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 = gdbarch_tdep (regset->arch);
  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, 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   size_t buflen = (sizeof sigreturn) + 1;
  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) + 1);
 109   if (!safe_frame_unwind_memory (next_frame, start_pc + 6, buf, buflen))
 110     return 0;
 111
 112   /* Check for sigreturn(2).  Depending on how the assembler encoded
 113      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 114      7.  */
 115   if (memcmp (buf, sigreturn, sizeof sigreturn)
 116       && memcpy (buf + 1, sigreturn, sizeof sigreturn))
 117     return 0;
 118
 119   return 1;
 120 }
 121
 122 /* Assuming NEXT_FRAME is for a frame following a BSD sigtramp
 123    routine, return the address of the associated sigcontext structure.  */
 124
 125 static CORE_ADDR
 126 amd64obsd_sigcontext_addr (struct frame_info *next_frame)
 127 {
 128   CORE_ADDR pc = frame_pc_unwind (next_frame);
 129   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 130
 131   /* The %rsp register points at `struct sigcontext' upon entry of a
 132      signal trampoline.  The relevant part of the trampoline is
 133
 134         call    *%rax
 135         movq    %rsp, %rdi
 136         pushq   %rdi
 137         movq    $SYS_sigreturn,%rax
 138         int     $0x80
 139
 140      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 141      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 142
 143   if (offset > 5)
 144     return frame_unwind_register_unsigned (next_frame, AMD64_RDI_REGNUM);
 145   else
 146     return frame_unwind_register_unsigned (next_frame, AMD64_RSP_REGNUM);
 147 }
 148 \f
 149 /* OpenBSD 3.5 or later.  */
 150
 151 /* Mapping between the general-purpose registers in `struct reg'
 152    format and GDB's register cache layout.  */
 153
 154 /* From <machine/reg.h>.  */
 155 int amd64obsd_r_reg_offset[] =
 156 {
 157   14 * 8,                       /* %rax */
 158   13 * 8,                       /* %rbx */
 159   3 * 8,                        /* %rcx */
 160   2 * 8,                        /* %rdx */
 161   1 * 8,                        /* %rsi */
 162   0 * 8,                        /* %rdi */
 163   12 * 8,                       /* %rbp */
 164   15 * 8,                       /* %rsp */
 165   4 * 8,                        /* %r8 .. */
 166   5 * 8,
 167   6 * 8,
 168   7 * 8,
 169   8 * 8,
 170   9 * 8,
 171   10 * 8,
 172   11 * 8,                       /* ... %r15 */
 173   16 * 8,                       /* %rip */
 174   17 * 8,                       /* %eflags */
 175   18 * 8,                       /* %cs */
 176   19 * 8,                       /* %ss */
 177   20 * 8,                       /* %ds */
 178   21 * 8,                       /* %es */
 179   22 * 8,                       /* %fs */
 180   23 * 8                        /* %gs */
 181 };
 182
 183 /* From <machine/signal.h>.  */
 184 static int amd64obsd_sc_reg_offset[] =
 185 {
 186   14 * 8,                       /* %rax */
 187   13 * 8,                       /* %rbx */
 188   3 * 8,                        /* %rcx */
 189   2 * 8,                        /* %rdx */
 190   1 * 8,                        /* %rsi */
 191   0 * 8,                        /* %rdi */
 192   12 * 8,                       /* %rbp */
 193   24 * 8,                       /* %rsp */
 194   4 * 8,                        /* %r8 ... */
 195   5 * 8,
 196   6 * 8,
 197   7 * 8,
 198   8 * 8,
 199   9 * 8,
 200   10 * 8,
 201   11 * 8,                       /* ... %r15 */
 202   21 * 8,                       /* %rip */
 203   23 * 8,                       /* %eflags */
 204   22 * 8,                       /* %cs */
 205   25 * 8,                       /* %ss */
 206   18 * 8,                       /* %ds */
 207   17 * 8,                       /* %es */
 208   16 * 8,                       /* %fs */
 209   15 * 8                        /* %gs */
 210 };
 211
 212 static void
 213 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 214 {
 215   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 216
 217   amd64_init_abi (info, gdbarch);
 218
 219   /* Initialize general-purpose register set details.  */
 220   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 221   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 222   tdep->sizeof_gregset = 24 * 8;
 223
 224   set_gdbarch_regset_from_core_section (gdbarch,
 225                                         amd64obsd_regset_from_core_section);
 226
 227   tdep->jb_pc_offset = 7 * 8;
 228
 229   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 230   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 231   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 232   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 233
 234   /* OpenBSD uses SVR4-style shared libraries.  */
 235   set_solib_svr4_fetch_link_map_offsets
 236     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 237 }
 238 \f
 239
 240 /* Provide a prototype to silence -Wmissing-prototypes.  */
 241 void _initialize_amd64obsd_tdep (void);
 242
 243 void
 244 _initialize_amd64obsd_tdep (void)
 245 {
 246   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 247   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 248
 249   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 250                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 251
 252   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 253   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 254                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 255 }