gdb/amd64-ravenscar-thread.c

   1 /* Ravenscar x86-64 target support.
   2
   3    Copyright (C) 2020-2021 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 "gdbcore.h"
  23 #include "regcache.h"
  24 #include "amd64-tdep.h"
  25 #include "inferior.h"
  26 #include "ravenscar-thread.h"
  27 #include "amd64-ravenscar-thread.h"
  28
  29 struct amd64_ravenscar_ops : public ravenscar_arch_ops
  30 {
  31   void fetch_registers (struct regcache *regcache, int regnum) override;
  32   void store_registers (struct regcache *regcache, int regnum) override;
  33
  34 private:
  35
  36   /* Return the offset of the register in the context buffer.  */
  37   int register_offset (struct gdbarch *arch, int regnum);
  38 };
  39
  40 /* x86-64 Ravenscar stores registers as:
  41
  42    type Context_Buffer is record
  43       RIP    : System.Address;
  44       RFLAGS : EFLAGS;
  45       RSP    : System.Address;
  46
  47       RBX    : System.Address;
  48       RBP    : System.Address;
  49       R12    : System.Address;
  50       R13    : System.Address;
  51       R14    : System.Address;
  52       R15    : System.Address;
  53    end record;
  54 */
  55 static const int register_layout[] =
  56 {
  57   AMD64_RIP_REGNUM,
  58   AMD64_EFLAGS_REGNUM,
  59   AMD64_RSP_REGNUM,
  60   AMD64_RBX_REGNUM,
  61   AMD64_RBP_REGNUM,
  62   AMD64_R12_REGNUM,
  63   AMD64_R13_REGNUM,
  64   AMD64_R14_REGNUM,
  65   AMD64_R15_REGNUM,
  66 };
  67
  68 int
  69 amd64_ravenscar_ops::register_offset (struct gdbarch *arch, int regnum)
  70 {
  71   for (int i = 0; i < ARRAY_SIZE (register_layout); ++i)
  72     if (register_layout[i] == regnum)
  73       return i * 8;
  74   /* Not saved.  */
  75   return -1;
  76 }
  77
  78 /* Supply register REGNUM, which has been saved at REGISTER_ADDR, to
  79    the regcache.  */
  80
  81 static void
  82 supply_register_at_address (struct regcache *regcache, int regnum,
  83                             CORE_ADDR register_addr)
  84 {
  85   struct gdbarch *gdbarch = regcache->arch ();
  86   int buf_size = register_size (gdbarch, regnum);
  87   gdb_byte *buf;
  88
  89   buf = (gdb_byte *) alloca (buf_size);
  90   read_memory (register_addr, buf, buf_size);
  91   regcache->raw_supply (regnum, buf);
  92 }
  93
  94 void
  95 amd64_ravenscar_ops::fetch_registers (struct regcache *regcache, int regnum)
  96 {
  97   struct gdbarch *gdbarch = regcache->arch ();
  98   const int num_regs = gdbarch_num_regs (gdbarch);
  99   int current_regnum;
 100   CORE_ADDR current_address;
 101   CORE_ADDR thread_descriptor_address;
 102
 103   /* The tid is the thread_id field, which is a pointer to the thread.  */
 104   thread_descriptor_address = (CORE_ADDR) inferior_ptid.tid ();
 105
 106   /* Read registers.  */
 107   for (current_regnum = 0; current_regnum < num_regs; current_regnum++)
 108     {
 109       int offset = register_offset (gdbarch, current_regnum);
 110
 111       if (offset != -1)
 112         {
 113           current_address = thread_descriptor_address + offset;
 114           supply_register_at_address (regcache, current_regnum,
 115                                       current_address);
 116         }
 117     }
 118 }
 119
 120 void
 121 amd64_ravenscar_ops::store_registers (struct regcache *regcache, int regnum)
 122 {
 123   struct gdbarch *gdbarch = regcache->arch ();
 124   int buf_size = register_size (gdbarch, regnum);
 125   gdb_byte buf[buf_size];
 126   CORE_ADDR register_address;
 127
 128   int offset = register_offset (gdbarch, regnum);
 129   if (offset != -1)
 130     {
 131       register_address = inferior_ptid.tid () + offset;
 132
 133       regcache->raw_collect (regnum, buf);
 134       write_memory (register_address,
 135                     buf,
 136                     buf_size);
 137     }
 138 }
 139
 140 /* The ravenscar_arch_ops vector for AMD64 targets.  */
 141
 142 static struct amd64_ravenscar_ops amd64_ravenscar_ops;
 143
 144 /* Register amd64_ravenscar_ops in GDBARCH.  */
 145
 146 void
 147 register_amd64_ravenscar_ops (struct gdbarch *gdbarch)
 148 {
 149   set_gdbarch_ravenscar_ops (gdbarch, &amd64_ravenscar_ops);
 150 }