gdb/sparc-obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/sparc.
   2
   3    Copyright (C) 2004-2020 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 "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
  29 #include "obsd-tdep.h"
  30 #include "sparc-tdep.h"
  31 #include "solib-svr4.h"
  32 #include "bsd-uthread.h"
  33 #include "gdbarch.h"
  34
  35 /* Signal trampolines.  */
  36
  37 /* The OpenBSD kernel maps the signal trampoline at some random
  38    location in user space, which means that the traditional BSD way of
  39    detecting it won't work.
  40
  41    The signal trampoline will be mapped at an address that is page
  42    aligned.  We recognize the signal trampoline by looking for the
  43    sigreturn system call.  */
  44
  45 static const int sparc32obsd_page_size = 4096;
  46
  47 static int
  48 sparc32obsd_pc_in_sigtramp (CORE_ADDR pc, const char *name)
  49 {
  50   CORE_ADDR start_pc = (pc & ~(sparc32obsd_page_size - 1));
  51   unsigned long insn;
  52
  53   if (name)
  54     return 0;
  55
  56   /* Check for "restore %g0, SYS_sigreturn, %g1".  */
  57   insn = sparc_fetch_instruction (start_pc + 0xec);
  58   if (insn != 0x83e82067)
  59     return 0;
  60
  61   /* Check for "t ST_SYSCALL".  */
  62   insn = sparc_fetch_instruction (start_pc + 0xf4);
  63   if (insn != 0x91d02000)
  64     return 0;
  65
  66   return 1;
  67 }
  68
  69 static struct sparc_frame_cache *
  70 sparc32obsd_sigtramp_frame_cache (struct frame_info *this_frame,
  71                                   void **this_cache)
  72 {
  73   struct sparc_frame_cache *cache;
  74   CORE_ADDR addr;
  75
  76   if (*this_cache)
  77     return (struct sparc_frame_cache *) *this_cache;
  78
  79   cache = sparc_frame_cache (this_frame, this_cache);
  80   gdb_assert (cache == *this_cache);
  81
  82   /* If we couldn't find the frame's function, we're probably dealing
  83      with an on-stack signal trampoline.  */
  84   if (cache->pc == 0)
  85     {
  86       cache->pc = get_frame_pc (this_frame);
  87       cache->pc &= ~(sparc32obsd_page_size - 1);
  88
  89       /* Since we couldn't find the frame's function, the cache was
  90          initialized under the assumption that we're frameless.  */
  91       sparc_record_save_insn (cache);
  92       addr = get_frame_register_unsigned (this_frame, SPARC_FP_REGNUM);
  93       cache->base = addr;
  94     }
  95
  96   cache->saved_regs = sparc32nbsd_sigcontext_saved_regs (this_frame);
  97
  98   return cache;
  99 }
 100
 101 static void
 102 sparc32obsd_sigtramp_frame_this_id (struct frame_info *this_frame,
 103                                     void **this_cache,
 104                                     struct frame_id *this_id)
 105 {
 106   struct sparc_frame_cache *cache =
 107     sparc32obsd_sigtramp_frame_cache (this_frame, this_cache);
 108
 109   (*this_id) = frame_id_build (cache->base, cache->pc);
 110 }
 111
 112 static struct value *
 113 sparc32obsd_sigtramp_frame_prev_register (struct frame_info *this_frame,
 114                                           void **this_cache, int regnum)
 115 {
 116   struct sparc_frame_cache *cache =
 117     sparc32obsd_sigtramp_frame_cache (this_frame, this_cache);
 118
 119   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 120 }
 121
 122 static int
 123 sparc32obsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
 124                                     struct frame_info *this_frame,
 125                                     void **this_cache)
 126 {
 127   CORE_ADDR pc = get_frame_pc (this_frame);
 128   const char *name;
 129
 130   find_pc_partial_function (pc, &name, NULL, NULL);
 131   if (sparc32obsd_pc_in_sigtramp (pc, name))
 132     return 1;
 133
 134   return 0;
 135 }
 136 static const struct frame_unwind sparc32obsd_sigtramp_frame_unwind =
 137 {
 138   SIGTRAMP_FRAME,
 139   default_frame_unwind_stop_reason,
 140   sparc32obsd_sigtramp_frame_this_id,
 141   sparc32obsd_sigtramp_frame_prev_register,
 142   NULL,
 143   sparc32obsd_sigtramp_frame_sniffer
 144 };
 145
 146 \f
 147
 148 /* Offset wthin the thread structure where we can find %fp and %i7.  */
 149 #define SPARC32OBSD_UTHREAD_FP_OFFSET   128
 150 #define SPARC32OBSD_UTHREAD_PC_OFFSET   132
 151
 152 static void
 153 sparc32obsd_supply_uthread (struct regcache *regcache,
 154                             int regnum, CORE_ADDR addr)
 155 {
 156   struct gdbarch *gdbarch = regcache->arch ();
 157   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 158   CORE_ADDR fp, fp_addr = addr + SPARC32OBSD_UTHREAD_FP_OFFSET;
 159   gdb_byte buf[4];
 160
 161   gdb_assert (regnum >= -1);
 162
 163   fp = read_memory_unsigned_integer (fp_addr, 4, byte_order);
 164   if (regnum == SPARC_SP_REGNUM || regnum == -1)
 165     {
 166       store_unsigned_integer (buf, 4, byte_order, fp);
 167       regcache->raw_supply (SPARC_SP_REGNUM, buf);
 168
 169       if (regnum == SPARC_SP_REGNUM)
 170         return;
 171     }
 172
 173   if (regnum == SPARC32_PC_REGNUM || regnum == SPARC32_NPC_REGNUM
 174       || regnum == -1)
 175     {
 176       CORE_ADDR i7, i7_addr = addr + SPARC32OBSD_UTHREAD_PC_OFFSET;
 177
 178       i7 = read_memory_unsigned_integer (i7_addr, 4, byte_order);
 179       if (regnum == SPARC32_PC_REGNUM || regnum == -1)
 180         {
 181           store_unsigned_integer (buf, 4, byte_order, i7 + 8);
 182           regcache->raw_supply (SPARC32_PC_REGNUM, buf);
 183         }
 184       if (regnum == SPARC32_NPC_REGNUM || regnum == -1)
 185         {
 186           store_unsigned_integer (buf, 4, byte_order, i7 + 12);
 187           regcache->raw_supply (SPARC32_NPC_REGNUM, buf);
 188         }
 189
 190       if (regnum == SPARC32_PC_REGNUM || regnum == SPARC32_NPC_REGNUM)
 191         return;
 192     }
 193
 194   sparc_supply_rwindow (regcache, fp, regnum);
 195 }
 196
 197 static void
 198 sparc32obsd_collect_uthread(const struct regcache *regcache,
 199                             int regnum, CORE_ADDR addr)
 200 {
 201   struct gdbarch *gdbarch = regcache->arch ();
 202   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 203   CORE_ADDR sp;
 204   gdb_byte buf[4];
 205
 206   gdb_assert (regnum >= -1);
 207
 208   if (regnum == SPARC_SP_REGNUM || regnum == -1)
 209     {
 210       CORE_ADDR fp_addr = addr + SPARC32OBSD_UTHREAD_FP_OFFSET;
 211
 212       regcache->raw_collect (SPARC_SP_REGNUM, buf);
 213       write_memory (fp_addr,buf, 4);
 214     }
 215
 216   if (regnum == SPARC32_PC_REGNUM || regnum == -1)
 217     {
 218       CORE_ADDR i7, i7_addr = addr + SPARC32OBSD_UTHREAD_PC_OFFSET;
 219
 220       regcache->raw_collect (SPARC32_PC_REGNUM, buf);
 221       i7 = extract_unsigned_integer (buf, 4, byte_order) - 8;
 222       write_memory_unsigned_integer (i7_addr, 4, byte_order, i7);
 223
 224       if (regnum == SPARC32_PC_REGNUM)
 225         return;
 226     }
 227
 228   regcache->raw_collect (SPARC_SP_REGNUM, buf);
 229   sp = extract_unsigned_integer (buf, 4, byte_order);
 230   sparc_collect_rwindow (regcache, sp, regnum);
 231 }
 232 \f
 233
 234 static void
 235 sparc32obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 236 {
 237   /* OpenBSD/sparc is very similar to NetBSD/sparc ELF.  */
 238   sparc32nbsd_init_abi (info, gdbarch);
 239
 240   set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
 241
 242   frame_unwind_append_unwinder (gdbarch, &sparc32obsd_sigtramp_frame_unwind);
 243
 244   /* OpenBSD provides a user-level threads implementation.  */
 245   bsd_uthread_set_supply_uthread (gdbarch, sparc32obsd_supply_uthread);
 246   bsd_uthread_set_collect_uthread (gdbarch, sparc32obsd_collect_uthread);
 247 }
 248
 249 void _initialize_sparc32obsd_tdep ();
 250 void
 251 _initialize_sparc32obsd_tdep ()
 252 {
 253   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_OPENBSD,
 254                           sparc32obsd_init_abi);
 255 }