gdb/sparcobsd-tdep.c

   1 /* Target-dependent code for OpenBSD/sparc.
   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 "floatformat.h"
  24 #include "frame.h"
  25 #include "frame-unwind.h"
  26 #include "osabi.h"
  27 #include "solib-svr4.h"
  28 #include "symtab.h"
  29 #include "trad-frame.h"
  30
  31 #include "gdb_assert.h"
  32
  33 #include "sparc-tdep.h"
  34 #include "nbsd-tdep.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 the 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, 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_frame_cache (struct frame_info *next_frame, void **this_cache)
  72 {
  73   struct sparc_frame_cache *cache;
  74   CORE_ADDR addr;
  75
  76   if (*this_cache)
  77     return *this_cache;
  78
  79   cache = sparc_frame_cache (next_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 = frame_pc_unwind (next_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       cache->frameless_p = 0;
  92       addr = frame_unwind_register_unsigned (next_frame, SPARC_FP_REGNUM);
  93       cache->base = addr;
  94     }
  95
  96   cache->saved_regs = sparc32nbsd_sigcontext_saved_regs (next_frame);
  97
  98   return cache;
  99 }
 100
 101 static void
 102 sparc32obsd_frame_this_id (struct frame_info *next_frame, void **this_cache,
 103                            struct frame_id *this_id)
 104 {
 105   struct sparc_frame_cache *cache =
 106     sparc32obsd_frame_cache (next_frame, this_cache);
 107
 108   (*this_id) = frame_id_build (cache->base, cache->pc);
 109 }
 110
 111 static void
 112 sparc32obsd_frame_prev_register (struct frame_info *next_frame,
 113                                  void **this_cache,
 114                                  int regnum, int *optimizedp,
 115                                  enum lval_type *lvalp, CORE_ADDR *addrp,
 116                                  int *realnump, void *valuep)
 117 {
 118   struct sparc_frame_cache *cache =
 119     sparc32obsd_frame_cache (next_frame, this_cache);
 120
 121   trad_frame_get_prev_register (next_frame, cache->saved_regs, regnum,
 122                                 optimizedp, lvalp, addrp, realnump, valuep);
 123 }
 124
 125 static const struct frame_unwind sparc32obsd_frame_unwind =
 126 {
 127   SIGTRAMP_FRAME,
 128   sparc32obsd_frame_this_id,
 129   sparc32obsd_frame_prev_register
 130 };
 131
 132 static const struct frame_unwind *
 133 sparc32obsd_sigtramp_frame_sniffer (struct frame_info *next_frame)
 134 {
 135   CORE_ADDR pc = frame_pc_unwind (next_frame);
 136   char *name;
 137
 138   find_pc_partial_function (pc, &name, NULL, NULL);
 139   if (sparc32obsd_pc_in_sigtramp (pc, name))
 140     return &sparc32obsd_frame_unwind;
 141
 142   return NULL;
 143 }
 144 \f
 145
 146 static void
 147 sparc32obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 148 {
 149   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 150
 151   /* OpenBSD doesn't support the 128-bit `long double' from the psABI.  */
 152   set_gdbarch_long_double_bit (gdbarch, 64);
 153   set_gdbarch_long_double_format (gdbarch, &floatformat_ieee_double_big);
 154
 155   frame_unwind_append_sniffer (gdbarch, sparc32obsd_sigtramp_frame_sniffer);
 156
 157   set_solib_svr4_fetch_link_map_offsets
 158     (gdbarch, nbsd_ilp32_solib_svr4_fetch_link_map_offsets);
 159 }
 160
 161 \f
 162 /* Provide a prototype to silence -Wmissing-prototypes.  */
 163 void _initialize_sparc32obsd_tdep (void);
 164
 165 void
 166 _initialize_sparc32obsd_tdep (void)
 167 {
 168   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_OPENBSD_ELF,
 169                           sparc32obsd_init_abi);
 170 }