gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright 2003, 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 "gdbcore.h"
  25 #include "symtab.h"
  26 #include "objfiles.h"
  27 #include "osabi.h"
  28 #include "regset.h"
  29 #include "target.h"
  30
  31 #include "gdb_assert.h"
  32 #include "gdb_string.h"
  33
  34 #include "amd64-tdep.h"
  35 #include "i387-tdep.h"
  36 #include "solib-svr4.h"
  37
  38 /* Support for core dumps.  */
  39
  40 static void
  41 amd64obsd_supply_regset (const struct regset *regset,
  42                          struct regcache *regcache, int regnum,
  43                          const void *regs, size_t len)
  44 {
  45   const struct gdbarch_tdep *tdep = regset->descr;
  46
  47   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  48
  49   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  50   amd64_supply_fxsave (regcache, regnum, (char *)regs + tdep->sizeof_gregset);
  51 }
  52
  53 static const struct regset *
  54 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  55                                     const char *sect_name, size_t sect_size)
  56 {
  57   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  58
  59   /* OpenBSD core dumps don't use seperate register sets for the
  60      general-purpose and floating-point registers.  */
  61
  62   if (strcmp (sect_name, ".reg") == 0
  63       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  64     {
  65       if (tdep->gregset == NULL)
  66         tdep->gregset = regset_alloc (gdbarch, tdep,
  67                                       amd64obsd_supply_regset, NULL);
  68       return tdep->gregset;
  69     }
  70
  71   return NULL;
  72 }
  73 \f
  74
  75 /* Support for signal handlers.  */
  76
  77 /* Default page size.  */
  78 static const int amd64obsd_page_size = 4096;
  79
  80 /* Return whether the frame preceding NEXT_FRAME corresponds to an
  81    OpenBSD sigtramp routine.  */
  82
  83 static int
  84 amd64obsd_sigtramp_p (struct frame_info *next_frame)
  85 {
  86   CORE_ADDR pc = frame_pc_unwind (next_frame);
  87   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  88   const char sigreturn[] =
  89   {
  90     0x48, 0xc7, 0xc0,
  91     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  92     0xcd, 0x80                  /* int $0x80 */
  93   };
  94   char *name, *buf;
  95
  96   /* If the function has a valid symbol name, it isn't a
  97      trampoline.  */
  98   find_pc_partial_function (pc, &name, NULL, NULL);
  99   if (name != NULL)
 100     return 0;
 101
 102   /* If the function lives in a valid section (even without a starting
 103      point) it isn't a trampoline.  */
 104   if (find_pc_section (pc) != NULL)
 105     return 0;
 106
 107   /* If we can't read the instructions at START_PC, return zero.  */
 108   buf = alloca (sizeof sigreturn);
 109   if (target_read_memory (start_pc + 7, buf, sizeof sigreturn))
 110     return 0;
 111
 112   /* Check for sigreturn(2).  */
 113   if (memcmp (buf, sigreturn, sizeof sigreturn))
 114     return 0;
 115
 116   return 1;
 117 }
 118
 119 /* Assuming NEXT_FRAME is for a frame following a BSD sigtramp
 120    routine, return the address of the associated sigcontext structure.  */
 121
 122 static CORE_ADDR
 123 amd64obsd_sigcontext_addr (struct frame_info *next_frame)
 124 {
 125   CORE_ADDR pc = frame_pc_unwind (next_frame);
 126   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 127
 128   /* The %rsp register points at `struct sigcontext' upon entry of a
 129      signal trampoline.  The relevant part of the trampoline is
 130
 131         call    *%rax
 132         movq    %rsp, %rdi
 133         pushq   %rdi
 134         movq    $SYS_sigreturn,%rax
 135         int     $0x80
 136
 137      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 138      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 139
 140   if (offset > 6)
 141     return frame_unwind_register_unsigned (next_frame, AMD64_RDI_REGNUM);
 142   else
 143     return frame_unwind_register_unsigned (next_frame, AMD64_RSP_REGNUM);
 144 }
 145 \f
 146 /* OpenBSD 3.5 or later.  */
 147
 148 /* Mapping between the general-purpose registers in `struct reg'
 149    format and GDB's register cache layout.  */
 150
 151 /* From <machine/reg.h>.  */
 152 int amd64obsd_r_reg_offset[] =
 153 {
 154   14 * 8,                       /* %rax */
 155   13 * 8,                       /* %rbx */
 156   3 * 8,                        /* %rcx */
 157   2 * 8,                        /* %rdx */
 158   1 * 8,                        /* %rsi */
 159   0 * 8,                        /* %rdi */
 160   12 * 8,                       /* %rbp */
 161   15 * 8,                       /* %rsp */
 162   4 * 8,                        /* %r8 .. */
 163   5 * 8,
 164   6 * 8,
 165   7 * 8,
 166   8 * 8,
 167   9 * 8,
 168   10 * 8,
 169   11 * 8,                       /* ... %r15 */
 170   16 * 8,                       /* %rip */
 171   17 * 8,                       /* %eflags */
 172   18 * 8,                       /* %cs */
 173   19 * 8,                       /* %ss */
 174   20 * 8,                       /* %ds */
 175   21 * 8,                       /* %es */
 176   22 * 8,                       /* %fs */
 177   23 * 8                        /* %gs */
 178 };
 179
 180 /* From <machine/signal.h>.  */
 181 static int amd64obsd_sc_reg_offset[] =
 182 {
 183   14 * 8,                       /* %rax */
 184   13 * 8,                       /* %rbx */
 185   3 * 8,                        /* %rcx */
 186   2 * 8,                        /* %rdx */
 187   1 * 8,                        /* %rsi */
 188   0 * 8,                        /* %rdi */
 189   12 * 8,                       /* %rbp */
 190   24 * 8,                       /* %rsp */
 191   4 * 8,                        /* %r8 ... */
 192   5 * 8,
 193   6 * 8,
 194   7 * 8,
 195   8 * 8,
 196   9 * 8,
 197   10 * 8,
 198   11 * 8,                       /* ... %r15 */
 199   21 * 8,                       /* %rip */
 200   23 * 8,                       /* %eflags */
 201   22 * 8,                       /* %cs */
 202   25 * 8,                       /* %ss */
 203   18 * 8,                       /* %ds */
 204   17 * 8,                       /* %es */
 205   16 * 8,                       /* %fs */
 206   15 * 8                        /* %gs */
 207 };
 208
 209 static void
 210 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 211 {
 212   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 213
 214   amd64_init_abi (info, gdbarch);
 215
 216   /* Initialize general-purpose register set details.  */
 217   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 218   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 219   tdep->sizeof_gregset = 24 * 8;
 220
 221   set_gdbarch_regset_from_core_section (gdbarch,
 222                                         amd64obsd_regset_from_core_section);
 223
 224   tdep->jb_pc_offset = 7 * 8;
 225
 226   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 227   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 228   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 229   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 230
 231   /* OpenBSD uses SVR4-style shared libraries.  */
 232   set_solib_svr4_fetch_link_map_offsets
 233     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 234 }
 235 \f
 236
 237 /* Provide a prototype to silence -Wmissing-prototypes.  */
 238 void _initialize_amd64obsd_tdep (void);
 239
 240 void
 241 _initialize_amd64obsd_tdep (void)
 242 {
 243   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 244   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 245
 246   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 247                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 248
 249   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 250   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 251                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 252 }