1/* Native-dependent code for OpenBSD/amd64.
2
3   Copyright (C) 2003-2020 Free Software Foundation, Inc.
4
5   This file is part of GDB.
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
19
20#include "defs.h"
21#include "gdbcore.h"
22#include "regcache.h"
23#include "target.h"
24
25#include "amd64-tdep.h"
26#include "amd64-bsd-nat.h"
27#include "amd64-nat.h"
28#include "obsd-nat.h"
29
30/* Mapping between the general-purpose registers in OpenBSD/amd64
31   `struct reg' format and GDB's register cache layout for
32   OpenBSD/i386.
33
34   Note that most (if not all) OpenBSD/amd64 registers are 64-bit,
35   while the OpenBSD/i386 registers are all 32-bit, but since we're
36   little-endian we get away with that.  */
37
38/* From <machine/reg.h>.  */
39static int amd64obsd32_r_reg_offset[] =
40{
41  14 * 8,			/* %eax */
42  3 * 8,			/* %ecx */
43  2 * 8,			/* %edx */
44  13 * 8,			/* %ebx */
45  15 * 8,			/* %esp */
46  12 * 8,			/* %ebp */
47  1 * 8,			/* %esi */
48  0 * 8,			/* %edi */
49  16 * 8,			/* %eip */
50  17 * 8,			/* %eflags */
51  18 * 8,			/* %cs */
52  19 * 8,			/* %ss */
53  20 * 8,			/* %ds */
54  21 * 8,			/* %es */
55  22 * 8,			/* %fs */
56  23 * 8			/* %gs */
57};
58
59
60/* Support for debugging kernel virtual memory images.  */
61
62#include <sys/types.h>
63#include <machine/frame.h>
64#include <machine/pcb.h>
65
66#include "bsd-kvm.h"
67
68static int
69amd64obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
70{
71  struct switchframe sf;
72  int regnum;
73
74  /* The following is true for OpenBSD 3.5:
75
76     The pcb contains the stack pointer at the point of the context
77     switch in cpu_switch().  At that point we have a stack frame as
78     described by `struct switchframe', which for OpenBSD 3.5 has the
79     following layout:
80
81     interrupt level
82     %r15
83     %r14
84     %r13
85     %r12
86     %rbp
87     %rbx
88     return address
89
90     Together with %rsp in the pcb, this accounts for all callee-saved
91     registers specified by the psABI.  From this information we
92     reconstruct the register state as it would look when we just
93     returned from cpu_switch().
94
95     For core dumps the pcb is saved by savectx().  In that case the
96     stack frame only contains the return address, and there is no way
97     to recover the other registers.  */
98
99  /* The stack pointer shouldn't be zero.  */
100  if (pcb->pcb_rsp == 0)
101    return 0;
102
103  /* Read the stack frame, and check its validity.  */
104  read_memory (pcb->pcb_rsp, (gdb_byte *) &sf, sizeof sf);
105  if (sf.sf_rbp == pcb->pcb_rbp)
106    {
107      /* Yes, we have a frame that matches cpu_switch().  */
108      pcb->pcb_rsp += sizeof (struct switchframe);
109      regcache->raw_supply (12, &sf.sf_r12);
110      regcache->raw_supply (13, &sf.sf_r13);
111      regcache->raw_supply (14, &sf.sf_r14);
112      regcache->raw_supply (15, &sf.sf_r15);
113      regcache->raw_supply (AMD64_RBX_REGNUM, &sf.sf_rbx);
114      regcache->raw_supply (AMD64_RIP_REGNUM, &sf.sf_rip);
115    }
116  else
117    {
118      /* No, the pcb must have been last updated by savectx().  */
119      pcb->pcb_rsp += 8;
120      regcache->raw_supply (AMD64_RIP_REGNUM, &sf);
121    }
122
123  regcache->raw_supply (AMD64_RSP_REGNUM, &pcb->pcb_rsp);
124  regcache->raw_supply (AMD64_RBP_REGNUM, &pcb->pcb_rbp);
125
126  return 1;
127}
128
129static amd64_bsd_nat_target<obsd_nat_target> the_amd64_obsd_nat_target;
130
131void _initialize_amd64obsd_nat ();
132void
133_initialize_amd64obsd_nat ()
134{
135  amd64_native_gregset32_reg_offset = amd64obsd32_r_reg_offset;
136  amd64_native_gregset32_num_regs = ARRAY_SIZE (amd64obsd32_r_reg_offset);
137  amd64_native_gregset64_reg_offset = amd64obsd_r_reg_offset;
138
139  add_inf_child_target (&the_amd64_obsd_nat_target);
140
141  /* Support debugging kernel virtual memory images.  */
142  bsd_kvm_add_target (amd64obsd_supply_pcb);
143}
144