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1 /* BFD back-end for Motorola 68000 COFF binaries.
2    Copyright (C) 1990-2014 Free Software Foundation, Inc.
3    Written by Cygnus Support.
4 
5    This file is part of BFD, the Binary File Descriptor library.
6 
7    This program is free software; you can redistribute it and/or modify
8    it under the terms of the GNU General Public License as published by
9    the Free Software Foundation; either version 3 of the License, or
10    (at your option) any later version.
11 
12    This program is distributed in the hope that it will be useful,
13    but WITHOUT ANY WARRANTY; without even the implied warranty of
14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15    GNU General Public License for more details.
16 
17    You should have received a copy of the GNU General Public License
18    along with this program; if not, write to the Free Software
19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
20    MA 02110-1301, USA.  */
21 
22 #include "sysdep.h"
23 #include "bfd.h"
24 #include "libbfd.h"
25 #include "coff/m68k.h"
26 #include "coff/internal.h"
27 #include "libcoff.h"
28 
29 /* This source file is compiled multiple times for various m68k COFF
30    variants.  The following macros control its behaviour:
31 
32    TARGET_SYM
33      The C name of the BFD target vector.  The default is m68k_coff_vec.
34    TARGET_NAME
35      The user visible target name.  The default is "coff-m68k".
36    NAMES_HAVE_UNDERSCORE
37      Whether symbol names have an underscore.
38    ONLY_DECLARE_RELOCS
39      Only declare the relocation howto array.  Don't actually compile
40      it.  The actual array will be picked up in another version of the
41      file.
42    STATIC_RELOCS
43      Make the relocation howto array, and associated functions, static.
44    COFF_COMMON_ADDEND
45      If this is defined, then, for a relocation against a common
46      symbol, the object file holds the value (the size) of the common
47      symbol.  If this is not defined, then, for a relocation against a
48      common symbol, the object file holds zero.  */
49 
50 #define COFF_DEFAULT_SECTION_ALIGNMENT_POWER (2)
51 
52 #ifndef COFF_PAGE_SIZE
53 /* The page size is a guess based on ELF.  */
54 #define COFF_PAGE_SIZE 0x2000
55 #endif
56 
57 #ifndef COFF_COMMON_ADDEND
58 #define RELOC_SPECIAL_FN 0
59 #else
60 static bfd_reloc_status_type m68kcoff_common_addend_special_fn
61   (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
62 
63 #define RELOC_SPECIAL_FN m68kcoff_common_addend_special_fn
64 #endif
65 
66 static bfd_boolean m68k_coff_is_local_label_name (bfd *, const char *);
67 
68 /* On the delta, a symbol starting with L% is local.  We won't see
69    such a symbol on other platforms, so it should be safe to always
70    consider it local here.  */
71 
72 static bfd_boolean
m68k_coff_is_local_label_name(bfd * abfd,const char * name)73 m68k_coff_is_local_label_name (bfd *abfd, const char *name)
74 {
75   if (name[0] == 'L' && name[1] == '%')
76     return TRUE;
77 
78   return _bfd_coff_is_local_label_name (abfd, name);
79 }
80 
81 #ifndef STATIC_RELOCS
82 /* Clean up namespace.  */
83 #define m68kcoff_howto_table	_bfd_m68kcoff_howto_table
84 #define m68k_rtype2howto	_bfd_m68kcoff_rtype2howto
85 #define m68k_howto2rtype	_bfd_m68kcoff_howto2rtype
86 #define m68k_reloc_type_lookup	_bfd_m68kcoff_reloc_type_lookup
87 #define m68k_reloc_name_lookup _bfd_m68kcoff_reloc_name_lookup
88 #endif
89 
90 #ifdef ONLY_DECLARE_RELOCS
91 extern reloc_howto_type m68kcoff_howto_table[];
92 #else
93 #ifdef STATIC_RELOCS
94 static
95 #endif
96 reloc_howto_type m68kcoff_howto_table[] =
97   {
98     HOWTO (R_RELBYTE,	       0,  0,  	8,  FALSE, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "8",	TRUE, 0x000000ff,0x000000ff, FALSE),
99     HOWTO (R_RELWORD,	       0,  1, 	16, FALSE, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "16",	TRUE, 0x0000ffff,0x0000ffff, FALSE),
100     HOWTO (R_RELLONG,	       0,  2, 	32, FALSE, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "32",	TRUE, 0xffffffff,0xffffffff, FALSE),
101     HOWTO (R_PCRBYTE,	       0,  0, 	8,  TRUE,  0, complain_overflow_signed,   RELOC_SPECIAL_FN, "DISP8",    TRUE, 0x000000ff,0x000000ff, FALSE),
102     HOWTO (R_PCRWORD,	       0,  1, 	16, TRUE,  0, complain_overflow_signed,   RELOC_SPECIAL_FN, "DISP16",   TRUE, 0x0000ffff,0x0000ffff, FALSE),
103     HOWTO (R_PCRLONG,	       0,  2, 	32, TRUE,  0, complain_overflow_signed,   RELOC_SPECIAL_FN, "DISP32",   TRUE, 0xffffffff,0xffffffff, FALSE),
104     HOWTO (R_RELLONG_NEG,      0, -2, 	32, FALSE, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "-32",	TRUE, 0xffffffff,0xffffffff, FALSE),
105   };
106 #endif /* not ONLY_DECLARE_RELOCS */
107 
108 #ifndef BADMAG
109 #define BADMAG(x) M68KBADMAG(x)
110 #endif
111 #define M68 1		/* Customize coffcode.h */
112 
113 /* Turn a howto into a reloc number */
114 
115 #ifdef ONLY_DECLARE_RELOCS
116 extern void m68k_rtype2howto (arelent *internal, int relocentry);
117 extern int m68k_howto2rtype (reloc_howto_type *);
118 extern reloc_howto_type * m68k_reloc_type_lookup
119   (bfd *, bfd_reloc_code_real_type);
120 extern reloc_howto_type * m68k_reloc_name_lookup (bfd *, const char *);
121 #else
122 
123 #ifdef STATIC_RELOCS
124 #define STAT_REL static
125 #else
126 #define STAT_REL
127 #endif
128 
129 STAT_REL void m68k_rtype2howto (arelent *, int);
130 STAT_REL int  m68k_howto2rtype (reloc_howto_type *);
131 STAT_REL reloc_howto_type * m68k_reloc_type_lookup (bfd *, bfd_reloc_code_real_type);
132 STAT_REL reloc_howto_type * m68k_reloc_name_lookup (bfd *, const char *);
133 
134 STAT_REL void
m68k_rtype2howto(arelent * internal,int relocentry)135 m68k_rtype2howto (arelent *internal, int relocentry)
136 {
137   switch (relocentry)
138     {
139     case R_RELBYTE:	internal->howto = m68kcoff_howto_table + 0; break;
140     case R_RELWORD:	internal->howto = m68kcoff_howto_table + 1; break;
141     case R_RELLONG:	internal->howto = m68kcoff_howto_table + 2; break;
142     case R_PCRBYTE:	internal->howto = m68kcoff_howto_table + 3; break;
143     case R_PCRWORD:	internal->howto = m68kcoff_howto_table + 4; break;
144     case R_PCRLONG:	internal->howto = m68kcoff_howto_table + 5; break;
145     case R_RELLONG_NEG:	internal->howto = m68kcoff_howto_table + 6; break;
146     }
147 }
148 
149 STAT_REL int
m68k_howto2rtype(reloc_howto_type * internal)150 m68k_howto2rtype (reloc_howto_type * internal)
151 {
152   if (internal->pc_relative)
153     {
154       switch (internal->bitsize)
155 	{
156 	case 32: return R_PCRLONG;
157 	case 16: return R_PCRWORD;
158 	case 8: return R_PCRBYTE;
159 	}
160     }
161   else
162     {
163       switch (internal->bitsize)
164 	{
165 	case 32: return R_RELLONG;
166 	case 16: return R_RELWORD;
167 	case 8: return R_RELBYTE;
168 	}
169     }
170   return R_RELLONG;
171 }
172 
173 STAT_REL reloc_howto_type *
m68k_reloc_type_lookup(bfd * abfd ATTRIBUTE_UNUSED,bfd_reloc_code_real_type code)174 m68k_reloc_type_lookup (bfd *abfd ATTRIBUTE_UNUSED,
175 			bfd_reloc_code_real_type code)
176 {
177   switch (code)
178     {
179     default:			return NULL;
180     case BFD_RELOC_8:		return m68kcoff_howto_table + 0;
181     case BFD_RELOC_16:		return m68kcoff_howto_table + 1;
182     case BFD_RELOC_CTOR:
183     case BFD_RELOC_32:		return m68kcoff_howto_table + 2;
184     case BFD_RELOC_8_PCREL:	return m68kcoff_howto_table + 3;
185     case BFD_RELOC_16_PCREL:	return m68kcoff_howto_table + 4;
186     case BFD_RELOC_32_PCREL:	return m68kcoff_howto_table + 5;
187       /* FIXME: There doesn't seem to be a code for R_RELLONG_NEG.  */
188     }
189   /*NOTREACHED*/
190 }
191 
192 STAT_REL reloc_howto_type *
m68k_reloc_name_lookup(bfd * abfd ATTRIBUTE_UNUSED,const char * r_name)193 m68k_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED,
194 		        const char *r_name)
195 {
196   unsigned int i;
197 
198   for (i = 0;
199        i < sizeof (m68kcoff_howto_table) / sizeof (m68kcoff_howto_table[0]);
200        i++)
201     if (m68kcoff_howto_table[i].name != NULL
202 	&& strcasecmp (m68kcoff_howto_table[i].name, r_name) == 0)
203       return &m68kcoff_howto_table[i];
204 
205   return NULL;
206 }
207 
208 #endif /* not ONLY_DECLARE_RELOCS */
209 
210 #define RTYPE2HOWTO(internal, relocentry) \
211   m68k_rtype2howto(internal, (relocentry)->r_type)
212 
213 #define SELECT_RELOC(external, internal) \
214   external.r_type = m68k_howto2rtype (internal)
215 
216 #define coff_bfd_reloc_type_lookup m68k_reloc_type_lookup
217 #define coff_bfd_reloc_name_lookup m68k_reloc_name_lookup
218 
219 #ifndef COFF_COMMON_ADDEND
220 #ifndef coff_rtype_to_howto
221 
222 #define coff_rtype_to_howto m68kcoff_rtype_to_howto
223 
224 static reloc_howto_type *
m68kcoff_rtype_to_howto(bfd * abfd ATTRIBUTE_UNUSED,asection * sec,struct internal_reloc * rel,struct coff_link_hash_entry * h ATTRIBUTE_UNUSED,struct internal_syment * sym ATTRIBUTE_UNUSED,bfd_vma * addendp)225 m68kcoff_rtype_to_howto (bfd *abfd ATTRIBUTE_UNUSED,
226 			 asection *sec,
227 			 struct internal_reloc *rel,
228 			 struct coff_link_hash_entry *h ATTRIBUTE_UNUSED,
229 			 struct internal_syment *sym ATTRIBUTE_UNUSED,
230 			 bfd_vma *addendp)
231 {
232   arelent relent;
233   reloc_howto_type *howto;
234 
235   relent.howto = NULL;
236   RTYPE2HOWTO (&relent, rel);
237 
238   howto = relent.howto;
239 
240   if (howto != NULL && howto->pc_relative)
241     *addendp += sec->vma;
242 
243   return howto;
244 }
245 
246 #endif /* ! defined (coff_rtype_to_howto) */
247 #endif /* ! defined (COFF_COMMON_ADDEND) */
248 
249 #ifdef COFF_COMMON_ADDEND
250 
251 /* If COFF_COMMON_ADDEND is defined, then when using m68k COFF the
252    value stored in the .text section for a reference to a common
253    symbol is the value itself plus any desired offset.  (taken from
254    work done by Ian Taylor, Cygnus Support, for I386 COFF).  */
255 
256 /* If we are producing relocatable output, we need to do some
257    adjustments to the object file that are not done by the
258    bfd_perform_relocation function.  This function is called by every
259    reloc type to make any required adjustments.  */
260 
261 static bfd_reloc_status_type
m68kcoff_common_addend_special_fn(bfd * abfd,arelent * reloc_entry,asymbol * symbol,void * data,asection * input_section ATTRIBUTE_UNUSED,bfd * output_bfd,char ** error_message ATTRIBUTE_UNUSED)262 m68kcoff_common_addend_special_fn (bfd *abfd,
263 				   arelent *reloc_entry,
264 				   asymbol *symbol,
265 				   void * data,
266 				   asection *input_section ATTRIBUTE_UNUSED,
267 				   bfd *output_bfd,
268 				   char **error_message ATTRIBUTE_UNUSED)
269 {
270   symvalue diff;
271 
272   if (output_bfd == (bfd *) NULL)
273     return bfd_reloc_continue;
274 
275   if (bfd_is_com_section (symbol->section))
276     {
277       /* We are relocating a common symbol.  The current value in the
278 	 object file is ORIG + OFFSET, where ORIG is the value of the
279 	 common symbol as seen by the object file when it was compiled
280 	 (this may be zero if the symbol was undefined) and OFFSET is
281 	 the offset into the common symbol (normally zero, but may be
282 	 non-zero when referring to a field in a common structure).
283 	 ORIG is the negative of reloc_entry->addend, which is set by
284 	 the CALC_ADDEND macro below.  We want to replace the value in
285 	 the object file with NEW + OFFSET, where NEW is the value of
286 	 the common symbol which we are going to put in the final
287 	 object file.  NEW is symbol->value.  */
288       diff = symbol->value + reloc_entry->addend;
289     }
290   else
291     {
292       /* For some reason bfd_perform_relocation always effectively
293 	 ignores the addend for a COFF target when producing
294 	 relocatable output.  This seems to be always wrong for 386
295 	 COFF, so we handle the addend here instead.  */
296       diff = reloc_entry->addend;
297     }
298 
299 #define DOIT(x) \
300   x = ((x & ~howto->dst_mask) | (((x & howto->src_mask) + diff) & howto->dst_mask))
301 
302   if (diff != 0)
303     {
304       reloc_howto_type *howto = reloc_entry->howto;
305       unsigned char *addr = (unsigned char *) data + reloc_entry->address;
306 
307       switch (howto->size)
308 	{
309 	case 0:
310 	  {
311 	    char x = bfd_get_8 (abfd, addr);
312 	    DOIT (x);
313 	    bfd_put_8 (abfd, x, addr);
314 	  }
315 	  break;
316 
317 	case 1:
318 	  {
319 	    short x = bfd_get_16 (abfd, addr);
320 	    DOIT (x);
321 	    bfd_put_16 (abfd, (bfd_vma) x, addr);
322 	  }
323 	  break;
324 
325 	case 2:
326 	  {
327 	    long x = bfd_get_32 (abfd, addr);
328 	    DOIT (x);
329 	    bfd_put_32 (abfd, (bfd_vma) x, addr);
330 	  }
331 	  break;
332 
333 	default:
334 	  abort ();
335 	}
336     }
337 
338   /* Now let bfd_perform_relocation finish everything up.  */
339   return bfd_reloc_continue;
340 }
341 
342 /* Compute the addend of a reloc.  If the reloc is to a common symbol,
343    the object file contains the value of the common symbol.  By the
344    time this is called, the linker may be using a different symbol
345    from a different object file with a different value.  Therefore, we
346    hack wildly to locate the original symbol from this file so that we
347    can make the correct adjustment.  This macro sets coffsym to the
348    symbol from the original file, and uses it to set the addend value
349    correctly.  If this is not a common symbol, the usual addend
350    calculation is done, except that an additional tweak is needed for
351    PC relative relocs.
352    FIXME: This macro refers to symbols and asect; these are from the
353    calling function, not the macro arguments.  */
354 
355 #define CALC_ADDEND(abfd, ptr, reloc, cache_ptr)		\
356   {								\
357     coff_symbol_type *coffsym = (coff_symbol_type *) NULL;	\
358     if (ptr && bfd_asymbol_bfd (ptr) != abfd)			\
359       coffsym = (obj_symbols (abfd)				\
360 	         + (cache_ptr->sym_ptr_ptr - symbols));		\
361     else if (ptr)						\
362       coffsym = coff_symbol_from (abfd, ptr);			\
363     if (coffsym != (coff_symbol_type *) NULL			\
364 	&& coffsym->native->u.syment.n_scnum == 0)		\
365       cache_ptr->addend = - coffsym->native->u.syment.n_value;	\
366     else if (ptr && bfd_asymbol_bfd (ptr) == abfd		\
367 	     && ptr->section != (asection *) NULL)		\
368       cache_ptr->addend = - (ptr->section->vma + ptr->value);	\
369     else							\
370       cache_ptr->addend = 0;					\
371     if (ptr && (reloc.r_type == R_PCRBYTE			\
372 		|| reloc.r_type == R_PCRWORD			\
373 		|| reloc.r_type == R_PCRLONG))			\
374       cache_ptr->addend += asect->vma;				\
375   }
376 
377 #ifndef coff_rtype_to_howto
378 
379 /* coff-m68k.c uses the special COFF backend linker.  We need to
380    adjust common symbols.  */
381 
382 static reloc_howto_type *
m68kcoff_common_addend_rtype_to_howto(bfd * abfd ATTRIBUTE_UNUSED,asection * sec,struct internal_reloc * rel,struct coff_link_hash_entry * h,struct internal_syment * sym,bfd_vma * addendp)383 m68kcoff_common_addend_rtype_to_howto (bfd *abfd ATTRIBUTE_UNUSED,
384 				       asection *sec,
385 				       struct internal_reloc *rel,
386 				       struct coff_link_hash_entry *h,
387 				       struct internal_syment *sym,
388 				       bfd_vma *addendp)
389 {
390   arelent relent;
391   reloc_howto_type *howto;
392 
393   relent.howto = NULL;
394   RTYPE2HOWTO (&relent, rel);
395 
396   howto = relent.howto;
397 
398   if (howto->pc_relative)
399     *addendp += sec->vma;
400 
401   if (sym != NULL && sym->n_scnum == 0 && sym->n_value != 0)
402     {
403       /* This is a common symbol.  The section contents include the
404 	 size (sym->n_value) as an addend.  The relocate_section
405 	 function will be adding in the final value of the symbol.  We
406 	 need to subtract out the current size in order to get the
407 	 correct result.  */
408       BFD_ASSERT (h != NULL);
409       *addendp -= sym->n_value;
410     }
411 
412   /* If the output symbol is common (in which case this must be a
413      relocatable link), we need to add in the final size of the
414      common symbol.  */
415   if (h != NULL && h->root.type == bfd_link_hash_common)
416     *addendp += h->root.u.c.size;
417 
418   return howto;
419 }
420 
421 #define coff_rtype_to_howto m68kcoff_common_addend_rtype_to_howto
422 
423 #endif /* ! defined (coff_rtype_to_howto) */
424 
425 #endif /* COFF_COMMON_ADDEND */
426 
427 #if !defined ONLY_DECLARE_RELOCS && ! defined STATIC_RELOCS
428 /* Given a .data section and a .emreloc in-memory section, store
429    relocation information into the .emreloc section which can be
430    used at runtime to relocate the section.  This is called by the
431    linker when the --embedded-relocs switch is used.  This is called
432    after the add_symbols entry point has been called for all the
433    objects, and before the final_link entry point is called.  */
434 
435 bfd_boolean
bfd_m68k_coff_create_embedded_relocs(bfd * abfd,struct bfd_link_info * info,asection * datasec,asection * relsec,char ** errmsg)436 bfd_m68k_coff_create_embedded_relocs (bfd *abfd,
437 				      struct bfd_link_info *info,
438 				      asection *datasec,
439 				      asection *relsec,
440 				      char **errmsg)
441 {
442   char *extsyms;
443   bfd_size_type symesz;
444   struct internal_reloc *irel, *irelend;
445   bfd_byte *p;
446   bfd_size_type amt;
447 
448   BFD_ASSERT (! info->relocatable);
449 
450   *errmsg = NULL;
451 
452   if (datasec->reloc_count == 0)
453     return TRUE;
454 
455   extsyms = obj_coff_external_syms (abfd);
456   symesz = bfd_coff_symesz (abfd);
457 
458   irel = _bfd_coff_read_internal_relocs (abfd, datasec, TRUE, NULL, FALSE,
459 					 NULL);
460   irelend = irel + datasec->reloc_count;
461 
462   amt = (bfd_size_type) datasec->reloc_count * 12;
463   relsec->contents = (bfd_byte *) bfd_alloc (abfd, amt);
464   if (relsec->contents == NULL)
465     return FALSE;
466 
467   p = relsec->contents;
468 
469   for (; irel < irelend; irel++, p += 12)
470     {
471       asection *targetsec;
472 
473       /* We are going to write a four byte longword into the runtime
474        reloc section.  The longword will be the address in the data
475        section which must be relocated.  It is followed by the name
476        of the target section NUL-padded or truncated to 8
477        characters.  */
478 
479       /* We can only relocate absolute longword relocs at run time.  */
480       if (irel->r_type != R_RELLONG)
481 	{
482 	  *errmsg = _("unsupported reloc type");
483 	  bfd_set_error (bfd_error_bad_value);
484 	  return FALSE;
485 	}
486 
487       if (irel->r_symndx == -1)
488 	targetsec = bfd_abs_section_ptr;
489       else
490 	{
491 	  struct coff_link_hash_entry *h;
492 
493 	  h = obj_coff_sym_hashes (abfd)[irel->r_symndx];
494 	  if (h == NULL)
495 	    {
496 	      struct internal_syment isym;
497 
498 	      bfd_coff_swap_sym_in (abfd, extsyms + symesz * irel->r_symndx,
499 				    &isym);
500 	      targetsec = coff_section_from_bfd_index (abfd, isym.n_scnum);
501 	    }
502 	  else if (h->root.type == bfd_link_hash_defined
503 		   || h->root.type == bfd_link_hash_defweak)
504 	    targetsec = h->root.u.def.section;
505 	  else
506 	    targetsec = NULL;
507 	}
508 
509       bfd_put_32 (abfd,
510 		  (irel->r_vaddr - datasec->vma + datasec->output_offset), p);
511       memset (p + 4, 0, 8);
512       if (targetsec != NULL)
513 	strncpy ((char *) p + 4, targetsec->output_section->name, 8);
514     }
515 
516   return TRUE;
517 }
518 #endif /* neither ONLY_DECLARE_RELOCS not STATIC_RELOCS  */
519 
520 #define coff_bfd_is_local_label_name m68k_coff_is_local_label_name
521 
522 #define coff_relocate_section _bfd_coff_generic_relocate_section
523 
524 #ifndef bfd_pe_print_pdata
525 #define bfd_pe_print_pdata	NULL
526 #endif
527 
528 #include "coffcode.h"
529 
530 #ifndef TARGET_SYM
531 #define TARGET_SYM m68k_coff_vec
532 #endif
533 
534 #ifndef TARGET_NAME
535 #define TARGET_NAME "coff-m68k"
536 #endif
537 
538 #ifdef NAMES_HAVE_UNDERSCORE
539 CREATE_BIG_COFF_TARGET_VEC (TARGET_SYM, TARGET_NAME, D_PAGED, 0, '_', NULL, COFF_SWAP_TABLE)
540 #else
541 CREATE_BIG_COFF_TARGET_VEC (TARGET_SYM, TARGET_NAME, D_PAGED, 0, 0, NULL, COFF_SWAP_TABLE)
542 #endif
543