about summary refs log tree commit diff
path: root/sysdeps/arm/dl-machine.h
blob: 2d802b7e9b13b3fed74be0cba001773ce17d4c3c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
/* Machine-dependent ELF dynamic relocation inline functions.  ARM version.
   Copyright (C) 1995,96,97,98,99,2000,2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef dl_machine_h
#define dl_machine_h

#define ELF_MACHINE_NAME "ARM"

#include <sys/param.h>

#define VALID_ELF_ABIVERSION(ver)	(ver == 0)
#define VALID_ELF_OSABI(osabi) \
  (osabi == ELFOSABI_SYSV || osabi == ELFOSABI_ARM)
#define VALID_ELF_HEADER(hdr,exp,size) \
  memcmp (hdr,exp,size-2) == 0 \
  && VALID_ELF_OSABI (hdr[EI_OSABI]) \
  && VALID_ELF_ABIVERSION (hdr[EI_ABIVERSION])

#define CLEAR_CACHE(BEG,END)						\
{									\
  register unsigned long _beg __asm ("a1") = (unsigned long)(BEG);	\
  register unsigned long _end __asm ("a2") = (unsigned long)(END);	\
  register unsigned long _flg __asm ("a3") = 0;				\
  __asm __volatile ("swi 0x9f0002		@ sys_cacheflush"	\
		    : /* no outputs */					\
		    : /* no inputs */					\
		    : "a1");						\
}

/* Return nonzero iff ELF header is compatible with the running host.  */
static inline int __attribute__ ((unused))
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
  return ehdr->e_machine == EM_ARM;
}


/* Return the link-time address of _DYNAMIC.  Conveniently, this is the
   first element of the GOT.  This must be inlined in a function which
   uses global data.  */
static inline Elf32_Addr __attribute__ ((unused))
elf_machine_dynamic (void)
{
  register Elf32_Addr *got asm ("r10");
  return *got;
}


/* Return the run-time load address of the shared object.  */
static inline Elf32_Addr __attribute__ ((unused))
elf_machine_load_address (void)
{
  extern void __dl_start asm ("_dl_start");
  Elf32_Addr got_addr = (Elf32_Addr) &__dl_start;
  Elf32_Addr pcrel_addr;
  asm ("adr %0, _dl_start" : "=r" (pcrel_addr));
  return pcrel_addr - got_addr;
}


/* Set up the loaded object described by L so its unrelocated PLT
   entries will jump to the on-demand fixup code in dl-runtime.c.  */

static inline int __attribute__ ((unused))
elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
{
  Elf32_Addr *got;
  extern void _dl_runtime_resolve (Elf32_Word);
  extern void _dl_runtime_profile (Elf32_Word);

  if (l->l_info[DT_JMPREL] && lazy)
    {
      /* patb: this is different than i386 */
      /* The GOT entries for functions in the PLT have not yet been filled
	 in.  Their initial contents will arrange when called to push an
	 index into the .got section, load ip with &_GLOBAL_OFFSET_TABLE_[3],
	 and then jump to _GLOBAL_OFFSET_TABLE[2].  */
      got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
      got[1] = (Elf32_Addr) l;	/* Identify this shared object.  */

      /* The got[2] entry contains the address of a function which gets
	 called to get the address of a so far unresolved function and
	 jump to it.  The profiling extension of the dynamic linker allows
	 to intercept the calls to collect information.  In this case we
	 don't store the address in the GOT so that all future calls also
	 end in this function.  */
      if (profile)
	{
	  got[2] = (Elf32_Addr) &_dl_runtime_profile;

	  if (_dl_name_match_p (_dl_profile, l))
	    /* Say that we really want profiling and the timers are
	       started.  */
	    _dl_profile_map = l;
	}
      else
	/* This function will get called to fix up the GOT entry indicated by
	   the offset on the stack, and then jump to the resolved address.  */
	got[2] = (Elf32_Addr) &_dl_runtime_resolve;
    }
  return lazy;
}

/* This code is used in dl-runtime.c to call the `fixup' function
   and then redirect to the address it returns.  */
   // macro for handling PIC situation....
#ifdef PIC
#define CALL_ROUTINE(x) " ldr sl,0f
	add 	sl, pc, sl
1:	ldr	r2, 2f
	mov	lr, pc
	add	pc, sl, r2
	b	3f
0:	.word	_GLOBAL_OFFSET_TABLE_ - 1b - 4
2:	.word " #x "(GOTOFF)
3:	"
#else
#define CALL_ROUTINE(x) " bl " #x
#endif

#ifndef PROF
# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
	.text
	.globl _dl_runtime_resolve
	.type _dl_runtime_resolve, #function
	.align 2
_dl_runtime_resolve:
	@ we get called with
	@ 	stack[0] contains the return address from this call
	@	ip contains &GOT[n+3] (pointer to function)
	@	lr points to &GOT[2]

	@ save almost everything; lr is already on the stack
	stmdb	sp!,{r0-r3,sl,fp}

	@ prepare to call fixup()
	@ change &GOT[n+3] into 8*n        NOTE: reloc are 8 bytes each
	sub	r1, ip, lr
	sub	r1, r1, #4
	add	r1, r1, r1

	@ get pointer to linker struct
	ldr	r0, [lr, #-4]

	@ call fixup routine
	" CALL_ROUTINE(fixup) "

	@ save the return
	mov	ip, r0

	@ restore the stack
	ldmia	sp!,{r0-r3,sl,fp,lr}

	@ jump to the newly found address
	mov	pc, ip

	.size _dl_runtime_resolve, .-_dl_runtime_resolve

	.globl _dl_runtime_profile
	.type _dl_runtime_profile, #function
	.align 2
_dl_runtime_profile:
	@ save almost everything; lr is already on the stack
	stmdb	sp!,{r0-r3,sl,fp}

	@ prepare to call fixup()
	@ change &GOT[n+3] into 8*n        NOTE: reloc are 8 bytes each
	sub	r1, ip, lr
	sub	r1, r1, #4
	add	r1, r1, r1

	@ get pointer to linker struct
	ldr	r0, [lr, #-4]

	@ call profiling fixup routine
	" CALL_ROUTINE(profile_fixup) "

	@ save the return
	mov	ip, r0

	@ restore the stack
	ldmia	sp!,{r0-r3,sl,fp,lr}

	@ jump to the newly found address
	mov	pc, ip

	.size _dl_runtime_resolve, .-_dl_runtime_resolve
	.previous
");
#else // PROF
# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
	.text
	.globl _dl_runtime_resolve
	.globl _dl_runtime_profile
	.type _dl_runtime_resolve, #function
	.type _dl_runtime_profile, #function
	.align 2
_dl_runtime_resolve:
_dl_runtime_profile:
	@ we get called with
	@ 	stack[0] contains the return address from this call
	@	ip contains &GOT[n+3] (pointer to function)
	@	lr points to &GOT[2]

	@ save almost everything; return add is already on the stack
	stmdb	sp!,{r0-r3,sl,fp}

	@ prepare to call fixup()
	@ change &GOT[n+3] into 8*n        NOTE: reloc are 8 bytes each
	sub	r1, ip, lr
	sub	r1, r1, #4
	add	r1, r1, r1

	@ get pointer to linker struct
	ldr	r0, [lr, #-4]

	@ call profiling fixup routine
	" CALL_ROUTINE(fixup) "

	@ save the return
	mov	ip, r0

	@ restore the stack
	ldmia	sp!,{r0-r3,sl,fp,lr}

	@ jump to the newly found address
	mov	pc, ip

	.size _dl_runtime_profile, .-_dl_runtime_profile
	.previous
");
#endif //PROF

/* Mask identifying addresses reserved for the user program,
   where the dynamic linker should not map anything.  */
#define ELF_MACHINE_USER_ADDRESS_MASK	0xf8000000UL

/* Initial entry point code for the dynamic linker.
   The C function `_dl_start' is the real entry point;
   its return value is the user program's entry point.  */

#define RTLD_START asm ("\
.text
.globl _start
.globl _dl_start_user
_start:
	@ at start time, all the args are on the stack
	mov	r0, sp
	bl	_dl_start
	@ returns user entry point in r0
_dl_start_user:
	mov	r6, r0
	@ we are PIC code, so get global offset table
	ldr	sl, .L_GET_GOT
	add	sl, pc, sl
.L_GOT_GOT:
	@ Store the highest stack address
	ldr	r1, .L_STACK_END
	ldr	r1, [sl, r1]
	str	sp, [r1]
	@ See if we were run as a command with the executable file
	@ name as an extra leading argument.
	ldr	r4, .L_SKIP_ARGS
	ldr	r4, [sl, r4]
	@ get the original arg count
	ldr	r1, [sp]
	@ subtract _dl_skip_args from it
	sub	r1, r1, r4
	@ adjust the stack pointer to skip them
	add	sp, sp, r4, lsl #2
	@ get the argv address
	add	r2, sp, #4
	@ store the new argc in the new stack location
	str	r1, [sp]
	@ compute envp
	add	r3, r2, r1, lsl #2
	add	r3, r3, #4

	@ now we call _dl_init
	ldr	r0, .L_LOADED
	ldr	r0, [sl, r0]
	ldr	r0, [r0]
	@ call _dl_init
	bl	_dl_init(PLT)
	@ clear the startup flag
	ldr	r2, .L_STARTUP_FLAG
	ldr	r1, [sl, r2]
	mov	r0, #0
	str	r0, [r1]
	@ load the finalizer function
	ldr	r0, .L_FINI_PROC
	ldr	r0, [sl, r0]
	@ jump to the user_s entry point
	mov	pc, r6
.L_GET_GOT:
	.word	_GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4	\n\
.L_SKIP_ARGS:					\n\
	.word	_dl_skip_args(GOTOFF)		\n\
.L_STARTUP_FLAG:
	.word	_dl_starting_up(GOT)
.L_FINI_PROC:
	.word	_dl_fini(GOT)
.L_STACK_END:
	.word	__libc_stack_end(GOT)
.L_LOADED:
	.word	_dl_loaded(GOT)
.previous\n\
");

/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
   PLT entries should not be allowed to define the value.
   ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
   of the main executable's symbols, as for a COPY reloc.  */
#define elf_machine_type_class(type) \
  ((((type) == R_ARM_JUMP_SLOT) * ELF_RTYPE_CLASS_PLT)	\
   | (((type) == R_ARM_COPY) * ELF_RTYPE_CLASS_COPY))

/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
#define ELF_MACHINE_JMP_SLOT	R_ARM_JUMP_SLOT

/* The ARM never uses Elf32_Rela relocations.  */
#define ELF_MACHINE_NO_RELA 1

/* We define an initialization functions.  This is called very early in
   _dl_sysdep_start.  */
#define DL_PLATFORM_INIT dl_platform_init ()

extern const char *_dl_platform;

static inline void __attribute__ ((unused))
dl_platform_init (void)
{
  if (_dl_platform != NULL && *_dl_platform == '\0')
    /* Avoid an empty string which would disturb us.  */
    _dl_platform = NULL;
}

static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
		       const Elf32_Rel *reloc,
		       Elf32_Addr *reloc_addr, Elf32_Addr value)
{
  return *reloc_addr = value;
}

/* Return the final value of a plt relocation.  */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rel *reloc,
		       Elf32_Addr value)
{
  return value;
}

#endif /* !dl_machine_h */

#ifdef RESOLVE

extern char **_dl_argv;

/* Deal with an out-of-range PC24 reloc.  */
static Elf32_Addr
fix_bad_pc24 (Elf32_Addr *const reloc_addr, Elf32_Addr value)
{
  static void *fix_page;
  static unsigned int fix_offset;
  static size_t pagesize;
  Elf32_Word *fix_address;

  if (! fix_page)
    {
      if (! pagesize)
	pagesize = getpagesize ();
      fix_page = mmap (NULL, pagesize, PROT_READ | PROT_WRITE | PROT_EXEC,
		       MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
      if (! fix_page)
	assert (! "could not map page for fixup");
      fix_offset = 0;
    }

  fix_address = (Elf32_Word *)(fix_page + fix_offset);
  fix_address[0] = 0xe51ff004;	/* ldr pc, [pc, #-4] */
  fix_address[1] = value;

  fix_offset += 8;
  if (fix_offset >= pagesize)
    fix_page = NULL;

  return (Elf32_Addr)fix_address;
}

/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
   MAP is the object containing the reloc.  */

static inline void
elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
		 const Elf32_Sym *sym, const struct r_found_version *version,
		 Elf32_Addr *const reloc_addr)
{
  const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);

  if (__builtin_expect (r_type == R_ARM_RELATIVE, 0))
    {
#ifndef RTLD_BOOTSTRAP
      if (map != &_dl_rtld_map) /* Already done in rtld itself.  */
#endif
	*reloc_addr += map->l_addr;
    }
#ifndef RTLD_BOOTSTRAP
  else if (__builtin_expect (r_type == R_ARM_NONE, 0))
    return;
#endif
  else
    {
      const Elf32_Sym *const refsym = sym;
      Elf32_Addr value = RESOLVE (&sym, version, r_type);
      if (sym)
	value += sym->st_value;

      switch (r_type)
	{
	case R_ARM_COPY:
	  if (sym == NULL)
	    /* This can happen in trace mode if an object could not be
	       found.  */
	    break;
	  if (sym->st_size > refsym->st_size
	      || (_dl_verbose && sym->st_size < refsym->st_size))
	    {
	      const char *strtab;

	      strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
	      _dl_error_printf ("\
%s: Symbol `%s' has different size in shared object, consider re-linking\n",
				_dl_argv[0] ?: "<program name unknown>",
				strtab + refsym->st_name);
	    }
	  memcpy (reloc_addr, (void *) value, MIN (sym->st_size,
						   refsym->st_size));
	  break;
	case R_ARM_GLOB_DAT:
	case R_ARM_JUMP_SLOT:
#ifdef RTLD_BOOTSTRAP
	  /* Fix weak undefined references.  */
	  if (sym != NULL && sym->st_value == 0)
	    *reloc_addr = 0;
	  else
#endif
	    *reloc_addr = value;
	  break;
	case R_ARM_ABS32:
	  {
#ifndef RTLD_BOOTSTRAP
	   /* This is defined in rtld.c, but nowhere in the static
	      libc.a; make the reference weak so static programs can
	      still link.  This declaration cannot be done when
	      compiling rtld.c (i.e.  #ifdef RTLD_BOOTSTRAP) because
	      rtld.c contains the common defn for _dl_rtld_map, which
	      is incompatible with a weak decl in the same file.  */
	    weak_extern (_dl_rtld_map);
	    if (map == &_dl_rtld_map)
	      /* Undo the relocation done here during bootstrapping.
		 Now we will relocate it anew, possibly using a
		 binding found in the user program or a loaded library
		 rather than the dynamic linker's built-in definitions
		 used while loading those libraries.  */
	      value -= map->l_addr + refsym->st_value;
#endif
	    *reloc_addr += value;
	    break;
	  }
	case R_ARM_PC24:
	  {
	     Elf32_Sword addend;
	     Elf32_Addr newvalue, topbits;

	     addend = *reloc_addr & 0x00ffffff;
	     if (addend & 0x00800000) addend |= 0xff000000;

	     newvalue = value - (Elf32_Addr)reloc_addr + (addend << 2);
	     topbits = newvalue & 0xfe000000;
	     if (topbits != 0xfe000000 && topbits != 0x00000000)
	       {
		 newvalue = fix_bad_pc24(reloc_addr, value)
		   - (Elf32_Addr)reloc_addr + (addend << 2);
		 topbits = newvalue & 0xfe000000;
		 if (topbits != 0xfe000000 && topbits != 0x00000000)
		   {
		     _dl_signal_error (0, map->l_name, NULL,
				       "R_ARM_PC24 relocation out of range");
		   }
	       }
	     newvalue >>= 2;
	     value = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff);
	     *reloc_addr = value;
	  }
	break;
	default:
	  _dl_reloc_bad_type (map, r_type, 0);
	  break;
	}
    }
}

static inline void
elf_machine_rel_relative (Elf32_Addr l_addr, const Elf32_Rel *reloc,
			  Elf32_Addr *const reloc_addr)
{
  *reloc_addr += l_addr;
}

static inline void
elf_machine_lazy_rel (struct link_map *map,
		      Elf32_Addr l_addr, const Elf32_Rel *reloc)
{
  Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
  const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
  /* Check for unexpected PLT reloc type.  */
  if (__builtin_expect (r_type == R_ARM_JUMP_SLOT, 1))
    *reloc_addr += l_addr;
  else
    _dl_reloc_bad_type (map, r_type, 1);
}

#endif /* RESOLVE */