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, 2008, 2009, 2010 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 3 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, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "server.h"
  21 #include "linux-low.h"
  22
  23 #include <elf.h>
  24 #include <sys/ptrace.h>
  25
  26 #include "gdb_proc_service.h"
  27
  28 /* Defined in auto-generated files.  */
  29 void init_registers_arm (void);
  30 void init_registers_arm_with_iwmmxt (void);
  31 void init_registers_arm_with_vfpv2 (void);
  32 void init_registers_arm_with_vfpv3 (void);
  33 void init_registers_arm_with_neon (void);
  34
  35 #ifndef PTRACE_GET_THREAD_AREA
  36 #define PTRACE_GET_THREAD_AREA 22
  37 #endif
  38
  39 #ifndef PTRACE_GETWMMXREGS
  40 # define PTRACE_GETWMMXREGS 18
  41 # define PTRACE_SETWMMXREGS 19
  42 #endif
  43
  44 #ifndef PTRACE_GETVFPREGS
  45 # define PTRACE_GETVFPREGS 27
  46 # define PTRACE_SETVFPREGS 28
  47 #endif
  48
  49 static unsigned long arm_hwcap;
  50
  51 /* These are in <asm/elf.h> in current kernels.  */
  52 #define HWCAP_VFP       64
  53 #define HWCAP_IWMMXT    512
  54 #define HWCAP_NEON      4096
  55 #define HWCAP_VFPv3     8192
  56 #define HWCAP_VFPv3D16  16384
  57
  58 #ifdef HAVE_SYS_REG_H
  59 #include <sys/reg.h>
  60 #endif
  61
  62 #define arm_num_regs 26
  63
  64 static int arm_regmap[] = {
  65   0, 4, 8, 12, 16, 20, 24, 28,
  66   32, 36, 40, 44, 48, 52, 56, 60,
  67   -1, -1, -1, -1, -1, -1, -1, -1, -1,
  68   64
  69 };
  70
  71 static int
  72 arm_cannot_store_register (int regno)
  73 {
  74   return (regno >= arm_num_regs);
  75 }
  76
  77 static int
  78 arm_cannot_fetch_register (int regno)
  79 {
  80   return (regno >= arm_num_regs);
  81 }
  82
  83 static void
  84 arm_fill_gregset (void *buf)
  85 {
  86   int i;
  87
  88   for (i = 0; i < arm_num_regs; i++)
  89     if (arm_regmap[i] != -1)
  90       collect_register (i, ((char *) buf) + arm_regmap[i]);
  91 }
  92
  93 static void
  94 arm_store_gregset (const void *buf)
  95 {
  96   int i;
  97   char zerobuf[8];
  98
  99   memset (zerobuf, 0, 8);
 100   for (i = 0; i < arm_num_regs; i++)
 101     if (arm_regmap[i] != -1)
 102       supply_register (i, ((char *) buf) + arm_regmap[i]);
 103     else
 104       supply_register (i, zerobuf);
 105 }
 106
 107 static void
 108 arm_fill_wmmxregset (void *buf)
 109 {
 110   int i;
 111
 112   if (!(arm_hwcap & HWCAP_IWMMXT))
 113     return;
 114
 115   for (i = 0; i < 16; i++)
 116     collect_register (arm_num_regs + i, (char *) buf + i * 8);
 117
 118   /* We only have access to wcssf, wcasf, and wcgr0-wcgr3.  */
 119   for (i = 0; i < 6; i++)
 120     collect_register (arm_num_regs + i + 16, (char *) buf + 16 * 8 + i * 4);
 121 }
 122
 123 static void
 124 arm_store_wmmxregset (const void *buf)
 125 {
 126   int i;
 127
 128   if (!(arm_hwcap & HWCAP_IWMMXT))
 129     return;
 130
 131   for (i = 0; i < 16; i++)
 132     supply_register (arm_num_regs + i, (char *) buf + i * 8);
 133
 134   /* We only have access to wcssf, wcasf, and wcgr0-wcgr3.  */
 135   for (i = 0; i < 6; i++)
 136     supply_register (arm_num_regs + i + 16, (char *) buf + 16 * 8 + i * 4);
 137 }
 138
 139 static void
 140 arm_fill_vfpregset (void *buf)
 141 {
 142   int i, num, base;
 143
 144   if (!(arm_hwcap & HWCAP_VFP))
 145     return;
 146
 147   if ((arm_hwcap & (HWCAP_VFPv3 | HWCAP_VFPv3D16)) == HWCAP_VFPv3)
 148     num = 32;
 149   else
 150     num = 16;
 151
 152   base = find_regno ("d0");
 153   for (i = 0; i < num; i++)
 154     collect_register (base + i, (char *) buf + i * 8);
 155
 156   collect_register_by_name ("fpscr", (char *) buf + 32 * 8);
 157 }
 158
 159 static void
 160 arm_store_vfpregset (const void *buf)
 161 {
 162   int i, num, base;
 163
 164   if (!(arm_hwcap & HWCAP_VFP))
 165     return;
 166
 167   if ((arm_hwcap & (HWCAP_VFPv3 | HWCAP_VFPv3D16)) == HWCAP_VFPv3)
 168     num = 32;
 169   else
 170     num = 16;
 171
 172   base = find_regno ("d0");
 173   for (i = 0; i < num; i++)
 174     supply_register (base + i, (char *) buf + i * 8);
 175
 176   supply_register_by_name ("fpscr", (char *) buf + 32 * 8);
 177 }
 178
 179 extern int debug_threads;
 180
 181 static CORE_ADDR
 182 arm_get_pc ()
 183 {
 184   unsigned long pc;
 185   collect_register_by_name ("pc", &pc);
 186   if (debug_threads)
 187     fprintf (stderr, "stop pc is %08lx\n", pc);
 188   return pc;
 189 }
 190
 191 static void
 192 arm_set_pc (CORE_ADDR pc)
 193 {
 194   unsigned long newpc = pc;
 195   supply_register_by_name ("pc", &newpc);
 196 }
 197
 198 /* Correct in either endianness.  */
 199 static const unsigned long arm_breakpoint = 0xef9f0001;
 200 #define arm_breakpoint_len 4
 201 static const unsigned short thumb_breakpoint = 0xde01;
 202 #define thumb_breakpoint_len 2
 203
 204 /* For new EABI binaries.  We recognize it regardless of which ABI
 205    is used for gdbserver, so single threaded debugging should work
 206    OK, but for multi-threaded debugging we only insert the current
 207    ABI's breakpoint instruction.  For now at least.  */
 208 static const unsigned long arm_eabi_breakpoint = 0xe7f001f0;
 209
 210 static int
 211 arm_breakpoint_at (CORE_ADDR where)
 212 {
 213   unsigned long cpsr;
 214
 215   collect_register_by_name ("cpsr", &cpsr);
 216
 217   if (cpsr & 0x20)
 218     {
 219       /* Thumb mode.  */
 220       unsigned short insn;
 221
 222       (*the_target->read_memory) (where, (unsigned char *) &insn, 2);
 223       if (insn == thumb_breakpoint)
 224         return 1;
 225     }
 226   else
 227     {
 228       /* ARM mode.  */
 229       unsigned long insn;
 230
 231       (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
 232       if (insn == arm_breakpoint)
 233         return 1;
 234
 235       if (insn == arm_eabi_breakpoint)
 236         return 1;
 237     }
 238
 239   return 0;
 240 }
 241
 242 /* We only place breakpoints in empty marker functions, and thread locking
 243    is outside of the function.  So rather than importing software single-step,
 244    we can just run until exit.  */
 245 static CORE_ADDR
 246 arm_reinsert_addr ()
 247 {
 248   unsigned long pc;
 249   collect_register_by_name ("lr", &pc);
 250   return pc;
 251 }
 252
 253 /* Fetch the thread-local storage pointer for libthread_db.  */
 254
 255 ps_err_e
 256 ps_get_thread_area (const struct ps_prochandle *ph,
 257                     lwpid_t lwpid, int idx, void **base)
 258 {
 259   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
 260     return PS_ERR;
 261
 262   /* IDX is the bias from the thread pointer to the beginning of the
 263      thread descriptor.  It has to be subtracted due to implementation
 264      quirks in libthread_db.  */
 265   *base = (void *) ((char *)*base - idx);
 266
 267   return PS_OK;
 268 }
 269
 270 static int
 271 arm_get_hwcap (unsigned long *valp)
 272 {
 273   unsigned char *data = alloca (8);
 274   int offset = 0;
 275
 276   while ((*the_target->read_auxv) (offset, data, 8) == 8)
 277     {
 278       unsigned int *data_p = (unsigned int *)data;
 279       if (data_p[0] == AT_HWCAP)
 280         {
 281           *valp = data_p[1];
 282           return 1;
 283         }
 284
 285       offset += 8;
 286     }
 287
 288   *valp = 0;
 289   return 0;
 290 }
 291
 292 static void
 293 arm_arch_setup (void)
 294 {
 295   arm_hwcap = 0;
 296   if (arm_get_hwcap (&arm_hwcap) == 0)
 297     {
 298       init_registers_arm ();
 299       return;
 300     }
 301
 302   if (arm_hwcap & HWCAP_IWMMXT)
 303     {
 304       init_registers_arm_with_iwmmxt ();
 305       return;
 306     }
 307
 308   if (arm_hwcap & HWCAP_VFP)
 309     {
 310       int pid;
 311       char *buf;
 312
 313       /* NEON implies either no VFP, or VFPv3-D32.  We only support
 314          it with VFP.  */
 315       if (arm_hwcap & HWCAP_NEON)
 316         init_registers_arm_with_neon ();
 317       else if ((arm_hwcap & (HWCAP_VFPv3 | HWCAP_VFPv3D16)) == HWCAP_VFPv3)
 318         init_registers_arm_with_vfpv3 ();
 319       else
 320         init_registers_arm_with_vfpv2 ();
 321
 322       /* Now make sure that the kernel supports reading these
 323          registers.  Support was added in 2.6.30.  */
 324       pid = lwpid_of (get_thread_lwp (current_inferior));
 325       errno = 0;
 326       buf = malloc (32 * 8 + 4);
 327       if (ptrace (PTRACE_GETVFPREGS, pid, 0, buf) < 0
 328           && errno == EIO)
 329         {
 330           arm_hwcap = 0;
 331           init_registers_arm ();
 332         }
 333       free (buf);
 334
 335       return;
 336     }
 337
 338   /* The default configuration uses legacy FPA registers, probably
 339      simulated.  */
 340   init_registers_arm ();
 341 }
 342
 343 struct regset_info target_regsets[] = {
 344   { PTRACE_GETREGS, PTRACE_SETREGS, 18 * 4,
 345     GENERAL_REGS,
 346     arm_fill_gregset, arm_store_gregset },
 347   { PTRACE_GETWMMXREGS, PTRACE_SETWMMXREGS, 16 * 8 + 6 * 4,
 348     EXTENDED_REGS,
 349     arm_fill_wmmxregset, arm_store_wmmxregset },
 350   { PTRACE_GETVFPREGS, PTRACE_SETVFPREGS, 32 * 8 + 4,
 351     EXTENDED_REGS,
 352     arm_fill_vfpregset, arm_store_vfpregset },
 353   { 0, 0, -1, -1, NULL, NULL }
 354 };
 355
 356 struct linux_target_ops the_low_target = {
 357   arm_arch_setup,
 358   arm_num_regs,
 359   arm_regmap,
 360   arm_cannot_fetch_register,
 361   arm_cannot_store_register,
 362   arm_get_pc,
 363   arm_set_pc,
 364
 365   /* Define an ARM-mode breakpoint; we only set breakpoints in the C
 366      library, which is most likely to be ARM.  If the kernel supports
 367      clone events, we will never insert a breakpoint, so even a Thumb
 368      C library will work; so will mixing EABI/non-EABI gdbserver and
 369      application.  */
 370 #ifndef __ARM_EABI__
 371   (const unsigned char *) &arm_breakpoint,
 372 #else
 373   (const unsigned char *) &arm_eabi_breakpoint,
 374 #endif
 375   arm_breakpoint_len,
 376   arm_reinsert_addr,
 377   0,
 378   arm_breakpoint_at,
 379 };