gdb/mips-sde-tdep.c

   1 /* Target-dependent code for SDE on MIPS processors.
   2
   3    Copyright (C) 2014-2020 Free Software Foundation, 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 "osabi.h"
  22 #include "elf-bfd.h"
  23 #include "block.h"
  24 #include "symtab.h"
  25
  26 #include "frame.h"
  27 #include "frame-unwind.h"
  28 #include "frame-base.h"
  29 #include "trad-frame.h"
  30
  31 #include "mips-tdep.h"
  32
  33 /* Fill in the register cache *THIS_CACHE for THIS_FRAME for use
  34    in the SDE frame unwinder.  */
  35
  36 static struct trad_frame_cache *
  37 mips_sde_frame_cache (struct frame_info *this_frame, void **this_cache)
  38 {
  39   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  40   const struct mips_regnum *regs = mips_regnum (gdbarch);
  41   const int sizeof_reg_t = mips_abi_regsize (gdbarch);
  42   enum mips_abi abi = mips_abi (gdbarch);
  43   struct trad_frame_cache *cache;
  44   CORE_ADDR xcpt_frame;
  45   CORE_ADDR start_addr;
  46   CORE_ADDR stack_addr;
  47   CORE_ADDR pc;
  48   int i;
  49
  50   if (*this_cache != NULL)
  51     return (struct trad_frame_cache *) *this_cache;
  52   cache = trad_frame_cache_zalloc (this_frame);
  53   *this_cache = cache;
  54
  55   /* The previous registers are held in struct xcptcontext
  56      which is at $sp+offs
  57
  58      struct xcptcontext {
  59        reg_t    sr;             CP0 Status
  60        reg_t    cr;             CP0 Cause
  61        reg_t    epc;            CP0 EPC
  62        reg_t    vaddr;          CP0 BadVAddr
  63        reg_t    regs[32];       General registers
  64        reg_t    mdlo;           LO
  65        reg_t    mdhi;           HI
  66        reg_t    mdex;           ACX
  67        ...
  68      };
  69   */
  70
  71   stack_addr = get_frame_register_signed (this_frame,
  72                                           gdbarch_sp_regnum (gdbarch));
  73   switch (abi)
  74     {
  75     case MIPS_ABI_O32:
  76       /* 40: XCPTCONTEXT
  77          24: xcpt_gen() argspace                (16 bytes)
  78          16: _xcptcall() saved ra, rounded up   ( 8 bytes)
  79          00: _xcptcall() argspace               (16 bytes)  */
  80       xcpt_frame = stack_addr + 40;
  81       break;
  82     case MIPS_ABI_N32:
  83     case MIPS_ABI_N64:
  84     default:                    /* Wild guess.  */
  85       /* 16: XCPTCONTEXT
  86          16: xcpt_gen() argspace                ( 0 bytes)
  87          00: _xcptcall() saved ra, rounded up   (16 bytes)  */
  88       xcpt_frame = stack_addr + 16;
  89       break;
  90     }
  91
  92   trad_frame_set_reg_addr (cache,
  93                            MIPS_PS_REGNUM + gdbarch_num_regs (gdbarch),
  94                            xcpt_frame + 0 * sizeof_reg_t);
  95   trad_frame_set_reg_addr (cache,
  96                            regs->cause + gdbarch_num_regs (gdbarch),
  97                            xcpt_frame + 1 * sizeof_reg_t);
  98   trad_frame_set_reg_addr (cache,
  99                            regs->pc + gdbarch_num_regs (gdbarch),
 100                            xcpt_frame + 2 * sizeof_reg_t);
 101   trad_frame_set_reg_addr (cache,
 102                            regs->badvaddr + gdbarch_num_regs (gdbarch),
 103                            xcpt_frame + 3 * sizeof_reg_t);
 104   for (i = 0; i < MIPS_NUMREGS; i++)
 105     trad_frame_set_reg_addr (cache,
 106                              i + MIPS_ZERO_REGNUM + gdbarch_num_regs (gdbarch),
 107                              xcpt_frame + (4 + i) * sizeof_reg_t);
 108   trad_frame_set_reg_addr (cache,
 109                            regs->lo + gdbarch_num_regs (gdbarch),
 110                            xcpt_frame + 36 * sizeof_reg_t);
 111   trad_frame_set_reg_addr (cache,
 112                            regs->hi + gdbarch_num_regs (gdbarch),
 113                            xcpt_frame + 37 * sizeof_reg_t);
 114
 115   pc = get_frame_pc (this_frame);
 116   find_pc_partial_function (pc, NULL, &start_addr, NULL);
 117   trad_frame_set_id (cache, frame_id_build (start_addr, stack_addr));
 118
 119   return cache;
 120 }
 121
 122 /* Implement the this_id function for the SDE frame unwinder.  */
 123
 124 static void
 125 mips_sde_frame_this_id (struct frame_info *this_frame, void **this_cache,
 126                         struct frame_id *this_id)
 127 {
 128   struct trad_frame_cache *this_trad_cache
 129     = mips_sde_frame_cache (this_frame, this_cache);
 130
 131   trad_frame_get_id (this_trad_cache, this_id);
 132 }
 133
 134 /* Implement the prev_register function for the SDE frame unwinder.  */
 135
 136 static struct value *
 137 mips_sde_frame_prev_register (struct frame_info *this_frame,
 138                               void **this_cache,
 139                               int prev_regnum)
 140 {
 141   struct trad_frame_cache *trad_cache
 142     = mips_sde_frame_cache (this_frame, this_cache);
 143
 144   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
 145 }
 146
 147 /* Implement the sniffer function for the SDE frame unwinder.  */
 148
 149 static int
 150 mips_sde_frame_sniffer (const struct frame_unwind *self,
 151                         struct frame_info *this_frame,
 152                         void **this_cache)
 153 {
 154   CORE_ADDR pc = get_frame_pc (this_frame);
 155   const char *name;
 156
 157   find_pc_partial_function (pc, &name, NULL, NULL);
 158   return (name
 159           && (strcmp (name, "_xcptcall") == 0
 160               || strcmp (name, "_sigtramp") == 0));
 161 }
 162
 163 /* Data structure for the SDE frame unwinder.  */
 164
 165 static const struct frame_unwind mips_sde_frame_unwind =
 166 {
 167   SIGTRAMP_FRAME,
 168   default_frame_unwind_stop_reason,
 169   mips_sde_frame_this_id,
 170   mips_sde_frame_prev_register,
 171   NULL,
 172   mips_sde_frame_sniffer
 173 };
 174
 175 /* Implement the this_base, this_locals, and this_args hooks
 176    for the normal unwinder.  */
 177
 178 static CORE_ADDR
 179 mips_sde_frame_base_address (struct frame_info *this_frame, void **this_cache)
 180 {
 181   struct trad_frame_cache *this_trad_cache
 182     = mips_sde_frame_cache (this_frame, this_cache);
 183
 184   return trad_frame_get_this_base (this_trad_cache);
 185 }
 186
 187 static const struct frame_base mips_sde_frame_base =
 188 {
 189   &mips_sde_frame_unwind,
 190   mips_sde_frame_base_address,
 191   mips_sde_frame_base_address,
 192   mips_sde_frame_base_address
 193 };
 194
 195 static const struct frame_base *
 196 mips_sde_frame_base_sniffer (struct frame_info *this_frame)
 197 {
 198   if (mips_sde_frame_sniffer (&mips_sde_frame_unwind, this_frame, NULL))
 199     return &mips_sde_frame_base;
 200   else
 201     return NULL;
 202 }
 203
 204 static void
 205 mips_sde_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect,
 206                                            void *obj)
 207 {
 208   enum gdb_osabi *os_ident_ptr = (enum gdb_osabi *) obj;
 209   const char *name;
 210
 211   name = bfd_section_name (sect);
 212
 213   /* The presence of a section with a ".sde" prefix is indicative
 214      of an SDE binary.  */
 215   if (startswith (name, ".sde"))
 216     *os_ident_ptr = GDB_OSABI_SDE;
 217 }
 218
 219 /* OSABI sniffer for MIPS SDE.  */
 220
 221 static enum gdb_osabi
 222 mips_sde_elf_osabi_sniffer (bfd *abfd)
 223 {
 224   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
 225   unsigned int elfosabi;
 226
 227   /* If the generic sniffer gets a hit, return and let other sniffers
 228      get a crack at it.  */
 229   bfd_map_over_sections (abfd,
 230                          generic_elf_osabi_sniff_abi_tag_sections,
 231                          &osabi);
 232   if (osabi != GDB_OSABI_UNKNOWN)
 233     return GDB_OSABI_UNKNOWN;
 234
 235   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 236
 237   if (elfosabi == ELFOSABI_NONE)
 238     {
 239       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
 240          file are conforming to the base specification for that machine
 241          (there are no OS-specific extensions).  In order to determine the
 242          real OS in use we must look for OS notes that have been added.
 243
 244          For SDE, we simply look for sections named with .sde as prefixes.  */
 245       bfd_map_over_sections (abfd,
 246                              mips_sde_elf_osabi_sniff_abi_tag_sections,
 247                              &osabi);
 248     }
 249   return osabi;
 250 }
 251
 252 static void
 253 mips_sde_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 254 {
 255   frame_unwind_append_unwinder (gdbarch, &mips_sde_frame_unwind);
 256   frame_base_append_sniffer (gdbarch, mips_sde_frame_base_sniffer);
 257 }
 258
 259 void
 260 _initialize_mips_sde_tdep (void)
 261 {
 262   gdbarch_register_osabi_sniffer (bfd_arch_mips,
 263                                   bfd_target_elf_flavour,
 264                                   mips_sde_elf_osabi_sniffer);
 265
 266   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_SDE, mips_sde_init_abi);
 267 }