gdb/linux-nat-trad.c

   1 /* Generic GNU/Linux target using traditional ptrace register access.
   2
   3    Copyright (C) 1988-2018 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 /* Pointer to a function that returns the offset within the user area
  27    where a particular register is stored.  */
  28 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
  29
  30 /* Fetch register REGNUM from the inferior.  */
  31
  32 static void
  33 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
  34 {
  35   struct gdbarch *gdbarch = regcache->arch ();
  36   CORE_ADDR addr;
  37   size_t size;
  38   PTRACE_TYPE_RET *buf;
  39   pid_t pid;
  40   int i;
  41
  42   /* This isn't really an address, but ptrace thinks of it as one.  */
  43   addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
  44   if (addr == (CORE_ADDR)-1
  45       || gdbarch_cannot_fetch_register (gdbarch, regnum))
  46     {
  47       regcache_raw_supply (regcache, regnum, NULL);
  48       return;
  49     }
  50
  51   pid = get_ptrace_pid (regcache_get_ptid (regcache));
  52
  53   size = register_size (gdbarch, regnum);
  54   gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
  55   buf = (PTRACE_TYPE_RET *) alloca (size);
  56
  57   /* Read the register contents from the inferior a chunk at a time.  */
  58   for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
  59     {
  60       errno = 0;
  61       buf[i] = 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
  67       addr += sizeof (PTRACE_TYPE_RET);
  68     }
  69   regcache_raw_supply (regcache, regnum, buf);
  70 }
  71
  72 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
  73    for all registers.  */
  74
  75 static void
  76 inf_ptrace_fetch_registers (struct target_ops *ops,
  77                             struct regcache *regcache, int regnum)
  78 {
  79   if (regnum == -1)
  80     for (regnum = 0;
  81          regnum < gdbarch_num_regs (regcache->arch ());
  82          regnum++)
  83       inf_ptrace_fetch_register (regcache, regnum);
  84   else
  85     inf_ptrace_fetch_register (regcache, regnum);
  86 }
  87
  88 /* Store register REGNUM into the inferior.  */
  89
  90 static void
  91 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
  92 {
  93   struct gdbarch *gdbarch = regcache->arch ();
  94   CORE_ADDR addr;
  95   size_t size;
  96   PTRACE_TYPE_RET *buf;
  97   pid_t pid;
  98   int i;
  99
 100   /* This isn't really an address, but ptrace thinks of it as one.  */
 101   addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
 102   if (addr == (CORE_ADDR)-1
 103       || gdbarch_cannot_store_register (gdbarch, regnum))
 104     return;
 105
 106   pid = get_ptrace_pid (regcache_get_ptid (regcache));
 107
 108   size = register_size (gdbarch, regnum);
 109   gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
 110   buf = (PTRACE_TYPE_RET *) alloca (size);
 111
 112   /* Write the register contents into the inferior a chunk at a time.  */
 113   regcache_raw_collect (regcache, regnum, buf);
 114   for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
 115     {
 116       errno = 0;
 117       ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
 118       if (errno != 0)
 119         error (_("Couldn't write register %s (#%d): %s."),
 120                gdbarch_register_name (gdbarch, regnum),
 121                regnum, safe_strerror (errno));
 122
 123       addr += sizeof (PTRACE_TYPE_RET);
 124     }
 125 }
 126
 127 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 128    this for all registers.  */
 129
 130 static void
 131 inf_ptrace_store_registers (struct target_ops *ops,
 132                             struct regcache *regcache, int regnum)
 133 {
 134   if (regnum == -1)
 135     for (regnum = 0;
 136          regnum < gdbarch_num_regs (regcache->arch ());
 137          regnum++)
 138       inf_ptrace_store_register (regcache, regnum);
 139   else
 140     inf_ptrace_store_register (regcache, regnum);
 141 }
 142
 143 /* Create a "traditional" Linux/ptrace target.  REGISTER_U_OFFSET
 144    should be a function returning the offset within the user area
 145    where a particular register is stored.  */
 146
 147 struct target_ops *
 148 linux_trad_target (CORE_ADDR (*register_u_offset)(struct gdbarch *, int, int))
 149 {
 150   struct target_ops *t = inf_ptrace_target();
 151
 152   gdb_assert (register_u_offset);
 153   inf_ptrace_register_u_offset = register_u_offset;
 154   t->to_fetch_registers = inf_ptrace_fetch_registers;
 155   t->to_store_registers = inf_ptrace_store_registers;
 156
 157   linux_target_install_ops (t);
 158
 159   return t;
 160 }