| 1 | /* Target-dependent code for GNU/Linux on Nios II. |
| 2 | Copyright (C) 2012-2020 Free Software Foundation, Inc. |
| 3 | Contributed by Mentor Graphics, 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 "frame.h" |
| 22 | #include "osabi.h" |
| 23 | #include "solib-svr4.h" |
| 24 | #include "trad-frame.h" |
| 25 | #include "tramp-frame.h" |
| 26 | #include "symtab.h" |
| 27 | #include "regset.h" |
| 28 | #include "regcache.h" |
| 29 | #include "linux-tdep.h" |
| 30 | #include "glibc-tdep.h" |
| 31 | #include "nios2-tdep.h" |
| 32 | #include "gdbarch.h" |
| 33 | |
| 34 | /* Core file and register set support. */ |
| 35 | |
| 36 | /* Map from the normal register enumeration order to the order that |
| 37 | registers appear in core files, which corresponds to the order |
| 38 | of the register slots in the kernel's struct pt_regs. */ |
| 39 | |
| 40 | static const int reg_offsets[NIOS2_NUM_REGS] = |
| 41 | { |
| 42 | -1, 8, 9, 10, 11, 12, 13, 14, /* r0 - r7 */ |
| 43 | 0, 1, 2, 3, 4, 5, 6, 7, /* r8 - r15 */ |
| 44 | 23, 24, 25, 26, 27, 28, 29, 30, /* r16 - r23 */ |
| 45 | -1, -1, 19, 18, 17, 21, -1, 16, /* et bt gp sp fp ea sstatus ra */ |
| 46 | 21, /* pc */ |
| 47 | -1, 20, -1, -1, -1, -1, -1, -1, /* status estatus ... */ |
| 48 | -1, -1, -1, -1, -1, -1, -1, -1 |
| 49 | }; |
| 50 | |
| 51 | /* General register set size. Should match sizeof (struct pt_regs) + |
| 52 | sizeof (struct switch_stack) from the NIOS2 Linux kernel patch. */ |
| 53 | |
| 54 | #define NIOS2_GREGS_SIZE (4 * 34) |
| 55 | |
| 56 | /* Implement the supply_regset hook for core files. */ |
| 57 | |
| 58 | static void |
| 59 | nios2_supply_gregset (const struct regset *regset, |
| 60 | struct regcache *regcache, |
| 61 | int regnum, const void *gregs_buf, size_t len) |
| 62 | { |
| 63 | const gdb_byte *gregs = (const gdb_byte *) gregs_buf; |
| 64 | int regno; |
| 65 | static const gdb_byte zero_buf[4] = {0, 0, 0, 0}; |
| 66 | |
| 67 | for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++) |
| 68 | if (regnum == -1 || regnum == regno) |
| 69 | { |
| 70 | if (reg_offsets[regno] != -1) |
| 71 | regcache->raw_supply (regno, gregs + 4 * reg_offsets[regno]); |
| 72 | else |
| 73 | regcache->raw_supply (regno, zero_buf); |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | /* Implement the collect_regset hook for core files. */ |
| 78 | |
| 79 | static void |
| 80 | nios2_collect_gregset (const struct regset *regset, |
| 81 | const struct regcache *regcache, |
| 82 | int regnum, void *gregs_buf, size_t len) |
| 83 | { |
| 84 | gdb_byte *gregs = (gdb_byte *) gregs_buf; |
| 85 | int regno; |
| 86 | |
| 87 | for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++) |
| 88 | if (regnum == -1 || regnum == regno) |
| 89 | { |
| 90 | if (reg_offsets[regno] != -1) |
| 91 | regcache->raw_collect (regno, gregs + 4 * reg_offsets[regno]); |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | static const struct regset nios2_core_regset = |
| 96 | { |
| 97 | NULL, |
| 98 | nios2_supply_gregset, |
| 99 | nios2_collect_gregset |
| 100 | }; |
| 101 | |
| 102 | /* Iterate over core file register note sections. */ |
| 103 | |
| 104 | static void |
| 105 | nios2_iterate_over_regset_sections (struct gdbarch *gdbarch, |
| 106 | iterate_over_regset_sections_cb *cb, |
| 107 | void *cb_data, |
| 108 | const struct regcache *regcache) |
| 109 | { |
| 110 | cb (".reg", NIOS2_GREGS_SIZE, NIOS2_GREGS_SIZE, &nios2_core_regset, NULL, |
| 111 | cb_data); |
| 112 | } |
| 113 | |
| 114 | /* Initialize a trad-frame cache corresponding to the tramp-frame. |
| 115 | FUNC is the address of the instruction TRAMP[0] in memory. |
| 116 | |
| 117 | This ABI is not documented. It corresponds to rt_setup_ucontext in |
| 118 | the kernel arch/nios2/kernel/signal.c file. |
| 119 | |
| 120 | The key points are: |
| 121 | - The kernel creates a trampoline at the hard-wired address 0x1044. |
| 122 | - The stack pointer points to an object of type struct rt_sigframe. |
| 123 | The definition of this structure is not exported from the kernel. |
| 124 | The register save area is located at offset 152 bytes (as determined |
| 125 | by inspection of the stack contents in the debugger), and the |
| 126 | registers are saved as r1-r23, ra, fp, gp, ea, sp. |
| 127 | |
| 128 | This interface was implemented with kernel version 3.19 (the first |
| 129 | official mainline kernel). Older unofficial kernel versions used |
| 130 | incompatible conventions; we do not support those here. */ |
| 131 | |
| 132 | #define NIOS2_SIGRETURN_TRAMP_ADDR 0x1044 |
| 133 | #define NIOS2_SIGRETURN_REGSAVE_OFFSET 152 |
| 134 | |
| 135 | static void |
| 136 | nios2_linux_rt_sigreturn_init (const struct tramp_frame *self, |
| 137 | struct frame_info *next_frame, |
| 138 | struct trad_frame_cache *this_cache, |
| 139 | CORE_ADDR func) |
| 140 | { |
| 141 | CORE_ADDR sp = get_frame_register_unsigned (next_frame, NIOS2_SP_REGNUM); |
| 142 | CORE_ADDR base = sp + NIOS2_SIGRETURN_REGSAVE_OFFSET; |
| 143 | int i; |
| 144 | |
| 145 | for (i = 0; i < 23; i++) |
| 146 | trad_frame_set_reg_addr (this_cache, i + 1, base + i * 4); |
| 147 | trad_frame_set_reg_addr (this_cache, NIOS2_RA_REGNUM, base + 23 * 4); |
| 148 | trad_frame_set_reg_addr (this_cache, NIOS2_FP_REGNUM, base + 24 * 4); |
| 149 | trad_frame_set_reg_addr (this_cache, NIOS2_GP_REGNUM, base + 25 * 4); |
| 150 | trad_frame_set_reg_addr (this_cache, NIOS2_PC_REGNUM, base + 27 * 4); |
| 151 | trad_frame_set_reg_addr (this_cache, NIOS2_SP_REGNUM, base + 28 * 4); |
| 152 | |
| 153 | /* Save a frame ID. */ |
| 154 | trad_frame_set_id (this_cache, frame_id_build (base, func)); |
| 155 | } |
| 156 | |
| 157 | /* Trampoline for sigreturn. This has the form |
| 158 | movi r2, __NR_rt_sigreturn |
| 159 | trap 0 |
| 160 | appropriately encoded for R1 or R2. */ |
| 161 | |
| 162 | static struct tramp_frame nios2_r1_linux_rt_sigreturn_tramp_frame = |
| 163 | { |
| 164 | SIGTRAMP_FRAME, |
| 165 | 4, |
| 166 | { |
| 167 | { MATCH_R1_MOVI | SET_IW_I_B (2) | SET_IW_I_IMM16 (139), ULONGEST_MAX }, |
| 168 | { MATCH_R1_TRAP | SET_IW_R_IMM5 (0), ULONGEST_MAX}, |
| 169 | { TRAMP_SENTINEL_INSN } |
| 170 | }, |
| 171 | nios2_linux_rt_sigreturn_init |
| 172 | }; |
| 173 | |
| 174 | static struct tramp_frame nios2_r2_linux_rt_sigreturn_tramp_frame = |
| 175 | { |
| 176 | SIGTRAMP_FRAME, |
| 177 | 4, |
| 178 | { |
| 179 | { MATCH_R2_MOVI | SET_IW_F2I16_B (2) | SET_IW_F2I16_IMM16 (139), ULONGEST_MAX }, |
| 180 | { MATCH_R2_TRAP | SET_IW_X2L5_IMM5 (0), ULONGEST_MAX}, |
| 181 | { TRAMP_SENTINEL_INSN } |
| 182 | }, |
| 183 | nios2_linux_rt_sigreturn_init |
| 184 | }; |
| 185 | |
| 186 | /* When FRAME is at a syscall instruction, return the PC of the next |
| 187 | instruction to be executed. */ |
| 188 | |
| 189 | static CORE_ADDR |
| 190 | nios2_linux_syscall_next_pc (struct frame_info *frame, |
| 191 | const struct nios2_opcode *op) |
| 192 | { |
| 193 | CORE_ADDR pc = get_frame_pc (frame); |
| 194 | ULONGEST syscall_nr = get_frame_register_unsigned (frame, NIOS2_R2_REGNUM); |
| 195 | |
| 196 | /* If we are about to make a sigreturn syscall, use the unwinder to |
| 197 | decode the signal frame. */ |
| 198 | if (syscall_nr == 139 /* rt_sigreturn */) |
| 199 | return frame_unwind_caller_pc (frame); |
| 200 | |
| 201 | return pc + op->size; |
| 202 | } |
| 203 | |
| 204 | /* Return true if PC is a kernel helper, a function mapped by the kernel |
| 205 | into user space on an unwritable page. Currently the only such function |
| 206 | is __kuser_cmpxchg at 0x1004. See arch/nios2/kernel/entry.S in the Linux |
| 207 | kernel sources and sysdeps/unix/sysv/linux/nios2/atomic-machine.h in |
| 208 | GLIBC. */ |
| 209 | static bool |
| 210 | nios2_linux_is_kernel_helper (CORE_ADDR pc) |
| 211 | { |
| 212 | return pc == 0x1004; |
| 213 | } |
| 214 | |
| 215 | /* Hook function for gdbarch_register_osabi. */ |
| 216 | |
| 217 | static void |
| 218 | nios2_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 219 | { |
| 220 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 221 | |
| 222 | linux_init_abi (info, gdbarch); |
| 223 | |
| 224 | /* Shared library handling. */ |
| 225 | set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); |
| 226 | set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver); |
| 227 | |
| 228 | set_solib_svr4_fetch_link_map_offsets (gdbarch, |
| 229 | svr4_ilp32_fetch_link_map_offsets); |
| 230 | /* Enable TLS support. */ |
| 231 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 232 | svr4_fetch_objfile_link_map); |
| 233 | /* Core file support. */ |
| 234 | set_gdbarch_iterate_over_regset_sections |
| 235 | (gdbarch, nios2_iterate_over_regset_sections); |
| 236 | /* Linux signal frame unwinders. */ |
| 237 | if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_nios2r2) |
| 238 | tramp_frame_prepend_unwinder (gdbarch, |
| 239 | &nios2_r2_linux_rt_sigreturn_tramp_frame); |
| 240 | else |
| 241 | tramp_frame_prepend_unwinder (gdbarch, |
| 242 | &nios2_r1_linux_rt_sigreturn_tramp_frame); |
| 243 | |
| 244 | tdep->syscall_next_pc = nios2_linux_syscall_next_pc; |
| 245 | tdep->is_kernel_helper = nios2_linux_is_kernel_helper; |
| 246 | |
| 247 | /* Index of target address word in glibc jmp_buf. */ |
| 248 | tdep->jb_pc = 10; |
| 249 | } |
| 250 | |
| 251 | void |
| 252 | _initialize_nios2_linux_tdep (void) |
| 253 | { |
| 254 | |
| 255 | const struct bfd_arch_info *arch_info; |
| 256 | |
| 257 | for (arch_info = bfd_lookup_arch (bfd_arch_nios2, 0); |
| 258 | arch_info != NULL; |
| 259 | arch_info = arch_info->next) |
| 260 | gdbarch_register_osabi (bfd_arch_nios2, arch_info->mach, |
| 261 | GDB_OSABI_LINUX, nios2_linux_init_abi); |
| 262 | } |