This patch set mainly aims at improving the S/390 disassembler's
readability and also fixes some minor issues. S/390: Split disassembler routine into smaller functions S/390: Fix disassembler's treatment of signed/unsigned operands S/390: Fix off-by-one error in disassembler initialization S/390: Simplify opcode search loop in disassembler S/390: Drop function pointer dereferences in disassembler S/390: Various minor simplifications in disassembler
This commit is contained in:
Andreas Arnez
Nick Clifton
parent
cb417230fb
commit
9ace48f3d7
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@ -1,3 +1,30 @@
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2014-08-19 Andreas Arnez <arnez@linux.vnet.ibm.com>
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* s390-dis.c (s390_insn_length, s390_insn_matches_opcode)
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(s390_print_insn_with_opcode, opcode_mask_more_specific): New
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static functions, code was moved from...
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(print_insn_s390): ...here.
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(s390_extract_operand): Adjust comment. Change type of first
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parameter from 'unsigned char *' to 'const bfd_byte *'.
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(union operand_value): New.
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(s390_extract_operand): Change return type to union operand_value.
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Also avoid integer overflow in sign-extension.
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(s390_print_insn_with_opcode): Adjust to changed return value from
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s390_extract_operand(). Change "%i" printf format to "%u" for
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unsigned values.
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(init_disasm): Simplify initialization of opc_index[]. This also
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fixes an access after the last element of s390_opcodes[].
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(print_insn_s390): Simplify the opcode search loop.
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Check architecture mask against all searched opcodes, not just the
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first matching one.
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(s390_print_insn_with_opcode): Drop function pointer dereferences
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without effect.
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(print_insn_s390): Likewise.
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(s390_insn_length): Simplify formula for return value.
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(s390_print_insn_with_opcode): Avoid special handling for the
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separator before the first operand. Use new local variable
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'flags' in place of 'operand->flags'.
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2014-08-14 Mike Frysinger <vapier@gentoo.org>
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* bfin-dis.c (struct private): Change int's to bfd_boolean's.
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@ -35,19 +35,15 @@ static int current_arch_mask = 0;
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static void
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init_disasm (struct disassemble_info *info)
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{
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const struct s390_opcode *opcode;
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const struct s390_opcode *opcode_end;
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int i;
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const char *p;
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memset (opc_index, 0, sizeof (opc_index));
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opcode_end = s390_opcodes + s390_num_opcodes;
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for (opcode = s390_opcodes; opcode < opcode_end; opcode++)
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{
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opc_index[(int) opcode->opcode[0]] = opcode - s390_opcodes;
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while ((opcode < opcode_end) &&
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(opcode[1].opcode[0] == opcode->opcode[0]))
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opcode++;
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}
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/* Reverse order, such that each opc_index ends up pointing to the
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first matching entry instead of the last. */
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for (i = s390_num_opcodes; i--; )
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opc_index[s390_opcodes[i].opcode[0]] = i;
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for (p = info->disassembler_options; p != NULL; )
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{
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@ -69,15 +65,46 @@ init_disasm (struct disassemble_info *info)
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init_flag = 1;
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}
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/* Derive the length of an instruction from its first byte. */
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static inline int
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s390_insn_length (const bfd_byte *buffer)
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{
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/* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6. */
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return ((buffer[0] >> 6) + 3) & ~1U;
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}
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/* Match the instruction in BUFFER against the given OPCODE, excluding
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the first byte. */
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static inline int
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s390_insn_matches_opcode (const bfd_byte *buffer,
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const struct s390_opcode *opcode)
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{
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return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
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&& (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
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&& (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
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&& (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
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&& (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
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}
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union operand_value
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{
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int i;
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unsigned int u;
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};
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/* Extracts an operand value from an instruction. */
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/* We do not perform the shift operation for larl-type address
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operands here since that would lead to an overflow of the 32 bit
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integer value. Instead the shift operation is done when printing
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the operand in print_insn_s390. */
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the operand. */
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static inline unsigned int
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s390_extract_operand (unsigned char *insn, const struct s390_operand *operand)
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static inline union operand_value
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s390_extract_operand (const bfd_byte *insn,
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const struct s390_operand *operand)
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{
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union operand_value ret;
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unsigned int val;
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int bits;
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@ -99,15 +126,97 @@ s390_extract_operand (unsigned char *insn, const struct s390_operand *operand)
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if (operand->bits == 20 && operand->shift == 20)
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val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
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/* Sign extend value if the operand is signed or pc relative. */
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if ((operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
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&& (val & (1U << (operand->bits - 1))))
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val |= (-1U << (operand->bits - 1)) << 1;
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/* Sign extend value if the operand is signed or pc relative. Avoid
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integer overflows. */
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if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
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{
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unsigned int m = 1U << (operand->bits - 1);
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/* Length x in an instructions has real length x + 1. */
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if (operand->flags & S390_OPERAND_LENGTH)
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val++;
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return val;
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if (val >= m)
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ret.i = (int) (val - m) - 1 - (int) (m - 1U);
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else
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ret.i = (int) val;
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}
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else if (operand->flags & S390_OPERAND_LENGTH)
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/* Length x in an instruction has real length x + 1. */
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ret.u = val + 1;
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else
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ret.u = val;
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return ret;
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}
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/* Print the S390 instruction in BUFFER, assuming that it matches the
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given OPCODE. */
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static void
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s390_print_insn_with_opcode (bfd_vma memaddr,
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struct disassemble_info *info,
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const bfd_byte *buffer,
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const struct s390_opcode *opcode)
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{
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const unsigned char *opindex;
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char separator;
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/* Mnemonic. */
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info->fprintf_func (info->stream, "%s", opcode->name);
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/* Operands. */
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separator = '\t';
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for (opindex = opcode->operands; *opindex != 0; opindex++)
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{
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const struct s390_operand *operand = s390_operands + *opindex;
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union operand_value val = s390_extract_operand (buffer, operand);
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unsigned long flags = operand->flags;
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if ((flags & S390_OPERAND_INDEX) && val.u == 0)
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continue;
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if ((flags & S390_OPERAND_BASE) &&
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val.u == 0 && separator == '(')
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{
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separator = ',';
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continue;
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}
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info->fprintf_func (info->stream, "%c", separator);
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if (flags & S390_OPERAND_GPR)
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info->fprintf_func (info->stream, "%%r%u", val.u);
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else if (flags & S390_OPERAND_FPR)
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info->fprintf_func (info->stream, "%%f%u", val.u);
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else if (flags & S390_OPERAND_AR)
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info->fprintf_func (info->stream, "%%a%u", val.u);
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else if (flags & S390_OPERAND_CR)
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info->fprintf_func (info->stream, "%%c%u", val.u);
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else if (flags & S390_OPERAND_PCREL)
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info->print_address_func (memaddr + val.i + val.i, info);
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else if (flags & S390_OPERAND_SIGNED)
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info->fprintf_func (info->stream, "%i", val.i);
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else
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info->fprintf_func (info->stream, "%u", val.u);
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if (flags & S390_OPERAND_DISP)
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separator = '(';
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else if (flags & S390_OPERAND_BASE)
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{
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info->fprintf_func (info->stream, ")");
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separator = ',';
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}
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else
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separator = ',';
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}
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}
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/* Check whether opcode A's mask is more specific than that of B. */
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static int
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opcode_mask_more_specific (const struct s390_opcode *a,
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const struct s390_opcode *b)
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{
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return (((int) a->mask[0] + a->mask[1] + a->mask[2]
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+ a->mask[3] + a->mask[4] + a->mask[5])
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> ((int) b->mask[0] + b->mask[1] + b->mask[2]
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+ b->mask[3] + b->mask[4] + b->mask[5]));
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}
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/* Print a S390 instruction. */
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@ -116,11 +225,9 @@ int
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print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
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{
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bfd_byte buffer[6];
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const struct s390_opcode *opcode;
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const struct s390_opcode *opcode_end;
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const struct s390_opcode *opcode = NULL;
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unsigned int value;
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int status, opsize, bufsize;
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char separator;
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if (init_flag == 0)
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init_disasm (info);
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@ -130,156 +237,72 @@ print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
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/* Every S390 instruction is max 6 bytes long. */
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memset (buffer, 0, 6);
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status = (*info->read_memory_func) (memaddr, buffer, 6, info);
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status = info->read_memory_func (memaddr, buffer, 6, info);
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if (status != 0)
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{
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for (bufsize = 0; bufsize < 6; bufsize++)
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if ((*info->read_memory_func) (memaddr, buffer, bufsize + 1, info) != 0)
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if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
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break;
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if (bufsize <= 0)
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{
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(*info->memory_error_func) (status, memaddr, info);
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info->memory_error_func (status, memaddr, info);
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return -1;
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}
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/* Opsize calculation looks strange but it works
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00xxxxxx -> 2 bytes, 01xxxxxx/10xxxxxx -> 4 bytes,
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11xxxxxx -> 6 bytes. */
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opsize = ((((buffer[0] >> 6) + 1) >> 1) + 1) << 1;
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opsize = s390_insn_length (buffer);
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status = opsize > bufsize;
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}
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else
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{
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bufsize = 6;
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opsize = ((((buffer[0] >> 6) + 1) >> 1) + 1) << 1;
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opsize = s390_insn_length (buffer);
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}
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if (status == 0)
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{
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const struct s390_opcode *op;
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/* Find the first match in the opcode table. */
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opcode_end = s390_opcodes + s390_num_opcodes;
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for (opcode = s390_opcodes + opc_index[(int) buffer[0]];
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(opcode < opcode_end) && (buffer[0] == opcode->opcode[0]);
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opcode++)
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/* Find the "best match" in the opcode table. */
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for (op = s390_opcodes + opc_index[buffer[0]];
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op != s390_opcodes + s390_num_opcodes
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&& op->opcode[0] == buffer[0];
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op++)
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{
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const struct s390_operand *operand;
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const unsigned char *opindex;
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/* Check architecture. */
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if (!(opcode->modes & current_arch_mask))
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continue;
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/* Check signature of the opcode. */
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if ((buffer[1] & opcode->mask[1]) != opcode->opcode[1]
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|| (buffer[2] & opcode->mask[2]) != opcode->opcode[2]
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|| (buffer[3] & opcode->mask[3]) != opcode->opcode[3]
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|| (buffer[4] & opcode->mask[4]) != opcode->opcode[4]
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|| (buffer[5] & opcode->mask[5]) != opcode->opcode[5])
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continue;
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/* Advance to an opcode with a more specific mask. */
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for (op = opcode + 1; op < opcode_end; op++)
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{
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if ((buffer[0] & op->mask[0]) != op->opcode[0])
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break;
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if ((buffer[1] & op->mask[1]) != op->opcode[1]
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|| (buffer[2] & op->mask[2]) != op->opcode[2]
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|| (buffer[3] & op->mask[3]) != op->opcode[3]
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|| (buffer[4] & op->mask[4]) != op->opcode[4]
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|| (buffer[5] & op->mask[5]) != op->opcode[5])
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continue;
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if (((int)opcode->mask[0] + opcode->mask[1] +
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opcode->mask[2] + opcode->mask[3] +
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opcode->mask[4] + opcode->mask[5]) <
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((int)op->mask[0] + op->mask[1] +
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op->mask[2] + op->mask[3] +
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op->mask[4] + op->mask[5]))
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opcode = op;
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}
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/* The instruction is valid. */
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if (opcode->operands[0] != 0)
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(*info->fprintf_func) (info->stream, "%s\t", opcode->name);
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else
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(*info->fprintf_func) (info->stream, "%s", opcode->name);
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/* Extract the operands. */
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separator = 0;
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for (opindex = opcode->operands; *opindex != 0; opindex++)
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{
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operand = s390_operands + *opindex;
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value = s390_extract_operand (buffer, operand);
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if ((operand->flags & S390_OPERAND_INDEX) && value == 0)
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continue;
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if ((operand->flags & S390_OPERAND_BASE) &&
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value == 0 && separator == '(')
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{
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separator = ',';
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continue;
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}
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if (separator)
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(*info->fprintf_func) (info->stream, "%c", separator);
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if (operand->flags & S390_OPERAND_GPR)
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(*info->fprintf_func) (info->stream, "%%r%i", value);
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else if (operand->flags & S390_OPERAND_FPR)
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(*info->fprintf_func) (info->stream, "%%f%i", value);
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else if (operand->flags & S390_OPERAND_AR)
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(*info->fprintf_func) (info->stream, "%%a%i", value);
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else if (operand->flags & S390_OPERAND_CR)
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(*info->fprintf_func) (info->stream, "%%c%i", value);
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else if (operand->flags & S390_OPERAND_PCREL)
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(*info->print_address_func) (memaddr + (int)value + (int)value,
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info);
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else if (operand->flags & S390_OPERAND_SIGNED)
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(*info->fprintf_func) (info->stream, "%i", (int) value);
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else
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(*info->fprintf_func) (info->stream, "%u", value);
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if (operand->flags & S390_OPERAND_DISP)
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{
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separator = '(';
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}
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else if (operand->flags & S390_OPERAND_BASE)
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{
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(*info->fprintf_func) (info->stream, ")");
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separator = ',';
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}
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else
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separator = ',';
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}
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/* Found instruction, printed it, return its size. */
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return opsize;
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if ((op->modes & current_arch_mask)
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&& s390_insn_matches_opcode (buffer, op)
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&& (opcode == NULL
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|| opcode_mask_more_specific (op, opcode)))
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opcode = op;
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}
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/* No matching instruction found, fall through to hex print. */
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}
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if (opcode != NULL)
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{
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/* The instruction is valid. Print it and return its size. */
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s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
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return opsize;
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}
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/* Fall back to hex print. */
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if (bufsize >= 4)
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{
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value = (unsigned int) buffer[0];
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value = (value << 8) + (unsigned int) buffer[1];
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value = (value << 8) + (unsigned int) buffer[2];
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value = (value << 8) + (unsigned int) buffer[3];
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(*info->fprintf_func) (info->stream, ".long\t0x%08x", value);
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info->fprintf_func (info->stream, ".long\t0x%08x", value);
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return 4;
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}
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else if (bufsize >= 2)
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{
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value = (unsigned int) buffer[0];
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value = (value << 8) + (unsigned int) buffer[1];
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(*info->fprintf_func) (info->stream, ".short\t0x%04x", value);
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info->fprintf_func (info->stream, ".short\t0x%04x", value);
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return 2;
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}
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else
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{
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value = (unsigned int) buffer[0];
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(*info->fprintf_func) (info->stream, ".byte\t0x%02x", value);
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info->fprintf_func (info->stream, ".byte\t0x%02x", value);
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return 1;
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}
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}
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