| 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 | /* 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 | /* Breakpoint support. Also see comments on nios2_breakpoint_from_pc |
| 99 | in nios2-tdep.c. */ |
| 100 | |
| 101 | #if defined(__nios2_arch__) && __nios2_arch__ == 2 |
| 102 | #define NIOS2_BREAKPOINT 0xb7fd0020 |
| 103 | #define CDX_BREAKPOINT 0xd7c9 |
| 104 | #else |
| 105 | #define NIOS2_BREAKPOINT 0x003b6ffa |
| 106 | #endif |
| 107 | |
| 108 | /* We only register the 4-byte breakpoint, even on R2 targets which also |
| 109 | support 2-byte breakpoints. Since there is no supports_z_point_type |
| 110 | function provided, gdbserver never inserts software breakpoints itself |
| 111 | and instead relies on GDB to insert the breakpoint of the correct length |
| 112 | via a memory write. */ |
| 113 | static const unsigned int nios2_breakpoint = NIOS2_BREAKPOINT; |
| 114 | #define nios2_breakpoint_len 4 |
| 115 | |
| 116 | /* Implementation of linux_target_ops method "sw_breakpoint_from_kind". */ |
| 117 | |
| 118 | static const gdb_byte * |
| 119 | nios2_sw_breakpoint_from_kind (int kind, int *size) |
| 120 | { |
| 121 | *size = nios2_breakpoint_len; |
| 122 | return (const gdb_byte *) &nios2_breakpoint; |
| 123 | } |
| 124 | |
| 125 | /* Implement the breakpoint_at linux_target_ops method. */ |
| 126 | |
| 127 | static int |
| 128 | nios2_breakpoint_at (CORE_ADDR where) |
| 129 | { |
| 130 | unsigned int insn; |
| 131 | |
| 132 | /* For R2, first check for the 2-byte CDX trap.n breakpoint encoding. */ |
| 133 | #if defined(__nios2_arch__) && __nios2_arch__ == 2 |
| 134 | the_target->read_memory (where, (unsigned char *) &insn, 2); |
| 135 | if (insn == CDX_BREAKPOINT) |
| 136 | return 1; |
| 137 | #endif |
| 138 | |
| 139 | the_target->read_memory (where, (unsigned char *) &insn, 4); |
| 140 | if (insn == nios2_breakpoint) |
| 141 | return 1; |
| 142 | return 0; |
| 143 | } |
| 144 | |
| 145 | /* Fetch the thread-local storage pointer for libthread_db. */ |
| 146 | |
| 147 | ps_err_e |
| 148 | ps_get_thread_area (struct ps_prochandle *ph, |
| 149 | lwpid_t lwpid, int idx, void **base) |
| 150 | { |
| 151 | if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0) |
| 152 | return PS_ERR; |
| 153 | |
| 154 | /* IDX is the bias from the thread pointer to the beginning of the |
| 155 | thread descriptor. It has to be subtracted due to implementation |
| 156 | quirks in libthread_db. */ |
| 157 | *base = (void *) ((char *) *base - idx); |
| 158 | |
| 159 | return PS_OK; |
| 160 | } |
| 161 | |
| 162 | /* Helper functions to collect/supply a single register REGNO. */ |
| 163 | |
| 164 | static void |
| 165 | nios2_collect_register (struct regcache *regcache, int regno, |
| 166 | union nios2_register *reg) |
| 167 | { |
| 168 | union nios2_register tmp_reg; |
| 169 | |
| 170 | collect_register (regcache, regno, &tmp_reg.reg32); |
| 171 | reg->reg32 = tmp_reg.reg32; |
| 172 | } |
| 173 | |
| 174 | static void |
| 175 | nios2_supply_register (struct regcache *regcache, int regno, |
| 176 | const union nios2_register *reg) |
| 177 | { |
| 178 | supply_register (regcache, regno, reg->buf); |
| 179 | } |
| 180 | |
| 181 | /* We have only a single register set on Nios II. */ |
| 182 | |
| 183 | static void |
| 184 | nios2_fill_gregset (struct regcache *regcache, void *buf) |
| 185 | { |
| 186 | union nios2_register *regset = (union nios2_register *) buf; |
| 187 | int i; |
| 188 | |
| 189 | for (i = 1; i < nios2_num_regs; i++) |
| 190 | nios2_collect_register (regcache, i, regset + i); |
| 191 | } |
| 192 | |
| 193 | static void |
| 194 | nios2_store_gregset (struct regcache *regcache, const void *buf) |
| 195 | { |
| 196 | const union nios2_register *regset = (union nios2_register *) buf; |
| 197 | int i; |
| 198 | |
| 199 | for (i = 0; i < nios2_num_regs; i++) |
| 200 | nios2_supply_register (regcache, i, regset + i); |
| 201 | } |
| 202 | |
| 203 | static struct regset_info nios2_regsets[] = |
| 204 | { |
| 205 | { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS, |
| 206 | nios2_num_regs * 4, GENERAL_REGS, |
| 207 | nios2_fill_gregset, nios2_store_gregset }, |
| 208 | NULL_REGSET |
| 209 | }; |
| 210 | |
| 211 | static struct regsets_info nios2_regsets_info = |
| 212 | { |
| 213 | nios2_regsets, /* regsets */ |
| 214 | 0, /* num_regsets */ |
| 215 | NULL, /* disabled_regsets */ |
| 216 | }; |
| 217 | |
| 218 | static struct usrregs_info nios2_usrregs_info = |
| 219 | { |
| 220 | nios2_num_regs, |
| 221 | nios2_regmap, |
| 222 | }; |
| 223 | |
| 224 | static struct regs_info regs_info = |
| 225 | { |
| 226 | NULL, /* regset_bitmap */ |
| 227 | &nios2_usrregs_info, |
| 228 | &nios2_regsets_info |
| 229 | }; |
| 230 | |
| 231 | static const struct regs_info * |
| 232 | nios2_regs_info (void) |
| 233 | { |
| 234 | return ®s_info; |
| 235 | } |
| 236 | |
| 237 | struct linux_target_ops the_low_target = |
| 238 | { |
| 239 | nios2_arch_setup, |
| 240 | nios2_regs_info, |
| 241 | nios2_cannot_fetch_register, |
| 242 | nios2_cannot_store_register, |
| 243 | NULL, |
| 244 | linux_get_pc_32bit, |
| 245 | linux_set_pc_32bit, |
| 246 | NULL, /* breakpoint_kind_from_pc */ |
| 247 | nios2_sw_breakpoint_from_kind, |
| 248 | NULL, /* get_next_pcs */ |
| 249 | 0, |
| 250 | nios2_breakpoint_at, |
| 251 | }; |
| 252 | |
| 253 | void |
| 254 | initialize_low_arch (void) |
| 255 | { |
| 256 | init_registers_nios2_linux (); |
| 257 | |
| 258 | initialize_regsets_info (&nios2_regsets_info); |
| 259 | } |