about summary refs log tree commit diff
path: root/sysdeps/powerpc/powerpc32/dl-machine.h
blob: 31c7f3f95a2ce1b2a7e66e5f526e859e6a74bc42 (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
/* Machine-dependent ELF dynamic relocation inline functions.  PowerPC version.
   Copyright (C) 1995-2018 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, see
   <http://www.gnu.org/licenses/>.  */

#ifndef dl_machine_h
#define dl_machine_h

#define ELF_MACHINE_NAME "powerpc"

#include <assert.h>
#include <dl-tls.h>
#include <dl-irel.h>
#include <hwcapinfo.h>

/* Translate a processor specific dynamic tag to the index
   in l_info array.  */
#define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM)

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

/* Return the value of the GOT pointer.  */
static inline Elf32_Addr * __attribute__ ((const))
ppc_got (void)
{
  Elf32_Addr *got;

  asm ("bcl 20,31,1f\n"
       "1:	mflr %0\n"
       "	addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n"
       "	addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n"
       : "=b" (got) : : "lr");

  return got;
}

/* Return the link-time address of _DYNAMIC, stored as
   the first value in the GOT. */
static inline Elf32_Addr __attribute__ ((const))
elf_machine_dynamic (void)
{
  return *ppc_got ();
}

/* Return the run-time load address of the shared object.  */
static inline Elf32_Addr __attribute__ ((const))
elf_machine_load_address (void)
{
  Elf32_Addr *branchaddr;
  Elf32_Addr runtime_dynamic;

  /* This is much harder than you'd expect.  Possibly I'm missing something.
     The 'obvious' way:

       Apparently, "bcl 20,31,$+4" is what should be used to load LR
       with the address of the next instruction.
       I think this is so that machines that do bl/blr pairing don't
       get confused.

     asm ("bcl 20,31,0f ;"
	  "0: mflr 0 ;"
	  "lis %0,0b@ha;"
	  "addi %0,%0,0b@l;"
	  "subf %0,%0,0"
	  : "=b" (addr) : : "r0", "lr");

     doesn't work, because the linker doesn't have to (and in fact doesn't)
     update the @ha and @l references; the loader (which runs after this
     code) will do that.

     Instead, we use the following trick:

     The linker puts the _link-time_ address of _DYNAMIC at the first
     word in the GOT. We could branch to that address, if we wanted,
     by using an @local reloc; the linker works this out, so it's safe
     to use now. We can't, of course, actually branch there, because
     we'd cause an illegal instruction exception; so we need to compute
     the address ourselves. That gives us the following code: */

  /* Get address of the 'b _DYNAMIC@local'...  */
  asm ("bcl 20,31,0f;"
       "b _DYNAMIC@local;"
       "0:"
       : "=l" (branchaddr));

  /* So now work out the difference between where the branch actually points,
     and the offset of that location in memory from the start of the file.  */
  runtime_dynamic = ((Elf32_Addr) branchaddr
		     + ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6));

  return runtime_dynamic - elf_machine_dynamic ();
}

#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */

/* The PLT uses Elf32_Rela relocs.  */
#define elf_machine_relplt elf_machine_rela

/* Mask identifying addresses reserved for the user program,
   where the dynamic linker should not map anything.  */
#define ELF_MACHINE_USER_ADDRESS_MASK	0xf0000000UL

/* The actual _start code is in dl-start.S.  Use a really
   ugly bit of assembler to let dl-start.o see _dl_start.  */
#define RTLD_START asm (".globl _dl_start");

/* Decide where a relocatable object should be loaded.  */
extern ElfW(Addr)
__elf_preferred_address(struct link_map *loader, size_t maplength,
			ElfW(Addr) mapstartpref);
#define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
  __elf_preferred_address (loader, maplength, mapstartpref)

/* 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_COPY iff TYPE should not be allowed to resolve to one
   of the main executable's symbols, as for a COPY reloc.  */
/* We never want to use a PLT entry as the destination of a
   reloc, when what is being relocated is a branch. This is
   partly for efficiency, but mostly so we avoid loops.  */
#define elf_machine_type_class(type)			\
  ((((type) == R_PPC_JMP_SLOT				\
    || (type) == R_PPC_REL24				\
    || ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */	\
	&& (type) <= R_PPC_DTPREL32)			\
    || (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT)	\
   | (((type) == R_PPC_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_PPC_JMP_SLOT

/* The PowerPC never uses REL relocations.  */
#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0

/* We define an initialization function to initialize HWCAP/HWCAP2 and
   platform data so it can be copied into the TCB later.  This is called
   very early in _dl_sysdep_start for dynamically linked binaries.  */
#ifdef SHARED
# define DL_PLATFORM_INIT dl_platform_init ()

static inline void __attribute__ ((unused))
dl_platform_init (void)
{
  __tcb_parse_hwcap_and_convert_at_platform ();
}
#endif

/* Set up the loaded object described by MAP so its unrelocated PLT
   entries will jump to the on-demand fixup code in dl-runtime.c.
   Also install a small trampoline to be used by entries that have
   been relocated to an address too far away for a single branch.  */
extern int __elf_machine_runtime_setup (struct link_map *map,
					int lazy, int profile);

static inline int
elf_machine_runtime_setup (struct link_map *map,
			   int lazy, int profile)
{
  if (map->l_info[DT_JMPREL] == 0)
    return lazy;

  if (map->l_info[DT_PPC(GOT)] == 0)
    /* Handle old style PLT.  */
    return __elf_machine_runtime_setup (map, lazy, profile);

  /* New style non-exec PLT consisting of an array of addresses.  */
  map->l_info[DT_PPC(GOT)]->d_un.d_ptr += map->l_addr;
  if (lazy)
    {
      Elf32_Addr *plt, *got, glink;
      Elf32_Word num_plt_entries;
      void (*dlrr) (void);
      extern void _dl_runtime_resolve (void);
      extern void _dl_prof_resolve (void);

      if (__glibc_likely (!profile))
	dlrr = _dl_runtime_resolve;
      else
	{
	  if (GLRO(dl_profile) != NULL
	      &&_dl_name_match_p (GLRO(dl_profile), map))
	    GL(dl_profile_map) = map;
	  dlrr = _dl_prof_resolve;
	}
      got = (Elf32_Addr *) map->l_info[DT_PPC(GOT)]->d_un.d_ptr;
      glink = got[1];
      got[1] = (Elf32_Addr) dlrr;
      got[2] = (Elf32_Addr) map;

      /* Relocate everything in .plt by the load address offset.  */
      plt = (Elf32_Addr *) D_PTR (map, l_info[DT_PLTGOT]);
      num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
			 / sizeof (Elf32_Rela));

      /* If a library is prelinked but we have to relocate anyway,
	 we have to be able to undo the prelinking of .plt section.
	 The prelinker saved us at got[1] address of .glink
	 section's start.  */
      if (glink)
	{
	  glink += map->l_addr;
	  while (num_plt_entries-- != 0)
	    *plt++ = glink, glink += 4;
	}
      else
	while (num_plt_entries-- != 0)
	  *plt++ += map->l_addr;
    }
  return lazy;
}

/* Change the PLT entry whose reloc is 'reloc' to call the actual routine.  */
extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
					   Elf32_Addr *reloc_addr,
					   Elf32_Addr finaladdr);

static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
		       const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
		       const Elf32_Rela *reloc,
		       Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
{
  if (map->l_info[DT_PPC(GOT)] == 0)
    /* Handle old style PLT.  */
    return __elf_machine_fixup_plt (map, reloc_addr, finaladdr);

  *reloc_addr = finaladdr;
  return finaladdr;
}

/* Return the final value of a plt relocation.  */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
		       Elf32_Addr value)
{
  return value + reloc->r_addend;
}


/* Names of the architecture-specific auditing callback functions.  */
#define ARCH_LA_PLTENTER ppc32_gnu_pltenter
#define ARCH_LA_PLTEXIT ppc32_gnu_pltexit

#endif /* dl_machine_h */

#ifdef RESOLVE_MAP

/* Do the actual processing of a reloc, once its target address
   has been determined.  */
extern void __process_machine_rela (struct link_map *map,
				    const Elf32_Rela *reloc,
				    struct link_map *sym_map,
				    const Elf32_Sym *sym,
				    const Elf32_Sym *refsym,
				    Elf32_Addr *const reloc_addr,
				    Elf32_Addr finaladdr,
				    int rinfo) attribute_hidden;

/* Call _dl_signal_error when a resolved value overflows a relocated area.  */
extern void _dl_reloc_overflow (struct link_map *map,
				const char *name,
				Elf32_Addr *const reloc_addr,
				const Elf32_Sym *refsym) attribute_hidden;

/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
   LOADADDR is the load address of the object; INFO is an array indexed
   by DT_* of the .dynamic section info.  */

auto inline void __attribute__ ((always_inline))
elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
		  const Elf32_Sym *sym, const struct r_found_version *version,
		  void *const reloc_addr_arg, int skip_ifunc)
{
  Elf32_Addr *const reloc_addr = reloc_addr_arg;
  const Elf32_Sym *const refsym = sym;
  Elf32_Addr value;
  const int r_type = ELF32_R_TYPE (reloc->r_info);
  struct link_map *sym_map = NULL;

#ifndef RESOLVE_CONFLICT_FIND_MAP
  if (r_type == R_PPC_RELATIVE)
    {
      *reloc_addr = map->l_addr + reloc->r_addend;
      return;
    }

  if (__glibc_unlikely (r_type == R_PPC_NONE))
    return;

  /* binutils on ppc32 includes st_value in r_addend for relocations
     against local symbols.  */
  if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0)
      && sym->st_shndx != SHN_UNDEF)
    {
      sym_map = map;
      value = map->l_addr;
    }
  else
    {
      sym_map = RESOLVE_MAP (&sym, version, r_type);
      value = SYMBOL_ADDRESS (sym_map, sym, true);
    }
  value += reloc->r_addend;
#else
  value = reloc->r_addend;
#endif

  if (sym != NULL
      && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
      && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
      && __builtin_expect (!skip_ifunc, 1))
    value = elf_ifunc_invoke (value);

  /* A small amount of code is duplicated here for speed.  In libc,
     more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
     libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
     R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
     wouldn't usually handle).  As an bonus, doing this here allows
     the switch statement in __process_machine_rela to work.  */
  switch (r_type)
    {
    case R_PPC_GLOB_DAT:
    case R_PPC_ADDR32:
      *reloc_addr = value;
      break;

#ifndef RESOLVE_CONFLICT_FIND_MAP
# ifdef RTLD_BOOTSTRAP
#  define NOT_BOOTSTRAP 0
# else
#  define NOT_BOOTSTRAP 1
# endif

    case R_PPC_DTPMOD32:
      if (map->l_info[DT_PPC(OPT)]
	  && (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
	{
	  if (!NOT_BOOTSTRAP)
	    {
	      reloc_addr[0] = 0;
	      reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
			       + TLS_DTV_OFFSET);
	      break;
	    }
	  else if (sym_map != NULL)
	    {
# ifndef SHARED
	      CHECK_STATIC_TLS (map, sym_map);
# else
	      if (TRY_STATIC_TLS (map, sym_map))
# endif
		{
		  reloc_addr[0] = 0;
		  /* Set up for local dynamic.  */
		  reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
				   + TLS_DTV_OFFSET);
		  break;
		}
	    }
	}
      if (!NOT_BOOTSTRAP)
	/* During startup the dynamic linker is always index 1.  */
	*reloc_addr = 1;
      else if (sym_map != NULL)
	/* Get the information from the link map returned by the
	   RESOLVE_MAP function.  */
	*reloc_addr = sym_map->l_tls_modid;
      break;
    case R_PPC_DTPREL32:
      if (map->l_info[DT_PPC(OPT)]
	  && (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
	{
	  if (!NOT_BOOTSTRAP)
	    {
	      *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
	      break;
	    }
	  else if (sym_map != NULL)
	    {
	      /* This reloc is always preceded by R_PPC_DTPMOD32.  */
# ifndef SHARED
	      assert (HAVE_STATIC_TLS (map, sym_map));
# else
	      if (HAVE_STATIC_TLS (map, sym_map))
# endif
		{
		  *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
		  break;
		}
	    }
	}
      /* During relocation all TLS symbols are defined and used.
	 Therefore the offset is already correct.  */
      if (NOT_BOOTSTRAP && sym_map != NULL)
	*reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
      break;
    case R_PPC_TPREL32:
      if (!NOT_BOOTSTRAP || sym_map != NULL)
	{
	  if (NOT_BOOTSTRAP)
	    CHECK_STATIC_TLS (map, sym_map);
	  *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
	}
      break;
#endif

    case R_PPC_JMP_SLOT:
#ifdef RESOLVE_CONFLICT_FIND_MAP
      RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr);
#endif
      if (map->l_info[DT_PPC(GOT)] != 0)
	{
	  *reloc_addr = value;
	  break;
	}
      /* FALLTHROUGH */

    default:
      __process_machine_rela (map, reloc, sym_map, sym, refsym,
			      reloc_addr, value, r_type);
    }
}

auto inline void __attribute__ ((always_inline))
elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
			   void *const reloc_addr_arg)
{
  Elf32_Addr *const reloc_addr = reloc_addr_arg;
  *reloc_addr = l_addr + reloc->r_addend;
}

auto inline void __attribute__ ((always_inline))
elf_machine_lazy_rel (struct link_map *map,
		      Elf32_Addr l_addr, const Elf32_Rela *reloc,
		      int skip_ifunc)
{
  /* elf_machine_runtime_setup handles this. */
}

#endif /* RESOLVE_MAP */