path: root/gdb/gdbserver/linux-crisv32-low.c

/* GNU/Linux/CRIS specific low level interface, for the remote server for GDB.
   Copyright (C) 1995, 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   2007, 2008, 2009, 2010 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>

/* Defined in auto-generated file reg-crisv32.c.  */
void init_registers_crisv32 (void);

/* CRISv32 */
#define cris_num_regs 49

/* Note: Ignoring USP (having the stack pointer in two locations causes trouble
   without any significant gain).  */

/* Locations need to match <include/asm/arch/ptrace.h>.  */
static int cris_regmap[] = {
  1*4, 2*4, 3*4, 4*4,
  5*4, 6*4, 7*4, 8*4,
  9*4, 10*4, 11*4, 12*4,
  13*4, 14*4, 24*4, 15*4,

  -1, -1, -1, 16*4,
  -1, 22*4, 23*4, 17*4,
  -1, -1, 21*4, 20*4,
  -1, 19*4, -1, 18*4,

  25*4,

  26*4, -1,   -1,   29*4,
  30*4, 31*4, 32*4, 33*4,
  34*4, 35*4, 36*4, 37*4,
  38*4, 39*4, 40*4, -1

};

extern int debug_threads;

static CORE_ADDR
cris_get_pc (struct regcache *regcache)
{
  unsigned long pc;
  collect_register_by_name (regcache, "pc", &pc);
  if (debug_threads)
    fprintf (stderr, "stop pc is %08lx\n", pc);
  return pc;
}

static void
cris_set_pc (struct regcache *regcache, CORE_ADDR pc)
{
  unsigned long newpc = pc;
  supply_register_by_name (regcache, "pc", &newpc);
}

static const unsigned short cris_breakpoint = 0xe938;
#define cris_breakpoint_len 2

static int
cris_breakpoint_at (CORE_ADDR where)
{
  unsigned short insn;

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

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

/* 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.  */

/* FIXME: This function should not be needed, since we have PTRACE_SINGLESTEP
   for CRISv32.  Without it, td_ta_event_getmsg in thread_db_create_event
   will fail when debugging multi-threaded applications.  */

static CORE_ADDR
cris_reinsert_addr (void)
{
  struct regcache *regcache = get_thread_regcache (current_inferior, 1);
  unsigned long pc;
  collect_register_by_name (regcache, "srp", &pc);
  return pc;
}

static void
cris_write_data_breakpoint (struct regcache *regcache,
			    int bp, unsigned long start, unsigned long end)
{
  switch (bp)
    {
    case 0:
      supply_register_by_name (regcache, "s3", &start);
      supply_register_by_name (regcache, "s4", &end);
      break;
    case 1:
      supply_register_by_name (regcache, "s5", &start);
      supply_register_by_name (regcache, "s6", &end);
      break;
    case 2:
      supply_register_by_name (regcache, "s7", &start);
      supply_register_by_name (regcache, "s8", &end);
      break;
    case 3:
      supply_register_by_name (regcache, "s9", &start);
      supply_register_by_name (regcache, "s10", &end);
      break;
    case 4:
      supply_register_by_name (regcache, "s11", &start);
      supply_register_by_name (regcache, "s12", &end);
      break;
    case 5:
      supply_register_by_name (regcache, "s13", &start);
      supply_register_by_name (regcache, "s14", &end);
      break;
    }
}

static int
cris_insert_point (char type, CORE_ADDR addr, int len)
{
  int bp;
  unsigned long bp_ctrl;
  unsigned long start, end;
  unsigned long ccs;
  struct regcache *regcache;

  /* Breakpoint/watchpoint types (GDB terminology):
     0 = memory breakpoint for instructions
     (not supported; done via memory write instead)
     1 = hardware breakpoint for instructions (not supported)
     2 = write watchpoint (supported)
     3 = read watchpoint (supported)
     4 = access watchpoint (supported).  */

  if (type < '2' || type > '4')
    {
      /* Unsupported.  */
      return 1;
    }

  regcache = get_thread_regcache (current_inferior, 1);

  /* Read watchpoints are set as access watchpoints, because of GDB's
     inability to deal with pure read watchpoints.  */
  if (type == '3')
    type = '4';

  /* Get the configuration register.  */
  collect_register_by_name (regcache, "s0", &bp_ctrl);

  /* The watchpoint allocation scheme is the simplest possible.
     For example, if a region is watched for read and
     a write watch is requested, a new watchpoint will
     be used.  Also, if a watch for a region that is already
     covered by one or more existing watchpoints, a new
     watchpoint will be used.  */

  /* First, find a free data watchpoint.  */
  for (bp = 0; bp < 6; bp++)
    {
      /* Each data watchpoint's control registers occupy 2 bits
	 (hence the 3), starting at bit 2 for D0 (hence the 2)
	 with 4 bits between for each watchpoint (yes, the 4).  */
      if (!(bp_ctrl & (0x3 << (2 + (bp * 4)))))
	break;
    }

  if (bp > 5)
    {
      /* We're out of watchpoints.  */
      return -1;
    }

  /* Configure the control register first.  */
  if (type == '3' || type == '4')
    {
      /* Trigger on read.  */
      bp_ctrl |= (1 << (2 + bp * 4));
    }
  if (type == '2' || type == '4')
    {
      /* Trigger on write.  */
      bp_ctrl |= (2 << (2 + bp * 4));
    }

  /* Setup the configuration register.  */
  supply_register_by_name (regcache, "s0", &bp_ctrl);

  /* Setup the range.  */
  start = addr;
  end = addr + len - 1;

  /* Configure the watchpoint register.  */
  cris_write_data_breakpoint (regcache, bp, start, end);

  collect_register_by_name (regcache, "ccs", &ccs);
  /* Set the S1 flag to enable watchpoints.  */
  ccs |= (1 << 19);
  supply_register_by_name (regcache, "ccs", &ccs);

  return 0;
}

static int
cris_remove_point (char type, CORE_ADDR addr, int len)
{
  int bp;
  unsigned long bp_ctrl;
  unsigned long start, end;
  struct regcache *regcache;

  /* Breakpoint/watchpoint types:
     0 = memory breakpoint for instructions
     (not supported; done via memory write instead)
     1 = hardware breakpoint for instructions (not supported)
     2 = write watchpoint (supported)
     3 = read watchpoint (supported)
     4 = access watchpoint (supported).  */
  if (type < '2' || type > '4')
    return -1;

  regcache = get_thread_regcache (current_inferior, 1);

  /* Read watchpoints are set as access watchpoints, because of GDB's
     inability to deal with pure read watchpoints.  */
  if (type == '3')
    type = '4';

  /* Get the configuration register.  */
  collect_register_by_name (regcache, "s0", &bp_ctrl);

  /* Try to find a watchpoint that is configured for the
     specified range, then check that read/write also matches.  */

  /* Ugly pointer arithmetic, since I cannot rely on a
     single switch (addr) as there may be several watchpoints with
     the same start address for example.  */

  unsigned long bp_d_regs[12];

  /* Get all range registers to simplify search.  */
  collect_register_by_name (regcache, "s3", &bp_d_regs[0]);
  collect_register_by_name (regcache, "s4", &bp_d_regs[1]);
  collect_register_by_name (regcache, "s5", &bp_d_regs[2]);
  collect_register_by_name (regcache, "s6", &bp_d_regs[3]);
  collect_register_by_name (regcache, "s7", &bp_d_regs[4]);
  collect_register_by_name (regcache, "s8", &bp_d_regs[5]);
  collect_register_by_name (regcache, "s9", &bp_d_regs[6]);
  collect_register_by_name (regcache, "s10", &bp_d_regs[7]);
  collect_register_by_name (regcache, "s11", &bp_d_regs[8]);
  collect_register_by_name (regcache, "s12", &bp_d_regs[9]);
  collect_register_by_name (regcache, "s13", &bp_d_regs[10]);
  collect_register_by_name (regcache, "s14", &bp_d_regs[11]);

  for (bp = 0; bp < 6; bp++)
    {
      if (bp_d_regs[bp * 2] == addr
	  && bp_d_regs[bp * 2 + 1] == (addr + len - 1)) {
	/* Matching range.  */
	int bitpos = 2 + bp * 4;
	int rw_bits;

	/* Read/write bits for this BP.  */
	rw_bits = (bp_ctrl & (0x3 << bitpos)) >> bitpos;

	if ((type == '3' && rw_bits == 0x1)
	    || (type == '2' && rw_bits == 0x2)
	    || (type == '4' && rw_bits == 0x3))
	  {
	    /* Read/write matched.  */
	    break;
	  }
      }
    }

  if (bp > 5)
    {
      /* No watchpoint matched.  */
      return -1;
    }

  /* Found a matching watchpoint.  Now, deconfigure it by
     both disabling read/write in bp_ctrl and zeroing its
     start/end addresses.  */
  bp_ctrl &= ~(3 << (2 + (bp * 4)));
  /* Setup the configuration register.  */
  supply_register_by_name (regcache, "s0", &bp_ctrl);

  start = end = 0;
  /* Configure the watchpoint register.  */
  cris_write_data_breakpoint (regcache, bp, start, end);

  /* Note that we don't clear the S1 flag here.  It's done when continuing.  */
  return 0;
}

static int
cris_stopped_by_watchpoint (void)
{
  unsigned long exs;

  collect_register_by_name ("exs", &exs);

  return (((exs & 0xff00) >> 8) == 0xc);
}

static CORE_ADDR
cris_stopped_data_address (void)
{
  unsigned long eda;

  collect_register_by_name ("eda", &eda);

  /* FIXME: Possibly adjust to match watched range.  */
  return eda;
}

static void
cris_fill_gregset (void *buf)
{
  int i;

  for (i = 0; i < cris_num_regs; i++)
    {
      if (cris_regmap[i] != -1)
	collect_register (i, ((char *) buf) + cris_regmap[i]);
    }
}

static void
cris_store_gregset (const void *buf)
{
  int i;

  for (i = 0; i < cris_num_regs; i++)
    {
      if (cris_regmap[i] != -1)
	supply_register (i, ((char *) buf) + cris_regmap[i]);
    }
}

typedef unsigned long elf_gregset_t[cris_num_regs];

struct regset_info target_regsets[] = {
  { PTRACE_GETREGS, PTRACE_SETREGS, sizeof (elf_gregset_t),
    GENERAL_REGS, cris_fill_gregset, cris_store_gregset },
  { 0, 0, -1, -1, NULL, NULL }
};

struct linux_target_ops the_low_target = {
  init_register_crisv32,
  -1,
  NULL,
  NULL,
  NULL,
  cris_get_pc,
  cris_set_pc,
  (const unsigned char *) &cris_breakpoint,
  cris_breakpoint_len,
  cris_reinsert_addr,
  0,
  cris_breakpoint_at,
  cris_insert_point,
  cris_remove_point,
  cris_stopped_by_watchpoint,
  cris_stopped_data_address,
};