gdb/nios2-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on Nios II.
   2    Copyright (C) 2012-2015 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 #include "features/nios2-linux.c"
  34
  35 /* Core file and register set support.  */
  36
  37 /* Map from the normal register enumeration order to the order that
  38    registers appear in core files, which corresponds to the order
  39    of the register slots in the kernel's struct pt_regs.  */
  40
  41 static const int reg_offsets[NIOS2_NUM_REGS] =
  42 {
  43   -1,  8,  9, 10, 11, 12, 13, 14,       /* r0 - r7 */
  44   0,  1,  2,  3,  4,  5,  6,  7,        /* r8 - r15 */
  45   23, 24, 25, 26, 27, 28, 29, 30,       /* r16 - r23 */
  46   -1, -1, 19, 18, 17, 21, -1, 16,       /* et bt gp sp fp ea sstatus ra */
  47   21,                                   /* pc */
  48   -1, 20, -1, -1, -1, -1, -1, -1,       /* status estatus ...  */
  49   -1, -1, -1, -1, -1, -1, -1, -1
  50 };
  51
  52 /* General register set size.  Should match sizeof (struct pt_regs) +
  53    sizeof (struct switch_stack) from the NIOS2 Linux kernel patch.  */
  54
  55 #define NIOS2_GREGS_SIZE (4 * 34)
  56
  57 /* Implement the supply_regset hook for core files.  */
  58
  59 static void
  60 nios2_supply_gregset (const struct regset *regset,
  61                       struct regcache *regcache,
  62                       int regnum, const void *gregs_buf, size_t len)
  63 {
  64   const gdb_byte *gregs = gregs_buf;
  65   int regno;
  66   static const gdb_byte zero_buf[4] = {0, 0, 0, 0};
  67
  68   for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
  69     if (regnum == -1 || regnum == regno)
  70       {
  71         if (reg_offsets[regno] != -1)
  72           regcache_raw_supply (regcache, regno,
  73                                gregs + 4 * reg_offsets[regno]);
  74         else
  75           regcache_raw_supply (regcache, regno, zero_buf);
  76       }
  77 }
  78
  79 /* Implement the collect_regset hook for core files.  */
  80
  81 static void
  82 nios2_collect_gregset (const struct regset *regset,
  83                        const struct regcache *regcache,
  84                        int regnum, void *gregs_buf, size_t len)
  85 {
  86   gdb_byte *gregs = gregs_buf;
  87   int regno;
  88
  89   for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
  90     if (regnum == -1 || regnum == regno)
  91       {
  92         if (reg_offsets[regno] != -1)
  93           regcache_raw_collect (regcache, regno,
  94                                 gregs + 4 * reg_offsets[regno]);
  95       }
  96 }
  97
  98 static const struct regset nios2_core_regset =
  99 {
 100   NULL,
 101   nios2_supply_gregset,
 102   nios2_collect_gregset
 103 };
 104
 105 /* Iterate over core file register note sections.  */
 106
 107 static void
 108 nios2_iterate_over_regset_sections (struct gdbarch *gdbarch,
 109                                     iterate_over_regset_sections_cb *cb,
 110                                     void *cb_data,
 111                                     const struct regcache *regcache)
 112 {
 113   cb (".reg", NIOS2_GREGS_SIZE, &nios2_core_regset, NULL, cb_data);
 114 }
 115
 116 /* Initialize a trad-frame cache corresponding to the tramp-frame.
 117    FUNC is the address of the instruction TRAMP[0] in memory.
 118
 119    This ABI is not documented.  It corresponds to rt_setup_ucontext in
 120    the kernel arch/nios2/kernel/signal.c file.
 121
 122    The key points are:
 123    - The kernel creates a trampoline at the hard-wired address 0x1044.
 124    - The stack pointer points to an object of type struct rt_sigframe.
 125      The definition of this structure is not exported from the kernel.
 126      The register save area is located at offset 152 bytes (as determined
 127      by inspection of the stack contents in the debugger), and the
 128      registers are saved as r1-r23, ra, fp, gp, ea, sp.
 129
 130    This interface was implemented with kernel version 3.19 (the first
 131    official mainline kernel).  Older unofficial kernel versions used
 132    incompatible conventions; we do not support those here.  */
 133
 134 #define NIOS2_SIGRETURN_TRAMP_ADDR 0x1044
 135 #define NIOS2_SIGRETURN_REGSAVE_OFFSET 152
 136
 137 static void
 138 nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
 139                                struct frame_info *next_frame,
 140                                struct trad_frame_cache *this_cache,
 141                                CORE_ADDR func)
 142 {
 143   CORE_ADDR sp = get_frame_register_unsigned (next_frame, NIOS2_SP_REGNUM);
 144   CORE_ADDR base = sp + NIOS2_SIGRETURN_REGSAVE_OFFSET;
 145   int i;
 146
 147   for (i = 0; i < 23; i++)
 148     trad_frame_set_reg_addr (this_cache, i + 1, base + i * 4);
 149   trad_frame_set_reg_addr (this_cache, NIOS2_RA_REGNUM, base + 23 * 4);
 150   trad_frame_set_reg_addr (this_cache, NIOS2_FP_REGNUM, base + 24 * 4);
 151   trad_frame_set_reg_addr (this_cache, NIOS2_GP_REGNUM, base + 25 * 4);
 152   trad_frame_set_reg_addr (this_cache, NIOS2_PC_REGNUM, base + 27 * 4);
 153   trad_frame_set_reg_addr (this_cache, NIOS2_SP_REGNUM, base + 28 * 4);
 154
 155   /* Save a frame ID.  */
 156   trad_frame_set_id (this_cache, frame_id_build (base, func));
 157 }
 158
 159 static struct tramp_frame nios2_linux_rt_sigreturn_tramp_frame =
 160 {
 161   SIGTRAMP_FRAME,
 162   4,
 163   {
 164     { 0x00800004 | (139 << 6), -1 },  /* movi r2,__NR_rt_sigreturn */
 165     { 0x003b683a, -1 },               /* trap */
 166     { TRAMP_SENTINEL_INSN }
 167   },
 168   nios2_linux_rt_sigreturn_init
 169 };
 170
 171 /* When FRAME is at a syscall instruction, return the PC of the next
 172    instruction to be executed.  */
 173
 174 static CORE_ADDR
 175 nios2_linux_syscall_next_pc (struct frame_info *frame)
 176 {
 177   CORE_ADDR pc = get_frame_pc (frame);
 178   ULONGEST syscall_nr = get_frame_register_unsigned (frame, NIOS2_R2_REGNUM);
 179
 180   /* If we are about to make a sigreturn syscall, use the unwinder to
 181      decode the signal frame.  */
 182   if (syscall_nr == 139 /* rt_sigreturn */)
 183     return frame_unwind_caller_pc (frame);
 184
 185   return pc + NIOS2_OPCODE_SIZE;
 186 }
 187
 188 /* Hook function for gdbarch_register_osabi.  */
 189
 190 static void
 191 nios2_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 192 {
 193   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 194
 195   linux_init_abi (info, gdbarch);
 196
 197   /* Shared library handling.  */
 198   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 199   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 200
 201   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 202                                          svr4_ilp32_fetch_link_map_offsets);
 203   /* Enable TLS support.  */
 204   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 205                                              svr4_fetch_objfile_link_map);
 206   /* Core file support.  */
 207   set_gdbarch_iterate_over_regset_sections
 208     (gdbarch, nios2_iterate_over_regset_sections);
 209   /* Linux signal frame unwinders.  */
 210   tramp_frame_prepend_unwinder (gdbarch,
 211                                 &nios2_linux_rt_sigreturn_tramp_frame);
 212
 213   tdep->syscall_next_pc = nios2_linux_syscall_next_pc;
 214
 215   /* Index of target address word in glibc jmp_buf.  */
 216   tdep->jb_pc = 10;
 217 }
 218
 219 /* Provide a prototype to silence -Wmissing-prototypes.  */
 220
 221 extern initialize_file_ftype _initialize_nios2_linux_tdep;
 222
 223 void
 224 _initialize_nios2_linux_tdep (void)
 225 {
 226   gdbarch_register_osabi (bfd_arch_nios2, 0, GDB_OSABI_LINUX,
 227                           nios2_linux_init_abi);
 228
 229   initialize_tdesc_nios2_linux ();
 230 }