gdb/linux-nat-trad.c

   1 /* Generic GNU/Linux target using traditional ptrace register access.
   2
   3    Copyright (C) 1988-2019 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
  26 /* Fetch register REGNUM from the inferior.  */
  27
  28 void
  29 linux_nat_trad_target::fetch_register (struct regcache *regcache, int regnum)
  30 {
  31   struct gdbarch *gdbarch = regcache->arch ();
  32   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  33   CORE_ADDR addr;
  34   gdb_byte *buf;
  35   size_t size;
  36   pid_t pid;
  37   int i;
  38
  39   /* This isn't really an address, but ptrace thinks of it as one.  */
  40   addr = register_u_offset (gdbarch, regnum, 0);
  41   if (addr == (CORE_ADDR)-1
  42       || gdbarch_cannot_fetch_register (gdbarch, regnum))
  43     {
  44       regcache->raw_supply (regnum, NULL);
  45       return;
  46     }
  47
  48   pid = get_ptrace_pid (regcache->ptid ());
  49
  50   size = register_size (gdbarch, regnum);
  51   buf = (gdb_byte *) alloca (size);
  52
  53   /* Read the register contents from the inferior a chunk at a time.  */
  54   for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
  55     {
  56       size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
  57       PTRACE_TYPE_RET val;
  58
  59       errno = 0;
  60       val = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, 0);
  61       if (errno != 0)
  62         error (_("Couldn't read register %s (#%d): %s."),
  63                gdbarch_register_name (gdbarch, regnum),
  64                regnum, safe_strerror (errno));
  65       store_unsigned_integer (buf + i, chunk, byte_order, val);
  66
  67       addr += sizeof (PTRACE_TYPE_RET);
  68     }
  69   regcache->raw_supply (regnum, buf);
  70 }
  71
  72 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
  73    for all registers.  */
  74
  75 void
  76 linux_nat_trad_target::fetch_registers (struct regcache *regcache, int regnum)
  77 {
  78   if (regnum == -1)
  79     for (regnum = 0;
  80          regnum < gdbarch_num_regs (regcache->arch ());
  81          regnum++)
  82       fetch_register (regcache, regnum);
  83   else
  84     fetch_register (regcache, regnum);
  85 }
  86
  87 /* Store register REGNUM into the inferior.  */
  88
  89 void
  90 linux_nat_trad_target::store_register (const struct regcache *regcache,
  91                                        int regnum)
  92 {
  93   struct gdbarch *gdbarch = regcache->arch ();
  94   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  95   CORE_ADDR addr;
  96   size_t size;
  97   gdb_byte *buf;
  98   pid_t pid;
  99   int i;
 100
 101   /* This isn't really an address, but ptrace thinks of it as one.  */
 102   addr = register_u_offset (gdbarch, regnum, 1);
 103   if (addr == (CORE_ADDR)-1
 104       || gdbarch_cannot_store_register (gdbarch, regnum))
 105     return;
 106
 107   pid = get_ptrace_pid (regcache->ptid ());
 108
 109   size = register_size (gdbarch, regnum);
 110   buf = (gdb_byte *) alloca (size);
 111
 112   /* Write the register contents into the inferior a chunk at a time.  */
 113   regcache->raw_collect (regnum, buf);
 114   for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
 115     {
 116       size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
 117       PTRACE_TYPE_RET val;
 118
 119       val = extract_unsigned_integer (buf + i, chunk, byte_order);
 120       errno = 0;
 121       ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, val);
 122       if (errno != 0)
 123         error (_("Couldn't write register %s (#%d): %s."),
 124                gdbarch_register_name (gdbarch, regnum),
 125                regnum, safe_strerror (errno));
 126
 127       addr += sizeof (PTRACE_TYPE_RET);
 128     }
 129 }
 130
 131 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 132    this for all registers.  */
 133
 134 void
 135 linux_nat_trad_target::store_registers (struct regcache *regcache, int regnum)
 136 {
 137   if (regnum == -1)
 138     for (regnum = 0;
 139          regnum < gdbarch_num_regs (regcache->arch ());
 140          regnum++)
 141       store_register (regcache, regnum);
 142   else
 143     store_register (regcache, regnum);
 144 }