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
   4    Free Software Foundation, 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., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #include "server.h"
  24 #include "linux-low.h"
  25
  26 #include <sys/ptrace.h>
  27
  28 #include "gdb_proc_service.h"
  29
  30 #ifndef PTRACE_GET_THREAD_AREA
  31 #define PTRACE_GET_THREAD_AREA 22
  32 #endif
  33
  34 #ifdef HAVE_SYS_REG_H
  35 #include <sys/reg.h>
  36 #endif
  37
  38 #define arm_num_regs 26
  39
  40 static int arm_regmap[] = {
  41   0, 4, 8, 12, 16, 20, 24, 28,
  42   32, 36, 40, 44, 48, 52, 56, 60,
  43   -1, -1, -1, -1, -1, -1, -1, -1, -1,
  44   64
  45 };
  46
  47 static int
  48 arm_cannot_store_register (int regno)
  49 {
  50   return (regno >= arm_num_regs);
  51 }
  52
  53 static int
  54 arm_cannot_fetch_register (int regno)
  55 {
  56   return (regno >= arm_num_regs);
  57 }
  58
  59 extern int debug_threads;
  60
  61 static CORE_ADDR
  62 arm_get_pc ()
  63 {
  64   unsigned long pc;
  65   collect_register_by_name ("pc", &pc);
  66   if (debug_threads)
  67     fprintf (stderr, "stop pc is %08lx\n", pc);
  68   return pc;
  69 }
  70
  71 static void
  72 arm_set_pc (CORE_ADDR pc)
  73 {
  74   unsigned long newpc = pc;
  75   supply_register_by_name ("pc", &newpc);
  76 }
  77
  78 /* Correct in either endianness.  We do not support Thumb yet.  */
  79 static const unsigned long arm_breakpoint = 0xef9f0001;
  80 #define arm_breakpoint_len 4
  81
  82 /* For new EABI binaries.  We recognize it regardless of which ABI
  83    is used for gdbserver, so single threaded debugging should work
  84    OK, but for multi-threaded debugging we only insert the current
  85    ABI's breakpoint instruction.  For now at least.  */
  86 static const unsigned long arm_eabi_breakpoint = 0xe7f001f0;
  87
  88 static int
  89 arm_breakpoint_at (CORE_ADDR where)
  90 {
  91   unsigned long insn;
  92
  93   (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
  94   if (insn == arm_breakpoint)
  95     return 1;
  96
  97   if (insn == arm_eabi_breakpoint)
  98     return 1;
  99
 100   /* If necessary, recognize more trap instructions here.  GDB only uses the
 101      two.  */
 102
 103   return 0;
 104 }
 105
 106 /* We only place breakpoints in empty marker functions, and thread locking
 107    is outside of the function.  So rather than importing software single-step,
 108    we can just run until exit.  */
 109 static CORE_ADDR
 110 arm_reinsert_addr ()
 111 {
 112   unsigned long pc;
 113   collect_register_by_name ("lr", &pc);
 114   return pc;
 115 }
 116
 117 /* Fetch the thread-local storage pointer for libthread_db.  */
 118
 119 ps_err_e
 120 ps_get_thread_area (const struct ps_prochandle *ph,
 121                     lwpid_t lwpid, int idx, void **base)
 122 {
 123   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
 124     return PS_ERR;
 125
 126   /* IDX is the bias from the thread pointer to the beginning of the
 127      thread descriptor.  It has to be subtracted due to implementation
 128      quirks in libthread_db.  */
 129   *base = (void *) ((char *)*base - idx);
 130
 131   return PS_OK;
 132 }
 133
 134 struct linux_target_ops the_low_target = {
 135   arm_num_regs,
 136   arm_regmap,
 137   arm_cannot_fetch_register,
 138   arm_cannot_store_register,
 139   arm_get_pc,
 140   arm_set_pc,
 141 #ifndef __ARM_EABI__
 142   (const unsigned char *) &arm_breakpoint,
 143 #else
 144   (const unsigned char *) &arm_eabi_breakpoint,
 145 #endif
 146   arm_breakpoint_len,
 147   arm_reinsert_addr,
 148   0,
 149   arm_breakpoint_at,
 150 };