1 /* `a.out' object-file definitions, including extensions to 64-bit fields
3 Copyright (C) 1999-2019 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
18 MA 02110-1301, USA. */
20 #ifndef __A_OUT_64_H__
21 #define __A_OUT_64_H__
24 #define BYTES_IN_WORD 4
27 /* This is the layout on disk of the 32-bit or 64-bit exec header. */
32 bfd_byte e_info
[4]; /* Magic number and stuff. */
33 bfd_byte e_text
[BYTES_IN_WORD
]; /* Length of text section in bytes. */
34 bfd_byte e_data
[BYTES_IN_WORD
]; /* Length of data section in bytes. */
35 bfd_byte e_bss
[BYTES_IN_WORD
]; /* Length of bss area in bytes. */
36 bfd_byte e_syms
[BYTES_IN_WORD
]; /* Length of symbol table in bytes. */
37 bfd_byte e_entry
[BYTES_IN_WORD
]; /* Start address. */
38 bfd_byte e_trsize
[BYTES_IN_WORD
]; /* Length of text relocation info. */
39 bfd_byte e_drsize
[BYTES_IN_WORD
]; /* Length of data relocation info. */
42 #define EXEC_BYTES_SIZE (4 + BYTES_IN_WORD * 7)
44 /* Magic numbers for a.out files. */
47 #define OMAGIC 0x1001 /* Code indicating object file. */
48 #define ZMAGIC 0x1002 /* Code indicating demand-paged executable. */
49 #define NMAGIC 0x1003 /* Code indicating pure executable. */
51 /* There is no 64-bit QMAGIC as far as I know. */
53 #define N_BADMAG(x) (N_MAGIC(x) != OMAGIC \
54 && N_MAGIC(x) != NMAGIC \
55 && N_MAGIC(x) != ZMAGIC)
57 #define OMAGIC 0407 /* Object file or impure executable. */
58 #define NMAGIC 0410 /* Code indicating pure executable. */
59 #define ZMAGIC 0413 /* Code indicating demand-paged executable. */
60 #define BMAGIC 0415 /* Used by a b.out object. */
62 /* This indicates a demand-paged executable with the header in the text.
63 It is used by 386BSD (and variants) and Linux, at least. */
68 # define N_BADMAG(x) (N_MAGIC(x) != OMAGIC \
69 && N_MAGIC(x) != NMAGIC \
70 && N_MAGIC(x) != ZMAGIC \
71 && N_MAGIC(x) != QMAGIC)
72 # endif /* N_BADMAG */
78 #define N_IS_QMAGIC(x) (N_MAGIC (x) == QMAGIC)
80 #define N_IS_QMAGIC(x) (0)
83 /* The difference between TARGET_PAGE_SIZE and N_SEGSIZE is that TARGET_PAGE_SIZE is
84 the finest granularity at which you can page something, thus it
85 controls the padding (if any) before the text segment of a ZMAGIC
86 file. N_SEGSIZE is the resolution at which things can be marked as
87 read-only versus read/write, so it controls the padding between the
88 text segment and the data segment (in memory; on disk the padding
89 between them is TARGET_PAGE_SIZE). TARGET_PAGE_SIZE and N_SEGSIZE are the same
90 for most machines, but different for sun3. */
92 /* By default, segment size is constant. But some machines override this
93 to be a function of the a.out header (e.g. machine type). */
96 #define N_SEGSIZE(x) SEGMENT_SIZE
99 /* Virtual memory address of the text section.
100 This is getting very complicated. A good reason to discard a.out format
101 for something that specifies these fields explicitly. But til then...
103 * OMAGIC and NMAGIC files:
104 (object files: text for "relocatable addr 0" right after the header)
105 start at 0, offset is EXEC_BYTES_SIZE, size as stated.
106 * The text address, offset, and size of ZMAGIC files depend
107 on the entry point of the file:
108 * entry point below TEXT_START_ADDR:
109 (hack for SunOS shared libraries)
110 start at 0, offset is 0, size as stated.
111 * If N_HEADER_IN_TEXT(x) is true (which defaults to being the
112 case when the entry point is EXEC_BYTES_SIZE or further into a page):
113 no padding is needed; text can start after exec header. Sun
114 considers the text segment of such files to include the exec header;
115 for BFD's purposes, we don't, which makes more work for us.
116 start at TEXT_START_ADDR + EXEC_BYTES_SIZE, offset is EXEC_BYTES_SIZE,
117 size as stated minus EXEC_BYTES_SIZE.
118 * If N_HEADER_IN_TEXT(x) is false (which defaults to being the case when
119 the entry point is less than EXEC_BYTES_SIZE into a page (e.g. page
120 aligned)): (padding is needed so that text can start at a page boundary)
121 start at TEXT_START_ADDR, offset TARGET_PAGE_SIZE, size as stated.
123 Specific configurations may want to hardwire N_HEADER_IN_TEXT,
124 for efficiency or to allow people to play games with the entry point.
125 In that case, you would #define N_HEADER_IN_TEXT(x) as 1 for sunos,
126 and as 0 for most other hosts (Sony News, Vax Ultrix, etc).
127 (Do this in the appropriate bfd target file.)
128 (The default is a heuristic that will break if people try changing
129 the entry point, perhaps with the ld -e flag.)
131 * QMAGIC is always like a ZMAGIC for which N_HEADER_IN_TEXT is true,
132 and for which the starting address is TARGET_PAGE_SIZE (or should this be
133 SEGMENT_SIZE?) (TEXT_START_ADDR only applies to ZMAGIC, not to QMAGIC). */
135 /* This macro is only relevant for ZMAGIC files; QMAGIC always has the header
137 #ifndef N_HEADER_IN_TEXT
138 #define N_HEADER_IN_TEXT(x) \
139 (((x)->a_entry & (TARGET_PAGE_SIZE-1)) >= EXEC_BYTES_SIZE)
142 /* Sun shared libraries, not linux. This macro is only relevant for ZMAGIC
145 #define N_SHARED_LIB(x) (0)
148 /* Returning 0 not TEXT_START_ADDR for OMAGIC and NMAGIC is based on
149 the assumption that we are dealing with a .o file, not an
150 executable. This is necessary for OMAGIC (but means we don't work
151 right on the output from ld -N); more questionable for NMAGIC. */
154 #define N_TXTADDR(x) \
155 (/* The address of a QMAGIC file is always one page in, \
156 with the header in the text. */ \
158 ? (bfd_vma) TARGET_PAGE_SIZE + EXEC_BYTES_SIZE \
159 : (N_MAGIC (x) != ZMAGIC \
160 ? (bfd_vma) 0 /* Object file or NMAGIC. */ \
161 : (N_SHARED_LIB (x) \
163 : (N_HEADER_IN_TEXT (x) \
164 ? (bfd_vma) TEXT_START_ADDR + EXEC_BYTES_SIZE \
165 : (bfd_vma) TEXT_START_ADDR))))
168 /* If N_HEADER_IN_TEXT is not true for ZMAGIC, there is some padding
169 to make the text segment start at a certain boundary. For most
170 systems, this boundary is TARGET_PAGE_SIZE. But for Linux, in the
171 time-honored tradition of crazy ZMAGIC hacks, it is 1024 which is
172 not what TARGET_PAGE_SIZE needs to be for QMAGIC. */
174 #ifndef ZMAGIC_DISK_BLOCK_SIZE
175 #define ZMAGIC_DISK_BLOCK_SIZE TARGET_PAGE_SIZE
178 #define N_DISK_BLOCK_SIZE(x) \
179 (N_MAGIC(x) == ZMAGIC ? ZMAGIC_DISK_BLOCK_SIZE : TARGET_PAGE_SIZE)
181 /* Offset in an a.out of the start of the text section. */
183 #define N_TXTOFF(x) \
184 (/* For {O,N,Q}MAGIC, no padding. */ \
185 N_MAGIC (x) != ZMAGIC \
187 : (N_SHARED_LIB (x) \
189 : (N_HEADER_IN_TEXT (x) \
190 ? EXEC_BYTES_SIZE /* No padding. */ \
191 : ZMAGIC_DISK_BLOCK_SIZE /* A page of padding. */)))
193 /* Size of the text section. It's always as stated, except that we
194 offset it to `undo' the adjustment to N_TXTADDR and N_TXTOFF
195 for ZMAGIC files that nominally include the exec header
196 as part of the first page of text. (BFD doesn't consider the
197 exec header to be part of the text segment.) */
199 #define N_TXTSIZE(x) \
200 (/* For QMAGIC, we don't consider the header part of the text section. */\
202 ? (x)->a_text - EXEC_BYTES_SIZE \
203 : ((N_MAGIC (x) != ZMAGIC || N_SHARED_LIB (x)) \
205 : (N_HEADER_IN_TEXT (x) \
206 ? (x)->a_text - EXEC_BYTES_SIZE /* No padding. */ \
207 : (x)->a_text /* A page of padding. */ )))
209 /* The address of the data segment in virtual memory.
210 It is the text segment address, plus text segment size, rounded
211 up to a N_SEGSIZE boundary for pure or pageable files. */
213 #define N_DATADDR(x) \
214 (N_MAGIC (x) == OMAGIC \
215 ? (N_TXTADDR (x) + N_TXTSIZE (x)) \
216 : (N_SEGSIZE (x) + ((N_TXTADDR (x) + N_TXTSIZE (x) - 1) \
217 & ~ (bfd_vma) (N_SEGSIZE (x) - 1))))
219 /* The address of the BSS segment -- immediately after the data segment. */
221 #define N_BSSADDR(x) (N_DATADDR (x) + (x)->a_data)
223 /* Offsets of the various portions of the file after the text segment. */
225 /* For {Q,Z}MAGIC, there is padding to make the data segment start on
226 a page boundary. Most of the time the a_text field (and thus
227 N_TXTSIZE) already contains this padding. It is possible that for
228 BSDI and/or 386BSD it sometimes doesn't contain the padding, and
229 perhaps we should be adding it here. But this seems kind of
230 questionable and probably should be BSDI/386BSD-specific if we do
233 For NMAGIC (at least for hp300 BSD, probably others), there is
234 padding in memory only, not on disk, so we must *not* ever pad here
238 #define N_DATOFF(x) (N_TXTOFF (x) + N_TXTSIZE (x))
241 #define N_TRELOFF(x) (N_DATOFF (x) + (x)->a_data)
244 #define N_DRELOFF(x) (N_TRELOFF (x) + (x)->a_trsize)
247 #define N_SYMOFF(x) (N_DRELOFF (x) + (x)->a_drsize)
250 #define N_STROFF(x) (N_SYMOFF (x) + (x)->a_syms)
254 #ifndef external_nlist
255 struct external_nlist
257 bfd_byte e_strx
[BYTES_IN_WORD
]; /* Index into string table of name. */
258 bfd_byte e_type
[1]; /* Type of symbol. */
259 bfd_byte e_other
[1]; /* Misc info (usually empty). */
260 bfd_byte e_desc
[2]; /* Description field. */
261 bfd_byte e_value
[BYTES_IN_WORD
]; /* Value of symbol. */
263 #define EXTERNAL_NLIST_SIZE (BYTES_IN_WORD+4+BYTES_IN_WORD)
266 struct internal_nlist
268 unsigned long n_strx
; /* Index into string table of name. */
269 unsigned char n_type
; /* Type of symbol. */
270 unsigned char n_other
; /* Misc info (usually empty). */
271 unsigned short n_desc
; /* Description field. */
272 bfd_vma n_value
; /* Value of symbol. */
275 /* The n_type field is the symbol type, containing: */
277 #define N_UNDF 0 /* Undefined symbol. */
278 #define N_ABS 2 /* Absolute symbol -- defined at particular addr. */
279 #define N_TEXT 4 /* Text sym -- defined at offset in text seg. */
280 #define N_DATA 6 /* Data sym -- defined at offset in data seg. */
281 #define N_BSS 8 /* BSS sym -- defined at offset in zero'd seg. */
282 #define N_COMM 0x12 /* Common symbol (visible after shared lib dynlink). */
283 #define N_FN 0x1f /* File name of .o file. */
284 #define N_FN_SEQ 0x0C /* N_FN from Sequent compilers (sigh). */
285 /* Note: N_EXT can only be usefully OR-ed with N_UNDF, N_ABS, N_TEXT,
286 N_DATA, or N_BSS. When the low-order bit of other types is set,
287 (e.g. N_WARNING versus N_FN), they are two different types. */
288 #define N_EXT 1 /* External symbol (as opposed to local-to-this-file). */
290 #define N_STAB 0xe0 /* If any of these bits are on, it's a debug symbol. */
294 /* The following symbols refer to set elements.
295 All the N_SET[ATDB] symbols with the same name form one set.
296 Space is allocated for the set in the text section, and each set
297 elements value is stored into one word of the space.
298 The first word of the space is the length of the set (number of elements).
300 The address of the set is made into an N_SETV symbol
301 whose name is the same as the name of the set.
302 This symbol acts like a N_DATA global symbol
303 in that it can satisfy undefined external references. */
305 /* These appear as input to LD, in a .o file. */
306 #define N_SETA 0x14 /* Absolute set element symbol. */
307 #define N_SETT 0x16 /* Text set element symbol. */
308 #define N_SETD 0x18 /* Data set element symbol. */
309 #define N_SETB 0x1A /* Bss set element symbol. */
311 /* This is output from LD. */
312 #define N_SETV 0x1C /* Pointer to set vector in data area. */
314 /* Warning symbol. The text gives a warning message, the next symbol
315 in the table will be undefined. When the symbol is referenced, the
316 message is printed. */
318 #define N_WARNING 0x1e
320 /* Weak symbols. These are a GNU extension to the a.out format. The
321 semantics are those of ELF weak symbols. Weak symbols are always
322 externally visible. The N_WEAK? values are squeezed into the
323 available slots. The value of a N_WEAKU symbol is 0. The values
324 of the other types are the definitions. */
325 #define N_WEAKU 0x0d /* Weak undefined symbol. */
326 #define N_WEAKA 0x0e /* Weak absolute symbol. */
327 #define N_WEAKT 0x0f /* Weak text symbol. */
328 #define N_WEAKD 0x10 /* Weak data symbol. */
329 #define N_WEAKB 0x11 /* Weak bss symbol. */
333 There are two types of relocation flavours for a.out systems,
334 standard and extended. The standard form is used on systems where the
335 instruction has room for all the bits of an offset to the operand, whilst
336 the extended form is used when an address operand has to be split over n
337 instructions. Eg, on the 68k, each move instruction can reference
338 the target with a displacement of 16 or 32 bits. On the sparc, move
339 instructions use an offset of 14 bits, so the offset is stored in
340 the reloc field, and the data in the section is ignored. */
342 /* This structure describes a single relocation to be performed.
343 The text-relocation section of the file is a vector of these structures,
344 all of which apply to the text section.
345 Likewise, the data-relocation section applies to the data section. */
347 struct reloc_std_external
349 bfd_byte r_address
[BYTES_IN_WORD
]; /* Offset of data to relocate. */
350 bfd_byte r_index
[3]; /* Symbol table index of symbol. */
351 bfd_byte r_type
[1]; /* Relocation type. */
354 #define RELOC_STD_BITS_PCREL_BIG ((unsigned int) 0x80)
355 #define RELOC_STD_BITS_PCREL_LITTLE ((unsigned int) 0x01)
357 #define RELOC_STD_BITS_LENGTH_BIG ((unsigned int) 0x60)
358 #define RELOC_STD_BITS_LENGTH_SH_BIG 5
359 #define RELOC_STD_BITS_LENGTH_LITTLE ((unsigned int) 0x06)
360 #define RELOC_STD_BITS_LENGTH_SH_LITTLE 1
362 #define RELOC_STD_BITS_EXTERN_BIG ((unsigned int) 0x10)
363 #define RELOC_STD_BITS_EXTERN_LITTLE ((unsigned int) 0x08)
365 #define RELOC_STD_BITS_BASEREL_BIG ((unsigned int) 0x08)
366 #define RELOC_STD_BITS_BASEREL_LITTLE ((unsigned int) 0x10)
368 #define RELOC_STD_BITS_JMPTABLE_BIG ((unsigned int) 0x04)
369 #define RELOC_STD_BITS_JMPTABLE_LITTLE ((unsigned int) 0x20)
371 #define RELOC_STD_BITS_RELATIVE_BIG ((unsigned int) 0x02)
372 #define RELOC_STD_BITS_RELATIVE_LITTLE ((unsigned int) 0x40)
374 #define RELOC_STD_SIZE (BYTES_IN_WORD + 3 + 1) /* Bytes per relocation entry. */
376 struct reloc_std_internal
378 bfd_vma r_address
; /* Address (within segment) to be relocated. */
379 /* The meaning of r_symbolnum depends on r_extern. */
380 unsigned int r_symbolnum
:24;
381 /* Nonzero means value is a pc-relative offset
382 and it should be relocated for changes in its own address
383 as well as for changes in the symbol or section specified. */
384 unsigned int r_pcrel
:1;
385 /* Length (as exponent of 2) of the field to be relocated.
386 Thus, a value of 2 indicates 1<<2 bytes. */
387 unsigned int r_length
:2;
388 /* 1 => relocate with value of symbol.
389 r_symbolnum is the index of the symbol
390 in files the symbol table.
391 0 => relocate with the address of a segment.
392 r_symbolnum is N_TEXT, N_DATA, N_BSS or N_ABS
393 (the N_EXT bit may be set also, but signifies nothing). */
394 unsigned int r_extern
:1;
395 /* The next three bits are for SunOS shared libraries, and seem to
397 unsigned int r_baserel
:1; /* Linkage table relative. */
398 unsigned int r_jmptable
:1; /* pc-relative to jump table. */
399 unsigned int r_relative
:1; /* "relative relocation". */
401 unsigned int r_pad
:1; /* Padding -- set to zero. */
405 /* EXTENDED RELOCS. */
407 struct reloc_ext_external
409 bfd_byte r_address
[BYTES_IN_WORD
]; /* Offset of data to relocate. */
410 bfd_byte r_index
[3]; /* Symbol table index of symbol. */
411 bfd_byte r_type
[1]; /* Relocation type. */
412 bfd_byte r_addend
[BYTES_IN_WORD
]; /* Datum addend. */
415 #ifndef RELOC_EXT_BITS_EXTERN_BIG
416 #define RELOC_EXT_BITS_EXTERN_BIG ((unsigned int) 0x80)
419 #ifndef RELOC_EXT_BITS_EXTERN_LITTLE
420 #define RELOC_EXT_BITS_EXTERN_LITTLE ((unsigned int) 0x01)
423 #ifndef RELOC_EXT_BITS_TYPE_BIG
424 #define RELOC_EXT_BITS_TYPE_BIG ((unsigned int) 0x1F)
427 #ifndef RELOC_EXT_BITS_TYPE_SH_BIG
428 #define RELOC_EXT_BITS_TYPE_SH_BIG 0
431 #ifndef RELOC_EXT_BITS_TYPE_LITTLE
432 #define RELOC_EXT_BITS_TYPE_LITTLE ((unsigned int) 0xF8)
435 #ifndef RELOC_EXT_BITS_TYPE_SH_LITTLE
436 #define RELOC_EXT_BITS_TYPE_SH_LITTLE 3
439 /* Bytes per relocation entry. */
440 #define RELOC_EXT_SIZE (BYTES_IN_WORD + 3 + 1 + BYTES_IN_WORD)
444 /* Simple relocations. */
445 RELOC_8
, /* data[0:7] = addend + sv */
446 RELOC_16
, /* data[0:15] = addend + sv */
447 RELOC_32
, /* data[0:31] = addend + sv */
448 /* PC-rel displacement. */
449 RELOC_DISP8
, /* data[0:7] = addend - pc + sv */
450 RELOC_DISP16
, /* data[0:15] = addend - pc + sv */
451 RELOC_DISP32
, /* data[0:31] = addend - pc + sv */
453 RELOC_WDISP30
, /* data[0:29] = (addend + sv - pc)>>2 */
454 RELOC_WDISP22
, /* data[0:21] = (addend + sv - pc)>>2 */
455 RELOC_HI22
, /* data[0:21] = (addend + sv)>>10 */
456 RELOC_22
, /* data[0:21] = (addend + sv) */
457 RELOC_13
, /* data[0:12] = (addend + sv) */
458 RELOC_LO10
, /* data[0:9] = (addend + sv) */
461 /* P.I.C. (base-relative). */
462 RELOC_BASE10
, /* Not sure - maybe we can do this the */
463 RELOC_BASE13
, /* right way now */
465 /* For some sort of pc-rel P.I.C. (?) */
468 /* P.I.C. jump table. */
470 /* Reputedly for shared libraries somehow. */
484 struct reloc_internal
486 bfd_vma r_address
; /* Offset of data to relocate. */
487 long r_index
; /* Symbol table index of symbol. */
488 enum reloc_type r_type
; /* Relocation type. */
489 bfd_vma r_addend
; /* Datum addend. */
493 Should the length of the string table be 4 bytes or 8 bytes ?
496 What about archive indexes ? */
498 #endif /* __A_OUT_64_H__ */
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