364         Type = ELF::R_PPC64_GOT16_LO_DS;
365         break;
366       case MCSymbolRefExpr::VK_PPC_TOC:
367         Type = ELF::R_PPC64_TOC16_DS;
368         break;
369       case MCSymbolRefExpr::VK_PPC_TOC_LO:
370         Type = ELF::R_PPC64_TOC16_LO_DS;
371         break;
372       case MCSymbolRefExpr::VK_TPREL:
373         Type = ELF::R_PPC64_TPREL16_DS;
374         break;
375       case MCSymbolRefExpr::VK_PPC_TPREL_LO:
376         Type = ELF::R_PPC64_TPREL16_LO_DS;
377         break;
378       case MCSymbolRefExpr::VK_DTPREL:
379         Type = ELF::R_PPC64_DTPREL16_DS;
380         break;
381       case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
382         Type = ELF::R_PPC64_DTPREL16_LO_DS;
383         break;
384       case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
385         Type = ELF::R_PPC64_GOT_TPREL16_DS;
386         break;
387       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
388         Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
389         break;
390       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
391         Type = ELF::R_PPC64_GOT_DTPREL16_DS;
392         break;
393       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
394         Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
395         break;
396       }
397       break;
398     case PPC::fixup_ppc_nofixup:
399       switch (Modifier) {
400       default: llvm_unreachable("Unsupported Modifier");
401       case MCSymbolRefExpr::VK_PPC_TLSGD:
402         if (is64Bit())
403           Type = ELF::R_PPC64_TLSGD;
404         else
405           Type = ELF::R_PPC_TLSGD;
406         break;
407       case MCSymbolRefExpr::VK_PPC_TLSLD:
408         if (is64Bit())
409           Type = ELF::R_PPC64_TLSLD;
410         else
411           Type = ELF::R_PPC_TLSLD;
412         break;
413       case MCSymbolRefExpr::VK_PPC_TLS:
414         if (is64Bit())
415           Type = ELF::R_PPC64_TLS;
416         else
417           Type = ELF::R_PPC_TLS;
418         break;
419       case MCSymbolRefExpr::VK_PPC_TLS_PCREL:
420         Type = ELF::R_PPC64_TLS;
421         break;
422       }
423       break;
424     case PPC::fixup_ppc_imm34:
425       switch (Modifier) {
426       default:
427         report_fatal_error("Unsupported Modifier for fixup_ppc_imm34.");
428       case MCSymbolRefExpr::VK_DTPREL:
429         Type = ELF::R_PPC64_DTPREL34;
430         break;
431       case MCSymbolRefExpr::VK_TPREL:
432         Type = ELF::R_PPC64_TPREL34;
433         break;
434       }
435       break;
436     case FK_Data_8:
437       switch (Modifier) {
438       default: llvm_unreachable("Unsupported Modifier");
439       case MCSymbolRefExpr::VK_PPC_TOCBASE:
440         Type = ELF::R_PPC64_TOC;
441         break;
442       case MCSymbolRefExpr::VK_None:
443         Type = ELF::R_PPC64_ADDR64;
444         break;
445       case MCSymbolRefExpr::VK_PPC_DTPMOD:
446         Type = ELF::R_PPC64_DTPMOD64;
447         break;
448       case MCSymbolRefExpr::VK_TPREL:
449         Type = ELF::R_PPC64_TPREL64;
450         break;
451       case MCSymbolRefExpr::VK_DTPREL:
452         Type = ELF::R_PPC64_DTPREL64;
453         break;
454       }
455       break;
456     case FK_Data_4:
457       Type = ELF::R_PPC_ADDR32;
458       break;
459     case FK_Data_2:
460       Type = ELF::R_PPC_ADDR16;
461       break;
462     }
463   }
464   return Type;
465 }
466 
needsRelocateWithSymbol(const MCSymbol & Sym,unsigned Type) const467 bool PPCELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
468                                                  unsigned Type) const {
469   switch (Type) {
470     default:
471       return false;
472 
473     case ELF::R_PPC_REL24:
474     case ELF::R_PPC64_REL24_NOTOC:
475       // If the target symbol has a local entry point, we must keep the
476       // target symbol to preserve that information for the linker.
477       // The "other" values are stored in the last 6 bits of the second byte.
478       // The traditional defines for STO values assume the full byte and thus
479       // the shift to pack it.
480       unsigned Other = cast<MCSymbolELF>(Sym).getOther() << 2;
481       return (Other & ELF::STO_PPC64_LOCAL_MASK) != 0;
482   }
483 }
484 
485 std::unique_ptr<MCObjectTargetWriter>
createPPCELFObjectWriter(bool Is64Bit,uint8_t OSABI)486 llvm::createPPCELFObjectWriter(bool Is64Bit, uint8_t OSABI) {
487   return std::make_unique<PPCELFObjectWriter>(Is64Bit, OSABI);
488 }
489