1/* Generic GNU/Linux target using traditional ptrace register access.
2
3   Copyright (C) 1988-2020 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 "linux-nat-trad.h"
22
23#include "nat/gdb_ptrace.h"
24#include "inf-ptrace.h"
25#include "gdbarch.h"
26
27/* Fetch register REGNUM from the inferior.  */
28
29void
30linux_nat_trad_target::fetch_register (struct regcache *regcache, int regnum)
31{
32  struct gdbarch *gdbarch = regcache->arch ();
33  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
34  CORE_ADDR addr;
35  gdb_byte *buf;
36  size_t size;
37  pid_t pid;
38  int i;
39
40  /* This isn't really an address, but ptrace thinks of it as one.  */
41  addr = register_u_offset (gdbarch, regnum, 0);
42  if (addr == (CORE_ADDR)-1
43      || gdbarch_cannot_fetch_register (gdbarch, regnum))
44    {
45      regcache->raw_supply (regnum, NULL);
46      return;
47    }
48
49  pid = get_ptrace_pid (regcache->ptid ());
50
51  size = register_size (gdbarch, regnum);
52  buf = (gdb_byte *) alloca (size);
53
54  /* Read the register contents from the inferior a chunk at a time.  */
55  for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
56    {
57      size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
58      PTRACE_TYPE_RET val;
59
60      errno = 0;
61      val = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, 0);
62      if (errno != 0)
63	error (_("Couldn't read register %s (#%d): %s."),
64	       gdbarch_register_name (gdbarch, regnum),
65	       regnum, safe_strerror (errno));
66      store_unsigned_integer (buf + i, chunk, byte_order, val);
67
68      addr += sizeof (PTRACE_TYPE_RET);
69    }
70  regcache->raw_supply (regnum, buf);
71}
72
73/* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
74   for all registers.  */
75
76void
77linux_nat_trad_target::fetch_registers (struct regcache *regcache, int regnum)
78{
79  if (regnum == -1)
80    for (regnum = 0;
81	 regnum < gdbarch_num_regs (regcache->arch ());
82	 regnum++)
83      fetch_register (regcache, regnum);
84  else
85    fetch_register (regcache, regnum);
86}
87
88/* Store register REGNUM into the inferior.  */
89
90void
91linux_nat_trad_target::store_register (const struct regcache *regcache,
92				       int regnum)
93{
94  struct gdbarch *gdbarch = regcache->arch ();
95  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
96  CORE_ADDR addr;
97  size_t size;
98  gdb_byte *buf;
99  pid_t pid;
100  int i;
101
102  /* This isn't really an address, but ptrace thinks of it as one.  */
103  addr = register_u_offset (gdbarch, regnum, 1);
104  if (addr == (CORE_ADDR)-1
105      || gdbarch_cannot_store_register (gdbarch, regnum))
106    return;
107
108  pid = get_ptrace_pid (regcache->ptid ());
109
110  size = register_size (gdbarch, regnum);
111  buf = (gdb_byte *) alloca (size);
112
113  /* Write the register contents into the inferior a chunk at a time.  */
114  regcache->raw_collect (regnum, buf);
115  for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
116    {
117      size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
118      PTRACE_TYPE_RET val;
119
120      val = extract_unsigned_integer (buf + i, chunk, byte_order);
121      errno = 0;
122      ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, val);
123      if (errno != 0)
124	error (_("Couldn't write register %s (#%d): %s."),
125	       gdbarch_register_name (gdbarch, regnum),
126	       regnum, safe_strerror (errno));
127
128      addr += sizeof (PTRACE_TYPE_RET);
129    }
130}
131
132/* Store register REGNUM back into the inferior.  If REGNUM is -1, do
133   this for all registers.  */
134
135void
136linux_nat_trad_target::store_registers (struct regcache *regcache, int regnum)
137{
138  if (regnum == -1)
139    for (regnum = 0;
140	 regnum < gdbarch_num_regs (regcache->arch ());
141	 regnum++)
142      store_register (regcache, regnum);
143  else
144    store_register (regcache, regnum);
145}
146