gdb/amd64-nat.c

   1 /* Native-dependent code for AMD64.
   2
   3    Copyright (C) 2003-2019 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
  22 /* Local non-gdb includes.  */
  23 #include "amd64-nat.h"
  24 #include "amd64-tdep.h"
  25 #include "gdbarch.h"
  26 #include "i386-tdep.h"
  27 #include "regcache.h"
  28
  29 /* The following bits of code help with implementing debugging 32-bit
  30    code natively on AMD64.  The idea is to define two mappings between
  31    the register number as used by GDB and the register set used by the
  32    host to represent the general-purpose registers; one for 32-bit
  33    code and one for 64-bit code.  The mappings are specified by the
  34    follwing variables and consist of an array of offsets within the
  35    register set indexed by register number, and the number of
  36    registers supported by the mapping.  We don't need mappings for the
  37    floating-point and SSE registers, since the difference between
  38    64-bit and 32-bit variants are negligable.  The difference in the
  39    number of SSE registers is already handled by the target code.  */
  40
  41 /* General-purpose register mapping for native 32-bit code.  */
  42 int *amd64_native_gregset32_reg_offset;
  43 int amd64_native_gregset32_num_regs = I386_NUM_GREGS;
  44
  45 /* General-purpose register mapping for native 64-bit code.  */
  46 int *amd64_native_gregset64_reg_offset;
  47 int amd64_native_gregset64_num_regs = AMD64_NUM_GREGS;
  48
  49 /* Return the offset of REGNUM within the appropriate native
  50    general-purpose register set.  */
  51
  52 static int
  53 amd64_native_gregset_reg_offset (struct gdbarch *gdbarch, int regnum)
  54 {
  55   int *reg_offset = amd64_native_gregset64_reg_offset;
  56   int num_regs = amd64_native_gregset64_num_regs;
  57
  58   gdb_assert (regnum >= 0);
  59
  60   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
  61     {
  62       reg_offset = amd64_native_gregset32_reg_offset;
  63       num_regs = amd64_native_gregset32_num_regs;
  64     }
  65
  66   if (num_regs > gdbarch_num_regs (gdbarch))
  67     num_regs = gdbarch_num_regs (gdbarch);
  68
  69   if (regnum >= num_regs)
  70     return -1;
  71
  72   /* Kernels that predate Linux 2.6.25 don't provide access to
  73      these segment registers in user_regs_struct.   */
  74 #ifndef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE
  75   if (regnum == AMD64_FSBASE_REGNUM || regnum == AMD64_GSBASE_REGNUM)
  76     return -1;
  77 #endif
  78
  79   return reg_offset[regnum];
  80 }
  81
  82 /* Return whether the native general-purpose register set supplies
  83    register REGNUM.  */
  84
  85 int
  86 amd64_native_gregset_supplies_p (struct gdbarch *gdbarch, int regnum)
  87 {
  88   return (amd64_native_gregset_reg_offset (gdbarch, regnum) != -1);
  89 }
  90
  91
  92 /* Supply register REGNUM, whose contents are stored in GREGS, to
  93    REGCACHE.  If REGNUM is -1, supply all appropriate registers.  */
  94
  95 void
  96 amd64_supply_native_gregset (struct regcache *regcache,
  97                              const void *gregs, int regnum)
  98 {
  99   const char *regs = (const char *) gregs;
 100   struct gdbarch *gdbarch = regcache->arch ();
 101   int num_regs = amd64_native_gregset64_num_regs;
 102   int i;
 103
 104   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
 105     num_regs = amd64_native_gregset32_num_regs;
 106
 107   if (num_regs > gdbarch_num_regs (gdbarch))
 108     num_regs = gdbarch_num_regs (gdbarch);
 109
 110   for (i = 0; i < num_regs; i++)
 111     {
 112       if (regnum == -1 || regnum == i)
 113         {
 114           int offset = amd64_native_gregset_reg_offset (gdbarch, i);
 115
 116           if (offset != -1)
 117             regcache->raw_supply (i, regs + offset);
 118         }
 119     }
 120 }
 121
 122 /* Collect register REGNUM from REGCACHE and store its contents in
 123    GREGS.  If REGNUM is -1, collect and store all appropriate
 124    registers.  */
 125
 126 void
 127 amd64_collect_native_gregset (const struct regcache *regcache,
 128                               void *gregs, int regnum)
 129 {
 130   char *regs = (char *) gregs;
 131   struct gdbarch *gdbarch = regcache->arch ();
 132   int num_regs = amd64_native_gregset64_num_regs;
 133   int i;
 134
 135   if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
 136     {
 137       num_regs = amd64_native_gregset32_num_regs;
 138
 139       /* Make sure %eax, %ebx, %ecx, %edx, %esi, %edi, %ebp, %esp and
 140          %eip get zero-extended to 64 bits.  */
 141       for (i = 0; i <= I386_EIP_REGNUM; i++)
 142         {
 143           if (regnum == -1 || regnum == i)
 144             memset (regs + amd64_native_gregset_reg_offset (gdbarch, i), 0, 8);
 145         }
 146       /* Ditto for %cs, %ss, %ds, %es, %fs, and %gs.  */
 147       for (i = I386_CS_REGNUM; i <= I386_GS_REGNUM; i++)
 148         {
 149           if (regnum == -1 || regnum == i)
 150             memset (regs + amd64_native_gregset_reg_offset (gdbarch, i), 0, 8);
 151         }
 152     }
 153
 154   if (num_regs > gdbarch_num_regs (gdbarch))
 155     num_regs = gdbarch_num_regs (gdbarch);
 156
 157   for (i = 0; i < num_regs; i++)
 158     {
 159       if (regnum == -1 || regnum == i)
 160         {
 161           int offset = amd64_native_gregset_reg_offset (gdbarch, i);
 162
 163           if (offset != -1)
 164             regcache->raw_collect (i, regs + offset);
 165         }
 166     }
 167 }