aboutsummaryrefslogtreecommitdiff
path: root/gdb/m32r-linux-tdep.c
blob: 6606a64afa12fb1a4719a9744a1d6a2293de8950 (plain)
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
/* Target-dependent code for GNU/Linux m32r.

   Copyright (C) 2004-2022 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "gdbcore.h"
#include "frame.h"
#include "value.h"
#include "regcache.h"
#include "inferior.h"
#include "osabi.h"
#include "reggroups.h"
#include "regset.h"

#include "glibc-tdep.h"
#include "solib-svr4.h"
#include "symtab.h"

#include "trad-frame.h"
#include "frame-unwind.h"

#include "m32r-tdep.h"
#include "linux-tdep.h"
#include "gdbarch.h"



/* Recognizing signal handler frames.  */

/* GNU/Linux has two flavors of signals.  Normal signal handlers, and
   "realtime" (RT) signals.  The RT signals can provide additional
   information to the signal handler if the SA_SIGINFO flag is set
   when establishing a signal handler using `sigaction'.  It is not
   unlikely that future versions of GNU/Linux will support SA_SIGINFO
   for normal signals too.  */

/* When the m32r Linux kernel calls a signal handler and the
   SA_RESTORER flag isn't set, the return address points to a bit of
   code on the stack.  This function returns whether the PC appears to
   be within this bit of code.

   The instruction sequence for normal signals is
       ldi    r7, #__NR_sigreturn
       trap   #2
   or 0x67 0x77 0x10 0xf2.

   Checking for the code sequence should be somewhat reliable, because
   the effect is to call the system call sigreturn.  This is unlikely
   to occur anywhere other than in a signal trampoline.

   It kind of sucks that we have to read memory from the process in
   order to identify a signal trampoline, but there doesn't seem to be
   any other way.  Therefore we only do the memory reads if no
   function name could be identified, which should be the case since
   the code is on the stack.

   Detection of signal trampolines for handlers that set the
   SA_RESTORER flag is in general not possible.  Unfortunately this is
   what the GNU C Library has been doing for quite some time now.
   However, as of version 2.1.2, the GNU C Library uses signal
   trampolines (named __restore and __restore_rt) that are identical
   to the ones used by the kernel.  Therefore, these trampolines are
   supported too.  */

static const gdb_byte linux_sigtramp_code[] = {
  0x67, 0x77, 0x10, 0xf2,
};

/* If PC is in a sigtramp routine, return the address of the start of
   the routine.  Otherwise, return 0.  */

static CORE_ADDR
m32r_linux_sigtramp_start (CORE_ADDR pc, struct frame_info *this_frame)
{
  gdb_byte buf[4];

  /* We only recognize a signal trampoline if PC is at the start of
     one of the instructions.  We optimize for finding the PC at the
     start of the instruction sequence, as will be the case when the
     trampoline is not the first frame on the stack.  We assume that
     in the case where the PC is not at the start of the instruction
     sequence, there will be a few trailing readable bytes on the
     stack.  */

  if (pc % 2 != 0)
    {
      if (!safe_frame_unwind_memory (this_frame, pc, {buf, 2}))
	return 0;

      if (memcmp (buf, linux_sigtramp_code, 2) == 0)
	pc -= 2;
      else
	return 0;
    }

  if (!safe_frame_unwind_memory (this_frame, pc, {buf, 4}))
    return 0;

  if (memcmp (buf, linux_sigtramp_code, 4) != 0)
    return 0;

  return pc;
}

/* This function does the same for RT signals.  Here the instruction
   sequence is
       ldi    r7, #__NR_rt_sigreturn
       trap   #2
   or 0x97 0xf0 0x00 0xad 0x10 0xf2 0xf0 0x00.

   The effect is to call the system call rt_sigreturn.  */

static const gdb_byte linux_rt_sigtramp_code[] = {
  0x97, 0xf0, 0x00, 0xad, 0x10, 0xf2, 0xf0, 0x00,
};

/* If PC is in a RT sigtramp routine, return the address of the start
   of the routine.  Otherwise, return 0.  */

static CORE_ADDR
m32r_linux_rt_sigtramp_start (CORE_ADDR pc, struct frame_info *this_frame)
{
  gdb_byte buf[4];

  /* We only recognize a signal trampoline if PC is at the start of
     one of the instructions.  We optimize for finding the PC at the
     start of the instruction sequence, as will be the case when the
     trampoline is not the first frame on the stack.  We assume that
     in the case where the PC is not at the start of the instruction
     sequence, there will be a few trailing readable bytes on the
     stack.  */

  if (pc % 2 != 0)
    return 0;

  if (!safe_frame_unwind_memory (this_frame, pc, {buf, 4}))
    return 0;

  if (memcmp (buf, linux_rt_sigtramp_code, 4) == 0)
    {
      if (!safe_frame_unwind_memory (this_frame, pc + 4, {buf, 4}))
	return 0;

      if (memcmp (buf, linux_rt_sigtramp_code + 4, 4) == 0)
	return pc;
    }
  else if (memcmp (buf, linux_rt_sigtramp_code + 4, 4) == 0)
    {
      if (!safe_frame_unwind_memory (this_frame, pc - 4, {buf, 4}))
	return 0;

      if (memcmp (buf, linux_rt_sigtramp_code, 4) == 0)
	return pc - 4;
    }

  return 0;
}

static int
m32r_linux_pc_in_sigtramp (CORE_ADDR pc, const char *name,
			   struct frame_info *this_frame)
{
  /* If we have NAME, we can optimize the search.  The trampolines are
     named __restore and __restore_rt.  However, they aren't dynamically
     exported from the shared C library, so the trampoline may appear to
     be part of the preceding function.  This should always be sigaction,
     __sigaction, or __libc_sigaction (all aliases to the same function).  */
  if (name == NULL || strstr (name, "sigaction") != NULL)
    return (m32r_linux_sigtramp_start (pc, this_frame) != 0
	    || m32r_linux_rt_sigtramp_start (pc, this_frame) != 0);

  return (strcmp ("__restore", name) == 0
	  || strcmp ("__restore_rt", name) == 0);
}

/* From <asm/sigcontext.h>.  */
static int m32r_linux_sc_reg_offset[] = {
  4 * 4,			/* r0 */
  5 * 4,			/* r1 */
  6 * 4,			/* r2 */
  7 * 4,			/* r3 */
  0 * 4,			/* r4 */
  1 * 4,			/* r5 */
  2 * 4,			/* r6 */
  8 * 4,			/* r7 */
  9 * 4,			/* r8 */
  10 * 4,			/* r9 */
  11 * 4,			/* r10 */
  12 * 4,			/* r11 */
  13 * 4,			/* r12 */
  21 * 4,			/* fp */
  22 * 4,			/* lr */
  -1 * 4,			/* sp */
  16 * 4,			/* psw */
  -1 * 4,			/* cbr */
  23 * 4,			/* spi */
  20 * 4,			/* spu */
  19 * 4,			/* bpc */
  17 * 4,			/* pc */
  15 * 4,			/* accl */
  14 * 4			/* acch */
};

struct m32r_frame_cache
{
  CORE_ADDR base, pc;
  trad_frame_saved_reg *saved_regs;
};

static struct m32r_frame_cache *
m32r_linux_sigtramp_frame_cache (struct frame_info *this_frame,
				 void **this_cache)
{
  struct m32r_frame_cache *cache;
  CORE_ADDR sigcontext_addr, addr;
  int regnum;

  if ((*this_cache) != NULL)
    return (struct m32r_frame_cache *) (*this_cache);
  cache = FRAME_OBSTACK_ZALLOC (struct m32r_frame_cache);
  (*this_cache) = cache;
  cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);

  cache->base = get_frame_register_unsigned (this_frame, M32R_SP_REGNUM);
  sigcontext_addr = cache->base + 4;

  cache->pc = get_frame_pc (this_frame);
  addr = m32r_linux_sigtramp_start (cache->pc, this_frame);
  if (addr == 0)
    {
      /* If this is a RT signal trampoline, adjust SIGCONTEXT_ADDR
	 accordingly.  */
      addr = m32r_linux_rt_sigtramp_start (cache->pc, this_frame);
      if (addr)
	sigcontext_addr += 128;
      else
	addr = get_frame_func (this_frame);
    }
  cache->pc = addr;

  cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);

  for (regnum = 0; regnum < sizeof (m32r_linux_sc_reg_offset) / 4; regnum++)
    {
      if (m32r_linux_sc_reg_offset[regnum] >= 0)
	cache->saved_regs[regnum].set_addr (sigcontext_addr
					    + m32r_linux_sc_reg_offset[regnum]);
    }

  return cache;
}

static void
m32r_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
				   void **this_cache,
				   struct frame_id *this_id)
{
  struct m32r_frame_cache *cache =
    m32r_linux_sigtramp_frame_cache (this_frame, this_cache);

  (*this_id) = frame_id_build (cache->base, cache->pc);
}

static struct value *
m32r_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
					 void **this_cache, int regnum)
{
  struct m32r_frame_cache *cache =
    m32r_linux_sigtramp_frame_cache (this_frame, this_cache);

  return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
}

static int
m32r_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
				   struct frame_info *this_frame,
				   void **this_cache)
{
  CORE_ADDR pc = get_frame_pc (this_frame);
  const char *name;

  find_pc_partial_function (pc, &name, NULL, NULL);
  if (m32r_linux_pc_in_sigtramp (pc, name, this_frame))
    return 1;

  return 0;
}

static const struct frame_unwind m32r_linux_sigtramp_frame_unwind = {
  "m32r linux sigtramp",
  SIGTRAMP_FRAME,
  default_frame_unwind_stop_reason,
  m32r_linux_sigtramp_frame_this_id,
  m32r_linux_sigtramp_frame_prev_register,
  NULL,
  m32r_linux_sigtramp_frame_sniffer
};

/* Mapping between the registers in `struct pt_regs'
   format and GDB's register array layout.  */

static int m32r_pt_regs_offset[] = {
  4 * 4,			/* r0 */
  4 * 5,			/* r1 */
  4 * 6,			/* r2 */
  4 * 7,			/* r3 */
  4 * 0,			/* r4 */
  4 * 1,			/* r5 */
  4 * 2,			/* r6 */
  4 * 8,			/* r7 */
  4 * 9,			/* r8 */
  4 * 10,			/* r9 */
  4 * 11,			/* r10 */
  4 * 12,			/* r11 */
  4 * 13,			/* r12 */
  4 * 24,			/* fp */
  4 * 25,			/* lr */
  4 * 23,			/* sp */
  4 * 19,			/* psw */
  4 * 19,			/* cbr */
  4 * 26,			/* spi */
  4 * 23,			/* spu */
  4 * 22,			/* bpc */
  4 * 20,			/* pc */
  4 * 16,			/* accl */
  4 * 15			/* acch */
};

#define PSW_OFFSET (4 * 19)
#define BBPSW_OFFSET (4 * 21)
#define SPU_OFFSET (4 * 23)
#define SPI_OFFSET (4 * 26)

#define M32R_LINUX_GREGS_SIZE (4 * 28)

static void
m32r_linux_supply_gregset (const struct regset *regset,
			   struct regcache *regcache, int regnum,
			   const void *gregs, size_t size)
{
  const gdb_byte *regs = (const gdb_byte *) gregs;
  enum bfd_endian byte_order =
    gdbarch_byte_order (regcache->arch ());
  ULONGEST psw, bbpsw;
  gdb_byte buf[4];
  const gdb_byte *p;
  int i;

  psw = extract_unsigned_integer (regs + PSW_OFFSET, 4, byte_order);
  bbpsw = extract_unsigned_integer (regs + BBPSW_OFFSET, 4, byte_order);
  psw = ((0x00c1 & bbpsw) << 8) | ((0xc100 & psw) >> 8);

  for (i = 0; i < ARRAY_SIZE (m32r_pt_regs_offset); i++)
    {
      if (regnum != -1 && regnum != i)
	continue;

      switch (i)
	{
	case PSW_REGNUM:
	  store_unsigned_integer (buf, 4, byte_order, psw);
	  p = buf;
	  break;
	case CBR_REGNUM:
	  store_unsigned_integer (buf, 4, byte_order, psw & 1);
	  p = buf;
	  break;
	case M32R_SP_REGNUM:
	  p = regs + ((psw & 0x80) ? SPU_OFFSET : SPI_OFFSET);
	  break;
	default:
	  p = regs + m32r_pt_regs_offset[i];
	}

      regcache->raw_supply (i, p);
    }
}

static void
m32r_linux_collect_gregset (const struct regset *regset,
			    const struct regcache *regcache,
			    int regnum, void *gregs, size_t size)
{
  gdb_byte *regs = (gdb_byte *) gregs;
  int i;
  enum bfd_endian byte_order =
    gdbarch_byte_order (regcache->arch ());
  ULONGEST psw;
  gdb_byte buf[4];

  regcache->raw_collect (PSW_REGNUM, buf);
  psw = extract_unsigned_integer (buf, 4, byte_order);

  for (i = 0; i < ARRAY_SIZE (m32r_pt_regs_offset); i++)
    {
      if (regnum != -1 && regnum != i)
	continue;

      switch (i)
	{
	case PSW_REGNUM:
	  store_unsigned_integer (regs + PSW_OFFSET, 4, byte_order,
				  (psw & 0xc1) << 8);
	  store_unsigned_integer (regs + BBPSW_OFFSET, 4, byte_order,
				  (psw >> 8) & 0xc1);
	  break;
	case CBR_REGNUM:
	  break;
	case M32R_SP_REGNUM:
	  regcache->raw_collect
	    (i, regs + ((psw & 0x80) ? SPU_OFFSET : SPI_OFFSET));
	  break;
	default:
	  regcache->raw_collect (i, regs + m32r_pt_regs_offset[i]);
	}
    }
}

static const struct regset m32r_linux_gregset = {
  NULL,
  m32r_linux_supply_gregset, m32r_linux_collect_gregset
};

static void
m32r_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
					 iterate_over_regset_sections_cb *cb,
					 void *cb_data,
					 const struct regcache *regcache)
{
  cb (".reg", M32R_LINUX_GREGS_SIZE, M32R_LINUX_GREGS_SIZE, &m32r_linux_gregset,
      NULL, cb_data);
}

static void
m32r_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{

  linux_init_abi (info, gdbarch, 0);

  /* Since EVB register is not available for native debug, we reduce
     the number of registers.  */
  set_gdbarch_num_regs (gdbarch, M32R_NUM_REGS - 1);

  frame_unwind_append_unwinder (gdbarch, &m32r_linux_sigtramp_frame_unwind);

  /* GNU/Linux uses SVR4-style shared libraries.  */
  set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
  set_solib_svr4_fetch_link_map_offsets
    (gdbarch, linux_ilp32_fetch_link_map_offsets);

  /* Core file support.  */
  set_gdbarch_iterate_over_regset_sections
    (gdbarch, m32r_linux_iterate_over_regset_sections);

  /* Enable TLS support.  */
  set_gdbarch_fetch_tls_load_module_address (gdbarch,
					     svr4_fetch_objfile_link_map);
}

void _initialize_m32r_linux_tdep ();
void
_initialize_m32r_linux_tdep ()
{
  gdbarch_register_osabi (bfd_arch_m32r, 0, GDB_OSABI_LINUX,
			  m32r_linux_init_abi);
}