gdb/sparc64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/sparc64.
   2
   3    Copyright (C) 2004, 2005 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 2 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, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20    Boston, MA 02110-1301, USA.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "frame-unwind.h"
  25 #include "osabi.h"
  26 #include "regset.h"
  27 #include "symtab.h"
  28 #include "objfiles.h"
  29 #include "solib-svr4.h"
  30 #include "trad-frame.h"
  31
  32 #include "gdb_assert.h"
  33
  34 #include "obsd-tdep.h"
  35 #include "sparc64-tdep.h"
  36
  37 /* OpenBSD uses the traditional NetBSD core file format, even for
  38    ports that use ELF.  The core files don't use multiple register
  39    sets.  Instead, the general-purpose and floating-point registers
  40    are lumped together in a single section.  Unlike on NetBSD, OpenBSD
  41    uses a different layout for its general-purpose registers than the
  42    layout used for ptrace(2).  */
  43
  44 /* From <machine/reg.h>.  */
  45 const struct sparc_gregset sparc64obsd_core_gregset =
  46 {
  47   0 * 8,                        /* "tstate" */
  48   1 * 8,                        /* %pc */
  49   2 * 8,                        /* %npc */
  50   3 * 8,                        /* %y */
  51   -1,                           /* %fprs */
  52   -1,
  53   7 * 8,                        /* %g1 */
  54   22 * 8,                       /* %l0 */
  55   4                             /* sizeof (%y) */
  56 };
  57
  58 static void
  59 sparc64obsd_supply_gregset (const struct regset *regset,
  60                             struct regcache *regcache,
  61                             int regnum, const void *gregs, size_t len)
  62 {
  63   const char *regs = gregs;
  64
  65   sparc64_supply_gregset (&sparc64obsd_core_gregset, regcache, regnum, regs);
  66   sparc64_supply_fpregset (regcache, regnum, regs + 288);
  67 }
  68 \f
  69
  70 /* Signal trampolines.  */
  71
  72 /* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page
  73    in virtual memory.  The randomness makes it somewhat tricky to
  74    detect it, but fortunately we can rely on the fact that the start
  75    of the sigtramp routine is page-aligned.  We recognize the
  76    trampoline by looking for the code that invokes the sigreturn
  77    system call.  The offset where we can find that code varies from
  78    release to release.
  79
  80    By the way, the mapping mentioned above is read-only, so you cannot
  81    place a breakpoint in the signal trampoline.  */
  82
  83 /* Default page size.  */
  84 static const int sparc64obsd_page_size = 8192;
  85
  86 /* Offset for sigreturn(2).  */
  87 static const int sparc64obsd_sigreturn_offset[] = {
  88   0xf0,                         /* OpenBSD 3.8 */
  89   0xec,                         /* OpenBSD 3.6 */
  90   0xe8,                         /* OpenBSD 3.2 */
  91   -1
  92 };
  93
  94 static int
  95 sparc64obsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
  96 {
  97   CORE_ADDR start_pc = (pc & ~(sparc64obsd_page_size - 1));
  98   unsigned long insn;
  99   const int *offset;
 100
 101   if (name)
 102     return 0;
 103
 104   for (offset = sparc64obsd_sigreturn_offset; *offset != -1; offset++)
 105     {
 106       /* Check for "restore %g0, SYS_sigreturn, %g1".  */
 107       insn = sparc_fetch_instruction (start_pc + *offset);
 108       if (insn != 0x83e82067)
 109         continue;
 110
 111       /* Check for "t ST_SYSCALL".  */
 112       insn = sparc_fetch_instruction (start_pc + *offset + 8);
 113       if (insn != 0x91d02000)
 114         continue;
 115
 116       return 1;
 117     }
 118
 119   return 0;
 120 }
 121
 122 static struct sparc_frame_cache *
 123 sparc64obsd_frame_cache (struct frame_info *next_frame, void **this_cache)
 124 {
 125   struct sparc_frame_cache *cache;
 126   CORE_ADDR addr;
 127
 128   if (*this_cache)
 129     return *this_cache;
 130
 131   cache = sparc_frame_cache (next_frame, this_cache);
 132   gdb_assert (cache == *this_cache);
 133
 134   /* If we couldn't find the frame's function, we're probably dealing
 135      with an on-stack signal trampoline.  */
 136   if (cache->pc == 0)
 137     {
 138       cache->pc = frame_pc_unwind (next_frame);
 139       cache->pc &= ~(sparc64obsd_page_size - 1);
 140
 141       /* Since we couldn't find the frame's function, the cache was
 142          initialized under the assumption that we're frameless.  */
 143       cache->frameless_p = 0;
 144       addr = frame_unwind_register_unsigned (next_frame, SPARC_FP_REGNUM);
 145       if (addr & 1)
 146         addr += BIAS;
 147       cache->base = addr;
 148     }
 149
 150   /* We find the appropriate instance of `struct sigcontext' at a
 151      fixed offset in the signal frame.  */
 152   addr = cache->base + 128 + 16;
 153   cache->saved_regs = sparc64nbsd_sigcontext_saved_regs (addr, next_frame);
 154
 155   return cache;
 156 }
 157
 158 static void
 159 sparc64obsd_frame_this_id (struct frame_info *next_frame, void **this_cache,
 160                            struct frame_id *this_id)
 161 {
 162   struct sparc_frame_cache *cache =
 163     sparc64obsd_frame_cache (next_frame, this_cache);
 164
 165   (*this_id) = frame_id_build (cache->base, cache->pc);
 166 }
 167
 168 static void
 169 sparc64obsd_frame_prev_register (struct frame_info *next_frame,
 170                                  void **this_cache,
 171                                  int regnum, int *optimizedp,
 172                                  enum lval_type *lvalp, CORE_ADDR *addrp,
 173                                  int *realnump, gdb_byte *valuep)
 174 {
 175   struct sparc_frame_cache *cache =
 176     sparc64obsd_frame_cache (next_frame, this_cache);
 177
 178   trad_frame_get_prev_register (next_frame, cache->saved_regs, regnum,
 179                                 optimizedp, lvalp, addrp, realnump, valuep);
 180 }
 181
 182 static const struct frame_unwind sparc64obsd_frame_unwind =
 183 {
 184   SIGTRAMP_FRAME,
 185   sparc64obsd_frame_this_id,
 186   sparc64obsd_frame_prev_register
 187 };
 188
 189 static const struct frame_unwind *
 190 sparc64obsd_sigtramp_frame_sniffer (struct frame_info *next_frame)
 191 {
 192   CORE_ADDR pc = frame_pc_unwind (next_frame);
 193   char *name;
 194
 195   find_pc_partial_function (pc, &name, NULL, NULL);
 196   if (sparc64obsd_pc_in_sigtramp (pc, name))
 197     return &sparc64obsd_frame_unwind;
 198
 199   return NULL;
 200 }
 201 \f
 202
 203 static void
 204 sparc64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 205 {
 206   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 207
 208   tdep->gregset = regset_alloc (gdbarch, sparc64obsd_supply_gregset, NULL);
 209   tdep->sizeof_gregset = 832;
 210
 211   frame_unwind_append_sniffer (gdbarch, sparc64obsd_sigtramp_frame_sniffer);
 212
 213   sparc64_init_abi (info, gdbarch);
 214
 215   /* OpenBSD/sparc64 has SVR4-style shared libraries.  */
 216   set_solib_svr4_fetch_link_map_offsets
 217     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 218   set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
 219 }
 220 \f
 221
 222 /* Provide a prototype to silence -Wmissing-prototypes.  */
 223 void _initialize_sparc64obsd_tdep (void);
 224
 225 void
 226 _initialize_sparc64obsd_tdep (void)
 227 {
 228   gdbarch_register_osabi (bfd_arch_sparc, bfd_mach_sparc_v9,
 229                           GDB_OSABI_OPENBSD_ELF, sparc64obsd_init_abi);
 230 }