gdb/m68klinux-tdep.c

   1 /* Motorola m68k target-dependent support for GNU/Linux.
   2
   3    Copyright 1996, 1998, 2000, 2001, 2002, 2003 Free Software Foundation,
   4    Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "gdbcore.h"
  25 #include "frame.h"
  26 #include "target.h"
  27 #include "gdb_string.h"
  28 #include "gdbtypes.h"
  29 #include "osabi.h"
  30 #include "regcache.h"
  31 #include "objfiles.h"
  32 #include "symtab.h"
  33 #include "m68k-tdep.h"
  34 \f
  35 /* Offsets (in target ints) into jmp_buf.  */
  36
  37 #define M68K_LINUX_JB_ELEMENT_SIZE 4
  38 #define M68K_LINUX_JB_PC 7
  39
  40 /* Check whether insn1 and insn2 are parts of a signal trampoline.  */
  41
  42 #define IS_SIGTRAMP(insn1, insn2)                                       \
  43   (/* addaw #20,sp; moveq #119,d0; trap #0 */                           \
  44    (insn1 == 0xdefc0014 && insn2 == 0x70774e40)                         \
  45    /* moveq #119,d0; trap #0 */                                         \
  46    || insn1 == 0x70774e40)
  47
  48 #define IS_RT_SIGTRAMP(insn1, insn2)                                    \
  49   (/* movel #173,d0; trap #0 */                                         \
  50    (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)                         \
  51    /* moveq #82,d0; notb d0; trap #0 */                                 \
  52    || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
  53
  54 /* Return non-zero if PC points into the signal trampoline.  For the sake
  55    of m68k_linux_frame_saved_pc we also distinguish between non-RT and RT
  56    signal trampolines.  */
  57
  58 static int
  59 m68k_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
  60 {
  61   CORE_ADDR sp;
  62   char buf[12];
  63   unsigned long insn0, insn1, insn2;
  64
  65   if (read_memory_nobpt (pc - 4, buf, sizeof (buf)))
  66     return 0;
  67   insn1 = extract_unsigned_integer (buf + 4, 4);
  68   insn2 = extract_unsigned_integer (buf + 8, 4);
  69   if (IS_SIGTRAMP (insn1, insn2))
  70     return 1;
  71   if (IS_RT_SIGTRAMP (insn1, insn2))
  72     return 2;
  73
  74   insn0 = extract_unsigned_integer (buf, 4);
  75   if (IS_SIGTRAMP (insn0, insn1))
  76     return 1;
  77   if (IS_RT_SIGTRAMP (insn0, insn1))
  78     return 2;
  79
  80   insn0 = ((insn0 << 16) & 0xffffffff) | (insn1 >> 16);
  81   insn1 = ((insn1 << 16) & 0xffffffff) | (insn2 >> 16);
  82   if (IS_SIGTRAMP (insn0, insn1))
  83     return 1;
  84   if (IS_RT_SIGTRAMP (insn0, insn1))
  85     return 2;
  86
  87   return 0;
  88 }
  89
  90 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
  91 #define SIGCONTEXT_PC_OFFSET 26
  92
  93 /* Offset to saved PC in ucontext, from <asm/ucontext.h>.  */
  94 #define UCONTEXT_PC_OFFSET 88
  95
  96 /* Get saved user PC for sigtramp from sigcontext or ucontext.  */
  97
  98 static CORE_ADDR
  99 m68k_linux_sigtramp_saved_pc (struct frame_info *frame)
 100 {
 101   CORE_ADDR sigcontext_addr;
 102   char buf[TARGET_PTR_BIT / TARGET_CHAR_BIT];
 103   int ptrbytes = TARGET_PTR_BIT / TARGET_CHAR_BIT;
 104   int sigcontext_offs = (2 * TARGET_INT_BIT) / TARGET_CHAR_BIT;
 105
 106   /* Get sigcontext address, it is the third parameter on the stack.  */
 107   if (get_next_frame (frame))
 108     sigcontext_addr
 109       = read_memory_unsigned_integer (get_frame_base (get_next_frame (frame))
 110                                       + FRAME_ARGS_SKIP
 111                                       + sigcontext_offs,
 112                                       ptrbytes);
 113   else
 114     sigcontext_addr
 115       = read_memory_unsigned_integer (read_register (SP_REGNUM)
 116                                       + sigcontext_offs,
 117                                       ptrbytes);
 118
 119   /* Don't cause a memory_error when accessing sigcontext in case the
 120      stack layout has changed or the stack is corrupt.  */
 121   if (m68k_linux_pc_in_sigtramp (get_frame_pc (frame), 0) == 2)
 122     target_read_memory (sigcontext_addr + UCONTEXT_PC_OFFSET, buf, ptrbytes);
 123   else
 124     target_read_memory (sigcontext_addr + SIGCONTEXT_PC_OFFSET, buf, ptrbytes);
 125   return extract_unsigned_integer (buf, ptrbytes);
 126 }
 127
 128 /* Return the saved program counter for FRAME.  */
 129
 130 static CORE_ADDR
 131 m68k_linux_frame_saved_pc (struct frame_info *frame)
 132 {
 133   if (get_frame_type (frame) == SIGTRAMP_FRAME)
 134     return m68k_linux_sigtramp_saved_pc (frame);
 135
 136   return read_memory_unsigned_integer (get_frame_base (frame) + 4, 4);
 137 }
 138
 139 /* The following definitions are appropriate when using the ELF
 140    format, where floating point values are returned in fp0, pointer
 141    values in a0 and other values in d0.  */
 142
 143 /* Extract from an array REGBUF containing the (raw) register state a
 144    function return value of type TYPE, and copy that, in virtual
 145    format, into VALBUF.  */
 146
 147 static void
 148 m68k_linux_extract_return_value (struct type *type, char *regbuf, char *valbuf)
 149 {
 150   if (TYPE_CODE (type) == TYPE_CODE_FLT)
 151     {
 152        REGISTER_CONVERT_TO_VIRTUAL (FP0_REGNUM, type,
 153                                     regbuf + REGISTER_BYTE (FP0_REGNUM),
 154                                     valbuf);
 155     }
 156   else if (TYPE_CODE (type) == TYPE_CODE_PTR)
 157     memcpy (valbuf, regbuf + REGISTER_BYTE (M68K_A0_REGNUM),
 158             TYPE_LENGTH (type));
 159   else
 160     memcpy (valbuf,
 161             regbuf + (TYPE_LENGTH (type) >= 4 ? 0 : 4 - TYPE_LENGTH (type)),
 162             TYPE_LENGTH (type));
 163 }
 164
 165 /* Write into appropriate registers a function return value of type
 166    TYPE, given in virtual format.  */
 167
 168 static void
 169 m68k_linux_store_return_value (struct type *type, char *valbuf)
 170 {
 171   if (TYPE_CODE (type) == TYPE_CODE_FLT)
 172     {
 173       char raw_buffer[REGISTER_RAW_SIZE (FP0_REGNUM)];
 174       REGISTER_CONVERT_TO_RAW (type, FP0_REGNUM, valbuf, raw_buffer);
 175       deprecated_write_register_bytes (REGISTER_BYTE (FP0_REGNUM),
 176                                        raw_buffer, TYPE_LENGTH (type));
 177     }
 178   else
 179     {
 180       if (TYPE_CODE (type) == TYPE_CODE_PTR)
 181         deprecated_write_register_bytes (REGISTER_BYTE (M68K_A0_REGNUM),
 182                                          valbuf, TYPE_LENGTH (type));
 183       deprecated_write_register_bytes (0, valbuf, TYPE_LENGTH (type));
 184     }
 185 }
 186
 187 /* Extract from an array REGBUF containing the (raw) register state
 188    the address in which a function should return its structure value,
 189    as a CORE_ADDR.  */
 190
 191 static CORE_ADDR
 192 m68k_linux_extract_struct_value_address (char *regbuf)
 193 {
 194   return *(CORE_ADDR *) (regbuf + REGISTER_BYTE (M68K_A0_REGNUM));
 195 }
 196
 197 static void
 198 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 199 {
 200   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 201
 202   tdep->jb_pc = M68K_LINUX_JB_PC;
 203   tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
 204
 205   set_gdbarch_deprecated_frame_saved_pc (gdbarch,
 206                                          m68k_linux_frame_saved_pc);
 207   set_gdbarch_deprecated_extract_return_value (gdbarch,
 208                                                m68k_linux_extract_return_value);
 209   set_gdbarch_deprecated_store_return_value (gdbarch,
 210                                              m68k_linux_store_return_value);
 211   set_gdbarch_deprecated_extract_struct_value_address (gdbarch,
 212                                                        m68k_linux_extract_struct_value_address);
 213
 214   set_gdbarch_pc_in_sigtramp (gdbarch, m68k_linux_pc_in_sigtramp);
 215
 216   /* Shared library handling.  */
 217   set_gdbarch_in_solib_call_trampoline (gdbarch, in_plt_section);
 218   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 219 }
 220
 221 void
 222 _initialize_m68k_linux_tdep (void)
 223 {
 224   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 225                           m68k_linux_init_abi);
 226 }