gdb/s390-linux-tdep.c

gdb/s390-linux-tdep.c - gdb

Source code

/* Target-dependent code for GDB, the GNU debugger.



   Copyright (C) 2001-2015 Free Software Foundation, Inc.



   Contributed by D.J. Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)

   for IBM Deutschland Entwicklung GmbH, IBM Corporation.



   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 "defs.h"

#include "arch-utils.h"

#include "frame.h"

#include "inferior.h"

#include "infrun.h"

#include "symtab.h"

#include "target.h"

#include "gdbcore.h"

#include "gdbcmd.h"

#include "objfiles.h"

#include "floatformat.h"

#include "regcache.h"

#include "trad-frame.h"

#include "frame-base.h"

#include "frame-unwind.h"

#include "dwarf2-frame.h"

#include "reggroups.h"

#include "regset.h"

#include "value.h"

#include "dis-asm.h"

#include "solib-svr4.h"

#include "prologue-value.h"

#include "linux-tdep.h"

#include "s390-linux-tdep.h"

#include "auxv.h"

#include "xml-syscall.h"



#include "stap-probe.h"

#include "ax.h"

#include "ax-gdb.h"

#include "user-regs.h"

#include "cli/cli-utils.h"

#include <ctype.h>

#include "elf/common.h"



#include "features/s390-linux32.c"

#include "features/s390-linux32v1.c"

#include "features/s390-linux32v2.c"

#include "features/s390-linux64.c"

#include "features/s390-linux64v1.c"

#include "features/s390-linux64v2.c"

#include "features/s390-te-linux64.c"

#include "features/s390x-linux64.c"

#include "features/s390x-linux64v1.c"

#include "features/s390x-linux64v2.c"

#include "features/s390x-te-linux64.c"



‌#define XML_SYSCALL_FILENAME_S390 "syscalls/s390-linux.xml"

‌#define XML_SYSCALL_FILENAME_S390X "syscalls/s390x-linux.xml"



/* The tdep structure.  */



‌struct gdbarch_tdep

{

  /* ABI version.  */

  enum { ABI_LINUX_S390, ABI_LINUX_ZSERIES } abi;



  /* Pseudo register numbers.  */

  int gpr_full_regnum;

  int pc_regnum;

  int cc_regnum;



  int have_linux_v1;

  int have_linux_v2;

  int have_tdb;

};





/* ABI call-saved register information.  */



static int

‌s390_register_call_saved (struct gdbarch *gdbarch, int regnum)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  switch (tdep->abi)

    {

    case ABI_LINUX_S390:

      if ((regnum >= S390_R6_REGNUM && regnum <= S390_R15_REGNUM)

          || regnum == S390_F4_REGNUM || regnum == S390_F6_REGNUM

          || regnum == S390_A0_REGNUM)

        return 1;



      break;



    case ABI_LINUX_ZSERIES:

      if ((regnum >= S390_R6_REGNUM && regnum <= S390_R15_REGNUM)

          || (regnum >= S390_F8_REGNUM && regnum <= S390_F15_REGNUM)

          || (regnum >= S390_A0_REGNUM && regnum <= S390_A1_REGNUM))

        return 1;



      break;

    }



  return 0;

}



static int

‌s390_cannot_store_register (struct gdbarch *gdbarch, int regnum)

{

  /* The last-break address is read-only.  */

  return regnum == S390_LAST_BREAK_REGNUM;

}



static void

‌s390_write_pc (struct regcache *regcache, CORE_ADDR pc)

{

  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);



  /* Set special SYSTEM_CALL register to 0 to prevent the kernel from

     messing with the PC we just installed, if we happen to be within

     an interrupted system call that the kernel wants to restart.



     Note that after we return from the dummy call, the SYSTEM_CALL and

     ORIG_R2 registers will be automatically restored, and the kernel

     continues to restart the system call at this point.  */

  if (register_size (gdbarch, S390_SYSTEM_CALL_REGNUM) > 0)

    regcache_cooked_write_unsigned (regcache, S390_SYSTEM_CALL_REGNUM, 0);

}





/* DWARF Register Mapping.  */



‌static const short s390_dwarf_regmap[] =

{

  /* General Purpose Registers.  */

  S390_R0_REGNUM, S390_R1_REGNUM, S390_R2_REGNUM, S390_R3_REGNUM,

  S390_R4_REGNUM, S390_R5_REGNUM, S390_R6_REGNUM, S390_R7_REGNUM,

  S390_R8_REGNUM, S390_R9_REGNUM, S390_R10_REGNUM, S390_R11_REGNUM,

  S390_R12_REGNUM, S390_R13_REGNUM, S390_R14_REGNUM, S390_R15_REGNUM,



  /* Floating Point Registers.  */

  S390_F0_REGNUM, S390_F2_REGNUM, S390_F4_REGNUM, S390_F6_REGNUM,

  S390_F1_REGNUM, S390_F3_REGNUM, S390_F5_REGNUM, S390_F7_REGNUM,

  S390_F8_REGNUM, S390_F10_REGNUM, S390_F12_REGNUM, S390_F14_REGNUM,

  S390_F9_REGNUM, S390_F11_REGNUM, S390_F13_REGNUM, S390_F15_REGNUM,



  /* Control Registers (not mapped).  */

  -1, -1, -1, -1, -1, -1, -1, -1,

  -1, -1, -1, -1, -1, -1, -1, -1,



  /* Access Registers.  */

  S390_A0_REGNUM, S390_A1_REGNUM, S390_A2_REGNUM, S390_A3_REGNUM,

  S390_A4_REGNUM, S390_A5_REGNUM, S390_A6_REGNUM, S390_A7_REGNUM,

  S390_A8_REGNUM, S390_A9_REGNUM, S390_A10_REGNUM, S390_A11_REGNUM,

  S390_A12_REGNUM, S390_A13_REGNUM, S390_A14_REGNUM, S390_A15_REGNUM,



  /* Program Status Word.  */

  S390_PSWM_REGNUM,

  S390_PSWA_REGNUM,



  /* GPR Lower Half Access.  */

  S390_R0_REGNUM, S390_R1_REGNUM, S390_R2_REGNUM, S390_R3_REGNUM,

  S390_R4_REGNUM, S390_R5_REGNUM, S390_R6_REGNUM, S390_R7_REGNUM,

  S390_R8_REGNUM, S390_R9_REGNUM, S390_R10_REGNUM, S390_R11_REGNUM,

  S390_R12_REGNUM, S390_R13_REGNUM, S390_R14_REGNUM, S390_R15_REGNUM,



  /* GNU/Linux-specific registers (not mapped).  */

  -1, -1, -1,

};



/* Convert DWARF register number REG to the appropriate register

   number used by GDB.  */

static int

‌s390_dwarf_reg_to_regnum (struct gdbarch *gdbarch, int reg)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  /* In a 32-on-64 debug scenario, debug info refers to the full 64-bit

     GPRs.  Note that call frame information still refers to the 32-bit

     lower halves, because s390_adjust_frame_regnum uses register numbers

     66 .. 81 to access GPRs.  */

  if (tdep->gpr_full_regnum != -1 && reg >= 0 && reg < 16)

    return tdep->gpr_full_regnum + reg;



  if (reg >= 0 && reg < ARRAY_SIZE (s390_dwarf_regmap))

    return s390_dwarf_regmap[reg];



  warning (_("Unmapped DWARF Register #%d encountered."), reg);

  return -1;

}



/* Translate a .eh_frame register to DWARF register, or adjust a

   .debug_frame register.  */

static int

‌s390_adjust_frame_regnum (struct gdbarch *gdbarch, int num, int eh_frame_p)

{

  /* See s390_dwarf_reg_to_regnum for comments.  */

  return (num >= 0 && num < 16)? num + 66 : num;

}





/* Pseudo registers.  */



static int

‌regnum_is_gpr_full (struct gdbarch_tdep *tdep, int regnum)

{

  return (tdep->gpr_full_regnum != -1

          && regnum >= tdep->gpr_full_regnum

          && regnum <= tdep->gpr_full_regnum + 15);

}



static const char *

‌s390_pseudo_register_name (struct gdbarch *gdbarch, int regnum)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  if (regnum == tdep->pc_regnum)

    return "pc";



  if (regnum == tdep->cc_regnum)

    return "cc";



  if (regnum_is_gpr_full (tdep, regnum))

    {

      static const char *full_name[] = {

        "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",

        "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"

      };

      return full_name[regnum - tdep->gpr_full_regnum];

    }



  internal_error (__FILE__, __LINE__, _("invalid regnum"));

}



static struct type *

‌s390_pseudo_register_type (struct gdbarch *gdbarch, int regnum)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  if (regnum == tdep->pc_regnum)

    return builtin_type (gdbarch)->builtin_func_ptr;



  if (regnum == tdep->cc_regnum)

    return builtin_type (gdbarch)->builtin_int;



  if (regnum_is_gpr_full (tdep, regnum))

    return builtin_type (gdbarch)->builtin_uint64;



  internal_error (__FILE__, __LINE__, _("invalid regnum"));

}



static enum register_status

‌s390_pseudo_register_read (struct gdbarch *gdbarch, struct regcache *regcache,

                           int regnum, gdb_byte *buf)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  int regsize = register_size (gdbarch, regnum);

  ULONGEST val;



  if (regnum == tdep->pc_regnum)

    {

      enum register_status status;



      status = regcache_raw_read_unsigned (regcache, S390_PSWA_REGNUM, &val);

      if (status == REG_VALID)

        {

          if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)

            val &= 0x7fffffff;

          store_unsigned_integer (buf, regsize, byte_order, val);

        }

      return status;

    }



  if (regnum == tdep->cc_regnum)

    {

      enum register_status status;



      status = regcache_raw_read_unsigned (regcache, S390_PSWM_REGNUM, &val);

      if (status == REG_VALID)

        {

          if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)

            val = (val >> 12) & 3;

          else

            val = (val >> 44) & 3;

          store_unsigned_integer (buf, regsize, byte_order, val);

        }

      return status;

    }



  if (regnum_is_gpr_full (tdep, regnum))

    {

      enum register_status status;

      ULONGEST val_upper;



      regnum -= tdep->gpr_full_regnum;



      status = regcache_raw_read_unsigned (regcache, S390_R0_REGNUM + regnum, &val);

      if (status == REG_VALID)

        status = regcache_raw_read_unsigned (regcache, S390_R0_UPPER_REGNUM + regnum,

                                             &val_upper);

      if (status == REG_VALID)

        {

          val |= val_upper << 32;

          store_unsigned_integer (buf, regsize, byte_order, val);

        }

      return status;

    }



  internal_error (__FILE__, __LINE__, _("invalid regnum"));

}



static void

‌s390_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,

                            int regnum, const gdb_byte *buf)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  int regsize = register_size (gdbarch, regnum);

  ULONGEST val, psw;



  if (regnum == tdep->pc_regnum)

    {

      val = extract_unsigned_integer (buf, regsize, byte_order);

      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)

        {

          regcache_raw_read_unsigned (regcache, S390_PSWA_REGNUM, &psw);

          val = (psw & 0x80000000) | (val & 0x7fffffff);

        }

      regcache_raw_write_unsigned (regcache, S390_PSWA_REGNUM, val);

      return;

    }



  if (regnum == tdep->cc_regnum)

    {

      val = extract_unsigned_integer (buf, regsize, byte_order);

      regcache_raw_read_unsigned (regcache, S390_PSWM_REGNUM, &psw);

      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)

        val = (psw & ~((ULONGEST)3 << 12)) | ((val & 3) << 12);

      else

        val = (psw & ~((ULONGEST)3 << 44)) | ((val & 3) << 44);

      regcache_raw_write_unsigned (regcache, S390_PSWM_REGNUM, val);

      return;

    }



  if (regnum_is_gpr_full (tdep, regnum))

    {

      regnum -= tdep->gpr_full_regnum;

      val = extract_unsigned_integer (buf, regsize, byte_order);

      regcache_raw_write_unsigned (regcache, S390_R0_REGNUM + regnum,

                                   val & 0xffffffff);

      regcache_raw_write_unsigned (regcache, S390_R0_UPPER_REGNUM + regnum,

                                   val >> 32);

      return;

    }



  internal_error (__FILE__, __LINE__, _("invalid regnum"));

}



/* 'float' values are stored in the upper half of floating-point

   registers, even though we are otherwise a big-endian platform.  */



static struct value *

‌s390_value_from_register (struct gdbarch *gdbarch, struct type *type,

                          int regnum, struct frame_id frame_id)

{

  struct value *value = default_value_from_register (gdbarch, type,

                                                     regnum, frame_id);

  check_typedef (type);



  if (regnum >= S390_F0_REGNUM && regnum <= S390_F15_REGNUM

      && TYPE_LENGTH (type) < 8)

    set_value_offset (value, 0);



  return value;

}



/* Register groups.  */



static int

‌s390_pseudo_register_reggroup_p (struct gdbarch *gdbarch, int regnum,

                                 struct reggroup *group)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  /* We usually save/restore the whole PSW, which includes PC and CC.

     However, some older gdbservers may not support saving/restoring

     the whole PSW yet, and will return an XML register description

     excluding those from the save/restore register groups.  In those

     cases, we still need to explicitly save/restore PC and CC in order

     to push or pop frames.  Since this doesn't hurt anything if we

     already save/restore the whole PSW (it's just redundant), we add

     PC and CC at this point unconditionally.  */

  if (group == save_reggroup || group == restore_reggroup)

    return regnum == tdep->pc_regnum || regnum == tdep->cc_regnum;



  return default_register_reggroup_p (gdbarch, regnum, group);

}





/* Maps for register sets.  */



‌static const struct regcache_map_entry s390_gregmap[] =

  {

    { 1, S390_PSWM_REGNUM },

    { 1, S390_PSWA_REGNUM },

    { 16, S390_R0_REGNUM },

    { 16, S390_A0_REGNUM },

    { 1, S390_ORIG_R2_REGNUM },

    { 0 }

  };



‌static const struct regcache_map_entry s390_fpregmap[] =

  {

    { 1, S390_FPC_REGNUM, 8 },

    { 16, S390_F0_REGNUM, 8 },

    { 0 }

  };



‌static const struct regcache_map_entry s390_regmap_upper[] =

  {

    { 16, S390_R0_UPPER_REGNUM, 4 },

    { 0 }

  };



‌static const struct regcache_map_entry s390_regmap_last_break[] =

  {

    { 1, REGCACHE_MAP_SKIP, 4 },

    { 1, S390_LAST_BREAK_REGNUM, 4 },

    { 0 }

  };



‌static const struct regcache_map_entry s390x_regmap_last_break[] =

  {

    { 1, S390_LAST_BREAK_REGNUM, 8 },

    { 0 }

  };



‌static const struct regcache_map_entry s390_regmap_system_call[] =

  {

    { 1, S390_SYSTEM_CALL_REGNUM, 4 },

    { 0 }

  };



‌static const struct regcache_map_entry s390_regmap_tdb[] =

  {

    { 1, S390_TDB_DWORD0_REGNUM, 8 },

    { 1, S390_TDB_ABORT_CODE_REGNUM, 8 },

    { 1, S390_TDB_CONFLICT_TOKEN_REGNUM, 8 },

    { 1, S390_TDB_ATIA_REGNUM, 8 },

    { 12, REGCACHE_MAP_SKIP, 8 },

    { 16, S390_TDB_R0_REGNUM, 8 },

    { 0 }

  };





/* Supply the TDB regset.  Like regcache_supply_regset, but invalidate

   the TDB registers unless the TDB format field is valid.  */



static void

‌s390_supply_tdb_regset (const struct regset *regset, struct regcache *regcache,

                    int regnum, const void *regs, size_t len)

{

  ULONGEST tdw;

  enum register_status ret;

  int i;



  regcache_supply_regset (regset, regcache, regnum, regs, len);

  ret = regcache_cooked_read_unsigned (regcache, S390_TDB_DWORD0_REGNUM, &tdw);

  if (ret != REG_VALID || (tdw >> 56) != 1)

    regcache_supply_regset (regset, regcache, regnum, NULL, len);

}



‌const struct regset s390_gregset = {

  s390_gregmap,

  regcache_supply_regset,

  regcache_collect_regset

};



‌const struct regset s390_fpregset = {

  s390_fpregmap,

  regcache_supply_regset,

  regcache_collect_regset

};



‌static const struct regset s390_upper_regset = {

  s390_regmap_upper,

  regcache_supply_regset,

  regcache_collect_regset

};



‌const struct regset s390_last_break_regset = {

  s390_regmap_last_break,

  regcache_supply_regset,

  regcache_collect_regset

};



‌const struct regset s390x_last_break_regset = {

  s390x_regmap_last_break,

  regcache_supply_regset,

  regcache_collect_regset

};



‌const struct regset s390_system_call_regset = {

  s390_regmap_system_call,

  regcache_supply_regset,

  regcache_collect_regset

};



‌const struct regset s390_tdb_regset = {

  s390_regmap_tdb,

  s390_supply_tdb_regset,

  regcache_collect_regset

};



/* Iterate over supported core file register note sections. */



static void

‌s390_iterate_over_regset_sections (struct gdbarch *gdbarch,

                                   iterate_over_regset_sections_cb *cb,

                                   void *cb_data,

                                   const struct regcache *regcache)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  const int gregset_size = (tdep->abi == ABI_LINUX_S390 ?

                            s390_sizeof_gregset : s390x_sizeof_gregset);



  cb (".reg", gregset_size, &s390_gregset, NULL, cb_data);

  cb (".reg2", s390_sizeof_fpregset, &s390_fpregset, NULL, cb_data);



  if (tdep->abi == ABI_LINUX_S390 && tdep->gpr_full_regnum != -1)

    cb (".reg-s390-high-gprs", 16 * 4, &s390_upper_regset,

        "s390 GPR upper halves", cb_data);



  if (tdep->have_linux_v1)

    cb (".reg-s390-last-break", 8,

        (gdbarch_ptr_bit (gdbarch) == 32

         ? &s390_last_break_regset : &s390x_last_break_regset),

        "s930 last-break address", cb_data);



  if (tdep->have_linux_v2)

    cb (".reg-s390-system-call", 4, &s390_system_call_regset,

        "s390 system-call", cb_data);



  /* If regcache is set, we are in "write" (gcore) mode.  In this

     case, don't iterate over the TDB unless its registers are

     available.  */

  if (tdep->have_tdb

      && (regcache == NULL

          || REG_VALID == regcache_register_status (regcache,

                                                    S390_TDB_DWORD0_REGNUM)))

    cb (".reg-s390-tdb", s390_sizeof_tdbregset, &s390_tdb_regset,

        "s390 TDB", cb_data);

}



static const struct target_desc *

‌s390_core_read_description (struct gdbarch *gdbarch,

                            struct target_ops *target, bfd *abfd)

{

  asection *high_gprs = bfd_get_section_by_name (abfd, ".reg-s390-high-gprs");

  asection *v1 = bfd_get_section_by_name (abfd, ".reg-s390-last-break");

  asection *v2 = bfd_get_section_by_name (abfd, ".reg-s390-system-call");

  asection *section = bfd_get_section_by_name (abfd, ".reg");

  CORE_ADDR hwcap = 0;



  target_auxv_search (target, AT_HWCAP, &hwcap);

  if (!section)

    return NULL;



  switch (bfd_section_size (abfd, section))

    {

    case s390_sizeof_gregset:

      if (high_gprs)

        return ((hwcap & HWCAP_S390_TE) ? tdesc_s390_te_linux64 :

                v2? tdesc_s390_linux64v2 :

                v1? tdesc_s390_linux64v1 : tdesc_s390_linux64);

      else

        return (v2? tdesc_s390_linux32v2 :

                v1? tdesc_s390_linux32v1 : tdesc_s390_linux32);



    case s390x_sizeof_gregset:

      return ((hwcap & HWCAP_S390_TE) ? tdesc_s390x_te_linux64 :

              v2? tdesc_s390x_linux64v2 :

              v1? tdesc_s390x_linux64v1 : tdesc_s390x_linux64);



    default:

      return NULL;

    }

}





/* Decoding S/390 instructions.  */



/* Named opcode values for the S/390 instructions we recognize.  Some

   instructions have their opcode split across two fields; those are the

   op1_* and op2_* enums.  */

enum

  {

    op1_lhi  = 0xa7,   op2_lhi  = 0x08,

    op1_lghi = 0xa7,   op2_lghi = 0x09,

    op1_lgfi = 0xc0,   op2_lgfi = 0x01,

    op_lr    = 0x18,

    op_lgr   = 0xb904,

    op_l     = 0x58,

    op1_ly   = 0xe3,   op2_ly   = 0x58,

    op1_lg   = 0xe3,   op2_lg   = 0x04,

    op_lm    = 0x98,

    op1_lmy  = 0xeb,   op2_lmy  = 0x98,

    op1_lmg  = 0xeb,   op2_lmg  = 0x04,

    op_st    = 0x50,

    op1_sty  = 0xe3,   op2_sty  = 0x50,

    op1_stg  = 0xe3,   op2_stg  = 0x24,

    op_std   = 0x60,

    op_stm   = 0x90,

    op1_stmy = 0xeb,   op2_stmy = 0x90,

    op1_stmg = 0xeb,   op2_stmg = 0x24,

    op1_aghi = 0xa7,   op2_aghi = 0x0b,

    op1_ahi  = 0xa7,   op2_ahi  = 0x0a,

    op1_agfi = 0xc2,   op2_agfi = 0x08,

    op1_afi  = 0xc2,   op2_afi  = 0x09,

    op1_algfi= 0xc2,   op2_algfi= 0x0a,

    op1_alfi = 0xc2,   op2_alfi = 0x0b,

    op_ar    = 0x1a,

    op_agr   = 0xb908,

    op_a     = 0x5a,

    op1_ay   = 0xe3,   op2_ay   = 0x5a,

    op1_ag   = 0xe3,   op2_ag   = 0x08,

    op1_slgfi= 0xc2,   op2_slgfi= 0x04,

    op1_slfi = 0xc2,   op2_slfi = 0x05,

    op_sr    = 0x1b,

    op_sgr   = 0xb909,

    op_s     = 0x5b,

    op1_sy   = 0xe3,   op2_sy   = 0x5b,

    op1_sg   = 0xe3,   op2_sg   = 0x09,

    op_nr    = 0x14,

    op_ngr   = 0xb980,

    op_la    = 0x41,

    op1_lay  = 0xe3,   op2_lay  = 0x71,

    op1_larl = 0xc0,   op2_larl = 0x00,

    op_basr  = 0x0d,

    op_bas   = 0x4d,

    op_bcr   = 0x07,

    op_bc    = 0x0d,

    op_bctr  = 0x06,

    op_bctgr = 0xb946,

    op_bct   = 0x46,

    op1_bctg = 0xe3,   op2_bctg = 0x46,

    op_bxh   = 0x86,

    op1_bxhg = 0xeb,   op2_bxhg = 0x44,

    op_bxle  = 0x87,

    op1_bxleg= 0xeb,   op2_bxleg= 0x45,

    op1_bras = 0xa7,   op2_bras = 0x05,

    op1_brasl= 0xc0,   op2_brasl= 0x05,

    op1_brc  = 0xa7,   op2_brc  = 0x04,

    op1_brcl = 0xc0,   op2_brcl = 0x04,

    op1_brct = 0xa7,   op2_brct = 0x06,

    op1_brctg= 0xa7,   op2_brctg= 0x07,

    op_brxh  = 0x84,

    op1_brxhg= 0xec,   op2_brxhg= 0x44,

    op_brxle = 0x85,

    op1_brxlg= 0xec,   op2_brxlg= 0x45,

    op_svc   = 0x0a,

  };





/* Read a single instruction from address AT.  */



‌#define S390_MAX_INSTR_SIZE 6

static int

‌s390_readinstruction (bfd_byte instr[], CORE_ADDR at)

{

  static int s390_instrlen[] = { 2, 4, 4, 6 };

  int instrlen;



  if (target_read_memory (at, &instr[0], 2))

    return -1;

  instrlen = s390_instrlen[instr[0] >> 6];

  if (instrlen > 2)

    {

      if (target_read_memory (at + 2, &instr[2], instrlen - 2))

        return -1;

    }

  return instrlen;

}





/* The functions below are for recognizing and decoding S/390

   instructions of various formats.  Each of them checks whether INSN

   is an instruction of the given format, with the specified opcodes.

   If it is, it sets the remaining arguments to the values of the

   instruction's fields, and returns a non-zero value; otherwise, it

   returns zero.



   These functions' arguments appear in the order they appear in the

   instruction, not in the machine-language form.  So, opcodes always

   come first, even though they're sometimes scattered around the

   instructions.  And displacements appear before base and extension

   registers, as they do in the assembly syntax, not at the end, as

   they do in the machine language.  */

static int

‌is_ri (bfd_byte *insn, int op1, int op2, unsigned int *r1, int *i2)

{

  if (insn[0] == op1 && (insn[1] & 0xf) == op2)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      /* i2 is a 16-bit signed quantity.  */

      *i2 = (((insn[2] << 8) | insn[3]) ^ 0x8000) - 0x8000;

      return 1;

    }

  else

    return 0;

}





static int

‌is_ril (bfd_byte *insn, int op1, int op2,

        unsigned int *r1, int *i2)

{

  if (insn[0] == op1 && (insn[1] & 0xf) == op2)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      /* i2 is a signed quantity.  If the host 'int' is 32 bits long,

         no sign extension is necessary, but we don't want to assume

         that.  */

      *i2 = (((insn[2] << 24)

              | (insn[3] << 16)

              | (insn[4] << 8)

              | (insn[5])) ^ 0x80000000) - 0x80000000;

      return 1;

    }

  else

    return 0;

}





static int

‌is_rr (bfd_byte *insn, int op, unsigned int *r1, unsigned int *r2)

{

  if (insn[0] == op)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *r2 = insn[1] & 0xf;

      return 1;

    }

  else

    return 0;

}





static int

‌is_rre (bfd_byte *insn, int op, unsigned int *r1, unsigned int *r2)

{

  if (((insn[0] << 8) | insn[1]) == op)

    {

      /* Yes, insn[3].  insn[2] is unused in RRE format.  */

      *r1 = (insn[3] >> 4) & 0xf;

      *r2 = insn[3] & 0xf;

      return 1;

    }

  else

    return 0;

}





static int

‌is_rs (bfd_byte *insn, int op,

       unsigned int *r1, unsigned int *r3, int *d2, unsigned int *b2)

{

  if (insn[0] == op)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *r3 = insn[1] & 0xf;

      *b2 = (insn[2] >> 4) & 0xf;

      *d2 = ((insn[2] & 0xf) << 8) | insn[3];

      return 1;

    }

  else

    return 0;

}





static int

‌is_rsy (bfd_byte *insn, int op1, int op2,

        unsigned int *r1, unsigned int *r3, int *d2, unsigned int *b2)

{

  if (insn[0] == op1

      && insn[5] == op2)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *r3 = insn[1] & 0xf;

      *b2 = (insn[2] >> 4) & 0xf;

      /* The 'long displacement' is a 20-bit signed integer.  */

      *d2 = ((((insn[2] & 0xf) << 8) | insn[3] | (insn[4] << 12))

                ^ 0x80000) - 0x80000;

      return 1;

    }

  else

    return 0;

}





static int

‌is_rsi (bfd_byte *insn, int op,

        unsigned int *r1, unsigned int *r3, int *i2)

{

  if (insn[0] == op)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *r3 = insn[1] & 0xf;

      /* i2 is a 16-bit signed quantity.  */

      *i2 = (((insn[2] << 8) | insn[3]) ^ 0x8000) - 0x8000;

      return 1;

    }

  else

    return 0;

}





static int

‌is_rie (bfd_byte *insn, int op1, int op2,

        unsigned int *r1, unsigned int *r3, int *i2)

{

  if (insn[0] == op1

      && insn[5] == op2)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *r3 = insn[1] & 0xf;

      /* i2 is a 16-bit signed quantity.  */

      *i2 = (((insn[2] << 8) | insn[3]) ^ 0x8000) - 0x8000;

      return 1;

    }

  else

    return 0;

}





static int

‌is_rx (bfd_byte *insn, int op,

       unsigned int *r1, int *d2, unsigned int *x2, unsigned int *b2)

{

  if (insn[0] == op)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *x2 = insn[1] & 0xf;

      *b2 = (insn[2] >> 4) & 0xf;

      *d2 = ((insn[2] & 0xf) << 8) | insn[3];

      return 1;

    }

  else

    return 0;

}





static int

‌is_rxy (bfd_byte *insn, int op1, int op2,

        unsigned int *r1, int *d2, unsigned int *x2, unsigned int *b2)

{

  if (insn[0] == op1

      && insn[5] == op2)

    {

      *r1 = (insn[1] >> 4) & 0xf;

      *x2 = insn[1] & 0xf;

      *b2 = (insn[2] >> 4) & 0xf;

      /* The 'long displacement' is a 20-bit signed integer.  */

      *d2 = ((((insn[2] & 0xf) << 8) | insn[3] | (insn[4] << 12))

                ^ 0x80000) - 0x80000;

      return 1;

    }

  else

    return 0;

}





/* Prologue analysis.  */



‌#define S390_NUM_GPRS 16

‌#define S390_NUM_FPRS 16



‌struct s390_prologue_data {



  /* The stack.  */

  struct pv_area *stack;



  /* The size and byte-order of a GPR or FPR.  */

  int gpr_size;

  int fpr_size;

  enum bfd_endian byte_order;



  /* The general-purpose registers.  */

  pv_t gpr[S390_NUM_GPRS];



  /* The floating-point registers.  */

  pv_t fpr[S390_NUM_FPRS];



  /* The offset relative to the CFA where the incoming GPR N was saved

     by the function prologue.  0 if not saved or unknown.  */

  int gpr_slot[S390_NUM_GPRS];



  /* Likewise for FPRs.  */

  int fpr_slot[S390_NUM_FPRS];



  /* Nonzero if the backchain was saved.  This is assumed to be the

     case when the incoming SP is saved at the current SP location.  */

  int back_chain_saved_p;

};



/* Return the effective address for an X-style instruction, like:



        L R1, D2(X2, B2)



   Here, X2 and B2 are registers, and D2 is a signed 20-bit

   constant; the effective address is the sum of all three.  If either

   X2 or B2 are zero, then it doesn't contribute to the sum --- this

   means that r0 can't be used as either X2 or B2.  */

static pv_t

‌s390_addr (struct s390_prologue_data *data,

           int d2, unsigned int x2, unsigned int b2)

{

  pv_t result;



  result = pv_constant (d2);

  if (x2)

    result = pv_add (result, data->gpr[x2]);

  if (b2)

    result = pv_add (result, data->gpr[b2]);



  return result;

}



/* Do a SIZE-byte store of VALUE to D2(X2,B2).  */

static void

‌s390_store (struct s390_prologue_data *data,

            int d2, unsigned int x2, unsigned int b2, CORE_ADDR size,

            pv_t value)

{

  pv_t addr = s390_addr (data, d2, x2, b2);

  pv_t offset;



  /* Check whether we are storing the backchain.  */

  offset = pv_subtract (data->gpr[S390_SP_REGNUM - S390_R0_REGNUM], addr);



  if (pv_is_constant (offset) && offset.k == 0)

    if (size == data->gpr_size

        && pv_is_register_k (value, S390_SP_REGNUM, 0))

      {

        data->back_chain_saved_p = 1;

        return;

      }





  /* Check whether we are storing a register into the stack.  */

  if (!pv_area_store_would_trash (data->stack, addr))

    pv_area_store (data->stack, addr, size, value);





  /* Note: If this is some store we cannot identify, you might think we

     should forget our cached values, as any of those might have been hit.



     However, we make the assumption that the register save areas are only

     ever stored to once in any given function, and we do recognize these

     stores.  Thus every store we cannot recognize does not hit our data.  */

}



/* Do a SIZE-byte load from D2(X2,B2).  */

static pv_t

‌s390_load (struct s390_prologue_data *data,

           int d2, unsigned int x2, unsigned int b2, CORE_ADDR size)



{

  pv_t addr = s390_addr (data, d2, x2, b2);



  /* If it's a load from an in-line constant pool, then we can

     simulate that, under the assumption that the code isn't

     going to change between the time the processor actually

     executed it creating the current frame, and the time when

     we're analyzing the code to unwind past that frame.  */

  if (pv_is_constant (addr))

    {

      struct target_section *secp;

      secp = target_section_by_addr (&current_target, addr.k);

      if (secp != NULL

          && (bfd_get_section_flags (secp->the_bfd_section->owner,

                                     secp->the_bfd_section)

              & SEC_READONLY))

        return pv_constant (read_memory_integer (addr.k, size,

                                                 data->byte_order));

    }



  /* Check whether we are accessing one of our save slots.  */

  return pv_area_fetch (data->stack, addr, size);

}



/* Function for finding saved registers in a 'struct pv_area'; we pass

   this to pv_area_scan.



   If VALUE is a saved register, ADDR says it was saved at a constant

   offset from the frame base, and SIZE indicates that the whole

   register was saved, record its offset in the reg_offset table in

   PROLOGUE_UNTYPED.  */

static void

‌s390_check_for_saved (void *data_untyped, pv_t addr,

                      CORE_ADDR size, pv_t value)

{

  struct s390_prologue_data *data = data_untyped;

  int i, offset;



  if (!pv_is_register (addr, S390_SP_REGNUM))

    return;



  offset = 16 * data->gpr_size + 32 - addr.k;



  /* If we are storing the original value of a register, we want to

     record the CFA offset.  If the same register is stored multiple

     times, the stack slot with the highest address counts.  */



  for (i = 0; i < S390_NUM_GPRS; i++)

    if (size == data->gpr_size

        && pv_is_register_k (value, S390_R0_REGNUM + i, 0))

      if (data->gpr_slot[i] == 0

          || data->gpr_slot[i] > offset)

        {

          data->gpr_slot[i] = offset;

          return;

        }



  for (i = 0; i < S390_NUM_FPRS; i++)

    if (size == data->fpr_size

        && pv_is_register_k (value, S390_F0_REGNUM + i, 0))

      if (data->fpr_slot[i] == 0

          || data->fpr_slot[i] > offset)

        {

          data->fpr_slot[i] = offset;

          return;

        }

}



/* Analyze the prologue of the function starting at START_PC,

   continuing at most until CURRENT_PC.  Initialize DATA to

   hold all information we find out about the state of the registers

   and stack slots.  Return the address of the instruction after

   the last one that changed the SP, FP, or back chain; or zero

   on error.  */

static CORE_ADDR

‌s390_analyze_prologue (struct gdbarch *gdbarch,

                       CORE_ADDR start_pc,

                       CORE_ADDR current_pc,

                       struct s390_prologue_data *data)

{

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;



  /* Our return value:

     The address of the instruction after the last one that changed

     the SP, FP, or back chain;  zero if we got an error trying to

     read memory.  */

  CORE_ADDR result = start_pc;



  /* The current PC for our abstract interpretation.  */

  CORE_ADDR pc;



  /* The address of the next instruction after that.  */

  CORE_ADDR next_pc;



  /* Set up everything's initial value.  */

  {

    int i;



    data->stack = make_pv_area (S390_SP_REGNUM, gdbarch_addr_bit (gdbarch));



    /* For the purpose of prologue tracking, we consider the GPR size to

       be equal to the ABI word size, even if it is actually larger

       (i.e. when running a 32-bit binary under a 64-bit kernel).  */

    data->gpr_size = word_size;

    data->fpr_size = 8;

    data->byte_order = gdbarch_byte_order (gdbarch);



    for (i = 0; i < S390_NUM_GPRS; i++)

      data->gpr[i] = pv_register (S390_R0_REGNUM + i, 0);



    for (i = 0; i < S390_NUM_FPRS; i++)

      data->fpr[i] = pv_register (S390_F0_REGNUM + i, 0);



    for (i = 0; i < S390_NUM_GPRS; i++)

      data->gpr_slot[i]  = 0;



    for (i = 0; i < S390_NUM_FPRS; i++)

      data->fpr_slot[i]  = 0;



    data->back_chain_saved_p = 0;

  }



  /* Start interpreting instructions, until we hit the frame's

     current PC or the first branch instruction.  */

  for (pc = start_pc; pc > 0 && pc < current_pc; pc = next_pc)

    {

      bfd_byte insn[S390_MAX_INSTR_SIZE];

      int insn_len = s390_readinstruction (insn, pc);



      bfd_byte dummy[S390_MAX_INSTR_SIZE] = { 0 };

      bfd_byte *insn32 = word_size == 4 ? insn : dummy;

      bfd_byte *insn64 = word_size == 8 ? insn : dummy;



      /* Fields for various kinds of instructions.  */

      unsigned int b2, r1, r2, x2, r3;

      int i2, d2;



      /* The values of SP and FP before this instruction,

         for detecting instructions that change them.  */

      pv_t pre_insn_sp, pre_insn_fp;

      /* Likewise for the flag whether the back chain was saved.  */

      int pre_insn_back_chain_saved_p;



      /* If we got an error trying to read the instruction, report it.  */

      if (insn_len < 0)

        {

          result = 0;

          break;

        }



      next_pc = pc + insn_len;



      pre_insn_sp = data->gpr[S390_SP_REGNUM - S390_R0_REGNUM];

      pre_insn_fp = data->gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];

      pre_insn_back_chain_saved_p = data->back_chain_saved_p;





      /* LHI r1, i2 --- load halfword immediate.  */

      /* LGHI r1, i2 --- load halfword immediate (64-bit version).  */

      /* LGFI r1, i2 --- load fullword immediate.  */

      if (is_ri (insn32, op1_lhi, op2_lhi, &r1, &i2)

          || is_ri (insn64, op1_lghi, op2_lghi, &r1, &i2)

          || is_ril (insn, op1_lgfi, op2_lgfi, &r1, &i2))

        data->gpr[r1] = pv_constant (i2);



      /* LR r1, r2 --- load from register.  */

      /* LGR r1, r2 --- load from register (64-bit version).  */

      else if (is_rr (insn32, op_lr, &r1, &r2)

               || is_rre (insn64, op_lgr, &r1, &r2))

        data->gpr[r1] = data->gpr[r2];



      /* L r1, d2(x2, b2) --- load.  */

      /* LY r1, d2(x2, b2) --- load (long-displacement version).  */

      /* LG r1, d2(x2, b2) --- load (64-bit version).  */

      else if (is_rx (insn32, op_l, &r1, &d2, &x2, &b2)

               || is_rxy (insn32, op1_ly, op2_ly, &r1, &d2, &x2, &b2)

               || is_rxy (insn64, op1_lg, op2_lg, &r1, &d2, &x2, &b2))

        data->gpr[r1] = s390_load (data, d2, x2, b2, data->gpr_size);



      /* ST r1, d2(x2, b2) --- store.  */

      /* STY r1, d2(x2, b2) --- store (long-displacement version).  */

      /* STG r1, d2(x2, b2) --- store (64-bit version).  */

      else if (is_rx (insn32, op_st, &r1, &d2, &x2, &b2)

               || is_rxy (insn32, op1_sty, op2_sty, &r1, &d2, &x2, &b2)

               || is_rxy (insn64, op1_stg, op2_stg, &r1, &d2, &x2, &b2))

        s390_store (data, d2, x2, b2, data->gpr_size, data->gpr[r1]);



      /* STD r1, d2(x2,b2) --- store floating-point register.  */

      else if (is_rx (insn, op_std, &r1, &d2, &x2, &b2))

        s390_store (data, d2, x2, b2, data->fpr_size, data->fpr[r1]);



      /* STM r1, r3, d2(b2) --- store multiple.  */

      /* STMY r1, r3, d2(b2) --- store multiple (long-displacement

         version).  */

      /* STMG r1, r3, d2(b2) --- store multiple (64-bit version).  */

      else if (is_rs (insn32, op_stm, &r1, &r3, &d2, &b2)

               || is_rsy (insn32, op1_stmy, op2_stmy, &r1, &r3, &d2, &b2)

               || is_rsy (insn64, op1_stmg, op2_stmg, &r1, &r3, &d2, &b2))

        {

          for (; r1 <= r3; r1++, d2 += data->gpr_size)

            s390_store (data, d2, 0, b2, data->gpr_size, data->gpr[r1]);

        }



      /* AHI r1, i2 --- add halfword immediate.  */

      /* AGHI r1, i2 --- add halfword immediate (64-bit version).  */

      /* AFI r1, i2 --- add fullword immediate.  */

      /* AGFI r1, i2 --- add fullword immediate (64-bit version).  */

      else if (is_ri (insn32, op1_ahi, op2_ahi, &r1, &i2)

               || is_ri (insn64, op1_aghi, op2_aghi, &r1, &i2)

               || is_ril (insn32, op1_afi, op2_afi, &r1, &i2)

               || is_ril (insn64, op1_agfi, op2_agfi, &r1, &i2))

        data->gpr[r1] = pv_add_constant (data->gpr[r1], i2);



      /* ALFI r1, i2 --- add logical immediate.  */

      /* ALGFI r1, i2 --- add logical immediate (64-bit version).  */

      else if (is_ril (insn32, op1_alfi, op2_alfi, &r1, &i2)

               || is_ril (insn64, op1_algfi, op2_algfi, &r1, &i2))

        data->gpr[r1] = pv_add_constant (data->gpr[r1],

                                         (CORE_ADDR)i2 & 0xffffffff);



      /* AR r1, r2 -- add register.  */

      /* AGR r1, r2 -- add register (64-bit version).  */

      else if (is_rr (insn32, op_ar, &r1, &r2)

               || is_rre (insn64, op_agr, &r1, &r2))

        data->gpr[r1] = pv_add (data->gpr[r1], data->gpr[r2]);



      /* A r1, d2(x2, b2) -- add.  */

      /* AY r1, d2(x2, b2) -- add (long-displacement version).  */

      /* AG r1, d2(x2, b2) -- add (64-bit version).  */

      else if (is_rx (insn32, op_a, &r1, &d2, &x2, &b2)

               || is_rxy (insn32, op1_ay, op2_ay, &r1, &d2, &x2, &b2)

               || is_rxy (insn64, op1_ag, op2_ag, &r1, &d2, &x2, &b2))

        data->gpr[r1] = pv_add (data->gpr[r1],

                                s390_load (data, d2, x2, b2, data->gpr_size));



      /* SLFI r1, i2 --- subtract logical immediate.  */

      /* SLGFI r1, i2 --- subtract logical immediate (64-bit version).  */

      else if (is_ril (insn32, op1_slfi, op2_slfi, &r1, &i2)

               || is_ril (insn64, op1_slgfi, op2_slgfi, &r1, &i2))

        data->gpr[r1] = pv_add_constant (data->gpr[r1],

                                         -((CORE_ADDR)i2 & 0xffffffff));



      /* SR r1, r2 -- subtract register.  */

      /* SGR r1, r2 -- subtract register (64-bit version).  */

      else if (is_rr (insn32, op_sr, &r1, &r2)

               || is_rre (insn64, op_sgr, &r1, &r2))

        data->gpr[r1] = pv_subtract (data->gpr[r1], data->gpr[r2]);



      /* S r1, d2(x2, b2) -- subtract.  */

      /* SY r1, d2(x2, b2) -- subtract (long-displacement version).  */

      /* SG r1, d2(x2, b2) -- subtract (64-bit version).  */

      else if (is_rx (insn32, op_s, &r1, &d2, &x2, &b2)

               || is_rxy (insn32, op1_sy, op2_sy, &r1, &d2, &x2, &b2)

               || is_rxy (insn64, op1_sg, op2_sg, &r1, &d2, &x2, &b2))

        data->gpr[r1] = pv_subtract (data->gpr[r1],

                                s390_load (data, d2, x2, b2, data->gpr_size));



      /* LA r1, d2(x2, b2) --- load address.  */

      /* LAY r1, d2(x2, b2) --- load address (long-displacement version).  */

      else if (is_rx (insn, op_la, &r1, &d2, &x2, &b2)

               || is_rxy (insn, op1_lay, op2_lay, &r1, &d2, &x2, &b2))

        data->gpr[r1] = s390_addr (data, d2, x2, b2);



      /* LARL r1, i2 --- load address relative long.  */

      else if (is_ril (insn, op1_larl, op2_larl, &r1, &i2))

        data->gpr[r1] = pv_constant (pc + i2 * 2);



      /* BASR r1, 0 --- branch and save.

         Since r2 is zero, this saves the PC in r1, but doesn't branch.  */

      else if (is_rr (insn, op_basr, &r1, &r2)

               && r2 == 0)

        data->gpr[r1] = pv_constant (next_pc);



      /* BRAS r1, i2 --- branch relative and save.  */

      else if (is_ri (insn, op1_bras, op2_bras, &r1, &i2))

        {

          data->gpr[r1] = pv_constant (next_pc);

          next_pc = pc + i2 * 2;



          /* We'd better not interpret any backward branches.  We'll

             never terminate.  */

          if (next_pc <= pc)

            break;

        }



      /* Terminate search when hitting any other branch instruction.  */

      else if (is_rr (insn, op_basr, &r1, &r2)

               || is_rx (insn, op_bas, &r1, &d2, &x2, &b2)

               || is_rr (insn, op_bcr, &r1, &r2)

               || is_rx (insn, op_bc, &r1, &d2, &x2, &b2)

               || is_ri (insn, op1_brc, op2_brc, &r1, &i2)

               || is_ril (insn, op1_brcl, op2_brcl, &r1, &i2)

               || is_ril (insn, op1_brasl, op2_brasl, &r2, &i2))

        break;



      else

        {

          /* An instruction we don't know how to simulate.  The only

             safe thing to do would be to set every value we're tracking

             to 'unknown'.  Instead, we'll be optimistic: we assume that

             we *can* interpret every instruction that the compiler uses

             to manipulate any of the data we're interested in here --

             then we can just ignore anything else.  */

        }



      /* Record the address after the last instruction that changed

         the FP, SP, or backlink.  Ignore instructions that changed

         them back to their original values --- those are probably

         restore instructions.  (The back chain is never restored,

         just popped.)  */

      {

        pv_t sp = data->gpr[S390_SP_REGNUM - S390_R0_REGNUM];

        pv_t fp = data->gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];



        if ((! pv_is_identical (pre_insn_sp, sp)

             && ! pv_is_register_k (sp, S390_SP_REGNUM, 0)

             && sp.kind != pvk_unknown)

            || (! pv_is_identical (pre_insn_fp, fp)

                && ! pv_is_register_k (fp, S390_FRAME_REGNUM, 0)

                && fp.kind != pvk_unknown)

            || pre_insn_back_chain_saved_p != data->back_chain_saved_p)

          result = next_pc;

      }

    }



  /* Record where all the registers were saved.  */

  pv_area_scan (data->stack, s390_check_for_saved, data);



  free_pv_area (data->stack);

  data->stack = NULL;



  return result;

}



/* Advance PC across any function entry prologue instructions to reach

   some "real" code.  */

static CORE_ADDR

‌s390_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)

{

  struct s390_prologue_data data;

  CORE_ADDR skip_pc;

  skip_pc = s390_analyze_prologue (gdbarch, pc, (CORE_ADDR)-1, &data);

  return skip_pc ? skip_pc : pc;

}



/* Return true if we are in the functin's epilogue, i.e. after the

   instruction that destroyed the function's stack frame.  */

static int

‌s390_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)

{

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;



  /* In frameless functions, there's not frame to destroy and thus

     we don't care about the epilogue.



     In functions with frame, the epilogue sequence is a pair of

     a LM-type instruction that restores (amongst others) the

     return register %r14 and the stack pointer %r15, followed

     by a branch 'br %r14' --or equivalent-- that effects the

     actual return.



     In that situation, this function needs to return 'true' in

     exactly one case: when pc points to that branch instruction.



     Thus we try to disassemble the one instructions immediately

     preceding pc and check whether it is an LM-type instruction

     modifying the stack pointer.



     Note that disassembling backwards is not reliable, so there

     is a slight chance of false positives here ...  */



  bfd_byte insn[6];

  unsigned int r1, r3, b2;

  int d2;



  if (word_size == 4

      && !target_read_memory (pc - 4, insn, 4)

      && is_rs (insn, op_lm, &r1, &r3, &d2, &b2)

      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)

    return 1;



  if (word_size == 4

      && !target_read_memory (pc - 6, insn, 6)

      && is_rsy (insn, op1_lmy, op2_lmy, &r1, &r3, &d2, &b2)

      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)

    return 1;



  if (word_size == 8

      && !target_read_memory (pc - 6, insn, 6)

      && is_rsy (insn, op1_lmg, op2_lmg, &r1, &r3, &d2, &b2)

      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)

    return 1;



  return 0;

}



/* Displaced stepping.  */



/* Fix up the state of registers and memory after having single-stepped

   a displaced instruction.  */

static void

‌s390_displaced_step_fixup (struct gdbarch *gdbarch,

                           struct displaced_step_closure *closure,

                           CORE_ADDR from, CORE_ADDR to,

                           struct regcache *regs)

{

  /* Since we use simple_displaced_step_copy_insn, our closure is a

     copy of the instruction.  */

  gdb_byte *insn = (gdb_byte *) closure;

  static int s390_instrlen[] = { 2, 4, 4, 6 };

  int insnlen = s390_instrlen[insn[0] >> 6];



  /* Fields for various kinds of instructions.  */

  unsigned int b2, r1, r2, x2, r3;

  int i2, d2;



  /* Get current PC and addressing mode bit.  */

  CORE_ADDR pc = regcache_read_pc (regs);

  ULONGEST amode = 0;



  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)

    {

      regcache_cooked_read_unsigned (regs, S390_PSWA_REGNUM, &amode);

      amode &= 0x80000000;

    }



  if (debug_displaced)

    fprintf_unfiltered (gdb_stdlog,

                        "displaced: (s390) fixup (%s, %s) pc %s len %d amode 0x%x\n",

                        paddress (gdbarch, from), paddress (gdbarch, to),

                        paddress (gdbarch, pc), insnlen, (int) amode);



  /* Handle absolute branch and save instructions.  */

  if (is_rr (insn, op_basr, &r1, &r2)

      || is_rx (insn, op_bas, &r1, &d2, &x2, &b2))

    {

      /* Recompute saved return address in R1.  */

      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,

                                      amode | (from + insnlen));

    }



  /* Handle absolute branch instructions.  */

  else if (is_rr (insn, op_bcr, &r1, &r2)

           || is_rx (insn, op_bc, &r1, &d2, &x2, &b2)

           || is_rr (insn, op_bctr, &r1, &r2)

           || is_rre (insn, op_bctgr, &r1, &r2)

           || is_rx (insn, op_bct, &r1, &d2, &x2, &b2)

           || is_rxy (insn, op1_bctg, op2_brctg, &r1, &d2, &x2, &b2)

           || is_rs (insn, op_bxh, &r1, &r3, &d2, &b2)

           || is_rsy (insn, op1_bxhg, op2_bxhg, &r1, &r3, &d2, &b2)

           || is_rs (insn, op_bxle, &r1, &r3, &d2, &b2)

           || is_rsy (insn, op1_bxleg, op2_bxleg, &r1, &r3, &d2, &b2))

    {

      /* Update PC iff branch was *not* taken.  */

      if (pc == to + insnlen)

        regcache_write_pc (regs, from + insnlen);

    }



  /* Handle PC-relative branch and save instructions.  */

  else if (is_ri (insn, op1_bras, op2_bras, &r1, &i2)

           || is_ril (insn, op1_brasl, op2_brasl, &r1, &i2))

    {

      /* Update PC.  */

      regcache_write_pc (regs, pc - to + from);

      /* Recompute saved return address in R1.  */

      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,

                                      amode | (from + insnlen));

    }



  /* Handle PC-relative branch instructions.  */

  else if (is_ri (insn, op1_brc, op2_brc, &r1, &i2)

           || is_ril (insn, op1_brcl, op2_brcl, &r1, &i2)

           || is_ri (insn, op1_brct, op2_brct, &r1, &i2)

           || is_ri (insn, op1_brctg, op2_brctg, &r1, &i2)

           || is_rsi (insn, op_brxh, &r1, &r3, &i2)

           || is_rie (insn, op1_brxhg, op2_brxhg, &r1, &r3, &i2)

           || is_rsi (insn, op_brxle, &r1, &r3, &i2)

           || is_rie (insn, op1_brxlg, op2_brxlg, &r1, &r3, &i2))

    {

      /* Update PC.  */

      regcache_write_pc (regs, pc - to + from);

    }



  /* Handle LOAD ADDRESS RELATIVE LONG.  */

  else if (is_ril (insn, op1_larl, op2_larl, &r1, &i2))

    {

      /* Update PC.  */

      regcache_write_pc (regs, from + insnlen);

      /* Recompute output address in R1.  */

      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,

                                      amode | (from + i2 * 2));

    }



  /* If we executed a breakpoint instruction, point PC right back at it.  */

  else if (insn[0] == 0x0 && insn[1] == 0x1)

    regcache_write_pc (regs, from);



  /* For any other insn, PC points right after the original instruction.  */

  else

    regcache_write_pc (regs, from + insnlen);



  if (debug_displaced)

    fprintf_unfiltered (gdb_stdlog,

                        "displaced: (s390) pc is now %s\n",

                        paddress (gdbarch, regcache_read_pc (regs)));

}





/* Helper routine to unwind pseudo registers.  */



static struct value *

‌s390_unwind_pseudo_register (struct frame_info *this_frame, int regnum)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  struct type *type = register_type (gdbarch, regnum);



  /* Unwind PC via PSW address.  */

  if (regnum == tdep->pc_regnum)

    {

      struct value *val;



      val = frame_unwind_register_value (this_frame, S390_PSWA_REGNUM);

      if (!value_optimized_out (val))

        {

          LONGEST pswa = value_as_long (val);



          if (TYPE_LENGTH (type) == 4)

            return value_from_pointer (type, pswa & 0x7fffffff);

          else

            return value_from_pointer (type, pswa);

        }

    }



  /* Unwind CC via PSW mask.  */

  if (regnum == tdep->cc_regnum)

    {

      struct value *val;



      val = frame_unwind_register_value (this_frame, S390_PSWM_REGNUM);

      if (!value_optimized_out (val))

        {

          LONGEST pswm = value_as_long (val);



          if (TYPE_LENGTH (type) == 4)

            return value_from_longest (type, (pswm >> 12) & 3);

          else

            return value_from_longest (type, (pswm >> 44) & 3);

        }

    }



  /* Unwind full GPRs to show at least the lower halves (as the

     upper halves are undefined).  */

  if (regnum_is_gpr_full (tdep, regnum))

    {

      int reg = regnum - tdep->gpr_full_regnum;

      struct value *val;



      val = frame_unwind_register_value (this_frame, S390_R0_REGNUM + reg);

      if (!value_optimized_out (val))

        return value_cast (type, val);

    }



  return allocate_optimized_out_value (type);

}



static struct value *

‌s390_trad_frame_prev_register (struct frame_info *this_frame,

                               struct trad_frame_saved_reg saved_regs[],

                               int regnum)

{

  if (regnum < S390_NUM_REGS)

    return trad_frame_get_prev_register (this_frame, saved_regs, regnum);

  else

    return s390_unwind_pseudo_register (this_frame, regnum);

}





/* Normal stack frames.  */



‌struct s390_unwind_cache {



  CORE_ADDR func;

  CORE_ADDR frame_base;

  CORE_ADDR local_base;



  struct trad_frame_saved_reg *saved_regs;

};



static int

‌s390_prologue_frame_unwind_cache (struct frame_info *this_frame,

                                  struct s390_unwind_cache *info)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  struct s390_prologue_data data;

  pv_t *fp = &data.gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];

  pv_t *sp = &data.gpr[S390_SP_REGNUM - S390_R0_REGNUM];

  int i;

  CORE_ADDR cfa;

  CORE_ADDR func;

  CORE_ADDR result;

  ULONGEST reg;

  CORE_ADDR prev_sp;

  int frame_pointer;

  int size;

  struct frame_info *next_frame;



  /* Try to find the function start address.  If we can't find it, we don't

     bother searching for it -- with modern compilers this would be mostly

     pointless anyway.  Trust that we'll either have valid DWARF-2 CFI data

     or else a valid backchain ...  */

  func = get_frame_func (this_frame);

  if (!func)

    return 0;



  /* Try to analyze the prologue.  */

  result = s390_analyze_prologue (gdbarch, func,

                                  get_frame_pc (this_frame), &data);

  if (!result)

    return 0;



  /* If this was successful, we should have found the instruction that

     sets the stack pointer register to the previous value of the stack

     pointer minus the frame size.  */

  if (!pv_is_register (*sp, S390_SP_REGNUM))

    return 0;



  /* A frame size of zero at this point can mean either a real

     frameless function, or else a failure to find the prologue.

     Perform some sanity checks to verify we really have a

     frameless function.  */

  if (sp->k == 0)

    {

      /* If the next frame is a NORMAL_FRAME, this frame *cannot* have frame

         size zero.  This is only possible if the next frame is a sentinel

         frame, a dummy frame, or a signal trampoline frame.  */

      /* FIXME: cagney/2004-05-01: This sanity check shouldn't be

         needed, instead the code should simpliy rely on its

         analysis.  */

      next_frame = get_next_frame (this_frame);

      while (next_frame && get_frame_type (next_frame) == INLINE_FRAME)

        next_frame = get_next_frame (next_frame);

      if (next_frame

          && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME)

        return 0;



      /* If we really have a frameless function, %r14 must be valid

         -- in particular, it must point to a different function.  */

      reg = get_frame_register_unsigned (this_frame, S390_RETADDR_REGNUM);

      reg = gdbarch_addr_bits_remove (gdbarch, reg) - 1;

      if (get_pc_function_start (reg) == func)

        {

          /* However, there is one case where it *is* valid for %r14

             to point to the same function -- if this is a recursive

             call, and we have stopped in the prologue *before* the

             stack frame was allocated.



             Recognize this case by looking ahead a bit ...  */



          struct s390_prologue_data data2;

          pv_t *sp = &data2.gpr[S390_SP_REGNUM - S390_R0_REGNUM];



          if (!(s390_analyze_prologue (gdbarch, func, (CORE_ADDR)-1, &data2)

                && pv_is_register (*sp, S390_SP_REGNUM)

                && sp->k != 0))

            return 0;

        }

    }





  /* OK, we've found valid prologue data.  */

  size = -sp->k;



  /* If the frame pointer originally also holds the same value

     as the stack pointer, we're probably using it.  If it holds

     some other value -- even a constant offset -- it is most

     likely used as temp register.  */

  if (pv_is_identical (*sp, *fp))

    frame_pointer = S390_FRAME_REGNUM;

  else

    frame_pointer = S390_SP_REGNUM;



  /* If we've detected a function with stack frame, we'll still have to

     treat it as frameless if we're currently within the function epilog

     code at a point where the frame pointer has already been restored.

     This can only happen in an innermost frame.  */

  /* FIXME: cagney/2004-05-01: This sanity check shouldn't be needed,

     instead the code should simpliy rely on its analysis.  */

  next_frame = get_next_frame (this_frame);

  while (next_frame && get_frame_type (next_frame) == INLINE_FRAME)

    next_frame = get_next_frame (next_frame);

  if (size > 0

      && (next_frame == NULL

          || get_frame_type (get_next_frame (this_frame)) != NORMAL_FRAME))

    {

      /* See the comment in s390_in_function_epilogue_p on why this is

         not completely reliable ...  */

      if (s390_in_function_epilogue_p (gdbarch, get_frame_pc (this_frame)))

        {

          memset (&data, 0, sizeof (data));

          size = 0;

          frame_pointer = S390_SP_REGNUM;

        }

    }



  /* Once we know the frame register and the frame size, we can unwind

     the current value of the frame register from the next frame, and

     add back the frame size to arrive that the previous frame's

     stack pointer value.  */

  prev_sp = get_frame_register_unsigned (this_frame, frame_pointer) + size;

  cfa = prev_sp + 16*word_size + 32;



  /* Set up ABI call-saved/call-clobbered registers.  */

  for (i = 0; i < S390_NUM_REGS; i++)

    if (!s390_register_call_saved (gdbarch, i))

      trad_frame_set_unknown (info->saved_regs, i);



  /* CC is always call-clobbered.  */

  trad_frame_set_unknown (info->saved_regs, S390_PSWM_REGNUM);



  /* Record the addresses of all register spill slots the prologue parser

     has recognized.  Consider only registers defined as call-saved by the

     ABI; for call-clobbered registers the parser may have recognized

     spurious stores.  */



  for (i = 0; i < 16; i++)

    if (s390_register_call_saved (gdbarch, S390_R0_REGNUM + i)

        && data.gpr_slot[i] != 0)

      info->saved_regs[S390_R0_REGNUM + i].addr = cfa - data.gpr_slot[i];



  for (i = 0; i < 16; i++)

    if (s390_register_call_saved (gdbarch, S390_F0_REGNUM + i)

        && data.fpr_slot[i] != 0)

      info->saved_regs[S390_F0_REGNUM + i].addr = cfa - data.fpr_slot[i];



  /* Function return will set PC to %r14.  */

  info->saved_regs[S390_PSWA_REGNUM] = info->saved_regs[S390_RETADDR_REGNUM];



  /* In frameless functions, we unwind simply by moving the return

     address to the PC.  However, if we actually stored to the

     save area, use that -- we might only think the function frameless

     because we're in the middle of the prologue ...  */

  if (size == 0

      && !trad_frame_addr_p (info->saved_regs, S390_PSWA_REGNUM))

    {

      info->saved_regs[S390_PSWA_REGNUM].realreg = S390_RETADDR_REGNUM;

    }



  /* Another sanity check: unless this is a frameless function,

     we should have found spill slots for SP and PC.

     If not, we cannot unwind further -- this happens e.g. in

     libc's thread_start routine.  */

  if (size > 0)

    {

      if (!trad_frame_addr_p (info->saved_regs, S390_SP_REGNUM)

          || !trad_frame_addr_p (info->saved_regs, S390_PSWA_REGNUM))

        prev_sp = -1;

    }



  /* We use the current value of the frame register as local_base,

     and the top of the register save area as frame_base.  */

  if (prev_sp != -1)

    {

      info->frame_base = prev_sp + 16*word_size + 32;

      info->local_base = prev_sp - size;

    }



  info->func = func;

  return 1;

}



static void

‌s390_backchain_frame_unwind_cache (struct frame_info *this_frame,

                                   struct s390_unwind_cache *info)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  CORE_ADDR backchain;

  ULONGEST reg;

  LONGEST sp;

  int i;



  /* Set up ABI call-saved/call-clobbered registers.  */

  for (i = 0; i < S390_NUM_REGS; i++)

    if (!s390_register_call_saved (gdbarch, i))

      trad_frame_set_unknown (info->saved_regs, i);



  /* CC is always call-clobbered.  */

  trad_frame_set_unknown (info->saved_regs, S390_PSWM_REGNUM);



  /* Get the backchain.  */

  reg = get_frame_register_unsigned (this_frame, S390_SP_REGNUM);

  backchain = read_memory_unsigned_integer (reg, word_size, byte_order);



  /* A zero backchain terminates the frame chain.  As additional

     sanity check, let's verify that the spill slot for SP in the

     save area pointed to by the backchain in fact links back to

     the save area.  */

  if (backchain != 0

      && safe_read_memory_integer (backchain + 15*word_size,

                                   word_size, byte_order, &sp)

      && (CORE_ADDR)sp == backchain)

    {

      /* We don't know which registers were saved, but it will have

         to be at least %r14 and %r15.  This will allow us to continue

         unwinding, but other prev-frame registers may be incorrect ...  */

      info->saved_regs[S390_SP_REGNUM].addr = backchain + 15*word_size;

      info->saved_regs[S390_RETADDR_REGNUM].addr = backchain + 14*word_size;



      /* Function return will set PC to %r14.  */

      info->saved_regs[S390_PSWA_REGNUM]

        = info->saved_regs[S390_RETADDR_REGNUM];



      /* We use the current value of the frame register as local_base,

         and the top of the register save area as frame_base.  */

      info->frame_base = backchain + 16*word_size + 32;

      info->local_base = reg;

    }



  info->func = get_frame_pc (this_frame);

}



static struct s390_unwind_cache *

‌s390_frame_unwind_cache (struct frame_info *this_frame,

                         void **this_prologue_cache)

{

  volatile struct gdb_exception ex;

  struct s390_unwind_cache *info;



  if (*this_prologue_cache)

    return *this_prologue_cache;



  info = FRAME_OBSTACK_ZALLOC (struct s390_unwind_cache);

  *this_prologue_cache = info;

  info->saved_regs = trad_frame_alloc_saved_regs (this_frame);

  info->func = -1;

  info->frame_base = -1;

  info->local_base = -1;



  TRY_CATCH (ex, RETURN_MASK_ERROR)

    {

      /* Try to use prologue analysis to fill the unwind cache.

         If this fails, fall back to reading the stack backchain.  */

      if (!s390_prologue_frame_unwind_cache (this_frame, info))

        s390_backchain_frame_unwind_cache (this_frame, info);

    }

  if (ex.reason < 0 && ex.error != NOT_AVAILABLE_ERROR)

    throw_exception (ex);



  return info;

}



static void

‌s390_frame_this_id (struct frame_info *this_frame,

                    void **this_prologue_cache,

                    struct frame_id *this_id)

{

  struct s390_unwind_cache *info

    = s390_frame_unwind_cache (this_frame, this_prologue_cache);



  if (info->frame_base == -1)

    return;



  *this_id = frame_id_build (info->frame_base, info->func);

}



static struct value *

‌s390_frame_prev_register (struct frame_info *this_frame,

                          void **this_prologue_cache, int regnum)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  struct s390_unwind_cache *info

    = s390_frame_unwind_cache (this_frame, this_prologue_cache);



  return s390_trad_frame_prev_register (this_frame, info->saved_regs, regnum);

}



‌static const struct frame_unwind s390_frame_unwind = {

  NORMAL_FRAME,

  default_frame_unwind_stop_reason,

  s390_frame_this_id,

  s390_frame_prev_register,

  NULL,

  default_frame_sniffer

};





/* Code stubs and their stack frames.  For things like PLTs and NULL

   function calls (where there is no true frame and the return address

   is in the RETADDR register).  */



‌struct s390_stub_unwind_cache

{

  CORE_ADDR frame_base;

  struct trad_frame_saved_reg *saved_regs;

};



static struct s390_stub_unwind_cache *

‌s390_stub_frame_unwind_cache (struct frame_info *this_frame,

                              void **this_prologue_cache)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  struct s390_stub_unwind_cache *info;

  ULONGEST reg;



  if (*this_prologue_cache)

    return *this_prologue_cache;



  info = FRAME_OBSTACK_ZALLOC (struct s390_stub_unwind_cache);

  *this_prologue_cache = info;

  info->saved_regs = trad_frame_alloc_saved_regs (this_frame);



  /* The return address is in register %r14.  */

  info->saved_regs[S390_PSWA_REGNUM].realreg = S390_RETADDR_REGNUM;



  /* Retrieve stack pointer and determine our frame base.  */

  reg = get_frame_register_unsigned (this_frame, S390_SP_REGNUM);

  info->frame_base = reg + 16*word_size + 32;



  return info;

}



static void

‌s390_stub_frame_this_id (struct frame_info *this_frame,

                         void **this_prologue_cache,

                         struct frame_id *this_id)

{

  struct s390_stub_unwind_cache *info

    = s390_stub_frame_unwind_cache (this_frame, this_prologue_cache);

  *this_id = frame_id_build (info->frame_base, get_frame_pc (this_frame));

}



static struct value *

‌s390_stub_frame_prev_register (struct frame_info *this_frame,

                               void **this_prologue_cache, int regnum)

{

  struct s390_stub_unwind_cache *info

    = s390_stub_frame_unwind_cache (this_frame, this_prologue_cache);

  return s390_trad_frame_prev_register (this_frame, info->saved_regs, regnum);

}



static int

‌s390_stub_frame_sniffer (const struct frame_unwind *self,

                         struct frame_info *this_frame,

                         void **this_prologue_cache)

{

  CORE_ADDR addr_in_block;

  bfd_byte insn[S390_MAX_INSTR_SIZE];



  /* If the current PC points to non-readable memory, we assume we

     have trapped due to an invalid function pointer call.  We handle

     the non-existing current function like a PLT stub.  */

  addr_in_block = get_frame_address_in_block (this_frame);

  if (in_plt_section (addr_in_block)

      || s390_readinstruction (insn, get_frame_pc (this_frame)) < 0)

    return 1;

  return 0;

}



‌static const struct frame_unwind s390_stub_frame_unwind = {

  NORMAL_FRAME,

  default_frame_unwind_stop_reason,

  s390_stub_frame_this_id,

  s390_stub_frame_prev_register,

  NULL,

  s390_stub_frame_sniffer

};





/* Signal trampoline stack frames.  */



‌struct s390_sigtramp_unwind_cache {

  CORE_ADDR frame_base;

  struct trad_frame_saved_reg *saved_regs;

};



static struct s390_sigtramp_unwind_cache *

‌s390_sigtramp_frame_unwind_cache (struct frame_info *this_frame,

                                  void **this_prologue_cache)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  struct s390_sigtramp_unwind_cache *info;

  ULONGEST this_sp, prev_sp;

  CORE_ADDR next_ra, next_cfa, sigreg_ptr, sigreg_high_off;

  int i;



  if (*this_prologue_cache)

    return *this_prologue_cache;



  info = FRAME_OBSTACK_ZALLOC (struct s390_sigtramp_unwind_cache);

  *this_prologue_cache = info;

  info->saved_regs = trad_frame_alloc_saved_regs (this_frame);



  this_sp = get_frame_register_unsigned (this_frame, S390_SP_REGNUM);

  next_ra = get_frame_pc (this_frame);

  next_cfa = this_sp + 16*word_size + 32;



  /* New-style RT frame:

        retcode + alignment (8 bytes)

        siginfo (128 bytes)

        ucontext (contains sigregs at offset 5 words).  */

  if (next_ra == next_cfa)

    {

      sigreg_ptr = next_cfa + 8 + 128 + align_up (5*word_size, 8);

      /* sigregs are followed by uc_sigmask (8 bytes), then by the

         upper GPR halves if present.  */

      sigreg_high_off = 8;

    }



  /* Old-style RT frame and all non-RT frames:

        old signal mask (8 bytes)

        pointer to sigregs.  */

  else

    {

      sigreg_ptr = read_memory_unsigned_integer (next_cfa + 8,

                                                 word_size, byte_order);

      /* sigregs are followed by signo (4 bytes), then by the

         upper GPR halves if present.  */

      sigreg_high_off = 4;

    }



  /* The sigregs structure looks like this:

            long   psw_mask;

            long   psw_addr;

            long   gprs[16];

            int    acrs[16];

            int    fpc;

            int    __pad;

            double fprs[16];  */



  /* PSW mask and address.  */

  info->saved_regs[S390_PSWM_REGNUM].addr = sigreg_ptr;

  sigreg_ptr += word_size;

  info->saved_regs[S390_PSWA_REGNUM].addr = sigreg_ptr;

  sigreg_ptr += word_size;



  /* Then the GPRs.  */

  for (i = 0; i < 16; i++)

    {

      info->saved_regs[S390_R0_REGNUM + i].addr = sigreg_ptr;

      sigreg_ptr += word_size;

    }



  /* Then the ACRs.  */

  for (i = 0; i < 16; i++)

    {

      info->saved_regs[S390_A0_REGNUM + i].addr = sigreg_ptr;

      sigreg_ptr += 4;

    }



  /* The floating-point control word.  */

  info->saved_regs[S390_FPC_REGNUM].addr = sigreg_ptr;

  sigreg_ptr += 8;



  /* And finally the FPRs.  */

  for (i = 0; i < 16; i++)

    {

      info->saved_regs[S390_F0_REGNUM + i].addr = sigreg_ptr;

      sigreg_ptr += 8;

    }



  /* If we have them, the GPR upper halves are appended at the end.  */

  sigreg_ptr += sigreg_high_off;

  if (tdep->gpr_full_regnum != -1)

    for (i = 0; i < 16; i++)

      {

        info->saved_regs[S390_R0_UPPER_REGNUM + i].addr = sigreg_ptr;

        sigreg_ptr += 4;

      }



  /* Restore the previous frame's SP.  */

  prev_sp = read_memory_unsigned_integer (

                        info->saved_regs[S390_SP_REGNUM].addr,

                        word_size, byte_order);



  /* Determine our frame base.  */

  info->frame_base = prev_sp + 16*word_size + 32;



  return info;

}



static void

‌s390_sigtramp_frame_this_id (struct frame_info *this_frame,

                             void **this_prologue_cache,

                             struct frame_id *this_id)

{

  struct s390_sigtramp_unwind_cache *info

    = s390_sigtramp_frame_unwind_cache (this_frame, this_prologue_cache);

  *this_id = frame_id_build (info->frame_base, get_frame_pc (this_frame));

}



static struct value *

‌s390_sigtramp_frame_prev_register (struct frame_info *this_frame,

                                   void **this_prologue_cache, int regnum)

{

  struct s390_sigtramp_unwind_cache *info

    = s390_sigtramp_frame_unwind_cache (this_frame, this_prologue_cache);

  return s390_trad_frame_prev_register (this_frame, info->saved_regs, regnum);

}



static int

‌s390_sigtramp_frame_sniffer (const struct frame_unwind *self,

                             struct frame_info *this_frame,

                             void **this_prologue_cache)

{

  CORE_ADDR pc = get_frame_pc (this_frame);

  bfd_byte sigreturn[2];



  if (target_read_memory (pc, sigreturn, 2))

    return 0;



  if (sigreturn[0] != op_svc)

    return 0;



  if (sigreturn[1] != 119 /* sigreturn */

      && sigreturn[1] != 173 /* rt_sigreturn */)

    return 0;



  return 1;

}



‌static const struct frame_unwind s390_sigtramp_frame_unwind = {

  SIGTRAMP_FRAME,

  default_frame_unwind_stop_reason,

  s390_sigtramp_frame_this_id,

  s390_sigtramp_frame_prev_register,

  NULL,

  s390_sigtramp_frame_sniffer

};



/* Retrieve the syscall number at a ptrace syscall-stop.  Return -1

   upon error. */



static LONGEST

‌s390_linux_get_syscall_number (struct gdbarch *gdbarch,

                               ptid_t ptid)

{

  struct regcache *regs = get_thread_regcache (ptid);

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  ULONGEST pc;

  ULONGEST svc_number = -1;

  unsigned opcode;



  /* Assume that the PC points after the 2-byte SVC instruction.  We

     don't currently support SVC via EXECUTE. */

  regcache_cooked_read_unsigned (regs, tdep->pc_regnum, &pc);

  pc -= 2;

  opcode = read_memory_unsigned_integer ((CORE_ADDR) pc, 1, byte_order);

  if (opcode != op_svc)

    return -1;



  svc_number = read_memory_unsigned_integer ((CORE_ADDR) pc + 1, 1,

                                             byte_order);

  if (svc_number == 0)

    regcache_cooked_read_unsigned (regs, S390_R1_REGNUM, &svc_number);



  return svc_number;

}





/* Frame base handling.  */



static CORE_ADDR

‌s390_frame_base_address (struct frame_info *this_frame, void **this_cache)

{

  struct s390_unwind_cache *info

    = s390_frame_unwind_cache (this_frame, this_cache);

  return info->frame_base;

}



static CORE_ADDR

‌s390_local_base_address (struct frame_info *this_frame, void **this_cache)

{

  struct s390_unwind_cache *info

    = s390_frame_unwind_cache (this_frame, this_cache);

  return info->local_base;

}



‌static const struct frame_base s390_frame_base = {

  &s390_frame_unwind,

  s390_frame_base_address,

  s390_local_base_address,

  s390_local_base_address

};



static CORE_ADDR

‌s390_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  ULONGEST pc;

  pc = frame_unwind_register_unsigned (next_frame, tdep->pc_regnum);

  return gdbarch_addr_bits_remove (gdbarch, pc);

}



static CORE_ADDR

‌s390_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)

{

  ULONGEST sp;

  sp = frame_unwind_register_unsigned (next_frame, S390_SP_REGNUM);

  return gdbarch_addr_bits_remove (gdbarch, sp);

}





/* DWARF-2 frame support.  */



static struct value *

‌s390_dwarf2_prev_register (struct frame_info *this_frame, void **this_cache,

                           int regnum)

{

  return s390_unwind_pseudo_register (this_frame, regnum);

}



static void

‌s390_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,

                            struct dwarf2_frame_state_reg *reg,

                            struct frame_info *this_frame)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);



  /* The condition code (and thus PSW mask) is call-clobbered.  */

  if (regnum == S390_PSWM_REGNUM)

    reg->how = DWARF2_FRAME_REG_UNDEFINED;



  /* The PSW address unwinds to the return address.  */

  else if (regnum == S390_PSWA_REGNUM)

    reg->how = DWARF2_FRAME_REG_RA;



  /* Fixed registers are call-saved or call-clobbered

     depending on the ABI in use.  */

  else if (regnum < S390_NUM_REGS)

    {

      if (s390_register_call_saved (gdbarch, regnum))

        reg->how = DWARF2_FRAME_REG_SAME_VALUE;

      else

        reg->how = DWARF2_FRAME_REG_UNDEFINED;

    }



  /* We install a special function to unwind pseudos.  */

  else

    {

      reg->how = DWARF2_FRAME_REG_FN;

      reg->loc.fn = s390_dwarf2_prev_register;

    }

}





/* Dummy function calls.  */



/* Return non-zero if TYPE is an integer-like type, zero otherwise.

   "Integer-like" types are those that should be passed the way

   integers are: integers, enums, ranges, characters, and booleans.  */

static int

‌is_integer_like (struct type *type)

{

  enum type_code code = TYPE_CODE (type);



  return (code == TYPE_CODE_INT

          || code == TYPE_CODE_ENUM

          || code == TYPE_CODE_RANGE

          || code == TYPE_CODE_CHAR

          || code == TYPE_CODE_BOOL);

}



/* Return non-zero if TYPE is a pointer-like type, zero otherwise.

   "Pointer-like" types are those that should be passed the way

   pointers are: pointers and references.  */

static int

‌is_pointer_like (struct type *type)

{

  enum type_code code = TYPE_CODE (type);



  return (code == TYPE_CODE_PTR

          || code == TYPE_CODE_REF);

}





/* Return non-zero if TYPE is a `float singleton' or `double

   singleton', zero otherwise.



   A `T singleton' is a struct type with one member, whose type is

   either T or a `T singleton'.  So, the following are all float

   singletons:



   struct { float x };

   struct { struct { float x; } x; };

   struct { struct { struct { float x; } x; } x; };



   ... and so on.



   All such structures are passed as if they were floats or doubles,

   as the (revised) ABI says.  */

static int

‌is_float_singleton (struct type *type)

{

  if (TYPE_CODE (type) == TYPE_CODE_STRUCT && TYPE_NFIELDS (type) == 1)

    {

      struct type *singleton_type = TYPE_FIELD_TYPE (type, 0);

      CHECK_TYPEDEF (singleton_type);



      return (TYPE_CODE (singleton_type) == TYPE_CODE_FLT

              || TYPE_CODE (singleton_type) == TYPE_CODE_DECFLOAT

              || is_float_singleton (singleton_type));

    }



  return 0;

}





/* Return non-zero if TYPE is a struct-like type, zero otherwise.

   "Struct-like" types are those that should be passed as structs are:

   structs and unions.



   As an odd quirk, not mentioned in the ABI, GCC passes float and

   double singletons as if they were a plain float, double, etc.  (The

   corresponding union types are handled normally.)  So we exclude

   those types here.  *shrug* */

static int

‌is_struct_like (struct type *type)

{

  enum type_code code = TYPE_CODE (type);



  return (code == TYPE_CODE_UNION

          || (code == TYPE_CODE_STRUCT && ! is_float_singleton (type)));

}





/* Return non-zero if TYPE is a float-like type, zero otherwise.

   "Float-like" types are those that should be passed as

   floating-point values are.



   You'd think this would just be floats, doubles, long doubles, etc.

   But as an odd quirk, not mentioned in the ABI, GCC passes float and

   double singletons as if they were a plain float, double, etc.  (The

   corresponding union types are handled normally.)  So we include

   those types here.  *shrug* */

static int

‌is_float_like (struct type *type)

{

  return (TYPE_CODE (type) == TYPE_CODE_FLT

          || TYPE_CODE (type) == TYPE_CODE_DECFLOAT

          || is_float_singleton (type));

}





static int

‌is_power_of_two (unsigned int n)

{

  return ((n & (n - 1)) == 0);

}



/* Return non-zero if TYPE should be passed as a pointer to a copy,

   zero otherwise.  */

static int

‌s390_function_arg_pass_by_reference (struct type *type)

{

  if (TYPE_LENGTH (type) > 8)

    return 1;



  return (is_struct_like (type) && !is_power_of_two (TYPE_LENGTH (type)))

          || TYPE_CODE (type) == TYPE_CODE_COMPLEX

          || (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type));

}



/* Return non-zero if TYPE should be passed in a float register

   if possible.  */

static int

‌s390_function_arg_float (struct type *type)

{

  if (TYPE_LENGTH (type) > 8)

    return 0;



  return is_float_like (type);

}



/* Return non-zero if TYPE should be passed in an integer register

   (or a pair of integer registers) if possible.  */

static int

‌s390_function_arg_integer (struct type *type)

{

  if (TYPE_LENGTH (type) > 8)

    return 0;



   return is_integer_like (type)

          || is_pointer_like (type)

          || (is_struct_like (type) && is_power_of_two (TYPE_LENGTH (type)));

}



/* Return ARG, a `SIMPLE_ARG', sign-extended or zero-extended to a full

   word as required for the ABI.  */

static LONGEST

‌extend_simple_arg (struct gdbarch *gdbarch, struct value *arg)

{

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  struct type *type = check_typedef (value_type (arg));



  /* Even structs get passed in the least significant bits of the

     register / memory word.  It's not really right to extract them as

     an integer, but it does take care of the extension.  */

  if (TYPE_UNSIGNED (type))

    return extract_unsigned_integer (value_contents (arg),

                                     TYPE_LENGTH (type), byte_order);

  else

    return extract_signed_integer (value_contents (arg),

                                   TYPE_LENGTH (type), byte_order);

}





/* Return the alignment required by TYPE.  */

static int

‌alignment_of (struct type *type)

{

  int alignment;



  if (is_integer_like (type)

      || is_pointer_like (type)

      || TYPE_CODE (type) == TYPE_CODE_FLT

      || TYPE_CODE (type) == TYPE_CODE_DECFLOAT)

    alignment = TYPE_LENGTH (type);

  else if (TYPE_CODE (type) == TYPE_CODE_STRUCT

           || TYPE_CODE (type) == TYPE_CODE_UNION)

    {

      int i;



      alignment = 1;

      for (i = 0; i < TYPE_NFIELDS (type); i++)

        {

          int field_alignment

            = alignment_of (check_typedef (TYPE_FIELD_TYPE (type, i)));



          if (field_alignment > alignment)

            alignment = field_alignment;

        }

    }

  else

    alignment = 1;



  /* Check that everything we ever return is a power of two.  Lots of

     code doesn't want to deal with aligning things to arbitrary

     boundaries.  */

  gdb_assert ((alignment & (alignment - 1)) == 0);



  return alignment;

}





/* Put the actual parameter values pointed to by ARGS[0..NARGS-1] in

   place to be passed to a function, as specified by the "GNU/Linux

   for S/390 ELF Application Binary Interface Supplement".



   SP is the current stack pointer.  We must put arguments, links,

   padding, etc. whereever they belong, and return the new stack

   pointer value.



   If STRUCT_RETURN is non-zero, then the function we're calling is

   going to return a structure by value; STRUCT_ADDR is the address of

   a block we've allocated for it on the stack.



   Our caller has taken care of any type promotions needed to satisfy

   prototypes or the old K&R argument-passing rules.  */

static CORE_ADDR

‌s390_push_dummy_call (struct gdbarch *gdbarch, struct value *function,

                      struct regcache *regcache, CORE_ADDR bp_addr,

                      int nargs, struct value **args, CORE_ADDR sp,

                      int struct_return, CORE_ADDR struct_addr)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  int i;



  /* If the i'th argument is passed as a reference to a copy, then

     copy_addr[i] is the address of the copy we made.  */

  CORE_ADDR *copy_addr = alloca (nargs * sizeof (CORE_ADDR));



  /* Reserve space for the reference-to-copy area.  */

  for (i = 0; i < nargs; i++)

    {

      struct value *arg = args[i];

      struct type *type = check_typedef (value_type (arg));



      if (s390_function_arg_pass_by_reference (type))

        {

          sp -= TYPE_LENGTH (type);

          sp = align_down (sp, alignment_of (type));

          copy_addr[i] = sp;

        }

    }



  /* Reserve space for the parameter area.  As a conservative

     simplification, we assume that everything will be passed on the

     stack.  Since every argument larger than 8 bytes will be

     passed by reference, we use this simple upper bound.  */

  sp -= nargs * 8;



  /* After all that, make sure it's still aligned on an eight-byte

     boundary.  */

  sp = align_down (sp, 8);



  /* Allocate the standard frame areas: the register save area, the

     word reserved for the compiler (which seems kind of meaningless),

     and the back chain pointer.  */

  sp -= 16*word_size + 32;



  /* Now we have the final SP value.  Make sure we didn't underflow;

     on 31-bit, this would result in addresses with the high bit set,

     which causes confusion elsewhere.  Note that if we error out

     here, stack and registers remain untouched.  */

  if (gdbarch_addr_bits_remove (gdbarch, sp) != sp)

    error (_("Stack overflow"));





  /* Finally, place the actual parameters, working from SP towards

     higher addresses.  The code above is supposed to reserve enough

     space for this.  */

  {

    int fr = 0;

    int gr = 2;

    CORE_ADDR starg = sp + 16*word_size + 32;



    /* A struct is returned using general register 2.  */

    if (struct_return)

      {

        regcache_cooked_write_unsigned (regcache, S390_R0_REGNUM + gr,

                                        struct_addr);

        gr++;

      }



    for (i = 0; i < nargs; i++)

      {

        struct value *arg = args[i];

        struct type *type = check_typedef (value_type (arg));

        unsigned length = TYPE_LENGTH (type);



        if (s390_function_arg_pass_by_reference (type))

          {

            /* Actually copy the argument contents to the stack slot

               that was reserved above.  */

            write_memory (copy_addr[i], value_contents (arg), length);



            if (gr <= 6)

              {

                regcache_cooked_write_unsigned (regcache, S390_R0_REGNUM + gr,

                                                copy_addr[i]);

                gr++;

              }

            else

              {

                write_memory_unsigned_integer (starg, word_size, byte_order,

                                               copy_addr[i]);

                starg += word_size;

              }

          }

        else if (s390_function_arg_float (type))

          {

            /* The GNU/Linux for S/390 ABI uses FPRs 0 and 2 to pass arguments,

               the GNU/Linux for zSeries ABI uses 0, 2, 4, and 6.  */

            if (fr <= (tdep->abi == ABI_LINUX_S390 ? 2 : 6))

              {

                /* When we store a single-precision value in an FP register,

                   it occupies the leftmost bits.  */

                regcache_cooked_write_part (regcache, S390_F0_REGNUM + fr,

                                            0, length, value_contents (arg));

                fr += 2;

              }

            else

              {

                /* When we store a single-precision value in a stack slot,

                   it occupies the rightmost bits.  */

                starg = align_up (starg + length, word_size);

                write_memory (starg - length, value_contents (arg), length);

              }

          }

        else if (s390_function_arg_integer (type) && length <= word_size)

          {

            if (gr <= 6)

              {

                /* Integer arguments are always extended to word size.  */

                regcache_cooked_write_signed (regcache, S390_R0_REGNUM + gr,

                                              extend_simple_arg (gdbarch,

                                                                 arg));

                gr++;

              }

            else

              {

                /* Integer arguments are always extended to word size.  */

                write_memory_signed_integer (starg, word_size, byte_order,

                                             extend_simple_arg (gdbarch, arg));

                starg += word_size;

              }

          }

        else if (s390_function_arg_integer (type) && length == 2*word_size)

          {

            if (gr <= 5)

              {

                regcache_cooked_write (regcache, S390_R0_REGNUM + gr,

                                       value_contents (arg));

                regcache_cooked_write (regcache, S390_R0_REGNUM + gr + 1,

                                       value_contents (arg) + word_size);

                gr += 2;

              }

            else

              {

                /* If we skipped r6 because we couldn't fit a DOUBLE_ARG

                   in it, then don't go back and use it again later.  */

                gr = 7;



                write_memory (starg, value_contents (arg), length);

                starg += length;

              }

          }

        else

          internal_error (__FILE__, __LINE__, _("unknown argument type"));

      }

  }



  /* Store return PSWA.  In 31-bit mode, keep addressing mode bit.  */

  if (word_size == 4)

    {

      ULONGEST pswa;

      regcache_cooked_read_unsigned (regcache, S390_PSWA_REGNUM, &pswa);

      bp_addr = (bp_addr & 0x7fffffff) | (pswa & 0x80000000);

    }

  regcache_cooked_write_unsigned (regcache, S390_RETADDR_REGNUM, bp_addr);



  /* Store updated stack pointer.  */

  regcache_cooked_write_unsigned (regcache, S390_SP_REGNUM, sp);



  /* We need to return the 'stack part' of the frame ID,

     which is actually the top of the register save area.  */

  return sp + 16*word_size + 32;

}



/* Assuming THIS_FRAME is a dummy, return the frame ID of that

   dummy frame.  The frame ID's base needs to match the TOS value

   returned by push_dummy_call, and the PC match the dummy frame's

   breakpoint.  */

static struct frame_id

‌s390_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)

{

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  CORE_ADDR sp = get_frame_register_unsigned (this_frame, S390_SP_REGNUM);

  sp = gdbarch_addr_bits_remove (gdbarch, sp);



  return frame_id_build (sp + 16*word_size + 32,

                         get_frame_pc (this_frame));

}



static CORE_ADDR

‌s390_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)

{

  /* Both the 32- and 64-bit ABI's say that the stack pointer should

     always be aligned on an eight-byte boundary.  */

  return (addr & -8);

}





/* Function return value access.  */



static enum return_value_convention

‌s390_return_value_convention (struct gdbarch *gdbarch, struct type *type)

{

  if (TYPE_LENGTH (type) > 8)

    return RETURN_VALUE_STRUCT_CONVENTION;



  switch (TYPE_CODE (type))

    {

    case TYPE_CODE_STRUCT:

    case TYPE_CODE_UNION:

    case TYPE_CODE_ARRAY:

    case TYPE_CODE_COMPLEX:

      return RETURN_VALUE_STRUCT_CONVENTION;



    default:

      return RETURN_VALUE_REGISTER_CONVENTION;

    }

}



static enum return_value_convention

‌s390_return_value (struct gdbarch *gdbarch, struct value *function,

                   struct type *type, struct regcache *regcache,

                   gdb_byte *out, const gdb_byte *in)

{

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  int word_size = gdbarch_ptr_bit (gdbarch) / 8;

  enum return_value_convention rvc;

  int length;



  type = check_typedef (type);

  rvc = s390_return_value_convention (gdbarch, type);

  length = TYPE_LENGTH (type);



  if (in)

    {

      switch (rvc)

        {

        case RETURN_VALUE_REGISTER_CONVENTION:

          if (TYPE_CODE (type) == TYPE_CODE_FLT

              || TYPE_CODE (type) == TYPE_CODE_DECFLOAT)

            {

              /* When we store a single-precision value in an FP register,

                 it occupies the leftmost bits.  */

              regcache_cooked_write_part (regcache, S390_F0_REGNUM,

                                          0, length, in);

            }

          else if (length <= word_size)

            {

              /* Integer arguments are always extended to word size.  */

              if (TYPE_UNSIGNED (type))

                regcache_cooked_write_unsigned (regcache, S390_R2_REGNUM,

                        extract_unsigned_integer (in, length, byte_order));

              else

                regcache_cooked_write_signed (regcache, S390_R2_REGNUM,

                        extract_signed_integer (in, length, byte_order));

            }

          else if (length == 2*word_size)

            {

              regcache_cooked_write (regcache, S390_R2_REGNUM, in);

              regcache_cooked_write (regcache, S390_R3_REGNUM, in + word_size);

            }

          else

            internal_error (__FILE__, __LINE__, _("invalid return type"));

          break;



        case RETURN_VALUE_STRUCT_CONVENTION:

          error (_("Cannot set function return value."));

          break;

        }

    }

  else if (out)

    {

      switch (rvc)

        {

        case RETURN_VALUE_REGISTER_CONVENTION:

          if (TYPE_CODE (type) == TYPE_CODE_FLT

              || TYPE_CODE (type) == TYPE_CODE_DECFLOAT)

            {

              /* When we store a single-precision value in an FP register,

                 it occupies the leftmost bits.  */

              regcache_cooked_read_part (regcache, S390_F0_REGNUM,

                                         0, length, out);

            }

          else if (length <= word_size)

            {

              /* Integer arguments occupy the rightmost bits.  */

              regcache_cooked_read_part (regcache, S390_R2_REGNUM,

                                         word_size - length, length, out);

            }

          else if (length == 2*word_size)

            {

              regcache_cooked_read (regcache, S390_R2_REGNUM, out);

              regcache_cooked_read (regcache, S390_R3_REGNUM, out + word_size);

            }

          else

            internal_error (__FILE__, __LINE__, _("invalid return type"));

          break;



        case RETURN_VALUE_STRUCT_CONVENTION:

          error (_("Function return value unknown."));

          break;

        }

    }



  return rvc;

}





/* Breakpoints.  */



static const gdb_byte *

‌s390_breakpoint_from_pc (struct gdbarch *gdbarch,

                         CORE_ADDR *pcptr, int *lenptr)

{

  static const gdb_byte breakpoint[] = { 0x0, 0x1 };



  *lenptr = sizeof (breakpoint);

  return breakpoint;

}





/* Address handling.  */



static CORE_ADDR

‌s390_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)

{

  return addr & 0x7fffffff;

}



static int

‌s390_address_class_type_flags (int byte_size, int dwarf2_addr_class)

{

  if (byte_size == 4)

    return TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;

  else

    return 0;

}



static const char *

‌s390_address_class_type_flags_to_name (struct gdbarch *gdbarch, int type_flags)

{

  if (type_flags & TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1)

    return "mode32";

  else

    return NULL;

}



static int

‌s390_address_class_name_to_type_flags (struct gdbarch *gdbarch,

                                       const char *name,

                                       int *type_flags_ptr)

{

  if (strcmp (name, "mode32") == 0)

    {

      *type_flags_ptr = TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;

      return 1;

    }

  else

    return 0;

}



/* Implement gdbarch_gcc_target_options.  GCC does not know "-m32".  */



static char *

‌s390_gcc_target_options (struct gdbarch *gdbarch)

{

  return xstrdup ("-m31");

}



/* Implementation of `gdbarch_stap_is_single_operand', as defined in

   gdbarch.h.  */



static int

‌s390_stap_is_single_operand (struct gdbarch *gdbarch, const char *s)

{

  return ((isdigit (*s) && s[1] == '(' && s[2] == '%') /* Displacement

                                                          or indirection.  */

          || *s == '%' /* Register access.  */

          || isdigit (*s)); /* Literal number.  */

}



/* Set up gdbarch struct.  */



static struct gdbarch *

‌s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)

{

  const struct target_desc *tdesc = info.target_desc;

  struct tdesc_arch_data *tdesc_data = NULL;

  struct gdbarch *gdbarch;

  struct gdbarch_tdep *tdep;

  int tdep_abi;

  int have_upper = 0;

  int have_linux_v1 = 0;

  int have_linux_v2 = 0;

  int have_tdb = 0;

  int first_pseudo_reg, last_pseudo_reg;

  static const char *const stap_register_prefixes[] = { "%", NULL };

  static const char *const stap_register_indirection_prefixes[] = { "(",

                                                                    NULL };

  static const char *const stap_register_indirection_suffixes[] = { ")",

                                                                    NULL };



  /* Default ABI and register size.  */

  switch (info.bfd_arch_info->mach)

    {

    case bfd_mach_s390_31:

      tdep_abi = ABI_LINUX_S390;

      break;



    case bfd_mach_s390_64:

      tdep_abi = ABI_LINUX_ZSERIES;

      break;



    default:

      return NULL;

    }



  /* Use default target description if none provided by the target.  */

  if (!tdesc_has_registers (tdesc))

    {

      if (tdep_abi == ABI_LINUX_S390)

        tdesc = tdesc_s390_linux32;

      else

        tdesc = tdesc_s390x_linux64;

    }



  /* Check any target description for validity.  */

  if (tdesc_has_registers (tdesc))

    {

      static const char *const gprs[] = {

        "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",

        "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"

      };

      static const char *const fprs[] = {

        "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",

        "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15"

      };

      static const char *const acrs[] = {

        "acr0", "acr1", "acr2", "acr3", "acr4", "acr5", "acr6", "acr7",

        "acr8", "acr9", "acr10", "acr11", "acr12", "acr13", "acr14", "acr15"

      };

      static const char *const gprs_lower[] = {

        "r0l", "r1l", "r2l", "r3l", "r4l", "r5l", "r6l", "r7l",

        "r8l", "r9l", "r10l", "r11l", "r12l", "r13l", "r14l", "r15l"

      };

      static const char *const gprs_upper[] = {

        "r0h", "r1h", "r2h", "r3h", "r4h", "r5h", "r6h", "r7h",

        "r8h", "r9h", "r10h", "r11h", "r12h", "r13h", "r14h", "r15h"

      };

      static const char *const tdb_regs[] = {

        "tdb0", "tac", "tct", "atia",

        "tr0", "tr1", "tr2", "tr3", "tr4", "tr5", "tr6", "tr7",

        "tr8", "tr9", "tr10", "tr11", "tr12", "tr13", "tr14", "tr15"

      };

      const struct tdesc_feature *feature;

      int i, valid_p = 1;



      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.core");

      if (feature == NULL)

        return NULL;



      tdesc_data = tdesc_data_alloc ();



      valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                          S390_PSWM_REGNUM, "pswm");

      valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                          S390_PSWA_REGNUM, "pswa");



      if (tdesc_unnumbered_register (feature, "r0"))

        {

          for (i = 0; i < 16; i++)

            valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                                S390_R0_REGNUM + i, gprs[i]);

        }

      else

        {

          have_upper = 1;



          for (i = 0; i < 16; i++)

            valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                                S390_R0_REGNUM + i,

                                                gprs_lower[i]);

          for (i = 0; i < 16; i++)

            valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                                S390_R0_UPPER_REGNUM + i,

                                                gprs_upper[i]);

        }



      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.fpr");

      if (feature == NULL)

        {

          tdesc_data_cleanup (tdesc_data);

          return NULL;

        }



      valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                          S390_FPC_REGNUM, "fpc");

      for (i = 0; i < 16; i++)

        valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                            S390_F0_REGNUM + i, fprs[i]);



      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.acr");

      if (feature == NULL)

        {

          tdesc_data_cleanup (tdesc_data);

          return NULL;

        }



      for (i = 0; i < 16; i++)

        valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                            S390_A0_REGNUM + i, acrs[i]);



      /* Optional GNU/Linux-specific "registers".  */

      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.linux");

      if (feature)

        {

          tdesc_numbered_register (feature, tdesc_data,

                                   S390_ORIG_R2_REGNUM, "orig_r2");



          if (tdesc_numbered_register (feature, tdesc_data,

                                       S390_LAST_BREAK_REGNUM, "last_break"))

            have_linux_v1 = 1;



          if (tdesc_numbered_register (feature, tdesc_data,

                                       S390_SYSTEM_CALL_REGNUM, "system_call"))

            have_linux_v2 = 1;



          if (have_linux_v2 > have_linux_v1)

            valid_p = 0;

        }



      /* Transaction diagnostic block.  */

      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.tdb");

      if (feature)

        {

          for (i = 0; i < ARRAY_SIZE (tdb_regs); i++)

            valid_p &= tdesc_numbered_register (feature, tdesc_data,

                                                S390_TDB_DWORD0_REGNUM + i,

                                                tdb_regs[i]);

          have_tdb = 1;

        }



      if (!valid_p)

        {

          tdesc_data_cleanup (tdesc_data);

          return NULL;

        }

    }



  /* Find a candidate among extant architectures.  */

  for (arches = gdbarch_list_lookup_by_info (arches, &info);

       arches != NULL;

       arches = gdbarch_list_lookup_by_info (arches->next, &info))

    {

      tdep = gdbarch_tdep (arches->gdbarch);

      if (!tdep)

        continue;

      if (tdep->abi != tdep_abi)

        continue;

      if ((tdep->gpr_full_regnum != -1) != have_upper)

        continue;

      if (tdesc_data != NULL)

        tdesc_data_cleanup (tdesc_data);

      return arches->gdbarch;

    }



  /* Otherwise create a new gdbarch for the specified machine type.  */

  tdep = XCNEW (struct gdbarch_tdep);

  tdep->abi = tdep_abi;

  tdep->have_linux_v1 = have_linux_v1;

  tdep->have_linux_v2 = have_linux_v2;

  tdep->have_tdb = have_tdb;

  gdbarch = gdbarch_alloc (&info, tdep);



  set_gdbarch_believe_pcc_promotion (gdbarch, 0);

  set_gdbarch_char_signed (gdbarch, 0);



  /* S/390 GNU/Linux uses either 64-bit or 128-bit long doubles.

     We can safely let them default to 128-bit, since the debug info

     will give the size of type actually used in each case.  */

  set_gdbarch_long_double_bit (gdbarch, 128);

  set_gdbarch_long_double_format (gdbarch, floatformats_ia64_quad);



  /* Amount PC must be decremented by after a breakpoint.  This is

     often the number of bytes returned by gdbarch_breakpoint_from_pc but not

     always.  */

  set_gdbarch_decr_pc_after_break (gdbarch, 2);

  /* Stack grows downward.  */

  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);

  set_gdbarch_breakpoint_from_pc (gdbarch, s390_breakpoint_from_pc);

  set_gdbarch_skip_prologue (gdbarch, s390_skip_prologue);

  set_gdbarch_in_function_epilogue_p (gdbarch, s390_in_function_epilogue_p);



  set_gdbarch_num_regs (gdbarch, S390_NUM_REGS);

  set_gdbarch_sp_regnum (gdbarch, S390_SP_REGNUM);

  set_gdbarch_fp0_regnum (gdbarch, S390_F0_REGNUM);

  set_gdbarch_stab_reg_to_regnum (gdbarch, s390_dwarf_reg_to_regnum);

  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, s390_dwarf_reg_to_regnum);

  set_gdbarch_value_from_register (gdbarch, s390_value_from_register);

  set_gdbarch_core_read_description (gdbarch, s390_core_read_description);

  set_gdbarch_iterate_over_regset_sections (gdbarch,

                                            s390_iterate_over_regset_sections);

  set_gdbarch_cannot_store_register (gdbarch, s390_cannot_store_register);

  set_gdbarch_write_pc (gdbarch, s390_write_pc);

  set_gdbarch_pseudo_register_read (gdbarch, s390_pseudo_register_read);

  set_gdbarch_pseudo_register_write (gdbarch, s390_pseudo_register_write);

  set_tdesc_pseudo_register_name (gdbarch, s390_pseudo_register_name);

  set_tdesc_pseudo_register_type (gdbarch, s390_pseudo_register_type);

  set_tdesc_pseudo_register_reggroup_p (gdbarch,

                                        s390_pseudo_register_reggroup_p);

  tdesc_use_registers (gdbarch, tdesc, tdesc_data);



  /* Assign pseudo register numbers.  */

  first_pseudo_reg = gdbarch_num_regs (gdbarch);

  last_pseudo_reg = first_pseudo_reg;

  tdep->gpr_full_regnum = -1;

  if (have_upper)

    {

      tdep->gpr_full_regnum = last_pseudo_reg;

      last_pseudo_reg += 16;

    }

  tdep->pc_regnum = last_pseudo_reg++;

  tdep->cc_regnum = last_pseudo_reg++;

  set_gdbarch_pc_regnum (gdbarch, tdep->pc_regnum);

  set_gdbarch_num_pseudo_regs (gdbarch, last_pseudo_reg - first_pseudo_reg);



  /* Inferior function calls.  */

  set_gdbarch_push_dummy_call (gdbarch, s390_push_dummy_call);

  set_gdbarch_dummy_id (gdbarch, s390_dummy_id);

  set_gdbarch_frame_align (gdbarch, s390_frame_align);

  set_gdbarch_return_value (gdbarch, s390_return_value);



  /* Syscall handling.  */

  set_gdbarch_get_syscall_number (gdbarch, s390_linux_get_syscall_number);



  /* Frame handling.  */

  dwarf2_frame_set_init_reg (gdbarch, s390_dwarf2_frame_init_reg);

  dwarf2_frame_set_adjust_regnum (gdbarch, s390_adjust_frame_regnum);

  dwarf2_append_unwinders (gdbarch);

  frame_base_append_sniffer (gdbarch, dwarf2_frame_base_sniffer);

  frame_unwind_append_unwinder (gdbarch, &s390_stub_frame_unwind);

  frame_unwind_append_unwinder (gdbarch, &s390_sigtramp_frame_unwind);

  frame_unwind_append_unwinder (gdbarch, &s390_frame_unwind);

  frame_base_set_default (gdbarch, &s390_frame_base);

  set_gdbarch_unwind_pc (gdbarch, s390_unwind_pc);

  set_gdbarch_unwind_sp (gdbarch, s390_unwind_sp);



  /* Displaced stepping.  */

  set_gdbarch_displaced_step_copy_insn (gdbarch,

                                        simple_displaced_step_copy_insn);

  set_gdbarch_displaced_step_fixup (gdbarch, s390_displaced_step_fixup);

  set_gdbarch_displaced_step_free_closure (gdbarch,

                                           simple_displaced_step_free_closure);

  set_gdbarch_displaced_step_location (gdbarch,

                                       displaced_step_at_entry_point);

  set_gdbarch_max_insn_length (gdbarch, S390_MAX_INSTR_SIZE);



  /* Note that GNU/Linux is the only OS supported on this

     platform.  */

  linux_init_abi (info, gdbarch);



  switch (tdep->abi)

    {

    case ABI_LINUX_S390:

      set_gdbarch_addr_bits_remove (gdbarch, s390_addr_bits_remove);

      set_gdbarch_gcc_target_options (gdbarch, s390_gcc_target_options);

      set_solib_svr4_fetch_link_map_offsets

        (gdbarch, svr4_ilp32_fetch_link_map_offsets);



      set_xml_syscall_file_name (gdbarch, XML_SYSCALL_FILENAME_S390);

      break;



    case ABI_LINUX_ZSERIES:

      set_gdbarch_long_bit (gdbarch, 64);

      set_gdbarch_long_long_bit (gdbarch, 64);

      set_gdbarch_ptr_bit (gdbarch, 64);

      set_solib_svr4_fetch_link_map_offsets

        (gdbarch, svr4_lp64_fetch_link_map_offsets);

      set_gdbarch_address_class_type_flags (gdbarch,

                                            s390_address_class_type_flags);

      set_gdbarch_address_class_type_flags_to_name (gdbarch,

                                                    s390_address_class_type_flags_to_name);

      set_gdbarch_address_class_name_to_type_flags (gdbarch,

                                                    s390_address_class_name_to_type_flags);

      set_xml_syscall_file_name (gdbarch, XML_SYSCALL_FILENAME_S390);

      break;

    }



  set_gdbarch_print_insn (gdbarch, print_insn_s390);



  set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);



  /* Enable TLS support.  */

  set_gdbarch_fetch_tls_load_module_address (gdbarch,

                                             svr4_fetch_objfile_link_map);



  set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type);



  /* SystemTap functions.  */

  set_gdbarch_stap_register_prefixes (gdbarch, stap_register_prefixes);

  set_gdbarch_stap_register_indirection_prefixes (gdbarch,

                                          stap_register_indirection_prefixes);

  set_gdbarch_stap_register_indirection_suffixes (gdbarch,

                                          stap_register_indirection_suffixes);

  set_gdbarch_stap_is_single_operand (gdbarch, s390_stap_is_single_operand);



  return gdbarch;

}





extern initialize_file_ftype _initialize_s390_tdep; /* -Wmissing-prototypes */



void

‌_initialize_s390_tdep (void)

{

  /* Hook us into the gdbarch mechanism.  */

  register_gdbarch_init (bfd_arch_s390, s390_gdbarch_init);



  /* Initialize the GNU/Linux target descriptions.  */

  initialize_tdesc_s390_linux32 ();

  initialize_tdesc_s390_linux32v1 ();

  initialize_tdesc_s390_linux32v2 ();

  initialize_tdesc_s390_linux64 ();

  initialize_tdesc_s390_linux64v1 ();

  initialize_tdesc_s390_linux64v2 ();

  initialize_tdesc_s390_te_linux64 ();

  initialize_tdesc_s390x_linux64 ();

  initialize_tdesc_s390x_linux64v1 ();

  initialize_tdesc_s390x_linux64v2 ();

  initialize_tdesc_s390x_te_linux64 ();

}
gdb/s390-linux-tdep.c - gdb

Global variables defined

Data types defined

Functions defined

Macros defined

Source code
