gdb/nios2-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on Nios II.
   2    Copyright (C) 2012-2018 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
  33 /* Core file and register set support.  */
  34
  35 /* Map from the normal register enumeration order to the order that
  36    registers appear in core files, which corresponds to the order
  37    of the register slots in the kernel's struct pt_regs.  */
  38
  39 static const int reg_offsets[NIOS2_NUM_REGS] =
  40 {
  41   -1,  8,  9, 10, 11, 12, 13, 14,       /* r0 - r7 */
  42   0,  1,  2,  3,  4,  5,  6,  7,        /* r8 - r15 */
  43   23, 24, 25, 26, 27, 28, 29, 30,       /* r16 - r23 */
  44   -1, -1, 19, 18, 17, 21, -1, 16,       /* et bt gp sp fp ea sstatus ra */
  45   21,                                   /* pc */
  46   -1, 20, -1, -1, -1, -1, -1, -1,       /* status estatus ...  */
  47   -1, -1, -1, -1, -1, -1, -1, -1
  48 };
  49
  50 /* General register set size.  Should match sizeof (struct pt_regs) +
  51    sizeof (struct switch_stack) from the NIOS2 Linux kernel patch.  */
  52
  53 #define NIOS2_GREGS_SIZE (4 * 34)
  54
  55 /* Implement the supply_regset hook for core files.  */
  56
  57 static void
  58 nios2_supply_gregset (const struct regset *regset,
  59                       struct regcache *regcache,
  60                       int regnum, const void *gregs_buf, size_t len)
  61 {
  62   const gdb_byte *gregs = (const gdb_byte *) gregs_buf;
  63   int regno;
  64   static const gdb_byte zero_buf[4] = {0, 0, 0, 0};
  65
  66   for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
  67     if (regnum == -1 || regnum == regno)
  68       {
  69         if (reg_offsets[regno] != -1)
  70           regcache->raw_supply (regno, gregs + 4 * reg_offsets[regno]);
  71         else
  72           regcache->raw_supply (regno, zero_buf);
  73       }
  74 }
  75
  76 /* Implement the collect_regset hook for core files.  */
  77
  78 static void
  79 nios2_collect_gregset (const struct regset *regset,
  80                        const struct regcache *regcache,
  81                        int regnum, void *gregs_buf, size_t len)
  82 {
  83   gdb_byte *gregs = (gdb_byte *) gregs_buf;
  84   int regno;
  85
  86   for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
  87     if (regnum == -1 || regnum == regno)
  88       {
  89         if (reg_offsets[regno] != -1)
  90           regcache->raw_collect (regno, gregs + 4 * reg_offsets[regno]);
  91       }
  92 }
  93
  94 static const struct regset nios2_core_regset =
  95 {
  96   NULL,
  97   nios2_supply_gregset,
  98   nios2_collect_gregset
  99 };
 100
 101 /* Iterate over core file register note sections.  */
 102
 103 static void
 104 nios2_iterate_over_regset_sections (struct gdbarch *gdbarch,
 105                                     iterate_over_regset_sections_cb *cb,
 106                                     void *cb_data,
 107                                     const struct regcache *regcache)
 108 {
 109   cb (".reg", NIOS2_GREGS_SIZE, &nios2_core_regset, NULL, cb_data);
 110 }
 111
 112 /* Initialize a trad-frame cache corresponding to the tramp-frame.
 113    FUNC is the address of the instruction TRAMP[0] in memory.
 114
 115    This ABI is not documented.  It corresponds to rt_setup_ucontext in
 116    the kernel arch/nios2/kernel/signal.c file.
 117
 118    The key points are:
 119    - The kernel creates a trampoline at the hard-wired address 0x1044.
 120    - The stack pointer points to an object of type struct rt_sigframe.
 121      The definition of this structure is not exported from the kernel.
 122      The register save area is located at offset 152 bytes (as determined
 123      by inspection of the stack contents in the debugger), and the
 124      registers are saved as r1-r23, ra, fp, gp, ea, sp.
 125
 126    This interface was implemented with kernel version 3.19 (the first
 127    official mainline kernel).  Older unofficial kernel versions used
 128    incompatible conventions; we do not support those here.  */
 129
 130 #define NIOS2_SIGRETURN_TRAMP_ADDR 0x1044
 131 #define NIOS2_SIGRETURN_REGSAVE_OFFSET 152
 132
 133 static void
 134 nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
 135                                struct frame_info *next_frame,
 136                                struct trad_frame_cache *this_cache,
 137                                CORE_ADDR func)
 138 {
 139   CORE_ADDR sp = get_frame_register_unsigned (next_frame, NIOS2_SP_REGNUM);
 140   CORE_ADDR base = sp + NIOS2_SIGRETURN_REGSAVE_OFFSET;
 141   int i;
 142
 143   for (i = 0; i < 23; i++)
 144     trad_frame_set_reg_addr (this_cache, i + 1, base + i * 4);
 145   trad_frame_set_reg_addr (this_cache, NIOS2_RA_REGNUM, base + 23 * 4);
 146   trad_frame_set_reg_addr (this_cache, NIOS2_FP_REGNUM, base + 24 * 4);
 147   trad_frame_set_reg_addr (this_cache, NIOS2_GP_REGNUM, base + 25 * 4);
 148   trad_frame_set_reg_addr (this_cache, NIOS2_PC_REGNUM, base + 27 * 4);
 149   trad_frame_set_reg_addr (this_cache, NIOS2_SP_REGNUM, base + 28 * 4);
 150
 151   /* Save a frame ID.  */
 152   trad_frame_set_id (this_cache, frame_id_build (base, func));
 153 }
 154
 155 /* Trampoline for sigreturn.  This has the form
 156      movi r2, __NR_rt_sigreturn
 157      trap 0
 158    appropriately encoded for R1 or R2.  */
 159
 160 static struct tramp_frame nios2_r1_linux_rt_sigreturn_tramp_frame =
 161 {
 162   SIGTRAMP_FRAME,
 163   4,
 164   {
 165     { MATCH_R1_MOVI | SET_IW_I_B (2) | SET_IW_I_IMM16 (139), -1 },
 166     { MATCH_R1_TRAP | SET_IW_R_IMM5 (0), -1},
 167     { TRAMP_SENTINEL_INSN }
 168   },
 169   nios2_linux_rt_sigreturn_init
 170 };
 171
 172 static struct tramp_frame nios2_r2_linux_rt_sigreturn_tramp_frame =
 173 {
 174   SIGTRAMP_FRAME,
 175   4,
 176   {
 177     { MATCH_R2_MOVI | SET_IW_F2I16_B (2) | SET_IW_F2I16_IMM16 (139), -1 },
 178     { MATCH_R2_TRAP | SET_IW_X2L5_IMM5 (0), -1},
 179     { TRAMP_SENTINEL_INSN }
 180   },
 181   nios2_linux_rt_sigreturn_init
 182 };
 183
 184 /* When FRAME is at a syscall instruction, return the PC of the next
 185    instruction to be executed.  */
 186
 187 static CORE_ADDR
 188 nios2_linux_syscall_next_pc (struct frame_info *frame,
 189                              const struct nios2_opcode *op)
 190 {
 191   CORE_ADDR pc = get_frame_pc (frame);
 192   ULONGEST syscall_nr = get_frame_register_unsigned (frame, NIOS2_R2_REGNUM);
 193
 194   /* If we are about to make a sigreturn syscall, use the unwinder to
 195      decode the signal frame.  */
 196   if (syscall_nr == 139 /* rt_sigreturn */)
 197     return frame_unwind_caller_pc (frame);
 198
 199   return pc + op->size;
 200 }
 201
 202 /* Hook function for gdbarch_register_osabi.  */
 203
 204 static void
 205 nios2_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 206 {
 207   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 208
 209   linux_init_abi (info, gdbarch);
 210
 211   /* Shared library handling.  */
 212   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 213   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 214
 215   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 216                                          svr4_ilp32_fetch_link_map_offsets);
 217   /* Enable TLS support.  */
 218   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 219                                              svr4_fetch_objfile_link_map);
 220   /* Core file support.  */
 221   set_gdbarch_iterate_over_regset_sections
 222     (gdbarch, nios2_iterate_over_regset_sections);
 223   /* Linux signal frame unwinders.  */
 224   if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_nios2r2)
 225     tramp_frame_prepend_unwinder (gdbarch,
 226                                   &nios2_r2_linux_rt_sigreturn_tramp_frame);
 227   else
 228     tramp_frame_prepend_unwinder (gdbarch,
 229                                   &nios2_r1_linux_rt_sigreturn_tramp_frame);
 230
 231   tdep->syscall_next_pc = nios2_linux_syscall_next_pc;
 232
 233   /* Index of target address word in glibc jmp_buf.  */
 234   tdep->jb_pc = 10;
 235 }
 236
 237 void
 238 _initialize_nios2_linux_tdep (void)
 239 {
 240
 241   const struct bfd_arch_info *arch_info;
 242
 243   for (arch_info = bfd_lookup_arch (bfd_arch_nios2, 0);
 244        arch_info != NULL;
 245        arch_info = arch_info->next)
 246     gdbarch_register_osabi (bfd_arch_nios2, arch_info->mach,
 247                             GDB_OSABI_LINUX, nios2_linux_init_abi);
 248 }