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 "m68k-tdep.h"
  30 \f
  31 /* Check whether insn1 and insn2 are parts of a signal trampoline.  */
  32
  33 #define IS_SIGTRAMP(insn1, insn2)                                       \
  34   (/* addaw #20,sp; moveq #119,d0; trap #0 */                           \
  35    (insn1 == 0xdefc0014 && insn2 == 0x70774e40)                         \
  36    /* moveq #119,d0; trap #0 */                                         \
  37    || insn1 == 0x70774e40)
  38
  39 #define IS_RT_SIGTRAMP(insn1, insn2)                                    \
  40   (/* movel #173,d0; trap #0 */                                         \
  41    (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)                         \
  42    /* moveq #82,d0; notb d0; trap #0 */                                 \
  43    || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
  44
  45 /* Return non-zero if PC points into the signal trampoline.  For the sake
  46    of m68k_linux_frame_saved_pc we also distinguish between non-RT and RT
  47    signal trampolines.  */
  48
  49 int
  50 m68k_linux_in_sigtramp (CORE_ADDR pc)
  51 {
  52   CORE_ADDR sp;
  53   char buf[12];
  54   unsigned long insn0, insn1, insn2;
  55
  56   if (read_memory_nobpt (pc - 4, buf, sizeof (buf)))
  57     return 0;
  58   insn1 = extract_unsigned_integer (buf + 4, 4);
  59   insn2 = extract_unsigned_integer (buf + 8, 4);
  60   if (IS_SIGTRAMP (insn1, insn2))
  61     return 1;
  62   if (IS_RT_SIGTRAMP (insn1, insn2))
  63     return 2;
  64
  65   insn0 = extract_unsigned_integer (buf, 4);
  66   if (IS_SIGTRAMP (insn0, insn1))
  67     return 1;
  68   if (IS_RT_SIGTRAMP (insn0, insn1))
  69     return 2;
  70
  71   insn0 = (insn0 << 16) | (insn1 >> 16);
  72   insn1 = (insn1 << 16) | (insn2 >> 16);
  73   if (IS_SIGTRAMP (insn0, insn1))
  74     return 1;
  75   if (IS_RT_SIGTRAMP (insn0, insn1))
  76     return 2;
  77
  78   return 0;
  79 }
  80
  81 /* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
  82 #define SIGCONTEXT_PC_OFFSET 26
  83
  84 /* Offset to saved PC in ucontext, from <asm/ucontext.h>.  */
  85 #define UCONTEXT_PC_OFFSET 88
  86
  87 /* Get saved user PC for sigtramp from sigcontext or ucontext.  */
  88
  89 static CORE_ADDR
  90 m68k_linux_sigtramp_saved_pc (struct frame_info *frame)
  91 {
  92   CORE_ADDR sigcontext_addr;
  93   char buf[TARGET_PTR_BIT / TARGET_CHAR_BIT];
  94   int ptrbytes = TARGET_PTR_BIT / TARGET_CHAR_BIT;
  95   int sigcontext_offs = (2 * TARGET_INT_BIT) / TARGET_CHAR_BIT;
  96
  97   /* Get sigcontext address, it is the third parameter on the stack.  */
  98   if (get_next_frame (frame))
  99     sigcontext_addr
 100       = read_memory_unsigned_integer (get_frame_base (get_next_frame (frame))
 101                                       + FRAME_ARGS_SKIP
 102                                       + sigcontext_offs,
 103                                       ptrbytes);
 104   else
 105     sigcontext_addr
 106       = read_memory_unsigned_integer (read_register (SP_REGNUM)
 107                                       + sigcontext_offs,
 108                                       ptrbytes);
 109
 110   /* Don't cause a memory_error when accessing sigcontext in case the
 111      stack layout has changed or the stack is corrupt.  */
 112   if (m68k_linux_in_sigtramp (get_frame_pc (frame)) == 2)
 113     target_read_memory (sigcontext_addr + UCONTEXT_PC_OFFSET, buf, ptrbytes);
 114   else
 115     target_read_memory (sigcontext_addr + SIGCONTEXT_PC_OFFSET, buf, ptrbytes);
 116   return extract_unsigned_integer (buf, ptrbytes);
 117 }
 118
 119 /* Return the saved program counter for FRAME.  */
 120
 121 CORE_ADDR
 122 m68k_linux_frame_saved_pc (struct frame_info *frame)
 123 {
 124   if (get_frame_type (frame) == SIGTRAMP_FRAME)
 125     return m68k_linux_sigtramp_saved_pc (frame);
 126
 127   return read_memory_unsigned_integer (get_frame_base (frame) + 4, 4);
 128 }
 129
 130 void
 131 m68k_linux_extract_return_value (struct type *type, char *regbuf, char *valbuf)
 132 {
 133   if (TYPE_CODE (type) == TYPE_CODE_FLT)
 134     {
 135        REGISTER_CONVERT_TO_VIRTUAL (FP0_REGNUM, type,
 136                                     regbuf + REGISTER_BYTE (FP0_REGNUM),
 137                                     valbuf);
 138     }
 139   else if (TYPE_CODE (type) == TYPE_CODE_PTR)
 140     memcpy (valbuf, regbuf + REGISTER_BYTE (M68K_A0_REGNUM),
 141             TYPE_LENGTH (type));
 142   else
 143     memcpy (valbuf,
 144             regbuf + (TYPE_LENGTH (type) >= 4 ? 0 : 4 - TYPE_LENGTH (type)),
 145             TYPE_LENGTH (type));
 146 }
 147
 148 void
 149 m68k_linux_store_return_value (struct type *type, char *valbuf)
 150 {
 151   if (TYPE_CODE (type) == TYPE_CODE_FLT)
 152     {
 153       char raw_buffer[REGISTER_RAW_SIZE (FP0_REGNUM)];
 154       REGISTER_CONVERT_TO_RAW (type, FP0_REGNUM, valbuf, raw_buffer);
 155       deprecated_write_register_bytes (REGISTER_BYTE (FP0_REGNUM),
 156                                        raw_buffer, TYPE_LENGTH (type));
 157     }
 158   else
 159     {
 160       if (TYPE_CODE (type) == TYPE_CODE_PTR)
 161         deprecated_write_register_bytes (REGISTER_BYTE (M68K_A0_REGNUM),
 162                                          valbuf, TYPE_LENGTH (type));
 163       deprecated_write_register_bytes (0, valbuf, TYPE_LENGTH (type));
 164     }
 165 }
 166
 167 CORE_ADDR
 168 m68k_linux_extract_struct_value_address (char *regbuf)
 169 {
 170   return *(CORE_ADDR *) (regbuf + REGISTER_BYTE (M68K_A0_REGNUM));
 171 }