path: root/gdb/gdbserver/linux-mips-low.c

/* GNU/Linux/MIPS specific low level interface, for the remote server for GDB.
   Copyright (C) 1995-1996, 1998-2002, 2005-2012 Free Software
   Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "server.h"
#include "linux-low.h"

#include <sys/ptrace.h>
#include <endian.h>

#include "gdb_proc_service.h"

/* Defined in auto-generated file mips-linux.c.  */
void init_registers_mips_linux (void);
/* Defined in auto-generated file mips64-linux.c.  */
void init_registers_mips64_linux (void);

#ifndef PTRACE_GET_THREAD_AREA
#define PTRACE_GET_THREAD_AREA 25
#endif

#ifdef HAVE_SYS_REG_H
#include <sys/reg.h>
#endif

#define mips_num_regs 73

#include <asm/ptrace.h>

union mips_register
{
  unsigned char buf[8];

  /* Deliberately signed, for proper sign extension.  */
  int reg32;
  long long reg64;
};

/* Return the ptrace ``address'' of register REGNO. */

static int mips_regmap[] = {
  -1,  1,  2,  3,  4,  5,  6,  7,
  8,  9,  10, 11, 12, 13, 14, 15,
  16, 17, 18, 19, 20, 21, 22, 23,
  24, 25, 26, 27, 28, 29, 30, 31,

  -1, MMLO, MMHI, BADVADDR, CAUSE, PC,

  FPR_BASE,      FPR_BASE + 1,  FPR_BASE + 2,  FPR_BASE + 3,
  FPR_BASE + 4,  FPR_BASE + 5,  FPR_BASE + 6,  FPR_BASE + 7,
  FPR_BASE + 8,  FPR_BASE + 8,  FPR_BASE + 10, FPR_BASE + 11,
  FPR_BASE + 12, FPR_BASE + 13, FPR_BASE + 14, FPR_BASE + 15,
  FPR_BASE + 16, FPR_BASE + 17, FPR_BASE + 18, FPR_BASE + 19,
  FPR_BASE + 20, FPR_BASE + 21, FPR_BASE + 22, FPR_BASE + 23,
  FPR_BASE + 24, FPR_BASE + 25, FPR_BASE + 26, FPR_BASE + 27,
  FPR_BASE + 28, FPR_BASE + 29, FPR_BASE + 30, FPR_BASE + 31,
  FPC_CSR, FPC_EIR,

  0
};

/* From mips-linux-nat.c.  */

/* Pseudo registers can not be read.  ptrace does not provide a way to
   read (or set) PS_REGNUM, and there's no point in reading or setting
   ZERO_REGNUM.  We also can not set BADVADDR, CAUSE, or FCRIR via
   ptrace().  */

static int
mips_cannot_fetch_register (int regno)
{
  if (mips_regmap[regno] == -1)
    return 1;

  if (find_regno ("r0") == regno)
    return 1;

  return 0;
}

static int
mips_cannot_store_register (int regno)
{
  if (mips_regmap[regno] == -1)
    return 1;

  if (find_regno ("r0") == regno)
    return 1;

  if (find_regno ("cause") == regno)
    return 1;

  if (find_regno ("badvaddr") == regno)
    return 1;

  if (find_regno ("fir") == regno)
    return 1;

  return 0;
}

static CORE_ADDR
mips_get_pc (struct regcache *regcache)
{
  union mips_register pc;
  collect_register_by_name (regcache, "pc", pc.buf);
  return register_size (0) == 4 ? pc.reg32 : pc.reg64;
}

static void
mips_set_pc (struct regcache *regcache, CORE_ADDR pc)
{
  union mips_register newpc;
  if (register_size (0) == 4)
    newpc.reg32 = pc;
  else
    newpc.reg64 = pc;

  supply_register_by_name (regcache, "pc", newpc.buf);
}

/* Correct in either endianness.  */
static const unsigned int mips_breakpoint = 0x0005000d;
#define mips_breakpoint_len 4

/* We only place breakpoints in empty marker functions, and thread locking
   is outside of the function.  So rather than importing software single-step,
   we can just run until exit.  */
static CORE_ADDR
mips_reinsert_addr (void)
{
  struct regcache *regcache = get_thread_regcache (current_inferior, 1);
  union mips_register ra;
  collect_register_by_name (regcache, "r31", ra.buf);
  return register_size (0) == 4 ? ra.reg32 : ra.reg64;
}

static int
mips_breakpoint_at (CORE_ADDR where)
{
  unsigned int insn;

  (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
  if (insn == mips_breakpoint)
    return 1;

  /* If necessary, recognize more trap instructions here.  GDB only uses the
     one.  */
  return 0;
}

/* Fetch the thread-local storage pointer for libthread_db.  */

ps_err_e
ps_get_thread_area (const struct ps_prochandle *ph,
		    lwpid_t lwpid, int idx, void **base)
{
  if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
    return PS_ERR;

  /* IDX is the bias from the thread pointer to the beginning of the
     thread descriptor.  It has to be subtracted due to implementation
     quirks in libthread_db.  */
  *base = (void *) ((char *)*base - idx);

  return PS_OK;
}

#ifdef HAVE_PTRACE_GETREGS

static void
mips_collect_register (struct regcache *regcache,
		       int use_64bit, int regno, union mips_register *reg)
{
  union mips_register tmp_reg;

  if (use_64bit)
    {
      collect_register (regcache, regno, &tmp_reg.reg64);
      *reg = tmp_reg;
    }
  else
    {
      collect_register (regcache, regno, &tmp_reg.reg32);
      reg->reg64 = tmp_reg.reg32;
    }
}

static void
mips_supply_register (struct regcache *regcache,
		      int use_64bit, int regno, const union mips_register *reg)
{
  int offset = 0;

  /* For big-endian 32-bit targets, ignore the high four bytes of each
     eight-byte slot.  */
  if (__BYTE_ORDER == __BIG_ENDIAN && !use_64bit)
    offset = 4;

  supply_register (regcache, regno, reg->buf + offset);
}

static void
mips_collect_register_32bit (struct regcache *regcache,
			     int use_64bit, int regno, unsigned char *buf)
{
  union mips_register tmp_reg;
  int reg32;

  mips_collect_register (regcache, use_64bit, regno, &tmp_reg);
  reg32 = tmp_reg.reg64;
  memcpy (buf, &reg32, 4);
}

static void
mips_supply_register_32bit (struct regcache *regcache,
			    int use_64bit, int regno, const unsigned char *buf)
{
  union mips_register tmp_reg;
  int reg32;

  memcpy (&reg32, buf, 4);
  tmp_reg.reg64 = reg32;
  mips_supply_register (regcache, use_64bit, regno, &tmp_reg);
}

static void
mips_fill_gregset (struct regcache *regcache, void *buf)
{
  union mips_register *regset = buf;
  int i, use_64bit;

  use_64bit = (register_size (0) == 8);

  for (i = 1; i < 32; i++)
    mips_collect_register (regcache, use_64bit, i, regset + i);

  mips_collect_register (regcache, use_64bit,
			 find_regno ("lo"), regset + 32);
  mips_collect_register (regcache, use_64bit,
			 find_regno ("hi"), regset + 33);
  mips_collect_register (regcache, use_64bit,
			 find_regno ("pc"), regset + 34);
  mips_collect_register (regcache, use_64bit,
			 find_regno ("badvaddr"), regset + 35);
  mips_collect_register (regcache, use_64bit,
			 find_regno ("status"), regset + 36);
  mips_collect_register (regcache, use_64bit,
			 find_regno ("cause"), regset + 37);

  mips_collect_register (regcache, use_64bit,
			 find_regno ("restart"), regset + 0);
}

static void
mips_store_gregset (struct regcache *regcache, const void *buf)
{
  const union mips_register *regset = buf;
  int i, use_64bit;

  use_64bit = (register_size (0) == 8);

  for (i = 0; i < 32; i++)
    mips_supply_register (regcache, use_64bit, i, regset + i);

  mips_supply_register (regcache, use_64bit, find_regno ("lo"), regset + 32);
  mips_supply_register (regcache, use_64bit, find_regno ("hi"), regset + 33);
  mips_supply_register (regcache, use_64bit, find_regno ("pc"), regset + 34);
  mips_supply_register (regcache, use_64bit,
			find_regno ("badvaddr"), regset + 35);
  mips_supply_register (regcache, use_64bit,
			find_regno ("status"), regset + 36);
  mips_supply_register (regcache, use_64bit,
			find_regno ("cause"), regset + 37);

  mips_supply_register (regcache, use_64bit,
			find_regno ("restart"), regset + 0);
}

static void
mips_fill_fpregset (struct regcache *regcache, void *buf)
{
  union mips_register *regset = buf;
  int i, use_64bit, first_fp, big_endian;

  use_64bit = (register_size (0) == 8);
  first_fp = find_regno ("f0");
  big_endian = (__BYTE_ORDER == __BIG_ENDIAN);

  /* See GDB for a discussion of this peculiar layout.  */
  for (i = 0; i < 32; i++)
    if (use_64bit)
      collect_register (regcache, first_fp + i, regset[i].buf);
    else
      collect_register (regcache, first_fp + i,
			regset[i & ~1].buf + 4 * (big_endian != (i & 1)));

  mips_collect_register_32bit (regcache, use_64bit,
			       find_regno ("fcsr"), regset[32].buf);
  mips_collect_register_32bit (regcache, use_64bit, find_regno ("fir"),
			       regset[32].buf + 4);
}

static void
mips_store_fpregset (struct regcache *regcache, const void *buf)
{
  const union mips_register *regset = buf;
  int i, use_64bit, first_fp, big_endian;

  use_64bit = (register_size (0) == 8);
  first_fp = find_regno ("f0");
  big_endian = (__BYTE_ORDER == __BIG_ENDIAN);

  /* See GDB for a discussion of this peculiar layout.  */
  for (i = 0; i < 32; i++)
    if (use_64bit)
      supply_register (regcache, first_fp + i, regset[i].buf);
    else
      supply_register (regcache, first_fp + i,
		       regset[i & ~1].buf + 4 * (big_endian != (i & 1)));

  mips_supply_register_32bit (regcache, use_64bit,
			      find_regno ("fcsr"), regset[32].buf);
  mips_supply_register_32bit (regcache, use_64bit, find_regno ("fir"),
			      regset[32].buf + 4);
}
#endif /* HAVE_PTRACE_GETREGS */

struct regset_info target_regsets[] = {
#ifdef HAVE_PTRACE_GETREGS
  { PTRACE_GETREGS, PTRACE_SETREGS, 0, 38 * 8, GENERAL_REGS,
    mips_fill_gregset, mips_store_gregset },
  { PTRACE_GETFPREGS, PTRACE_SETFPREGS, 0, 33 * 8, FP_REGS,
    mips_fill_fpregset, mips_store_fpregset },
#endif /* HAVE_PTRACE_GETREGS */
  { 0, 0, 0, -1, -1, NULL, NULL }
};

struct linux_target_ops the_low_target = {
#ifdef __mips64
  init_registers_mips64_linux,
#else
  init_registers_mips_linux,
#endif
  mips_num_regs,
  mips_regmap,
  mips_cannot_fetch_register,
  mips_cannot_store_register,
  mips_get_pc,
  mips_set_pc,
  (const unsigned char *) &mips_breakpoint,
  mips_breakpoint_len,
  mips_reinsert_addr,
  0,
  mips_breakpoint_at,
};