gdb/amd64-nat.c

   1 /* Native-dependent code for 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 "gdbarch.h"
  22 #include "regcache.h"
  23
  24 #include "i386-tdep.h"
  25 #include "amd64-tdep.h"
  26 #include "amd64-nat.h"
  27
  28 /* The following bits of code help with implementing debugging 32-bit
  29    code natively on AMD64.  The idea is to define two mappings between
  30    the register number as used by GDB and the register set used by the
  31    host to represent the general-purpose registers; one for 32-bit
  32    code and one for 64-bit code.  The mappings are specified by the
  33    following variables and consist of an array of offsets within the
  34    register set indexed by register number, and the number of
  35    registers supported by the mapping.  We don't need mappings for the
  36    floating-point and SSE registers, since the difference between
  37    64-bit and 32-bit variants are negligible.  The difference in the
  38    number of SSE registers is already handled by the target code.  */
  39
  40 /* General-purpose register mapping for native 32-bit code.  */
  41 int *amd64_native_gregset32_reg_offset;
  42 int amd64_native_gregset32_num_regs = I386_NUM_GREGS;
  43
  44 /* General-purpose register mapping for native 64-bit code.  */
  45 int *amd64_native_gregset64_reg_offset;
  46 int amd64_native_gregset64_num_regs = AMD64_NUM_GREGS;
  47
  48 /* Return the offset of REGNUM within the appropriate native
  49    general-purpose register set.  */
  50
  51 static int
  52 amd64_native_gregset_reg_offset (struct gdbarch *gdbarch, int regnum)
  53 {
  54   int *reg_offset = amd64_native_gregset64_reg_offset;
  55   int num_regs = amd64_native_gregset64_num_regs;
  56
  57   gdb_assert (regnum >= 0);
  58
  59   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
  60     {
  61       reg_offset = amd64_native_gregset32_reg_offset;
  62       num_regs = amd64_native_gregset32_num_regs;
  63     }
  64
  65   if (num_regs > gdbarch_num_regs (gdbarch))
  66     num_regs = gdbarch_num_regs (gdbarch);
  67
  68   if (regnum >= num_regs)
  69     return -1;
  70
  71   /* Kernels that predate Linux 2.6.25 don't provide access to
  72      these segment registers in user_regs_struct.   */
  73 #ifndef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE
  74   if (regnum == AMD64_FSBASE_REGNUM || regnum == AMD64_GSBASE_REGNUM)
  75     return -1;
  76 #endif
  77
  78   return reg_offset[regnum];
  79 }
  80
  81 /* Return whether the native general-purpose register set supplies
  82    register REGNUM.  */
  83
  84 int
  85 amd64_native_gregset_supplies_p (struct gdbarch *gdbarch, int regnum)
  86 {
  87   return (amd64_native_gregset_reg_offset (gdbarch, regnum) != -1);
  88 }
  89
  90
  91 /* Supply register REGNUM, whose contents are stored in GREGS, to
  92    REGCACHE.  If REGNUM is -1, supply all appropriate registers.  */
  93
  94 void
  95 amd64_supply_native_gregset (struct regcache *regcache,
  96                              const void *gregs, int regnum)
  97 {
  98   const char *regs = (const char *) gregs;
  99   struct gdbarch *gdbarch = regcache->arch ();
 100   int num_regs = amd64_native_gregset64_num_regs;
 101   int i;
 102
 103   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
 104     num_regs = amd64_native_gregset32_num_regs;
 105
 106   if (num_regs > gdbarch_num_regs (gdbarch))
 107     num_regs = gdbarch_num_regs (gdbarch);
 108
 109   for (i = 0; i < num_regs; i++)
 110     {
 111       if (regnum == -1 || regnum == i)
 112         {
 113           int offset = amd64_native_gregset_reg_offset (gdbarch, i);
 114
 115           if (offset != -1)
 116             regcache->raw_supply (i, regs + offset);
 117         }
 118     }
 119 }
 120
 121 /* Collect register REGNUM from REGCACHE and store its contents in
 122    GREGS.  If REGNUM is -1, collect and store all appropriate
 123    registers.  */
 124
 125 void
 126 amd64_collect_native_gregset (const struct regcache *regcache,
 127                               void *gregs, int regnum)
 128 {
 129   char *regs = (char *) gregs;
 130   struct gdbarch *gdbarch = regcache->arch ();
 131   int num_regs = amd64_native_gregset64_num_regs;
 132   int i;
 133
 134   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
 135     {
 136       num_regs = amd64_native_gregset32_num_regs;
 137
 138       /* Make sure %eax, %ebx, %ecx, %edx, %esi, %edi, %ebp, %esp and
 139          %eip get zero-extended to 64 bits.  */
 140       for (i = 0; i <= I386_EIP_REGNUM; i++)
 141         {
 142           if (regnum == -1 || regnum == i)
 143             memset (regs + amd64_native_gregset_reg_offset (gdbarch, i), 0, 8);
 144         }
 145       /* Ditto for %cs, %ss, %ds, %es, %fs, and %gs.  */
 146       for (i = I386_CS_REGNUM; i <= I386_GS_REGNUM; i++)
 147         {
 148           if (regnum == -1 || regnum == i)
 149             memset (regs + amd64_native_gregset_reg_offset (gdbarch, i), 0, 8);
 150         }
 151     }
 152
 153   if (num_regs > gdbarch_num_regs (gdbarch))
 154     num_regs = gdbarch_num_regs (gdbarch);
 155
 156   for (i = 0; i < num_regs; i++)
 157     {
 158       if (regnum == -1 || regnum == i)
 159         {
 160           int offset = amd64_native_gregset_reg_offset (gdbarch, i);
 161
 162           if (offset != -1)
 163             regcache->raw_collect (i, regs + offset);
 164         }
 165     }
 166 }