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[PATCH 2/6] S/390: Fix disassembler's treatment of signed/unsigned operands
- From: Andreas Arnez <arnez at linux dot vnet dot ibm dot com>
- To: binutils at sourceware dot org
- Cc: Martin Schwidefsky <schwidefsky at de dot ibm dot com>, Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>
- Date: Fri, 25 Jul 2014 19:01:49 +0200
- Subject: [PATCH 2/6] S/390: Fix disassembler's treatment of signed/unsigned operands
- Authentication-results: sourceware.org; auth=none
- References: <1406307713-7926-1-git-send-email-arnez at linux dot vnet dot ibm dot com>
Currently the S/390 disassembler relies on implementation-defined
behavior upon integer overflow and sometimes uses the "%i" printf
format for unsigned values. This patch intends to fix these.
opcodes/
* s390-dis.c (union operand_value): New.
(s390_extract_operand): Change return type to union operand_value.
Also avoid integer overflow in sign-extension.
(s390_print_insn_with_opcode): Adjust to changed return value from
s390_extract_operand(). Change "%i" printf format to "%u" for
unsigned values.
---
opcodes/s390-dis.c | 55 ++++++++++++++++++++++++++++++++++--------------------
1 file changed, 35 insertions(+), 20 deletions(-)
diff --git a/opcodes/s390-dis.c b/opcodes/s390-dis.c
index 444e7ae..47c449a 100644
--- a/opcodes/s390-dis.c
+++ b/opcodes/s390-dis.c
@@ -92,16 +92,23 @@ s390_insn_matches_opcode (const bfd_byte *buffer,
&& (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 unsigned int
+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;
@@ -123,15 +130,24 @@ s390_extract_operand (const bfd_byte *insn,
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. */
- if ((operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
- && (val & (1U << (operand->bits - 1))))
- val |= (-1U << (operand->bits - 1)) << 1;
+ /* 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
+ ret.u = val;
- /* Length x in an instructions has real length x + 1. */
- if (operand->flags & S390_OPERAND_LENGTH)
- val++;
- return val;
+ return ret;
}
/* Print the S390 instruction in BUFFER, assuming that it matches the
@@ -156,12 +172,12 @@ s390_print_insn_with_opcode (bfd_vma memaddr,
for (opindex = opcode->operands; *opindex != 0; opindex++)
{
const struct s390_operand *operand = s390_operands + *opindex;
- unsigned int value = s390_extract_operand (buffer, operand);
+ union operand_value val = s390_extract_operand (buffer, operand);
- if ((operand->flags & S390_OPERAND_INDEX) && value == 0)
+ if ((operand->flags & S390_OPERAND_INDEX) && val.u == 0)
continue;
if ((operand->flags & S390_OPERAND_BASE) &&
- value == 0 && separator == '(')
+ val.u == 0 && separator == '(')
{
separator = ',';
continue;
@@ -171,20 +187,19 @@ s390_print_insn_with_opcode (bfd_vma memaddr,
(*info->fprintf_func) (info->stream, "%c", separator);
if (operand->flags & S390_OPERAND_GPR)
- (*info->fprintf_func) (info->stream, "%%r%i", value);
+ (*info->fprintf_func) (info->stream, "%%r%u", val.u);
else if (operand->flags & S390_OPERAND_FPR)
- (*info->fprintf_func) (info->stream, "%%f%i", value);
+ (*info->fprintf_func) (info->stream, "%%f%u", val.u);
else if (operand->flags & S390_OPERAND_AR)
- (*info->fprintf_func) (info->stream, "%%a%i", value);
+ (*info->fprintf_func) (info->stream, "%%a%u", val.u);
else if (operand->flags & S390_OPERAND_CR)
- (*info->fprintf_func) (info->stream, "%%c%i", value);
+ (*info->fprintf_func) (info->stream, "%%c%u", val.u);
else if (operand->flags & S390_OPERAND_PCREL)
- (*info->print_address_func) (memaddr + (int)value + (int)value,
- info);
+ (*info->print_address_func) (memaddr + val.i + val.i, info);
else if (operand->flags & S390_OPERAND_SIGNED)
- (*info->fprintf_func) (info->stream, "%i", (int) value);
+ (*info->fprintf_func) (info->stream, "%i", val.i);
else
- (*info->fprintf_func) (info->stream, "%u", value);
+ (*info->fprintf_func) (info->stream, "%u", val.u);
if (operand->flags & S390_OPERAND_DISP)
{
--
1.8.4.2