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