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       }
142       break;
143     case FK_Data_4:
144     case FK_PCRel_4:
145       Type = ELF::R_PPC_REL32;
146       break;
147     case FK_Data_8:
148     case FK_PCRel_8:
149       Type = ELF::R_PPC64_REL64;
150       break;
151     }
152   } else {
153     switch (Fixup.getTargetKind()) {
154       default: llvm_unreachable("invalid fixup kind!");
155     case PPC::fixup_ppc_br24abs:
156       Type = ELF::R_PPC_ADDR24;
157       break;
158     case PPC::fixup_ppc_brcond14abs:
159       Type = ELF::R_PPC_ADDR14; // XXX: or BRNTAKEN?_
160       break;
161     case PPC::fixup_ppc_half16:
162       switch (Modifier) {
163       default: llvm_unreachable("Unsupported Modifier");
164       case MCSymbolRefExpr::VK_None:
165         Type = ELF::R_PPC_ADDR16;
166         break;
167       case MCSymbolRefExpr::VK_PPC_LO:
168         Type = ELF::R_PPC_ADDR16_LO;
169         break;
170       case MCSymbolRefExpr::VK_PPC_HI:
171         Type = ELF::R_PPC_ADDR16_HI;
172         break;
173       case MCSymbolRefExpr::VK_PPC_HA:
174         Type = ELF::R_PPC_ADDR16_HA;
175         break;
176       case MCSymbolRefExpr::VK_PPC_HIGH:
177         Type = ELF::R_PPC64_ADDR16_HIGH;
178         break;
179       case MCSymbolRefExpr::VK_PPC_HIGHA:
180         Type = ELF::R_PPC64_ADDR16_HIGHA;
181         break;
182       case MCSymbolRefExpr::VK_PPC_HIGHER:
183         Type = ELF::R_PPC64_ADDR16_HIGHER;
184         break;
185       case MCSymbolRefExpr::VK_PPC_HIGHERA:
186         Type = ELF::R_PPC64_ADDR16_HIGHERA;
187         break;
188       case MCSymbolRefExpr::VK_PPC_HIGHEST:
189         Type = ELF::R_PPC64_ADDR16_HIGHEST;
190         break;
191       case MCSymbolRefExpr::VK_PPC_HIGHESTA:
192         Type = ELF::R_PPC64_ADDR16_HIGHESTA;
193         break;
194       case MCSymbolRefExpr::VK_GOT:
195         Type = ELF::R_PPC_GOT16;
196         break;
197       case MCSymbolRefExpr::VK_PPC_GOT_LO:
198         Type = ELF::R_PPC_GOT16_LO;
199         break;
200       case MCSymbolRefExpr::VK_PPC_GOT_HI:
201         Type = ELF::R_PPC_GOT16_HI;
202         break;
203       case MCSymbolRefExpr::VK_PPC_GOT_HA:
204         Type = ELF::R_PPC_GOT16_HA;
205         break;
206       case MCSymbolRefExpr::VK_PPC_TOC:
207         Type = ELF::R_PPC64_TOC16;
208         break;
209       case MCSymbolRefExpr::VK_PPC_TOC_LO:
210         Type = ELF::R_PPC64_TOC16_LO;
211         break;
212       case MCSymbolRefExpr::VK_PPC_TOC_HI:
213         Type = ELF::R_PPC64_TOC16_HI;
214         break;
215       case MCSymbolRefExpr::VK_PPC_TOC_HA:
216         Type = ELF::R_PPC64_TOC16_HA;
217         break;
218       case MCSymbolRefExpr::VK_TPREL:
219         Type = ELF::R_PPC_TPREL16;
220         break;
221       case MCSymbolRefExpr::VK_PPC_TPREL_LO:
222         Type = ELF::R_PPC_TPREL16_LO;
223         break;
224       case MCSymbolRefExpr::VK_PPC_TPREL_HI:
225         Type = ELF::R_PPC_TPREL16_HI;
226         break;
227       case MCSymbolRefExpr::VK_PPC_TPREL_HA:
228         Type = ELF::R_PPC_TPREL16_HA;
229         break;
230       case MCSymbolRefExpr::VK_PPC_TPREL_HIGH:
231         Type = ELF::R_PPC64_TPREL16_HIGH;
232         break;
233       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHA:
234         Type = ELF::R_PPC64_TPREL16_HIGHA;
235         break;
236       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHER:
237         Type = ELF::R_PPC64_TPREL16_HIGHER;
238         break;
239       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHERA:
240         Type = ELF::R_PPC64_TPREL16_HIGHERA;
241         break;
242       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHEST:
243         Type = ELF::R_PPC64_TPREL16_HIGHEST;
244         break;
245       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHESTA:
246         Type = ELF::R_PPC64_TPREL16_HIGHESTA;
247         break;
248       case MCSymbolRefExpr::VK_DTPREL:
249         Type = ELF::R_PPC64_DTPREL16;
250         break;
251       case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
252         Type = ELF::R_PPC64_DTPREL16_LO;
253         break;
254       case MCSymbolRefExpr::VK_PPC_DTPREL_HI:
255         Type = ELF::R_PPC64_DTPREL16_HI;
256         break;
257       case MCSymbolRefExpr::VK_PPC_DTPREL_HA:
258         Type = ELF::R_PPC64_DTPREL16_HA;
259         break;
260       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGH:
261         Type = ELF::R_PPC64_DTPREL16_HIGH;
262         break;
263       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHA:
264         Type = ELF::R_PPC64_DTPREL16_HIGHA;
265         break;
266       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHER:
267         Type = ELF::R_PPC64_DTPREL16_HIGHER;
268         break;
269       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHERA:
270         Type = ELF::R_PPC64_DTPREL16_HIGHERA;
271         break;
272       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHEST:
273         Type = ELF::R_PPC64_DTPREL16_HIGHEST;
274         break;
275       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHESTA:
276         Type = ELF::R_PPC64_DTPREL16_HIGHESTA;
277         break;
278       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD:
279         if (is64Bit())
280           Type = ELF::R_PPC64_GOT_TLSGD16;
281         else
282           Type = ELF::R_PPC_GOT_TLSGD16;
283         break;
284       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
285         Type = ELF::R_PPC64_GOT_TLSGD16_LO;
286         break;
287       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
288         Type = ELF::R_PPC64_GOT_TLSGD16_HI;
289         break;
290       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
291         Type = ELF::R_PPC64_GOT_TLSGD16_HA;
292         break;
293       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
294         if (is64Bit())
295           Type = ELF::R_PPC64_GOT_TLSLD16;
296         else
297           Type = ELF::R_PPC_GOT_TLSLD16;
298         break;
299       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
300         Type = ELF::R_PPC64_GOT_TLSLD16_LO;
301         break;
302       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
303         Type = ELF::R_PPC64_GOT_TLSLD16_HI;
304         break;
305       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
306         Type = ELF::R_PPC64_GOT_TLSLD16_HA;
307         break;
308       case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
309         /* We don't have R_PPC64_GOT_TPREL16, but since GOT offsets
310            are always 4-aligned, we can use R_PPC64_GOT_TPREL16_DS.  */
311         Type = ELF::R_PPC64_GOT_TPREL16_DS;
312         break;
313       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
314         /* We don't have R_PPC64_GOT_TPREL16_LO, but since GOT offsets
315            are always 4-aligned, we can use R_PPC64_GOT_TPREL16_LO_DS.  */
316         Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
317         break;
318       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HI:
319         Type = ELF::R_PPC64_GOT_TPREL16_HI;
320         break;
321       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
322         /* We don't have R_PPC64_GOT_DTPREL16, but since GOT offsets
323            are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_DS.  */
324         Type = ELF::R_PPC64_GOT_DTPREL16_DS;
325         break;
326       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
327         /* We don't have R_PPC64_GOT_DTPREL16_LO, but since GOT offsets
328            are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_LO_DS.  */
329         Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
330         break;
331       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA:
332         Type = ELF::R_PPC64_GOT_TPREL16_HA;
333         break;
334       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HI:
335         Type = ELF::R_PPC64_GOT_DTPREL16_HI;
336         break;
337       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HA:
338         Type = ELF::R_PPC64_GOT_DTPREL16_HA;
339         break;
340       }
341       break;
342     case PPC::fixup_ppc_half16ds:
343       switch (Modifier) {
344       default: llvm_unreachable("Unsupported Modifier");
345       case MCSymbolRefExpr::VK_None:
346         Type = ELF::R_PPC64_ADDR16_DS;
347         break;
348       case MCSymbolRefExpr::VK_PPC_LO:
349         Type = ELF::R_PPC64_ADDR16_LO_DS;
350         break;
351       case MCSymbolRefExpr::VK_GOT:
352         Type = ELF::R_PPC64_GOT16_DS;
353         break;
354       case MCSymbolRefExpr::VK_PPC_GOT_LO:
355         Type = ELF::R_PPC64_GOT16_LO_DS;
356         break;
357       case MCSymbolRefExpr::VK_PPC_TOC:
358         Type = ELF::R_PPC64_TOC16_DS;
359         break;
360       case MCSymbolRefExpr::VK_PPC_TOC_LO:
361         Type = ELF::R_PPC64_TOC16_LO_DS;
362         break;
363       case MCSymbolRefExpr::VK_TPREL:
364         Type = ELF::R_PPC64_TPREL16_DS;
365         break;
366       case MCSymbolRefExpr::VK_PPC_TPREL_LO:
367         Type = ELF::R_PPC64_TPREL16_LO_DS;
368         break;
369       case MCSymbolRefExpr::VK_DTPREL:
370         Type = ELF::R_PPC64_DTPREL16_DS;
371         break;
372       case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
373         Type = ELF::R_PPC64_DTPREL16_LO_DS;
374         break;
375       case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
376         Type = ELF::R_PPC64_GOT_TPREL16_DS;
377         break;
378       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
379         Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
380         break;
381       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
382         Type = ELF::R_PPC64_GOT_DTPREL16_DS;
383         break;
384       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
385         Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
386         break;
387       }
388       break;
389     case PPC::fixup_ppc_nofixup:
390       switch (Modifier) {
391       default: llvm_unreachable("Unsupported Modifier");
392       case MCSymbolRefExpr::VK_PPC_TLSGD:
393         if (is64Bit())
394           Type = ELF::R_PPC64_TLSGD;
395         else
396           Type = ELF::R_PPC_TLSGD;
397         break;
398       case MCSymbolRefExpr::VK_PPC_TLSLD:
399         if (is64Bit())
400           Type = ELF::R_PPC64_TLSLD;
401         else
402           Type = ELF::R_PPC_TLSLD;
403         break;
404       case MCSymbolRefExpr::VK_PPC_TLS:
405         if (is64Bit())
406           Type = ELF::R_PPC64_TLS;
407         else
408           Type = ELF::R_PPC_TLS;
409         break;
410       }
411       break;
412     case FK_Data_8:
413       switch (Modifier) {
414       default: llvm_unreachable("Unsupported Modifier");
415       case MCSymbolRefExpr::VK_PPC_TOCBASE:
416         Type = ELF::R_PPC64_TOC;
417         break;
418       case MCSymbolRefExpr::VK_None:
419         Type = ELF::R_PPC64_ADDR64;
420         break;
421       case MCSymbolRefExpr::VK_PPC_DTPMOD:
422         Type = ELF::R_PPC64_DTPMOD64;
423         break;
424       case MCSymbolRefExpr::VK_TPREL:
425         Type = ELF::R_PPC64_TPREL64;
426         break;
427       case MCSymbolRefExpr::VK_DTPREL:
428         Type = ELF::R_PPC64_DTPREL64;
429         break;
430       }
431       break;
432     case FK_Data_4:
433       Type = ELF::R_PPC_ADDR32;
434       break;
435     case FK_Data_2:
436       Type = ELF::R_PPC_ADDR16;
437       break;
438     }
439   }
440   return Type;
441 }
442 
needsRelocateWithSymbol(const MCSymbol & Sym,unsigned Type) const443 bool PPCELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
444                                                  unsigned Type) const {
445   switch (Type) {
446     default:
447       return false;
448 
449     case ELF::R_PPC_REL24:
450     case ELF::R_PPC64_REL24_NOTOC:
451       // If the target symbol has a local entry point, we must keep the
452       // target symbol to preserve that information for the linker.
453       // The "other" values are stored in the last 6 bits of the second byte.
454       // The traditional defines for STO values assume the full byte and thus
455       // the shift to pack it.
456       unsigned Other = cast<MCSymbolELF>(Sym).getOther() << 2;
457       return (Other & ELF::STO_PPC64_LOCAL_MASK) != 0;
458   }
459 }
460 
461 std::unique_ptr<MCObjectTargetWriter>
createPPCELFObjectWriter(bool Is64Bit,uint8_t OSABI)462 llvm::createPPCELFObjectWriter(bool Is64Bit, uint8_t OSABI) {
463   return std::make_unique<PPCELFObjectWriter>(Is64Bit, OSABI);
464 }
465