gdb/sparc64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/sparc64.
   2
   3    Copyright 2004 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., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, 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 "solib-svr4.h"
  29 #include "trad-frame.h"
  30
  31 #include "gdb_assert.h"
  32
  33 #include "sparc64-tdep.h"
  34 #include "nbsd-tdep.h"
  35
  36 /* OpenBSD uses the traditional NetBSD core file format, even for
  37    ports that use ELF.  The core files don't use multiple register
  38    sets.  Instead, the general-purpose and floating-point registers
  39    are lumped together in a single section.  Unlike on NetBSD, OpenBSD
  40    uses a different layout for its general-purpose registers than the
  41    layout used for ptrace(2).  */
  42
  43 /* From <machine/reg.h>.  */
  44 const struct sparc_gregset sparc64obsd_core_gregset =
  45 {
  46   0 * 8,                        /* "tstate" */
  47   1 * 8,                        /* %pc */
  48   2 * 8,                        /* %npc */
  49   3 * 8,                        /* %y */
  50   -1,                           /* %fprs */
  51   -1,
  52   7 * 8,                        /* %g1 */
  53   22 * 8,                       /* %l0 */
  54   4                             /* sizeof (%y) */
  55 };
  56
  57 static void
  58 sparc64obsd_supply_gregset (const struct regset *regset,
  59                             struct regcache *regcache,
  60                             int regnum, const void *gregs, size_t len)
  61 {
  62   const char *regs = gregs;
  63
  64   sparc64_supply_gregset (&sparc64obsd_core_gregset, regcache, regnum, regs);
  65   sparc64_supply_fpregset (regcache, regnum, regs + 288);
  66 }
  67 \f
  68
  69 /* Signal trampolines.  */
  70
  71 /* The OpenBSD kernel maps the signal trampoline at some random
  72    location in user space, which means that the traditional BSD way of
  73    detecting it won't work.
  74
  75    The signal trampoline will be mapped at an address that is page
  76    aligned.  We recognize the signal trampoline by the looking for the
  77    sigreturn system call.  The offset where we can find the code that
  78    makes this system call varies from release to release.  For OpenBSD
  79    3.6 and later releases we can find the code at offset 0xec.  For
  80    OpenBSD 3.5 and earlier releases, we find it at offset 0xe8.  */
  81
  82 static const int sparc64obsd_page_size = 8192;
  83 static const int sparc64obsd_sigreturn_offset[] = { 0xec, 0xe8, -1 };
  84
  85 static int
  86 sparc64obsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
  87 {
  88   CORE_ADDR start_pc = (pc & ~(sparc64obsd_page_size - 1));
  89   unsigned long insn;
  90   const int *offset;
  91
  92   if (name)
  93     return 0;
  94
  95   for (offset = sparc64obsd_sigreturn_offset; *offset != -1; offset++)
  96     {
  97       /* Check for "restore %g0, SYS_sigreturn, %g1".  */
  98       insn = sparc_fetch_instruction (start_pc + *offset);
  99       if (insn != 0x83e82067)
 100         continue;
 101
 102       /* Check for "t ST_SYSCALL".  */
 103       insn = sparc_fetch_instruction (start_pc + *offset + 8);
 104       if (insn != 0x91d02000)
 105         continue;
 106
 107       return 1;
 108     }
 109
 110   return 0;
 111 }
 112
 113 static struct sparc_frame_cache *
 114 sparc64obsd_frame_cache (struct frame_info *next_frame, void **this_cache)
 115 {
 116   struct sparc_frame_cache *cache;
 117   CORE_ADDR addr;
 118
 119   if (*this_cache)
 120     return *this_cache;
 121
 122   cache = sparc_frame_cache (next_frame, this_cache);
 123   gdb_assert (cache == *this_cache);
 124
 125   /* If we couldn't find the frame's function, we're probably dealing
 126      with an on-stack signal trampoline.  */
 127   if (cache->pc == 0)
 128     {
 129       cache->pc = frame_pc_unwind (next_frame);
 130       cache->pc &= ~(sparc64obsd_page_size - 1);
 131
 132       /* Since we couldn't find the frame's function, the cache was
 133          initialized under the assumption that we're frameless.  */
 134       cache->frameless_p = 0;
 135       addr = frame_unwind_register_unsigned (next_frame, SPARC_FP_REGNUM);
 136       cache->base = addr;
 137     }
 138
 139   /* We find the appropriate instance of `struct sigcontext' at a
 140      fixed offset in the signal frame.  */
 141   addr = cache->base + BIAS + 128 + 16;
 142   cache->saved_regs = sparc64nbsd_sigcontext_saved_regs (addr, next_frame);
 143
 144   return cache;
 145 }
 146
 147 static void
 148 sparc64obsd_frame_this_id (struct frame_info *next_frame, void **this_cache,
 149                            struct frame_id *this_id)
 150 {
 151   struct sparc_frame_cache *cache =
 152     sparc64obsd_frame_cache (next_frame, this_cache);
 153
 154   (*this_id) = frame_id_build (cache->base, cache->pc);
 155 }
 156
 157 static void
 158 sparc64obsd_frame_prev_register (struct frame_info *next_frame,
 159                                  void **this_cache,
 160                                  int regnum, int *optimizedp,
 161                                  enum lval_type *lvalp, CORE_ADDR *addrp,
 162                                  int *realnump, void *valuep)
 163 {
 164   struct sparc_frame_cache *cache =
 165     sparc64obsd_frame_cache (next_frame, this_cache);
 166
 167   trad_frame_get_prev_register (next_frame, cache->saved_regs, regnum,
 168                                 optimizedp, lvalp, addrp, realnump, valuep);
 169 }
 170
 171 static const struct frame_unwind sparc64obsd_frame_unwind =
 172 {
 173   SIGTRAMP_FRAME,
 174   sparc64obsd_frame_this_id,
 175   sparc64obsd_frame_prev_register
 176 };
 177
 178 static const struct frame_unwind *
 179 sparc64obsd_sigtramp_frame_sniffer (struct frame_info *next_frame)
 180 {
 181   CORE_ADDR pc = frame_pc_unwind (next_frame);
 182   char *name;
 183
 184   find_pc_partial_function (pc, &name, NULL, NULL);
 185   if (sparc64obsd_pc_in_sigtramp (pc, name))
 186     return &sparc64obsd_frame_unwind;
 187
 188   return NULL;
 189 }
 190 \f
 191
 192 static void
 193 sparc64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 194 {
 195   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 196
 197   tdep->gregset = regset_alloc (gdbarch, sparc64obsd_supply_gregset, NULL);
 198   tdep->sizeof_gregset = 832;
 199
 200   frame_unwind_append_sniffer (gdbarch, sparc64obsd_sigtramp_frame_sniffer);
 201
 202   sparc64_init_abi (info, gdbarch);
 203
 204   set_solib_svr4_fetch_link_map_offsets
 205     (gdbarch, nbsd_lp64_solib_svr4_fetch_link_map_offsets);
 206 }
 207
 208 \f
 209 /* Provide a prototype to silence -Wmissing-prototypes.  */
 210 void _initialize_sparc64obsd_tdep (void);
 211
 212 void
 213 _initialize_sparc64obsd_tdep (void)
 214 {
 215   gdbarch_register_osabi (bfd_arch_sparc, bfd_mach_sparc_v9,
 216                           GDB_OSABI_OPENBSD_ELF, sparc64obsd_init_abi);
 217 }