gdb/gdbserver/linux-nios2-low.c

   1 /* GNU/Linux/Nios II specific low level interface, for the remote server for
   2    GDB.
   3    Copyright (C) 2008-2015 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 /* The following definition must agree with the number of registers
  35    defined in "struct user_regs" in GLIBC
  36    (sysdeps/unix/sysv/linux/nios2/sys/user.h), and also with
  37    NIOS2_NUM_REGS in GDB proper.  */
  38
  39 #define nios2_num_regs 49
  40
  41 /* Defined in auto-generated file nios2-linux.c.  */
  42
  43 void init_registers_nios2_linux (void);
  44 extern const struct target_desc *tdesc_nios2_linux;
  45
  46 /* This union is used to convert between int and byte buffer
  47    representations of register contents.  */
  48
  49 union nios2_register
  50 {
  51   unsigned char buf[4];
  52   int reg32;
  53 };
  54
  55 /* Return the ptrace ``address'' of register REGNO. */
  56
  57 static int nios2_regmap[] = {
  58   -1,  1,  2,  3,  4,  5,  6,  7,
  59   8,  9,  10, 11, 12, 13, 14, 15,
  60   16, 17, 18, 19, 20, 21, 22, 23,
  61   24, 25, 26, 27, 28, 29, 30, 31,
  62   32, 33, 34, 35, 36, 37, 38, 39,
  63   40, 41, 42, 43, 44, 45, 46, 47,
  64   48,
  65   0
  66 };
  67
  68 /* Implement the arch_setup linux_target_ops method.  */
  69
  70 static void
  71 nios2_arch_setup (void)
  72 {
  73   current_process ()->tdesc = tdesc_nios2_linux;
  74 }
  75
  76 /* Implement the cannot_fetch_register linux_target_ops method.  */
  77
  78 static int
  79 nios2_cannot_fetch_register (int regno)
  80 {
  81   if (nios2_regmap[regno] == -1)
  82     return 1;
  83
  84   return 0;
  85 }
  86
  87 /* Implement the cannot_store_register linux_target_ops method.  */
  88
  89 static int
  90 nios2_cannot_store_register (int regno)
  91 {
  92   if (nios2_regmap[regno] == -1)
  93     return 1;
  94
  95   return 0;
  96 }
  97
  98 /* Implement the get_pc linux_target_ops method.  */
  99
 100 static CORE_ADDR
 101 nios2_get_pc (struct regcache *regcache)
 102 {
 103   union nios2_register pc;
 104
 105   collect_register_by_name (regcache, "pc", pc.buf);
 106   return pc.reg32;
 107 }
 108
 109 /* Implement the set_pc linux_target_ops method.  */
 110
 111 static void
 112 nios2_set_pc (struct regcache *regcache, CORE_ADDR pc)
 113 {
 114   union nios2_register newpc;
 115
 116   newpc.reg32 = pc;
 117   supply_register_by_name (regcache, "pc", newpc.buf);
 118 }
 119
 120 /* Breakpoint support.  Also see comments on nios2_breakpoint_from_pc
 121    in nios2-tdep.c.  */
 122
 123 #if defined(__nios2_arch__) && __nios2_arch__ == 2
 124 #define NIOS2_BREAKPOINT 0xb7fd0020
 125 #define CDX_BREAKPOINT 0xd7c9
 126 #else
 127 #define NIOS2_BREAKPOINT 0x003b6ffa
 128 #endif
 129
 130 /* We only register the 4-byte breakpoint, even on R2 targets which also
 131    support 2-byte breakpoints.  Since there is no supports_z_point_type
 132    function provided, gdbserver never inserts software breakpoints itself
 133    and instead relies on GDB to insert the breakpoint of the correct length
 134    via a memory write.  */
 135 static const unsigned int nios2_breakpoint = NIOS2_BREAKPOINT;
 136 #define nios2_breakpoint_len 4
 137
 138 /* Implementation of linux_target_ops method "sw_breakpoint_from_kind".  */
 139
 140 static const gdb_byte *
 141 nios2_sw_breakpoint_from_kind (int kind, int *size)
 142 {
 143   *size = nios2_breakpoint_len;
 144   return (const gdb_byte *) &nios2_breakpoint;
 145 }
 146
 147 /* Implement the breakpoint_at linux_target_ops method.  */
 148
 149 static int
 150 nios2_breakpoint_at (CORE_ADDR where)
 151 {
 152   unsigned int insn;
 153
 154   /* For R2, first check for the 2-byte CDX trap.n breakpoint encoding.  */
 155 #if defined(__nios2_arch__) && __nios2_arch__ == 2
 156   (*the_target->read_memory) (where, (unsigned char *) &insn, 2);
 157   if (insn == CDX_BREAKPOINT)
 158     return 1;
 159 #endif
 160
 161   (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
 162   if (insn == nios2_breakpoint)
 163     return 1;
 164   return 0;
 165 }
 166
 167 /* Fetch the thread-local storage pointer for libthread_db.  */
 168
 169 ps_err_e
 170 ps_get_thread_area (const struct ps_prochandle *ph,
 171                     lwpid_t lwpid, int idx, void **base)
 172 {
 173   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
 174     return PS_ERR;
 175
 176   /* IDX is the bias from the thread pointer to the beginning of the
 177      thread descriptor.  It has to be subtracted due to implementation
 178      quirks in libthread_db.  */
 179   *base = (void *) ((char *) *base - idx);
 180
 181   return PS_OK;
 182 }
 183
 184 /* Helper functions to collect/supply a single register REGNO.  */
 185
 186 static void
 187 nios2_collect_register (struct regcache *regcache, int regno,
 188                         union nios2_register *reg)
 189 {
 190   union nios2_register tmp_reg;
 191
 192   collect_register (regcache, regno, &tmp_reg.reg32);
 193   reg->reg32 = tmp_reg.reg32;
 194 }
 195
 196 static void
 197 nios2_supply_register (struct regcache *regcache, int regno,
 198                        const union nios2_register *reg)
 199 {
 200   supply_register (regcache, regno, reg->buf);
 201 }
 202
 203 /* We have only a single register set on Nios II.  */
 204
 205 static void
 206 nios2_fill_gregset (struct regcache *regcache, void *buf)
 207 {
 208   union nios2_register *regset = buf;
 209   int i;
 210
 211   for (i = 1; i < nios2_num_regs; i++)
 212     nios2_collect_register (regcache, i, regset + i);
 213 }
 214
 215 static void
 216 nios2_store_gregset (struct regcache *regcache, const void *buf)
 217 {
 218   const union nios2_register *regset = buf;
 219   int i;
 220
 221   for (i = 0; i < nios2_num_regs; i++)
 222     nios2_supply_register (regcache, i, regset + i);
 223 }
 224
 225 static struct regset_info nios2_regsets[] =
 226 {
 227   { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,
 228     nios2_num_regs * 4, GENERAL_REGS,
 229     nios2_fill_gregset, nios2_store_gregset },
 230   NULL_REGSET
 231 };
 232
 233 static struct regsets_info nios2_regsets_info =
 234   {
 235     nios2_regsets, /* regsets */
 236     0, /* num_regsets */
 237     NULL, /* disabled_regsets */
 238   };
 239
 240 static struct usrregs_info nios2_usrregs_info =
 241   {
 242     nios2_num_regs,
 243     nios2_regmap,
 244   };
 245
 246 static struct regs_info regs_info =
 247   {
 248     NULL, /* regset_bitmap */
 249     &nios2_usrregs_info,
 250     &nios2_regsets_info
 251   };
 252
 253 static const struct regs_info *
 254 nios2_regs_info (void)
 255 {
 256   return &regs_info;
 257 }
 258
 259 struct linux_target_ops the_low_target =
 260 {
 261   nios2_arch_setup,
 262   nios2_regs_info,
 263   nios2_cannot_fetch_register,
 264   nios2_cannot_store_register,
 265   NULL,
 266   nios2_get_pc,
 267   nios2_set_pc,
 268   NULL, /* breakpoint_kind_from_pc */
 269   nios2_sw_breakpoint_from_kind,
 270   NULL, /* get_next_pcs */
 271   0,
 272   nios2_breakpoint_at,
 273 };
 274
 275 void
 276 initialize_low_arch (void)
 277 {
 278   init_registers_nios2_linux ();
 279
 280   initialize_regsets_info (&nios2_regsets_info);
 281 }