gdb/gdbserver/linux-arm-low.c

   1 /* GNU/Linux/ARM specific low level interface, for the remote server for GDB.
   2    Copyright (C) 1995, 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   3    2006, 2007 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., 51 Franklin Street, Fifth Floor,
  20    Boston, MA 02110-1301, USA.  */
  21
  22 #include "server.h"
  23 #include "linux-low.h"
  24
  25 #include <sys/ptrace.h>
  26
  27 #include "gdb_proc_service.h"
  28
  29 #ifndef PTRACE_GET_THREAD_AREA
  30 #define PTRACE_GET_THREAD_AREA 22
  31 #endif
  32
  33 #ifdef HAVE_SYS_REG_H
  34 #include <sys/reg.h>
  35 #endif
  36
  37 #define arm_num_regs 26
  38
  39 static int arm_regmap[] = {
  40   0, 4, 8, 12, 16, 20, 24, 28,
  41   32, 36, 40, 44, 48, 52, 56, 60,
  42   -1, -1, -1, -1, -1, -1, -1, -1, -1,
  43   64
  44 };
  45
  46 static int
  47 arm_cannot_store_register (int regno)
  48 {
  49   return (regno >= arm_num_regs);
  50 }
  51
  52 static int
  53 arm_cannot_fetch_register (int regno)
  54 {
  55   return (regno >= arm_num_regs);
  56 }
  57
  58 extern int debug_threads;
  59
  60 static CORE_ADDR
  61 arm_get_pc ()
  62 {
  63   unsigned long pc;
  64   collect_register_by_name ("pc", &pc);
  65   if (debug_threads)
  66     fprintf (stderr, "stop pc is %08lx\n", pc);
  67   return pc;
  68 }
  69
  70 static void
  71 arm_set_pc (CORE_ADDR pc)
  72 {
  73   unsigned long newpc = pc;
  74   supply_register_by_name ("pc", &newpc);
  75 }
  76
  77 /* Correct in either endianness.  We do not support Thumb yet.  */
  78 static const unsigned long arm_breakpoint = 0xef9f0001;
  79 #define arm_breakpoint_len 4
  80
  81 /* For new EABI binaries.  We recognize it regardless of which ABI
  82    is used for gdbserver, so single threaded debugging should work
  83    OK, but for multi-threaded debugging we only insert the current
  84    ABI's breakpoint instruction.  For now at least.  */
  85 static const unsigned long arm_eabi_breakpoint = 0xe7f001f0;
  86
  87 static int
  88 arm_breakpoint_at (CORE_ADDR where)
  89 {
  90   unsigned long insn;
  91
  92   (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
  93   if (insn == arm_breakpoint)
  94     return 1;
  95
  96   if (insn == arm_eabi_breakpoint)
  97     return 1;
  98
  99   /* If necessary, recognize more trap instructions here.  GDB only uses the
 100      two.  */
 101
 102   return 0;
 103 }
 104
 105 /* We only place breakpoints in empty marker functions, and thread locking
 106    is outside of the function.  So rather than importing software single-step,
 107    we can just run until exit.  */
 108 static CORE_ADDR
 109 arm_reinsert_addr ()
 110 {
 111   unsigned long pc;
 112   collect_register_by_name ("lr", &pc);
 113   return pc;
 114 }
 115
 116 /* Fetch the thread-local storage pointer for libthread_db.  */
 117
 118 ps_err_e
 119 ps_get_thread_area (const struct ps_prochandle *ph,
 120                     lwpid_t lwpid, int idx, void **base)
 121 {
 122   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
 123     return PS_ERR;
 124
 125   /* IDX is the bias from the thread pointer to the beginning of the
 126      thread descriptor.  It has to be subtracted due to implementation
 127      quirks in libthread_db.  */
 128   *base = (void *) ((char *)*base - idx);
 129
 130   return PS_OK;
 131 }
 132
 133 struct linux_target_ops the_low_target = {
 134   arm_num_regs,
 135   arm_regmap,
 136   arm_cannot_fetch_register,
 137   arm_cannot_store_register,
 138   arm_get_pc,
 139   arm_set_pc,
 140 #ifndef __ARM_EABI__
 141   (const unsigned char *) &arm_breakpoint,
 142 #else
 143   (const unsigned char *) &arm_eabi_breakpoint,
 144 #endif
 145   arm_breakpoint_len,
 146   arm_reinsert_addr,
 147   0,
 148   arm_breakpoint_at,
 149 };