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
  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 the 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, 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_frame_cache (struct frame_info *next_frame, void **this_cache)
  71 {
  72   struct sparc_frame_cache *cache;
  73   CORE_ADDR addr;
  74
  75   if (*this_cache)
  76     return *this_cache;
  77
  78   cache = sparc_frame_cache (next_frame, this_cache);
  79   gdb_assert (cache == *this_cache);
  80
  81   /* If we couldn't find the frame's function, we're probably dealing
  82      with an on-stack signal trampoline.  */
  83   if (cache->pc == 0)
  84     {
  85       cache->pc = frame_pc_unwind (next_frame);
  86       cache->pc &= ~(sparc32obsd_page_size - 1);
  87
  88       /* Since we couldn't find the frame's function, the cache was
  89          initialized under the assumption that we're frameless.  */
  90       cache->frameless_p = 0;
  91       addr = frame_unwind_register_unsigned (next_frame, SPARC_FP_REGNUM);
  92       cache->base = addr;
  93     }
  94
  95   cache->saved_regs = sparc32nbsd_sigcontext_saved_regs (next_frame);
  96
  97   return cache;
  98 }
  99
 100 static void
 101 sparc32obsd_frame_this_id (struct frame_info *next_frame, void **this_cache,
 102                            struct frame_id *this_id)
 103 {
 104   struct sparc_frame_cache *cache =
 105     sparc32obsd_frame_cache (next_frame, this_cache);
 106
 107   (*this_id) = frame_id_build (cache->base, cache->pc);
 108 }
 109
 110 static void
 111 sparc32obsd_frame_prev_register (struct frame_info *next_frame,
 112                                  void **this_cache,
 113                                  int regnum, int *optimizedp,
 114                                  enum lval_type *lvalp, CORE_ADDR *addrp,
 115                                  int *realnump, gdb_byte *valuep)
 116 {
 117   struct sparc_frame_cache *cache =
 118     sparc32obsd_frame_cache (next_frame, this_cache);
 119
 120   trad_frame_get_prev_register (next_frame, cache->saved_regs, regnum,
 121                                 optimizedp, lvalp, addrp, realnump, valuep);
 122 }
 123
 124 static const struct frame_unwind sparc32obsd_frame_unwind =
 125 {
 126   SIGTRAMP_FRAME,
 127   sparc32obsd_frame_this_id,
 128   sparc32obsd_frame_prev_register
 129 };
 130
 131 static const struct frame_unwind *
 132 sparc32obsd_sigtramp_frame_sniffer (struct frame_info *next_frame)
 133 {
 134   CORE_ADDR pc = frame_pc_unwind (next_frame);
 135   char *name;
 136
 137   find_pc_partial_function (pc, &name, NULL, NULL);
 138   if (sparc32obsd_pc_in_sigtramp (pc, name))
 139     return &sparc32obsd_frame_unwind;
 140
 141   return NULL;
 142 }
 143 \f
 144
 145 static void
 146 sparc32obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 147 {
 148   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 149
 150   /* OpenBSD/sparc is very similar to NetBSD/sparc ELF.  */
 151   sparc32nbsd_elf_init_abi (info, gdbarch);
 152
 153   frame_unwind_append_sniffer (gdbarch, sparc32obsd_sigtramp_frame_sniffer);
 154 }
 155
 156 \f
 157 /* Provide a prototype to silence -Wmissing-prototypes.  */
 158 void _initialize_sparc32obsd_tdep (void);
 159
 160 void
 161 _initialize_sparc32obsd_tdep (void)
 162 {
 163   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_OPENBSD_ELF,
 164                           sparc32obsd_init_abi);
 165 }