summaryrefslogtreecommitdiff
path: root/gdb/amd64obsd-nat.c
blob: 265aca9ec56c322553495faea04d623bfbda0682 (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
/* Native-dependent code for OpenBSD/amd64.

   Copyright (C) 2003, 2004 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 2 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, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.  */

#include "defs.h"
#include "gdbcore.h"
#include "regcache.h"
#include "target.h"

#include "gdb_assert.h"

#include "amd64-tdep.h"
#include "amd64-nat.h"

/* Mapping between the general-purpose registers in OpenBSD/amd64
   `struct reg' format and GDB's register cache layout for
   OpenBSD/i386.

   Note that most (if not all) OpenBSD/amd64 registers are 64-bit,
   while the OpenBSD/i386 registers are all 32-bit, but since we're
   little-endian we get away with that.  */

/* From <machine/reg.h>.  */
static int amd64obsd32_r_reg_offset[] =
{
  14 * 8,			/* %eax */
  3 * 8,			/* %ecx */
  2 * 8,			/* %edx */
  13 * 8,			/* %ebx */
  15 * 8,			/* %esp */
  12 * 8,			/* %ebp */
  1 * 8,			/* %esi */
  0 * 8,			/* %edi */
  16 * 8,			/* %eip */
  17 * 8,			/* %eflags */
  18 * 8,			/* %cs */
  19 * 8,			/* %ss */
  20 * 8,			/* %ds */
  21 * 8,			/* %es */
  22 * 8,			/* %fs */
  23 * 8			/* %gs */
};


/* Support for debugging kernel virtual memory images.  */

#include <sys/types.h>
#include <machine/frame.h>
#include <machine/pcb.h>

#include "bsd-kvm.h"

static int
amd64obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
{
  struct switchframe sf;
  int regnum;

  /* The following is true for OpenBSD 3.5:

     The pcb contains the stack pointer at the point of the context
     switch in cpu_switch().  At that point we have a stack frame as
     described by `struct switchframe', which for OpenBSD 3.5 has the
     following layout:

     interrupt level
     %r15
     %r14
     %r13
     %r12
     %rbp
     %rbx
     return address

     Together with %rsp in the pcb, this accounts for all callee-saved
     registers specified by the psABI.  From this information we
     reconstruct the register state as it would look when we just
     returned from cpu_switch().

     For core dumps the pcb is saved by savectx().  In that case the
     stack frame only contains the return address, and there is no way
     to recover the other registers.  */

  /* The stack pointer shouldn't be zero.  */
  if (pcb->pcb_rsp == 0)
    return 0;

  /* Read the stack frame, and check its validity.  */
  read_memory (pcb->pcb_rsp, (char *) &sf, sizeof sf);
  if (sf.sf_rbp == pcb->pcb_rbp)
    {
      /* Yes, we have a frame that matches cpu_switch().  */
      pcb->pcb_rsp += sizeof (struct switchframe);
      regcache_raw_supply (regcache, 12, &sf.sf_r12);
      regcache_raw_supply (regcache, 13, &sf.sf_r13);
      regcache_raw_supply (regcache, 14, &sf.sf_r14);
      regcache_raw_supply (regcache, 15, &sf.sf_r15);
      regcache_raw_supply (regcache, AMD64_RBX_REGNUM, &sf.sf_rbx);
      regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &sf.sf_rip);
    }
  else
    {
      /* No, the pcb must have been last updated by savectx().  */
      pcb->pcb_rsp += 8;
      regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &sf);
    }

  regcache_raw_supply (regcache, AMD64_RSP_REGNUM, &pcb->pcb_rsp);
  regcache_raw_supply (regcache, AMD64_RBP_REGNUM, &pcb->pcb_rbp);

  return 1;
}


/* Provide a prototype to silence -Wmissing-prototypes.  */
void _initialize_amd64obsd_nat (void);

void
_initialize_amd64obsd_nat (void)
{
  amd64_native_gregset32_reg_offset = amd64obsd32_r_reg_offset;
  amd64_native_gregset32_num_regs = ARRAY_SIZE (amd64obsd32_r_reg_offset);
  amd64_native_gregset64_reg_offset = amd64obsd_r_reg_offset;

  /* We've got nothing to add to the common *BSD/amd64 target.  */
  add_target (amd64bsd_target ());

  /* Support debugging kernel virtual memory images.  */
  bsd_kvm_add_target (amd64obsd_supply_pcb);
}