/* s390-dis.c -- Disassemble S390 instructions
Copyright (C) 2000-2018 Free Software Foundation, Inc.
Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
This file is part of the GNU opcodes library.
This library 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, or (at your option)
any later version.
It 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 file; see the file COPYING. If not, write to the
Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#include "sysdep.h"
#include <stdio.h>
#include "ansidecl.h"
#include "disassemble.h"
#include "opintl.h"
#include "opcode/s390.h"
#include "libiberty.h"
static int opc_index[256];
static int current_arch_mask = 0;
static int option_use_insn_len_bits_p = 0;
typedef struct
{
const char *name;
const char *description;
} s390_options_t;
static const s390_options_t options[] =
{
{ "esa" , N_("Disassemble in ESA architecture mode") },
{ "zarch", N_("Disassemble in z/Architecture mode") },
{ "insnlength", N_("Print unknown instructions according to "
"length from first two bits") }
};
/* Set up index table for first opcode byte. */
void
disassemble_init_s390 (struct disassemble_info *info)
{
int i;
const char *p;
memset (opc_index, 0, sizeof (opc_index));
/* Reverse order, such that each opc_index ends up pointing to the
first matching entry instead of the last. */
for (i = s390_num_opcodes; i--; )
opc_index[s390_opcodes[i].opcode[0]] = i;
current_arch_mask = 1 << S390_OPCODE_ZARCH;
option_use_insn_len_bits_p = 0;
for (p = info->disassembler_options; p != NULL; )
{
if (CONST_STRNEQ (p, "esa"))
current_arch_mask = 1 << S390_OPCODE_ESA;
else if (CONST_STRNEQ (p, "zarch"))
current_arch_mask = 1 << S390_OPCODE_ZARCH;
else if (CONST_STRNEQ (p, "insnlength"))
option_use_insn_len_bits_p = 1;
else
fprintf (stderr, "Unknown S/390 disassembler option: %s\n", p);
p = strchr (p, ',');
if (p != NULL)
p++;
}
}
/* Derive the length of an instruction from its first byte. */
static inline int
s390_insn_length (const bfd_byte *buffer)
{
/* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6. */
return ((buffer[0] >> 6) + 3) & ~1U;
}
/* Match the instruction in BUFFER against the given OPCODE, excluding
the first byte. */
static inline int
s390_insn_matches_opcode (const bfd_byte *buffer,
const struct s390_opcode *opcode)
{
return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
&& (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
&& (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
&& (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
&& (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
}
union operand_value
{
int i;
unsigned int u;
};
/* Extracts an operand value from an instruction. */
/* We do not perform the shift operation for larl-type address
operands here since that would lead to an overflow of the 32 bit
integer value. Instead the shift operation is done when printing
the operand. */
static inline union operand_value
s390_extract_operand (const bfd_byte *insn,
const struct s390_operand *operand)
{
union operand_value ret;
unsigned int val;
int bits;
const bfd_byte *orig_insn = insn;
/* Extract fragments of the operand byte for byte. */
insn += operand->shift / 8;
bits = (operand->shift & 7) + operand->bits;
val = 0;
do
{
val <<= 8;
val |= (unsigned int) *insn++;
bits -= 8;
}
while (bits > 0);
val >>= -bits;
val &= ((1U << (operand->bits - 1)) << 1) - 1;
/* Check for special long displacement case. */
if (operand->bits == 20 && operand->shift == 20)
val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
/* Sign extend value if the operand is signed or pc relative. Avoid
integer overflows. */
if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
{
unsigned int m = 1U << (operand->bits - 1);
if (val >= m)
ret.i = (int) (val - m) - 1 - (int) (m - 1U);
else
ret.i = (int) val;
}
else if (operand->flags & S390_OPERAND_LENGTH)
/* Length x in an instruction has real length x + 1. */
ret.u = val + 1;
else if (operand->flags & S390_OPERAND_VR)
{
/* Extract the extra bits for a vector register operand stored
in the RXB field. */
unsigned vr = operand->shift == 32 ? 3
: (unsigned) operand->shift / 4 - 2;
ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));
}
else
ret.u = val;
return ret;
}
/* Print the S390 instruction in BUFFER, assuming that it matches the
given OPCODE. */
static void
s390_print_insn_with_opcode (bfd_vma memaddr,
struct disassemble_info *info,
const bfd_byte *buffer,
const struct s390_opcode *opcode)
{
const unsigned char *opindex;
char separator;
/* Mnemonic. */
info->fprintf_func (info->stream, "%s", opcode->name);
/* Operands. */
separator = '\t';
for (opindex = opcode->operands; *opindex != 0; opindex++)
{
const struct s390_operand *operand = s390_operands + *opindex;
union operand_value val = s390_extract_operand (buffer, operand);
unsigned long flags = operand->flags;
if ((flags & S390_OPERAND_INDEX) && val.u == 0)
continue;
if ((flags & S390_OPERAND_BASE) &&
val.u == 0 && separator == '(')
{
separator = ',';
continue;
}
/* For instructions with a last optional operand don't print it
if zero. */
if ((opcode->flags & (S390_INSTR_FLAG_OPTPARM | S390_INSTR_FLAG_OPTPARM2))
&& val.u == 0
&& opindex[1] == 0)
break;
if ((opcode->flags & S390_INSTR_FLAG_OPTPARM2)
&& val.u == 0 && opindex[1] != 0 && opindex[2] == 0)
{
union operand_value next_op_val =
s390_extract_operand (buffer, s390_operands + opindex[1]);
if (next_op_val.u == 0)
break;
}
if (flags & S390_OPERAND_GPR)
info->fprintf_func (info->stream, "%c%%r%u", separator, val.u);
else if (flags & S390_OPERAND_FPR)
info->fprintf_func (info->stream, "%c%%f%u", separator, val.u);
else if (flags & S390_OPERAND_VR)
info->fprintf_func (info->stream, "%c%%v%i", separator, val.u);
else if (flags & S390_OPERAND_AR)
info->fprintf_func (info->stream, "%c%%a%u", separator, val.u);
else if (flags & S390_OPERAND_CR)
info->fprintf_func (info->stream, "%c%%c%u", separator, val.u);
else if (flags & S390_OPERAND_PCREL)
{
info->fprintf_func (info->stream, "%c", separator);
info->print_address_func (memaddr + val.i + val.i, info);
}
else if (flags & S390_OPERAND_SIGNED)
info->fprintf_func (info->stream, "%c%i", separator, val.i);
else
{
if (flags & S390_OPERAND_OR1)
val.u &= ~1;
if (flags & S390_OPERAND_OR2)
val.u &= ~2;
if (flags & S390_OPERAND_OR8)
val.u &= ~8;
if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
&& val.u == 0
&& opindex[1] == 0)
break;
info->fprintf_func (info->stream, "%c%u", separator, val.u);
}
if (flags & S390_OPERAND_DISP)
separator = '(';
else if (flags & S390_OPERAND_BASE)
{
info->fprintf_func (info->stream, ")");
separator = ',';
}
else
separator = ',';
}
}
/* Check whether opcode A's mask is more specific than that of B. */
static int
opcode_mask_more_specific (const struct s390_opcode *a,
const struct s390_opcode *b)
{
return (((int) a->mask[0] + a->mask[1] + a->mask[2]
+ a->mask[3] + a->mask[4] + a->mask[5])
> ((int) b->mask[0] + b->mask[1] + b->mask[2]
+ b->mask[3] + b->mask[4] + b->mask[5]));
}
/* Print a S390 instruction. */
int
print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
{
bfd_byte buffer[6];
const struct s390_opcode *opcode = NULL;
unsigned int value;
int status, opsize, bufsize, bytes_to_dump, i;
/* The output looks better if we put 6 bytes on a line. */
info->bytes_per_line = 6;
/* Every S390 instruction is max 6 bytes long. */
memset (buffer, 0, 6);
status = info->read_memory_func (memaddr, buffer, 6, info);
if (status != 0)
{
for (bufsize = 0; bufsize < 6; bufsize++)
if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
break;
if (bufsize <= 0)
{
info->memory_error_func (status, memaddr, info);
return -1;
}
opsize = s390_insn_length (buffer);
status = opsize > bufsize;
}
else
{
bufsize = 6;
opsize = s390_insn_length (buffer);
}
if (status == 0)
{
const struct s390_opcode *op;
/* Find the "best match" in the opcode table. */
for (op = s390_opcodes + opc_index[buffer[0]];
op != s390_opcodes + s390_num_opcodes
&& op->opcode[0] == buffer[0];
op++)
{
if ((op->modes & current_arch_mask)
&& s390_insn_matches_opcode (buffer, op)
&& (opcode == NULL
|| opcode_mask_more_specific (op, opcode)))
opcode = op;
}
if (opcode != NULL)
{
/* The instruction is valid. Print it and return its size. */
s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
return opsize;
}
}
/* For code sections it makes sense to skip unknown instructions
according to their length bits. */
if (status == 0
&& option_use_insn_len_bits_p
&& info->section != NULL
&& (info->section->flags & SEC_CODE))
bytes_to_dump = opsize;
else
/* By default unknown instructions are printed as .long's/.short'
depending on how many bytes are available. */
bytes_to_dump = bufsize >= 4 ? 4 : bufsize;
if (bytes_to_dump == 0)
return 0;
/* Fall back to hex print. */
switch (bytes_to_dump)
{
case 4:
value = (unsigned int) buffer[0];
value = (value << 8) + (unsigned int) buffer[1];
value = (value << 8) + (unsigned int) buffer[2];
value = (value << 8) + (unsigned int) buffer[3];
info->fprintf_func (info->stream, ".long\t0x%08x", value);
return 4;
case 2:
value = (unsigned int) buffer[0];
value = (value << 8) + (unsigned int) buffer[1];
info->fprintf_func (info->stream, ".short\t0x%04x", value);
return 2;
default:
info->fprintf_func (info->stream, ".byte\t0x%02x",
(unsigned int) buffer[0]);
for (i = 1; i < bytes_to_dump; i++)
info->fprintf_func (info->stream, ",0x%02x",
(unsigned int) buffer[i]);
return bytes_to_dump;
}
return 0;
}
const disasm_options_t *
disassembler_options_s390 (void)
{
static disasm_options_t *opts = NULL;
if (opts == NULL)
{
size_t i, num_options = ARRAY_SIZE (options);
opts = XNEW (disasm_options_t);
opts->name = XNEWVEC (const char *, num_options + 1);
opts->description = XNEWVEC (const char *, num_options + 1);
for (i = 0; i < num_options; i++)
{
opts->name[i] = options[i].name;
opts->description[i] = _(options[i].description);
}
/* The array we return must be NULL terminated. */
opts->name[i] = NULL;
opts->description[i] = NULL;
}
return opts;
}
void
print_s390_disassembler_options (FILE *stream)
{
unsigned int i, max_len = 0;
fprintf (stream, _("\n\
The following S/390 specific disassembler options are supported for use\n\
with the -M switch (multiple options should be separated by commas):\n"));
for (i = 0; i < ARRAY_SIZE (options); i++)
{
unsigned int len = strlen (options[i].name);
if (max_len < len)
max_len = len;
}
for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
fprintf (stream, " %s%*c %s\n",
options[i].name,
(int)(max_len - strlen (options[i].name)), ' ',
_(options[i].description));
}