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
|
/* Target-dependent code for OpenBSD/amd64.
Copyright (C) 2003-2017 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 "frame.h"
#include "frame-unwind.h"
#include "gdbcore.h"
#include "symtab.h"
#include "objfiles.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "target.h"
#include "trad-frame.h"
#include "obsd-tdep.h"
#include "amd64-tdep.h"
#include "i387-tdep.h"
#include "x86-xstate.h"
#include "solib-svr4.h"
#include "bsd-uthread.h"
/* Support for signal handlers. */
/* Default page size. */
static const int amd64obsd_page_size = 4096;
/* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
routine. */
static int
amd64obsd_sigtramp_p (struct frame_info *this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
const gdb_byte osigreturn[] =
{
0x48, 0xc7, 0xc0,
0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
0xcd, 0x80 /* int $0x80 */
};
const gdb_byte sigreturn[] =
{
0x48, 0xc7, 0xc0,
0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
0x0f, 0x05 /* syscall */
};
size_t buflen = (sizeof sigreturn) + 1;
gdb_byte *buf;
const char *name;
/* If the function has a valid symbol name, it isn't a
trampoline. */
find_pc_partial_function (pc, &name, NULL, NULL);
if (name != NULL)
return 0;
/* If the function lives in a valid section (even without a starting
point) it isn't a trampoline. */
if (find_pc_section (pc) != NULL)
return 0;
/* If we can't read the instructions at START_PC, return zero. */
buf = (gdb_byte *) alloca ((sizeof sigreturn) + 1);
if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
return 0;
/* Check for sigreturn(2). Depending on how the assembler encoded
the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
7. OpenBSD 5.0 and later use the `syscall' instruction. Older
versions use `int $0x80'. Check for both. */
if (memcmp (buf, sigreturn, sizeof sigreturn)
&& memcmp (buf + 1, sigreturn, sizeof sigreturn)
&& memcmp (buf, osigreturn, sizeof osigreturn)
&& memcmp (buf + 1, osigreturn, sizeof osigreturn))
return 0;
return 1;
}
/* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
address of the associated sigcontext structure. */
static CORE_ADDR
amd64obsd_sigcontext_addr (struct frame_info *this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
ULONGEST offset = (pc & (amd64obsd_page_size - 1));
/* The %rsp register points at `struct sigcontext' upon entry of a
signal trampoline. The relevant part of the trampoline is
call *%rax
movq %rsp, %rdi
pushq %rdi
movq $SYS_sigreturn,%rax
int $0x80
(see /usr/src/sys/arch/amd64/amd64/locore.S). The `pushq'
instruction clobbers %rsp, but its value is saved in `%rdi'. */
if (offset > 5)
return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
else
return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
}
/* OpenBSD 3.5 or later. */
/* Mapping between the general-purpose registers in `struct reg'
format and GDB's register cache layout. */
/* From <machine/reg.h>. */
int amd64obsd_r_reg_offset[] =
{
14 * 8, /* %rax */
13 * 8, /* %rbx */
3 * 8, /* %rcx */
2 * 8, /* %rdx */
1 * 8, /* %rsi */
0 * 8, /* %rdi */
12 * 8, /* %rbp */
15 * 8, /* %rsp */
4 * 8, /* %r8 .. */
5 * 8,
6 * 8,
7 * 8,
8 * 8,
9 * 8,
10 * 8,
11 * 8, /* ... %r15 */
16 * 8, /* %rip */
17 * 8, /* %eflags */
18 * 8, /* %cs */
19 * 8, /* %ss */
20 * 8, /* %ds */
21 * 8, /* %es */
22 * 8, /* %fs */
23 * 8 /* %gs */
};
/* From <machine/signal.h>. */
static int amd64obsd_sc_reg_offset[] =
{
14 * 8, /* %rax */
13 * 8, /* %rbx */
3 * 8, /* %rcx */
2 * 8, /* %rdx */
1 * 8, /* %rsi */
0 * 8, /* %rdi */
12 * 8, /* %rbp */
24 * 8, /* %rsp */
4 * 8, /* %r8 ... */
5 * 8,
6 * 8,
7 * 8,
8 * 8,
9 * 8,
10 * 8,
11 * 8, /* ... %r15 */
21 * 8, /* %rip */
23 * 8, /* %eflags */
22 * 8, /* %cs */
25 * 8, /* %ss */
18 * 8, /* %ds */
17 * 8, /* %es */
16 * 8, /* %fs */
15 * 8 /* %gs */
};
/* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c. */
static int amd64obsd_uthread_reg_offset[] =
{
19 * 8, /* %rax */
16 * 8, /* %rbx */
18 * 8, /* %rcx */
17 * 8, /* %rdx */
14 * 8, /* %rsi */
13 * 8, /* %rdi */
15 * 8, /* %rbp */
-1, /* %rsp */
12 * 8, /* %r8 ... */
11 * 8,
10 * 8,
9 * 8,
8 * 8,
7 * 8,
6 * 8,
5 * 8, /* ... %r15 */
20 * 8, /* %rip */
4 * 8, /* %eflags */
21 * 8, /* %cs */
-1, /* %ss */
3 * 8, /* %ds */
2 * 8, /* %es */
1 * 8, /* %fs */
0 * 8 /* %gs */
};
/* Offset within the thread structure where we can find the saved
stack pointer (%esp). */
#define AMD64OBSD_UTHREAD_RSP_OFFSET 400
static void
amd64obsd_supply_uthread (struct regcache *regcache,
int regnum, CORE_ADDR addr)
{
struct gdbarch *gdbarch = get_regcache_arch (regcache);
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
CORE_ADDR sp = 0;
gdb_byte buf[8];
int i;
gdb_assert (regnum >= -1);
if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
{
int offset;
/* Fetch stack pointer from thread structure. */
sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
/* Adjust the stack pointer such that it looks as if we just
returned from _thread_machdep_switch. */
offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
store_unsigned_integer (buf, 8, byte_order, sp + offset);
regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
}
for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
{
if (amd64obsd_uthread_reg_offset[i] != -1
&& (regnum == -1 || regnum == i))
{
/* Fetch stack pointer from thread structure (if we didn't
do so already). */
if (sp == 0)
sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
/* Read the saved register from the stack frame. */
read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
regcache_raw_supply (regcache, i, buf);
}
}
}
static void
amd64obsd_collect_uthread (const struct regcache *regcache,
int regnum, CORE_ADDR addr)
{
struct gdbarch *gdbarch = get_regcache_arch (regcache);
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
CORE_ADDR sp = 0;
gdb_byte buf[8];
int i;
gdb_assert (regnum >= -1);
if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
{
int offset;
/* Calculate the stack pointer (frame pointer) that will be
stored into the thread structure. */
offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
/* Store the stack pointer. */
write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
/* The stack pointer was (potentially) modified. Make sure we
build a proper stack frame. */
regnum = -1;
}
for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
{
if (amd64obsd_uthread_reg_offset[i] != -1
&& (regnum == -1 || regnum == i))
{
/* Fetch stack pointer from thread structure (if we didn't
calculate it already). */
if (sp == 0)
sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
/* Write the register into the stack frame. */
regcache_raw_collect (regcache, i, buf);
write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
}
}
}
/* Kernel debugging support. */
/* From <machine/frame.h>. Easy since `struct trapframe' matches
`struct sigcontext'. */
#define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
static struct trad_frame_cache *
amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
struct trad_frame_cache *cache;
CORE_ADDR func, sp, addr;
ULONGEST cs;
const char *name;
int i;
if (*this_cache)
return (struct trad_frame_cache *) *this_cache;
cache = trad_frame_cache_zalloc (this_frame);
*this_cache = cache;
func = get_frame_func (this_frame);
sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
find_pc_partial_function (func, &name, NULL, NULL);
if (name && startswith (name, "Xintr"))
addr = sp + 8; /* It's an interrupt frame. */
else
addr = sp;
for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
if (amd64obsd_tf_reg_offset[i] != -1)
trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
/* Read %cs from trap frame. */
addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
cs = read_memory_unsigned_integer (addr, 8, byte_order);
if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
{
/* Trap from user space; terminate backtrace. */
trad_frame_set_id (cache, outer_frame_id);
}
else
{
/* Construct the frame ID using the function start. */
trad_frame_set_id (cache, frame_id_build (sp + 16, func));
}
return cache;
}
static void
amd64obsd_trapframe_this_id (struct frame_info *this_frame,
void **this_cache, struct frame_id *this_id)
{
struct trad_frame_cache *cache =
amd64obsd_trapframe_cache (this_frame, this_cache);
trad_frame_get_id (cache, this_id);
}
static struct value *
amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
void **this_cache, int regnum)
{
struct trad_frame_cache *cache =
amd64obsd_trapframe_cache (this_frame, this_cache);
return trad_frame_get_register (cache, this_frame, regnum);
}
static int
amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
struct frame_info *this_frame,
void **this_prologue_cache)
{
ULONGEST cs;
const char *name;
/* Check Current Privilege Level and bail out if we're not executing
in kernel space. */
cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
return 0;
find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
return (name && ((strcmp (name, "calltrap") == 0)
|| (strcmp (name, "osyscall1") == 0)
|| (strcmp (name, "Xsyscall") == 0)
|| (startswith (name, "Xintr"))));
}
static const struct frame_unwind amd64obsd_trapframe_unwind = {
/* FIXME: kettenis/20051219: This really is more like an interrupt
frame, but SIGTRAMP_FRAME would print <signal handler called>,
which really is not what we want here. */
NORMAL_FRAME,
default_frame_unwind_stop_reason,
amd64obsd_trapframe_this_id,
amd64obsd_trapframe_prev_register,
NULL,
amd64obsd_trapframe_sniffer
};
static void
amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
amd64_init_abi (info, gdbarch,
amd64_target_description (X86_XSTATE_SSE_MASK));
obsd_init_abi (info, gdbarch);
/* Initialize general-purpose register set details. */
tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
tdep->sizeof_gregset = 24 * 8;
tdep->jb_pc_offset = 7 * 8;
tdep->sigtramp_p = amd64obsd_sigtramp_p;
tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
/* OpenBSD provides a user-level threads implementation. */
bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
/* OpenBSD uses SVR4-style shared libraries. */
set_solib_svr4_fetch_link_map_offsets
(gdbarch, svr4_lp64_fetch_link_map_offsets);
/* Unwind kernel trap frames correctly. */
frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
}
void
_initialize_amd64obsd_tdep (void)
{
/* The OpenBSD/amd64 native dependent code makes this assumption. */
gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
GDB_OSABI_OPENBSD, amd64obsd_init_abi);
}
|