aboutsummaryrefslogtreecommitdiff
path: root/gdb/i386-fbsd-tdep.c
blob: 3848bf890d48f1792f54525917d6c83b2ccd625a (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
/* Target-dependent code for FreeBSD/i386.

   Copyright (C) 2003-2019 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 "arch-utils.h"
#include "gdbcore.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "i386-fbsd-tdep.h"
#include "gdbsupport/x86-xstate.h"

#include "i386-tdep.h"
#include "i387-tdep.h"
#include "fbsd-tdep.h"
#include "solib-svr4.h"

/* Support for signal handlers.  */

/* Return whether THIS_FRAME corresponds to a FreeBSD sigtramp
   routine.  */

/* FreeBSD/i386 supports three different signal trampolines, one for
   versions before 4.0, a second for 4.x, and a third for 5.0 and
   later.  To complicate matters, FreeBSD/i386 binaries running under
   an amd64 kernel use a different set of trampolines.  These
   trampolines differ from the i386 kernel trampolines in that they
   omit a middle section that conditionally restores %gs.  */

static const gdb_byte i386fbsd_sigtramp_start[] =
{
  0x8d, 0x44, 0x24, 0x20,       /* lea     SIGF_UC(%esp),%eax */
  0x50				/* pushl   %eax */
};

static const gdb_byte i386fbsd_sigtramp_middle[] =
{
  0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
				/* testl   $PSL_VM,UC_EFLAGS(%eax) */
  0x75, 0x03,			/* jne	   +3 */
  0x8e, 0x68, 0x14		/* mov	   UC_GS(%eax),%gs */
};

static const gdb_byte i386fbsd_sigtramp_end[] =
{
  0xb8, 0xa1, 0x01, 0x00, 0x00, /* movl   $SYS_sigreturn,%eax */
  0x50,			/* pushl   %eax */
  0xcd, 0x80			/* int	   $0x80 */
};

static const gdb_byte i386fbsd_freebsd4_sigtramp_start[] =
{
  0x8d, 0x44, 0x24, 0x14,	/* lea	   SIGF_UC4(%esp),%eax */
  0x50				/* pushl   %eax */
};

static const gdb_byte i386fbsd_freebsd4_sigtramp_middle[] =
{
  0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
				/* testl   $PSL_VM,UC4_EFLAGS(%eax) */
  0x75, 0x03,			/* jne	   +3 */
  0x8e, 0x68, 0x14		/* mov	   UC4_GS(%eax),%gs */
};

static const gdb_byte i386fbsd_freebsd4_sigtramp_end[] =
{
  0xb8, 0x58, 0x01, 0x00, 0x00, /* movl    $344,%eax */
  0x50,			/* pushl   %eax */
  0xcd, 0x80			/* int	   $0x80 */
};

static const gdb_byte i386fbsd_osigtramp_start[] =
{
  0x8d, 0x44, 0x24, 0x14,	/* lea	   SIGF_SC(%esp),%eax */
  0x50				/* pushl   %eax */
};

static const gdb_byte i386fbsd_osigtramp_middle[] =
{
  0xf7, 0x40, 0x18, 0x00, 0x00, 0x02, 0x00,
				/* testl   $PSL_VM,SC_PS(%eax) */
  0x75, 0x03,			/* jne	   +3 */
  0x8e, 0x68, 0x44		/* mov	   SC_GS(%eax),%gs */
};

static const gdb_byte i386fbsd_osigtramp_end[] =
{
  0xb8, 0x67, 0x00, 0x00, 0x00, /* movl    $103,%eax */
  0x50,			/* pushl   %eax */
  0xcd, 0x80			/* int	   $0x80 */
};

/* The three different trampolines are all the same size.  */
gdb_static_assert (sizeof i386fbsd_sigtramp_start
		   == sizeof i386fbsd_freebsd4_sigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_start
		   == sizeof i386fbsd_osigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
		   == sizeof i386fbsd_freebsd4_sigtramp_middle);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
		   == sizeof i386fbsd_osigtramp_middle);
gdb_static_assert (sizeof i386fbsd_sigtramp_end
		   == sizeof i386fbsd_freebsd4_sigtramp_end);
gdb_static_assert (sizeof i386fbsd_sigtramp_end
		   == sizeof i386fbsd_osigtramp_end);

/* We assume that the middle is the largest chunk below.  */
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
		   > sizeof i386fbsd_sigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
		   > sizeof i386fbsd_sigtramp_end);

static int
i386fbsd_sigtramp_p (struct frame_info *this_frame)
{
  CORE_ADDR pc = get_frame_pc (this_frame);
  gdb_byte buf[sizeof i386fbsd_sigtramp_middle];
  const gdb_byte *middle, *end;

  /* Look for a matching start.  */
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
				 sizeof i386fbsd_sigtramp_start))
    return 0;
  if (memcmp (buf, i386fbsd_sigtramp_start, sizeof i386fbsd_sigtramp_start)
      == 0)
    {
      middle = i386fbsd_sigtramp_middle;
      end = i386fbsd_sigtramp_end;
    }
  else if (memcmp (buf, i386fbsd_freebsd4_sigtramp_start,
		   sizeof i386fbsd_freebsd4_sigtramp_start) == 0)
    {
      middle = i386fbsd_freebsd4_sigtramp_middle;
      end = i386fbsd_freebsd4_sigtramp_end;
    }
  else if (memcmp (buf, i386fbsd_osigtramp_start,
		   sizeof i386fbsd_osigtramp_start) == 0)
    {
      middle = i386fbsd_osigtramp_middle;
      end = i386fbsd_osigtramp_end;
    }
  else
    return 0;

  /* Since the end is shorter than the middle, check for a matching end
     next.  */
  pc += sizeof i386fbsd_sigtramp_start;
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
				 sizeof i386fbsd_sigtramp_end))
    return 0;
  if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) == 0)
    return 1;

  /* If the end didn't match, check for a matching middle.  */
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
				 sizeof i386fbsd_sigtramp_middle))
    return 0;
  if (memcmp (buf, middle, sizeof i386fbsd_sigtramp_middle) != 0)
    return 0;

  /* The middle matched, check for a matching end.  */
  pc += sizeof i386fbsd_sigtramp_middle;
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
				 sizeof i386fbsd_sigtramp_end))
    return 0;
  if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) != 0)
    return 0;

  return 1;
}

/* FreeBSD 3.0-RELEASE or later.  */

/* From <machine/reg.h>.  */
static int i386fbsd_r_reg_offset[] =
{
  9 * 4, 8 * 4, 7 * 4, 6 * 4,	/* %eax, %ecx, %edx, %ebx */
  15 * 4, 4 * 4,		/* %esp, %ebp */
  3 * 4, 2 * 4,			/* %esi, %edi */
  12 * 4, 14 * 4,		/* %eip, %eflags */
  13 * 4, 16 * 4,		/* %cs, %ss */
  1 * 4, 0 * 4, -1, -1		/* %ds, %es, %fs, %gs */
};

/* Sigtramp routine location.  */
CORE_ADDR i386fbsd_sigtramp_start_addr;
CORE_ADDR i386fbsd_sigtramp_end_addr;

/* From <machine/signal.h>.  */
int i386fbsd_sc_reg_offset[] =
{
  8 + 14 * 4,			/* %eax */
  8 + 13 * 4,			/* %ecx */
  8 + 12 * 4,			/* %edx */
  8 + 11 * 4,			/* %ebx */
  8 + 0 * 4,                    /* %esp */
  8 + 1 * 4,                    /* %ebp */
  8 + 10 * 4,                   /* %esi */
  8 + 9 * 4,                    /* %edi */
  8 + 3 * 4,                    /* %eip */
  8 + 4 * 4,                    /* %eflags */
  8 + 7 * 4,                    /* %cs */
  8 + 8 * 4,                    /* %ss */
  8 + 6 * 4,                    /* %ds */
  8 + 5 * 4,                    /* %es */
  8 + 15 * 4,			/* %fs */
  8 + 16 * 4			/* %gs */
};

/* Get XSAVE extended state xcr0 from core dump.  */

uint64_t
i386fbsd_core_read_xcr0 (bfd *abfd)
{
  asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
  uint64_t xcr0;

  if (xstate)
    {
      size_t size = bfd_section_size (abfd, xstate);

      /* Check extended state size.  */
      if (size < X86_XSTATE_AVX_SIZE)
	xcr0 = X86_XSTATE_SSE_MASK;
      else
	{
	  char contents[8];

	  if (! bfd_get_section_contents (abfd, xstate, contents,
					  I386_FBSD_XSAVE_XCR0_OFFSET,
					  8))
	    {
	      warning (_("Couldn't read `xcr0' bytes from "
			 "`.reg-xstate' section in core file."));
	      return X86_XSTATE_SSE_MASK;
	    }

	  xcr0 = bfd_get_64 (abfd, contents);
	}
    }
  else
    xcr0 = X86_XSTATE_SSE_MASK;

  return xcr0;
}

/* Implement the core_read_description gdbarch method.  */

static const struct target_desc *
i386fbsd_core_read_description (struct gdbarch *gdbarch,
				struct target_ops *target,
				bfd *abfd)
{
  return i386_target_description (i386fbsd_core_read_xcr0 (abfd), true);
}

/* Similar to i386_supply_fpregset, but use XSAVE extended state.  */

static void
i386fbsd_supply_xstateregset (const struct regset *regset,
			      struct regcache *regcache, int regnum,
			      const void *xstateregs, size_t len)
{
  i387_supply_xsave (regcache, regnum, xstateregs);
}

/* Similar to i386_collect_fpregset, but use XSAVE extended state.  */

static void
i386fbsd_collect_xstateregset (const struct regset *regset,
			       const struct regcache *regcache,
			       int regnum, void *xstateregs, size_t len)
{
  i387_collect_xsave (regcache, regnum, xstateregs, 1);
}

/* Register set definitions.  */

static const struct regset i386fbsd_xstateregset =
  {
    NULL,
    i386fbsd_supply_xstateregset,
    i386fbsd_collect_xstateregset
  };

/* Iterate over core file register note sections.  */

static void
i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
				       iterate_over_regset_sections_cb *cb,
				       void *cb_data,
				       const struct regcache *regcache)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  cb (".reg", tdep->sizeof_gregset, tdep->sizeof_gregset, &i386_gregset, NULL,
      cb_data);
  cb (".reg2", tdep->sizeof_fpregset, tdep->sizeof_fpregset, &i386_fpregset,
      NULL, cb_data);

  if (tdep->xcr0 & X86_XSTATE_AVX)
    cb (".reg-xstate", X86_XSTATE_SIZE (tdep->xcr0),
	X86_XSTATE_SIZE (tdep->xcr0), &i386fbsd_xstateregset,
	"XSAVE extended state", cb_data);
}

/* Implement the get_thread_local_address gdbarch method.  */

static CORE_ADDR
i386fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
				   CORE_ADDR lm_addr, CORE_ADDR offset)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  struct regcache *regcache;

  if (tdep->fsbase_regnum == -1)
    error (_("Unable to fetch %%gsbase"));

  regcache = get_thread_arch_regcache (ptid, gdbarch);

  target_fetch_registers (regcache, tdep->fsbase_regnum + 1);

  ULONGEST gsbase;
  if (regcache->cooked_read (tdep->fsbase_regnum + 1, &gsbase) != REG_VALID)
    error (_("Unable to fetch %%gsbase"));

  CORE_ADDR dtv_addr = gsbase + gdbarch_ptr_bit (gdbarch) / 8;
  return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
}

static void
i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Obviously FreeBSD is BSD-based.  */
  i386bsd_init_abi (info, gdbarch);

  /* FreeBSD has a different `struct reg', and reserves some space for
     its FPU emulator in `struct fpreg'.  */
  tdep->gregset_reg_offset = i386fbsd_r_reg_offset;
  tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd_r_reg_offset);
  tdep->sizeof_gregset = 18 * 4;
  tdep->sizeof_fpregset = 176;

  /* FreeBSD uses -freg-struct-return by default.  */
  tdep->struct_return = reg_struct_return;

  tdep->sigtramp_p = i386fbsd_sigtramp_p;

  /* FreeBSD uses a different memory layout.  */
  tdep->sigtramp_start = i386fbsd_sigtramp_start_addr;
  tdep->sigtramp_end = i386fbsd_sigtramp_end_addr;

  /* FreeBSD has a more complete `struct sigcontext'.  */
  tdep->sc_reg_offset = i386fbsd_sc_reg_offset;
  tdep->sc_num_regs = ARRAY_SIZE (i386fbsd_sc_reg_offset);

  i386_elf_init_abi (info, gdbarch);

  /* FreeBSD uses SVR4-style shared libraries.  */
  set_solib_svr4_fetch_link_map_offsets
    (gdbarch, svr4_ilp32_fetch_link_map_offsets);
}

/* FreeBSD 4.0-RELEASE or later.  */

/* From <machine/reg.h>.  */
static int i386fbsd4_r_reg_offset[] =
{
  10 * 4, 9 * 4, 8 * 4, 7 * 4,	/* %eax, %ecx, %edx, %ebx */
  16 * 4, 5 * 4,		/* %esp, %ebp */
  4 * 4, 3 * 4,			/* %esi, %edi */
  13 * 4, 15 * 4,		/* %eip, %eflags */
  14 * 4, 17 * 4,		/* %cs, %ss */
  2 * 4, 1 * 4, 0 * 4, 18 * 4	/* %ds, %es, %fs, %gs */
};

/* From <machine/signal.h>.  */
int i386fbsd4_sc_reg_offset[] =
{
  20 + 11 * 4,			/* %eax */
  20 + 10 * 4,			/* %ecx */
  20 + 9 * 4,			/* %edx */
  20 + 8 * 4,			/* %ebx */
  20 + 17 * 4,			/* %esp */
  20 + 6 * 4,			/* %ebp */
  20 + 5 * 4,			/* %esi */
  20 + 4 * 4,			/* %edi */
  20 + 14 * 4,			/* %eip */
  20 + 16 * 4,			/* %eflags */
  20 + 15 * 4,			/* %cs */
  20 + 18 * 4,			/* %ss */
  20 + 3 * 4,			/* %ds */
  20 + 2 * 4,			/* %es */
  20 + 1 * 4,			/* %fs */
  20 + 0 * 4			/* %gs */
};

static void
i386fbsd4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Generic FreeBSD support. */
  fbsd_init_abi (info, gdbarch);

  /* Inherit stuff from older releases.  We assume that FreeBSD
     4.0-RELEASE always uses ELF.  */
  i386fbsd_init_abi (info, gdbarch);

  /* FreeBSD 4.0 introduced a new `struct reg'.  */
  tdep->gregset_reg_offset = i386fbsd4_r_reg_offset;
  tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd4_r_reg_offset);
  tdep->sizeof_gregset = 19 * 4;

  /* FreeBSD 4.0 introduced a new `struct sigcontext'.  */
  tdep->sc_reg_offset = i386fbsd4_sc_reg_offset;
  tdep->sc_num_regs = ARRAY_SIZE (i386fbsd4_sc_reg_offset);

  tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;

  /* Iterate over core file register note sections.  */
  set_gdbarch_iterate_over_regset_sections
    (gdbarch, i386fbsd_iterate_over_regset_sections);

  set_gdbarch_core_read_description (gdbarch,
				     i386fbsd_core_read_description);

  set_gdbarch_fetch_tls_load_module_address (gdbarch,
					     svr4_fetch_objfile_link_map);
  set_gdbarch_get_thread_local_address (gdbarch,
					i386fbsd_get_thread_local_address);
}

void
_initialize_i386fbsd_tdep (void)
{
  gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_FREEBSD,
			  i386fbsd4_init_abi);
}