1 /* BFD support for handling relocation entries.
2 Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
3 Written by Cygnus Support.
5 This file is part of BFD, the Binary File Descriptor library.
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 2 of the License, or
10 (at your option) any later version.
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.
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., 675 Mass Ave, Cambridge, MA 02139, USA. */
25 BFD maintains relocations in much the same way it maintains
26 symbols: they are left alone until required, then read in
27 en-mass and translated into an internal form. A common
28 routine <<bfd_perform_relocation>> acts upon the
29 canonical form to do the fixup.
31 Relocations are maintained on a per section basis,
32 while symbols are maintained on a per BFD basis.
34 All that a back end has to do to fit the BFD interface is to create
35 a <<struct reloc_cache_entry>> for each relocation
36 in a particular section, and fill in the right bits of the structures.
51 typedef arelent, howto manager, Relocations, Relocations
56 This is the structure of a relocation entry:
60 .typedef enum bfd_reloc_status
62 . {* No errors detected *}
65 . {* The relocation was performed, but there was an overflow. *}
68 . {* The address to relocate was not within the section supplied. *}
69 . bfd_reloc_outofrange,
71 . {* Used by special functions *}
74 . {* Unsupported relocation size requested. *}
75 . bfd_reloc_notsupported,
80 . {* The symbol to relocate against was undefined. *}
81 . bfd_reloc_undefined,
83 . {* The relocation was performed, but may not be ok - presently
84 . generated only when linking i960 coff files with i960 b.out
85 . symbols. If this type is returned, the error_message argument
86 . to bfd_perform_relocation will be set. *}
89 . bfd_reloc_status_type;
92 .typedef struct reloc_cache_entry
94 . {* A pointer into the canonical table of pointers *}
95 . struct symbol_cache_entry **sym_ptr_ptr;
97 . {* offset in section *}
98 . bfd_size_type address;
100 . {* addend for relocation value *}
103 . {* Pointer to how to perform the required relocation *}
104 . const struct reloc_howto_struct *howto;
113 Here is a description of each of the fields within an <<arelent>>:
117 The symbol table pointer points to a pointer to the symbol
118 associated with the relocation request. It is
119 the pointer into the table returned by the back end's
120 <<get_symtab>> action. @xref{Symbols}. The symbol is referenced
121 through a pointer to a pointer so that tools like the linker
122 can fix up all the symbols of the same name by modifying only
123 one pointer. The relocation routine looks in the symbol and
124 uses the base of the section the symbol is attached to and the
125 value of the symbol as the initial relocation offset. If the
126 symbol pointer is zero, then the section provided is looked up.
130 The <<address>> field gives the offset in bytes from the base of
131 the section data which owns the relocation record to the first
132 byte of relocatable information. The actual data relocated
133 will be relative to this point; for example, a relocation
134 type which modifies the bottom two bytes of a four byte word
135 would not touch the first byte pointed to in a big endian
140 The <<addend>> is a value provided by the back end to be added (!)
141 to the relocation offset. Its interpretation is dependent upon
142 the howto. For example, on the 68k the code:
148 | return foo[0x12345678];
151 Could be compiled into:
154 | moveb @@#12345678,d0
160 This could create a reloc pointing to <<foo>>, but leave the
161 offset in the data, something like:
164 |RELOCATION RECORDS FOR [.text]:
168 |00000000 4e56 fffc ; linkw fp,#-4
169 |00000004 1039 1234 5678 ; moveb @@#12345678,d0
170 |0000000a 49c0 ; extbl d0
171 |0000000c 4e5e ; unlk fp
175 Using coff and an 88k, some instructions don't have enough
176 space in them to represent the full address range, and
177 pointers have to be loaded in two parts. So you'd get something like:
180 | or.u r13,r0,hi16(_foo+0x12345678)
181 | ld.b r2,r13,lo16(_foo+0x12345678)
185 This should create two relocs, both pointing to <<_foo>>, and with
186 0x12340000 in their addend field. The data would consist of:
189 |RELOCATION RECORDS FOR [.text]:
191 |00000002 HVRT16 _foo+0x12340000
192 |00000006 LVRT16 _foo+0x12340000
194 |00000000 5da05678 ; or.u r13,r0,0x5678
195 |00000004 1c4d5678 ; ld.b r2,r13,0x5678
196 |00000008 f400c001 ; jmp r1
199 The relocation routine digs out the value from the data, adds
200 it to the addend to get the original offset, and then adds the
201 value of <<_foo>>. Note that all 32 bits have to be kept around
202 somewhere, to cope with carry from bit 15 to bit 16.
204 One further example is the sparc and the a.out format. The
205 sparc has a similar problem to the 88k, in that some
206 instructions don't have room for an entire offset, but on the
207 sparc the parts are created in odd sized lumps. The designers of
208 the a.out format chose to not use the data within the section
209 for storing part of the offset; all the offset is kept within
210 the reloc. Anything in the data should be ignored.
213 | sethi %hi(_foo+0x12345678),%g2
214 | ldsb [%g2+%lo(_foo+0x12345678)],%i0
218 Both relocs contain a pointer to <<foo>>, and the offsets
222 |RELOCATION RECORDS FOR [.text]:
224 |00000004 HI22 _foo+0x12345678
225 |00000008 LO10 _foo+0x12345678
227 |00000000 9de3bf90 ; save %sp,-112,%sp
228 |00000004 05000000 ; sethi %hi(_foo+0),%g2
229 |00000008 f048a000 ; ldsb [%g2+%lo(_foo+0)],%i0
230 |0000000c 81c7e008 ; ret
231 |00000010 81e80000 ; restore
236 The <<howto>> field can be imagined as a
237 relocation instruction. It is a pointer to a structure which
238 contains information on what to do with all of the other
239 information in the reloc record and data section. A back end
240 would normally have a relocation instruction set and turn
241 relocations into pointers to the correct structure on input -
242 but it would be possible to create each howto field on demand.
248 <<enum complain_overflow>>
250 Indicates what sort of overflow checking should be done when
251 performing a relocation.
255 .enum complain_overflow
257 . {* Do not complain on overflow. *}
258 . complain_overflow_dont,
260 . {* Complain if the bitfield overflows, whether it is considered
261 . as signed or unsigned. *}
262 . complain_overflow_bitfield,
264 . {* Complain if the value overflows when considered as signed
266 . complain_overflow_signed,
268 . {* Complain if the value overflows when considered as an
269 . unsigned number. *}
270 . complain_overflow_unsigned
279 The <<reloc_howto_type>> is a structure which contains all the
280 information that libbfd needs to know to tie up a back end's data.
283 .struct symbol_cache_entry; {* Forward declaration *}
285 .typedef unsigned char bfd_byte;
287 .struct reloc_howto_struct
289 . {* The type field has mainly a documetary use - the back end can
290 . do what it wants with it, though normally the back end's
291 . external idea of what a reloc number is stored
292 . in this field. For example, a PC relative word relocation
293 . in a coff environment has the type 023 - because that's
294 . what the outside world calls a R_PCRWORD reloc. *}
297 . {* The value the final relocation is shifted right by. This drops
298 . unwanted data from the relocation. *}
299 . unsigned int rightshift;
301 . {* The size of the item to be relocated. This is *not* a
302 . power-of-two measure. To get the number of bytes operated
303 . on by a type of relocation, use bfd_get_reloc_size. *}
306 . {* The number of bits in the item to be relocated. This is used
307 . when doing overflow checking. *}
308 . unsigned int bitsize;
310 . {* Notes that the relocation is relative to the location in the
311 . data section of the addend. The relocation function will
312 . subtract from the relocation value the address of the location
313 . being relocated. *}
314 . boolean pc_relative;
316 . {* The bit position of the reloc value in the destination.
317 . The relocated value is left shifted by this amount. *}
318 . unsigned int bitpos;
320 . {* What type of overflow error should be checked for when
322 . enum complain_overflow complain_on_overflow;
324 . {* If this field is non null, then the supplied function is
325 . called rather than the normal function. This allows really
326 . strange relocation methods to be accomodated (e.g., i960 callj
328 . bfd_reloc_status_type (*special_function)
329 . PARAMS ((bfd *abfd,
330 . arelent *reloc_entry,
331 . struct symbol_cache_entry *symbol,
333 . asection *input_section,
335 . char **error_message));
338 . {* If this field is non null, then the supplied function is
339 . called rather than the normal function. This is similar
340 . to special_function (previous), but takes different arguments,
341 . and is used for the new linking code. *}
342 . bfd_reloc_status_type (*special_function1)
343 . PARAMS((const reloc_howto_type *howto,
345 . bfd_vma relocation,
346 . bfd_byte *location));
348 . {* The textual name of the relocation type. *}
351 . {* When performing a partial link, some formats must modify the
352 . relocations rather than the data - this flag signals this.*}
353 . boolean partial_inplace;
355 . {* The src_mask selects which parts of the read in data
356 . are to be used in the relocation sum. E.g., if this was an 8 bit
357 . bit of data which we read and relocated, this would be
358 . 0x000000ff. When we have relocs which have an addend, such as
359 . sun4 extended relocs, the value in the offset part of a
360 . relocating field is garbage so we never use it. In this case
361 . the mask would be 0x00000000. *}
364 . {* The dst_mask selects which parts of the instruction are replaced
365 . into the instruction. In most cases src_mask == dst_mask,
366 . except in the above special case, where dst_mask would be
367 . 0x000000ff, and src_mask would be 0x00000000. *}
370 . {* When some formats create PC relative instructions, they leave
371 . the value of the pc of the place being relocated in the offset
372 . slot of the instruction, so that a PC relative relocation can
373 . be made just by adding in an ordinary offset (e.g., sun3 a.out).
374 . Some formats leave the displacement part of an instruction
375 . empty (e.g., m88k bcs); this flag signals the fact.*}
376 . boolean pcrel_offset;
379 .typedef struct reloc_howto_struct reloc_howto_type;
388 The HOWTO define is horrible and will go away.
391 .#define HOWTO(C, R,S,B, P, BI, O, SF, NAME, INPLACE, MASKSRC, MASKDST, PC) \
392 . {(unsigned)C,R,S,B, P, BI, O,SF, 0,NAME,INPLACE,MASKSRC,MASKDST,PC}
393 .#define HOWTO2(C, R,S,B, P, BI, O, SF, SF1,NAME, INPLACE, MASKSRC, MASKDST, PC) \
394 . {(unsigned)C,R,S,B, P, BI, O,SF, SF1,NAME,INPLACE,MASKSRC,MASKDST,PC}
397 And will be replaced with the totally magic way. But for the
398 moment, we are compatible, so do it this way.
401 .#define NEWHOWTO( FUNCTION, NAME,SIZE,REL,IN) HOWTO(0,0,SIZE,0,REL,0,complain_overflow_dont,FUNCTION, NAME,false,0,0,IN)
404 Helper routine to turn a symbol into a relocation value.
406 .#define HOWTO_PREPARE(relocation, symbol) \
408 . if (symbol != (asymbol *)NULL) { \
409 . if (bfd_is_com_section (symbol->section)) { \
413 . relocation = symbol->value; \
425 int bfd_get_reloc_size (const reloc_howto_type *);
428 For a reloc_howto_type that operates on a fixed number of bytes,
429 this returns the number of bytes operated on.
433 bfd_get_reloc_size (howto)
434 const reloc_howto_type *howto;
454 How relocs are tied together in an <<asection>>:
456 .typedef struct relent_chain {
458 . struct relent_chain *next;
467 bfd_perform_relocation
470 bfd_reloc_status_type
471 bfd_perform_relocation
473 arelent *reloc_entry,
475 asection *input_section,
477 char **error_message);
480 If @var{output_bfd} is supplied to this function, the
481 generated image will be relocatable; the relocations are
482 copied to the output file after they have been changed to
483 reflect the new state of the world. There are two ways of
484 reflecting the results of partial linkage in an output file:
485 by modifying the output data in place, and by modifying the
486 relocation record. Some native formats (e.g., basic a.out and
487 basic coff) have no way of specifying an addend in the
488 relocation type, so the addend has to go in the output data.
489 This is no big deal since in these formats the output data
490 slot will always be big enough for the addend. Complex reloc
491 types with addends were invented to solve just this problem.
492 The @var{error_message} argument is set to an error message if
493 this return @code{bfd_reloc_dangerous}.
498 bfd_reloc_status_type
499 bfd_perform_relocation (abfd, reloc_entry, data, input_section, output_bfd,
502 arelent *reloc_entry;
504 asection *input_section;
506 char **error_message;
509 bfd_reloc_status_type flag = bfd_reloc_ok;
510 bfd_size_type addr = reloc_entry->address;
511 bfd_vma output_base = 0;
512 const reloc_howto_type *howto = reloc_entry->howto;
513 asection *reloc_target_output_section;
516 symbol = *(reloc_entry->sym_ptr_ptr);
517 if (bfd_is_abs_section (symbol->section)
518 && output_bfd != (bfd *) NULL)
520 reloc_entry->address += input_section->output_offset;
524 /* If we are not producing relocateable output, return an error if
525 the symbol is not defined. An undefined weak symbol is
526 considered to have a value of zero (SVR4 ABI, p. 4-27). */
527 if (bfd_is_und_section (symbol->section)
528 && (symbol->flags & BSF_WEAK) == 0
529 && output_bfd == (bfd *) NULL)
530 flag = bfd_reloc_undefined;
532 /* If there is a function supplied to handle this relocation type,
533 call it. It'll return `bfd_reloc_continue' if further processing
535 if (howto->special_function)
537 bfd_reloc_status_type cont;
538 cont = howto->special_function (abfd, reloc_entry, symbol, data,
539 input_section, output_bfd,
541 if (cont != bfd_reloc_continue)
545 /* Is the address of the relocation really within the section? */
546 if (reloc_entry->address > input_section->_cooked_size)
547 return bfd_reloc_outofrange;
549 /* Work out which section the relocation is targetted at and the
550 initial relocation command value. */
552 /* Get symbol value. (Common symbols are special.) */
553 if (bfd_is_com_section (symbol->section))
556 relocation = symbol->value;
559 reloc_target_output_section = symbol->section->output_section;
561 /* Convert input-section-relative symbol value to absolute. */
562 if (output_bfd && howto->partial_inplace == false)
565 output_base = reloc_target_output_section->vma;
567 relocation += output_base + symbol->section->output_offset;
569 /* Add in supplied addend. */
570 relocation += reloc_entry->addend;
572 /* Here the variable relocation holds the final address of the
573 symbol we are relocating against, plus any addend. */
575 if (howto->pc_relative == true)
577 /* This is a PC relative relocation. We want to set RELOCATION
578 to the distance between the address of the symbol and the
579 location. RELOCATION is already the address of the symbol.
581 We start by subtracting the address of the section containing
584 If pcrel_offset is set, we must further subtract the position
585 of the location within the section. Some targets arrange for
586 the addend to be the negative of the position of the location
587 within the section; for example, i386-aout does this. For
588 i386-aout, pcrel_offset is false. Some other targets do not
589 include the position of the location; for example, m88kbcs,
590 or ELF. For those targets, pcrel_offset is true.
592 If we are producing relocateable output, then we must ensure
593 that this reloc will be correctly computed when the final
594 relocation is done. If pcrel_offset is false we want to wind
595 up with the negative of the location within the section,
596 which means we must adjust the existing addend by the change
597 in the location within the section. If pcrel_offset is true
598 we do not want to adjust the existing addend at all.
600 FIXME: This seems logical to me, but for the case of
601 producing relocateable output it is not what the code
602 actually does. I don't want to change it, because it seems
603 far too likely that something will break. */
606 input_section->output_section->vma + input_section->output_offset;
608 if (howto->pcrel_offset == true)
609 relocation -= reloc_entry->address;
612 if (output_bfd != (bfd *) NULL)
614 if (howto->partial_inplace == false)
616 /* This is a partial relocation, and we want to apply the relocation
617 to the reloc entry rather than the raw data. Modify the reloc
618 inplace to reflect what we now know. */
619 reloc_entry->addend = relocation;
620 reloc_entry->address += input_section->output_offset;
625 /* This is a partial relocation, but inplace, so modify the
628 If we've relocated with a symbol with a section, change
629 into a ref to the section belonging to the symbol. */
631 reloc_entry->address += input_section->output_offset;
634 if (abfd->xvec->flavour == bfd_target_coff_flavour
635 && strcmp (abfd->xvec->name, "aixcoff-rs6000") != 0
636 && strcmp (abfd->xvec->name, "coff-Intel-little") != 0
637 && strcmp (abfd->xvec->name, "coff-Intel-big") != 0)
640 /* For m68k-coff, the addend was being subtracted twice during
641 relocation with -r. Removing the line below this comment
642 fixes that problem; see PR 2953.
644 However, Ian wrote the following, regarding removing the line below,
645 which explains why it is still enabled: --djm
647 If you put a patch like that into BFD you need to check all the COFF
648 linkers. I am fairly certain that patch will break coff-i386 (e.g.,
649 SCO); see coff_i386_reloc in coff-i386.c where I worked around the
650 problem in a different way. There may very well be a reason that the
651 code works as it does.
653 Hmmm. The first obvious point is that bfd_perform_relocation should
654 not have any tests that depend upon the flavour. It's seem like
655 entirely the wrong place for such a thing. The second obvious point
656 is that the current code ignores the reloc addend when producing
657 relocateable output for COFF. That's peculiar. In fact, I really
658 have no idea what the point of the line you want to remove is.
660 A typical COFF reloc subtracts the old value of the symbol and adds in
661 the new value to the location in the object file (if it's a pc
662 relative reloc it adds the difference between the symbol value and the
663 location). When relocating we need to preserve that property.
665 BFD handles this by setting the addend to the negative of the old
666 value of the symbol. Unfortunately it handles common symbols in a
667 non-standard way (it doesn't subtract the old value) but that's a
668 different story (we can't change it without losing backward
669 compatibility with old object files) (coff-i386 does subtract the old
670 value, to be compatible with existing coff-i386 targets, like SCO).
672 So everything works fine when not producing relocateable output. When
673 we are producing relocateable output, logically we should do exactly
674 what we do when not producing relocateable output. Therefore, your
675 patch is correct. In fact, it should probably always just set
676 reloc_entry->addend to 0 for all cases, since it is, in fact, going to
677 add the value into the object file. This won't hurt the COFF code,
678 which doesn't use the addend; I'm not sure what it will do to other
679 formats (the thing to check for would be whether any formats both use
680 the addend and set partial_inplace).
682 When I wanted to make coff-i386 produce relocateable output, I ran
683 into the problem that you are running into: I wanted to remove that
684 line. Rather than risk it, I made the coff-i386 relocs use a special
685 function; it's coff_i386_reloc in coff-i386.c. The function
686 specifically adds the addend field into the object file, knowing that
687 bfd_perform_relocation is not going to. If you remove that line, then
688 coff-i386.c will wind up adding the addend field in twice. It's
689 trivial to fix; it just needs to be done.
691 The problem with removing the line is just that it may break some
692 working code. With BFD it's hard to be sure of anything. The right
693 way to deal with this is simply to build and test at least all the
694 supported COFF targets. It should be straightforward if time and disk
695 space consuming. For each target:
697 2) generate some executable, and link it using -r (I would
698 probably use paranoia.o and link against newlib/libc.a, which
699 for all the supported targets would be available in
700 /usr/cygnus/progressive/H-host/target/lib/libc.a).
701 3) make the change to reloc.c
702 4) rebuild the linker
704 6) if the resulting object files are the same, you have at least
706 7) if they are different you have to figure out which version is
709 relocation -= reloc_entry->addend;
711 reloc_entry->addend = 0;
715 reloc_entry->addend = relocation;
721 reloc_entry->addend = 0;
724 /* FIXME: This overflow checking is incomplete, because the value
725 might have overflowed before we get here. For a correct check we
726 need to compute the value in a size larger than bitsize, but we
727 can't reasonably do that for a reloc the same size as a host
729 FIXME: We should also do overflow checking on the result after
730 adding in the value contained in the object file. */
731 if (howto->complain_on_overflow != complain_overflow_dont)
735 /* Get the value that will be used for the relocation, but
736 starting at bit position zero. */
737 if (howto->rightshift > howto->bitpos)
738 check = relocation >> (howto->rightshift - howto->bitpos);
740 check = relocation << (howto->bitpos - howto->rightshift);
741 switch (howto->complain_on_overflow)
743 case complain_overflow_signed:
745 /* Assumes two's complement. */
746 bfd_signed_vma reloc_signed_max = (1 << (howto->bitsize - 1)) - 1;
747 bfd_signed_vma reloc_signed_min = ~reloc_signed_max;
749 /* The above right shift is incorrect for a signed value.
750 Fix it up by forcing on the upper bits. */
751 if (howto->rightshift > howto->bitpos
752 && (bfd_signed_vma) relocation < 0)
753 check |= ((bfd_vma) - 1
755 >> (howto->rightshift - howto->bitpos)));
756 if ((bfd_signed_vma) check > reloc_signed_max
757 || (bfd_signed_vma) check < reloc_signed_min)
758 flag = bfd_reloc_overflow;
761 case complain_overflow_unsigned:
763 /* Assumes two's complement. This expression avoids
764 overflow if howto->bitsize is the number of bits in
766 bfd_vma reloc_unsigned_max =
767 (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
769 if ((bfd_vma) check > reloc_unsigned_max)
770 flag = bfd_reloc_overflow;
773 case complain_overflow_bitfield:
775 /* Assumes two's complement. This expression avoids
776 overflow if howto->bitsize is the number of bits in
778 bfd_vma reloc_bits = (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
780 if (((bfd_vma) check & ~reloc_bits) != 0
781 && ((bfd_vma) check & ~reloc_bits) != (-1 & ~reloc_bits))
783 /* The above right shift is incorrect for a signed
784 value. See if turning on the upper bits fixes the
786 if (howto->rightshift > howto->bitpos
787 && (bfd_signed_vma) relocation < 0)
789 check |= ((bfd_vma) - 1
791 >> (howto->rightshift - howto->bitpos)));
792 if (((bfd_vma) check & ~reloc_bits) != (-1 & ~reloc_bits))
793 flag = bfd_reloc_overflow;
796 flag = bfd_reloc_overflow;
806 Either we are relocating all the way, or we don't want to apply
807 the relocation to the reloc entry (probably because there isn't
808 any room in the output format to describe addends to relocs)
811 /* The cast to bfd_vma avoids a bug in the Alpha OSF/1 C compiler
812 (OSF version 1.3, compiler version 3.11). It miscompiles the
826 x <<= (unsigned long) s.i0;
830 printf ("succeeded (%lx)\n", x);
834 relocation >>= (bfd_vma) howto->rightshift;
836 /* Shift everything up to where it's going to be used */
838 relocation <<= (bfd_vma) howto->bitpos;
840 /* Wait for the day when all have the mask in them */
843 i instruction to be left alone
844 o offset within instruction
845 r relocation offset to apply
854 i i i i i o o o o o from bfd_get<size>
855 and S S S S S to get the size offset we want
856 + r r r r r r r r r r to get the final value to place
857 and D D D D D to chop to right size
858 -----------------------
861 ... i i i i i o o o o o from bfd_get<size>
862 and N N N N N get instruction
863 -----------------------
869 -----------------------
870 R R R R R R R R R R put into bfd_put<size>
874 x = ( (x & ~howto->dst_mask) | (((x & howto->src_mask) + relocation) & howto->dst_mask))
880 char x = bfd_get_8 (abfd, (char *) data + addr);
882 bfd_put_8 (abfd, x, (unsigned char *) data + addr);
889 short x = bfd_get_16 (abfd, (bfd_byte *) data + addr);
891 bfd_put_16 (abfd, x, (unsigned char *) data + addr);
897 long x = bfd_get_32 (abfd, (bfd_byte *) data + addr);
899 bfd_put_32 (abfd, x, (bfd_byte *) data + addr);
904 long x = bfd_get_32 (abfd, (bfd_byte *) data + addr);
905 relocation = -relocation;
907 bfd_put_32 (abfd, x, (bfd_byte *) data + addr);
919 bfd_vma x = bfd_get_64 (abfd, (bfd_byte *) data + addr);
921 bfd_put_64 (abfd, x, (bfd_byte *) data + addr);
928 return bfd_reloc_other;
934 /* This relocation routine is used by some of the backend linkers.
935 They do not construct asymbol or arelent structures, so there is no
936 reason for them to use bfd_perform_relocation. Also,
937 bfd_perform_relocation is so hacked up it is easier to write a new
938 function than to try to deal with it.
940 This routine does a final relocation. It should not be used when
941 generating relocateable output.
943 FIXME: This routine ignores any special_function in the HOWTO,
944 since the existing special_function values have been written for
945 bfd_perform_relocation.
947 HOWTO is the reloc howto information.
948 INPUT_BFD is the BFD which the reloc applies to.
949 INPUT_SECTION is the section which the reloc applies to.
950 CONTENTS is the contents of the section.
951 ADDRESS is the address of the reloc within INPUT_SECTION.
952 VALUE is the value of the symbol the reloc refers to.
953 ADDEND is the addend of the reloc. */
955 bfd_reloc_status_type
956 _bfd_final_link_relocate (howto, input_bfd, input_section, contents, address,
958 const reloc_howto_type *howto;
960 asection *input_section;
968 /* Sanity check the address. */
969 if (address > input_section->_cooked_size)
970 return bfd_reloc_outofrange;
972 /* This function assumes that we are dealing with a basic relocation
973 against a symbol. We want to compute the value of the symbol to
974 relocate to. This is just VALUE, the value of the symbol, plus
975 ADDEND, any addend associated with the reloc. */
976 relocation = value + addend;
978 /* If the relocation is PC relative, we want to set RELOCATION to
979 the distance between the symbol (currently in RELOCATION) and the
980 location we are relocating. Some targets (e.g., i386-aout)
981 arrange for the contents of the section to be the negative of the
982 offset of the location within the section; for such targets
983 pcrel_offset is false. Other targets (e.g., m88kbcs or ELF)
984 simply leave the contents of the section as zero; for such
985 targets pcrel_offset is true. If pcrel_offset is false we do not
986 need to subtract out the offset of the location within the
987 section (which is just ADDRESS). */
988 if (howto->pc_relative)
990 relocation -= (input_section->output_section->vma
991 + input_section->output_offset);
992 if (howto->pcrel_offset)
993 relocation -= address;
996 if(howto->special_function1) {
997 bfd_reloc_status_type cont;
998 cont = (*howto->special_function1)(howto, input_bfd, relocation,
1000 if (cont != bfd_reloc_continue)
1003 return _bfd_relocate_contents (howto, input_bfd, relocation,
1004 contents + address);
1007 /* Relocate a given location using a given value and howto. */
1009 bfd_reloc_status_type
1010 _bfd_relocate_contents (howto, input_bfd, relocation, location)
1011 const reloc_howto_type *howto;
1020 /* If the size is negative, negate RELOCATION. This isn't very
1022 if (howto->size < 0)
1023 relocation = -relocation;
1025 /* Get the value we are going to relocate. */
1026 size = bfd_get_reloc_size (howto);
1033 x = bfd_get_8 (input_bfd, location);
1036 x = bfd_get_16 (input_bfd, location);
1039 x = bfd_get_32 (input_bfd, location);
1043 x = bfd_get_64 (input_bfd, location);
1050 /* Check for overflow. FIXME: We may drop bits during the addition
1051 which we don't check for. We must either check at every single
1052 operation, which would be tedious, or we must do the computations
1053 in a type larger than bfd_vma, which would be inefficient. */
1055 if (howto->complain_on_overflow != complain_overflow_dont)
1058 bfd_signed_vma signed_check;
1060 bfd_signed_vma signed_add;
1062 if (howto->rightshift == 0)
1065 signed_check = (bfd_signed_vma) relocation;
1069 /* Drop unwanted bits from the value we are relocating to. */
1070 check = relocation >> howto->rightshift;
1072 /* If this is a signed value, the rightshift just dropped
1073 leading 1 bits (assuming twos complement). */
1074 if ((bfd_signed_vma) relocation >= 0)
1075 signed_check = check;
1077 signed_check = (check
1079 & ~((bfd_vma) - 1 >> howto->rightshift)));
1082 /* Get the value from the object file. */
1083 add = x & howto->src_mask;
1085 /* Get the value from the object file with an appropriate sign.
1086 The expression involving howto->src_mask isolates the upper
1087 bit of src_mask. If that bit is set in the value we are
1088 adding, it is negative, and we subtract out that number times
1089 two. If src_mask includes the highest possible bit, then we
1090 can not get the upper bit, but that does not matter since
1091 signed_add needs no adjustment to become negative in that
1094 if ((add & (((~howto->src_mask) >> 1) & howto->src_mask)) != 0)
1095 signed_add -= (((~howto->src_mask) >> 1) & howto->src_mask) << 1;
1097 /* Add the value from the object file, shifted so that it is a
1099 if (howto->bitpos == 0)
1102 signed_check += signed_add;
1106 check += add >> howto->bitpos;
1108 /* For the signed case we use ADD, rather than SIGNED_ADD,
1109 to avoid warnings from SVR4 cc. This is OK since we
1110 explictly handle the sign bits. */
1111 if (signed_add >= 0)
1112 signed_check += add >> howto->bitpos;
1114 signed_check += ((add >> howto->bitpos)
1116 & ~((bfd_vma) - 1 >> howto->bitpos)));
1119 switch (howto->complain_on_overflow)
1121 case complain_overflow_signed:
1123 /* Assumes two's complement. */
1124 bfd_signed_vma reloc_signed_max = (1 << (howto->bitsize - 1)) - 1;
1125 bfd_signed_vma reloc_signed_min = ~reloc_signed_max;
1127 if (signed_check > reloc_signed_max
1128 || signed_check < reloc_signed_min)
1132 case complain_overflow_unsigned:
1134 /* Assumes two's complement. This expression avoids
1135 overflow if howto->bitsize is the number of bits in
1137 bfd_vma reloc_unsigned_max =
1138 (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
1140 if (check > reloc_unsigned_max)
1144 case complain_overflow_bitfield:
1146 /* Assumes two's complement. This expression avoids
1147 overflow if howto->bitsize is the number of bits in
1149 bfd_vma reloc_bits = (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
1151 if ((check & ~reloc_bits) != 0
1152 && (((bfd_vma) signed_check & ~reloc_bits)
1153 != (-1 & ~reloc_bits)))
1162 /* Put RELOCATION in the right bits. */
1163 relocation >>= (bfd_vma) howto->rightshift;
1164 relocation <<= (bfd_vma) howto->bitpos;
1166 /* Add RELOCATION to the right bits of X. */
1167 x = ((x & ~howto->dst_mask)
1168 | (((x & howto->src_mask) + relocation) & howto->dst_mask));
1170 /* Put the relocated value back in the object file. */
1177 bfd_put_8 (input_bfd, x, location);
1180 bfd_put_16 (input_bfd, x, location);
1183 bfd_put_32 (input_bfd, x, location);
1187 bfd_put_64 (input_bfd, x, location);
1194 return overflow ? bfd_reloc_overflow : bfd_reloc_ok;
1200 howto manager, , typedef arelent, Relocations
1205 When an application wants to create a relocation, but doesn't
1206 know what the target machine might call it, it can find out by
1207 using this bit of code.
1216 The insides of a reloc code. The idea is that, eventually, there
1217 will be one enumerator for every type of relocation we ever do.
1218 Pass one of these values to <<bfd_reloc_type_lookup>>, and it'll
1219 return a howto pointer.
1221 This does mean that the application must determine the correct
1222 enumerator value; you can't get a howto pointer from a random set
1227 .typedef enum bfd_reloc_code_real
1229 . {* Basic absolute relocations *}
1237 . {* PC-relative relocations *}
1238 . BFD_RELOC_64_PCREL,
1239 . BFD_RELOC_32_PCREL,
1240 . BFD_RELOC_24_PCREL, {* used by i960 *}
1241 . BFD_RELOC_16_PCREL,
1242 . BFD_RELOC_8_PCREL,
1244 . {* Linkage-table relative *}
1245 . BFD_RELOC_32_BASEREL,
1246 . BFD_RELOC_16_BASEREL,
1247 . BFD_RELOC_8_BASEREL,
1249 . {* The type of reloc used to build a contructor table - at the moment
1250 . probably a 32 bit wide abs address, but the cpu can choose. *}
1253 . {* 8 bits wide, but used to form an address like 0xffnn *}
1256 . {* 32-bit pc-relative, shifted right 2 bits (i.e., 30-bit
1257 . word displacement, e.g. for SPARC) *}
1258 . BFD_RELOC_32_PCREL_S2,
1259 . {* signed 16-bit pc-relative, shifted right 2 bits (e.g. for MIPS) *}
1260 . BFD_RELOC_16_PCREL_S2,
1261 . {* this is used on the Alpha *}
1262 . BFD_RELOC_23_PCREL_S2,
1264 . {* High 22 bits of 32-bit value, placed into lower 22 bits of
1265 . target word; simple reloc. *}
1267 . {* Low 10 bits. *}
1270 . {* For systems that allocate a Global Pointer register, these are
1271 . displacements off that register. These relocation types are
1272 . handled specially, because the value the register will have is
1273 . decided relatively late. *}
1274 . BFD_RELOC_GPREL16,
1275 . BFD_RELOC_GPREL32,
1277 . {* Reloc types used for i960/b.out. *}
1278 . BFD_RELOC_I960_CALLJ,
1280 . {* now for the sparc/elf codes *}
1281 . BFD_RELOC_NONE, {* actually used *}
1282 . BFD_RELOC_SPARC_WDISP22,
1283 . BFD_RELOC_SPARC22,
1284 . BFD_RELOC_SPARC13,
1285 . BFD_RELOC_SPARC_GOT10,
1286 . BFD_RELOC_SPARC_GOT13,
1287 . BFD_RELOC_SPARC_GOT22,
1288 . BFD_RELOC_SPARC_PC10,
1289 . BFD_RELOC_SPARC_PC22,
1290 . BFD_RELOC_SPARC_WPLT30,
1291 . BFD_RELOC_SPARC_COPY,
1292 . BFD_RELOC_SPARC_GLOB_DAT,
1293 . BFD_RELOC_SPARC_JMP_SLOT,
1294 . BFD_RELOC_SPARC_RELATIVE,
1295 . BFD_RELOC_SPARC_UA32,
1297 . {* these are a.out specific? *}
1298 . BFD_RELOC_SPARC_BASE13,
1299 . BFD_RELOC_SPARC_BASE22,
1301 . {* some relocations we're using for sparc v9
1302 . -- subject to change *}
1303 . BFD_RELOC_SPARC_10,
1304 . BFD_RELOC_SPARC_11,
1305 .#define BFD_RELOC_SPARC_64 BFD_RELOC_64
1306 . BFD_RELOC_SPARC_OLO10,
1307 . BFD_RELOC_SPARC_HH22,
1308 . BFD_RELOC_SPARC_HM10,
1309 . BFD_RELOC_SPARC_LM22,
1310 . BFD_RELOC_SPARC_PC_HH22,
1311 . BFD_RELOC_SPARC_PC_HM10,
1312 . BFD_RELOC_SPARC_PC_LM22,
1313 . BFD_RELOC_SPARC_WDISP16,
1314 . BFD_RELOC_SPARC_WDISP19,
1315 . BFD_RELOC_SPARC_GLOB_JMP,
1316 . BFD_RELOC_SPARC_LO7,
1318 . {* Alpha ECOFF relocations. Some of these treat the symbol or "addend"
1319 . in some special way. *}
1320 . {* For GPDISP_HI16 ("gpdisp") relocations, the symbol is ignored when
1321 . writing; when reading, it will be the absolute section symbol. The
1322 . addend is the displacement in bytes of the "lda" instruction from
1323 . the "ldah" instruction (which is at the address of this reloc). *}
1324 . BFD_RELOC_ALPHA_GPDISP_HI16,
1325 . {* For GPDISP_LO16 ("ignore") relocations, the symbol is handled as
1326 . with GPDISP_HI16 relocs. The addend is ignored when writing the
1327 . relocations out, and is filled in with the file's GP value on
1328 . reading, for convenience. *}
1329 . BFD_RELOC_ALPHA_GPDISP_LO16,
1331 . {* The Alpha LITERAL/LITUSE relocs are produced by a symbol reference;
1332 . the assembler turns it into a LDQ instruction to load the address of
1333 . the symbol, and then fills in a register in the real instruction.
1335 . The LITERAL reloc, at the LDQ instruction, refers to the .lita
1336 . section symbol. The addend is ignored when writing, but is filled
1337 . in with the file's GP value on reading, for convenience, as with the
1338 . GPDISP_LO16 reloc.
1340 . The LITUSE reloc, on the instruction using the loaded address, gives
1341 . information to the linker that it might be able to use to optimize
1342 . away some literal section references. The symbol is ignored (read
1343 . as the absolute section symbol), and the "addend" indicates the type
1344 . of instruction using the register:
1345 . 1 - "memory" fmt insn
1346 . 2 - byte-manipulation (byte offset reg)
1347 . 3 - jsr (target of branch)
1349 . The GNU linker currently doesn't do any of this optimizing. *}
1350 . BFD_RELOC_ALPHA_LITERAL,
1351 . BFD_RELOC_ALPHA_LITUSE,
1353 . {* The HINT relocation indicates a value that should be filled into the
1354 . "hint" field of a jmp/jsr/ret instruction, for possible branch-
1355 . prediction logic which may be provided on some processors. *}
1356 . BFD_RELOC_ALPHA_HINT,
1358 . {* Bits 27..2 of the relocation address shifted right 2 bits;
1359 . simple reloc otherwise. *}
1360 . BFD_RELOC_MIPS_JMP,
1362 . {* High 16 bits of 32-bit value; simple reloc. *}
1364 . {* High 16 bits of 32-bit value but the low 16 bits will be sign
1365 . extended and added to form the final result. If the low 16
1366 . bits form a negative number, we need to add one to the high value
1367 . to compensate for the borrow when the low bits are added. *}
1369 . {* Low 16 bits. *}
1371 . {* Like BFD_RELOC_HI16_S, but PC relative. *}
1372 . BFD_RELOC_PCREL_HI16_S,
1373 . {* Like BFD_RELOC_LO16, but PC relative. *}
1374 . BFD_RELOC_PCREL_LO16,
1376 . {* relocation relative to the global pointer. *}
1377 .#define BFD_RELOC_MIPS_GPREL BFD_RELOC_GPREL16
1379 . {* Relocation against a MIPS literal section. *}
1380 . BFD_RELOC_MIPS_LITERAL,
1382 . {* MIPS ELF relocations. *}
1383 . BFD_RELOC_MIPS_GOT16,
1384 . BFD_RELOC_MIPS_CALL16,
1385 .#define BFD_RELOC_MIPS_GPREL32 BFD_RELOC_GPREL32
1387 . {* i386/elf relocations *}
1388 . BFD_RELOC_386_GOT32,
1389 . BFD_RELOC_386_PLT32,
1390 . BFD_RELOC_386_COPY,
1391 . BFD_RELOC_386_GLOB_DAT,
1392 . BFD_RELOC_386_JUMP_SLOT,
1393 . BFD_RELOC_386_RELATIVE,
1394 . BFD_RELOC_386_GOTOFF,
1395 . BFD_RELOC_386_GOTPC,
1397 . {* ns32k relocations *}
1398 . BFD_RELOC_NS32K_IMM_8,
1399 . BFD_RELOC_NS32K_IMM_16,
1400 . BFD_RELOC_NS32K_IMM_32,
1401 . BFD_RELOC_NS32K_IMM_8_PCREL,
1402 . BFD_RELOC_NS32K_IMM_16_PCREL,
1403 . BFD_RELOC_NS32K_IMM_32_PCREL,
1404 . BFD_RELOC_NS32K_DISP_8,
1405 . BFD_RELOC_NS32K_DISP_16,
1406 . BFD_RELOC_NS32K_DISP_32,
1407 . BFD_RELOC_NS32K_DISP_8_PCREL,
1408 . BFD_RELOC_NS32K_DISP_16_PCREL,
1409 . BFD_RELOC_NS32K_DISP_32_PCREL,
1411 . {* PowerPC/POWER (RS/6000) relocs. *}
1412 . {* 26 bit relative branch. Low two bits must be zero. High 24
1413 . bits installed in bits 6 through 29 of instruction. *}
1414 . BFD_RELOC_PPC_B26,
1415 . {* 26 bit absolute branch, like BFD_RELOC_PPC_B26 but absolute. *}
1416 . BFD_RELOC_PPC_BA26,
1417 . {* 16 bit TOC relative reference. *}
1418 . BFD_RELOC_PPC_TOC16,
1420 . {* this must be the highest numeric value *}
1422 . } bfd_reloc_code_real_type;
1428 bfd_reloc_type_lookup
1431 const struct reloc_howto_struct *
1432 bfd_reloc_type_lookup (bfd *abfd, bfd_reloc_code_real_type code);
1435 Return a pointer to a howto structure which, when
1436 invoked, will perform the relocation @var{code} on data from the
1442 const struct reloc_howto_struct *
1443 bfd_reloc_type_lookup (abfd, code)
1445 bfd_reloc_code_real_type code;
1447 return BFD_SEND (abfd, reloc_type_lookup, (abfd, code));
1450 static reloc_howto_type bfd_howto_32 =
1451 HOWTO (0, 00, 2, 32, false, 0, complain_overflow_bitfield, 0, "VRT32", false, 0xffffffff, 0xffffffff, true);
1456 bfd_default_reloc_type_lookup
1459 const struct reloc_howto_struct *bfd_default_reloc_type_lookup
1460 (bfd *abfd, bfd_reloc_code_real_type code);
1463 Provides a default relocation lookup routine for any architecture.
1468 const struct reloc_howto_struct *
1469 bfd_default_reloc_type_lookup (abfd, code)
1471 bfd_reloc_code_real_type code;
1475 case BFD_RELOC_CTOR:
1476 /* The type of reloc used in a ctor, which will be as wide as the
1477 address - so either a 64, 32, or 16 bitter. */
1478 switch (bfd_get_arch_info (abfd)->bits_per_address)
1483 return &bfd_howto_32;
1492 return (const struct reloc_howto_struct *) NULL;
1498 bfd_generic_relax_section
1501 boolean bfd_generic_relax_section
1504 struct bfd_link_info *,
1508 Provides default handling for relaxing for back ends which
1509 don't do relaxing -- i.e., does nothing.
1514 bfd_generic_relax_section (abfd, section, link_info, again)
1517 struct bfd_link_info *link_info;
1526 bfd_generic_get_relocated_section_contents
1530 bfd_generic_get_relocated_section_contents (bfd *abfd,
1531 struct bfd_link_info *link_info,
1532 struct bfd_link_order *link_order,
1534 boolean relocateable,
1538 Provides default handling of relocation effort for back ends
1539 which can't be bothered to do it efficiently.
1544 bfd_generic_get_relocated_section_contents (abfd, link_info, link_order, data,
1545 relocateable, symbols)
1547 struct bfd_link_info *link_info;
1548 struct bfd_link_order *link_order;
1550 boolean relocateable;
1553 /* Get enough memory to hold the stuff */
1554 bfd *input_bfd = link_order->u.indirect.section->owner;
1555 asection *input_section = link_order->u.indirect.section;
1557 long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
1558 arelent **reloc_vector = NULL;
1564 reloc_vector = (arelent **) malloc (reloc_size);
1565 if (reloc_vector == NULL && reloc_size != 0)
1567 bfd_set_error (bfd_error_no_memory);
1571 /* read in the section */
1572 if (!bfd_get_section_contents (input_bfd,
1576 input_section->_raw_size))
1579 /* We're not relaxing the section, so just copy the size info */
1580 input_section->_cooked_size = input_section->_raw_size;
1581 input_section->reloc_done = true;
1583 reloc_count = bfd_canonicalize_reloc (input_bfd,
1587 if (reloc_count < 0)
1590 if (reloc_count > 0)
1593 for (parent = reloc_vector; *parent != (arelent *) NULL;
1596 char *error_message = (char *) NULL;
1597 bfd_reloc_status_type r =
1598 bfd_perform_relocation (input_bfd,
1602 relocateable ? abfd : (bfd *) NULL,
1607 asection *os = input_section->output_section;
1609 /* A partial link, so keep the relocs */
1610 os->orelocation[os->reloc_count] = *parent;
1614 if (r != bfd_reloc_ok)
1618 case bfd_reloc_undefined:
1619 if (!((*link_info->callbacks->undefined_symbol)
1620 (link_info, bfd_asymbol_name (*(*parent)->sym_ptr_ptr),
1621 input_bfd, input_section, (*parent)->address)))
1624 case bfd_reloc_dangerous:
1625 BFD_ASSERT (error_message != (char *) NULL);
1626 if (!((*link_info->callbacks->reloc_dangerous)
1627 (link_info, error_message, input_bfd, input_section,
1628 (*parent)->address)))
1631 case bfd_reloc_overflow:
1632 if (!((*link_info->callbacks->reloc_overflow)
1633 (link_info, bfd_asymbol_name (*(*parent)->sym_ptr_ptr),
1634 (*parent)->howto->name, (*parent)->addend,
1635 input_bfd, input_section, (*parent)->address)))
1638 case bfd_reloc_outofrange:
1647 if (reloc_vector != NULL)
1648 free (reloc_vector);
1652 if (reloc_vector != NULL)
1653 free (reloc_vector);