/* GNU/Linux S/390 specific low level interface, for the remote server
   for GDB.
   Copyright (C) 2001, 2002, 2005, 2006, 2007, 2008, 2009, 2010, 2011
   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/>.  */

/* This file is used for both 31-bit and 64-bit S/390 systems.  */

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

#include <asm/ptrace.h>
#include <elf.h>

#ifndef HWCAP_S390_HIGH_GPRS
#define HWCAP_S390_HIGH_GPRS 512
#endif

/* Defined in auto-generated file s390-linux32.c.  */
void init_registers_s390_linux32 (void);
/* Defined in auto-generated file s390-linux64.c.  */
void init_registers_s390_linux64 (void);
/* Defined in auto-generated file s390x-linux64.c.  */
void init_registers_s390x_linux64 (void);

#define s390_num_regs 51

static int s390_regmap[] = {
  PT_PSWMASK, PT_PSWADDR,

  PT_GPR0, PT_GPR1, PT_GPR2, PT_GPR3,
  PT_GPR4, PT_GPR5, PT_GPR6, PT_GPR7,
  PT_GPR8, PT_GPR9, PT_GPR10, PT_GPR11,
  PT_GPR12, PT_GPR13, PT_GPR14, PT_GPR15,

  PT_ACR0, PT_ACR1, PT_ACR2, PT_ACR3,
  PT_ACR4, PT_ACR5, PT_ACR6, PT_ACR7,
  PT_ACR8, PT_ACR9, PT_ACR10, PT_ACR11,
  PT_ACR12, PT_ACR13, PT_ACR14, PT_ACR15,

  PT_FPC,

#ifndef __s390x__
  PT_FPR0_HI, PT_FPR1_HI, PT_FPR2_HI, PT_FPR3_HI,
  PT_FPR4_HI, PT_FPR5_HI, PT_FPR6_HI, PT_FPR7_HI,
  PT_FPR8_HI, PT_FPR9_HI, PT_FPR10_HI, PT_FPR11_HI,
  PT_FPR12_HI, PT_FPR13_HI, PT_FPR14_HI, PT_FPR15_HI,
#else
  PT_FPR0, PT_FPR1, PT_FPR2, PT_FPR3,
  PT_FPR4, PT_FPR5, PT_FPR6, PT_FPR7,
  PT_FPR8, PT_FPR9, PT_FPR10, PT_FPR11,
  PT_FPR12, PT_FPR13, PT_FPR14, PT_FPR15,
#endif
};

#ifdef __s390x__
#define s390_num_regs_3264 67

static int s390_regmap_3264[] = {
  PT_PSWMASK, PT_PSWADDR,

  PT_GPR0, PT_GPR0, PT_GPR1, PT_GPR1,
  PT_GPR2, PT_GPR2, PT_GPR3, PT_GPR3,
  PT_GPR4, PT_GPR4, PT_GPR5, PT_GPR5,
  PT_GPR6, PT_GPR6, PT_GPR7, PT_GPR7,
  PT_GPR8, PT_GPR8, PT_GPR9, PT_GPR9,
  PT_GPR10, PT_GPR10, PT_GPR11, PT_GPR11,
  PT_GPR12, PT_GPR12, PT_GPR13, PT_GPR13,
  PT_GPR14, PT_GPR14, PT_GPR15, PT_GPR15,

  PT_ACR0, PT_ACR1, PT_ACR2, PT_ACR3,
  PT_ACR4, PT_ACR5, PT_ACR6, PT_ACR7,
  PT_ACR8, PT_ACR9, PT_ACR10, PT_ACR11,
  PT_ACR12, PT_ACR13, PT_ACR14, PT_ACR15,

  PT_FPC,

  PT_FPR0, PT_FPR1, PT_FPR2, PT_FPR3,
  PT_FPR4, PT_FPR5, PT_FPR6, PT_FPR7,
  PT_FPR8, PT_FPR9, PT_FPR10, PT_FPR11,
  PT_FPR12, PT_FPR13, PT_FPR14, PT_FPR15,
};
#endif


static int
s390_cannot_fetch_register (int regno)
{
  return 0;
}

static int
s390_cannot_store_register (int regno)
{
  return 0;
}

static void
s390_collect_ptrace_register (struct regcache *regcache, int regno, char *buf)
{
  int size = register_size (regno);
  if (size < sizeof (long))
    {
      int regaddr = the_low_target.regmap[regno];

      memset (buf, 0, sizeof (long));

      if ((regno ^ 1) < the_low_target.num_regs
	  && the_low_target.regmap[regno ^ 1] == regaddr)
	{
	  collect_register (regcache, regno & ~1, buf);
	  collect_register (regcache, (regno & ~1) + 1,
			    buf + sizeof (long) - size);
	}
      else if (regaddr == PT_PSWMASK)
	{
	  /* Convert 4-byte PSW mask to 8 bytes by clearing bit 12 and copying
	     the basic addressing mode bit from the PSW address.  */
	  char *addr = alloca (register_size (regno ^ 1));
	  collect_register (regcache, regno, buf);
	  collect_register (regcache, regno ^ 1, addr);
	  buf[1] &= ~0x8;
	  buf[size] |= (addr[0] & 0x80);
	}
      else if (regaddr == PT_PSWADDR)
	{
	  /* Convert 4-byte PSW address to 8 bytes by clearing the addressing
	     mode bit (which gets copied to the PSW mask instead).  */
	  collect_register (regcache, regno, buf + sizeof (long) - size);
	  buf[sizeof (long) - size] &= ~0x80;
	}
      else if (regaddr >= PT_GPR0 && regaddr <= PT_GPR15)
	collect_register (regcache, regno, buf + sizeof (long) - size);
      else
	collect_register (regcache, regno, buf);
    }
  else
    collect_register (regcache, regno, buf);
}

static void
s390_supply_ptrace_register (struct regcache *regcache,
			     int regno, const char *buf)
{
  int size = register_size (regno);
  if (size < sizeof (long))
    {
      int regaddr = the_low_target.regmap[regno];

      if ((regno ^ 1) < the_low_target.num_regs
	  && the_low_target.regmap[regno ^ 1] == regaddr)
	{
	  supply_register (regcache, regno & ~1, buf);
	  supply_register (regcache, (regno & ~1) + 1,
			   buf + sizeof (long) - size);
	}
      else if (regaddr == PT_PSWMASK)
	{
	  /* Convert 8-byte PSW mask to 4 bytes by setting bit 12 and copying
	     the basic addressing mode into the PSW address.  */
	  char *mask = alloca (size);
	  char *addr = alloca (register_size (regno ^ 1));
	  memcpy (mask, buf, size);
	  mask[1] |= 0x8;
	  supply_register (regcache, regno, mask);

	  collect_register (regcache, regno ^ 1, addr);
	  addr[0] &= ~0x80;
	  addr[0] |= (buf[size] & 0x80);
	  supply_register (regcache, regno ^ 1, addr);
	}
      else if (regaddr == PT_PSWADDR)
	{
	  /* Convert 8-byte PSW address to 4 bytes by truncating, but
	     keeping the addressing mode bit (which was set from the mask).  */
	  char *addr = alloca (size);
	  char amode;
	  collect_register (regcache, regno, addr);
	  amode = addr[0] & 0x80;
	  memcpy (addr, buf + sizeof (long) - size, size);
	  addr[0] &= ~0x80;
	  addr[0] |= amode;
	  supply_register (regcache, regno, addr);
	}
      else if (regaddr >= PT_GPR0 && regaddr <= PT_GPR15)
	supply_register (regcache, regno, buf + sizeof (long) - size);
      else
	supply_register (regcache, regno, buf);
    }
  else
    supply_register (regcache, regno, buf);
}

/* Provide only a fill function for the general register set.  ps_lgetregs
   will use this for NPTL support.  */

static void s390_fill_gregset (struct regcache *regcache, void *buf)
{
  int i;

  for (i = 0; i < the_low_target.num_regs; i++)
    {
      if (the_low_target.regmap[i] < PT_PSWMASK
	  || the_low_target.regmap[i] > PT_ACR15)
	continue;

      s390_collect_ptrace_register (regcache, i, (char *) buf
				       + the_low_target.regmap[i]);
    }
}

struct regset_info target_regsets[] = {
  { 0, 0, 0, 0, GENERAL_REGS, s390_fill_gregset, NULL },
  { 0, 0, 0, -1, -1, NULL, NULL }
};


static const unsigned char s390_breakpoint[] = { 0, 1 };
#define s390_breakpoint_len 2

static CORE_ADDR
s390_get_pc (struct regcache *regcache)
{
  if (register_size (0) == 4)
    {
      unsigned int pswa;
      collect_register_by_name (regcache, "pswa", &pswa);
      return pswa & 0x7fffffff;
    }
  else
    {
      unsigned long pc;
      collect_register_by_name (regcache, "pswa", &pc);
      return pc;
    }
}

static void
s390_set_pc (struct regcache *regcache, CORE_ADDR newpc)
{
  if (register_size (0) == 4)
    {
      unsigned int pswa;
      collect_register_by_name (regcache, "pswa", &pswa);
      pswa = (pswa & 0x80000000) | (newpc & 0x7fffffff);
      supply_register_by_name (regcache, "pswa", &pswa);
    }
  else
    {
      unsigned long pc = newpc;
      supply_register_by_name (regcache, "pswa", &pc);
    }
}

#ifdef __s390x__
static unsigned long
s390_get_hwcap (void)
{
  int wordsize = register_size (0);
  unsigned char *data = alloca (2 * wordsize);
  int offset = 0;

  while ((*the_target->read_auxv) (offset, data, 2 * wordsize) == 2 * wordsize)
    {
      if (wordsize == 4)
        {
          unsigned int *data_p = (unsigned int *)data;
          if (data_p[0] == AT_HWCAP)
	    return data_p[1];
        }
      else
        {
          unsigned long *data_p = (unsigned long *)data;
          if (data_p[0] == AT_HWCAP)
	    return data_p[1];
        }

      offset += 2 * wordsize;
    }

  return 0;
}
#endif

static void
s390_arch_setup (void)
{
  /* Assume 31-bit inferior process.  */
  init_registers_s390_linux32 ();
  the_low_target.num_regs = s390_num_regs;
  the_low_target.regmap = s390_regmap;

  /* On a 64-bit host, check the low bit of the (31-bit) PSWM
     -- if this is one, we actually have a 64-bit inferior.  */
#ifdef __s390x__
  {
    unsigned int pswm;
    struct regcache *regcache = new_register_cache ();
    fetch_inferior_registers (regcache, find_regno ("pswm"));
    collect_register_by_name (regcache, "pswm", &pswm);
    free_register_cache (regcache);

    if (pswm & 1)
      init_registers_s390x_linux64 ();

    /* For a 31-bit inferior, check whether the kernel supports
       using the full 64-bit GPRs.  */
    else if (s390_get_hwcap () & HWCAP_S390_HIGH_GPRS)
      {
        init_registers_s390_linux64 ();
	the_low_target.num_regs = s390_num_regs_3264;
	the_low_target.regmap = s390_regmap_3264;
      }
  }
#endif
}


static int
s390_breakpoint_at (CORE_ADDR pc)
{
  unsigned char c[s390_breakpoint_len];
  read_inferior_memory (pc, c, s390_breakpoint_len);
  return memcmp (c, s390_breakpoint, s390_breakpoint_len) == 0;
}


struct linux_target_ops the_low_target = {
  s390_arch_setup,
  s390_num_regs,
  s390_regmap,
  s390_cannot_fetch_register,
  s390_cannot_store_register,
  s390_get_pc,
  s390_set_pc,
  s390_breakpoint,
  s390_breakpoint_len,
  NULL,
  s390_breakpoint_len,
  s390_breakpoint_at,
  NULL,
  NULL,
  NULL,
  NULL,
  s390_collect_ptrace_register,
  s390_supply_ptrace_register,
};
