gdb/sparc-obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/sparc.
   2
   3    Copyright (C) 2004-2021 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 "frame.h"
  22 #include "frame-unwind.h"
  23 #include "gdbcore.h"
  24 #include "osabi.h"
  25 #include "regcache.h"
  26 #include "symtab.h"
  27 #include "trad-frame.h"
  28 #include "inferior.h"
  29
  30 #include "obsd-tdep.h"
  31 #include "sparc-tdep.h"
  32 #include "solib-svr4.h"
  33 #include "bsd-uthread.h"
  34 #include "gdbarch.h"
  35
  36 /* Signal trampolines.  */
  37
  38 /* The OpenBSD kernel maps the signal trampoline at some random
  39    location in user space, which means that the traditional BSD way of
  40    detecting it won't work.
  41
  42    The signal trampoline will be mapped at an address that is page
  43    aligned.  We recognize the signal trampoline by looking for the
  44    sigreturn system call.  */
  45
  46 static const int sparc32obsd_page_size = 4096;
  47
  48 static int
  49 sparc32obsd_pc_in_sigtramp (CORE_ADDR pc, const char *name)
  50 {
  51   CORE_ADDR start_pc = (pc & ~(sparc32obsd_page_size - 1));
  52   unsigned long insn;
  53
  54   if (name)
  55     return 0;
  56
  57   /* Check for "restore %g0, SYS_sigreturn, %g1".  */
  58   insn = sparc_fetch_instruction (start_pc + 0xec);
  59   if (insn != 0x83e82067)
  60     return 0;
  61
  62   /* Check for "t ST_SYSCALL".  */
  63   insn = sparc_fetch_instruction (start_pc + 0xf4);
  64   if (insn != 0x91d02000)
  65     return 0;
  66
  67   return 1;
  68 }
  69
  70 static struct sparc_frame_cache *
  71 sparc32obsd_sigtramp_frame_cache (struct frame_info *this_frame,
  72                                   void **this_cache)
  73 {
  74   struct sparc_frame_cache *cache;
  75   CORE_ADDR addr;
  76
  77   if (*this_cache)
  78     return (struct sparc_frame_cache *) *this_cache;
  79
  80   cache = sparc_frame_cache (this_frame, this_cache);
  81   gdb_assert (cache == *this_cache);
  82
  83   /* If we couldn't find the frame's function, we're probably dealing
  84      with an on-stack signal trampoline.  */
  85   if (cache->pc == 0)
  86     {
  87       cache->pc = get_frame_pc (this_frame);
  88       cache->pc &= ~(sparc32obsd_page_size - 1);
  89
  90       /* Since we couldn't find the frame's function, the cache was
  91          initialized under the assumption that we're frameless.  */
  92       sparc_record_save_insn (cache);
  93       addr = get_frame_register_unsigned (this_frame, SPARC_FP_REGNUM);
  94       cache->base = addr;
  95     }
  96
  97   cache->saved_regs = sparc32nbsd_sigcontext_saved_regs (this_frame);
  98
  99   return cache;
 100 }
 101
 102 static void
 103 sparc32obsd_sigtramp_frame_this_id (struct frame_info *this_frame,
 104                                     void **this_cache,
 105                                     struct frame_id *this_id)
 106 {
 107   struct sparc_frame_cache *cache =
 108     sparc32obsd_sigtramp_frame_cache (this_frame, this_cache);
 109
 110   (*this_id) = frame_id_build (cache->base, cache->pc);
 111 }
 112
 113 static struct value *
 114 sparc32obsd_sigtramp_frame_prev_register (struct frame_info *this_frame,
 115                                           void **this_cache, int regnum)
 116 {
 117   struct sparc_frame_cache *cache =
 118     sparc32obsd_sigtramp_frame_cache (this_frame, this_cache);
 119
 120   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 121 }
 122
 123 static int
 124 sparc32obsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
 125                                     struct frame_info *this_frame,
 126                                     void **this_cache)
 127 {
 128   CORE_ADDR pc = get_frame_pc (this_frame);
 129   const char *name;
 130
 131   find_pc_partial_function (pc, &name, NULL, NULL);
 132   if (sparc32obsd_pc_in_sigtramp (pc, name))
 133     return 1;
 134
 135   return 0;
 136 }
 137 static const struct frame_unwind sparc32obsd_sigtramp_frame_unwind =
 138 {
 139   "sparc32 openbsd sigtramp",
 140   SIGTRAMP_FRAME,
 141   default_frame_unwind_stop_reason,
 142   sparc32obsd_sigtramp_frame_this_id,
 143   sparc32obsd_sigtramp_frame_prev_register,
 144   NULL,
 145   sparc32obsd_sigtramp_frame_sniffer
 146 };
 147
 148 \f
 149
 150 /* Offset wthin the thread structure where we can find %fp and %i7.  */
 151 #define SPARC32OBSD_UTHREAD_FP_OFFSET   128
 152 #define SPARC32OBSD_UTHREAD_PC_OFFSET   132
 153
 154 static void
 155 sparc32obsd_supply_uthread (struct regcache *regcache,
 156                             int regnum, CORE_ADDR addr)
 157 {
 158   struct gdbarch *gdbarch = regcache->arch ();
 159   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 160   CORE_ADDR fp, fp_addr = addr + SPARC32OBSD_UTHREAD_FP_OFFSET;
 161   gdb_byte buf[4];
 162
 163   /* This function calls functions that depend on the global current thread.  */
 164   gdb_assert (regcache->ptid () == inferior_ptid);
 165
 166   gdb_assert (regnum >= -1);
 167
 168   fp = read_memory_unsigned_integer (fp_addr, 4, byte_order);
 169   if (regnum == SPARC_SP_REGNUM || regnum == -1)
 170     {
 171       store_unsigned_integer (buf, 4, byte_order, fp);
 172       regcache->raw_supply (SPARC_SP_REGNUM, buf);
 173
 174       if (regnum == SPARC_SP_REGNUM)
 175         return;
 176     }
 177
 178   if (regnum == SPARC32_PC_REGNUM || regnum == SPARC32_NPC_REGNUM
 179       || regnum == -1)
 180     {
 181       CORE_ADDR i7, i7_addr = addr + SPARC32OBSD_UTHREAD_PC_OFFSET;
 182
 183       i7 = read_memory_unsigned_integer (i7_addr, 4, byte_order);
 184       if (regnum == SPARC32_PC_REGNUM || regnum == -1)
 185         {
 186           store_unsigned_integer (buf, 4, byte_order, i7 + 8);
 187           regcache->raw_supply (SPARC32_PC_REGNUM, buf);
 188         }
 189       if (regnum == SPARC32_NPC_REGNUM || regnum == -1)
 190         {
 191           store_unsigned_integer (buf, 4, byte_order, i7 + 12);
 192           regcache->raw_supply (SPARC32_NPC_REGNUM, buf);
 193         }
 194
 195       if (regnum == SPARC32_PC_REGNUM || regnum == SPARC32_NPC_REGNUM)
 196         return;
 197     }
 198
 199   sparc_supply_rwindow (regcache, fp, regnum);
 200 }
 201
 202 static void
 203 sparc32obsd_collect_uthread(const struct regcache *regcache,
 204                             int regnum, CORE_ADDR addr)
 205 {
 206   struct gdbarch *gdbarch = regcache->arch ();
 207   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 208   CORE_ADDR sp;
 209   gdb_byte buf[4];
 210
 211   /* This function calls functions that depend on the global current thread.  */
 212   gdb_assert (regcache->ptid () == inferior_ptid);
 213
 214   gdb_assert (regnum >= -1);
 215
 216   if (regnum == SPARC_SP_REGNUM || regnum == -1)
 217     {
 218       CORE_ADDR fp_addr = addr + SPARC32OBSD_UTHREAD_FP_OFFSET;
 219
 220       regcache->raw_collect (SPARC_SP_REGNUM, buf);
 221       write_memory (fp_addr,buf, 4);
 222     }
 223
 224   if (regnum == SPARC32_PC_REGNUM || regnum == -1)
 225     {
 226       CORE_ADDR i7, i7_addr = addr + SPARC32OBSD_UTHREAD_PC_OFFSET;
 227
 228       regcache->raw_collect (SPARC32_PC_REGNUM, buf);
 229       i7 = extract_unsigned_integer (buf, 4, byte_order) - 8;
 230       write_memory_unsigned_integer (i7_addr, 4, byte_order, i7);
 231
 232       if (regnum == SPARC32_PC_REGNUM)
 233         return;
 234     }
 235
 236   regcache->raw_collect (SPARC_SP_REGNUM, buf);
 237   sp = extract_unsigned_integer (buf, 4, byte_order);
 238   sparc_collect_rwindow (regcache, sp, regnum);
 239 }
 240 \f
 241
 242 static void
 243 sparc32obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 244 {
 245   /* OpenBSD/sparc is very similar to NetBSD/sparc ELF.  */
 246   sparc32nbsd_init_abi (info, gdbarch);
 247
 248   set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
 249
 250   frame_unwind_append_unwinder (gdbarch, &sparc32obsd_sigtramp_frame_unwind);
 251
 252   /* OpenBSD provides a user-level threads implementation.  */
 253   bsd_uthread_set_supply_uthread (gdbarch, sparc32obsd_supply_uthread);
 254   bsd_uthread_set_collect_uthread (gdbarch, sparc32obsd_collect_uthread);
 255 }
 256
 257 void _initialize_sparc32obsd_tdep ();
 258 void
 259 _initialize_sparc32obsd_tdep ()
 260 {
 261   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_OPENBSD,
 262                           sparc32obsd_init_abi);
 263 }