gdb/mips-sde-tdep.c

   1 /* Target-dependent code for SDE on MIPS processors.
   2
   3    Copyright (C) 2014-2024 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 "symtab.h"
  24
  25 #include "frame.h"
  26 #include "frame-unwind.h"
  27 #include "frame-base.h"
  28 #include "trad-frame.h"
  29
  30 #include "mips-tdep.h"
  31
  32 /* Fill in the register cache *THIS_CACHE for THIS_FRAME for use
  33    in the SDE frame unwinder.  */
  34
  35 static struct trad_frame_cache *
  36 mips_sde_frame_cache (frame_info_ptr this_frame, void **this_cache)
  37 {
  38   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  39   const struct mips_regnum *regs = mips_regnum (gdbarch);
  40   const int sizeof_reg_t = mips_abi_regsize (gdbarch);
  41   enum mips_abi abi = mips_abi (gdbarch);
  42   struct trad_frame_cache *cache;
  43   CORE_ADDR xcpt_frame;
  44   CORE_ADDR start_addr;
  45   CORE_ADDR stack_addr;
  46   CORE_ADDR pc;
  47   int i;
  48
  49   if (*this_cache != NULL)
  50     return (struct trad_frame_cache *) *this_cache;
  51   cache = trad_frame_cache_zalloc (this_frame);
  52   *this_cache = cache;
  53
  54   /* The previous registers are held in struct xcptcontext
  55      which is at $sp+offs
  56
  57      struct xcptcontext {
  58        reg_t    sr;             CP0 Status
  59        reg_t    cr;             CP0 Cause
  60        reg_t    epc;            CP0 EPC
  61        reg_t    vaddr;          CP0 BadVAddr
  62        reg_t    regs[32];       General registers
  63        reg_t    mdlo;           LO
  64        reg_t    mdhi;           HI
  65        reg_t    mdex;           ACX
  66        ...
  67      };
  68   */
  69
  70   stack_addr = get_frame_register_signed (this_frame,
  71                                           gdbarch_sp_regnum (gdbarch));
  72   switch (abi)
  73     {
  74     case MIPS_ABI_O32:
  75       /* 40: XCPTCONTEXT
  76          24: xcpt_gen() argspace                (16 bytes)
  77          16: _xcptcall() saved ra, rounded up   ( 8 bytes)
  78          00: _xcptcall() argspace               (16 bytes)  */
  79       xcpt_frame = stack_addr + 40;
  80       break;
  81     case MIPS_ABI_N32:
  82     case MIPS_ABI_N64:
  83     default:                    /* Wild guess.  */
  84       /* 16: XCPTCONTEXT
  85          16: xcpt_gen() argspace                ( 0 bytes)
  86          00: _xcptcall() saved ra, rounded up   (16 bytes)  */
  87       xcpt_frame = stack_addr + 16;
  88       break;
  89     }
  90
  91   trad_frame_set_reg_addr (cache,
  92                            MIPS_PS_REGNUM + gdbarch_num_regs (gdbarch),
  93                            xcpt_frame + 0 * sizeof_reg_t);
  94   trad_frame_set_reg_addr (cache,
  95                            regs->cause + gdbarch_num_regs (gdbarch),
  96                            xcpt_frame + 1 * sizeof_reg_t);
  97   trad_frame_set_reg_addr (cache,
  98                            regs->pc + gdbarch_num_regs (gdbarch),
  99                            xcpt_frame + 2 * sizeof_reg_t);
 100   trad_frame_set_reg_addr (cache,
 101                            regs->badvaddr + gdbarch_num_regs (gdbarch),
 102                            xcpt_frame + 3 * sizeof_reg_t);
 103   for (i = 0; i < MIPS_NUMREGS; i++)
 104     trad_frame_set_reg_addr (cache,
 105                              i + MIPS_ZERO_REGNUM + gdbarch_num_regs (gdbarch),
 106                              xcpt_frame + (4 + i) * sizeof_reg_t);
 107   trad_frame_set_reg_addr (cache,
 108                            regs->lo + gdbarch_num_regs (gdbarch),
 109                            xcpt_frame + 36 * sizeof_reg_t);
 110   trad_frame_set_reg_addr (cache,
 111                            regs->hi + gdbarch_num_regs (gdbarch),
 112                            xcpt_frame + 37 * sizeof_reg_t);
 113
 114   pc = get_frame_pc (this_frame);
 115   find_pc_partial_function (pc, NULL, &start_addr, NULL);
 116   trad_frame_set_id (cache, frame_id_build (start_addr, stack_addr));
 117
 118   return cache;
 119 }
 120
 121 /* Implement the this_id function for the SDE frame unwinder.  */
 122
 123 static void
 124 mips_sde_frame_this_id (frame_info_ptr this_frame, void **this_cache,
 125                         struct frame_id *this_id)
 126 {
 127   struct trad_frame_cache *this_trad_cache
 128     = mips_sde_frame_cache (this_frame, this_cache);
 129
 130   trad_frame_get_id (this_trad_cache, this_id);
 131 }
 132
 133 /* Implement the prev_register function for the SDE frame unwinder.  */
 134
 135 static struct value *
 136 mips_sde_frame_prev_register (frame_info_ptr this_frame,
 137                               void **this_cache,
 138                               int prev_regnum)
 139 {
 140   struct trad_frame_cache *trad_cache
 141     = mips_sde_frame_cache (this_frame, this_cache);
 142
 143   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
 144 }
 145
 146 /* Implement the sniffer function for the SDE frame unwinder.  */
 147
 148 static int
 149 mips_sde_frame_sniffer (const struct frame_unwind *self,
 150                         frame_info_ptr this_frame,
 151                         void **this_cache)
 152 {
 153   CORE_ADDR pc = get_frame_pc (this_frame);
 154   const char *name;
 155
 156   find_pc_partial_function (pc, &name, NULL, NULL);
 157   return (name
 158           && (strcmp (name, "_xcptcall") == 0
 159               || strcmp (name, "_sigtramp") == 0));
 160 }
 161
 162 /* Data structure for the SDE frame unwinder.  */
 163
 164 static const struct frame_unwind mips_sde_frame_unwind =
 165 {
 166   "mips sde sigtramp",
 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 (frame_info_ptr 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 (frame_info_ptr 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   for (asection *sect : gdb_bfd_sections (abfd))
 230     generic_elf_osabi_sniff_abi_tag_sections (abfd, sect, &osabi);
 231   if (osabi != GDB_OSABI_UNKNOWN)
 232     return GDB_OSABI_UNKNOWN;
 233
 234   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 235
 236   if (elfosabi == ELFOSABI_NONE)
 237     {
 238       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
 239          file are conforming to the base specification for that machine
 240          (there are no OS-specific extensions).  In order to determine the
 241          real OS in use we must look for OS notes that have been added.
 242
 243          For SDE, we simply look for sections named with .sde as prefixes.  */
 244       bfd_map_over_sections (abfd,
 245                              mips_sde_elf_osabi_sniff_abi_tag_sections,
 246                              &osabi);
 247     }
 248   return osabi;
 249 }
 250
 251 static void
 252 mips_sde_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 253 {
 254   frame_unwind_append_unwinder (gdbarch, &mips_sde_frame_unwind);
 255   frame_base_append_sniffer (gdbarch, mips_sde_frame_base_sniffer);
 256 }
 257
 258 void _initialize_mips_sde_tdep ();
 259 void
 260 _initialize_mips_sde_tdep ()
 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 }