gdbserver/linux-nios2-low.cc

   1 /* GNU/Linux/Nios II specific low level interface, for the remote server for
   2    GDB.
   3    Copyright (C) 2008-2024 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 "linux-low.h"
  23 #include "elf/common.h"
  24 #include "nat/gdb_ptrace.h"
  25 #include <endian.h>
  26 #include "gdb_proc_service.h"
  27 #include <asm/ptrace.h>
  28
  29 #ifndef PTRACE_GET_THREAD_AREA
  30 #define PTRACE_GET_THREAD_AREA 25
  31 #endif
  32
  33 /* Linux target op definitions for the NIOS II architecture.  */
  34
  35 class nios2_target : public linux_process_target
  36 {
  37 public:
  38
  39   const regs_info *get_regs_info () override;
  40
  41   const gdb_byte *sw_breakpoint_from_kind (int kind, int *size) override;
  42
  43 protected:
  44
  45   void low_arch_setup () override;
  46
  47   bool low_cannot_fetch_register (int regno) override;
  48
  49   bool low_cannot_store_register (int regno) override;
  50
  51   bool low_supports_breakpoints () override;
  52
  53   CORE_ADDR low_get_pc (regcache *regcache) override;
  54
  55   void low_set_pc (regcache *regcache, CORE_ADDR newpc) override;
  56
  57   bool low_breakpoint_at (CORE_ADDR pc) override;
  58 };
  59
  60 /* The singleton target ops object.  */
  61
  62 static nios2_target the_nios2_target;
  63
  64 bool
  65 nios2_target::low_supports_breakpoints ()
  66 {
  67   return true;
  68 }
  69
  70 CORE_ADDR
  71 nios2_target::low_get_pc (regcache *regcache)
  72 {
  73   return linux_get_pc_32bit (regcache);
  74 }
  75
  76 void
  77 nios2_target::low_set_pc (regcache *regcache, CORE_ADDR pc)
  78 {
  79   linux_set_pc_32bit (regcache, pc);
  80 }
  81
  82 /* The following definition must agree with the number of registers
  83    defined in "struct user_regs" in GLIBC
  84    (sysdeps/unix/sysv/linux/nios2/sys/user.h), and also with
  85    NIOS2_NUM_REGS in GDB proper.  */
  86
  87 #define nios2_num_regs 49
  88
  89 /* Defined in auto-generated file nios2-linux.c.  */
  90
  91 void init_registers_nios2_linux (void);
  92 extern const struct target_desc *tdesc_nios2_linux;
  93
  94 /* This union is used to convert between int and byte buffer
  95    representations of register contents.  */
  96
  97 union nios2_register
  98 {
  99   unsigned char buf[4];
 100   int reg32;
 101 };
 102
 103 /* Return the ptrace ``address'' of register REGNO. */
 104
 105 static int nios2_regmap[] = {
 106   -1,  1,  2,  3,  4,  5,  6,  7,
 107   8,  9,  10, 11, 12, 13, 14, 15,
 108   16, 17, 18, 19, 20, 21, 22, 23,
 109   24, 25, 26, 27, 28, 29, 30, 31,
 110   32, 33, 34, 35, 36, 37, 38, 39,
 111   40, 41, 42, 43, 44, 45, 46, 47,
 112   48,
 113   0
 114 };
 115
 116 /* Implement the low_arch_setup linux target ops method.  */
 117
 118 void
 119 nios2_target::low_arch_setup ()
 120 {
 121   current_process ()->tdesc = tdesc_nios2_linux;
 122 }
 123
 124 /* Implement the low_cannot_fetch_register linux target ops method.  */
 125
 126 bool
 127 nios2_target::low_cannot_fetch_register (int regno)
 128 {
 129   return (nios2_regmap[regno] == -1);
 130 }
 131
 132 /* Implement the low_cannot_store_register linux target ops method.  */
 133
 134 bool
 135 nios2_target::low_cannot_store_register (int regno)
 136 {
 137   return (nios2_regmap[regno] == -1);
 138 }
 139
 140 /* Breakpoint support.  Also see comments on nios2_breakpoint_from_pc
 141    in nios2-tdep.c.  */
 142
 143 #if defined(__nios2_arch__) && __nios2_arch__ == 2
 144 #define NIOS2_BREAKPOINT 0xb7fd0020
 145 #define CDX_BREAKPOINT 0xd7c9
 146 #else
 147 #define NIOS2_BREAKPOINT 0x003b6ffa
 148 #endif
 149
 150 /* We only register the 4-byte breakpoint, even on R2 targets which also
 151    support 2-byte breakpoints.  Since there is no supports_z_point_type
 152    function provided, gdbserver never inserts software breakpoints itself
 153    and instead relies on GDB to insert the breakpoint of the correct length
 154    via a memory write.  */
 155 static const unsigned int nios2_breakpoint = NIOS2_BREAKPOINT;
 156 #define nios2_breakpoint_len 4
 157
 158 /* Implementation of target ops method "sw_breakpoint_from_kind".  */
 159
 160 const gdb_byte *
 161 nios2_target::sw_breakpoint_from_kind (int kind, int *size)
 162 {
 163   *size = nios2_breakpoint_len;
 164   return (const gdb_byte *) &nios2_breakpoint;
 165 }
 166
 167 /* Implement the low_breakpoint_at linux target ops method.  */
 168
 169 bool
 170 nios2_target::low_breakpoint_at (CORE_ADDR where)
 171 {
 172   unsigned int insn;
 173
 174   /* For R2, first check for the 2-byte CDX trap.n breakpoint encoding.  */
 175 #if defined(__nios2_arch__) && __nios2_arch__ == 2
 176   read_memory (where, (unsigned char *) &insn, 2);
 177   if (insn == CDX_BREAKPOINT)
 178     return true;
 179 #endif
 180
 181   read_memory (where, (unsigned char *) &insn, 4);
 182   if (insn == nios2_breakpoint)
 183     return true;
 184   return false;
 185 }
 186
 187 /* Fetch the thread-local storage pointer for libthread_db.  */
 188
 189 ps_err_e
 190 ps_get_thread_area (struct ps_prochandle *ph,
 191                     lwpid_t lwpid, int idx, void **base)
 192 {
 193   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
 194     return PS_ERR;
 195
 196   /* IDX is the bias from the thread pointer to the beginning of the
 197      thread descriptor.  It has to be subtracted due to implementation
 198      quirks in libthread_db.  */
 199   *base = (void *) ((char *) *base - idx);
 200
 201   return PS_OK;
 202 }
 203
 204 /* Helper functions to collect/supply a single register REGNO.  */
 205
 206 static void
 207 nios2_collect_register (struct regcache *regcache, int regno,
 208                         union nios2_register *reg)
 209 {
 210   union nios2_register tmp_reg;
 211
 212   collect_register (regcache, regno, &tmp_reg.reg32);
 213   reg->reg32 = tmp_reg.reg32;
 214 }
 215
 216 static void
 217 nios2_supply_register (struct regcache *regcache, int regno,
 218                        const union nios2_register *reg)
 219 {
 220   supply_register (regcache, regno, reg->buf);
 221 }
 222
 223 /* We have only a single register set on Nios II.  */
 224
 225 static void
 226 nios2_fill_gregset (struct regcache *regcache, void *buf)
 227 {
 228   union nios2_register *regset = (union nios2_register *) buf;
 229   int i;
 230
 231   for (i = 1; i < nios2_num_regs; i++)
 232     nios2_collect_register (regcache, i, regset + i);
 233 }
 234
 235 static void
 236 nios2_store_gregset (struct regcache *regcache, const void *buf)
 237 {
 238   const union nios2_register *regset = (union nios2_register *) buf;
 239   int i;
 240
 241   for (i = 0; i < nios2_num_regs; i++)
 242     nios2_supply_register (regcache, i, regset + i);
 243 }
 244
 245 static struct regset_info nios2_regsets[] =
 246 {
 247   { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,
 248     nios2_num_regs * 4, GENERAL_REGS,
 249     nios2_fill_gregset, nios2_store_gregset },
 250   NULL_REGSET
 251 };
 252
 253 static struct regsets_info nios2_regsets_info =
 254   {
 255     nios2_regsets, /* regsets */
 256     0, /* num_regsets */
 257     NULL, /* disabled_regsets */
 258   };
 259
 260 static struct usrregs_info nios2_usrregs_info =
 261   {
 262     nios2_num_regs,
 263     nios2_regmap,
 264   };
 265
 266 static struct regs_info myregs_info =
 267   {
 268     NULL, /* regset_bitmap */
 269     &nios2_usrregs_info,
 270     &nios2_regsets_info
 271   };
 272
 273 const regs_info *
 274 nios2_target::get_regs_info ()
 275 {
 276   return &myregs_info;
 277 }
 278
 279 /* The linux target ops object.  */
 280
 281 linux_process_target *the_linux_target = &the_nios2_target;
 282
 283 void
 284 initialize_low_arch (void)
 285 {
 286   init_registers_nios2_linux ();
 287
 288   initialize_regsets_info (&nios2_regsets_info);
 289 }