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