gdbserver/linux-nios2-low.cc

   1 /* GNU/Linux/Nios II specific low level interface, for the remote server for
   2    GDB.
   3    Copyright (C) 2008-2020 Free Software Foundation, Inc.
   4
   5    Contributed by Mentor Graphics, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "server.h"
  23 #include "linux-low.h"
  24 #include "elf/common.h"
  25 #include "nat/gdb_ptrace.h"
  26 #include <endian.h>
  27 #include "gdb_proc_service.h"
  28 #include <asm/ptrace.h>
  29
  30 #ifndef PTRACE_GET_THREAD_AREA
  31 #define PTRACE_GET_THREAD_AREA 25
  32 #endif
  33
  34 /* Linux target op definitions for the NIOS II architecture.  */
  35
  36 class nios2_target : public linux_process_target
  37 {
  38 public:
  39
  40 };
  41
  42 /* The singleton target ops object.  */
  43
  44 static nios2_target the_nios2_target;
  45
  46 /* The following definition must agree with the number of registers
  47    defined in "struct user_regs" in GLIBC
  48    (sysdeps/unix/sysv/linux/nios2/sys/user.h), and also with
  49    NIOS2_NUM_REGS in GDB proper.  */
  50
  51 #define nios2_num_regs 49
  52
  53 /* Defined in auto-generated file nios2-linux.c.  */
  54
  55 void init_registers_nios2_linux (void);
  56 extern const struct target_desc *tdesc_nios2_linux;
  57
  58 /* This union is used to convert between int and byte buffer
  59    representations of register contents.  */
  60
  61 union nios2_register
  62 {
  63   unsigned char buf[4];
  64   int reg32;
  65 };
  66
  67 /* Return the ptrace ``address'' of register REGNO. */
  68
  69 static int nios2_regmap[] = {
  70   -1,  1,  2,  3,  4,  5,  6,  7,
  71   8,  9,  10, 11, 12, 13, 14, 15,
  72   16, 17, 18, 19, 20, 21, 22, 23,
  73   24, 25, 26, 27, 28, 29, 30, 31,
  74   32, 33, 34, 35, 36, 37, 38, 39,
  75   40, 41, 42, 43, 44, 45, 46, 47,
  76   48,
  77   0
  78 };
  79
  80 /* Implement the arch_setup linux_target_ops method.  */
  81
  82 static void
  83 nios2_arch_setup (void)
  84 {
  85   current_process ()->tdesc = tdesc_nios2_linux;
  86 }
  87
  88 /* Implement the cannot_fetch_register linux_target_ops method.  */
  89
  90 static int
  91 nios2_cannot_fetch_register (int regno)
  92 {
  93   if (nios2_regmap[regno] == -1)
  94     return 1;
  95
  96   return 0;
  97 }
  98
  99 /* Implement the cannot_store_register linux_target_ops method.  */
 100
 101 static int
 102 nios2_cannot_store_register (int regno)
 103 {
 104   if (nios2_regmap[regno] == -1)
 105     return 1;
 106
 107   return 0;
 108 }
 109
 110 /* Breakpoint support.  Also see comments on nios2_breakpoint_from_pc
 111    in nios2-tdep.c.  */
 112
 113 #if defined(__nios2_arch__) && __nios2_arch__ == 2
 114 #define NIOS2_BREAKPOINT 0xb7fd0020
 115 #define CDX_BREAKPOINT 0xd7c9
 116 #else
 117 #define NIOS2_BREAKPOINT 0x003b6ffa
 118 #endif
 119
 120 /* We only register the 4-byte breakpoint, even on R2 targets which also
 121    support 2-byte breakpoints.  Since there is no supports_z_point_type
 122    function provided, gdbserver never inserts software breakpoints itself
 123    and instead relies on GDB to insert the breakpoint of the correct length
 124    via a memory write.  */
 125 static const unsigned int nios2_breakpoint = NIOS2_BREAKPOINT;
 126 #define nios2_breakpoint_len 4
 127
 128 /* Implementation of linux_target_ops method "sw_breakpoint_from_kind".  */
 129
 130 static const gdb_byte *
 131 nios2_sw_breakpoint_from_kind (int kind, int *size)
 132 {
 133   *size = nios2_breakpoint_len;
 134   return (const gdb_byte *) &nios2_breakpoint;
 135 }
 136
 137 /* Implement the breakpoint_at linux_target_ops method.  */
 138
 139 static int
 140 nios2_breakpoint_at (CORE_ADDR where)
 141 {
 142   unsigned int insn;
 143
 144   /* For R2, first check for the 2-byte CDX trap.n breakpoint encoding.  */
 145 #if defined(__nios2_arch__) && __nios2_arch__ == 2
 146   the_target->read_memory (where, (unsigned char *) &insn, 2);
 147   if (insn == CDX_BREAKPOINT)
 148     return 1;
 149 #endif
 150
 151   the_target->read_memory (where, (unsigned char *) &insn, 4);
 152   if (insn == nios2_breakpoint)
 153     return 1;
 154   return 0;
 155 }
 156
 157 /* Fetch the thread-local storage pointer for libthread_db.  */
 158
 159 ps_err_e
 160 ps_get_thread_area (struct ps_prochandle *ph,
 161                     lwpid_t lwpid, int idx, void **base)
 162 {
 163   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
 164     return PS_ERR;
 165
 166   /* IDX is the bias from the thread pointer to the beginning of the
 167      thread descriptor.  It has to be subtracted due to implementation
 168      quirks in libthread_db.  */
 169   *base = (void *) ((char *) *base - idx);
 170
 171   return PS_OK;
 172 }
 173
 174 /* Helper functions to collect/supply a single register REGNO.  */
 175
 176 static void
 177 nios2_collect_register (struct regcache *regcache, int regno,
 178                         union nios2_register *reg)
 179 {
 180   union nios2_register tmp_reg;
 181
 182   collect_register (regcache, regno, &tmp_reg.reg32);
 183   reg->reg32 = tmp_reg.reg32;
 184 }
 185
 186 static void
 187 nios2_supply_register (struct regcache *regcache, int regno,
 188                        const union nios2_register *reg)
 189 {
 190   supply_register (regcache, regno, reg->buf);
 191 }
 192
 193 /* We have only a single register set on Nios II.  */
 194
 195 static void
 196 nios2_fill_gregset (struct regcache *regcache, void *buf)
 197 {
 198   union nios2_register *regset = (union nios2_register *) buf;
 199   int i;
 200
 201   for (i = 1; i < nios2_num_regs; i++)
 202     nios2_collect_register (regcache, i, regset + i);
 203 }
 204
 205 static void
 206 nios2_store_gregset (struct regcache *regcache, const void *buf)
 207 {
 208   const union nios2_register *regset = (union nios2_register *) buf;
 209   int i;
 210
 211   for (i = 0; i < nios2_num_regs; i++)
 212     nios2_supply_register (regcache, i, regset + i);
 213 }
 214
 215 static struct regset_info nios2_regsets[] =
 216 {
 217   { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,
 218     nios2_num_regs * 4, GENERAL_REGS,
 219     nios2_fill_gregset, nios2_store_gregset },
 220   NULL_REGSET
 221 };
 222
 223 static struct regsets_info nios2_regsets_info =
 224   {
 225     nios2_regsets, /* regsets */
 226     0, /* num_regsets */
 227     NULL, /* disabled_regsets */
 228   };
 229
 230 static struct usrregs_info nios2_usrregs_info =
 231   {
 232     nios2_num_regs,
 233     nios2_regmap,
 234   };
 235
 236 static struct regs_info regs_info =
 237   {
 238     NULL, /* regset_bitmap */
 239     &nios2_usrregs_info,
 240     &nios2_regsets_info
 241   };
 242
 243 static const struct regs_info *
 244 nios2_regs_info (void)
 245 {
 246   return &regs_info;
 247 }
 248
 249 struct linux_target_ops the_low_target =
 250 {
 251   nios2_arch_setup,
 252   nios2_regs_info,
 253   nios2_cannot_fetch_register,
 254   nios2_cannot_store_register,
 255   NULL,
 256   linux_get_pc_32bit,
 257   linux_set_pc_32bit,
 258   NULL, /* breakpoint_kind_from_pc */
 259   nios2_sw_breakpoint_from_kind,
 260   NULL, /* get_next_pcs */
 261   0,
 262   nios2_breakpoint_at,
 263 };
 264
 265 /* The linux target ops object.  */
 266
 267 linux_process_target *the_linux_target = &the_nios2_target;
 268
 269 void
 270 initialize_low_arch (void)
 271 {
 272   init_registers_nios2_linux ();
 273
 274   initialize_regsets_info (&nios2_regsets_info);
 275 }